false2023FY0001771910P5YP3Y5P16M22DP28M22Dhttp://fasb.org/us-gaap/2023#CostsAndExpenseshttp://fasb.org/us-gaap/2023#CostsAndExpensesP2Y00017719102023-01-012023-12-3100017719102023-06-30iso4217:USD00017719102024-03-01xbrli:shares00017719102023-12-3100017719102022-12-31iso4217:CHFxbrli:shares00017719102022-01-012022-12-31iso4217:USDxbrli:shares0001771910us-gaap:CommonStockMember2021-12-310001771910us-gaap:AdditionalPaidInCapitalMember2021-12-310001771910us-gaap:TreasuryStockCommonMember2021-12-310001771910us-gaap:AccumulatedOtherComprehensiveIncomeMember2021-12-310001771910us-gaap:RetainedEarningsMember2021-12-3100017719102021-12-310001771910us-gaap:RetainedEarningsMember2022-01-012022-12-310001771910us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-01-012022-12-310001771910adc:OtherThanAtTheMarketFacilityMemberus-gaap:CommonStockMember2022-01-012022-12-310001771910adc:OtherThanAtTheMarketFacilityMemberus-gaap:TreasuryStockCommonMember2022-01-012022-12-310001771910adc:OtherThanAtTheMarketFacilityMember2022-01-012022-12-310001771910us-gaap:CommonStockMemberadc:AtTheMarketFacilityMember2022-01-012022-12-310001771910us-gaap:AdditionalPaidInCapitalMemberadc:AtTheMarketFacilityMember2022-01-012022-12-310001771910adc:AtTheMarketFacilityMemberus-gaap:TreasuryStockCommonMember2022-01-012022-12-310001771910adc:AtTheMarketFacilityMember2022-01-012022-12-310001771910us-gaap:AdditionalPaidInCapitalMember2022-01-012022-12-310001771910us-gaap:TreasuryStockCommonMember2022-01-012022-12-310001771910us-gaap:CommonStockMember2022-01-012022-12-310001771910us-gaap:CommonStockMember2022-12-310001771910us-gaap:AdditionalPaidInCapitalMember2022-12-310001771910us-gaap:TreasuryStockCommonMember2022-12-310001771910us-gaap:AccumulatedOtherComprehensiveIncomeMember2022-12-310001771910us-gaap:RetainedEarningsMember2022-12-310001771910us-gaap:RetainedEarningsMember2023-01-012023-12-310001771910us-gaap:AccumulatedOtherComprehensiveIncomeMember2023-01-012023-12-310001771910us-gaap:AdditionalPaidInCapitalMember2023-01-012023-12-310001771910us-gaap:TreasuryStockCommonMember2023-01-012023-12-310001771910us-gaap:CommonStockMember2023-12-310001771910us-gaap:AdditionalPaidInCapitalMember2023-12-310001771910us-gaap:TreasuryStockCommonMember2023-12-310001771910us-gaap:AccumulatedOtherComprehensiveIncomeMember2023-12-310001771910us-gaap:RetainedEarningsMember2023-12-310001771910adc:SeniorSecuredTermLoanMember2023-01-012023-12-310001771910adc:SeniorSecuredTermLoanMember2022-01-012022-12-310001771910adc:ConvertibleLoansMember2023-01-012023-12-310001771910adc:ConvertibleLoansMember2022-01-012022-12-310001771910adc:DeerfieldWarrantsMember2023-01-012023-12-310001771910adc:DeerfieldWarrantsMember2022-01-012022-12-310001771910adc:SeniorSecuredTermLoanMember2023-01-012023-12-310001771910adc:SeniorSecuredTermLoanMember2022-01-012022-12-31adc:subsidiary0001771910adc:TopFourCustomersMemberus-gaap:CustomerConcentrationRiskMemberus-gaap:FinanceReceivablesMember2023-01-012023-12-31xbrli:pure0001771910adc:TopFourCustomersMemberus-gaap:CustomerConcentrationRiskMemberus-gaap:FinanceReceivablesMember2022-01-012022-12-310001771910currency:GBP2023-12-310001771910currency:GBP2022-12-310001771910currency:GBP2023-01-012023-12-310001771910currency:GBP2022-01-012022-12-310001771910srt:MinimumMember2023-01-012023-12-310001771910srt:MaximumMember2023-01-012023-12-310001771910us-gaap:LeaseholdImprovementsMembersrt:MinimumMember2023-12-310001771910us-gaap:LeaseholdImprovementsMembersrt:MaximumMember2023-12-310001771910adc:LaboratoryEquipmentMember2023-12-310001771910us-gaap:OfficeEquipmentMember2023-12-310001771910adc:HardwareAndSoftwareMember2023-12-31adc:segment0001771910country:CH2023-12-310001771910country:CH2022-12-310001771910country:GB2023-12-310001771910country:GB2022-12-310001771910country:US2023-12-310001771910country:US2022-12-310001771910us-gaap:FairValueInputsLevel1Member2023-12-310001771910us-gaap:FairValueInputsLevel2Member2023-12-310001771910us-gaap:FairValueInputsLevel3Member2023-12-310001771910us-gaap:FairValueInputsLevel1Member2022-12-310001771910us-gaap:FairValueInputsLevel2Member2022-12-310001771910us-gaap:FairValueInputsLevel3Member2022-12-310001771910us-gaap:LeaseholdImprovementsMember2023-12-310001771910us-gaap:LeaseholdImprovementsMember2022-12-310001771910adc:LaboratoryEquipmentMember2022-12-310001771910us-gaap:OfficeEquipmentMember2022-12-310001771910adc:HardwareAndSoftwareMember2022-12-310001771910country:CH2023-09-010001771910country:GB2023-01-300001771910stpr:NJ2022-09-300001771910adc:OverlandADCTBioPharmaCYLimitedMember2020-12-142020-12-14adc:product0001771910adc:OverlandPharmaceuticalsMember2020-12-142020-12-140001771910adc:OverlandADCTBioPharmaMemberadc:OverlandPharmaceuticalsMember2020-12-140001771910adc:OverlandADCTBioPharmaMember2020-12-140001771910adc:OverlandADCTBioPharmaMember2020-12-140001771910adc:OverlandADCTBioPharmaCYLimitedMember2021-12-310001771910adc:OverlandADCTBioPharmaCYLimitedMember2022-01-012022-12-310001771910adc:OverlandADCTBioPharmaCYLimitedMember2022-12-310001771910adc:OverlandADCTBioPharmaCYLimitedMember2023-01-012023-12-310001771910adc:OverlandADCTBioPharmaCYLimitedMember2023-12-310001771910us-gaap:DomesticCountryMember2023-12-310001771910us-gaap:DomesticCountryMember2022-12-310001771910us-gaap:StateAndLocalJurisdictionMember2023-12-310001771910us-gaap:StateAndLocalJurisdictionMember2022-12-310001771910us-gaap:ResearchMember2023-12-310001771910us-gaap:ForeignCountryMember2023-12-310001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMember2022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMember2022-08-152022-08-150001771910adc:InterestRatePeriodOneMemberadc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMemberadc:SecuredOvernightFinancingRateSOFRMember2022-08-152022-08-150001771910adc:InterestRatePeriodOneMemberadc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMemberus-gaap:BaseRateMember2022-08-152022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMemberadc:SecuredOvernightFinancingRateSOFRMemberadc:InterestRatePeriodTwoMember2022-08-152022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMemberadc:InterestRatePeriodTwoMemberus-gaap:BaseRateMember2022-08-152022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMemberadc:SecuredOvernightFinancingRateSOFRMember2022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMembersrt:MinimumMemberus-gaap:LineOfCreditMember2022-08-152022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMembersrt:MaximumMemberus-gaap:LineOfCreditMember2022-08-152022-08-150001771910adc:LoanAgreementWarrantsMember2022-08-1500017719102022-08-152022-08-150001771910adc:LoanAgreementWarrantsMemberus-gaap:MeasurementInputExercisePriceMember2022-08-150001771910adc:LoanAgreementWarrantsMemberus-gaap:MeasurementInputSharePriceMember2022-08-150001771910adc:LoanAgreementWarrantsMemberus-gaap:MeasurementInputRiskFreeInterestRateMember2022-08-150001771910adc:LoanAgreementWarrantsMemberus-gaap:MeasurementInputPriceVolatilityMember2022-08-150001771910adc:LoanAgreementWarrantsMemberus-gaap:MeasurementInputExpectedTermMember2022-08-150001771910adc:LoanAgreementWarrantsMemberadc:MeasurementInputDividendYieldMember2022-08-150001771910adc:LoanAgreementWarrantsMemberadc:MeasurementInputValueMember2022-08-1500017719102022-08-150001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMember2023-01-012023-12-310001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMember2022-01-012022-12-310001771910adc:LoanAgreementMemberus-gaap:SecuredDebtMemberus-gaap:LineOfCreditMember2023-12-310001771910adc:LoanAgreementMember2023-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.Memberus-gaap:ConvertibleDebtMember2020-04-240001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:ConvertibleDebtMember2020-04-240001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:ConvertibleDebtMember2020-04-240001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberadc:DebtInstrumentConversionPercentOfIPOPriceMemberus-gaap:ConvertibleDebtMember2020-04-242020-04-240001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberadc:DebtInstrumentConversionPercentOfIPOPriceMemberus-gaap:ConvertibleDebtMember2020-04-242020-04-240001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:ConvertibleDebtMemberadc:DebtInstrumentConversionVolumeWeightedAveragePriceMember2020-04-242020-04-240001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.Memberus-gaap:ConvertibleDebtMember2022-08-152022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:ConvertibleDebtMember2023-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:ConvertibleDebtMember2023-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMember2022-01-012022-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMember2022-01-012022-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.Member2022-08-152022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMember2021-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMember2022-08-152022-08-150001771910us-gaap:IPOMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:MeasurementInputExercisePriceMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:MeasurementInputConversionPriceMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:MeasurementInputSharePriceMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:MeasurementInputRiskFreeInterestRateMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:MeasurementInputPriceVolatilityMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:MeasurementInputExpectedTermMember2022-08-15utr:M0001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberadc:MeasurementInputDividendYieldMember2022-08-150001771910adc:MeasurementInputRecoveryRateMemberadc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberadc:MeasurementInputImpliedBondYiedMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:MeasurementInputExercisePriceMember2022-08-150001771910us-gaap:MeasurementInputConversionPriceMemberadc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:MeasurementInputSharePriceMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:MeasurementInputRiskFreeInterestRateMember2022-08-150001771910us-gaap:MeasurementInputPriceVolatilityMemberadc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:MeasurementInputExpectedTermMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberadc:MeasurementInputDividendYieldMember2022-08-150001771910adc:MeasurementInputRecoveryRateMemberadc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMember2022-08-150001771910adc:MeasurementInputImpliedBondYiedMemberadc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMember2022-08-150001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.Memberus-gaap:ConvertibleDebtMember2020-04-242020-04-240001771910adc:DeerfieldWarrantsMember2022-08-152022-08-150001771910adc:DeerfieldWarrantsMemberadc:WarrantsTrancheOneMember2022-08-152022-08-150001771910adc:DeerfieldWarrantsMemberadc:WarrantsTrancheOneMember2022-08-150001771910adc:DeerfieldWarrantsMemberadc:WarrantsTrancheTwoMember2022-08-152022-08-150001771910adc:DeerfieldWarrantsMemberadc:WarrantsTrancheTwoMember2022-08-150001771910adc:DeerfieldWarrantsMember2022-08-150001771910adc:DeerfieldWarrantsMember2023-12-310001771910adc:DeerfieldWarrantsMember2022-12-310001771910adc:DeerfieldWarrantsMembersrt:MinimumMemberus-gaap:MeasurementInputExercisePriceMember2023-12-310001771910adc:DeerfieldWarrantsMembersrt:MaximumMemberus-gaap:MeasurementInputExercisePriceMember2023-12-310001771910adc:DeerfieldWarrantsMembersrt:MinimumMemberus-gaap:MeasurementInputExercisePriceMember2022-12-310001771910adc:DeerfieldWarrantsMembersrt:MaximumMemberus-gaap:MeasurementInputExercisePriceMember2022-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputSharePriceMember2023-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputSharePriceMember2022-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputRiskFreeInterestRateMember2023-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputRiskFreeInterestRateMember2022-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputPriceVolatilityMember2023-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputPriceVolatilityMember2022-12-310001771910adc:DeerfieldWarrantsMemberadc:MeasurementInputDividendYieldMember2023-12-310001771910adc:DeerfieldWarrantsMemberadc:MeasurementInputDividendYieldMember2022-12-310001771910adc:DeerfieldWarrantsMemberadc:MeasurementInputValueMembersrt:MinimumMember2023-12-310001771910adc:DeerfieldWarrantsMemberadc:MeasurementInputValueMembersrt:MaximumMember2023-12-310001771910adc:DeerfieldWarrantsMemberadc:MeasurementInputValueMembersrt:MinimumMember2022-12-310001771910adc:DeerfieldWarrantsMemberadc:MeasurementInputValueMembersrt:MaximumMember2022-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputExpectedTermMember2023-12-310001771910adc:DeerfieldWarrantsMemberus-gaap:MeasurementInputExpectedTermMember2022-12-3100017719102021-08-252021-08-250001771910adc:ZYNLONTAMember2021-08-252021-08-250001771910adc:CamiMember2021-08-252021-08-250001771910srt:MaximumMember2021-08-252021-08-250001771910srt:MaximumMember2022-01-012022-12-310001771910srt:MinimumMember2021-08-252021-08-250001771910srt:MinimumMember2022-01-012022-12-310001771910srt:MinimumMember2023-12-310001771910srt:MaximumMember2023-12-310001771910srt:MinimumMember2022-12-310001771910srt:MaximumMember2022-12-3100017719102021-01-012021-12-3100017719102021-08-250001771910country:US2023-01-012023-12-310001771910country:US2022-01-012022-12-310001771910us-gaap:ForeignPlanMember2023-01-012023-12-310001771910us-gaap:ForeignPlanMember2022-01-012022-12-31adc:age0001771910srt:MedianMember2023-01-012023-12-31adc:participantiso4217:CHF00017719102022-09-052022-09-0500017719102022-10-012022-12-3100017719102021-06-042021-06-0400017719102022-09-062022-09-0600017719102022-09-060001771910us-gaap:ProductMember2023-01-012023-12-310001771910us-gaap:ProductMember2022-01-012022-12-310001771910adc:LicenseRevenuesMember2023-01-012023-12-310001771910adc:LicenseRevenuesMember2022-01-012022-12-310001771910adc:RoyaltyRevenueMember2023-01-012023-12-310001771910adc:RoyaltyRevenueMember2022-01-012022-12-310001771910country:US2023-01-012023-12-310001771910country:US2022-01-012022-12-310001771910us-gaap:EMEAMember2023-01-012023-12-310001771910us-gaap:EMEAMember2022-01-012022-12-310001771910country:JP2023-01-012023-12-310001771910country:JP2022-01-012022-12-310001771910adc:DiscardedDrugRebateMember2021-12-310001771910adc:OtherAdjustmentsMember2021-12-310001771910adc:DiscardedDrugRebateMember2022-01-012022-12-310001771910adc:OtherAdjustmentsMember2022-01-012022-12-310001771910adc:DiscardedDrugRebateMember2022-12-310001771910adc:OtherAdjustmentsMember2022-12-310001771910adc:DiscardedDrugRebateMember2023-01-012023-12-310001771910adc:OtherAdjustmentsMember2023-01-012023-12-310001771910adc:DiscardedDrugRebateMember2023-12-310001771910adc:OtherAdjustmentsMember2023-12-310001771910us-gaap:CustomerConcentrationRiskMemberadc:McKessonMemberus-gaap:SalesRevenueNetMember2023-01-012023-12-310001771910us-gaap:CustomerConcentrationRiskMemberadc:McKessonMemberus-gaap:SalesRevenueNetMember2022-01-012022-12-310001771910us-gaap:CustomerConcentrationRiskMemberus-gaap:SalesRevenueNetMemberadc:AmerisourceBergenCorporationMember2023-01-012023-12-310001771910us-gaap:CustomerConcentrationRiskMemberus-gaap:SalesRevenueNetMemberadc:AmerisourceBergenCorporationMember2022-01-012022-12-310001771910us-gaap:CustomerConcentrationRiskMemberus-gaap:SalesRevenueNetMemberadc:CardinalHealthMember2023-01-012023-12-310001771910us-gaap:CustomerConcentrationRiskMemberus-gaap:SalesRevenueNetMemberadc:CardinalHealthMember2022-01-012022-12-3100017719102022-01-182022-01-1800017719102022-07-082022-07-080001771910adc:LoanAgreementMember2023-01-012023-12-310001771910adc:LoanAgreementMember2022-01-012022-12-310001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheOneMemberus-gaap:ConvertibleDebtMember2020-05-190001771910adc:FacilityAgreementWithDeerfieldPartnersL.P.TrancheTwoMemberus-gaap:ConvertibleDebtMember2020-05-190001771910adc:A2019EquityIncentivePlanMember2019-11-300001771910us-gaap:StockCompensationPlanMemberadc:A2019EquityIncentivePlanMember2019-11-300001771910adc:A2019EquityIncentivePlanMemberus-gaap:EmployeeStockOptionMember2023-03-222023-03-220001771910adc:A2019EquityIncentivePlanMemberus-gaap:RestrictedStockUnitsRSUMember2023-03-222023-03-220001771910adc:A2019EquityIncentivePlanMember2023-01-012023-12-310001771910adc:A2019EquityIncentivePlanMember2022-01-012022-12-310001771910adc:ConditionalShareCapitalPlanMember2019-11-300001771910adc:ConditionalShareCapitalPlanMemberus-gaap:RestrictedStockUnitsRSUMember2023-12-062023-12-060001771910us-gaap:StockCompensationPlanMemberadc:ConditionalShareCapitalPlanMember2023-12-062023-12-060001771910adc:ConditionalShareCapitalPlanMember2023-12-310001771910adc:ConditionalShareCapitalPlanMember2023-01-012023-12-310001771910adc:InducementPlanMember2023-12-310001771910adc:EquityExchangeProgramMember2023-03-062023-03-060001771910srt:MinimumMemberadc:EquityExchangeProgramMember2023-03-062023-03-060001771910srt:MaximumMemberadc:EquityExchangeProgramMember2023-03-062023-03-060001771910adc:EmployeeStockOptionExchangeMemberadc:EquityExchangeProgramMember2023-01-012023-12-310001771910adc:EmployeeStockOptionExchangeMemberadc:EquityExchangeProgramMember2023-03-062023-03-060001771910us-gaap:EmployeeStockOptionMember2019-11-012019-11-300001771910us-gaap:StockCompensationPlanMember2023-01-012023-12-310001771910us-gaap:StockCompensationPlanMember2022-01-012022-12-310001771910us-gaap:EmployeeStockOptionMember2023-01-012023-12-310001771910srt:MinimumMemberus-gaap:EmployeeStockOptionMember2023-12-310001771910srt:MaximumMemberus-gaap:EmployeeStockOptionMember2023-12-310001771910srt:MinimumMemberus-gaap:EmployeeStockOptionMember2022-12-310001771910srt:MaximumMemberus-gaap:EmployeeStockOptionMember2022-12-310001771910srt:MinimumMemberus-gaap:EmployeeStockOptionMember2023-01-012023-12-310001771910srt:MaximumMemberus-gaap:EmployeeStockOptionMember2023-01-012023-12-310001771910srt:MinimumMemberus-gaap:EmployeeStockOptionMember2022-01-012022-12-310001771910srt:MaximumMemberus-gaap:EmployeeStockOptionMember2022-01-012022-12-310001771910us-gaap:EmployeeStockOptionMember2022-01-012022-12-310001771910adc:EmployeeStockOptionExchangeMembersrt:MinimumMember2023-01-012023-12-310001771910adc:EmployeeStockOptionExchangeMembersrt:MaximumMember2023-01-012023-12-310001771910adc:EmployeeStockOptionExchangeMember2023-01-012023-12-310001771910adc:A2019EquityIncentivePlanMembersrt:MinimumMemberus-gaap:RestrictedStockUnitsRSUMember2019-11-012019-11-300001771910adc:A2019EquityIncentivePlanMembersrt:MaximumMemberus-gaap:RestrictedStockUnitsRSUMember2019-11-012019-11-300001771910adc:A2019EquityIncentivePlanMemberus-gaap:RestrictedStockUnitsRSUMember2023-01-012023-12-310001771910adc:A2019EquityIncentivePlanMemberus-gaap:RestrictedStockUnitsRSUMember2022-01-012022-12-310001771910us-gaap:RestrictedStockUnitsRSUMember2021-12-310001771910us-gaap:RestrictedStockUnitsRSUMember2022-01-012022-12-310001771910us-gaap:RestrictedStockUnitsRSUMember2022-12-310001771910us-gaap:RestrictedStockUnitsRSUMember2023-01-012023-12-310001771910us-gaap:RestrictedStockUnitsRSUMember2023-12-310001771910us-gaap:RestrictedStockUnitsRSUMember2023-12-062023-12-060001771910us-gaap:RestrictedStockUnitsRSUMember2023-03-222023-03-220001771910us-gaap:EmployeeStockMemberadc:A2022EmployeeStockPurchasePlanMember2022-06-012022-06-300001771910adc:A2022EmployeeStockPurchasePlanMember2023-01-012023-12-310001771910us-gaap:EmployeeStockMember2022-01-012022-12-310001771910us-gaap:EmployeeStockOptionMemberadc:A2019EquityIncentivePlanMember2023-01-012023-12-310001771910us-gaap:EmployeeStockOptionMemberadc:A2019EquityIncentivePlanMember2022-01-012022-12-310001771910adc:A2019EquityIncentivePlanMemberus-gaap:RestrictedStockUnitsRSUMember2023-01-012023-12-310001771910adc:A2019EquityIncentivePlanMemberus-gaap:RestrictedStockUnitsRSUMember2022-01-012022-12-310001771910adc:ConditionalShareCapitalPlanMember2023-01-012023-12-310001771910adc:ConditionalShareCapitalPlanMember2022-01-012022-12-310001771910us-gaap:WarrantMember2023-01-012023-12-310001771910us-gaap:WarrantMember2022-01-012022-12-310001771910adc:A2022EmployeeStockPurchasePlanMember2023-01-012023-12-310001771910adc:A2022EmployeeStockPurchasePlanMember2022-01-012022-12-3100017719102023-10-012023-12-31

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

(Mark One)

Commission File Number: 001-39071

ADC Therapeutics SA
(Exact name of registrant as specified in its charter)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐          No ☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐    No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days. Yes ☒          No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒          No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to § 240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐          No ☒

The aggregate market value of the voting and non-voting common equity held by non-affiliates, based on the closing price of the common shares on The New York Stock Exchange, as of the last business day of the registrant’s most recently completed second fiscal quarter was approximately $153.4 million.

As of March 1, 2024, the number of common shares outstanding was 82,529,549.

DOCUMENTS INCORPORATED BY REFERENCE: None

Unless otherwise indicated or the context otherwise requires, all references in this Annual Report to “ADC Therapeutics,” “ADCT,” the “Company,” “we,” “our,” “ours,” “us” or similar terms refer to ADC Therapeutics SA and its consolidated subsidiaries.

We own various trademark registrations and applications, and unregistered trademarks, including ADC Therapeutics, ADCT, ZYNLONTA and our corporate logo. All other trade names, trademarks and service marks of other companies appearing in this Annual Report are the property of their respective owners. Solely for convenience, the trademarks and trade names in this Annual Report may be referred to without the ® and ™ symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto. We do not intend to use or display other companies’ trademarks and trade names to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

This Annual Report contains industry, market and competitive position data that are based on general and industry publications, surveys and studies conducted by third parties, some of which may not be publicly available, and our own internal estimates and research. Third-party publications, surveys and studies generally state that they have obtained information from sources believed to be reliable, but do not guarantee the accuracy and completeness of such information. These data involve a number of assumptions and limitations and contain projections and estimates of the future performance of the industries in which we operate that are subject to a high degree of uncertainty.

This Annual Report contains statements that constitute forward-looking statements. All statements other than statements of historical facts contained in this Annual Report, including statements regarding our future catalysts, results of operations and financial position, business and commercial strategy, market opportunities, products and product candidates, research pipeline, ongoing and planned preclinical studies and clinical trials, regulatory submissions and approvals, research and development costs, projected revenues and expenses and the timing of revenues and expenses, timing and likelihood of success, as well as plans and objectives of management for future operations are forward-looking statements. Many of the forward-looking statements contained in this Annual Report can be identified by the use of forward-looking words such as “anticipate,” “believe,” “could,” “expect,” “should,” “plan,” “intend,” “estimate,” “will” and “potential,” among others.

Forward-looking statements are based on our management’s beliefs and assumptions and on information available to our management at the time such statements are made. Such statements are subject to known and unknown risks and uncertainties, and actual results may differ materially from those expressed or implied in the forward-looking statements due to various factors, including, but not limited to:

•the substantial net losses that we have incurred since our inception, our expectation to continue to incur losses for the foreseeable future and our need to raise additional capital to fund our operations and execute our business plan;

•our indebtedness under the loan agreement and guaranty (the “Loan Agreement”) with certain affiliates and/or funds managed by each of Oaktree Capital Management, L.P. and Owl Rock Capital Advisors LLC, as lenders, and Blue Owl Opportunistic Master Fund I, L.P., as administrative agent, and the associated restrictive covenants thereunder;

•the purchase and sale agreement (the “HCR Agreement”) with certain entities managed by HealthCare Royalty Management, LLC (“HCR”) and its negative effect on the amount of cash that we are able to generate from sales of, and licensing agreements involving, ZYNLONTA and Cami and on our attractiveness as an acquisition target;

•our ability to complete clinical trials on expected timelines, if at all;

•the timing, outcome and results of ongoing or planned clinical trials and the sufficiency of such results;

•undesirable side effects or adverse events of our products and product candidates;

•our and our partners’ ability to obtain and maintain regulatory approval for our product and product candidates;

•our and our partners’ ability to successfully commercialize our products;

•the availability and scope of coverage and reimbursement for our products;

•the complexity and difficulty of manufacturing our products and product candidates;

•the substantial competition in our industry, including new technologies and therapies;

•the timing and results of any early research projects and future clinical outcomes;

•our reliance on third parties for preclinical studies and clinical trials and for the manufacture, production, storage and distribution of our products and product candidates and certain commercialization activities for our products;

•our ability to obtain, maintain and protect our intellectual property rights and our ability to operate our business without infringing on the intellectual property rights of others;

•our estimates regarding future revenue, expenses and needs for additional financing;

•the size and growth potential of the markets for our products and product candidates potential product liability lawsuits and product recalls;

•and those identified in the “Item 1A. Risk Factors” section of this Annual Report and in our other reports filed with the U.S. Securities and Exchange Commission (the “SEC”), from time to time hereafter

Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. Moreover, we operate in an evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements, whether as a result of any new information, future events, changed circumstances or otherwise.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Annual Report, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and investors are cautioned not to unduly rely upon these statements.

ADC Therapeutics is a leading, commercial-stage global pioneer in the field of antibody drug conjugates (“ADCs”) with a validated and differentiated technology platform with multiple payloads and targets, a robust next-generation research and development toolbox, and specialized end-to-end capabilities. We are advancing our proprietary ADC technology to transform the treatment paradigm for patients with hematologic malignancies and solid tumors.

We leverage our scientific and technical expertise and apply a disciplined approach to target selection to expand and advance our pipeline. We have created a diverse clinical and research pipeline that we are advancing with the goal of transforming the cancer treatment paradigm across both hematology and solid tumors. We are also seeking to expand the label for our marketed product, ZYNLONTA (loncastuximab tesirine) into new indications. Our portfolio of ADCs utilizes our highly potent pyrrolobenzodiazepine (“PBD”) technology, a differentiated exatecan-based payload with a novel hydrophilic linker and a next generation ADC toolbox.

In the hematology space, our flagship product, ZYNLONTA, a CD19-directed ADC, received accelerated approval from the U.S. Food and Drug Administration (“FDA”) and conditional approval from the European Commission for the treatment of relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”) after two or more lines of systemic therapy. We are seeking to continue expanding ZYNLONTA into international markets throughout the world, and into earlier lines of DLBCL and indolent lymphomas, including follicular lymphoma (”FL”) and marginal zone lymphoma (“MZL”), as a single agent and in combination through our LOTIS-5 confirmatory Phase 3 clinical trial and LOTIS-7 Phase 1b clinical trial as well as through investigator-initiated trials (“IITs”) at leading institutions. In addition, we are investigating a CD-22 targeted compound, ADCT-602, in a Phase 1/2 investigator-initiated study in relapsed or refractory B-cell acute lymphoblastic leukemia.

In the solid tumor space, our clinical-stage pipeline consists of ADCT-601 (mipasetamab uzoptirine) targeting AXL as a single agent and/or in combination in sarcoma, pancreatic, and NSCLC. Our pre-clinical stage pipeline includes a portfolio of next generation investigational ADCs targeting Claudin-6, NaPi2b, PSMA and other undisclosed targets. In addition, we are advancing research with a range of payloads, linkers, and conjugation technologies against undisclosed targets.

Our goal is to be a leading ADC company that transforms the lives of those impacted by cancer. To achieve this, we are focused on unlocking the potential value of our robust ADC portfolio across two pillars of growth: hematology and solid tumors.

We aim to expand our portfolio and accelerate the development of our pipeline through targeted investments and in collaboration with strategic partners. In this way, we plan to pursue multiple targets in parallel, enabling us to prioritize and ensure disciplined capital allocation strategy while advancing the most promising candidates in both hematology and solid tumors.

Our key priorities span both pillars of our strategy.

(1) Hematology:

•Maximize the ZYNLONTA opportunity.

▪Maximize ZYNLONTA in 3L+ DLBCL. We believe we are well-positioned to grow ZYNLONTA in the 3L/3L+ setting of DLBCL through increased awareness of ZYNLONTA’s single agent efficacy and manageable safety profile making it well-suited for use across both academic and community treatment settings.

▪Seek to expand ZYNLONTA into earlier lines of DLBCL and indolent lymphomas as a single agent and in combination with other drugs. We are exploring the potential to move ZYNLONTA into earlier lines of therapy in combination with rituximab and other novel combinations through our clinical trials and IITs. We believe these development efforts, if successful, will enable ZYNLONTA to move into earlier lines of treatment and potentially become a combination agent of choice in the second-line and third-line settings, increasing ZYNLONTA’s overall market opportunity.

▪Continue to advance the development and commercialization of ZYNLONTA outside of the United States through strategic partnerships. We are committed to providing global access to ZYNLONTA to patients who may benefit from this treatment. We have entered into strategic agreements to maximize the commercial potential of ZYNLONTA, including an exclusive license agreement with Mitsubishi Tanabe Corporation (“MTPC”) in Japan, and a joint venture with Overland Pharmaceuticals in China (including Hong Kong, Macau), Singapore, and Taiwan, and an exclusive license agreement with Sobi for all other regions, excluding the U.S. In Europe, ZYNLONTA has received conditional approval from the European Commission for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. In China, we submitted a marketing authorization application seeking an indication for relapsed or refractory DLBCL after two or more lines of systemic therapy. In Japan, MTPC is undertaking a Phase 1/2 bridging study and joined the LOTIS-5 confirmatory Phase 3 clinical trial.

•ADCT-602 (targeting CD22): The Company is developing ADCT-602 in collaboration with MD Anderson Cancer Center for patients with relapsed or refractory acute lymphoblastic leukemia. Dose escalation and expansion in the Phase 1 trial is progressing and additional clinical trial sites are being added.

(2) Solid Tumors:

•Advance ADC assets against validated targets in indications with high unmet need. ADCT-601 (mipasetamab uzoptirine) (targeting AXL): The Company is evaluating ADCT-601 in a Phase 1b trial in patients with sarcoma, pancreatic cancer and AXL-expressing non-small cell lung cancer and is currently in dose optimization for expansion as single agent and/or in combination.

•Broaden our ADC platform and leadership. The Company is advancing a portfolio of investigational ADCs including those targeting Claudin-6, NaPi2b and PSMA. These candidates are based on an innovative proprietary approach which utilizes exatecan with a novel hydrophilic linker as a highly potent and differentiated payload. We are leveraging our decade-long expertise in the ADC field with multiple INDs and a proven track record of success to continue building this toolbox with new antibody formats, linkers and toxins while advancing a range of payloads, linkers and conjugation technologies against multiple targets to develop differentiated next-generation assets.

We are a pioneer and leader in the ADC field with specialized end-to-end capabilities for developing optimized ADCs. This includes a strong, integrated research & development organization and a validated technology platform with two clinical-stage product candidates currently in the pipeline, multiple next-generation ADCs being developed and a proven executional track record that includes ZYNLONTA, the first PBD-based ADC receiving accelerated approval from the FDA and conditional approval from the European Commission. Since the company was founded in 2011, ADC Therapeutics has significantly invested in all the core capabilities required for the design, pre-clinical and clinical development and manufacturing of novel ADCs. In the discovery stage, we utilize cutting-edge research to select optimal targeting moiety, linker and payload. The intersection of our technical capabilities, integrated organization and depth of experience allows us to move efficiently through preclinical development into the clinic in pursuit of therapeutic window, if needed in biomarker enriched patient populations. Further, Our robust in-house CMC capabilities utilize a highly experienced workforce to manage a top-tier external manufacturing network through third-party CMOs. Our third-party CMO network is capable of manufacturing highly potent molecules and complex biologics.

Antibody drug conjugates (ADCs) are an established therapeutic approach in oncology. ADCs selectively deliver potent cytotoxins directly to tumor cells, with the goal of maximizing activity in tumor cells while minimizing toxicity to healthy cells. ADCs are an important part of the cancer treatment paradigm for the following reasons:

•Selective Targeting. Traditional chemotherapies are unable to distinguish between healthy cells and tumor cells and therefore have a narrow therapeutic window (i.e., the dose range that can treat disease effectively without causing unacceptable toxic side effects). In contrast, ADCs, through their use of tumor-specific antibodies, target tumor cells with greater selectivity than chemotherapies. This selective targeting allows ADCs to use potent cytotoxins at dose levels that otherwise would not be tolerated and ADCs therefore represent a highly effective treatment approach while maintaining manageable side effects.

•Wide Addressable Patient Population. ADCs represent a treatment approach that expands the treatment options available to cancer patients. Many therapies are not appropriate for certain patient populations. For example, chemotherapy may not be appropriate when the patient is too sick to tolerate or does not respond to available chemotherapeutics, stem cell transplant may not be appropriate when the patient is frail, and some novel targeted therapies such as CAR-T (i.e., a type of treatment in which a patient’s T cells are modified in the laboratory so they will attack cancer cells) may not be appropriate when there is significant comorbidity. As a result of these limitations, there remains a significant unmet medical need for patients for whom other treatment options are inappropriate or ineffective.

•Potential in Relapsed or Refractory Patients. Traditional therapies typically have limited effectiveness for patients who exhibit relapsed (i.e., the cancer returns after an initial positive response to treatment) or refractory (i.e., the cancer is resistant to treatment) disease. In contrast, some ADCs have proven efficacious in such patient populations while maintaining a manageable safety profile. Therefore, ADCs represent an important part of the cancer treatment paradigm, expanding the treatment options available to patients suffering from relapsed or refractory disease.

An ADC consists of three components: (i) an antibody that selectively targets a distinct antigen preferentially expressed on tumor cells; (ii) a cytotoxic molecule, often referred to as the toxin or the warhead, that kills the target cell; and (iii) a chemical linker that joins together the antibody and the warhead. The warhead and the linker are together referred to as the payload. The figure below shows the three components of an ADC.

_______________
Schematic representation of an ADC, showing its three components.

Within ADC Therapeutics, we have a strong focus on technology development with the goal of developing best-in-class ADC candidates with an optimal therapeutic window for any given tumor target.

An overview of our expanding toolbox is presented in the table below.

Note: 1 DAR: Drug antibody ratio

Different antibody technologies can be used to optimize targeting of the ADC to the tumor and/or to enhance uptake of the ADC into the tumor once it is bound to the target on the membrane of the tumor. Currently, while most of the ADCs in development are based on monoclonal antibody targeting, we are also exploring the use of bispecific and/or biparatopic antibodies in our ADC selection to enhance the uptake of the ADC into the tumor. We are also exploring the use of novel antibody formats in ADC design such conditionally binding antibodies. Conditionally binding antibodies bind stronger to target expressed in the more acidic local tumor environment and bind less strong to target expressed on healthy tissue which has neutral pH.

Our current pipeline consists of multiple programs targeting a variety of hematological and solid tumor targets for which we have selected ADC candidates employing our proprietary exatecan platform or PBD dimer technology (under license from AstraZeneca). Exatecans belong to the family of camptothecins, which are naturally occurring pentacyclic quinoline alkaloids that bind to DNA topoisomerase I, inhibiting DNA relegation and finally causing apoptosis. Campothecins such as exatecan therefore possesses high cytotoxic activity against a variety of tumors. The potency of exatecan is slightly higher than DXd, the topoisomerase I inhibitor used in EnhertuTM and other ADCs in clinical development such as ifinatamab deruxtecan, patritumab deruxtecan and raludotatug deruxtecan.

PBD dimers are highly potent and bind irreversibly to two guanines from opposite DNA strands in minor groove of DNA without distorting the double helix, potentially evading DNA repair mechanisms. The interstrand cross-links block DNA strand separation, disrupting essential DNA metabolic processes such as replication, and ultimately result in cell death. These interstrand cross-links persist in target cells and can lie dormant, potentially for weeks, which may contribute to the frequency and durability of responses in heavily pre-treated and primary refractory patients that we have observed in our clinical trials with PBD-based ADCs.

Both exatecans and PBD dimers cause a bystander effect, which occurs when a released warhead (from a target positive cells which has internalized and processed the ADC) is able to diffuse into and kill neighboring cells in the tumor microenvironment, irrespective of those cells’ antigen expression. Since exatecan and PBD dimers are cell-permeable, they may be able to diffuse into adjacent cells and kill them in an antigen-independent manner. Importantly, the bystander effect of exatecan has been observed to be considerably stronger than the other topoisomerase 1 inhibitor DXd. Both exatecan and PBD dimers also cause immunogenic cell death (ICD), whereby a cancer cell’s death expresses certain stress signals that induce the body’s anti-tumor immune response through the activation of T cells and antigen-presenting cells. This opens up the potential for combining our ADCs with other therapies, particularly with immuno-oncology therapies such as checkpoint inhibitors, that are specifically designed to activate the patient’s own immune system to combat cancer.

In addition to our proprietary exatecan platform and PBD dimer technology, we have access to another DNA alkylating cytotoxin which we can access under a license agreement. We are furthermore developing payloads based on immune modulators to develop immune stimulating antibody conjugates (ISACs) based on TLR7 or TLR8 agonists. Our ultimate objective is to have a variety of different toxins with orthogonal Mode of Action which can be used to design dual conjugate ADCs (i.e.

an ADC to which two different toxins are conjugated).

Our linker design focuses on different aspects. First, we focus on the spacer in the linker. Our proprietary exatecan platform is based on a novel hydrophilic spacer which allows conjugation of exatecan to antibodies at high drug to antibody ratio (DAR). Secondly, we have cleavable versus non-cleavable linker configurations. While cleavable linkers are the preferred choice if a bystander effect of the ADC is desired, in certain cases bystander activity should be avoided, which can be achieved using non-cleavable linkers. Finally, we have developed a set of branched linkers that allows us to increase the DAR or to generate ADCs with multiple toxins on a single conjugation site.

Depending on the desired DAR and other criteria such as the need for FcGamma Receptor Binding, we have the potential to design the optimal ADC using a selection of different site-specific conjugation technologies, either enzymatic or non-enzymatic. We also have access to multiple conjugation chemistries such as classical maleimide and bio-orthogonal click chemistry and we are implementing additional proprietary approaches. We also have a variety of tools that allows us to design Dual Conjugate ADCs, i.e. ADCs with different toxins conjugated to different sites on the antibody.

The following table provides an overview of our current product portfolio and research pipeline:

NTE: Non-Transplant Eligible. 1. DLBCL, FL, MZL 2. Non-selected advanced/metastatic NSCLC completed. Moving forward with AXL expressing NSCLC Contingent on in-house assay. AA: Accelerated Approval.

There are two core pillars to our strategy which we believe will unlock the tremendous value we see in the Company. Our first pillar, and primary focus, is hematology. The second pillar of our strategy is grounded in our emerging solid tumor pipeline.

We have and continue to develop ZYNLONTA for the treatment of B-cell lymphomas, including:

•DLBCL, is the most common type of lymphoma. It is an aggressive form of non-Hodgkin lymphoma (“NHL”) and accounts for 30% of all NHL cases. Approximately 32,000 people in the United States are diagnosed with DLBCL each year and the five-year prevalence for DLBCL is an estimated 109,000 patients, with approximately 70% in the first-line setting, approximately 21% in the second-line setting and approximately 9% in the third-line setting.

•FL, which is an indolent type of NHL. In the United States, the five-year prevalence for FL is an estimated 61,000 patients, with approximately 65% in the first-line setting, approximately 24% in the second-line setting and approximately 11% in the third-line setting.

•MZL, which is an indolent type of NHL. In the United States, the five-year prevalence for MZL is an estimated 38,000 patients, with approximately 61% in the first-line setting, approximately 27% in the second-line setting and approximately 12% in the third-line setting.

Currently, ZYNLONTA is approved for the treatment of DLBCL in the third-line setting. We believe that our LOTIS-5 confirmatory Phase 3 clinical trial evaluating the efficacy of ZYNLONTA and rituximab, if successful, could allow this combination to be approved for use in the second-line setting for the treatment of DLBCL. In addition, our LOTIS-7 Phase 1b clinical trial is currently evaluating ZYNLONTA in combination with either glofitamab or mosunetuzumab in DLBCL, FL, and MZL, which could provide data supporting the efficacy and safety for these novel combinations also in the second line setting.

Our flagship product, ZYNLONTA (loncastuximab tesirine) is an ADC targeting CD19-expressing cancers. It received accelerated approval from the FDA and conditional approval from the European Commission for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. We are seeking to expand ZYNLONTA into international markets throughout the world, and into earlier lines of DLBCL and other indolent lymphomas as a single agent and in combination through our LOTIS-5 and LOTIS-7 clinical trials, as well as through IITs at leading institutions. ZYNLONTA as a monotherapy has a differentiated profile. Based on data from our LOTIS-2 trial, ZYNLONTA provides rapid responses with the median time to response of 1.5 months. Responses were durable for patients with a complete response and the median duration of response had not yet been reached at the 2-year follow-up. ZYNLONTA has a manageable safety profile with no cytokine release syndrome (CRS), no Risk Evaluation and Mitigation Strategies (“REMS”) or requirement for in-patient stay. ZYNLONTA’s profile is well-positioned for community treaters who do not have access to more complex therapies like CAR-T and newly approved bi-specific antibodies.

ZYNLONTA is composed of a humanized monoclonal antibody (RB4v1.2) directed against human CD19 and conjugated through a cathepsin-cleavable linker to SG3199, a PBD dimer cytotoxin. Once bound to a CD19-expressing cell, it is internalized by the cell, following which the warhead is released. The warhead is designed to bind irreversibly to DNA to create highly potent interstrand cross-links that block DNA strand separation, thus disrupting essential DNA metabolic processes such as replication and ultimately resulting in cell death.

The human CD19 antigen is involved in the recognition, binding and adhesion processes of cells, mediating direct interactions between surfaces of different cell types and pathogen recognition. CD19 is expressed only on B cells (i.e., a type of white blood cell that plays a significant role in protecting the body from infection by producing antibodies)

throughout all stages of B cell development and differentiation. Its expression is maintained at high levels in hematologic B cell malignancies, including NHL and certain types of leukemia.

On April 23, 2021, ZYNLONTA received accelerated approval from the FDA for the treatment of adult patients with relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy, including DLBCL not otherwise specified, DLBCL arising from low-grade lymphoma and high-grade B-cell lymphoma. Continued approval for this indication is contingent upon verification and description of clinical benefit in a confirmatory trial, which we intend to satisfy through our LOTIS-5 confirmatory Phase 3 clinical trial.

On December 20, 2022, the European Commission granted conditional marketing authorization for the use of ZYNLONTA for the treatment of relapsed or refractory DLBCL. The decision is valid in all European Union Member States, Iceland, Norway, and Liechtenstein. Continued approval for this indication is contingent upon verification of clinical benefit in a confirmatory trial, which we intend to satisfy through our LOTIS-5 confirmatory Phase 3 clinical trial.

We continue to directly commercialize ZYNLONTA in the United States through a commercial organization comprised of cross-functional employees, including marketing, sales, market access, insights and analytics, and commercial operations functions. Our field sales team calls on healthcare providers across both the academic and community settings and has the potential to cover more than 90% of the DLBCL opportunity.

Outside of the United States, we have entered into strategic agreements to maximize the commercial potential of ZYNLONTA, including an exclusive license agreement with MTPC in Japan, and a joint venture with Overland Pharmaceuticals in China (including Hong Kong, Macau), Singapore, and Taiwan, and an exclusive license agreement with Sobi for all other regions, excluding the U.S. and Japan. In Europe, ZYNLONTA has received conditional approval from the European Commission for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. In China, we submitted a marketing authorization application seeking an indication for relapsed or refractory DLBCL after two or more lines of systemic therapy. In Japan, MTPC is undertaking a Phase 1/2 bridging study and joined the LOTIS-5 confirmatory Phase 3 clinical trial.

LOTIS-5 is a Phase 3, randomized, open-label, two-part, two-arm, multi-center clinical trial of ZYNLONTA combined with rituximab compared to immunochemotherapy in patients with relapsed or refractory DLBCL. We believe that this clinical trial, if successful, will support an sBLA for ZYNLONTA to be used as a second-line therapy for the treatment of relapsed or refractory DLBCL in transplant-ineligible patients.

The primary objective of the clinical trial is to evaluate the efficacy of ZYNLONTA combined with rituximab compared to standard immunochemotherapy, as measured by PFS. The secondary objectives of the clinical trial are to evaluate OS as well as: (i) characterize the safety profile of ZYNLONTA combined with rituximab, (ii) characterize the pharmacokinetic profile of ZYNLONTA combined with rituximab, (iii) evaluate the immunogenicity of ZYNLONTA combined with rituximab and (iv) evaluate the impact of ZYNLONTA combined with rituximab treatment on treatment-related and disease-related symptoms, patient-reported functions and overall health status.

The clinical trial is enrolling patients with pathologically confirmed relapsed or refractory DLBCL who are not considered by the investigator to be a candidate for SCT and who had failed at least one multi-agent systemic treatment regimen. We expect to complete enrollment in 2024.

The clinical trial is being conducted in two parts: In the safety run-in, the first 20 patients were non-randomly assigned to receive ZYNLONTA in combination with rituximab to compare the combination’s toxicity against historical safety data from monotherapy clinical trials of ZYNLONTA. The randomized part of the clinical trial was initiated after the last patient in the safety run-in completed the first treatment cycle and it was observed that there were no significant increases in toxicity of the combination as compared to historical safety data of ZYNLONTA used as a monotherapy. Patients are randomly assigned 1:1 to receive either ZYNLONTA in combination with rituximab or rituximab in combination with gemcitabine and oxaliplatin.

On August 30, 2023, we announced that updated safety run-in results from the clinical trial. The 20 patients in the safety run-in were a median age of 74.5 years and had previously received a median of five cycles of ZYNLONTA in combination with rituximab and one previous therapy. As of the April 10, 2023, data cutoff:

•Seven patients completed treatment and five continue in follow-up.

•The ORR by central review was 16/20 (80%). A total of 10/20 (50%) and 6/20 (30%) patients attained complete and partial response, respectively.

•The median DoR was 8.0 months and the median PFS was 8.3 months.

•A total of 11 (55%) patients had Grade ≥3 TEAEs. The most common Grade ≥3 TEAEs were increased gamma-glutamyltransferase (five patients (25%)) and neutropenia (three patients (15%)).

As noted by the clinical team and confirmed with the Independent Data Monitoring Committee (IDMC), we have observed higher-than-expected censoring in this trial. As a result, we may need to enroll additional patients, beyond the originally planned 350 patients, to achieve the required number of pre-specified progression-free survival events. Nonetheless, we continue to expect to complete enrollment of this trial in 2024. The IDMC noted no safety concerns and recommended the trial to proceed at its most recent meeting held in January 16, 2024.

We have conducted a 145-patient Phase 2, multi-center, open-label, single-arm clinical trial to evaluate the safety and efficacy of ZYNLONTA in patients with relapsed or refractory DLBCL.

The primary objective of the clinical trial was to evaluate the efficacy of ZYNLONTA in patients with relapsed or refractory DLBCL, measured by ORR based on the 2014 Lugano Classification Criteria. The secondary objectives were to (i) further evaluate the efficacy of ZYNLONTA measured by duration of response (“DoR”), complete response rate (“CRR”), progression-free survival (“PFS”), relapse-free survival (“RFS”) and overall survival (“OS”), (ii) characterize the safety profile of ZYNLONTA, (iii) characterize the pharmacokinetic profile of ZYNLONTA, (iv) evaluate the immunogenicity of ZYNLONTA and (v) evaluate the impact of ZYNLONTA treatment on health-related quality of life (“HRQoL”).

The clinical trial enrolled patients with pathologically confirmed relapsed or refractory DLBCL who have previously received two or more multi-agent systemic treatment regimens. The table below presents information about the patients’ characteristics.

Patient Characteristics												n=145
Age, median (minimum, maximum)												66						(23, 94)
Histology, n (%)						DLBCL Not otherwise specified						128						(88.3)
						HGBCL*						10						(6.9)
						PMBCL**						7						(4.8)
Cancer characteristic, n (%)						Double-hit or triple-hit disease***						15						(10.3)
						Double/triple expressor						20						(13.8)
						Transformed disease****						29						(20.0)
Disease stage*****, n (%)						I-II						33						(22.8)
						III-IV						112						(77.2)
Number of previous systemic therapies received, median (minimum, maximum)												3						(2, 7)
Response to first-line prior systemic therapy, n (%)						Relapsed						99						(68.3)
						Refractory						29						(20.0)
Response to most recent prior systemic therapy, n (%)						Relapsed						44						(30.3)
						Refractory						88						(60.7)
Refractory to all prior systemic therapies, n (%)						Yes						24						(16.6)
						No						115						(79.3)
Prior stem cell transplant, n (%)						Autologous stem cell transplant						21						(14.5)
						Allogeneic stem cell transplant						2						(1.4)
						Both autologous and allogeneic stem cell transplant						1						(0.7)
						No						121						(83.4)

_______________
Information about the patients’ characteristics. *High-grade diffuse large B-cell lymphoma. **Primary mediastinal large B-cell lymphoma. ***Double-hit or triple-hit DLBCL are rare subtypes of DLBCL characterized by two or three recurrent chromosome translocations and are generally associated with poor prognosis. ****Transformed disease is recorded for patients who had another type of lymphoma that transformed to DLBCL. *****Disease stage is determined by the location of the tumor: Stage I means that the cancer is located in a single region, usually one lymph node and the surrounding area. Stage II means that the cancer is located in two separate regions, an affected lymph node or lymphatic organ and a second affected area, and that both affected areas are confined to one side of the diaphragm; Stage III means that the cancer has spread to both sides of the diaphragm, including one organ or area near the lymph nodes or the spleen; Stage IV means diffuse or disseminated involvement of one or more extralymphatic organs, including any involvement of the liver, bone marrow, or nodular involvement of the lungs.

The mean number of treatment cycles received was 4.6 and the maximum number of treatment cycles received was 26.

As of March 1, 2021, the main observed safety and tolerability findings were as follows:

•Grade ≥3 TEAEs were reported in 107 patients, or 73.8% of patients. The most common Grade ≥3 TEAEs that were reported in more than 10% of patients included neutropenia (reported in 26.2% of patients), thrombocytopenia (reported in 17.9% of patients), gamma-glutamyltransferase increased (reported in 17.2% of patients) and anemia (reported in 10.3% of patients).

•Treatment-related adverse events in 27 patients, or 18.6% of patients, led to treatment discontinuation. The most common of such adverse events that led to treatment discontinuation in more than 2% of patients included gamma-glutamyltransferase increased (led to treatment discontinuation in 11.7% of patients), peripheral edema (led to treatment discontinuation in 2.8% of patients) and localized edema (led to treatment discontinuation in 2.1% of patients).

•No increase in adverse events was observed in patients aged ≥65 years compared to younger patients.

The main observed efficacy findings were as follows:

•Thirty-six patients, or 24.8% of patients, achieved a complete response and another 34 patients, or 23.4% of patients, achieved a partial response, resulting in a 48.3% ORR. The median time to first response was 41.0 days.

•ZYNLONTA’s favorable clinical activity was observed across a broad patient population in this clinical trial, including transplant eligible and ineligible patients, patients who have not responded to first-line therapy or any prior therapy, double-hit and triple-hit disease and transformed disease and patients who had received prior CD19 therapies or SCT.

•The median DoR was 13.37 months for patients who achieved a response. The median DoR was not reached for patients who achieved a complete response and was 5.68 months for patients who achieved a partial response. The median DoR observed in subgroups at high risk of poor prognosis was comparable to that observed in the overall study population.

•Sixteen patients received CD-19 directed CAR-T after receiving treatment with ZYNLONTA, with an investigator-assessed ORR of 56.3% (eight complete response and one partial response). Eleven patients received SCT as consolidation after responding to treatment with ZYNLONTA.

•The median progression free survival was 4.93 months.

•The median overall survival was 9.53 months.

LOTIS-7 is a Phase 1b, multi-center, open-label, multi-arm study to evaluate the safety and anti-cancer activity of ZYNLONTA in combination with other anti-cancer agents in patients with relapsed or refractory B-cell NHL. The primary objective of the clinical trial is to characterize the safety and tolerability of loncastuximab tesirine in combination with polatuzumab vedotin, glofitamab, or mosunetuzumab, and to identify the maximum tolerated dose (“MTD”) and/or recommended dose for expansion (“RDE”) for any of the combinations.

The secondary objectives of the clinical trial are to evaluate the anti-cancer effect of loncastuximab tesirine in combination with polatuzumab vedotin, glofitamab, or mosunetuzumab, to characterize the pharmacokinetics (“PK”) profile of loncastuximab tesirine in combination with polatuzumab vedotin, glofitamab, or mosunetuzumab, and to evaluate the immunogenicity of loncastuximab tesirine, glofitamab, and mosunetuzumab, respectively.

The clinical trial is enrolling patients with relapsed or refractory B-cell NHL who have previously received two or more multi-agent systemic treatment regimens (in the dose escalation part) or who have previously received one or more multi-agent systemic treatment regimens (in the dose expansion part). The clinical trial is expected to enroll approximately 200 patients. The clinical trial intends to evaluate various combinations in two parts: dose escalation and dose expansion. Dose escalation is ongoing with a cohort of patients receiving ZYNLONTA in combination with mosunetuzumab or in combination with glofitamab.

The dose-limiting toxicity (DLT) period has been cleared for the first two dosing levels of ZYNLONTA (90 µg/kg, 120 µg/kg) in both arms and we are currently enrolling patients at 150 µg/kg. After the first Investigator assessment, we have seen evidence of anti-tumor activity among the majority of patients dosed at the first two levels, with mixed histologies including DLBCL, FL, and MZL. Once dose escalation is complete, we plan to expand at the appropriate dose levels. The Company expects to share additional data once a larger and more mature dataset is available.

LOTIS-10 is a Phase 1b open-label, multi-center study to evaluate the safety, pharmacokinetics and anti-cancer activity of ZYNLONTA in patients with relapsed or refractory DLBCL or high-grade B-cell lymphoma (“HGBCL”) with hepatic impairment. The primary objective of the clinical trial is to determine the recommended dosing regimen of loncastuximab

tesirine in DLBCL or HGBCL patients with moderate and severe hepatic impairment. The secondary objectives of the clinical trial are to characterize the PK profile, safety and tolerability of loncastuximab tesirine in patients with hepatic impairment, and to evaluate the antitumor activity and the immunogenicity of loncastuximab tesirine in patients with hepatic impairment.

The clinical trial is enrolling patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) or HGBCL with hepatic impairment. The clinical trial is expected to enroll approximately 56 patients.

‘Glo-BNHL’ is an international multi-center, adaptive, platform trial of novel agents in pediatric and adolescent relapsed or refractory B-cell NHL. The primary objective of the clinical trial is to estimate the clinical efficacy of the specific treatment in patients with r/r B-NHL in either first relapse or subsequent relapse. The secondary objectives of the clinical trial are to assess the safety profile of the novel agent in children, adolescents, and young adults and to confirm the pharmacokinetics of the novel agent at the recommended trial dose in children, adolescents, and young adults, where relevant.

The clinical trial is enrolling children, adolescents and young adults with relapsed or refractory B-cell NHL. The initial target sample size is 15 evaluable patients in each treatment arm or relevant sub-group, with additional patients to be added pending results from the no/no go decision from the initial 15 patients results.

The clinical trial consists of three arms: bispecific antibody (Arm A); ADC with standard chemotherapy (Arm B); and CAR-T (Arm C). Novel agents are selected for inclusion in the platform according to an overarching prioritization list and a robust systematic scientific assessment of each proposed asset. ZYNLONTA was selected for study in Arm B in combination with modified R-ICE (rituximab, ifosfamide, carboplatin and etoposide) chemotherapy to estimate the clinical efficacy of the combination in patients with relapsed or refractory B-cell NHL in first (only one prior line of therapy) or subsequent relapse (more than one prior line of therapy).

Acute lymphoblastic leukemia (“ALL”) is a rare form of blood cancer with an annual incidence of ~6,000. Adults make-up ~50% of ALL patients. The five-year survival rate is 71%; however, it declines significantly with age. Allogeneic transplant is the standard of care for patients who are relapsed or refractory to induction therapy. Achieving a response without toxicities which can prevent a patient’s ability to get to an allogeneic transplant is an area of unmet need. We are developing ADCT-602 (CD22) in this area of high unmet medical need.

ADCT-602 (CD22) is composed of a humanized monoclonal antibody (hLL2-C220) directed against human CD22 and conjugated through a cathepsin-cleavable linker to SG3199, a PBD dimer cytotoxin. Once bound to a CD22-expressing cell, it is internalized by the cell, following which the warhead is released. The warhead is designed to bind irreversibly to DNA to create highly potent interstrand cross-links that block DNA strand separation, thus disrupting essential DNA metabolic processes such as replication and ultimately resulting in cell death. The human CD22 antigen plays a pivotal role in the recognition, binding and adhesion processes of cells. CD22 is only expressed on B cells throughout all stages of B cell development and differentiation. Its expression is maintained in high levels in hematological B cell malignancies, including in NHL and certain types of leukemia, including B-cell ALL.

Pursuant to our collaboration agreement with MD Anderson Cancer Center, a Phase 1/2, open-label, dose escalation and dose expansion clinical trial of the safety and anti-tumor activity of ADCT-602 (CD22), used as monotherapy, in patients with relapsed or refractory ALL is progressing and additional clinical trial sites are being added to accelerate enrollment.

The primary objectives of the dose escalation stage are to (i) evaluate the safety and tolerability, and determine, as appropriate, the MTD of ADCT-602 (CD22) in patients with relapsed or refractory ALL and (ii) determine the recommended dose(s) of ADCT-602 (CD22) for the dose expansion stage. The primary objective of the dose expansion stage is to evaluate the efficacy of ADCT-602 (CD22) at the dose level(s) recommended from the results of the dose escalation stage. The secondary objectives of the clinical trial are to (i) evaluate the clinical activity of ADCT-602 (CD22), as measured by ORR, DoR, OS and PFS, (ii) characterize the pharmacokinetic profile of ADCT-602 and the free warhead SG3199, (iii) evaluate the immunogenicity of ADCT-602 (CD22) and (iv) characterize the effect of ADCT-602 (CD22) exposure on the QT interval.

The clinical trial is enrolling patients with pathologically confirmed relapsed or refractory B-ALL and patients with pathologically confirmed relapsed or refractory Ph+ ALL who have failed either first- or second-generation tyrosine kinase inhibitor. The clinical trial is expected to enroll approximately 65 patients.

As presented at ASH 2022 (data cutoff July 2022), 21 patients have been treated with ADCT-602 (CD22). We observed that ADCT-602 (CD22) was well tolerated with one DLT of prolonged myelosuppression. Four patients achieved MRD-negative remission, including two of six patients at the 50 µg/kg weekly dose level. One additional patient at 50 µg/kg weekly dose level had marrow blast clearance without count recovery. Additional data is expected in 2024.

There are many different types of solid tumors and they account for the majority of cancers. Some of the most commonly diagnosed solid tumor cancers include lung cancer and prostate cancer. There were an estimated ~198,000 new cases of non-small cell lung cancer and ~264,000 new cases of prostate cancer in the United States in 2022. The prognosis and treatment of solid tumor cancers vary based on the type of cancer. Two types of solid tumor cancers with limited therapeutic options and poor prognosis include pancreatic cancer and sarcoma. There are ~64,000 new cases of pancreatic cancer and ~18,000 new cases of sarcoma each year in the United States.

Despite recent significant advances in the treatment of some solid tumor cancers, there remains a high medical need for novel therapies.

Pancreatic Cancer:

With an 11% 5-year survival rate among all patients, and only 2.9% in patients with metastatic disease, pancreatic ductal adenocarcinoma (“PDAC”) has surpassed breast cancer to become the third leading cause of cancer related death in the United States. By 2030, PDAC is expected to be second only to lung cancer as the leading cause of cancer-related mortality.

Surgery is the sole potentially curative option for patients with pancreatic cancer. This is only possible in 15%–20% of patients as non-specific symptoms and disease aggressiveness lead to late diagnosis. Most patients (~80%) have locally advanced or metastatic pancreatic adenocarcinoma (mPAC) at diagnosis, and 60%–90% of resected patients will develop locally recurrent or metastatic disease despite surgery and adjuvant treatment.

Sarcoma:

Sarcomas are a heterogeneous group of tumors which includes more than 70 different subtypes. Treatment of sarcoma is complicated by the heterogenous nature of the tumors, however, anthracycline-based chemotherapy remains the first-line standard of care for most metastatic soft tissue sarcoma (STS), with a significant burden in terms of toxicity and variable efficacy. Even with the recent development and approval of a few novel therapeutic agents in the past few years, the prognosis of metastatic STS remains dire. In fact, only about 15% of patients with soft tissue metastatic sarcoma are alive at 5 years from diagnosis.

ADCT-601 (AXL) is composed of a humanized monoclonal antibody (1H12-HAKB) directed against human AXL and conjugated through a cathepsin-cleavable linker to SG3199, a PBD dimer cytotoxin. ADCT-601 employs GlycoConnectTM and HydraspaceTM technology licensed from Synaffix (The Netherlands). Once bound to an AXL-expressing cell, it is internalized by the cell, following which the warhead is released. The warhead is designed to bind irreversibly to DNA to create highly potent interstrand cross-links that block DNA strand separation, thus disrupting essential DNA metabolic processes such as replication and ultimately resulting in cell death. AXL is thought to be overexpressed in various solid tumors of significant unmet medical need including non-small cell lung cancer, pancreatic cancer and sarcoma.

We conducted a Phase 1, open-label, dose escalation and dose expansion clinical trial of the safety, tolerability, pharmacokinetics and anti-tumor activity of ADCT-601 (AXL) in patients with selected advanced solid or metastatic tumors, including triple-negative breast cancer, colorectal cancer, esophageal cancer, gastric cancer, head and neck cancer, mesothelioma, non-small cell lung cancer, ovarian cancer, pancreatic cancer and soft tissue sarcoma.

The primary objectives of the clinical trial were to (i) evaluate the safety and tolerability of ADCT-601 (AXL) in patients with selected advanced solid tumors and (ii) identify the recommended dose and dose schedule for future studies in patients with selected advanced solid tumors. The secondary objectives were to (i) evaluate the preliminary anti-tumor activity of ADCT-601 (AXL), (ii) characterize the pharmacokinetic profile of ADCT-601 (AXL) and (iii) evaluate the immunogenicity of ADCT-601 (AXL). The clinical trial enrolled patients with pathologically confirmed relapsed or refractory solid tumor malignancy that is locally advanced or metastatic at the time of screening and who have failed or are intolerant to existing therapies.

The clinical trial is expected to enroll approximately 150 patients.

Dose escalation is completed for monotherapy and ongoing in combination with gemcitabine. In the dose expansion stage, we intend to prioritize soft tissue sarcoma, pancreatic cancer and AXL-expressing NSCLC for the monotherapy cohort and to prioritize sarcoma indications and pancreatic cancer for the combination cohort. As of December 2023, from 18 patients with sarcoma in the monotherapy arm, three patients discontinued treatment due to AEs and the most common Grade ≥3 TEAEs occurring in at least 10% of patients was gamma-glutamyltransferase increased (11.1%). As of December 2023, from nine patients with sarcoma in the combination arm, no patients discontinued treatment due to AEs and the most common Grade ≥3 TEAEs occurring in at least 10% of patients were anemia (44.4%), thrombocytopenia (44.4%), neutropenia (33.3%), neutrophil count decreased (33.3%), pleural effusion (22.2%), platelet count decreased (22.2%) and gamma-glutamyltransferase increased (22.2%). We have observed that ADCT-601 (AXL) has shown early signs of anti-tumor activity as monotherapy and in combination with gemcitabine in sarcoma patients.

We believe that the manufacture of ADCs requires considerable expertise, know-how and resources. We are a pioneer and leader in the ADC field with specialized end-to-end capabilities for developing optimized manufacturing processes for ADCs. Our robust in-house CMC capabilities utilize a highly experienced workforce to manage a top-tier external manufacturing network through third-party CMOs. Our third-party CMO network is capable of manufacturing highly potent molecules and complex biologics.

We do not own or operate, and do not plan to own or operate, manufacturing infrastructure for the manufacture of clinical supply of our product candidates or commercial product. Instead, we contract with third-party cGMP-compliant CMOs that have the facilities and capabilities to manufacture on our behalf the intermediate components and the final product candidates for use in clinical trials and commercial supply. We have sufficient commercial-grade drug product, ZYNLONTA, in stock and we believe we and our CMOs will be able to conduct additional manufacturing at the scheduled times. Our in-house team oversees all aspects of the CMO manufacturing process, including defining the scope of work and monitoring all aspects of the manufacturing process, including conducting routine site visits and audits. We also contract with external specialist quality control and stability-testing organizations to monitor the quality of the materials manufactured by the CMOs.

Our success depends in part on our ability to obtain and maintain proprietary protection for our technology, programs and know-how related to our business, defend and enforce our intellectual property rights, in particular, our patent rights, preserve the confidentiality of our trade secrets, and operate without infringing valid and enforceable intellectual property rights of others. We seek to protect our proprietary position by, among other things, exclusively licensing and filing U.S. and foreign patent applications related to our technology, existing and planned programs and improvements that are important to the development of our business, where patent protection is available.

We also rely on trade secrets, know-how, continuing technological innovation and confidential information to develop and maintain our proprietary position and protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection. We seek to protect our proprietary technology and processes, in part, by confidentiality agreements with our employees, consultants, scientific advisors, and contractors. We also seek to preserve the integrity and confidentiality of our data and trade secrets by maintaining physical security of our premises and physical and electronic security of our information technology systems.

Notwithstanding these efforts, we cannot be sure that patents will be granted with respect to any patent applications we have licensed or filed or may license or file in the future, and we cannot be sure that any patents we have licensed or patents that may be licensed or granted to us in the future will not be challenged, invalidated, or circumvented or that such patents will be commercially useful in protecting our technology. Moreover, trade secrets can be difficult to protect. While we have confidence in the measures we take to protect and preserve our trade secrets, such measures can be breached, and we may not have adequate remedies for any such breach. In addition, our trade secrets may otherwise become known or be independently discovered by competitors.

In addition, we or our licensors may be subject to claims that former employees, collaborators, or other third parties have an interest in our owned or in-licensed patents or other intellectual property as an inventor or co-inventor. If we are unable to obtain an exclusive license to any such third-party co-owners’ interest in such patent applications, such co-owners may be able to license their rights to other third parties, including our competitors. In addition, we may need the cooperation of any such co-owners to enforce any patents that issue from such patent applications against third parties, and such cooperation may not be provided to us.

For more information regarding the risks related to intellectual property, please see “Item 1A. Risk Factors—Risks Related to Intellectual Property.”

The term of individual utility patents depends upon the countries in which they are granted. In most countries, including the United States, the utility patent term is generally 20 years from the earliest claimed filing date of a non-provisional utility patent application in the applicable country. United States provisional utility patent applications are not eligible to become issued patents until, among other things, non-provisional patent applications are filed within 12 months of the filing date of the applicable provisional patent applications and the failure to file such non-provisional patent applications within such timeline could cause us to lose the ability to obtain patent protection for the inventions disclosed in the associated provisional patent applications. In the United States, a patent’s term may, in certain cases, be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the USPTO in examining and granting a patent, or may be shortened if a patent is terminally disclaimed over a commonly owned patent having an earlier expiration date. In certain circumstances, U.S. patents can also be eligible for patent term extension; for more information, see “—Government Regulation—Regulatory Approval in the United States—U.S. Patent Term Restoration and Marketing Exclusivity.” The expiration dates referred to below are without regard to potential patent term adjustment or extension that may be available to us.

In general, our licensed, owned or co-owned patents relate to our ADC products, the underlying antibodies, the warheads, such as PBD-based warhead, the linker used to connect such warheads to the antibodies to form an ADC, modifications of the antibodies to enhance efficacy, and the methods to formulate, co-formulate, use and administer or co-administer such ADCs. We typically file patent applications in the U.S. and other key foreign countries. We have over 400 patents issued in the U.S. and other countries with expirations ranging from 2023 to 2043 as well as numerous pending patent applications in the U.S. and other countries.

As of December 31, 2023, with respect to the PBD-based warhead and ADC technology we use to develop our product candidates, we have exclusively licensed from MedImmune for particular target molecules, 36 patent families directed to different aspects of the chemistry of the PBD molecules and methods of using the molecules in the treatment of proliferative diseases. These families include approximately 40 issued U.S. utility patents. The issued utility patents, and any utility patents granted from the pending applications in these families, are expected to expire between 2023 and 2038.

As of December 31, 2023, we co-own with MedImmune, and have exclusive rights to, approximately 30 patent families directed to ADCs with PBD warheads and targeting moieties that bind to specific target molecules, combinations of these ADCs with other therapeutic molecules and therapeutic uses of these ADCs. These families include approximately 21 issued U.S. utility patents. The issued utility patents, and any utility patents granted from the pending applications in these families, are expected to expire between 2033 and 2042. Further details in relation to particular marketed products are provided below. We also solely own eight patent families directed to antibodies, ADCs with warheads other than PBDs and therapeutic uses of these antibodies and ADCs.

The antibody for ZYNLONTA is in the public domain.

Patents more specifically directed to the ZYNLONTA ADC are co-owned by us and MedImmune, with us having the exclusive right to exploit the relevant patents during the term of our license and collaboration agreement with MedImmune. As of December 31, 2023, there are six such patent families directed to the ADC product, methods of using the ADC as a single agent or in combination with other named molecules in the treatment of proliferative diseases, and dosing regimens. The issued utility patents, and any utility patents granted from the pending applications in these families, are expected to expire between 2033 and 2042.

For more information on the license and collaboration agreement with MedImmune, see “—Material Contracts—MedImmune License and Collaboration Agreement.”

The biotechnology industry, and the oncology subsector, are characterized by rapid evolution of technologies, fierce competition and strong defense of intellectual property. While we believe that our technology, intellectual property, know-how, scientific expertise and team provide us with certain competitive advantages, we face potential competition from many sources, including major pharmaceutical and biotechnology companies, academic institutions and public and private research organizations. Many competitors and potential competitors have substantially greater scientific, research and product development capabilities, as well as greater financial, marketing and human resources than we do.

Many companies are active in the oncology market and are developing or marketing products for the specific therapeutic markets that we target, including both antibody drug conjugate (“ADC”) and non-antibody drug conjugate therapies. Similarly, we also face competition from other companies and institutions that continue to invest in innovation in the ADC field including new payload classes, new conjugation approaches and new targeting moieties. Specifically, we are aware of multiple companies with ADC technologies that may be competitive with our product and product candidates, including, but not limited to, AbbVie, Inc., Daiichi Sankyo Company, GlaxoSmithKline plc, Gilead Sciences, Inc., Mersana Therapeutics Inc., Sanofi S.A., Roche Holding AG, Pfizer Inc. and Zymeworks, Inc. There are hundreds of ADCs in development, the vast majority of which were being developed for the treatment of cancer.

In the relapsed or refractory DLBCL setting, for which we have developed ZYNLONTA, current third-line treatment options include CAR-T, allogeneic stem cell transplant, polatuzumab in combination with bendamustine and a rituximab product, selinexor, tafasitamab in combination with lenalidomide, glofitamab, epcoritamab and chemotherapies. If ZYNLONTA is approved for use as a second-line treatment for DLBCL patients, we will continue to compete with CAR-T, autologous stem cell transplant, rituximab in combination with chemotherapies, polatuzumab in combination with bendamustine and a rituximab product, and tafasitamab in combination with lenalidomide. In addition, we expect potential future competition from bispecific antibodies such as glofitamab and epcoritamab alone or in combinations with chemotherapies or polatuzumab to gain approval in the second-line treatment of DLBCL.

Any products and product candidates that we successfully develop and commercialize may compete directly with approved therapies and any new therapies that may be approved in the future. Competition will be based on their safety and effectiveness, the timing and scope of marketing approvals, the availability and cost of supply, marketing and sales capabilities, reimbursement coverage, price levels and discounts offered, patent position and other factors. Our competitors may succeed in developing competing products before we do, obtaining marketing approval for products and gaining acceptance for such products in the same markets that we are targeting.

The following descriptions of our material agreements are not complete and are qualified in their entirety by reference to the full text of such agreements, which are filed as exhibits to this Annual Report.

In 2011, we (then operating under the name ADCT Sàrl) entered into a license and collaboration agreement with Spirogen (since renamed ADC Products UK Ltd.), pursuant to which Spirogen granted us access to its next-generation PBD-based warhead and linker technology. In connection with AstraZeneca plc’s acquisition of Spirogen Sàrl (which was at the time the direct parent company of Spirogen) and the transfer of certain of Spirogen’s intellectual property to Spirogen Sàrl, including its PBD-based warhead and linker technology, the agreement was subsequently amended and restated in October 2013 (with retroactive effect to September 2011), with Spirogen Sàrl also becoming a party to such agreement. Spirogen Sàrl subsequently transferred the PBD technology to MedImmune Limited, which, together with MedImmune LLC, is the global biologics research and development arm of AstraZeneca plc. Thereafter, Spirogen Sàrl transferred its rights and obligations under the agreement to MedImmune and the agreement was subsequently amended and restated again in May 2016 (with retroactive effect to September 2011), with MedImmune replacing Spirogen Sàrl as the licensor thereunder.

Under the terms of the agreement, MedImmune has granted us an exclusive, worldwide license under certain patent rights and related know-how to make, have made, use, sell, offer for sale and import product candidates in the field of human therapeutics and diagnostics that consist of (i) PBD-based molecules directly conjugated to an antibody (i.e., ADCs with a PBD-based warhead) that specifically bind to up to 11 approved targets (“ADC Targets”), and (ii) PBD-based molecules conjugated to a non-antibody (i.e., targeting-moiety conjugates with a PBD-based warhead) that specifically bind to up to ten approved targets (“XDC Targets”). As of the date hereof, there are 11 approved ADC Targets subject to the license, including CD19 (the target of ZYNLONTA), and ten approved XDC Targets subject to the license.

Under the terms of the agreement, we have the right to grant sublicenses to affiliates and, subject to MedImmune’s approval (not to be unreasonably withheld), third parties. In addition, with respect to each licensed target, we agreed to use commercially reasonable efforts to develop and commercialize at least one product and submit an IND application with the FDA (or its equivalent in another jurisdiction) for one product within 48 months after formal designation of the target as an approved target, which we have done with respect to CD19 and CD25 upon submitting the IND applications for ZYNLONTA and Cami, respectively.

As consideration for the rights granted to us under the agreement, in 2011 we paid Spirogen an up-front licensing fee of $2.5 million. No further payments in consideration for the grant of such rights are required to be paid to Spirogen or MedImmune under the agreement.

With respect to patent rights conceived during the course of our exercise of our rights under the agreement, rights are allocated as follows under the agreement: (i) we own any such patent that claims an antibody that binds to one of the ADC Targets approved under the agreement, (ii) we and MedImmune jointly own any such patent claiming any PBD-based ADC, with us owning the exclusive right to exploit such patent during the term of the agreement and (iii) MedImmune owns any such patent that claims a PBD or any PBD attached to an antibody that does not bind to one of the ADC Targets approved under the agreement. In addition, we have the right to prosecute and maintain all patents described in clauses (i) and (ii) above and are responsible for the costs of prosecuting and maintaining such patents. The ownership of any patent rights conceived during our exercise of our rights under the agreement in connection with non-ADC Targets will be determined under U.S. patent law.

Unless earlier terminated, the agreement terminates on the date of expiration of the last to expire licensed patent right that covers a product being exploited under the license. The agreement (including the licenses granted thereunder) will terminate upon our material breach of any provision of the agreement that is not cured within an applicable cure period.

In December 2020, we entered into a joint venture with Overland Pharmaceuticals (“Overland”) to develop and commercialize ZYNLONTA, ADCT-602, ADCT-601 and ADCT-901 in greater China and Singapore. In connection with such joint venture, we entered into a license and collaboration agreement with the joint venture entity, Overland ADCT BioPharma (CY) Limited (“Overland ADCT BioPharma”) pursuant to which we granted Overland ADCT BioPharma an exclusive license or sublicense (as applicable) under all applicable patents and know-how now or in the future owned or controlled by us relating to ZYNLONTA, ADCT-602, ADCT-601 and ADCT-901 (collectively, the “Licensed Products”) in order to use, sell, offer for sale, import and commercialize such product candidates in China, Hong Kong, Macau, Taiwan and Singapore (the “Territory”). We also granted Overland ADCT BioPharma an exclusive right of first negotiation to obtain a license in the event we seek to grant to a third party a license in certain circumstances.

Overland ADCT BioPharma is responsible, at its sole cost, for the development, regulatory approval and commercialization of the Licensed Products in the Territory, and must use diligent efforts in order to obtain and maintain regulatory approval for and commercialize the products in each applicable jurisdiction. We maintain an exclusive option, on a product-by-product basis, to co-promote and participate in the detailing, promotion and marketing of the Licensed Products in the Territory. Upon any exercise by us of such option, we and Overland ADCT BioPharma will negotiate in good faith commercially reasonable terms for a co-promotion agreement. We maintain the right to control clinical trials for the Licensed Products conducted both in and out of the Territory, and the license agreement sets forth the division of costs between us and Overland ADCT BioPharma with respect to clinical trials depending on the territories within which such trials are conducted or relate to. We are required to use diligent efforts to manufacture and supply to Overland ADCT BioPharma (at our manufacturing cost), and Overland ADCT BioPharma must purchase from us, all of Overland ADCT BioPharma’s requirements of the Licensed Products for its development and commercialization activities.

The collaboration will be managed by a joint steering committee (and other applicable committees and subcommittees) comprised of equal numbers of representatives from us and Overland ADCT BioPharma. In the event of a dispute that cannot be resolved by discussions between our CEO and Overland ADCT BioPharma’s CEO, Overland ADCT BioPharma shall have final decision-making authority with respect to matters that relate specifically to the development and commercialization of the Licensed Products in the Territory, except where such matters could also affect the products outside of the Territory and with respect to other specified matters (in which cases we shall have such authority).

As partial consideration for the rights granted to Overland ADCT BioPharma pursuant to the agreement, Overland ADCT BioPharma issued to us 44,590,000 Series A shares. We are also entitled to receive tiered quarterly royalties on Overland ADCT BioPharma’s net sales of the Licensed Products ranging from the low to mid-single digit percentages.

Such royalties are payable, on a product-by-product and jurisdiction-by-jurisdiction basis, from the first commercial sale of a product in a jurisdiction until the latest of (i) the expiration of the last to expire claim in the licensed patent that covers such product or any components thereof in such jurisdiction, (ii) the last to expire regulatory exclusivity period for such product in such jurisdiction and (iii) a specified period after the first commercial sale of such product in such jurisdiction. Overland ADCT BioPharma must also reimburse us for any payments we are obligated to make to any of our licensors including in connection with the grant of a sublicense to Overland ADCT BioPharma under applicable intellectual property pursuant to this agreement, including any fees or payments directly resulting from or reasonably allocable to Overland ADCT BioPharma’s development and commercialization of the Licensed Products.

The license agreement remains in effect, on a product-by-product basis, for as long as Overland ADCT BioPharma continues to develop or commercialize such product. Either party may terminate the license agreement for a material breach by the other party, subject to specified notice and cure periods, or upon immediate written notice for an insolvency-related event experienced by the other party. We may also terminate the license agreement, subject to a specified notice and cure period, if Overland ADCT BioPharma commences a legal action challenging the validity, enforceability or scope of any patent owned or controlled by us that covers the applicable products.

In August 2021, we entered into a royalty purchase agreement with certain entities managed by HCR for up to $325.0 million. Under the terms of the agreement, we received gross proceeds of $225.0 million upon closing and $75.0 million upon the first commercial sale of ZYNLONTA in Europe (collectively, the “Investment Amount”). Under the agreement, we are obligated to pay to HCR (i) a 7% royalty on the worldwide (excluding China, Hong Kong, Macau, Taiwan, Singapore and South Korea) net sales of ZYNLONTA and any product that contains ZYNLONTA and on any upfront or milestone payments we receive from licenses that we grant to commercialize ZYNLONTA or any product that contains ZYNLONTA in any region other than China, Hong Kong, Macau, Taiwan, Singapore and South Korea, (ii) a 7% royalty on the worldwide net sales of Cami and any product that contains Cami and on any upfront or milestone payments we receive from licenses that we grant to commercialize Cami or any product that contains Cami in the United States and Europe, and (iii) outside the United States and Europe, a 7% share of any upfront or milestone payments derived from licenses that we grant to commercialize Cami or any product that contains Cami and, in lieu of the royalty on net sales under such licenses, a mid-teen percentage share of the net royalty we receive from such licenses. These royalty rates are subject to potential upward adjustment, up to a maximum of 10%, based on performance tests in 2026 and 2027. The 7% royalty rates described above are subject to adjustment to a potential high-single-digit percentage royalty rate after September 30, 2026 and/or a 10% royalty rate after September 30, 2027, if the aggregate net sales and license revenue subject to royalty obligations in the preceding twelve months do not exceed certain mid-nine-digit milestones by such dates. Our aggregate royalty obligations are capped at 2.50 times the amount paid by HCR under the agreement, or at 2.25 times the amount paid by HCR under the agreement if HCR receives royalty payments exceeding a mid-nine-digit amount on or prior to March 31, 2029 (the “Royalty Cap”). Once the Royalty Cap is reached, the royalty purchase agreement will terminate.

Upon the occurrence of a change in control event, we are obligated to pay HCR an amount equal to the Royalty Cap, less any amounts we previously paid to HCR. If the change in control event occurs prior to the 36-month anniversary of the closing of the royalty purchase agreement, we are obligated to pay HCR an amount equal to 2.0 times the amount paid by HCR, less any amounts we previously paid to HCR pursuant to the agreement. In addition, we retain the right, at any time after the 27-month anniversary of the closing of the royalty purchase agreement, to terminate the remaining royalty obligations under the agreement by paying HCR an amount equal to the Royalty Cap, less any amounts we previously paid to HCR pursuant to the agreement (such amount, the “Buyout Amount”), provided that HCR may instead elect to receive 50% of the Buyout Amount and continue to receive 50% of the royalty payments under the agreement but with the Royalty Cap reduced to reflect our payment of 50% of the Buyout Amount.

In January 2022, we entered into a license agreement with Mitsubishi Tanabe Pharma Corporation (“MTPC”) to develop and commercialize ZYNLONTA in Japan, pursuant to which we granted MPTC an exclusive license under all applicable patents and know-how relating to ZYNLONTA in order to use, sell, offer for sale, import and commercialize ZYNLONTA for all cancer indications in Japan. Under the agreement, we received an upfront payment of $30 million and are eligible to up to $205 million in regulatory and net sales-based milestones as well as royalties ranging from high teens to the low twenties based on net sales of ZYNLONTA in Japan. The royalties payable to us are subject to downward adjustment in certain circumstances, including the expiration of a patent covering ZYNLONTA, generic or biosimilar competition, and required royalty payments to third parties.

MTPC will conduct clinical studies and be responsible for the development and commercialization of ZYNLONTA in Japan and bear the associated costs. At MPTC’s option, it may also participate in any clinical studies of ZYNLONTA outside of Japan by bearing a portion of the costs of such studies. In addition, MPTC agreed that it will not engage in certain activities with respect to products that are similar to ZYNLONTA.

Unless terminated earlier, the agreement terminates upon the occurrence of the earliest of (i) the expiration of the last-to-expire patent covering ZYNLONTA in Japan, (ii) the expiration of exclusivity with respect to ZYNLONTA granted to MTPC by a regulatory authority, and (iii) ten years after the first commercial sale of ZYNLONTA in Japan. In addition, MTPC may terminate the agreement at its discretion upon 180 days’ notice to us, each party may terminate the agreement for the other party’s material breach or insolvency and we may terminate the agreement if MTPC engages in certain challenges of patents covering ZYNLONTA.

In July 2022, we entered into a license agreement with Swedish Orphan Biovitrum AB (publ) (“Sobi”) to develop and commercialize ZYNLONTA in all territories other than the United States, greater China, Singapore and Japan (the territories subject to the agreement, collectively, the “Covered Territory”). Pursuant to the agreement, we granted Sobi (i) an exclusive license under applicable patents and know-how relating to ZYNLONTA in order to use, develop, sell, offer for sale, distribute, import and commercialize ZYNLONTA for all human therapeutic and diagnostic uses in the Covered Territory, (ii) a non-exclusive license under applicable patents and know-how relating to ZYNLONTA in order to package and label ZYNLONTA for all human therapeutic and diagnostic uses in the Covered Territory and (iii) a non-exclusive license under applicable patents and know-how relating to ZYNLONTA in order to manufacture and have manufactured ZYNLONTA in any territory solely for the use and sale of ZYNLONTA for human therapeutic and diagnostic uses in the Covered Territory exercisable upon Sobi assuming responsibility to manufacture or have manufactured ZYNLONTA, in each case, with the right to sublicense to affiliates and, with our written consent, other third parties and the right to subcontract to third parties. The licenses are subject to certain retained rights as specified in the agreement.

Under the agreement, we received an upfront payment of $55 million in July 2022 and $50 million in February 2023 for the approval of a Marketing Authorization Application (“MAA”) by the European Commission for ZYNLONTA in third-line DLBCL, and are eligible for up to $332.5 million in other regulatory and net sales-based milestones, as well as tiered royalties ranging from the mid-teens to the mid-twenties based on net sales of ZYNLONTA in the Covered Territory. The royalties payable to us are subject to downward adjustment in certain circumstances, including the expiration of patents covering ZYNLONTA, generic or biosimilar competition and required payments to third parties. The royalty term with respect to a product in a given country begins upon the first commercial sale of the product in the country and terminates upon the latest of (x) 10 years after the first commercial sale of the product in the country, (y) the expiration of the last-to-expire valid patent claim covering the product in the country and (z) the expiration of regulatory exclusivity for the product in the country.

Sobi will conduct development and commercialization activities with respect to ZYNLONTA in the Covered Territory and bear the associated costs, other than the costs of global clinical studies that are intended to support regulatory approval in both the United States and the Covered Territory. In addition, Sobi will co-fund 25% of the costs of certain specified global clinical studies of ZYNLONTA and have the option to co-fund additional global clinical studies in exchange for use of the data generated from such additional studies, subject to an aggregate annual co-funding cap of $10 million.

Both we and Sobi agreed that neither party would (i) during the term of the agreement until the fifth anniversary of the first MAA approval of ZYNLONTA for the first indication in the first of Germany, France, United Kingdom, Spain or Italy, engage in the development (other than non-clinical and preclinical research activities) of any competitive product directed to CD19 for the treatment of DLBCL in the Covered Territory, or (ii) during the term of the agreement, commercialize any competitive product directed to CD19 for the treatment of DLBCL in the Covered Territory. If either party acquires or is acquired by a third party that has a competitive program, then such party may continue such competitive program as long as such party establishes firewalls to operate such competitive program separately from the ZYNLONTA program.

In August 2022, we, ADC Therapeutics (UK) Limited and ADC Therapeutics America, Inc. entered into a loan agreement and guaranty (as amended, the “Loan Agreement”) with certain affiliates and/or funds managed by each of Oaktree Capital Management, L.P. and Owl Rock Capital Advisors LLC, as lenders, and Owl Rock Opportunistic Master Fund I, L.P., as administrative agent and collateral agent, pursuant to which we borrowed $120.0 million principal amount of term loans. The secured term loans are scheduled to mature on August 15, 2029 and accrue interest at an annual rate of SOFR plus 7.50% per annum or a base rate plus 6.50% per annum for the first five years of the term loans, and thereafter, at an annual rate of SOFR plus 9.25% or a base rate plus 8.25%, in each case subject to a 1.00% per annum SOFR floor.

At our election, for the first three years, we may choose to pay an amount of interest on the outstanding principal amount of term loans corresponding to up to 2.50% of the applicable interest rate in kind (in lieu of payment in cash). We are obligated to pay certain exit fees upon certain prepayments and repayments of the principal amount of the term loans. In addition, we have the right to prepay the term loans at any time subject to certain prepayment premiums applicable during the period commencing from the closing date until the fourth anniversary of the closing date. The Loan Agreement also contains certain prepayment provisions, including mandatory prepayments from the proceeds from certain asset sales, casualty events and from issuances or incurrences of debt, which may also be subject to prepayment premiums if made on or prior to the fourth anniversary of the closing date. The obligations under the Loan Agreement are secured by substantially all of our assets and those of certain of our subsidiaries and are guaranteed initially by our subsidiaries in the United States and the United Kingdom. The Loan Agreement contains customary covenants, including a covenant to maintain qualified cash of at least $60.0 million plus an amount equal to any accounts payable that remain unpaid more than ninety days after the date of the original invoice therefor, and negative covenants including limitations on indebtedness, liens, fundamental changes, asset sales, investments, dividends and other restricted payments and other matters customarily restricted in such agreements. In addition, the Loan Agreement contains a revenue covenant that, so long as the Company’s 30-day average market capitalization is less than $650 million, requires the Company achieve minimum levels of ZYNLONTA net sales in the United States, tested on a quarterly basis, which is subject to a customary cure right in favor of the Company that may be exercised by making certain prepayments and that, subject to certain limitations, may be exercised up to three times during the term of the Loan Agreement. The Loan Agreement also contains customary events of default, after which the term loan may become due and payable immediately, including payment defaults, material inaccuracy of representations and warranties, covenant defaults (including creation of any liens other than those that are expressly permitted), bankruptcy and insolvency proceedings, cross-defaults to certain other agreements, judgments against us and our subsidiaries and change in control.

Government authorities in the United States at the federal, state and local level and in other countries and jurisdictions, including the European Union, extensively regulate, among other things, the research, development, testing, manufacture, quality control, approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, post-approval monitoring and reporting, marketing and export and import of drug and biological products, such as our investigational medicines and any future investigational medicines. Generally, before a new drug or biologic can be marketed, considerable data demonstrating its quality, safety and efficacy must be obtained, organized into a format specific for each regulatory authority, submitted for review and approved by the regulatory authority.

In the United States, pharmaceutical products are subject to extensive regulation by the FDA. The FDCA and other federal and state statutes and regulations govern, among other things, the research, development, testing, manufacture, storage, recordkeeping, approval, labeling, promotion and marketing, distribution, post-approval monitoring and reporting, sampling, and import and export of pharmaceutical products. Biological products used for the prevention, treatment or cure of a disease or condition of a human being are subject to regulation under the FDCA, except that the section of the FDCA that governs the approval of new drug applications (“NDAs”) does not apply to the approval of biological products. Biological products, such as our ADC product candidates, are approved for marketing under provisions of the Public Health Service Act (the “PHSA”), via a BLA. However, the application process and requirements for approval of BLAs are very similar to those for NDAs, and biologics are associated with similar approval risks and costs as drugs. Failure to comply with applicable U.S. requirements may subject a company to a variety of administrative or judicial sanctions, such as clinical hold, FDA refusal to approve pending NDAs or BLAs, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, civil penalties, and criminal prosecution.

Our investigational medicines and any future investigational medicines must be approved by the FDA pursuant to a BLA before they may be legally marketed in the United States. The process generally involves the following:

•completion of extensive preclinical laboratory and animal studies in accordance with applicable regulations, including studies conducted in accordance with GLP requirements;

•submission to the FDA of an IND, which must become effective before human clinical trials may begin;

•approval by an IRB or independent ethics committee at each clinical trial site before each clinical trial may be commenced;

•performance of adequate and well-controlled human clinical trials in accordance with applicable IND regulations, GCP requirements and other clinical trial-related regulations to establish the safety and efficacy of the investigational product for each proposed indication;

•submission to the FDA of a BLA;

•a determination by the FDA within 60 days of its receipt of a BLA to file the submission for review;

•satisfactory completion of one or more FDA pre-approval inspections of the manufacturing facility or facilities where the biologic, or components thereof, will be produced to assess compliance with cGMP requirements to assure that the facilities, methods and controls are adequate to preserve the biologic’s identity, strength, quality and purity;

•satisfactory completion of any potential FDA audits of the clinical trial sites that generated the data in support of the BLA to assure compliance with GCPs and integrity of the clinical data;

•payment of any user fees for FDA review of the BLA;

•FDA review and approval of the BLA, including consideration of the views of any FDA advisory committee; and

•compliance with any post-approval requirements, including REMS, where applicable, and post-approval studies required by the FDA as a condition of approval.

The preclinical and clinical testing and approval process requires substantial time, effort and financial resources, and we cannot be certain that any approvals for our product candidates will be granted on a timely basis, or at all.

Before testing any biological product candidates in humans, the product candidate must undergo rigorous preclinical testing. Preclinical studies include laboratory evaluation of product chemistry and formulation, as well as in vitro and animal studies to assess the potential for adverse events and in some cases to establish a rationale for therapeutic use. The conduct of preclinical studies is subject to federal regulations and requirements, including GLP regulations for safety/toxicology studies. An IND sponsor must submit the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and plans for clinical studies, among other things, to the FDA as part of an IND. An IND is a request for authorization from the FDA to administer an investigational product to humans and must become effective before human clinical trials may begin. Some long-term preclinical testing may continue after the IND is submitted. An IND automatically becomes effective 30 days after receipt by the FDA, unless before that time the FDA raises concerns or questions related to one or more proposed clinical trials and places the trial on clinical hold. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. As a result, submission of an IND may not result in the FDA allowing clinical trials to commence.

The clinical stage of development involves the administration of the investigational product to healthy volunteers or patients under the supervision of qualified investigators, generally physicians not employed by or under the trial sponsor’s control. Clinical trials must be conducted: (i) in compliance with federal regulations; (ii) in compliance with GCPs, an international standard meant to protect the rights and health of patients and to define the roles of clinical trial sponsors, administrators, and monitors; as well as (iii) under protocols detailing, among other things, the objectives of the trial, the parameters to be used in monitoring safety, and the effectiveness criteria to be evaluated in the trial. Each protocol involving testing on U.S. patients and subsequent protocol amendments must be submitted to the FDA as part of the IND. Furthermore, each clinical trial must be reviewed and approved by an IRB for each institution at which the clinical trial will be conducted to ensure that the risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits. The IRB also approves the informed consent form that must be provided to each clinical trial subject or his or her legal representative and must monitor the clinical trial until completed.

There also are requirements governing the reporting of ongoing clinical trials and completed clinical trial results to public registries. Information about certain clinical trials, including clinical trial results, must be submitted within specific time frames for publication on the www.clinicaltrials.gov website. Information related to the product, patient population, phase of investigation, clinical trial sites and investigators, and other aspects of the clinical trial is then made public as part of the registration. Sponsors are also obligated to discuss the results of their clinical trials after completion. Disclosure of the results of these clinical trials can be delayed in certain circumstances for up to two years after the date of completion of the trial.

Competitors may use this publicly available information to gain knowledge regarding the progress of development programs.

A sponsor who wishes to conduct a clinical trial outside of the United States may, but need not, obtain FDA authorization to conduct the clinical trial under an IND. If a foreign clinical trial is not conducted under an IND, the sponsor may submit data from the clinical trial to the FDA in support of a BLA. The FDA will accept a well-designed and well-conducted foreign clinical trial not conducted under an IND if the clinical trial was conducted in accordance with GCP requirements and the FDA is able to validate the data through an onsite inspection if deemed necessary.

Clinical trials are generally conducted in three sequential phases, known as Phase 1, Phase 2 and Phase 3:

•Phase 1 clinical trials generally involve a small number of healthy volunteers or disease-affected patients who are initially exposed to a single dose and then multiple doses of the product candidate. The primary purpose of these clinical trials is to assess the metabolism, pharmacokinetics, pharmacologic action, side effect tolerability, safety of the product candidate, and, if possible, early evidence of effectiveness. Phase 1 clinical trials may be designated as Phase 1a, which may involve dose escalation to determine the maximum tolerated dose, or Phase 1b, which may involve dose expansion at one or more dose levels to determine the recommended dose level for Phase 2 clinical trials.

•Phase 2 clinical trials generally involve studies in disease-affected patients to evaluate proof of concept and/or determine the dosing regimen(s) for subsequent investigations. At the same time, safety and further pharmacokinetic and pharmacodynamic information is collected, possible adverse effects and safety risks are identified, and a preliminary evaluation of efficacy is conducted.

•Phase 3 clinical trials generally involve a large number of patients at multiple sites and are designed to provide the data necessary to demonstrate the effectiveness of the product for its intended use, its safety in use and to establish the overall benefit/risk relationship of the product, and provide an adequate basis for product labeling. In most cases, the FDA requires two adequate and well-controlled Phase 3 clinical trials to demonstrate the efficacy of the biologic.

These Phases may overlap or be combined. For example, a Phase 1/2 clinical trial may contain both a dose-escalation stage and a dose-expansion stage, the latter of which may confirm tolerability at the recommended dose for expansion in future clinical trials (as in traditional Phase 1 clinical trials) and provide insight into the anti-tumor effects of the investigational therapy in selected subpopulation(s).

Typically, during the development of oncology therapies, all subjects enrolled in Phase 1 clinical trials are disease-affected patients and, as a result, considerably more information on clinical activity may be collected during such trials than during Phase 1 clinical trials for non-oncology therapies. A single Phase 3 or Phase 2 trial may be sufficient in rare instances, including (1) where the trial is a large, multicenter trial demonstrating internal consistency and a statistically very persuasive finding of a clinically meaningful effect on mortality, irreversible morbidity or prevention of a disease with a potentially serious outcome and confirmation of the result in a second trial would be practically or ethically impossible or (2) when in conjunction with other confirmatory evidence. Approval on the basis of a single trial may be subject to the requirement of additional post-approval studies.

The manufacturer of an investigational drug in a Phase 2 or Phase 3 clinical trial for a serious or life-threatening disease is required to make available, such as by posting on its website, its policy on evaluating and responding to requests for expanded access to such investigational drug.

Phase 1, Phase 2, Phase 3 and other types of clinical trials may not be completed successfully within any specified period, if at all. The FDA, the IRB, or the sponsor may suspend or terminate a clinical trial at any time on various grounds, including non-compliance with regulatory requirements or a finding that the patients are being exposed to an unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution if the clinical trial is not being conducted in accordance with the IRB’s requirements or if the drug or biologic has been associated with unexpected serious harm to patients. Additionally, some clinical trials are overseen by an independent group of qualified experts organized by the clinical trial sponsor, known as a data safety monitoring board or committee. This group provides authorization for whether a trial may move forward at designated checkpoints based on access to certain data from the trial.

Concurrent with clinical trials, companies usually complete additional animal studies and also must develop additional information about the chemistry and physical characteristics of the drug or biologic as well as finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements.

The manufacturing process must be capable of consistently producing quality batches of the product and, among other things, companies must develop methods for testing the identity, strength, quality, potency, and purity of the final product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the investigational medicines do not undergo unacceptable deterioration over their shelf life.

Following completion of the clinical trials, the results of preclinical studies and clinical trials are submitted to the FDA as part of a BLA, along with proposed labeling, chemistry and manufacturing information to ensure product quality and other relevant data. To support marketing approval, the data submitted must be sufficient in quality and quantity to establish the safety and efficacy of the investigational product to the satisfaction of the FDA. FDA approval of a BLA must be obtained before a biologic or drug may be marketed in the United States.

The cost of preparing and submitting a BLA is substantial. Under the Prescription Drug User Fee Act (“PDUFA”), each BLA must be accompanied by a substantial user fee. The FDA adjusts the PDUFA user fees on an annual basis. Fee waivers or reductions are available in certain circumstances, including a waiver of the application fee for the first application filed by a small business. Additionally, no user fees are assessed on BLAs for products designated as orphan drugs, unless the product also includes a non-orphan indication. The applicant under an approved BLA is also subject to an annual program fee.

The FDA reviews all submitted BLAs before it files them and may request additional information. The FDA must make a decision on filing a BLA within 60 days of receipt, and such decision could include a refusal to file by the FDA. Once the submission is filed, the FDA begins an in-depth review of the BLA. Under the goals and policies agreed to by the FDA under PDUFA, the FDA has 10 months, from the filing date, in which to complete its initial review of an original BLA for a new molecular entity and respond to the applicant, and six months from the filing date of an original BLA designated for priority review. The review process for both standard and priority review may be extended by the FDA for three additional months to consider certain late-submitted information or information intended to clarify information already provided in the submission. The FDA does not always meet its PDUFA goal dates for standard and priority BLAs, and the review process can be extended by FDA requests for additional information or clarification.

Before approving a BLA, the FDA will conduct a pre-approval inspection of the manufacturing facilities for the new product to determine whether they comply with cGMP requirements. The FDA will not approve the product unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications.

The FDA also may audit data from clinical trials to ensure compliance with GCP requirements and the integrity of the data supporting safety and efficacy. Additionally, the FDA may refer applications for novel products or products that present difficult questions of safety or efficacy to an advisory committee, typically a panel that includes clinicians and other experts, for review, evaluation and a recommendation as to whether the application should be approved and under what conditions, if any. The FDA is not bound by recommendations of an advisory committee, but it generally follows such recommendations when making decisions on approval. The FDA likely will reanalyze the clinical trial data, which could result in extensive discussions between the FDA and the applicant during the review process.

After the FDA evaluates a BLA, it will issue either an approval letter or a Complete Response Letter. An approval letter authorizes commercial marketing of the biologic with specific prescribing information for specific indications. A Complete Response Letter indicates that the review cycle of the application is complete, and the application will not be approved in its present form. A Complete Response Letter generally outlines the deficiencies in the BLA and may require additional clinical data, additional pivotal clinical trial(s), and/or other significant and time-consuming requirements related to clinical trials, preclinical studies or manufacturing in order for the FDA to reconsider the application. If a Complete Response Letter is issued, the applicant may either resubmit the BLA, addressing all of the deficiencies identified in the letter, or withdraw the application or request an opportunity for a hearing. The FDA has committed to reviewing such resubmissions in two or six months, depending on the type of information included. Even if such data and information are submitted, the FDA may decide that the BLA does not satisfy the criteria for approval.

As a condition of BLA approval, the FDA may require a risk evaluation and mitigation strategy (“REMS”) to help ensure that the benefits of the biologic outweigh the potential risks to patients. A REMS can include medication guides, communication plans for healthcare professionals, and elements to assure a product’s safe use (“ETASU”). An ETASU can include, but is not limited to, special training or certification for prescribing or dispensing the product, dispensing the product only under certain circumstances, special monitoring, and the use of patient-specific registries. The requirement for a REMS can materially affect the potential market and profitability of the product.

Moreover, the FDA may require substantial post-approval testing and surveillance to monitor the product’s safety or efficacy.

Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biological product intended to treat a rare disease or condition, which is generally a disease or condition that affects fewer than 200,000 individuals in the United States, or more than 200,000 individuals in the United States but for which there is no reasonable expectation that the cost of developing and making the product for this type of disease or condition will be recovered from sales of the product in the United States.

Orphan drug designation must be requested before submitting a BLA. After the FDA grants orphan drug designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan drug designation on its own does not convey any advantage in or shorten the duration of the regulatory review and approval process.

If a product that has orphan designation subsequently receives the first FDA approval for the disease or condition for which it has such designation, the product is entitled to orphan drug exclusivity, which means that the FDA may not approve any other applications to market the same product for the same indication for seven years from the date of such approval, except in limited circumstances, such as a showing of clinical superiority to the product with orphan exclusivity by means of greater effectiveness, greater safety, or providing a major contribution to patient care, or in instances of drug supply issues. Competitors, however, may receive approval of either a different product for the same indication or the same product for a different indication. In the latter case, because healthcare professionals are free to prescribe products for off-label uses, the competitor’s product could be used for the orphan indication despite another product’s orphan exclusivity.

FDA’s determination of whether two ADCs are the same product for purposes of orphan drug exclusivity is based on a determination of sameness of the monoclonal antibody element and the functional element of the conjugated molecule. Two ADCs are deemed to be the same product if the complementarity determining region sequences of the antibody and the functional element of the conjugated molecule are the same. A difference in either of those two elements can result in a determination that the molecules are different.

The FDA is authorized to designate certain products for expedited review if they are intended to address an unmet medical need in the treatment of a serious or life-threatening disease or condition.

Fast track designation may be granted for products that are intended to treat a serious or life-threatening disease or condition for which there is no effective treatment, and preclinical or clinical data demonstrate the potential to address unmet medical needs for the condition. Fast track designation applies to both the product and the specific indication for which it is being studied. The sponsor of a new biologic candidate can request the FDA to designate the candidate for a specific indication for fast track status concurrent with, or after, the submission of the IND for the candidate. The FDA must determine if the biologic candidate qualifies for fast track designation within 60 days of receipt of the sponsor’s request. For fast track products, sponsors may have greater interactions with the FDA and the FDA may initiate review of sections of a fast track product’s BLA before the application is complete. This “rolling review” is available if the FDA determines, after preliminary evaluation of clinical data submitted by the sponsor, that a fast track product may be effective. The sponsor must also provide, and the FDA must approve, a schedule for the submission of the remaining information and the sponsor must pay applicable user fees. Any product submitted to the FDA for marketing, including under a fast track program, may be eligible for other types of FDA programs intended to expedite development and review, such as priority review and accelerated approval.

Breakthrough therapy designation may be granted for products that are intended, alone or in combination with one or more other products, to treat a serious or life-threatening condition and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over currently approved therapies on one or more clinically significant endpoints. Under the breakthrough therapy program, the sponsor of a new biologic candidate may request that the FDA designate the candidate for a specific indication as a breakthrough therapy concurrent with, or after, the submission of the IND for the biologic candidate. The FDA must determine if the biological product qualifies for breakthrough therapy designation within 60 days of receipt of the sponsor’s request. The FDA may take certain actions with respect to breakthrough therapies, including holding meetings with the sponsor throughout the development process, providing timely advice to the product sponsor regarding development and approval, involving more senior staff in the review process, assigning a cross-disciplinary project lead for the review team and taking other steps to design the clinical studies in an efficient manner.

Priority review may be granted for products that are intended to treat a serious or life-threatening condition and, if approved, would provide a significant improvement in safety and effectiveness compared to available therapies. The FDA will attempt to direct additional resources to the evaluation of an application designated for priority review in an effort to facilitate the review.

Accelerated approval may be granted for products that are intended to treat a serious or life-threatening condition and that generally provide a meaningful therapeutic advantage to patients over existing treatments. A product eligible for accelerated approval may be approved on the basis of either a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity or prevalence of the condition and the availability or lack of alternative treatments. In clinical trials, a surrogate endpoint is a measurement of laboratory or clinical signs of a disease or condition that substitutes for a direct measurement of how a patient feels, functions, or survives. The accelerated approval pathway is most often used in settings in which the course of a disease is long and an extended period of time is required to measure the intended clinical benefit of a product, even if the effect on the surrogate or intermediate clinical endpoint occurs rapidly. Thus, accelerated approval has been used extensively in the development and approval of products for treatment of a variety of cancers in which the goal of therapy is generally to improve survival or decrease morbidity and the duration of the typical disease course requires lengthy and sometimes large studies to demonstrate a clinical or survival benefit. The accelerated approval pathway is contingent on a sponsor’s agreement to conduct additional post-approval confirmatory studies to verify and describe the product’s clinical benefit. These confirmatory trials must be completed with due diligence, and, in some cases, the FDA may require that the trial be designed, initiated, and/or fully enrolled prior to approval. Failure to conduct required post-approval studies, or to confirm a clinical benefit during post-marketing studies, would allow the FDA to withdraw the product from the market on an expedited basis. All promotional materials for product candidates approved under accelerated regulations are subject to prior review by the FDA. Pursuant to the Food and Drug Omnibus Reform Act (“FDORA”), the FDA is authorized to require a post-approval study to be underway prior to approval or within a specified time period following approval. FDORA also requires the FDA to specify conditions of any required post-approval study, which may include milestones such as a target date of study completion and requires sponsors to submit progress reports for required post-approval studies and any conditions required by FDA not later than 180 days following approval and not less frequently than every 180 days thereafter until completion or termination of the study. FDORA enables the FDA to initiate enforcement action for the failure to conduct with due diligence a required post-approval study, including a failure to meet any required conditions specified by the FDA or to submit timely reports.

Even if a product qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or the time period for FDA review or approval may not be shortened. Furthermore, fast track designation, breakthrough therapy designation, priority review and accelerated approval do not change the standards for approval but may expedite the development or approval process.

To help reduce the increased risk of the introduction of adventitious agents, the PHSA emphasizes the importance of manufacturing controls for products whose attributes cannot be precisely defined. The PHSA also provides authority to the FDA to immediately suspend licenses in situations where there exists a danger to public health, to prepare or procure products in the event of shortages and critical public health needs, and to authorize the creation and enforcement of regulations to prevent the introduction or spread of communicable diseases in the United States and between states.

After a BLA is approved, the product may also be subject to official lot release as a condition of approval. As part of the manufacturing process, the manufacturer is required to perform certain tests on each lot of the product before it is released for distribution. If the product is subject to official release by the FDA, the manufacturer submits samples of each lot of product to the FDA together with a release protocol showing a summary of the history of manufacture of the lot and the results of all of the manufacturer’s tests performed on the lot. The FDA may also perform certain confirmatory tests on lots of some products, such as viral vaccines, before releasing the lots for distribution by the manufacturer. In addition, the FDA conducts laboratory research related to the regulatory standards on the safety, purity, potency, and effectiveness of biological products. As with drugs, after approval of biologics, manufacturers must address any safety issues that arise, are subject to recalls or a halt in manufacturing, and are subject to periodic inspection after approval.

Under the Pediatric Research Equity Act (“PREA), BLAs or supplements to BLAs must contain data to assess the safety and effectiveness of the biological product for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the biological product is safe and effective. The FDA may grant full or partial waivers, or deferrals, for submission of data. Unless otherwise required by regulation, PREA generally does not apply to any biological product for an indication for which orphan designation has been granted. However, PREA applies to BLAs for orphan-designated biologics if the biologic is a molecularly targeted cancer product intended for the treatment of an adult cancer and is directed at a molecular target that FDA has determined is substantially relevant to the growth or progression of a pediatric cancer.

The Best Pharmaceuticals for Children Act (the “BPCA”) provides a six-month extension of non-patent exclusivity for a biologic if certain conditions are met. Conditions for exclusivity include the FDA’s determination that information relating to the use of a new biologic in the pediatric population may produce health benefits in that population, the FDA making a written request for pediatric studies, and the applicant agreeing to perform, and reporting on, the requested studies within the statutory time frame. Applications under the BPCA are treated as priority applications, with all of the benefits that designation confers.

Once a BLA is approved, a product will be subject to certain post-approval requirements. For instance, the FDA closely regulates the post-approval marketing and promotion of biologics, including standards and regulations for direct-to-consumer advertising, off-label promotion, industry-sponsored scientific and educational activities and promotional activities involving the Internet. Biologics may be marketed only for the approved indications and in a manner consistent with the provisions of the approved labeling. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses, and a company that is found to have improperly promoted off-label uses may be subject to significant liability, including investigation by federal and state authorities.

Adverse event reporting and submission of periodic safety summary reports is required following FDA approval of a BLA. The FDA also may require post-marketing testing, known as Phase 4 testing, REMS, and surveillance to monitor the effects of an approved product, or the FDA may place conditions on an approval that could restrict the distribution or use of the product. In addition, quality control, biological product manufacture, packaging, and labeling procedures must continue to conform to cGMPs after approval. Biologic manufacturers and certain of their subcontractors are required to register their establishments with the FDA and certain state agencies. Registration with the FDA subjects entities to periodic unannounced inspections by the FDA, during which the agency inspects a biologic product’s manufacturing facilities to assess compliance with cGMPs. Accordingly, manufacturers must continue to expend time, money, and effort in the areas of production and quality-control to maintain compliance with cGMPs. Regulatory authorities may withdraw product approvals or request product recalls if a company fails to comply with required regulatory standards, if it encounters problems following initial marketing, or if previously unrecognized problems are subsequently discovered.

Once an approval is granted, the FDA may withdraw the approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information, imposition of post-market studies or clinical studies to assess new safety risks or imposition of distribution or other restrictions under a REMS program. Other potential consequences include, among other things:

•restrictions on the marketing or manufacturing of the product, suspension of the approval, complete withdrawal of the product from the market or product recalls;

•fines, warning or other enforcement-related letters or holds on post-approval clinical studies;

•refusal of the FDA to approve pending BLAs or supplements to approved BLAs, or suspension or revocation of product license approvals;

•product seizure or detention, or refusal to permit the import or export of products; or

•injunctions or the imposition of civil or criminal penalties.

Certain changes to an approved BLA or the conditions under which it was approved, including changes in its indications, safety information, labeling, or manufacturing processes or facilities, require submission and FDA approval of a new BLA or BLA supplement before the product can be marketed or distributed with those changes. A BLA supplement for a new indication typically requires clinical data similar to that in the original application. The FDA uses the same procedures and actions in reviewing BLA supplements as it does in reviewing original BLAs.

Depending upon the timing, duration, and specifics of FDA approval of our product candidates, some of our U.S. patents may be eligible for limited patent term extension under the Hatch-Waxman Amendments. The Hatch Waxman Amendments provide for a patent term extension of up to five years as compensation for patent term lost during the FDA regulatory review process. Patent term extension, however, cannot extend the remaining term of a patent beyond a total of 14 years from the product’s approval date. The patent term extension period is generally one half the time between the effective date of an IND and the submission date of a BLA, plus the time between the submission date of a BLA and the approval of that application, up to five years. If the extended patent was issued during the development of review period, the calculation begins from the date of patent issuance. The review period is reduced by any time during which the applicant failed to exercise due diligence. Only one patent applicable to an approved drug is eligible for such an extension, only those claims covering the approved drug, a method for using it, or a method for manufacturing it may be extended and the application for the extension must be submitted prior to the expiration of the patent. Such application must be submitted within 60 days of approval. The USPTO, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration. In the future, we or our licensors may apply for patent term extension for our owned or licensed patents to add patent life beyond their current expiration date, depending on the expected length of the clinical trials and other factors involved in the filing of the relevant BLA. However, an extension might not be granted because of, for example, failing to exercise due diligence during the testing phase or regulatory review process, failing to apply within applicable deadlines, failing to apply prior to expiration of relevant patents or otherwise failing to satisfy applicable requirements. Moreover, the applicable time period or the scope of patent protection afforded could be less than requested.

The BPCIA created an abbreviated approval pathway for biological products shown to be biosimilar to, or interchangeable with, an FDA-licensed reference biological product. Biosimilarity, which requires that the biological product be highly similar to the reference product notwithstanding minor differences in clinically inactive components and that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity and potency, can be shown through analytical studies, animal studies and/or toxicity studies, and a clinical trial or trials. Interchangeability requires that a biological product be biosimilar to the reference product and that the product can be expected to produce the same clinical results as the reference product in any given patient and, for products administered multiple times to an individual, that the product and the reference product may be alternated or switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biological product without such alternation or switch.

A reference biological product is granted 12 years of data exclusivity from the time of first licensure of the product and the FDA will not accept an application for a biosimilar or interchangeable product based on the reference biological product until four years after the date of first licensure of the reference product. “First licensure” typically means the initial date the particular product at issue was licensed in the United States. Date of first licensure does not include the date of licensure of (and a new period of exclusivity is not available for) a biological product if the licensure is for a supplement for the biological product or for a subsequent application by the same sponsor or manufacturer of the biological product (or licensor, predecessor in interest, or other related entity) for a change (not including a modification to the structure of the biological product) that results in a new indication, route of administration, dosing schedule, dosage form, delivery system, delivery device or strength, or for a modification to the structure of the biological product that does not result in a change in safety, purity or potency.

The European Medicines Agency (the “EMA”) is a decentralized scientific agency of the European Union. It coordinates the evaluation and monitoring of centrally authorized medicinal products. It is responsible for the scientific evaluation of applications for EU marketing authorizations, as well as the development of technical guidance and the provision of scientific advice to sponsors. The EMA decentralizes its scientific assessment of medicines by working through a network of about 4,500 experts throughout the European Union, nominated by the member states. The EMA draws on resources of over 40 National Competent Authorities of European Union member states.

The process regarding approval of medicinal products in the European Union follows roughly the same lines as in the United States and likewise generally involves satisfactorily completing each of the following:

•preclinical laboratory tests, animal studies and formulation studies all performed in accordance with the applicable EU Good Laboratory Practice regulations;

•submission to the relevant national authorities of a clinical trial application (“CTA”) for each trial in humans, which must be approved before the trial may begin in each country where patient enrollment is planned;

•performance of adequate and well-controlled clinical trials to establish the safety and efficacy of the product for each proposed indication;

•submission to the relevant competent authorities of an MAA, which includes the data supporting safety and efficacy as well as detailed information on the manufacture and composition of the product in clinical development and proposed labelling;

•satisfactory completion of an inspection by the relevant national authorities of the manufacturing facility or facilities, including those of third parties, at which the product is produced to assess compliance with strictly enforced cGMP;

•potential audits of the non-clinical and clinical trial sites that generated the data in support of the MAA; and

•review and approval by the relevant competent authority of the MAA before any commercial marketing, sale or shipment of the product.

Preclinical tests include laboratory evaluations of product chemistry, formulation and stability, as well as studies to evaluate toxicity in animal studies, in order to assess the quality and potential safety and efficacy of the product. The conduct of the preclinical tests and formulation of the compounds for testing must comply with the relevant international, EU and national legislation, regulations and guidelines. The results of the preclinical tests, together with relevant manufacturing information and analytical data, are submitted as part of the CTA.

Pursuant to the Clinical Trials Directive 2001/20/EC, as amended (the “Clinical Trials Directive”), a system for the approval of clinical trials in the European Union has been implemented through national legislation of the member states. Under this system, approval must be obtained from the competent national authority of each European Union member state in which a clinical trial is planned to be conducted. To this end, a CTA is submitted, which must be supported by an investigational medicinal product dossier and further supporting information prescribed by the Clinical Trials Directive and other applicable guidance documents including, but not limited to, the clinical trial protocol. Furthermore, a clinical trial may only be started after a central ethics committee has issued a favorable opinion on the clinical trial application in that country.

Directive 2001/20/EC has been replaced by Regulation (EU) No. 536/2014, which became effective on January 31, 2022. The Regulation introduces an authorization procedure based on a single submission via a single EU portal, an assessment procedure leading to a single decision, as well as transparency requirements (the proactive publication of clinical trial data in the EU database). Since October 2016, based on its Policy 0070, the EMA has been publishing clinical data submitted by pharmaceutical companies to support their MAA for human medicines under this centralized procedure.

Manufacturing and import into the EU of investigational medicinal products is subject to the holding of appropriate authorizations and must be carried out in accordance with cGMP.

Authorization to market a product in the European Union member states proceeds under one of four procedures: a centralized authorization procedure, a mutual recognition procedure, a decentralized procedure or a national procedure. Since our products by their virtue of being antibody-based biologics fall under the centralized procedure, only this procedure will be described here.

Certain drugs, including medicinal products developed by means of biotechnological processes, must be approved via the centralized authorization procedure for marketing authorization. A successful application under the centralized authorization procedure results in a marketing authorization from the European Commission, which is automatically valid in all European Union member states. The other European Economic Area member states (namely Norway, Iceland and Liechtenstein) are also obligated to recognize the European Commission decision. The EMA and the European Commission administer the centralized authorization procedure.

Under the centralized authorization procedure, the Committee for Medicinal Products for Human Use (the “CHMP”) serves as the scientific committee that renders opinions about the safety, efficacy and quality of human products on behalf of the EMA. The CHMP is composed of experts nominated by each member state’s national health authority, with one of them appointed to act as Rapporteur for the co-ordination of the evaluation with the assistance of a further member of the CHMP acting as a Co-Rapporteur. The CHMP is required to issue an opinion within 210 days of receipt of a valid application, though the clock is stopped if it is necessary to ask the applicant for clarification or further supporting data. The process is complex and involves extensive consultation with the regulatory authorities of member states and a number of experts. Once the procedure is completed, a European Public Assessment Report is produced. If the CHMP concludes that the quality, safety and efficacy of the medicinal product is sufficiently proven, it adopts a positive opinion. The CHMP’s opinion is sent to the European Commission, which uses the opinion as the basis for its decision whether or not to grant a marketing authorization. If the opinion is negative, information is given as to the grounds on which this conclusion was reached.

After a drug has been authorized and launched, it is a condition of maintaining the marketing authorization that all aspects relating to its quality, safety and efficacy must be kept under review. Sanctions may be imposed for failure to adhere to the conditions of the marketing authorization. In extreme cases, the authorization may be revoked, resulting in withdrawal of the product from sale.

As per Article 14(7) of Regulation (EC) 726/2004, a medicine that would fulfill an unmet medical need may, if its immediate availability is in the interest of public health, be granted a conditional marketing authorization on the basis of less complete clinical data than are normally required, subject to specific obligations being imposed on the authorization holder. These specific obligations are to be reviewed annually by the EMA. The list of these obligations shall be made publicly accessible. Such an authorization shall be valid for one year, on a renewable basis.

When an application is submitted for a marketing authorization in respect of a drug for human use which is of major interest from the point of view of public health and in particular from the viewpoint of therapeutic innovation, the applicant may request an accelerated assessment procedure pursuant to Article 14(9) of Regulation (EC) 726/2004. Under the accelerated assessment procedure, the CHMP is required to issue an opinion within 150 days of receipt of a valid application, subject to clock stops. We believe that some of the disease indications in which our product candidates are currently being or may be developed in the future qualify for this provision, and we will take advantage of this provision as appropriate.

A full marketing authorization is initially valid for five years and may then be renewed on the basis of a re-evaluation of the risk-benefit balance by the EMA or by the competent authority of the authorizing member state. To this end, the marketing authorization holder shall provide the EMA or the competent authority with a consolidated version of the file in respect of quality, safety and efficacy, including all variants introduced since the marketing authorization was granted, at least nine months before the expiry date of the marketing authorization. Once renewed, the marketing authorization shall be valid for an unlimited period, unless the European Commission or the competent authority decides, on justified grounds relating to pharmacovigilance, to proceed with one additional five-year renewal. Any authorization which is not followed by the actual placing of the drug on the EU market (in case of centralized procedure) or on the market of the authorizing member state within three years after authorization shall cease to be valid (the so-called “sunset clause”).

Without prejudice to the law on the protection of industrial and commercial property, marketing authorizations for new medicinal products benefit from an 8+2+1 year period of regulatory protection. This regime consists of a regulatory data protection period of eight years plus a concurrent market exclusivity of 10 years plus an additional market exclusivity of one further year if, during the first eight years of those 10 years, the marketing approval holder obtains an approval for one or more new therapeutic indications which, during the scientific evaluation prior to their approval, are determined to bring a significant clinical benefit in comparison with existing therapies. Under the current rules, a third party may reference the preclinical and clinical data of the reference product beginning eight years after first approval, but the third party may market a generic version of the reference product after only 10 (or 11) years have lapsed.

Regulation (EC) 141/2000 states that a drug shall be designated as an orphan drug if its sponsor can establish (i) that it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition affecting not more than five in 10,000 persons in the European Union when the application is made, or that it is intended for the diagnosis, prevention or treatment of a life-threatening, seriously debilitating or serious and chronic condition in the European Union and that without incentives it is unlikely that the marketing of the drug in the European Union would generate sufficient return to justify the necessary investment; and (ii) that there exists no satisfactory method of diagnosis, prevention or treatment of the condition in question that has been authorized in the European Union or, if such method exists, the drug will be of significant benefit to those affected by that condition.

Regulation (EC) 847/2000 sets out criteria for the designation of orphan drugs. An application for designation as an orphan product can be made any time prior to the filing of an application for approval to market the product. Marketing authorization for an orphan drug leads to a 10-year period of market exclusivity, which means that no similar medicinal product can be authorized in the same indication. This period may, however, be reduced to six years if, at the end of the fifth year, it is established that the product no longer meets the criteria for orphan drug designation, for example because the product is sufficiently profitable not to justify continued market exclusivity. In addition, derogation from market exclusivity may be granted on an individual basis in very select cases, such as consent from the marketing authorization holder, inability to supply sufficient quantities of the product or demonstration of “clinically relevant superiority” by a similar medicinal product. Medicinal products designated as orphan drugs pursuant to Regulation (EC) 141/2000 are eligible for incentives made available by the European Union and by the member states to support research into, and the development and availability of, orphan drugs.

If the MAA of a medicinal product designated as an orphan drug pursuant to Regulation (EC) 141/2000 includes the results of all studies conducted in compliance with an agreed PIP, and a corresponding statement is subsequently included in the marketing authorization granted, the 10-year period of market exclusivity will be extended to 12 years.

The collection, transfer, processing and other use of personal information, including health data, in the European Union is governed by the GDPR. This directive imposes several requirements relating to (i) obtaining, in some situations, the consent of the individuals to whom the personal data relates, (ii) the information provided to the individuals about how their personal information is used, (iii) ensuring the security and confidentiality of the personal data, (iv) the obligation to notify regulatory authorities and affected individuals of personal data breaches, (v) extensive internal privacy governance obligations and (vi) obligations to honor rights of individuals in relation to their personal data (for example, the right to access, correct and delete their data). The GDPR prohibits the transfer of personal data to countries outside the European Economic Area, such as the United States, which are not considered by the European Commission to provide an adequate level of data protection. Switzerland has adopted similar restrictions. Failure to comply with the requirements of the GDPR and the related national data protection laws of the European Union member states may result in fines and other administrative penalties. The GDPR introduces new data protection requirements in the EU and substantial fines for breaches of the data protection rules. The GDPR and related data protection laws may impose additional responsibility and liability in relation to personal data that we collect and process, and we may be required to put in place additional mechanisms ensuring compliance with such rules. This may be onerous and adversely affect our business, financial condition, results of operations, and prospects.

Much like the Anti-Kickback Statute prohibition in the United States, the provision of benefits or advantages to physicians to induce or encourage the prescription, recommendation, endorsement, purchase, supply, order or use of medicinal products is also prohibited in the EU. The provision of benefits or advantages to physicians is governed by the national anti-bribery laws of European Union member states, such as the U.K. Bribery Act 2010. Infringement of these laws could result in substantial fines and imprisonment.

Payments made to physicians in certain European Union member states must be publicly disclosed. Moreover, agreements with physicians often must be the subject of prior notification and approval by the physician’s employer, his or her competent professional organization, and/or the regulatory authorities of the individual European Union member states. These requirements are provided in the national laws, industry codes or professional codes of conduct, applicable in the European Union member states.

Failure to comply with these requirements could result in reputational risk, public reprimands, administrative penalties, fines or imprisonment.

In addition to regulations in the United States and Europe, a variety of foreign regulations govern clinical trials, commercial sales and distribution of product candidates. The approval process varies from country to country, and the time to approval may be longer or shorter than that required for FDA or European Commission approval.

For other material healthcare laws and regulations that affect our business, see “Item 1A. Risk Factors—Risks Related to Regulatory Approval and Government Regulation.”

We and our third-party contractors are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the use, generation, manufacture, distribution, storage, handling, treatment, remediation and disposal of hazardous materials and wastes. Hazardous chemicals, including flammable and biological materials, are involved in certain aspects of our business, and we cannot eliminate the risk of injury or contamination from the use, generation, manufacture, distribution, storage, handling, treatment or disposal of hazardous materials and wastes. In particular, our product candidates use PBDs, which are highly potent cytotoxins that require special handling by our and our contractors’ staff. In the event of contamination or injury, or failure to comply with environmental, health and safety laws and regulations, we could be held liable for any resulting damages, fines and penalties associated with such liability, which could exceed our assets and resources. Environmental, health and safety laws and regulations are becoming increasingly more stringent. We may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations.

Federal law requires that a pharmaceutical manufacturer, as a condition of having its products receive federal reimbursement under Medicaid and Medicare Part B, must pay quarterly rebates to state Medicaid programs for all units of its covered outpatient drugs dispensed to Medicaid beneficiaries and paid for by a state Medicaid program under either a fee-for-service arrangement or through a managed care organization. This federal requirement is effectuated through a Medicaid drug rebate agreement between the manufacturer and the Secretary of U.S. Department of Health and Human Services (“HHS”). CMS administers the Medicaid drug rebate agreements with manufacturers and which provide, among other things, that the drug manufacturer will pay rebates to each state Medicaid agency on a quarterly basis and report certain price information on a monthly and quarterly basis the rebates are based on the average manufacturer price (AMP) reported to CMS by manufacturers for their covered outpatient drugs. For non-innovator products, generally generic drugs marketed under abbreviated ANDAs, the rebate amount is 13% of the AMP for the quarter. The AMP is the weighted average of prices paid to the manufacturer as defined by the applicable regulations. For innovator products (i.e., drugs that are marketed under NDAs or BLAs), the rebate amount is the greater of 23.1% of the AMP for the quarter or the difference between such AMP and the best price for that same quarter. The best price is essentially the lowest price available to non-governmental entities after accounting for discounts and rebates. Innovator products may also be subject to an additional rebate that is based on the amount, if any, by which the product’s AMP for a given quarter exceeds the inflation-adjusted baseline AMP, which for most drugs is the AMP for the first full quarter after launch. Since 2017, non-innovator products are also subject to an additional rebate. To date, the rebate amount for a drug has been capped at 100% of the AMP; however, effective January 1, 2024, this cap will be eliminated, which means that a manufacturer could pay a total rebate amount on a unit of the drug that is greater than the average price the manufacturer receives for the drug.

The terms of participation in the Medicaid drug rebate program impose an obligation to correct the prices reported in previous quarters, as may be necessary. Any such corrections could result in additional or lesser rebate liability, depending on the direction of the correction. In addition to retroactive rebates, if a manufacturer were found to have knowingly submitted false information to the government, federal law provides for civil monetary penalties for failing to provide required information, late submission of required information, and false information.

A manufacturer must also participate in a federal program known as the 340B drug pricing program for federal funds to be available to pay for the manufacturer’s drugs and biological products under Medicaid and Medicare Part B. Under this program, the participating manufacturer agrees to charge certain safety net healthcare providers no more than an established discounted price for its covered outpatient drugs.

The formula for determining the discounted price is defined by statute and is based on the AMP and the unit rebate amount as calculated under the Medicaid drug rebate program, discussed above. Manufacturers are required to report pricing information to the Health Resources and Services Administration (HRSA) on a quarterly basis. HRSA has also issued regulations relating to the calculation of the ceiling price as well as imposition of civil monetary penalties for each instance of knowingly and intentionally overcharging a 340B covered entity. There is ongoing litigation that may restrict the number of third-party contract pharmacies that can dispense drugs that manufacturers sell to 340B covered entities and who qualify as patients of these 340B covered entities. The outcome of this litigation may change the scope of the 340B program in coming years.

Federal law also requires that manufacturers report data on a quarterly basis to CMS regarding the pricing of drugs that are separately reimbursable under Medicare Part B. These are generally drugs, such as injectable products, that are administered “incident to” a physician service and are not generally self-administered. The average selling price (ASP) reported by CMS manufacturers is the basis for reimbursement to providers for drugs covered under Medicare Part B. Under the Inflation Reduction Act (“IRA”), as of January 1, 2023, manufacturers are also required to provide quarterly rebates for certain single-source drugs and biologics (including biosimilars) covered under Medicare Part B with ASPs that increase faster than the rate of inflation. This requirement started on January 1, 2023, for drugs approved on or before December 1, 2020, and begins six quarters after a drug is first marketed for all other drugs. As with the Medicaid drug rebate program, Federal law provides for civil monetary penalties for failing to provide required information, late submission of required information, and false information.

The Infrastructure Investment and Jobs Act added a requirement, effective January 1, 2023, for manufacturers of certain single-source drugs (including biologics and biosimilars) separately paid for under Medicare Part B for at least 18 months and marketed in single-dose containers or packages (known as refundable single-dose container or single-use package drugs) to provide annual refunds for any portions of the dispensed drug that are unused and discarded if those unused or discarded portions exceed an applicable percentage defined by statute or regulation. Manufacturers will be subject to periodic audits and those that fail to pay refunds for their refundable single-dose container or single-use package drugs shall be subject to civil monetary penalties.

Federal law requires that manufacturers with covered drugs under Medicare Part D pay a portion of the enrollee’s copay via a rebate to CMS. Medicare Part D provides prescription drug benefits for seniors and people with disabilities. The Medicare Part D benefit design and the portion of the enrollee’s co-pay that manufacturers are required to pay has changed over time. The current manufacturer responsibility which began in 2019 is 70% of the coverage gap portion of the enrollee’s copay (amount between the initial coverage limit and start of catastrophic coverage). Medicare Part D enrollees once had a gap in their coverage (between the initial coverage limit and the point at which catastrophic coverage begins) where Medicare did not cover their prescription drug costs, known as the coverage gap. However, beginning in 2019, Medicare Part D enrollees paid 25% of brand drug costs after they reached the initial coverage limit — the same percentage they were responsible for before they reached that limit — thereby closing the coverage gap from the enrollee’s point of view. Most of the cost of closing the coverage gap is being borne by innovator companies and the government through subsidies. Each manufacturer of drugs approved under NDAs or BLAs is required to enter into a Medicare Part D coverage gap discount agreement and provide a 70% discount on those drugs dispensed to Medicare Part D enrollees in the coverage gap, in order for its drugs to be reimbursed by Medicare Part D. Beginning in 2025, the IRA eliminates the coverage gap under Medicare Part D by significantly lowering the enrollee maximum out-of-pocket cost and requiring manufacturers to subsidize, through a newly established manufacturer discount program which requires manufacturers to pay 10% of Part D enrollees’ prescription costs for brand drugs above a deductible and below the out-of-pocket maximum, and 20% once the out-of-pocket maximum has been reached. Although these discounts represent a lower percentage of enrollees’ costs than the current discounts required below the out-of-pocket maximum (that is, in the coverage gap phase of Part D coverage), the new manufacturer contribution required above the out-of-pocket maximum could be considerable for very high-cost patients and the total contributions by manufacturers to a Part D enrollee’s drug expenses may exceed those currently provided. Effective October 1, 2022, the IRA also requires manufacturers to provide annual Medicare Part D rebates for single-source drugs and biological products with prices that increase faster than the rate of inflation.

The IRA also allows HHS to directly negotiate the selling price of a statutorily specified number of drugs and biologics each year that CMS reimburses under Medicare Part B and Part D. Only high-expenditure single-source biologics that have been approved for at least 11 years (7 years for single-source drugs) can qualify for negotiation, with the negotiated price taking effect two years after the selection year. Negotiations for Medicare Part D products begin in 2024 with the negotiated price taking effect in 2026, and negotiations for Medicare Part B products begin in 2026 with the negotiated price taking effect in 2028. In August 2023, HHS announced the ten Medicare Part D drugs and biologics that it selected for negotiations, and by October 1, 2023, each manufacturer of the selected drugs signed a manufacturer agreement to participate in the negotiations. HHS will announce the negotiated maximum fair price by September 1, 2024, and this price cap, which cannot exceed a statutory ceiling price, will come into effect on January 1, 2026.

A drug or biological product that has an orphan drug designation for only one rare disease or condition will be excluded from the IRA's price negotiations requirements, but loses that exclusion if it has designations for more than one rare disease or condition, or if is approved for an indication that is not within that single designated rare disease or condition, unless such additional designation or such disqualifying approvals are withdrawn by the time CMS evaluates the drug for selection for negotiation.

Manufacturers are also required to make their covered drugs, which are generally drugs approved under NDAs or BLAs, available to authorized users of the Federal Supply Schedule (“FSS”) of the General Services Administration. The law also requires manufacturers to offer deeply discounted FSS contract pricing for purchases of their covered drugs by the Department of Veterans Affairs, the Department of Defense, the Coast Guard, and the Public Health Service (including the Indian Health Service) in order for federal funding to be available for reimbursement or purchase of the manufacturer’s drugs under certain federal programs. FSS pricing to those four federal agencies for covered drugs must be no more than the Federal Ceiling Price (“FCP”), which is at least 24% below the Non-Federal Average Manufacturer Price (“Non-FAMP”) for the prior year. The Non-FAMP is the average price for covered drugs sold to wholesalers or other middlemen, net of any price reductions.

The accuracy of a manufacturer’s reported Non-FAMPs, FCPs, or FSS contract prices may be audited by the government. Among the remedies available to the government for inaccuracies is recoupment of any overcharges to the four specified federal agencies based on those inaccuracies. If a manufacturer were found to have knowingly reported false prices, in addition to other penalties available to the government, the law provides for significant civil monetary penalties per incorrect item. Finally, manufacturers are required to disclose in FSS contract proposals all commercial pricing that is equal to or less than the proposed FSS pricing, and subsequent to award of an FSS contract, manufacturers are required to monitor certain commercial price reductions and extend commensurate price reductions to the government, under the terms of the FSS contract Price Reductions Clause. Among the remedies available to the government for any failure to properly disclose commercial pricing and/or to extend FSS contract price reductions is recoupment of any FSS overcharges that may result from such omissions.

We believe that our success is largely dependent upon our ability to attract and retain qualified employees. We currently have 273 full-time employees and one part-time employee, of which 60 employees are based in our New Jersey office facility, 58 employees in our UK research facility, 24 employees in our Swiss corporate office, 24 in our California facility and 107 employees remote. Our workforce includes 57 employees directly involved in or supporting our commercial sales organization, 119 in research and development, 35 in manufacturing, CMC and quality and 62 in corporate and administrative functions. We are not party to any collective bargaining arrangements. We believe that we have been successful to date in attracting skilled and experienced scientific and business professionals.

We continue to focus on building a high performing organization with an engaging work culture and have established initiatives to support this strategic priority. We perform periodic employee engagement surveys, set and monitor retention goals, and offer training and leadership development to cultivate our organization. Additionally, we are committed to diversity and inclusion as a focus of our human capital strategy. We embrace differences, diversity and varying perspectives amongst our employee base, and are proud to be an equal opportunity employer. We do not discriminate based on race, religious creed, color, national origin, ancestry, physical disability, mental disability, medical condition, genetic information, marital status, sex, gender, gender identity, gender expression, age, military or veteran status, sexual orientation or any other protected characteristic established by federal, state or local laws. A diverse workforce, as well as an inclusive culture and work environment, are fundamentally important and strategic to us, beginning with our Board of Directors and extending to all levels of the organization. As of December 31, 2023, our total employee base was 67% diverse on the basis of gender and race.

We strongly believe that the success of ADCT depends, in part, on open and regular communication with employees to help foster a high performing and engaged workforce. To help ensure that employees fully understand the Company’s long-term strategy and annual goals, along with how their work contributes to the Company’s success, we use a variety of channels to facilitate open and direct communication, including: (i) regular CEO Town Hall meetings; (ii) regular ongoing update communications; and (iii) employee engagement surveys.

Talent management and leadership development is critical to our ability to execute on our long-term growth strategy. We seek to provide pay, benefits, and services that are competitive to market practice and create incentives to attract and retain employees. Our compensation package includes market-competitive base salary, discretionary broad-based stock grants and bonuses, health care and retirement benefits, paid time off and family leave. To help support the development and advancement of our high performing employees, we offer training and development programs encouraging advancement from within and continue to fill our team with strong and experienced management talent.

We leverage both formal and informal programs to identify, foster, and retain top talent throughout the organization.

Our compensation philosophy is to pay for performance, and designed to support the Company’s business strategies, and offer competitive compensation arrangements to attract and retain key individuals. Our Board of directors have established a Compensation Committee to oversee and monitor our compensation practices. Consistent with this philosophy, the Compensation Committee considers the impact of our corporate performance in determining compensation for named executive officers, as well as each named executive officer’s individual performance, macroeconomic conditions, and data from peer group companies.

We are subject to the informational requirements of the Exchange Act. Accordingly, we are required to file reports and other information with the SEC, including annual, quarterly and current reports and proxy and information statements. The SEC maintains an internet site at sec.gov that contains reports, proxy and information statements and other information we have filed electronically with the SEC.

Our website address is adctherapeutics.com. We make available free of charge on our website our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Sections 13(a) and 15(d) of the Exchange Act, as soon as reasonably practicable after we file or furnish such materials with the SEC. Information on, or accessible through, our website is not part of this Annual Report or incorporated by reference in any of our filings with the SEC, except where we expressly incorporate such information.

We are organized under the laws of Switzerland and our registered office and domicile is located in Epalinges, Switzerland. Moreover, a number of our directors and executive officers are not residents of the United States, and all or a substantial portion of the assets of such persons are located outside the United States. As a result, it may not be possible for investors to effect service of process within the United States upon us or upon such persons or to enforce against them judgments obtained in U.S. courts, including judgments in actions predicated upon the civil liability provisions of the federal securities laws of the United States. There is doubt as to the enforceability in

Switzerland of original actions, or in actions for enforcement of judgments of U.S. courts, of civil liabilities to the extent solely predicated upon the federal and state securities laws of the United States. Original actions against persons in Switzerland based solely upon the U.S. federal or state securities laws are governed, among other things, by the principles set forth in the Swiss Federal Act on Private International Law (the “PILA”). The PILA provides that the application of provisions of non-Swiss law by the courts in Switzerland shall be precluded if the result would be incompatible with Swiss public policy. Also, mandatory provisions of Swiss law may be applicable regardless of any other law that would otherwise apply.

Switzerland and the United States do not have a treaty providing for reciprocal recognition of and enforcement of judgments in civil and commercial matters. The recognition and enforcement of a judgment of the courts of the United States in Switzerland is governed by the principles set forth in the PILA. The PILA provides in principle that a judgment rendered by a non-Swiss court may be enforced in Switzerland only if:

•the non-Swiss court had jurisdiction pursuant to the PILA;

•the judgment of such non-Swiss court has become final and non-appealable;

•the judgment does not contravene Swiss public policy;

•the court procedures and the service of documents leading to the judgment were in accordance with the due process of law; and

•no proceeding involving the same position and the same subject matter was first brought in Switzerland, or adjudicated in Switzerland, or was earlier adjudicated in a third state and this decision is recognizable in Switzerland.

Our business faces significant risks and uncertainties. You should carefully consider all of the information set forth in this Annual Report and in other documents we file with or furnish to the SEC, including the following risk factors, before deciding to invest in or to maintain an investment in our securities. Our business, as well as our reputation, financial condition, results of operations, and share price, could be materially adversely affected by any of these risks, as well as other risks and uncertainties not currently known to us or not currently considered material.

Our ability to implement our business strategy is subject to numerous risks, as more fully described in this Annual Report and our other documents filed with the SEC. These risks include, among others:

•We have incurred substantial net losses since our inception, expect to continue to incur losses for the foreseeable future and may never achieve or sustain profitability. We may need to raise additional capital to fund our operations and execute our business plan.

•Our indebtedness under the Loan Agreement and the associated restrictive covenants thereunder could adversely affect our financial condition.

•The HCR Agreement reduces the amount of cash we are able to generate from sales of, and licensing agreements involving, ZYNLONTA and Cami and could make us a less attractive acquisition target.

•We may be unable to complete clinical trials on our expected timelines, if at all.

•Our products and product candidates may cause undesirable side effects or adverse events.

•We may be unable to obtain, or experience delays in obtaining, regulatory approval for our product candidates. We may be unable to maintain regulatory approval for any approved products.

•We or our partners may not be able to successfully commercialize our products.

•There can be no assurance regarding the outcome of ongoing or planned clinical trials or the sufficiency of results from such clinical trials.

•Coverage and reimbursement may be limited or unavailable for our products.

•Our products and product candidates are complex and difficult to manufacture.

•We face substantial competition, which may result in others discovering, developing or commercializing products, treatment methods or technologies before, or more successfully than, we do.

•We rely on third parties to conduct preclinical studies and clinical trials and for the manufacture, production, storage and distribution of our products and product candidates and certain commercialization activities for our products.

•If we are unable to obtain, maintain or protect our intellectual property rights in any products or technologies we develop, or if the scope of the intellectual property protection obtained is not sufficiently broad, third parties could develop and commercialize products and technology similar or identical to ours, and we may not be able to compete effectively in our market.

•We may become involved in lawsuits to protect or enforce our patents or other intellectual property, which could be expensive, time-consuming and unsuccessful, and our issued patents covering one or more of our products, product candidates or technologies or the technology we use in our products and product candidates, could be found invalid or unenforceable if challenged in court.

•We may be subject to claims by third parties asserting that our products infringe their intellectual property or that we or our employees, consultants or advisors have misappropriated their intellectual property, or claiming ownership of what we regard as our own intellectual property.

•Product liability lawsuits and product recalls could cause us to incur substantial liabilities and to limit development and commercialization of our products.

We have incurred substantial net losses since our inception, expect to continue to incur losses for the foreseeable future and may never achieve or sustain profitability. We may need to raise additional capital to fund our operations and execute our business plan and such additional capital could be dilutive, limit our ability to operate our business and adversely impact the price of our stock.

We have incurred substantial net losses since our inception and expect to continue to incur losses for the foreseeable future. As of December 31, 2023, we had accumulated losses of $1,335 million. We expect to continue to incur net losses for the foreseeable future as we continue to devote substantial resources to research and development and marketing and commercialization efforts in both hematology and solid tumors, in particular to grow ZYNLONTA in the 3L+ DLBCL setting, continue to study and advance ZYNLONTA in earlier lines of therapy and in combinations to potentially expand our market opportunity and further develop our pipeline and our ADC platform. We are unable to accurately predict whether and when we will achieve profitability. Even if we achieve profitability, we may not be able to sustain profitability in subsequent periods. This risk is heightened as we only have one approved product, ZYNLONTA, at the present time and thus are heavily dependent on its commercial performance and its continued research and development.

As a result, we may need to raise additional capital to fund our operations and execute our business plan. We do not have any committed external source of funds, and additional funds may not be available when we need them or on terms that are acceptable to us. Our ability to raise additional funds will depend on financial, economic and market conditions and other factors, over which we may have no or limited control. Further, as a Swiss company, we have less flexibility to raise capital, particularly in a quick and efficient manner, as compared to U.S. companies. See “—Risks Related to Our Common Shares—Our shareholders enjoy certain rights that may limit our flexibility to raise capital, issue dividends and otherwise manage ongoing capital needs.” The restrictions contained in our contractual agreements may also limit our ability to raise certain forms of capital. For example, subject to certain exceptions, the Loan Agreement restricts our ability to incur indebtedness and the HCR Agreement restricts our ability to sell, finance or loan any additional royalties on ZYNLONTA outside of China, Hong Kong, Macau, Taiwan, Singapore and South Korea or on Cami, and to incur indebtedness exceeding 20% of our market capitalization. If adequate funds are not available to us on a timely basis or on terms acceptable to us, we may be required to delay, limit, reduce or terminate our research and development, commercialization or growth efforts.

We may seek additional capital through a variety of means. If we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms of such equity or convertible debt securities may include liquidation or other preferences that are senior to or otherwise adversely affect your rights as a shareholder. If we raise additional capital through the sale of debt securities or through entering into credit or loan facilities, we may be restricted in our ability to take certain actions, such as incurring additional debt, making capital expenditures, acquiring or licensing intellectual property rights, declaring dividends or encumbering our assets to secure future indebtedness. If we raise additional capital through collaborations with third parties, we may be required to relinquish valuable rights to our intellectual property, products or product candidates or we may be required to grant licenses for our intellectual property, products or product candidates on unfavorable terms.

We have significant indebtedness outstanding under the Loan Agreement. Such indebtedness requires us to dedicate a substantial portion of our cash and cash equivalents to the payment of interest on, and principal of, the indebtedness, thereby reducing the amounts available to fund working capital, capital expenditures, research and development efforts, commercialization efforts and other general corporate purposes. Indebtedness under the Loan Agreement bears variable rates of interest based on the prevailing SOFR, thereby making us more vulnerable to rising interest rates.

The Loan Agreement contains certain restrictions on our activities and customary covenants, including a covenant to maintain qualified cash of at least $60.0 million plus an amount equal to any accounts payable that remain unpaid more than ninety days after the date of the original invoice therefor, and negative covenants including limitations on indebtedness, liens, fundamental changes, asset sales, investments, dividends and other restricted payments and other matters customarily restricted in such agreements. In addition, the Loan Agreement contains a revenue covenant that, so long as the Company’s 30-day average market capitalization is less than $650 million, requires the Company achieve minimum levels of ZYNLONTA net sales in the United States, tested on a quarterly basis, which is subject to a customary cure right in favor of the Company that may be exercised by making certain prepayments and that, subject to certain limitations, may be exercised up to three times during the term of the Loan Agreement.

The obligations under the Loan Agreement are secured by substantially all of our assets and are guaranteed by certain of our subsidiaries. Such covenants could limit our flexibility in planning for, or reacting to, changes in our business and our industry; place us at a competitive disadvantage compared to our competitors who have less debt or competitors with comparable debt on more favorable terms; and limit our ability to borrow additional amounts.

Our ability to maintain compliance with the covenants imposed by our indebtedness and to repay the principal of, pay interest on and refinance our indebtedness depends on our future performance, which is subject to economic, financial, competitive and other factors, many of which are beyond our control. If we are unable to comply with the covenants imposed by our indebtedness or to generate sufficient cash flow to service or repay our indebtedness, we may be in default of the Loan Agreement and be required to adopt one or more alternatives, such as restructuring debt or obtaining additional financing on terms that may be unfavorable to us or highly dilutive.

Under the HCR Agreement, we are obligated to pay to HCR royalties representing a percentage of net sales of ZYNLONTA in certain jurisdictions, a percentage of any upfront or milestone payments we receive from licenses that we grant to commercialize ZYNLONTA in certain jurisdictions, and a percentage of any upfront or milestone payments (or on royalties) we receive from licenses that we grant to commercialize Cami. See “Item 1. Business—Material Contracts.” As a result, our ability to generate from sales of, and licensing agreements involving, ZYNLONTA and Cami is reduced, which could adversely affect our financial condition.

In addition, upon the occurrence of a change in control event that occurs after the 36-month anniversary of the closing of the HCR Agreement, we are obligated to pay HCR an amount equal to 2.50 times the amount paid by HCR under the HCR Agreement, or at 2.25 times the amount paid by HCR under the agreement if HCR receives royalty payments exceeding a mid-nine-digit amount on or prior to March 31, 2029, less any amounts we previously paid to HCR. If the change in control event occurs prior to the 36-month anniversary of the closing of the HCR Agreement, we are obligated to pay HCR an amount equal to 2.0 times the amount paid by HCR, less any amounts we previously paid to HCR. The foregoing provisions may make us a less attractive acquisition target by reducing the benefit accruing to our shareholders in any change-of-control transaction.

The warrants that we have issued to Deerfield Partners, L.P. and Deerfield Private Design Fund IV, L.P. (the “Deerfield Warrants”) are presented in the audited consolidated balance sheet as a liability, which is remeasured to fair value at each reporting date. The fair value changes based on our share price and its expected volatility. Our obligations under the HCR Agreement is accounted for as a short-term and long-term debt obligation. To determine the accretion of the liability, we are required to estimate the total amount of future royalty payments and estimated timing of such payment to HCR based on our revenue projections as well as the achievement of certain milestones. Based on our periodic review, the amount and timing of repayment is likely to be different at each reporting period. To the extent the amount or timing of such payments is materially different than our initial estimates, we will record a cumulative catch-up adjustment. As a result, our Deerfield Warrants and obligations under the HCR Agreement could result in considerable non-cash charges to, and significant volatility in, our statement of operations.

As of December 31, 2023, we reported $1,059 million in tax loss carryforwards for Swiss corporate income tax purposes. Such tax loss carryforwards and tax credits could, with certain limitations, be used to offset future taxable income. Swiss tax loss carryforwards generally expire seven years after the tax year in which they were incurred; U.S. federal and state tax credits generally expire after 20 years, although some state tax credits expire as quickly as seven years after the tax year in which they were incurred, and others do not expire. There can be no assurance that we will be able to generate sufficient income that allows us to use such tax loss carryforwards or tax credits before their expiration. U.S. federal and state credits in our financial statements are based on our assessment of the value that we will be able to realize; however, such assessments are based on our projections of our future taxable income, which are subject to uncertainty and change based on numerous factors, including those described in this “Item 1A. Risk Factors” section. In addition, relevant tax authorities may not accept our claims of tax loss carryforwards or tax credits. Furthermore, changes in tax law, as well as interpretation of such tax laws, could reduce, eliminate, or otherwise impair our ability to use our tax loss carryforwards and US federal and state credits.

We operate internationally and are exposed to fluctuations in foreign exchange rates between the U.S. dollar and other currencies, particularly the British pound, the Euro and the Swiss franc. Our reporting currency is the U.S. dollar and, as a result, financial line items are converted into U.S. dollars at the applicable foreign exchange rates. As our business grows, we expect that at least some of our revenues and expenses will be denominated in currencies other than the U.S. dollar. Therefore, unfavorable developments in the value of the U.S. dollar relative to other relevant currencies could adversely affect our business and financial condition.

Under the Internal Revenue Code of 1986, as amended (the “Code”), we will be a passive foreign investment company (“PFIC”), for any taxable year in which, after the application of certain look-through rules with respect to subsidiaries, either (i) 75% or more of our gross income consists of “passive income” or (ii) 50% or more of the average quarterly value of our assets consists of assets that produce, or are held for the production of, “passive income” (including cash). Passive income generally includes interest, dividends, certain non-active rents and royalties, and capital gains.

Cash is generally characterized as a passive asset for these purposes. Goodwill is generally characterized as a non-passive or passive asset based on the nature of the income produced in the activity to which the goodwill is attributable. The extent to which our goodwill should be characterized as a non-passive asset is not entirely clear. We hold a substantial amount of cash, and while this continues to be the case, our PFIC status for any taxable year depends largely on the value of our goodwill and the characterization of our goodwill as passive or non-passive. The value of our goodwill for any taxable year may be determined in large part by reference to the average of our market capitalization for that year. Because our market capitalization declined substantially during 2023, we believe we were a PFIC for our 2023 taxable year. There is also a risk that we will be a PFIC for 2024 and possibly future taxable years. We have not obtained any valuation of our assets (including goodwill). A beneficial owner of our common shares who, for U.S. federal income tax purposes, is eligible for the benefits of the income tax treaty between Switzerland and the United States (the “Treaty”) and who is (i) a citizen or individual resident of the United States, (ii) a corporation, or other entity taxable as a corporation, created or organized in or under the laws of the United States, any state therein or the District of Columbia or (iii) an estate or trust the income of which is subject to U.S. federal income taxation regardless of its source (each, a “Holder”), should consult their tax advisers regarding the value and characterization of our assets for purposes of the PFIC rules, as they are subject to some uncertainties. In addition, our PFIC status is a factual annual determination that can be made only after the end of the relevant taxable year and will depend on the composition of our income and assets and the value of our assets from time to time. Accordingly, our PFIC status for 2024 and any future taxable year is uncertain.

If we are a PFIC for any taxable year during which a U.S. Holder holds common shares, we generally will continue to be treated as a PFIC with respect to that U.S. Holder for all succeeding years during which the U.S. Holder holds common shares, even if we cease to meet the threshold requirements for PFIC status. Such a U.S. Holder may be subject to adverse U.S. federal income tax consequences, including (i) the treatment of all or a portion of any gain on disposition as ordinary income; (ii) the application of a deferred interest charge on such gain and the receipt of certain dividends; and (iii) compliance with certain reporting requirements. A “qualified electing fund” (“QEF”) election or, if our common shares are regularly traded on a qualified exchange, a “mark-to-market” election may be available that will alter the consequences of PFIC status.

Because we believe we were a PFIC for the 2023 taxable year, we will endeavor to provide information necessary for our U.S. Holders to make a QEF election with respect to us for the 2023 taxable year and expect to provide such information for any subsequent year if we believe we are a PFIC, but there is no assurance that we will timely provide this information. There is also no assurance that we will have timely knowledge of our status as a PFIC in the future or of the information that a U.S. Holder would need in order to make a valid election. Any such information will be provided on our website.

We may expend our resources to pursue particular products or product candidates and fail to capitalize on those that may be more profitable or for which there is a greater likelihood of success.

Because we have limited financial resources and personnel, we may prioritize the research, development and commercialization of select products, product candidates and technologies and of products, product candidates and technologies in select indications or markets.

As a result, we may forgo or delay the pursuit of other products, product candidates and technologies or of other indications and markets that later prove to have greater commercial potential. Decision-making about development and commercialization priorities involves inherent subjectivity and uncertainty, and there can be no assurance that we will pursue product candidates and technologies with the greatest likelihood of obtaining regulatory approval or products, product candidates and technologies with the greatest market potential. In addition, we may relinquish valuable rights to products, product candidates and technologies through partnering, licensing or other arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such products, product candidates and technologies.

Clinical trials are subject to the numerous risks described in this “Item 1A. Risk Factors” section and in our other filings with the SEC, and a failure, delay or termination of one or more clinical trials can occur at any stage of the clinical trial process. Events that could impede our ability to complete clinical trials on a timely basis include but are not limited to:

•delays in the timely commencement of clinical trials due to negative preclinical data, delays in receiving the required regulatory clearance from the appropriate regulatory authorities, delays in reaching an agreement on acceptable terms with prospective clinical research organizations (“CROs”) and clinical trial sites and difficulties in obtaining required Institutional Review Board (“IRB”) or ethics committee approval at each clinical trial site;

•challenges in recruiting and enrolling suitable patients that meet the study criteria to participate in clinical trials, which challenges may be heightened for clinical trials that seek to enroll patients with characteristics that are found in a small population and by the novel nature of our products and product candidates;

•competition from alternative clinical trials in a similar space or new treatments in similar indications which may limit or ability to recruit and enroll new subjects;

•difficulties in retaining and following up with subjects and censoring of patients;

•any failure by us or CROs, CMOs, and other third parties to adhere to applicable requirements, which risk may be heightened by our reliance on third parties, and which may result in delays, trial suspension or the imposition of clinical holds;

•safety issues, including occurrence of treatment emergent adverse events (“TEAEs”) and serious adverse events (“SAEs”), which may result in trial suspension or the imposition of clinical holds such as the partial clinical hold that was imposed by the FDA on our previous clinical trial of ZYNLONTA and rituximab in unfit or frail previously untreated DLBCL patients due to respiratory-related events;

•the inability to manufacture adequate quantities of a product or a product candidate or other materials necessary in accordance with current Good Manufacturing Practices (“cGMPs”) to conduct clinical trials, including, for example, quality issues and delays in the testing, validation, manufacturing delays or failures at our CROs and delivery of the product or product candidate to the clinical trial sites;

•the ability to obtain on a timely basis and on commercially reasonable terms an adequate supply of products or product candidates to be used in combination with our products and product candidates;

•changes in regulatory requirements and guidance;

•changes in the treatment landscape, such as new therapies or the withdrawal of a competing product; and

•lack of adequate funding to continue the clinical trial.

Any delays in the completion of clinical trials could increase costs, delay or prevent regulatory approval of our product candidates and impair our ability to maintain regulatory approval of and to commercialize any approved products.

Drug research and clinical trials are inherently uncertain. There can be no assurance regarding the outcome of any ongoing or planned clinical trials, including whether such trials will meet their respective endpoint, whether severe adverse events will occur during the trials and whether the final results will ultimately be sufficient to support regulatory approval.

For example, we are conducting a confirmatory Phase 3 trial of ZYNLONTA in combination with rituximab for the treatment of relapsed or refractory DLBCL. Despite ZYNLONTA having received accelerated approval from the FDA and conditional approval from the EMA and UK MHRA, ZYNLONTA may fail to achieve its endpoints in this clinical trial, which could result in our inability to maintain regulatory approval. Results from earlier-stage clinical trials are even more unpredictable due to the limited size of the clinical trials and number of unknown factors at such early stages.

Results from preclinical studies and early-stage clinical trials of a product candidate may not be predictive of results from late-stage clinical trials of that product candidate or of any other product or product candidate. In the past, despite promising results from preclinical studies and early-stage clinical trials, we have discontinued development of product candidates due the results from late-stage clinical trials. In addition, positive and promising results from preclinical studies and clinical trials of a product or product candidate in one indication may not be predictive of results from clinical trials of that product or product candidate in other indications or in combination with other agents. There may be significant differences between clinical trials, including differences in inclusion and exclusion criteria, efficacy endpoints, dosing regimen and statistical design. For example, results from the pivotal Phase 2 clinical trial of ZYNLONTA for the treatment of relapsed or refractory DLBCL, or any other clinical trial of ZYNLONTA, may not be predictive of results from other clinical trials of ZYNLONTA, such as the confirmatory Phase 3 clinical trial, particularly those in which ZYNLONTA is used in combination with other agents and those involving different patient populations, such as the Phase 1 LOTIS-7 trial. If the results of our confirmatory trial for ZYNLONTA or the additional trials for ZYNLONTA in other indications do not meet their primary endpoints, then we may be unable to maintain regulatory approval for ZYNLONTA or obtain regulatory approval for expanded or new indications for ZYNLONTA. Failure to maintain or obtain regulatory approval for ZYNLONTA could have an adverse impact on our ability to continue to generate and grow our revenue in the future.

From time to time, we may announce or publish preliminary data, such as we had done for the LOTIS-7 trial or the ADCT-601 trial, but such data may not be predictive of future results for the next phase of the clinical program and are subject to the risk that one or more of the outcomes may materially change as more data become available. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully evaluate all data. Therefore, positive preliminary results in any ongoing clinical trial may not be predictive of results in the completed trial. Preliminary data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, preliminary data should be viewed with caution until the final data are available.

Undesirable side effects or adverse events caused by our products or product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials, result in more restrictive labeling, boxed warnings, REMS or the denial or withdrawal of regulatory approval by the FDA, the EMA or other regulatory authorities, subject us to product liability claims or require us to issue product recalls. For example, in July 2023, we discontinued our Phase 2 clinical trial of ZYNLONTA in combination with rituximab in unfit or frail previously untreated DLBCL patients due to safety data that signaled potentially excessive respiratory-related events. In addition, undesirable side effects or adverse events could impair our ability to market our products, limit patients’ and physicians’ willingness to use our products and make it more difficult for us to obtain adequate coverage and reimbursement for our products.

In our clinical trials, we have observed certain class toxicities associated with our warheads, including elevated liver enzymes, skin rash, and effusions and edema. The prescribing information for ZYNLONTA contains warnings and precautions for effusion and edema, myelosuppression, infections, cutaneous reactions and embryo-fetal toxicity.

Such information is based on adverse events observed in our clinical trials and post-marketing information. However, clinical trials by their nature utilize a sample of the potential patient population. With a limited number of subjects and limited duration of exposure, rare and severe side effects of our products or product candidates may only be uncovered with a significantly larger number of patients exposed to the drug. Therefore, there can be no assurance that ZYNLONTA will not cause side effects that are different or more severe in a greater proportion of patients when used by more patients as we commercialize the product. Similarly, as our other product candidates advance through late-stage clinical trials that involve more patients than earlier-stage clinical trials, these product candidates may cause side effects or adverse events that are different in nature, severity and frequency than observed in earlier-stage clinical trials.

In addition, we are developing ZYNLONTA and certain of our product candidates in combination with other therapies, such as rituximab and bispecifics. Combining therapies may cause additional, different or more severe side effects or adverse events than when a drug is used as a monotherapy. In addition, therapies used in combination may have common toxicities.

When used in combination, the severity and frequency of such undesirable side effects or adverse events may be greater than the cumulative severity and frequency of such side effects or adverse events when the therapies are used as monotherapies.

ZYNLONTA is currently approved for the treatment of adult patients with relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy, including DLBCL not otherwise specified, DLBCL arising from low-grade lymphoma, and also high-grade B-cell lymphoma. We are undertaking clinical trials to potentially expand ZYNLONTA into other indications and into earlier lines of therapy. However, clinical development and regulatory review is inherently unpredictable and are subject to numerous risks and uncertainties described in this “Item 1A. Risk Factors” section. Failure to expand the indication(s) for ZYNLONTA, could limit the market opportunity for ZYNLONTA and our potential future revenue which could have an adverse effect on our business and operations. There can be no assurance that we will succeed in expanding the market opportunity of ZYNLONTA.

A key element of our development strategy is to build a robust pipeline ADCs targeting both novel and clinically validated cancer targets using a variety of technologies for the treatment of hematological malignancies and solid tumors. There can be no assurance that we will be able to identify suitable additional product candidates for clinical development or that our research and development efforts will yield safe, effective and commercially viable product candidates. If we are not successful in developing these new drugs, our future market opportunity and potential revenue may be negatively impacted, which could adversely impact our business and operations.

Our product candidates must be approved by the FDA in the United States, by the EMA in the European Union and by comparable regulatory authorities in other jurisdictions prior to commercialization. In order to obtain regulatory approval for the commercial sale of any product candidates, we must demonstrate through extensive preclinical studies and clinical trials that the product candidate is safe and effective for use in each target indication and that manufacturing of the product candidate is safe, robust and reproducible. The time and resources required to obtain regulatory approval is unpredictable, typically takes many years and significant investment following the commencement of clinical trials and depends upon numerous factors.

Regulatory authorities have substantial discretion in the approval process. They may refuse to accept any application or may decide that our data are insufficient for approval and require additional clinical trials or other studies. In this Annual Report and elsewhere in our public communications, we designate certain of our clinical trials as “pivotal” if we believe that these clinical trials, if successful, will support biologics license application (“BLA”) submissions; however, there can be no assurance that any clinical trial that we designate as “pivotal” will be viewed as sufficient by the FDA, the EMA and other comparable regulatory authorities in other jurisdictions to support regulatory approval. If we are required to conduct additional clinical trials or other testing of any of our products and product candidates beyond those that are contemplated, we may incur significant additional costs and regulatory approval may be delayed or prevented.

Various regulatory programs in the United States, such as Breakthrough Therapy Designation, Fast Track Designation or Priority Review Designation, are designed to expedite the development and review of therapies to treat certain diseases. We may seek such designations, and comparable designations by foreign regulatory authorities, for one or more of our product candidates for the treatment of certain indications. However, regulatory authorities have broad discretion whether or not to grant such designations, and the receipt of such designations may not result in faster development, review or approval and does not guarantee regulatory approval.

We are developing certain of our products and product candidates in combination with other therapies. If we choose to develop a product or product candidate for use in combination with an approved therapy, we are subject to the risk that the FDA, the EMA or comparable regulatory authorities in other jurisdictions could revoke approval of, or that safety, efficacy, manufacturing or supply issues could arise with, the therapy used in combination with our product or product candidate. If the therapies we use in combination with our products and product candidates are replaced as the standard of care, the FDA, the EMA or comparable regulatory authorities in other jurisdictions may require us to conduct additional clinical trials. The occurrence of any of these risks could result in our products, if approved only for use in combination with another approved therapy, being removed from the market or being less successful commercially.

Where we develop a product or product candidate for use in combination with a therapy that has not been approved by the FDA, the EMA or comparable regulatory authorities in other jurisdictions, we may not be able to market our product or product candidate for use in combination with such an unapproved therapy, unless and until the unapproved therapy receives regulatory approval. Unapproved therapies face the same risks described with respect to our product candidates currently in development. In addition, other companies may also develop their products or product candidates in combination with the unapproved therapies with which we are developing our products and product candidates for use in combination. Any setbacks in these companies’ clinical trials, including the emergence of serious adverse effects, may delay or prevent the development and approval of our products and product candidates for use in combination with an approved therapy.

Furthermore, the process and time required to obtain regulatory approval differ by jurisdiction. Approval by one regulatory authority does not ensure approval by regulatory authorities in other jurisdictions. In particular, prior to regulatory approval, regulatory authorities may require additional clinical trials to be conducted with a local population. Moreover, in many countries outside the United States, a drug must be approved for reimbursement before it can be approved for sale in that country, which can take considerable time and be heavily impacted by political, economic and regulatory developments.

In addition, the approval policies or regulations of the FDA, the EMA or comparable regulatory authorities in other jurisdictions may change in a manner rendering our clinical data insufficient for approval. Recently, the accelerated approval pathway has come under scrutiny within the FDA and by Congress. The FDA has put increased focus on ensuring that confirmatory studies are conducted with diligence and, ultimately, that such studies confirm the benefit. For example, FDA has convened its Oncologic Drugs Advisory Committee to review what the FDA has called dangling or delinquent accelerated approvals where confirmatory studies have not been completed or where results did not confirm benefit. In addition, the Food and Drug Omnibus Reform Act (“FDORA”) included provisions related to the accelerated approval pathway and authorized the FDA to require a post-approval study to be underway prior to approval or within a specified time period following approval. In addition, the Oncology Center of Excellence within the FDA is advancing Project Optimus, which is an initiative to reform the dose optimization and dose selection paradigm in oncology drug development to emphasize selection of an optimal dose, which is a dose or doses that maximizes not only the efficacy of a drug but the safety and tolerability as well. This shift from the prior approach, which generally determined the maximum tolerated dose, may require sponsors to spend additional time and resources to further explore a product candidate’s dose-response relationship to facilitate optimum dose selection in a target population. Other recent Oncology Center of Excellence initiatives have included Project FrontRunner, a new initiative with a goal of developing a framework for identifying candidate drugs for initial clinical development in the earlier advanced setting rather than for treatment of patients who have received numerous prior lines of therapies or have exhausted available treatment options, and Project Equity, which is an initiative to ensure that the data submitted to the FDA for approval of oncology medical products adequately reflects the demographic representation of patients for whom the medical products are intended.

As part of regulatory approval, we may be subject to a number of post-marketing requirements and commitments, such as post-marketing studies or clinical trials, surveillance to monitor the safety or efficacy of any approved product and risk evaluation and mitigation strategies. For example, our post-marketing obligations with respect to ZYNLONTA include a deferred pediatric trial and a trial in patients with hepatic impairment. In particular, for any products for which we receive accelerated approval from the FDA or conditional approval from the EMA or comparable regulatory authorities in other jurisdictions, we are required to complete confirmatory clinical trials. The FDA may withdraw approval of our products approved under the accelerated approval pathway if, for example, the clinical trial(s) required to verify the predicted clinical benefit of a product fails to verify such benefit or does not demonstrate sufficient clinical benefit to justify the risks associated with the product, other evidence demonstrates that a product is not shown to be safe or effective under the conditions of use, we fail to conduct any required post-marketing confirmatory clinical trial with due diligence or we disseminate false or misleading promotional materials relating to the relevant product. There can be no assurance that we will receive full approval or maintain the current accelerated approval for ZYNLONTA for the treatment of relapsed or refractory DLBCL or that we will receive full approval for ZYNLONTA in other indications or for any of product candidates for which we receive accelerated approval. In addition, any products for which we receive regulatory approval in a particular jurisdiction and the activities associated with their commercialization, including testing, manufacture, recordkeeping, labeling, storage, approval, advertising, promotion, sale and distribution, will be subject to comprehensive regulation by the FDA, the EMA or comparable regulatory authorities in other jurisdictions. These requirements include, without limitation, submissions of safety and other post-marketing information and reports, registration and listing requirements, the FDA’s cGMP requirements or comparable requirements in foreign jurisdictions, requirements relating to manufacturing, quality control, quality assurance and corresponding maintenance of records and documents, including periodic inspections by the FDA, the EMA or comparable regulatory authorities in other jurisdictions, requirements regarding the distribution of samples to physicians, tracking and reporting of payments to physicians and other healthcare providers and recordkeeping.

If we are unable to complete the required confirmatory or post-marketing studies, if such studies fail to meet their safety and efficacy endpoints or if we otherwise fail to comply with post-marketing requirements and regulations, we may be unable to maintain regulatory approval for any approved products.

The policies of the FDA, the EMA and comparable regulatory authorities in other jurisdictions may change and additional regulations may be enacted. If we are slow or unable to adapt to changes in existing requirements or to the adoption of new requirements, or not able to maintain regulatory compliance, we may lose any regulatory approval that may have been obtained. We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the United States or abroad, as the regulatory environment changes rapidly.

Regulatory authorities in some jurisdictions, including the United States and the European Union, may designate drugs for relatively small patient populations as orphan drugs. In the United States, orphan drug designation entitles a party to financial incentives such as tax advantages and user fee waivers. In addition, if a product receives the first FDA approval for the condition for which it has orphan designation, the product is entitled to orphan drug exclusivity, which means the FDA may not approve any other application to market the same drug for the same condition for a period of seven years, except in limited circumstances, such as a showing of clinical superiority over the product with orphan exclusivity or where the manufacturer is unable to assure sufficient product quantity. In the European Union, orphan drug designation entitles a party to financial incentives such as reduction of fees or fee waivers and ten years of market exclusivity for the orphan indication following drug or biological product approval, provided that the criteria for orphan designation are still applicable at the time of the granting of the marketing authorization. This period may be reduced to six years if, at the end of the fifth year, the orphan drug designation criteria are no longer met, including where it is shown that the product is sufficiently profitable not to justify maintenance of market exclusivity. The respective orphan drug designation and exclusivity frameworks in the United States and in the European Union are subject to change, and any such changes may affect our ability to obtain, or the impact of obtaining, European Union or U.S. orphan designations in the future.

We may pursue orphan drug designation for one or more of our other product candidates. However, obtaining an orphan drug designation can be difficult, and we may not be successful in doing so. Even if we obtain orphan drug designation, we may not be able to maintain such designation. For example, in the process of seeking marketing authorization in the European Union, the Committee for Orphan Medicinal Products recommended to not uphold ZYNLONTA’s previously granted orphan drug designation. Even if we obtain orphan drug designation for our product candidates in specific conditions, we may not be the first to obtain regulatory approval of these product candidates for the orphan-designated condition. Orphan drug designation neither shortens the development time or regulatory review time of a product candidate nor gives the product candidate any advantage in the regulatory review or approval process. In addition, exclusive marketing rights in the United States may be limited if we seek approval for an indication broader than the orphan-designated condition or may be lost if the FDA later determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition. Furthermore, even if we obtain orphan drug exclusivity for a product, that exclusivity may not effectively protect the product from competition because different ADCs with different monoclonal antibody elements or functional elements of the conjugated molecule can be approved for the same condition. Even after an orphan product is approved, the FDA can subsequently approve the same ADC with the same monoclonal antibody element and functional element of the conjugated molecule for the same condition if the FDA concludes that the later ADC is safer, more effective or makes a major contribution to patient care. Our inability to obtain orphan drug designation for any product candidates for the treatment of rare cancers and/or our inability to maintain that designation for the duration of the applicable exclusivity period, could reduce our ability to make sufficient sales of the applicable product candidate to balance our expenses incurred to develop it.

We believe ZYNLONTA is the first loncastuximab tesirine product to have been licensed by the FDA and should be entitled to a period of 12 years of Reference Product Exclusivity (“RPE”). However, the FDA has not yet awarded ZYNLONTA such RPE, and the FDA may not do so for unknown reasons. The Biologics Price Competition and Innovation Act of 2009 (the “BPCIA”) established an abbreviated pathway to licensure for follow-on biologics called biosimilars. Biosimilars are biological products approved under section 351(k) of the Public Health Act Service Act (“PHS Act”) relying on the FDA’s findings of safety, purity, and potency for a licensed biologic (“Reference Product”) submitted pursuant to section 351(k) of the PHS Act. A biosimilar is highly similar to its Reference Product, excluding minor differences in clinically inactive components for which there are no clinically meaningful differences between the proposed biological product and the Reference Product in safety, purity, or potency.

The BPCIA provides a 12-year period of RPE during which the FDA may not license a biosimilar application relying on the Reference Product; the applicant may not submit a biosimilar application relying on the Reference Product for the first 4 years of the 12-year RPE period. That RPE runs from the “date of first licensure,” which is the date that the FDA first licensed the Reference Product, and when such a period of RPE is awarded to a given Reference Product, it is listed in the FDA’s Database of Licensed Biological Products (the “Purple Book”) as a “Date of First Licensure.” The FDA historically has been slow to make these determinations and often does not do so until there is a biosimilar application pending. There is no “Date of First Licensure” listed in the Purple Book for ZYNLONTA.

RPE is available unless the putative Reference Product falls under one of several exclusions. Specifically, RPE is not available where licensure is for a supplement for the putative Reference Product or where the licensure is for a subsequent application filed by the same sponsor or manufacturer of the biological product for a change other than a modification to the structure of the biological product that results in a change in safety, purity, and potency. The “same sponsor” includes any licensor, predecessor in interest, or other related entity. For each putative Reference Product, the FDA assesses whether an application is considered a subsequent application filed by the same sponsor or manufacturer of the biological product and whether there is a modification to the structure of the biological product previously licensed by such an entity. If there is a structural modification, the FDA then determines whether such modification would result in a change in safety, purity, or potency.

ZYNLONTA is listed in the Purple Book, but the FDA has not yet listed a Date of First Licensure. Accordingly, it is unclear whether the FDA will award ZYNLONTA its 12 years of RPE. While we are not aware of any disqualifying factors, the FDA could determine that ZYNLONTA is not entitled to RPE if it determines that an entity related to us received licensure of a similar molecule in the past.

Even if ZYNLONTA does receive its 12 years of exclusivity, the value of RPE is limited. As data exclusivity, RPE would not preclude subsequent licensure of a similar or related product unless the application sought to rely on the FDA’s findings of safety, purity, and potency for ZYNLONTA in a biosimilar application filed pursuant to Section 351(k) of the PHS Act. Accordingly, the FDA could approve an identical loncastuximab tesirine product with full studies demonstrating safety, purity, and potency submitted under section 351(k) of the PHS Act. The FDA could also approve loncastuximab tesirine for a different indication or with a different route of administration or formulation despite any RPE for ZYNLONTA.

The FDA, the EMA and comparable regulatory authorities in other jurisdictions strictly regulate the promotional claims that may be made about prescription drug products, such as our products. While physicians, in the practice of medicine, may prescribe approved drugs for unapproved indications, a product may not be promoted for uses that are not approved by the applicable regulatory authority as reflected in the product’s approved labeling or for uses inconsistent with the product’s approved labeling. For example, despite ZYNLONTA being approved for the treatment of adult patients with relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy, including DLBCL not otherwise specified, DLBCL arising from low grade lymphoma and high-grade B-cell lymphoma, if our promotional materials and related activities are not consistent with the approved labeling or if physicians, in their professional medical judgment, nevertheless prescribe the drug product to their patients in a manner that is inconsistent with the approved labeling, we may be subject to claims that we promoted off-label use or otherwise violated applicable regulations. In addition, although we believe our warhead may provide for superior efficacy as compared to marketed ADCs, without head-to-head data, we will be unable to make comparative claims for our products. If we are found to have promoted such off-label use or made such unsubstantiated comparative claims, we may become subject to significant liability under the Federal Food, Drug, and Cosmetic Act (the “FDCA”) and other statutory authorities, such as laws prohibiting false claims for reimbursement.

We receive, generate and store significant and increasing volumes of sensitive information, such as employee and patient data. In addition, we actively seek access to medical information, including patient data, through research and development collaborations or otherwise. We and any potential collaborators may be subject to federal, state, local and foreign laws and regulations that apply to the collection, use, retention, protection, disclosure, transfer and other processing of personal data, including the Health Insurance Portability and Accountability Act of 1996 (“HIPAA”), as amended by the Health Information Technology for Economic and Clinical Health Act of 2009 (“HITECH”), the California Consumer Privacy Act and other state laws and regulations, the Regulation 2016/679, known as the General Data Protection Regulation (the “GDPR”), as well as European Union member state implementing legislations, the UK General Data Protection Regulation (“UK GDPR”) and the Swiss Federal Act on Data Protection.

These laws and regulations are complex and change frequently, at times due to changes in political climate, and existing laws and regulations are subject to different and conflicting interpretations, which adds to the complexity of processing personal data from these jurisdictions. Compliance with U.S. and international data protection laws and regulations could require us to take on more onerous obligations in our contracts, restrict our ability to collect, use and disclose data, or in some cases, impact our ability to operate in certain jurisdictions. Failure to comply with these laws and regulations could result in government enforcement actions, which could include civil, criminal and administrative penalties, private litigation, and adverse publicity and could negatively affect our operating results and business. Moreover, clinical trial subjects, employees and other individuals about whom we or our potential collaborators obtain personal information, as well as the providers who share this information with us, may limit our ability to collect, use and disclose the information. Claims that we have violated individuals’ privacy rights, failed to comply with data protection laws, or breached our contractual obligations, even if we are not found liable, could be expensive and time-consuming to defend and could result in adverse publicity that could harm our business.

Healthcare providers, physicians and third-party payors will play a primary role in the recommendation and prescription of our products for which we obtain marketing approval. Our operations, including any arrangements with healthcare providers, physicians, third-party payors and customers may expose us to broadly applicable fraud and abuse and other healthcare laws that may affect the business or financial arrangements and relationships through which we would market, sell and distribute our products. The healthcare laws that may affect our ability to operate include, but are not limited to:

•The federal Anti-Kickback Statute, which prohibits any person or entity from, among other things, knowingly and willfully soliciting, receiving, offering or paying any remuneration, directly or indirectly, overtly or covertly, in cash or in kind, to induce or reward either the referral of an individual for, or the purchase, order or recommendation of an item or service reimbursable, in whole or in part, under a federal healthcare program, such as the Medicare and Medicaid programs. The term “remuneration” has been broadly interpreted to include anything of value. The federal Anti-Kickback Statute has also been interpreted to apply to arrangements between pharmaceutical manufacturers, on the one hand, and prescribers, purchasers, and formulary managers, on the other hand. There are a number of statutory exceptions and regulatory safe harbors protecting some common activities from prosecution, but the exceptions and safe harbors are drawn narrowly and require strict compliance in order to offer protection.

•Federal civil and criminal false claims laws, such as the False Claims Act (“FCA”), which can be enforced by private citizens through civil qui tam actions, and the Civil Monetary Penalties Law prohibit individuals or entities from, among other things, knowingly presenting, or causing to be presented, false, fictitious or fraudulent claims for payment of federal funds, and knowingly making, using or causing to be made or used a false record or statement material to a false or fraudulent claim to avoid, decrease or conceal an obligation to pay money to the federal government. For example, pharmaceutical companies have been prosecuted under the FCA in connection with their alleged off-label promotion of drugs, purportedly concealing price concessions in the pricing information submitted to the government for government price reporting purposes, and allegedly providing free product to customers with the expectation that the customers would bill federal healthcare programs for the product. In addition, a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the FCA. As a result of a modification made by the Fraud Enforcement and Recovery Act of 2009, a claim includes “any request or demand” for money or property presented to the U.S. government. In addition, manufacturers can be held liable under the FCA even when they do not submit claims directly to government payors if they are deemed to “cause” the submission of false or fraudulent claims.

•HIPAA, which, among other things, imposes criminal liability for executing or attempting to execute a scheme to defraud any healthcare benefit program, including private third-party payors, knowingly and willfully embezzling or stealing from a healthcare benefit program, or willfully obstructing a criminal investigation of a healthcare offense, and creates federal criminal laws that prohibit knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false, fictitious or fraudulent statement or representation, or making or using any false writing or document knowing the same to contain any materially false, fictitious or fraudulent statement or entry in connection with the delivery of or payment for healthcare benefits, items or services.

•HIPAA, as amended by HITECH, and its implementing regulations, which impose privacy, security and breach reporting obligations with respect to individually identifiable health information upon entities subject to the law, such as health plans, healthcare clearinghouses and certain healthcare providers, known as covered entities, and their respective business associates and covered subcontractors that perform services for them that involve individually identifiable health information. HITECH also created new tiers of civil monetary penalties, amended HIPAA to make civil and criminal penalties directly applicable to business associates, and gave state attorneys general new authority to file civil actions for damages or injunctions in U.S. federal courts to enforce HIPAA laws and seek attorneys’ fees and costs associated with pursuing federal civil actions.

•Federal and state consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities that potentially harm consumers.

•The federal transparency requirements under the Physician Payments Sunshine Act, which requires, among other things, certain manufacturers of drugs, devices, biologics and medical supplies reimbursed under Medicare, Medicaid, or the Children’s Health Insurance Program to report annually to the Centers for Medicare & Medicaid Services (the “CMS”) information related to payments and other transfers of value provided to physicians, as defined by such law, certain other healthcare professionals, and teaching hospitals and physician ownership and investment interests, including such ownership and investment interests held by a physician’s immediate family members.

•State and foreign laws that are analogous to each of the above federal laws, such as anti-kickback and false claims laws, that may impose similar or more prohibitive restrictions, and may apply to items or services reimbursed by non-governmental third-party payors, including private insurers.

•State and foreign laws that require pharmaceutical companies to implement compliance programs, comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government, or to track and report gifts, compensation and other remuneration provided to physicians and other healthcare providers; state laws that require the reporting of marketing expenditures or drug pricing, including information pertaining to and justifying price increases; state and local laws that require the registration of pharmaceutical sales representatives; state laws that prohibit various marketing-related activities, such as the provision of certain kinds of gifts or meals; state laws that require the posting of information relating to clinical trials and their outcomes; and other federal, state and foreign laws that govern the privacy and security of health information or personally identifiable information in certain circumstances, including state health information privacy and data breach notification laws which govern the collection, use, disclosure, and protection of health-related and other personal information, many of which differ from each other in significant ways and often are not pre-empted by HIPAA, thus requiring additional compliance efforts.

Ensuring that our operations and business arrangements with third parties comply with applicable healthcare laws and regulations is costly. If our operations are found to be in violation of any of these laws or any other current or future healthcare laws that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, disgorgement, imprisonment, exclusion from government funded healthcare programs, such as Medicare and Medicaid, contractual damages, reputational harm, diminished profits and future earnings, additional reporting obligations and oversight if we become subject to a corporate integrity agreement or other agreement to resolve allegations of non-compliance with these laws, and the curtailment or restructuring of our operations, any of which could substantially disrupt our operations. Although effective compliance programs can mitigate the risk of investigation and prosecution for violations of these laws, these risks cannot be entirely eliminated. Any action against us for an alleged or suspected violation could cause us to incur significant legal expenses and could divert our management’s attention from the operation of our business, even if our defense is successful.

Our revenues and revenue prospects could be affected by changes in healthcare spending and policies in the United States, the European Union and any other potential jurisdictions in which we or our collaborators may seek to commercialize our products. We operate in a highly regulated industry, and new laws, regulations and judicial decisions, or new interpretations of existing laws, regulations and decisions, related to healthcare availability, the method of delivery and payment for healthcare products and services could negatively affect our business, financial condition and prospects. There is significant interest in promoting healthcare reforms, and it is likely that federal and state legislatures within the United States and the governments of other countries will continue to consider changes to existing healthcare legislation.

For example, there have been and continue to be a number of initiatives at the United States federal and state levels that seek to reduce healthcare costs, including the Budget Control Act (which, subject to certain sequestration periods, imposed 2% reductions in Medicare payments to providers per fiscal year) and the Infrastructure Investment and Jobs Act (which added a requirement for manufacturers of certain single-source drugs (including biologics and biosimilars) separately paid for under Medicare Part B for at least 18 months and marketed in single-dose containers or packages (known as refundable single-dose container or single-use package drugs), such as ZYNLONTA, to provide annual refunds for any portions of the dispensed drug that are unused and discarded if those unused or discarded portions exceed an applicable percentage defined by statute or regulation) which requirement has caused and we expect will continue to cause a significant adverse effect on ZYNLONTA net sales and thus our results of operations.

.

These initiatives culminated in the enactment of the Inflation Reduction Act (“IRA”), which, among other things, allows the U.S. Department of Health and Human Services (“HHS”) to directly negotiate the selling price of a statutorily specified number of drugs and biologics each year that the Centers for Medicare & Medicaid Services (“CMS”) reimburses under Medicare Part B and Part D. Only high-expenditure single-source biologics that have been approved for at least 11 years (7 years for single-source drugs) can qualify for negotiations, with the negotiated price taking effect two years after the selection year. Negotiations for Medicare Part D products begin in 2024 with the negotiated price taking effect in 2026, and negotiations for Medicare Part B products begin in 2026 with the negotiated price taking effect in 2028. In August 2023, HHS announced the ten Medicare Part D drugs and biologics that it selected for negotiations, and by October 1, 2023, each manufacturer of the selected drugs signed a manufacturer agreement to participate in the negotiations. HHS will announce the negotiated maximum fair price by September 1, 2024, and this price cap, which cannot exceed a statutory ceiling price, will come into effect on January 1, 2026. A drug or biological product that has an orphan drug designation for only one rare disease or condition will be excluded from the IRA’s price negotiations requirements, but loses that exclusion if it has designations for more than one rare disease or condition, or if is approved for an indication that is not within that single designated rare disease or condition, unless such additional designation or such disqualifying approvals are withdrawn by the time CMS evaluates the drug for selection for negotiation. The IRA also penalizes drug manufacturers that increase prices of Medicare Part B and Part D drugs at a rate greater than the rate of inflation and requires manufacturers that wish for their drugs to be covered by Medicare Part D to provide statutorily defined discounts to Part D enrollees. For example, ZYNLONTA is considered an innovative product and therefor may be subject to certain provisions of the IRA including penalties associated with inflation rebates relative to Medicare Part-B. The IRA permits the Secretary of HHS to implement many of these provisions through guidance, as opposed to regulation, for the initial years. Manufacturers that fail to comply with the IRA may be subject to various penalties, some significant, including civil monetary penalties. The IRA also extends enhanced subsidies for individuals purchasing health insurance coverage in ACA marketplaces through plan year 2025. These provisions began taking effect progressively in 2023, although they may be subject to legal challenges. Thus, while it is unclear how the IRA will be implemented, we expect that we will be liable for price increase penalties under the IRA and that the IRA will negatively impact our gross-to-net adjustment for ZYNLONTA sales.

Individual states in the United States have also become increasingly active in passing legislation and implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers will be included in their prescription drug and other healthcare programs.

We expect that additional state and federal healthcare reform measures will be adopted in the future. Any adopted healthcare reform measure could reduce the ultimate demand for our products or put pressure on our product pricing. It is likely that federal and state legislatures within the United States and foreign governments will continue to consider changes to existing healthcare legislation. We cannot predict the reform initiatives that may be adopted in the future or whether initiatives that have been adopted will be repealed or modified.

To successfully commercialize our products, we must attract and retain qualified selling and marketing personnel and attain significant market acceptance of our products. We face significant competition for qualified personnel. See “—We face substantial competition, which may result in others discovering, developing or commercializing products, treatment methods or technologies before or more successfully than we do.” Establishing market acceptance of our products among physicians, patients, patient advocacy groups, third-party payors and the medical community is complex and resource intensive. The risk of our inability to establish market acceptance may be heightened as our products represent novel treatment methods and be influenced by factors beyond our control, including perceptions of ADC products generally or those of our competitors and coverage and reimbursement for our products. Further, changes to our commercialization strategy may result in disruptions to and adverse impacts on our commercialization efforts. For example, the change in commercialization model in 2023 caused significant disruption to our commercialization efforts. If we do not successfully commercialize our products, we may not generate significant product revenues and may not receive a satisfactory return on our investment into the research and development of those products.

Alternatively, we have established collaborations with third parties to commercialize our product. See “Item 1. Business—Material Contracts.” In such collaborations, we depend on the performance of the contractual counterparty, over which we have limited control. Therefore, such collaborations may generate lower product revenues or profit than if we were to commercialize our products ourselves. We may wish to establish additional collaborations with third parties to commercialize our product. We may not be successful in entering into such marketing and distribution arrangements with third parties or in entering in such marketing and distribution arrangements with third parties on favorable terms. Moreover, such arrangements are complex and time-consuming to negotiate, document and implement and they may require substantial resources to maintain.

In both domestic and foreign markets, sales of our products will depend substantially on the extent to which the costs of our products will be covered by third-party payors, such as government health programs, commercial insurance and managed healthcare organizations. These third-party payors decide which products will be covered and establish reimbursement levels for those products. If coverage and adequate reimbursement are not available, or are available only to limited levels, we may not be able to successfully commercialize our products.

Obtaining coverage approval and reimbursement from a government or other third-party payor is a time-consuming and costly process that could require us to provide supporting scientific, clinical and cost-effectiveness data for the use of our products to the payor, which we may be unable to provide. In particular, there is significant uncertainty related to the insurance coverage and reimbursement of newly approved products. In the United States, there is no uniform policy for coverage and reimbursement and, as a result, coverage and reimbursement can differ significantly from payor to payor. The principal decisions about reimbursement for new medicines are typically made by the CMS, which decides whether and to what extent a new medicine will be covered and reimbursed under Medicare. Private payors often, but not always, follow the CMS’s decisions regarding coverage and reimbursement. Further, coverage policies and third-party payor reimbursement rates may change at any time. It is difficult to predict what third-party payors will decide with respect to coverage and reimbursement for fundamentally novel products such as ours, as there is no body of established practices and precedents for these new products. Further, one payor’s determination to provide coverage and adequate reimbursement for a product does not assure that other payors will also provide coverage and adequate reimbursement for that product. In Europe, pricing and reimbursement schemes may be more restrictive than those in the United States and vary widely from country to country and may require additional clinical trials and additional cost-effectiveness assessments. Many foreign jurisdictions provide nationalized healthcare which may impact the ability to obtain coverage or the amount of reimbursement. In addition, countries may restrict the price of products through the use of nationalized tender processes, controls on the profitability of drug companies, guidance to physicians to limit prescriptions, reference pricing and parallel distribution. Furthermore, many countries have increased the amount of discounts required on pharmaceutical products. This risk may be heightened by our collaboration with Sobi, pursuant to which we do not control the commercialization of, including obtaining coverage and reimbursement for, ZYNLONTA. The downward pressure on healthcare costs in general, and prescription products in particular, has become increasingly intense.

Furthermore, the containment of healthcare costs has become a priority of governments and private third-party payors. Governments and private third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. We also expect to experience pricing pressures due to the trend towards managed healthcare, the increasing influence of health maintenance organizations and additional legislative changes. In particular, we contract with group purchasing organizations, which increases our gross-to-net deductions. These and other cost-control initiatives could cause us to decrease the price we might establish for products, which could result in lower-than-anticipated product revenues. In addition, the publication of discounts by third-party payors or authorities may lead to further pressure on the prices or reimbursement levels within the country of publication and other countries. If pricing is set at unsatisfactory levels or if coverage and adequate reimbursement of our products is unavailable or limited in scope or amount, our revenues and the potential profitability of our products in those countries would be negatively affected.

Our products and product candidates are complex and difficult to manufacture. Problems with the manufacturing process, including even minor deviations from the normal process, could result in product defects or manufacturing failures that result in lot failures, product recalls, product liability claims, and insufficient inventory, negative impact on our sales and results of operations and make us a less attractive collaborator for potential partners. We may encounter problems achieving adequate quantities and quality of clinical-grade materials that meet FDA, EMA or other applicable standards or specifications with consistent and acceptable production yields and costs.

In the past, we have received batches of certain of ZYNLONTA and our product candidates that did not meet our specifications. There can be no assurance that manufacturing issues will not occur in the future. We currently rely on third parties to manufacture all our raw materials, components and finished products, many of which are sole source suppliers, and this risk may be heightened by our reliance on contract manufacturing organizations (“CMOs”) to produce our products and product candidates. See “—Risks Related to Our Relationship with Third Parties.” In particular, our products, product candidates and research pipeline use highly potent cytotoxins and payloads and complex conjugation technology that require special manufacturing and handling, which may subject us to liability for any contamination or injury, or failure to comply with environmental, health and safety laws and regulations.

Increases in the costs and expenses of components or raw materials may also adversely influence our business, results of operations and financial condition. Supply sources could be interrupted from time to time and, if interrupted, it is not certain that supplies could be resumed, whether in part or in whole, within a reasonable time frame and at an acceptable cost, or at all. This risk is heightened by our use of sole source suppliers. The cost to manufacture our products could be significantly greater than we expect, which could limit the market acceptance of our products or reduce our potential profit on such product sales.

Furthermore, given the nature of biologics manufacturing, there is a risk of contamination during manufacturing. Any contamination could materially harm our ability to produce products and product candidates on schedule and could cause reputational damage. Some of the raw materials required in our manufacturing process are derived from biologic sources, which are difficult to procure and may be subject to contamination or recall. A material shortage, contamination, recall or restriction on the use of biologically derived substances in the manufacture of any products or product candidates could adversely impact or disrupt the commercial manufacturing or the production of clinical material, which could materially harm our development timelines and our business, financial condition, results of operations and prospects.

Our projections of the number of people who have the cancers we are targeting, as well as the subset of people with these cancers in a position to receive a certain line of therapy and who have the potential to benefit from treatment with our products and product candidates, are based on estimates derived from a variety of sources, including scientific literature, surveys of clinicians and healthcare professionals and other forms of market research. These estimates may be inaccurate or based on imprecise data and are based on assumptions such as labeling, acceptance, patient access and pricing and reimbursement. The number of patients in the addressable markets may turn out to be lower than expected, new treatments may be approved in the future which may reduce our potential patient population, patients may not be otherwise amenable to treatment with our products and product candidates or new patients may become increasingly difficult to identify or gain access to, all of which could negatively impact our market opportunity estimate and materially adversely affect our business, financial condition, results of operations and prospects.

Our industry is characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products. We face competition with respect to our current products and product candidates and will face competition with respect to any products and product candidates that we may seek to develop or commercialize in the future. Our competitors include large pharmaceutical and biotechnology companies, academic institutions, government agencies and other public and private research organizations that conduct research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and commercialization. Many of our competitors have significantly greater financial resources and capabilities in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approval and marketing than we do. Furthermore, mergers and acquisitions in the biotechnology industry may result in even more resources being concentrated among a smaller number of our competitors.

Many companies are active in the oncology market and are developing or marketing products for the specific therapeutic markets that we target, including both antibody- and non-antibody-based therapies. Similarly, we also face competition from other companies and institutions that continue to invest in innovation in the ADC field, including new payload classes, new conjugation approaches and new targeting moieties. Specifically, we are aware of multiple companies with ADC technologies that may be competitive with our products and product candidates, including, but not limited to, AbbVie, Inc., Daiichi Sankyo Company, GlaxoSmithKline plc, Gilead Sciences, Inc., Mersana Therapeutics Inc., Sanofi S.A., Roche Holding AG, Pfizer Inc. and Zymeworks, Inc. There are hundreds of ADCs in development, the vast majority of which were being developed for the treatment of cancer.

In the relapsed or refractory DLBCL setting, for which we are commercializing ZYNLONTA, current third-line treatment options include CAR-T, allogeneic stem cell transplant, polatuzumab in combination with bendamustine and a rituximab product, selinexor, tafasitamab in combination with lenalidomide, chemotherapy using small molecules and bispecifics. If ZYNLONTA is approved for use as a second-line treatment for DLBCL patients, we will continue to compete with CAR-T, autologous stem cell transplant, rituximab in combination with chemotherapies, polatuzumab in combination with bendamustine and a rituximab product, and tafasitamab in combination with lenalidomide. In addition, we expect changes to the treatment paradigm, including potential new entrants and new approvals in the second-line setting. New technologies, procedures or treatments could render our products and product candidates obsolete and there can be no assurance that our products and product candidates would be able to compete effectively. If we are unable to compete with these new treatment options, physicians may not utilize our products and our future revenues and estimates may be negatively impacted.

We rely, and we expect that we will continue to rely, on CROs and other third parties to assist in managing, monitoring and otherwise carrying out preclinical studies and clinical trials of our products and product candidates and CMOs and other third parties for the manufacture, production, storage and distribution of our products and product candidates and certain commercialization activities for our products, including government pricing, reporting and chargeback and rebate processing, pharmacovigilance and adverse event reporting. We have less control over the activities of third parties than we would otherwise have if we relied entirely upon our own staff and we are exposed to different risks, including all the risks associated with such third parties’ businesses and financial condition, than if we performed such functions ourselves. There can be no assurance that these third parties will perform services for us in accordance with our timelines, standards and expectations. If these third parties do not successfully carry out their duties under their agreements or otherwise fail to comply with regulatory requirements, we may experience delays in our research and development activities, be unable to obtain and maintain regulatory approval, be unable to commercialize our products and be required to issue product recalls. In addition, if any of our relationships with these third parties terminate, we may not be able to enter into alternative arrangements on a timely basis or on commercially reasonable terms, and even if successful in entering into alternative arrangements, we may experience significant delays during the transition. This risk may be heightened by our use of single-source supplier arrangements. Furthermore, if a CMO or other third-party manufacturer cannot maintain a compliance status acceptable to the FDA, or if the EMA or a comparable regulatory authority in another jurisdiction does not approve these facilities for the manufacture of our products and product candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would be time-consuming, costly and uncertain and significantly impact our ability to develop, obtain regulatory approval for, source adequate supply of or market our products and product candidates.

We have entered into, and may in the future may enter into, collaboration agreements with third parties for the development and commercialization for products, product candidates and/or research programs. See “Item 1. Business—Material Contracts” for a description of such agreements that are material to us. There can be no assurance that we will be able to enter into additional collaboration agreements on favorable terms, or at all. Even if we are successful in our efforts to establish collaborations, we may not be able to maintain such collaborations if, for example, development or approval of a product or product candidate is delayed or sales of an approved product are disappointing. If we fail to establish and maintain collaborations, we could bear all of the risk and costs related to the development and commercialization of any such product or product candidate, which may require us to seek additional financing, hire additional employees and otherwise develop expertise for which we have not budgeted, and may have a detrimental effect on our financial position by reducing or eliminating the potential for us to receive technology access and license fees, milestones and royalties, and/or reimbursement of development costs.

In such collaborations, we will depend on the performance of our collaborators. Our collaborators may fail to perform their obligations under the collaboration agreements or may not perform their obligations in a timely manner. If conflicts arise between our collaborators and us, the other party may act in a manner adverse to us and could limit our ability to implement our strategies.

Furthermore, our collaborators may not properly obtain, maintain, enforce or defend our intellectual property or proprietary rights or may use our proprietary information in such a way as to invite litigation that could jeopardize or invalidate our proprietary information or expose us to potential litigation. In addition, we cannot control the amount and timing of resources our collaborators may devote to our products and product candidates. They may separately pursue competing products, therapeutic approaches or technologies to develop treatments for the diseases targeted by us. Competing products, either developed by the collaborators or to which the collaborators have rights, may result in the withdrawal of support for our products and product candidates. Even if our collaborators continue their contributions to the strategic collaborations, they may nevertheless determine not to actively pursue the development or commercialization of any resulting products. Additionally, if our collaborators pursue different clinical or regulatory strategies with their product candidates based on similar technology as is used in our products and product candidates, adverse events with their product candidates could negatively affect our products and product candidates. Any of these developments could harm our development and commercialization efforts, which adversely impact our business and operations.

Our success depends in significant part on our own and any of our licensors’ ability to obtain, maintain and protect patents and other intellectual property rights and operate without infringing, misappropriating, or otherwise violating the intellectual property rights of others. To protect our proprietary position, we have filed numerous patent applications both in the United States and in foreign jurisdictions to obtain patent rights to inventions we have developed that are important to our business. We have also licensed from third parties rights to patents and other intellectual property, including from MedImmune with respect to the PBD technology we use for our PBD-based ADCs and from other parties for some of our other product candidates and related technology. If we or our current or future licensors are unable to obtain or maintain patent protection with respect to such inventions and technology, our business, financial condition, results of operations and prospects could be materially harmed.

The patent prosecution process is expensive, time-consuming and complex and uncertain, and we and our current or future licensors may not be able to prepare, file, prosecute, maintain and enforce all necessary or desirable patent applications at a reasonable cost or in a timely manner. Patents may be invalidated and patent applications may not be granted for a number of reasons, including known and unknown prior art (including our own prior art), deficiencies in the patent applications or the lack of novelty of the underlying inventions or technology. It is also possible that we or our current and future licensors will fail to identify patentable aspects of inventions made in the course of research, development and commercialization activities in time to obtain patent protection. Although we enter into non-disclosure and confidentiality agreements with parties who have access to confidential or patentable aspects of our research, development and commercialization activities, such as our employees, corporate collaborators, outside scientific collaborators, CROs, consultants, advisors and other third parties, any of these parties may breach the agreements and disclose such activities before a patent application is filed, thereby jeopardizing our ability to seek patent protection. In addition, publications of discoveries in the scientific literature often lag behind actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until eighteen months after filing, or in some cases not at all. Therefore, we cannot be certain that we or our current or future licensors were the first to make the inventions claimed in our owned or licensed patents or patent applications, or that we or our current or future licensors were the first to file for patent protection of such inventions.

Moreover, in some circumstances, we may not have the right to control the preparation, filing, prosecution, maintenance, enforcement and defense of patents and patent applications covering technology that we license from third parties, and are reliant on our licensors. For example, pursuant to our agreements with MedImmune, MedImmune retains control of the preparation, filing, prosecution, maintenance, enforcement and defense of certain of the patents and patent applications licensed to us. Therefore, these patents and applications may not be prepared, filed, prosecuted, maintained, enforced and defended in a manner consistent with the best interests of our business. If our current or future licensors fail to prosecute, maintain, enforce or defend such patents and other intellectual property rights, are not fully cooperative or disagree with us as to the prosecution, maintenance or enforcement of any patent rights, or lose rights to those patents or patent applications, the rights that we have licensed may be reduced or eliminated, and our right to develop and commercialize any of our products and product candidates that are the subject of such licensed rights could be adversely affected.

The patent position of biotechnology companies generally is highly uncertain, involves complex legal and factual questions and has, in recent years, been the subject of much litigation. As a result, the issuance, scope, validity, enforceability and commercial value of our and our current or future licensors’ patent rights are highly uncertain. Our owned and licensed pending and future patent applications may not result in patents being issued which protect the products or technologies we develop, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. Moreover, the patent examination process may require us or our current and future licensors to narrow the scope of the claims of our owned or licensed pending and future patent applications, which may limit the scope of patent protection that may be obtained. Additionally, the scope of patent protection can be reinterpreted after issuance. Even if our owned or licensed pending and future patent applications issue as patents, they may not issue in a form that will provide us with any meaningful protection, prevent competitors or other third parties from competing with us, or otherwise provide us with any competitive advantage. Any patents that we hold or in-license may be challenged, narrowed, circumvented or invalidated by third parties in court or in patent offices in the United States and abroad. Our owned or licensed patent applications cannot be enforced against third parties practicing the technology claimed in such applications unless and until a patent issues from such applications, and then, only to the extent the issued claims cover the technology. Our competitors or other third parties may also be able to circumvent our patents by developing similar or alternative technologies or products in a non-infringing manner.

We may be subject to a third-party pre-issuance submission of prior art to the United States Patent and Trademark Office (“USPTO”). We cannot assure you that all of the potentially relevant prior art relating to our patents and patent applications has been found. If such prior art exists, it can invalidate a patent or prevent a patent from issuing from a pending patent application. Even if patents do successfully issue and even if such patents cover our products and product candidates, third parties may initiate an opposition, interference, reexamination, post-grant review, inter partes review, nullification or derivation action in court or before patent offices, or other proceedings challenging the inventorship, validity, enforceability or scope of such patents, which may result in the patent claims being narrowed or invalidated. An adverse determination in any such proceeding or litigation could reduce the scope of, or invalidate, the patent rights we own or license, allow third parties to commercialize the products or technologies we develop and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize products without infringing third-party patent rights. Such proceedings also may result in substantial cost and require significant time and attention from our scientific and management personnel, even if the eventual outcome is favorable to us. Consequently, there can be no assurance that any product, product candidate or technology we develop will be protectable or remain protected by valid and enforceable patents. In addition, if the breadth or strength of protection provided by our patents or patent applications is threatened, regardless of the outcome, it could dissuade companies from collaborating with us to license, develop or commercialize current or future products and product candidates.

Because patent applications in the United States and most other countries are confidential for a period of time after filing, and some remain so until issued, we cannot be certain that we or our current and future licensors were the first to file any patent application related to a product or product candidate. Furthermore, if third parties have filed such patent applications on or before March 15, 2013, an interference proceeding in the United States can be initiated by such third parties to determine who was the first to invent any of the subject matter covered by the patent claims of our applications. If third parties have filed such applications after March 15, 2013, a derivation proceeding in the United States can be initiated by such third parties to determine whether our invention was derived from theirs. Even where we have a valid and enforceable patent, we may not be able to exclude others from practicing our invention where the other party can show that they used the invention in commerce before our filing date or the other party benefits from a compulsory license. Any of the foregoing could have a material adverse effect on our business, results of operations, financial condition and prospects.

Competitors and other third parties may infringe, misappropriate or otherwise violate our issued patents or other intellectual property or the patents or other intellectual property of our licensors. To protect our competitive position, we or our licensors may, from time to time, resort to litigation in order to enforce or defend any patents or other intellectual property rights owned by or licensed to us, or to determine or challenge the scope or validity of patents or other intellectual property rights of third parties. Enforcement of intellectual property rights is difficult, unpredictable and expensive, and many of our or our licensors’ or collaboration partners’ adversaries in these proceedings may have the ability to dedicate substantially greater resources to prosecuting these legal actions than we or our licensors or collaboration partners can. Accordingly, despite our or our licensors’ or collaboration partners’ efforts, we or our licensors or collaboration partners may not prevent third parties from infringing upon, misappropriating or otherwise violating intellectual property rights we own or control, particularly in countries where the laws may not protect those rights as fully as in the United States and the European Union.

Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. We may fail in enforcing our rights, in which case third parties, including our competitors, may be permitted to use our technology without being required to pay us any license fees.

If we or one of our current or future licensors were to initiate legal proceedings against a third party to enforce a patent covering one of our products or product candidates, the defendant could counterclaim that such patent is invalid or unenforceable. In patent litigation in the United States and in Europe, defendant counterclaims alleging invalidity or unenforceability are commonplace. A claim for a validity challenge may be based on failure to meet any of several statutory requirements, for example, lack of novelty, obviousness or non-enablement. A claim for unenforceability could involve an allegation that someone connected with prosecution of the patent withheld relevant information from the USPTO or the European Patent Office or made a misleading statement during prosecution. Third parties may also raise similar claims before the USPTO or an equivalent foreign body, even outside the context of litigation. Potential proceedings include reexamination, post-grant review, inter partes review, interference proceedings, derivation proceedings and equivalent proceedings in foreign jurisdictions (e.g., opposition proceedings). Such proceedings could result in the revocation of, cancellation of, or amendment to our patents in such a way that they no longer cover our technology or any products or product candidates that we may develop. The outcome following legal assertions of invalidity and unenforceability during patent litigation is unpredictable. If a defendant were to prevail on a legal assertion of invalidity or unenforceability, we would lose at least part, and perhaps all, of the patent protection on one or more of our products or product candidates or certain aspects of the technology we use in our products and product candidates, and third parties, including our competitors, could compete directly with us, without payment to us. Such a loss of patent protection could have a material adverse impact on our business, financial condition, results of operations and prospects. Further, litigation could result in substantial costs and diversion of management resources, regardless of the outcome, and this could harm our business and financial results. Patents and other intellectual property rights also will not protect our technology if competitors design around our protected technology without infringing our patents or other intellectual property rights.

In addition, our patents or the patents of our licensors may become involved in inventorship or priority disputes. Interference proceedings provoked by third parties or brought by us or declared by the USPTO may be necessary to determine the priority of inventions with respect to our or our licensors’ patents or patent applications. If we or our licensors are unsuccessful in any interference proceedings to which we or they are subject, we may lose valuable intellectual property rights through the loss of one or more patents owned or licensed or our owned or licensed patent claims may be narrowed, invalidated or held unenforceable. If we or our licensors are unsuccessful in any interference proceeding or other priority or inventorship dispute, we may be required to obtain and maintain licenses from third parties, including parties involved in any such interference proceedings or other priority of inventorship disputes. Such licenses may not be available on commercially reasonable terms or at all, or may be non-exclusive. If we are unable to obtain and maintain such licenses, we may need to cease the development, manufacture and commercialization of one or more of the products and product candidates we may develop. The loss of exclusivity or narrowing of our owned or licensed patent claims could limit our ability to stop others from using or commercializing similar or identical technology and products. Any of the foregoing could have a material adverse effect on our business, results of operations, financial condition and prospects.

We are party to a number of intellectual property and technology licenses that are important to our business. For example, the PBD technology we use to generate our PBD-based ADCs was developed by, and is licensed on a target-exclusive basis from, MedImmune. If we fail to comply with our obligations under these or our other agreements, including payment and diligence terms, our current and future licensors may have the right to terminate these agreements, in which event we may not be able to develop, manufacture, market or sell any product that is covered by these agreements or may face other penalties under these agreements. Such an occurrence could adversely affect the value of the products and product candidates being developed under any such agreement. Termination of these agreements or reduction or elimination of our rights under these agreements may result in our having to negotiate new or reinstated agreements, which may not be available to us on equally favorable terms, or at all, or cause us to lose our rights under these agreements, including our rights to intellectual property or technology important to our development programs. Accordingly, termination of these agreements may require us to cease the development of our products and product candidates.

In addition, the agreements under which we license intellectual property or technology from third parties are generally complex, and certain provisions in such agreements may be susceptible to multiple interpretations. The resolution of any contract interpretation disagreement that may arise could narrow what we believe to be the scope of our rights to the relevant intellectual property or technology, or increase what we believe to be our financial or other obligations under the relevant agreements. Moreover, if disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on commercially acceptable terms, we may be unable to successfully develop and commercialize the affected products and product candidates. Any of the foregoing could have a material adverse effect on our business, financial condition, results of operations and prospects.

A third party may hold intellectual property, including patent rights, that is important or necessary to the development of our products and product candidates. In order to avoid infringing these third-party patents, we may find it necessary or prudent to obtain licenses from such third-party intellectual property holders. Moreover, we may need to obtain additional licenses from our existing licensors and others to advance our research or allow commercialization of products and product candidates we may develop. In addition, many of our patents are co-owned with MedImmune, which licenses its interest in such patents to us. With respect to any patents we co-own with third parties, we may require licenses to such co-owners’ interest to such patents. In addition, we may need the cooperation of any co-owners of our patents in order to enforce such patents against third parties, and such cooperation may not be provided to us. We may be unable to secure such licenses or otherwise acquire or in-license any compositions, methods of use, processes or other intellectual property rights from third parties that we identify as necessary for products and product candidates we develop. The licensing or acquisition of third-party intellectual property rights is a competitive area, and more established companies may pursue strategies to license or acquire third-party intellectual property rights that we may consider attractive or necessary. These established companies may have a competitive advantage over us due to their size, capital resources and greater clinical development or commercialization capabilities. In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. As a result, we may be unable to obtain any such licenses at a reasonable cost or on reasonable terms, if at all. In that event, we may be required to expend significant time and resources to redesign our technology, products, product candidates or the methods for manufacturing them or to develop or license replacement technology, all of which may not be feasible on a technical or commercial basis. If we are unable to do so, we may be unable to develop or commercialize the affected products and product candidates, which could significantly harm our business, financial condition, results of operations and prospects. In addition, even if we obtain a license, it may be non-exclusive, thereby giving third parties, including our competitors, access to the same technologies licensed to us. In addition, any license we obtain could require us to make substantial licensing and royalty payments. If we are unable to obtain an exclusive license to any third-party or co-owned patents or patent applications, such parties may be able to license their rights to other third parties, including our competitors, and such third parties could market competing products and technology. Any of the foregoing could have a material adverse effect on our business, results of operations, financial condition and prospects.

Our commercial success depends upon our ability to develop, manufacture, market and sell our products and product candidates and use our and our current or future licensors’ proprietary technologies without infringing, misappropriating or otherwise violating the intellectual property rights of third parties. Third parties may initiate legal proceedings against us or our current and future licensors alleging that we or our current and future licensors infringe, misappropriate or otherwise violate their intellectual property rights. In addition, we and our licensors have initiated, and we and our current and future licensors may in the future initiate, legal proceedings against third parties to challenge the validity or scope of intellectual property rights controlled by third parties, including in oppositions, interferences, reexaminations, inter partes reviews or derivation proceedings in the United States or other jurisdictions. These proceedings can be expensive and time-consuming, and many of our or our current and future licensors’ adversaries in these proceedings may have the ability to dedicate substantially greater resources to prosecuting these legal actions than we or our current and future licensors. Numerous U.S.- and foreign-issued patents and pending patent applications which are owned by third parties exist in the fields in which we are pursuing our products and product candidates. We are aware of a patent family with issued claims that could be construed to cover the linker in ADCT-601. As the biotechnology and pharmaceutical industries expand and more patents are issued, the risk increases that we may be subject to claims of infringement of the patent rights of third parties.

There are, and in the future, we may identify, other third-party patents or patent applications with claims to materials, formulations, methods of manufacture or methods for treatment related to the use or manufacture of one or more of our products and product candidates. Because patent applications can take many years to issue, there may be currently pending patent applications that may later result in issued patents that our products and product candidates may infringe. In addition, third parties may obtain patents in the future and claim that use of our technologies infringes upon these patents. Parties making infringement, misappropriation or other intellectual property claims against us may obtain injunctive or other equitable relief, which could effectively block our ability to further develop and commercialize one or more of our products and product candidates. Defense of these claims, regardless of their merit, would involve substantial litigation expense and would be a substantial diversion of management and employee resources. In addition, even if we believe any third-party intellectual property claims are without merit, there is no assurance that a court would find in our favor on questions of validity, enforceability, priority or non-infringement. A court of competent jurisdiction could hold that such third-party patents are valid, enforceable and infringed, which could materially and adversely affect our ability to commercialize any of our products, product candidates or technologies covered by the asserted third-party patents. In order to successfully challenge the validity of any such third-party U.S. patents in federal court, we would need to overcome a presumption of validity. As this burden is a high one requiring us to present clear and convincing evidence as to the invalidity of any such U.S. patent claim, there is no assurance that a court of competent jurisdiction would invalidate the claims of any such U.S. patent. An unfavorable outcome could require us or our current and future licensors to cease using the related technology or developing or commercializing our products and product candidates, or to attempt to license rights to it from the prevailing party. If we are not successful in defending a third-party claim of infringement, we may be enjoined from continuing to sell our products or our business could be harmed if the prevailing party does not offer us or our current and future licensors a license on commercially reasonable terms or at all. Even if we or our current and future licensors obtain a license, it may be non-exclusive, thereby giving our competitors access to the same technologies licensed to us or our current and future licensors, and it could require us to make substantial licensing and royalty payments. In addition, we could be found liable for monetary damages, including treble damages and attorneys’ fees, if we are found to have willfully infringed a patent. A finding of infringement, misappropriation or other violation of third-party intellectual property could prevent us from commercializing our products and product candidates or force us to cease some of our business operations, which could harm our business. Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar material adverse effect on our business, results of operations, financial condition and prospects. Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation or administrative proceedings, there is a risk that some of our confidential information could be compromised by disclosure.

Many of our employees, consultants, and advisors, including our senior management, were previously employed at other biopharmaceutical companies, including our competitors or potential competitors. Some of these employees executed proprietary rights, non-disclosure and/or non-competition agreements in connection with such previous employment. Although we try to ensure that our employees, consultants and advisors do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or these individuals have used or disclosed confidential information or intellectual property, including trade secrets or other proprietary information, of any such individual’s current or former employer. Litigation may be necessary to defend against these claims. If we fail in defending against any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Such intellectual property rights could be awarded to a third party, and we could be required to obtain a license from such third party to commercialize our technology or products. Such a license may not be available on commercially reasonable terms, or at all.

In addition, while it is our policy to require our employees and contractors who may be involved in the conception or development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who, in fact, conceives or develops intellectual property that we regard as our own. The assignment of intellectual property rights may not be self-executing, or the assignment agreements may be breached, and we may be forced to bring claims against third parties, or defend claims that they may bring against us, to determine the ownership of what we regard as our intellectual property. Such claims could have a material adverse effect on our business, results of operations, financial condition and prospects.

Obtaining and enforcing patents in the biopharmaceutical industry involves both technological and legal complexity and is therefore costly, time-consuming and inherently uncertain. Changes in either the patent laws or the interpretation of the patent laws in the United States or other jurisdictions could increase the uncertainties and costs surrounding the prosecution of patent applications and the enforcement or defense of issued patents. Depending on future actions by the U.S. Congress, the U.S. courts, the USPTO and the relevant law-making bodies in other countries, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future.

Patents have a limited lifespan. Due to the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our owned and licensed patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours. In the United States, if all maintenance fees are timely paid, the natural expiration of a patent is generally 20 years from its earliest U.S. non-provisional filing date. Patent terms vary in other jurisdictions. Various extensions may be available, including under the Drug Price Competition and Patent Term Restoration Action of 1984 (the “Hatch-Waxman Amendments”) in the United States, but the life of a patent, and the protection it affords, is limited. Even if patents covering our product candidates are obtained, once the patent life has expired for a product, we may be open to competition from competitive medications, including biosimilar or generic medications. At the time of the expiration of any relevant patents, the underlying technology covered by such patents can be used by any third party, including competitors.

Filing, prosecuting, enforcing and defending patents on products and product candidates in all countries throughout the world would be prohibitively expensive, and our owned or licensed intellectual property rights may not exist in some countries outside the United States or may be less extensive in some countries than in the United States. In addition, the laws of some foreign countries do not protect intellectual property rights to the same extent as federal and state laws in the United States. For example, in some jurisdictions, including Europe, it is more difficult to obtain patents protecting a medical method of use, and any such patents we are able to obtain in such jurisdictions may issue with narrower scope than their U.S. counterparts. Many countries have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties, and many countries limit the enforceability of patents against government agencies or government contractors. In these countries, the patent owner may have limited remedies, which could materially diminish the value of such patent. Consequently, we and our current and future licensors may not be able to prevent third parties from practicing our owned or licensed inventions in all countries outside the United States, or from selling or importing products made using our owned or licensed inventions in and into the United States or other jurisdictions.

In addition to seeking patents for some of our technology, products and product candidates, we also rely on trade secrets, including unpatented know-how, technology and other proprietary information to maintain our competitive position. Trade secrets can be difficult to protect. We seek to protect these trade secrets, in part, by entering into non-disclosure, confidentiality and invention assignment agreements with parties who have access to them, such as our employees, corporate collaborators, outside scientific collaborators, CROs, contract manufacturers, consultants, advisors and other third parties. We also enter into confidentiality agreements with our employees and consultants. However, there can be no assurance that we have entered into such agreements with each party that may have or have had access to our trade secrets or proprietary technology and processes. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. Misappropriation or unauthorized disclosure of our trade secrets could significantly affect our competitive position and may have a material adverse effect on our business.

Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. Some courts both within and outside the United States may be less willing or unwilling to protect trade secrets. Furthermore, trade secret protection does not prevent competitors from independently developing substantially equivalent information and techniques, and we cannot guarantee that our competitors will not independently develop substantially equivalent information and techniques.

If a competitor lawfully obtained or independently developed any of our trade secrets, we would have no right to prevent such competitor from using that technology or information to compete with us. Failure on our part to adequately protect our trade secrets or confidential information could have a material adverse effect on our business, results of operations, financial condition and prospects.

Our registered or unregistered trademarks or trade names may be challenged, circumvented, declared generic or determined to be infringing on other marks. There can be no assurance that competitors will not infringe our trademarks, that we will have adequate resources to enforce our trademarks or that any of our current or future trademark applications will be approved. During trademark registration proceedings, we may receive rejections and, although we are given an opportunity to respond, we may be unable to overcome such rejections. In addition, in proceedings before the USPTO and in proceedings before comparable agencies in many foreign jurisdictions, trademarks are examined for registrability against prior pending and registered third-party trademarks, and third parties are given an opportunity to oppose registration of pending trademark applications and/or to seek cancellation of registered trademarks. Applications to register our trademarks may be finally rejected, and opposition or cancellation proceedings may be filed against our trademarks, which may necessitate a change in branding strategy if such rejections and proceedings cannot be overcome or resolved. For example, in some jurisdictions the applicable trademark office has rejected our corporate name for registration, or a third party has objected to a published application for a product trademark, which, in some cases, has caused us to abandon or limit our applications, and rely more on the registration for our corporate logo.

Our ability to compete in the highly competitive biotechnology industry depends upon our ability to attract, motivate and retain highly qualified managerial, scientific and medical personnel. The loss of the services of our other senior management members, other key employees and scientific and medical advisors could impede the achievement of our research, development and commercialization objectives. Members of our senior management are employed pursuant to employment agreements with no term and that require advance notice for termination, but these persons may terminate their employment with us at any time. In addition, laws and regulations on executive compensation, including legislation in our home country, Switzerland, may restrict our ability to attract, motivate and retain the required level of qualified personnel including those that (i) impose an annual binding shareholders’ “say-on-pay” vote with respect to the compensation of the members of the executive committee and the board of directors, (ii) prohibit severance, advances, transaction premiums and similar payments to the members of the executive committee and the board of directors, and (iii) require companies to specify various compensation-related matters in their articles of association, thus requiring them to be approved by a shareholders’ vote. We do not maintain “key person” insurance for any of our executives or other employees. Further, we compensate our employees, in part, using share-based compensation, the effectiveness of which is influenced by the price of our common shares. If the price of our common shares continues to decrease or is subject to continued volatility, which may occur for various factors, including those beyond our control, we may be unable to attract or retain qualified personnel. Competition for skilled personnel is intense, particularly in the biotechnology industry. We face competition for personnel from other companies, universities, public and private research institutions and other organizations. This competition may limit our ability to hire and retain highly qualified personnel on acceptable terms, or at all. This possibility is further compounded by the novel nature of our product candidates, as fewer people are trained in or are experienced with product candidates of this type.

We cannot ensure that our compliance controls, policies and procedures will in every instance protect us from acts committed by our employees, agents, contractors or collaborators that would violate the laws or regulations of the jurisdictions in which we operate, including, without limitation, healthcare, employment, foreign corrupt practices, environmental, competition, and patient privacy and other privacy laws and regulations. In particular, because we operate globally and our business is heavily regulated and therefore involves significant interaction with public officials and because the healthcare providers and drug purchasers in certain countries are employed by their government, we face heightened risk with respect to compliance with the Foreign Corrupt Practices Act (the “FCPA”). There is no certainty that all of our employees, agents, contractors, or collaborators, or those of our affiliates, will comply with all applicable laws and regulations, particularly given the high level of complexity of these laws. We have provisions in our Code of Business Conduct and Ethics, an anti-corruption policy and certain controls and procedures in place that are designed to mitigate the risk of non-compliance with anti-corruption and anti-bribery laws.

However, it is not always possible to identify and deter employee misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from government investigations or other actions stemming from a failure to comply with these laws or regulations. Violations of these laws and regulations could result in, among other things, significant administrative, civil and criminal fines and sanctions against us, our officers, or our employees, the closing of our facilities, exclusion from participation in federal healthcare programs including Medicare and Medicaid, implementation of compliance programs, integrity oversight and reporting obligations, and prohibitions on the conduct of our business.

We face an inherent risk of product liability and product recalls as a result of the clinical testing of our product candidates in human clinical trials and as a result of the commercialization of approved products and their use by patients. Side effects or adverse events known or reported to be associated with, or manufacturing defects in, the products sold by us could exacerbate a patient’s condition or could result in serious injury or impairments or even death. This risk is heightened by our use of highly potent ADCs. If we cannot successfully defend ourselves against product liability claims, we may incur substantial liabilities or be required to limit the research and development and commercialization of our products and product candidates. Even a successful defense would require significant financial and management resources. We currently carry product and clinical trial liability insurance in an amount that we believe is appropriate for our business. Although we maintain such insurance, any claim that may be brought against us could result in a court judgment or settlement in an amount that is not covered, in whole or in part, by our insurance or that is in excess of the limits of our insurance coverage. Our insurance policies also have various exclusions, and we may be subject to a product liability claim for which we have no coverage. If we are unable to obtain or maintain sufficient insurance coverage at an acceptable cost or to otherwise protect against potential product liability claims, it could prevent or inhibit the development of our products and product candidates and the commercial production and sale of our products.

To the extent that a product fails to conform to its specifications or comply with the applicable laws or regulations, we or our partners may be required to or may decide to voluntarily recall the product or regulatory authorities may request or require that we recall a product even if there is no immediate potential harm to a patient. Recalls are costly and take time and effort to administer and damage our reputation and attractiveness as a collaborator. Even if a recall only initially relates to a single product, product batch, or a portion of a batch, recalls may later be expanded to additional products or batches or we or our partners may incur additional costs and need to dedicate additional efforts to investigate and rule out the potential for additional impacted products or batches. Moreover, if any of our partners recall a product due to an issue with a product or component that we supplied, they may claim that we are responsible for such issue and may seek to recover the costs related to such recall or be entitled to certain contractual remedies from us. Recalls may further result in decreased demand for our or our partners’ products, could cause our partners or distributors to return products to us for which we may be required to provide refunds or replacement products, or could result in product shortages. Recalls may also require regulatory reporting and prompt regulators to conduct additional inspections of our or our partners’ or contractors’ facilities, which could result in findings of noncompliance and regulatory enforcement actions. A recall could also result in product liability claims by individuals and third-party payers and the suspension, variation, or withdrawal of regulatory approval.

Despite the implementation of security measures, our internal computer systems and those of our current or future partners, third-party CROs and other contractors and consultants have been subject to attacks by, and may be vulnerable to damage from, various methods, including cybersecurity attacks, breaches, intentional or accidental mistakes or errors, or other technological failures which can include, among other things, computer viruses, malicious codes, employee theft or misuse, unauthorized copying of our website or its content, unauthorized access attempts including third parties gaining access to systems using stolen or inferred credentials, denial-of-service attacks, phishing attempts, service disruptions, natural disasters, fire, terrorism, war and telecommunication and electrical failures. As the cyber-threat landscape evolves, these attacks are growing in frequency, sophistication and intensity, and are becoming increasingly difficult to detect. If a failure, accident or security breach were to occur and cause interruptions in our, our partners’ or our CROs’ operations, it could result in a misappropriation of confidential information, including our intellectual property or financial information, a material disruption of our programs and significant monetary losses. In particular, because of our approach to running multiple clinical trials in parallel, any breach of our computer systems may result in a loss of data or compromised data integrity across many of our programs in many stages of development.

Any such breach, loss or compromise of clinical trial participant personal data may also subject us to civil fines and penalties, including under the GDPR and relevant member state law in the European Union, the UK GDPR or the CCPA, HIPAA and other relevant state and federal privacy laws in the United States. Moreover, because we maintain sensitive company data on our computer networks, including our intellectual property and proprietary business information, any such security breach may compromise information stored on our networks and may result in significant data losses or theft of our intellectual property or proprietary business information. We currently carry cybersecurity liability insurance in an amount that we believe is appropriate for our business. However, our current cybersecurity liability insurance, and any such insurance that we may obtain in the future, may not cover the damages we would sustain based on any breach of our computer security protocols or other cybersecurity attack. To the extent that any disruption or security breach results in a loss of or damage to our data or applications or other data or applications relating to our technology, products or product candidates, or inappropriate disclosure of confidential or proprietary information, our reputation could be harmed and we could incur significant liabilities and the development and commercialization of our products and product candidates could be disrupted.

We are a global organization and thus subject to the risks associated with international operations, including inflationary pressures, economic weakness or political instability in particular non-U.S. economies and markets; global trends involving pharmaceutical pricing; differing regulatory requirements for drug approvals in non-U.S. countries; differing reimbursement, pricing and insurance regimes; potentially reduced protection for, and complexities and difficulties in obtaining, maintaining, protecting and enforcing, intellectual property rights; difficulties in compliance with non-U.S. laws and regulations; changes in non-U.S. regulations and customs, tariffs and trade barriers; changes in non-U.S. currency exchange rates and currency controls; changes in a specific country’s or region’s political or economic environment; trade protection measures, economic sanctions and embargoes, import or export licensing requirements or other restrictive actions by U.S. or non-U.S. governments; negative consequences from changes in tax laws; difficulties associated with staffing and managing international operations, including differing labor relations; production shortages resulting from any events affecting raw material supply or manufacturing capabilities abroad; business interruptions resulting from geopolitical actions and conflict, war and terrorism, including the recent conflict between Russia and the Ukraine and resulting sanctions, retaliatory measures, changes in the availability and price of various materials and effects on global financial markets; business interruptions resulting from natural disasters; and the impact of public health epidemics on employees and the global economy. In addition, as a result of the United Kingdom’s exit from the European Union, we may face increasingly divergent regulations in Europe, with which may be expensive and time-consuming for us to comply.

Our business could be adversely affected by health epidemics, pandemics and natural disasters. To the extent any pandemic, epidemic or outbreak of an infectious disease adversely affects our business and financial results, it may also have the effect of heightening many of the other risks described in this “Item 1A. Risk Factors” section. In addition, any unplanned event, such as a flood, fire, explosion, earthquake, extreme weather condition, medical epidemic, power shortage, telecommunication failure or other natural or man-made accidents or incidents that result in us being unable to fully use our facilities, or the manufacturing facilities of our third-party contract manufacturers, may have a material and adverse effect on our ability to operate our business and have significant negative consequences on our financial and operating conditions. Certain of these events may become more frequent and severe as a result of the effects of climate change. Loss of access to these facilities may result in increased costs, reduced revenues, delays in the development of our products and product candidates or the interruption of our business operations for a substantial period of time. We maintain business continuity insurance coverage at levels that we believe are appropriate for our business. However, in the event of an accident or incident at these facilities, there can be no assurance that the amounts of insurance will be sufficient to satisfy any damages and losses. If our facilities, or the manufacturing facilities of our third-party contract manufacturers, are unable to operate because of an accident or incident or for any other reason, even for a short period of time, any or all of our research and development programs and commercialization efforts may be harmed.

Effective internal controls over financial reporting are necessary for us to provide reliable financial reports and, together with adequate disclosure controls and procedures, are designed to prevent fraud. Any failure to implement required new or improved controls, or difficulties encountered in their implementation could cause us to fail to meet our reporting obligations.

In addition, any testing conducted by us in connection with Section 404 of the Sarbanes-Oxley Act, or any subsequent testing conducted by our independent registered public accounting firm, may reveal deficiencies in our internal controls over financial reporting that are deemed to be material weaknesses or that may require prospective or retroactive changes to our financial statements, or identify other areas for further attention or improvement. The failure to maintain controls compliant with Sarbanes-Oxley Act could also cause investors to lose confidence in our reported financial information, which could have a negative effect on the trading price of our shares.

As a biotechnology and pharmaceutical company, we are subject to a large body of legal and regulatory requirements, guidance, and recommendations from a variety of regulatory authorities, such as the FDA, the EMA, and HHS OIG. In addition, as a publicly traded company we are subject to significant regulations. While we have developed and instituted a corporate compliance program based on what we believe are the current best practices and continue to update the program in response to newly implemented regulatory requirements and guidance, we cannot ensure that we are or will be in compliance with all potentially applicable regulations. Failure to comply with all potentially applicable laws and regulations could lead to the imposition of fines, cause the value of our common shares to decline, and impede our ability to raise capital or list our securities on certain securities exchanges.

The market price of shares of our common shares could be subject to wide fluctuations in response to many risk factors listed in this “Item 1A. Risk Factors” section, and others beyond our control such as actions by our shareholders (including if substantial amounts of common shares are sold in the public market or if the market perceives that such sales may occur), collaborators or competitors and general market and economic conditions. In particular, pharmaceutical, biotechnology and other life sciences company stocks have historically experienced significant volatility. As we operate in a single industry, we are especially vulnerable to these factors to the extent that they affect our industry. In the past, securities class action litigation has often been initiated against companies following periods of volatility in their stock price. This risk is especially relevant for biotechnology companies, which have experienced significant stock price volatility in recent years. Securities litigation could result in substantial costs and divert our management’s attention and resources, and could also require us to make substantial payments to satisfy judgments or to settle litigation.

As of the date of this Annual Report, we have outstanding warrants to purchase an aggregate of 2,631,578 common shares at an exercise price of $24.70 per share (which are exercisable, on a cash or cashless basis, at the option of the holder at any time on or prior to May 19, 2025), warrants to purchase an aggregate of 1,781,262 common shares at an exercise price of $28.07 (which are exercisable, on a cash or cashless basis, at the option of the holder at any time on or prior to May 19, 2025) and warrants to purchase an aggregate of 527,295 common shares at an exercise price of $8.30 per share (which are exercisable, on a cash or a cashless basis, at the option of the holder at any time on or prior to August 15, 2032). The warrants also contain customary anti-dilution adjustments and will entitle holders to receive any dividends or other distributions paid on the underlying common shares prior to their expiration on an as-exercised basis. If our outstanding warrants are exercised into common shares, our existing shareholders’ ownership interest will be diluted.

We have not paid any cash dividends since our incorporation. Even if future operations lead to significant levels of distributable profits, we currently intend to reinvest any earnings in our business and do not anticipate declaring or paying any cash dividends until we have an established revenue stream to support continuing dividends. In addition, any proposal for the payment of future dividends will be at the discretion of our board of directors after taking into account various factors including our business prospects, liquidity requirements, financial performance and new product development. Furthermore, payment of future dividends is subject to certain limitations pursuant to our current and future debt instruments, Swiss law and our articles of association. In addition, the Loan Agreement limits our ability to pay dividends. See “—Risks Related to Our Financial Position and Capital Requirements.” Accordingly, investors cannot rely on dividend income from our common shares, and any returns on an investment in our common shares will likely depend entirely upon any future appreciation in the price of our common shares.

The trading market for our common shares depends, in part, on the research and reports that securities or industry analysts publish about us or our business. If one or more of the analysts who cover us downgrade our common shares or publish inaccurate or unfavorable research about our business, the price of our common shares would likely decline. In addition, if our operating results fail to meet the forecast of analysts, the price of our common shares would likely decline. If one or more of these analysts cease coverage of our company or fail to publish reports on us regularly, demand for our common shares could decrease, which might cause the price of our common shares and trading volume to decline.

We are a Swiss corporation. Our corporate affairs are governed by our articles of association and by the laws governing companies incorporated in Switzerland. The rights of our shareholders and the responsibilities of members of our board of directors may be different from the rights and obligations of shareholders and directors of companies governed by the laws of U.S. jurisdictions. In particular, in the performance of its duties, our board of directors is required by Swiss law to consider the interests of our company, our shareholders, our employees and other stakeholders, in all cases with due observation of the principles of reasonableness and fairness. It is possible that some of these parties will have interests that are different from, or in addition to, shareholders’ interests. Swiss law limits the ability of our shareholders to challenge resolutions made or other actions taken by our board of directors in court. Our shareholders generally are not permitted to file a suit to reverse a decision or an action taken by our board of directors, but are instead only permitted to seek damages for breaches of fiduciary duty. As a matter of Swiss law, shareholder claims against a member of our board of directors for breach of fiduciary duty would have to be brought to the competent courts in Epalinges, Canton of Vaud, Switzerland, or where the relevant member of our board of directors is domiciled. In addition, under Swiss law, any claims by our shareholders against us must be brought exclusively to the competent courts in Epalinges, Canton of Vaud, Switzerland. For a further summary of applicable Swiss company law, see Exhibit 4.1 to this Annual Report. Accordingly, our shareholders do not have the same rights as those of a Delaware-incorporated company.

Swiss law reserves for approval by shareholders certain corporate actions over which a board of directors would have authority in some other jurisdictions. For example, the payment of dividends must be approved by shareholders. Swiss law also requires that our shareholders themselves resolve to, or authorize our board of directors to, increase or decrease our share capital. While our shareholders may authorize our board of directors to issue or cancel shares without additional shareholder approval, Swiss law limits this authorization to 50% of the issued share capital at the time of the authorization. The authorization, furthermore, has a limited duration of up to five years and must be renewed by the shareholders from time to time thereafter in order to be available for raising capital. Additionally, subject to specified exceptions, including exceptions described in our articles of association, Swiss law grants pre-emptive subscription rights to existing shareholders to subscribe for new issuances of shares. Swiss law also does not provide as much flexibility in the various rights and regulations that can attach to different categories of shares as do the laws of some other jurisdictions. These Swiss law requirements relating to our capital management may limit our flexibility, and situations may arise where greater flexibility would have provided benefits to our shareholders. See Exhibit 4.1 to this Annual Report.

Because our common shares are listed exclusively on the NYSE and not in Switzerland, our shareholders do not benefit from the protection afforded by certain provisions of Swiss law that are designed to protect shareholders in the event of a public takeover offer or a change-of-control transaction. For example, Article 120 of the Swiss Financial Market Infrastructure Act and its implementing provisions require investors to disclose their interest in our company if they reach, exceed or fall below certain ownership thresholds. Similarly, the Swiss takeover regime imposes a duty on any person or group of persons who acquires more than one-third of a company’s voting rights to make a mandatory offer for all of the company’s outstanding listed equity securities. In addition, the Swiss takeover regime imposes certain restrictions and obligations on bidders in a voluntary public takeover offer that are designed to protect shareholders. However, these protections are applicable only to issuers that list their equity securities in Switzerland and, because our common shares are listed exclusively on the NYSE, are not be applicable to us. Furthermore, since Swiss law restricts our ability to implement rights plans or U.S.-style “poison pills,” our ability to resist an unsolicited takeover attempt or to protect minority shareholders in the event of a change of control transaction may be limited.

Therefore, our shareholders may not be protected in the same degree in a public takeover offer or a change-of-control transaction as are shareholders in a Swiss company listed in Switzerland.

We are organized under the laws of Switzerland and our registered office and domicile is located in Epalinges, Canton of Vaud, Switzerland. Moreover, a number of our directors and executive officers are not residents of the United States, and all or a substantial portion of the assets of such persons are located outside the United States. As a result, it may not be possible for investors to effect service of process within the United States upon us or upon such persons or to enforce against them judgments obtained in U.S. courts, including judgments in actions predicated upon the civil liability provisions of the federal securities laws of the United States. There is doubt as to the enforceability in Switzerland of original actions, or in actions for enforcement of judgments of U.S. courts, of civil liabilities to the extent solely predicated upon the federal and state securities laws of the United States. Original actions against persons in Switzerland based solely upon the U.S. federal or state securities laws are governed, among other things, by the principles set forth in the Swiss Federal Act on Private International Law (the “PILA”). The PILA provides that the application of provisions of non-Swiss law by the courts in Switzerland shall be precluded if the result is incompatible with Swiss public policy. Also, certain mandatory provisions of Swiss law may be applicable regardless of any other law that would otherwise apply.

Switzerland and the United States do not have a treaty providing for reciprocal recognition and enforcement of judgments in civil and commercial matters. The recognition and enforcement of a judgment of the courts of the United States in Switzerland is governed by the principles set forth in the PILA. The PILA provides in principle that a judgment rendered by a non-Swiss court may be enforced in Switzerland only if:

•the non-Swiss court had jurisdiction pursuant to the PILA;

•the judgment of such non-Swiss court has become final and non-appealable;

•the judgment does not contravene Swiss public policy;

•the court procedures and the service of documents leading to the judgment were in accordance with the due process of law; and

•no proceeding involving the same parties and the same subject matter was first brought in Switzerland, or adjudicated in Switzerland, or was earlier adjudicated in a third state, and this decision is recognizable in Switzerland.

Our articles of association contain provisions that may have the effect of discouraging, delaying or preventing a change in control of us that shareholders may consider favorable, including transactions in which our shareholders may receive a premium for their shares. Our articles of association include provisions that:

•in certain cases, allow our board of directors to place up to 44,520,973 common shares, as well as any treasury shares that the Company may hold from time to time, and rights to acquire an additional 17,909,703 common shares with affiliates or third parties, without existing shareholders having statutory pre-emptive rights in relation to this share placement;

•allow our board of directors not to record any acquirer of common shares, or several acquirers acting in concert, in our share register as a shareholder with voting rights with respect to more than 15% of our share capital as set forth in the commercial register;

•limit the size of our board of directors to nine members; and

•require two-thirds of the votes represented at a shareholder meeting for amending or repealing the above-mentioned voting and recording restrictions, for amending the provision setting a maximum board size or providing for indemnification of our directors and members of our executive committee and for removing the chairman or any member of the board of directors before the end of his or her term of office.

These and other provisions, alone or together, could delay or prevent takeovers and changes in control. See Exhibit 4.1 to this Annual Report. These provisions could also limit the price that investors might be willing to pay in the future for our common shares, thereby depressing the market price of our common shares.

We are a “smaller reporting company,” which allows us to take advantage of certain provisions of the Exchange Act, including only being required to provide two years of audited financial statements and reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements. If some investors find our common shares less attractive as a result of our reliance on these reduced disclosure obligations, there may be a less active trading market for our common shares and our price of our common shares may be more volatile.

None.

Cybersecurity risk management is an integral part of our overall enterprise risk management program. Our cybersecurity risk management program is based on industry best practices and provides a framework for handling cybersecurity threats and incidents, including threats and incidents associated with the use of third-party service providers, and facilitates coordination across different departments of our company. This framework includes steps for assessing the severity of a cybersecurity threat, identifying the source of a cybersecurity threat including whether the cybersecurity threat is associated with a third-party service provider, implementing cybersecurity countermeasures and mitigation strategies and informing management and our board of directors of material cybersecurity threats and incidents. Our cybersecurity team also engages third-party security experts for risk assessment and system enhancements. Our cybersecurity team is responsible for assessing our cybersecurity risk management program. In addition, our cybersecurity team provides annual training to all employees.

Our board of directors has overall oversight responsibility for our risk management and has delegated cybersecurity risk management oversight to the audit committee. The audit committee is responsible for ensuring that management has processes in place designed to identify and evaluate cybersecurity risks to which the company is exposed and implement processes and programs to manage cybersecurity risks and mitigate cybersecurity incidents. The audit committee also reports material cybersecurity risks to our full board of directors. Management is responsible for identifying, considering and assessing material cybersecurity risks on an ongoing basis, establishing processes to ensure that such potential cybersecurity risk exposures are monitored, putting in place appropriate mitigation measures and maintaining cybersecurity programs. Our cybersecurity programs are under the direction of our Chief Information Officer (“CIO”), who receives reports from our cybersecurity team and monitors the prevention, detection, mitigation, and remediation of cybersecurity incidents. Our CIO has more than 25 years of leading technology specialist teams and leads a team of experienced information systems security professionals and information security managers. Management, together with the CIO, regularly present updates at standing audit committee meetings on the company’s cybersecurity programs, material cybersecurity risks and mitigation strategies and provide periodic cybersecurity reports that cover, among other topics, the company’s cybersecurity programs, developments in cybersecurity and updates to the company’s cybersecurity programs and mitigation strategies.

In 2023, we did not identify any cybersecurity threats that have materially affected or are reasonably likely to materially affect our business strategy, results of operations, or financial condition. However, despite our efforts, we cannot eliminate all risks from cybersecurity threats, or provide assurances that we have not experienced an undetected cybersecurity incident. See “Item 1A. Risk Factors.”

We do not own any real property. The table below sets forth the sizes and uses of our leased facilities as of the date of this Annual Report:

(1)We do not intend to renew our lease at this location when it expires in June 2024. Thereafter, we intend for our CMC operations to be located in our New Jersey location.

We are not aware of any environmental issues or other constraints that would materially impact the intended use of our facilities.

From time to time, we may be subject to various legal proceedings and claims that arise in the ordinary course of our business activities. The results of litigation and claims cannot be predicted with certainty. As of the date of this Annual Report, we do not believe that we are party to any claim or litigation, the outcome of which would, individually or in the aggregate, be reasonably expected to have a material adverse effect on our business.

As of March 1, 2024, we had 162 shareholders of record of our common shares. The actual number of shareholders is greater than this number of record holders and includes shareholders who are beneficial owners but whose shares are held in street name by brokers and other nominees or in trust or by other entities.

We have never declared or paid cash dividends on our share capital. We intend to retain all available funds and any future earnings, if any, to fund the development and expansion of our business and we do not anticipate paying any cash dividends in the foreseeable future. In addition, the Loan Agreement limits our ability to pay dividends. Any future determination related to dividend policy will be made at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements, contractual restrictions, business prospects and other factors our board of directors may deem relevant.

Under Swiss law, any dividend must be approved by our shareholders. In addition, our auditors must confirm that the dividend proposal of our board of directors to the shareholders conforms to Swiss statutory law and our articles of association. A Swiss corporation may pay dividends only if it has sufficient distributable profits from the previous or current business year (bénéfice résultant du bilan) or brought forward from previous business years (report des bénéfices) or if it has distributable reserves (réserves à libre disposition), each as evidenced by its audited stand-alone statutory balance sheet prepared pursuant to Swiss law and after allocations to reserves required by Swiss law and its articles of association have been deducted. Distributable reserves are generally booked either as free reserves (réserves libres) or as reserves from capital contributions (apports de capital).

Distributions out of share capital, which is the aggregate par value of a corporation’s issued shares, may be made only by way of a share capital reduction. See Exhibit 4.1 to this Annual Report.

The following table is a summary of the common shares authorized for issuance under equity compensation plans as of December 31, 2023:

*The aggregate number of shares that may be issued pursuant to rights granted under the 2022 Employee Stock Purchase Plan is equal to 1% of our common share capital at the plan’s adoption. In addition to the foregoing, on the first day of each calendar year beginning on January 1, 2023 and ending on and including January 1, 2032, the number of common shares available for issuance under the 2022 Employee Stock Purchase Plan is increased by that number of common shares equal to the least of (a) 1% of the common shares outstanding on the final day of the immediately preceding calendar year and (b) such smaller number of common shares as determined by the board of directors. The number of shares reported in this column represents the number of common shares available for future issuance as of December 31, 2023.

The material features of the equity compensation plans adopted without shareholder approval are described below. Any such material plans under which awards in Company shares may currently be granted are included as exhibits to this Annual Report.

Eligible Participants. The administrator is able to offer equity awards at its discretion under the 2019 Equity Incentive Plan to: (1) any employees of us or any of our subsidiaries; (2) any non-employee directors serving on our board of directors; and (3) any consultants or other advisors to us or any of our subsidiaries. The administrator of the plan may determine that an award for the benefit of a non-employee director will be granted to an affiliate of such director, but only to the extent consistent with the registration of shares offered under the plan on Form S-8 under the Securities Act.

Awards. The maximum number of common shares in respect of which awards may be granted under the 2019 Equity Incentive Plan is 17,741,355 common shares (including share-based equity awards granted to date, less awards forfeited), subject to adjustment in the event of certain corporate transactions or events if necessary to prevent dilution or enlargement of the benefits made available under the plan. Equity incentive awards under the 2019 Equity Incentive Plan may be granted in the form of options, share appreciation rights, restricted shares, restricted share units, performance awards or other share-based awards but not “incentive stock options” for purposes of U.S. tax laws. Options and share appreciation rights will have an exercise price determined by the administrator but will not be less than fair market value of the underlying common shares on the date of grant.

Eligible Participants. The administrator is able to offer equity awards at its discretion under the Inducement Plan to any employee who is eligible to receive an employment inducement grant in accordance with NYSE Listed Company Manual 303A.08.

Awards. The maximum number of common shares in respect of which awards may be granted under the Inducement Plan is 1,000,000 common shares (including share-based equity awards granted to date, less awards forfeited), subject to adjustment in the event of certain corporate transactions or events if necessary to prevent dilution or enlargement of the benefits made available under the plan. Equity incentive awards under the Inducement Plan may be granted in the form of options, share appreciation rights, restricted shares, restricted share units, performance awards or other share-based awards but not “incentive stock options” for purposes of U.S. tax laws. Options and share appreciation rights will have an exercise price determined by the administrator but will not be less than fair market value of the underlying common shares on the date of grant.

Termination of Service and Change in Control. In the event of a participant’s termination of employment, the compensation committee may, in its discretion, determine the extent to which an equity incentive award may be exercised, settled, vested, paid or forfeited. In the event of our termination of a participant’s employment without cause or a participant’s resignation for good reason (as defined in the Inducement Plan) upon or within 18 months following a change in control of the company (as defined in the Inducement Plan), any awards outstanding to the participant (unless otherwise provided in the award agreement) will immediately vest and settle, and options and share appreciation rights will become fully exercisable.

In the event of a change in control that involves a merger, acquisition or other corporate transaction, any outstanding award not assumed, substituted, replaced or continued in connection with the transaction will immediately vest and settle, and options and share appreciation rights will become fully exercisable. In connection with a change of control, the compensation committee may, in its discretion, take any one or more of the following actions with respect to outstanding awards: (i) cancel any such award, in exchange for a payment in cash, securities or other property or any combination thereof with a value equal to the value of such award based on the per share value of common shares received or to be received by other shareholders in the event (or without payment of consideration if the committee determines that no amount would have been realized upon the exercise of the award or other realization of the participant’s rights); (ii) require the exercise of any outstanding option; (iii) provide for the assumption, substitution, replacement or continuation of any award by the successor or surviving corporation, along with appropriate adjustments with respect to the number and type of securities (or other consideration) of the successor or surviving corporation, subject to any replacement awards, the terms and conditions of the replacement awards (including performance targets) and the grant, exercise or purchase price per share for the replacement awards; (iv) make any other adjustments in the number and type of securities (or other consideration) subject to (a) such awards and in the terms and conditions of such awards in order to prevent the dilution or enlargement of benefits intended to be made available under the Inducement Plan and (b) awards that may be granted in the future; (v) provide that any such award shall be accelerated and become exercisable, payable and/or fully vested with respect to all shares covered thereby or (vi) provide that any award shall not vest, be exercised or become payable as a result of such event.

There were no sales of unregistered equity securities during the period covered by this report.

There were no purchases of our equity securities by or on behalf of us or any affiliated purchaser during the period covered by this report.

You should read the following discussion and analysis of our financial condition and results of operations together with our audited consolidated financial statements, including the notes thereto, included in this Annual Report. The following discussion includes forward-looking statements that involve risks, uncertainties and assumptions. Our actual results may differ materially from those anticipated in these forward-looking statements. See “Forward-Looking Statements.”

ADC Therapeutics is a leading, commercial-stage global pioneer in the field of antibody drug conjugates (“ADCs”).

Our goal is to be a leading ADC company that transforms the lives of those impacted by cancer. To achieve this, we are focused on unlocking the potential value of our robust ADC portfolio across two pillars of growth: hematology and solid tumors. We are a pioneer in the ADC field with specialized end-to-end capabilities unique to ADCs including a validated technology platform, a growing next-generation research & development toolbox and a proven track record that includes an approved and marketed product. We aim to expand our portfolio and accelerate the development of our pipeline through targeted investments and in collaboration with strategic partners. In this way, we plan to pursue multiple targets in parallel, enabling us to prioritize and ensure disciplined capital allocation strategy while advancing the most promising candidates in both hematology and solid tumors.

In the hematology space, our flagship product, ZYNLONTA, a CD19-directed ADC, received accelerated approval from the U.S. Food and Drug Administration (“FDA”) and conditional approval from the European Commission for the treatment of relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”) after two or more lines of systemic therapy. We are seeking to continue expanding ZYNLONTA into international markets throughout the world, and into earlier lines of DLBCL and other indolent lymphomas, including follicular lymphoma (”FL”) and marginal zone lymphoma MZL as a single and combination agent of choice through our LOTIS-5 confirmatory Phase 3 clinical trial and LOTIS-7 Phase1b clinical trial as well as through investigator-initiated trials (“IITs”) at leading institutions.

In addition, we are investigating a CD-22 targeted compound, ADCT-602, in a Phase 1/2 investigator-initiated study in relapsed or refractory B-cell acute lymphoblastic leukemia.

In the solid tumor space, our clinical-stage pipeline consists of ADCT-601 (mipasetamab uzoptirine) targeting AXL as a single agent and/or in combination in sarcoma, pancreatic, and NSCLC. Our pre-clinical stage pipeline includes a portfolio of next generation investigational ADCs targeting Claudin-6, NaPi2b, PSMA and other undisclosed targets. In addition, we are advancing research with a range of payloads, linkers and conjugation technologies against undisclosed targets.

The following table summarizes our results of operations for the year ended December 31, 2023 and 2022:

We generate product revenue through the sale of ZYNLONTA in the United States. Revenue is recognized when control is transferred to the customer at the net selling price, which includes reductions for gross-to-net (“GTN”) sales adjustments such as government rebates, chargebacks, distributor service fees, other rebates and administrative fees, sales returns and allowances and sales discounts. In the long term, we expect that our product revenue will increase as we execute our business strategy, although our product revenue may fluctuate from period to period based on a number of factors, including patient demand, as well as the timing, dose and duration, of patient therapy and customers’ buying patterns and gross-to-net deductions. We have experienced in 2023 higher GTN sales adjustments than we had previously recognized, including discarded drug and inflationary rebates. We expect to continue experiencing these level of GTN sales adjustments as a percentage of gross sales.

Product revenues, net, decreased to $69.1 million for the year ended December 31, 2023 from $74.9 million for the year ended December 31, 2022, a decrease of $5.8 million, or 7.8%. The decrease is primarily attributable to higher GTN deductions due to the Infrastructure Investment and Jobs Act's requirement for manufacturers of certain single-source drugs separately paid for under Medicare Part B and marketed in single-dose containers to provide annual refunds ("discarded drug rebate") for unused drug, as well as lower volume due to changes in our commercialization model and increased competition, partially offset by a higher price.

We generate license revenue and royalties from our strategic agreements for the development and commercialization of ZYNLONTA and other product candidates outside of the United States. Under these agreements, we receive upfront payments and are eligible for certain milestone payments and royalties. See “Item 1. Business—Material Contracts.” We are unable to predict the timing and amounts of license revenue and royalties as meeting milestones is subject to many factors outside of our control and we have limited control over our partners’ commercialization efforts.

License revenues and royalties decreased to $0.5 million for the year ended December 31, 2023 from $135.0 million for the year ended December 31, 2022. The decrease is primarily attributable to upfront and milestone payments under our exclusive license agreements with Sobi and MTPC that were recognized in 2022.

Cost of product sales primarily includes direct and indirect costs relating to the third-party manufacture and distribution of ZYNLONTA, royalties payable to a collaboration partner based on net product sales of ZYNLONTA and inventory write-downs. We expect that cost of product sales will increase on an absolute basis as product revenue increases and as we sell through pre-approval inventory that was previously expensed prior to commercialization under U.S. GAAP. Factors such as inflation may also increase our cost of product sales as a percentage of product revenue if we are not able to increase the price at which we sell ZYNLONTA to offset such increases in our cost of product sales.

Cost of product sales decreased to $2.5 million for the year ended December 31, 2023 from $3.3 million for the year ended December 31, 2022, a decrease of $0.8 million, or 23.4%. The decrease is primarily attributable to a reduction in costs related to the manufacturing of batches that did not meet our specifications.

The following table summarizes our research and development expenses for our major development programs for the years ended December 31, 2023 and 2022:

Research and development expense consists primarily of employee related expenses, including share-based compensation expense; costs for production of preclinical and clinical-stage product candidates by CMOs; fees and other costs paid to contract research organizations in connection with the performance of preclinical studies and clinical trials; costs of related facilities, materials and equipment; external costs associated with obtaining intellectual property; depreciation; and upfront fees and achieved milestone payments associated with R&D collaboration arrangements.

We expect that research and development expense will decrease on an absolute basis in the near term as we continue our capital allocation optimization, but will continue to comprise the largest component of our overall operating expenses, although our research and development expense may fluctuate from period to period based on a number of factors, including the timing, progress and stage of clinical trials, costs associated with regulatory approval processes and manufacturing costs associated with commercialization activities prior to the receipt of regulatory approval.

Our R&D expenses decreased to $127.1 million for the year ended December 31, 2023 from $186.5 million for the year ended December 31, 2022, a decrease of $59.3 million, or 31.8%.

Research and development expenses for ZYNLONTA decreased to $68.5 million for the year ended December 31, 2023 from $75.9 million for the year ended December 31, 2022, a decrease of $7.4 million. The decrease was due to higher cost sharing with our partners in clinical trial costs primarily resulting from the Sobi license agreement executed in July 2022. We also had lower clinical trial costs for LOTIS 3, LOTIS 6 and LOTIS 7, as well as lower professional fees related to ZYNLONTA for the year ended December 31, 2023 as a result of productivity initiatives and portfolio prioritization.

Research and development expenses for Cami decreased to $10.3 million for the year ended December 31, 2023 from $38.1 million for the year ended December 31, 2022, a decrease of $27.8 million. The decrease was primarily due to completion of the Phase 2 study in 2022 and our decision to pause the program while we evaluated FDA feedback.

Research and development expenses for ADCT-601 increased to $10.8 million for the year ended December 31, 2023 from $8.1 million for the year ended December 31, 2022, an increase of $2.7 million. The increase is primarily attributable to higher patient enrollment and progress towards the completion of the study.

Research and development expenses for ADCT-901 increased to $6.6 million for the year ended December 31, 2023 from $5.5 million for the year ended December 31, 2022, an increase of $1.1 million. This increase was primarily due to increased clinical trial expenses that resulted from increased enrollment and ongoing treatment and monitoring of currently enrolled and completed patients.

Research and development expenses for ADCT-212 decreased to $4.8 million for the year ended December 31, 2023 from $19.2 million for the year ended December 31, 2022, a decrease of $14.4 million. The decrease is primarily attributable to a decrease in expenses related to IND enabling analytical work during the year ended December 31, 2023. We have re-prioritized the R&D pipeline to focus resources on the most advanced, lower risk value-generating programs and have therefore paused investments on this preclinical program.

Share-based compensation decreased to $4.0 million for the year ended December 31, 2023 from $17.4 million for the year ended December 31, 2022, a decrease of $13.5 million. The decrease was driven by decreases in our share price, forfeitures of awards in connection with employee terminations and the workforce reduction announced and put into effect during the second quarter of 2023.

The following table summarizes our selling and marketing expenses for the year ended December 31, 2023 and 2022:

(1)Excludes share-based compensation expense.

Selling and marketing costs (“S&M”) are expensed as incurred and are primarily attributable to commercialization of ZYNLONTA in the United States. S&M includes employee costs and share-based compensation expense for commercial employees and external costs related to commercialization (including professional fees, communication costs and IT costs, travel expenses and depreciation of property and equipment). We expect our S&M expenses to decrease as a percentage of revenue over time as we have transitioned to being a commercial-stage public organization and implemented a new go-to-market model in 2023 to help drive growth and optimize local area influence.

Selling and marketing expenses decreased to $57.5 million for the year ended December 31, 2023 from $69.1 million for the year ended December 31, 2022, a decrease of $11.6 million or 16.8%. The decrease in external costs and overhead was primarily attributable to $2.6 million in lower spend on marketing, analytics and expenses, including those expenses in the European Union relating to the commercial launch of ZYNLONTA. The decrease in employee expenses was primarily due to lower wages and benefits of $3.0 million. The decrease in share-based compensation expense of $6.1 million was primarily due to fluctuations in our share price, forfeitures of awards in connection with employee terminations and the commercial re-alignment announced and put into effect during the second quarter of 2023.

The following table summarizes our general and administrative expenses for the year ended December 31, 2023 and 2022:

(1)Excludes share-based compensation expense.

General and administrative expense includes employee expenses (including share-based compensation expense) for general and administrative employees, external costs (including, in particular, professional fees, legal costs associated with maintaining patents and other intellectual property, communications costs and IT costs, facility expenses and travel expenses), general and administrative costs charged by related parties (including telecommunications costs), depreciation of property and equipment, depreciation of right-of-use assets and amortization of intangible assets.

General and administrative expenses decreased to $48.4 million for the year ended December 31, 2023 from $74.4 million for the year ended December 31, 2022, a decrease of $26.0 million, or 35.0%. The decrease in external costs and overhead was primarily due to lower insurance and IT costs of $4.1 million, as well as lower professional fees of $0.6 million, which primarily includes fees associated with the license agreement entered into with MTPC. The decrease in employee expenses was primarily due to lower wages and benefits of $1.8 million as well as lower temporary help and recruiting of $1.2 million. The decrease in share-based compensation expense was primarily due to fluctuations in our share price, the transition of a board member, forfeitures of awards in connection with terminations and the workforce reductions announced and put into effect during the second quarter of 2023.

Interest income includes interest received from banks on our cash balances. Our policy is to invest funds in a variety of capital preservation instruments, which may include all or a combination of cash and cash equivalents, short-term and long-term interest-bearing instruments, investment-grade securities, and direct or guaranteed obligations of the U.S. government.

Interest income increased to $10.5 million for the year ended December 31, 2023 from $2.6 million for the year ended December 31, 2022, an increase of $8.0 million. The increase was due to higher yields received on our cash deposits during the year ended December 31, 2023.

Interest expense is primarily related to the accretion of our deferred royalty obligation with HCR, the senior secured term loan facility and convertible loans. Interest expense increased to $46.3 million for the year ended December 31, 2023 from $36.7 million for the year ended December 31, 2022, an increase of $9.6 million, or 26.1%. The increase was related to higher interest expense due to the accretion of our deferred royalty obligation with HCR and senior secured term loans, offset by not having interest expense on our convertible loans as a result of the extinguishment on August 15, 2022.

On August 15, 2022, pursuant to an exchange agreement with Deerfield (the “Exchange Agreement”), Deerfield exchanged $115.0 million aggregate principal amount of the Company's senior secured convertible notes for warrants to purchase an aggregate of 4,412,840 common shares, an aggregate of 2,390,297 common shares and cash equal to $117.3 million. As a result of the Exchange Agreement, the Company recognized a loss on debt extinguishment of $42.1 million for the year ended December 31, 2022, which primarily consists of the difference between the fair value of the consideration transferred and the carrying value of the convertible loans, exit fee, as well as the unpaid interest payments through the maturity date. Any transaction costs related to the exchange are included as part of the calculation of the loss on debt extinguishment.

Other, net consists primarily of changes in the fair value (gains or losses) of the convertible loan, other derivatives and warrant obligation; and cumulative catch-up adjustments related to our deferred royalty obligation.

Other, net as of December 31, 2023 and 2022 included the following:

The change in fair value of the convertible loans derivatives was recognized as income of $25.7 million for the year ended December 31, 2022. The decreases in fair values of the embedded derivatives were primarily due to decreases in the fair value of the underlying shares during the period. The loan was exchanged on August 15, 2022. As a result, no income or expense was recognized during the year ended December 31, 2023.

Pursuant to an Exchange Agreement with Deerfield entered into on August 15, 2022, the Company issued warrants to Deerfield to purchase an aggregate of 4,412,840 common shares. The Deerfield warrant obligation has been recorded at its initial fair value at the time the agreement was entered into on August 15, 2022 and is remeasured to fair value at the end of each reporting period. The income of $0.5 million and $11.5 million as a result of changes in the warrant obligation for the year ended December 31, 2023 and 2022, respectively, was primarily due to the decrease in fair value of the underlying shares during the respective period.

We periodically assess the expected payments to HCR based on our underlying revenue projections and to the extent the amount or timing of such payments is materially different than our initial estimates we will record a cumulative catch-up adjustment to the deferred royalty obligation. The adjustment to the carrying amount is recognized in Other, net as an adjustment in the period in which the change in estimate occurred.

The cumulative catch-up adjustment decreased to $5.0 million for the year ended December 31, 2023 from $15.4 million for the year ended December 31, 2022, a decrease of $10.4 million, or 67.7%. The decrease was primarily due to revised revenue forecasts used in the valuation model.

We recorded an income tax expense of $39.1 million for the year ended December 31, 2023 as compared to $0.2 million for the year ended December 31, 2022, primarily driven by our U.S. operations.

Income tax expense associated with our U.S. operations was $38.6 million for the year ended December 31, 2023 driven by the recognition of a $47.8 million valuation allowance on our deferred tax assets due to a change in our intercompany operating and transfer pricing model. Generally, current income tax is primarily due to our internal arrangements to reimburse our foreign subsidiaries in the U.S. and the United Kingdom for the services they render to our parent company in Switzerland. Commercial sales in the U.S. also contributed to the current period income tax expense. Ultimately, the net profit at each subsidiary is subject to local income tax. During the year ended December 31, 2023, with respect to our U.S. operations, a deferred tax expense of $37.1 million and current income tax expense of $1.5 million was recorded.

Comparatively, our income tax expense of $0.2 million recorded during the year ended December 31, 2022 was driven by $1.8 million of current income tax expense recorded in connection with US and UK operations, partially offset by $1.6 million of deferred income tax benefit related to various book to tax adjustments.

We are subject to corporate taxation in Switzerland. We are also subject to taxation in other jurisdictions in which we operate, in particular, the United States and the United Kingdom, where our two wholly-owned subsidiaries are incorporated. We are entitled under Swiss laws to carry forward any losses incurred for a period of seven years, which could be used to offset future taxable income. We are also entitled under U.S. tax law to carry forward R&D tax credits for a period of up to 20 years, which could be used to offset future taxable income.

In estimating future taxable income to assess the realizability of deferred tax assets, management develops assumptions including the amount of future net revenue and pre-tax operating income (loss) and the implementation of feasible and prudent tax planning strategies. These assumptions require significant judgment about the forecasts of future taxable income and are consistent with the plans and estimates we are using to manage the underlying business. Management notes that its projections of future taxable profits and losses rely on currently enacted law and are subject to revision if the U.S. legislates new tax law. As such, changes in tax laws and rates could also affect recorded deferred tax assets and liabilities in the future. We record the effect of a tax rate or law change on our deferred tax assets and liabilities in the period of enactment. Future tax rate or law changes could have a material effect on our financial condition, results of operations or cash flows.

We recorded our proportionate share of Overland ADCT BioPharma’s net loss of $5.5 million and $10.1 million for the years ended December 31, 2023 and 2022, respectively. The decrease in Overland ADCT BioPharma's net loss for the year ended December 31, 2023 as compared to the year ended December 31, 2022 was primarily attributable to lower R&D costs as the BLA submitted by Overland ADCT BioPharma has been accepted and granted priority review by the NMPA, as well as lower share-based compensation expense as a result of a workforce reduction for the year ended December 31, 2023. We also recorded a $0.6 million true-up during the year ended December 31, 2023 to align our proportionate share of Overland ADCT BioPharma's share-based compensation expense, which was lower than our estimate for the year ended December 31, 2022.

As of December 31, 2023, we had cash and cash equivalents of $278.6 million. We believe that our current capital resources are sufficient to fund our operation and meet capital requirements for more than twelve months after the date of filing this Annual Report on Form 10-K.

We plan to continue to fund our operating needs through our existing cash and cash equivalents, revenues from sales of ZYNLONTA, and potential milestone and royalty payments under our licensing agreements and additional equity financings, debt financings and/or other forms of financing, as well as funds provided by collaborations. We are also continuously exploring strategic collaborations, business combinations, licensing opportunities or similar strategies for clinical development and commercialization of ZYNLONTA and/or our product candidates.

To date, we have financed our operations primarily through equity financings, convertible debt and senior secured term loan financings, and additional funds provided by collaborations and royalty financings and sales of ZYNLONTA in the United States. For a description of the Loan Agreement, HCR Agreement and other license and collaboration agreements, see “Item 1. Business - Material Contracts.”

Our primary uses of capital are, and we expect will continue to be, research and development expenses, selling and marketing expenses, compensation and related expenses, interest and principal payments on debt obligations and other operating expenses. We expect to incur substantial expenses as we continue to devote substantial resources to research and development and marketing and commercialization efforts, in particular to grow ZYNLONTA in the 3L+ DLBCL setting, continue to study and advance ZYNLONTA in earlier lines of therapy and in combinations to potentially expand our market opportunity and further develop our pipeline and our ADC platform. Cash used to fund operating expenses is impacted by the timing of when we pay expenses, as reflected in the change in our outstanding accounts payable and accrued expenses, as well as the timing of collecting receivables from the sale of ZYNLONTA and paying royalties related to our deferred royalty obligation.

Our contractual obligations relate to our outstanding indebtedness under the Loan Agreement, as described above, and our lease agreements. For information relating to our scheduled maturities with respect to our lease liabilities and long-term debt see Note 6 Leases and Note 10 Senior secured term loan facility and warrants, respectively, included in the Notes to our audited consolidated financial statements.

We have future royalty obligations to HCR, under our royalty purchase agreement, which royalty payment amounts and timing is dependent on the future sales results of ZYNLONTA. See note 13 Deferred Royalty Obligation, included in the Notes to our audited consolidated financial statements for further information.

For information relating to our non-cancelable obligations under third party manufacturing agreements see Note 15 Commitments and Contingencies, included in the Notes to our audited consolidated financial statements.

The Company has entered into various collaborations with development partners, including in-licensing and manufacturing agreements. These agreements provide for the Company to make potential future milestone and royalty payments that are conditional on success, and that are spread over various stages of development and commercialization, including achieving preclinical proof of concept, filing an investigational new drug (“IND”) application, commencing or completing multiple clinical development stages, obtaining regulatory approval in multiple countries, and achieving various levels of commercial sales. Due to the nature of these arrangements, the future potential payments related to the attainment of the specified milestones are inherently uncertain, and accordingly, no amounts have been recorded for these future potential payments in the Company’s consolidated balance sheet as of December 31, 2023 and 2022. The aggregate amount of such potential milestone payments (excluding royalty payments), under all such collaboration agreements, was $372.5 million, including approximately $106.8 million contingent on the achievement of various research, development and regulatory approval milestones and approximately $265.7 million in sales-based milestones. A milestone associated with a collaboration agreement was achieved during December 2020, which the Company recorded as an R&D expense of $5.0 million within the consolidated statement of operation for the year ended December 31, 2020. The milestone continues to be recorded as an accrued expense on the consolidated balance sheet as of December 31, 2023 and December 31, 2022.

The following table summarizes our cash flows for the years ended December 31, 2023 and 2022:

Net cash used in operating activities decreased to $118.7 million for the year ended December 31, 2023 from $138.3 million for the year ended December 31, 2022, a decrease of $19.6 million. The decrease was primarily due to the receipt of $50.0 million in Sobi license revenue recognized in December 2022 upon approval of the Marketing Authorisation Application by the European Commission for ZYNLONTA in third-line DLBCL which was received during the year ended December 31, 2023, as well as tax refunds received during the year ended December 31, 2023.

Net cash used in investing activities increased to $3.2 million for the year ended December 31, 2023 from $0.7 million for the year ended December 31, 2022, an increase of $2.5 million. The increase in net cash used in investing activities primarily relates to purchases of property and equipment.

Net cash provided by financing activities was $73.9 million for the year ended December 31, 2023 and primarily related to the proceeds received under the deferred royalty obligation with HCR upon the first commercial sale of ZYNLONTA in the United Kingdom or any European Union country.

Net cash used in financing activities was $0.9 million for the year ended December 31, 2022. For the year ended December 31, 2022, we drew down $120.0 million principal amount of term loans under the Loan Agreement prior to transaction costs paid of $7.2 million during the year ended December 31, 2022. In addition, we received $6.1 million of proceeds, net of transaction costs paid during the year ended December 31, 2022, from the issuance of shares under the share purchase agreement. Additionally, we exchanged our senior secured convertible notes pursuant to the exchange agreement with Deerfield, resulting in $118.3 million (including exit fees and transaction costs) being used.

During the periods presented, we did not have, and we do not currently have, any off-balance sheet arrangements.

A summary of the significant accounting policies is provided in Note 2 Summary of Significant Accounting Policies, included in the Notes to our audited consolidated financial statements.

The preparation of financial statements in accordance with generally accepted accounting principles, or GAAP, requires us to make estimates, assumptions and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities.

We evaluate our estimates on an ongoing basis. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable under the circumstances, the results of which form our basis for making judgments about the carrying values of assets and liabilities and the reported amounts of revenues and expenses that are not readily apparent from other sources. Actual results may differ from those estimates under different assumptions and conditions.

Management considers an accounting estimate to be critical if:

•it requires a significant level of estimation uncertainty; and

•changes in the estimate are reasonably likely to have a material effect on our financial condition or results of operations.

We believe the following critical accounting policies and estimates describe the more significant judgments and estimates used in the preparation of our consolidated financial statements.

Product revenues, net

We generate revenue from sales of ZYNLONTA in the U.S. for the treatment of relapsed or refractory DLBCL, which was approved by the FDA on April 23, 2021 and launched shortly thereafter. We also generate product revenue from sales of products outside the US under license and supply arrangements with partners.

GTN sales adjustments involve significant estimates and judgment after considering factors including legal interpretations of applicable laws and regulations, historical experience and drug product analogs in the absence of Company experience, payer channel mix, current contract prices under applicable programs, unbilled claims and processing time lags and inventory levels in the distribution channel. We also use information from external sources to identify prescription trends, patient demand, average selling prices, discarded volumes and sales return and allowance data for the Company and analog drug products. Our estimates are subject to inherent limitations of estimates that rely on third-party information, as certain third-party information was itself in the form of estimates and reflect other limitations including lags between the date as of which third-party information is generated and the date on which we receive third-party information. Estimates will be assessed each period and adjusted as required to revise information or actual experience. In particular, the following rebate requires a substantial degree of judgement.

We began estimating and recording a provision for the discarded drug rebate as a GTN sales adjustment beginning in the first quarter of 2023, which is included in Other long-term liabilities due to the long-term nature of when the first annual refunds are expected to come due. The significant assumptions used to estimate the discarded drug rebate include legal interpretations of applicable laws and regulations, historical experience with discarded volumes and time lags in the processing of claims and invoicing from CMS. We use a number of factors to estimate the discarded drug rebate, including information from external sources to identify the Company’s discarded volumes, preliminary information from CMS on estimated discarded volumes, as well as legal interpretations of the payment limit amount and J-code billing unit used in the discarded drug rebate calculation. We will continue to rely on projection methodologies and expect annual reports for 2023 and 2024 to be received from CMS by the end of 2024 and 2025, respectively, with an expectation of first invoice payments being made in 2025. Given the annual nature of the proposed reporting schedule we will continue to estimate periodically discarded drug rebate liabilities.

Deferred royalty obligation

On August 25, 2021, we entered into a royalty purchase agreement with certain entities managed by Healthcare Royalty Partners (“HCR”). We accounted for the initial cash received as debt, less transaction costs and will subsequently account for the value of the debt at amortized cost. The amount received by us will be accreted to the total estimated royalty payments over the life of the agreement which will be recorded as interest expense. The carrying value of the debt will decrease for royalty payments made to HCR based on actual net sales and licensing revenue.

To determine the accretion of the liability related to the deferred royalty obligation, we are required to estimate the total amount of future royalty payments and estimated timing of such payment to HCR based on our revenue projections. The Company uses a third party valuation firm to assist in determining the total amount of future royalty payments and estimated timing of such payment to HCR using an option pricing Monte Carlo simulation model.

The significant assumptions used to estimate the HCR deferred royalty obligation accretion of the liability include the revenue projections and timing of payments. At each reporting period, we assess the expected payments to HCR based on its underlying revenue projections and to the extent the amount or timing of such payments is materially different than its initial estimates we will record a cumulative catch-up adjustment to the deferred royalty obligation. The adjustment to the carrying amount is recognized in earnings as an adjustment to Other, net in the period in which the change in estimate occurred.

The exact amount and timing of repayment is likely to be different each reporting period as compared to those estimated based on our revenue projections. A significant increase or decrease in actual net sales of ZYNLONTA compared to the Company’s revenue projections, and regulatory approval and commercialization of Cami, as well as ZYNLONTA in other indications as well as licensing revenue could change the royalty rate and royalty cap due to HCR, which could materially impact the debt obligation as well as interest expense associated with the royalty purchase agreement. Also, our total obligation to HCR can vary depending on the achievement of the sales milestones as well as the timing of a change in control event.

Refer to Note 2 to our audited consolidated financial statements for recently adopted accounting pronouncements and recently issued accounting pronouncements not yet adopted as of the date of this Annual Report.

We are not required to provide the information required by this Item 7A as we are a smaller reporting company.

To the Board of Directors and Shareholders of ADC Therapeutics SA

We have audited the accompanying consolidated balance sheets of ADC Therapeutics SA and its subsidiaries (the “Company”) as of December 31, 2023 and 2022, and the related consolidated statements of operation, comprehensive loss, changes in shareholders’ equity (deficit) and cash flows for the years then ended, including the related notes (collectively referred to as the “consolidated financial statements”). We also have audited the Company's internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2023 and 2022, and the results of its operations and its cash flows for the years then ended in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO.

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Annual Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

The critical audit matters communicated below are matters arising from the current period audit of the consolidated financial statements that were communicated or required to be communicated to the audit committee and that (i) relate to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

As described in Note 13 to the consolidated financial statements, on August 25, 2021, the Company entered into a royalty purchase agreement with certain entities managed by HealthCare Royalty Management, LLC (HCR) for up to $325.0 million. Under the terms of the agreement, the Company received gross proceeds of $225.0 million upon closing and received an additional $75.0 million during the year ended December 31, 2023. The Company’s aggregate royalty obligations are capped at 2.50 times the amount paid by HCR under the agreement or at 2.25 times the amount paid by HCR under the agreement if HCR receives royalty payments exceeding a mid-nine-digit amount on or prior to March 31, 2029 (the “Royalty Cap”). Once the Royalty Cap is reached, the royalty purchase agreement will terminate. The Company evaluated the terms of the royalty purchase agreement and concluded that the features of the investment amount are similar to those of a debt instrument. Accordingly, the Company recorded a liability relating to the initial gross proceeds received as debt less transaction costs in August 2021, and increased the liability in June 2023 for the eligible amount received as debt less transaction costs upon first commercial sale of ZYNLONTA in Europe. The Company accounts for the value of the debt at amortized cost. The amounts received by the Company will be accreted to the total estimated amount of the royalty payments necessary to extinguish the Company’s obligation under the agreement, which will be recognized as interest expense. The carrying value of the debt decreases for royalty payments made to HCR based on actual net sales and licensing revenue. To determine the accretion of the liability related to the deferred royalty obligation, the Company is required to estimate the total amount of future royalty payments and estimate the timing of such payments to HCR based on the Company's revenue projections. The Company uses a third party valuation firm to assist in determining the total amount of future royalty payments and estimates timing of such payment to HCR using an option pricing Monte Carlo simulation model. At each reporting period, the Company assesses the expected payments to HCR based on its underlying revenue projections and to the extent the amount or timing of such payments is materially different than its initial estimates, the Company will record a cumulative catch-up adjustment to the deferred royalty obligation. The Company’s deferred royalty obligation recognized within liabilities was $309.6 million as of December 31, 2023. The significant assumptions used to estimate the HCR deferred royalty obligation accretion of the liability include the revenue projections and timing of payments.

The principal considerations for our determination that performing procedures relating to the deferred royalty obligation with HealthCare Royalty Partners is a critical audit matter are the significant judgment by management when determining the value of the deferred royalty obligation. This in turn led to a high degree of auditor judgment, subjectivity, and effort in performing procedures and evaluating the audit evidence obtained related to management’s assumptions related to the revenue projections used to determine the timing of expected cash outflows through the Monte Carlo simulation model. In addition, the audit effort involved the use of professionals with specialized skills and knowledge.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to management’s determination of the accretion of the liability. These procedures also included, among others, (i) testing management’s process for developing the deferred royalty obligation; (ii) evaluating the appropriateness of the Monte Carlo simulation model; (iii) testing the completeness and accuracy of underlying data used in the model; and (iv) evaluating the reasonableness of the significant assumptions used by management related to future revenue projections and the timing of payments considering external market and industry data.

Professionals with specialized skill and knowledge were used to assist in evaluating (i) the appropriateness of the Monte Carlo simulation model and (ii) reasonableness of the revenue projections.

As described in Notes 2 and 17 to the consolidated financial statements, product revenue is recognized at the net selling price, which includes reductions for gross-to-net (“GTN”) sales adjustments such as government rebates, chargebacks, distributor service fees, other rebates and administrative fees, sales returns and allowances and sales discounts. Government rebates include the discarded drug rebate. The Infrastructure Investment and Jobs Act requires manufacturers of certain single-source drugs separately paid for under Medicare Part B and marketed in single-dose containers to refund the dispensed drug unused and discarded exceeding an applicable percentage defined by statute or regulation. The accrual for such rebate recognized within other long-term liabilities was $7.4 million as of December 31, 2023. The significant assumptions used to estimate the discarded drug rebate include historical experience with discarded volumes considering time lags in the processing of claims and invoicing from the Centers for Medicare & Medicaid services as well as legal interpretations of the payment limit amount used in the rebate calculation.

The principal considerations for our determination that performing procedures relating to the Product revenue – Gross-to-net (GTN) sales adjustments – Discarded Drug Rebate is a critical audit matter are the significant judgment made by management when determining the discarded drug rebate. This in turn led to a high degree of auditor judgment, subjectivity, and effort in performing procedures and evaluating the audit evidence obtained related to the valuation of the discarded drug rebate and management’s assumptions related to historical experience with discarded volumes as well as legal interpretations of the payment limit amount used in the rebate calculation.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to management’s estimate of the discarded drug rebate. These procedures also included, among others, (i) testing management’s process for developing the discarded drug rebate estimates; (ii) testing the accuracy of the rebate calculation; (iii) testing the completeness and accuracy of inputs underlying data used in the calculation of the rebate; and (iv) evaluating the reasonableness of significant assumptions used by management related to the discarded volumes considering historical experience as well as legal interpretations of the payment limit amount used in the rebate calculation, and whether assumptions were consistent with evidence obtained in other areas of the audit.

Lausanne, Switzerland
March 13, 2024

We have served as the Company's auditor since 2015.