​

(Unaudited)

​

​

(in thousands, except share data)

​

September 30, 2022

​

December 31, 2021

Assets

​

​

Current assets:

​

​

Cash and cash equivalents

​

$

62,568

​

$

128,965

Marketable securities

​

​

151,190

​

​

186,808

Prepaid expenses and other current assets

​

1,509

​

1,726

Prepaid research and development

​

7,257

​

7,567

Total current assets

​

222,524

​

325,066

Property and equipment, net

​

22,918

​

23,806

Right of use assets - operating leases

​

​

19,890

​

​

-

Other assets

​

4,720

​

6,204

Total assets

​

$

270,052

​

$

355,076

Liabilities and stockholders’ equity

​

​

​

Current liabilities:

​

​

​

Accounts payable

​

$

4,506

​

$

9,448

Accrued expenses and other current liabilities

​

13,861

​

20,050

Operating lease liabilities

​

​

3,252

​

​

-

Total current liabilities

​

21,619

​

29,498

Operating lease liabilities - noncurrent

​

24,037

​

-

Deferred rent

​

-

​

6,921

Total liabilities

​

45,656

​

36,419

​

​

​

​

​

​

​

Commitments and Contingencies

​

​

​

​

​

​

​

​

​

​

Stockholders’ equity:

​

​

​

Common stock, $0.0001 par value: 300,000,000 shares authorized; 54,546,596 shares issued and outstanding at September 30, 2022 and 54,244,996 shares issued and outstanding at December 31, 2021

​

5

​

5

Additional paid-in capital

​

691,194

​

675,346

Accumulated other comprehensive income (loss)

​

​

(1,468)

​

​

(413)

Accumulated deficit

​

(465,335)

​

(356,281)

Total stockholders’ equity

​

224,396

​

318,657

Total liabilities and stockholders’ equity

​

$

270,052

​

$

355,076

​

​

Three Months Ended September 30, 

​

Nine Months Ended September 30, 

(in thousands, except share and per share data)

2022

2021

​

2022

2021

Operating expenses:

​

​

​

​

​

Research and development

​

$

15,362

​

$

26,623

​

$

68,396

​

$

84,705

Acquired in-process research and development

​

1,500

​

5,500

​

3,000

​

7,000

General and administrative

​

10,664

​

14,978

​

38,754

​

42,864

Loss from operations

​

(27,526)

​

(47,101)

​

(110,150)

​

(134,569)

Interest income, net

​

825

​

186

​

1,096

​

337

Net loss

​

$

(26,701)

​

$

(46,915)

​

$

(109,054)

​

$

(134,232)

Per share information:

​

​

​

​

​

Net loss per share of common stock, basic and diluted

​

$

(0.49)

​

$

(0.87)

​

$

(2.01)

​

$

(2.53)

Weighted average common shares outstanding, basic and diluted

​

54,473,945

​

53,995,560

​

54,379,397

​

53,080,645

Comprehensive loss:

​

​

​

​

​

​

​

​

​

​

​

​

Net loss

​

$

(26,701)

​

$

(46,915)

​

$

(109,054)

​

$

(134,232)

Unrealized gain (loss) on marketable securities

​

​

110

​

​

14

​

​

(1,055)

​

​

45

Comprehensive loss

​

$

(26,591)

​

$

(46,901)

​

$

(110,109)

​

$

(134,187)

Fulfilling the Promise of Genetic Medicines for Central Nervous System DisordersCorporate PresentationNovember 2022NASDAQ GS: PASG

2 Forward-Looking StatementThis presentation includes “forward-looking statements” within the meaning of, and made pursuant to the safe harbor provisions of, the Private Securities Litigation Reform Act of 1995, including, but not limited to: our expectation about timing and execution of anticipated milestones, including our planned progressof clinical trials and the availability of clinical data from such trials; our expectations about our collaborators’ and partners’ ability to execute key initiatives; our expectations about our manufacturing plans and strategies; estimates regarding our cash forecasts; the expected impact of the COVID-19 pandemic on our operations; and the ability of our lead product candidates to treat their respective target CNS disorders. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” “believe,” “could,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,”“might,” “plan,” “potential,” “possible,” “will,” “would,” and other words and terms of similar meaning. These statements involve risks and uncertainties thatcould cause actual results to differ materially from those reflected in such statements, including: our ability to develop, obtain regulatory approval for and commercialize PBGM01, PBFT02, PBKR03, PBML04, and future product candidates; the timing and results of preclinical studies and clinical trials; the risk that positiveresults in a preclinical study or clinical trial may not be replicated in subsequent trials or success in early stage clinical trials may not be predictive of results in later stage clinical trials; risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise fromadditional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates; the occurrence of adverse safety events; failure to protect and enforce our intellectual property, and other proprietary rights; failure to successfully execute or realize the anticipated benefits of our strategic and growth initiatives; risks relating to technology failures orbreaches; our dependence on collaborators and other third parties for the development of product candidates and other aspects of our business, which are outside of ourfull control; risks associated with current and potential delays, work stoppages, or supply chain disruptions caused by the coronavirus pandemic; risks associated with current and potential future healthcare reforms; risks relating to attracting and retaining key personnel; failure to comply with legal and regulatory requirements; risks relating to access to capital and credit markets; and the other risks and uncertainties that are described in the Risk Factors section of our most recent filings with the U.S. Securities and Exchange Commission. These statements are based on our current beliefs and expectations and speak only as of the date of thispresentation. We do not undertake any obligation to publicly update any forward-looking statements except as required by law. By attending or receiving this presentation you acknowledge that you are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date such statements are made; you will be solely responsible for your own assessment of the market and our market position; and that you will conduct your own analysisand be solely responsible for forming your own view of the potential future performance of Passage Bio.

3 The Passage Bio AdvantageOur VisionTo fulfill the promise of genetic medicines by developing groundbreaking therapies that transform the lives of patients with CNS diseasesA corporate model designed for success PENN GTP PARTNERSHIPDEDICATED MANUFACTURING & ANALYTICSBROAD AND ROBUST PIPELINE

4 Penn GTP Partnership Leaders in AAV gene therapy World-class Gene Therapy ProgramFounded by renowned innovatorJames M. Wilson, M.D., Ph.D.Chief Scientific Advisor, Passage Bio Cutting-edge research and bioengineering Rigorous preclinical characterization to support product candidate selection Next-generation vector technologies and novel capsids Decades of proven gene therapy expertise 350+ full-time employees Strong connections with orphan disease community4

5 A Broad and Robust Pipeline with Global RightsTransformative therapies for CNS disorders across rare and large patient populations Program* Indication GeneDiscoveryPre-clinicalPhase 1/2Pivotal PBGM01 † GM1 gangliosidosis GLB1 PBFT02 Frontotemporal dementia GRN PBAL05 Amyotrophic lateral sclerosis C9orf72 Unnamed Huntington’s disease HTT & Undisclosed Unnamed Temporal lobe epilepsy Undisclosed PBKR03 Krabbe disease GALC PBML04 Metachromatic leukodystrophy ARSA *8 additional CNS pipeline license options remain; 3 license options were previously exercised, and rights were subsequently returned to the University of Pennsylvania.† Program includes ongoing natural history study of infantile and juvenile GM1 gangliosidosis patients Exploring strategic alternatives

6 UPenn GTPResearch Analytics and Vector Engineering Passage Bio CMC R&D Lab Analyticaland Process Development and Clinical Product TestingScale-up Capability to Support Development Plans Catalent Suite and Global Supply ChainDedicated cGMP Manufacturing Capacity and End-to-End Clinical Supply Chain Passage Bio Manufacturing and CMC CapabilitiesEnsuring product supply from clinical development through commercialization Dedicated Capacity and End-to-End Supply ChainKey Strategic PartnershipsInternal State-of-the-Art CMC CapabilitiesFOUNDATION >>>>PARTNERSHIP>>>>>>INVESTMENT >>>>>>>>>

PBGM01GM1 Gangliosidosis

8 GM1 Gangliosidosis: A Devastating Pediatric Disease FATAL, PEDIATRIC NEUROLOGICAL LYSOSOMAL STORAGE DISORDER caused by GLB1gene mutations characterized by destruction of neurons in the brain and spinal cord.Characterized by rapidly progressive neurological decline resulting in reduced muscle tone, progressive CNS dysfunction, deafness, blindness, rigidity and skeletal dysplasia. RARE AND UNDERSERVEDpopulations with incidence of up to ~1 per 100,000 live births worldwide.No disease-modifying therapies are presently approved.Source: NIH, CHOP, American Journal of Neuroradiology

9 PBGM01OUR APPROACHNext-generation, proprietary capsid delivers functional GLB1gene encoding β-gal to the brain and peripheral tissuesPRECLINICAL EVIDENCECompelling preclinical data in knock-out mouse model•Dose-related histological correction, improvements in neurological function, and survival•Meaningful transduction of both CNS and critical peripheral organsCLINICAL DEVELOPMENT•Ongoing global Phase 1/2 Imagine-1 trial focused on early and late infantile GM1•Well-tolerated, positive safety profile, demonstration of functional transgene expression, and meaningful gains in developmental milestones*Potential transformative therapy for rare, underserved disorder * Based on Cohort 1 interim results

10 Imagine-1: Global Phase 1/2 Trial with PBGM01Initial safety and biomarker data from Cohorts 2 & 3 expected in December 2022 Trial DesignPhase 1/2, multi-center, open-label, dose escalation and confirmatory study Route of AdministrationIntra-cisterna magna (ICM)VectorAAVhu68DurationTwo years, with rollover into a separate long-term follow-up studyPrimary Endpoints•Safety and tolerability•Efficacy (confirmatory cohort)Regulatory Clearances and Designations•Received multiple global regulatory clearances•Received Orphan Drug, Rare Pediatric Disease and Fast Track designations by FDA and Orphan and Advanced Therapy Medicinal Product designations by EC COHORT 4Early Infantilen = 2DOSE 2 (1.1e11 GC/g)*DOSE 1 (3.3e10 GC/g)* Expansion CohortEarly Infantilen = 6 Expansion CohortLate Infantilen = 6 COHORT 2Late Infantilen = 2 COHORT 3Early Infantilen = 2 COHORT 1Late Infantilen = 2 60 days between subject enrollment IDMC review Recruiting Dosing complete* Genome copies per gram of estimated brain weight

11 Key Takeaways from Interim Cohort 1 Data*Well tolerated, demonstration of functional transgene expression, and meaningful developmental improvement BIOMARKERSPost treatment CSF and serum β-gal activity for both patients above natural history study (NHS) patient values SAFETYPBGM01 was well tolerated and had a positive safety profile•No serious adverse events (SAEs)•No complications related to ICM injection•No evidence of DRG toxicity CLINICAL STATUSMeaningful improvement across developmental areas on both the Vineland and Bayley scales including regaining of lost milestones* Interim data aspresented at ASGCT 25thAnnual Meeting on May 18, 2022.

12 Interim Clinical Results: Patient 1Patient 1 demonstrated meaningful gains in developmental milestones, advancing from baseline to 12-months•Gross motor: progressed from taking a few steps without support toobserved jumping, balancing on 1 foot, and climbing stairs•Expressive language: progressed from usingno words with meaning tousing names to address siblings and creating simple sentencesSustained improvement documented in all developmental areas *The Vineland-II is caretaker-assessed. **Patient 1 was subsequently found to have unrelated visual impairment that could have impacted the Bayley-III. (Patient 1 recently began wearing glasses.) The Bayley-III is based on direct observation by a neurodevelopmental specialist. 81318 232833 381315171921232527 Developmental Age (months) Chronological Age (months)Vineland-II* (12 months) Normal Fine motor Gross motor Receptive language Expressive language Personal living skills Interpersonal relationships Play and leisure time Overall 1012 14 161820 22 24 261315171921232527 Developmental Age (months) Chronological Age (months)Bayley-III**(12 months) Normal Gross motor Fine motor Receptive language Expressive language Cognition Overall

13 Interim Clinical Results: Patient 2At month 4, Patient 2 was clinically observed to have regained previously lost developmental milestones•Gross motor: progressed from standing with support for 5 seconds to standing with support for 1-3 minutes and walking without support•Expressive language: progressed from using no words with meaning to using single words and waving goodbyeContinued improvement despite having severe developmental delay at baseline and prior history of regression 7911 13 151719 212331333537 Developmental Age (months) Chronological Age (months)Vineland-II* (6 months) Normal Fine motor Gross motor Receptive language Expressive language Personal living skills Interpersonal relationships Play and leisure time Overall 357911131531333537 Developmental Age (months) Chronological Age (months)Bayley-III**(6 months) Normal* Gross motor Fine motor Receptive language Expressive language Cognition Overall*The Vineland-II is caretaker-assessed.**The Bayley-III is based on direct observation by a neurodevelopmental specialist.

14 •CSF β-gal activity increased above levels seen in NHS following dosing and sustained at upper limit of NHS•Serum β-gal activity increased in both patients; however, over time, post-treatment β-gal activity for Patient 1 was above NHS patient values, while Patient 2 normalized to NHS patient values•CSF GM1 gangliosides increased in Patient 1 but subsequently stabilized; data for Patient 2 fluctuated•Whole blood GM1 gangliosides in Patients 1 and 2 increased slightly through ~50 days post-treatment, then trended downward slightly over timeCohort 1 Interim Biomarker Data * Apparent estimated concentration1. Baseline reflects the average of two samples collected within 48-hours of dosing. †Based on preliminary data from University of Pennsylvania’s ODC NHS study (NCT04041102).β-Gal=β-galactosidase; CSF=cerebrospinal fluid; NHS=natural history study,WB=whole bloodPatient 2 Patient 1 0501001502000100200300400nM*Time (Days)CSF GM1 Gangliosides 01 2340100200300400β - Gal Activity, CSF (nmol/mL/3hr) Time (Days)CSF β-gal NHS patient value range0.30-1.81 nmol/mL/3hr† 051015200100200300400β - Gal Activity, Serum (nmol/mL/3hr) Time (Days)Serum β-gal1 NHS patient value range2.25-10 nmol/mL/3hr† 0200400600 8001,0000100200300400nM*Time (Days)WB GM1 Gangliosides

PBFT02Frontotemporal Dementia —GRN

16 FTD-GRN: A Devastating Adult DiseaseDEVASTATING FORM OF DEMENTIA caused by a GRNgene mutation resulting in progranulin (PGRN) deficiency. Approximately 5–10% of FTD is caused by a GRNmutation.Disease progression is rapid and degenerative including loss of speech, loss of expression, severe behavioral changes and immobility. RARE AND UNDERSERVEDpopulations with estimated U.S. prevalence of ~3,000 to 6,000 patients.No disease-modifying therapies are presently approved.

17 PBFT02OUR APPROACHProprietary construct delivers functional GRNgene encoding progranulin (PGRN) with potential therapeutic benefit of a one-time gene therapy approachPRECLINICAL EVIDENCECompelling preclinical evidence from NHP studies•Broad transduction across the brain, including high transduction of ependymal cells•Achieved supraphysiologic CSF levels of PGRN compared to levels in healthy human volunteersCLINICAL DEVELOPMENTOngoing global Phase 1/2 upliFT-D trial focused on early symptomatic FTD-GRNPotential transformative therapy for rare, underserved disorder

18 PBFT02: NHP Preclinical Studies Utilizing ICM•AAV1 increased CSF PGRN levels ~5x more than AAV5 and AAVhu68 vectors, without further elevating peripheral levels•CSF delivery of AAV1.hPGRN achieved supraphysiologic CSF levels of PGRN compared to levels in healthy human volunteers1Hinderer et al.,Annals Clin Trans Neurology.2020 Production of Human PGRN in Plasma Left, right: Two adult rhesus macaques per treatment received ICM AAV.hPGRNHigh dose, 3.0 x 1013GC / 3.3 x 1011GC/g brain) on study day 01.Center: Adult rhesus macaques received ICM PBFT02 (n = 3/dose) or vehicle (n =2) on study day 0. CSF was sampled 14 days post-dose.Shading: Reference ranges for healthy adult controls’ PGRN levels in CSF (n = 61) and plasma (n = 56) (Passage Bio data) AAV1 transgene delivery led to supraphysiologic hPGRNlevels in CSF CSF PGRN (ng/mL)010203040CSF0.1110100 Day AAVhu68AAVhu68(v2)AAV5AAV1NormalLLOQ PlasmaPlasma PGRN (ng/mL) 0102030400.1110100NormalDay1,000 PBFT02 (AAV1) Showed Dose-Related Increases in CSF PGRN 024681012High DoseMedium DoseLow DoseVehicleHuman PGRN (ng/ml) 14 days post-ICM dose

19 upliFT-D: Global Phase 1/2 Trial with PBFT02 OPTIONAL DOSE 3 DOSE 2 (1.1e11 GC/g)* DOSE 1 (3.3e10 GC/g)* 60 days between subject enrollment COHORT 1n = 3 COHORT 2n = 3 OPTIONAL COHORT 3n = 3 Trial DesignPhase 1/2, multicenter, open-label, dose escalation studyRoute of AdministrationIntra-cisterna magna (ICM)VectorAAV1Duration2 years; with additional 3 years of follow-up for safety and durability of effectPrimary Endpoints•Safety and tolerabilitySecondary Endpoints•Biomarkers, functional and clinical signs of disease progressionRegulatory Clearances and Designations•Received regulatory clearances from FDA, Health Canada and ANVISA (Brazil)•Received Orphan Drug and Fast Track designations by FDA and Orphan designation by EC* Genome copies per gram of estimated brain weight IDMC review Recruiting Dosing complete

Looking Ahead

21 TIMINGMILESTONEGM1Early 2022First patient dosed for Cohorts 2 and 3Feb 2022Late breaker presentation at WORLDSymposiumDecemberInitial safety and biomarker data for Cohorts 2 and 3FTD-GRNMid-2022First patient dosed in Phase 1/2 trial for PBFT02Key Milestones RESEARCH PIPELINE•Advance programs for ALS and Huntington’s Disease•Advance target ID research program for TLE•8 additional CNS pipeline options remain through GTP partnershipBALANCE SHEET•Cash balance of $214 million as of 9/30/22*•Cash on hand to fund operations into 1H 2025* Cash, cash equivalents and marketable securities

22 22Genetic Medicines Company on a Mission to Transform the Lives of Patients with CNS Diseases A diversified rare and large portfolio strategy to ensure sustained value Robust collaboration with GTP, an unmatched leader in cutting-edge AAV gene therapy research Dedicated manufacturing and analytics to ensure capacity, flexibility and control

Thank Youpassagebio.com |NASDAQ GS: PASG

24 Demonstrated LeadershipLEADERSHIP TEAM Deep experience in rare disease, CNS disorders and genetic medicines Simona KingChief Financial Officer Mark Forman, M.D., Ph.D.Chief Medical OfficerBOARD OF DIRECTORSMaxine Gowen, Ph.D.ChairwomanAthenaCountouriotis, M.D.AvenzoTherapeuticsDerrell Porter, M.D.CellevolveBioMichaelKamarck, Ph.D.Sanofi Biotech Advisory CouncilSandip KapadiaHarmony BiosciencesSaqib Islam, J.D.SpringWorksTom Woiwode, Ph.D.VersantWilliam Chou, M.D.Chief Executive Officer William Chou, M.D.Chief Executive Officer Chip CaleGeneral Counsel & Corporate Secretary Alex Fotopoulos Chief Technology Officer Desiree Luthman, D.D.S.SVP Global Regulatory Affairs

25 Intra-Cisterna Magna (ICM) Administration•Directly deliver vector into the CSF via a single injection to reach both CNS and peripheral tissues*–Allows for broad CNS biodistribution–Lower doses compared to IV systemic delivery–Reduced impact of neutralizing antibodies •Administered under anesthesia using modern neuroimaging to allow for precise delivery•Currently being used in several clinical studies in both pediatric and adult populations Cisterna magna Source:Hinderer et. al,Human Gene Therapy. 2018 Jan; 29(1):15-24Utilized across three clinical-stage programs to directly target CNS

26 Pathway to Patient Identification and Trial Recruitment Screening / DiagnosisSponsoring ScreenPlus Pilot Program•GM1 included in the New York newborn screening pilot program led by Dr. Melissa Wasserstein Supporting Invitae Detect LSD and InformedDNA Programs•Free genetic testing and counseling offered to support earlier diagnosis and patient identification•Clinical trial information provided to clinicians and patients Patient and Caregiver ActivitiesImplementing caregiver and physician support and/or training programsDecreasing patient and site trial burden•Remote visits and video capture implemented for relevant endpoints•Clincierge offered for travel and accommodation support Patient Recruitment and Advocacy StrategiesMaintaining strong relationships with trial sites, study coordinators and investigatorsEstablishing clinical trial sites at centers of excellence globally Increasing clinical trial awareness •Partnering with patient advocacy groups, medical specialists and organizations