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(Registrant’s telephone number, including area code)

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

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 is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes ☐ No ☒

As of July 29, 2024, there were 27,736,760 shares of common stock, $0.001 par value per share, issued and outstanding.

Castle Biosciences, Inc. (the ‘‘Company”, “we”, “us” or “our”) was incorporated in the state of Delaware on September 12, 2007. We are a commercial-stage diagnostics company focused on providing clinicians and their patients with personalized, clinically actionable information to inform treatment decisions and improve health outcomes. We are based in Friendswood, Texas (a suburb of Houston, Texas) and our laboratory operations are conducted at our facilities located in Phoenix, Arizona and Pittsburgh, Pennsylvania.

Our unaudited condensed consolidated financial statements include the accounts of Castle Biosciences, Inc. and our wholly owned subsidiaries and have been prepared in conformity with accounting principles generally accepted in the United States of America (‘‘U.S. GAAP’’). All intercompany accounts and transactions have been eliminated in consolidation.

We have a history of recurring net losses and negative cash flows and as of June 30, 2024, we had an accumulated deficit of $212.0 million. We believe our $85.6 million of cash and cash equivalents and $174.1 million of marketable investment securities as of June 30, 2024, and anticipated revenue from our test reports, will be sufficient to meet our cash requirements through at least the 12-month period following the date that these unaudited condensed consolidated financial statements were issued.

The accompanying condensed consolidated balance sheet as of June 30, 2024; the condensed consolidated statements of operations, the condensed consolidated statements of comprehensive income (loss) and the condensed consolidated statements of stockholders’ equity, each for the three and six months ended June 30, 2024 and 2023; and the condensed consolidated statements of cash flows for the six months ended June 30, 2024 and 2023 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of our consolidated financial position as of June 30, 2024, the results of our consolidated operations for the three and six months ended June 30, 2024 and 2023 and our consolidated cash flows for the six months ended June 30, 2024 and 2023. The financial data and other information disclosed in these notes related to the three and six months ended June 30, 2024 and 2023 are also unaudited. The results for the three and six months ended June 30, 2024 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. The balance sheet as of December 31, 2023 included herein was derived from the audited financial statements as of that date. Certain disclosures have been condensed or omitted from the unaudited interim consolidated financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with our audited consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission (“SEC”) on February 28, 2024 (the “2023 Form 10-K”).

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant items subject to such estimates include revenue recognition, the valuation of stock-based compensation, assessing future tax exposure and the realizability of deferred tax assets, the useful lives and recoverability of long-lived assets, the goodwill impairment test, the valuation of acquired intangible assets and the valuation of contingent consideration and other contingent liabilities. We base these estimates on historical and anticipated results, trends, and various other assumptions that we believe are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenues and expenses that are not readily apparent from other sources. Actual results could differ from those estimates and assumptions.

Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less. Our cash equivalents consist of money market funds, which are not insured by the Federal Deposit Insurance Corporation (“FDIC”), that are primarily invested in short-term U.S. government obligations. Cash deposits at financial institutions may exceed the amount of insurance provided by the FDIC. Management believes that we are not exposed to significant credit risk on our cash deposits due to the financial position of the financial institutions in which deposits are held.

All debt securities are recognized in accordance with Financial Accounting Standards Board (‘‘FASB’’) Accounting Standards Codification (‘‘ASC’’) Topic 320, Investments-Debt Securities (‘‘ASC 320’’). Management determines the appropriate classification of securities at the time of purchase and re-evaluates such determination at each balance sheet date. All debt securities are classified as available-for-sale and are recorded at fair value in accordance with ASC 320. We recognize the unrealized gains and losses related to changes in fair value as a separate component of accumulated other comprehensive loss within total stockholders’ equity, net of any related deferred income tax effects, on our condensed consolidated balance sheets. Premiums or discounts from par value are amortized to interest income over the life of the underlying investment. Realized gains and losses on available-for-sale securities are calculated at the individual security level and included in interest income in the condensed consolidated statements of operations. Impairments of available-for-sale debt securities, if any, are recorded in our unaudited condensed consolidated statements of operations. See Notes 5 and 10 for further details.

In accordance with ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), we follow a five-step process to recognize revenues: (1) identify the contract with the customer, (2) identify the performance obligations, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations and (5) recognize revenues when the performance obligations are satisfied. We have determined that we have a contract with the patient when the treating clinician orders the test. Our contracts generally contain a single performance obligation, which is the delivery of the test report, and we satisfy our performance obligation at a point in time upon the delivery of the test report to the treating clinician, at which point we can bill for the report. The amount of revenue recognized reflects the amount of consideration to which we expect to be entitled, or the transaction price, and considers the effects of variable consideration. See Note 3 for further details.

We classify accounts receivable balances that are expected to be paid more than one year from the consolidated balance sheet date as noncurrent assets. The estimated timing of payment utilized as a basis for classification as noncurrent is determined by analyses of historical payor-specific payment experience, adjusted for known factors that are expected to change the timing of future payments.

We accrue an allowance for credit losses against our accounts receivable based on management’s current estimate of amounts that will not be collected. Management’s estimates are typically based on historical loss information adjusted for current conditions. We generally do not perform evaluations of customers’ financial condition and generally do not require collateral. Historically, our credit losses have not been significant given our application of the constraint to variable consideration. The allowance for credit losses was zero as of June 30, 2024 and December 31, 2023. Adjustments for implicit price concessions attributable to variable consideration, as discussed below, are incorporated into the measurement of the accounts receivable balances and are not part of the allowance for credit losses.

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally between five and ten years. Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful life of the asset or the term of the lease. Our leasehold improvements primarily relate to our office and laboratory facilities in Friendswood, Texas, Phoenix, Arizona and Pittsburgh, Pennsylvania, and are generally being depreciated through the end of the lease terms in 2025 and 2033, respectively. Maintenance and repairs are charged to expense as incurred, and material improvements are capitalized. Interest costs incurred during the construction of major capital projects are capitalized until the underlying asset is ready for its intended use, at which point the capitalized interest costs are amortized using the straight-line method over the estimated useful life of the underlying asset.

When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the consolidated balance sheet and any resulting gain or loss is reflected in the consolidated statements of operations in the period realized.

Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired in a business combination. In accordance with ASC Topic 350, Intangibles—Goodwill and Other, our goodwill is not amortized but is tested for impairment on an annual basis or whenever events or changes in circumstances indicate that it may be impaired. We perform annual impairment reviews of our goodwill balance during the fourth quarter of each fiscal year. We may perform a qualitative assessment to determine if it is necessary to perform a quantitative impairment test. If we determine that a quantitative impairment test is necessary, we apply the guidance in Accounting Standards Update (“ASU”) No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, by comparing the fair value of the reporting unit to its carrying value, including the goodwill. If the carrying value exceeds the fair value, we recognize an impairment loss for the amount by which the carrying value exceeds fair value, up to the total amount of goodwill allocated to the reporting unit. We did not incur any goodwill impairment losses in any of the periods presented.

Factors that could result in a future impairment of goodwill include declines in the price of our common stock, increased competition, changes in macroeconomic developments, unfavorable government or regulatory developments and changes in coverage or reimbursement conditions.

We accrue for liabilities under discretionary employee and executive bonus plans. Our estimated compensation liabilities are based on progress against corporate objectives approved by our board of directors, compensation levels of eligible individuals and target bonus percentage levels. Our board of directors reviews and evaluates the performance against these objectives and ultimately determines the actual achievement levels attained. We also accrue for liabilities under employee sales incentive bonus plans with accruals based on performance achieved to date compared to established targets. As of June 30, 2024 and December 31, 2023, we accrued approximately $12,573,000 and $21,706,000, respectively, for liabilities associated with these bonus plans. These amounts are classified as current or noncurrent accrued liabilities in the unaudited condensed consolidated balance sheets based on the expected timing of payment.

Stock-based compensation expense for equity instruments issued to employees is measured based on the grant-date fair value of the awards. The fair value of employee stock options and offerings under the 2019 Employee Stock Purchase Plan (the “ESPP”) are estimated on the date of grant using the Black-Scholes option-pricing valuation model. For restricted stock units (“RSUs”) and performance-based restricted stock units (“PSUs”), the fair value is equal to the closing price of our common stock on the date of grant. For awards with graded vesting and only service conditions, we recognize compensation costs on a straight-line basis over the requisite service period of the awards. For options and RSUs, the requisite service period is generally the award’s vesting period (typically four years). PSUs vest upon the achievement of certain performance conditions and the provision of service with us through a specified period. Accruals of compensation cost for PSUs are based on the probable outcome of the performance conditions and are reassessed each reporting period. We recognize compensation cost for PSUs separately for each vesting tranche on a ratable basis over the requisite service period. The requisite service period for PSUs is based on an analysis of vesting requirements and performance conditions for the particular award. Certain employees are entitled to acceleration of vesting of a portion of their awards upon retirement, subject to age, service and notice requirements. In these cases, the requisite service period takes into consideration the employee’s retirement eligibility, and is reassessed at each reporting date. For the ESPP, the requisite service period is generally the period of time from the offering date to the purchase date. Forfeitures are accounted for as they occur.

Comprehensive income (loss) is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive income (loss) is made up of net income (loss) plus net unrealized gain (loss) on marketable investment securities, which is our only other item of other comprehensive income (loss).

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740)—Improvements to Income Tax Disclosures (“ASU 2023-09”), which is intended to enhance the transparency and decision usefulness of income tax disclosures. The amendments in ASU 2023-09 provide for enhanced income tax information primarily through changes to the rate reconciliation and income taxes paid information. ASU 2023-09 is effective for the Company prospectively to all annual periods beginning after December 15, 2024. Early adoption is permitted. We are currently evaluating the impact this update will have on our consolidated financial statements and disclosures.

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280)—Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which require public companies disclose significant segment expenses and other segment items on an annual and interim basis and to provide in interim periods all disclosures about a reportable segment’s profit or loss and assets that are currently required annually. The guidance is effective for public entities for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The guidance is applied retrospectively to all periods presented in the financial statements, unless it is impracticable. We are currently evaluating the impact this update will have on our consolidated financial statements and disclosures.

We have evaluated all other recently issued, but not yet effective, accounting pronouncements and do not believe that these accounting pronouncements will have any material impact on our consolidated financial statements or disclosures upon adoption.

All of our revenues from contracts with customers are associated with the provision of testing services. Our revenues are primarily attributable to our DecisionDx®-Melanoma test for cutaneous melanoma. We also provide a test for patients with cutaneous squamous cell carcinoma, DecisionDx®-SCC, a test for use in patients with suspicious pigmented lesions, MyPath® Melanoma, a test for uveal melanoma, DecisionDx®-UM, a test for patients diagnosed with Barrett’s esophagus, the TissueCypher® Barrett’s Esophagus Test and a pharmacogenomics testing service focused on mental health, IDgenetix®. We previously offered a second test for patients with suspicious pigmented lesions, DiffDx®-Melanoma, which we suspended in February 2023. Information on the disaggregation of revenues is included below.

Once we satisfy our performance obligations and bill for the service, the timing of the collection of payments may vary based on the payment practices of the third-party payor and the existence of contractually established reimbursement rates. The payments for our services are primarily made by third-party payors, including Medicare and commercial health insurance carriers. Certain contracts contain a contractual commitment of a reimbursement rate that differs from our list prices. However, absent a positive coverage policy, with or without a contractually committed reimbursement rate, with a commercial carrier or governmental program, our diagnostic tests may or may not be paid by these entities. In addition, patients do not enter into direct agreements with us that commit them to pay any portion of the cost of the tests in the event that their insurance provider declines to reimburse us. We may pursue, on a case-by-case basis, reimbursement from such patients in the form of co-payments and co-insurance, in accordance with the contractual obligations that we have with the insurance carrier or health plan. These situations may result in a delay in the collection of payments.

The Medicare claims that are covered by Medicare are generally paid at a rate established on Medicare’s Clinical Laboratory Fee Schedule or by the respective Medicare contractor within 30 days from receipt. Medicare claims that were either submitted to Medicare prior to the local coverage determination or other coverage commencement date or are not covered but meet the definition of being medically reasonable and necessary pursuant to the controlling Section 1862(a)(1)(A) of the Social Security Act are generally appealed and may ultimately be paid at the first (termed ‘‘redetermination’’), second (termed ‘‘reconsideration’’) or third level of appeal (de novo hearing with an Administrative Law Judge). A successful appeal at any of these levels may result in prompt payment.

In the absence of Medicare coverage, contractually established reimbursements rates or other coverage, we have concluded that our contracts include variable consideration because the amounts paid by Medicare or commercial health insurance carriers may be paid at less than our standard rates or not paid at all, with such differences considered implicit price concessions. Variable consideration attributable to these price concessions is measured at the expected value using the ‘‘most likely amount’’ method under ASC 606.

The amounts are estimated using historical average collection rates by test type and payor category taking into consideration the range of possible outcomes, the predictive value of our past experiences, the time period of when uncertainties expect to be resolved and the amount of consideration that is susceptible to factors outside of our influence, such as the judgment and actions of third parties. Such variable consideration is included in the transaction price only to the extent it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainties with respect to the amount are resolved. Variable consideration may be constrained and excluded from the transaction price in situations where there is no contractually agreed upon reimbursement coverage or in the absence of a predictable pattern and history of collectability with a payor. Accordingly, in such situations revenues are recognized on the basis of actual cash collections. Variable consideration for Medicare claims that are not covered by Medicare, including those claims undergoing appeal, is deemed to be fully constrained due to factors outside our influence (e.g., judgment or actions of third parties) and the uncertainty of the amount to be received is not expected to be resolved for a long period of time. Variable consideration is evaluated each reporting period and adjustments are recorded as increases or decreases in revenues. Included in revenues for the three months ended June 30, 2024 and 2023 were $363,000 of net positive revenue adjustments and $88,000 of net negative revenue adjustments, respectively, associated with changes in estimated variable consideration. Included in revenues for the six months ended June 30, 2024 and 2023 were $959,000 of net positive and $1,705,000 of net negative revenue adjustments, respectively, associated with changes in estimated variable consideration. These amounts include (i) adjustments for actual collections versus estimated amounts and (ii) cash collections and the related recognition of revenue in current period for tests delivered in prior periods due to the release of the constraint on variable consideration.

Because our contracts with customers have an expected duration of one year or less, we have elected the practical expedient in ASC 606 to not disclose information about our remaining performance obligations. Any incremental costs to obtain contracts are recorded as selling, general and administrative expenses as incurred due to the short duration of our contracts. Contract balances consisted solely of accounts receivable (both current and noncurrent) as of June 30, 2024 and December 31, 2023.

The table below provides the disaggregation of revenue by type (in thousands):

			Three Months Ended June 30,												Six Months Ended June 30,
			2024						2023						2024						2023
Dermatologic(1)			$	68,828					$	43,030					$	128,163					$	78,941
Non-Dermatologic(2)			18,174						7,108						31,813						13,234
Total net revenues			$	87,002					$	50,138					$	159,976					$	92,175

(1)Consists of DecisionDx-Melanoma, DecisionDx-SCC and our Diagnostic Gene Expression Profile offering (MyPath Melanoma and DiffDx-Melanoma).

(2)Consists of TissueCypher Barrett’s Esophagus Test, DecisionDx-UM and IDgenetix.

We rely upon reimbursements from third-party government payors (primarily Medicare) and private-payor insurance companies to collect accounts receivable related to sales of our tests.

Our significant third-party payors and their related revenues as a percentage of total revenues and accounts receivable balances are as follows:

*    Less than 10%

There were no other third-party payors that individually accounted for more than 10% of our total revenue or accounts receivable for the periods shown in the table above.

Basic earnings (loss) per share is computed by dividing net income (loss) for the period by the weighted-average number of common shares outstanding during the period. Diluted earnings (loss) per share reflects the additional dilution from potential issuances of common stock, such as stock issuable pursuant to the exercise of stock options, vesting of RSUs and PSUs or purchases under the ESPP. The treasury stock method is used to calculate the potential dilutive effect of these common stock equivalents. Contingently issuable PSU awards are included in the computation of diluted earnings (loss) per share when the applicable performance criteria would be met and the common shares would be issuable if the end of the reporting period were the end of the contingency period. However, potentially dilutive shares are excluded from the computation of diluted loss per share when their effect is antidilutive.

The following table shows the computation of basic and diluted earnings (loss) per share for the following three and six months ended June 30, 2024 and 2023 (in thousands, except per share data):

						Three Months Ended June 30,												Six Months Ended June 30,
						2024						2023						2024						2023
Numerator:
Net income (loss)						$	8,920					$	(18,777)					$	6,386					$	(47,981)
Denominator:
Weighted-average common shares outstanding, basic						27,646						26,733						27,566						26,670
Assumed exercise of stock options						440						—						441						—
Assumed vesting of RSUs						546						—						427						—
Assumed vesting of PSUs						98						—						98						—
Assumed issuance of shares under the ESPP						8						—						10						—
Weighted-average common shares outstanding, diluted						28,738						26,733						28,542						26,670
Earnings (loss) per share:
Basic						$	0.32					$	(0.70)					$	0.23					$	(1.80)
Diluted						$	0.31					$	(0.70)					$	0.22					$	(1.80)

Due to the Company reporting a net loss attributable to common stockholders for the three and six months ended June 30, 2023, all potentially dilutive securities are antidilutive and are excluded from the computations of diluted loss per share.

The table below provides the weighted-average number of potential common shares associated with outstanding securities not included in our calculation of diluted earnings (loss) per share for the three and six months ended June 30, 2024 and 2023 because to do so would be antidilutive. With regard to the PSUs, we assume that the associated performance targets will be met at the target level of performance for purposes of calculating diluted net income per common share until such time that it is probable that actual performance will be above or below target (in thousands):

In addition, in connection with our acquisition of AltheaDx, Inc. (“AltheaDx”) in April 2022, we may be required to issue shares of our common stock to satisfy the contingent consideration obligations, pending the outcome of certain commercial and regulatory milestones, as required by the definitive agreement to acquire AltheaDx. For purposes of calculating diluted earnings (loss) per share, no such shares were assumed to have been issued because none of the applicable conditions have been met to date. See Note 10 for additional information.

The following tables present our available-for-sale debt securities (in thousands):

Although available to be sold to meet operating needs or otherwise, securities are generally held through maturity. We classify all investments as current assets, as these are readily available for use in current operations. The cost of securities sold is determined based on the specific identification method for purposes of recording gains and losses.

There were no realized gains or losses on sales of investments for the three and six months ended June 30, 2024 and 2023.

We evaluated our investment portfolio under the available-for-sale debt securities impairment model guidance and determined our investment portfolio is comprised of low-risk, investment grade securities. As of June 30, 2024, unrealized losses on our available-for-sale investments are not attributed to credit risk. We believe that an allowance for credit losses is unnecessary because the unrealized losses on certain of our marketable investment securities are due to market factors. No credit-related or noncredit-related impairment losses were recorded for the three and six months ended June 30, 2024 and 2023. The allowance for credit losses was zero as of June 30, 2024 and December 31, 2023.

As of June 30, 2024, all of our available-for-sale debt securities had contractual maturities of one year or less. Accrued interest receivable is included in prepaid expenses and other current assets in our unaudited condensed consolidated balance sheets. As of June 30, 2024 and December 31, 2023, the accrued interest receivable balance was immaterial.

Additional information relating to the fair value of marketable investment securities can be found in Note 10.

Property and equipment, net consisted of the following (in thousands):

(1)On February 9, 2024, we purchased approximately 23 acres of land in Friendswood, Texas for purpose of developing a commercial office building to be used as our future corporate headquarters.

(2)As of June 30, 2024 and December 31, 2023, includes lab equipment under finance lease of $369 thousand and accumulated depreciation of $323 thousand and $278 thousand, respectively.

(3)As of June 30, 2024, includes computer equipment under finance lease of $166 thousand and accumulated depreciation of $3 thousand. As of December 31, 2023, includes no computer equipment under finance lease.

Depreciation expense was recorded in the unaudited condensed consolidated statements of operations as follows (in thousands):

The balance of our goodwill was $10.7 million as of June 30, 2024 and December 31, 2023. There were no accumulated impairments of goodwill as of June 30, 2024 or December 31, 2023.

Our other intangible assets, net consist of the following (in thousands):

Amortization expense of intangible assets was $2.2 million and $4.5 million for the three and six months ended June 30, 2024, respectively, and $2.2 million and $4.5 million for the three and six months ended June 30, 2023, respectively.

Other accrued and current liabilities consisted of the following (in thousands):

Borrowings under our 2024 LSA approximate their fair value as the interest rate is variable and reflects market rates (Level 2 instrument). As of June 30, 2024, the carrying amount of borrowings under our 2024 LSA, exclusive of unamortized discount, and their estimated fair value were $10.2 million.

Future maturities of principal amounts on long-term debt as of June 30, 2024 are as follows (in thousands):

On March 26, 2024 (the ‘‘Closing Date’’), we entered into a Loan and Security Agreement (the ‘‘2024 LSA”), by and between us, our wholly owned subsidiary, Castle Narnia Real Estate Holding 1, LLC and Silicon Valley Bank, a division of First-Citizens Bank & Trust Company (the “Lender’’). The 2024 LSA provides for (i) on the Closing Date, $10.0 million aggregate principal amount of term loans (discussed in the ‘‘2024 Term Loan’’ section below), and (ii) from the Closing Date until March 31, 2025, an additional line of credit of $25.0 million with the same interest rate and maturity as the term debt available (discussed in the ‘‘2024 Credit Line’’ section below) at our option.

The obligations under the 2024 LSA are secured by substantially all of our assets, excluding intellectual property, the real property held by us, and are subject to certain other exceptions and limitations. We have the right to prepay the 2024 LSA in whole, subject to a prepayment fee of approximately 1.50% if prepaid prior to March 26, 2026. Amounts repaid under the 2024 LSA may not be reborrowed.

In addition, the 2024 LSA contains customary conditions of borrowing, events of default and covenants, including covenants that restrict our ability to dispose of assets, merge with or acquire other entities, incur indebtedness and make distributions to holders of our capital stock. Should an event of default occur, including the occurrence of a material adverse change, we could be liable for immediate repayment of all obligations under the 2024 LSA. Should we seek to amend the terms of the 2024 LSA, the consent of the Lender would be required.

As of June 30, 2024, we were in compliance with all of the covenants.

On March 26, 2024, we drew $10.0 million in Term Loans under the terms and provisions of the 2024 LSA. We are obligated to make a final payment of $200,000 under the terms of the 2024 LSA final payment provisions. A discount on debt equal to this obligation was recorded on the draw date and is being amortized as additional interest expense using the effective interest method over the term of the debt. As of June 30, 2024, no payment on principal has been made. As of June 30, 2024, the effective interest rate for all outstanding debt under the 2024 Term Loan was 9.03%.

The table below shows the components of interest expense for the three and six months ended June 30, 2024 (in thousands):

There was no interest expense on long term debt or capitalized interest for the three and six months ended June 30, 2023.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market in an orderly transaction between market participants at the measurement date. The fair value hierarchy prioritizes the inputs to valuation techniques used in measuring fair value. There are three levels to the fair value hierarchy based on the reliability of inputs, as follows:

Level 1 – Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly.

Level 3 – Unobservable inputs in which little or no market data exists, therefore requiring us to develop our own assumptions.

Financial instruments measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The use of different assumptions and/or estimation methodologies may have a material effect on estimated fair values. Accordingly, the fair value estimates disclosed, or amounts recorded, may not be indicative of the amount that we or holders of the instruments could realize in a current market exchange.

The table below provides information, by level within the fair value hierarchy, of our financial assets and liabilities that are accounted for at fair value on a recurring basis as of June 30, 2024 and December 31, 2023 (in thousands):

(1)Classified as “Cash and cash equivalents” in the unaudited condensed consolidated balance sheets.

(2)Classified as “Marketable investment securities” in the unaudited condensed consolidated balance sheets.

(3)Current portion, if any, classified as “Other accrued and current liabilities” in the unaudited condensed consolidated balance sheets.

In connection with our acquisition of AltheaDx, we agreed to pay contingent consideration of up to $75.0 million of commercial milestone payments based on the achievement of certain net revenue targets relating to the years ending December 31, 2022, 2023 and 2024 (“AltheaDx Earnout Payments”). The portion of the AltheaDx Earnout Payments associated with the commercial milestones for the year ended December 31, 2023 was $37.5 million and was not paid since the applicable commercial milestones were not met. The AltheaDx Earnout Payments included a 2022 catch-up provision for additional payment of up to $17.5 million that expired in 2023. Therefore, as of June 30, 2024, we have a potential payment obligation of up to $20.0 million with respect to the remaining commercial milestones for 2024. If the settlement of the remaining portion of the AltheaDx Earnout Payments would have occurred on June 30, 2024, no amounts would have been due because no commercial milestones had been achieved as of such date.

The contingent consideration was classified as a Level 3 fair value measurement due to the use of significant unobservable inputs and a Monte Carlo simulation to determine its fair value. The Monte Carlo simulation uses projections of the commercial milestones for the applicable period as well as the corresponding targets and approximate timing of payment based on the terms of the arrangement. The valuation of the AltheaDx contingent consideration was zero as of June 30, 2024 and December 31, 2023, and no gains or losses were recorded associated with changes in fair value during the three and six months ended June 30, 2024 and 2023.

The contingent consideration liability is remeasured at fair value at each reporting period taking into account any updated assumptions or changes in circumstances. Any changes in the fair value are recorded as gains or losses in our unaudited condensed consolidated statement of operations.

From time to time, we may be involved in legal proceedings arising in the ordinary course of business. We believe there is no threatened litigation or litigation pending that could have, individually or in the aggregate, a material adverse effect on our financial position, results of operations or cash flows. On February 1, 2024, we received a Subpoena from the Department of Health and Human Services, Office of Inspector General, seeking documents and information concerning claims submitted for payment under federal healthcare programs. The Subpoena requested that we produce documents relating primarily to interactions with medical providers and billing to government-funded healthcare programs for our tests. The time period covered by the Subpoena is January 1, 2015 through February 1, 2024. We are continuing to cooperate with the government’s request and are in the process of responding to the Subpoena. We are unable to predict what action, if any, might be taken in the future by the Department of Health and Human Services, Office of Inspector General, or any other governmental authority as a result of the matters related to this Subpoena. No claims have been made against us at this time. Any potential claims could subject us to significant liability for damages and harm our reputation. Our insurance and indemnities may not cover all claims that may be asserted against us. We are unable to predict the outcome and are unable to make a meaningful estimate of the amount or range of loss, if any, that could result from any unfavorable outcome.

Effective January 1, 2024, an additional 1,370,526 shares became available under our 2019 Equity Incentive Plan (the “2019 Plan”) pursuant to an automatic annual increase. The 2019 Plan provides for automatic annual increases to the number of shares authorized for issuance, equal to 5% of our common shares outstanding as of the immediately preceding year end, through January 1, 2029. As of June 30, 2024, 353,485 shares remained available for grant under the 2019 Plan.

On December 22, 2022, our board of directors approved the 2022 Inducement Plan (the “Inducement Plan”). Our Inducement Plan provides for the grant of RSU awards and other stock awards made as an inducement material to the grantee’s entering into employment with us to the extent such grantee was not previously an employee of ours or is entering into employment following a bona fide period of non-employment with us. As of June 30, 2024, there were 292,473 shares available for grant under the Inducement Plan.

Stock option activity under our stock plans for the six months ended June 30, 2024 is set forth below:

RSUs represent the right to receive shares of our common stock at a specified future date, subject to vesting. Our RSUs generally vest annually from the grant date in four equal installments subject to the holder’s continued service with us. We issue new shares of common stock upon the vesting of RSUs.

The following table summarizes our RSU activity for the six months ended June 30, 2024:

(1)The aggregate number of shares withheld upon vesting for employee tax obligations was 51,519 for the six months ended June 30, 2024.

PSUs represent the right to receive shares of our common stock contingent upon the achievement of certain financial performance measures. We issue new shares of common stock upon the vesting of PSUs.

The following table summarizes our PSU activity for the six months ended June 30, 2024:

In January 2023, our board of directors approved a retirement policy (the “Retirement Policy”) that provides for acceleration of a portion of unvested awards that were granted to certain eligible employees upon meeting age, service and notice requirements. We considered the adoption of the Retirement Policy to be a modification of existing awards under ASC Topic 718, Compensation – Stock Compensation. The modification did not result in any incremental compensation cost. However, the adoption of the policy resulted in a new estimate of the requisite service period for certain awards, which we reassess at each balance sheet date. In connection with the Retirement Policy, we accelerated the recognition of compensation expense of $0.4 million and $0.4 million during the three months ended June 30, 2024 and 2023, respectively, and accelerated the recognition of compensation expense of $0.6 million and $1.1 million for the six months ended June 30, 2024 and 2023, respectively.

The ESPP provides for certain automatic increases in the number of shares of common stock reserved for issuance, which resulted in an additional 274,105 shares becoming available under the ESPP effective January 1, 2024. During the six months ended June 30, 2024, we issued 111,241 shares of common stock pursuant to scheduled purchases under the ESPP. As of June 30, 2024, 1,103,127 shares remained available for issuance under the ESPP.

We use the Black-Scholes option pricing model to estimate the fair value of each option grant on the date of grant or any other measurement date. The following table sets forth the assumptions used to determine the fair value of stock options:

The following table sets forth assumptions used to determine the fair value of the purchase rights issued under the ESPP:

We use the closing price of our common stock on the date of grant to determine the fair value of RSUs and PSUs.

Stock-based compensation expense is included in the unaudited condensed consolidated statements of operations as follows (in thousands):

For the six months ended June 30, 2023, the weighted-average grant date fair value of stock options granted was $15.99 per option. There were no stock options granted for the same period in 2024. For the six months ended June 30, 2024 and 2023, the weighted-average grant date fair value of the purchase rights granted under the ESPP was $11.17 and $11.00 per share, respectively. As of June 30, 2024, the total unrecognized stock-based compensation cost related to outstanding awards was $94,633,000, which is expected to be recognized over a weighted-average period of 2.4 years. The total unrecognized compensation cost will be adjusted for forfeitures in future periods as they occur.

Our effective income tax rate was (13.1)% and (18.3)% for the three and six months ended June 30, 2024, respectively. Our effective income tax rate was immaterial for the three and six months ended June 30, 2023, respectively.

The effective rate for the three and six months ended June 30, 2024 and 2023 differed from our federal statutory rate of 21% primarily due to the tax impact from the valuation allowance for current year activity, state income taxes and the non-deductibility of other permanent items.

Castle Biosciences is a molecular diagnostics company offering innovative test solutions to aid clinicians in the diagnosis and treatment of dermatologic cancers, Barrett’s esophagus (“BE”), uveal melanoma (“UM”), and in the treatment of mental health conditions.

We currently offer five commercially available proprietary multi-analyte assays with algorithmic analysis (“MAAA”) tests for use in the dermatologic, gastroenterology and ocular fields. We also offer a proprietary pharmacogenomics (“PGx”) test to guide optimal drug treatment for patients diagnosed with depression, anxiety and other mental health conditions.

Currently, our revenue is primarily generated by our DecisionDx-Melanoma risk stratification test for cutaneous melanoma (“CM”), which is supplemented by revenue generated from our DecisionDx-SCC risk stratification test for cutaneous squamous cell carcinoma (“SCC”), our TissueCypher risk stratification test for BE and our DecisionDx-UM risk stratification test for UM.

All five of our MAAA tests have been granted Advanced Diagnostic Laboratory Test (“ADLT”) status by the Centers for Medicare & Medicaid Services (“CMS”) which means each test has demonstrated that (i) when combined with an empirically derived algorithm, it yields a result that predicts the probability a specific individual patient will develop a certain condition or conditions, or will respond to a particular therapy or therapies; and (ii) it provides new clinical diagnostic information that cannot be obtained from any other test or combination of tests. We believe this designation not only demonstrates our focus on developing and validating innovative tests but also enables our Medicare reimbursement rate to be set, over the long term, by the median private payor rate, which we believe provides a fair exchange of value. Further information about Medicare coverage and ADLT status with respect to each of our tests is set forth below.

DecisionDx-Melanoma is our proprietary risk stratification gene expression profile (“GEP”) test that is designed to predict the risk of metastasis or recurrence for patients diagnosed with invasive CM.

In a typical year, we estimate approximately 130,000 patients are diagnosed with invasive CM in the United States, representing an estimated U.S. total addressable market (“TAM”) of approximately $540 million. We estimate that approximately 50% of patients diagnosed with CM are 65 years of age or older.

DecisionDx‑SCC is our proprietary GEP test for use in patients with SCC, with one or more risk factors (also referred to as “high-risk” SCC). We estimate that 20% of SCC patients, or 200,000 annually in the United States, are classified as high risk, representing an estimated U.S. TAM of approximately $820 million.

MyPath Melanoma is our proprietary GEP test for use in patients with a melanocytic lesion and uncertainty related to the malignancy of the lesion. We estimate approximately 300,000 patients each year present with a diagnostically ambiguous lesion, representing an estimated U.S. TAM of approximately $600 million. We began offering MyPath Melanoma following our acquisition of the Myriad MyPath Laboratory in May 2021 at which point we offered both our MyPath Melanoma test and our DiffDx-Melanoma test under an offering that we referred to as our Diagnostic GEP offering. However, following an internal assessment of the clinical value of offering both tests, we made the decision to suspend the clinical offering of DiffDx-Melanoma in February 2023 and now the focus of this offering is MyPath Melanoma.

TissueCypher is our proprietary risk stratification spatial omics test designed to predict future development of high-grade dysplasia and/or esophageal cancer in patients with non-dysplastic, indefinite dysplasia or low-grade dysplasia BE. We estimate a U.S. TAM of approximately $1 billion.

DecisionDx-UM is a proprietary, risk stratification GEP test that is designed to predict the risk of metastasis for patients with UM. We believe DecisionDx-UM is the standard of care in the management of newly diagnosed UM in the majority of ocular oncology practices in the United States. We estimate a U.S. TAM of approximately $10 million.

IDgenetix is a PGx test that guides personalized mental health medication selection and management for patients with depression, anxiety and other mental health conditions. We estimate a U.S. TAM of approximately $5 billion associated with this test.

In September 2022, we established a new commercial sales team dedicated to our Diagnostic GEP offering and added additional outside territories for our TissueCypher test, which were fully integrated into our commercial operations by the end of the second quarter of 2023.

During the year ended December 31, 2023, we continued to expand our dermatologic and gastrointestinal commercial sales forces through territory and headcount expansions with focus being on our DecisionDx Melanoma, DecisionDx-SCC, and TissueCypher tests.

During the six months ended June 30, 2024, we further expanded our sales and marketing team for our TissueCypher test. We will continue to assess market response in determining further commercial expansions and commercial team structure.

The primary source of revenue for our products is reimbursement from third-party payors, which includes government payors, such as Medicare, and commercial payors, such as insurance companies. Achieving broad coverage and reimbursement of our current products by third-party payors and continued Medicare coverage are key components of our financial success.

We bill third-party payors and patients for the tests we perform. We have received Medicare coverage for our DecisionDx-Melanoma, DecisionDx-SCC, MyPath Melanoma, DecisionDx-UM, TissueCypher and IDgenetix tests which meet certain criteria for Medicare and Medicare Advantage beneficiaries.

The Medicare rates discussed below are prior to giving effect to applicable sequestration in effect from time to time as described in further detail under “Government Regulation and Product Approval—Healthcare Reform” included in Item 1, Business, of our Annual Report on Form 10-K for the year ended December 31, 2023.

DecisionDx-Melanoma tests are processed from our Phoenix laboratory and since the second quarter of 2022, have been covered under “foundational” local coverage determinations (“LCD”) finalized by Medicare Administrative Contractors (“MACs”) Palmetto GBA MolDX (“Palmetto”) and Noridian Health Solutions (“Noridian”).

DecisionDx-Melanoma has met ADLT status, as determined by the CMS, since 2019. Since 2022, the rate for DecisionDx-Melanoma is set annually based upon the median private payor rate for the first half of the second preceding calendar year. For example, the rate for 2023 was set using median private payor rate data from January 1, 2021 to June 30, 2021. Our rate for 2023 was $7,193 per test and is $7,193 for 2024.

DecisionDx-UM tests are processed from our Phoenix laboratory and are covered under LCDs finalized by MAC administrators Palmetto and Noridian in July 2017.

DecisionDx-UM has met the criteria of “existing advanced diagnostic laboratory test” status, also referred to as “existing ADLT” status, as determined by the CMS, since May 2019. Our rate is set annually based upon the median private payor rate for the first half of the second preceding calendar year. For example, the rate for 2023 was set using median private payor rate data from January 1, 2021 to June 30, 2021. Our rate for 2023 was $7,776 per test and is $7,776 for 2024.

MyPath Melanoma was covered under a test-specific LCD policy through Noridian that became effective in June 2019. Effective August 6, 2023, Palmetto and Noridian issued LCDs that converted the test-specific MyPath Melanoma LCD to a “foundational” LCD and provided coverage for both MyPath Melanoma and DiffDx-Melanoma.

MyPath Melanoma was approved as a “new ADLT” in September 2019. The rate for our MyPath Melanoma test is set annually based upon the median private payor rate for the first half of the second preceding calendar year. Our 2023 rate was set at $1,755 per test, based on data submitted by the predecessor owner of the Myriad MyPath Laboratory relating to the first half of 2021. Our 2024 rate is set at $1,950 per test.

In the second quarter of 2022, we obtained a Proprietary Laboratory Analyses (“PLA”) code for DiffDx-Melanoma. In 2023, DiffDx-Melanoma went through the CMS gapfill process which concluded in September 2023 with CMS posting a final MAC-specific gapfill rate of $1,950 per test. Our rate for 2024 is $1,950 per test.

Our Diagnostic GEP offering included MyPath Melanoma and DiffDx-Melanoma. We began offering MyPath Melanoma following our acquisition of the Myriad MyPath Laboratory on May 28, 2021. Our internal data indicates that we have improved the technical performance of MyPath Melanoma and that it is comparable to the technical performance of DiffDx-Melanoma. As such, following an internal assessment of the clinical value of offering both tests, we made the decision to suspend the clinical offering of DiffDx-Melanoma in February 2023.

We issue our DecisionDx-SCC tests from our Pittsburgh and Phoenix labs, with a majority of tests being issued from our Pittsburgh lab.

On June 2, 2023, Novitas Solutions (“Novitas”), the MAC responsible for administering claims for test reports issued by our Pittsburgh laboratory, posted a finalized oncology biomarker LCD pursuant to which the DecisionDx-SCC test would no longer be covered by Medicare effective July 17, 2023. However, on July 6, 2023, Novitas suspended the final version of the LCD and announced its intent to post a new proposed LCD for comment and presentation at an open meeting. On July 27, 2023, Novitas posted a nearly identical proposed oncology biomarker LCD that continues to intend to rely upon evidentiary reviews sourced from three databases: ClinGen, OncoKB and NCCN. The proposed LCD also recommends non-coverage for our DecisionDx-SCC test. The comment period for the proposed LCD ended on September 9, 2023. We cannot predict whether this LCD will be finalized as proposed or what the timing of any final LCD might be.

DecisionDx-SCC was reimbursed at a rate of $3,873 per test under a PLA code from second quarter of 2022 through June 30, 2023 when CMS determined DecisionDx-SCC meets the criteria for “new ADLT” status. Effective July 1, 2023 and through March 31, 2024, CMS set the initial period rate equal to the list price of $8,500 per test. Effective April 1, 2024 and through December 31, 2025, the published CLFS rate for DecisionDx-SCC will be based on the median private payor rates received between July 1, 2023 and November 30, 2023. We submitted the median private payor data to CMS during the data reporting period in December 2023. Effective April 1, 2024, the updated CLFS rate will continue at $8,500 through December 31, 2025. Future rates will be set annually based upon the median private payor rate for the first half of the second preceding calendar year. ADLT status determines the process by which the rate is set and is not an indication of Medicare coverage.

TissueCypher is processed in our Pittsburgh laboratory and falls under the Medicare jurisdiction managed by Novitas.

On March 24, 2022, CMS determined that TissueCypher meets the criteria for “new ADLT” status. ADLT status exempts TissueCypher from what is called the “14-day rule,” which simplifies the billing process for Medicare patients. Effective January 1, 2023, the published CLFS rate for TissueCypher was set at $4,950 per test, which will remain effective through December 31, 2024. This rate is based on the median private payor rates received between April 1, 2022 and August 31, 2022. Thereafter, the rate will be set annually based upon the median private payor rate for the first half of the second preceding calendar year.

IDgenetix is currently covered under a Noridian LCD policy and accompanying billing and coding article developed by MolDX.

Our IDgenetix multi-gene panel was reimbursed by Medicare at approximately $1,500 per test from April 2022 through February 2023, when MolDX notified us that as part of its annual CPT code updates, IDgenetix should shift billing to a different generic gene sequencing CPT code (the “New CPT Code”) and continue using the IDgenetix Z-Code beginning in March 2023. The New CPT Code was set at $917 per test while the test went through CMS’s Gapfill pricing process. We believed the new CPT Code, in conjunction with the IDgenetix Z-Code, did not describe all of the components of the IDgenetix test and thus, was not appropriate for IDgenetix. We subsequently obtained a test-specific PLA CPT code which became effective October 1, 2023. In November 2023, CMS posted its final CLFS determination which crosswalks our PLA CPT code to an existing PLA code at a rate of $1,336 per test effective January 1, 2024.

On April 29, 2024, the U.S. Food and Drug Administration (“FDA”) published a final rule on the regulation of Laboratory Developed Tests (“LDTs”) which amends the FDA's regulations to make explicit that LDT's are devices under the Federal Food, Drug, and Cosmetic Act (“FD&C Act”). The FDA issued a policy to phase out, over the course of four years, its general enforcement discretion approach to LDTs and also issued targeted enforcement discretion policies for certain categories of LDTs. The FDA is continuing enforcement discretion for currently marketed tests offered as LDTs (that were first marketed before May 6, 2024) that are approved by the New York State Department of Health Clinical Laboratory Evaluation Program (“NYS CLEP”). Our proprietary tests, outlined above, are all NYS CLEP approved. We believe this final ruling will have no material impact on our existing test offerings given all of our tests were marketed before May 6, 2024.

The number of test reports we deliver is a key indicator that we use to assess our business. A test report is generated when we receive a sample in our laboratory, and then the relevant test information is entered into our Laboratory Information Management System, the laboratory portion of the test is performed, including proprietary algorithmic analysis of the combined biomarkers, and a report is then generated which is delivered to the clinician who ordered the test.

The number of test reports delivered by us during the six months ended June 30, 2024 and 2023 and for the year ended December 31, 2023 are presented in the table below:

(1)Includes MyPath Melanoma and DiffDx-Melanoma. We offered both MyPath Melanoma and DiffDx-Melanoma under our Diagnostic GEP offering until February 2023 when we suspended the offering of DiffDx-Melanoma, as discussed above.

(2)We temporarily paused accepting additional orders in July 2023 and resumed accepting new orders in a phased approach in September 2023. We completed processing of our pre-existing backlog orders in October 2023 and continue to accept new orders as of June 30, 2024.

For the three and six months ended June 30, 2024, our test report volume increased by 49.2% and 44.9%, respectively, compared to the same period in 2023. Our dermatologic test report volume increased by 22% and 20.3% for the three and six months ended June 30, 2024, respectively, compared to the prior period in 2023, largely driven by continued growth from our DecisionDx-Melanoma and DecisionDx-SCC tests. Increases from our other tests (non-dermatologic), primarily IDgenetix and TissueCypher, also contributed to the overall volume increase. For a discussion of how we recognize revenue derived from our tests, refer to “Net Revenues” under “Components of Results of Operations” below.

In developing our DecisionDx-SCC test, we believed that in addition to addressing significant unmet clinical needs, we would see opportunities for leverage, as many of the clinicians currently ordering DecisionDx-Melanoma would likely be the same clinicians who would find value in our DecisionDx-SCC test. For example, we found that during the six months ended June 30, 2024, approximately 68% of all clinicians ordering DecisionDx-SCC had also ordered our DecisionDx-Melanoma test during that same period.

The following provides additional information about certain metrics we have disclosed in this Management’s Discussion and Analysis of Financial Condition and Results of Operations.

Test reports delivered represent the number of completed test reports delivered by us during the reporting period indicated. The period in which a test report is delivered does not necessarily correspond with the period in which the related revenue, if any, is recognized, due to the timing and amount of adjustments for variable consideration under Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”). We use this metric to evaluate the growth in adoption of our tests and to measure against our internal performance objectives. We believe this metric is useful to investors in evaluating the volume of our business activity from period-to-period that may not be discernible from our reported revenues under ASC 606.

Macroeconomic conditions, including uncertainties associated with the Israel-Hamas war, the ongoing conflict between Ukraine and Russia, economic slowdowns, public health crises, labor shortages, recessions or market corrections, supply chain disruptions, inflation and monetary policy shifts, liquidity concerns at, and failures of, banks and other financial institutions or other disruptions in the banking system or financing markets, rising interest rates and financial and credit market fluctuations, volatility in the capital markets or other evolving macroeconomic developments, continue to have direct and indirect impacts on our business and could in the future materially impact our results of operations and financial condition. We continue to actively monitor the impact of these macroeconomic factors on our results of operations, financial condition and cash flows. The extent of the impact of these factors on our operational performance and financial condition, including our ability to execute our business strategies and initiatives in the expected timeframe, will depend on future developments, which are uncertain and cannot be predicted; however, any continued or renewed disruption resulting from these factors could negatively impact our business.

Our net income may fluctuate significantly from period to period, depending on the timing of our planned development activities, the growth of our sales and marketing activities and the timing of revenue recognition under ASC 606. We expect our expenses will increase substantially over time as we:

•execute clinical studies to generate evidence supporting our current and future product candidates;

•execute our commercialization strategy for our current and future commercial products;

•continue our ongoing and planned development of new products in our pipeline;

•seek to discover and develop additional product candidates;

•hire additional scientific and research and development staff; and

•add additional operational, financial and management information systems and personnel.

We believe there are several important factors that have impacted, and that we expect will continue to impact, our operating performance and results of operations, including:

•Report volume. We believe that the number of reports we deliver to clinicians is an important indicator of the growth of adoption among the healthcare provider community. Our revenue and costs are affected by the volume of testing and mix of customers. Our performance depends on our ability to retain and broaden adoption with existing prescribing clinicians, as well as attract new clinicians. Our report volume could be negatively impacted by developments related to evolving macroeconomic developments, as discussed above.

•Reimbursement. We believe that expanding reimbursement is an important indicator of the value of our products. Payors require extensive evidence of clinical utility, clinical validity, patient outcomes and health economic benefits in order to provide reimbursement for diagnostic products. Our revenue depends on our ability to demonstrate the value of our products to these payors.

•Gross margin. We believe that our gross margin is an important indicator of the operating performance of our business. Higher gross margins reflect the average selling price of our tests, as well as the operating efficiency of our laboratory operations.

•Expansion of our sales force and marketing programs. We believe the expansion of our direct sales force and marketing organization to educate clinicians and pathologists on the value of our molecular testing products will significantly impact our performance.

•Integrating acquisitions. Revenue growth, operational results and advances to our business strategy depends on our ability to integrate any acquisitions into our existing business and effectively scale their operations. The integration of acquired assets may impact our revenue growth, increase the cost of operations or may require management resources that otherwise would be available for ongoing development of our existing business.

•New product development. A significant aspect of our business is our investment in research and development activities, including activities related to the development of new products. In addition to the development of new product candidates, we believe these studies are critical to gaining clinician adoption of new products and driving favorable coverage decisions by payors for such products.

We generate revenues from the sale of our products. Currently, our revenues are primarily derived from the sale of DecisionDx-Melanoma, DecisionDx-SCC, TissueCypher and DecisionDx-UM. We bill third-party payors and patients for the tests we perform.

Under ASC 606, we recognize revenue at the amount we expect to be entitled, subject to a constraint for variable consideration, in the period in which our tests are delivered to the treating clinicians. We have determined that our contracts contain variable consideration under ASC 606 because the amounts paid by third-party payors may be paid at less than our standard rates or not paid at all, with such differences considered implicit price concessions. Variable consideration is recognized only to the extent it is probable that a significant reversal of revenue will not occur in future periods when the uncertainties are resolved. Variable consideration is evaluated each reporting period and adjustments are recorded as increases or decreases in revenues. Variable consideration for Medicare claims that are not covered by Medicare, including those claims undergoing appeal, is deemed to be fully constrained due to factors outside our influence (e.g., judgment or actions of third parties) and the uncertainty of the amount to be received is not expected to be resolved for a long period of time. For these fully constrained claims, we generally recognize revenue in the period the uncertainty is favorably resolved, if at all. Due to potential future changes in Medicare coverage policies and appeal cycles, insurance coverage policies, contractual rates and other trends in the reimbursement of our tests, our revenues may fluctuate significantly from period to period. Our ability to recognize revenue for a test is dependent on the development of reimbursement experience and obtaining coverage decisions. For tests with limited reimbursement experience or no coverage, we recognize revenues on the basis of actual cash collections.

Our ability to increase our revenues will depend on our ability to further penetrate our target markets, and, in particular, generate sales through our direct sales force, maintain Medicare coverage for our currently marketed products, develop and commercialize additional tests, including through acquisitions, obtain reimbursement from additional third-party payors and increase our reimbursement rate for tests performed.

The components of our cost of sales are material and service costs associated with testing samples, personnel costs (including salaries, bonuses, benefits and stock-based compensation expense), electronic medical record set up costs, order and delivery systems, shipping charges to transport samples, third-party test fees, and allocated overhead including rent, information technology costs, equipment and facilities depreciation and utilities. Costs associated with testing samples are recorded when the test is processed regardless of whether and when revenues are recognized with respect to that test. As a result, our cost of sales as a percentage of revenues may vary significantly from period to period because we do not recognize all revenues in the period in which the associated costs are incurred. We expect cost of sales in absolute dollars to increase as the number of tests we perform increases. Additionally, we expect cost of sales to increase with the expansion of laboratory capacity and staffing in advance of the anticipated growth of our more recently launched tests and tests acquired through acquisitions. For example, we commenced operations in a newly expanded laboratory facility in Pittsburgh, Pennsylvania in the second quarter of 2023 and expect to operate additional lab space in Pittsburgh by end of 2024.

Gross margin and gross margin percentage are key indicators we use to assess our business. See the table in “Results of Operations—Comparison of the Three Months Ended June 30, 2024 and 2023” and “Results of Operations—Comparison of the Six Months Ended June 30, 2024 and 2023” for details.

Research and development expenses include costs incurred to develop our tests, collect clinical samples and conduct clinical studies to develop and support our products. These costs consist of personnel costs (including salaries, bonuses, benefits and stock-based compensation expense), prototype materials, laboratory supplies, consulting costs, regulatory costs, electronic medical records set up costs, costs associated with setting up and conducting clinical studies and allocated overhead, including rent, information technology, equipment depreciation and utilities. We expense all research and development costs in the periods in which they are incurred. We expect our research and development expenses to increase in absolute dollars as we continue to invest in research and development activities related to developing enhanced and new products.

We expect to use a portion of our cash and cash equivalents and marketable investment securities to further support and accelerate our research and development activities, including important studies that are underway to support our DecisionDx-Melanoma test. For instance, in February 2023, we announced the publication of data from the DECIDE study presenting DecisionDx-Melanoma test results influenced 85% of clinicians’ decisions regarding the SLNB surgical procedure. Additionally, use of the tests’ results within current guideline recommendations led to a significant reduction in SLNB procedures performed, demonstrating the clinical value of the test to guide risk-aligned patient care. Also, in 2021, we initiated our large prospective, multi-center clinical study to develop, validate and bring to market a pipeline genomic test, or tests, aimed at predicting response to systemic therapy in patients with moderate to severe psoriasis, atopic dermatitis and related inflammatory skin conditions. As of June 30, 2024, there were more than 41 active clinical study sites and over 1,100 patients enrolled in this study. Assuming we are successful in validating a genomic test, or tests, for one or more of these uses, then we expect to launch this pipeline test by the end of 2025.

Selling, general and administrative (“SG&A”) expenses include executive, selling and marketing, legal, finance and accounting, human resources and billing functions. These expenses consist of personnel costs (including salaries, bonuses, benefits and stock-based compensation expense), direct marketing expenses, audit and legal expenses, consulting costs, payor outreach programs and allocated overhead, including rent, information technology, equipment depreciation, and utilities. Other administrative and professional services expenses within SG&A are expected to increase with the scale of our business, but selling and marketing-related expenses are expected to increase significantly, consistent with our growth strategy.

Amortization of acquired intangible assets is primarily associated with developed technology obtained through acquisitions, such as our acquisitions of Cernostics in December 2021 and AltheaDx in April 2022.

Interest income consists primarily of earnings on cash and cash equivalents, primarily money market funds, and marketable investment securities, primarily short-term U.S. government obligations.

Interest expense is primarily attributable to long-term debt and finance leases.

Our consolidated financial statements do not reflect any federal or state income tax benefits attributable to the pre-tax losses we have incurred, due to the uncertainty of realizing a benefit from those items. As of December 31, 2023, we had federal net operating loss (“NOL”) carryforwards of $197.1 million, of which $92.0 million will begin to expire in 2029 if not utilized to offset federal taxable income, and $105.1 million may be carried forward indefinitely. As of December 31, 2023, we also had state NOL carryforwards of $114.3 million, which begin to expire in 2028 if not utilized to offset state taxable income.