ADC Therapeutics SA

Report of Independent Registered Public Accounting Firm

To the Board of Directors and Shareholders of ADC Therapeutics SA

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of ADC Therapeutics SA and its subsidiaries (the “Company”) as of December 31, 2024 and 2023, and the related consolidated statements of operations, comprehensive loss, changes in shareholders’ equity (deficit) and cash flows for the years then ended, including the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for the years then ended in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s consolidated financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits of these consolidated financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

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

Deferred royalty obligation with HealthCare Royalty Partners

As described in Note 12 to the consolidated financial statements, on August 25, 2021, the Company entered into a royalty purchase agreement with certain entities managed by HealthCare Royalty Partners (HCR) for up to $325.0 million. Under the terms of the agreement, the Company received gross proceeds of $225.0 million upon closing and received an additional $75.0 million during the year ended December 31, 2023. The Company’s aggregate royalty obligations are capped at 2.50 times the amount paid by HCR under the agreement or at 2.25 times the amount paid by HCR under the agreement if HCR receives royalty payments exceeding a mid-nine-digit amount on or prior to March 31, 2029 (the “Royalty Cap”). Once the Royalty Cap is reached, the royalty purchase agreement will terminate. The Company evaluated the terms of the royalty purchase agreement and concluded that the features of the investment amount are similar to those of a debt instrument. Accordingly, the Company recorded a liability relating to the initial gross proceeds received as debt less transaction costs in August 2021, and increased the liability in June 2023 for the eligible amount received as debt less transaction costs upon first commercial sale of ZYNLONTA in Europe. The Company accounts for the value of the debt at amortized cost. The amounts received by the Company will be accreted to the total estimated amount of the royalty payments necessary to extinguish the Company’s obligation under the agreement, which will be recognized as interest expense. The carrying value of the debt decreases for royalty payments made to HCR based on actual net sales and licensing revenue. To determine the accretion of the liability related to the deferred royalty obligation, the Company is required to estimate the total amount of future royalty payments and estimate the timing of such payments to HCR based on the Company's revenue projections. The Company uses a third party valuation firm to assist in determining the total amount of future royalty payments and estimates timing of such payment to HCR using an option pricing Monte Carlo simulation model. At each reporting period, the Company assesses the expected payments to HCR based on its underlying revenue projections and to the extent the amount or timing of such payments is materially different than its initial estimates, the Company will record a cumulative catch-up adjustment to the deferred royalty obligation. The Company’s deferred royalty obligation recognized within liabilities was $326.7 million as of December 31, 2024. The significant assumptions used to estimate the HCR deferred royalty obligation accretion of the liability include the revenue projections and timing of payments.

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

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

Product Revenue – Gross-to-net (GTN) sales adjustment – Discarded Drug Rebate

As described in Notes 2 and 16 to the consolidated financial statements, product revenue is recognized at the net selling price, which includes reductions for gross-to-net (“GTN”) sales adjustments such as government rebates, chargebacks, distributor service fees, other rebates and administrative fees, sales returns and allowances and sales discounts. Government rebates include the discarded drug rebate. The Infrastructure Investment and Jobs Act requires manufacturers of certain single-source drugs separately paid for under Medicare Part B and marketed in single-dose containers to refund the dispensed drug unused and discarded exceeding an applicable percentage defined by statute or regulation. The accrual for such rebate recognized within accrued expenses and other current liabilities was $15.1 million as of December 31, 2024. The significant assumptions used to estimate the discarded drug rebate include historical experience with discarded volumes considering time lags in the processing of claims and invoicing from the Centers for Medicare & Medicaid Services as well as legal interpretations of applicable laws and regulations used in the rebate calculation.

The principal considerations for our determination that performing procedures relating to the discarded drug rebate GTN sales adjustment is a critical audit matter are (i) the significant judgment made by management when determining the discarded drug rebate sales adjustment; and (ii) a high degree of auditor judgment, subjectivity, and effort in performing procedures and evaluating the audit evidence obtained related to the valuation of the discarded drug rebate and management’s assumptions related to historical experience with discarded volumes as well as legal interpretations of applicable laws and regulations used in the rebate calculation.

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

/s/PricewaterhouseCoopers SA

Pully, Switzerland

March 27, 2025

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