Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

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

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Overview

ADC Therapeutics is a commercial-stage global pioneer in the field of antibody drug conjugates (“ADCs”), transforming treatment for patients through our focused portfolio with ZYNLONTA (loncastuximab tesirine-lpyl), a CD19-directed ADC. ZYNLONTA received accelerated approval from the U.S. Food and Drug Administration (“FDA”) and conditional approval from the European Commission, China National Medical Products Administration (“NMPA”) and Health Canada for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. We are pursuing expansion of ZYNLONTA internationally, and into earlier lines of diffuse large B-cell lymphoma (“DLBCL”) through our LOTIS-5 confirmatory Phase 3 clinical trial (rituximab combination) and LOTIS-7 Phase 1b clinical trial (bispecific combination) as well as into indolent lymphomas, including marginal zone lymphoma (“MZL”) and follicular lymphoma (”FL”), through investigator-initiated trials (“IITs”) at leading institutions.

Our goal is to be a leading ADC company bringing meaningful therapies to patients in need by leveraging our decade-long experience in the ADC field, with multiple INDs, and a proven track record of success. We are focused on maximizing the ZYNLONTA opportunity through expansion into earlier lines of therapies of DLBCL and indolent lymphomas.

On June 11, 2025, the Board of Directors approved a strategic reprioritization and restructuring plan (the “2025 Restructuring”) to focus resources on ZYNLONTA expansion opportunities and the advancement of its preclinical exatecan-based PSMA-targeting ADC. The Company closed down its UK facility, and has reduced its global workforce across functions by approximately 30%.

Results of Operations

The following table summarizes our results of operations for the years ended December 31, 2025 and 2024:

Year Ended December 31,

(in thousands, except percentages and per share) 2025 2024 Change % Change

Revenue

Operating expense

Restructuring, impairment and other related costs (13,120) — (13,120) 100.0 %

Other income (expense)

Equity in net losses of joint venture — (1,544) 1,544 (100.0) %

Net loss per share, basic and diluted $ (1.12) $ (1.62) $ 0.50 (30.8) %

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Revenue

Product Revenues, net

We generate product revenue through the sale of ZYNLONTA in the United States. Revenue is recognized when control is transferred to the customer at the net selling price, which includes reductions for gross-to-net (“GTN”) sales adjustments such as government rebates, chargebacks, distributor service fees, other rebates and administrative fees, sales returns and allowances and sales discounts. Our product revenue may fluctuate from period to period based on a number of factors, including patient demand, as well as the timing, dose and duration of patient therapy and customers’ ordering patterns, pricing and GTN deductions. We expect a relatively consistent level of GTN sales adjustments as a percentage of gross sales, but may also experience variability in GTN sales adjustments due to additional information and actual experience such as actual rebate and return rates.

Product revenues, net, were $73.6 million for the year ended December 31, 2025 as compared to $69.3 million for the year ended December 31, 2024, an increase of $4.3 million, or 6.2%. The increase is principally attributable to a higher sales price, with consistent sales volume on a period over period basis.

License Revenue and Royalties

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

License revenues and royalties were $7.8 million for the year ended December 31, 2025 as compared to $1.6 million for the year ended December 31, 2024, an increase of $6.2 million attributable to our exclusive license agreement with Sobi to develop and commercialize ZYNLONTA in all territories other than the United States, greater China, Singapore and Japan. In March 2025, the Company recognized $5.0 million in license revenue in connection with a milestone due upon ZYNLONTA’s conditional approval by Health Canada for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy, which was paid to us by Sobi in the second quarter of 2025. The increase was also attributable to increased royalty revenue from Sobi.

Operating Expenses

Cost of Product Sales

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

Cost of product sales were $5.8 million for the year ended December 31, 2025 as compared to $5.9 million for the year ended December 31, 2024, a decrease of $0.1 million, or 2.5%. The decrease in cost of product sales was primarily driven by a $1.1 million batch cancellation fee recognized during the year ended December 31, 2024, partially offset by higher inventory write-downs of $0.8 million during the year ended December 31, 2025 primarily attributable to the manufacturing of a batch that did not meet our specifications.

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Research and Development Expenses

The following table summarizes our research and development expenses for our major development programs for the years ended December 31, 2025 and 2024:

Year Ended December 31,

(1) Excludes share-based compensation expense.

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

We expect our research and development expense to decrease for fiscal year 2026, as compared to 2025, primarily driven by an expected reduction in spending on discontinued programs and our preclinical product candidates and research pipeline as a result of the 2025 Restructuring, as well as reduced spend on ZYNLONTA due to the timing, progress and stage of clinical trials. Thereafter, our research and development expense may fluctuate from period to period based on a number of factors, including the timing, progress and stage of clinical trials, costs associated with regulatory approval processes and manufacturing costs associated with commercialization activities prior to the receipt of regulatory approval.

Our R&D expenses were $104.0 million for the year ended December 31, 2025 as compared to $109.6 million for the year ended December 31, 2024, a decrease of $5.6 million, or 5.1%. The decrease in external costs and overhead of $6.9 million was driven primarily by a reduction in spending on discontinued programs, including ADCT-601 that was discontinued in November 2024, and our preclinical product candidates and research pipeline as a result of the 2025 Restructuring. These decreases were partially offset by an increase in spending on our PSMA-targeting ADC program due to the timing of costs incurred in connection with IND-enabling activities and an increase in ZYNLONTA spend due to the timing and enrollment of our ZYNLONTA clinical trials and related costs incurred in connection with the LOTIS 5 trials.

The increase in employee expenses of $0.6 million was primarily driven by higher temporary project help of $4.0 million, partially offset by lower wages and benefits of $3.4 million due to headcount reduction as a result of the 2025 Restructuring.The increase in share-based compensation expense of $0.7 million was primarily driven by the forfeitures of awards in connection with employee terminations in the prior year.

Selling and Marketing Expenses

The following table summarizes our selling and marketing expenses for the year ended December 31, 2025 and 2024:

Year Ended December 31,

(1)Excludes share-based compensation expense.

Selling and marketing costs (“S&M”) are expensed as incurred and are primarily attributable to commercialization of ZYNLONTA in the United States. S&M includes employee costs and share-based compensation expense for commercial

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employees and external costs related to commercialization (including professional fees, communication costs and IT costs, travel expenses and depreciation of property and equipment).

Selling and marketing expenses were $43.4 million for the year ended December 31, 2025 as compared to $44.0 million for the year ended December 31, 2024, a decrease of $0.6 million, or 1.5%. The decrease in external costs and overhead was primarily attributable to $2.0 million in lower spend on marketing and advertising expenses as a result of reduced spending initiatives within the U.S. The increase in employee expenses was primarily due to an increase in wages and benefits of $0.3 million. The increase in share-based compensation expense of $1.0 million was primarily driven by the forfeitures of awards in connection with employee terminations in the prior year.

General and Administrative Expenses

The following table summarizes our general and administrative expenses for the year ended December 31, 2025 and 2024:

Year Ended December 31,

(1)Excludes share-based compensation expense.

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

General and administrative expenses were $36.6 million for the year ended December 31, 2025 as compared to $41.9 million for the year ended December 31, 2024, an overall decrease of $5.3 million, or 12.7%. The decrease in external costs and overhead was primarily related to lower professional fees of $2.1 million primarily as a result of lower legal and accounting expenses, VAT recoveries of $0.5 million, lower insurance costs of $0.7 million and lower travel and IT costs of $0.5 million. The decrease in employee expenses of $0.6 million was primarily due to lower wages and benefits of $0.4 million and lower recruitment costs of $0.4 million, partially offset by $0.2 million in higher temporary project help. The decrease in share-based compensation expense of $1.0 million was primarily due to the timing of forfeitures of awards in connection with employee terminations.

Restructuring, Impairment and Other Related Costs

In connection with the 2025 Restructuring, we incurred Restructuring, impairment, and other related costs of $13.1 million for the year ended December 31, 2025, which consisted of $6.0 million in employee severance and related benefit costs, the majority of which were paid by the end of 2025, $5.8 million in impairment of long-lived assets and prepaid expenses, and $1.3 million in legal fees, dilapidations, lease termination and other related costs associated with the UK facility closure. We did not incur restructuring, impairment and other related costs for the year ended December 31, 2024.

Other Income (Expense)

Interest Income

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

Interest income was $8.8 million for the year ended December 31, 2025 as compared to $12.3 million for the year ended December 31, 2024, a decrease of $3.5 million, or 28.2%. The decrease was primarily due to lower yields received on our cash deposits and cash equivalents and lower average balances.

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Interest Expense

Interest expense is primarily related to the accretion of our deferred royalty obligation to HCR and the senior secured term loan facility. Interest expense was $51.6 million for the year ended December 31, 2025 as compared to $50.2 million for the year ended December 31, 2024, an increase of $1.4 million, or 2.8%. This was due to higher accretion of our deferred royalty obligation with HCR of $1.7 million as a result of higher total revenue, net, partially offset by lower interest on our senior secured term loan facility of $0.3 million as a result of a lower effective interest rate.

Other, net

Other, net consists primarily of cumulative catch-up adjustments related to our deferred royalty obligation and the R&D tax credit from our UK operations. Other, net as of December 31, 2025 and 2024 included the following:

Year Ended December 31,

Deerfield warrant obligation, change in fair value income — 296 (296)

Exchange differences loss (670) (80) (590)

Cumulative catch-up adjustment income, deferred royalty obligation

We periodically assess the expected payments to HCR based on our underlying revenue projections and to the extent the amount or timing of such payments is materially different than our initial estimates we will record a cumulative catch-up adjustment to the deferred royalty obligation. The adjustment to the carrying amount is recognized in Other, net as an adjustment in the period in which the change in estimate occurred. The cumulative catch-up adjustment income was $22.2 million for the year ended December 31, 2025 as compared to $11.2 million for the year ended December 31, 2024, a change of $11.0 million. The change was primarily due to revised revenue forecasts incorporated into the valuation model in 2025 having a greater effect on the expected payments to HCR relative to the 2024 revised revenue forecasts. Revisions in both years were primarily attributable to changes in assumptions in the Company’s updated strategic and development plans, revenue projections and associated timing thereof.

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Income Tax Expense

We are subject to corporate income taxation in Switzerland and in other jurisdictions in which we operate, including the United States and the United Kingdom, where our two wholly-owned subsidiaries are incorporated. Under Swiss law, we are permitted to carry forward net operating losses for up to seven years, which may be used to offset future taxable income. Under U.S. tax law, research and development tax credits may generally be carried forward for up to 20 years and used to offset future tax liabilities, subject to statutory requirements.

We recorded an income tax expense of $1.0 million for the year ended December 31, 2025 as compared to $0.2 million for the year ended December 31, 2024, primarily driven by our U.S. and U.K. operations and the full valuation allowance recognized on our deferred tax assets.

Income tax expense associated with our U.S. and UK operations was $1.0 million for the year ended December 31, 2025, consisting primarily of $1.2 million of current‐period UK income tax expense, partially offset by a $0.2 million benefit resulting from true‐ups of prior‐year U.S. and UK income tax returns. Current income tax expense is primarily attributable to intercompany service arrangements under which our Swiss parent company reimburses its UK subsidiary, as well as restructuring‐related tax adjustments. No current or deferred income tax expense was recorded for our U.S. operations for the year ended December 31, 2025, primarily due to the deductibility of domestic research and development expenditures under OBBB legislation and the existence of a full valuation allowance on U.S. deferred tax assets.

Equity in Net Losses of Joint Venture

Year Ended December 31,

Share of Overland ADCT BioPharma net loss $ — $ (1,544) $ (1,544)

We recorded our proportionate share of Overland ADCT BioPharma’s net loss of $1.5 million for the year ended December 31, 2024. We recorded our share of Overland ADCT BioPharma’s net loss up until the point at which our share of losses exceeded our interest in Overland ADCT BioPharma. Losses were not recognized in excess of our total investment, as we have not incurred legal or constructive obligations or committed to additional funding on behalf of the joint venture. As a result, we did not record losses for the year ended December 31, 2025.

Liquidity and Capital Resources

As of December 31, 2025, we had cash and cash equivalents of $261.3 million and believe that our current cash position and capital resources are sufficient to fund our operation and meet capital requirements for at least the next twelve months from the date of filing this Annual Report on Form 10-K.

We plan to continue to fund our operating needs through our existing cash and cash equivalents, revenues from sales of ZYNLONTA, potential milestone and royalty payments under our licensing agreements and additional equity financings, debt financings and/or other forms of financing, as well as potential funds provided by collaborations. We are continuously exploring strategic collaborations, business combinations, licensing opportunities or similar strategies for clinical development and commercialization of ZYNLONTA and/or our PSMA-targeting ADC. However, we may be unable to obtain such future financing, licensing and collaboration arrangements on favorable terms, if at all.

Sources of Liquidity and Capital Resources

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

On October 27, 2025, we completed a $60.0 million private placement which resulted in net proceeds of $57.6 million. In the private placement, we sold 11,250,00 common shares and pre-funded warrants (the “October 2025 Pre-Funded Warrants”) to purchase 3,846,153 common shares. The October 2025 Pre-Funded Warrants are exercisable, on a cash or cashless basis, at the option of the holder after the date of issuance until the tenth anniversary of their original issuance. At

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any time during the last 90 days of the term, the holder may exchange the October 2025 Pre-Funded Warrant for, and we will issue, a new pre-funded warrant for the number of common shares then remaining under the October 2025 Pre-Funded Warrant. The October 2025 Pre-Funded Warrants have certain limitations on exercise, including (i) any exercise must be for at least 50,000 common shares (or, if less, the remaining common shares available for purchase under the October 2025 Pre-Funded Warrants), (ii) a holder cannot exercise for any amount that would cause such holder’s beneficial ownership of our common shares to exceed 9.99% (or 19.99% with 61-days’ notice to us), and (iii) cashless exercise is not available in certain circumstances as specified in the October 2025 Pre-Funded Warrants. The warrants contain customary anti-dilution adjustments and will entitle holders to receive any dividends or other distributions paid on the underlying common shares prior to their expiration on an as-exercised basis.

On June 16, 2025, the Company completed a $100.0 million private placement which resulted in net proceeds of $93.1 million. In the private placement, we sold 13,031,161 common and pre-funded warrants (the “June 2025 Pre-Funded Warrants”) to purchase 15,734,267 common shares. The June 2025 Pre-Funded Warrants are exercisable, on a cash or cashless basis, at the option of the holder after the date of issuance until the tenth anniversary of their original issuance. At any time during the last 90 days of the term, the holder may exchange the June 2025 Pre-Funded Warrant for, and we will issue, a new pre-funded warrant for the number of common shares then remaining under the June 2025 Pre-Funded Warrant. The June 2025 Pre-Funded Warrants have certain limitations on exercise, including (i) any exercise must be for at least 50,000 common shares (or, if less, the remaining common shares available for purchase under the June 2025 Pre-Funded Warrants), (ii) a holder cannot exercise for any amount that would cause such holder’s beneficial ownership of our common shares to exceed 9.99% (or 19.99% with 61-days’ notice to us), and (iii) cashless exercise is not available in certain circumstances as specified in the June 2025 Pre-Funded Warrants. The warrants contain customary anti-dilution adjustments and will entitle holders to receive any dividends or other distributions paid on the underlying common shares prior to their expiration on an as-exercised basis.

Uses of Capital Resources

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

Contractual Obligations and Commitments

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

We have future royalty obligations to HCR, under our royalty purchase agreement, which royalty payment amounts and timing is dependent on the future sales results of ZYNLONTA. See Note 12, “Deferred royalty obligation”, included in the Notes to our audited consolidated financial statements for further information.

For information relating to our non-cancelable obligations under third party manufacturing agreements see Note 14, “Commitments and contingencies,” included in the Notes to our audited consolidated financial statements.

The Company has entered into certain collaborations with development partners, including in-licensing and manufacturing agreements. These agreements include potential future milestone and royalty payments that become payable only upon the achievement of specified development, regulatory, or commercial events. As of December 31, 2025, and 2024 we have not incurred any obligations under these arrangements, and we do not expect any material payments to become due unless and until such events occur. The aggregate amount of such potential milestone payments (excluding royalty payments), under

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all such collaboration agreements, was $59.6 million, including approximately $29.2 million contingent on the achievement of various research, development and regulatory approval milestones and approximately $30.4 million in sales-based milestones.

Cash Flows

The following table summarizes our cash flows for the years ended December 31, 2025 and 2024:

Year Ended December 31,

Net cash (used in) provided by:

Net Cash Used in Operating Activities

Net cash used in operating activities increased to $141.2 million for the year ended December 31, 2025 from $123.8 million for the year ended December 31, 2024, an increase of $17.3 million.

The increase was primarily due to the payment of the 2023 and 2024 discarded drug rebate of $14.4 million paid in 2025, a $5.7 million period over period decrease in partner collections, $4.6 million in severance payments as a result of the 2025 restructuring, a $4.0 million period over period decrease in interest income and a $4.0 million period over period increase in annual bonus and retention payments, partially offset by and the timing of other operating cash payments and receipts.

Net Cash provided by (used in) Investing Activities

Net cash provided by investing activities was $0.4 million for the year ended December 31, 2025. Net cash used in investing activities was $0.9 million for the year ended December 31, 2024. The decrease of $1.3 million is primarily due to $0.6 million in sales proceeds received in 2025 for the sale of all the UK laboratory equipment and remaining consumables, as well as the timing of payment for purchases of property and equipment.

Net Cash Provided by Financing Activities

Net cash provided by financing activities was $150.9 million for the year ended December 31, 2025 and primarily related to the net proceeds received from the completion of the Company’s June 2025 and October 2025 Private Placements. Net cash provided by financing activities was $97.1 million for the year ended December 31, 2024 and primarily related to the net proceeds received from the completion of the Company’s 2024 Equity Offering in May 2024.

Off-Balance Sheet Arrangements

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

Critical Accounting Estimates

A summary of the significant accounting policies is provided in Note 2 “Summary of significant accounting policies,” included in the notes to our audited consolidated financial statements.

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

We evaluate our estimates on an ongoing basis. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable under the circumstances, the results of which form our basis for making

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judgments about the carrying values of assets and liabilities and the reported amounts of revenues and expenses that are not readily apparent from other sources. Actual results may differ from those estimates under different assumptions and conditions.

Management considers an accounting estimate to be critical if:

•it requires a significant level of estimation uncertainty; and

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

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

Product revenues, net

We generate revenue from sales of ZYNLONTA in the U.S. for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. Revenue is recognized when control is transferred to the customer at the net selling price, which includes reductions for gross-to-net (“GTN”) sales adjustments such as government rebates, chargebacks, distributor service fees, other rebates and administrative fees, sales returns and allowances and sales discounts.

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

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 or packages to provide annual refunds (“discarded drug rebate”), if those portions of the dispensed drug that are unused and discarded exceed an applicable percentage defined by statute or regulation. The Centers for Medicare & Medicaid Services (the “CMS”) finalized regulations to implement this section on November 18, 2022, and the provision went into effect on January 1, 2023. In particular, the estimate for the discarded drug rebate requires a substantial degree of judgement.

The provision is recorded to Other current liabilities or Other long-term liabilities depending on when the annual refunds are expected to come due. The significant assumptions used to estimate the discarded drug rebate include legal interpretations of applicable laws and regulations, historical experience with discarded volumes and time lags in the processing of claims and invoicing from CMS. We use a number of factors to estimate the discarded drug rebate, including information from external sources to identify the Company’s discarded volumes and information from CMS on discarded volumes. We have now received from CMS the invoices for 2023 and 2024, the payments of which have been paid in 2025, and were generally consistent with our estimate and no significant prior period adjustments were made. We will continue to rely on projection methodologies and expect annual reports to be received from CMS. Given the annual nature of the proposed reporting schedule we will continue to estimate periodically discarded drug rebate liabilities.

Deferred royalty obligation

On August 25, 2021, we entered into a royalty purchase agreement with certain entities managed by Healthcare Royalty Partners (“HCR”). We accounted for the initial cash received as debt, less transaction costs and will subsequently account

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for the value of the debt at amortized cost. The amount received by us will be accreted to the total estimated royalty payments over the life of the agreement which will be recorded as interest expense. The carrying value of the debt will decrease for royalty payments made to HCR based on actual net sales and licensing revenue.

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

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

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

Recently Issued and Adopted Accounting Pronouncements

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

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

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

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Item 8. Financial Statements and Supplementary Data

INDEX TO AUDITED CONSOLIDATED FINANCIAL STATEMENTS

Audited Consolidated Financial Statements — ADC Therapeutics SA

Report of Independent Registered Public Accounting Firm (PCAOB ID 1358) 85

Consolidated Balance Sheets as of December 31, 2025 and 2024 88

Notes to the Consolidated Financial Statements 93

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Report of Independent Registered Public Accounting Firm

To theBoard 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, 2025 and 2024, and the related consolidated statements of operations, comprehensive loss, changes in shareholders’ (deficit) equity 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, 2025 and 2024, 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 consolidatedfinancial 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 consolidatedfinancial 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

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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 $333.6 million as of December 31, 2025.

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 or packages to provide annual refunds, if those portions of the dispensed drug that are unused and discarded exceed an applicable percentage defined by statute or regulation. The accrual for such rebate recognized within accrued expenses and other current liabilities was $8.0 million as of December 31, 2025. 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.

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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

Lausanne, Switzerland

March 10, 2026

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

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ADC Therapeutics SA

CONSOLIDATED BALANCE SHEETS

(in thousands, except share amounts)

As of December 31,

ASSETS

Current assets

Property and equipment, net — 5,075

Operating lease right-of-use assets 1,297 8,354

LIABILITIES AND SHAREHOLDERS’ (DEFICIT) EQUITY

Current liabilities

Accrued expenses and other current liabilities 57,988 62,440

Senior secured term loans, current portion 3,000 —

Operating lease liabilities, long-term 1,034 7,995

Commitments and contingencies (Note 14)

Shareholders’ (deficit) equity

Accumulated other comprehensive loss (517) (1,421)

Total liabilities and shareholders’ (deficit) equity $ 323,150 $ 321,980

The accompanying notes are an integral part of these consolidated financial statements.

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ADC Therapeutics SA

CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except share and per share amounts)

For the Years Ended December 31,

Revenue

License revenues and royalties 7,806 1,557

Operating expense

Restructuring, impairment and other related costs (13,120) —

Other income (expense)

Loss before equity in net losses of joint venture (142,623) (156,302)

Equity in net losses of joint venture — (1,544)

Net loss per share

Net loss per share, basic and diluted $ (1.12) $ (1.62)

The accompanying notes are an integral part of these consolidated financial statements.

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ADC Therapeutics SA

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS

(in thousands)

For the Years Ended December 31,

Other comprehensive (loss) income:

Remeasurement of defined benefit pension liability 33 (1,044)

Foreign currency translation adjustment 871 (185)

Share of other comprehensive loss in joint venture — (103)

Other comprehensive income (loss) 904 (1,332)

The accompanying notes are an integral part of these consolidated financial statements.

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ADC Therapeutics SA

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ (DEFICIT) EQUITY

Loss for the period — $ — $ — — $ — $ — $ (157,846) $ (157,846)

Other comprehensive loss — — — — — (1,332) — (1,332)

Share-based compensation expense — — 6,568 — — — — 6,568

Loss for the period — $ — $ — — $ — $ — $ (142,623) $ (142,623)

Other comprehensive income — — — — — 904 — 904

Share-based compensation expense — — 6,905 — — — — 6,905

The accompanying notes are an integral part of these consolidated financial statements.

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ADC Therapeutics SA

CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

For the Years Ended December 31,

Cash used in operating activities

Adjustments to reconcile net loss to net cash used in operations:

Share-based compensation expense 6,905 6,568

Accretion expense of deferred royalty obligation 29,132 28,224

Cumulative catch-up adjustment, deferred royalty obligation (22,212) (11,178)

Amortization of operating lease right-of-use assets 1,171 1,942

Share of results in joint venture — 1,544

Amortization of debt discount, senior secured term loan 1,820 902

Changes in operating assets and liabilities:

Prepaid expenses and other current assets 5,233 (1,480)

Other long-term assets (46) (456)

Accrued expenses and other current liabilities (7,420) 11,140

Operating lease liabilities (2,504) (1,958)

Other long-term liabilities (410) (6,925)

Cash flows used in investing activities

Payment for purchases of property and equipment (264) (867)

Proceeds from the sale of equipment 659 —

Net cash provided by (used in) investing activities 395 (867)

Cash flows provided by financing activities

Proceeds from sale of common shares, net of transaction costs 86,282 60,506

Proceeds from Pre-Funded Warrants, net of transaction costs 65,372 36,925

Proceeds from share issuance under stock purchase plan 271 558

Proceeds from the exercise of options 534 228

Taxes paid related to net settled equity awards (1,514) (1,163)

Net cash provided by financing activities 150,945 97,054

Net decrease in cash and cash equivalents 10,166 (27,648)

Exchange (losses)/gains on cash and cash equivalents 305 (83)

Cash and cash equivalents at beginning of year 250,867 278,598

Supplemental Cash Flow Information:

Payments made under royalty financing transaction 6,214 5,384

Supplemental Non-Cash Investing Activities:

The accompanying notes are an integral part of these consolidated financial statements.

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ADC Therapeutics SA

NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS

(in thousands, except per share amounts)

1.Description of Business and Organization

The Company generates sales from its flagship product, ZYNLONTA, which is currently approved in the U.S. for the treatment of relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”) after two or more lines of systemic therapy and has also been granted conditional approval from the European Commission, the China National Medical Products Administration and Health Canada. Additionally, the Company is pursuing label expansion into earlier lines of therapies and indolent lymphomas.

The Company was incorporated on June 6, 2011 under the laws of Switzerland, with its registered office located at Route de la Corniche 3B, 1066 Epalinges, Switzerland. The Company has two wholly-owned subsidiaries: ADC Therapeutics America, Inc. (“ADCT America”), which was incorporated in Delaware, USA on December 10, 2014 and ADC Therapeutics (UK) Ltd (“ADCT UK”), incorporated in England on December 12, 2014. The Company and its two subsidiaries form the ADCT Group (the “Group”). ADC Therapeutics (NL) B.V., previously a wholly-owned subsidiary of the Company, was dissolved effective October 4, 2024.

All references to “ADC Therapeutics,” “the Company", “we,” “us,” and “our” refer to ADC Therapeutics SA and its consolidated subsidiaries unless otherwise indicated.

2.Summary of Significant Accounting Policies

Basis of preparation and principles of consolidation

The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”) and include the accounts of the Company and its wholly-owned subsidiaries. Intercompany transactions and balances have been eliminated in consolidation.

Revision of Prior Period Financial Information

During the preparation of the consolidated financial statements for the year ended December 31, 2025, management identified and corrected an error in its prior period consolidated financial statements related to the classification of certain inventory balances between current and long-term assets. As a result, the Company revised its consolidated balance sheet for the year ended December 31, 2024 with a decrease to Inventory and Total current assets of $16.1 million, and a corresponding increase to Inventory, long-term. Management evaluated the materiality of the revision from a quantitative and qualitative perspective and concluded that the revision is immaterial to the consolidated financial statements. This reclassification revision had no impact on the Company’s total assets, as previously reported. The revision also had no impact on the consolidated statements of operations, comprehensive loss, stockholders’ (deficit) equity or cash flows. Additionally, the revision does not affect the Company’s compliance with any financial covenants.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures in the consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on assumptions believed to be reasonable under the circumstances. Actual results could differ materially from those estimates.

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Risks and Uncertainties

The Company is subject to risks and uncertainties common to companies in the global biotechnology and pharmaceutical industries, including, but not limited to, risks of failure or unsatisfactory results of its research and development efforts and clinical studies, the need for significant capital to fund the continued development of its products and pipeline, the need to obtain and maintain marketing approval for its products and product candidates, the need to successfully commercialize and gain market acceptance of any of its products and product candidates that obtain regulatory approval, dependence on strategic relationships with collaboration and commercialization partners and on key personnel, securing and protecting proprietary technology, compliance with government regulations, competition, and dependence on third-party service providers such as contract research organizations (“CROs”), contract manufacturing organizations (“CMOs”), other suppliers, and third-party logistics providers.

Concentrations of Risk

Foreign exchange risk

The Company operates internationally and is exposed to foreign exchange risk arising from various currency exposures, primarily with respect to British pounds, Euros and Swiss francs. Transaction exposure arises because the amount of local currency paid or received in transactions denominated in foreign currencies may vary due to changes in exchange rates. Foreign exchange risk arises from:

–forecast costs denominated in a currency other than the entity’s functional currency;

–recognized assets and liabilities denominated in a currency other than the entity's functional currency; and

–net investments in foreign operations.

Management believes that foreign exchange risk is minimal, as the Company pays invoices mainly in U.S. dollars and holds cash principally in U.S. dollars.

Interest rate risk

Interest rate risk arises from movements in interest rates which could have adverse effects on the Company's net loss or financial position. Changes in interest rates cause variations in interest income and expenses on interest-bearing assets and liabilities, and on the value of the net defined benefit pension obligation. In relation to the royalty purchase agreement with HCR, the Company is obligated to pay interest in the form of royalties in connection with certain net sales and licensing revenue. As the effective interest rate (“EIR”) on the deferred royalty obligation does not depend on market performance, the exposure to interest rate and market risk is deemed low. See Note 12, “Deferred royalty obligation” for further information. In regards to the senior secured term loans, the interest rate is variable and dependent upon market factors. The Company will update the EIR at the end of each reporting period for changes in the rate. See Note 10, "Senior secured term loan facility and warrants" for further information.

Credit risk

Credit risk is the risk that a counterparty will not meet its obligations under a financial instrument or customer contract, leading to a financial loss. The Company is exposed to credit risk from its operating activities and from its financing activities including deposits with banks and other financial institutions. The Company’s cash and cash equivalents accounts are maintained with well established, highly rated financial institutions. The Company’s wholly-owned subsidiaries are solvent, are managed on a cost-plus service provider basis, and are supported by the Company as the parent.

To date, the Company’s only source of product revenue, which commenced during May 2021, has been sales of ZYNLONTA only in the U.S., which is sold primarily through wholesale distributors. In addition, the Company earns license revenues and royalties through its license agreements with third parties. See Note 16 “Revenue” for further information. We continuously monitor the creditworthiness of our customers and have internal policies regarding

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customer credit limits. When determining customer allowances for estimated credit losses, the Company analyzes accounts that are past due, the creditworthiness of its customers, current economic conditions and actual credit losses incurred by the Company. As of December 31, 2025, and 2024, the Company did not record an allowance for expected credit losses as it was considered immaterial.

Liquidity risk

Liquidity risk is the risk that the Company may not be able to generate sufficient cash resources to settle its obligations in full as they fall due or can do so only on terms that are materially disadvantageous. Prudent liquidity risk management implies maintaining sufficient cash to cover working capital requirements. Cash is monitored by the Company’s management.

Funding and liquidity risks are reviewed regularly by management and the Board of Directors. The Board of Directors reviews the Company’s ongoing liquidity risks quarterly as part of the financial review process and on an ad hoc basis as necessary. To date, we have financed our operations primarily through equity financings, convertible debt and senior secured term loan financings, and additional funds provided by collaborations and royalty financings and sales of ZYNLONTA in the United States. The Company may need to raise additional capital to fund operations and execute on the Company’s business plan, and that such additional funds may not be available when the Company needs them or on terms that are acceptable to us.

Other Concentrations of Risk

We depend on single source suppliers for certain components of our inventory, and our production, warehousing and distribution operations are outsourced to third-party suppliers and CMOs where a significant portion of our inventory is located. Disruption of supply from key vendors or third-party suppliers may have a material adverse impact on our operations and financial results.

Our primary source of revenue is from sales of ZYNLONTA. Historically, we have not experienced significant credit losses on our accounts receivable and as of December 31, 2025 and 2024, allowances on receivables were not material. Three customers accounted for 100% and 98% of gross accounts receivable as of December 31, 2025, and 2024, respectively.

Foreign currency translation

Functional and presentation currency

Items included in the financial statements of each of the Company’s entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in US dollars (“$” or “USD”), which is the Company’s functional and Group’s reporting currency.

Transactions and balances

Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies are recognized within “Other, net” in the consolidated statements of operations.

Wholly-owned subsidiaries

The results and financial position of all the Company’s entities that have a functional currency different from the reporting currency are translated into the reporting currency as follows:

(i)assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet;

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(ii)income and expenses for each consolidated statement of operations are translated at monthly average exchange rates; and

(iii)all resulting exchange differences are recognized in other comprehensive loss, under “Foreign currency translation adjustment.”

Monetary assets and liabilities are translated at exchange rates in effect at the balance sheet date while non-monetary assets and liabilities are translated at historical exchange rates. Exchange gains and losses resulting from remeasurement adjustments are recorded within general and administration costs in the consolidated statements of operations.

Foreign currency exchange rates

The following exchange rates have been used for the translation of the financial statements of ADCT UK, the functional currency of which is the British pound:

Year ended December 31,

US $ / GBP

Cash and cash equivalents

Cash and cash equivalents include demand deposits held at financial institutions and other short-term highly liquid investments with original maturities of three months or less that are readily convertible to cash.

Fair value measurements

Financial assets and liabilities are required to be measured and reported at fair value at each reporting period. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, an exit price, in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value includes:

a.Level 1: quoted prices (unadjusted) in active markets for identical assets or liabilities;

b.Level 2: inputs other than quoted prices that are observable for the asset or liability, either directly (for example, as prices) or indirectly (for example, derived from prices);

c.Level 3: inputs for the asset or liability that are not based on observable market data.

Accounts receivable

Trade accounts receivable represent amounts due from customers from product sales and are stated net of customer sales allowances for chargebacks, product returns and estimated credit losses. The Company’s payment terms range from 30 to 90 days. When determining customer allowances for estimated credit losses, the Company analyzes accounts that are past due, the creditworthiness of its customers, current economic conditions and actual credit losses incurred by the Company. As of December 31, 2025, and 2024, the Company did not record an allowance for expected credit losses as it was considered immaterial.

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License revenue and royalties receivable, as well as other amounts due from the Company’s partners, are included in accounts receivable and are typically payable to us within 45 to 60 days after the end of each quarter in which they were earned.

Inventory

Inventory is stated at the lower of cost or net realizable value with costs determined on a first-in, first-out basis. Costs related to inventories that are not expected to be sold within the Company’s operating cycle of 12 months are classified as non-current assets and presented within Inventory, long-term in our consolidated balance sheets. Reserves for potentially excess, dated or obsolete inventories are established as a write-down to inventory and a charge to cost of product sales based on forecasted product demand estimates and the likelihood of consumption in the normal course of business, considering the expiration dates of the inventories on hand, planned production volumes and required production lead times.

Property and equipment

All property and equipment is stated at historical cost less accumulated depreciation. Historical cost includes expenditure that is directly attributable to the acquisition of the items.

Depreciation is calculated using the straight-line method to reduce the cost of each asset to its residual value over its estimated useful life, as follows:

Leasehold improvements 2 to 6 years

Office equipment 5 years

Hardware and computer software 3 years

Leases

The Company recognizes operating lease right-of-use (“ROU”) assets and operating lease liabilities when the Company obtains the right to control the asset under a leasing arrangement with an initial term greater than twelve months. The Company evaluates the nature of each lease at the inception of an arrangement to determine whether it is an operating or financing lease and recognizes the operating lease ROU asset and operating lease liability based on the present value of future minimum lease payments over the expected lease term. The lease payments are discounted using the interest rate implicit in the lease. If that rate cannot be determined, the Company uses the incremental borrowing rate we would expect to pay to borrow on a similar collateralized basis over a similar term in order to determine the present value of our lease payments. Operating lease ROU assets are comprised of the lease liability plus any lease payments made and excludes lease incentives. Certain lease arrangements contain renewal or termination options that have been included in the determination of the lease term if the options are reasonably certain of being exercised. For contracts that contain lease and non-lease components, the Company accounts for both components as a single lease component. Lease expense for operating leases is recognized on a straight-line basis over the lease term.

Investments in joint venture

The Company has an investment in a joint venture in which we own less than 50% and do not control the investee. The investment is accounted for using the equity method given our ability to exercise significant influence over the operating and financial decisions of the investee. The Company recognized its share of the investee’s profit or losses, other comprehensive income or losses and capital transactions as an adjustment to the carrying value of its investment in joint venture. The Company’s carrying value of its investment in a joint venture increases or decreases in relation to the Company’s proportionate share of comprehensive income or loss of the joint venture. When the Company’s share of losses of a joint venture exceeds the Company’s interest in that joint venture, the Company ceases to recognize its share of further losses. Additional losses are recognized only to the extent that the Company has incurred legal or constructive obligations or made payments on behalf of the joint venture. The Company’s Investment in joint venture

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is assessed for impairment when events or circumstances indicate the carrying value of the investment may be impaired based on qualitative factors.

Long-lived assets

The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If such circumstances are determined to exist, an estimate of undiscounted future cash flows produced by the long-lived asset, including its eventual residual value, is compared to the carrying value to determine whether impairment exists. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their estimated fair values.

On June 11, 2025, the Board of Directors approved the 2025 Restructuring, pursuant to which the Company closed down its UK facility, and has reduced its global workforce across functions by approximately 30%. As a result, the Company recognized $5.4 million of impairment losses on its long-lived asset group associated with the UK facility during the year-ended December 31, 2025.Subsequent to recording the impairment, on November 21, 2025, the Company entered into an equipment sales agreement for $0.7 million for all the laboratory equipment and remaining consumables. See Note 17 for further information regarding the restructuring and associated impairment of long-lived assets. There were no material impairment losses on long-lived assets for the year ended December 31, 2024.

Long-lived assets by geographic area are as follows:

(in thousands)

Loans

Loans are initially recognized at fair value, net of transaction costs incurred. Loans are subsequently measured at amortized cost using an effective interest rate (“EIR”). Loans are presented as a financial liability in the consolidated balance sheets. Debt is classified as a current liability when due within 12 months after the end of the reporting period. The remainder of the amount is presented as a long-term liability.

Warrants

The Company accounts for warrants as either equity-classified or liability-classified instruments based on an assessment of the warrant’s specific terms and applicable authoritative guidance included in Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 480, Distinguishing Liabilities from Equity (“ASC 480”), ASC 815, Derivatives and Hedging (“ASC 815”) and Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity (“ASU 2020-06”). The assessment considers whether the warrants are freestanding financial instruments pursuant to ASC 480, whether the warrants meet the definition of a liability pursuant to ASC 480, and whether the warrants meet all of the requirements for equity classification under ASC 815, including whether the warrants are indexed to the Company’s own common stock and whether the warrant holders could potentially require “net cash settlement” in a circumstance outside of the Company’s control, among other conditions for equity classification. This assessment, which requires the use of professional judgment, is conducted at the time of warrant issuance and as of each subsequent quarterly period end date while the warrants are outstanding. For warrants that are classified as liabilities, the Company records the fair value of the warrants at each balance sheet date and records changes in the estimated fair value as a gain or loss in Other, net.

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Employee benefits

Employee Pension Plans

The Company’s wholly-owned subsidiaries operate defined benefit and defined contribution pension plans in accordance with the local conditions and practices in the countries in which they operate. Certain employees of the UK subsidiary are covered by local defined contribution plans. The defined benefit schemes are generally funded through payments to insurance companies or trustee-administered funds, determined by periodic actuarial calculations. A defined contribution plan is a plan that provides an individual account for each participant and provides benefits that are based on all of the following: amounts contributed to the participant’s account by the employer or employee; investment experience; and any forfeitures allocated to the account, less any administrative expenses charged to the plan. A defined benefit plan is a pension plan that is not a defined contribution plan. Typically, defined benefit plans define an amount of pension benefit that an employee will receive on retirement, usually dependent on one or more factors such as age, years of service and compensation. However, as is the case with many Swiss pension plans, although the amount of ultimate pension benefit is not defined, certain legal obligations of the plan nevertheless create constructive obligations on the employer to pay further contributions to fund an eventual deficit. This results in the plan being accounted for as a defined benefit plan.

The liability recognized in the consolidated balance sheets in respect of defined benefit pension plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The defined benefit obligation is calculated annually by a third party using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity that approximate the terms of the related pension obligation.

The current service cost of the defined benefit plan is recognized in the consolidated statements of operations in employee benefit expenses, except where included in the cost of an asset, and reflects the increase in the defined benefit obligation resulting from employee service in the current year.

Past service costs, resulting from a plan amendment or curtailment, are recognized in Other comprehensive (loss) income and amortized to the consolidated statements of operations and comprehensive loss over the average remaining service period of active employees.

The net interest cost is calculated by applying the discount rate to the net balance of the present value of the defined benefit obligation and the fair value of plan assets. This cost is included in employee benefit expenses within research and development and general and administrative expenses in the consolidated statements of operations.

Actuarial gains and losses arising from experience adjustments and changes in actuarial assumptions are recognized in Other comprehensive (loss) income in the period in which they arise and amortized to the consolidated statements of operations and comprehensive loss in subsequent periods using the corridor approach.

For defined contribution plans, the company pays contributions to publicly or privately administered pension insurance plans on a mandatory, contractual or voluntary basis. Once the contributions have been paid, the company has no further payment obligations. The contributions are recognized as employee benefit expenses in the consolidated statements of operations. Prepaid contributions are recognized as an asset to the extent that a cash refund or a reduction in the future payments is available.

Share-based Compensation

The Company grants share-based awards. The fair value of awards expected to vest are recognized as an employee share-based compensation expense using the graded accelerated vesting method over the requisite service period of the award less actual forfeitures. The fair value of each stock option is estimated on the date of grant using the Black-Scholes option valuation model, that requires the use of assumptions including the expected volatility of the Company’s stock price, expected term, risk-free rate and the fair value of the underlying common stock. We estimate

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the fair value of restricted stock units granted based on the closing market price of our common stock on the date of grant. Actual forfeitures are recognized as they occur.

Employee Stock Purchase Plan

The fair value of purchase rights granted under the employee stock purchase plan is recognized as an employee share-based compensation expense with a corresponding increase in Additional paid-in capital. The total amount to be expensed is determined by reference to the fair value of the purchase rights granted.

The total expense is recognized over the offering period, which is the period over which all of the specified vesting conditions are to be satisfied. Participants that voluntarily withdraw from the plan are accounted for as a cancellation and total share-based compensation is recorded in the period in which the participant withdraws. Terminations are accounted for as forfeitures and any share-based compensation expense is reversed in the period the participant terminates. Accumulated payroll deductions are recorded within Accrued expenses in other current liabilities until the shares are purchased by the participant at the end of the offering period.

Revenue Recognition

The Company recognizes revenue when or as control of promised goods or services is transferred to its customers in an amount that reflects the consideration to which the Company expects to receive in exchange for those goods or services. The Company follows a five-step model: (i) identify the customer contract; (ii) identify the contract’s performance obligation; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations; and (v) recognize revenue when, or as, a performance obligation is satisfied.

Product revenue

The Company generates revenue from sales of ZYNLONTA in the U.S. for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. Revenue is recognized when control is transferred to the customer at the net selling price, which includes reductions for gross-to-net (“GTN”) sales adjustments such as government rebates, chargebacks, distributor service fees, other rebates and administrative fees, sales returns and allowances and sales discounts.

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

Discarded Drug Rebate

100

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The significant assumptions used to estimate the discarded drug rebate include legal interpretations of applicable laws and regulations, historical experience with discarded volumes and time lags in the processing of claims and invoicing from CMS. Management uses a number of factors to estimate the discarded drug rebate, including information from external sources to identify the Company’s discarded volumes and information from CMS on discarded volumes.

License arrangements

The Company recognizes revenues from license fees for intellectual property (IP) either at a point in time or over time. The Company must make an assessment as to whether such a license represents a right-to-use the IP (at a point in time) or a right to access the IP (over time). The Company recognizes revenue for a right-to-use license immediately if the licensee can begin to use and benefit from the IP upon commencement of the license term and the Company has no further obligations in the context of the IP. A license is considered a right to access the IP when the Company undertakes activities during the license term that may significantly affect the IP, which directly exposes the customer to any positive or negative effects arising from such activities. These activities do not result in the immediate transfer of a good or service to the customer. As such, revenues from the right to access the IP are recognized over time.

The Company may enter into agreements with multiple performance obligations. Performance obligations are identified and separated when the other party can benefit from the license on its own or together with other resources that are readily available, and the license is separately identifiable from other goods or services in the contract.

Transaction prices for out-license arrangements may include fixed up-front amounts as well as variable consideration such as contingent development and regulatory milestones, sales-based milestones and royalties. The most likely amount method is used to estimate contingent development and regulatory milestones because the ultimate outcomes are binary in nature. Variable consideration is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue will not occur when the uncertainty associated with the variable consideration is subsequently resolved. To the extent arrangements include multiple performance obligations that are distinct, the transaction price assigned to each distinct performance obligation is reflective of the relative stand-alone selling price when sold separately or estimated stand-alone selling price on the basis of comparable transactions with other customers when such goods or services are not sold separately. The residual approach is the method used to estimate a stand-alone selling price when the selling price for a good or service is highly variable or uncertain.

In determining the transaction prices for licenses of intellectual property only or when a license of intellectual property is the predominant item, both sales milestones and royalties are excluded from the variable consideration guidance and recognized at the later of when the subsequent sales transaction occurs, or the satisfaction or partial satisfaction of the performance obligation to which some or all of the royalty has been allocated.

Cost of product sales

Cost of product sales primarily includes direct and indirect costs relating to the manufacture of ZYNLONTA from third-party providers of manufacturing, distribution and logistics, and royalties to a collaboration partner based on net product sales of ZYNLONTA. Inventory amounts written down as a result of excess or obsolescence are charged to Cost of product sales.

Research and Development (“R&D”) expenses

R&D costs are expensed as incurred, and consist of salaries and benefits of employees, share-based compensation costs, fees paid to CROs and CMOs, upfront fees and achieved milestone payments associated with R&D collaboration arrangements, supplies, facilities costs and allocated overhead expenditures. Clinical study and certain research costs are recognized over the service periods specified in the contracts and adjusted as necessary based upon an ongoing review of the level of effort and costs actually incurred. The Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its R&D efforts. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and

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timing of services performed may vary, and will be assessed each period and adjusted as required to reflect amounts actually incurred. Research and development costs are presented net of reimbursements from development partners.

Restructuring Charges

On June 11, 2025, the Board of Directors approved the 2025 Restructuring, pursuant to which the Company closed down its UK facility, and has reduced its global workforce across functions by approximately 30%. Restructuring charges consist primarily of employee severance, contract termination costs and other costs. Liabilities for costs associated with a restructuring activity are recognized when the liability is incurred and are measured at fair value. For one-time employee terminations benefits, the Company recognizes the liability in full on the communication date when future services are not required or amortizes the liability ratably over the service period, if required. One-time termination benefits include severance, continuation of health insurance coverage for certain employees, and other company funded benefits. The Company evaluates and adjusts these costs as appropriate for changes in circumstances as additional information becomes available. See Note 17 for additional information regarding restructuring expenses.

Income taxes

Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be reversed. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is provided when it is more-likely-than-not that some portion or all of a deferred tax asset will not be realized. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized upon settlement. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. Interest and penalties related to an underpayment of income taxes are included in the income tax expense and classified with the related liability on the consolidated balance sheets. The uncertain tax position is presented as a reduction to a deferred tax asset for credit carryforward.

On July 4, 2025, the United States Congress enacted the budget reconciliation bill H.R. 1, referred to as the One Big Beautiful Bill (“OBBB”). The OBBB introduced several changes to corporate taxation, including modifications to the capitalization of research and development (R&D) expenses, limitations on deductions for interest expense, and accelerated depreciation for certain fixed assets. Under the OBBB, U.S. domestic R&D expenditures are now immediately deductible, while foreign R&D expenditures continue to be subject to capitalization and amortization. The Company has incorporated the impact of these provisions in its income tax accounting for the year ended December 31, 2025. The enactment of the OBBB did not have a material effect on the Company’s consolidated financial statements or overall tax position for the current year.

Loss per share

Basic loss per share is calculated by dividing the net loss attributable to shareholders by the weighted average number of common shares in issue during the year, excluding common shares owned by the Company and held as treasury shares.

Diluted loss per share adjusts the shares used in the determination of basic loss per share to take into account potentially dilutive common shares, if applicable, and the weighted average number of ordinary shares that would have been outstanding assuming the conversion of all potentially dilutive common shares (share option plans, employee stock purchase plan and outstanding warrants). The Company has incurred a loss for the years ended December 31, 2025 and 2024 and therefore potentially dilutive common shares have been excluded from the calculation of diluted loss per share because the effect would be anti-dilutive.

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Contingencies

From time to time, we may become involved in claims and other legal matters arising in the ordinary course of business. We record accruals for loss contingencies to the extent that we conclude that it is probable that a liability has been incurred and the amount of the related loss can be reasonably estimated. Legal fees and other expenses related to litigation are expensed as incurred and included in selling, general and administrative expenses.

Recent Accounting Pronouncements

New accounting pronouncements which have been adopted

We adopted FASB ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, effective for fiscal years beginning in January 2025, which requires the annual financial statements to include consistent categories and greater disaggregation of information in the rate reconciliation, and income taxes paid disaggregated by jurisdiction. We adopted the new guidance on a retrospective basis for the annual report for the fiscal year beginning on January 1, 2025. Adoption of this standard did not have a material impact on our financial statements, but resulted in expanded disclosures as included in Note 8, “Income taxes.”

Issued but not yet adopted

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses Disclosure. The ASU requires disaggregation, in the notes to the financial statements, of certain cost and expense captions presented on the face of the Company’s interim and annual financial statements. ASU 2023-09 is effective for fiscal years beginning in January 2027 and interim periods beginning January 2028, with early adoption permitted. Adoption may be applied prospectively or retrospectively. Early adoption is permitted. The Company does not anticipate that the adoption of this standard will have a material impact on our financial statements but may result in enhanced or expanded disclosures.

In July 2025, the FASB issued ASU 2025-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets to simplify the estimation of credit losses on current accounts receivable and current contract assets arising from transactions accounted for under ASC 606. The ASU provides a practical expedient permitting an entity to assume that conditions at the balance sheet date remain unchanged over the life of the asset when estimating expected credit losses for current classified accounts receivable and contract assets. The ASU is effective for fiscal years beginning in January 2026, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of the ASU, but does not anticipate the adoption of this standard to have a material impact on our financial statements.

In December 2025, the FASB issued ASU 2025-11, Interim Reporting (Topic 270): Narrow-Scope Improvements. The ASU clarifies interim disclosure requirements, the applicability of ASC 270 and the form and content of interim financial statements in accordance with U.S. GAAP. The objective of the amendments is to provide further clarity about the current interim disclosure requirements. The ASU is effective for interim reporting periods within fiscal years beginning in January 2028. Adoption of this ASU can be applied either a prospective or a retrospective approach. The Company is currently evaluating the impact of the ASU, but does not anticipate the adoption of this standard to have a material impact on our financial statements.

In December 2025, the FASB issued ASU 2025-12, Codification Improvements. The ASU addresses thirty-three items, representing the changes to the Codification that (1) clarify, (2) correct errors, or (3) make minor improvements. Generally, the amendments in this ASU are not intended to result in significant changes for most entities. The ASU is effective for interim reporting periods within annual reporting periods beginning in January 2027, with early adoption permitted. The adoption method of this ASU may vary, on an issue-by-issue basis. The Company is currently evaluating the impact of the ASU, but does not anticipate the adoption of this standard to have a material impact on our financial statements.

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3.Fair value measurements

The carrying amount of Cash and cash equivalents, Accounts Receivable, net and Accounts payable is a reasonable approximation of fair value due to the short-term nature of these assets and liabilities. Financial liabilities that are not measured at fair value on a recurring basis include our senior secured term loan and deferred royalty financing obligation. The carrying value of our senior secured term loan approximates fair value as these borrowings are based on variable market rates. The fair value of our deferred royalty obligation was $311.0 million and $312.0 million as of December 31, 2025 and 2024, respectively, and is based on our current estimates of future royalties expected to be paid over the estimated life of the royalty purchase agreement which are level 3 inputs.

The Deerfield warrants were measured at fair value on a recurring basis and were classified as Level 2. The warrants expired on May 19, 2025 in accordance with their terms and therefore, there were no warrants outstanding as of December 31, 2025. As of December 31, 2024 the value of the Deerfield warrants was $0. Fair values were estimated at the end of each reporting period with regard to the Deerfield warrants. The approach to valuation follows the fair value principle, and the key input factors are described for the Deerfield warrants in Note 11, "Deerfield warrants." A Black-Scholes model was used to calculate the fair values.

There were no transfers between the respective levels during the period.

4.Inventory

As of December 31, 2025 and 2024 inventory consisted of the following:

(1) Inventory expected to be sold beyond the Company’s 12-month operating cycle is classified as non-current inventory and recorded in Inventory, long-term.

(2) Reflects the correction related to the classification of certain inventory balances between current and long-term assets. See Note 2, “Summary of Significant Accounting Policies - Revision of Prior Period Financial Information.”

Inventory write-downs of $2,284 and $1,518 were recognized and charged to cost of product sales in the Company’s consolidated statements of operations for the years ended December 31, 2025 and 2024, respectively.

5.Property and equipment

Property and equipment as of December 31, 2025 and 2024 consisted of the following:

Leasehold improvements $ 225 $ 3,873

Laboratory equipment — 4,415

Hardware and computer software 970 1,137

Less: accumulated depreciation (1,381) (5,320)

Property and equipment, net $ — $ 5,075

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Depreciation expense for the years ended December 31, 2025 and 2024 was $705 and $1,334, respectively.

In connection with the 2025 Restructuring, the Company recorded impairment of property and equipment of $5.0 million during the year-ended December 31, 2025. Subsequent to recording the impairment, the Company entered into an equipment sales agreement for $0.6 million for all the laboratory equipment and remaining consumables. See Note 17 for further information regarding the restructuring and associated impairment of long-lived assets.

6.Leases

The Company leases space for its corporate offices and research and development facilities under non-cancellable operating leases.

As a result of the 2025 Restructuring, and in accordance with the UK facility lease agreement which allows for early termination upon notice and payment of breakage fees, the Company notified the landlord of its intention to terminate the lease. As a result, the associated lease liability and right-of-use asset were remeasured to $1.4 million and $0.4 million, respectively, reflecting the revised lease payments and term end date of January 28, 2026. The remeasurement resulted in a $6.8 million reduction to the lease liability and ROU asset.

The remaining ROU asset associated with the UK facility was assessed for impairment as part of the overall asset group. See Note 17 for further information regarding the restructuring and associated impairment of long-lived assets.

On May 15, 2025, the Company modified the terms of its existing lease for its office in New Jersey, USA. The existing lease contract was scheduled to expire on June 30, 2025. The Company extended the term of the lease by eighteen months commencing on July 1, 2025 and expiring on December 31, 2026. Accordingly, the Company remeasured its lease liability and adjusted its ROU asset based on the revised lease term.

During the third quarter of 2024, the Company modified the terms of its existing lease for its office in New Jersey, USA. The existing lease contract was scheduled to expire on November 30, 2024, including an extension option for three additional years, which at inception, the Company believed was reasonably likely to be exercised. The Company extended the term by seven months commencing on December 1, 2024 and removed the three-year extension option. Accordingly, the Company remeasured its lease liability and adjusted its ROU asset based on the revised lease term.

During the year ended December 31, 2025, the Company did not recognize any new right-of-use assets or lease liabilities, and therefore, non-cash operating lease ROU assets obtained in exchange for operating lease obligations was nil. Non-cash operating lease ROU assets obtained in exchange for operating lease obligations was $0.6 million million for the year ended December 31, 2024.

Lease costs for the years ended December 31, 2025 and 2024 are $1,171 and $1,942, respectively.

Maturities of lease liabilities are as follows:

Total lease payments 1,725

Less: imputed interest 152

Present value of lease liabilities $ 1,573

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Other supplemental information related to leases is summarized below:

As of December 31,

Weighted average remaining lease term (years) 6.0 6.3

Weighted average discount rate 3.3 % 4.6 %

7.Interest in joint venture

On December 14, 2020, the Company formed a new joint venture company, Overland ADCT BioPharma, with Overland Pharmaceuticals (“Overland”) to develop and commercialize ZYNLONTA, and three of the Company’s ADC product candidates, ADCT-601, ADCT-602 and ADCT-901 (collectively, the “Licensed Products”), in greater China and Singapore (the “Territory”). The Company agreed to supply product to Overland ADCT BioPharma for its drug development and commercialization under a supply agreement entered into between the parties.

Under the terms of the license agreement between the Company and Overland ADCT BioPharma, the Company licensed exclusive development and commercialization rights to the Licensed Products (the “Licensed IP”) in the Territory to Overland ADCT BioPharma. Overland invested $50.0 million in Overland ADCT BioPharma, and is obligated to pay the Company potential development milestone payments related to ADCT-601, ADCT-602 and ADCT-901, for a 51% equity interest. The Company received a 49% equity interest in exchange for contribution of the Licensed IP. The Company and Overland have appointed an equal number of nominees to the board of directors of Overland ADCT BioPharma which includes the Chief Executive Officer of Overland ADCT BioPharma. Pursuant to the license agreement, the Company may also earn low to mid-single digit royalties on net sales of the Licensed Products. In addition, Overland ADCT BioPharma elected to participate in the Company’s global clinical trials. The Company also received an option, which it may exercise at its sole discretion, to exchange any or all of its equity interest in Overland ADCT BioPharma into an equity interest in Overland upon an initial public offering of Overland. Given the uncertainty of an initial public offering of Overland, the Company did not assign any value to the option.

In connection with the formation of Overland ADCT BioPharma, the Company determined the fair value of its equity interest by implying a total equity value of Overland ADCT BioPharma using Overland’s investment of $50.0 million and the fair value of the contingent milestone consideration for Overland’s 51% equity interest. The fair value of the contingent consideration was determined to be nominal due to the high uncertainty related to achieving certain conditions associated with the contingent consideration as of the closing date.

The Company recognized the proportionate share of Overland ADCT BioPharma’s net loss up to the investment

carrying amount. The Company recorded its proportionate share of Overland ADCT BioPharma’s net loss of $1.6 million for the year ended December 31, 2024 which reduced the equity method investment in Overland ADCT Biopharma to zero. No further losses will be recorded in the Company's consolidated financial statements as the Company has not incurred legal or constructive obligations or committed to additional funding on behalf of the joint venture. The Company will begin recognizing its share of net income only when it is greater than the cumulative net losses not recognized during the period the equity method was suspended.

8.Income taxes

For the years ended December 31, 2025 and 2024, loss before taxes consists of the following:

Year Ended December 31,

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Income tax expense (benefit) attributable to income consists of:

(in thousands) Current Deferred

Switzerland — —

United Kingdom 1,303 —

US federal (150) —

US state (138) —

Switzerland $ — $ —

United Kingdom (148) —

US federal 140 —

Tax rate reconciliation

Income tax expense attributable to income was $1.0 million and $0.2 million for the years ended December 31, 2025 and 2024, respectively. The income tax expense differed from the amounts computed by applying the Swiss income tax rate of 7.83% for both periods to pretax income from continuing operations as a result of the following:

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For the years ended December 31,

(in thousands) Amount Percentage Amount Percentage

Federal

Cantonal Taxes

Foreign tax effects

United States

Adjustments for current tax of prior periods 1,036 (0.73) % (429) 0.27 %

United Kingdom

Statutory Income Tax Rate Differential 442 (0.31) % 441 (0.28) %

Adjustments for current tax of prior periods (2) — % (681) 0.44 %

Worldwide Change in Uncertain Tax Positions (712) 0.50 % 1,314 (0.84) %

In the table above, the Company used ADCT SA’s statutory tax rate as the starting point for the reconciliation since it is the parent entity of the business. The rate reconciliation begins with the statutory tax rate of the Company’s country of domicile, Switzerland. Effective tax rate varies from the statutory tax rate primarily due to valuation allowance recorded in the current losses in Switzerland and U.S. deferred tax assets.

Deferred tax assets

The income tax effect of each type of temporary difference comprising the net deferred tax asset as of December 31, 2025 and 2024 is as follows:

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Year ended December 31,

Deferred tax assets:

Net deferred tax assets $ 789 $ 1,912

Deferred tax liabilities:

Interest in joint venture — —

Other deferred tax liabilities (789) (1,912)

Total gross deferred tax liabilities (789) (1,912)

Net deferred tax liability $ (789) $ (1,912)

Total deferred tax $ — $ —

The valuation allowance at December 31, 2025 was primarily related to Swiss NOL, Federal R&D and Orphan Drug credits, Capitalized Research & Development, and Share Based Compensation that, in the judgment of management, may not be realized. The valuation allowance increased by $31.1 million in 2025. The change in valuation allowance from 2024 was related to increases in U.S. capitalized R&D, share-based compensation, orphan drug credit deferred tax assets and U.S. and Swiss NOL. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that all or some portion of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities (including the effect of available carryback and carryforward periods), projected future taxable income, and tax-planning strategies in making this assessment. In order to fully realize the deferred tax asset, the Company will need to generate significant future taxable income prior to the expiration of R&D credit carryforwards in 2045.

At December 31, 2025, the Company has R&D credit for federal and state income tax purposes of $42.9 million which are available to offset partial future federal taxable income, if any, through 2045. The Company has not recognized the entire R&D carryforward due to the reasons stated above.

As of December 31, 2025, the Company had net operating loss carryforwards of approximately $1,009 million for Swiss corporate income tax purposes and $19.3 million for U.S. corporate income tax purposes. The Swiss net operating loss carryforwards expire between 2026 to 2032. The U.S. net operating loss carryforwards do not expire; however,their utilization is subject to certain limitations. The Company has not recognized deferred tax assets related to these net operating loss carryforwards, as it is not considered more likely than not that such deferred tax asset will be realized, for the reasons stated above.

Uncertain tax positions

The Company recorded uncertain tax positions without interest and penalties of $6.8 million and $7.5 million as of December 31, 2025 and 2024, respectively. The increase of uncertain tax positions from tax year 2024 is related to current year positions. The uncertain tax position is recorded in the deduction of deferred tax assets.

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Decrease related to prior year tax positions (71) (1)

Increase related to current year tax positions 913 1,314

Settlements (785) —

Lapse of statute of limitations (769) (420)

The Company files income tax returns in Switzerland, United States, and United Kingdom. The Company remains subject to tax examinations in the following jurisdictions as of December 31, 2025:

Tax Year

Income taxes paid, net of refunds

For the years ended December 31, 2025 and December 31, 2024, the Company obtained income tax refunds, net of payments, totaling $0.1 million and $0.9 million, respectively. Cash taxes were paid (or refunded) across U.S. federal and various U.S. state jurisdictions, as shown below. Positive amounts represent tax payments, while amounts in parentheses represent tax refunds received.

Amount Payment (Refund)

U.S. federal $(6) $0

U.S. state — —

Illinois (19) —

Philadelphia (82) 5

Pennsylvania — (488)

Other States 5 19

Total Income Tax Paid (Refunded) $ (106) $ (945)

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9.Accrued expenses and other current liabilities

Accrued expenses and other current liabilities consist of the following:

Accrued restructuring costs 2,159 —

Gross-to-net sales adjustments, short-term 9,020 15,697

Operating lease liabilities, short-term 538 1,371

10.Senior secured term loan facility and warrants

On August 15, 2022, the Company, ADCT UK and ADCT America entered into the Loan Agreement, pursuant to which the Company could borrow up to $175.0 million principal amount of secured term loans, including (i) a First Tranche and (ii) Future Tranches. On August 15, 2022, the Company borrowed $120.0 million principal amount of term loans under the Loan Agreement. The secured term loans mature on August 15, 2029 and accrue interest at an annual rate ofsecured overnight financing rate (SOFR) plus 7.50% per annum (with respect to SOFR loans) or a base rate plus 6.50% per annum (with respect to alternative base rate ("ABR") loans) for the first five years of the term loans, and thereafter, at an annual rate of SOFR plus 9.25% (with respect to SOFR loans) or a base rate plus 8.25% (with respect to ABR loans), in each case subject to a 1.00% per annum SOFR floor. The secured term loans require the payment of interest only through June 30, 2026 and quarterly payments of principal, interest and exit fees thereafter until the maturity date of August 15, 2029. The Company has the option to elect for the loans to be either a SOFR loan or ABR loan and has elected the First Tranche of the secured term loan to be a SOFR loan. Interest is paid on the last business day of each quarter.

The Company is obligated to pay certain exit fees upon certain prepayments and repayments of the principal amount of the term loans in an amount ranging from zero to 4.0% of the amount of the loan so paid. In addition, the Company has the right to prepay the term loans at any time subject to certain prepayment premiums applicable until August 15, 2026. The Loan Agreement also contains certain prepayment provisions, including mandatory prepayments from the proceeds from certain asset sales, casualty events and from issuances or incurrences of debt, which may also be subject to prepayment premiums if made on or prior to August 15, 2026. The obligations under the Loan Agreement are secured by substantially all of the Company's assets and those of certain of the Company's subsidiaries and are guaranteed initially by the Company's subsidiaries in the U.S. and the UK. The Loan Agreement contains customary covenants, including a covenant to maintain a balance at the end of each quarter of at least $60.0 million in cash and cash equivalents plus an amount equal to any accounts payable that remain unpaid more than ninety days after the original invoice therefore, and negative covenants including limitations on indebtedness, liens, fundamental changes, asset sales, investments, dividends and other restricted payments and other matters customarily restricted in such agreements. In addition, the Loan Agreement contains a revenue covenant that, so long as the Company’s 30-day average market capitalization is less than $650 million, requires the Company achieve minimum levels of ZYNLONTA net sales in the United States, tested on a quarterly basis, which is subject to a customary cure right in favor of the Company that may be exercised by making certain prepayments and that, subject to certain limitations, may be exercised up to three times during the term of the Loan Agreement. The Loan Agreement also contains customary events of default, after which the term loan may become due and payable immediately, including payment defaults, material inaccuracy of representations and warranties, covenant defaults (including creation of any liens other than those that are expressly permitted), bankruptcy and insolvency proceedings, cross-defaults to certain other agreements, judgments against the Company and its subsidiaries and change in control.

On August 15, 2022, the Company also issued to the lenders under the Loan Agreement warrants to purchase an aggregate of 527,295 common shares, which warrants have an exercise price of $8.30 per share. Each warrant is exercisable, on a cash or a cashless basis, at the option of the holder at any time on or prior to August 15, 2032. The

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warrants contain customary anti-dilution adjustments and will entitle holders to receive any dividends or other distributions paid on the underlying common shares prior to their expiration on an as-exercised basis. On August 15, 2022, the Company also entered into the Share Purchase Agreement with the lenders under the Loan Agreement to purchase 733,568 common shares of the Company.

The Company has accounted for the First Tranche of the senior secured term loans, the warrants and the common shares described above eachas freestanding financial instruments.

The warrants are freestanding financial instruments that are indexed to the Company’s common stock and meet all other conditions for equity classification under ASC 480 and ASC 815.Accordingly, these warrants were recognized in equity and accounted for as a component of additional paid-in capital at the time of issuance.

The proceeds received were allocated to the loan, the warrants and the common shares based on the relative fair value method, resulting in a discount on the loan. The loan was recorded at $116.0 million on August 15, 2022. The loan is subsequently measured at its amortized cost. See further illustration of the allocation of proceeds in the table below:

(in thousands) Common shares Warrants Loan Total

Transaction costs were allocated to the loan, the warrants and the common shares based on the relative fair value method. Transaction costs associated to the warrants and common shares have been deducted from the respective instrument in equity, while transaction costs associated to the loan have been deducted from the loan and amortized using the effective interest method over the expected life of the loan. See further illustration of the allocation of transaction costs in table below:

(in thousands) Common shares Warrants Loan Total

As illustrated in the table above, the transaction costs of the loan (net of the transaction costs allocated to the warrant and common shares) were deducted from the loan to determine the carrying value as of August 15, 2022. The implied EIR that would be needed to increase the book value of the loan to cover all future expected outflows, taking into account the deduction of transaction costs from the initial loan balance, and based on a 360-day year for a SOFR loan, was computed at inception at 14.99%. Given the interest rate in the senior secured term loans is variable and dependent upon market factors, the Company will update the EIR at the end of each reporting period for changes in the rate. For the years ended December 31, 2025 and December 31, 2024, the Company recorded interest expense on the senior secured term loan in the amount of $16.3 million and $16.6 million, respectively, which was recorded in interest expense in the consolidated statements of operations. The EIR at December 31, 2025 was 15.86%.

The following table provides a summary of the interest expense for the Company’s senior secured term loan for the years ended December 31, 2025 and 2024:

Year ended December 31,

Amortization of debt discount 1,820 902

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The amount at which the senior secured term loan is presented as a liability in the consolidated balance sheets represents the net present value of all future cash outflows associated with the loan discounted at the EIR. The carrying value of the senior secured term loan is $115.5 million and $113.6 million as of December 31, 2025 and 2024, respectively. The Company will begin paying principal payments on the senior secured term loan in 2026, and accordingly $3.0 million of principal payments due in 2026 are classified as a current liability within the "Senior secured term loans, current portion” line item on the consolidated balance sheet as of December 31, 2025.

Contractual payments due under our senior secured term loans, including exit fees are as follows (in thousands):

11.Deerfield warrants

Pursuant to the Exchange Agreement with Deerfield entered into on August 15, 2022, the Company issued warrants to purchase an aggregate of 4,412,840 common shares. The warrants consisted of warrants to purchase an aggregate of 2,631,578 common shares at an exercise price of $24.70 per share and warrants to purchase an aggregate of 1,781,262 common shares at an exercise price of $28.07 per share. Each warrant was exercisable, on a cash or a cashless basis, at the option of the holder, at any time on or prior to May 19, 2025. The warrants contained customary anti-dilution adjustments and entitled holders to receive any dividends or other distributions paid on the underlying common shares prior to their expiration on an as-exercised basis. Each holder also may have required the Company to repurchase the warrants for their Black Scholes-based fair value in connection with certain transformative transactions or change of control of the Company that occur prior to their expiration.

These warrants had been recognized as a warrant obligation and presented in the consolidated balance sheets as a liability given the warrants may be settled through a cash or cashless exercise by the warrant holder. The liability was initially measured at fair value and was determined to approximate the fair value of the existing embedded conversion option features immediately prior to the consummation of the Exchange Agreement as the terms of the warrants are reflective of the terms of the embedded conversion option features of the Deerfield Facility Agreement prior to the Exchange Agreement. As such, the warrant obligation was recorded at an initial fair value of $12,297 on August 15, 2022. Subsequent to issuance, the warrant obligation was remeasured to fair value at the end of each reporting period. Changes in the fair value (gains or losses) of the warrant obligation at the end of each period was recorded in the consolidated statements of operations.

During the year ended December 31, 2025 and 2024, the Company recognized income of nil and $0.3 million, respectively, as a result of changes in the fair value of the warrant obligation. This amount was recorded to Other, net in the consolidated statements of operations. The warrants expired on May 19, 2025 in accordance with their terms and therefore, there were no warrants outstanding as of December 31, 2025. The fair value of the warrant obligation as of December 31, 2024 was nil. See Note 18, "Other income (expense)" for further information.

The Company calculated the fair value of the Deerfield warrant obligation, using the Black-Scholes option-pricing model. Key inputs for the valuation of the warrant obligation as of December 31, 2024 were as follows:

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Share price in $ 1.99

Risk-free interest rate 4.3 %

Expected volatility 83 %

Expected term (years) 0.39 years

Dividend yield —

Black-Scholes value in $ nil and nil

12.Deferred royalty obligation

On August 25, 2021, the Company entered into a royalty purchase agreement with certain entities managed by HCR for up to $325.0 million. Under the terms of the agreement, the Company received gross proceeds of $225.0 million upon closing (the “First Investment Amount”) and received an additional $75.0 million during the year ended December 31, 2023 upon the first commercial sale of ZYNLONTA in the United Kingdom or any European Union country (the “Second Investment Amount”) and together with the First Investment Amount, the “Investment Amount”). Under the agreement, the Company is obligated to pay to HCR (i) a 7% royalty on the worldwide (excluding China, Hong Kong, Macau, Taiwan, Singapore and South Korea) net sales of ZYNLONTA and any product that contains ZYNLONTA and on any upfront or milestone payments the Company receives from licenses that it grants to commercialize ZYNLONTA or any product that contains ZYNLONTA in any region other than China, Hong Kong, Macau, Taiwan, Singapore and South Korea, (ii) a 7% royalty on the worldwide net sales of Cami, a now-discontinued product candidate, and any product that contains Cami and on any upfront or milestone payments the Company receives from licenses that it grants to commercialize Cami or any product that contains Cami in the United States and Europe, and (iii) outside the United States and Europe, a 7% share of any upfront or milestone payments derived from licenses that the Company grants to commercialize Cami or any product that contains Cami and, in lieu of the royalty on net sales under such licenses, a mid-teen percentage share of the net royalty the Company receives from such licenses. The 7% royalty rates described above are subject to adjustment to a potential high-single-digit percentage royalty rate after September 30, 2026 and/or a 10% royalty rate after September 30, 2027, if the aggregate net sales and license revenue subject to royalty obligations in the preceding twelve months do not exceed certain mid-nine-digit milestones by such dates. The Company’s aggregate royalty obligations are capped at 2.50 times the amount paid by HCR under the agreement ($750.0 million as of December 31, 2025 and December 31, 2024), or at 2.25 times the amount paid by HCR under the agreement ($675.0 million as of December 31, 2025 and December 31, 2024) if HCR receives royalty payments exceeding a mid-nine-digit amount on or prior to March 31, 2029 (the “Royalty Cap”). Once the Royalty Cap is reached, the royalty purchase agreement will terminate.

Upon the occurrence of a change in control event, the Company is obligated to pay HCR an amount equal to the Royalty Cap, less any amounts the Company previously paid to HCR. On February 18, 2026, the Company and HCR amended the payments in a change in control event. See Note 22 – Subsequent Events. During the year ended December 31, 2021, the Company received gross proceeds of $225.0 million before deducting transaction costs of $7.0 million, all of which were paid during 2021, which resulted in net proceeds of $218.0 million. During the year ended December 31, 2023 the Company received an additional $75.0 million upon the first commercial sale of ZYNLONTA in the United Kingdom or any European Union country, which resulted in net proceeds of $73.1 million, net of transaction costs of $1.9 million.

The table below provides a rollforward of the Company’s debt obligation relating to the royalty purchase agreement.

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(in thousands)

Less: royalty payments 5,384

Plus: interest expense 33,608

Less: cumulative catch-up adjustment, Other, net 11,178

Less: royalty payments 6,214

ADCT US Equity

ADCT · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

ADCT US Equity☆

ADCT · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

ADCT US Equity