ADC Therapeutics SA

Table of Contents

ADC Therapeutics SA

NOTES TO THE CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

(in thousands, except per share amounts)

1. Description of Business and Organization

ADC Therapeutics is a commercial-stage global leader and pioneer in the field of antibody drug conjugates (“ADCs”), transforming treatment for patients through our focused portfolio with ZYNLONTA® (loncastuximab tesirine-lpyl) and an early stage prostate-specific membrane antigen targeting ADC (“PSMA-targeting ADC”).

The Company generates sales from its flagship product, ZYNLONTA, which was granted accelerated approval by the Food and Drug Administration (“FDA”) in the U.S. for the treatment of relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”) in the 3L setting and has also been granted conditional approval from the European Commission, conditional approval from the China National Medical Products Administration and conditional approval by Health Canada. Beyond ZYNLONTA, ADC Therapeutics is leveraging its expertise to advance IND-enabling activities for a next-generation PSMA-targeting ADC which utilizes a differentiated exatecan-based payload with a novel hydrophilic linker.

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 hastwo 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 itstwo subsidiaries form the ADCT Group (the “Group”).

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

These accompanying unaudited condensed consolidated financial statements, which include the accounts of the Company and its wholly-owned subsidiaries, have been prepared following the requirements of the U.S. Securities and Exchange Commission for interim reporting. As permitted under those rules, certain footnotes and other financial information that are normally required by U.S. generally accepted accounting principles, or U.S. GAAP, can be condensed or omitted. All intercompany transactions and balances have been eliminated in consolidation. The information included in this Quarterly Report on Form 10‑Q should be read in conjunction with our annual audited consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10‑K for the year ended December 31, 2024.

In the opinion of management, these condensed consolidated financial statements have been prepared on the same basis as the annual audited consolidated financial statements and include all adjustments, consisting only of normal recurring adjustments, considered necessary for the fair statement of our financial position and operating results. The results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2025, for any other interim period or for any future period.

The Company’s significant accounting policies have not changed substantially from those previously described in the Company’s Annual Report on Form 10‑K for the year ended December 31, 2024.

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.

Restructuring Charges

On June 11, 2025, the Board of Directors approved a strategic reprioritization and restructuring plan (the “2025 Restructuring”), pursuant to which the Company is in the process of shutting 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 15 for additional information regarding restructuring expenses.

Impairment of 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.

As a result of the 2025 Restructuring, the Company recognized $5.4 million of impairment losses on its long-lived asset group associated with the UK facility during the second quarter of 2025. See Note 15 for further information regarding the restructuring and associated impairment of long-lived assets.

Long-lived assets by geographic area are as follows:

Income taxes

On July 4, 2025, the United States Congress passed budget reconciliation bill H.R. 1 referred to as the One Big Beautiful Bill (“OBBB”). The OBBB contains several changes to corporate taxation including modifications to capitalization of research and development expenses, limitations on deductions for interest expense and accelerated fixed asset depreciation. Under the OBBB, U.S. domestic R&D expenditures are now immediately deductible, while foreign R&D expenditures remain subject to capitalization and amortization. The Company has reflected the impact of these provisions in its estimated annual effective tax rate for the third quarter of 2025. Management does not expect the OBBB to have a material effect on the Company’s overall tax position for the current year.

Recent Accounting Pronouncements

Issued but not yet adopted

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. The ASU 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. ASU 2023-09 is effective for the Company’s annual reporting periods beginning in January 2025. Adoption is either with a prospective method or a fully retrospective method of transition. Early adoption is permitted. The Company is currently evaluating the effect that adoption of ASU 2023-09 will have on its consolidated financial statements. 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 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. The Company is currently evaluating the effect that adoption of ASU 2024-03 will have on its consolidated financial statements.

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 carrying value of our deferred royalty obligation approximates fair value as the loan is recorded using the amortized cost method and considers our current estimates of future royalties expected to be paid over the estimated life of the royalty purchase agreement which are level 3 inputs, adjusted for accretion and royalty payments made by the Company during the nine months ended September 30, 2025. The carrying value of the liability is updated periodically for material changes to the expected payments to HCR based on its underlying revenue projections.

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 September 30, 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 9, "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 September 30, 2025 and December 31, 2024 inventory consisted of the following:

Inventory write-downs of $237 and $1,873 were recognized for the three and nine months ended September 30, 2025, respectively, andnil and $1,036 were recognized for the three and nine months ended September 30, 2024, respectively, and charged to cost of product sales in the Company’s unaudited condensed consolidated statements of operations.

5. Property and equipment

Property and equipment as of September 30, 2025 and December 31, 2024 consisted of the following:

Depreciation expense wasnil and $705 for the three and nine months ended September 30, 2025, respectively, and $336 and $993 for the three and nine months ended September 30, 2024, respectively.

In connection with the 2025 Restructuring, the Company recorded impairment of property and equipment of $5.0 million during the second quarter of 2025,related to leasehold improvements, lab equipment and furniture and fixtures located at the UK facility. See Note 15 for further information regarding the restructuring and associated impairment of long-lived assets. There wereno impairments of property and equipment recorded during the three and nine months ended September 30, 2024.

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 right-of-use asset as of September 30, 2025.

The remaining right-of-use asset associated with the UK facility was assessed for impairment as part of the overall asset group. See Note 15 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 right-of-use asset based on the revised lease term.

Maturities of lease liabilities are as follows:

Other supplemental information related to leases is summarized below:

7. Accrued expenses and other current liabilities

Accrued expenses and other current liabilities consist of the following:

8. Senior secured term loan facility

On August 15, 2022, the Company, ADCT UK and ADCT America entered into the Loan Agreement, pursuant to which the Company may 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 drew down $120.0 million principal amount of term loans under the Loan Agreement.

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 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 are recognized in equity and accounted for as a component of additional paid-in capital at the time of issuance.

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.

For the three and nine months ended September 30, 2025, the Company recorded interest expense on the senior secured term loan in the amount of $4,396 and $12,455, respectively, and $4,585 and $13,401 for the three and nine months ended September 30, 2024, respectively, which was recorded in interest expense in the unaudited condensed consolidated statements of operations. The effective interest rate (“EIR”) at September 30, 2025 was 16.01%.

The following table provides a summary of the interest expense for the Company’s senior secured term loan for the three and nine months ended September 30, 2025 and 2024:

The amount at which the senior secured term loan is presented as a liability in the unaudited condensed 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 $115.2 million and $113.6 million as of September 30, 2025 and December 31, 2024, respectively.

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

9. 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 warrant obligation, which was included in other long-term liabilities in the unaudited condensed consolidated balance sheets, was remeasured to fair value at the end of each reporting period. Changes in the fair value losses of the warrant obligation at the end of each period were recorded in the unaudited condensed consolidated statements of operations.

During the three and nine months ended September 30, 2025, the Company didnot recognize any expense or income as a result of changes in the fair value of the warrant obligation. For the three and nine months ended September 30, 2024, the Company recognized income of $1.1 million and $0.3 million, respectively. This amount was recorded to Other, net in the unaudited condensed 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 September 30, 2025. The fair value of the warrant obligation as of December 31, 2024 was $0. See Note 16, "Other income (expense)" for further information.

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

10. 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”).

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

11. Pension and post-retirement benefit obligations

The pension plan for Swiss employees is a defined benefit pension plan. The Company contracted with the Swiss Life Collective BVG Foundation based in Zurich for the provision of occupational benefits. All benefits in accordance with the regulations are reinsured in their entirety with Swiss Life SA within the framework of the corresponding contract. This pension solution fully reinsures the risks of disability, death and longevity with Swiss Life. Swiss Life invests the vested pension capital and provides a 100% capital and interest guarantee. The pension plan is entitled to an annual bonus from Swiss Life comprising the effective savings, risk and cost results.

Although, as is the case with many Swiss pension plans, the amount of ultimate pension benefit is not defined, certain legal obligations of the plan create constructive obligations on the employer to pay further contributions to fund an eventual deficit; this results in the plan nevertheless being accounted for as a defined benefit plan.

The net periodic benefit cost for the three and nine months ended September 30, 2025 and 2024 is as follows:

The components of net periodic benefit cost are included in operating expense on the unaudited condensed consolidated statements of operations.

12. Commitments and contingencies

Manufacturing Commitments

Some of our inventory components require long lead times to manufacture. Therefore, we make long-term investments in our supply chain in order to ensure we have enough drug product to meet current and future revenue forecasts. Third party manufacturing agreements include non-cancelable obligations related to the supply of ZYNLONTA and the company’s product candidates. There have been no material changes related to our non-cancelable obligations under these arrangements as disclosed in our Annual Report on Form 10-K for the year ended December 31, 2024.

Contingent liabilities

As a result of the 2025 Restructuring, and in accordance with the UK lease agreement, the Company notified the landlord of its intention to terminate the lease. In accordance with the lease terms, the landlord may require the Company to return the leased space to its original condition upon termination of the lease agreement, including the removal of the Company’s leasehold improvements. The Company continues to monitor negotiations with the landlord to determine the specific works to be removed, if any, and as of September 30, 2025, amounts are reasonably estimable and a liability of $0.8 million was recorded. See Note 15 for additional information regarding restructuring expenses.

From time to time, we may be involved in various legal matters generally incidental to our business. Although the results of litigation and claims cannot be predicted with certainty, after discussion with legal counsel, we are not aware of any matters for which the likelihood of a loss is probable and reasonably estimable and which could have a material impact on our consolidated financial condition, liquidity, or results of operations.

13. Shareholders’ equity

June 2025 Private Placement

On June 11, 2025, the Company entered into securities purchase agreements for the sale of its equity securities to certain institutional investors. In the private placement, the Company sold 13,031,161 common shares at $3.53 per share, which was the last reported sale price of the common shares on the New York Stock Exchange on June 11, 2025, and pre-funded warrants (the “June 2025 Pre-Funded Warrants”) to purchase 15,734,267 common shares at $3.43 per pre-funded warrant, which is the price per common share in the private placement minus the exercise price of CHF 0.08 per pre-funded warrant (collectively, the “June 2025 Private Placement”). The private placement closed on June 16, 2025. Gross proceeds from the June 2025 Private Placement were $100.0 million, and, after giving effect to $6.9 million of transaction costs related to the private placement, net proceeds were $93.1 million.

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.

Accounting for the June 2025 Private Placement and Pre-funded Warrants

The Company has accounted for the common shares and June 2025 Pre-funded Warrants described above each as freestanding financial instruments.

The common shares for the private placement were issued from the Company’s capital range. The common shares were recorded as $42.4 million to equity for the issuance of the common shares, net of transaction costs accrued and paid, and an increase in cash and cash equivalents.

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, including the warrant holders cannot require “net cash settlement” in a circumstance outside of the Company’s control, and there is sufficient authorized and unissued shares to settle the warrants. Accordingly, these warrants are recognized as $50.8 million in equity and accounted for as a component of additional paid-in capital at the time of issuance, net of transaction costs accrued and paid, and an increase in cash and cash equivalents.

Transaction costs have been allocated to 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.

14. Revenue

The table below provides a disaggregation of revenues by type and customer location for the three and nine months ended September 30, 2025 and 2024:

(1)Europe, the Middle East and Africa

Product revenues, net

The table below provides a rollforward of the Company’s accruals related to the gross-to-net (“GTN”) sales adjustments for the three and nine months ended September 30, 2025:

The table below provides a rollforward of the Company’s accruals related to the gross-to-net (“GTN”) sales adjustments for the three and nine months ended September 30, 2024:

The table below provides the classification of the accruals related to the GTN sales adjustment included in the Company’s unaudited condensed consolidated balance sheets as of September 30, 2025 and December 31, 2024.

Customers from which we derive more than 10% of our total product revenues for the three and nine months ended September 30, 2025 and 2024 are as follows:

(1)AmerisourceBergen also operates under the name Cencora.

License revenues

The Company is party to an exclusive license agreement with Sobi for the development and commercialization of ZYNLONTA for all hematologic and solid tumor indications outside of the U.S., greater China, Singapore and Japan. Under the terms of the agreement, the Company is eligible to receive regulatory and net sales-based milestones. In March 2025, the Company recognized $5.0 million in license revenue upon ZYNLONTA’s conditional approval by Health Canada for the treatment of relapsed or refractory DLBCL after two or more lines of systemic therapy. The payment was received in the second quarter of 2025.

15. Restructuring, impairment and other related costs

On June 11, 2025, the Board of Directors approved a strategic reprioritization and restructuring plan (the “2025 Restructuring”) to focus resources on ZYNLONTA® (loncastuximab tesirine-lpyl) expansion opportunities and the advancement of its PSMA-targeting ADC. The Company is discontinuing early development efforts for the remaining preclinical programs in solid tumors. In connection with the 2025 Restructuring, the Company is in the process of shutting down its UK research and development facility, and has reduced its global workforce across functions by approximately 30%.

In connection with the 2025 Restructuring, the Company reported the following costs in restructuring, impairment and other related costs:

Severance and benefit expense

Employees affected by the reduction in force under the 2025 Restructuring are entitled to receive severance payments, continuing healthcare benefits and other employee-related costs. Costs associated with one-time termination benefits were recorded pursuant to ASC 420, while costs associated with ongoing benefit arrangements were recorded pursuant to ASC 712. As a result, the Company recorded $6.2 million to Restructuring, impairment and other related costs in the Company’s unaudited condensed consolidated statements of operations during the nine months ended September 30, 2025, of which $3.4 million was paid as of September 30, 2025. The remaining $2.8 million not paid as of September 30, 2025 was accrued in Accrued expenses and other current liabilities in the Company’s unaudited condensed consolidated balance sheet and the Company expects to pay the remainder of the restructuring costs by the first quarter of 2026.

Impairment of long-lived assets and prepaid expenses and other related costs

As a result of the 2025 Restructuring, the Company recognized impairment losses of $6.4 million during the second quarter of 2025, which included $5.4 million recorded to the long-lived asset group associated with the UK facility and $1.0 million recorded to prepaid expenses in the UK. The long-lived asset group associated with the UK facility lease, included the right-of-use asset, leasehold improvements, lab equipment and furniture and fixtures. The $5.4 million recognized as impairment losses on the long-lived asset group were allocated to the various assets within the long-lived asset group based on their relative carrying values and consisted of $0.4 million recorded to right-of-use asset, $2.7 million recorded to leasehold improvements, $2.1 million recorded to lab equipment and $0.2 million recorded to furniture and fixtures.

Furthermore, as a result of the 2025 Restructuring, and in accordance with the UK facility lease agreement, the Company notified the landlord of its intention to terminate the lease. In accordance with the lease terms, the landlord may require the Company to return the leased space to its original condition upon termination of the lease agreement, including the removal of the Company’s leasehold improvements. The Company is in negotiations with the landlord to determine the specific works to be removed or restored, if any, and for the three and nine months ended September 30, 2025, amounts are reasonably estimable and a liability of $0.8 million was recorded.

16. Other income (expense)

The components of Interest expense for the three and nine months ended September 30, 2025 and 2024 are as follows:

Other, net

The components of Other, net for the three and nine months ended September 30, 2025 and 2024 are as follows:

17. Share-based compensation

The Company has adopted various share-based compensation incentive plans. Under these plans the Company may at its discretion grant to the plan participants, such as directors, certain employees, and service providers awards in the form of restricted shares and restricted share units (“RSUs”), share options, share appreciation rights, performance awards and other share-based awards. The 2019 Equity Incentive Plan was adopted in November 2019 while the Conditional Share Capital Plan and the Inducement Plan were adopted in December 2023.

2019 Equity Incentive Plan

In November 2019, the Company adopted the 2019 Equity Incentive Plan. Under the 2019 Equity Incentive Plan, the Company may at its discretion grant to plan participants, such as directors, certain employees and service providers, awards in the form of restricted shares and RSUs, share options, share appreciation rights, performance awards and other share-based awards. The Company has reserved 22,591,355 common shares for future issuance under the 2019 Equity Incentive Plan (including share-based equity awards granted to date less awards forfeited). As of September 30, 2025, the Company has 6,975,464 common shares available for the future issuance of share-based equity awards.

As of September 30, 2025 and December 31, 2024, the cumulative amount recorded as a net increase to additional paid-in capital within equity on the unaudited condensed consolidated balance sheets in respect of the 2019 Equity Incentive Plan was $164,690 and $160,945, respectively. The amounts of expense recognized for all awards for services received during the three and nine months ended September 30, 2025 were $1,116 and $3,996, respectively, and $1,541 and $1,408 during the three and nine months ended September 30, 2024, respectively.

Conditional Share Capital Plan

In December 2023, the Company adopted the Conditional Share Capital Plan. Under the Conditional Share Capital Plan, the Company may at its discretion grant to plan participants, such as directors, certain employees and service providers, awards in the form of restricted shares and RSUs, share options, share appreciation rights, performance awards and other share-based awards. The Company has reserved 8,000,000 common shares for future issuance under this plan. On February 13, 2025 the Company issued its 2025 annual equity award under the Conditional Share Capital Plan, which was approved by the Compensation Committee of the Board of Directors and by the Board of Directors for the senior management team, consisted of 5,015,765 RSUs. No share options were issued in connection with this award. As of September 30, 2025, the Company has 1,684,004 common shares available for the future issuance of share-based equity awards.

As of September 30, 2025 and December 31, 2024, the cumulative amount recorded as a net increase to additional paid-in capital within equity on the unaudited condensed consolidated balance sheet in respect of the Conditional Share Capital Plan was $4,893 and $2,964. The amounts of expense for all awards recognized for services received during the three and nine months ended September 30, 2025 were $699 and $1,929, respectively, and $970 and $3,008 during the three and nine months ended September 30, 2024, respectively.

Inducement Plan

In December 2023, the Company adopted the Inducement Plan. Under the Inducement Plan, the Company may at its discretion grant to any employee who is eligible to receive an employment inducement grant in accordance with NYSE Listed Company Manual 303A.08. The maximum number of common shares in respect of which awards may be granted under the Inducement Plan is 2,000,000 common shares (including share-based equity awards granted to date, less awards forfeited), subject to adjustment in the event of certain corporate transactions or events if necessary to prevent dilution or enlargement of the benefits made available under the plan. Equity incentive awards under the Inducement Plan may be granted in the form of options, share appreciation rights, restricted shares, restricted share units, performance awards or other share-based awards but not “incentive stock options” for purposes of U.S. tax laws. As of September 30, 2025, the Company has 1,087,943 common shares available for the future issuance of share-based equity awards under this plan.

As of September 30, 2025 and December 31, 2024, the cumulative amount recorded as a net increase to additional paid-in capital within equity on the unaudited condensed consolidated balance sheet in respect of the Inducement Plan was $1,111 and $554. The amounts of expense for all awards recognized for services received during the three and nine months ended September 30, 2025 were $184 and $557, respectively, and $232 and $327 during the three and nine months ended September 30, 2024.

Share Options

Pursuant to the 2019 Equity Incentive Plan, the Conditional Share Capital Plan and Inducement Plan (the “Share-based Compensation Plans”), the Company may grant share options to its directors, certain employees and service providers working for the benefit of the Company at the time. The exercise price per share option is set by the Company at the fair market value of the underlying common shares on the date of grant, as determined by the Company, which is generally the closing share price of the Company’s common shares traded on the NYSE. The awards generally vest 25% on the first anniversary of the date of grant, and thereafter evenly on a monthly basis over the subsequent three years. The contractual term of each share option award granted isten years. Under the grant, the options may be settled only in common shares of the Company. Therefore, the grants of share options under the 2019 Equity Incentive Plan and Inducement Plan have been accounted for as equity-settled under US GAAP. As such, the Company records a charge for the vested portion of award grants and for partially earned but non-vested portions of award grants. This results in a front-loaded charge to the Company’s unaudited condensed consolidated statements of operations and a corresponding increase to additional paid-in capital within equity on the unaudited condensed consolidated balance sheets.

The expense recognized for services received during the three and nine months ended September 30, 2025 were $531 and $2,114, respectively, and $1,386 and $641 during the three and nine months ended September 30, 2024, respectively.

Movements in the number of awards outstanding under the Plans described above and their related weighted average strike prices are as follows:

As of September 30, 2025,7,003,807 awards are vested and exercisable out of the total outstanding awards of 10,362,327 common shares. As of September 30, 2025, the weighted average strike price and weighted average remaining life for vested and exercisable awards is $10.83 and 6.27 years, respectively. Awards outstanding as of September 30, 2025 have expiration dates through 2035. The weighted average grant date fair value of the awards granted during the nine months ended September 30, 2025 was $2.21. The aggregate intrinsic value of vested and exercisable options was zero. As of September 30, 2025, the unrecognized compensation cost related to 3,358,520 unvested share options expected to vest was $4.3 million. This unrecognized cost will be recognized over an estimated weighted-average amortization period of 1.59 years.

The exercise price of stock options granted is equal to the closing price of the common stock on the date of grant. The fair values of the options granted under the 2019 Equity Incentive Plan and the Inducement Plan were estimated on the date of the grant using the Black-Scholes option-pricing model. Expected volatility is historical volatility of our common stock. The award life for options granted was based on the time interval between the date of grant and the date during the ten-year life after which, when making the grant, the Company expected on average that participants would exercise their options. The assumptions used were as follows:

RSUs

Pursuant to the Share-based Compensation Plans, the Company may grant RSUs to its directors, certain employees and service providers working for the benefit of the Company at the time. The awards generally vest annually over a period oftwo tothree years commencing on the first anniversary of the date of grant. The RSUs may be settled only in common shares of the Company. Therefore, the grant of RSUs under both the 2019 Equity Incentive Plan and Conditional Share Capital Plan have been accounted for as equity-settled under US GAAP. As such, the Company records a charge for the vested portion of award grants and for partially earned but non-vested portions of award grants. This results in a front-loaded charge to the Company’s unaudited condensed consolidated statements of operations and a corresponding increase to additional paid-in capital within equity on the unaudited condensed consolidated balance sheets. The expense recognized for services received during the three and nine months ended September 30, 2025 is $1,468 and $4,368, respectively, and $1,357 and $4,102 during the three and nine months ended September 30, 2024, respectively. An amount of $250 was withheld for tax withholding obligations during the nine months ended September 30, 2025.

The following table summarizes the RSU awards outstanding as of September 30, 2025:

(1)Includes 87,054 shares withheld to cover tax withholding obligations in connection with the vesting of RSUs previously granted.

The total fair value of RSU awards vested (as measured on the date of vesting) during the nine months ended September 30, 2025 was $1,364.

18. Loss per share

The basic loss per share is calculated by dividing the net loss attributable to shareholders by the weighted average number of shares in issue during the period, excluding common shares owned by the Company and held as treasury shares, as follows:

For the three and nine months ended September 30, 2025 and 2024, basic and diluted loss per share are calculated on the weighted average number of shares issued and outstanding and also include the June 2025 Pre-funded warrants issued in connection with the 2024 Equity Offering and the June 2025 Private Placement. The calculation excludes shares to be issued under the Share-based Compensation Plans, the Company’s Deerfield warrants and shares to be issued under the 2022 ESPP as the effect of including those shares would be anti-dilutive. See Note 8, “Senior secured term loan facility,” Note 9, “Deerfield warrants”, and Note 17, “Share-based compensation,” for further information.

Potentially dilutive securities that were not included in the diluted per share calculations because the effect of including them would be anti-dilutive were as follows:

19. Segment reporting

The Company is managed and operated asone reportable segment, which includes all global activities related to the development and commercialization of targeted ADC cancer therapies. The determination of a single reportable segment is consistent with the consolidated financial information regularly provided to the Company’s CODM, which is its chief executive officer. The CODM uses loss from operations and consolidated net loss for purposes of assessing performance, making operating decisions, allocating resources and planning and forecasting for future periods. The CODM allocates resources and plans for the long-term growth of the Company based on the Company's available cash resources, forecasted cash flow, and expenditures on a consolidated basis, as well as an assessment of the probability of success of its research and development activities. Resource allocation and long-term growth decisions are informed by budgeted and forecasted expense information, along with actual expenses incurred to date. The measure of segment assets is reported on the consolidated balance sheets as total assets.

The following table is the summary of the segment profit or loss information, including the significant expense categories for the three and nine months ended September 30, 2025 and 2024, respectively:

(1)Excludes share-based compensation.

(2)Includes Other expense, net, Income tax expense and Equity in net losses of joint venture.

20. Subsequent events

October 2025 Private Placement

On October 12, 2025, the Company entered into securities purchase agreements for the sale of its equity securities to certain institutional investors. In the private placement, the Company sold 11,250,000 common shares at $4.00 per share, and pre-funded warrants (the “October 2025 Pre-Funded Warrants”) to purchase 3,846,153 common shares at $3.90 per pre-funded warrant, which is the price per common share in the private placement minus the exercise price of CHF 0.08 per pre-funded warrant (collectively, the “October 2025 Private Placement”). The private placement closed on October 27, 2025. Gross proceeds from the October 2025 Private Placement were $60.0 million, and, after giving effect to $2.4 million of transaction costs related to the private placement, net proceeds were $57.6 million.

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 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.

Accounting for the October 2025 Private Placement and Pre-funded Warrants

The Company will account for the common shares and October 2025 Pre-funded Warrants described above each as freestanding financial instruments.

The common shares for the private placement were issued from the Company’s capital range. The common shares will be recorded as $43.0 million to equity for the issuance of the common shares, net of transaction costs accrued and paid, and an increase in cash and cash equivalents.

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, including the warrant holders cannot require “net cash settlement” in a circumstance outside of the Company’s control, and there is sufficient authorized and unissued shares to settle the warrants. Accordingly, these warrants will be recognized as $14.6 million in equity and accounted for as a component of additional paid-in capital at the time of issuance, net of transaction costs accrued and paid, and an increase in cash and cash equivalents.

Transaction costs will be allocated to the warrants and the common shares based on the relative fair value method. Transaction costs associated to the warrants and common shares will be deducted from the respective instrument in equity.