What changed in this filing

/stocks — the workspaceLOADING

Item 9A. Controls and Procedures

2026-02-23 compared with 2025-02-24 · 412 added, 587 removed, 913 unchanged (52% of the section changed)

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Evaluation of Disclosure Controls and Procedures

We have performed out an evaluation of the effectiveness of our disclosure controls and procedures under the supervision and the participation of the company’s management, including our Co-Chief Executive Officers (our Principal Executive Officers) and our Chief Operating Officer and Chief Financial Officer (our Principal Financial Officer).

We have performed an evaluation of the effectiveness of our disclosure controls and procedures under the supervision and the participation of the company’s management, including our Co-Chief Executive Officers (our Principal Executive Officers) and our Chief Operating Officer and Chief Financial Officer (our Principal Financial Officer).

The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms.

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Based on this assessment, management concluded that, as of December 31, 2025, our internal control over financial reporting is effective based on the COSO internal control criteria.

The effectiveness of the Company’s internal control over financial reporting as of December 31, 2024 has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in its report included in Item 15 of this Annual Report on Form 10-K.

The effectiveness of the Company’s internal control over financial reporting as of December 31, 2025 has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in its report included in Item 15, “Exhibits, Financial Statement Schedules” of this Annual Report on Form 10-K.

Changes in Internal Control Over Financial Reporting

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001-36866), filed with the Securities and Exchange Commission on January 10, 2019)

4.2 Form of Specimen Stock Certificate (incorporated by reference to Exhibit 4.2 to the Company ’ s Current Report on Form 8-K (File No.

001-36866), filed with the Securities and Exchange Commission on September 29, 2020)

Form of Consultant Warrant (incorporated by reference to Exhibit 4.2 to the Company’s Current Report on Form 8-K (File No.

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001-36866), filed with the Securities and Exchange Commission on November 6, 2020)

4.7 Form of Subscription Rights Certificate (incorporated by reference to Exhibit 4.1 to the Company’s Current Report on Form 8-K (File No.

001-36866), filed with the Securities and Exchange Commission on April 21, 2021)

2005 Enterprise Management Incentive Scheme (incorporated by reference to Exhibit 4.3 to the Company’s Transition Report on 20-F (File No.

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Form of Indemnification Agreement between Summit Therapeutics Inc.

and each of its Executive Officers and Directors (incorporated by reference to Exhibit 10.1 to the Company’s Current Report on Form 8-K (File No.

001-36866), filed with the Securities and Exchange Commission on September 18, 2020)

and each of its Executive Officers and Directors

2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.2 to the Company’s Current Report on Form 8-K (File No.

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Duggan (incorporated by reference to Exhibit 10.3 of Form 8-K filed by the Company on January 20, 2023, File No.

Amended and Restated 2020 Stock Incentive Plan, dated July 27, 2022 (incorporated by reference to Exh ibit 10.45 to the Company's Annual Report on Form 10-K (File No.

Amended and Restated 2020 Stock Incentive Plan, dated July 27, 2022 (incorporated by reference to Exhibit 10.45 to the Company's Annual Report on Form 10-K (File No.

001-36866), filed with the Securities and Exchange Commission on March 9, 2023)

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001-36866), filed with the Securities and Exchange Commission on March 9, 2023)

A mended Employment Agreement, dated October 31, 2023 by and between Summit Therapeutics Inc.

and Mahkam Zanganeh.

(incorporated by reference to Exhibit 10.1 to the Company's Quarterly Report on Form 10-Q (File No.

001-36866), filed with the Securities and Exchange Commission on May 1, 2024)

Employment Agreement, dated October 13, 2023, by and between Summit Therapeutics Inc.

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10.25 Securities Purchase Agreement, dated October 13, 2023, by and between Summit Therapeutics Inc.

and Manmeet Son i ( incorporated by reference to Exhibit 10.1 to the Company's Qua rterly Report on Form 10-Q (File No.

001-36866), filed with the Securities and Exchange Commi ssion on November 7, 2023)

and Manmeet Soni (incorporated by reference to Exhibit 10.1 to the Company's Quarterly Report on Form 10-Q (File No.

001-36866), filed with the Securities and Exchange Commission on November 7, 2023)

10.26 Amended and Restated Promissory Note, dated February 17, 2024, by and between Summit Therapeutics Inc.

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and its affiliates (incorporated by reference to Exhibit 10.3 to the Company’s Quarterly Report on Form 10-Q (File No.

001-36866), filed with the Sec urities and Exchange Commission on Aug ust 6, 202 4 .

001-36866), filed with the Securities and Exchange Commission on August 6, 2024.

Sublease, dated June 27, 2024, by and between Summit Therapeutics Inc.

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001-36866), filed with the Securities and Exchange Commission on September 12, 2024)

Sub-Sublease Agreement, dated June 2, 2025, by and between Summit Therapeutics Inc.

and Ascendis Pharma, Inc.

(incorporated by reference to Exhibit 10.1 of the Company’s Quarterly Report on Form 10-Q filed (File No.

001-36866), filed with the Securities and Exchange Commission on August 11, 2025)

10.38 Amendment to Distribution Agreement, dated August 11, 2025, by and between Summit Therapeutics Inc.

Morgan Securities LLC (incorporated by reference to Exhibit 1.2 of the Company’s Current Report on Form 8-K filed (File No.

001-36866), filed with the Securities and Exchange Commission on August 11, 2025)

Form of Securities Purchase Agreement by and between Summit Therapeutics Inc.

and certain Investors (incorporated by reference to Exhibit 1.1 of the Company’s Current Report on Form 8-K filed (File No.

001-36866), filed with the Securities and Exchange Commission on October 22, 2025)

Form of Registration Rights Agreement and between Summit Therapeutics Inc.

and certain Investors (incorporated by reference to Exhibit 1.2 of the Company’s Current Report on Form 8-K filed (File No.

001-36866), filed with the Securities and Exchange Commission on October 22, 2025)

Code of Business Conduct and Ethics of Summit Therapeutics Inc .

I nsider Trading Policy

19.1 Insider Trading Policy

21.1* List of Significant Subsidiaries

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* Filed herewith.

Furnished herewith.

† Portions of this exhibit have been omitted in compliance with Regulation S-K Item 601(b)(10)(iv) because the Registrant has determined that the information is not material and is the type that the Registrant treats as private or confidential.

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SUMMIT THERAPEUTICS INC.

Index to the Financial Statements

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Report of Independent Registered Public Accounting Firm (PCAOB ID:

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Consolidated Statements of Cash Flows

Notes to the Consolidated Financial Statements

Notes to Consolidated Financial Statements

Report of Independent Registered Public Accounting Firm

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A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company;

(ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the

expenditures of the company are being made only in accordance with authorizations of management and directors of the company;

and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

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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 matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Research and Development Prepaid Expenses and Accrued Liabilities

As described in Notes 4 and 14 to the consolidated financial statements, included within prepaid expenses and other assets as of December 31, 2024 is $8.3 million of prepayments relating to research and development expenditures.

Included within accrued liabilities as of December 31, 2024 is $17.4 million relating to research and development expenditures.

The Company records accruals for estimated ongoing research and development costs or prepaid expenses where the payments made exceed the estimated costs.

These amounts are determined by management based on the estimated costs to complete each study or activity, the estimation of the current stage of completion and the invoices received, as well as predetermined milestones which are not reflective of the current stage of development for prepaid expenses.

However, prepaid expenses decrease, and accrued liabilities increase as the activities progress, and if actual costs incurred exceed the prepaid expense, an accrual will be recorded for the liability.

The key sensitivity is the estimated current stage of completion of each study or activity, which is based on information received from the supplier and management’s operational knowledge of the work completed under those contracts.

The principal considerations for our determination that performing procedures relating to accrued and prepaid research and development costs is a critical audit matter are (i) the significant judgment by management when developing the estimated research and development costs and, (ii) a high degree of auditor judgment, subjectivity, and effort in performing procedures and evaluating audit evidence related to management’s significant assumptions related to the estimated current stage of completion of each study or activity.

External Research and Development Costs

The Company’s research and development expense for the year ended December 31, 2025 was $537.7 million, of which a portion relates to external research and development costs.

As described in Note 2 to the consolidated financial statements, research and development costs are expensed as incurred.

Research and development expenses consist of costs incurred to discover, research and develop product candidates, including third-party license fees and external costs of outside vendors engaged to conduct preclinical and clinical development activities and clinical trials as well as to manufacture clinical trial materials.

Management has entered into various research and development contracts with other companies.

These agreements are generally cancellable, and related payments are recorded as research and development expenses as incurred.

The principal consideration for our determination that performing procedures relating to external research and development costs is a critical audit matter is a high degree of auditor effort in performing procedures related to the Company’s external research and development costs.

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 testing the effectiveness of controls related to the accrued and prepaid research and development costs process, including controls over the development of estimated research and development costs.

These procedures also included, among others, (i) evaluating management’s process on a sample basis for determining the current stage of completion of each study or activity;

(ii) reading a sample of research and development contracts;

(iii) evaluating the reasonableness of progress towards completion for a sample of research and development activities and the associated incurred cost based on invoices, external confirmations or other information received from the supplier;

and (iv) testing the completeness and accuracy of the underlying data including total costs included within contracts and actual billed amounts for a sample of contracts.

These procedures included testing the effectiveness of controls related to the research and development costs process.

These procedures also included, among others, testing external research and development costs on a sample basis by (i) evaluating costs incurred to underlying agreements with outside vendors, invoices received, and underlying payments made for costs incurred on the contract;

and (ii) evaluating the classification as research and development costs.

/s/ PricewaterhouseCoopers LLP

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Prepaid expenses and other current assets 6,537 11,076

Research and development tax credit receivable 557 848

Total current assets 720,301 423,750

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Goodwill 2,001 1,864

Research and development tax credit receivable 698 959

Other assets 7,205 2,548

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Other non-current liabilities 1,832 1,630

Promissory note payable to a related party — 100,000

Total liabilities 92,322 46,812

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1,000,000,000 shares authorized;

737,626,004 and 701,660,053 shares issued and outstanding at

December 31, 2024 and 2023, respectively

775,371,200 and 737,626,004 shares issued and outstanding at December 31, 2025 and 2024, respectively

Additional paid-in capital 2,947,805 1,598,230

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2025 2024 2023

Revenue $ — $ — $ 705

Operating expenses:

Research and development (1)

$ 537,674 $ 150,777 $ 59,471

Acquired in-process research and development — 15,007 520,915

General and administrative 556,750 60,214 29,264

Impairment of intangible assets — — 8,468

Total operating expenses 1,094,424 225,998 609,650

Other operating income, net 313 1,001 14,416

Operating loss ( 225,998 ) ( 609,650 ) ( 72,089 )

Other income (expense), net 13,369 11,183 ( 2,292 )

Other income, net 14,838 13,369 11,183

Interest expense — ( 8,686 ) ( 16,461 )

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Foreign currency translation adjustments ( 327 ) 60 ( 172 )

Reclassification of unrealized loss on short-term investments to other expense, net 3 — —

Reclassification of cumulative currency translation gain to other

Reclassification of unrealized loss on short-term investments to other income, net — 3 —

Reclassification of cumulative currency translation gain to other income, net — — ( 419 )

Unrealized gain on short-term investments 72 100 36

Comprehensive loss $ ( 1,079,841 ) $ ( 221,152 ) $ ( 615,483 )

(1) Refer to Note 15 – Related Party Transactions for expenses incurred.

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

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Balance at December 31, 2022

2022 Rights Offering of common stock, net of offering costs of $ 111

211,091,425 $ 2,110 $ 504,767 $ ( 1,893 ) $ ( 378,330 ) $ 126,654

Issuance of common stock in lieu of interest to related parties 9,720,291 97 7,497 — — 7,594

Issuance of common stock under stock purchase plans and exercise of stock

options 238,811 2 397 — — 399

Stock-based compensation — — 11,948 — — 11,948

Imputed interest expense on promissory note payable to a related party — — 2,018 — — 2,018

Foreign currency translation adjustment — — — 304 — 304

Net loss — — — — ( 78,782 ) ( 78,782 )

Balance at December 31, 2022

211,091,425 $ 2,110 $ 504,767 $ ( 1,893 ) $ ( 378,330 ) $ 126,654

2023 Rights Offering of common stock, net of offering costs of $ 619 (2)

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Exercise of warrants (2)

Stock-based compensation — — 14,108 — — 14,108

Unrealized gain on short-term investments — — — 36 — 36

Reclassification of cumulative translation gain (Note 8)

805,495 8 1,195 — — 1,203

Foreign currency translation adjustment — — — ( 172 ) — ( 172 )

Stock-based compensation — — 14,108 — — 14,108

Net other comprehensive loss — — — ( 555 ) — ( 555 )

Net loss — — — — ( 614,928 ) ( 614,928 )

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Stock-based compensation — — 50,981 — — 50,981

Unrealized gain on short-term investments — — — 100 — 100

Reclassification of unrealized loss on short-term investments to other expense, net — — — 3 — 3

Foreign currency translation adjustment — — — 60 — 60

Net other comprehensive gain — — — 163 — 163

Net loss — — — — ( 221,315 ) ( 221,315 )

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737,626,004 $ 7,376 $ 1,598,230 $ ( 2,285 ) $ ( 1,214,573 ) $ 388,748

Private placement of common stock (2)

26,682,846 267 499,770 — — 500,037

Issuance of common stock under stock purchase plans and exercise of stock options and warrants 5,723,011 58 12,910 — — 12,968

Proceeds from at-the-market offering, net of commissions and offering costs of $ 1,969

5,339,339 53 104,475 — — 104,528

Stock-based compensation — — 732,420 — — 732,420

Net other comprehensive loss — — — ( 255 ) — ( 255 )

Net loss — — — — ( 1,079,586 ) ( 1,079,586 )

Balance at December 31, 2025

775,371,200 $ 7,754 $ 2,947,805 $ ( 2,540 ) $ ( 2,294,159 ) $ 658,860

(2) Refer to Note 13 – Stockholders’ Equity for related party transactions.

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

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Adjustments to reconcile net loss to net cash used in operating activities:

Gain on remeasurement of liabilities — — ( 1,265 )

Non-cash interest expense — — 6,253

— 6,253 4,303

Amortization of discount on short-term investments ( 7,006 ) ( 2,576 ) ( 1,924 )

( 2,576 ) ( 1,924 ) —

Unrealized foreign currency loss (gain)

229 ( 812 ) 2,616

Unrealized foreign exchange loss (gain) ( 320 ) 229 ( 812 )

Reclassification of currency translation gain — — ( 419 )

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Depreciation 146 89 198

Amortization of intangible assets — — 914

Impairment of intangible assets — — 8,468

Stock-based compensation 732,420 50,981 14,108

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Acquired in-process research and development expense — 15,007 520,915

15,007 520,915 —

Changes in operating assets and liabilities:

Accounts receivable — 359 975

Prepaid expenses and other current assets 4,866 ( 7,370 ) 3,613

( 7,905 ) ( 914 ) 5,107

2,470 ( 3,421 ) 215

Research and development tax credit receivable 535 4,168 8,437

Deferred revenue and other income — — ( 7,278 )

Other assets ( 4,875 ) 2,470 ( 3,421 )

Accounts payable 15,303 2,015 2,263

Accrued liabilities and other current liabilities 12,930 11,879 ( 2,377 )

11,879 ( 2,377 ) 4,782

Accrued compensation 2,909 6,557 ( 235 )

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Operating lease right-of-use assets and lease liabilities, net 203 ( 167 ) ( 359 )

( 167 ) ( 359 ) 152

Net cash used in operating activities ( 322,930 ) ( 142,106 ) ( 76,760 )

Cash flows used in investing activities:

Maturities and sales of short-term investments 311,340 489,837 208,165

Purchase of short-term investments ( 484,993 ) ( 680,032 ) ( 321,022 )

Purchase of property and equipment ( 657 ) ( 139 ) ( 128 )

( 139 ) ( 128 ) ( 624 )

Proceeds from sale of property, plant and equipment — — 226

Purchase of short-term investments ( 680,032 ) ( 321,022 ) —

Maturities and sales of short-term investments 489,837 208,165 —

Payments to Akeso for upfront milestone payments and associated direct transaction costs — ( 15,007 ) ( 475,015 )

( 15,007 ) ( 475,015 ) —

Net cash used in investing activities ( 174,310 ) ( 205,341 ) ( 587,774 )

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500,037 434,860 5,000

Proceeds from the issuance of common stock under at-the-market offering, net of

commissions and offering costs

Proceeds from the issuance of common stock for rights offering

— 104,686 100,000

Transaction costs from the issuance of common stock for rights offering

Proceeds from the issuance of common stock under at-the-market offering, net of commissions and offering costs 104,528 43,033 —

Proceeds from exercise of warrants (2)

7,315 598 1,203

Net receipts related to the exercise of warrants

Proceeds received related to employee stock purchase plan and exercise of stock options 5,653 2,736 929

Proceeds from related party promissory notes — — 545,000

Proceeds from the issuance of common stock for rights offering (2)

Transaction costs from the issuance of common stock for rights offering — — ( 619 )

Re-payment of related party promissory notes — ( 100,000 ) ( 24,686 )

Payments of related party promissory notes issuance costs — — ( 44 )

Net cash provided by financing activities 617,533 381,227 86,513

Effect of exchange rates on cash and cash equivalents 102 ( 18 ) 839

( 18 ) 839 ( 1,222 )

Increase (decrease) in cash, cash equivalents and restricted cash 120,395 33,762 ( 577,182 )

33,762 ( 577,182 ) 576,816

Cash, cash equivalents and restricted cash at beginning of period 105,187 71,425 648,607

71,425 648,607 71,791

Cash, cash equivalents and restricted cash at end of period $ 225,582 $ 105,187 71,425

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Supplemental Disclosure of Non-Cash Investing and Financing Activities:

Debt issuance costs in accrued expenses $ — $ — $ 31

Leased assets obtained in exchange for operating lease liabilities $ 17,056 $ 4,216 $ 4,245

Unpaid amounts related to purchase of property, plant and equipment $ 291 $ — $ —

Consideration for the issuance of common stock for rights offering used to satisfy a portion of a related party promissory note (Note 12)

$ — $ — $ 395,314

Deferred transaction costs included in other non-current assets $ — $ — $ 425

Leased assets obtained in exchange for operating lease liabilities $ 4,216 $ 4,245 $ 2,860

Issuance of common stock pursuant to the Akeso License Agreement (Note 4)

$ — $ — $ 45,900

(2) Refer to Note 13 – Stockholders’ Equity for related party transactions.

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

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

Nature of Business and Operations

(in thousands, except share and per share data)

Summit Therapeutics Inc.

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The Company’s current lead development candidate is ivonescimab, a novel, potential first-in-class bispecific antibody intending to combine the effects of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects of an anti-VEGF compound into a single molecule.

On December 5, 2022, the Company entered into a Collaboration and License Agreement (the “License Agreement”) with Akeso, Inc.

and its affiliates (collectively, “Akeso”) pursuant to which the Company has in-licensed intellectual property related to ivonescimab, as further described in Note 5.

On December 5, 2022, the Company entered into the License Agreement with Akeso, Inc.

and its affiliates (collectively, “Akeso”) pursuant to which the Company has in-licensed intellectual property rights related to ivonescimab (as amended, the “License Agreement”), as further described in Note 4.

Through the License Agreement, the Company obtained the rights to develop and commercialize ivonescimab in the United States, Canada, Europe, and Japan.

The License Agreement and transaction closed in January 2023 following customary waiting periods.

On June 3, 2024, the Company entered into an amendment to the License Agreement with Akeso to expand its territories covered under the License Agreement to also include the Latin America, Middle East and Africa regions (collectively, and as expanded, the “Licensed Territory”).

On June 3, 2024, the Company entered into an amendment to the License Agreement (the “Second Amendment”) with Akeso to expand its territories covered under the License Agreement to also include Latin America, including Mexico and all countries in Central America and South America, the Middle East and Africa (collectively, and as expanded, the “Licensed Territory“) .

The Company’s operations are focused on the development of ivonescimab and other future activities, as the Company determines.

Basis of Presentation and Use of Estimates

Basis of Presentation

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Use of Estimates

The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenues and expenses during the reporting period.

On an on-going basis, management evaluates its estimates and judgments, including those related to accrued research and development expenses, stock-based compensation, other long-lived assets and income taxes.

On an on-going basis, management evaluates its estimates and judgments, including those related to accrued research and development expenses, stock-based compensation, and income taxes.

Management bases its estimates and judgments on historical experience and on various other factors that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources.

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Liquidity and Capital Resources

During the year ended December 31, 2024, the Company incurred a net loss of $ 221,315 and cash flows used in operating activities was $ 142,106 .

As of December 31, 2024, the Company had an accumulated deficit of $ 1,214,573 , and cash and cash equivalents of $ 104,862 and short term investments in U.S.

treasury securities of $ 307,487 .

During the year ended December 31, 2025, the Company incurred a net loss of $ 1,079,586 and cash used in operating activities was $ 322,930 .

As of December 31, 2025, the Company had an accumulated deficit of $ 2,294,159 , and cash and cash equivalents of $ 225,266 and short-term investments of $ 488,182 .

The Company expects to continue to generate operating losses for the foreseeable future.

The Company has evaluated and concluded that its cash, cash equivalents and short-term investments provide sufficient cash to fund its operating cash needs for at least the next 12 months from the date of issuance of these consolidated financial statements.

During the year ended December 31, 2025, the Company raised gross proceeds of $ 500,037 from a private placement and $ 106,498 from the Company’s at-the-market sales agreement, both described further in Note 13.

With these recent financings, the Company has evaluated and concluded that its cash, cash equivalents and short-term investments provide sufficient cash to fund its operating cash needs for at least the next 12 months from the date of issuance of these consolidated financial statements.

Until the Company can generate substantial revenue and achieve profitability, the Company will need to raise additional capital to fund its ongoing operations and capital needs.

The Company continues to evaluate options to further finance its operating

Summit Therapeutics Inc.

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(in thousands, except share and per share data)

Until the Company can generate substantial revenue and achieve profitability, the Company will need to raise additional capital to fund its ongoing operations and capital needs.

The Company continues to evaluate options to further finance its operating cash needs for its product candidates through a combination of some, or all, of the following:

cash needs for its product candidates through a combination of some, or all, of the following:

equity and debt offerings, collaborations, strategic alliances, grants and clinical trial support from government entities, philanthropic, non-government and not-for-profit organizations, and marketing, distribution or licensing arrangements.

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Translation gains and losses are included in accumulated other comprehensive (loss) income in stockholders’ equity.

Foreign currency transaction gains and losses are included in other expen se, net in the results of operations.

The Company recorded realized and unrealized foreign currency transaction (loss) gain of ($ 97 ), $ 613 and ($ 4,109 ) for the years ended December 31, 2024, 2023 and 2022, respectively, which is included in other expense, net in the statements of operations and comprehensive loss.

Other Operating (Expense) Income, Net

The Company generated income from government contracts that reimburse the Company for certain allowable costs for funded projects.

For contracts with government agencies where the funding arrangement is considered central to the Company’s ongoing operations, the Company classifies the recognized funding received within other operating (expense) income, net in the consolidated statements of operations and comprehensive loss.

Income from government grants is recognized as the qualifying expenses related to the contracts are incurred, provided that there is reasonable assurance of recoverability.

If the government agency approves the project proposed by the Company, the government agency funds the project upon receipt of the support for the costs incurred up to the contract limit.

Income recognized upon incurring qualifying expenses in advance of billing is recorded as unbilled receivable, a component of other current assets, in the consolidated balance sheet.

Grant income is not recognized as deductions of research and development costs because the Company acts as the principal in conducting the research and development activities and these contracts are central to its ongoing operations.

The funds received through these means are held as deferred income in the consolidated balance sheets and are released to the consolidated statement of operations and comprehensive loss, classified as other operating (expense) income, net, as the underlying expenditure is incurred and to the extent the conditions of the grant are met.

The related costs incurred by the Company are included in research and development expense in the Company’s consolidated statements of operations and comprehensive loss.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

The Company benefits from two United Kingdom ("U.K.") research and development (“R&D”) tax credit cash rebate regimes:

Small and Medium Enterprise (“SME”) Program and the Research and Development Expenditure Credit (“RDEC”) Program.

Each reporting period, management evaluates which tax relief programs the Company is expected to be eligible for and records as other operating (expense) income, net the portion of the expense that it expects to qualify under the programs, that it plans to submit a claim for, and it has reasonable assurance that the amount will ultimately be realized.

Foreign currency transaction gains and losses are included in other income , net in the consolidated statements of operations and comprehensive loss.

The Company recorded realized and unrealized foreign currency transaction (loss) gain of ($ 610 ), $( 97 ) and $ 613 for the years ended December 31, 2025, 2024 and 2023, respectively, which is included in other income, net in the consolidated statements of operations and comprehensive loss.

Net Loss Per Share

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The Company assesses goodwill for impairment on an annual basis as of December 31 or more frequently when events and circumstances occur indicating that the recorded goodwill may be impaired.

The Company regularly monitors current business conditions and other factors including, but not limited to, adverse industry or economic trends and lower projections of profitability that may impact future operating results.

The Company regularly monitors current business conditions and other factors including, but not limited to, adverse industry or economic trends and lower projections of

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

profitability that may impact future operating results.

The process of evaluating the potential impairment of goodwill requires significant judgment.

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If the fair value is less than the carrying amount, a goodwill impairment loss is measured and recorded.

Intangible Assets and Long-lived Assets

The Company evaluates the recoverability of its intangible and long-lived assets whenever events and changes in circumstances indicate that the carrying amount of an asset or asset group may not be fully recoverable.

If events and circumstances indicate that the carrying amount may not fully be recoverable, the carrying values of the asset or asset group are evaluated in relation to their operating performance and future undiscounted cash flows of the underlying business.

If the future undiscounted cash flows are less than their carrying value, impairment exists.

The impairment is measured as the difference between the carrying value and the fair value of the underlying asset or asset group.

Fair values are based on estimates of market prices and assumptions concerning the amount and timing of estimated future cash flows and assumed discount rates, reflecting varying degrees of perceived risk.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation.

Cost is comprised of the purchase price plus any incidental costs of acquisition and commissioning.

Depreciation is calculated based on cost, less residual value, in equal annual installments over the estimated useful lives of the assets.

The residual value, if significant, is reassessed annually.

Laboratory equipment 2 - 10 years

Furniture and fixtures, office equipment and software

Leasehold improvements Over the shorter of the asset ’ s useful life or the remaining lease term

Depreciation is recognized as part of the general and administrative and research and development expense lines shown on the face of the consolidated statement of operations and comprehensive loss depending on the nature of the underlying assets.

Expenditures for repairs and maintenance are expensed as incurred.

Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is included in loss from operations.

The Company has operating leases for real estate.

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Any development or commercial milestone payments are recognized when the achievement of the associated milestone becomes probable and will either be expensed or capitalized depending upon whether or not regulatory approval has been obtained.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Research and Development Costs

1 unchanged sentence

Research and development expenses consist of costs incurred to discover, research and develop product candidates, including personnel expenses, stock-based compensation expense, allocated facility-related and depreciation expenses, third-party license fees and external costs of outside vendors engaged to conduct preclinical and clinical development activities and clinical trials as well as to manufacture clinical trial materials.

Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

refundable prepayments for goods or services that will be used or rendered for future research and development activities are recorded as prepaid expenses.

Such amounts are recognized as an expense as the goods are delivered or the related services are performed, or until it is no longer expected that the goods will be delivered, or the services rendered.

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Equity awards generally vest over terms of 3 or 4 years.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

The Company classifies stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified.

1 unchanged sentence

Tax laws may require items to be included in tax filings at different times than the items are reflected in the financial statements.

A current asset or liability is recognized for the estimated taxes receivable or payable for the current year.

A current asset or liability is recognized

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

for the estimated taxes receivable or payable for the current year.

Deferred taxes represent the future tax consequences expected to occur when the reported amounts of assets and liabilities are recovered or paid.

2 unchanged sentences

Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized.

The Company has recorded a full valuation allowance against the deferred tax assets in excess of its deferred tax liabilities, as the deferred tax liability represents future reversals of existing taxable temporary differences.

The Company has recorded a full valuation allowance against the deferred tax assets in excess of its deferred tax liabilities, as the deferred tax liabilities represent future reversals of existing taxable temporary differences.

The Company records interest and penalties related to income tax matters as part of income tax expense.

Concentration of Credit Risk

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash and short-term investments.

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Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Level 3 assets and liabilities include financial instruments whose value is determined using pricing models,

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation.

Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation.

In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy.

1 unchanged sentence

The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Cash and Cash Equivalents

The Company considers only those investments that are highly liquid, readily convertible to cash and that mature within 90 days or less from date of purchase to be cash equivalents.

As of December 31, 2024, cash equivalents were comprised of money market funds.

As of December 31, 2025, cash equivalents were comprised of money market funds and U.S.

treasury securities.

As of December 31, 2024 , cash equivalents were comprised of money market funds.

Restricted Cash

Restricted cash represents amounts which are legally restricted to withdrawal or usage and is presented in the consolidated balance sheet as restricted cash.

On December 15, 2022, the Company transferred $ 300,000 into an escrow fund reserved for the Company ’ s initial upfront payment to Akeso in connection with the License Agreement, as described further in Note 5.

Following the Antitrust Clearance Date, on January 17, 2023, the License Agreement closed and Akeso was issued 10,000,000 shares of Company common stock pursuant to the Common Stock Issuance Agreement and was paid $ 274,900 in cash as the initial upfront payment.

The remaining amounts in escrow were returned to the Company ’ s operating cash accounts.

As of December 31, 2025 the Company has $ 316 of restricted cash associated with an irrevocable letter of credit required by the landlord to enter into the lease for Company’s corporate office.

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Short-term Investments

Marketable securities consist of investments with original maturities greater than ninety days from the date of acquisition.

The Company classifies investments with maturities of greater than 90 days and less than one year as short-term, based on the liquid nature of the securities and because such marketable securities represent the investment of cash that is available for current operations.

The Company considers its investment portfolio of investments as available-for-sale.

Short-term investments consist of marketable securities with original maturities greater than ninety days from the date of acquisition.

The Company classifies marketable securities with original maturities of greater than 90 days and less than one year as short-term, based on the liquid nature of the marketable securities and because such marketable securities represent the investment of cash that is available for current operations.

The Company considers its investment portfolio of marketable securities as available-for-sale.

Accordingly, these investments are recorded at fair value, which is based on quoted market prices or other observable inputs.

Unrealized gains and losses are recorded as a component of other comprehensive income (loss).

Realized gains and losses are determined on a specific identification basis and are included in other (expense) income.

Amortization and accretion of discounts and premiums are also recorded in other (expense) income.

Realized gains and losses are determined on a specific identification basis and are included in other income, net.

Amortization and accretion of discounts and premiums are also recorded in other income, net.

When the fair value is below the amortized cost of the asset, an estimate of expected credit losses is made.

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If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis the allowance for credit loss is written off and the excess of the amortized cost basis of the asset over its fair value is recorded in the consolidated statements of operations and comprehensive loss.

Recently Issued Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update “ASU” 2023-09, “Improvements to Income Tax Disclosures”, which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures.

ASU 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option.

Early adoption is permitted.

The Company adopted ASU 2023-09 for the year ended December 31, 2025 using a retrospective approach.

The adoption of ASU-2023-09 did not have a material impact on the Company’s consolidated financial statements and related disclosures.

Summit Therapeutics Inc.

1 unchanged sentence

(in thousands, except share and per share data)

Warrants issued by the Company are recognized and classified as equity when, upon exercise, the Company would issue a fixed amount of its own equity instruments (common stock) in exchange for a fixed amount of cash or another financial asset.

Consideration received, net of incremental costs directly attributable to the issue of such new warrants, is shown in stockholders' equity.

Such warrants are not remeasured at fair value in subsequent reporting periods.

Warrants issued in which external services are received as consideration for equity instruments of the company should be measured at the fair value of the goods or services received.

Only if the fair value of the services cannot be measured reliably would the fair value of the equity instruments granted be used.

The fair value for the warrants is calculated using the Black-Scholes model and recorded in the consolidated statement of operations and comprehensive loss on a straight-line basis over the period of the consulting services.

If the services are terminated prior to the end of the consultancy agreement, the warrants cease vesting and any unvested portion of the warrants will lapse immediately.

The warrants in issue are classified within stockholders’ equity as they are indexed to the Company ’ s own shares of common stock and require settlement in its shares of common stocks with no provision for any cash settlement.

Recently Issued or Adopted Accounting Pronouncements

In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards update “ASU” No.

2023-09, “Improvements to Income Tax Disclosures”, which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation, and modifies other income tax-related disclosures.

2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option.

In November 2024, the FASB issued ASU 2024-03, “Disaggregation of Income Statement Expenses”, which requires disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures.

The guidance is to be applied prospectively, with the option for retrospective application and is effective for public business entities for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027.

Early adoption is permitted.

The Company is currently evaluating the impact of the ASU on the income tax disclosures within the consolidated financial statements.

In November 2023, the FASB issued ASU No.

2023-07, “Segment Reporting (Topic 280):

Improvements to Reportable Segment Disclosures”, which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others.

2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024.

Early adoption was permitted, and the amendments should be applied retrospectively.

The Company adopted and retrospectively applied the amendments in this update during the fourth quarter of 2024 and in preparation of the annual consolidated financial statements.

Refer to Note 6 regarding the additional disclosures included within the consolidated financial statements.

In November 2024, the FASB issued ASU 2024-03, “Disaggregation of Income Statement Expenses.” The new standard requires disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures.

The guidance is effective for public business entities for fiscal years beginning after December 15, 2026, and interim periods beginning after December 15, 2027.

The Company is currently evaluating the impact of the adoption of this standard on the Company’s consolidated financial statements and related disclosures.

In December 2025, the FASB issued ASU 2025-11, “Narrow-Scope Improvements”, which is intended to improve the navigability of the guidance in ASC 270 and clarify when the guidance is applicable.

ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027.

Early adoption is permitted.

The guidance is to be applied prospectively, with the option for retrospective application.

The Company is currently evaluating the impact of the ASU on the disclosures within the consolidated financial statements.

Other recent authoritative guidance issued by the FASB (including technical corrections to the FASB ASC), the American Institute of Certified Public Accountants, and the Securities and Exchange Commission did not or are not expected to have a material impact on the Company ’ s consolidated financial statements.

The Company is currently evaluating the impact of the adoption of this standard on the Company’s consolidated financial statements and related disclosures.

Other recent authoritative guidance issued by the FASB (including technical corrections to the FASB ASC), the American Institute of Certified Public Accountants, and the SEC did not or are not expected to have a material impact on the Company’s consolidated financial statements and related disclosures.

Segment Reporting

The Company’s chief operating decision makers (the “CODM function ” ), which are the Company ’ s Co-Chief Executive Officers, Mr.

Duggan and Dr.

Zanganeh, and Chief Operating Officer and Chief Financial Officer, Mr.

Soni, utilize consolidated net loss that is reported on the consolidated statement of operations and comprehensive loss to make decisions about allocating resources and assessing performance for the entire Company.

The CODM function approves of key operating and strategic decisions, including key decisions in clinical development and clinical operating activities, entering into significant contracts, such as revenue contracts and collaboration agreements and approves the Company ’ s consolidated operating budget.

The CODM function views the Company's operations and manages its business on a consolidated basis and as a single reportable operating segment.

The CODM function is regularly provided with the following significant segment expenses:

Year Ended December 31,

2025 2024 2023

Oncology clinical trial related costs $ 266,439 $ 100,937 $ 35,224

Acquired in-process research and development — 15,007 520,915

Compensation related costs, excluding stock-based compensation 75,575 48,295 31,371

Stock-based compensation 732,420 50,981 14,108

Other expenses (1)

19,990 10,778 8,032

Total segment expenses

1,094,424 225,998 609,650

Other income, net 14,838 13,369 11,183

Interest expense — ( 8,686 ) ( 16,461 )

Net loss $ ( 1,079,586 ) $ ( 221,315 ) $ ( 614,928 )

(1) Other expenses include general and administrative expenses excluding compensation and stock-based compensation.

As of December 31, 2025 and 2024, substantially all of our long-lived assets are located in the United States.

Akeso License and Collaboration Agreement

On December 5, 2022, the Company entered into a Collaboration and License Agreement (the “License Agreement”) with Akeso, Inc.

and its affiliates ("Akeso") pursuant to which the Company is in-licensing its breakthrough bispecific antibody, ivonescimab.

On December 5, 2022, the Company entered into the License Agreement with Akeso pursuant to which the Company is in-licensing its breakthrough bispecific antibody, ivonescimab.

The License Agreement and transaction closed in January 2023 following customary waiting periods.

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Pursuant to the terms of the License Agreement, Summit will have final decision-making authority with respect to commercial strategy, pricing and reimbursement and other commercialization matters in the Licensed Territory.

In connection with the License Agreement, the Company has also entered into a Supply Agreement with Akeso, pursuant to which Summit agrees to purchase a certain portion of drug substance for clinical and commercial supply.

In connection with the License Agreement, the Company agreed to purchase a certain portion of drug substance and/or drug product for clinical and commercial supply and to enter into a supply agreement with Akeso.

Summit is not assuming any liabilities (including contingent liabilities), acquiring any physical assets or trade names, or hiring or acquiring any employees from Akeso in connection with the License Agreement.

Through the License Agreement, the Company obtained the rights to develop and commercialize ivonescimab in the United States, Canada, Europe, and Japan.

In exchange for the rights obtained, the Company made an upfront payment of $ 500,000 to Akeso, of which $ 274,900 was paid in cash and, pursuant to the License Agreement and Issuance Agreement, Akeso elected to receive 10,000,000 shares of our common stock in lieu of $ 25,100 cash.

The remaining $ 200,000 amount of the upfront payment was paid on March 6, 2023.

Effective June 3, 2024, the Company and Akeso entered into an amendment (the “Second Amendment”) to the License Agreement to expand the Company’s territories covered under the License Agreement to include the Latin America, Middle East and Africa regions.

Effective June 3, 2024, the Company and Akeso entered into the Second Amendment to the License Agreement to expand the Company’s territories covered under the License Agreement to include the Latin America, Middle East and Africa regions.

Pursuant to the Second Amendment, the Company paid an upfront payment to Akeso of $ 15,000 in the third quarter of 2024.

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As such, the Company has expensed the consideration as acquired in-process research and development upon closing of the transaction in the consolidated statement of operations and comprehensive loss.

Acquired in-process research and development expense for the year ended December 31, 2024 was $ 15,007 which related to the upfront payment and immaterial transaction costs for the Second Amendment.

For the year ended December 31, 2023, acquired in-process research and development expense was $ 520,915 which was comprised of the $ 474,900 paid in cash, the fair value of the 10,000,000 shares of common stock on the date of closing the transaction of $ 45,900 , and $ 115 of direct transactions costs incurred for the License Agreement.

Acquired in-process research and development expense for the year ended December 31, 2025 was nil .

Acquired in-process research and development expense for the year ended December 31, 2024, was $ 15,007 which is comprised of the upfront payment and immaterial transaction costs.

For the year ended December 31, 2023, acquired in-process research and development expense totaled $ 520,915 pursuant to the License Agreement, which was comprised of the $ 474,900 paid in cash, the fair value of the 10,000,000 shares of common stock on the date of closing the transaction of $ 45,900 , and $ 115 of direct transactions costs incurred.

In addition to the payments already made to Akeso, under the License Agreement and Second Amendment, there are additional potential milestone payments of up to $ 4,555,000 , as Akeso will be eligible to receive regulatory milestones of up to $ 1,050,000 and commercial milestones of up to $ 3,505,000 .

3 unchanged sentences

(in thousands, except share and per share data)

Segment Reporting

The Company’s chief operating decision makers (the “CODM function"), which are the Company's Co-Chief Executive Officers, Mr.

Duggan and Dr.

Zanganeh, and Chief Operating Officer and Chief Financial Officer, Mr.

The CODM function views the Company's operations and manages its business on a consolidated basis and as a single reportable operating segment.

The CODM function is regularly provided with the following significant segment expenses:

Year Ended December 31,

2024 2023 2022

$ — $ — $ 705

Oncology clinical trial related costs 100,937 35,224 —

Acquired in-process research and development 15,007 520,915 —

Compensation related costs, excluding stock-based compensation 48,295 31,371 27,817

Stock-based compensation 50,981 14,108 11,948

Other expenses (2)

11,091 9,033 47,445

Total segment expenses

226,311 610,651 87,210

Other operating income, net 313 1,001 14,416

Operating loss ( 225,998 ) ( 609,650 ) ( 72,089 )

Other income (expense), net 13,369 11,183 ( 2,292 )

Interest expense ( 8,686 ) ( 16,461 ) ( 4,401 )

Net loss $ ( 221,315 ) $ ( 614,928 ) $ ( 78,782 )

(1) Revenue relates to amounts received from the license and commercialization agreement related to ridinilazole clinical trials.

All prior development activities related to ridinilazole have been terminated.

(2) Other expenses include costs for the Company’s antibiotic pipeline research activities and ridinilazole or CDI program activities (collectively, “Anti-infectives), general and administrative expenses excluding compensation and stock-based compensation, and impairment of intangible assets.

All prior development activities related to Anti-infectives have been terminated.

As of December 31, 2024 and 2023, substantially all of our long-lived assets are located in the United States.

Other Operating Income, net

The following table sets forth the components of other operating income by category:

Year Ended December 31,

2024 2023 2022

Funding income from BARDA (as defined below) $ — $ — 8,085

Research and development tax credits 313 946 4,523

Grant income from CARB-X (as defined below) — 45 1,808

Other income — 10 —

$ 313 $ 1,001 14,416

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

BARDA (as defined below)

In September 2017, we were awarded a funding contract from the Biomedical Advanced Research and Development Authority (“BARDA”), part of the Office of the Assistant Secretary for Preparedness and Response at the United States Department of Health and Human Services, to fund, in part, the clinical and regulatory development of ridinilazole for the treatment of infections caused by C.

difficile ("CDI").

The contract provides for a cost-sharing arrangement under which BARDA committed to funding $ 62,400 of estimated costs for the continued clinical and regulatory development of ridinilazole for CDI.

As a result of the Company ’ s decision, on September 28, 2022, to not pursue further internal clinical development of ridinilazole and seek partners or a divestiture related to ridinilazole as a path forward for the clinical development of the asset, the Company recorded expenses for the remaining clinical trial costs associated with the close out activities of ridinilazole and recognized the remainder of the deferred income that had been received from BARDA.

As of December 31, 2022, the Company recognized $ 59,203 of cumulative income under the BARDA contract and no additional income will be recognized.

Research and development credits

Research and development tax credits consists of tax credits received in the United Kingdom (“U.K.”).

As of December 31, 2024 and 2023, the current and long-term research and development tax credit receivable was $ 1,255 and $ 1,807 , respectively.

Refer to Note 4 for information about the two U.K.

research and development tax credit cash rebate regimes which the Company benefits from, as well as criteria established by the HMRC.

CARB-X (as defined below)

In May 2021, the Company received an award from the Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator program ("CARB-X") to progress SMT-738 through preclinical development and an option to continue into Phase Ia clinical studies.

The award committed initial non-dilutive funding of up to $ 4,100 , with the possibility of up to another $ 3,700 based on the achievement of future milestones.

As of December 31, 2022, the Company recognized $ 2,920 of cumulative income under the CARB-X contract and no additional income will be recognized.

Other Income (Expense), net

The following table sets forth the components of other (expense) income:

Other Income, Net

The following table sets forth the components of other income, net:

Year Ended December 31,

2025 2024 2023

Foreign currency (losses) gains

$ ( 97 ) $ 613 $ ( 4,109 )

Foreign currency (loss) gain $ ( 610 ) $ ( 97 ) $ 613

Investment income (1)

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tax law and requires judgment and estimates.

The Company has assessed the applicability of the OECD/G20 Inclusive Framework on Base Erosion and Profit Shifting (BEPS) Pillar 2 rules, which establish a global minimum tax rate.

Based on our current financial position and revenue thresholds, the Company is not large enough for

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Pillar 2 to apply.

The Company has also assessed the applicability of the OECD/G20 Inclusive Framework on Base Erosion and Profit Shifting (BEPS) Pillar 2 rules, which establish a global minimum tax rate.

Based on the Company’s current financial position and revenue it does not meet the thresholds for Pillar 2 to apply.

Therefore, the provisions and requirements under Pillar 2 do not impact our financial statements for the reporting period.

6 unchanged sentences

Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized.

The Company records interest and penalties related to income tax matters as part of income tax expense.

The Company accounts for uncertainty in income taxes by applying a two-step process to determine the amount of tax benefit to be recognized.

First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities.

Uncertain Tax Positions

The Company accounts for uncertain tax positions taken in its tax filings by applying a two-step process to determine the amount of tax benefit to be recognized.

First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities having full knowledge of the facts and applicable tax rules.

If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed as the amount of benefit to recognize in the consolidated financial statements.

The amount of benefits that may be used is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement.

The amount of benefits that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement.

The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate, as well as the related net interest and penalties.

At December 31, 2024 and 2023, the Company had $ 2,122 and $ 1,064 uncertain tax positions for the respective reporting periods.

Due to the Company’s full valuation allowance, the unrecognized tax benefits would not materially impact the Company’s effective tax rate when recognized.

The Company does not anticipate the total amounts of unrecognized tax benefits will significantly increase or decrease in the next 12 months.

The Company’s policy is to recognize interest and penalties related to uncertain tax positions as part of its income tax provision.

For the years ended December 31, 2024 and 2023, the Company had no interest or penalties related to unrecognized tax benefits.

Due to the Company’s full valuation allowance, the unrecognized tax benefits are not expected to materially impact the Company’s effective tax rate when recognized or significantly increase or decrease in the next 12 months.

In addition, the

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Company’s policy is to recognize interest and penalties related to uncertain tax positions as part of its income tax provision.

However, for the years ended December 31, 2025 and 2024, the Company had no interest or penalties related to unrecognized tax benefits because any potential disallowance would not result in current tax but only result in a reduction to the Company’s net operating loss carryforwards.

Loss Before Income Taxes

The components of the Company’s loss before income taxes are as follows:

1 unchanged sentence

2025 2024 2023

$ ( 199,040 ) $ ( 499,810 ) $ ( 46,868 )

Foreign $ ( 326,729 ) $ ( 199,040 ) $ ( 499,810 )

United States ( 752,857 ) ( 22,275 ) ( 115,118 )

Loss before income taxes $ ( 1,079,586 ) $ ( 221,315 ) $ ( 614,928 )

The Company has not recognized a current or deferred provision for federal, state or non-United States income taxes in the years ended December 31, 2024, 2023 and 2022.

Deferred Income Taxes

The Company has not recognized a current or deferred provision for federal, state or non-United States income taxes in either of the years ending December 31, 2025 or December 31, 2024.

Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

The major components of deferred tax assets and liabilities are as follows:

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For the year ended December 31, 2025 and 2024, the Company recorded a deferred tax asset of $ 133,578 and $ 95,925 , respectively.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize its deferred tax assets, which are comprised primarily of net operating loss carryforwards and research and development costs capitalized for tax purposes.

Management has considered the Company’s history of cumulative net losses in the U.S.

and the U.K., estimated future taxable income, as well as prudent and feasible tax planning strategies, and has concluded that it is more likely than not that the Company will not realize the benefits of its U.S.

federal and state deferred tax assets and U.K.

deferred tax assets.

The Company has evaluated the positive and negative evidence bearing upon its ability to realize its deferred tax assets, which are comprised primarily of net operating loss carryforwards, research and development credits, stock-based compensation expense, and research and development costs capitalized for tax purposes.

Management has considered the Company’s history of cumulative net losses in each taxing jurisdiction, estimated future taxable income, as well as prudent and feasible tax planning strategies, and has concluded that it is more likely than not that the Company will not realize the tax benefits in each

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

jurisdiction.

Accordingly, a full valuation allowance has been established against these net deferred tax assets as of December 31, 2025 and 2024, respectively.

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Valuation allowance as of end of year $ ( 133,161 ) $ ( 95,588 ) $ ( 84,751 )

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2025 and 2024, the Company had U.S.

Federal gross operating loss carryforwards of approximately $ 93,210 and $ 44,270 , respectively, which may be available to offset future income tax liabilities.

The 2017 Tax Cuts and Jobs Act (“TCJA”) will generally allow losses incurred after 2017 to be carried over indefinitely, but will generally limit the net operating loss deduction to the lesser of the net operating loss carryover or 80% of a corporation’s taxable income (subject to Section 382 of the Internal Revenue Code of 1986, as amended).

The 2017 Tax Cuts and Jobs Act (“TCJA”) will generally allow losses incurred after 2017 to be carried over indefinitely but generally limits the net operating loss deduction to the lesser of the net operating loss carryover or 80% of a corporation’s taxable income (subject to Section 382 of the Internal Revenue Code of 1986, as amended).

In addition, the Company has approximately $ 21,335 in U.S.

State gross loss carryforwards which expire through various dates through 2043 and as of December 31, 2024, the Company

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

had an estimated U.S.

State gross loss carryforwards which expire through various dates through 2044.

As of December 31, 2025, the Company had an estimated U.S.

federal and state research and development tax credit carryforwards of $ 15,565 and $ 5,002 , respectively, which may be available to offset future tax liabilities, and each begin to expire in 2041 and 2037, respectively.

As of December 31, 2024 the Company also had approximately $ 198,653 in U.K.

gross loss carryforwards available to use against future taxable profits on a year-by-year basis.

As of December 31, 2025 and 2024, the Company had U.K.

gross operating loss carryforwards of approximately $ 211,096 and $ 198,653 respectively, which may be available to offset future income tax liabilities.

To the extent that U.K.

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In addition, losses accrued subsequent to April 1, 2017 will be extinguished on a change of ownership when there is a major change in the nature or conduct of a company’s business, or where there is a major change in the scale of that business, or a company ceases to carry on a particular trade or business.

The Company has not completed a study to assess whether a change of ownership has occurred since its formation, or whether there has been a major change in the Company ’ s business that would restrict the U.K.

The Company has not completed a study to assess whether a change of ownership has occurred since its formation, or whether there has been a major change in the Company ’ s business that would

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

restrict the U.K.

Any limitation may result in the loss of a portion of the net operating loss carryforwards before utilization.

The 2017 Tax Cuts and Jobs Act (“TCJA”) created a requirement that US corporations include in income earnings of certain controlled foreign corporations (“CFC”) under the global intangible low taxed income (“GILTI”) regime.

Income Inclusions

The TCJA created a requirement that US corporations include in income earnings of certain controlled foreign corporations under the global intangible low taxed income (“GILTI”) regime.

Pursuant to the FASB Staff Q&A, Topic 740 No.5.

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net deferred tax assets, these provisions have not had a material impact on the Company’s consolidated financial statements.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Annual Effective Tax Rate Reconciliation

A reconciliation of the Company’s effective tax rate to the U.S.

2 unchanged sentences

2025 2024 2023

federal income tax statutory rate 21.0 % 21.0 % 21.0 %

Tax at federal statutory rate ( 226,702 ) 21.0 % ( 46,476 ) 21.0 % ( 129,048 ) 21.0 %

State income tax, net of federal tax benefit — — % ( 17 ) — % — — %

Change in valuation allowance ( 4.8 ) ( 3.4 ) ( 16.8 )

Research and development tax credit 1.4 0.2 ( 3.6 )

Effect of foreign operations taxed at various rates ( 18.5 ) ( 17.1 ) 2.1

Research and development credits ( 6,828 ) 0.6 % ( 4,782 ) 2.2 % ( 2,275 ) 0.4 %

Nontaxable or nondeductible Items

Stock-based compensation 134,033 ( 12.4 ) % ( 130 ) 0.1 % 2,978 ( 0.5 ) %

Other 299 — % 77 — % 521 ( 0.1 ) %

Foreign Tax Effects

Cayman Islands Statutory income tax rate differential

67,969 ( 6.3 ) % 41,570 ( 18.8 ) % 104,282 ( 17.0 ) %

Other foreign jurisdictions 644 ( 0.1 ) % 229 ( 0.1 ) % 678 ( 0.1 ) %

Changes in unrecognized tax benefits 1,357 ( 0.1 ) % 956 ( 0.4 ) % 800 ( 0.1 ) %

Change in valuation allowance 29,228 ( 2.7 ) % 8,573 ( 4.0 ) % 22,064 ( 3.6 ) %

$ — — % $ — — % $ — — %

Unrecognized Tax Benefit Reconciliation

The Company records unrecognized tax benefits in accordance with ASC 740-10, Income Taxes.

ASC 740-10 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s income tax return and also provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition.

As of December 31, 2025, 2024, and 2023, the Company had total unrecognized tax benefits of $ 3,903 , $ 2,122 , and $ 1,064 , respectively.

A reconciliation of unrecognized tax benefits from continuing operations is as follows:

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Unrecognized tax benefits, beginning of year $ 2,122 $ 1,064 $ —

$ 1,064 $ — $ —

Increases related to prior year tax positions 592 122 610

1 unchanged sentence

Unrecognized tax benefits, end of year $ 3,903 $ 2,122 $ 1,064

$ 2,122 $ 1,064 $ —

In the U.S., the Company files income tax returns in various states.

Tax years from 2020 remain subject to examination by the U.S.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Audit Examinations

In the U.S., the Company files a Federal consolidated income tax return and income tax returns in various states.

In the U.S., the filings for tax years from 2020 remain subject to examination by the U.S.

Internal Revenue Service and state tax authorities.

1 unchanged sentence

To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period.

In the U.K., tax returns for the year ended December 31, 2023 remain subject to examination by HMRC.

In the U.K., tax returns for the year ended December 31, 2023 remains subject to examination by HMRC.

Legislative Impacts

On July 4, 2025, H.R.

budget reconciliation bill, was signed into law.

The Company has assessed the provisions of the new legislation and has integrated the resulting impacts into its effective income tax rate.

Management has concluded that the bill does not have an impact on the Company's consolidated financial statements for the current period.

Net Loss per Share

3 unchanged sentences

Net loss $ ( 1,079,586 ) $ ( 221,315 ) $ ( 614,928 )

Basic weighted average number of shares of common stock outstanding 718,541,896 619,646,180 193,336,063

Diluted weighted average number of shares of common stock outstanding 718,541,896 619,646,180 193,336,063

Basic and diluted weighted average number of shares of common stock outstanding 747,702,265 718,541,896 619,646,180

Basic net loss per share $ ( 1.44 ) $ ( 0.31 ) $ ( 0.99 )

Diluted net loss per share $ ( 1.44 ) $ ( 0.31 ) $ ( 0.99 )

As the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods, as the inclusion of all potential common share equivalents outstanding would have been anti-dilutive.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Because the 2023 Rights Offering (as defined in Note 17) exercise price of $ 1.05 per share was less than the closing price of $ 1.82 per share on March 1, 2023, the expiration, the Company has retroactively adjusted earnings per share and the weighted average number of shares outstanding for the bonus element for the years ended December 31, 2023 and 2022.

Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period.

Diluted net loss per share is computed by dividing the diluted net loss by the weighted-average number of common shares outstanding for the period, including potentially dilutive common shares.

Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods, as the inclusion of all potential common share equivalents outstanding would have been antidilutive.

Because the 2023 Rights Offering (see Note 13) exercise price of $ 1.05 per share was less than the closing price of $ 1.82 per share on March 1, 2023, the expiration, the Company has retroactively adjusted earnings per share and the weighted average number of shares outstanding for the bonus element for the year ended December 31, 2023.

The following potentially dilutive securities were excluded from the computation of the diluted net loss per share of common stock for the periods presented because their effect would have been anti-dilutive:

Year Ended December 31,

2025 2024 2023

3 unchanged sentences

115,680,633 73,636,872 59,380,094

Stock options that are outstanding and contain performance-based or market-based vesting criteria for which the performance or market conditions have not been met are excluded from the presentation of common stock equivalents outstanding in the table above.

Goodwill and Intangible Assets

Stock options that are outstanding and contain improbable vesting criteria are excluded from the presentation of common stock equivalents outstanding in the table above.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

In December 2017, the Company expanded its activities in the field of infectious diseases with the acquisition of Discuva Limited, a privately held United Kingdom-based company.

Through this acquisition, the Company obtained a bacterial genetics platform and a suite of software-based technologies (the “Discuva Platform”), which facilitates the discovery and development of new mechanism antibiotics.

Through this acquisition, the Company obtained a bacterial genetics platform and a suite of software-based technologies, which facilitates the discovery and development of new mechanism antibiotics.

This resulted in the recognition of goodwill of £ 1.5 million, which is translated into U.S.

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The Company has recorded no goodwill impairment charges to date.

Intangible Assets

In December 2017, the Company expanded its infectious disease research by acquiring Discuva Limited, a privately held company in the United Kingdom.

This acquisition provided a bacterial genetics platform and associated software-based technologies (collectively referred to as the “Discuva Platform”).

In conjunction with the significant change in the Company’s strategy and shift in focus to the therapeutic area of oncology, the Company determined that it would cease further investment in the Discuva Platform.

Management concluded that the carrying amount of the acquired Discuva Platform intangible asset may not be recoverable and performed an assessment to calculate the fair value of the asset using a probability-weighted approach which was compared to the carrying value of the asset.

An impairment charge of $ 8,468 which represented the carrying value of the Discuva Platform was recognized during the year ended December 31, 2022.

This impairment charge is presented as impairment of intangible assets in the consolidated statements of operations and comprehensive loss.

There was no amortization expense for the years ended December 31, 2024 and 2023.

Amortization expense for the year ended December 31, 2022 was $ 914 .

Net book value of intangible assets is nil as at December 31, 2024 and December 31, 2023.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Fair Value Measurements and Short-Term Investments

Fair Value Measurements

The following tables sets forth the Company’s fair value hierarchy for its assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2025 and 2024:

Fair Value Measurements as of December 31, 2024

Level 1 Level 2 Level 3 Total

Cash equivalents:

Money market funds $ 88,599 $ — $ — $ 88,599

Short-term investments:

Government treasury bills — 307,487 — 307,487

$ 88,599 $ 307,487 $ — $ 396,086

Fair Value Measurements as of December 31, 2023

Level 1 Level 2 Level 3 Total

Cash equivalents:

Money market funds $ 21,016 $ — $ — $ 21,016

Government treasury bills — 39,341 — 39,341

Short-term investments:

Government treasury bills

— 114,817 — 114,817

$ 21,016 $ 154,158 $ — $ 175,174

December 31, 2025

Fair Value Hierarchy Level Amortized Cost Unrealized Gain Unrealized (Loss) Credit (Loss) Fair Value

Financial assets included within cash and cash equivalents:

Money market funds Level 1 $ 163,588 $ — $ — $ — $ 163,588

Government treasury bills Level 2 45,300 12 — — 45,312

Financial assets included within short-term investments:

Certificate of deposit

Level 2 25,000 — — — 25,000

Government treasury bills Level 2 463,022 160 — — 463,182

Total $ 696,910 $ 172 $ — $ — $ 697,082

December 31, 2024

Fair Value Hierarchy Level Amortized Cost Unrealized Gain Unrealized (Loss) Credit (Loss) Fair Value

Financial assets included within cash and cash equivalents:

Money market funds Level 1 $ 88,599 $ — $ — $ — $ 88,599

Financial assets included within short-term investments:

Government treasury bills Level 2 307,387 100 — — 307,487

Total $ 395,986 $ 100 $ — $ — $ 396,086

The tables above do not include cash at December 31, 2025 and 2024 of $ 16,366 and $ 16,263 , respectively.

The Company believes that the carrying amounts of prepaid expenses, other current assets, accounts payable, and accrued expenses approximates their fair values due to the short-term nature of those instruments.

As of December 31, 2023, the carrying value of the Company’s promissory note approximated its fair value and the current interest rate of the note outstanding when compared to market interest rates (which represents a Level 2 measurement).

Refer to Note 16 for further details.

Summit Therapeutics Inc.

1 unchanged sentence

(in thousands, except share and per share data)

Short-Term Investments

The following table sets forth the Company’s short-term investments as of December 31, 2024 and 2023, which have a contractual maturity of less than one year:

December 31, 2024

Amortized Cost Unrealized Gains

Unrealized (Losses)

Credit (Loss)

Government treasury bills $ 307,387 $ 100 $ — $ — $ 307,487

Total $ 307,387 $ 100 $ — $ — $ 307,487

December 31, 2023

Amortized Cost Unrealized Gains

Unrealized (Losses)

Credit (Loss)

Government treasury bills $ 114,781 $ 36 $ — $ — $ 114,817

Total $ 114,781 $ 36 $ — $ — $ 114,817

Property and Equipment

Property and equipment consisted of the following:

December 31, 2024 December 31, 2023

Laboratory equipment $ 21 $ 22

Furniture and fixtures, office equipment and software 1,028 896

Leasehold improvements 323 328

Property and equipment, gross 1,372 1,246

accumulated depreciation ( 1,118 ) ( 1,042 )

Property and equipment, net $ 254 $ 204

Depreciation expense for the years ended December 31, 2024, 2023 and 2022 was $ 89 , $ 198 and $ 349 , respectively.

There were no material impairment charges related to fixed assets for the years ended December 31, 2024, 2023 and 2022.

Realized gain (loss) on short-term investments for the years ended December 31, 2025 and 2024 were immaterial, respectively.

Research and Development Prepaid Expenses and Accrued Liabilities

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Included within accrued liabilities at December 31, 2025 and 2024 is $ 31,498 and $ 17,441 , respectively, relating to research and development expenditures.

The Company records accruals for estimated ongoing research and development costs or prepaid expenses where the payments made exceed the estimated costs.

These amounts are determined based on the estimated costs to complete each study or activity, the estimation of the current stage of completion and the invoices received, as well as predetermined milestones which are not reflective of the current stage of development for prepaid expenses.

However, prepaid expenses decrease and accrued liabilities increase as the activities progress, and if actual costs incurred exceed the prepaid expense, an accrual will be recorded for the liability.

These amounts are determined based on the estimated costs to complete each study or activity related to the ongoing clinical trials for ivonescimab, the estimation of the current stage of completion and the invoices received, as well as predetermined milestones which are not reflective of the current stage of development for prepaid expenses.

However, accrued liabilities increase as the activities progress.

The key sensitivity is the estimated current stage of completion of each study or activity, which is based on information received from the supplier and the Company’s operational knowledge of the work completed under those contracts.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

The Company has operating leases for real estate.

The Company does not have any finance leases.

The Company leases its offices and facilities in Menlo Park, CA, Miami, FL and Oxford, U.K., under non-cancellable operating lease agreements.

The lease agreements for the Company’s offices and facilities in Menlo Park, CA expire from December 2025 to May 2026.

The lease agreements for the Company’s offices and facilities in Miami, FL and Oxford, U.K.

April 2029 and February 2027, respectively.

The Company leases its offices and facilities in Miami, FL, Palo Alto, CA, Princeton, NJ, Oxford, U.K., and Menlo Park, CA under non-cancellable operating lease agreements.

The lease agreements for the Company’s offices and facilities in Miami, FL, Palo Alto, CA, Princeton, NJ and Oxford, U.K., expire in April 2029, October 2033, August 2028, and February 2027, respectively.

The remaining lease agreement for the Company’s office and facility in Menlo Park, CA expires in May 2026.

Under the terms of the lease agreements, the Company is responsible for certain repair and maintenance, utilities, licensing and permit fees.

During the year ended December 31, 2024, the Company recorded $ 4,216 of additional right-of-use assets related to a new lease for office space that commenced during the first fiscal quarter for its Miami, Florida headquarter location.

During the year ended December 31, 2025, the Company recorded $ 17,056 of operating right-of-use assets and operating lease liabilities related to new leases for office space for its Palo Alto, CA and Princeton, NJ locations.

Total future lease payments as of December 31, 2025 are approximately $ 23,117 on an undiscounted basis.

This lease commenced on February 1, 2024 and has a term of 5.3 years.

As of December 31, 2024, the Company had $ 325 of restricted cash associated with an irrevocable letter of credit required by the landlord to enter into this lease.

In addition, during the year ended December 31, 2023, the Company terminated the Company’s Cambridge, U.K.

laboratory and office space lease as a result of the Company re-prioritizing its investments and financial resources towards the development of ivonescimab.

This resulted in disposing the carrying value of the right-of use asset of $ 788 , removing the related lease liability of $ 809 , and there were no penalties charged for early termination of this lease.

The Palo Alto lease commenced on December 1, 2025 and has a term of approximately 8 years.

The Princeton, NJ lease commenced on August 18, 2025 and has a term of 3 years.

The Company recorded $ 4,216 of right-of-use assets during the year ended December 31, 2024 related to its Miami, Florida headquarters.

The carrying value of the right-of-use assets as of December 31, 2025 and 2024 is $ 20,616 and $ 7,144 , respectively.

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Variable lease costs 225 48 83

Short-term lease (1)

Total lease cost $ 4,078 $ 3,509 $ 2,297

(1) Short-term lease costs relate to the Company’s Cambridge, Massachusetts, United States office lease which the Company exited during fiscal year 2022.

The weighted average discount rate and the weighted average remaining lease term were 7.6 % and 6.7 years, respectively, as of December 31, 2025.

The weighted average discount rate and the weighted average remaining lease term were 6.9 % and 2.8 years, respectively, as of December 31, 2024.

The Company made cash payments related to lease liabilities of $ 2,568 and $ 2,208 for the years ending December 31, 2024 and 2023 respectively.

The Company made cash payments related to lease liabilities of $ 3,741 and $ 2,568 for the years ended December 31, 2025 and 2024, respectively.

Summit Therapeutics Inc.

3 unchanged sentences

Year Ending December 31,

Thereafter 9,205

Total lease payments 27,328

1 unchanged sentence

Total operating lease liabilities $ 20,890

Total operating lease liabilities balance sheet presentation:

Current lease liabilities $ 3,765

Non-current lease liabilities 3,453

Operating lease liabilities, current portion 3,388

Operating lease liabilities, net of current portion $ 17,502

Promissory Note Payable to Related Parties

At December 31, 2024 and 2023, the Company's non-current debt was $ 0 and $ 100,000 , respectively.

As of December 31, 2023, the non-current debt balance consisted of principal amounts due on promissory notes payable to related parties as described below.

At December 31, 2024 and 2023, the Company had no current debt.

March 2022 Promissory Note

On March 10, 2022, Mr.

Duggan, entered into a Note Purchase Agreement (the “March 2022 Note”), pursuant to which he loaned the Company $ 25,000 in exchange for the issuance by the Company of an unsecured promissory note in the amount of $ 25,000 .

The March 2022 Note accrued interest at a rate per annum equal to the prime rate as reported in the Wall Street Journal .

The March 2022 Note, including all accrued interest, became due upon the earlier of (i) the consummation of a registered public offering with net proceeds of no less than $ 25,000 or (ii) 18 months from the date of issuance of the March 2022 Note.

Debt issuance costs associated with the March 2022 Note were immaterial and expensed as incurred.

The March 2022 Note of $ 25,000 , plus accrued interest of $ 434 was repaid to Mr.

Duggan on August 10, 2022 in connection with the completion of the 2022 Rights Offering (as defined in Note 17) which received aggregate gross proceeds of $ 100,000 .

The Company incurred interest expense related to the March 2022 Note of $ 1,296 for the year ended December 31, 2022, which included amortized imputed interest of $ 861 .

December 2022 Promissory Notes

9 unchanged sentences

The maturity dates of the December 2022 Notes could have been extended one or more times at the Company’s election, but in no event to a date later than September 6, 2024.

In addition, if the Company consummated a public offering, then upon the later to occur of (i) five business days after the Company receives the net cash proceeds therefrom or (ii) May 15, 2023, the Duggan February Note and the Zanganeh Note were to be prepaid by an amount equal to the lesser of (a) 100 % of the amount of the net proceeds of such offering and (b) the outstanding principal amount on such Notes.

On January 19, 2023, the Company provided notice to extend the term of the Duggan February Note and Duggan September Note to a maturity date of September 6, 2024.

Furthermore, on January 19, 2023, the Company and Mr.

Duggan rectified the Duggan February Note and Duggan September Note in order to correctly reflect the parties’ intent that the Company may only prepay (i) the Duggan February Note following the completion of a public rights offering to be conducted by Summit in the approximate amount of $ 500,000 , or a similar capital raise, in an amount equal to the lesser of (x) the net proceeds of the rights offering or such capital raise or (y) the full amount outstanding of the Duggan February Note, and (ii) Duggan September Note following the completion of a capital raising transaction subsequent to the rights offering in an amount equal to the lesser of (A) the net proceeds of such capital raise or (B) the full amount outstanding of the Duggan September Note.

Following the issuance of the two new Promissory Notes (the “Revised Duggan February Note” and the “Revised Duggan September Note”, respectively), the Duggan February Note and Duggan September Note were marked as “cancelled” on their face and replaced in their entirety by the Revised Duggan February Note and the Revised Duggan September Note (together with the Zanganeh Note, the “Notes”).

On February 15, 2023, the $ 20,000 Zanganeh Note matured and the Company repaid the outstanding principal balance.

In connection with the closing of the rights offering in 2023 (the “2023 Rights Offering”), the $ 400,000 Revised Duggan February Note matured and became due, and the Company repaid all principal and accrued interest thereunder using a combination of a portion of the cash proceeds from the 2023 Rights Offering and the extinguishment of a portion of the amount due equal to the subscription price of shares subscribed by Mr.

Duggan in the 2023 Rights Offering.

Summit Therapeutics Inc.

1 unchanged sentence

(in thousands, except share and per share data)

the Zanganeh Note were to be prepaid by an amount equal to the lesser of (a) 100 % of the amount of the net proceeds of such offering and (b) the outstanding principal amount on such Notes.

On January 19, 2023, the Company provided notice to extend the term of the Duggan February Note and Duggan September Note to a maturity date of September 6, 2024.

Furthermore, on January 19, 2023, the Company and Mr.

Duggan rectified the Duggan February Note and Duggan September Note in order to correctly reflect the parties’ intent that the Company may only prepay (i) the Duggan February Note following the completion of a public rights offering to be conducted by Summit in the approximate amount of $ 500,000 or a similar capital raise, in an amount equal to the lesser of (x) the net proceeds of the Rights Offering or such capital raise or (y) the full amount outstanding of the Duggan February Note, and (ii) Duggan September Note following the completion of a capital raising transaction subsequent to the 2023 Rights Offering (as defined in Note 17) in an amount equal to the lesser of (A) the net proceeds of such capital raise or (B) the full amount outstanding of the Duggan September Note.

Following the issuance of the two new Promissory Notes (the “Duggan Promissory Notes”), the Duggan February Note and Duggan September Note were marked as “cancelled” on their face and replaced in their entirety by the Duggan Promissory Notes (together with the Zanganeh Note, the "Notes").

The Notes accrued interest at an initial rate of 7.5 %.

All interest on the Notes was paid on the date of signing for the period through February 15, 2023.

Such prepaid interest was paid in a number of shares of the Company’s common stock, par value $ 0.01 ("Common Stock") equal to the dollar amount of such prepaid interest, divided by $ 0.7913 (the consolidated closing bid price immediately preceding the time the Company entered into the Note Purchase Agreement, plus $ 0.01 ), which was 9,720,291 shares.

For all applicable periods following February 15, 2023, interest accrued on the outstanding principal balance of the Notes at the US prime interest rate, as reported in the Wall Street Journal, plus 50 basis points, as adjusted monthly, for three months immediately following February 15, 2023, and thereafter at the US prime rate plus 300 basis points, as adjusted monthly.

Such prepaid interest was paid in a number of shares of the Company’s common stock equal to the dollar amount of such prepaid interest, divided by $ 0.7913 (the consolidated closing bid price immediately preceding the time the Company entered into the Note Purchase Agreement, plus $ 0.01 ), which was 9,720,291 shares.

For all applicable periods following February 15, 2023, interest accrued on the outstanding principal balance of the Notes at the U.S.

prime interest rate, as reported in the Wall Street Journal, plus 50 basis points, as adjusted monthly, for three months immediately following February 15, 2023, and thereafter at the U.S.

prime rate plus 300 basis points, as adjusted monthly.

Accrued interest was paid in cash, quarterly in arrears, on each of March 31, June 30, September 30 and December 31.

On February 15, 2023, the $ 20,000 Zanganeh Note matured and the Company repaid the outstanding principal balance.

In connection with the closing of the 2023 Rights Offering, the $ 400,000 Duggan Promissory Note matured and became due, and the Company satisfied all principal and accrued interest thereunder using a combination of a portion of the cash proceeds from the 2023 Rights Offering and the extinguishment of a portion of the amount due equal to the subscription price of shares subscribed by Mr.

Duggan in the 2023 Rights Offering.

Debt issuance costs associated with the Notes were $ 44 and were capitalized as part of the carrying value of the promissory notes payable to related parties.

Imputed interest was calculated as the difference between the expected interest payable and the deemed market rate of interest and is recorded as a debt discount at inception of the note payable with a credit to additional paid-in capital for notes payable to related parties.

The debt discount is amortized to interest expense using an effective interest rate method.

The effective interest rate of the Duggan February Note and Zanganeh Note was 8.9 % and the effective interest rate of the Duggan September Note was 11.3 %.

On February 17, 2024 the Duggan February Note was amended to extend the maturity date from September 6, 2024 to April 1, 2025.

For all applicable periods commencing February 17, 2024, interest accrued on the outstanding principal balance at the greater of 12 % or the US prime interest rate, as reported in the Wall Street Journal plus 350 basis points, as adjusted monthly, compounded quarterly.

On February 17, 2024, the Revised Duggan February Note was amended to extend the maturity date from September 6, 2024 to April 1, 2025.

For all applicable periods commencing February 17, 2024, interest accrued on the outstanding principal balance at the greater of 12 % or the U.S.

prime interest rate, as reported in the Wall Street Journal plus 350 basis points, as adjusted monthly, and compounded quarterly.

Interest was paid upon maturity of the loan.

In accordance with the applicable accounting standards, a short-term debt obligation should be excluded from current liabilities if the entity has both the intent and ability to refinance the obligation on a long-term basis.

The intent and ability can be demonstrated by the issuance of a long-term obligation to refinance the short-term obligation on a long-term basis after the date of an entity’s balance sheet but before that balance sheet is issued.

As a result of the amendment entered into on February 17, 2024 to extend the maturity date to April 1, 2025, the Company classified $ 100,000 of notes payable to related party outstanding as of December 31, 2023 as long-term notes payable.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

During the year ended December 31, 2024, the Company incurred interest expense of $ 8,686 related to promissory notes payable.

During the year ended December 31, 2023, the Company incurred interest expense of $ 16,461 which included amortized imputed interest of $ 761 .

During the year ended December 31, 2022, the Company incurred interest expense of $ 3,105 related to the December 2022 Notes which included amortized imputed interest of $ 395 .

As of December 31, 2024 and 2023, there was $ 0 and $ 120 , respectively, of accrued interest payable included within accrued expenses in the consolidated balance sheet.

As of October 1, 2024, the Company repaid the Duggan September Note in full, resulting in principal payments in the aggregate amount of $ 100,000 and accrued cash interest of $ 7,305 .

The debt discount was amortized to interest expense using an effective interest rate method.

The effective interest rate of the Revised Duggan February Note and Zanganeh Note was 8.9 % and the effective interest rate of the Revised Duggan September Note was 11.3 %.

On September 16, 2024, the Company used some of the proceeds raised from the September 2024 Private Placement (see Note 13 for further details) to repay $ 75,500 in principal on the Revised Duggan September Note.

On October 1, 2024, the Company repaid the remaining outstanding balance of the Revised Duggan September Note in full, resulting in principal payments of $ 24,500 and accrued cash interest of $ 7,305 .

As of December 31, 2025 and 2024, the Company had no debt.

During the year ended December 31, 2025, the Company incurred no interest expense.

During the year ended December 31, 2024, the Company incurred interest expense of $ 8,686 related to the Revised Duggan September Note.

Stockholders' Equity

3 unchanged sentences

As of December 31, 2025 and December 31, 2024, the Company had 775,371,200 shares and 737,626,004 shares of Common Stock issued and outstanding, respectively.

In August 2022, the Company announced the closing of its 2022 rights offering (“2022 Rights Offering”).

The rights offering commenced on July 18, 2022, and the associated subscription rights expired on August 8, 2022.

The 2022 Rights Offering received aggregate gross proceeds of $ 100,000 from the sale of 103,092,783 shares of common stock.

Duggan and Dr.

Zanganeh fully subscribed to their respective basic subscription rights and oversubscribed, at a price per share of $ 0.97 .

Offering costs of $ 111 were incurred.

On December 6, 2022, the Company announced a rights offering for its existing shareholders to participate in the purchase of additional shares of its Common Stock for $ 1.05 per share (the “2023 Rights Offering”).

On December 6, 2022, the Company announced the 2023 Rights Offering for its existing shareholders to participate in the purchase of additional shares of its Common Stock for $ 1.05 per share.

The 2023 Rights Offering commenced on February 7, 2023 and the associated subscription rights expired on March 1, 2023.

23 unchanged sentences

and Baker Brothers Life Sciences, L.P., affiliates of Baker Bros.

Advisors, L.P.

(the “Investors”), for the sale by the Company in a private placement (the “June 2024 Private Placement”) of 22,222,222 shares (the “Shares”) of Common Stock, at a purchase price of $ 9.00 per share, for an aggregate purchase price of approximately $ 200,000 .

Advisors, L.P., for the sale by the Company in a private placement (the “June 2024 Private Placement”) of 22,222,222 shares (the “Shares”) of Common Stock, at a purchase price of $ 9.00 per share, for an aggregate purchase price of approximately $ 200,000 .

The closing of the June 2024 Private Placement was June 6, 2024.

1 unchanged sentence

The representations, warranties and covenants contained in the Purchase Agreement were made only for purposes of the Purchase Agreement and as of specific dates, were solely for the benefit of the parties to such agreements and were subject to limitations agreed upon by the contracting parties.

On June 3, 2024, in connection with the Purchase Agreement, the Company entered into a Registration Rights Agreement with the Investors (the “Registration Rights Agreement”).

On June 3, 2024, in connection with the Purchase Agreement, the Company entered into a Registration Rights Agreement with certain investors (the “Registration Rights Agreement”).

The Registration Rights Agreement provides, among other things, that the Company will as soon as reasonably practicable, file with the SEC a registration statement registering the resale of the shares.

2 unchanged sentences

September 2024 PIPE

On September 11, 2024, the Company entered into securities purchase agreements (the “September 2024 Purchase Agreements”) with multiple leading biotech institutional investors and individual accredited investors (the “September 2024 Investors”), for the sale by the Company in a private placement (the “September 2024 Private Placement”) of an aggregate of 10,352,418 shares (the “September 2024 Shares”) of the Company’s common stock, par value $ 0.01 per share of Common Stock, at purchase price of $ 22.70 per Share, which was the closing price of the Common Stock on September 11, 2024, for aggregate gross proceeds to the Company of approximately $ 235,000 , with offering costs of $ 140 .

On September 11, 2024, the Company entered into securities purchase agreements (the “September 2024 Purchase Agreements”) with multiple biotech institutional investors and individual accredited investors, for the sale by the Company in a private placement (the “September 2024 Private Placement”) for an aggregate of 10,352,418 shares of the Company’s Common Stock, par value $ 0.01 per share of Common Stock, at purchase price of $ 22.70 per share, which was the closing price of the Common Stock on September 11, 2024, for aggregate gross proceeds to the Company of approximately $ 235,000 , with offering costs of $ 140 .

All of the Company's Section 16 officers participated in the capital raise.

A total of $ 79,000 was raised by the Company's Co-Chief Executive Officer (“CEO”), Executive Chairman and majority stockholder, its Co-CEO and the President and member of the Company's Board of Directors (the "Board"), its Chief Operating Officer (“COO”), Chief Financial Officer (“CFO”), and member of the Board, its Chief Accounting Officer ("CAO"), and a member of the Board of Directors, who invested via a controlled entity.

A total of $ 79,000 was raised by the Company's Co-Chief Executive Officer (“CEO”), Executive Chairman and majority stockholder, its CEO and the President and member of the Company's Board of Directors (the “Board”), its Chief Operating Officer (“COO”), Chief Financial Officer (“CFO”), and member of the Board, its Chief Accounting Officer (“CAO”), and a member of the Board, who invested via a controlled entity.

The remaining $ 156,000 was raised with multiple leading biotech institutional investors.

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The closing of the September 2024 Private Placement was September 13, 2024.

The Purchase Agreements contain customary representations, warranties and covenants by the Company, customary indemnification obligations of the Company, including for liabilities under the Securities Act, as amended (the “Securities Act”), other obligations of the parties and termination provisions.

The representations, warranties and covenants contained in the Purchase Agreements were made only for purposes

The September 2024 Purchase Agreements contain customary representations, warranties and covenants by the Company, customary indemnification obligations of the Company, including for liabilities under the Securities Act, as amended (the “Securities Act”), other obligations of the parties and termination provisions.

The representations, warranties and covenants contained in the September 2024 Purchase

Summit Therapeutics Inc.

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(in thousands, except share and per share data)

of the Purchase Agreements and as of specific dates, were solely for the benefit of the parties to such agreements and were subject to limitations agreed upon by the contracting parties.

On September 11, 2024, in connection with the September 2024 Purchase Agreements, the Company entered into Registration Rights Agreements with the Investors (the “September 2024 Registration Rights Agreements”).

Agreements were made only for purposes of the September 2024 Purchase Agreements and as of specific dates, were solely for the benefit of the parties to such agreements and were subject to limitations agreed upon by the contracting parties.

On September 11, 2024, in connection with the September 2024 Purchase Agreements, the Company entered into Registration Rights Agreements with certain investors (the “September 2024 Registration Rights Agreements”).

The September 2024 Registration Rights Agreements provide, among other things, that the Company will as soon as reasonably practicable file with the SEC a registration statement registering the resale of the shares.

The Company filed the registration statement on September 19, 2024, which was automatically effective upon filing.

October 2025 PIPE

On October 21, 2025, the Company entered into securities purchase agreements (the “October 2025 Purchase Agreements”) with multiple biotech institutional investors and individual accredited investors, for the sale by the Company in a private placement for an aggregate of 26,682,846 shares of the Company’s Common Stock, par value $ 0.01 per share of Common Stock, at purchase price of $ 18.74 per Share, which was the closing price of the Common Stock on October 21, 2025, for aggregate gross proceeds to the Company of approximately $ 500,037 , with immaterial offering costs.

The private placement transaction was completed in October 2025.

All of the Company's Section 16 officers participated in the capital raise.

The Company's Co-CEO, Executive Chairman and majority stockholder, its Co-CEO and the President and member of the Board, its COO, CFO, and member of the Board, its CAO, and certain non-executive employees and other related persons purchased an aggregate of 14,514,402 shares of Common Stock for gross proceeds of approximately $ 272,000 .

Additionally, Akeso purchased 533,617 shares of Common Stock for gross proceeds of approximately $ 10,000 .

The remaining $ 218,037 was raised with multiple leading biotech institutional investors.

The October 2025 Purchase Agreements contain customary representations, warranties and covenants by the Company, customary indemnification obligations of the Company, including for liabilities under the Securities Act, as amended (the “Securities Act”), other obligations of the parties and termination provisions.

The representations, warranties and covenants contained in the October 2025 Purchase Agreements were made only for purposes of the October 2025 Purchase Agreements and as of specific dates, were solely for the benefit of the parties to such agreements and were subject to limitations agreed upon by the contracting parties.

On October 21, 2025, in connection with the October 2025 Purchase Agreements, the Company entered into Registration Rights Agreements with the Investors (the “October 2025 Registration Rights Agreements”).

The October 2025 Registration Rights Agreements provide, among other things, that the Company will as soon as reasonably practicable, and in any event by no later than December 19, 2025, file with the SEC a registration statement registering the resale of the shares.

The Company filed the registration statement on October 29, 2025, which was automatically effective upon filing.

At-the-Market Offering (ATM Offering)

On May 13, 2024, the Company entered into an at-the-market sales agreement (the "ATM Agreement") pursuant to which the Company may, subject to the terms and conditions set forth in the agreement offer and sell, from time to time, through or to the agents, acting as agents or principal, shares of the Company's common stock, par value $ 0.01 , having an aggregate offering price of up to $ 90,000 .

From the date of the ATM Agreement through December 31, 2024, the Company sold 1,807,093 shares of common stock under the ATM Agreement at a weighted-average price of $ 24.47 per share, for gross proceeds of $ 44,223 .

The remaining availability under the ATM Agreement as of December 31, 2024 is approximately $ 45,777 .

The Company has received net proceeds of $ 43,033 , which is net of sales commissions and other offering fees of approximately $ 1,190 .

On May 13, 2024, the Company entered into an at-the-market (“ATM”) sales agreement (the “Original Distribution Agreement”) pursuant to which the Company may, subject to the terms and conditions set forth in the agreement offer and sell, from time to time, through or to the agents, acting as agents or principal, shares of the Company's Common Stock, par value $ 0.01 , having an aggregate offering price of up to $ 90,000 .

On August 11, 2025, the Company entered into an amendment to the Original Distribution Agreement (as amended, the “Distribution Agreement”), which among other things, increased the aggregate offering price of Common Stock that the Company may offer and sell from time to time through the sales agent under the Distribution Agreement by an additional $ 360,000 .

From the date of the Original Distribution Agreement through December 31, 2025, the Company sold 7,146,432 shares of Common Stock under the ATM at a weighted-average price of $ 21.09 per share, for gross proceeds of $ 150,721 , with commissions and fees of approximately $ 3,160 .

The remaining gross proceeds available under the Distribution Agreement as of December 31, 2025 was approximately $ 299,279 .

The Company plans to use the net proceeds from this offering for working capital and general corporate purposes.

As part of the private placement on December 24, 2019, the participating investors were granted warrants with the right to subscribe for 5,261,350 shares of common stock at an exercise price of $ 1.58 , exercisable any time in the period commencing on the date falling six months following December 24, 2019 and ending on the tenth anniversary of admission.

Each warrant entitles the warrant holder to subscribe in cash for one share.

Shares of common stock allotted pursuant to the exercise of the warrant will rank in full for all dividends and other distributions with a record date after the exercise date with the shares of common stock in issue at that date.

The Company has the option to require the warrant holder to exercise some or all of the outstanding warrants after the third anniversary date if the ten-day volume weighted average price of the shares of common stock as reported on Nasdaq represents a premium of at least 50 percent to the exercise price.

The warrants are classified within stockholders’ equity as they are indexed to the Company’s shares of common stock and require settlement in its shares of common stock with no provision for any cash settlement.

Also, as part of the private placement on December 24, 2019, certain consultants were granted warrants with the right to subscribe for 3,358,732 shares of common stock in exchange for certain services.

The warrants have an exercise price of $ 1.44 and vested quarterly over three years .

If the consulting agreement terminated prior to three years after the date of the grant, all unvested warrants were to be deemed cancelled.

On June 30, 2020, the consulting agreement was terminated and 2,798,945 warrants cancelled immediately.

Warrants granted over shares of common stock to consultants in exchange of certain services are similar to stock-based compensation.

The following table summarizes the Company’s warrants activity for the year ended December 31, 2024:

Number of share warrants

Weighted average exercise price Weighted average remaining contractual term Aggregate intrinsic value

Outstanding as of December 31, 2023 5,015,642 $ 1.57 5.92 years $ 5,194

Exercised ( 385,654 ) $ 1.55

Outstanding as of December 31, 2024 4,629,988 $ 1.58 4.98 years $ 75,300

Summit Therapeutics Inc.

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As of December 31, 2025, the Company had no outstanding warrants.

As of December 31, 2024, the Company had outstanding and exercisable warrants of 4,629,988 with a weighted average exercise price of $ 1.58 .

During the year ended December 31, 2025, 4,629,988 warrants were exercised with a weighted average exercise price of $ 1.58 .

Stock-Based Compensation

2016 Long Term Incentive Plan

Upon the effectiveness of the 2020 Stock Incentive Plan, no additional grants will be made under the 2016 Long Term Incentive Plan, (the “2016 Plan”) and any outstanding awards continue with their original terms.

Upon the effectiveness of the 2020 Stock Incentive Plan (the “2020 Plan”), no additional grants will be made under the 2016 Long Term Incentive Plan, (the “2016 Plan”) and any outstanding awards continue with their original terms.

2020 Stock Award Plan

In September 2020, the Company’s Board of Directors approved the 2020 Stock Incentive Plan (the “2020 Plan”), which became effective on September 21, 2020.

In September 2020, the Company’s Board of Directors approved the 2020 Stock Incentive Plan, which became effective on September 21, 2020.

The 2020 plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards.

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The number of shares of Common Stock that may be issued under the 2020 Plan will automatically increase on each January 1, beginning in 2021 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2030, equal to the lesser of (i) 6,400,000 shares of Common Stock, (ii) 4 % of the common shares outstanding on the final day of the immediately preceding calendar year and (iii) an amount as determined by the Company’s Board of Directors.

On July 27, 2022, the Company held a Special Meeting of Stockholders (the “Special Meeting”) whereby the following matters were submitted to a vote of the Company’s stockholders at the Special Meeting and the Board of Directors resolved the following:

(i) an amendment to the Company’s Restated Certificate of Incorporation, dated September 18, 2020, to increase the number of authorized shares of common stock by 100,000,000 (from 250,000,000 to 350,000,000 );

and (ii) an amendment to the Summit Therapeutics Inc.

2020 Stock Incentive Plan (the “Plan”) to increase the number of shares of the Company’s common stock issuable under the Plan by 8,000,000 shares.

On October 12, 2023, the Company held a Special Meeting of Stockholders (the “October Special Meeting”) whereby the following matter was submitted to a vote of the Company’s stockholders at the Special Meeting and the Board of Directors resolved the following:

an amendment to the Summit Therapeutics Inc.

2020 Stock Incentive Plan to increase the number of shares of the Company ’ s common stock issuable under the Plan by 70,000,000 shares.

As of December 31, 2025, there are 2,643,200 shares available to be issued under the 2020 Plan.

The Company currently grants stock options to employees and directors under the 2020 Stock Incentive Plan (the “2020 Plan”) and formerly, the Company granted stock options under the 2016 Long Term Incentive Plan (the “2016 Plan”).

The 2020 Plan is administered by the Compensation Committee of the Board.

The 2020 Plan is administered by the Compensation Committee of the Company's Board of Directors.

The 2020 Plan is intended to attract and retain employees and directors and provide an incentive for these individuals to assist the Company to achieve long-range performance goals and to enable these individuals to participate in the long-term growth of the Company.

Based on the provisions of the 2020 Plan, the number of shares of common stock available for issuance under the 2020 Plan increased by 6,400,000 shares on January 1, 2025.

On September 18, 2025, the Board approved an increase of 8,000,000 shares of common stock available for issuance under the 2020 Plan (the “Incremental Pool”), subject to the approval of the holders of a majority of the shares voting at the Company’s stockholder meeting.

As of December 31, 2025, there are 3,082,075 shares available to be issued under the Incremental Pool.

The Company’s consolidated financial statements have treated the grant date of such stock options as the date Board approval was obtained.

On May 3, 2024, the Board adopted the 2024 Inducement Pool (the “Inducement Pool”), which mirrors the terms of the 2020 Plan, with a total of 2,000,000 shares of Common Stock reserved for issuance under the Inducement Pool.

Effective January 22, 2025, the number of shares of common stock available under the Inducement Pool increased by 2,000,000 shares.

The Inducement Pool provides for the grant of non-qualified stock options and was approved by the Compensation Committee of the Board without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Listing Rules.

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Stock Options

Time-based Stock Options

The Company estimates the fair value of stock options granted to employees and directors using the Black-Scholes valuation model.

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Expected volatility 124.9 % - 142.5 %

107.8 % 98.1 %

Expected annual dividends per share — % — % — %

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(in thousands, except share and per share data)

The following table summarizes the Company’s time-based stock option activity for the year ended December 31, 2024:

Number of share options Weighted average exercise price Weighted average remaining contractual term Aggregate intrinsic value

Outstanding as of December 31, 2023 54,209,289 $ 2.28 9.3 years $ 42,574

Granted 8,175,224 $ 6.07

Forfeited ( 1,771,037 ) $ 2.19

Exercised ( 797,486 ) $ 2.36

Outstanding as of December 31, 2024 59,815,990 $ 2.80 8.5 years $ 901,139

Outstanding as of December 31, 2024 - vested and expected to vest 55,670,146 $ 2.81 8.4 years $ 838,095

Exercisable at December 31, 2024 18,357,551 $ 3.10 7.7 years $ 270,696

As of December 31, 2024, there was $ 49,901 total unrecognized compensation cost related to unvested time-based stock option grants.

The unvested amount is expected to be recognized over a weighted average period of approximately 2.2 years.

Performance and Market-based Stock Options

The Compensation Committee of the Company’s Board of Directors and management approved 2,825,000 option grants to its executives and certain employees of the Company during the year ended December 31, 2024, which will vest based upon certain revenue and market-based performance conditions.

The Company uses a Monte Carlo simulation model to estimate the fair value of Performance and Market-based Stock Options at the date of grant which utilizes multiple input variables to estimate the probability that the market condition will be achieved.

Key assumptions used in the model include the risk-free interest rate, which reflects the US Treasury Constant Maturity Yield with a term commensurate with the contractual term of the award, and stock price volatility, which is derived based on the historical volatility of the Company’s stock.

The following table summarizes the Company’s performance and market-based stock option activity for the year ended December 31, 2024:

Number of share options Weighted average exercise price Weighted average remaining contractual term Aggregate intrinsic value

Outstanding as of December 31, 2023 46,654,220 $ 1.62 9.6 years $ 46,237

The following table summarizes the Company’s stock option activity for the year ended December 31, 2025:

Number of share options Weighted average exercise price Weighted average remaining contractual term (years)

Aggregate intrinsic value

Outstanding at December 31, 2024* 108,136,310 $ 2.34 8.6 $ 1,677,748

Granted* 13,297,732 19.20

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Exercised ( 953,564 ) 3.99

Outstanding as of December 31, 2024 48,320,320 $ 1.77 8.7 years $ 776,609

Outstanding as of December 31, 2024 - vested and expected to vest 9,104,344 $ 1.63 8.6 years $ 147,583

Exercisable at December 31, 2024 9,104,344 $ 1.63 8.6 years $ 147,583

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Outstanding at December 31, 2025 119,464,728 $ 4.14 7.8 $ 1,618,734

Vested and expected to vest at December 31, 2025 110,536,687 $ 3.86 7.7 $ 1,527,454

Exercisable at December 31, 2025 64,834,314 $ 2.32 7.4 $ 983,902

* The stock option activity in the table above includes performance-based options outstanding as of December 31, 2024 of 48,220,320 of which 39,013,976 options were unvested and converted to time-based vesting.

During the three months ended March 31, 2025, the company granted 5,475,000 performance-based options which were modified to time-based vesting during the three months ended June 30, 2025.

During the second quarter of 2025, the Compensation Committee of the Board of Directors approved a modification to the Company's outstanding unvested performance-based stock option awards for certain employees and executives that will require only the service-based vesting requirements to continue to be satisfied in order to become fully vested, subject to employee consent.

The Company accounted for this change as a Type III modification (improbable-to-probable) in accordance with the requirements of Accounting Standards Codification Topic 718 (ASC 718).

As a result, 44,488,976 options were valued on the modification date.

The Company is recognizing the newly assessed measurement date fair value of the awards as compensation expense over the remaining vesting period.

During the year ended December 31, 2025, the Company recognized expense of $ 650,959 associated with the modification.

As of December 31, 2025, the unrecognized compensation cost associated with the modification was $ 214,295 and is expected to be expensed over a weighted-average recognition period of approximately 1.6 years.

The weighted-average grant-date fair value of stock options granted during the years ended December 31, 2025, 2024 and 2023 was $ 17.10 , $ 3.40 and $ 1.41 , per share, respectively.

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The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock.

During the year ended December 31, 2024, the Company achieved certain market conditions, which resulted in 9,151,844 shares vesting and acceleration of $ 7,050 of stock-based compensation expense related to the accelerated vesting of these awards.

As of December 31, 2024, the number of unvested performance-based stock options that were deemed to be not probable of vesting and the related unrecognized stock-based compensation expense is 39,215,976 and $ 52,700 , respectively.

As of December 31, 2025, there was $ 345,387 total unrecognized compensation cost related to unvested stock option grants.

The unvested amount is expected to be recognized over a weighted average period of approximately 1.8 years.

Stock-Based Compensation

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Research and development $ 218,564 $ 16,007 $ 4,408

$ 16,007 $ 4,408 $ 4,303

General and administrative 513,856 34,974 9,700

34,974 9,700 7,645

Total stock-based compensation $ 732,420 $ 50,981 $ 14,108

$ 50,981 $ 14,108 $ 11,948

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

The following table summarizes stock-based compensation expense associated with each of our stock-based compensation arrangements:

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Time-based stock options $ 731,358 $ 39,349 $ 12,606

$ 39,349 $ 12,606 $ 11,630

Performance and market-based stock options — 11,033 1,318

11,033 1,318 84

Employee stock purchase plan 1,062 599 184

Total stock-based compensation $ 732,420 $ 50,981 $ 14,108

$ 50,981 $ 14,108 $ 11,948

Commitments and Contingencies

Fixed asset purchase commitments

At December 31, 2024 and 2023, the Company had no capital commitments.

Lease commitments

Refer to Note 15 for a discussion of the Company’s lease commitments.

Debt commitments

Refer to Note 16 for discussion of promissory notes payable to related parties.

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

Other commitments

The Company enters into contracts in the normal course of business with various third parties for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes.

Most contracts provide for termination upon notice, and therefore are cancellable contracts.

As of December 31, 2024, total unconditional purchase obligations, excluding leases commitments, are estimated to be approximately $ 13,900 .

The Company has certain commitments under its agreements with Akeso.

The License Agreement with Akeso also contains certain manufacturing and purchase commitments.

As of December 31, 2024, the Company is unable to estimate the amount, timing or likelihood of achieving the milestones, making future product sales or assessing estimated forecasts for manufacturing and supplied materials which these contingent payment obligations relate to.

Indemnifications

The Company’s certificate of incorporation provides that it will indemnify the directors and officers to the fullest extent permitted by Delaware law.

In addition, the Company has entered into indemnification agreements with all of the directors and executive officers.

These indemnification agreements may require the Company, among other things, to indemnify each such director or executive officer for some expenses, including attorneys’ fees, judgments, fines, and settlement amounts incurred by him or her in any action or proceeding arising out of his or her service as one of the Company’s directors or executive officers.

The Company believes the fair value for these indemnification obligations is minimal.

Accordingly, the Company has not recognized any liabilities relating to these obligations as of December 31, 2024.

Legal Proceedings

The Company is not currently subject to any material legal proceedings.

Related Party Transactions

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The agreement was further amended to include additional space, as noted below under the August 2, 2024 Third Amendment to Sublease Agreement with Maky Zanganeh and Associates, Inc.

During the years ended December 31, 2025, 2024 and 2023, payments of $ 834 , $ 795 , and $ 762 , respectively, were made pursuant to the first and third amendments to the Sublease Agreement.

July 29, 2022 Second Amendment to Sublease Agreement with Maky Zanganeh and Associates, Inc.

On July 29, 2022, the Company entered into a second amendment, dated August 1, 2022, to its existing sublease agreement with MZA, described above.

On July 29, 2022, the Company entered into a second amendment to its existing sublease agreement with MZA, described above.

The second amendment was effective as of August 1, 2022 and expires on December 31, 2025.

The second amendment includes an additional 1,277 square feet (the "Expansion Premises") of office space at 2882 Sand Hill Road, Menlo Park, California.

The second amendment includes an additional 1,277 square feet of office space at 2882 Sand Hill Road, Menlo Park, California.

The rent payable under the terms of the sublease is equivalent to the proportionate share of the net payable by MZA to the third-party landlord, based on the square footage of office space sublet by the Company, and no mark-up has been applied.

During the year ended December 31, 2024, 2023 and 2022 payments to MZA related to the above leases were $ 1,019 , $ 1,018 , and $ 598 were made pursuant to the second amendment to the Sublease Agreement.

During the years ended December 31, 2025, 2024 and 2023, payments of $ 232 , $ 224 and $ 218 , respectively, were made pursuant to the second amendment to the Sublease Agreement.

April 1, 2024 Miami Sublease Agreements

On April 1, 2024, the Company entered into two sublease agreements of its Miami headquarters location, one with Genius 24C Inc.

("Genius"), an affiliate of the Company's CEO, Robert W.

Duggan (the "Genius Sublease Agreement") and one with Duggan Investments Research LLC ("Investments Research"), also an affiliate of the Company's CEO, Robert W.

(“Genius”), an affiliate of the Company’s Co-CEO, Robert W.

Duggan (the “Genius Sublease Agreement”) and one with Duggan Investments Research LLC (“Investments Research”), also an affiliate of the Company's Co-CEO, Robert W.

Duggan (the “Investments Research Sublease Agreement”).

Pursuant to the Genius Sublease Agreement, Genius will sublease from the Company 848 square feet of office space in the Miami HQ for a sixty-two month term for total rental payments of

Pursuant to the Genius Sublease Agreement, Genius sublet from the Company 848 square feet of office space in the Miami HQ for a sixty-two month term for total rental payments of approximately $ 446 .

Pursuant to the Investments Research Sublease Agreement, Investments Research sublet from the Company 848 square feet of office space in the Miami HQ for a sixty-two month term for total rental payments of approximately $ 446 .

During the years ended December 31, 2025 and 2024, the Company recognized $ 186 and $ 156 , respectively, of sublease income recorded net of operating lease expenses.

August 2, 2024 Third Amendment to Sublease Agreement with Maky Zanganeh and Associates, Inc.

On August 2, 2024, the Company entered into a third amendment to its existing sublease agreement with MZA.

The third amendment was effective August 1, 2024 and included an additional space of 145 square feet of office space located at 2882

Summit Therapeutics Inc.

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(in thousands, except share and per share data)

approximately $ 446 .

Pursuant to the Investments Research Sublease Agreement, Investments Research will sublease from the Company 848 square feet of office space in the Miami HQ for a sixty-two month term for total rental payments of approximately $ 446 .

During the year ended December 31, 2024, the Company recognized $ 156 of sublease income recorded net of operating lease expenses.

August 2, 2024 Third Amendment to Sublease Agreement with Maky Zanganeh and Associates, Inc.

On August 2, 2024, the Company entered into a third amendment to its existing sublease agreement with MZA.

The third amendment has an effective date of August 1, 2024, which includes an additional space of 145 square feet of office space at 2882 Sand Hill Road, Menlo Park, California.

Sand Hill Road, Menlo Park, California.

The Company continues to be obligated to pay its proportionate share of the net payable by MZA to the third-party landlord, which is revised to 93.6 % as of the effective date, based on the square footage of office space sublet by the landlord.

2022 Rights Offering

Refer to Note 17 for a discussion on the 2022 Rights Offering.

Promissory Note Payable to Related Parties

Refer to Note 16 for a discussion of the promissory note payable to related parties issued December 6, 2022 and fully repaid on October 1, 2024.

Akeso License Agreement

Upon the closing of the License Agreement, the Board of Directors (the “Board”) of the Company appointed Dr.

Refer to Note 12 for disclosure of the promissory note payable to related parties issued December 6, 2022 and fully repaid as of October 1, 2024.

Akeso Agreements

Upon the closing of the License Agreement, the Board appointed Dr.

Yu (Michelle) Xia to serve as a member of the Board pursuant to the terms of the License Agreement.

Xia is the founder of Akeso, Inc., and has been the chairwoman, president and CEO of the Company since its inception in 2012.

For details on the License Agreement and Second Amendment entered into on June 3, 2024, see Note 5.

Furthermore, in connection with the License Agreement, the Company agreed to purchase a certain portion of drug substance

and/or drug product for clinical and commercial supply and to enter into a supply agreement with Akeso.

During the years ended December 31, 2024 and 2023, respectively, the Company paid $ 39,198 and $ 2,500 to Akeso.

As of December 31, 2024 and 2023, respectively, the Company included in accrued expenses approximately $ 3,956 and $ 3,619 due to Akeso.

Xia is the founder of Akeso, and has been the chairwoman, president and CEO of Akeso since its inception in 2012.

Furthermore, in connection with the License Agreement, the Company also entered into a Supply Agreement with Akeso, pursuant to which Summit agreed to purchase a certain portion of drug substance for clinical and commercial supply (the “Supply Agreement”).

Refer to Note 4 for details on the License Agreement and Second Amendment.

In addition to the License and Second Amendment and supply agreements, the Company also entered into various clinical services agreements with Akeso.

During the years ended December 31, 2025, 2024 and 2023, the Company incurred research and development expenses of $ 46,133 , $ 24,635 and $ 6,207 , respectively, under these agreements with Akeso.

As of December 31, 2025 and 2024 the Company included in accrued expenses, related to Akeso, $ 1,215 and $ 3,956 , respectively.

2023 Rights Offering

Refer to Note 13 for a discussion on the 2023 Rights Offering.

Registration of Shares

On March 17, 2023, the Company filed a registration statement on Form S-3 to register for resale the following shares of the Company’s common stock at $ 0.01 par value:

(i) 10,000,000 shares of Common Stock issued on January 17, 2023 in connection with the License Agreement with Akeso pursuant to which the Company issued Akeso such shares;

and (ii) the 9,346,434 and 373,857 shares of Common Stock issued in December 2022 to the Company’s Co-Chief Executive Officers, Mr.

Duggan and Dr.

Zanganeh, respectively, as payment of prepaid interest in connection with the Note Purchase Agreement dated December 6, 2022 between Mr.

Zanganeh and the Company.

On April 27, 2023, the SEC issued the Company a Notice of Effectiveness for the registration statement on Form S-3.

Private Placements

On October 16, 2023, the Company announced the appointment of Mr.

Soni as its Chief Operating Officer, effective immediately.

Soni has been a part of the Company’s Board of Directors since 2019.

In conjunction with his

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

appointment, Mr.

Soni entered into a share purchase agreement with the Company to purchase $ 5,000 of its common stock via a private placement.

The transaction was effective October 13, 2023 with a closing price of $ 1.68 , resulting in the purchase of 2,976,190 shares of the Company’s common stock.

October 2023 PIPE

Refer to Note 13 for a discussion on the participation by related parties in October 2023 PIPE.

September 2024 PIPE

On September 11, 2024, the Company's Section 16 officers participated in the "September 2024 Purchase Agreements" along with multiple leading biotech institutional investors, for the sale by the Company in the September 2024 Private Placement for an aggregate of 10,352,418 shares of the Company’s common stock, par value $ 0.01 per share of Common Stock, at purchase price of $ 22.70 per Share, which was the closing price of the Common Stock on September 11, 2024, for aggregate gross proceeds to the Company of approximately $ 235,000 .

The Company’s CEO and Executive Chairman, Mr.

Duggan, purchased 3,325,991 shares for an aggregate purchase price of $ 75,500 , CEO, President and member of its Board, Dr.

Mahkam Zanganeh, purchased 44,052 shares for an aggregate purchase price of $ 1,000 , COO and CFO, Manmeet S.

Soni, purchased 44,052 shares for an aggregate purchase price of $ 1,000 , and member of the Board, Jeff Huber, through his controlled entity, Caspian Capital LLC, purchased 44,052 shares for an aggregate purchase price of $ 1,000 , with their collective participation in the September 2024 Private Placement totaling 3,458,147 shares of Common Stock for an aggregate purchase price of $ 78,500 .

The Company used some of the proceeds raised from the September 2024 Private Placement to repay $ 75,500 in principal on the Duggan September Note.

See Note 16 for additional details regarding the promissory note payable to a related party.

Refer to Note 13 for a discussion on the participation by related parties in September 2024 PIPE.

October 2025 PIPE

Refer to Note 13 for a discussion on the participation by related parties in October 2025 PIPE.

Warrants Exercise

In March 2025, Mr.

Duggan, the Company’s Co-Chief Executive Officer, exercised 2,936,221 of the 3,985,055 warrants which he received in connection with a private placement completed by the Company with Mr.

Duggan and other investors on December 24, 2019, resulting in the purchase of 2,936,221 shares of common stock at an exercise price of $ 1.58 .

On April 8, 2025, Mr.

Duggan completed the exercise of the remaining warrants received in the December 24, 2019 private placement, resulting in the purchase of 1,048,834 shares of common stock at an exercise price of $ 1.58 .

In October 2024, the Shaun Zanganeh Irrevocable Trust exercised a warrant to purchase 315,681 shares of Common Stock.

In December 2023, Dr.

Zanganeh exercised 805,495 shares of warrants.

Refer to Note 13 for the warrants exercise activity for the year ended December 31, 2025.

Professional Services

During the year ended December 31, 2025, the Company engaged the law firm Wilson Sonsini Goodrich & Rosati P.C.

(“WSGR”), where Mr.

Clark, a member of the Board, is a partner.

Payments to be made by the Company to WSGR

Summit Therapeutics Inc.

Notes to Consolidated Financial Statements

(in thousands, except share and per share data)

were approved by the Audit Committee in accordance with its Related Party Transaction Policy.

For the year ended December 31, 2025, the Company incurred expenses for legal services rendered by WSGR totaling approximately $ 1.4 million included in general and administrative expenses.

Commitments and Contingencies

Fixed asset purchase commitments

At December 31, 2025 and 2024, the Company had no capital commitments.

Lease commitments

Refer to Note 11 for a discussion of the Company’s lease commitments.

Other commitments

Most contracts provide for termination upon notice, and therefore are cancellable contracts.

The majority of these commitments are due within one year .

As of December 31, 2025, total unconditional purchase obligations, excluding leases commitments, are estimated to be approximately $ 17,976 .

The Company has certain commitments under its agreements with Akeso.

The License Agreement also contains certain manufacturing and purchase commitments.

As of December 31, 2025, the Company is unable to estimate the amount, timing or likelihood of achieving the milestones, making future product sales or assessing estimated forecasts for manufacturing and supplied materials which these contingent payment obligations relate to.

Legal Proceedings

Litigation Relating to the December 2022 Notes Entered into in Connection with the License Agreement

On March 17, 2025, Rainaldi Revocable Trust, a purported stockholder of the Company, filed a derivative lawsuit in the Delaware Court of Chancery against certain of the Company’s current and former directors and the Company, solely as a nominal defendant, concerning the December 2022 Notes entered into by the Company, Mr.

Duggan and Dr.

Zanganeh in connection with the License Agreement.

The suit asserts claims for breach of fiduciary duty and unjust enrichment and seeks, among other things, unspecified damages, rescission of the shares that Mr.

Duggan and Dr.

Zanganeh received as part of prepaid interest payments under the December 2022 Notes, as well as attorneys’ fees and costs.

Defendants’ Motion to Dismiss the complaint was filed on May 16, 2025.

Plaintiff filed the Motion to Certify certain constitutional questions to the Delaware Supreme Court on May 29, 2025.

Defendants agreed to a stipulation staying briefing on the Motion to Certify and the Motion to Dismiss pending the Delaware Supreme Court’s decision in another case involving substantially the same constitutional questions.

On June 18, 2025, the Court granted such stipulation.

Defendants believe that Plaintiff's allegations are without merit and plan to vigorously defend against its claims

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 9A. Controls and Procedures