Summit Therapeutics Inc. 10-K

Item 9A. Controls and Procedures Evaluation of Disclosure Controls and Procedures 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. Disclosure controls and procedures include, without limitation, controls and procedures 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 accumulated and communicated to the company’s management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure. There are inherent limitations to the effectiveness of any system of disclosure controls and procedures, including the possibility of human error and the circumvention or overriding of the controls and procedures. Accordingly, even effective disclosure controls and procedures can only provide reasonable assurance of achieving their control objectives. Based upon our evaluation of our disclosure controls and procedures as o f December 31, 2025 , our Co-Chief Executive Officer and Executive Chairman and our Co-Chief Executive Officer, President and Director (our Principal Executive Officers), and our Chief Operating Officer, Chief Financial Officer and Director (our Principal Financial Officer) concluded that, as of such date, our disclosure controls and procedures were effective at a reasonable level of assurance. Management’s Report on Internal Control Over Financial Reporting Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Our internal control over financial reporting is a process designed, under the supervision of the Co-Chief Executive Officers (our Principal Executive Officers), and our Chief Operating Officer and Chief Financial Officer (our Principal Financial Officer), to provide reasonable assurance regarding the reliability of financial reporting and the preparation of our financial statements for external reporting purposes in accordance with generally accepted accounting principles. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of the effectiveness of internal control to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. Our management has assessed the effectiveness of internal control over financial reporting as of December 31, 2025, based on the “Internal Control—Integrated Framework” issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO) in 2013. 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, 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 There were no changes in our internal control over financial reporting (as defined in Rules 13a‑15(f) and 15d‑15(f) under the Exchange Act) during the quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting. Item 9B. Other Information Rule 10b5-1 Trading Plans. None. Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections Not applicable. 83 PART III s Item 10. Directors, Executive Officers and Corporate Governance The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference. Item 11. Executive Compensation The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference. Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference. Item 13. Certain Relationships and Related Party Transactions The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference. Item 14. Principal Accounting Fees and Services The information required in response to this item will be set forth in our definitive proxy statement for the 2026 annual meeting of stockholders and is incorporated herein by reference. 84 PART IV Item 15. Exhibits, Financial Statement Schedules (1) Financial Statements As part of this Annual Report on Form 10-K, the consolidated financial statements are listed in the accompanying index to financial statements on page 92 . (2) Financial Statement Schedules All financial statement schedules have been omitted because they are not applicable, not required, or the information required is shown in the consolidated financial statements or the notes thereto. 85 (3) Exhibits The exhibits filed as part of this Annual Report on Form 10-K are listed below. Exhibit No. Description 3.1 Restated Certificate of Incorporation (incorporated by reference to Exhibit 3.1 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 ) 3.2 Amended and Restated Bylaws (incorporated by reference to Exhibit 3.2 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) 3.3 Amendment to Restated Certificate of Incorporation of Summit Therapeutics Inc., as filed with the Delaware Secretary of State on July 27, 2022 (incorporated by reference to Exhibit 3.1 to the Company's Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on July 29, 2022 3.4 Amendment No. 2 to Restated Certificate of Incorporation of Summit Therapeutics Inc., dated January 19, 2023 (incorporated by reference to Exhibit 5.1 to the Company's Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on January 20, 2023 4.1 Registration Rights Agreement, dated January 9, 2019, by and among Summit Therapeutics plc and Robert W. Duggan (incorporated by reference to Exhibit 2.1 to the Company’s Report on Form 6-K (File No. 001-36866), filed with the Securities and Exchange Commission on January 10, 2019) 4.2 Form of Consultant Warrant (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 18, 2020) 4.3 Form of Investor Warrant (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 September 18, 2020) 4.4 Description of Securities Registered Under Section 12 of the Exchange Act (incorporated by reference to the description of securities contained in the Company’s Current Report on Form 8-K12B (File No. 001-36866), filed with the Securities and Exchange Commission on September 18, 2020) 4.5 Registration Rights Agreement, dated November 6, 2020, by and among Summit Therapeutics Inc., Polar Capital Funds plc - Biotechnology Fund and the Mahkam Zanganeh Revocable Trust (incorporated by reference to Exhibit 10.3 to the Company ’ s Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on November 6, 2020) 10.1# 2005 Enterprise Management Incentive Scheme (incorporated by reference to Exhibit 4.3 to the Company’s Transition Report on 20-F (File No. 333-36866), as amended, filed with the Securities and Exchange Commission on April 30, 2020) 10.2# 2016 Long Term Incentive Plan (incorporated by reference to Exhibit 4.22 to the Company’s Annual Report on Form 20-F (File No. 001-36866), filed with the Securities and Exchange Commission on May 12, 2016) 10.3 Lease, dated February 17, 2017, by and among MEPC Milton Park No. 1 Limited, MEPC Milton Park No. 2 Limited and Summit Therapeutics plc (incorporated by reference to Exhibit 4.25 to the Company’s Annual Report on Form 20-F (File No. 001-36866), filed with the Securities and Exchange Commission on March 30, 2017) 10.4 Lease, dated December 22, 2017, by and between Merrifield Centre Ltd and Discuva Limited (incorporated by reference to Exhibit 4.31 to the Company’s Annual Report on Form 20-F (File No. 001-36866), filed with the Securities and Exchange Commission on April 13, 2018) 10.5# Form of Non-Executive Director Restricted Stock Unit (RSU) Agreement (incorporated by reference to Exhibit 4.33 to the Company’s Annual Report on Form 20-F (File No. 001-36866), filed with the Securities and Exchange Commission on April 13, 2018) 10.6 (1) Securities Purchase Agreement, dated October 2, 2020, by and between Summit Therapeutics Inc. and Robert W. Duggan (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 October 5, 2020) 10.7#* Form of Indemnification Agreement between Summit Therapeutics Inc. and each of its Executive Officers and Directors 10.8# 2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.2 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) 10.9# Form of Option Award under 2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.28 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) 10.10# Form of Restricted Stock Unit Agreement under 2020 Stock Incentive Plan (incorporated by reference to Exhibit 10.29 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) 86 Exhibit No. Description 10.11# 2020 Employee Stock Purchase Plan (incorporated by reference to Exhibit 10.3 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) 10.12 Sublease Agreement, dated March 26, 2021, by and between Maky Zanganeh & Associates Inc. and Summit Therapeutics Sub Inc. (incorporated by reference to Exhibit 10.36 to the Company ’ s Annual Report on Form 10-K (File No. 001-36866), filed with the Securities and Exchange Commission on March 31, 2021) 10.13 (1) Note Purchase Agreement, dated March 10, 2022, by and between Summit Therapeutics Inc. and Robert W. Duggan (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 March 11, 2022) 10.14 Promissory Note, dated March 10, 2022, in the name of Robert W. Duggan (incorporated by reference to Exhibit 10.2 to the Company ’ s Current Report on Form 8-K (File. No. 001-36866), filed with the Securities and Exchange Commission on March 11, 2022) 10.15 Note Purchase Agreement, dated December 6, 2022, by and among Summit Therapeutics Inc., Robert W. Duggan, and Dr. Mahkam Zanganeh (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 December 6, 2022) 10.16† Collaboration and License Agreement, dated December 5, 2022, by and between Akeso, Inc. and its affiliates and Summit Therapeutics Sub Inc. (incorporated by reference to Exhibit 10.1 to the Company’s Form S-3 (File No. 333-268932) filed with the Securities and Exchange Commission on December 21, 2022) 10.17 Amendment No. 1 to Collaboration and License Agreement Amendment, dated January 16, 2023, by and among Summit Therapeutics Inc. and Akeso, Inc. (incorporated by reference to Exhibit 10.1 of Form 8-K filed by the Company on January 20, 2023, File No. 001-36866) 10.18 Common Stock Issuance Agreement, dated January 17, 2023, by and among Summit Therapeutics Inc. and Akeso, Inc. (incorporated by reference to Exhibit 10.2 of Form 8-K filed by the Company on January 20, 2023, File No. 001-36866) 10.19 Promissory Notes, dated January 19, 2023, by and among Summit Therapeutics Inc. and Robert W. Duggan (incorporated by reference to Exhibit 10.3 of Form 8-K filed by the Company on January 20, 2023, File No. 001-36866) 10.20# 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) 10.21† First Amendment to Sublease Agreement, dated July 25, 2022, by and among Summit Therapeutics Inc. and Maky Zanganeh and Associates, Inc. (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) 10.22† Second Amendment to Sublease Agreement, dated July 29, 2022, by and among Summit Therapeutics Inc. and Maky Zanganeh and Associates, Inc. (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) 10.23# 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) 10.24# Employment Agreement, dated October 13, 2023, by and between Summit Therapeutics Inc. 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) 10.25 Securities Purchase Agreement, dated October 13, 2023, by and between Summit Therapeutics Inc. 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. and Robert W. Duggan (incorporated by reference to Exhibit 10.51 to the Company's Annual Report on Form 10-K (File No. 001-36866), filed with the Securities and Exchange Commission on February 20, 2024). 10.27 Lease Agreement, dated January 8, 2024 by and between Brickell Key Center, LLC and Summit Therapeutics, Inc (incorporated by reference to Exhibit 10.2 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) 10.28 Distribution Agreement, dated May 13, 2024, by and between Summit Therapeutics Inc. and J.P. Morgan Securities LLC (incorporated by reference to Exhibit 1.1 to the Company’s Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on May 13, 2024) 87 Exhibit No. Description 10.29+ Securities Purchase Agreement, dated June 3, 2024, by and among the Company and the Investors named therein (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 June 3, 2024) 10.30+ Registration Rights Agreement, dated June 3, 2024, by and among the Company and the Investors named therein (incorporated by reference to Exhibit 10.2 to the Company’s Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on June 3, 2024) 10.31† Amendment No. 2 to Collaboration and License Agreement Amendment, dated June 3, 2024, by and among Summit Therapeutics Sub, Inc. and Akeso, Inc. 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 Securities and Exchange Commission on August 6, 2024. 10.32† Sublease, dated June 27, 2024, by and between Summit Therapeutics Inc. and Duggan Investments Research LLC (incorporated by reference to Exhibit 10.5 of the Company’s Quarterly Report on Form 10-Q (File No. 001-36866), filed with the Securities and Exchange Commission on August 6, 2024) 10.33† Sublease, dated June 27, 2024, by and between Summit Therapeutics Inc. and Genius 24C Inc. (incorporated by reference to Exhibit 10.6 of the Company’s Quarterly Report on 10-Q (File No. 001-36866), filed with the Securities and Exchange Commission on August 6, 2024) 10.34† Third Amendment to Sublease, dated August 2, 2024, by and between Summit Therapeutics Sub, Inc. and Zanganeh & Associates Inc. (incorporated by reference to Exhibit 10.7 of the Company’s Quarterly Report on 10-Q (File No. 001-36866), filed with the Securities and Exchange Commission on August 6, 2024) 10.35+ Securities Purchase Agreement, dated September 11, 2024, by and among Summit Therapeutics Inc. and the Investors named therein (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed (File No. 001-36866), filed with the Securities and Exchange Commission on September 12, 2024) 10.36+ Registration Rights Agreement, dated September 11, 2024, by and among Summit Therapeutics Inc. and the Investors named therein (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8-K filed (File No. 001-36866), filed with the Securities and Exchange Commission on September 12, 2024) 10.37† 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. and J.P. 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) 10.39+ 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) 10.40+ 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) 14.1* Code of Business Conduct and Ethics of Summit Therapeutics Inc . 19.1 Insider Trading Policy 21.1* List of Significant Subsidiaries 23.1* Consent of PricewaterhouseCoopers LLP, an independent registered public accounting firm 31.1* Certification of Chief Executive Officer pursuant to Securities Exchange Act Rules 13a-14(a) and 15d-14(a) as adopted pursuant to §302 of the Sarbanes-Oxley Act of 2002 31.2* Certification of Co-Chief Executive Officer pursuant to Securities Exchange Act Rules 13a-14(a) and 15d-14(a) as adopted pursuant to §302 of the Sarbanes-Oxley Act of 2002 31.3* Certification of Chief Financial Officer pursuant to Securities Exchange Act Rules 13a-14(a) and 15d-14(a) as adopted pursuant to §302 of the Sarbanes-Oxley Act of 2002 32.1** Certification pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002 97.1 Summit Therapeutics, Inc. Incentive-based Compensation Clawback Policy (incorporated by reference to Exhibit 97.1 to the Company's Annual Report on Form 10-K (File No. 001-36866), filed with the Securities and Exchange Commission on February 20, 2024) 101.INS* Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document 101.SCH* Inline XBRL Taxonomy Extension Schema Document 101.CAL* Inline XBRL Taxonomy Extension Calculation Linkbase Document 88 Exhibit No. Description 101.DEF* Inline XBRL Taxonomy Extension Definition Linkbase Document 101.LAB* Inline XBRL Taxonomy Extension Label Linkbase Document 101.PRE* Inline XBRL Taxonomy Extension Presentation Linkbase Document 104* Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101) * 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. + Certain of the exhibits and schedules to this exhibit have been omitted in accordance with Regulation S-K Item 601(a)(5). The Company agrees to furnish supplementally a copy of all omitted exhibits and schedules to the SEC upon its request. (1) The schedules and exhibits have been omitted. A copy of any omitted schedule or exhibit will be furnished to the SEC upon request. # Indicates management contract or compensatory plan or arrangement. Item 16. Report Summary None. 89 SIGNATURES Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. SUMMIT THERAPEUTICS INC. By: /s/ Robert W. Duggan Name: Title: Robert W. Duggan Co-Chief Executive Officer and Executive Chairman (Principal Executive Officer) By: /s/ Mahkam Zanganeh Name: Title: Dr. Mahkam Zanganeh Co-Chief Executive Officer, President and Director (Principal Executive Officer) By: /s/ Manmeet S. Soni Name: Title: Manmeet S. Soni Chief Operating Officer, Chief Financial Officer and Director (Principal Financial Officer) Date: February 23, 2026 90 Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Report has been signed below by the following persons on behalf of the Registrant in the capacities and on the dates indicated. Name Title Date /s/ Robert W. Duggan Co-Chief Executive Officer and Executive Chairman ( Principal Executive Officer ) February 23, 2026 Robert W. Duggan /s/ Mahkam Zanganeh Co-Chief Executive Officer, President and Director ( Principal Executive Officer ) February 23, 2026 Dr. Mahkam Zanganeh /s/ Manmeet S. Soni Chief Operating Officer, Chief Financial Officer and Director (Principal Financial Officer) February 23, 2026 Manmeet S. Soni /s/ Bhaskar Anand Head of Finance and Chief Accounting Officer (Principal Accounting Officer) February 23, 2026 Bhaskar Anand /s/ Robert F. Booth Director February 23, 2026 Dr. Robert F. Booth /s/ Alessandra Cesano Director February 23, 2026 Dr. Alessandra Cesano /s/ Kenneth Clark Director February 23, 2026 Kenneth Clark /s/ Jeff Huber Director February 23, 2026 Jeff Huber /s/ Mostafa Ronaghi Director February 23, 2026 Mostafa Ronaghi /s/ Yu Xia Director February 23, 2026 Dr. Yu Xia 91 SUMMIT THERAPEUTICS INC. Page INDEX TO CONSOLIDATED FINANCIAL STATEMENTS Report of Independent Registered Public Accounting Firm (PCAOB ID: 238 ) 93 Consolidated Balance Sheets 95 Consolidated Statements of Operations and Comprehensive Loss 96 Consolidated Statements of Stockholders' Equity 97 Consolidated Statements of Cash Flows 98 Notes to Consolidated Financial Statements 99 92 Report of Independent Registered Public Accounting Firm To the Board of Directors and Stockholders of Summit Therapeutics Inc. Opinions on the Financial Statements and Internal Control over Financial Reporting We have audited the accompanying consolidated balance sheets of Summit Therapeutics Inc. and its subsidiaries (the "Company") as of December 31, 2025 and 2024, and the related consolidated statements of operations and comprehensive loss, of stockholders’ equity and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes (collectively referred to as the "consolidated financial statements"). We also have audited the Company's internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO. Basis for Opinions The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects. Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions. Emphasis of Matter As discussed in Note 1 to the consolidated financial statements, the Company has incurred net losses from operations and cash outflows from operating activities. Management’s evaluation of the events and conditions and management’s plans to mitigate these matters are also described in Note 1. Definition and Limitations of Internal Control over Financial Reporting A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. 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 93 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. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. Critical Audit Matters The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates. 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 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 San Jose, California February 23, 2026 We have served as the Company’s auditor since 2021. 94 Summit Therapeutics Inc. Consolidated Balance Sheets (in thousands, except share and per share data) December 31, 2025 December 31, 2024 Assets Current assets: Cash and cash equivalents $ 225,266 $ 104,862 Restricted cash 316 325 Short-term investments 488,182 307,487 Prepaid expenses and other current assets 6,537 11,076 Total current assets 720,301 423,750 Non-current assets: Property and equipment, net 1,059 254 Operating lease right-of-use assets 20,616 7,144 Goodwill 2,001 1,864 Other assets 7,205 2,548 Total assets $ 751,182 $ 435,560 Liabilities and stockholders’ equity Current liabilities: Accounts payable $ 20,292 $ 4,636 Accrued liabilities 32,100 19,554 Accrued compensation 14,925 11,977 Operating lease liabilities, current portion 3,388 3,765 Other current liabilities 2,283 1,797 Total current liabilities 72,988 41,729 Non-current liabilities: Operating lease liabilities, net of current portion 17,502 3,453 Other non-current liabilities 1,832 1,630 Total liabilities 92,322 46,812 Commitments and contingencies (Note 16) Stockholders’ equity: Preferred stock, $ 0.01 par value, 20,000,000 shares authorized; none issued and outstanding at December 31, 2025 and 2024, respectively — — Common stock, $ 0.01 par value: 1,000,000,000 shares authorized; 775,371,200 and 737,626,004 shares issued and outstanding at December 31, 2025 and 2024, respectively 7,754 7,376 Additional paid-in capital 2,947,805 1,598,230 Accumulated other comprehensive loss ( 2,540 ) ( 2,285 ) Accumulated deficit ( 2,294,159 ) ( 1,214,573 ) Total stockholders' equity 658,860 388,748 Total liabilities and stockholders' equity $ 751,182 $ 435,560 The accompanying notes are an integral part of the consolidated financial statements 95 Summit Therapeutics Inc. Consolidated Statements of Operations and Comprehensive Loss (in thousands, except share and per share data) Year Ended December 31, 2025 2024 2023 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 Total operating 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 ) Net loss per share: Basic and diluted $ ( 1.44 ) $ ( 0.31 ) $ ( 0.99 ) Weighted average common shares outstanding: Basic and diluted 747,702,265 718,541,896 619,646,180 Other comprehensive income (loss): Foreign currency translation adjustments ( 327 ) 60 ( 172 ) 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. 96 Summit Therapeutics Inc. Consolidated Statements of Stockholders’ Equity (in thousands, except share data) Common Stock Additional Paid-In Capital Accumulated Other Comprehensive Loss Total Accumulated Deficit Total Stockholders’ Equity Shares Amount 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) 476,190,471 4,762 494,619 — — 499,381 Issuance of common stock under employee stock purchase plans and exercise of stock options 596,472 7 922 — — 929 Issuance of common stock in lieu of cash for Akeso upfront payment 10,000,000 100 45,800 — — 45,900 Private placement of common stock 2,976,190 30 4,970 — — 5,000 Exercise of warrants (2) 805,495 8 1,195 — — 1,203 Stock-based compensation — — 14,108 — — 14,108 Net other comprehensive loss — — — ( 555 ) — ( 555 ) Net loss — — — — ( 614,928 ) ( 614,928 ) Balance at December 31, 2023 701,660,053 $ 7,017 $ 1,066,381 $ ( 2,448 ) $ ( 993,258 ) $ 77,692 Private placement of common stock, net of offering costs of $ 140 (2) 32,574,640 326 434,534 — — 434,860 Issuance of common stock under stock purchase plans and exercise of stock options and warrants 1,584,218 15 3,319 — — 3,334 Proceeds from at-the-market offering, net of commissions and offering costs of $ 1,190 1,807,093 18 43,015 — — 43,033 Stock-based compensation — — 50,981 — — 50,981 Net other comprehensive gain — — — 163 — 163 Net loss — — — — ( 221,315 ) ( 221,315 ) Balance at December 31, 2024 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. 97 Summit Therapeutics Inc. Consolidated Statements of Cash Flows (in thousands) Year Ended December 31, 2025 2024 2023 Cash flows used in operating activities: Net loss $ ( 1,079,586 ) $ ( 221,315 ) $ ( 614,928 ) Adjustments to reconcile net loss to net cash used in operating activities: Non-cash interest expense — — 6,253 Amortization of discount on short-term investments ( 7,006 ) ( 2,576 ) ( 1,924 ) Unrealized foreign exchange loss (gain) ( 320 ) 229 ( 812 ) Reclassification of currency translation gain — — ( 419 ) Impairment of fixed assets — — 474 Depreciation 146 89 198 Stock-based compensation 732,420 50,981 14,108 Loss on disposal of assets — — ( 109 ) Acquired in-process research and development expense — 15,007 520,915 Changes in operating assets and liabilities: Prepaid expenses and other current assets 4,866 ( 7,370 ) 3,613 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 ) Accrued compensation 2,909 6,557 ( 235 ) Other long-term liabilities 80 95 — Operating lease right-of-use assets and lease liabilities, net 203 ( 167 ) ( 359 ) 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 ) Proceeds from sale of property, plant and equipment — — 226 Payments to Akeso for upfront milestone payments and associated direct transaction costs — ( 15,007 ) ( 475,015 ) Net cash used in investing activities ( 174,310 ) ( 205,341 ) ( 587,774 ) Cash flows provided by financing activities: Proceeds from the issuance of common stock via private placements, net of offering costs (2) 500,037 434,860 5,000 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 Proceeds received related to employee stock purchase plan and exercise of stock options 5,653 2,736 929 Proceeds from the issuance of common stock for rights offering (2) — — 104,686 Transaction costs from the issuance of common stock for rights offering — — ( 619 ) Re-payment of related party promissory notes — ( 100,000 ) ( 24,686 ) Net cash provided by financing activities 617,533 381,227 86,513 Effect of exchange rates on cash and cash equivalents 102 ( 18 ) 839 Increase (decrease) in cash, cash equivalents and restricted cash 120,395 33,762 ( 577,182 ) Cash, cash equivalents and restricted cash at beginning of period 105,187 71,425 648,607 Cash, cash equivalents and restricted cash at end of period $ 225,582 $ 105,187 71,425 Supplemental Disclosure of Cash Flow Information: Cash paid for interest on related party promissory note $ — $ 8,806 $ 10,650 Cash paid for income taxes $ — $ — $ 52 Supplemental Disclosure of Non-Cash Investing and Financing Activities: 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 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. 98 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 1. Organization Summit Therapeutics Inc. (“we”, “Summit” or the “Company”) is a biopharmaceutical company focused on the discovery, development, and commercialization of patient-, physician-, caregiver- and societal-friendly medicinal therapies intended to improve quality of life, increase potential duration of life, and resolve serious unmet medical needs. The Company’s pipeline of product candidates is designed with the goal to become the patient-friendly, new-era standard-of-care medicines, in the therapeutic area of oncology. 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 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 (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 The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. Any reference in these notes to applicable guidance is meant to refer to authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain reclassifications have been made to the prior years’ financial statements to conform to current year presentation. 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 income 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, 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. Actual results may differ from these estimates under different assumptions or conditions. Liquidity and Capital Resources 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. 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 99 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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. There is no assurance, however, that additional financing will be available when needed or that management of the Company will be able to obtain financing on terms acceptable to the Company. If the Company is unable to obtain funding when required in the future, the Company could be required to delay, reduce, or eliminate research and development programs, product portfolio expansion, or future commercialization efforts, which could adversely affect its business prospects. 2. Summary of Significant Accounting Policies and Recent Accounting Pronouncements The significant accounting policies adopted by the Company in the preparation of these consolidated financial statements are set out below. These policies have been consistently applied to all the years presented, unless otherwise stated. Principles of Consolidation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the U.S. GAAP and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. The consolidated financial statements reflect the accounts of Summit Therapeutics Inc. and its wholly owned subsidiaries. Intercompany balances and transactions are eliminated in consolidation. Foreign Currency Translation The financial statements of the Company’s subsidiaries with functional currencies other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates for operating results. 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 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 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. The dilutive effect of share options and warrants are determined under the treasury stock method using the average market price for the period. In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options and warrants that are in-the-money. Goodwill Goodwill represents the excess of the consideration transferred over the fair value of net assets acquired. Goodwill is assigned to reporting units at the time of acquisition or when there is a change in the reporting structure and bases that allocation on which reporting units will benefit from the acquired assets and liabilities. Reporting units are defined as operating segments or one level below an operating segment, referred to as a component. Typically acquisitions related to a single reporting unit do not require the allocation of goodwill to multiple reporting units. If the net assets obtained in an acquisition are assigned to multiple reporting units, the goodwill is distributed to the respective reporting units as part of the purchase price allocation process. 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 100 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. In performing the Company’s annual goodwill impairment test, the Company is permitted to first assess qualitative factors to determine whether it is more likely than not that the fair value of the Company’s reporting unit is less than its carrying amount, including goodwill. In performing the qualitative assessment, the Company considers certain events and circumstances specific to the reporting unit and to the entity as a whole, such as macroeconomic conditions, industry and market considerations, overall financial performance and cost factors when evaluating whether it is more likely than not that the fair value of the reporting unit is less than its carrying amount. The Company is also permitted to bypass the qualitative assessment and proceed directly to the quantitative test. If the Company chooses to undertake the qualitative assessment and concludes that it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the Company would then proceed to the quantitative impairment test. In the quantitative assessment, the Company compares the fair value of the reporting unit to its carrying amount, which includes goodwill. If the fair value exceeds the carrying value, no impairment loss exists. If the fair value is less than the carrying amount, a goodwill impairment loss is measured and recorded. Leases The Company has operating leases for real estate. The Company does not have any finance leases. A contract is or contains a lease when the lessee has the right to control the use of an identified asset. The Company determines if an arrangement is a lease at inception of the contract, which is the date on which the terms of the contract are agreed to and the agreement creates enforceable rights and obligations. The lease term used to calculate the lease liability include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. At the lease commencement date, the Company measures and recognizes a lease liability and a right-of-use asset in the financial statements. Lease liabilities are recognized based on the present value of the future lease payments over the lease term at commencement date. The right-of use asset is measured by taking the present value of future lease payments, plus any incremental direct costs incurred, less any lease incentives received. As most of the Company ’ s leases do not provide an implicit rate, the Company uses an estimated incremental borrowing rate based on the lease term and the economic environment of the lease at the lease commencement date, which is then utilized to determine the present value of future lease payments. Lease expense for minimum lease payments are recognized on a straight-line basis over the lease term, with variable lease payments recognized in the periods in which they are incurred. The Company has existing lease agreements with lease and non-lease components, has elected to account for the lease and non-lease components as a single lease component, and has allocated all of the contract consideration to the lease component only. Leases with an initial lease term of 12 months or less are not recorded on the balance sheet. The Company recognizes lease expense for its short-term leases on a straight-line basis over the lease term. Acquired In-Process Research and Development The Company may enter into agreements with collaboration partners for the development and commercialization of its products. These arrangements may include payments contingent on the occurrence of certain events such as development, regulatory or sales-based milestones. The Company considers the unique nature, terms and facts and circumstances of each transaction. The Company considers whether or not the assets acquired have an alternative future use. The fair value associated with acquired in-process research and development which does not have an alternative future use is expensed and is recorded as research and development expense. 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. Research and Development Costs Research and development costs are expensed as incurred. 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- 101 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. Milestone and other payments made to third-parties with respect to in-process research and development, in accordance with the Company’s license, acquisition and other similar agreements are expensed when determined to be probable and estimable. The Company 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 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. Actual results could differ from the Company’s estimates. In all cases, the full cost of each study or activity is expensed by the time the final report or where applicable, product, has been received. The Company’s historical estimates have not been materially different from the actual costs. Stock-Based Compensation The Company measures and recognizes compensation expense for all stock option awards based on the estimated fair value of the award on the grant date. The Company uses the Black-Scholes option pricing model to estimate the fair value of stock option awards. Additionally, the Company uses a Monte Carlo simulation model to calculate the estimated fair value on the date of grant related to awards with market-based service conditions. The fair value is recognized as expense, over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis for each separately vesting portion of the award when the only condition to vesting is continued service. If vesting is subject to a market or performance condition, recognition is based on the derived service period of the award. Expense for awards with performance conditions is estimated and adjusted on a quarterly basis based upon the assessment of the probability that the performance condition will be met. Use of the Black-Scholes option-pricing model requires management to apply judgment under subjective assumptions. These assumptions include: • Expected term—The expected term of stock options represents the weighted-average period the stock options are expected to be outstanding. The Company uses the simplified method for estimating the expected term as provided by the SEC. The simplified method calculates the expected term as the average of the time-to-vesting and the contractual life of the options. • Expected volatility—The expected volatility is calculated based on historical volatility of the Company ’ s share price. • Risk-free interest rate—The risk-free rate assumption is based on the U.S. Treasury instruments, the terms of which were consistent with the expected term of the Company’s stock options. • Expected dividend—The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has not paid and does not intend to pay dividends. 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 Company estimates expected forfeitures at the time of grant instead of accounting for forfeitures as they occur. Stock option awards have been granted at fair value to non-employees in connection with research and consulting services provided to the Company. Equity awards generally vest over terms of 3 or 4 years. 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. Income Taxes The provision for income taxes is determined using the asset and liability approach. 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 102 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. Deferred taxes are initially recognized at enacted tax rates in force at the time of initial recognition and are subsequently adjusted for any enacted changes in tax rates and tax laws. Subsequent changes to deferred taxes originally recognized in equity are recognized in income. 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 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 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. The Company’s cash is comprised of short-term cash deposits at a variety of financial institutions which the Company believes are of high credit ratings in amounts that may exceed federally insured limits. The Company has not experienced any losses on such accounts. Cash balances maintained during the year have been principally held with U.S.-based and U.K.-based banks. The Company does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company relies, and expects to continue to rely, on a number of vendors to conduct its clinical trials and preclinical studies, manufacture drug product and supply clinical trial and preclinical study materials for its development programs. These programs could be adversely affected by a significant interruption in these services or the availability of materials. Fair Value Measurements In accordance with the provisions of fair value accounting, a fair value measurement assumes that the transaction to sell an asset or transfer a liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability and defines fair value based on the exit price model. The fair value measurement guidance establishes a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The guidance describes three levels of inputs that may be used to measure fair value: Level 1 Quoted prices in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets and liabilities include debt securities with quoted prices that are traded less frequently than exchange-traded instruments or securities or derivative contracts that are valued using a pricing model with inputs that are observable in the market or can be derived principally from or corroborated by observable market data. Level 3 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, 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. In such cases, the Company categorizes such assets and liabilities based on the lowest level input that is significant to the fair value measurement in its entirety. 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. 103 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, 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. 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. The Company’s total cash, cash equivalents and restricted cash balances were as follows: Year Ended December 31, 2025 2024 2023 Cash and cash equivalents $ 225,266 $ 104,862 $ 71,425 Restricted cash 316 325 — Total cash, cash equivalents and restricted cash $ 225,582 $ 105,187 $ 71,425 Short-term Investments 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 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. This estimate is limited to the amount by which fair value is less than amortized cost. The credit-related impairment amount is recognized in the consolidated statements of operations and comprehensive loss and the remaining impairment amount and unrealized gains are reported as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Credit losses are recognized through the use of an allowance for credit losses account and subsequent improvements in expected credit losses are recognized as a reversal of the allowance account. 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. 104 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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 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 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. 3. 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. 4. Akeso License and Collaboration Agreement 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. 105 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) Ivonescimab, known as AK112 in China and Australia, and also as SMT112 in the United States, Canada, Europe, and Japan, is a novel, potential first-in-class bispecific antibody intending to combine the effect of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects of an anti-VEGF into a single molecule. Ivonescimab was engineered to bring two well established oncology targeted mechanisms together. Ivonescimab is currently in clinical development and, pursuant to the terms of the License Agreement, Summit will design and conduct the clinical trial activities to support regulatory filings in the Licensed Territory that Summit will submit. Pursuant to the terms of the License Agreement, Summit will have final decision making authority with respect to clinical development strategy and execution in the Licensed Territory. For co-joined studies in which both Summit and Akeso participate, mutual agreement is required for material decisions; Summit retains the exclusive decision making with respect to participating in, and continuing its participation in, co-joined studies. 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 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 the Company’s common stock, par value $ 0.01 per share (“common stock”) in lieu of $ 25,100 in 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 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. Akeso will also be eligible to receive up to an additional $ 55,000 upon the achievement of certain commercial milestones. Except as specifically modified by the Second Amendment, the terms and conditions of the License Agreement remain in full force and effect. The Company has accounted for the License Agreement and Second Amendment to acquire the rights to develop and commercialize ivonescimab as the acquisition of an asset. All of the consideration relates to ivonescimab and technological feasibility of the asset has not yet been established since ivonescimab is in clinical development. 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, 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 . In addition, Akeso will be eligible to receive low double-digit royalties on net sales. 106 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 5. Other Income, Net The following table sets forth the components of other income, net: Year Ended December 31, 2025 2024 2023 Foreign currency (loss) gain $ ( 610 ) $ ( 97 ) $ 613 Investment income (1) 15,501 13,466 10,403 Reclassification of cumulative currency translation gain (2) — — 419 Other expense, net ( 53 ) — ( 252 ) $ 14,838 $ 13,369 $ 11,183 (1) Investment income relates to the Company’s money market funds and short-term investments in U.S. treasury securities. Refer to Note 9 for details. (2) The reclassification of cumulative currency translation gain related to the reclassification of cumulative foreign currency translation gains from accumulated other comprehensive loss due to the dissolution of certain dormant entities. 6. Income Tax The Company is primarily subject to corporation taxes in the U.S. and the U.K. The calculation of the Company’s tax provision involves the application of both U.S. and U.K. tax law and requires judgment and estimates. 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. The provision for income taxes is determined using the asset and liability approach. 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. Deferred taxes represent the future tax consequences expected to occur when the reported amounts of assets and liabilities are recovered or paid. Deferred taxes are initially recognized at enacted tax rates in force at the time of initial recognition and are subsequently adjusted for any enacted changes in tax rates and tax laws. Subsequent changes to deferred taxes originally recognized in equity are recognized in income. 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 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. 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 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. 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 107 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: Year Ended December 31, 2025 2024 2023 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 ) 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. The major components of deferred tax assets and liabilities are as follows: Year Ended December 31, 2025 2024 Deferred tax assets: Net operating loss carryforward $ 73,583 $ 59,413 Research and development credit carryforward 16,092 7,869 Stock-based compensation 32,158 14,001 Section 174 Research and Development Capitalization 11,034 14,167 Other 711 475 Total deferred tax assets 133,578 95,925 Deferred tax liabilities: Other ( 417 ) ( 337 ) Total deferred tax liabilities ( 417 ) ( 337 ) Net deferred tax assets before valuation allowance 133,161 95,588 Valuation allowance ( 133,161 ) ( 95,588 ) Deferred tax, net $ — $ — 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, 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 108 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. The Company reevaluates the positive and negative evidence at each reporting period. The changes in the valuation allowance during the years ended December 31, 2025, 2024 and 2023 primarily related to net operating loss carryforwards and capitalized research and development expenses. The change in the valuation allowance was as follows: Year Ended December 31, 2025 2024 2023 Valuation allowance as of beginning of year $ ( 95,588 ) $ ( 84,751 ) $ ( 64,016 ) Net increases recorded to income tax provision ( 37,573 ) ( 10,837 ) ( 20,735 ) 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 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 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, 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. taxable profits exceed £5,000 in each year, the loss available to utilize against profits in excess of £5,000 will be restricted to 50%. The U.K. loss carryforwards do not lapse and therefore, the full amount will be relieved over time provided there are sufficient profits against which the losses can be utilized. Utilization of the U.S. net operating loss carryforwards and research and development tax credit carryforwards may be subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986 due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of carryforwards that can be utilized annually to offset future taxable income. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period. The Company has not completed a study to assess whether a change of ownership has occurred, or whether there have been multiple ownership changes since its formation. Any limitation may result in the loss of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization. U.K. tax losses are subject to additional restrictions where there is a change in ownership in the business and certain other conditions are met. An ownership change of a U.K. tax resident company would occur where (directly or indirectly) a single person acquires more than half of the ordinary share capital of a company, or two or more persons each acquire a holding of at least 5% of the ordinary share capital of a company and these holdings together amount to more than half the ordinary share capital of a company. Where a change in ownership has occurred, and within three years prior to that change in ownership and five years afterwards, there is a major change in the nature and conduct of trade of that company or the trade of that business becomes small or negligible, any losses carried forward will be extinguished from the point of the change in ownership. 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 109 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) restrict the U.K. tax losses. Any limitation may result in the loss of a portion of the net operating loss carryforwards before utilization. Deemed U.S. 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. Accounting for Global Intangible Low-taxed Income, the Company is allowed to make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as period expense only. The Company has elected to account for GILTI in the year the tax is incurred and include the current tax impact of GILTI in the effective tax rate. Given the Company’s loss position in the U.S. and the valuation allowance recorded against its U.S. net deferred tax assets, these provisions have not had a material impact on the Company’s consolidated financial statements. Annual Effective Tax Rate Reconciliation A reconciliation of the Company’s effective tax rate to the U.S. federal statutory rate is as follows: Year Ended December 31, 2025 2024 2023 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 ) — % — — % 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 ) % Total $ — — % $ — — % $ — — % 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: Year Ended December 31, 2025 2024 2023 Unrecognized tax benefits, beginning of year $ 2,122 $ 1,064 $ — Increases related to prior year tax positions 592 122 610 Increases related to current year tax positions 1,189 936 454 Unrecognized tax benefits, end of year $ 3,903 $ 2,122 $ 1,064 110 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. The Company is not currently under examination by the Internal Revenue Service or any other jurisdiction for years 2020 through present. 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 remains subject to examination by HMRC. Legislative Impacts On July 4, 2025, H.R. 1, a U.S. 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. 7. Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share: Year Ended December 31, 2025 2024 2023 Net loss $ ( 1,079,586 ) $ ( 221,315 ) $ ( 614,928 ) 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 ) 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 Options to purchase common stock 115,614,728 68,920,334 54,209,289 Warrants — 4,629,988 5,015,642 Shares expected to be purchased under employee stock purchase plan 65,905 86,550 155,163 Total 115,680,633 73,636,872 59,380,094 Stock options that are outstanding and contain improbable vesting criteria are excluded from the presentation of common stock equivalents outstanding in the table above. 111 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 8. Goodwill 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, 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. dollars at each reporting period. As of December 31, 2025 and 2024, goodwill was $ 2,001 and $ 1,864 , respectively. Changes year over year are the result of changes in foreign currency. The Company assesses goodwill for impairment on an annual basis as of December 31 or more frequently when events and circumstances occur indicating that recorded goodwill may be impaired. As of December 31, 2025, the Company performed its annual impairment assessment of goodwill and determined that it is more likely than not that the fair value of the reporting unit exceeds its carrying amount. The Company has recorded no goodwill impairment charges to date. 9. Fair Value Measurements and Short-Term Investments 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: 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 U.S. 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 U.S. 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: U.S. 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. 112 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) Realized gain (loss) on short-term investments for the years ended December 31, 2025 and 2024 were immaterial, respectively. 10. Research and Development Prepaid Expenses and Accrued Liabilities Included within prepaid expenses and other current assets at December 31, 2025 and 2024 is $ 3,996 and $ 8,338 , respectively, of prepayments relating to research and development expenditures. Included within accrued liabilities at December 31, 2025 and 2024 is $ 31,498 and $ 17,441 , respectively, relating to research and development expenditures. 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. 11. Leases The Company has operating leases for real estate. The Company does not have any finance leases. 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, 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. 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. The elements of lease expense were as follows: Year Ended December 31, 2025 2024 2023 Fixed lease costs $ 3,853 $ 3,461 $ 2,214 Variable lease costs 225 48 83 Total lease cost $ 4,078 $ 3,509 $ 2,297 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 $ 3,741 and $ 2,568 for the years ended December 31, 2025 and 2024, respectively. 113 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) Future lease payments under non-cancelable leases as of December 31, 2025 are detailed as follows: Year Ending December 31, 2026 $ 3,492 2027 4,052 2028 4,158 2029 3,349 2030 3,073 Thereafter 9,205 Total lease payments 27,328 Less: imputed interest 6,438 Total operating lease liabilities $ 20,890 Less: Operating lease liabilities, current portion 3,388 Operating lease liabilities, net of current portion $ 17,502 12. Promissory Note Payable to Related Parties December 2022 Promissory Notes On December 6, 2022, the Company entered into a Note Purchase Agreement (the “Note Purchase Agreement”), with Mr. Duggan and Dr. Zanganeh, pursuant to which the Company agreed to sell to each of Mr. Duggan and Dr. Zanganeh unsecured promissory notes in the aggregate amount of $ 520,000 . Pursuant to the Note Purchase Agreement, the Company issued to Mr. Duggan and Dr. Zanganeh unsecured promissory notes in the amount of $ 400,000 (the “Duggan February Note”) and $ 20,000 (the “Zanganeh Note”), respectively, which matured and became due on February 15, 2023 and an unsecured promissory note to Mr. Duggan in the amount of $ 100,000 (the “Duggan September Note” and together with the Duggan February Note and the Zanganeh Note, the “December 2022 Notes”), which was originally due on September 15, 2023. 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. 114 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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 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. 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. 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. 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. 13. Stockholders' Equity Preferred Stock As of December 31, 2025 and December 31, 2024, the Company had 20,000,000 shares of preferred stock, par value $ 0.01 authorized and no shares issued and outstanding. Common Stock As of December 31, 2025 and December 31, 2024, the Company had authorized 1,000,000,000 shares of common stock, par value $ 0.01 (the “Common Stock”). 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. 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. Aggregate gross proceeds from the 2023 Rights Offering were $ 500,000 from the sale of 476,190,471 shares of the Company’s Common Stock and issuance costs were $ 619 . Mr. Duggan and Dr. Zanganeh fully subscribed to their respective basic subscription rights at a price of $ 1.05 per share. To satisfy the $ 395,314 subscription price for the shares subscribed by Mr. Duggan in the 2023 Rights Offering, Mr. Duggan agreed with the Company to extinguish a portion of the amount due and payable to him by the Company at the closing of the 2023 Rights Offering pursuant to the $ 400,000 Duggan Promissory Note in an amount equal to the subscription price (see also Note 12). On January 19, 2023, the Company filed Amendment No. 2 to the Restated Certificate of Incorporation (the “Amendment No. 2”) with the Secretary of State of the State of Delaware to increase the number of authorized shares of its Common Stock by 650,000,000 (from 350,000,000 to 1,000,000,000 ), which became effective on such date. 115 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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 (as defined in Note 4) 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 Mr. Duggan and Dr. Zanganeh, respectively, as payment of prepaid interest in connection with the Note Purchase Agreement dated December 6, 2022 between Mr. Duggan, Dr. 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. 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. June 2024 PIPE (Private Investment in Public Equity) On June 3, 2024, the Company entered into a securities purchase agreement (the “Purchase Agreement”) with 667, L.P. and Baker Brothers Life Sciences, L.P., affiliates of Baker Bros. 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. The Purchase Agreement contained customary representations, warranties and covenants by the Company, customary indemnification obligations of the Company, including for liabilities under the Securities Act of 1933, other obligations of the parties and termination provisions. 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 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. The Company agreed to use its reasonable best efforts to have such registration statement declared effective as soon as practicable after the filing thereof. The Company filed the registration statement on August 6, 2024, which was automatically effective upon filing. September 2024 PIPE 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 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. Refer to Note 15 Related Party Transactions for further details regarding related parties' participation. The closing of the September 2024 Private Placement was September 13, 2024. 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 116 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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 (“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. 117 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) Warrants 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 . 14. Stock-Based Compensation 2016 Long Term Incentive Plan 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, 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. A total of 8,000,000 shares of Common Stock were initially reserved for issuance under the 2020 Plan. Additionally, up to 5,000,000 shares of Common Stock, including RSUs can be added to the 2020 Plan for future issuance from options that expire, lapse or are terminated from the 2016 Plan or any other predecessor plans. 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. 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 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. The Inducement Pool is administered by the Compensation Committee of the Board. In accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules, non-qualified stock options under the Inducement Pool may only be made to an employee who has not previously been an employee of the Company or member of the Board (or any parent or subsidiary of the Company), if he or she is granted such non-qualified stock options in connection with his or her commencement of employment with the Company or a subsidiary and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary. As of December 31, 2025, there were 1,936,452 shares available for grant under the Inducement Pool. 118 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 2020 Employee Stock Purchase Plan The 2020 Employee Stock Purchase Plan (the “2020 ESPP”) was adopted by the Board of Directors and approved by the Company’s shareholders on July 17, 2020 and approved by the predecessor company shareholders on August 19, 2020 and is qualified under Section 423 of the Internal Revenue Code. The 2020 ESPP initially authorized the issuance of up to 1,000,000 shares of Common Stock to participating employees. The number of common shares that may be issued under the 2020 ESPP automatically increases on each fiscal year commencing January 1, 2021 and continuing for each fiscal year until, and including the fiscal year commencing on, January 1, 2030 equal to the lesser of (i) 1,600,000 shares of Common Stock, (ii) 1 % of the common shares outstanding on such date and (iii) an amount as determined by the Company’s Board of Directors. As of December 31, 2025, there were 1,743,682 shares available to be issued under the 2020 ESPP. The 2020 ESPP is comprised of purchase periods of six months in duration and commence immediately preceding the end of the previous offering period, unless otherwise determined by the Board of Directors or Compensation Committee. Under the 2020 ESPP, eligible employees can purchase shares of Common Stock through payroll deductions of up to 15 % of their compensation received during the plan period or such shorter period during which deductions from payroll are made, up to a defined maximum amount. The option price is determined based on the lesser of the closing price of Common Stock on (i) the first business day of the plan period or (ii) the exercise date, or shall be based solely on the closing price of the Common Stock on the exercise date; provided that such option price shall be at least 85 % of the applicable closing price. In the absence of a determination by the Board of Directors or the Compensation Committee, the option price is 85 % of the lesser of the closing price of the Common Stock on (i) the first business day of the plan period or (ii) the exercise date. The closing price is the (a) the closing price (for the primary trading session) on the Nasdaq Global Select Market or (b) the average of the closing bid and asked prices in the over-the-counter-market, whichever is applicable, as published in the Wall Street Journal or another source selected by the Board or the Committee. During the fiscal year ended December 31, 2025 and 2024, 139,459 and 353,578 shares, respectively, were issued under the 2020 ESPP Plan. Stock Options The Company estimates the fair value of stock options granted to employees and directors using the Black-Scholes valuation model. Stock options granted under the 2016 and 2020 Plans generally vest over three or four years and expire after ten years . This valuation methodology utilizes several key assumptions as highlighted below. The assumptions used in the Company’s valuation are summarized as follows, presented on a weighted average basis: Year Ended December 31, 2025 2024 2023 Risk-free interest rate 3.8 % - 3.9 % 4.2 % 4.6 % Expected term (in years) 2.5 - 6.2 6.2 4.8 Expected volatility 124.9 % - 142.5 % 107.8 % 98.1 % Expected annual dividends per share — % — % — % 119 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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 Forfeited ( 1,015,750 ) 10.12 Exercised ( 953,564 ) 3.99 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. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2025, 2024 and 2023 was $ 15,212 , $ 863 , and $ 474 , respectively. 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. 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 Stock‑based compensation expense related to stock options is recorded within the consolidated statements of operations and comprehensive loss as follows: Year Ended December 31, 2025 2024 2023 Research and development $ 218,564 $ 16,007 $ 4,408 General and administrative 513,856 34,974 9,700 Total stock-based compensation $ 732,420 $ 50,981 $ 14,108 120 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: Year Ended December 31, 2025 2024 2023 Time-based stock options $ 731,358 $ 39,349 $ 12,606 Performance and market-based stock options — 11,033 1,318 Employee stock purchase plan 1,062 599 184 Total stock-based compensation $ 732,420 $ 50,981 $ 14,108 15. Related Party Transactions Leases July 25, 2022 First Amendment to Sublease Agreement with Maky Zanganeh and Associates, Inc. On July 25, 2022 the Company entered into a first amendment, dated July 19, 2022, to its existing sublease agreement with Maky Zanganeh and Associates, Inc. (“MZA”), an entity owned by Maky Zanganeh, consisting of 4,500 square feet of office space at 2882 Sand Hill Road, Menlo Park, California. The existing sublease term, which was set to expire on September 30, 2022, was extended for a period of thirty-nine months from October 1, 2022 through December 31, 2025. 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. 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 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 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 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 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 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 121 Summit Therapeutics Inc. Notes to Consolidated Financial Statements (in thousands, except share and per share data) 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. Promissory Note Payable to Related Parties 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. Dr. 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. Private Placements October 2023 PIPE Refer to Note 13 for a discussion on the participation by related parties in October 2023 PIPE. September 2024 PIPE 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. 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. Kenneth A. Clark, a member of the Board, is a partner. Payments to be made by the Company to WSGR 122 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. 16. 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 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. 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 123