Lyell Immunopharma, Inc. 10-K

Item 9A. Controls and Procedures. Evaluation of Disclosure Controls and Procedures As of December 31, 2025, management, with the participation and supervision of our Chief Executive Officer and Chief Financial Officer, have evaluated our disclosure controls and procedures as defined in Rules 13a-15(e) and 15d-15(e) of the Exchange Act. Our disclosure controls and procedures are designed to ensure that information required to be disclosed in the reports we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms, and that such information is accumulated and communicated to our management, including the Chief Executive Officer and Chief Financial Officer, to allow timely decisions regarding required disclosures. Any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objective and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on this evaluation, our Chief Executive Officer and Chief Financial Officer concluded that, as of December 31, 2025, the design and operation of our disclosure controls and procedures were effective at a reasonable assurance level. Inherent Limitations on Controls and Procedures Our management, including the principal executive officer and principal financial officer, does not expect that our disclosure controls and procedures and our internal control over financial reporting will prevent all error and all fraud. A control system, no matter how well designed and operated, can only provide reasonable assurances that the objectives of the control system are met. The design of a control system reflects resource constraints; the benefits of controls must be considered relative to their costs. Because there are inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that all control issues and instances of fraud, if any, for our company have been or will be detected. As these inherent limitations are known features of the disclosure and financial reporting processes, it is possible to design into the processes safeguards to reduce, though not eliminate, these risks. These inherent limitations include the realities that judgments in decision-making can be faulty and that breakdowns occur because of simple error or mistake. Controls can also be circumvented by the individual acts of some persons, by collusion of two or more people, or by management override of the control. The design of any system of controls is based in part upon certain assumptions about the likelihood of future events. While our disclosure controls and procedures and our internal control over financial reporting are designed to provide reasonable assurance of achieving their objectives, there can be no assurance that any design will succeed in achieving its stated goals under all future conditions. Over time, controls may become inadequate because of changes in conditions or deterioration in the degree of compliance with the policies or procedures. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and not be detected. Management’s Annual Report on Internal Control Over Financial Reporting Our management is responsible for establishing and maintaining an adequate internal control over financial reporting (as such term is defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) for our company. Our management, including our Chief Executive Officer and Chief Financial Officer, conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework set forth in “Internal Control—Integrated Framework” issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework). Based on an evaluation under that framework, our management concluded that our internal control over financial reporting was effective at the reasonable assurance level as of December 31, 2025. Changes in Internal Control over Financial Reporting There has been no change in our internal control over financial reporting during the quarter ended December 31, 2025 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting. 127 Table of Contents Item 9B. Other Information. During the quarter ended December 31, 2025, none of our directors or executive officers adopted or terminated a Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement as defined in Item 408(a) and (c) of Regulation S-K, respectively. Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections. Not applicable. 128 Table of Contents PART III Item 10. Directors, Executive Officers and Corporate Governance. Code of Ethics Our Board of Directors adopted a Code of Business Conduct and Ethics, which applies to all of our employees, officers and directors. This includes our principal executive officer, principal financial officer and principal accounting officer or controller, or persons performing similar functions. The full text of our Code of Business Conduct and Ethics may be viewed at the investor relations portion of our website at https://ir.lyell.com, in the section entitled “Governance Highlights” under “Corporate Governance.” We intend to satisfy the disclosure requirements under Item 5.05 of the SEC Form 8-K regarding an amendment to, or waiver from, a provision of our Code of Business Conduct and Ethics by posting such information on our website at the website address and location specified above. The remainder of the information required by this item is incorporated by reference to our Proxy Statement for the 2026 Annual Meeting of Stockholders to be filed with the SEC within 120 days of the fiscal year ended December 31, 2025 . Item 11. Executive Compensation. The information required by this item is incorporated by reference to our Proxy Statement for the 2026 Annual Meeting of Stockholders to be filed with the SEC within 120 days of the fiscal year ended December 31, 2025 . Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters. The information required by this item is incorporated by reference to our Proxy Statement for the 2026 Annual Meeting of Stockholders to be filed with the SEC within 120 days of the fiscal year ended December 31, 2025 . Item 13. Certain Relationships and Related Transactions, and Director Independence. The information required by this item is incorporated by reference to our Proxy Statement for the 2026 Annual Meeting of Stockholders to be filed with the SEC within 120 days of the fiscal year ended December 31, 2025 . Item 14. Principal Accountant Fees and Services. The information required by this item is incorporated by reference to our Proxy Statement for the 2026 Annual Meeting of Stockholders to be filed with the SEC within 120 days of the fiscal year ended December 31, 2025 . 129 Table of Contents PART IV Item 15. Exhibits and Financial Statement Schedules. (a) The following documents are being filed as part of this report: (1) The following financial statements and the Report of Independent Registered Public Accounting Firm are included in Part II, Item 8: Page Report of Independent Registered Public Accounting Firm (PCAOB ID: 42) 95 Consolidated Balance Sheets 97 Consolidated Statements of Operations and Comprehensive Loss 98 Consolidated Statements of Stockholders’ Equity 99 Consolidated Statements of Cash Flows 100 Notes to Consolidated Financial Statements 101 (2) All financial statement schedules are omitted because the information is inapplicable or presented in the Notes to Consolidated Financial Statements. (3) The following Exhibits are filed as part of this report. Incorporation by Reference Exhibit Number Exhibit Description Form File Number Exhibit/ Appendix Reference Filing Date Filed Herewith 2.1* Agreement and Plan of Merger, dated as of October 24, 2024, by and among the Registrant, ImmPACT Bio USA Inc., Inspire Merger Sub Inc. and WT Representative LLC, solely in its capacity as the Representative. 8-K 001-40502 2.1 10/24/2024 3.1 Amended and Restated Certificate of Incorporation. S-8 333-257249 4.1 6/21/2021 3.2 C ertificate of Amendment of the Ame nded and Restated Certificate of Incorporation of Lyell Immunopharma, Inc. 8-K 001-40502 3.1 5/28/2025 3.3 Amended and Restated Bylaws. 8-K 001-40502 3.1 12/05/2025 4.1 Form of Common Stock Certificate. 10-Q 001-40502 4.1 8/12/2025 4.2 Amended and Restated Investors’ Rights Agreement, by and among the Registrant and certain of its stockholders, dated March 5, 2020. S-1 333-256470 4.2 5/25/2021 4.3 Description of Securities 10-K 001-40502 4.3 2/28/2023 10.1# Lyell Immunopharma, Inc. 2018 Equity Incentive Plan, as amended. S-1 333-256470 10.1 5/25/2021 10.2# Forms of Stock Option Grant Notice, Stock Option Agreement and Notice of Exercise and Restricted Stock Award Agreement under the Lyell Immunopharma, Inc. 2018 Equity Incentive Plan. S-1 333-256470 10.2 5/25/2021 10.3# Lyell Immunopharma, Inc. 2021 Equity Incentive Plan. X 130 Table of Contents Incorporation by Reference Exhibit Number Exhibit Description Form File Number Exhibit/ Appendix Reference Filing Date Filed Herewith 10.4# Forms of Stock Option Grant Notice, Stock Option Agreement and Notice of Exercise under the Lyell Immunopharma, Inc. 2021 Equity Incentive Plan. S-1/A 333-256470 10.4 6/9/2021 10.5# Forms of Restricted Stock Unit Grant Notice and Award Agreement under the Lyell Immunopharma, Inc. 2021 Equity Incentive Plan. S-1/A 333-256470 10.5 6/9/2021 10.6# Lyell Immunopharma, Inc. 2021 Employee Stock Purchase Plan. X 10.7# Lyell Immunopharma, Inc. Non-Employee Director Compensation Policy. X 10.8# Lyell Immunopharma, Inc. Officer Severance Plan. 10-K 001-40502 10.8 3/29/2022 10.9 Form of Indemnification Agreement by and between the Registrant and its directors and executive officers. S-1 333-256470 10.9 5/25/2021 10.10# Offer Letter, by and between the Registrant and Lynn Seely, dated December 14, 2022 8-K 001-40502 10.2 12/16/2022 10.11# Offer Letter by and between the Registrant and Stephen Hill, dated May 9, 2019. S-1 333-256470 10.14 5/25/2021 10.12# Offer Letter by and between the Registrant and Gary Lee, dated November 24, 2021. 10-K 001-40502 10.16 2/28/2024 10.13# O ffer Letter by and between the Re gistrant and Mark Meltz, dated June 4, 2025. 10-Q 001-40502 10.2 8/12/2025 10.14# O ffer Letter by and between the Registrant and David Shook, dated June 3, 2025. 10-Q 001-40502 10.1 8/12/2025 10.15# Severance Waiver by and between the Registrant and Stephen Hill, dated April 19, 2022. 10-Q 001-40502 10.1 5/10/2022 10.16# O ff er Letter , by and between the Registrant and Smital Shah, dated March 3, 2026. 8-K 001-40502 10.1 3/9/2026 10.17 Standard Office Lease for Building C by and between the Registrant and Bre Wa Office Owner LLC, dated August 28, 2019. S-1 333-256470 10.19 5/25/2021 10.18 Standard Office Lease for Building E by and between the Registrant and Bre Wa Office Owner LLC, dated August 28, 2019. S-1 333-256470 10.20 5/25/2021 10.19 Lease by and between the Registrant and BMR-500 Fairview Avenue LLC, dated November 27, 2018, as amended. S-1 333-256470 10.21 5/25/2021 10.20 Lease Agreement by and between the Registrant and ARE-San Francisco No. 65, LLC, dated August 15, 2019, as amended. S-1 333-256470 10.22 5/25/2021 131 Table of Contents Incorporation by Reference Exhibit Number Exhibit Description Form File Number Exhibit/ Appendix Reference Filing Date Filed Herewith 10.21 Registration Rights Agreement, dated as of October 31, 2024, by and among the Registrant , each of the Sellers Party thereto and WT Representative LLC, solely in its capacity as the Representative of the Sellers. 8-K 001-40502 10.1 10/31/2024 10.22 Exclusive License Agreement by and between Kalthera, Inc., a subsidiary of the Registrant, and the Regents of the University of California, acting through The Technology Development Group of the University of California, Los Angeles (UCLA), dated February 18, 2021, as amended. 10-K 001-40502 10.22 3/11/2025 10.23 S ecurities Purchase A greement by and among the Registrant and the Purchasers listed therein, dated July 24, 2025. 8-K 001-40502 10.1 7/25/2025 10.24* Exclusive License Agreement by and between the Registrant and Innovative Cellular Therapeutics Holdings Limited and Innovative Cellular Therapeutics, Inc., dated November 6, 2025. X 10.25 R egistration Rights Agreement by and between the Registra nt and Innovative Cell ular Therapeutics Holdings Limited, dated November 6, 2025. X 19.1 Lyell Immunopharma, Inc. Insider Trading Policy. X 23.1 Consent of independent registered public accounting firm. X 24.1 Power of Attorney (included on signature page). X 31.1 Certification of Principal Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a). X 31.2 Certification of Principal Financial Officer Pursuant to Rules 13a-14(a) and 15d-14(a). X 32.1+ Certifications of Principal Executive Officer and Principal Financial Officer Pursuant to 18 U.S.C. Section 1350. X 97.1 Incentive Compensation Recoupment Policy dated September 6, 2023. 10-K 001-40502 97.1 2/28/2024 101.INS XBRL Instance Document. The XBRL 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. X 101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document. X 101.DEF Inline XBRL Taxonomy Extension Definition Linkbase Document. X 132 Table of Contents Incorporation by Reference Exhibit Number Exhibit Description Form File Number Exhibit/ Appendix Reference Filing Date Filed Herewith 101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document. X 101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document. X 104 Cover Page Interactive Data File. Formatted as Inline XBRL and contained in Exhibit 101. *Portions of this exhibit (indicated by [*]) have been omitted because the registrant has determined that the information is both not material and is the type that the registrant treats as private or confidential. # Indicates management contract or compensatory plan or arrangement. + The certifications attached as Exhibit 32.1 accompanying this Annual Report on Form 10-K are not deemed filed with the Securities and Exchange Commission and are not to be incorporated by reference into any filing of the Registrant under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date of this Annual Report on Form 10-K, irrespective of any general incorporation language contained in such filing. Item 16. Form 10-K Summary. None. 133 Table of Contents SIGNATURES Pursuant to the requirements of Section 13 or 15(d) of the Securities Act of 1934, the Registrant has duly caused this Annual Report on Form 10-K to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of South San Francisco, State of California on March 12, 2026. LYELL IMMUNOPHARMA, INC. By: /s/ LYNN SEELY Name: Lynn Seely, M.D. Title: President and Chief Executive Officer POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Lynn Seely, Smital Shah and Mark Meltz, and each of them, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10-K, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1934, this Annual Report on Form 10-K has been signed by the following persons on behalf of the Registrant and in the capacities and on the dates indicated: Signature Title Date /s/ LYNN SEELY President, Chief Executive Officer and Director March 12, 2026 Lynn Seely, M.D. (Principal Executive Officer) /s/ SMITAL SHAH Chief Financial and Business Officer March 12, 2026 Smital Shah (Principal Financial Officer) /s/ VERONICA SANCHEZ VP, Controller March 12, 2026 Veronica Sanchez (Principal Accounting Officer) /s/ RICHARD D. KLAUSNER Chair of the Board of Directors March 12, 2026 Richard D. Klausner, M.D. /s/ MARK BACHLEDA Director March 12, 2026 Mark Bachleda, Pharm.D. /s/ OTIS BRAWLEY Director March 12, 2026 Otis Brawley, M.D. /s/ CATHERINE FRIEDMAN Director March 12, 2026 Catherine Friedman /s/ ELIZABETH NABEL Director March 12, 2026 Elizabeth Nabel, M.D. /s/ SUMANT RAMACHANDRA Director March 12, 2026 Sumant Ramachandra, M.D., Ph.D. /s/ WILLIAM RIEFLIN Director March 12, 2026 William Rieflin 134