Lyell Immunopharma Inc 2025年度报告

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 (Mark One) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December31, 2025 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Lyell Immunopharma, Inc. (Exact name of registrant as specified in its charter) Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule405 of the Securities Act. YesNo Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. YesNo Indicate by check mark whether the registrant: (1)has filed all reports required to be filed by Section13 or 15(d) of the SecuritiesExchange Act of 1934 during the preceding 12months (or for such shorter period that the registrant was required to file such reports); and(2)has been subject to such filing requirements for the past 90days. YesNo Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant toRule405 of Regulation S-T (§232.405 of this chapter) during the preceding 12months (or for such shorter period that the registrant wasrequired to submit such files). YesNo Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reportingcompany, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reportingcompany,” and “emerging growth company” in Rule12b-2 of the Exchange Act. If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period forcomplying with any new or revised financial accounting standards provided pursuant to Section13(a) of the Exchange Act. Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness ofits internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered publicaccounting firm that prepared or issued its audit report. If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrantincluded in the filing reflect the correction of an error to previously issued financial statements. Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-basedcompensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). Indicate by check mark whether the registrant is a shell company (as defined in Rule12b-2 of the Act). YesNo The aggregate market value of the common stock held by non-affiliates of the registrant on June30, 2025, the last business day of theregistrant’s most recently completed second fiscal quarter, was approximately $129million based on the closing price reported for suchdate on The Nasdaq Global Select Market. The registrant had 23,307,143 shares of common stock outstanding as of March9, 2026. DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s Proxy Statement for the 2026 Annual Meeting of Stockholders are incorporated herein by reference in PartIIIof this Annual Report on Form 10-K to the extent stated herein. Such proxy statement will be filed with the Securities and ExchangeCommission within 120 days of the registrant’s fiscal year ended December31, 2025. Lyell Immunopharma, Inc.2025 Annual Report on Form 10-KTable of Contents Special Note Regarding Forward-Looking StatementsSummary of Risk Factors PART I Item 1.BusinessItem 1A.Risk FactorsItem 1B.Unresolved Staff CommentsItem 1C.CybersecurityItem 2.PropertiesItem 3.Legal ProceedingsItem 4.Mine Safety Disclosures PART II Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities81Item 6.[Reserved]81Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations82Item 7A.Quantitative and Qualitative Disclosures About Market Risk93Item 8.Financial Statements and Supplementary Data94Item 9.Changes in and Disagreements With Accountants on Accounting and Financial Disclosure127Item 9A.Controls and Procedures127Item 9B.Other Information128Item 9C.Disclosure Regarding Foreign Jurisdictions that Prevent Inspections128 Item 10.Directors, Executive Officers and Corporate GovernanceItem 11.Executive CompensationItem 12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder MattersItem 13.Certain Relationships and Related Transactions, and Director IndependenceItem 14.Principal Accountant Fees and Services PART IV Item 15.Exhibits and Financial Statement SchedulesItem 16.Form 10-K Summary SIGNATURE