Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q __________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40502 __________________________ Lyell Immunopharma, Inc. (Exact Name of Registrant ...

Exhibit 99.1 Lyell Immunopharma Reports Business Highlights and Financial Results for the First Quarter 2024 SOUTH SAN FRANCISCO, Calif., May 6, 2024 -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a clinical‑stage T-cell reprogramming company advancing a diverse pipeline of cell therapies for patients with solid tumors today reported financial results and business highlights for the first quarter ended March 31, 2024. "The initial clinical and translational data from the Phase 1 trial of LYL797, our lead CAR T ...

Expect to share initial clinical and translational data from the Phase 1 trial of LYL797, a ROR1-targeted CAR T‑cell product candidate, this quarterOn track to report initial clinical data from the Phase 1 trial of LYL845, an epigenetically enhanced TIL product candidate, in the second half of 2024IND for second generation ROR1-targeted CAR T-cell product candidate on track for submission this quarterCash, cash equivalents and marketable securities of $526.3 million as of March 31, 2024 supports advancing d ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 _________________________________ FORM 10-K _________________________________ (Mark One) (Address of Principal Executive Offices) (Zip Code) o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 001-40502 _________________________________ Lyell Immunopharma, Inc. _________________________________ (Exact name of registrant as s ...

Exhibit 99.1 Lyell Immunopharma Reports Business Highlights and Financial Results for the Fourth Quarter and Full Year 2023 SOUTH SAN FRANCISCO, Calif., Feb. 28, 2024 -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a clinical‑stage T-cell reprogramming company advancing a diverse pipeline of cell therapies for patients with solid tumors today reported financial results and business highlights for the fourth quarter and year ended December 31, 2023. "We are focused on generating clinical data in our two Phase 1 ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q __________________________ (Mark One) ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40502 __________________________ Lyell Immunopharma, Inc. (Exact Name of Registrant as Specified in its Charter) __________________________ Delaware 83-1300510 (State or other jurisdiction of incorporation or organization) ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q __________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40502 __________________________ Lyell Immunopharma, Inc. (Exact Name of Registrant a ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q __________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to (Exact Name of Registrant as Specified in its Charter) __________________________ Delaware 83-1300510 (State or ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 _________________________________ FORM 10-K _________________________________ (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 001-40502 _________________________________ Lyell Immu ...

FORM 10-Q __________________________ (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 OR Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40502 __________________________ Lyell Immunopharma, Inc. (Exact Name of Registr ...