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 ...

```markdown PART I—FINANCIAL INFORMATION [Item 1. Financial Statements (unaudited)](index=6&type=section&id=Item%201.%20Financial%20Statements%20(unaudited)) Unaudited Q1 2023 financials report a **$67.0 million net loss**, **$880.5 million total assets**, and **$46.2 million net cash used in operations** [Condensed Consolidated Balance Sheets](index=6&type=section&id=Condensed%20Consolidated%20Balance%20Sheets) Total assets decreased to **$880.5 million** by March 31, 2023, primarily due to reduced cash and marketable securities Condensed Consolidated Balance Sheet Highlights (in thousands) | Account | March 31, 2023 | December 31, 2022 | | :--- | :--- | :--- | | **Assets** | | | | Cash and cash equivalents | $109,426 | $123,554 | | Marketable securities (current & non-current) | $558,598 | $586,715 | | Total current assets | $624,398 | $651,295 | | Total assets | $880,450 | $937,561 | | **Liabilities & Stockholders' Equity** | | | | Total current liabilities | $30,797 | $37,028 | | Total liabilities | $96,624 | $104,309 | | Total stockholders' equity | $783,826 | $833,252 | | Total liabilities and stockholders' equity | $880,450 | $937,561 | [Condensed Consolidated Statements of Operations and Comprehensive Loss](index=7&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations%20and%20Comprehensive%20Loss) Q1 2023 net loss was **$67.0 million**, a slight improvement from prior year, impacted by lower G&A and an impairment Statement of Operations Summary (in thousands) | Metric | Three Months Ended March 31, 2023 | Three Months Ended March 31, 2022 | | :--- | :--- | :--- | | Revenue | $65 | $553 | | Research and development | $44,630 | $35,830 | | General and administrative | $19,279 | $34,421 | | Loss from operations | ($62,556) | ($68,576) | | Impairment of other investments | ($10,000) | $0 | | Net loss | ($66,959) | ($68,144) | | Net loss per common share, basic and diluted | ($0.27) | ($0.28) | [Condensed Consolidated Statements of Cash Flows](index=9&type=section&id=Condensed%20Consolidated%20Statements%20of%20Cash%20Flows) Q1 2023 saw **$46.2 million** net cash used in operations and **$32.2 million** provided by investing, resulting in a **$14.1 million** cash decrease Cash Flow Summary (in thousands) | Activity | Three Months Ended March 31, 2023 | Three Months Ended March 31, 2022 | | :--- | :--- | :--- | | Net cash used in operating activities | ($46,212) | ($47,852) | | Net cash provided by (used in) investing activities | $32,154 | ($26,122) | | Net cash (used in) provided by financing activities | ($69) | $2,555 | | **Net decrease in cash, cash equivalents and restricted cash** | **($14,127)** | **($71,419)** | [Notes to Unaudited Condensed Consolidated Financial Statements](index=10&type=section&id=Notes%20to%20Unaudited%20Condensed%20Consolidated%20Financial%20Statements) Notes confirm a 12-month cash runway, detail GSK termination, a **$10.0 million** investment impairment, and an unutilized **$200.0 million** ATM program - The company believes its available cash, cash equivalents, and marketable securities as of March 31, 2023, are **adequate** to fund operations for at least the **next 12 months**[32](index=32&type=chunk) - The collaboration agreement with GSK was **terminated** effective December 24, 2022, and the company has **discontinued further work** on the related programs (LYL331 and LYL132) Revenue from this agreement was **zero in Q1 2023**, down from **$0.6 million** in Q1 2022[50](index=50&type=chunk)[52](index=52&type=chunk) - The company recorded a **$10.0 million** impairment expense for one of its other investments during the three months ended March 31, 2023, determining its fair value to be **negligible**[63](index=63&type=chunk) - In August 2022, the company established an at-the-market (ATM) offering program to sell up to **$200.0 million** of its common stock To date, **no sales have been made** under this agreement[79](index=79&type=chunk) [Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations](index=25&type=section&id=Item%202.%20Management's%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) Management discusses pipeline progress, Q1 2023 financials with increased R&D and decreased G&A, confirming cash runway into 2026 Product Candidate Pipeline Status | Product Candidate | Modality | Target Indications | Status | Next Expected Milestone | | :--- | :--- | :--- | :--- | :--- | | LYL797 | CAR T Cell | TNBC, NSCLC | Phase 1 | Initial data in 1H 2024 | | LYL119 | CAR T Cell | ROR1+ Solid Tumors | Preclinical | Submit IND in 1H 2024 | | LYL845 | TIL | Melanoma, CRC, NSCLC | Phase 1 | Initial data in 2024 | - The company's LyFE™ manufacturing center in Bothell, Washington is **operational** and producing clinical supply for its Phase 1 trials At **full capacity**, it is expected to manufacture approximately **500 infusions per year**[113](index=113&type=chunk)[114](index=114&type=chunk) Comparison of Results of Operations (in thousands) | Line Item | Three Months Ended March 31, 2023 | Three Months Ended March 31, 2022 | Change | | :--- | :--- | :--- | :--- | | Research and development | $44,630 | $35,830 | $8,800 | | General and administrative | $19,279 | $34,421 | ($15,142) | | Loss from operations | ($62,556) | ($68,576) | $6,020 | | Net loss | ($66,959) | ($68,144) | $1,185 | - The company believes its existing cash, cash equivalents, and marketable securities of **$668.0 million** as of March 31, 2023, will be **sufficient** to meet working capital and capital expenditure needs **into 2026**[141](index=141&type=chunk)[144](index=144&type=chunk)[183](index=183&type=chunk) [Item 3. Quantitative and Qualitative Disclosures About Market Risk](index=34&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) Primary market risk is interest rate sensitivity on **$642.5 million** in short-term investments, considered not significant - The company's primary market risk is interest rate risk on its **$83.9 million** in cash equivalents and **$558.6 million** in marketable securities as of March 31, 2023 This risk is considered **not significant** due to the short-term nature of the investments[158](index=158&type=chunk) - The company has **no significant exposure** to foreign currency exchange risk as all operations and employees are currently located in the United States[159](index=159&type=chunk) [Item 4. Controls and Procedures](index=35&type=section&id=Item%204.%20Controls%20and%20Procedures) Disclosure controls and procedures were effective as of March 31, 2023, with no material changes during the quarter - The CEO and CFO concluded that as of March 31, 2023, the company's disclosure controls and procedures were **effective at a reasonable assurance level**[162](index=162&type=chunk) - **No material changes** to the company's internal control over financial reporting occurred during the quarter ended March 31, 2023[163](index=163&type=chunk) PART II—OTHER INFORMATION [Item 1. Legal Proceedings](index=36&type=section&id=Item%201.%20Legal%20Proceedings) The company is not party to any material legal proceedings, nor aware of any contemplated by authorities - As of the filing date, the company is **not party to any legal proceedings considered material** to its operations[166](index=166&type=chunk) [Item 1A. Risk Factors](index=36&type=section&id=Item%201A.%20Risk%20Factors) Key risks include early clinical stage, substantial losses, unproven technologies, manufacturing complexities, and need for additional capital - The company is an early clinical-stage biopharmaceutical company with a history of **substantial losses** (**$834.4 million** accumulated deficit as of March 31, 2023) and expects to incur increasing net losses for the foreseeable future[174](index=174&type=chunk) - The company's product candidates are based on novel, **unproven technologies**, which makes it difficult to predict the time and cost of development and the potential for regulatory approval[193](index=193&type=chunk) - Manufacturing of cellular therapies is **highly complex** and subject to risks such as product loss, contamination, and equipment failure, which could increase costs and delay programs[217](index=217&type=chunk) - The company's success payment obligations to Fred Hutch and Stanford, totaling up to **$400.0 million**, could result in **stockholder dilution or be a drain on cash resources** if triggered[185](index=185&type=chunk) [Item 2. Unregistered Sales of Equity Securities and Use of Proceeds](index=73&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) No unregistered equity sales occurred; **$391.8 million** IPO proceeds fund R&D, clinical trials, and general corporate purposes - The company raised approximately **$391.8 million** in net proceeds from its June 2021 IPO[369](index=369&type=chunk) - There has been **no material change** in the planned use of IPO proceeds, which are being used to fund R&D, clinical trials, and general corporate purposes[370](index=370&type=chunk) [Item 3. Defaults Upon Senior Securities](index=74&type=section&id=Item%203.%20Defaults%20Upon%20Senior%20Securities) This item is not applicable as the company has no defaults upon senior securities [Item 4. Mine Safety Disclosures](index=74&type=section&id=Item%204.%20Mine%20Safety%20Disclosures) This item is not applicable to the company [Item 5. Other Information](index=74&type=section&id=Item%205.%20Other%20Information) The company reported no other information for this item [Item 6. Exhibits](index=75&type=section&id=Item%206.%20Exhibits) This section lists exhibits filed with the Form 10-Q, including required certifications and XBRL data files ```

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 ...

DRAFT JPM22 Updated 12-14-21 Lyell Immunopharma August 4, 2022 Forward Looking Statements Certain matters discussed in this presentation are "forward-looking statements" of Lyell Immunopharma, Inc, Inc. (hereinafter referred to as the "Company," "we," "us," or "our") within the meaning of the Private Securities Litigation Reform Act of 1995 (the "PSLRA"). All such written or oral statements made in this presentation, other than statements of historical fact, are forward-looking statements and are intended t ...

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, 2022 OR ☐ 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) __________________________ Delawa ...

DRAFT JPM22 Updated 12-14-21 Lyell Immunopharma May 10, 2022 Forward Looking Statements Certain matters discussed in this presentation are "forward-looking statements" of Lyell Immunopharma, Inc, Inc. (hereinafter referred to as the "Company," "we," "us," or "our") within the meaning of the Private Securities Litigation Reform Act of 1995 (the "PSLRA"). All such written or oral statements made in this presentation, other than statements of historical fact, are forward-looking statements and are intended to ...