UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): ~~December 7~~March 6, ~~2025~~2026

Lyell Immunopharma, Inc.

(Exact name of Registrant as Specified in Its Charter)

Delaware

001-40502

83-1300510

(State or Other Jurisdiction

of Incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)


201 Haskins Way
South San Francisco, California		94080
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s Telephone Number, Including Area Code: 650 695-0677

(Former Name or Former Address, if Changed Since Last Report)

Not Applicable

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		~~TradingSymbol~~Trading Symbol(s)		Name of each exchange on which registered
Common Stock, $0.0001 par value per share		LYEL		~~The~~ Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8 5.0102 ~~Other~~Departure ~~Events~~of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On ~~December~~March 76, ~~2025~~2026, the Board of Directors of Lyell Immunopharma, Inc. (the “Company”) ~~presented~~approved at the ~~67th~~appointment ~~American Society~~ of ~~Hematology~~Smital ~~(ASH)~~Shah ~~Annual~~as ~~Meeting~~the ~~and~~Company’s ~~Exposition~~Chief ~~new~~Financial ~~clinical~~ and ~~translational~~Business ~~data~~Officer ~~from~~and ~~its~~principal ~~ongoing~~financial ~~clinical~~officer, ~~trial~~effective ofMarch 9, ~~rondecabtagene~~2026. ~~autoleucel~~Lynn ~~(ronde-cel~~Seely, ~~also known as LYL314) in patients with large B-cell lymphoma (“LBCL”)~~M.D., ~~Ronde-cel~~the isCompany’s anPresident ~~autologous dual-targeting CD19/CD20 chimeric antigen receptor (“CAR”) T-cell product candidate in pivotal development for patients with relapsed~~ and~~/or~~ ~~refractory~~Chief ~~(“R/R”)~~Executive ~~LBCL.~~Officer, ~~Ronde-cel~~previously ~~CAR~~served Tas ~~cells~~interim ~~are~~principal ~~designed~~financial to have enhanced antitumor activity through a proprietary manufacturing process that enriches for CD62L-positive cells to produce a CAR T-cell product with a higher proportion of naïve and central memory T cellsofficer.

~~Sixty-nine~~In ~~CAR~~connection ~~T-cell~~with ~~naïve~~Ms. Shah’s ~~patients~~appointment ~~with~~as ~~R/R~~the ~~LBCL~~Company’s ~~received~~Chief ~~ronde-cel~~Financial asand ofBusiness ~~September 5~~Officer, ~~2025 (~~the ~~data~~Company ~~cutoff~~and ~~date~~Ms. Shah ~~for~~entered ~~the~~into ~~presentation~~an atoffer ~~ASH).~~letter ~~The~~that ~~efficacy~~governs ~~evaluable~~the ~~population,~~terms ~~defined~~of asMs. Shah’s ~~those~~at-will ~~patients~~employment relationship with ~~Day~~the 84Company. ~~assessments~~Pursuant orto ~~prior~~the ~~disease~~offer ~~progression or death~~letter, ~~consisted~~Ms. Shah ofis 47entitled ~~patients~~to ~~(29~~receive inan ~~the~~initial ~~third-~~annual orbase ~~later-line~~salary ~~(“3L+”)~~of ~~setting~~$500,000 and 18a intarget ~~the~~annual ~~second-line~~bonus ~~(“2L”)~~of ~~setting).~~up ~~Patient~~to ~~demographics~~50% ~~and~~of ~~baseline~~her ~~disease~~base ~~characteristics~~salary. ~~were~~In ~~consistent~~addition, ~~with~~Ms. Shah will receive a ~~high-risk~~stock option for 140,000 shares ~~heavily~~of ~~pre-treated~~common ~~patient~~stock ~~population~~of the Company, ~~particularly~~with asan ~~compared~~exercise price equal to ~~historical~~the ~~trials~~fair market value of ~~CD19~~the ~~CAR~~common ~~T-cell~~stock ~~products:~~of ~~median~~the ~~ages~~Company on the date of 64grant, ~~and~~to 65be ~~years~~granted ~~with~~under ~~20%~~the ~~(9/45)~~Company’s ~~and~~2021 ~~21%~~Equity Incentive Plan. Twenty-five percent (~~5/24~~25%) of ~~patients~~the ~~being~~total 75shares ~~years~~subject orto ~~older~~the inoption will vest on the ~~3L+~~one-year ~~and~~anniversary 2Lof ~~settings,~~Ms. Shah’s ~~respectively;~~employment commencement date and ~~primary~~an ~~refractory~~additional ~~disease~~1/48th of the total shares subject to the option will vest in ~~49%~~equal ~~(22/45)~~monthly ~~and~~installments ~~92%~~thereafter, ~~(22/24)~~subject to Ms. Shah remaining an employee of ~~patients~~the Company on each applicable vesting date. Ms. Shah will participate in the ~~3L+~~Company’s ~~and~~Officer 2LSeverance ~~settings~~Plan, ~~respectively~~as amended (filed as Exhibit 10.1 to the Company’s Quarterly Report on Form 10-Q (No. 001-40502)) as a Tier I Employee (as defined therein).

~~Patients~~Prior ~~Evaluated~~to her appointment as the Company’s Chief Financial and Business Officer, Ms. Shah, 49, provided finance and business development consulting services to the Company since February 2026, and before that, since January 2023, served as an independent consultant to multiple biotech and life sciences companies on finance and business development strategy and operations. From October 2014 to December 2022, Ms. Shah served as Chief Business and Financial Officer of ProQR Therapeutics (Nasdaq: PRQR) overseeing all business functions related to finance, communications, commercial strategy, business development and legal. Previously, Ms. Shah managed the multi-billion-dollar debt, cash and investment portfolios of Gilead Sciences, Inc. Prior to Gilead, she was an investment banker at Leerink Partners and JP Morgan focused on capital raising and strategic transactions in the ~~3L+~~biotechnology ~~Setting~~space. Before that, Ms. Shah held various research and development roles at Johnson & Johnson Company. Ms. Shah holds a B.S. in Chemical Engineering from the University of Mumbai, an M.S. in Chemical Engineering from Virginia Tech and an M.B.A. in Finance from the University of California, Berkeley, Haas School of Business. Ms. Shah previously served on the Board of Directors of Pliant Therapeutics until June 2025 and was a Board Member and Chair of the Audit Committee at Graphite Bio until its merger with LENZ Therapeutics in March 2024.

~~There~~The ~~were~~Company 29has ~~efficacy-evaluable~~also ~~3L+~~entered ~~patients~~into ~~with~~its ~~R/R~~standard ~~LBCL~~indemnification ~~(diffuse~~agreement ~~large~~with ~~B-cell~~Ms. Shah ~~lymphoma,~~in ~~primary~~the ~~mediastinal~~form ~~B-cell~~previously ~~lymphoma,~~filed ~~Grade~~as ~~3B follicular lymphoma, or~~Exhibit ~~transformed~~10.9 ~~follicular~~to ~~lymphoma)~~the ~~with~~Company’s aRegistration ~~median~~Statement ~~follow~~on upForm ~~time~~S-1 of(No. 12333-256470), ~~months~~ as ofamended, filed with the ~~data~~Securities ~~cutoff~~and ~~date.~~Exchange InCommission ~~these~~on ~~patients:~~May 25, 2021.

• The ~~overall~~foregoing ~~response~~summary ~~rate~~of ~~was~~the ~~93%~~offer ~~(27/29~~letter ~~patients),~~does ~~with~~not ~~76%~~purport ~~(22/29)~~to be a complete description of ~~patients~~the ~~achieving~~offer aletter and is qualified in its entirety by reference to the complete ~~response~~text of the offer letter, which is filed as Exhibit 10.1 hereto.

•Item 9.01 ~~72%~~Financial ~~(13/18)~~Statements ofand ~~patients~~Exhibits. ~~with complete response remained in complete response at 6 months or longer~~

•(d) ~~Median~~Exhibits ~~progression-free survival was 18 months~~

Patients Evaluated in the 2L Setting


Exhibit Number		Description

10.1		Offer Letter, dated March 3, 2026, by and between Smital Shah and Lyell Immunopharma, Inc.

104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

There were 18 efficacy-evaluable patients enrolled in the 2L setting with a median follow-up time of 9 months as of the data cutoff date. Of these efficacy-evaluable patients, 94% had primary refractory disease. In these patients:

• The overall response rate was 83% (15/18 patients), with 61% (11/18) achieving a complete response

• 70% (7/10) of patients with complete response remained in complete response at ≥ 6 months

• The median duration of complete response was not reached

Safety Data

In 69 patients, including patients from both the 3L+ and the 2L cohorts, a manageable safety profile appropriate for outpatient administration was observed. No Grade 3 or greater cytokine release syndrome (“CRS”) was observed. Twenty-five of the 69 patients received protocol-directed dexamethasone prophylaxis (10 mg/day for 3 days). One case (4%) of Grade 3 or greater immune effector cell-associated neurotoxicity syndrome (“ICANS”) was reported in a patient with high disease burden; no case of Grade 2 ICANS was reported.

In all 69 patients, as of the data cutoff date, low rates of Grade 1 (32%) or Grade 2 (29%) CRS were reported; ICANS rates were reported as follows: Grade 1 (9%), Grade 2 (3%), and Grade 3 or greater (12%) of patients. The median time to complete resolution of all reports of ICANS was 4 days. Cell pharmacodynamic data demonstrated robust CAR T-cell expansion and persistence that were similar in patients with or without dexamethasone prophylaxis. No deaths were determined to be related to ronde-cel administration.

Ronde-cel Translational Data

Translational data from the ongoing Phase 1/2 clinical trial showed that ronde-cel manufactured with CD62L enrichment achieved robust expansion and high expression of memory-related genes after infusion in patients with LBCL. An evaluation of ronde-cel and published data for CD19 CAR T-cell products demonstrated that ronde-cel had a higher proportion of CD62L-positive T cells with a higher proportion of memory-cell phenotype prior to infusion (ronde-cel, N = 34; axi-cel, N = 110 and tisagenlecleucel (tisa-cel), N = 31). In addition, ronde-cel had up to a three-fold higher expansion in patients after infusion compared to the expansion of approved CD19 CAR T-cell products. The product memory-cell phenotype was positively correlated with expansion. Peripheral blood samples collected from patients one month after infusion (N = 9) also had a higher proportion of CAR T cells with a memory phenotype compared to cells from axi-cel-treated patients (N = 4). Ronde-cel CAR-positive T cells collected from patients one (N = 7) and two months (N = 3) after infusion demonstrated sustained capacity to proliferate, kill tumor cells over 72 hours, and secrete cytokines (N = 3).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Lyell Immunopharma, Inc.

Date: December 8, 2025

/s/ Mark Meltz

Date: March 9, 2026

/s/ Mark Meltz

Mark Meltz

General Counsel

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