Lyell Immunopharma, Inc.

1. Organization

Lyell Immunopharma, Inc. (the “Company”) was incorporated in Delaware in June 2018. The Company is a late‑stage clinical cell therapy company advancing a pipeline of proprietary next-generation autologous chimeric antigen receptor (“CAR”) T-cell product candidates for patients with hematologic malignancies and solid tumors. The Company’s lead product candidate, rondecabtagene autoleucel (ronde-cel, also known as LYL314), is an autologous dual‑targeting CD19/CD20 CAR T‑cell therapy in development for large B-cell lymphoma (LBCL). The Company has recently acquired exclusive global rights to a novel guanylyl cyclase-C (“GCC”)-targeted CAR T-cell product candidate in early clinical development for refractory metastatic colorectal cancer (mCRC) and other GCC-expressing cancers. The Company’s primary activities since incorporation have been to develop T‑cell therapies, conduct research and development, execute clinical trials, enable and execute manufacturing activities in support of its product candidate development efforts, submit regulatory submissions, acquire technology and product candidates, enter into strategic license and collaboration arrangements, organize and staff the Company, conduct business planning, establish its intellectual property portfolio, raise capital and provide general and administrative support for these activities.

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany transactions and balances have been eliminated in consolidation. Certain prior period amounts have been reclassified to conform with the current period presentation.

The condensed consolidated balance sheet as of December 31, 2024 included herein was derived from the audited consolidated financial statements as of that date. Certain information and footnote disclosures typically included in the Company’s audited consolidated financial statements have been condensed or omitted. The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented, but are not necessarily indicative of results to be expected for any future annual or interim period.

These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024.

Reverse Stock Split

On May 30, 2025, the Company effected a 1-for-20 reverse stock split (“Reverse Split”) of its issued and outstanding shares of common stock, and the common stock began trading on a split-adjusted basis on June 2, 2025. The Reverse Split did not reduce the total number of authorized shares of common stock or the Company’s preferred stock or change the par values per share of the common stock or preferred stock. The Reverse Split affected all stockholders uniformly and did not affect any stockholder’s ownership percentage of the shares of common stock (except to the extent that the Reverse Split resulted in some of the stockholders receiving cash in lieu of fractional shares). All outstanding equity awards entitling their holders to shares of common stock were adjusted as a result of the Reverse Split, in accordance with the terms of each such security. In addition, the number of shares reserved for future issuance pursuant to the Company’s equity incentive plans was adjusted accordingly. As a result, all historical per share data, the number of shares issued and outstanding and outstanding equity awards for the periods presented in the accompanying condensed consolidated financial statements and notes thereto have been adjusted retroactively in this Form 10-Q, where applicable, to reflect the Reverse Split. As the par value per share of the common stock was unchanged, corresponding amounts have been reclassified from common stock to additional paid-in capital.

Liquidity and Management’s Plan

The Company discovers and develops product candidates that involve experimental technologies. The product candidates may require several years and substantial expenditures to complete and ultimately may be unsuccessful. The Company plans to finance operations with available cash resources or from the issuance of equity or debt securities. The Company believes that its available cash, cash equivalents and marketable securities as of September 30, 2025 will be adequate to fund its operations at least through the next 12 months from the date these unaudited condensed consolidated financial statements are issued.

Use of Estimates

The preparation of the Company’s unaudited condensed consolidated financial statements in conformity with GAAP requires management to make judgments, estimates and assumptions that affect reported amounts and related disclosures. Specific accounts that require management estimates include, but are not limited to, stock-based compensation, valuation of long-lived assets, the SPA put/call (as defined below) asset, other investments and accrued expenses. See Note 9, Stockholders’ Equity - Securities Purchase Agreement, for additional information regarding the SPA put/call. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates.

Concentrations of Credit Risk and Off-balance Sheet Risk

The Company maintains its cash, cash equivalents and restricted cash with high quality, accredited financial institutions. Restricted cash is cash held in a bank account and is used as collateral associated with the Company’s corporate credit card program as well as collateral for a letter of credit in favor of one of the Company’s landlords. Cash, cash equivalents and restricted cash amounts, at times, may exceed federally insured limits. The Company also makes short-term investments in money market funds, U.S. Treasury securities, U.S. government agency securities and corporate debt securities, which can be subject to certain credit risk. However, the Company mitigates the risks by investing in high‑grade instruments, limiting exposure to any one issuer or type of investment and monitoring the ongoing creditworthiness of the financial institutions and issuers. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to significant risk on these funds. The Company has no off‑balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.

Significant Accounting Policies

There have been no material changes to the significant accounting policies from the Annual Report on Form 10-K for the year ended December 31, 2024 other than for the SPA put/call, which is described below.

Securities Purchase Agreement Put/Call

In July 2025, the Company entered into a Securities Purchase Agreement (the “SPA”) with certain institutional and other accredited investors (the “Purchasers”) that provided both the Company and the Purchasers with mutually exclusive rights, but not obligations, to purchase or sell additional shares of the Company’s common stock (or pre‑funded warrants in lieu thereof) under specified conditions. These rights include (i) the Company’s option to require investors to purchase additional equity securities upon the achievement of a defined milestone event (the “Milestone Closing”) and (ii) the investors’ option to purchase a similar dollar amount of equity securities at a fixed price prior to the Milestone Closing (the “Investor Call Closing”). Because the Milestone Closing and Investor Call Closing are mutually exclusive, they are accounted for as a single combined financial instrument, the SPA put/call.

The Company evaluates freestanding equity‑linked instruments to determine their appropriate classification as an asset, liability or equity. This assessment considers the guidance in ASC 480, Distinguishing Liabilities from Equity, and ASC 815, Derivatives and Hedging, including the own‑equity scope exception in ASC 815‑40. Based on this evaluation, the SPA put/call does not meet the definition of a derivative and does not qualify for equity classification. Accordingly, the SPA put/call is recognized as a freestanding financial asset at fair value on the date of issuance, with subsequent changes in fair value recognized in earnings. The Company reassesses the classification and measurement of the SPA put/call at each reporting date.

Recent Accounting Pronouncements

Recently Adopted

None.

Not Yet Adopted

Income Taxes

In December 2023, the FASB issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which includes amendments that further enhance income tax disclosures, primarily through standardization and disaggregation of rate reconciliation categories and income taxes paid by jurisdiction. The amendments are effective for annual periods beginning after December 15, 2024 and may be applied either prospectively or retrospectively. The Company is currently evaluating the impact of ASU 2023-09 on its consolidated financial statements.

Income Statement Expense Disaggregation

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures, to require more detailed information about specified categories of expenses (purchases of inventory, employee compensation, depreciation and amortization) included in certain expense captions presented on the face of the income statement. This ASU is effective for fiscal years beginning after December 15, 2026, and for interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The amendments may be applied either (1) prospectively to financial statements issued for reporting periods after the effective date of this ASU or (2) retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact of ASU 2024-03 on its consolidated financial statements.

3. Contingent Consideration Payable and Royalty Payments

On October 31, 2024 (the “Closing Date”), the Company completed its acquisition of ImmPACT Bio USA Inc., a Delaware corporation (“ImmPACT”), pursuant to the Agreement and Plan of Merger (the “Merger Agreement”). Pursuant to the terms of the Merger Agreement, on the Closing Date, the Company acquired all of the outstanding equity interests of ImmPACT in exchange for an upfront payment of $30.0 million in cash (in addition to approximately $11.9 million for ImmPACT’s existing cash balance, net of certain of ImmPACT’s unpaid transaction expenses) and 1.875 million shares of Company common stock. Contingent consideration following the Closing Date includes (a) additional equity consideration of 625,000 shares of Company common stock (“contingent consideration payable”) earned upon the achievement of the earlier to occur of (i) the demonstration of certain clinical milestones or (ii) the receipt of certain regulatory approvals and (b) a low single-digit royalty on future net sales of the dual-targeting CD19/20 CAR T‑cell product in the United States.

During the nine months ended September 30, 2025, the Company achieved a specified clinical milestone related to the contingent consideration payable from the acquisition of ImmPACT. The completion of the milestone triggered the Company’s obligation to issue the additional equity consideration of 625,000 shares of Company common stock valued at $5.9 million to certain former stockholders of ImmPACT, which were issued in July 2025. The issuance fulfilled the contingent consideration payable obligation under the Merger Agreement. The contingent consideration payable obligation was valued at initial issuance and quarterly going forward based on certain valuation inputs, including the closing share price of the Company’s common stock on the respective issuance and reporting dates and the probability of meeting the milestone prior to achievement, as further discussed in Note 7, Fair Value Measurements. The remeasurement of the contingent consideration payable resulted in a loss of $0.4 million and a gain of $1.7 million for the three and nine months ended September 30, 2025, respectively, recognized in other (expense) income, net in the Company’s Condensed Consolidated Statements of Operations and Comprehensive Loss.

The Company determined that the contingent consideration for the royalty payments is not subject to derivative accounting under ASC 815, Derivatives and Hedging, as its settlement is contingent upon future net sales of the Company's dual-targeting CD19/20 CAR T-cell product in the United States. Therefore, the Company did not record an associated contingent consideration liability on the acquisition date for the royalty payments. The Company will recognize any future contingent consideration payments in the period in which the royalty payments become due and payable. The Company has not made or accrued for contingent payments relating to the royalty payments as these have not become due and payable.

4. License, Collaboration and Success Payment Agreements

Fred Hutch

License Agreement - In 2018, the Company entered into a license agreement with Fred Hutchinson Cancer Center (“Fred Hutch”)that grants the Company a worldwide, sublicensable license under certain patent rights (exclusive) and certain technology (non-exclusive) to research, develop and commercialize products and processes for all fields of use utilizing chimeric antigen receptors (“CARs”) and/or T-cell receptors (“TCRs”), subject to certain exceptions.

Collaboration and Success Payments - In 2018, the Company entered into a research and collaboration agreement with Fred Hutch (“Fred Hutch Collaboration Agreement”), pursuant to which it granted Fred Hutch rights to certain success payments. The potential payments for the Fred Hutch success payments are based on multiples of increased value ranging from 10 times to 50 times based on a comparison of the per share fair market value of the Company’s common stock relative to the original $36.58 per share issuance price of the Company’s Series A convertible preferred stock, which converted into an equal number of shares of the Company’s common stock in connection with the closing of the Company’s initial public offering (“IPO”). The aggregate success payments to Fred Hutch are not to exceed $200.0 million, which would only occur upon a 50 times increase in value relative to the original $36.58 per share issuance price of the Company’s Series A convertible preferred stock. Each threshold is associated with a success payment, ascending from $10.0 million at $365.76 per share to $200.0 million at $1,828.80 per share, payable if such threshold is reached during the measurement period. The term of the success payment agreement ends on the earlier to occur of (i) thenine-year anniversary of the date of the agreement and (ii) a change in control transaction. All per-share values, including the original Series A issuance price referenced herein, have been retroactively adjusted to reflect the Reverse Split effected on May 30, 2025. See Note 2, Summary of Significant Accounting Policies, for additional information regarding the Reverse Split.

The following table summarizes the aggregate potential success payments, which are payable to Fred Hutch in cash or cash equivalents, or at the Company’s discretion, publicly-tradeable shares of the Company’s common stock:

The success payments will be owed if the per share fair value of the Company’s common stock on the contractually specified valuation measurement dates during the term of the success payment agreement equals or exceeds the above outlined multiples. The valuation measurement dates are triggered by the following events: theone-year anniversary of the Company’s IPO and eachtwo-year anniversary of the Company’s IPO thereafter, the closing of a change in control transaction and the last day of the term of the success payment agreement, unless the term has ended due to the closing of a change of control transaction. As of September 30, 2025, no success payments have been incurred as the per share fair value of the Company’s common stock was below the price required for payment.

The success payment liability was approximately $0.2 million and $0.1 million as of September 30, 2025 and December 31, 2024, respectively, which is recognized in accrued liabilities and other current liabilities. With respect to the Fred Hutch Collaboration Agreement success payment obligations, the Company recognized success payment expense of $0.2 million and expense reversal of $0.1 million for the three months ended September 30, 2025 and 2024, respectively, and success payment expense of $0.1 million and expense reversal of $0.4 million for the nine months ended September 30, 2025 and 2024, respectively, which are recognized in other (expense) income, net.

Stanford

License Agreement- In 2019, the Company entered into a license agreement with The Board of Trustees of the Leland Stanford Junior University (“Stanford”) to license specified patent rights.

Collaboration and Success Payments- In October 2020, the Company entered into a research and collaboration agreement with Stanford (“Stanford Collaboration Agreement”), pursuant to which it granted Stanford rights to certain success payments. The potential payments for the Stanford Collaboration Agreement success payments are based on multiples of increased value ranging from 10 times to 50 times based on a comparison of the per share fair market value of the Company’s common stock relative to the original $36.58 per share issuance price of the Company’s Series A convertible preferred stock, which converted into an equal number of shares of the Company’s common stock in connection with the closing of the Company’s IPO. The aggregate success payments to Stanford are not to exceed $200.0 million, which would only occur upon a 50 times increase in value relative to the original $36.58 per share issuance price of the Company’s Series A convertible preferred stock. Each threshold is associated with a success payment, ascending from $10.0 million at $365.76 per share to $200.0 million at $1,828.80 per share, payable if such threshold is reached during the measurement period. The term of each success payment agreement ends on the earlier to occur of (i) thenine-year anniversary of the date of the agreement and (ii) a change in control transaction. All per-share values, including the original Series A issuance price referenced herein, have been retroactively adjusted to reflect the Reverse Split effected on May 30, 2025. See Note 2, Summary of Significant Accounting Policies, for additional information regarding the Reverse Split.

The following table summarizes the aggregate potential success payments, which are payable to Stanford in cash or cash equivalents, or at the Company’s discretion, publicly-tradeable shares of the Company’s common stock:

The success payments will be owed if the per share fair value of the Company’s common stock on the contractually specified valuation measurement dates during the term of the success payment agreement equals or exceeds the above outlined multiples. The valuation measurement dates are triggered by the following events: theone-year anniversary of the Company’s IPO and eachtwo-year anniversary of the Company’s IPO thereafter, the closing of a change in control transaction and the last day of the term of the success payment agreement, unless the term has ended due to the closing of a change of control transaction. As of September 30, 2025, no success payments have been incurred as the per share fair value of the Company’s common stock was below the price required for payment.

The success payment liability is estimated at the fair value at inception and at each subsequent reporting period and the expense is accreted over the service period of the Stanford Collaboration Agreement as research and development expense through September 2024. As of October 2024, the Company’s associated success payment liability was fully accreted to fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The success payment liability was $0.4 million and $0.3 million as of September 30, 2025 and December 31, 2024, respectively, which is recognized in accrued liabilities and other current liabilities. With respect to the Stanford Collaboration Agreement success payment obligations, the Company recognized success payment expense of $0.3 million and $0.1 million for the three and nine months ended September 30, 2025, respectively, which are recognized in other (expense) income, net. The Company recognized success payment expense reversal of approximately zero and $0.3 million for the three and nine months ended September 30, 2024, respectively, which are recognized in research and development expense.

5. Cash Equivalents and Marketable Securities

The fair value and amortized cost of cash equivalents and fixed income marketable securities by major security type are as follows (in thousands):

The fair values of money market and fixed income marketable securities held by the Company in an unrealized loss position for less than 12 months were $47.8 million and $31.7 million as of September 30, 2025 and December 31, 2024, respectively. The fair values of money market and fixed income marketable securities held by the Company in an unrealized loss position for greater than 12 months were zero as of both September 30, 2025 and December 31, 2024. As of September 30, 2025 and December 31, 2024, all of the Company’s money market and fixed income marketable securities had a maturity date oftwo years or less, were available for use and were classified as available‑for‑sale. The Company does not intend to sell these securities nor does the Company believe that it will be required to sell these securities before recovery of their amortized cost basis. The Company determined that there was no material change in the credit risk of the above investments as of both September 30, 2025 and December 31, 2024. As such, an allowance for credit losses has not been recognized. Gross realized gains and losses werede minimis for the three and nine months ended September 30, 2025 and 2024 and as a result, amounts reclassified out of accumulated other comprehensive income for the three and nine months ended September 30, 2025 and 2024 were alsode minimis. See Note 7, Fair Value Measurements, for additional information regarding cash equivalents and fixed income marketable securities.

6. Other Investments

In prior years the Company made minority ownership strategic investments. As of September 30, 2025 and December 31, 2024, the aggregate carrying amount of the Company’s strategic investments in non-publicly traded companies was $19.0 million. These investments are measured at initial cost, minus impairment, if any, and plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Cumulative impairments of strategic investments in equity investments without readily determinable fair values still held as of both September 30, 2025 and December 31, 2024 were $23.0 million, reflecting the full impairment of two of the Company’s other investments.

As a part of the acquisition of each of the Company’s other investments, the Company determines whether an investment or other interest is considered a variable interest. As of both September 30, 2025 and December 31, 2024, the Company held an interest inone entity that was concluded to be a variable interest for which the Company was not the primary beneficiary as the Company did not have the power to direct the activities that most significantly impact the economic performance of the variable interest entity. As of both September 30, 2025 and December 31, 2024, the carrying value and maximum exposure to loss of the Company’s variable interests waszero.

In connection with the preparation of the financial statements for the nine months ended September 30, 2025 and 2024, the Company performed a qualitative assessment of potential indicators of impairment. The Company had previously determined in the second quarter of 2024 that indicators existed for one of its other investments with a carrying amount of $13.0 million. This resulted in impairment expense ofzero and $13.0 million for the nine months ended September 30, 2025 and 2024, respectively. The impairment expense was recorded within impairment of other investments on the condensed consolidated statements of operations and comprehensive loss and as a reduction to the investment balance within other investments on the condensed consolidated balance sheets.

7. Fair Value Measurements

The following table sets forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands):

The Company measures the fair value of money market funds based on quoted prices in active markets for identical assets or liabilities. The Company measures the fair value of marketable equity securities traded in active markets based on quoted prices of identical assets. The Level 2 marketable securities include U.S. Treasury securities, U.S. government agency securities and corporate debt securities, which are valued using third-party pricing sources. The pricing services applied industry standard valuation models. Inputs utilized include market pricing based on real-time trade data for the same or similar securities and other significant inputs derived from or corroborated by observable market data.

In July 2025, the Company completed a $50.0 million equity financing that included issuance of mutually exclusive put and call rights related to potential future equity issuance of up to an additional $50.0 million financing. These rights were accounted for as a combined financial asset or liability and measured at fair value on a recurring basis. See Note 2, Summary of Significant Accounting Policies - Securities Purchase Agreement Put/Call, for additional information regarding the accounting considerations of the SPA put/call. The SPA put/call is presented within prepaid expenses and other current assets on the Company’s condensed balance sheet as of September 30, 2025. See Note 9, Stockholders’ Equity - Securities Purchase Agreement, for additional information regarding the SPA put/call asset. The SPA put/call is classified as a Level 3 financial instrument and the fair value at inception on July 24, 2025 and period-end on September 30, 2025 was estimated using a Monte Carlo simulation valuation method including the following assumptions:

The Company’s contingent consideration payable and success payment liabilities are classified as Level 3 financial instruments. In July 2025, the Company issued 625,000 shares of common stock valued at $5.9 million upon achievement of a specific clinical milestone, thereby settling the contingent consideration payable related to the ImmPACT acquisition. Prior to settlement, the liability was valued using the Company’s common stock price and management’s assessment of the probability of achieving either (i) specified clinical milestones or (ii) certain regulatory approvals. The success payment liabilities were estimated by management using its historical experience of the correlation of success payment fair values relative to the Company’s stock price. See Note 3, Contingent Consideration Payable and Royalty Payments, for additional information regarding the contingent consideration payable.

The Company utilizes estimates and assumptions in determining the estimated contingent consideration payable, success payment liabilities and SPA put/call and associated changes in fair value. A change in management’s assessment of the likelihood of achieving any of (i) the specified clinical milestones, (ii) certain regulatory approvals related to the estimated valuation of the contingent consideration payable or (iii) a clinical milestone relating to the Company’s ongoing PiNACLE pivotal trial or certain other corporate milestones relevant to the SPA put/call may have a material change in its estimated fair value. Similarly, a small change in the valuation of the Company’s common stock may have a material change in the estimated fair value of the success payment liability and SPA put/call and associated changes in fair value.

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities (in thousands):

(1)The change in fair value of the contingent consideration payable, success payment liabilities and SPA put/call are recorded in other (expense) income, net.

8. Leases

The Company’s lease portfolio is comprised of operating leases for laboratory, office and manufacturing facilities located in South San Francisco and Los Angeles, California, and Seattle and Bothell, Washington with contractual periods expiring between January 2028 and March 2031. In addition to minimum rent, the leases require payment of real estate taxes, insurance, common area maintenance charges and other executory costs. These additional charges are considered variable lease costs and are recognized in the period in which the costs are incurred.

The following table summarizes the Company’s future minimum operating lease commitments as of September 30, 2025 (in thousands):

The operating lease costs for all operating leases were $2.2 million for both the three months ended September 30, 2025 and 2024, and $7.0 million and $6.8 million for the nine months ended September 30, 2025 and 2024, respectively. The operating lease costs and total commitments for short-term leases werede minimisfor the three and nine months ended September 30, 2025 and 2024. Variable lease costs for operating leases were $1.6 million for both the three months ended September 30, 2025 and 2024 and $5.4 million and $5.5 million for the nine months ended September 30, 2025 and 2024, respectively. The weighted-average remaining lease terms for operating leases were 5.0 and 5.7 years as of September 30, 2025 and December 31, 2024, respectively. The weighted‑average discount rate for operating leases was 8.5% as of both September 30, 2025 and December 31, 2024.

The Company entered into subleases in May 2021 and September 2024, whereby the Company agreed to sublease approximately 11,000 and 12,150 square feet, respectively, of its currently leased space in South San Francisco, California. These subleases are classified as operating leases and will expire in March 2031 and July 2026, respectively.

In September 2021, the Company entered into a sublease with Sonoma Biotherapeutics, Inc. (“Sonoma”), a related party, whereby the Company agreed to sublease approximately 18,000 square feet of space in South San Francisco, California currently leased by the Company. See Note 13, Related-Party Transactions. As a part of the sublease, in September 2021, the Company received a $4.6 million tenant improvement contribution payment, which is recognized over the term of the sublease. The sublease is classified as an operating lease and will expire in March 2031 if the approximate five-year renewal term is exercised.

The Company’s sublease income is recognized within other operating income, net in the condensed consolidated statements of operations and comprehensive loss. Total operating income from the subleases and income solely attributable to the subleases are shown in the table below (in thousands). Total operating income includes income attributable to the subleases, as well as additional operating fees recognized in other operating income, net such as common area maintenance charges.

As a result of the successful transition of the manufacturing of ronde-cel from the Company’s West Hills, Los Angeles manufacturing facility to the Company's LyFE Manufacturing Center TM in Bothell, Washington, and in connection with the planned closure of the West Hills facility, the associated lease has been classified as a separate asset group as of June 30, 2025. The Company performed an impairment assessment for the nine months ended September 30, 2025. The Company concluded that the carrying value of the West Hills asset group was not recoverable as it exceeded the future undiscounted cash flows the asset is expected to generate from its use and eventual disposition. The Company applied a discounted cash flow method to estimate the fair value of the right‑of-use asset, which represented level 3 nonrecurring fair value measurements. Based on this analysis, the Company recognized long-lived asset impairment charges of $1.4 million for the nine months ended September 30, 2025 within impairment of long-lived assets in the condensed consolidated statements of operations and comprehensive loss.

9. Stockholders’ Equity

Preferred Stock

The Company is authorized to issue 10 million shares of preferred stock with a par value of $0.0001 per share. As of September 30, 2025 and December 31, 2024, no shares of preferred stock were outstanding.

Common Stock

The Company is authorized to issue 500 million shares of common stock with a par value of $0.0001 per share. As of September 30, 2025 and December 31, 2024, there were 19,293,951 shares and 14,743,777 shares of the Company’s common stock outstanding, respectively.

On February 28, 2024, the Company entered into a sales agreement with Cowen and Company, LLC (“Cowen”) acting as the Company’s sales agent (the “Sales Agreement”), pursuant to which the Company may offer and sell shares of common stock having an aggregate offering price of up to $150.0 million from time to time in a series of one or more at‑the‑market equity offerings. The Company will pay Cowen commissions of up to 3.0% of the gross proceeds of the sale, and reimbursement of certain expenses, under this agreement. Neither the Company nor Cowen is obligated to sell any shares and, to date, the Company has not made any sales under the Sales Agreement.

Securities Purchase Agreement

In July 2025, the Company entered into the SPA with the Purchasers, pursuant to which the Company sold and issued 3,753,752 shares of common stock at a purchase price of $13.32 per share at an initial closing, for gross proceeds of approximately $50.0 million.

Pursuant to the SPA, the Company has the right, but not the obligation, to require the Purchasers to purchase approximately $50.0 million of additional shares of common stock (and/or pre-funded warrants in lieu of common stock) at a closing (the “Milestone Closing”) upon the occurrence of a milestone event within 12 months following the initial closing. The purchase price per share of common stock in the Milestone Closing will be $25.61, unless the closing price of the common stock on the date before the Milestone Closing is less than $10.41, in which case it will be $10.41 per share. If the purchase price in the Milestone Closing will be $10.41 per share, the Company may rescind its Milestone Closing election before completion of the Milestone Closing.

At any time before the Milestone Closing and until the later of 12 months following the initial closing and 40 days after the Purchasers receive notice from the Company of the achievement of a milestone event, each Purchaser will have the right, but not the obligation, to purchase at a closing (each, an “Investor Call Closing”) the same dollar amount of common stock (or pre-funded warrants in lieu thereof) it has committed to purchase in the Milestone Closing, at a purchase price of $30.73 per share. If any Purchaser exercises its right to hold its Investor Call Closing, it will not participate in any subsequent Milestone Closing. In addition, subject to specified exceptions, if the Company completes a bona fide equity financing for capital-raising purposes on terms that are more favorable to investors than the terms of the Investor Call Closing, the Company’s right to hold the Milestone Closing will terminate. The Milestone Closing and Investor Call Closing (the “SPA put/call”) were determined to be a combined financial instrument as they are mutually exclusive. The Company evaluated the SPA put/call under ASC 815 and concluded it does not meet the definition of a derivative. See Note 7, Fair Value Measurements, for additional information regarding the valuation of the SPA put/call asset.

10. Stock-based Compensation

Equity Incentive and Employee Stock Purchase Plans

In June 2021, the Company adopted the 2021 Equity Incentive Plan (“2021 Plan”) and the 2021 Employee Stock Purchase Plan (“2021 ESPP”), both of which became effective on the date of the underwriting agreement related to the Company’s IPO. Under the 2021 Plan, the Company may grant incentive stock options, non-statutory stock options, restricted stock awards (“RSAs”), restricted stock units (“RSUs”), performance-based restricted stock units (“PSUs”), stock appreciation rights, performance awards and other stock-based awards. The term of any stock option granted under the 2021 Plan cannot exceedten years. Generally, stock options (other than performance-based stock options, discussed below) and RSU awards granted by the Company vest over four years but may be granted with different vesting terms. PSUs generally vest over athree-year performance period, subject to the achievement of the associated performance condition.

On January 1, 2025, the Company reserved an additional 737,188 shares of common stock for issuance under the 2021 Plan representing 5% of the total common shares outstanding as of December 31, 2024. The Company’s board of directors elected to reserveno additional shares under the 2021 ESPP for the year beginning January 1, 2025.

The 2021 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their earnings, subject to plan limitations. Unless otherwise determined by the Company’s board of directors, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first date of an offering or on the purchase date. Under the 2021 ESPP,26,062 shares were issued for the three and nine months ended September 30, 2025 and 24,565 shares were issued for the three and nine months ended 2024.

As of September 30, 2025,2,310,205 and 226,570 shares were available for future issuance pursuant to the 2021 Plan and the 2021 ESPP, respectively.

Stock-based Compensation Expense

Stock-based compensation expense by classification included within the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands):

At September 30, 2025, total stock-based compensation cost related to unvested awards not yet recognized was $29.8 million, which is expected to be recognized over a remaining weighted-average period of 2.1 years.

Stock Options Repricing

In November 2023, the Board of Directors of the Company approved, effective November 16, 2023, a one-time repricing of certain stock option awards that had been granted to date under the 2021 Plan and 2018 Plan. The repricing impacted stock options with exercise prices greater than $47.40 held by employees who remained employed as of November 16, 2023 and were not impacted by the Company’s November 2023 reduction in workforce. The original exercise prices of the repriced stock options ranged from $52.20 to $359.00 per share for 200 total grantees with 1,170,843 shares repriced. Each stock option was repriced to have a per share exercise price of $37.40, which was the closing price of the Company’s common stock on November 16, 2023. To receive the new exercise price, option holders were required to be employed with the Company through November 15, 2024. Additionally, the vesting schedule for the unvested shares underlying repriced stock options held by executives at the level of senior vice president and above was extended for an additional year. There were no changes to the vesting schedules for employees below the level of senior vice president. No changes were made to the expiration dates of, or number of shares underlying the repriced stock options. Incremental stock‑based compensation expense resulting from the repricing was $8.9 million in the aggregate. Expense for vested awards was recognized through November 15, 2024 and expense for unvested awards will be recognized over the remaining service life of the option.

Performance-Based Stock Options

During the nine months ended September 30, 2025, the Company granted performance-based stock options to certain key employees. Performance-based stock options (“PBOs”) awarded to employees have athree-year performance period and vest based upon the Company’s performance against atwo- andthree-year relative total shareholder return (“rTSR”) metric or upon the achievement of certain clinical development milestones. None of the clinical development milestones were probable of achievement as of September 30, 2025. For the portion of PBOs subject to certain clinical development milestones,50% vest upon the achievement of the applicable milestone and the remaining 50% vest upon the earlier of (a)one year of service from the date of such achievement and (b) the end of thethree-year performance period. The vesting of all PBOs granted is also subject to the respective employee’s continued employment. The Company valued the portion of the PBOs subject to the rTSR metric using a Monte Carlo simulation. The number of PBOs granted subject to the rTSR metrics represents the target number of options that are eligible to be earned based on the achievement of the metrics established at the beginning of the performance period, which ends on December 31 st of thethree-year performance period. For the portion of PBOs subject to the rTSR metrics, employees may ultimately earn between zero and 200% of the target number of PBOs granted based on the degree of achievement of the applicable rTSR metric. Accordingly, additional

PBOs may be issued or currently outstanding PBOs may be cancelled upon final determination of the degree of achievement of the applicable rTSR metric. PBOs have contractual terms often years from grant date.

A summary of the Company’s PBO activity was as follows:

(1) PBO grants reflect the target number of options eligible to be earned at the time of grant.

Performance-Based Restricted Stock Units

During the year ended December 31, 2024, the Company granted PSU awards to certain key employees. PSUs awarded to employees have athree-year performance period and vest based upon the Company’s performance against atwo- andthree-year rTSR metric or upon the achievement of certain clinical development milestones. Certain of the clinical development milestones were determined to be probable of achievement as of September 30, 2025, representing 33,617 shares. For the portion of PSUs subject to certain clinical development milestones (other than the bonus clinical development milestone),50% vest upon the achievement of the applicable milestone, and the remaining 50% vest upon the earlier of (a)one year of service from the date of such achievement and (b) the end of thethree-year performance period. The vesting of all PSU awards granted is also subject to the respective employee’s continued employment. The Company valued the portion of PSUs subject to the rTSR metric using a Monte Carlo simulation. The number of PSUs granted subject to the rTSR metrics represents the target number of units that are eligible to be earned based on the achievement of the metrics established at the beginning of the performance period, which ends on December 31 st of thethree-year performance period. For the portion of PSUs subject to the rTSR metrics, employees may ultimately earn between zero and 200% of the target number of PSUs granted based on the degree of achievement of the applicable rTSR metric. Accordingly, additional PSUs may be issued or currently outstanding PSUs may be cancelled upon final determination of the degree of achievement of the applicable rTSR metric. Stock-based compensation expense recognized for the PSU awards was approximately $0.2 million andzero for the three months ended September 30, 2025 and 2024, respectively, and $0.8 million and $0.2 million for the nine months ended September 30, 2025 and 2024, respectively.

A summary of the Company’s PSU activity was as follows:

(1) PSU grants reflect the target number of shares eligible to be earned at the time of grant.

As of September 30, 2025, certain of the PSU metrics have been met, resulting in 33,623 shares vesting.

Restricted Stock Units

A summary of the Company’s RSU activity was as follows:

Stock Options

A summary of the Company’s stock option activity was as follows:

The fair value of stock options granted to employees and directors was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted-average assumptions:

The weighted-average grant date fair value of options granted for the nine months ended September 30, 2025 and 2024 were $8.93 per share and $27.00 per share, respectively.

11. Net Loss Per Share

Basic and diluted net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. The Company’s potentially dilutive shares, which include unvested RSUs, unvested PSUs and options to purchase common stock, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Shares subject to options to purchase common stock, unvested RSUs and unvested PSUs were all excluded from consideration in the calculation of diluted net loss per share in all periods presented due to their anti-dilutive effects.

12. Commitments and Contingencies

License and Collaboration Agreements

The Company has entered into certain license and collaboration agreements, including those identified in Note 4, License, Collaboration and Success Payment Agreements above, with third parties that include the funding of certain development, manufacturing and commercialization efforts with the potential for future milestone and royalty payments upon the achievement of pre-established developmental, regulatory and/or commercial milestones. The Company’s obligation to fund these efforts is contingent upon continued involvement in the programs and/or the lack of any adverse events that could cause the discontinuance of the programs, including termination of such agreements. Due to the nature of these agreements, the future potential payments are inherently uncertain, and accordingly no amounts had been recorded for the potential future achievement of these targets as of both September 30, 2025 and December 31, 2024.

13. Related-party Transactions

In September 2021, the Company entered into a sublease with Sonoma (“Sonoma Sublease”), with whom the Company has common stockholders with board seats, whereby the Company agreed to sublease approximately 18,000 square feet of space in South San Francisco, California currently leased by the Company. Dr. Klausner, the Chair of the Company’s board of directors, also serves as Board Chair of the board of directors of Sonoma. As a part of the Sonoma Sublease, a $4.6 million tenant improvement contribution payment was made by Sonoma, which is recognized over the term of the Sonoma Sublease. As of both September 30, 2025 and December 31, 2024, there were accrued liabilities and other current liabilities of $0.5 million and as of September 30, 2025 and December 31, 2024, there were other non-current liabilities of $2.2 million and $2.5 million, respectively, in connection with the Sonoma Sublease. Total operating income from Sonoma and income solely attributable to the Sonoma Sublease are shown in the table below (in thousands). Total operating income includes income attributable to the sublease, as well as additional operating fees recognized in “other operating income, net” such as common area maintenance charges. See Note 8, Leases, for more detail on the Sonoma Sublease.

In connection with the SPA, ARCH Venture XIII, L.P. participated as a Purchaser by acquiring approximately 0.9 million shares of common stock for aggregate gross proceeds to the Company of $12.5 million at a purchase price of $13.32 per share. ARCH Venture Fund XIII, L.P. filed a Form 3 in July 2025 stating it beneficially owned greater than 10% of the Company’s outstanding common stock as of that date. See Note 9, Stockholders’ Equity - Securities Purchase Agreement, for additional information regarding the SPA.

14. Segment

The Company reports segment information in accordance with the management approach, which reflects the internal reporting utilized by the Chief Operating Decision Maker (“CODM”), the Company’s President and Chief Executive Officer. Based on the information used by the CODM to allocate resources and assess the Company’s performance, the Company has determined it operates inone segment. The CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions and assessing financial performance.

The CODM evaluates the performance of the Company’s sole reportable segment based on net income or loss that also is reported on the condensed consolidated statements of operations and comprehensive loss as net income or loss. The measure of segment assets is reported on the condensed consolidated balance sheets as total assets.

Total expenditures for additions to the Company’s property and equipment, net were approximately zero for both the three months ended September 30, 2025 and 2024, respectively, and $0.3 million and $0.4 million for the nine months ended September 30, 2025 and 2024, respectively.

15. Subsequent Events

On November 6, 2025, the Company entered into an Exclusive License Agreement with Innovative Cellular Therapeutics Holdings Limited and Innovative Cellular Therapeutics, Inc. (together, “ICT”) for the development and commercialization of LYL273, a novel GCC-targeted CAR T-cell product candidate for the treatment of mCRC and other GCC-expressing cancers (the “ICT License Agreement”). Pursuant to the terms of the ICT License Agreement, the Company received exclusive global rights, outside of mainland China, Hong Kong, Macau and Taiwan, to research, develop, manufacture, commercialize and otherwise exploit LYL273 in exchange for an upfront payment of $40 million in cash and the issuance of 1.9 million shares of the Company’s common stock. In addition, ICT is eligible to receive additional cash and equity payments of (i) a potential $30 million clinical milestone payment, up to $115 million upon the achievement of certain late-stage regulatory milestones and up to $675 million in commercial sales milestones; (ii) up to an additional 1.85 million shares of the Company’s common stock based on the achievement of certain clinical and regulatory milestones; and (iii) tiered royalties ranging from mid-single-digits up to 10% on annual net sales in the United States and low to mid-single-digit royalties on annual net sales in other countries within the licensed territory.