Atara Biotherapeutics, Inc.

Description of Business

Atara Biotherapeutics, Inc. (Atara, we, our or the Company) was incorporated in August 2012 in Delaware. Atara is a leader in T-cell immunotherapy, leveraging its novel allogeneic Epstein-Barr Virus (EBV) T-cell platform to develop transformative therapies for patients with cancer and autoimmune disease.

Our most advanced T-cell immunotherapy program, tab-cel® (tabelecleucel), has received marketing authorization approval under the proprietary name Ebvallo™ by the European Commission (EC) for commercial sale and use in the European Economic Area (EEA), by the Medicines and Healthcare products Regulatory Agency (MHRA) for commercial sale and use in the United Kingdom (UK) and by Swissmedic for commercial sale and use in Switzerland. Tab-cel is currently in Phase 3 development in the US. In October 2021, we entered into a commercialization agreement (Pierre Fabre Commercialization Agreement) with Pierre Fabre Medicament (Pierre Fabre), as amended in September 2022, pursuant to which we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute Ebvallo in Europe and select emerging markets in the Middle East, Africa, Eastern Europe and Central Asia (the Initial Territory), following regulatory approval. In December 2022, we sold a portion of our right to receive royalties and certain milestones in Ebvallo under the Pierre Fabre Commercialization Agreement to HCR Molag Fund L.P. (HCRx) for a total investment amount of $31.0 million, subject to a repayment cap between 185% and 250% of the total investment amount by HCRx. See Note 6 for further information.

In October 2023, we amended and restated the Pierre Fabre Commercialization Agreement (A&R Commercialization Agreement). Pursuant to the A&R Commercialization Agreement, Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute tab-cel (Ebvallo) were expanded to include all other countries in the world (Additional Territory) in addition to the Initial Territory (Initial Territory and Additional Territory together, the Territory), subject to our performance of certain obligations. See Note 5 for further information. In March 2025, we completed the transfer of all manufacturing responsibility to Pierre Fabre and Pierre Fabre is, at its cost, responsible for manufacturing and supplying tabelecleucel for development and commercialization worldwide under an amendment to the A&R Commercialization Agreement (A&R Commercialization Agreement Amendment). Pursuant to the A&R Commercialization Agreement Amendment, Pierre Fabre also agreed to assume the future costs related to remediation of the third-party manufacturing facility to address the FDA's requests to support resubmission of the BLA for tab-cel. In exchange for accelerating the transfer of all manufacturing responsibility and assumption of such remediation costs by Pierre Fabre, among other things, we agreed to reduce the amount of certain potential future regulatory and commercial milestone payments under the A&R Commercialization Agreement. In July 2025, we further amended the A&R Commercialization Agreement and completed the transfer of all clinical (including sponsorship of the ALLELE and tab-cel multi-cohort studies) and development responsibility for tab-cel to Pierre Fabre. Pierre Fabre is, at its cost, responsible for all clinical (including sponsorship of the ALLELE and tab-cel multi-cohort studies) and development activities (other than responsibility for regulatory activities) for tabelecleucel worldwide. In October 2025, we further amended the A&R Commercialization Agreement to transfer all regulatory activities (including sponsorship of the tab-cel BLA) to Pierre Fabre. Pierre Fabre is, at its cost, responsible for all regulatory activities (including sponsorship of the tab-cel BLA) for tab-cel worldwide, and Pierre Fabre is to use commercially reasonable efforts to obtain BLA approval as soon as possible. We will, at Pierre Fabre’s expense, continue to observe the regulatory activities and support Pierre Fabre in its efforts to obtain BLA approval. We believe the tab-cel BLA is on track with a Prescription Drug User Fee Act target action date of January 10, 2026.

We have licensed rights to T-cell product candidates from Memorial Sloan Kettering Cancer Center (MSK), rights related to our next-generation CAR T programs from MSK, and rights to know-how and technology from the Council of the Queensland Institute of Medical Research (QIMR Berghofer). In May 2025, we returned the rights to the ATA188 and EBV Vaccine programs to QIMR. See Note 9 for further information.

We have executed various strategic reductions in force over the past several years. In November 2023, we announced a reduction in force that reduced our workforce at that time by approximately 30%. We recognized $6.7 million in total for severance and related benefits for employees laid off under the reduction in force. These charges are one-time termination benefits and are all cash charges.

In January 2024, we announced a reduction in workforce at that time of approximately 25%. We recognized $5.1 million in total for severance and related benefits for employees laid off under the reduction in force. The majority of the associated costs are cash expenditures and primarily one-time termination benefits.

In January 2025, we announced a reduction in force of approximately 50% of our total workforce at that time. The workforce reduction included total restructuring charges of $7.1 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In March 2025, we announced a further reduction in force of approximately 50% of our total workforce at that time. The workforce reduction included total restructuring charges of $2.7 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In May 2025, we announced a further reduction in force of approximately 30% of our total workforce at that time, retaining approximately 23 employees essential to execute our strategic priorities. The workforce reduction included total restructuring charges of $1.4 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. Refer to Note 8 for further information.

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited interim condensed consolidated financial statements include the accounts of Atara and its wholly owned subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These unaudited interim condensed consolidated financial statements should therefore be read in conjunction with the audited consolidated financial statements and notes for the year ended December 31, 2024, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 7, 2025. In the opinion of management, the condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair presentation of the Company’s condensed consolidated financial statements. The results of operations for any interim period are not necessarily indicative of the results to be expected for the full year or any other future period. The condensed consolidated balance sheet as of December 31, 2024 has been derived from audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements.

June 2024 Reverse Stock Split

At our annual meeting of stockholders held on June 10, 2024, our stockholders approved a proposal to authorize our Board of Directors (Board) to amend our Amended and Restated Certificate of Incorporation to effect a reverse stock split. The Board approved the reverse stock split on June 10, 2024 and, on June 20, 2024, we effected a 1-for-25 reverse stock split of our common stock. The par value and the authorized shares of the common stock were not adjusted as a result of the reverse stock split. All equity related information including per share amounts for all periods presented in these condensed consolidated financial statements and the notes thereto have been adjusted retroactively, where applicable, to reflect the effect of this reverse stock split.

Liquidity Risk

We have incurred significant operating losses since inception and have relied primarily on public and private equity financings and receipts from commercialization and license and collaboration agreements to fund our operations. As we continue to incur losses, our transition to profitability will depend on the successful development, approval and commercialization of product candidates and on the achievement of sufficient revenues to support our cost structure. We may never achieve sustained operating cash inflows or profitability.

Going Concern

With the exception of the first nine months of 2025, we have incurred substantial operating losses since inception, and we expect that existing cash, cash equivalents and short-term investments as of September 30, 2025, will not be sufficient to fund our planned operations for at least 12 months from the date of issuance of these condensed consolidated financial statements. Although we anticipate the receipt of certain payments from the amended and restated Pierre Fabre Commercialization Agreement, such payments are contingent upon the approval of the tab-cel BLA, as well as the completion of specific regulatory activities by us, our partner and actions taken by third parties, and are, therefore, uncertain at this time.

Inorder to alleviate the conditions that raise substantial doubt about our ability to continue as a going concern, we plan to secure additional capital, potentially through a combination of public or private security offerings; use of our ATM facility as described in Note 10; issuance of debt; and/or execution of strategic transactions. We may need to raise additional funding as required based on the status of our development programs and our projected cash flows. Even though we have been successful in raising capital in the past, and expect to continue to raise capital as required, there is no assurance that we will be successful in obtaining sufficient funding on terms acceptable to us to fund continuing operations, if at all, or identify and enter into any strategic transactions that will provide the capital that we will require. If we are unable to obtain sufficient funding on acceptable terms, we could be forced to delay, limit, reduce or terminate ongoing activities for our product candidate, which could have a material adverse effect on our business, results of operations, and financial condition. Accordingly, we have concluded that substantial doubt exists with respect to our ability to continue as a going concern for at least 12 months after the issuance of the accompanying condensed consolidated financial statements. The condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Segment and Geographic Information

We operate and manage our business asone operating and reportable segment, which is the business of developing therapeutics. Our President & Chief Executive Officer, who is our chief operating decision maker (CODM), reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. The CODM assesses performance for the business and decides how to allocate resources based on net income (loss) that also is reported on the income statement as consolidated net income (loss). The CODM uses net income (loss) to monitor expenditures and budget versus actual results. The measure of segment assets is reported on the balance sheet as total consolidated assets. The following tables represent information provided to the chief operating decision maker:

*Other segment items include Other Income (expense), net and Provision for (benefit from) income taxes

Substantially all of our assets are located in the U.S. All commercialization revenue recognized in the three and nine months ended September 30, 2025 and 2024 related to our agreements with Pierre Fabre, a French company.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates, assumptions and judgments that affect the amounts reported in the financial statements and accompanying notes. Significant estimates relied upon in preparing these financial statements include estimates related to revenue recognition, accrued research and development expenses, stock-based compensation expense, income taxes and the liability related to the sale of future revenues. Actual results could differ materially from those estimates.

Recent Accounting Pronouncements

We consider the applicability and impact of any recent Accounting Standards Update (ASU) issued by the Financial Accounting Standards Board (FASB). Other than the ASUs listed below, all other ASUs were assessed and determined to be either not applicable to Atara or are expected to have minimal impact on our condensed consolidated financial statements.

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures. This ASU enhances income tax disclosures by requiring, among other things, a tabular reconciliation of the effective tax rate with standardized categories and disclosure of percentage and dollar amounts for significant items, and annual disclosure of income taxes paid by jurisdiction, with a breakdown for significant individual jurisdictions. It also requires disaggregation of income and related tax expense by domestic and foreign components and eliminates certain existing disclosures. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. We are currently assessing the potential impact of the ASU on our disclosures.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40), which requires disclosure of additional information about specific expense categories underlying certain income statement expense line items. This ASU is effective for our annual periods beginning after December 15, 2026, and requires either prospective or retrospective application. We are currently evaluating the impact of the ASU on our disclosures.

Net Income (Loss) per Common Share

Basic net income (loss) per common share is calculated by dividing net income (loss) by the weighted-average number of shares of common stock and pre-funded warrants outstanding during the period, without consideration of common share equivalents. Diluted net income (loss) per common share is computed by dividing net income (loss) by the weighted-average number of shares of common stock, pre-funded warrants and common share equivalents outstanding for the period. The pre-funded warrants are included in the computation of basic and diluted net income (loss) per common share as the exercise price is negligible and the pre-funded warrants are fully vested and exercisable. Common share equivalents are only included in the calculation of diluted net income (loss) per common share when their effect is dilutive.

The following table is a reconciliation of the share amounts used in computing earnings per share:

Potential dilutive securities, which include unvested restricted stock units (RSUs), unvested performance-based RSUs and performance-based options to purchase common stock for which established performance criteria have been achieved as of the end of the respective periods, vested and unvested options to purchase common stock and shares to be issued under our employee stock purchase plan (ESPP), have been excluded from the computation of diluted net earnings (loss) per common share as the effect is antidilutive. Therefore, the denominator used to calculate both basic and diluted net earnings (loss) per common share is the same in all periods for which we record a net loss.

The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted net income (loss) per common share, as their inclusion would have an antidilutive effect:

Financial Instruments

Our financial assets are measured at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable U.S. GAAP:

Level 1: Quoted prices in active markets for identical assets or liabilities that we have the ability to access.

Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data such as quoted prices, interest rates and yield curves.

Level 3: Inputs that are unobservable data points that are not corroborated by market data.

We review the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels of certain securities within the fair value hierarchy. We recognize transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs. There have been no transfers between Level 1, Level 2 and Level 3 in any periods presented.

Financial assets and liabilities are considered Level 2 when their fair values are determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities. In addition, Level 2 financial instruments are valued using comparisons to like-kind financial instruments and models that use readily observable market data as their basis. U.S. Treasury, government agency and corporate debt obligations, commercial paper and asset-backed securities are valued primarily using market prices of comparable securities, bid/ask quotes, interest rate yields and prepayment spreads and are included in Level 2.

Financial assets and liabilities are considered Level 3 when their fair values are determined using pricing models, discounted cash flow methodologies, or similar techniques, and at least one significant model assumption or input is unobservable. We have no Level 3 financial assets or liabilities.

The following tables summarize the estimated fair value and related valuation input hierarchy of our available-for-sale securities as of each period end:

The amortized cost and fair value of our available-for-sale securities by contractual maturity were as follows:

We considered the current and expected future global economic and market conditions, including, but not limited to, the wars in Ukraine and the Middle East and increased tensions between the U.S. and China, and determined that our investments have not been significantly impacted. As of September 30, 2025, no significant facts or circumstances were present to indicate a deterioration in the creditworthiness of the issuers of the available-for-sale securities we hold, and we have no requirement or intention to sell these securities before maturity or recovery of their amortized cost basis. For all securities with a fair value less than its amortized cost basis, we determined the decline in fair value below amortized cost basis to be non-credit related and no allowance for losses has been recorded. During the nine months ended September 30, 2025 and 2024, we did not recognize any impairment losses on our investments.

We have elected the practical expedient to exclude the applicable accrued interest from both the fair value and the amortized cost basis of our available-for-sale securities for purposes of identifying and measuring an impairment. We present accrued interest receivable related to our available-for-sale securities in other current assets, separate from short-term investments, on our condensed consolidated balance sheet. As of September 30, 2025 and December 31, 2024, accrued interest receivable was immaterial. We havenot written off any accrued interest receivables during thenine months ended September 30, 2025 and 2024.

In addition, restricted cash collateralized by a certificate of deposit is a financial asset measured at fair value and is a Level 1 financial instrument under the fair value hierarchy.

The following table provides a reconciliation of cash, cash equivalents and restricted cash within the condensed consolidated balance sheets that sum to the total of the same such amounts in the condensed consolidated statement of cash flows:

Out-license Agreements

Pierre Fabre Agreements

In October 2021, we entered into the Pierre Fabre Commercialization Agreement, pursuant to which, we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute Ebvallo in Europe and select emerging markets in the Initial Territory following regulatory approval. In September 2022, we entered into Amendment No. 1 to the Pierre Fabre Commercialization Agreement (PF Amendment No. 1). Under the terms of PF Amendment No. 1, following European Commission approval of Ebvallo for EBV+ PTLD and subsequent filing of the Marketing Authorization Application (MAA) transfer to Pierre Fabre, we received an additional $30 million milestone payment in exchange for, among other things, a reduction in: (i) royalties we are eligible to receive as a percentage of net sales of tab-cel (Ebvallo) in the Territory, and (ii) the supply price mark up on tab-cel purchased by Pierre Fabre. Additionally, we agreed to extend the time period for provision of certain services to Pierre Fabre in the Initial Territory at our cost pursuant to the Pierre Fabre Commercialization Agreement. In December 2022, we sold a portion of our right to receive royalties and certain milestone payments related to Ebvallo in the Initial Territory under the Pierre Fabre Commercialization Agreement to HCRx for a total investment amount of $31.0 million, subject to a repayment cap between 185% and 250% of the total investment amount by HCRx. See Note 6 for further information related to the agreement with HCRx.

In October 2023, we entered into the A&R Commercialization Agreement with Pierre Fabre. Pursuant to the A&R Commercialization Agreement, Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute tab-cel were expanded to include all other countries in the world (Additional Territory) in addition to the Initial Territory (together, the Territory), subject to our performance of certain obligations as described below.

In August 2024, we sold certain intermediates used in the manufacture of Ebvallo to Pierre Fabre for $15.5 million, transferring title and risk of loss to these intermediates in advance of the Manufacturing Transition Date (as defined below), which guarantees Pierre Fabre supply and control of intermediates to be used in the production of Ebvallo. We received payment for these intermediates in September 2024.

We also entered into a separate manufacturing and supply agreement with Pierre Fabre for us to manufacture Ebvallo for Pierre Fabre to use in the Initial Territory based on a fixed price through December 31, 2023 and at a price equal to cost plus a margin for orders placed after December 31, 2023, subject to a maximum annual increase. In March 2025, we completed the transfer of all manufacturing responsibility to Pierre Fabre and Pierre Fabre is, at its cost, responsible for manufacturing and supplying tabelecleucel for development and commercialization worldwide under an amendment to the A&R Commercialization Agreement (A&R Commercialization Agreement Amendment). The A&R Commercialization Agreement Amendment defined the Manufacturing Transition Date as March 31, 2025 (the Manufacturing Transition Date). At the Manufacturing Transition Date, we sold to Pierre Fabre certain unreleased batches and intermediate inventory used in the production of tab-cel. We also sold to Pierre Fabre certain materials that support tab-cel manufacturing at no cost. Pursuant to the A&R Commercialization Agreement Amendment, Pierre Fabre has also agreed to pay certain liabilities owed to our CMOs that were incurred as of December 31, 2024. In exchange for accelerating the transfer of all manufacturing responsibility and assumption of such costs by Pierre Fabre, among other things, we agreed to reduce the amount of certain potential future regulatory and commercial milestone payments under the A&R Commercialization Agreement.

Cell selection is the process of identifying the appropriate cell line from available tab-cel inventory to be used for a patient. In February 2025, we transferred commercial cell selection in the Initial Territory and the Additional Territory to Pierre Fabre. Prior to the transfer of commercial cell selection, we were responsible for the performance of commercial cell selection services in the Initial Territory at our cost, and we were responsible for the performance of commercial cell selection services in the Additional Territory at the sole expense of Pierre Fabre. Without transfer of the cell selection technology, no other party can provide such services. In July 2025, we transferred clinical cell selection to Pierre Fabre.

Pierre Fabre paid us an upfront cash payment of $45.0 million for the exclusive license grant for the Initial Territory in the fourth quarter of 2021. In December 2022, we met the contractual right to receive $40.0 million in milestone payments upon certain regulatory milestones, for which the cash was received in January 2023. Subject to the terms of the royalty purchase agreement with HCRx, as described in Note 6, we are entitled to receive an aggregate of up to $308.0 million in remaining milestone payments upon achieving certain regulatory and commercial milestones in addition to double-digit tiered royalties as a percentage of net sales of Ebvallo in the Initial Territory, until the later of 12 years after the first commercial sale in each such country, the expiration of specified patent rights, or the expiration of all regulatory exclusivity for Ebvallo on a country-by-country basis. In December 2023, upon the effective date of the A&R Commercialization Agreement, we met the contractual right to receive an additional upfront cash payment of $20.0 million for the expanded exclusive license grant in the Additional Territory, for which the cash was received in January 2024. In March 2024, we met the contractual right to receive $20.0 million in milestone payments upon achieving a regulatory milestone, for which the cash was received in April 2024. In July 2024, we met the contractual right to receive an additional $20.0 million in milestone payments upon achieving acceptance of our biologics license application (BLA) for tab-cel by the United States Food and Drug Administration (FDA) and we received the cash in August 2024. We will also be entitled to receive an aggregate of up to $550.0 million in additional payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory, including up to $40.0 million in potential regulatory milestones in connection with the approval by the FDA of a BLA for tab-cel under the terms of the A&R Commercialization Agreement, as amended by the A&R Commercialization Agreement Amendment. We will be eligible to receive double-digit tiered royalties as a percentage of net sales of tab-cel in the Additional Territory until the later of 12 years after the first commercial sale in each such country, the expiration of specified patent rights in each such country, or the expiration of all regulatory exclusivity for tab-cel on a country-by-country basis.

As part of the Pierre Fabre Commercialization Agreement, we formed a joint steering committee (JSC) with Pierre Fabre that provides oversight, decision making and implementation guidance regarding the commercialization activities, the responsibilities of which has been expanded to cover the incremental scope of the A&R Commercialization Agreement.

During the applicable period specified in the A&R Commercialization Agreement, we are responsible for various development, safety, process science, and regulatory activities, including obtaining regulatory approval in the United States for tab-cel for EBV-associated post-transplant lymphoproliferative disease. Pierre Fabre will pay us for these services in accordance with the A&R Commercialization Agreement. Pierre Fabre is responsible, at its cost, for obtaining and maintaining all other required regulatory approvals and for commercialization and distribution of tab-cel in the Additional Territory, including conducting any other clinical study required. We will own any intellectual property rights developed solely by us under the A&R Commercialization Agreement. As described above, in March 2025, we transferred all process science services and manufacturing responsibilities to Pierre Fabre. In July 2025, we further amended the A&R Commercialization Agreement and completed the transfer of all development, clinical (including sponsorship of the ALLELE and tab-cel multi-cohort study) and safety activities for tab-cel to Pierre Fabre.

Accounting Analysis

Identification of the Contract

We assessed this arrangement in accordance with ASC 606 and concluded that the promises in the A&R Commercialization Agreement represent transactions with a customer.

Identification of the Promises and Performance Obligations

We identified five performance obligations under the A&R Commercialization Agreement, as amended by the A&R Commercialization Agreement Amendment, consisting of the following material promises:

(1)

the transfer of intellectual property rights in the form of a license in the Initial Territory, the obligation to participate in the JSC, the manufacture and supply of Ebvallo, a material right for purchases associated with the manufacture and supply of Ebvallo, and the performance of cell-selection services. We concluded that the individual promises are not distinct because Pierre Fabre cannot benefit from the license without the other services and vice versa, since Pierre Fabre is not capable of carrying out the manufacturing and supply and cell selection services on their own, until the transfer of the related technologies occur. Consequently, these promises represent a single performance obligation, collectively referred to as the Initial Territory Obligation.

(2)

the transfer of intellectual property rights in the form of a license in the Additional Territory, the manufacture and supply of tab-cel and the performance of cell-selection services, as well as the promises to transfer the related technologies, and perform certain development, safety, regulatory and information technology transition services. We concluded that the promises are not distinct because Pierre Fabre cannot benefit from the license without the other services and vice versa. Consequently, these promises represent a single performance obligation, collectively referred to as the Additional Territory Obligation.

(3)

performance of certain process science services, referred to as the Process Sciences Obligation.

(4)

the sale of certain intermediate inventory used in the production of tab-cel in existence on the Manufacturing Transition Date, referred to as the Intermediate Inventory Obligation; and

(5)

the sale of certain materials to support the production of tab-cel in existence on the Manufacturing Transition Date, referred to as the Manufacturing Materials Obligation.

Determination of the Transaction Price

Under the Pierre Fabre Commercialization Agreement, we determined that the $45.0 million upfront payment constituted the entire consideration to be included in the transaction price at the outset of the arrangement, and the $40.0 million in regulatory milestones achieved in December 2022 were added to the transaction price upon meeting the related milestone criteria. The remaining potential regulatory and commercial milestone payments that we are eligible to receive were excluded from the transaction price, as the milestone amounts were fully constrained based on the probability of achievement or have not been earned. None of the future royalty and sales-based milestone payments were included in the transaction price, as the potential payments represent sales-based consideration.

Upon the effective date of the A&R Commercialization Agreement, the $20.0 million additional upfront payment received and estimated revenue for the development, safety, regulatory and process science services were added to the transaction price, and the $20.0 million regulatory milestone achieved in March 2024 and the $20.0 million regulatory milestone achieved in July 2024 were added to the transaction price upon meeting the related milestone criteria. The remaining potential regulatory and commercial milestone payments that we are eligible to receive were excluded from the transaction price, as the milestone amounts were fully constrained based on the probability of achievement or have not been earned. None of the future royalty and sales-based milestone payments were included in the transaction price, as the potential payments represent sales-based consideration. Upon the effective date of the A&R Commercialization Agreement Amendment, the liabilities owed to the CMOs that were relieved by Pierre Fabre were added to the transaction price.

We reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, as necessary, we adjust our estimate of the transaction price.

Allocation of the Transaction Price to Performance Obligations

The transaction price was allocated to each performance obligation based on their relative standalone selling price. We developed the estimated standalone selling price for each of the A&R Commercialization Agreement performance obligations with the objective of determining the price at which we would sell such an item if it were to be sold regularly on a standalone basis.

Recognition of Revenue

Commercialization revenue associated with the Initial Territory Obligation was recognized over the period during which the material right existed, which ended on March 31, 2025, the Manufacturing Transition Date. Commercialization revenue associated with sales of Ebvallo and intermediate inventory to Pierre Fabre was deferred until we performed the associated manufacturing of finished Ebvallo product inventory and cell selection services, or until the transfer of manufacturing and cell selection technology to Pierre Fabre. All revenue associated with the Initial Territory Obligation was recognized as of March 31, 2025. As of March 31, 2025, Pierre Fabre is able to utilize the inventory it had purchased from us on its own.

Commercialization revenue associated with the Additional Territory Obligation and the Process Sciences Obligation is recognized using a cost-based input method based on the amount of actual costs incurred relative to the total budgeted costs expected to be incurred for the respective performance obligations. A cost-based input method of revenue recognition requires us to make estimates of costs to complete our performance obligation. In making such estimates, significant judgment is required to evaluate assumptions related to cost estimates. The cumulative effect of revisions to estimated costs to complete our performance obligation will be recorded in the period in which changes are identified and amounts can be reasonably estimated. The Process Services Obligation was completed on the Manufacturing Transition Date. All revenue associated with the Process Sciences Obligation was recognized as of March 31, 2025. As of September 30, 2025, there is approximately $1 million of deferred revenue remaining associated with the Additional Territory Obligation to be recognized upon completion of certain regulatory obligations. The transfer of control occurs over the respective time period and, in our judgment, is the best measure of progress towards satisfying the performance obligation. A significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods. We recognized all revenue associated with the Intermediate Inventory Obligation and the Manufacturing Materials Obligation at a point in time, upon the Manufacturing Transition Date, which is when title and risk of loss, and thus, control, of the intermediate inventory and materials transferred to Pierre Fabre.

Deferred revenue activity related to commercialization revenue for thenine months ended September 30, 2025 was as follows:

During the nine months ended September 30, 2025, we recognized $91.1 million of revenue that was included in the deferred revenue balance as of December 31, 2024.

Costs incurred relating to performing the services within the Additional Territory Obligation and Process Sciences Obligation consist of third party expenses and time incurred by our employees to satisfy requirements set forth by the A&R Commercialization Agreement. These costs are included in research and development expenses in the condensed consolidated statements of operations and comprehensive income (loss). Such costs were $0.9 million and $12.0 million for the three andnine months ended September 30, 2025, respectively, and such costs were $11.1 million and $33.8 million for the three andnine months ended September 30, 2024, respectively.

Liability Related to the Sale of Future Revenues

In December 2022, we entered into a Purchase and Sale Agreement (HCRx Agreement) with HCR Molag Fund, L.P., a Delaware limited partnership, (HCRx). In exchange for a payment of $31.0 million (Investment Amount) to Atara, net of certain transaction expenses, HCRx obtained the right to receive certain Ebvallo royalties and milestone payments payable by Pierre Fabre under the Pierre Fabre Commercialization Agreement up to an agreed upon multiple of the Investment Amount.

Under the HCRx Agreement, HCRx is entitled to receive tiered royalties on net sales of Ebvallo in the Initial Territory in amounts ranging from the mid-single digits to double digits based on annual net sales. HCRx is also entitled to certain milestone payments due to Atara from Pierre Fabre. The total royalties and milestones payable to HCRx are capped between 185% and 250% of the Investment Amount, depending upon the timing of such royalties and milestones. Upon meeting the cap amount, HCRx’s right to receive royalties and milestone payments will terminate and all rights will revert to Atara. To the extent a certain milestone within the Pierre Fabre Commercialization Agreement is not achieved on or prior to June 30, 2026, we will be required to make a one-time cash payment in the amount of $9.0 million to HCRx, and HCRx shall transfer all of its right, title and interest in this certain $9.0 million milestone payment to Atara. This payment, if required, would be included in the calculation of aggregate payments made to HCRx.

The gross proceeds of the Investment Amount of $31.0 million were recorded as a liability related to the sale of future revenues, net of transaction costs of $0.4 million, and is amortized using the effective interest method over the life of the arrangement.

To determine the amortization of the recorded liability, we are required to estimate the total amount of future payments to be received by HCRx. The sum of these amounts less the $31.0 million proceeds we received will be recorded as interest expense over the life of the HCRx Agreement. We estimate the effective interest rate used to record non-cash interest expense under the HCRx Agreement based on the estimate of future royalty payments to be received by HCRx. On September 30, 2025, the annual effective interest rate was approximately 9%. Over the life of the arrangement, the actual effective interest rate will be affected by the amount and timing of the actual and forecasted royalty and milestone payments to HCRx. At each reporting date, we will reassess our estimate of the timing and amounts of future payments made to HCRx, and prospectively adjust the effective interest rate and amortization of the liability as necessary.

The following table presents the changes in the liability related to the sale of future revenues under the HCRx Agreement for thenine months ended September 30, 2025:

Leases

In November 2018, we entered into a lease agreement for office space in Thousand Oaks, California, that expires in February 2026 and for which we have the option to extend the lease for an additional period of five years after the initial term. In February 2025, we vacated this office space prior to the termination of the lease, resulting in the right-of-use asset to be abandoned. When a lease right-of-use asset has been abandoned, the estimated useful life of the asset is updated to reflect the cease use date, and the remaining carrying value of the asset is amortized ratably over the period between the commitment date and the cease use date. In February 2025, with the abandonment of the lease, we recognized an acceleration of amortization expense on the abandoned right-of-use asset in the amount of $1.0 million within general and administrative expenses on the accompanying condensed consolidated statements of operations and comprehensive income (loss) for the nine months ended September 30, 2025. The lease liability for the Thousand Oaks office remains on our balance sheet.

In March 2021, we entered into a lease agreement for the 33,659 square feet of office, lab and warehouse space at the Atara Research Center (ARC). During the third quarter of 2021, the initial 10.5-year lease term commenced, upon substantial completion of the landlord’s work as defined under the agreement. Base rent is subject to annual increases of 3% with each annual anniversary of the rent commencement date. We have the option to extend this lease for two additional five-year periods after the initial term. In March 2025, we announced a pause on our CAR-T research and development activities. As a result, we are winding down activities at the ARC lab and actively seeking to sublease the facility. We considered this to be a triggering event and performed an impairment analysis on the right-of-use asset. For thenine months ended September 30, 2025, we recorded a non-cash impairment of the right-of-use asset of $4.1 million, representing the amount by which the carrying value of the right-of-use asset exceeded its estimated fair value. We recorded the impairment loss within research and development expenses on the accompanying condensed consolidated statements of operations and comprehensive income (loss). The remaining ROU asset and lease liability for the ARC facility remain on our balance sheet.

In February 2017, we entered into a lease agreement (the ATOM Lease) for approximately 90,580 square feet of office, lab and cellular therapy manufacturing space in Thousand Oaks, California (the ATOM Facility). The initial 15-year term of the headlease commenced on February 15, 2018, upon the substantial completion of landlord’s work as defined under the agreement. In April 2022, we assigned the ATOM Lease to FDB in connection with the closing of the sale of the ATOM Facility to FDB. Under ASC 842, we are considered to be the sub-lessor of the ATOM Lease. We have not received novation from the landlord and therefore have not been relieved of our primary obligations under the headlease. Therefore, the ROU asset and lease liability for the ATOM Facility remain on our balance sheet. Given the continued use of the ATOM lease by another party, we did not consider there to be a trigger for valuation considerations following our restructuring activities.

We evaluated our vendor contracts to identify embedded leases and determined that the Master Services and Supply Agreement (Fujifilm MSA) we entered into with FUJIFILM Diosynth Biotechnologies California, Inc. (FDB) contained items that constituted a lease under ASC 842, Leases, as Atara has the right to substantially all of the economic benefits from the use of the asset and can direct the use of the asset. We concluded that the Fujifilm MSA contains an embedded operating lease for certain dedicated processing rooms for the manufacturing of Atara product and an embedded finance lease for certain freezers dedicated for our use. The Fujifilm MSA includes contractual obligations in the form of payments for the processing rooms and the freezers, each over a term of five years. As a result, we added ROU assets and lease liabilities for the processing rooms and freezers for the initial term of the lease in the amounts of $50.8 million and $4.8 million, respectively. In November 2023, we agreed to forego the use of one processing room for approximately one year in return for a reduction in contractual obligations under the Fujifilm MSA, and in November 2024, we exercised the option to release the processing room to FDB for the remainder of the initial term. The Fujifilm MSA was novated to Pierre Fabre in March 2025 as part of the A&R Commercialization Agreement Amendment. As of June 30, 2025, we were relieved of our primary obligations under the Fujifilm MSA. Therefore, the ROU assets and lease liabilities for the processing rooms and the freezers have been removed from our condensed consolidated balance sheet as of June 30, 2025. At the time of this release in June 2025, we recognized a gain on derecognition of the operating lease liability of $0.7 million and a gain on derecognition of the finance lease liability of $0.5 million within research and development expenses on the accompanying condensed consolidated statements of operations and comprehensive income (loss).

Additionally, in 2021, we entered into an amended lease agreement (Aurora Lease) for our office and lab space in Aurora, Colorado, to add additional lab space and in November 2023, we further amended the Aurora Lease to extend the term to April 2025. The lease agreement expired on April 30, 2025, and the ROU asset and lease liability for the Aurora Lease are no longer on our balance sheet.

We originally leased office space in South San Francisco, California under a non-cancellable lease agreement. In December 2021, we entered into a second amendment with the landlord to extend the lease term through May 2025. The amended lease agreement does not include an option to extend the lease term. In connection with the amended lease, we were required to maintain a letter of credit in the amount of $0.1 million to the landlord. In October 2022, we entered into a sub-lease agreement with a third party for this office space. The sub-lease term commenced in November 2022 and expired in May 2025. At the expiration of the lease in May 2025 our ROU asset and lease liability for the South San Francisco office were removed from our balance sheet and the requirement to maintain a letter of credit was released.

We have no finance leases as of September 30, 2025. The maturities of lease liabilities under our operating leases as of September 30, 2025 were as follows:

The components of lease cost were as follows:

Other information related to leases was as follows:

Restructuring

We have executed various strategic reductions in force over the past several years. In November 2023, we announced a reduction in workforce of approximately 30%. The workforce reduction included total restructuring charges of $6.7 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California Worker Adjustment and Retraining Notification (WARN) Act. In most cases, the severance payments were paid as a lump sum in January 2024. As of September 30, 2025, there are no remaining payments for the November 2023 reduction in workforce. All of the costs were cash expenditures and represent one-time termination benefits.

In January 2024, we announced a reduction in force of approximately 25% of total workforce at that time. The workforce reduction resulted in total restructuring charges of $5.1 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the severance payments were paid during the first half of 2024. Certain of the notified employees had employment agreements that provided for separation benefits in the form of salary continuation, which were paid from February 2024 through January 2025. As of September 30, 2025, there are no remaining payments for the January 2024 reduction in workforce. The majority of the associated costs were cash expenditures and primarily represent one-time termination benefits.

In January 2025, we announced a reduction in force of approximately 50% of total workforce at that time. The workforce reduction included total restructuring charges of $7.1 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the severance payments were paid during the second quarter of 2025. Certain of the notified employees had employment agreements which provided for separation benefits in the form of salary continuation; these benefits will be paid from April 2025 to May 2026. As of September 30, 2025, approxim ately $1.0 million of further separation payments and benefits are required for the January 2025 reduction in workforce. The majority of the associated costs are cash expenditures and primarily represent one-time termination benefits.

In March 2025, we announced a further reduction in force of approximately 50% of total workforce at that time, retaining approximately 35 employees essential to execute on our strategic priorities. The workforce reduction included total restructuring charges of $2.7 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the severance payments were paid in the second quarter of 2025. Certain of the notified employees had employment agreements which provided for separation benefits in the form of salary continuation; these benefits will be paid from May 2025 to May 2026. As of September 30, 2025, approximately$0.2 million of further separation payments and benefits are required for the March 2025 reduction in workforce. The majority of the associated costs are cash expenditures and primarily represent one-time termination benefits.

In May 2025, we announced a further reduction in force of approximately 30% of total workforce at that time, retaining approximately 23 employees essential to execute on our strategic priorities. The workforce reduction included total restructuring charges of $1.4 million, comprised primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. The severance will be paid in second half of 2025. As of September 30, 2025, approximately $17,000 of further separation payments and benefits are required for the May 2025 reduction in workforce. The majority of the associated costs are cash expenditures and primarily represent one-time termination benefits.

The following is a summary of restructuring charges associated with the reductions in force for the periods presented:

We also incurred lease and property, plant and equipment charges as a result of the 2025 restructuring activities. For the nine months ended September 30, 2025, we recognized an acceleration of amortization expense on an abandoned right-of-use asset in the amount of $1.0 million within general and administrative expenses on the accompanying condensed consolidated statements of operations and comprehensive income (loss). For the nine months ended September 30, 2025, we also recorded a non-cash impairment of a lease right-of-use asset of $4.1 million, representing the amount by which the carrying value of the right-of-use asset exceeded its estimated fair value. We recorded the impairment loss within research and development expenses on the accompanying condensed consolidated statements of operations and comprehensive income (loss). Refer to Note 7 for further details. Further, for the nine months ended September 30, 2025, we recognized$0.1 million in loss on disposal of property, plant and equipment associated with the restructuring activities recorded in general and administrative expenses on the accompanying condensed consolidated statements of operations and comprehensive income (loss).

The following restructuring liability activity was recorded in connection with the reductions in force for thenine months ended September 30, 2025:

The liability balance as of September 30, 2025 and December 31, 2024 is recorded within other current liabilities on the accompanying condensed consolidated balance sheet.

Commitments and Contingencies

MSK In-License Agreements

In June 2015, we entered into an exclusive license agreement with MSK for three clinical stage T-cell therapies. We are required to make payments to MSK based on achievement of specified regulatory and sales-related milestones, as well as mid-single-digit percentage tiered royalty payments based on future sales of products resulting from the development of the licensed product candidates, if any. In addition, under certain circumstances, we are required to make certain minimum annual royalty payments to MSK, which are creditable against earned royalties owed for the same annual period. We are also required to pay a low double-digit percentage of any consideration we receive for sublicensing the licensed rights, subject to certain conditions. The license agreement expires on a product-by-product and country-by-country basis on the latest of: (i) expiration of the last licensed patent rights related to each licensed product, (ii) expiration of any market exclusivity period granted by law with respect to each licensed product, and (iii) a specified number of years after the first commercial sale of the licensed product in each country. Upon expiration of the license agreement, we will retain non-exclusive rights to the licensed products.

In May and December 2018, we licensed additional technology from MSK. We are obligated to make additional milestone payments based on achievement of specified development, regulatory and sales-related milestones as well as mid-single-digit percentage tiered royalty payments based on future sales of products resulting from the development of the licensed product candidates, if any.

In March 2021, we amended and restated our license agreement with MSK to terminate our license to certain rights and license additional know-how rights not otherwise covered by our existing agreements.

In March 2024, we terminated our license agreements with MSK to the ATA2271 and ATA3271 programs targeting mesothelin.

During the third quarter of 2024, MSK sent us a notice alleging that under the terms of our license agreements with MSK, MSK is entitled to $6.0 million of sub-licensing fees as a result of the $60.0 million we received from Pierre Fabre related to the Additional Territory upfront and milestone payments in 2024 pursuant to the A&R Commercialization Agreement. We paid the $6.0 million to MSK under protest in the third quarter of 2024 in order to proceed with the dispute process per the terms of the license agreements. We recorded this cost in research and development expenses on the consolidated statements of operations and comprehensive income (loss) during the year ended December 31, 2024.

In March 2025, we resolved and settled our dispute with MSK regarding sub-licensing fees related to the Additional Territory and milestone payments pursuant to the A&R Commercialization Agreement. Under the terms of the settlement, MSK returned $3.0 million of the $6.0 million paid under protest and we agreed to make future additional sub-licensing fee payments based on amounts we receive from Pierre Fabre pursuant to the A&R Commercialization Agreement based on achievement of specified development, regulatory and sales-related milestones, when and if such milestones are achieved.

QIMR Berghofer In-License Agreements

In October 2015, we entered into an exclusive license agreement and a research and development collaboration agreement with QIMR Berghofer. Under the terms of the license agreement, we obtained an exclusive, worldwide license to develop and commercialize allogeneic T-cell therapy programs utilizing technology and know-how developed by QIMR Berghofer. In September 2016, the exclusive license agreement and research and development collaboration agreement were amended and restated. Under the amended and restated agreements, we obtained an exclusive, worldwide license to develop and commercialize additional T-cell programs, as well as the option to license additional technology that we exercised in June 2018. We further amended and restated our license agreement and research and development collaboration agreements with QIMR Berghofer in August 2019, August 2020 and December 2021, in each case, to terminate our license to certain rights. Our current license agreement also provides for various milestone and royalty payments to QIMR Berghofer based on future product sales, if any. Under the terms of our current research and development collaboration agreement, we are also required to reimburse the cost of agreed-upon development activities related to programs developed under the collaboration. These payments are expensed on a straight-line basis over the related development periods. The agreement also provides for various milestone payments to QIMR Berghofer based on achievement of certain developmental and regulatory milestones. In May 2025, we returned the rights to the ATA188 and EBV Vaccine programs to QIMR.

Other In-License and Collaboration Agreements

From time to time, we have entered into other license and collaboration agreements with other parties. For example, we licensed rights related to our MSK-partnered next-generation CAR T programs from the National Institutes of Health in December 2018.

Milestones and royalties under each of the above agreements are contingent upon future events and will be recorded as expense when the underlying milestones are achieved or royalties are earned. Sales related milestone and royalty costs related to Ebvallo are recorded in cost of commercialization revenue, whereas regulatory milestone costs are recorded in research and development expense. As of September 30, 2025 and December 31, 2024, there wereno material outstanding obligations for milestones and royalties under our in-license and collaboration agreements.

CRL Manufacturing Agreement

In December 2019, we entered into a Commercial Manufacturing Services Agreement (the CRL MSA) with Cognate BioServices, Inc., which was acquired by Charles River Laboratories Inc. (CRL) in March 2021. The CRL MSA expired on August 31, 2024 and we have transitioned manufacturing responsibility for tab-cel to Pierre Fabre.

Fujifilm Master Services and Supply Agreement

In January 2022, we entered into the Fujifilm MSA, which became effective upon the closing of the sale of the ATOM Facility on April 4, 2022 and could extend for up toten years. Pursuant to the Fujifilm MSA, FDB will supply us with specified quantities of our cell therapy products and product candidates, manufactured in accordance with current Good Manufacturing Practices (cGMP) standards. In March 2025, in connection with the transition of manufacturing responsibility for tab-cel to Pierre Fabre, we assigned the Fujifilm MSA to Pierre Fabre. As of September 30, 2025, we have been relieved of our obligations under the Fujifilm MSA.

Other Research, Development and Manufacturing Agreements

We may enter into other contracts in the normal course of business with clinical research organizations for clinical trials, with CMOs for product, product candidates and clinical supplies, and with other vendors for preclinical studies, supplies and other services for our operating purposes. These contracts generally provide for termination on notice. As of September 30, 2025 and December 31, 2024, there wereno material amounts accrued related to contract termination charges.

Minimum Commitments

We had certain non-cancellable minimum commitments for products and services, subject to agreements with a term of greater than one year with clinical research organizations and CMOs. In March 2025, we assigned these agreements to Pierre Fabre in conjunction with the Pierre Fabre Amendment and have been relieved of our obligations under these agreements. As a result of our relief from such obligations, we did not incur any additional charges against the minimum commitments for the three months ended September 30, 2025. For the nine months ended September 30, 2025, we incurred $0.5 million against the minimum commitments.

For the comparative periods presented, we incurred $3.0 million and $9.7 million against the minimum commitments for the three andnine months ended September 30, 2024, respectively. As of December 31, 2024, we accrued $5.3 million in research and development expenses related to minimum purchase commitments.

Indemnification Agreements

In the normal course of business, we enter into contracts and agreements that contain a variety of representations and warranties and provide for indemnification for certain liabilities. The exposure under these agreements is unknown because it involves claims that may be made against us in the future but have not yet been made. To date, we have not paid any claims or been required to defend any action related to our indemnification obligations. However, we may record charges in the future as a result of these indemnification obligations. We also have indemnification obligations to our directors and executive officers for specified events or occurrences, subject to some limits, while they are serving at our request in such capacities. There have been no claims to date, and we consider the fair value of these indemnification agreements to be minimal. Accordingly, we didnot record liabilities for these agreements as of September 30, 2025 and December 31, 2024.

Contingencies

From time to time, we may be involved in legal proceedings, as well as demands, claims and threatened litigation, which arise in the normal course of our business or otherwise. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on our results of operations and financial condition. Regardless of outcome, litigation can have an adverse impact on us because of the defense costs, diversion of management resources and other factors. We are not currently involved in any material legal proceedings.

Stockholders’ Equity (Deficit)

Our authorized capital stock consists of 520,000,000 shares, all with a par value of $0.0001 per share, of which 500,000,000 shares are designated as common stock and 20,000,000 shares are designated as preferred stock. There wereno shares of preferred stock outstanding as of September 30, 2025 and December 31, 2024.

Equity Offerings

As part of our July 2019 underwritten public offering, we issued and sold pre-funded warrants to purchase 117,801 shares of common stock in an underwritten public offering pursuant to a shelf registration on Form S-3.

Each pre-funded warrant entitles the holder to purchaseone share of common stock at an exercise price of $0.0025 per share and expires seven years from the date of issuance. These warrants were recorded as a component of stockholders’ equity (deficit) within additional paid-in capital. Per the terms of the warrant agreement, a holder of the outstanding warrants is not entitled to exercise any portion of any pre-funded warrant if, upon exercise of the warrant, the holder’s ownership (together with its affiliates) of our common stock or combined voting power of our securities beneficially owned by such holder (together with its affiliates) would exceed 9.99% after giving effect to the exercise (2019 Warrant Maximum Ownership Percentage). Upon at least 61 days’ prior notice to us by the holder, any holder may increase or decrease the 2019 Warrant Maximum Ownership Percentage to any other percentage not to exceed 19.99%. No July 2019 pre-funded warrants were exercised during thenine months ended September 30, 2025, and as of September 30, 2025, pre-funded warrants to purchase 101,089 shares of our common stock from the July 2019 underwritten public offering were outstanding.

As part of the May 2020 underwritten public offering, we issued and sold pre-funded warrants to purchase 114,678 shares of common stock in an underwritten public offering pursuant to a shelf registration on Form S-3. Additionally, as part of the December 2020 underwritten public offering, we issued and sold pre-funded warrants to purchase 81,632 shares of common stock in an underwritten public offering pursuant to a shelf registration on Form S-3. These warrants were recorded as a component of stockholders' equity (deficit) within additional paid-in capital.

The terms of the pre-funded warrants issued and sold as part of the 2020 public offerings were similar to those issued and sold in 2019. No May 2020 or December 2020 pre-funded warrants were exercised during the nine months ended September 30, 2025. As of September 30, 2025,38,735 and 55,387 of the pre-funded warrants to purchase shares of our common stock issued and sold as part of the May 2020 and December 2020 underwritten public offerings, respectively, were outstanding.

In January 2024, we issued and sold pre-funded warrants to purchase 1,090,907 shares of common stock at a price of $13.7475 per warrant in a registered direct offering pursuant to a shelf registration on Form S-3. The gross proceeds from this sale were $15.0 million, resulting in net proceeds of $14.8 million after deducting offering expenses payable by us.

Each of the January 2024 pre-funded warrants issued entitles the holder to purchaseone share of common stock at an exercise price of $0.0025 per share, with no expiration date. These warrants were recorded as a component of stockholders’ equity (deficit) within additional paid-in capital. Per the terms of the warrant agreement, a holder of the outstanding warrants is not entitled to exercise any portion of any pre-funded warrant if, upon exercise of the warrant, the holder’s ownership (together with its affiliates) of our common stock or combined voting power of our securities beneficially owned by such holder (together with its affiliates) would exceed 9.99% after giving effect to the exercise (January 2024 Maximum Ownership Percentage). Upon at least 61 days’ prior notice to us by the holder, any holder may increase or decrease the January 2024 Maximum Ownership Percentage to any other percentage not to exceed 19.99%. No January 2024 pre-funded warrants were exercised during thenine months ended September 30, 2025 and all 1,090,907 of the January 2024 pre-funded warrants remain outstanding as of September 30, 2025.

In September 2024, we issued and sold 758,900 shares of common stock at an offering price of $8.25 per share and pre-funded warrants to purchase 3,604,780 shares of common stock at an offering price of $8.2499 per warrant in a registered direct offering pursuant to a shelf registration on Form S-3. The gross proceeds from this sale were $36.0 million, resulting in net proceeds of $35.8 million after deducting offering expenses payable by us.

Each of the September 2024 pre-funded warrants issued entitles the holder to purchaseone share of common stock at an exercise price of $0.0001 per share, with no expiration date. These warrants were recorded as a component of stockholders’ equity (deficit) within additional paid-in capital. Per the terms of the warrant agreement, a holder of the outstanding warrants is not entitled to exercise any portion of any pre-funded warrant if, upon exercise of the warrant, the holder’s ownership (together with its affiliates) of our common stock or combined voting power of our securities beneficially owned by such holder (together with its affiliates) would exceed, at the holder's election,4.99%,9.99% or 19.99% after giving effect to the exercise (the September 2024 Warrant Maximum Ownership Percentage). Upon at least 61 days’ prior notice to us by the holder, any holder may increase or decrease the September 2024 Warrant Maximum Ownership Percentage to any other percentage not to exceed 19.99%. No September 2024 pre-funded warrants were exercised during thenine months ended September 30, 2025 and as of September 30, 2025, pre-funded warrants to purchase 3,596,146 shares of our common stock from the September 2024 direct offering were outstanding.

In May 2025, we issued and sold 834,237 shares of common stock at an offering price of $6.61 per share and pre-funded warrants to purchase 1,587,108 shares of common stock at an offering price of $6.6099 per warrant in an underwritten registered direct offering pursuant to a shelf registration on Form S-3. The gross proceeds from this sale were $16.0 million, resulting in net proceeds of $14.8 million after deducting underwriting discounts and commissions and offering expenses payable by us.

Each of the May 2025 pre-funded warrants issued entitles the holder to purchaseone share of common stock at an exercise price of $0.0001 per share, with no expiration date. These warrants are recorded as a component of stockholders’ equity (deficit) within additional paid-in capital. Per the terms of the warrant, a holder of the outstanding warrants is not entitled to exercise any portion of any pre-funded warrant if, upon exercise of the warrant, the holder’s ownership (together with its affiliates) of our common stock or combined voting power of our securities beneficially owned by such holder (together with its affiliates) would exceed, at the holder's election,4.99%,9.99% or 19.99% after giving effect to the exercise (the May 2025 Warrant Maximum Ownership Percentage). Upon at least 61 days’ prior notice to us by the holder, any holder may increase or decrease the May 2025 Warrant Maximum Ownership Percentage to any other percentage not to exceed 19.99%. No May 2025 pre-funded warrants were exercised during thenine months ended September 30, 2025, and as of September 30, 2025, pre-funded warrants to purchase 1,587,108 shares of our common stock from the May 2025 underwritten registered direct offering were outstanding.

ATM Facilities

In the past three years, we have entered into two separate sales agreements with Cowen and Company, LLC (Cowen): in November 2021 (2021 ATM Facility) and in November 2023 (2023 ATM Facility). Each ATM facility provides or provided for the sale, in our sole discretion, of shares of our common stock having an aggregate offering price of up to $100.0 million, through Cowen, as our sales agent. We filed a registration statement on Form S-3 registering the offer and sale of these shares under the Securities Act (2023 Registration Statement). Upon the effectiveness of the 2023 Registration Statement, the 2021 ATM Facility was terminated, and no further sales can be made under the 2021 ATM Facility. The issuance and sale of these shares by us pursuant to the ATM facilities are deemed “at the market” offerings defined in Rule 415 under the Securities Act of 1933, as amended (Securities Act), and were registered under the Securities Act. Commissions of up to 3.0% are due on the gross sales proceeds of the common stock sold under each ATM facility.

During the nine months ended September 30, 2024, we sold an aggregate of 492,855 shares of common stock under the 2023 ATM Facility, at an average price of $19.23 per share, for gross proceeds of $9.5 million and net proceeds of $9.3 million, after deducting commissions and other offering expenses payable by us.

During the nine months ended September 30, 2025,124,434 shares of common stock were sold under the 2023 ATM Facility, for gross proceeds of $1,519,004 and net proceeds of $1,471,180 after deducting commissions and other offering expenses payable by us.

As of September 30, 2025, we had$87.2 million of common stock remaining and available to be sold under the 2023 ATM Facility.

Equity Incentive Plans

In June 2024, we adopted the 2024 Equity Incentive Plan (2024 EIP), under which we may grant stock options, restricted stock awards (RSAs) and RSUs to employees, directors, consultants and other service providers. RSUs generally vest over two to four years. The 2014 Equity Incentive Plan, as amended (2014 EIP), expired March 31, 2024, after which no new awards can be granted from it. All awards granted prior to the 2014 EIP expiration continue to remain outstanding and governed in accordance with the rules set forth in the 2014 EIP and the terms of the associated grant notice. To the extent forfeited, cancelled or expired, certain awards granted under the 2014 EIP will become available for grant under the 2024 EIP.

RSUs generally vest over two tofour years. We have granted performance-based RSUs to certain of our employees that provide for the issuance of common stock if specified Company performance criteria related to tab-cel regulatory milestones are achieved. The number of performance-based RSUs that ultimately vests depends upon if and which performance criteria are achieved, as well as the employee’s continuous service, as defined in the 2014 EIP and 2024 EIP, through the date of vesting. The fair value of performance-based RSUs is determined as the closing stock price on the date of grant.

Stock options are granted at prices no less than 100% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided, however, thatthe exercise price of an option granted to a 10% shareholder cannot be less than 110% of the estimated fair value of the shares on the date of grant. Options granted generally vest over three tofour years and expire inseven toten years. Wehave granted performance-based stock options to certain of our employees that provide for the issuance of a right to purchase a share of common stock if specified Company performance criteria related to tab-cel regulatory milestones are achieved. The vesting of performance-based stock options depends upon if and when the performance criteria are achieved, as well as the employee’s continuous service as defined in the 2014 EIP and 2024 EIP, through the date of vesting.

As of September 30, 2025, a total of 170,854 shares of common stock were reserved for issuance under the 2014 EIP, of which all were subject to outstanding options and RSUs, including performance-based awards.

As of September 30, 2025, a total of 402,977 shares of common stock were reserved for issuance under the 2024 EIP, of which 157,825 shares were available for future grant and 245,152 shares were subject to outstanding options and RSUs.

In February 2018, we adopted the 2018 Inducement Plan (Inducement Plan), under which we may grant options, stock appreciation rights, RSAs and RSUs to new employees. In November 2020, September 2021 and June 2022 we amended the Inducement Plan to reserve an additional 60,000 shares of the Company’s common stock for issuance under the Inducement Plan in each case.

As of September 30, 2025,150,248 shares of common stock were reserved for issuance under the Inducement Plan, of which 141,184 shares were available for future grant and 9,064 shares were subject to outstanding options and RSUs.

In May 2014, we adopted the 2014 Employee Stock Purchase Plan (2014 ESPP), which permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. Following stockholder approval, in June 2024, we amended the 2014 ESPP to increase the number of shares of our common stock available for issuance under the 2014 ESPP by 40,000 shares.

Restricted Stock Units

The following is a summary of RSU activity under our 2014 EIP, 2024 EIP and Inducement Plan:

As of September 30, 2025, there was$2.7 million of unrecognized stock-based compensation expense related to RSUs that is expected to be recognized over a weighted average period of 1.4 years. This excludes unrecognized stock-based compensation expense for performance-based RSUs that were deemed not probable of vesting in accordance with U.S. GAAP.

Stock Options

The following is a summary of stock option activity under our 2014 EIP, 2024 EIP and Inducement Plan:

Aggregate intrinsic value represents the difference between the closing stock price of our common stock on September 30, 2025 and the exercise price of outstanding, in-the-money options. As of September 30, 2025, there was$0.4 million of unrecognized stock-based compensation expense related to stock options that is expected to be recognized over a weighted average period of 0.4 years. This excludes unrecognized stock-based compensation expense for performance-based stock options that were deemed not probable of vesting in accordance with U.S. GAAP.

Reserved Shares

The following shares of common stock were reserved for future issuance under our equity incentive plans as of September 30, 2025:

Stock-based Compensation Expense

The following is a summary of stock-based compensation expense for the periods presented:

Supplemental Balance Sheet Information

Inventories

Inventories consisted of the following as of each period end:

Property and equipment, net

Property and equipment consisted of the following as of each period end:

For the three months ended September 30, 2025, depreciation expense was immaterial. Depreciation expense was $0.6 million for the three months ended September 30, 2024. Depreciation expense was $0.3 million and $2.2 million for thenine months ended September 30, 2025 and 2024, respectively.

Other current liabilities

Other current liabilities consisted of the following as of each period end:

12. Subsequent Events

In October 2025, we announced a further reduction in workforce of approximately 29% of total workforce, retaining approximately 15 employees essential to executing on our strategic priorities. We expect to recognize approximately $1.3 million in total severance and related benefits as a result of this reduction in force. Approximately 50% of these charges are salary continuation payments and wages for the 60-day notice period in accordance with the California WARN Act. We may also incur other charges or cash expenditures not currently contemplated due to events that may occur as a result of, or associated with, the workforce reduction.