Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

You should read the following discussion and analysis of our financial condition and results of operations together with our audited consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K. This discussion and other parts of this Annual Report contain forward-looking statements that involve risk and uncertainties, such as statements of our plans, objectives, expectations and intentions. As a result of many factors, including those factors set forth in the “Risk Factors” section of this Annual Report, our actual results could differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

Overview

Atara Biotherapeutics 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. Tab-cel (tabelecleucel) has received marketing authorization approval (MAA) under the proprietary name EbvalloTM for commercial sale in the European Economic Area (EEA) by the European Commission (EC), for commercial sale and use in the United Kingdom (UK) by the Medicines and Healthcare products Regulatory Agency (MHRA), and for commercial sale and use in Switzerland by Swissmedic. We are partnered with Pierre Fabre Medicament (Pierre Fabre) for commercialization in Europe and potential commercialization, if approved, worldwide, including in the U.S. Tab-cel is currently in Phase 3 development in the U.S. for patients with EBV- associated post-transplant lymphoproliferative disease (EBV+ PTLD) who have failed rituximab or rituximab plus chemotherapy, as well as other EBV-driven diseases.

In March 2025, we announced our decision to pause development of our allogeneic CAR T cell programs and to discontinue development operations for our CAR T programs, including all clinical trials evaluating ATA3219 and development operations for ATA3431. We have completed nearly all wind-down activities for the CAR T programs. We have also stopped development on ATA188, an allogeneic T-cell immunotherapy targeting multiple sclerosis (MS).

Our T-cell immunotherapy platform is potentially applicable to a broad array of targets and diseases. Our off-the-shelf, allogeneic T-cell platform allows for rapid delivery of a T-cell immunotherapy product manufactured in advance of patient need and stored in inventory, with each manufactured lot of cells providing therapy for numerous potential patients. This differs from autologous treatments, in which each patient’s own cells must be extracted, genetically modified outside the body and then delivered back to the patient, requiring a complex logistics network. We select the appropriate set of cells for use based on a patient’s unique immune profile.

In October 2021, we entered into the Commercialization Agreement with Pierre Fabre (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. As contemplated by the Pierre Fabre Commercialization Agreement, we entered into (i) a Manufacturing and Supply Agreement (ii) a Pharmacovigilance Agreement (iii) and a Quality Agreement, in each case, with Pierre Fabre to further advance our partnership with Pierre Fabre. In September 2022, we amended the Pierre Fabre Commercialization Agreement and received an additional $30 million milestone payment from Pierre Fabre following EC approval of Ebvallo for EBV+ PTLD and subsequent filing of the MAA transfer to Pierre Fabre, in exchange for, among other things, a reduction in: (i) royalties we are eligible to receive as a percentage of net sales of Ebvallo in the Initial 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 under the Pierre Fabre Commercialization Agreement. In December 2022, we entered into the HCRx Agreement with HCR Molag Fund L.P. (HCRx,) a Delaware limited partnership. Pursuant to the terms of the HCRx Agreement, we received a total investment amount of $31 million in exchange for HCRx being entitled to receive a portion of the tiered, sales-based royalties for Ebvallo, in amounts ranging from the mid-single digits to significant double digits, as well as certain milestone payments, both related to the Initial Territory and otherwise payable to us by Pierre Fabre. The total royalties and milestones payable to HCRx related to the Initial Territory under the HCRx Agreement are capped between 185% and 250% of the total investment amount by HCRx, dependent upon the timing of such royalty and milestone payments to HCRx.

On October 31, 2023, we entered into an amended and restated Pierre Fabre Commercialization Agreement (A&R Commercialization Agreement), pursuant to which we expanded Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute tab-cel (Ebvallo) 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 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, 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. In March 2025, we completed the transfer of all manufacturing responsibility to Pierre Fabre under the A&R Commercialization Agreement Amendment. Pierre Fabre is now responsible for manufacturing and supplying tabelecleucel for development and commercialization worldwide at its cost. Pursuant to the A&R Commercialization Agreement Amendment, Pierre Fabre has also agreed to assume the 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 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. In December 2025, we amended the A&R Commercialization Agreement to, among other things, mitigate the impact of the cost of rebuilding commercial inventory in the United States. We agreed to reduce the milestone payment due upon BLA approval of tab-cel to $31 million in exchange for the right to receive an additional $15 million potential milestone payment upon achieving a certain commercial milestone. Under the terms of the A&R Commercialization Agreement, as amended by the A&R Commercialization Agreement Amendment, we are entitled to receive an aggregate of up to $308 million in remaining milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Initial Territory, and an aggregate of up to $556 million in additional potential milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory, including up to $31.0 million in potential regulatory milestones in connection with the approval by the FDA of a BLA for tab-cel. We are also eligible to receive significant double-digit tiered royalties as a percentage of net sales of tab-cel (Ebvallo) in the 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 in each such country. Royalty payments may be reduced in certain specified customary circumstances. Royalties and milestones from the commercialization of Ebvallo in the Initial Territory remain subject to the HCRx Agreement.

We entered into research collaborations with leading academic institutions such as Memorial Sloan Kettering Cancer Center (MSK) and the Council of the Queensland Institute of Medical Research (QIMR Berghofer) pursuant to which we acquired rights to novel and proprietary technologies and programs. In May 2025, we returned the rights to the ATA188 and EBV Vaccine programs to QIMR.

We and FUJIFILM Diosynth Biotechnologies California, Inc. (FDB) entered into a Master Services and Supply Agreement (Fujifilm MSA), which became effective in April 2022 and could extend for up to ten years. Pursuant to the Fujifilm MSA, FDB will supply us with specified quantities of our cell therapy products (if approved) and product candidates, manufactured in accordance with cGMP standards. The Fujifilm MSA does not obligate us to purchase products and product candidates exclusively from FDB. In March 2025, in connection with the transition of manufacturing responsibility for tab-cel to Pierre Fabre, we assigned and Pierre Fabre assumed, the Fujifilm MSA.

We had non-cancellable minimum commitments for products and services, subject to agreements with a term of greater than one year, with CROs and CMOs. In March 2025, the CMO agreements were assigned to Pierre Fabre as part of the A&R Commercialization Agreement Amendment, and we have been relieved of our obligations under the CMO agreements as of June 30, 2025. In July 2025, the CRO agreements were assigned to Pierre Fabre and we have been relieved of our obligations under the CRO agreements.

We have executed various strategic reductions in force over the past several years. In November 2023, we announced a reduction in force of approximately 30% of our workforce at that time. This workforce reduction resulted in 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 December 31, 2025, there are no remaining payments for the November 2023 reduction in force. All of the costs were cash expenditures and represent one-time termination benefits.

In January 2024, we announced a reduction in force at that time of approximately 25%. 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 December 31, 2025, there are no remaining payments for the January 2024 reduction in force. The majority of the associated costs were cash expenditures and primarily represented one-time termination benefits.

In January 2025, we announced another reduction in force at that time of approximately 50%. We recognized approximately $7.2 million in total severance and related benefits as a result of this reduction in force, consisting primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the severance was paid in the first half 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 by May 2026. As of December 31, 2025, approximately $0.5 million of further separation payments and benefits are required for the January 2025 reduction in force. The associated costs represent cash expenditures and primarily represent one-time termination benefits.

In January 2025, the U.S. Food and Drug Administration (FDA) issued a Complete Response Letter (Response Letter) for the Biologics License Application (BLA) for tab-cel as monotherapy treatment for adult and pediatric patients two years of age and older with Epstein-Barr virus positive post-transplant lymphoproliferative disease (EBV+ PTLD), who have received at least one prior therapy including an anti-CD20 containing regimen. The Response Letter only cited findings that arose during a pre-license inspection of a third-party manufacturing facility for tab-cel. The Response Letter did not identify any deficiencies related to the manufacturing process, the clinical efficacy, or clinical safety data in the BLA, and the FDA did not request any new clinical trials to support a potential approval of tab-cel. Additionally, in January 2025, the FDA placed a clinical hold on Atara’s active Investigational New Drug (IND) applications. These INDs include the tab-cel program as monotherapy treatment for adult and pediatric patients two years of age and older with Epstein-Barr virus positive post-transplant lymphoproliferative disease (EBV+ PTLD). The clinical hold is directly linked to inadequately addressed Good Manufacturing Practices (GMP) compliance issues referenced in the Response Letter. In May 2025, the FDA notified us that we have satisfactorily addressed all clinical hold issues and the FDA has lifted the clinical holds. In May 2025, we aligned with the FDA on a plan to address the issues raised by the FDA in the Response Letter and the path forward for resubmission of the tab-cel BLA at a Type A meeting. In July 2025, we resubmitted, and the FDA accepted, the tab-cel BLA. In January 2026, the FDA issued a second Complete Response Letter (Second Complete Response Letter) for the BLA for tab-cel as monotherapy treatment for adult and pediatric patients two years of age and older with EBV+ PTLD, who have received at least one prior therapy including an anti-CD20 containing regimen. In the Second Complete Response Letter, the FDA confirmed that the GMP compliance issues identified in the Response Letter had been satisfactorily resolved, and importantly, no safety issues were raised. However, the Second Complete Response Letter claims that ALLELE trial, previously confirmed by the FDA as adequate to support the BLA filing, is no longer considered to be an adequate and well-controlled study due to deficiencies in study design, conduct and analysis, to provide substantial evidence of effectiveness of tab-cel to treat relapsed or refractory EBV+ PTLD. In March 2026, our partner, Pierre Fabre, submitted a request for, and the FDA has granted, a Type A meeting to address the FDA's concerns in the Second Complete Response Letter. We anticipate providing a regulatory update in the second quarter of 2026.

In March 2025, we announced a further reduction in force at that time of approximately 50%. We recognized approximately $2.8 million in total severance and related benefits as a result of this reduction in force, consisting primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the severance was paid in the first half 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 by May 2026. As of December 31, 2025, approximately $0.1 million of further separation payments and benefits are required for the March 2025 reduction in force. The associated costs represent cash expenditures and primarily represent one-time termination benefits.

In May 2025, we announced a further reduction in force at that time of approximately 30%. We recognized approximately $1.4 million in total severance and related benefits as a result of this reduction in force, consisting primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the severance was paid in the second half of 2025. As of December 31, 2025, no further separation payments and benefits are required for the May 2025 reduction in force.

In October 2025, we announced a further reduction in force of approximately 30% of total workforce, retaining approximately 15 employees essential to advancing our strategic priorities. We recognized approximately $1.2 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. As of December 31, 2025, approximately $0.3 million of further separation payments and benefits are required for the October 2025 reduction in force. The associated costs are cash expenditures and primarily represent one-time termination benefits.

Legislative and Regulatory Developments

On July 4, 2025, President Trump signed the tax law referred to as One Big Beautiful Bill Act (“OBBBA”). OBBBA includes a broad range of U.S. tax reform measures, including, among other provisions, the immediate expensing of U.S. research and development expenditures. In accordance with ASC 740, the Company has recognized the effects of the new tax law in the period of enactment. As the Company maintains a full valuation allowance on its U.S. deferred tax assets, the legislation does not have a material impact on its consolidated financial statements.

In March 2021, the American Rescue Plan Act of 2021 (“ARPA”) was enacted. Among other provisions, ARPA expanded the scope of Internal Revenue Code Section 162(m) by increasing the number of covered employees subject to the $1 million limitation on the deductibility of compensation, effective for taxable years beginning after December 31, 2026. The Company evaluated the impact of this provision, including its potential effect on the deductibility of executive compensation and related deferred tax balances. Based on this evaluation, the Company concluded that the enactment of ARPA did not have a material impact on its income tax provision.

Review of Strategic Alternatives

Our board of directors regularly reviews our strategic plan, priorities, and opportunities as part of its commitment to act in the best interest of the Company and its stockholders. In January 2025, we announced that we had previously engaged a well-known financial advisor to support the assessment of opportunities to advance and realize value from our CAR T assets, for which we announced in March 2025 that we paused development. The advisor’s scope was expanded to include a wider range of additional strategic alternatives designed to maximize value for our stockholders, which may include, but are not limited to, an acquisition, merger, reverse merger, other business combinations, sale of assets, licensing, or other strategic transactions. Through this process, we were in active discussions with several potential parties. However, there can be no assurance regarding the results or outcome of this process. It is possible that we may not pursue a strategic alternative or transaction or that any strategic alternative or transaction, if pursued, will not be completed on attractive terms, or that a strategic alternative or transaction may not ultimately be consummated. Our board of directors continues to evaluate potential strategic transactions.

Financial Overview

We have a limited operating history. Since our inception in 2012, we have devoted substantially all of our resources to identify, acquire and develop our product candidates, including conducting preclinical and clinical studies, acquiring or manufacturing materials for clinical studies, and providing general and administrative support for these operations.

Our net income (loss) was $32.7 million and $(85.4) million for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, we had an accumulated deficit of $2.0 billion. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative expenses associated with our operations. As of December 31, 2025, our cash, cash equivalents and short-term investments totaled $8.5 million, which we intend to use to fund our operations.

Revenues

We have generated commercialization revenues under the A&R Commercialization Agreement, following the December 2022 EC approval of Ebvallo. Our commercialization revenue recognized to date is derived from agreements with Pierre Fabre, primarily related to upfront license fees, milestone payments and amounts recognized from the sale of zero-cost inventories for which all performance obligations are complete, and is subject to the terms of the HCRx Agreement. We do not retain any meaningful milestone or royalty payments related to the Initial Territory under the A&R Commercialization Agreement until the applicable royalty cap under the HCRx Agreement is met, if at all, and milestone or royalty payments related to the Additional Territory under the A&R Commercialization Agreement are subject to us obtaining regulatory approval in the US or for another market within the Additional Territory.

We expect that any revenue we generate from the A&R Commercialization Agreement, subject to the terms of the HCRx Agreement, will fluctuate from period to period as a result of the timing of potential milestone achievement and any potential regulatory approvals.

Cost of Commercialization Revenue

adjustments to inventories. Costs incurred to produce Ebvallo prior to regulatory approval, referred to as zero cost inventories, have been recorded as research and development expense in our consolidated statement of operations and comprehensive income (loss). Cost of commercialization revenue for Ebvallo produced after receiving regulatory approval and in a qualified manufacturing facility also include direct and indirect costs related to the production of Ebvallo. Such costs are recorded into cost of commercialization revenue as the related commercialization revenue is recognized. Such costs include, but are not limited to, CMO costs, quality testing and validation, materials used in production, and an allocation of compensation, benefits and overhead costs associated with employees involved with production.

Research and Development Expenses

The largest component of our total operating expenses since inception has been our investment in research and development activities, including the preclinical and clinical development of our product candidates. Research and development expenses consist primarily of compensation and benefits for research and development and regulatory support employees, including stock-based compensation; expenses incurred under agreements with contract research organizations and investigative sites that conduct preclinical and clinical studies; the costs of acquiring and manufacturing clinical study materials and other supplies, including expenses incurred under agreements with CMOs; payments under licensing and research and development agreements; other outside services and consulting costs; and facilities, information technology and overhead expenses. Research and development costs are expensed as incurred.

Our expenditures on future preclinical and clinical development programs are subject to numerous uncertainties in timing and cost to completion. The duration, costs, and timing of clinical studies and development of our product candidates will depend on a variety of factors, including:

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the scope, rate of progress, and expenses of research and development activities;

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the potential review or reanalysis of our clinical study results;

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future clinical study results;

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the availability of qualified drug supply;

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potential additional safety monitoring or other studies requested by regulatory agencies;

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changing medical practice patterns related to the indications we are investigating;

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significant and changing government regulation;

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disruptions caused by man-made or natural disasters or public health pandemics or epidemics, including, for example, the COVID-19 pandemic; and

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the timing and receipt of any regulatory approvals, as well as potential post-market requirements.

The process of conducting the necessary clinical research to obtain approval from the FDA and other regulators is costly and time consuming and the successful development of our product candidates is highly uncertain. The risks and uncertainties associated with our research and development projects are discussed more fully in the section of this report titled “1A. Risk Factors.” As a result of these risks and uncertainties, we are unable to determine with any degree of certainty the duration and completion costs of our research and development projects, or if, when, or to what extent we will generate revenues from the commercialization and sale of any of our product candidates that obtain regulatory approval.

General and Administrative Expenses

General and administrative expenses consist primarily of compensation and benefits for legal, human resources, finance and other general and administrative employees, including stock-based compensation; professional services costs, including legal, patent, human resources, audit and accounting services; other outside services; and consulting costs; and information technology and overhead expenses.

Interest Income

Interest income consists of interest earned on our cash, cash equivalents and short-term investments.

Interest Expense

Interest expense consists primarily of interest expense recorded in connection with the HCRx Agreement.

Provision for Income Taxes

Provision for income taxes consists primarily of income taxes in U.S. states and foreign jurisdictions. Our effective tax rate was 0.1% and 0% for the years ended December 31, 2025 and 2024, respectively.

Critical Accounting Policies and Significant Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the U.S. The preparation of these financial statements requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities and expenses. On an on-going basis, we evaluate our critical accounting policies and estimates. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable in the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions and conditions. Our significant judgments and estimates are detailed below, and our significant accounting policies are more fully described in Note 2 of the accompanying consolidated financial statements.

Revenue Recognition

Revenue from out-license agreements is recognized as we satisfy performance obligations and when a customer obtains control of the promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. Revenue generated from our out-license agreements is not subject to repayment and typically includes upfront fees, development, regulatory and commercial milestone payments and royalties on the licensee’s future product sales.

Our out-license agreements may include the transfer of intellectual property rights in the form of licenses, promises to provide research and development services and promises to participate on certain development committees with the collaboration party. We assess whether the promises in these agreements are considered distinct performance obligations that should be accounted for separately. Judgment is required to determine whether these promises are distinct.

The transaction price in each agreement is allocated to the identified performance obligations based on the standalone selling price (SSP) of each distinct performance obligation.

Revenue associated with nonrefundable upfront license fees where the license fees and other promises cannot be accounted for as separate performance obligations is deferred and recognized as revenue over the expected period of performance using an appropriate recognition method based on the nature of the performance obligations. We utilize judgment to assess the pattern of delivery of the performance obligation. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. A significant change in the assumptions and estimates, such as forecasted costs or the extent and timing of patient demand, and expected dates of technology transfer, could have a material impact on the timing and amount of revenue recognized in future periods or adjustments to cumulative revenue recognized in the period of change.

At the inception of each agreement that includes development, regulatory or commercial milestone payments, we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price by using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. The transaction price is allocated to each performance obligation in the agreement based on relative SSP. We typically determine SSPs using a cost plus margin approach model. Milestone payments that are not within our or the licensee’s control, such as regulatory approvals, are typically not considered probable of being achieved until those approvals are received. At the end of each reporting period, we re-evaluate the probability of achievement of each such milestone and any related constraint, and if necessary, adjust our estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Certain judgments affect the application of our revenue recognition policy. For example, we record short-term and long-term deferred revenue based on our best estimate of when such revenue will be recognized. Short-term deferred revenue consists of amounts that are expected to be recognized as revenue in the next 12 months, and long-term deferred revenue consists of amounts that we expect will be recognized after the next 12 months. As of December 31, 2025, this estimate is based on our forecasted regulatory

operating plan. If the duration or the scope of the tab-cel regulatory activities change in the future, we may recognize a different amount of deferred revenue over the next 12-month period.

Accrued Research and Development Expenses

As part of the process of preparing our financial statements, we are required to estimate and accrue expenses, the largest of which is related to research and development expenses, including those related to clinical studies and clinical product candidate manufacturing. This process involves reviewing contracts and purchase orders, identifying and evaluating the services that have been performed on our behalf, and estimating the associated cost incurred for the services which we have not yet been invoiced or otherwise notified of the actual costs incurred.

Costs for preclinical studies, clinical studies and product candidate manufacturing activities are recognized based on an evaluation of our vendors’ progress towards completion of specific tasks, using data such as patient enrollment, clinical site activations or information provided to us by our vendors regarding their actual costs incurred. Payments for these activities are based on the terms of individual contracts and payment timing may differ significantly from the period in which the services were performed. We determine accrual estimates through reports from, and discussions with, applicable personnel and outside service providers as to the progress or state of completion of studies, or the goods and services delivered. Our estimates of accrued expenses as of each balance sheet date are based on the facts and circumstances known at the time. Costs that are paid in advance of performance are deferred as a prepaid asset and recognized as expense as the services are provided.

For the years ended December 31, 2025 and 2024, there were no material changes from our estimates of accrued research and development expenses. We do not believe there is a reasonable likelihood that there will be a material change in the future estimates of accrued research and development expenses. However, if actual results are not consistent with our estimates, we may be exposed to changes in accrued research and development expenses that could be material or the accrued research and development expenses reported in our financial statements may not be representative of the actual economic cost of accrued research and development.

Stock-based Compensation

We have stock-based compensation programs, which include an employee incentive plan, an inducement plan and an employee stock purchase plan. See Note 2 – “Summary of Significant Accounting Policies” and Note 10 – “Stockholders' Equity” in the Notes to Consolidated Financial Statements, included in Item 8. Financial Statements and Supplementary Data of this report for a complete discussion of our stock-based compensation programs. We account for stock-based compensation expense, including the expense for grants of restricted stock units (RSUs) and stock options that may be settled in shares of our common stock, based on the fair values of the equity instruments issued. The fair value is determined on the measurement date, which is generally the date of grant. The fair value of our RSUs is measured at the market price of our common stock on the measurement date. The fair value for our stock option awards is determined at the grant date using the Black-Scholes valuation model.

Assumptions for the Black-Scholes valuation model used for employee stock awards include:

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Expected term – We derived the expected term for employee stock awards using the “simplified” method (the expected term is determined as the average of the time-to-vesting and the contractual life of the options), as we have limited historical information to develop expectations about future exercise patterns and post vesting employment termination behavior. Expected term for non-employee awards is based on the remaining contractual term of an option on each measurement date.

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Expected volatility – In earlier periods, volatility was estimated using an average of our historical volatility and comparable public companies’ volatility for similar terms. Beginning in 2023, volatility is based solely on Atara's historical stock price volatility.

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Expected dividend rate – We have not historically declared or paid dividends to our stockholders and have no plans to pay dividends; therefore, we have assumed an expected dividend yield of 0%.

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Risk-free interest rate – The risk-free interest rate is based on the yields of U.S. Treasury securities with expected terms similar to that of the associated award.

The fair value of our common stock is measured at the market price on the measurement date. For awards with performance-based vesting criteria, we assess the probability of the achievement of the performance conditions at the end of each reporting period and begin to recognize the share-based compensation costs when it becomes probable that the performance conditions will be met. For awards that are subject to both service and performance conditions, no expense is recognized until it is probable that performance conditions will be met. We do not believe there is a reasonable likelihood that there will be a material change in the future estimates or assumptions we use to determine stock-based compensation expense. However, if actual results are not consistent with our estimates or assumptions, we may be exposed to changes in stock-based compensation expense that could be material or the stock-based compensation expense reported in our financial statements may not be representative of the actual economic cost of the stock-based compensation.

Accounting for Income Taxes

See Note 11 – “Income Taxes” in the Notes to Consolidated Financial Statements, included in Item 8. Financial Statements and Supplementary Data of this report for a complete discussion of the components of our income tax expense, if any, as well as the temporary differences that exist as of December 31, 2025.

Our consolidated effective income tax rate is influenced by tax planning opportunities available to us in the various jurisdictions in which we conduct business. Significant judgment is required in evaluating our tax positions, including those that may be uncertain. We are also required to exercise judgment with respect to the realization of our net deferred tax assets. We evaluate all positive and negative evidence and exercise judgment regarding past and future events to determine if it is more likely than not that all or some portion of the deferred tax assets may not be realized. If appropriate, a valuation allowance is recorded against deferred tax assets to offset future tax benefits that may not be realized.

We do not believe that there is a reasonable likelihood that there will be a material change in our liability for uncertain income tax positions or our effective income tax rate. However, if actual results are not consistent with our estimates or assumptions, we may be exposed to losses that could be material. We recorded a valuation allowance of approximately $355.0 million as of December 31, 2025 related primarily to net operating loss carryforwards, and capitalized research expenses.

Liability related to the sale of future revenues

To the extent we account for the sale of future revenues as debt in accordance with ASC 470, we amortize the liability and recognize interest expense related to the sale of future revenues using the effective interest rate method over the estimated life of the underlying agreement. The liability and related interest expense are based on our current estimate of expected future payments over the life of the arrangement. We re-assess the amount and timing of expected payments each reporting period using a combination of internal projections and forecasts from external resources and record interest expense on the carrying value of the liability using the imputed effective interest rate. To the extent our estimates of future payments are greater or less than previous estimates or the estimated timing of such payments is materially different than previous estimates, this could impact the amount of interest expense we record each period as well as the amount and classification of the liability. We will account for any such changes by adjusting the effective interest rate on a prospective basis. The assumptions used in determining the expected repayment term of the liability and amortization period requires that we make estimates that could impact the effective interest rate, short-term and long-term classification of the liability and the period over which the liability will be amortized.

Results of Operations

Comparison of the Years Ended December 31, 2025 and 2024

Revenues

Revenue consisted of the following in the periods presented:

Year ended December 31,

(in thousands)

Commercialization revenues were $120.8 million in 2025 as compared to $128.9 million in 2024. The decrease in 2025 was primarily due to a year-over-year reduction in revenue from transition activities after tab-cel manufacturing and clinical activities transitioned to Pierre Fabre in March and July 2025 respectively; the decrease was partially offset by an increase in revenue from the

sale of inventory to Pierre Fabre and higher deferred revenue recognized in 2025 following the transition of manufacturing activities to Pierre Fabre in March 2025.

Cost of commercialization revenue

Cost of commercialization revenue consisted of the following in the periods presented:

Year ended December 31,

(in thousands)

Costs of commercialization revenues were $21.2 million in 2025 compared to $21.0 million in 2024. The 2025 cost reflects the cost of the inventory sold to Pierre Fabre on March 31, 2025, according to the A&R Commercialization Agreement, as amended, while the 2024 costs primarily includes expenses recognized associated with adjustments to reflect inventory at net realizable value.

Research and development expenses

Research and development expenses consisted of the following costs, by function, in the periods presented (certain items have been reclassified in prior periods for consistency in presentation):

Year ended December 31,

(in thousands)

Technical operations and quality expenses were $21.9 million in 2025 as compared to $92.5 million in 2024. The decrease in 2025 was primarily due to the transition of tab-cel manufacturing activities to Pierre Fabre as of March 31, 2025, reduced headcount following the January, March and May 2025 reductions in force and pause of research and development of the CAR T programs as of March 2025.

Medical and safety expenses were $9.8 million in 2025 as compared to $44.1 million in 2024. The decrease in 2025 was primarily due to reduced headcount following the January, March and May 2025 reductions in force, the transition of tab-cel development activities to Pierre Fabre as of July 14, 2025 and termination of the ATA3219 phase 1 trials in NHL and lupus after the decision to pause research and development for CAR T assets in March 2025.

Regulatory and quality expense were $5.8 million in 2025 as compared to $14.8 million in 2024. The decrease in 2025 was primarily due to reduced headcount following the January, March and May 2025 reductions in force.

General and administrative expenses

General and administrative expenses for the periods indicated were as follows:

Year ended December 31,

(in thousands)

General and administrative expenses were $26.3 million in 2025 as compared to $39.9 million in 2024. The decrease in 2025 was primarily due to reduced headcount following the January, March and May 2025 reductions in force.

Other income (expense), net

Year ended December 31,

(in thousands)

Other income (expense), net (34 ) 528 (562 )

Total other income (expense), net $ (3,143 ) $ (1,977 ) $ (1,166 )

Interest income was $0.7 million in 2025, as compared to $2.1 million in 2024. The decrease in 2025 was primarily driven by lower balances of cash, cash equivalents and available-for-sale securities.

Interest expense was $3.8 million in 2025 and $4.6 million in 2024. The decrease in 2025 was primarily due to decreased interest expense recognized on the liability related to the sale of future revenues under the HCRx Agreement.

Liquidity and Capital Resources

Sources of Liquidity

Since our inception in 2012, we have funded our operations primarily through the issuance of common and preferred stock, issuance of pre-funded warrants to purchase common stock, upfront fees and milestone payments from the Bayer License Agreement and the A&R Commercialization Agreement and the sale of our ATOM Facility to FDB in 2022.

In the past four 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.

In January 2024, we completed a registered direct offering of pre-funded warrants to purchase 1,090,907 shares of common stock at a price of $13.7475 per warrant. We received aggregate net proceeds of $14.8 million after deducting offering expenses payable by us.

In September 2024, we completed a registered direct offering of 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. We received aggregate net proceeds of $35.8 million after deducting offering expenses payable by us.

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.

During the year ended December 31, 2025, we sold an aggregate of 124,434 shares of common stock under the 2023 ATM Facility, at an average price of $12.21 per share, for net proceeds of $1.5 million, after deducting commission expenses payable by us.

As of December 31, 2025, we had $87.2 million of common stock remaining and available to be sold under the 2023 ATM Facility, which, following the filing of this Form 10-K, will be subject to the limitations under General Instruction I.B.6 to Form S-3 discussed below. Subsequent to December 31, 2025, we sold an aggregate of 493,117 shares of our common stock under the 2023 ATM Facility, at an average price of $6.08 per share, for net proceeds of $3.0 million, after deducting commission expenses payable by us.

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 has also agreed to assume the 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.

We have incurred losses and negative cash flows from operations in each year since inception and have generated limited commercialization revenues from the A&R Commercialization Agreement, following the December 2022 EU regulatory approval of Ebvallo, which is subject to the terms of the HCRx Agreement. We do not maintain any meaningful milestone or royalty payments from Pierre Fabre relative to the Initial Territory until the applicable royalty cap under the HCRx Agreement is met, if at all. We continue to incur significant research and development and other expenses related to our ongoing operations and expect to incur losses for the foreseeable future. As a result, we will need additional capital to fund our operations, which we may raise through a combination of equity offerings, debt financings, other third-party funding and other collaborations, strategic alliances and partnering arrangements. We may borrow funds on terms that may include restrictive covenants, including covenants that restrict the operation of our business, liens on assets, high effective interest rates and repayment provisions that reduce cash resources and limit future access to capital markets. In addition, we expect to continue to opportunistically seek access to additional funds through additional public or private equity offerings or debt financings including by utilizing the 2023 ATM Facility, through potential collaboration, partnering or other strategic arrangements, or a combination of the foregoing. To the extent that we raise additional capital by issuing equity securities, our stockholders may experience substantial dilution. To the extent that we raise additional funds through collaboration or partnering arrangements, we may be required to relinquish some of our rights to our technologies or rights to market and sell our products in certain geographies or grant licenses or other rights on terms that are not favorable to us.

As of the date of this Form 10-K, our public float was less than $75 million. As a result, we are subject to the limitations of General Instruction I.B.6 to Form S-3 until such time as our public float exceeds $75 million, which means we only have the capacity to sell shares up to one-third of our public float under shelf registration statements in any twelve-month period. We will remain constrained by the limitations of General Instruction I.B.6 to Form S-3 until such time as our public float exceeds $75 million, at which time the number of securities we may sell under a Form S-3 registration statement will no longer be limited by limitations of General Instruction I.B.6 to Form S-3.

Cash in excess of immediate requirements is invested in accordance with our investment policy, primarily with a view to liquidity and capital preservation. Currently, our cash, cash equivalents and short-term investments are held in bank and custodial accounts and consist of money market funds, U.S. Treasury, and corporate debt obligations.

Our cash, cash equivalents and short-term investments balances as of the dates indicated were as follows:

December 31, December 31,

(in thousands)

Short-term investments — 17,466

Total cash, cash equivalents and short-term investments $ 8,482 $ 42,496

Contractual Obligations and Commitments

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 consolidated statements of operations and comprehensive income (loss) for the year ended December 31, 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. In March 2025, we announced a pause on our CAR T research and development activities and initiated the

wind-down of the ARC facility. We considered this to be a triggering event and performed an impairment analysis on the right-of-use asset. In April 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 consolidated statements of operations and comprehensive income (loss). In August 2025, we executed an amendment to the ARC lease that reduced our leased premises to 12,750 square feet and terminated our option to extend the lease. We determined that this amendment constituted a triggering event resulting in a partial lease termination modification. For the year ended December 31, 2025, we recorded a non-cash reduction of $3.4 million to the right-of-use asset to reflect the decrease in the asset’s value following the lease modification. The modification also reduced the related lease liability, generating a $6.0 million gain. Overall, these changes resulted in a net gain of $2.6 million within research and development expenses on the accompanying consolidated statements of operations and comprehensive income (loss). The remaining right-of-use asset and lease liability associated with the ARC facility continue to be reflected 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 right-of-use 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. See Note 7 – “Leases” in the Notes to Consolidated Financial Statements, included in Item 8. Financial Statements and Supplementary Data of this report for further information on our lease obligations.

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 right-of-use 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 right-of-use assets and lease liabilities for the processing rooms and the freezers have been removed from our consolidated balance sheet as of June 30, 2025.

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 right-of-use 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 right-of-use 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 enter into contracts in the normal course of business with clinical research organizations for clinical studies, with CMOs for clinical and commercial materials, and with other vendors for preclinical studies and supplies and other services and products for operating purposes. These contracts generally provide for termination for convenience following a notice period. We have 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. See Note 9 – “Commitments and Contingencies” in the Notes to Consolidated Financial Statements, included in Item 8. Financial Statements and Supplementary Data of this report for further information on our contractual obligations and commitments.

Cash Flows

Comparison of the Years Ended December 31, 2025 and 2024

The following table details the primary sources and uses of cash for each of the periods set forth below:

Year Ended December 31,

(in thousands)

Net cash (used in) provided by:

Net decrease in cash, cash equivalents and restricted cash $ (16,694 ) $ (811 )

Operating activities

Net cash used in operating activities was $50.9 million in 2025 as compared to $68.7 million in 2024. The decrease of $17.8 million was primarily due to lower cash operating expenses in 2025 as compared to 2024, primarily due to lower compensation-related costs resulting from lower headcount driven by January, March and May 2025 reductions in force, as well as transition of tab-cel manufacturing activities to Pierre Fabre in March 2025.

Investing activities

Net cash provided by investing activities in 2025 consisted of $25.1 million received from maturities and sales of available-for-sale securities and $0.9 million in sales of property and equipment, partially offset by $7.9 million used to purchase available-for-sale securities.

Net cash provided by investing activities in 2024 consisted primarily of $28.5 million received from maturities and sales of available-for-sale securities, partially offset by $19.7 million used to purchase available-for-sale securities and $0.2 million in purchases of property and equipment.

Financing activities

Net cash provided by financing activities in 2025 consisted primarily of $14.8 million of net proceeds from sale of common stock and pre-funded warrants in underwritten registered direct offering, and $1.5 million of net proceeds from 2023 ATM facility.

Net cash provided by financing activities in 2024 consisted primarily of $50.6 million from sale of common stock and pre-funded warrants in registered direct offerings and $9.3 million of net proceeds from ATM facilities.

Operating Capital Requirements and Plan of Operations

We do not know when, or if, we will generate sufficient revenue from commercialization to offset our operating expenses. We anticipate that we will continue to generate losses for the foreseeable future, and we expect the accumulated losses to increase as we continue the development of, and seek regulatory approvals for, our product candidate. We are subject to all of the risks inherent in the development of new products, and we may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. We anticipate that we will need to raise substantial additional funding in the near term to finance our planned operations.

Our operating plan may change as a result of many factors currently unknown to us, and we may need additional funds sooner than planned. We do not have any committed external source of funds other than milestone and royalty payments that we may receive under the A&R Commercialization Agreement, subject to the terms of the HCRx Agreement. We do not retain any meaningful milestone or royalty payments related to the Initial Territory from Pierre Fabre until the applicable royalty cap under the HCRx Agreement is met, if at all.

Our existing cash, cash equivalents and short-term investments as of December 31, 2025 will not be sufficient to fund our planned operations for at least the next 12 months after the date of issuance of these financial statements. These conditions raise substantial doubt about our ability to continue as a going concern for at least 12 months after the issuance of the accompanying consolidated financial statements.

In order to complete the process of obtaining regulatory approval for tab-cel in the US, we may require substantial additional funding. We expect to continue to seek access to additional funds through additional public or private equity offerings or debt financings, through potential collaboration, partnering or other strategic arrangements, or a combination of the foregoing. If we are unable to obtain sufficient funding on acceptable terms, we could be forced to further delay, limit, reduce or terminate clinical studies or other development activities.

We have based our projections of operating capital requirements on assumptions that may prove to be incorrect, and we may use all of our available capital resources sooner than we expect. Because of the numerous risks and uncertainties associated with research, development and commercialization of pharmaceutical products, we are unable to estimate the exact amount of our operating capital requirements. Our future funding requirements will depend on many factors, including, but not limited to:

•

the timing, costs and results of our ongoing and planned clinical studies for our product candidates;

•

our partner's success in establishing and maintaining manufacturing relationships with their CMOs;

•

the number and characteristics of product candidates that we pursue;

•

the outcome, timing and costs of seeking regulatory approvals;

•

subject to receipt of regulatory approval, costs associated with the commercialization of our product candidates by our partners and the amount of revenues received from commercial sales of our product candidates;

•

the timing of proceeds from, and our ability to perform under, the A&R Commercialization Agreement, subject to the HCRx Agreement, as well as the terms and timing of any future commercialization, collaboration, licensing, partnering or other arrangements that we may establish;

•

the amount and timing of any payments we may be required to make in connection with the licensing, filing, prosecution, maintenance, defense and enforcement of any patents or patent applications or other intellectual property rights;

•

the extent to which we in-license or acquire other products and technologies; and

•

the timing of the qualification of our partner's CMOs’ manufacturing facilities.

Until we are able to generate a sufficient amount of net cash inflows from operations, which we may never do, meeting our long-term capital requirements is in large part reliant on access to public and private equity and debt capital markets, augmented by cash generated from operations and interest income earned on the investment of our cash balances. We expect to continue to seek access to the equity and debt capital markets to support our development efforts and operations. To the extent that we raise additional capital by issuing equity securities, our stockholders may experience substantial dilution. To the extent that we raise additional funds through commercialization, collaboration or partnering arrangements, we may be required to relinquish some of our rights to our technologies or rights to market and sell our products in certain geographies, grant licenses or other rights on terms that are not favorable to us, or issue equity that may be substantially dilutive to our stockholders.

As a result of economic conditions, general global economic uncertainty, political change and other factors, we do not know whether additional capital will be available when needed, or that, if available, we will be able to obtain additional capital on reasonable terms. If we are unable to raise additional capital due to the volatile global financial markets, general economic uncertainty or other factors, we will be forced to delay, limit, reduce or terminate preclinical studies, clinical studies or other development activities for one or more of our product candidates.

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

Interest Rate Market Risk

We are exposed to market risk related to changes in interest rates. As of December 31, 2025, we had total cash, cash equivalents and short-term investments of $8.5 million. Our primary exposure to market risk is interest rate sensitivity, which is affected by changes in the general level of U.S. interest rates, particularly because our investments are in short-term securities. Our available-for-sale securities are subject to interest rate risk and will decrease in value if market interest rates increase, which could result in a realized loss if we are forced to sell an investment before its scheduled maturity. We currently do not hedge our interest rate risk exposure. Due to the short-term duration of our investment portfolio and the low risk profile of our investments, an immediate change in interest rates of 100 basis points would not result in a material change in the fair market value of our portfolio.

The primary objectives of our investment activities are capital preservation and liquidity, while at the same time maximizing the income we receive from our investments without significantly increasing risk. To achieve this objective, we maintain our portfolio of cash equivalents and short-term and long-term investments in a variety of securities, including money market funds, U.S. Treasury,

government agency and corporate debt obligations, commercial paper and asset-backed securities. These securities are all classified as available-for-sale and consequently are recorded on the balance sheet at fair value, with unrealized gains or losses reported as a separate component of accumulated other comprehensive income (loss). Our holdings of the securities of any one issuer, except for obligations of the U.S. Treasury, U.S. Treasury-guaranteed securities or money market funds, do not exceed 5% of our portfolio.

Item 8. Financial Statements and Supplementary Data

Index to Consolidated Financial Statements

Page

Report of Independent Registered Public Accounting Firm (PCAOB ID 34) 95

Consolidated Balance Sheets 98

Consolidated Statements of Operations and Comprehensive Income (Loss) 99

Consolidated Statements of Stockholders’ Equity (Deficit) 100

Consolidated Statements of Cash Flows 101

Notes to Consolidated Financial Statements 102

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the shareholders and the Board of Directors of Atara Biotherapeutics, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Atara Biotherapeutics, Inc. and subsidiaries (the "Company" or “Atara”) as of December 31, 2025 and 2024, the related consolidated statements of operations and comprehensive income (loss), stockholders’ equity (deficit), and cash flows, for each of the two years in the period ended December 31, 2025, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.

Going Concern

The accompanying financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 2 to the financial statements, the Company’s negative cash flow from operations and losses from operations raises substantial doubt about its ability to continue as a going concern. Management’s plans in regard to these matters are also described in Note 2. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB.

Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Commercialization Revenue and Deferred Revenue – Accounting for Out- License Agreements – Refer to Notes 2 and 5 to the Financial Statements

Critical Audit Matter Description

The Company has entered into certain out-license agreements with Pierre Fabre Medicament ("Pierre Fabre").

During 2021, the Company entered into a Commercialization Agreement with Pierre Fabre. Under the terms of the agreement, the Company granted Pierre Fabre a license to commercialize and distribute Ebvallo in an initial territory and became responsible for manufacturing and supplying Ebvallo to Pierre Fabre, along with related cell selection services. In 2022, the Company entered into an

Amendment Agreement to the Pierre Fabre Commercialization Agreement (the “PF Amendment No. 1”). Under the terms of the PF Amendment No. 1, Atara became entitled to an additional milestone payment in exchange for, among other things, a reduction in: (i) royalties Atara is eligible to receive, and (ii) the price mark up on supply purchased by Pierre Fabre. Additionally, Atara also agreed to extend the time period for provision of certain services to Pierre Fabre under the Pierre Fabre Commercialization Agreement. In 2023, the Company entered into an amended and restated Pierre Fabre Commercialization Agreement (the “A&R Commercialization Agreement”). Under the terms of the A&R Commercialization Agreement, the Company granted Pierre Fabre an expanded license to commercialize and distribute Ebvallo in all other countries in the world and remained responsible for manufacturing and supplying Ebvallo to Pierre Fabre, along with related cell selection services until transfer of responsibility to Pierre Fabre.

In 2024, the Company entered into an agreement with Pierre Fabre to sell certain intermediates used in the manufacture of Ebvallo for $15.5 million.

In March 2025, the Company transferred all process science services and manufacturing responsibilities to Pierre Fabre. In July 2025, the Company 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. In October 2025, Atara further amended the A&R Commercialization Agreement to transfer all regulatory activities (including sponsorship of the tab-cel BLA) to Pierre Fabre. In December 2025, the Company further amended the A&R Commercialization Agreement agreeing to reduce the milestone payment due upon BLA approval of tab-cel to $31 million in exchange for the right to receive an additional $15 million potential milestone payment upon achieving a certain commercial milestone.

The Company recognizes revenue on the commercialization agreements with Pierre Fabre as they satisfy their performance obligations and when the customer obtains control of the promised goods or services. The revenue related to the commercialization agreements with Pierre Fabre is recognized within commercialization revenue within the Consolidated Statements of Operations and Comprehensive Income (Loss). As of December 31, 2025, the Company recognized $120.8M of commercialization revenue and deferred revenue amounted to $0.7M, which is included in current liabilities.

We identified accounting for the commercialization agreements, the revenue recognized, and the estimated deferred revenue to be recognized as revenue as a critical audit matter. Given the judgments necessary to determine the accounting literature to apply to a commercialization agreement, the method to estimate and measure the progress toward the completion of the performance obligations and the estimated contractual term over which the performance obligations would be completed, auditing such judgments and estimates required extensive audit effort due to the complexity of the commercialization agreements and the high degree of auditor judgment applied when performing audit procedures and evaluating the results of those procedures.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to determining the accounting literature to apply to the agreements, assessing management's method for measuring progress and evaluating management’s estimation of the contract term over which the performance obligations will be completed included the following, among others:

•

We reviewed and obtained an understanding of the Company’s revenue generating agreements and related transactions during and at the end of the year via review of internal and external presentations, news and publications, and discussions with management.

•

We evaluated the Company’s conclusions related to the accounting for contract modifications.

•

We evaluated management’s determination that the agreements are within the scope of ASC 606 - Revenue from Contracts with Customers.

•

We evaluated management's determination of the contractual term and the appropriateness of management's method to measure its progress over that term.

•

We evaluated the assumptions used in the estimates of total costs and the estimated measure of progress for recognizing revenues by:

Performing corroborating inquiries with the Company's project and business development managers, and comparing the assumptions used in the estimates to management's work plans, cost estimates and costs reported to date, and material rights allocated, accumulated and earned.

Comparing costs incurred for activities completed to date to the costs forecasted for those activities.

Comparing material rights accumulated and earned for activities completed to date to the fulfilment of performance obligations forecasted for those activities.

Testing the mathematical accuracy of management’s revenue and current and long-term deferred revenue balances based on the estimated revenue to be recognized over time.

/s/ DELOITTE & TOUCHE LLP

San Francisco, California

March 16, 2026

We have served as the Company’s auditor since 2013.

Atara Biotherapeutics, Inc.

Consolidated Balance Sheets

(In thousands, except per share amounts)

December 31, December 31,

Assets

Current assets:

Short-term investments — 17,466

Restricted cash — 146

Property and equipment, net 73 1,294

Liabilities and stockholders’ equity (deficit)

Current liabilities:

Accrued research and development expenses 82 7,984

Liability related to the sale of future revenues – current portion 9,750 382

Operating lease liabilities – long-term 9,347 29,914

Liability related to the sale of future revenues – long-term 32,673 38,624

Commitments and contingencies (Note 9)

Stockholders’ equity (deficit):

Accumulated other comprehensive income 1 8

Total stockholders’ equity (deficit) (38,502 ) (97,283 )

Total liabilities and stockholders’ equity (deficit) $ 20,235 $ 109,098

See accompanying notes to the consolidated financial statements.

Atara Biotherapeutics, Inc.

Consolidated Statements of Operations and Comprehensive Income (Loss)

(In thousands, except per share amounts)

Years Ended December 31,

Costs and operating expenses:

Other income (expense), net:

Other income (expense), net: (34 ) 528

Total other income (expense), net (3,143 ) (1,977 )

Income (loss) before provision for (benefit from) income taxes 32,719 (85,415 )

Provision for (benefit from) income taxes 31 (12 )

Other comprehensive gain (loss):

Unrealized gain (loss) on available-for-sale securities (7 ) 212

Basis earnings (loss) per common share $ 2.61 $ (11.41 )

Diluted earnings (loss) per common share $ 2.57 $ (11.41 )

Basic weighted-average shares outstanding 12,544 7,488

Diluted weighted-average shares outstanding 12,718 7,488

See accompanying notes to the consolidated financial statements.

Atara Biotherapeutics, Inc.

Consolidated Statements of Changes in Stockholders’ Equity (Deficit)

(In thousands)

Accumulated

Common Additional Other Total

Stock Paid-in Comprehensive Accumulated Stockholders’

Shares Amount Capital Income (Loss) Deficit Equity (Deficit)

Exercise of pre-funded warrants 9 — — — — -

RSU settlements, net of shares withheld 314 — (7 ) — — (7 )

Issuance of common stock pursuant to employee stock awards 26 — 230 — — 230

Stock-based compensation expense — — 27,001 — — 27,001

Unrealized gain (loss) on available-for-sale securities — — — 212 — 212

Exercise of pre-funded warrants 49 — — — — -

RSU settlements, net of shares withheld 453 — (1 ) — — (1 )

Issuance of common stock pursuant to employee stock awards 4 — 35 — — 35

Stock-based compensation expense — — 9,752 — — 9,752

Unrealized gain (loss) on available-for-sale securities — — — (7 ) — (7 )

See accompanying notes to the consolidated financial statements.

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Atara Biotherapeutics, Inc.

Consolidated Statements of Cash Flows

(In thousands)

Year Ended December 31,

Operating activities

Depreciation and amortization expense 2,116 5,051

Accretion of liability related to sale of future revenues 3,578 4,109

Amortization (accretion) of investment premiums (discounts) 259 (240 )

Loss on impairment of lease right-of-use asset 4,130 —

Gain on derecognition of lease liabilities upon contract assignment (3,818 ) —

Other non-cash items, net 94 (402 )

Changes in operating assets and liabilities:

Accrued research and development expenses (7,902 ) (9,380 )

Operating lease liabilities (5,453 ) (11,051 )

Other long-term liabilities 1 (462 )

Net cash used in operating activities (50,940 ) (68,717 )

Investing activities

Purchases of short-term investments (7,885 ) (19,665 )

Proceeds from maturities and sales of short-term investments 25,085 28,535

Purchases of property and equipment — (246 )

Proceeds from sale of property and equipment 948 —

Net cash provided by investing activities 18,148 8,624

Financing activities

Proceeds from issuance of common stock through ATM facilities, net 1,471 9,348

Proceeds from employee stock awards 35 230

Principal payments on finance lease obligations (250 ) (892 )

Other financing activities, net (1 ) (7 )

Net cash provided by financing activities 16,098 59,282

Decrease in cash, cash equivalents and restricted cash (16,694 ) (811 )

Cash, cash equivalents and restricted cash at beginning of period 25,176 25,987

Cash, cash equivalents and restricted cash at end of period $ 8,482 $ 25,176

Supplemental cash flow disclosure

Cash paid for interest $ 286 $ 685

Cash paid for income taxes $ 190 $ 24

See accompanying notes to the consolidated financial statements.

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Atara Biotherapeutics, Inc.

Notes to Consolidated Financial Statements

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 EbvalloTM 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 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 were one-time termination benefits and were all cash charges.

In January 2024, we announced a reduction in force 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 were cash expenditures and primarily one-time termination benefits.

In January 2025, we announced a reduction in force of approximately 50% of our total force at that time. We recognized approximately $7.2 million in total severance and related benefits as a result of this reduction in force, consisting primarily of severance payments and wages for the 60-day notice period in accordance with the California WARN Act. In most cases, the

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severance was paid in the first half 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 by May 2026. As of December 31, 2025, approximately $0.5 million of further separation payments and benefits are required for the January 2025 reduction in force. The associated costs represent 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. 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 first half 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 by May 2026. As of December 31, 2025, approximately $0.1 million of further separation payments and benefits are required for the March 2025 reduction in force. 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. 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. In most cases, the severance was paid in the second half of 2025. As of December 31, 2025, no further separation payments and benefits are required for the May 2025 reduction in force. The majority of the associated costs are cash expenditures and primarily represent one-time termination benefits.

Certain prior year amounts, which are not material, have been reclassified to conform to current year presentation in the consolidated balance sheets and the notes to consolidated financial statements.

Summary of Significant Accounting Policies

Principles of Consolidation

The consolidated financial statements include the accounts of Atara and its wholly owned subsidiaries. All intercompany balances and transactions are eliminated in consolidation.

Segment and Geographic Information

We operate and manage our business as one 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 (certain items have been reclassified in prior periods for consistency in presentation):

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Year Ended December 31,

(in thousands)

Less:

Technical operations and quality expenses 21,863 92,514

*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 and collaboration revenue recognized in 2025 and 2024 related to our agreements with Pierre Fabre, a French company.

Use of Estimates

We prepare our consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP), which requires us to make estimates and assumptions that affect the amounts reported in our consolidated financial statements and accompanying notes. The level of uncertainty in estimates and assumptions increases with the length of time until the underlying transactions are completed. Significant estimates and assumptions relied upon in preparing these financial statements include those related to revenue recognition, accrued research and development expenses, stock-based compensation expense, liability related to the sale of future revenues and income taxes. Additionally, we use available market information to assess the fair value of our short-term investments. Actual results could differ materially from those estimates. If actual amounts differ from estimates, we include the updates in our consolidated results of operations in the period the actual amounts become known. Historically, the aggregate differences, if any, between our estimates and actual amounts in any year have not had a material effect on our 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 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

The Company has experienced negative cash flows from operations and with the exception of the year ended December 31, 2025, have also incurred substantial operating losses since inception, and we expect that existing cash, cash equivalents and short-term investments as of December 31, 2025, will not be sufficient to fund our planned operations for at least 12 months from the date of issuance of these consolidated financial statements.

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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 candidate program 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 consolidated financial statements. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Concentration of Credit Risk and Other Uncertainties

We place cash and cash equivalents in the custody of financial institutions that management believes are of high credit quality, the amount of which at times, may be in excess of the amount insured by the Federal Deposit Insurance Corporation. We also make short-term investments in money market funds; U.S. Treasury, government agency and corporate debt obligations; commercial paper; certificates of deposit; and asset-backed securities, which can be subject to certain credit risk. We strive to mitigate this credit risk by investing in high-grade instruments, limiting our exposure to any one issuer and monitoring the ongoing creditworthiness of the financial institutions and issuers.

Currency Translation

Transactions and monetary assets and liabilities that are denominated in a foreign currency are translated into U.S. dollars at the current exchange rate on the transaction date and as of each balance sheet date, respectively, with gains or losses on foreign exchange changes recognized in interest and other income (expense), net in the consolidated statements of operations and comprehensive loss. Foreign currency-denominated monetary assets and liabilities as of December 31, 2025 were not material.

Cash, Cash Equivalents and Short-Term Investments

Cash and cash equivalents are defined as highly liquid investments with original maturities of 90 days or less at the date of purchase.

Investments with original maturities of greater than 90 days are classified as short-term investments on the balance sheet.

As our entire investment portfolio is considered available for use in current operations, we classify all investments as available-for-sale and as current assets, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive loss, which is a separate component of stockholders’ equity in the consolidated balance sheet.

The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity, which are recorded to interest income in the consolidated statements of operations and comprehensive income (loss).

Changes in the fair value of available-for-sale securities impact the consolidated statements of operations and comprehensive income (loss) only when such securities are sold, if an allowance for credit losses is recognized or if an impairment is recognized. Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. We regularly review our investment portfolio to determine if any security is impaired, which would require us to record an allowance for credit losses or impairment charge in the period any such determination is made. In making this judgment, we evaluate, among other things, the duration and extent to which the fair value of a security is less than its cost, our intent to sell or whether it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis, the financial condition of the issuer and any changes thereto, and, as necessary, the portion of a decline in fair value that is credit-related. This assessment could change in the future due to new developments or changes in assumptions related to any particular security. Realized gains and losses, allowances for credit losses and impairments on available-for-sale securities, if any, are recorded to other income (expense), net in the statements of operations and comprehensive income (loss).

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Fair Value Measurement

The carrying amounts of certain of our financial instruments including cash equivalents, accounts receivable, other current assets, accounts payable and accrued liabilities approximate fair value due to their short maturities. Short-term investments are comprised of available-for-sale securities, which are carried at fair value.

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 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.

Accounts Receivable, net

Accounts receivable are primarily amounts due from our commercialization partner.

We estimate the allowance for doubtful accounts using the current expected credit loss model, or CECL model. Under the CECL model, the allowance for doubtful accounts reflects the net amount expected to be collected from the accounts receivable. We evaluate the collectability of these cash flow based on the asset’s amortized cost, the risk of loss even when that risk is remote, losses over an asset’s contractual life, and other relevant information available to us. Accounts receivable balances are written off against the allowance when it is probable that the receivable will not be collected. Given the nature and history of our accounts receivable, we determined that an allowance for doubtful accounts was not required for the periods presented.

Inventories

Inventories are stated at the lower of cost or estimated net realizable value, on a specific identification basis. We use actual costs to determine our cost basis for inventories. Inventories consist of raw materials, work-in-process and finished goods.

We begin capitalizing costs as inventory when the product candidate receives regulatory approval and when the manufacturing facility producing such inventory is qualified by the relevant regulatory agency. Prior to regulatory approval and facility qualification, we record such production costs related to product candidates as research and development expenses. Any manufactured product that is available for commercial sale is recorded to inventory; to the extent it is later used for clinical studies, such inventory costs are then recorded within research and development expenses.

We assess the recoverability of our inventory each reporting period and reduce the carrying value of the inventory when items are determined to be obsolete, defective or in excess of forecasted production requirements. Inventory write-downs for excess, defective and obsolete inventory are recorded within cost of commercialization revenue.

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Property and Equipment, net

Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets, ranging from three to five years, except for leasehold improvements, which are depreciated on a straight-line basis over the lesser of the estimated useful life of the leasehold improvement or the lease term. Costs incurred to acquire, construct or install property and equipment during the construction stage of a capital project or costs incurred to purchase and develop internal use software during the application development stage are recorded as construction in progress. Maintenance and repairs are expensed as incurred.

Long-lived Assets

We evaluate the carrying amount of our long-lived assets whenever events or changes in circumstances indicate that the assets may not be recoverable. An impairment loss would be recognized when estimated future cash flows expected to result from the use of the asset and its eventual disposition are less than the carrying amount of the asset. To date, there have been no such impairment losses.

Asset Retirement Obligation (ARO)

An ARO is a legal obligation associated with the retirement of long-lived assets pertaining to leasehold improvements. These liabilities are initially recorded at fair value and the related asset retirement costs are capitalized by increasing the carrying amount of the related assets by the same amount as the liability. Asset retirement costs are subsequently depreciated over the useful lives of the related assets. Subsequent to initial recognition, we record period-to-period changes in the ARO liability resulting from the passage of time and revisions to either the timing or the amount of the original estimate of undiscounted cash flows. We derecognize ARO liabilities when the related obligations are settled.

Leases

We determine if a contract is or contains a lease at contract inception. Operating leases are included in operating lease assets, other current liabilities, and operating lease liabilities on our consolidated balance sheets. Our policy is to not recognize right-of-use assets and lease liabilities for short-term operating leases with terms of 12 months or less; we recognize short-term lease expense for these leases on a straight-line basis over the lease term. Operating lease right-of-use assets and long-term operating lease liabilities are presented separately and operating lease liabilities payable in the next twelve months are recorded in other current liabilities. Finance lease right-of-use assets are recorded in other assets and the related finance lease liabilities are presented in other current liabilities and other long-term liabilities.

Lease assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. The lease term includes renewal options that we are reasonably certain of exercising as of the commencement date. None of the lease terms used to calculate the future minimum lease payments at commencement date include renewal options. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The incremental borrowing rate for our leases is determined based on lease term and currency in which lease payments are made, adjusted for impacts of collateral. Lease assets also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Operating lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Finance lease assets are amortized over the shorter of the lease term or the asset’s estimated useful life.

Our facilities and equipment operating leases have lease and non-lease components and we have made a policy election to account for the lease and non-lease components as a single lease component.

We are considered the sub-lessor for one of our leases where we have entered into a sub-lease agreement with or have assigned our lease to another party. Rental income was not material for any period presented and we record rental income as a reduction to rent expense within operating expenses.

We analyze whether or not amendments to existing leases classify as a lease modification or a full or partial termination of the existing lease. To the extent a partial lease termination is identified, our accounting policy is to decrease the existing right-of-use asset on a basis proportionate to the reduction in lease liability resulting from the partial termination.

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Accruals of Research and Development Costs

We record accruals for estimated research and development costs based on an evaluation of our vendors’ progress towards completion of specific tasks, using data such as patient enrollment, clinical site activations or information provided to us by our vendors regarding their actual costs incurred. Payments for these activities are based on the terms of individual contracts and payment timing may differ significantly from the period in which the services are performed. We determine accrual estimates through reports from and discussions with internal personnel and outside service providers as to the progress or state of completion of studies, or the services completed. Our estimates of accrued expenses as of each balance sheet date are based on the facts and circumstances known at the time. Costs that are paid in advance of performance are deferred as a prepaid asset and recognized as expense as the services are provided.

Sale of Future Revenues

To the extent that we account for the sale of future revenues as debt in accordance with ASC 470, we amortize the liability and recognize interest expense related to the sale of future revenues using the effective interest rate method over the estimated life of the underlying agreement. The liability and related interest expense are based on our current estimate of expected future payments over the life of the arrangement. We re-assess the amount and timing of expected payments each reporting period using a combination of internal projections and forecasts from external resources and record interest expense on the carrying value of the liability using the imputed effective interest rate on a prospective basis.

Revenue Recognition

For contracts that are determined to be within the scope of Accounting Standards Codification Topic 606 (Accounting Standards Update (ASU) No. 2014-09), Revenue from Contracts with Customers, and all subsequent amendments (collectively, ASC 606), revenue is recognized as we satisfy performance obligations and when a customer obtains control of the promised goods or services. The amount of revenue recognized reflects the consideration to which we expect to be entitled to receive in exchange for these goods and services. To achieve this core principle, we apply the following five steps (i) identify the contract with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as we satisfy a performance obligation. We only apply the five-step model to contracts when we determine that collection of substantially all consideration for goods and services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration.

Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct and are distinct in the context of the contract. To the extent a contract includes multiple promised goods and services, we apply judgment to determine whether promised goods and services are both capable of being distinct and distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation.

The transaction price is determined based on the consideration to which we will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, we estimate the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method, depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in our judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. Determining the transaction price requires significant judgment, which is discussed in further detail for our out-license agreements in Note 5 - “Financial Instruments” in the Notes to Consolidated Financial Statements. Our out-license agreements do not contain a significant financing component.

If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation. The consideration to be received is allocated among the separate performance obligations based on relative standalone selling prices. We typically determine standalone selling prices using an expected cost plus margin approach model.

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We satisfy performance obligations either over time or at a point in time. Revenue is recognized over time if either (i) the customer simultaneously receives and consumes the benefits provided by our performance, (ii) our performance creates or enhances an asset that the customer controls as the asset is created or enhanced or (iii) our performance does not create an asset with an alternative use to the entity and we have an enforceable right to payment for performance completed to date. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. If we do not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring control of a promised good or service to a customer.

As discussed in further detail in Note 5 - "Financial Instruments", the terms of our customer contracts include potential payments to us for some or all of the following: nonrefundable, upfront fees; development, regulatory, and commercial milestone payments; research and development funding payments; royalties on the net sales of licensed products; and transition plan cost reimbursements for certain development, safety, regulatory, and process science services. These payments relate to promised goods or services for which revenue will be recognized upon our satisfaction of the underlying performance obligations.

Licenses of intellectual property: If the license of our intellectual property is determined to be distinct from the other performance obligations identified in an arrangement, we recognize revenues from consideration allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are combined with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue.

Upfront payments: Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until we have satisfied our obligations under these arrangements.

Milestone payments: At the inception of each arrangement that includes development milestone payments, we evaluate the probability of reaching the milestones and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur in the future, the associated milestone value is included in the transaction price. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which we recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of such development milestones and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license and collaboration revenues and the consolidated statements of operations and comprehensive income (loss) in the period of adjustment.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on levels of sales, if the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied, or partially satisfied. To date, we have not recognized material royalty revenue resulting from our out-licensing agreements.

Transition plan cost reimbursements: Reimbursements for certain development, safety, regulatory and manufacturing services are recorded as revenue as we perform the services and related obligations identified within the transition plans for our customers.

Certain judgments affect the application of our revenue recognition policy. For example, we record short-term and long-term deferred revenue based on our best estimate of when such revenue will be recognized. Short-term deferred revenue consists of amounts that are expected to be recognized as revenue in the next 12 months, and long-term deferred revenue consists of amounts that we expect will be recognized after the next 12 months. This estimate is based on forecasted patient demand, our current operating plan and expected dates of technology transfer, and if these items should change in the future, we may recognize a different amount of deferred revenue over the next 12-month period.

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Cost of commercialization revenue

Cost of commercialization revenue consists primarily of expenses associated with cell selection services performed for Pierre Fabre, in-license sales-related milestone costs, period manufacturing expenses and adjustments to reduce inventory to the lower of cost or net realizable value. The majority of tab-cel (Ebvallo) sold to Pierre Fabre to date had been produced prior to receiving regulatory approval. Costs incurred to produce tab-cel (Ebvallo) prior to regulatory approval, referred to as zero cost inventories, have been recorded as research and development expense in our consolidated statement of operations and comprehensive income (loss). As we sell Ebvallo produced after receiving regulatory approval and in a qualified manufacturing facility, and as revenue is recognized on such Ebvallo sales, cost of commercialization revenue includes direct and indirect costs related to the production of Ebvallo. Such costs include, but are not limited to, CMO costs, quality testing and validation, materials used in production, and an allocation of compensation, benefits and overhead costs associated with employees involved with production.

In 2025 and 2024, cost of commercialization revenue included adjustments of $5.1 million and $18.5 million, respectively, to write-off inventories and to reflect them at the lower of cost or net realizable value.

Research and Development Expense

Research and development expense consists of costs incurred in performing research and development activities, including compensation and benefits for research and development employees; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical and preclinical studies; expense incurred under agreements with contract manufacturing organizations related to acquiring and manufacturing clinical study materials and other supplies to support the manufacture of our product candidates; payments under licensing and research and development agreements; other outside services and consulting costs, and facilities, information technology and overhead expenses. Research and development costs are expensed as incurred.

Stock-Based Compensation Expense

We account for stock-based compensation expense, including the expense of restricted common stock awards, grants of restricted stock units (RSUs), and stock options that may be settled in shares of our common stock, based on the fair values of the equity instruments issued. The fair value is determined on the measurement date, which is generally the date of grant. The fair value of our RSUs is measured at the closing market price of our common stock on the measurement date. The fair value for our stock option awards is determined at the grant date using the Black-Scholes valuation model.

In determining the fair value of stock option awards granted, we use the Black-Scholes valuation model and assumptions include:

Expected term – We derived the expected term using the “simplified” method (the expected term is determined as the average of the time-to-vesting and the contractual life of the options), as we have limited historical information to develop expectations about future exercise patterns and post vesting employment termination behavior.

Expected volatility – Expected volatility is estimated based on the historical volatility of Atara’s stock price historical volatility for the same period of time as the expected term of the associated award.

Expected dividend – We have not historically declared or paid dividends to our stockholders and have no plans to pay dividends; therefore, we assumed an expected dividend yield of 0%.

Risk-free interest rate – The risk-free interest rate is based on the yield on U.S. Treasury securities with the expected term of the associated award.

For awards with performance-based vesting criteria, we assess the probability of the achievement of the performance conditions at the end of each reporting period and begin to recognize the share-based compensation costs when it becomes probable that the performance conditions will be met. For awards that are subject to both service and performance conditions, no expense is recognized until it is probable that performance conditions will be met. Stock-based compensation expense for awards with time-based vesting criteria is recognized as expense on a straight-line basis over the requisite service period. Stock-based compensation expense for awards with performance and other vesting criteria is recognized as expense under an accelerated graded vesting model. We account for forfeitures of stock-based awards as they occur.

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Defined Contribution Plan

We have one qualified 401(k) plan covering all eligible employees. Under the plan, employees may contribute up to the statutory allowable amount for any calendar year. We make matching contributions, equal to 50% of each dollar contributed up to the first 6% of an individual’s eligible earnings, up to the annual IRS maximum. For the years ended December 31, 2025 and 2024 we recorded matching contributions of approximately $0.5 million and $1.2 million, respectively.

Income Taxes

We use the asset and liability method to account for income taxes. We record deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates expected to be in effect when the differences are expected to reverse. Valuation allowances are provided when necessary to reduce net deferred tax assets to the amount that is more likely than not to be realized. Based on the available evidence, we are unable, at this time, to support the determination that it is more likely than not that our deferred tax assets will be utilized in the future. Accordingly, we recorded a full valuation allowance as of December 31, 2025 and 2024. We intend to maintain valuation allowances until sufficient evidence exists to support their reversal.

Tax benefits related to uncertain tax positions are recognized when it is more likely than not that a tax position will be sustained during an audit. Interest and penalties related to unrecognized tax benefits are included within the provision for income tax.

Comprehensive Income (Loss)

Comprehensive income (loss) is defined as a change in equity of a business enterprise during a period resulting from transactions from non-owner sources. Our other comprehensive income (loss) is comprised solely of unrealized gains (losses) on available-for-sale securities and is presented net of taxes. There have not been any material reclassifications from other comprehensive income (loss) to net income (loss) recorded during any period presented.

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 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. We adopted ASU 2023-09 "Income Taxes (Topic 740): Improvements To Income Tax Disclosures" on a prospective basis beginning with the year ended December 31, 2025. (See Note 11 - "Income Taxes").

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 fiscal years beginning after December 15, 2026, and for interim periods beginning after December 15, 2027, with early adoption permitted. The company is currently evaluating the impact of adopting ASU 2024-03.

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:

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Year Ended December 31,

(in thousands)

Weighted average shares outstanding – Basic 12,544 7,488

Effect of dilutive securities 174 —

Weighted average shares outstanding – Diluted 12,718 7,488

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 dates listed that were excluded from the computation of diluted net earnings (loss) per common share, as their inclusion would have an antidilutive effect.

As of December 31,

Financial Instruments

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

Total Total Total Total

Amortized Unrealized Unrealized Estimated

As of December 31, 2025: Input Level Cost Gain Loss Fair Value

(in thousands)

Money market funds Level 1 $ 3,528 $ — $ — $ 3,528

Total available-for-sale securities 8,220 1 — 8,221

Less: amounts classified as cash equivalents (8,220 ) (1 ) — (8,221 )

Amounts classified as short-term investments $ — $ — $ — $ —

Total Total Total Total

Amortized Unrealized Unrealized Estimated

As of December 31, 2024: Input Level Cost Gain Loss Fair Value

(in thousands)

Less: amounts classified as cash equivalents (23,708 ) (2 ) — (23,710 )

Amounts classified as short-term investments $ 17,460 $ 6 $ — $ 17,466

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

Amortized Estimated Amortized Estimated

Cost Fair Value Cost Fair Value

(in thousands) (in thousands)

Maturing in one to five years — — — —

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 December 31, 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 years ended December 31, 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 consolidated balance sheet. As of December 31, 2025 and 2024, accrued interest receivable was immaterial. Our accounting policy is to not measure an allowance for credit losses for accrued interest receivables and to write-off any uncollectible accrued interest receivable as a reversal of interest income in a timely manner, which we consider to be in the period in which we determine the accrued interest will not be collected by us. We have not written off any accrued interest receivables for the years ended December 31, 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 consolidated balance sheets that sum to the total of the same such amounts in the consolidated statement of cash flows:

December 31, December 31,

(in thousands)

Restricted cash – short-term — 146

Total cash, cash equivalents and restricted cash $ 8,482 $ 25,176

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.

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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.

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. 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. In December 2025, we further amended the A&R Commercialization Agreement to, among other things, mitigate the impact of the cost of rebuilding commercial inventory in the United States. We agreed to reduce the milestone payment due upon BLA approval of tab-cel to $31 million in exchange for the right to receive an additional $15 million potential milestone payment upon achieving a certain commercial milestone. Under the terms of the A&R Commercialization Agreement, as amended by the A&R Commercialization Agreement Amendment, we are entitled to receive an aggregate of up to $308.0 million in remaining milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Initial Territory, and an aggregate of up to $556.0 million in additional potential milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory, including up to $31.0 million in potential regulatory milestones in connection with the approval by the FDA of a BLA for tab-cel.We are also eligible to receive significant double-digit tiered royalties as a percentage of net sales of tab-cel (Ebvallo) in the 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 in each such country. Royalty

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payments may be reduced in certain specified customary circumstances. Royalties and milestones from the commercialization of Ebvallo in the Initial Territory remain subject to the HCRx Agreement.

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, which consist 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 $308 million of potential regulatory and commercial milestone payments that we are eligible to receive associated with the Initial Territory 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 was 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 $556 million of potential regulatory and commercial milestone payments that we are eligible to receive associated with the Additional Territory 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.

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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 was able to utilize the inventory it had purchased from us on its own.

ATRA US Equity

ATRA · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

Item 8. Financial Statements and Supplementary Data

ATRA US Equity☆

ATRA · 10-K · period ended 2025-12-31

Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures about Market Risk

Item 8. Financial Statements and Supplementary Data

ATRA US Equity