UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-36548 ATARA BIOTHERAPEUTICS, INC. (Exact name of Registrant as specified in its Charter) Delaware 46-0920988 (State or other jurisdic ...

Atara Biotherapeutics Announces Fourth Quarter and Full Year 2025 Financial Results and Operational Progress Mar 16, 2026 4:05 PM Eastern Daylight Time Atara Biotherapeutics Announces Fourth Quarter and Full Year 2025 Financial Results and Operational Progress Share Atara delivers significant operational efficiencies and extends cash runway through year-end 2026 A Type A meeting has been scheduled between Pierre Fabre Pharmaceuticals and the FDA THOUSAND OAKS, Calif.--(BUSINESS WIRE)-- Atara Biotherapeutics ...

Core Viewpoint - Atara Biotherapeutics, Inc. is advancing its T-cell immunotherapy platform in collaboration with Pierre Fabre Pharmaceuticals, which has submitted a request to the FDA for a Type A meeting regarding their joint efforts [1] Company Summary - Atara Biotherapeutics is focused on developing therapies for cancer and autoimmune diseases using its allogeneic Epstein-Barr virus (EBV) T-cell platform [1] - The partnership with Pierre Fabre Pharmaceuticals aims to leverage their combined expertise to enhance the development of transformative therapies [1] Industry Context - The submission of a Type A meeting request to the FDA indicates a proactive approach in navigating regulatory pathways, which is crucial for the advancement of innovative therapies in the biopharmaceutical industry [1]

Core Viewpoint - Pomerantz LLP is investigating claims of potential securities fraud or unlawful business practices involving Atara Biotherapeutics, Inc. following a significant stock price drop after the FDA's Complete Response Letter regarding its drug EBVALLO™ [1][3]. Group 1: Company Overview - Atara Biotherapeutics, Inc. is a biopharmaceutical company focused on developing therapies for patients with serious diseases [1]. - The company’s stock experienced a dramatic decline of 56.99%, falling $7.79 to close at $5.88 per share on January 12, 2026, after the FDA's announcement [3]. Group 2: FDA Response - On January 12, 2026, Atara announced that the FDA issued a Complete Response Letter (CRL) for its EBVALLO™ Biologics License Application (BLA) for treating Epstein-Barr virus positive post-transplant lymphoproliferative disease [3]. - The CRL indicated that the FDA could not approve the BLA in its current form, citing inadequacies in the evidence of effectiveness from the single arm ALLELE trial [3].

Core Viewpoint - Pomerantz LLP is investigating claims of potential securities fraud or unlawful business practices involving Atara Biotherapeutics, following a significant stock price drop after the FDA's Complete Response Letter regarding its EBVALLO™ treatment [1][3]. Group 1: Company Overview - Atara Biotherapeutics, Inc. (NASDAQ: ATRA) is under investigation for possible securities fraud or other unlawful business practices [1]. - The company recently faced a setback when the FDA issued a Complete Response Letter for its EBVALLO™ Biologics License Application, indicating that the application could not be approved in its current form [3]. Group 2: FDA Response and Impact - The FDA's Complete Response Letter stated that the single-arm ALLELE trial, previously deemed adequate for the BLA filing, is now considered insufficient for demonstrating effectiveness for accelerated approval [3]. - Following the FDA's announcement, Atara's stock price plummeted by $7.79 per share, a decrease of 56.99%, closing at $5.88 per share on January 12, 2026 [3].

Core Insights - Several companies have experienced significant price changes due to various underlying factors, including corporate developments, industry shifts, and broader economic conditions [5] Company-Specific Summaries - Atara Biotherapeutics, Inc. (Nasdaq: ATRA) saw its price drop by approximately 54% to $6.28, down from a year-high of $19.14, potentially due to concerns over trial results, regulatory hurdles, or financial sustainability, particularly after receiving a Complete Response Letter (CRL) from the FDA regarding its Biologics License Application for EBVALLO™ [1][6] - Nuvation Bio Inc. (NUVB-WT) experienced a nearly 47% decrease in price to $0.09, reflecting investor skepticism possibly due to challenges in its oncology-focused pipeline and a lack of recent positive news [2][6] - Lyra Therapeutics, Inc. (LYRA) witnessed a 46% drop in its price to $2.04, attributed to concerns over the clinical progress of its key product candidates or potential financial constraints impacting its research and development activities [3] - Mingteng International Corporation Inc. (Nasdaq: MTEN) saw its price fall by over 41% to $0.077, possibly related to operational challenges, market competition, or broader economic factors affecting the manufacturing sector, despite announcing an expansion of its strategic collaboration in the new energy vehicle sector [4]

Financial Position - As of December 31, 2025, Atara Biotherapeutics reported its cash, cash equivalents, and short-term investments, although specific figures were not disclosed in the preliminary estimate[6] Regulatory Challenges - The U.S. FDA issued a Complete Response Letter for the EBVALLO™ (tabelecleucel) Biologics License Application, indicating regulatory challenges for the product[7]

Core Insights - Atara Biotherapeutics is focusing on allogeneic CAR T-cell therapy, which is a novel approach in engineered cell therapies [1] Company Analysis - The company has shown potential in the biotech sector, particularly in the development of innovative therapies [1] - The analyst has a background in biochemistry and extensive experience in analyzing clinical trials and biotech companies, indicating a strong foundation for evaluating Atara's prospects [1] Industry Context - The article emphasizes the importance of understanding the science behind biotech investments, highlighting the complexities and potential pitfalls in the industry [1]

Regulatory Approvals and Commercialization - Atara Biotherapeutics received marketing authorization approval for its lead program, Tab-cel (Ebvallo), for commercial sale in the European Economic Area, the UK, and Switzerland[148]. - Tab-cel, under the name Ebvallo, is approved for commercial sale in the EEA, UK, and Switzerland, with ongoing Phase 3 trials in the U.S. for EBV+ PTLD patients[165]. - The Prescription Drug User Fee Act target action date for the tab-cel BLA is set for January 10, 2026[169]. Financial Performance - Commercialization revenue for the nine months ended September 30, 2025, was $119.2 million, a decrease of $36.7 million compared to $96.2 million in the same period of 2024[185]. - The cost of commercialization revenue for the nine months ended September 30, 2025, was $21.1 million, a decrease of $7.5 million from $14.2 million in the same period of 2024[186]. - Research and development expenses for the nine months ended September 30, 2025, totaled $37.7 million, a decrease of $85.1 million compared to $122.8 million in the same period of 2024[187]. - The accumulated deficit as of September 30, 2025, was $2.0 billion, with net losses of $72.7 million for the nine months ended September 30, 2024[173]. - General and administrative expenses decreased to $4.0 million in Q3 2025 from $10.4 million in Q3 2024, a reduction of 61%[190]. - Interest income fell to $0.2 million in Q3 2025 from $0.5 million in Q3 2024, a decrease of 60%[191]. - Total cash, cash equivalents, and short-term investments decreased to $13.7 million as of September 30, 2025, down from $42.5 million as of December 31, 2024, a decline of 68.6%[199]. - Cash and cash equivalents as of September 30, 2025, were $5.7 million, down from $25.0 million as of December 31, 2024, a decrease of 77.2%[199]. - Net cash used in operating activities was $45.2 million for the nine months ended September 30, 2025, compared to $44.2 million in the same period of 2024, an increase of 2.3%[201]. - Net cash provided by financing activities was $16.1 million in the nine months ended September 30, 2025, down from $59.6 million in the same period of 2024, a decrease of 73%[200]. - As of September 30, 2025, the company had $87.2 million of common stock remaining to be sold under the 2023 ATM Facility[195]. - The company expects a $40 million milestone payment from Pierre Fabre upon approval of the tab-cel BLA, which will provide significant cash runway[204]. - The company incurred losses and negative cash flows from operations since inception and anticipates needing additional capital to fund operations[197]. - The company may need substantial additional funding to complete the regulatory approval process for tab-cel in the US[207]. Workforce and Restructuring - The company executed workforce reductions of approximately 30% in November 2023, resulting in restructuring charges of $6.7 million[156]. - A further workforce reduction of approximately 50% was announced in January 2025, with total severance and related benefits recognized at approximately $7.1 million[158]. Strategic Alternatives and Collaborations - The company has engaged a financial advisor to assess strategic alternatives, including potential acquisitions or mergers, following the pause in CAR-T asset development[164]. - The company has entered into research collaborations with leading academic institutions to acquire rights to novel technologies and programs[152]. Program Developments and Changes - The company announced a pause in the development of its allogeneic CAR T cell programs, including ATA3219 and ATA3431, and has completed nearly all wind-down activities for these programs[148]. - The FDA lifted the clinical hold on the ATA3219 program in May 2025 after compliance issues were addressed[166]. - The company returned rights to the ATA188 and EBV Vaccine programs to QIMR in May 2025, and discontinued other programs[168]. - Manufacturing responsibilities for tab-cel were transferred to Pierre Fabre as of March 31, 2025, following an amendment to the A&R Commercialization Agreement[170]. - The Fujifilm Master Services and Supply Agreement was assigned to Pierre Fabre as part of the transition of manufacturing responsibility for Tab-cel[153]. Risks and Future Considerations - The company anticipates no material impact from the recent U.S. corporate tax legislation changes on its business operations[162]. - No material changes to interest rate risk, market risk, and foreign currency exchange rate risk disclosures during the nine months ended September 30, 2025[212]. - The company is subject to the timing of proceeds from the A&R Commercialization Agreement and the HCRx Agreement[212]. - Future commercialization, collaboration, licensing, and partnering arrangements may impact financial performance[212]. - The company may incur costs related to licensing, filing, prosecution, maintenance, defense, and enforcement of patents[212]. - The extent of in-licensing or acquisition of other products and technologies will influence growth strategies[212]. - Timing of qualification for partner's CMOs' manufacturing facilities is critical for operational success[212].

Financial Performance - Atara reported total revenues of $3.5 million for Q3 2025, a decrease of 91.3% compared to $40.2 million in Q3 2024[7] - The net loss for Q3 2025 was $4.3 million, or $0.32 per share, significantly improved from a net loss of $21.9 million, or $2.93 per share, in Q3 2024[7] - Total costs and operating expenses for Q3 2025 were $7.0 million, down from $61.9 million in Q3 2024, marking a decrease of 88.7%[15] Cash and Investments - Cash, cash equivalents, and short-term investments totaled $13.7 million as of September 30, 2025, down from $22.3 million as of June 30, 2025[7] - Atara's accumulated deficit as of September 30, 2025, was $2.02 billion, compared to $2.05 billion at the end of 2024[13] Research and Development - Research and development expenses decreased to $2.9 million in Q3 2025 from $43.9 million in Q3 2024, reflecting a year-over-year reduction of 93.4%[7] - The company anticipates a full-year 2025 operating expense reduction of at least 60% compared to 2024 due to the transition of tab-cel activities to Pierre Fabre[11] Milestones and Future Expectations - Atara expects to receive a $40 million milestone payment from Pierre Fabre Laboratories contingent upon FDA approval of the tab-cel BLA[4] - The FDA has set a PDUFA target action date of January 10, 2026, for the tab-cel BLA, which has been granted Priority Review[3] - The company completed the transfer of substantially all tab-cel activities to Pierre Fabre Laboratories in October 2025[5]