Atara Biotherapeutics Announces Early Clinical Data from the Ongoing Tab-cel® Multicenter European Expanded Access Program (EAP) at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting and Provides Update on Regulatory Progress of Tab-cel EMA

SOUTH SAN FRANCISCO, Calif.–(BUSINESS WIRE)–Atara Biotherapeutics, Inc. (Nasdaq: ATRA), a leader in T-cell immunotherapy, leveraging its novel allogeneic EBV T-cell platform to develop transformative therapies for patients with cancer and autoimmune diseases. -immunes, today announced regulatory progress from the EMA and tabelecleucel (tab-cel^®) clinical results. Data are from the Expanded Access Program (EAP) multicenter study in Europe for patients with relapsed or refractory (r/r) post-transplant lymphoproliferative disease (EBV+PTLD) due to Epstein virus -Barr following solid organ transplant (SOT) or hematopoietic cell transplant (HCT) and will be the subject of a poster presentation at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting which will be held June 3-7, 2022 in Chicago, IL.

In the ongoing EAP, 22 patients from leading European centers consented to this observational study, of which 16 patients presented with EBV+ PTLD and six with EBV+ non-PTLD between July 2020 and November 2021. The main objective of the This study is to describe the demographics and disease characteristics of patients with EBV+ disease treated with tab-cel as part of EAP. The secondary objectives are to describe the tab-cel dosing regimen, assess clinically relevant treatment outcomes, and describe the safety of tab-cel in patients with EBV+ disease treated under EAP.

Of the 16 EBV+ PTLD patients, 15 received at least one dose of tab-cel. Overall, nine out of 15 (60%) patients treated with tab-cel achieved a physician-assessed response, with six complete responses (CR) and three partial responses (PR). Of the nine responses, eight were observed after the first round of tab-cel treatment.

The safety results were consistent with previously published data. All treatment-related events were assessed as unrelated to tab-cel by the treating physician and were consistent with the patients’ underlying illnesses. Further details on basic demographics and disease characteristics, as well as additional safety data, including details on tab-cel exposure, will be presented at the conference.

“We are delighted to share the latest data from our EAP in Europe demonstrating clinically meaningful results for patients with EBV+ PTLD, a rare and aggressive disease with no approved treatment options, consistent with the favorable safety and efficacy profile previously reported studies, including the pivotal Phase 3 ALLELE study,” said Jakob Dupont, MD, Head of Global Research and Development, Atara. “Furthermore, we now welcome the completion of our pre-approval inspections as a key milestone on our road to obtaining approval in the EU.”

Additionally, Atara announced the completion of the six pre-approval inspections required to support the marketing authorization application for tab-cel in Europe, with the required Good Manufacturing Practices (GMP) certificates of compliance. to support the planned filing by July. Combined with the recent 120-day critical appraisal report, in which the European Medicines Agency (EMA) considered comparability data between clinical and commercially manufactured versions to be sufficient to demonstrate comparability, Atara continues to expect approval from the European Commission in the fourth quarter of 2022.

Details of the ASCO presentation:

• Title: Demographics and treatment outcomes in patients with EBV+ PTLD treated with ready-to-use EBV-specific (tabelecleucel) CTLs in an ongoing expanded access program in Europe: initial analyses.
• Speaker: Ralf Trappe, MD, DIAKO Evangelisches Diakonie-Krankenhaus Bremen, Bremen, Germany
• Date and hour : Saturday, June 4, 2022, 8 a.m. to 11 a.m. CDT/6 a.m. to 9 a.m. PDT
• Abstract number: 7530
• Poster number: 184
• Session: Hematological malignancies—lymphoma and chronic lymphocytic leukemia
• Location: McCormick Place Convention Center Chicago, Hall A

About Atara Biotherapeutics, Inc.

Atara Biotherapeutics, Inc. (@Atarabio) is a pioneer in T-cell immunotherapy leveraging its novel allogeneic EBV T-cell platform to develop transformative therapies for patients with serious diseases, including solid tumors, hematological cancers and autoimmune diseases . With our flagship program in Phase 3 clinical development and currently under review to support registration in Europe, Atara is the most advanced allogeneic T-cell immunotherapy company and intends to rapidly deliver ready-to-use treatments employment to patients with unmet medical needs. Our platform exploits the unique biology of EBV T cells and has the ability to treat a wide range of EBV-associated diseases, or other serious illnesses through the incorporation of CARs (chimeric antigen receptors) or TCRs (T cell receptors) altered. Atara applies this unique platform, which does not require TCR or HLA gene editing, to create a robust pipeline including: tab-cel^® (tabelecleucel) in phase 3 development for Epstein-Barr virus-induced post-transplant lymphoproliferative disease (EBV+ PTLD); ATA188, a T-cell immunotherapy targeting EBV antigens as a potential treatment for multiple sclerosis; and multiple next-generation chimeric antigen receptor (CAR T) T-cell immunotherapies for solid tumors and hematological malignancies. Improving the lives of patients is our mission and we will never stop working to bring transformative therapies to those in need. Atara is headquartered in South San Francisco and our state-of-the-art research, development and manufacturing facilities are based in Thousand Oaks, California. For more company information, please visit atarabio.com and follow us on Twitter and LinkedIn.

Forward-looking statements

This press release contains or may imply “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. For example, forward-looking statements include statements regarding: potential benefits, safety and efficacy of tab-cel^®; the timing and progression of tab-cel^®, including (i) EAP data and analytics; (ii) the timetable and the result of the marketing authorization for tab-cel, (iii) the timetable for the review by the EMA of the marketing authorization for tab-cel; and (iv) Atara’s ability to successfully advance the development of tab-cel^®. Because these statements address future events and are based on Atara’s current expectations, they are subject to various risks and uncertainties, and Atara’s actual results, performance or achievements could differ materially from those described or implied. by the statements in this press release. These forward-looking statements are subject to risks and uncertainties, including, without limitation, the risks and uncertainties associated with the lengthy and costly pharmaceutical product development process and the uncertainty of clinical success; the ongoing COVID-19 pandemic, which may significantly impact (i) our business, research, clinical development plans and operations, including our operations in southern San Francisco and southern California and at our clinical trial sites, as well as the activities or operations of our third party manufacturer, our contract research organizations or other third parties with whom we do business, (ii) our ability to access capital and ( (iii) the value of our common stock; the sufficiency of Atara’s liquidity and the need for additional capital; and other risks and uncertainties affecting Atara and its development programs, including those discussed in Atara’s filings with the Securities and Exchange Commission (SEC), including in the “Risk Factors” and “Discussion and Management’s Discussion and Analysis of Financial Condition and Results of Operations” in the latest periodic reports filed by the Company on Forms 10-K and 10-Q and subsequent filings and in the documents incorporated by reference therein. Except as required by law, Atara disclaims any intention or obligation to update or revise any forward-looking statements, which speak only as of the date hereof, whether as a result of new information, future events or circumstances or otherwise.