Atara Biotherapeutics Announces Presentations Highlighting Tab-cel® and Mesothelin-Targeted CAR T Clinical Results at American Society of Clinical Oncology (ASCO) Annual Meeting

SOUTH SAN FRANCISCO, Calif., May 15, 2019 (GLOBE NEWSWIRE) -- Atara Biotherapeutics, Inc. (Nasdaq: ATRA), a leading off-the-shelf, allogeneic T-cell immunotherapy company developing novel treatments for patients with cancer, autoimmune and viral diseases, today announced three presentations at the upcoming ASCO 2019 Annual Meeting, which will take place in Chicago, Illinois from May 31 to June 4, 2019.

An oral session will feature a presentation by Atara’s collaborators at Memorial Sloan Kettering Cancer Center (MSK) with additional Phase 1 clinical results for their regionally delivered autologous mesothelin-targeted chimeric antigen receptor T-cell (CAR T) immunotherapy for patients with malignant pleural mesothelioma.

Atara will also present two studies highlighting tab-cel^® (tabelecleucel), the Company’s product candidate in Phase 3 development for patients with Epstein-Barr virus-associated post-transplant lymphoproliferative disorder (EBV+ PTLD) as well as in earlier stage development for other EBV-associated hematologic malignancies and solid tumors.

One study describes a potential biomarker for clinical response to tab-cel^® in patients with Epstein-Barr virus-associated diseases. A second presentation focuses on the design of Atara’s ongoing Phase 1b/2 clinical study design of tab-cel^® in combination with KEYTRUDA® (pembrolizumab) for patients with platinum-resistant or recurrent EBV-associated nasopharyngeal carcinoma (NPC).

Details of the presentations are as follows:

Abstract 2511: Regional delivery of mesothelin-targeted CAR T cells for pleural cancers: Safety and preliminary efficacy in combination with anti-PD-1 agent

Oral Presentation Date and Time: Tuesday, June 4, 2019, 8:36 a.m. - 8:48 a.m. CDT

Session Title: The Who, What, and Where of CAR T

Location: S406, McCormick Place, South Building, Chicago, IL

Authors: Prasad S. Adusumilli, Marjorie G Zauderer, Valerie W Rusch, Roisin E O’Cearbhaill, Amy Zhu, Daniel Ngai, Erin McGee, Navin Chintala, John Messinger, Waseem Cheema, Elizabeth F Halton, Claudia R Diamonte, John Pineda, Alain Vincent, Shanu Modi, Steve Solomon, David R Jones, Renier J Brentjens, Isabelle C Riviere, Michel W Sadelain

Affiliations: Memorial Sloan Kettering Cancer Center

Summary: Atara’s collaborators at Memorial Sloan Kettering Cancer Center (MSK) reported positive Phase 1 clinical results for their mesothelin-targeted CAR T immunotherapy for patients with solid tumors at the American Association of Cancer Research (AACR) Annual Meeting 2019. Efficacy and safety results were presented for patients with malignant pleural mesothelioma who may also have received pembrolizumab and lymphodepleting chemotherapy. Following administration of a novel mesothelin-targeted CAR T, MSK investigators observed a 72% response rate in a subset of these patients. Additional results from this study will be presented at the 2019 ASCO Annual Meeting.

Abstract 2532: Correlation of circulating EBV-targeted cytotoxic T lymphocyte precursors (EBV-CTLp) and clinical response following tabelecleucel (tab-cel) infusion in patients with EBV-driven disease

Poster Presentation Date and Time: Saturday, June 1, 2019, 8:00 a.m. - 11:00 a.m. CDT

Session Title: Developmental Immunotherapy and Tumor Immunobiology

Location: Poster Board 176, Hall A, McCormick Place, South Building, Chicago, IL

Authors: Blake T. Aftab, Daniel Munson, Kevin Rasor, Philippe Foubert, Donald Tsai, Wen Kai Weng, Armin Ghobadi, Koen van Besien, Yan Sun, Minoti Hiremath, Willis Navarro, Susan Prockop

Affiliations: Atara Biotherapeutics, University of Pennsylvania, Stanford University, Washington University, Cornell University, Memorial Sloan Kettering Cancer Center

Summary: Circulating EBV-CTLp were measured for patients with EBV-associated diseases following tab-cel^® administration. The study found a correlation between response rate and increases in EBV-CTLp and suggests EBV-CTLp levels could be used as a biomarker for clinical response to tab-cel^® treatment.

Abstract TPS6092: Tabelecleucel in combination with pembrolizumab (Pembro) in platinum-pretreated, recurrent/metastatic Epstein-Barr virus (EBV)-positive nasopharyngeal carcinoma (EBV+NPC)

Poster Presentation Date and Time: Saturday, June 1, 2019, 1:15 p.m. - 4:15 p.m. CDT

Session Title: Head and Neck Cancer

Location: Poster Board 79b, Hall A, McCormick Place, South Building, Chicago, IL

Authors: Lillian L. Siu, Joshua Bauml, Douglas Adkins, A. Dimitrios Colevas, Cesar Perez, Jennifer Choe, Yang Zhang, Wen Shi, Willis Navarro, Missak Haigentz Jr, Guilherme Rabinowits, David Pfister

Affiliations: Princess Margaret Cancer Centre, Perelman School of Medicine, Washington University School of Medicine, Stanford Cancer Institute, Sylvester Comprehensive Cancer Center, Duke University, Atara Biotherapeutics, Morristown Medical Center/Atlantic Health System, Miami Cancer Institute, Memorial Sloan Kettering Cancer Center

Summary: EBV-associated nasopharyngeal carcinoma (EBV+ NPC) is a solid tumor of the head and neck. Tab-cel^® Phase 1 EBV+ NPC clinical study results were encouraging and support ongoing development in combination with KEYTRUDA® (pembrolizumab) for patients with platinum-resistant or recurrent EBV+ NPC.

About Atara Biotherapeutics, Inc.

() is a leading off-the-shelf, allogeneic T-cell immunotherapy company developing novel treatments for patients with cancer, autoimmune and viral diseases. Atara’s technology platform leverages research collaborations with leading academic institutions with the Company’s scientific, clinical, regulatory and manufacturing expertise. Atara’s pipeline includes tab-cel^® (tabelecleucel), which is in Phase 3 development for patients with Epstein-Barr virus-associated post-transplant lymphoproliferative disorder (EBV+ PTLD) as well as in earlier stage development for other EBV-associated hematologic malignancies and solid tumors, including nasopharyngeal carcinoma (NPC); T-cell immunotherapies targeting EBV antigens believed to be important for the potential treatment of multiple sclerosis; and next-generation chimeric antigen receptor T-cell (CAR T) immunotherapies. The company was founded in 2012 and is co-located in South San Francisco and Southern California. Our Southern California hub is anchored by the state-of-the-art Atara T-cell Operations and Manufacturing (ATOM) facility in Thousand Oaks, California. For additional information about the company, please visit .

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. These forward-looking statements are subject to risks and uncertainties, including those discussed in Atara Biotherapeutics' filings with the Securities and Exchange Commission (SEC), including in the “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” sections of the Company’s most recently filed periodic reports on Form 10-K and Form 10-Q and subsequent filings and in the documents incorporated by reference therein. Except as otherwise required by law, Atara Biotherapeutics 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.

INVESTOR & MEDIA CONTACTS:

Investors:

John Craighead, Atara Biotherapeutics

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John Grimaldi, Burns McClellan

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Media:

Nancie Steinberg, Burns McClellan

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