Atara Biotherapeutics' Collaborating Investigators' Abstract on T-Cell Therapy for EBV Lymphoma to be Presented at a Clinical Trials Plenary Session at the American Association for Cancer Research Annual Meeting 2015 is Now Available

SOUTH SAN FRANCISCO, Calif., April 19, 2015 (GLOBE NEWSWIRE) -- Atara Biotherapeutics, Inc. (Nasdaq:ATRA), today announced that the abstract on cytotoxic T lymphocytes activated against Epstein-Barr Virus (EBV-CTL) that will be presented by its collaborating investigators at Memorial Sloan Kettering Cancer Center (MSK) at a Clinical Trials Plenary Session at the American Association for Cancer Research Annual Meeting (AACR) 2015 is now available. Clinical data on both the safety and efficacy of EBV-CTL in the treatment of patients with rituximab-refractory, EBV-associated lymphoproliferative disease (EBV-LPD) after allogeneic hematopoietic cell transplantation (HCT) will be presented. EBV-LPD is a serious malignancy with an unmet medical need that occurs after HCT and in other patients with immune deficiencies. The U.S. Food and Drug Administration (FDA) recently granted breakthrough therapy designation for EBV-CTL based on the data from the two studies. The AACR annual meeting is being held in Philadelphia, Pennsylvania from April 18th to April 22nd, 2015.  

Details of the presentation are as follows:

Date & Time: Sunday, April 19, 2015, 2:25 PM 
Title:  Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (EBV-CTLs) for treatment of rituximab-refractory EBV-associated lymphoproliferative disorder (EBV-LPD) 
Publication Number: CT107 
Session Title: Promising Trials in Immunotherapy 
Session Type: Clinical Trials Plenary Session 
Location: Terrace Ballroom I (400 Level), Pennsylvania Convention Center

The abstract is now available on the AACR website at http://www.aacr.org/Meetings/Pages/MeetingDetail.aspx?EventItemID=25&DetailItemID=154.

Under Atara's exclusive option agreement with MSK, Atara has the right to license the exclusive, worldwide rights to three clinical stage T-cell programs, including EBV-CTL.

About EBV-CTL

T-cells are a critical component of the body's immune system and can be harnessed to counteract viral infections and some cancers. By focusing the T-cells on specific proteins involved in cancers and infections, the power of the immune system can be employed to combat these diseases. EBV-CTL utilize a technology in which T-cells are collected from the blood of third-party donors and then exposed to EBV antigens. The resulting activated T-cells are then expanded, characterized, and stored for future therapeutic use in an appropriate partially human leukocyte antigen, or HLA, matched patient, providing an "off-the-shelf", allogeneic, cellular therapeutic option for patients.  In the context of EBV-LPD, the EBV-CTL find the cancer cells expressing EBV and kill them. EBV-CTL are currently being studied in two ongoing Phase 2 clinical trials (NCT00002663 and NCT01498484).

About Atara Biotherapeutics, Inc.

Atara Biotherapeutics, Inc. is a biopharmaceutical company focused on developing innovative therapies for patients with debilitating diseases. Atara's lead programs target myostatin and activin, members of the TGF-beta family of proteins that have demonstrated the potential to have therapeutic benefit in a number of clinical indications. In September 2014, Atara Biotherapeutics entered into an exclusive option agreement with MSK, under which it has the right to license (pursuant to a negotiated form of license agreement) the exclusive, worldwide rights to three clinical stage T-cell programs, including EBV-CTL, as well as other T-cell programs that are discovered or developed by MSK pursuant to sponsored research funded by the company. 

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. Because such statements deal with future events and are based on Atara's current expectations, they are subject to various risks and uncertainties and actual results, performance or achievements of Atara could differ materially from those described in or implied by the statements in this press release. For example, forward-looking statements include statements regarding the clinical development of product candidates and Atara's collaboration with MSK. These forward-looking statements are subject to other risks and uncertainties, including those discussed under the heading "Risk Factors" in Atara's annual report on Form 10-K for the year ended December 31, 2014 and subsequent filings with the Securities and Exchange Commission. Except as otherwise 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.

CONTACT: INVESTOR CONTACT:
         Tina Gullotta, Atara Biotherapeutics, Inc.
         650-741-1613
         tgullotta@atarabio.com

         MEDIA CONTACT:
         Susan Heins, Pure Communications, Inc.
         864-286-9597
         susan@purecommunicationsinc.com

Released April 19, 2015