Atara Biotherapeutics Doses First Patient in Phase 1 Clinical Study of STM 434, an Activin Inhibitor

BRISBANE, Calif., Oct. 22, 2014 (GLOBE NEWSWIRE) -- Atara Biotherapeutics, Inc. (Nasdaq:ATRA), a drug development company with a focus on innovative therapies for patients with debilitating diseases, today announced dosing of the first patient in its Phase 1 clinical study of STM 434, an Activin inhibitor, in patients with ovarian cancer and other solid tumors. The study is designed to assess the safety, tolerability and efficacy of STM 434 as a single therapy and in combination with liposomal doxorubicin. Further information regarding the clinical study can be found at http://www.clinicaltrials.gov/ct2/show/NCT02262455.

About Atara

Atara Biotherapeutics, Inc. is a drug development company focusing on innovative therapies for patients with debilitating diseases. The company's lead programs are focused on 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. For more information, visit http://www.atarabio.com. 

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 design of the STM 434 Phase 1 clinical study and target patient population. These forward-looking statements are subject to other risks and uncertainties, including those discussed under the heading "Risk Factors" in Atara Biotherapeutics, Inc.'s registration statement on Form S-1 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: MEDIA CONTACT: Tina Gullotta, tgullotta@atarabio.com. 415-287-2427
         INVESTOR CONTACT: Tina Gullotta, tgullotta@atarabio.com. 415-287-2427

Released October 22, 2014