Atara Bio Announces Closing of Underwritten Offering of Common Stock and Full Exercise of Underwriters' Option to Purchase Additional Shares

SOUTH SAN FRANCISCO, Calif., July 15, 2015 (GLOBE NEWSWIRE) -- Atara Biotherapeutics, Inc. (Nasdaq:ATRA), a biopharmaceutical company with a focus on developing innovative therapies for patients with debilitating diseases, today announced the closing of its underwritten public offering of 3,980,768 shares of its common stock at a public offering price of $52.00 per share, which included 519,230 shares sold pursuant to the full exercise by the underwriters of their option to purchase additional shares.

Goldman, Sachs & Co. and Citigroup Global Markets Inc. acted as joint book-running managers for the offering. William Blair & Company, L.L.C., Canaccord Genuity Inc. and JMP Securities LLC acted as co-managers.

A registration statement relating to these securities was declared effective by the U.S. Securities and Exchange Commission on July 9, 2015.

The offering was made only by means of a written prospectus forming part of the effective registration statement. Copies of the final prospectus relating to the offering was filed with the Securities and Exchange Commission and may be obtained from Goldman, Sachs & Co., Attention: Prospectus Department, 200 West Street, New York, New York 10282, by telephone at (866) 471-2526, by facsimile at (212) 902-9316, or by email at prospectus-ny@ny.email.gs.com, or from Citigroup Global Markets Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY, 11717, by email at prospectus@citi.com or by phone at (800) 831-9146.

This press release shall not constitute an offer to sell or a solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About Atara Biotherapeutics, Inc.

Atara Biotherapeutics, Inc. is a biopharmaceutical company focused on developing innovative therapies for patients with debilitating diseases. Atara Bio's programs include molecularly targeted product candidates and T-cell product candidates. Molecularly targeted product candidates include PINTA 745, STM 434 and ATA 842, members of the TGF-beta family of proteins that target myostatin and activin, and have demonstrated the potential to have therapeutic benefit in a number of clinical indications. T-cell product candidates include EBV-CTL, CMV-CTL and WT1-CTL.

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

Released July 15, 2015