Atara Bio Announces Positive Results From a Phase 2 Clinical Trial of Cytomegalovirus Targeted Cytotoxic T Lymphocytes (CMV-CTL), a Novel Approach to Adoptive Immunotherapy, to Treat Patients With Refractory CMV Disease in the Central Nervous System (CNS)

SOUTH SAN FRANCISCO, Calif., Dec. 06, 2015 (GLOBE NEWSWIRE) -- Atara Biotherapeutics, Inc. (Nasdaq:ATRA), a biopharmaceutical company focused on developing meaningful therapies for patients with unmet medical needs in diseases that have seen limited therapeutic innovation, today announced that its collaborating investigators at Memorial Sloan Kettering Cancer Center (MSK) are reporting additional Phase 2 clinical data for Atara's CMV-CTL product candidate during the 2015 ASH Annual Meeting. The data describe the safety and efficacy of CMV-CTL in the treatment of patients with refractory CMV chorioretinitis and meningoencephalitis.

Dr. Susan Prockop, M.D. and colleagues are reporting the following positive clinical data from an ongoing Phase 2 clinical trial and patients treated under compassionate use:

12 patients were treated with either primary donor derived (n=1) or third-party derived (n=11) CMV-CTL.

Patients had received a range of 3 to 6 prior therapies before treatment with CMV-CTL.

The overall response rate among the 11 evaluable patients was 73% (8/11) including 7 complete responses and 1 partial response.

CMV-CTL infusions were well tolerated and no patient developed de novo graft versus host disease (GvHD) or a flare of prior GvHD.

"These encouraging data demonstrate that CMV-CTL can drive durable responses in patients with refractory CMV disease in the CNS," said Chris Haqq M.D., Ph.D., Chief Medical Officer of Atara Bio. "CMV-CTL crosses the blood-brain barrier and can effectively recognize and target CMV-infected cells. We believe this therapeutic approach offers a novel treatment alternative to standard therapy in patients with resistant or refractory disease."

The ASH 2015 poster presentation, titled "Successful Treatment of Refractory CMV Chorioretinitis and Meningoencephalitis with Adoptive Transfer of Third Party CMVpp65 Specific T-Cell Lines," will take place this evening in Hall A of the Orange County Convention Center, Sunday, December 6, at 6:00 p.m. ET.

About CMV-CTL

Atara Bio's CMV-CTL product candidate targets cells infected with cytomegalovirus, or CMV. In patients with weakened immune systems, CMV infection can result in a range of symptoms including blindness, brain damage, difficulty breathing, or even death, depending on which organ is affected. CMV antigens have been reported to be expressed in tumor cells from seropositive patients with certain malignancies, including glioblastoma, or GBM. CMV-CTL is currently being investigated in two Phase 2 clinical trials for CMV infections that occur in patients who have received an allogeneic stem cell transplant.

About Atara Biotherapeutics, Inc.

Atara Biotherapeutics, Inc. is a biopharmaceutical company developing meaningful therapies for patients with unmet medical needs in diseases that have seen limited therapeutic innovation, with an initial focus on muscle wasting conditions, oncology and viral-associated 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. These product candidates target myostatin and activin, members of the TGF-beta family of proteins, and have demonstrated the potential to have therapeutic benefit in a number of clinical indications. The T-cell product candidates include EBV-CTL, CMV-CTL and WT1-CTL.