ATRA Atara Biotherapeutics Inc

Five of eight progressive MS patients who received the full course of autologous ATA190 experienced clinical improvements

Atara Biotherapeutics, Inc. (Nasdaq:ATRA), a leading T-cell immunotherapy company developing novel treatments for patients with cancer and autoimmune diseases, announced today that two abstracts by the Company’s collaborating investigators were published and will be presented at the upcoming MSParis 2017 Congress, the 7th Joint Meeting of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS). The Congress will be held October 25-28, 2017, at the Palais des Congrès de Paris, in Paris, France.

In August, Atara announced that the Company’s collaborating investigators at the QIMR Berghofer Medical Research Institute and The University of Queensland completed enrollment of 10 progressive MS patients in a Phase 1 study of autologous ATA190 (formerly known as autologous ATA188), an Epstein-Barr Virus (EBV) specific T-cell immunotherapy.

Updated, interim results from the Phase 1 study at the time of abstract submission in May 2017 showed that five of eight progressive MS patients who received the full course of autologous ATA190 experienced clinical improvements. Clinical improvements correlated with autologous ATA190’s reactivity against target EBV antigens (EBV reactivity) attained through the manufacturing process. No significant adverse events have been observed in the study. Further results for all 10 patients in the ongoing Phase 1 study following the May abstract submission will be presented at the MSParis 2017 Congress.

Atara and its collaborating investigators at Stanford Medicine will also present new data that demonstrate the presence of increased numbers of EBV-infected antigen presenting B-cells and antibody producing plasma cells in the brains of MS patients and suggest that EBV plays an important role in MS disease pathogenesis.

The abstracts are available in the Scientific Programme section of the MSParis 2017 Congress website and details for the poster presentations are as follows:

Abstract Title: Safety and clinical improvement in a phase 1 trial of autologous Epstein-Barr virus-specific T cell therapy in patients with progressive multiple sclerosisSession Title: Poster Session 1Presentation Date & Time: Thursday, October 26, 2017; 15:30 CESTLead Authors: Michael Pender, M.D., and Professor Rajiv Khanna

Abstract Title: Molecular signature of Epstein-Barr virus infection in multiple sclerosis brain lesionsSession Title: Poster Session 2Presentation Date & Time: Friday, October 27, 2017; 15:30 CESTLead Authors: May Han, M.D., and Lawrence Steinman, M.D.

About Progressive Multiple SclerosisMS is a chronic neurological autoimmune disease that affects an estimated 2.3 million people around the world. Progressive MS (PMS) is a severe form of the disease with few therapeutic options. PMS comprises two conditions, both characterized by persistent progression and worsening of MS symptoms and physical disability over time. Primary Progressive MS (PPMS) occurs when continuous progressive disease is present at diagnosis and occurs in approximately 15% of newly diagnosed cases.  Secondary Progressive MS (SPMS) initially begins as RRMS and develops into a progressive form. Up to 80% of people with RRMS will eventually develop SPMS. There is substantial unmet medical need for new and effective therapies for patients with PPMS and SPMS. Most treatment options that work well in reducing flares in RRMS have not been shown to be effective in slowing or reversing disability in PMS.

About allogeneic ATA188 and autologous ATA190Epstein-Barr Virus (EBV) is associated with a wide range of hematologic malignancies and solid tumors, as well as certain autoimmune conditions such as multiple sclerosis (MS). T-cells are a critical component of the body's immune system and can selectively target specific EBV antigens believed to be important for the potential treatment of MS. Allogeneic ATA188 and autologous ATA190, the Company’s next generation T-cell immunotherapies developed by Professor Rajiv Khanna at QIMR Berghofer, have the potential to precisely recognize and eliminate EBV-infected B-cells and plasma cells in the central nervous system that may catalyze autoimmune responses and MS pathophysiology. Professor Michael Pender from The University of Queensland presented the results of the first autologous ATA190 study, which was partially funded by MS Australia, MS Queensland and Perpetual Foundation, at the American Academy of Neurology (AAN) meeting in April 2017. This study tested adoptive immunotherapy in patients with MS and showed that autologous ATA190, led to encouraging clinical improvements in MS symptoms that correlated with autologous ATA190’s reactivity against target EBV antigens (EBV reactivity). In addition to the ongoing Phase 1 clinical study of autologous ATA190 in progressive forms of MS, a Phase 1 allogeneic ATA188 clinical study is expected to begin in the fourth quarter of 2017.

About Atara Biotherapeutics, Inc. Atara Biotherapeutics, Inc. (@Atarabio) is a leading T-cell immunotherapy company developing novel treatments for patients with cancer and autoimmune diseases. The Company’s “off-the-shelf”, or allogeneic, T-cells are engineered from donors with healthy immune function and allow for rapid delivery from inventory to patients without a requirement for pretreatment. Atara’s T-cell immunotherapies are designed to precisely recognize and eliminate cancerous or diseased cells without affecting normal, healthy cells. Atara’s most advanced T-cell immunotherapy in development, ATA129, is being developed for the treatment of cancer patients with rituximab-refractory Epstein-Barr virus (EBV) associated post-transplant lymphoproliferative disorder (EBV-PTLD), as well as other EBV positive hematologic and solid tumors including nasopharyngeal carcinoma (NPC). Phase 3 studies of ATA129 in EBV-PTLD following a hematopoietic cell transplant (MATCH study) or solid organ transplant (ALLELE study) are expected to start in 2017, and a Phase 1/2 study of ATA129 in combination with Merck's anti-PD-1 (programmed death receptor-1) therapy, KEYTRUDA® (pembrolizumab), in patients with platinum-resistant or recurrent EBV-associated NPC is planned for 2018. ATA129 is also available to eligible patients with EBV-positive tumors through an ongoing multicenter expanded access protocol (EAP) clinical study. Atara expects to submit ATA129 for conditional marketing authorization in EBV-PTLD following HCT in the EU in 2018. Allogeneic ATA188 and autologous ATA190, the Company’s next generation T-cell immunotherapies, selectively target specific EBV antigens believed to be important for the potential treatment of multiple sclerosis (MS). A Phase 1 clinical study of autologous ATA190 in progressive forms of MS is ongoing, and a Phase 1 allogeneic ATA188 study is expected to begin in the fourth quarter of 2017. Atara’s clinical pipeline also includes ATA520 targeting Wilms Tumor 1 (WT1) and ATA230 directed against cytomegalovirus (CMV).

Forward-Looking StatementsThis 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. For example, forward-looking statements include statements regarding: the Company’s belief that ATA188 and ATA190 have the potential to precisely recognize and eliminate EBV-infected B-cells and plasma cells in the central nervous system that may catalyze autoimmune responses and MS pathophysiology; the Company’s expected initiation of Phase 3 studies of ATA129 in EBV-PTLD following a hematopoietic cell transplant or solid organ transplant in 2017, a Phase 1/2 study of ATA129 in combination with Merck's anti-PD-1 therapy, KEYTRUDA® (pembrolizumab), in patients with platinum-resistant or recurrent EBV-associated NPC in 2018 and a Phase 1 allogeneic ATA188 study in the fourth quarter of 2017; and the Company’s expected submission of a conditional marketing authorization application in EBV-PTLD following HCT in the EU in 2018.  Because such statements deal with future events and are based on Atara Biotherapeutics’ current expectations, they are subject to various risks and uncertainties and actual results, performance or achievements of Atara Biotherapeutics could differ materially from those described in or implied by the statements in this press release. These forward-looking statements are subject to risks and uncertainties, including those discussed under the heading "Risk Factors" in Atara Biotherapeutics’ quarterly report on Form 10-Q filed with the Securities and Exchange Commission (SEC) on August 7, 2017, including the documents incorporated by reference therein, and subsequent filings with the SEC. 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 Biotherapeutics650-410-3012jcraighead@atarabio.com

Steve Klass, Burns McClellan212-213-0006 x331sklass@burnsmc.com

Media:Justin Jackson, Burns McClellan212-213-0006 x327jjackson@burnsmc.com