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Atara Biotherapeutics Reports Early Findings of Potential Efficacy from Phase 1 Study of ATA188 in Patients with Progressive Multiple Sclerosis at ECTRIMS 2019

Enrollment in the fourth and final planned Phase 1 dose escalation cohort completed

ATA188 targets Epstein-Barr Virus (EBV)-infected B cells, believed to play a role in the pathogenesis of multiple sclerosis

Conference call and webcast today at 3:30 p.m. CEST / 9:30 a.m. EDT

SOUTH SAN FRANCISCO, Calif., Sept. 13, 2019 (GLOBE NEWSWIRE) -- Atara Biotherapeutics, Inc. (ATRA), a leading off-the-shelf, allogeneic T-cell immunotherapy company developing novel treatments for patients with cancer, autoimmune and viral diseases, today announced the presentation of initial efficacy data as well as updated safety results from its ongoing Phase 1 study of ATA188 for the treatment of progressive forms of multiple sclerosis (MS). The data are featured in a late-breaking poster presentation at the 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS), held in Stockholm, Sweden, September 11-13, 2019.

ATA188 is an off-the-shelf, allogeneic T-cell immunotherapy that targets Epstein-Barr Virus (EBV)-infected B cells believed to play a role in the pathogenesis of MS.

“I am encouraged by the well tolerated safety profile as well as early findings of potential efficacy in the ongoing ATA188 Phase 1 study,” said Professor Amit Bar-Or, MD, FRCP, FAAN, FANA, Chief of MS Division, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania. “The outcome classification using multiple clinically recognized MS scales is an innovative approach, and I look forward to advancing the study alongside my colleagues for progressive MS patients who have limited treatment options and where continual clinical decline is expected.”

The reported initial data as of July 29, 2019 are from a Phase 1, multicenter, open-label, dose-escalation study evaluating the safety and efficacy of ATA188 in patients with progressive forms of MS. In this study, patients were treated across four dose cohorts (5 x 106, 1 x 107, 2 x 107 and 4 x 107 cells), with 6 patients per cohort.

Clinical outcome classification

Clinical outcomes of ATA188 were assessed at baseline and approximately 3, 6, and 12 months follow up from initial dose using recognized scales for MS symptoms, function and disability including: Expanded Disability Status Scale (EDSS), Fatigue Severity Score, MS Impact Scale-29 (physical), Timed 25-Foot Walk (T25FW), 9-Hole Peg Test, 12-Item MS Walking Scale (MSWS-12) and Visual Acuity (VA).

An outcome classification was developed to categorize clinical response by the following clinical criteria:

  • Clinical Improvement: Clinically significant improvement or greater on 2 or more of the above MS scales compared to baseline sustained over 2 or more consecutive timepoints
  • Partial Clinical Improvement: Clinically significant improvement or greater on 2 or more of the above MS scales compared to baseline at 1 or more timepoint
  • Stable: Does not fulfill criteria for decline or improvement
  • Clinical Decline: Clinically significant decline in 2 or more scales compared to baseline at 1 or more timepoint; clinical decline takes precedence over improvement

Safety 

Safety results showed that across the 4 planned dose cohorts, ATA188 was well tolerated in patients with progressive forms of MS with no evidence of cytokine release syndrome, graft versus host disease or dose-limiting toxicities.

Initial efficacy

At approximately 6 months from initial dose, 4 of 6 patients in cohort 1 demonstrated clinical decline which was maintained at 12 months.

In cohort 2, an outcome classification of clinical improvement or partial clinical improvement was observed in all 6 patients at 6 months. No patients showed an outcome classification of stable or clinical decline.

“The safety and efficacy results presented from our ongoing ATA188 Phase 1 study highlight the potential for an off-the-shelf, allogeneic T-cell immunotherapy targeting Epstein-Barr Virus (EBV)-infected B cells in patients with progressive forms of MS,” said AJ Joshi, MD, Senior Vice President and Chief Medical Officer of Atara Biotherapeutics. “Our recent completion of enrollment in the fourth and final dose escalation cohort moves us closer to identifying the dose to initiate a randomized, double-blind, placebo-controlled Phase 1b part of this study. We are committed to advancing ATA188 for MS patients and look forward to presenting additional efficacy and safety results from this study in 2020, including from cohorts 3 and 4.”

Atara will host a live conference call and webcast on Friday, September 13, at 3:30 p.m. CEST / 9:30 a.m. EDT to discuss these results, featuring Dr. Lawrence Steinman, professor of Neurology and Neurological Sciences, Pediatrics, and Genetics at Stanford University and former Chair of the Stanford University Interdepartmental Program in Immunology.

For more information about the ATA188 Phase 1 study, please visit ClinicalTrials.gov (NCT03283826).

Details of the ECTRIMS 2019 presentation

Title:   Preliminary safety and efficacy of ATA188, a pre-manufactured, unrelated donor (off-the-shelf, allogeneic) Epstein-Barr virus-targeted T-cell immunotherapy for patients with progressive forms of multiple sclerosis
Lead Author:   Amit Bar-Or, Perelman School of Medicine, University of Pennsylvania
Abstract #:   P1657
Session:   Poster Session 3
Date:    Friday, September 13, 2019
Time:   12:15-2:15 p.m. CEST
Location:   Poster Exhibition
     

Atara conference call and webcast information

Analysts and investors can participate in the conference call by dialing (888) 540-6216 for domestic callers and (734) 385-2715 for international callers, using the conference ID 3275835. A live audio webcast can be accessed by visiting the Investor Events and Presentations section of atarabio.com. An archived replay will be available on the Company's website for approximately 30 days following the live webcast.

About Multiple Sclerosis
Multiple Sclerosis (MS) is a chronic neurological autoimmune disease that affects more than two million people around the world. Relapsing-remitting MS (RRMS) is the most common form of MS and is characterized by episodes of new or worsening signs or symptoms (relapses) followed by periods of recovery. Progressive MS (PMS) is a severe form of the disease for which there are few therapeutic options. There are two categories of PMS, both of which are 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 has been reported to occur in approximately 15% of newly diagnosed cases of MS.  Secondary Progressive MS (SPMS) initially begins as RRMS and develops into a progressive form. Treatment history indicates that approximately 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. Scientific and clinical findings support a biologic connection between Epstein-Barr Virus (EBV) and MS.

About off-the-shelf, allogeneic ATA188 and autologous ATA190
ATA188 and ATA190 are T-cell immunotherapies targeting Epstein-Barr Virus (EBV)-infected B cells believed to play a role in the pathogenesis of MS. Both candidates selectively target latent EBV antigens presented by B cells; however, ATA188 is off-the-shelf and allogeneic, whereas ATA190 is autologous. ATA188 and ATA190 utilize T-cell immunotherapy technology pioneered by Professor Rajiv Khanna at QIMR Berghofer. Atara is advancing an ongoing Phase 1 ATA188 study in patients with progressive MS across clinical sites in the U.S. and Australia and plans to initiate a randomized ATA190 study in progressive MS patients.

About Atara Biotherapeutics, Inc.
Atara Biotherapeutics, Inc. (@Atarabio) is a leading off-the-shelf, allogeneic T-cell immunotherapy company developing novel treatments for patients with cancer, autoimmune and viral diseases. Atara’s technology platform leverages research collaborations with leading academic institutions with the Company’s scientific, clinical, regulatory and manufacturing expertise. Atara’s pipeline includes tab-cel® (tabelecleucel), which is in Phase 3 development for patients with Epstein-Barr Virus-associated post-transplant lymphoproliferative disorder (EBV+ PTLD) as well as in earlier stage development for other EBV-associated hematologic malignancies and solid tumors, including nasopharyngeal carcinoma (NPC); T-cell immunotherapies targeting EBV antigens believed to be important for the potential treatment of multiple sclerosis; and next-generation chimeric antigen receptor T-cell (CAR T) immunotherapies. The company was founded in 2012 and is co-located in South San Francisco and Southern California. Our Southern California hub is anchored by the state-of-the-art Atara T-cell Operations and Manufacturing (ATOM) facility in Thousand Oaks, California. For additional information about the company, please visit 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. For example, forward-looking statements include statements regarding: the results from Atara’s ongoing ATA188 Phase 1 clinical study; the continuation of this study and identification of a recommended Phase 2 dose; the initiation of a randomized, double-blind, placebo-controlled portion of this study; and beliefs about the connection of EBV-infected B cells to MS.  These forward-looking statements are subject to risks and uncertainties, including those discussed in Atara Biotherapeutics' filings with the Securities and Exchange Commission (SEC), including in the “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” sections of the Company’s most recently filed periodic reports on Form 10-K and Form 10-Q and subsequent filings and in the documents incorporated by reference therein. 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.

Editor’s note: Bar-Or is a paid consultant for Atara Biotherapeutics.

INVESTOR & MEDIA CONTACT:

John Craighead, Ph.D.
Vice President, Investor Relations & Corporate Communications
Atara Biotherapeutics
650-410-3012
jcraighead@atarabio.com