Syndax Appoints Dr. Briggs W. Morrison as Chief Executive Officer and Michael A. Metzger as President and Chief Operating Officer

New Executive Team Will Intensify Focus on Innovation and Leadership in Immuno-oncology

WALTHAM, Mass., June 15, 2015 -- Syndax Pharmaceuticals, Inc., a privately held oncology company, announced today that Briggs W. Morrison, M.D. is joining the Company as Chief Executive Officer and a member of the Board of Directors, and that Michael A. Metzger is joining the Company as President and Chief Operating Officer. Dr. Morrison joins Syndax from AstraZeneca, where he was Executive Vice President, Global Medicines Development and Chief Medical Officer. Mr. Metzger joins from Regado Biosciences, where he served as President and Chief Executive Officer through the company's strategic merger with Tobira Therapeutics.

"Syndax is at a major inflection point in its evolution, leveraging recent scientific insights into its lead therapeutic candidate entinostat in the emerging field of immuno-oncology. We are thrilled to have Briggs and Michael assume these critical executive roles," said Dennis G. Podlesak, Chairman of the Syndax Board of Directors and Partner at Domain Associates. "Briggs is a pre-eminent drug developer with an impressive track record of bringing cutting-edge medicines to patients and provides Syndax with the depth and vision to deliver on the promising data with entinostat. Michael comes to Syndax as an accomplished leader and builder of biotechnology companies and has a proven track record of success in creating value through business development and strategic financial transactions. Together they create an extraordinarily strong and complementary team capable of leading Syndax to the next level of success."

"Syndax is at the forefront of an exciting phase in the clinical and scientific validation of its epigenetic approach to unlocking the full potential of immuno-oncology therapies. With a breakthrough designation in advanced breast cancer and emerging preclinical and clinical data as an epigenetic immunomodulator, I believe entinostat could become a cornerstone combination therapy for a broad range of cancers," said Dr. Morrison.

"In 2015, we expect to build on the momentum generated from Syndax's recent collaborations with Merck and Kyowa Hakko Kirin, with additional partnerships and multiple, near-term clinical milestones. Michael and I look forward to working with the executive team at Syndax to help realize entinostat's and the company's full potential," Dr. Morrison continued.

As Executive Vice President, Global Medicines Development and Chief Medical Officer at AstraZeneca from 2012 to 2015, Dr. Morrison led the company's global, late-stage development organization and served as a member of the AstraZeneca Senior Executive Team. Prior to joining AstraZeneca, Dr. Morrison held a number of positions at Pfizer from 2007 to 2012 that culminated in his appointment as Head, Medical Affairs, Safety and Regulatory Affairs for Pfizer's human health business. He previously served in roles of increasing responsibility at Merck Research Laboratories from 1995 to 2007, where he was ultimately appointed to the role of Vice President, Clinical Sciences, Oncology, responsible for clinical development of all novel anti-cancer drugs. Dr. Morrison is Chairman of the Board of Transcelerate, an industry-funded company charged with improving aspects of clinical trials, a member of the Executive Committee of CTTI (the Clinical Trials Transformation Initiative sponsored by FDA) and is on the Board of ACRES (Alliance for Clinical Research Excellence and Safety). Dr. Morrison received a B.S. in Biology from Georgetown University, Phi Beta Kappa, and an M.D. from the University of Connecticut, followed by an internship and residency in Internal Medicine at the Massachusetts General Hospital, a fellowship in Medical Oncology at the Dana-Farber Cancer Institute and a post-doctoral research fellowship in Genetics at Harvard Medical School.

Mr. Metzger brings extensive experience leading and growing companies in the biopharmaceutical industry. Most recently, Mr. Metzger held the positions of President, Chief Executive Officer and a member of the Board of Directors of Regado Biosciences through the company's strategic merger with Tobira Therapeutics in 2015. Previously, he served as Executive Vice President and Chief Operating Officer at Mersana Therapeutics, a privately held biopharmaceutical company, from 2011 to 2013, and in senior Business Development positions including leading Mergers and Acquisitions at Forest Laboratories, Inc. from 2006 to 2011. Prior to Forest, Mr. Metzger served as Vice President, Corporate Development at Onconova Therapeutics, Inc., from 2001 until 2006, and was a Managing Director at Mesa Partners, Inc., a venture capital firm, from 1997 to 2001. Mr. Metzger holds a B.A. from George Washington University and an M.B.A. in Finance from the New York University Stern School of Business.

About Syndax Pharmaceuticals, Inc.
Syndax Pharmaceuticals is a privately held biopharmaceutical company leveraging recent scientific insights on its lead therapeutic candidate entinostat in the emerging field of immuno-oncology. Due to its distinctive mechanism and preclinical and clinical activity observed to date, entinostat, a targeted, epigenetic immunomodulator (EMOD), holds great promise as a cornerstone combination therapy for a broad range of cancers. Syndax is collaborating with Merck to evaluate entinostat in combination with KEYTRUDA® (pembrolizumab) to treat non-small cell lung cancer (NSCLC) and melanoma. Entinostat is also in Phase 3 development, under a special protocol assessment (SPA) agreement, in combination with exemestane to treat HR+ advanced breast cancer, an indication for which entinostat was granted Breakthrough Therapy designation by the U.S. Food and Drug Administration. Additional NCI- and investigator-sponsored combination clinical trials of entinostat and immuno-oncology agents in solid tumors further establish Syndax's broad immune-directed program. For more information on Syndax please visit www.syndax.com.

Contacts
Investor and Media Relations:
Karen L. Bergman
BCC Partners
(650) 575-1509
[email protected]

Jen LaVin
BCC Partners
(617) 718-0276
[email protected]