Epizyme Appoints Hoyoung Huh, MD, PhD Chairman of the Board

Cambridge, MA - September 20, 2009: Epizyme, Inc., a biopharmaceutical company translating key discoveries in the field of epigenetics into novel pharmaceutical agents, announced today that Dr. Hoyoung Huh, President and CEO of BiPar Sciences, Inc., was appointed Epizyme's Chairman of the Board of Directors. Epizyme recently announced the closing of a $32M Series B financing led by Bay City Capital (BCC).

Epizyme is developing a robust pipeline of first-in-class inhibitors of histone methyltransferase (HMT) enzymes involved in cancer and other serious indications including inflammatory conditions, metabolic disorders and neurodegenerative diseases. In addition to identifying novel small molecule HMT inhibitors for various cancers, Epizyme is developing an integrated platform that enables broad and efficient prosecution of the "HMTome" for its potential value across the therapeutic spectrum.

"I am excited to join the Board of a world- class research team and investor group in Epizyme. The company is well positioned to become a leader in the emerging field of epigenetics, one of the most exciting novel approaches to cancer therapeutic development," commented Dr. Huh.

Dr. Hoyoung Huh brings to the Board experience in drug discovery and development as well as expertise in corporate partnerships. Dr. Huh is currently President and CEO of BiPar Sciences, an independent, wholly owned subsidiary of Sanofi-aventis (EURONEXT: SAN and NYSE: SNY) developing novel cancer therapeutics based on DNA-repair inhibition. He led the $500 million merger in April 2009 between BiPar and Sanofi-aventis. Prior to BiPar, Dr. Huh was a member of the Board of Directors at Nektar Therapeutics (NASDAQ: NKTR), and also served in a number of executive positions, including Chief Operating Officer and Head of the PEGylation Business Unit. At Nektar, he led multiple partnerships with major pharmaceutical companies, including Bayer-Schering Pharma, Baxter International, Bristol-Myers Squibb, Novartis, Pfizer, and Roche. Dr. Huh is also a member of the board of directors at Facet Biotech (NASDAQ: FACT), BayBio, Interplast, Inc., and SciDose LLC. He was a partner at McKinsey & Company, where he served as a leader in the healthcare and biotechnology practice across the U.S., Europe and Asia. Dr. Huh received his M.D. degree from Cornell University Medical College, Ph.D. in Genetics/Cell Biology from Cornell University/Sloan-Kettering Institute, and his A.B. in Biochemistry from Dartmouth College.

"We are delighted that Dr. Huh will be joining our Board as Chairman and we look forward to his valuable input in a variety of our strategic initiatives ranging from clinical development to corporate partnering," commented Dr. Kazumi Shiosaki, CEO of Epizyme.

Epizyme Background

Epizyme, Inc., a biopharmaceutical company, was founded in 2007 to create innovative drugs for major diseases based on new discoveries emerging from the field of epigenetics. Epizyme is initially focusing on histone methyltransferases (HMTs), a large class of epigenetic enzymes that are recognized for the critical roles they play in serious diseases such as cancer. Epizyme is developing an enabling and integrated drug discovery platform that has evolved a robust and sustainable pipeline of first-in-class inhibitors of HMTs. Epizyme is located in Cambridge, MA. For additional information, please visit www.epizyme.com.

Contact: Kazumi Shiosaki, CEO, 617-500-7239, kshiosaki@epizyme.com