Epizyme, Inc. (NASDAQ: EPZM), a clinical stage biopharmaceutical company creating novel epigenetic therapeutics for cancer patients, today announced the closing of its public offering of 15,333,334 shares of its common stock at a price of $9.00 per share before underwriting discounts. The shares of common stock issued and sold in the offering at the closing include 2,000,000 shares issued upon the exercise in full by the underwriters of their option to purchase additional shares at the public offering price less the underwriting discount.

The aggregate net proceeds before expenses to Epizyme from the offering are approximately $130.1 million, after deducting underwriting discounts and commissions.

Citigroup, Leerink Partners LLC and RBC Capital Markets, LLC acted as joint book-running managers for the offering. JMP Securities and Wedbush PacGrow acted as co-lead managers for the offering, and Mizuho Securities, H.C. Wainwright & Co., LLC and Maxim Group LLC acted as co-managers.

A shelf registration statement relating to the shares of common stock offered in the public offering was filed with the Securities and Exchange Commission (SEC) on May 4, 2015, and declared effective by the SEC on May 29, 2015. The offering was made only by means of a written prospectus and prospectus supplement that form a part of the registration statement. A prospectus supplement related to the offering has been filed with the SEC and may be obtained for free by visiting EDGAR on the SEC website at www.sec.gov. Copies of the prospectus supplement and the accompanying prospectus relating to the securities offered may also be obtained by contacting Citigroup Global Markets Inc., c/o Broadridge Financial Services, 1155 Long Island Avenue, Edgewood, NY 11717, or by email at prospectus@citi.com or by phone at 800-831-9146; Leerink Partners LLC, Attention: Syndicate Department, One Federal Street, 37th Floor, Boston, MA 02110, or by email at Syndicate@Leerink.com, or by phone at 1-800-808-7525 ext. 6142; or RBC Capital Markets, LLC, 200 Vesey Street, 8th Floor, New York, NY 10281-8098; Attention: Equity Syndicate; Phone: 877-822-4089; Email: equityprospectus@rbccm.com.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or other jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or other jurisdiction.

About Epizyme, Inc.

Epizyme, Inc. is a clinical stage biopharmaceutical company creating novel epigenetic therapeutics for cancer patients. Epizyme has built a proprietary drug discovery platform that the company uses to create small molecule inhibitors of chromatin modifying proteins (CMPs) such as histone methyltransferases (HMTs). Using its proprietary platform, the company has built a pipeline of programs led by tazemetostat, its novel inhibitor of the EZH2 HMT. Based on data from an ongoing phase 1 clinical trial, tazemetostat is being evaluated in multiple registration-supporting trials for the potential treatment of non-Hodgkin lymphoma and certain genetically defined solid tumors. The company is currently conducting a phase 2 study of tazemetostat in patients with relapsed or refractory non-Hodgkin lymphoma, a phase 2 study in adult patients with INI1-negative solid tumors, certain SMARCA4-negative solid tumors or synovial sarcoma, and a phase 1 study in pediatric patients with INI1-negative solid tumors, certain SMARCA4-negative solid tumors or synovial sarcoma.