X0306 4 2014-05-19 0 0001571498 Epizyme, Inc. EPZM 0001577021 Copeland Robert A C/O EPIZYME, INC. 400 TECHNOLOGY SQUARE CAMBRIDGE MA 02139 0 1 0 0 EVP and CSO Common Stock, par value $0.0001 per share 2014-05-19 4 S 0 2450 22.2761 D 17561 D Common Stock, par value $0.0001 per share 2014-05-19 4 S 0 2550 22.2761 D 18281 I By Wife The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.05 per share to $22.63 per share, inclusive. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. /s/ Stephen Garbacz, attorney-in-fact 2014-05-21