X0306 4 2017-03-09 0 0001571498 Epizyme, Inc. EPZM 0001632720 Singer Andrew E. C/O EPIZYME, INC. 400 TECHNOLOGY SQUARE CAMBRIDGE MA 02139 0 1 0 0 EVP & CFO Common stock, par value $0.0001 2017-03-09 4 M 0 1682 A 37411 D Common stock, par value $0.0001 2017-03-09 4 M 0 777 A 38188 D Restricted Stock Units 0.00 2017-03-09 4 M 0 1682 0.00 D Common Stock 1682 38684 D Restricted Stock Units 0.00 2017-03-09 4 M 0 777 0.00 D Common Stock 777 17879 D Each restricted stock unit represents the contingent right to receive one share of Epizyme, Inc. common stock upon vesting. This award, granted on February 9, 2016, pursuant to the Company's 2013 Stock Incentive plan, vests as to 25% of the total award on February 9, 2016, a year from the commencement of employment, with the remaining 75% vesting in 36 substantially equal monthly installments thereafter. Vested shares will be delivered to the reporting person. This award, granted on February 9, 2015, pursuant to the Company's 2013 Stock Inventive Plan, vests as to 25% of the total award on February 9, 2016, with the remaining 75% vesting in 36 substantially equal monthly installments thereafter. Vested shares will be delivered to the reporting person. /s/ Adriana Sullivan, attorney-in-fact 2017-03-10