X0306 4 2022-08-09 0 0001571498 Epizyme, Inc. EPZM 0001766032 Beaulieu Joseph C/O EPIZYME, INC., 400 TECHNOLOGY SQUARE, 4TH FLOOR CAMBRIDGE MA 02139 0 1 0 0 See Remarks Common Stock, par value $0.0001 2022-08-09 4 M 0 300000 1.39 A 330963 D Common Stock, par value $0.0001 2022-08-09 4 F 0 279864 1.39 D 51099 D Stock Option (Right to Buy) 1.39 2022-08-09 4 M 0 300000 0.00 D 2032-03-16 Common Stock 300000 0 D These shares were withheld so the Reporting Person could satisfy the exercise price arising from a net (cashless) exercise of stock options that occurred on August 9, 2022. On June 27, 2022, the Issuer entered into an Agreement and Plan of Merger (the "Merger Agreement"), by and among the Issuer, Ipsen Pharma SAS and Hibernia Merger Sub, Inc. Pursuant to the terms of the Merger Agreement, each Exercisable Pre-Close Option (as defined in the Merger Agreement) became exercisable on the Acceleration Date (August 5, 2022) up to and through the close of regular trading on the Nasdaq Stock Market on the second (2nd) business day thereafter (August 9, 2022). Senior Vice President, Finance and Corporate Controller /s/ John Weidenbruch, attorney-in-fact 2022-08-11