The disclosure relates to a method for treating cancer comprising administering a therapeutically effective amount of an EZH2 inhibitor to a subject in need thereof, wherein the cancer is characterized by at least one cancer cell originating from a stem cell, a progenitor cell, or an immature cell and wherein the at least one cancer cell comprises one or more genetic lesion(s) that confer(s) dependence of the cancer cell on an EZH2 function. In certain embodiments, the EZH2 inhibitor of the disclosure is tazemetostat or a pharmaceutically acceptable salt thereof.
