he present invention relates to methods of treating cancer by administering an EZH2 inhibitor or a pharmaceutical composition thereof to the subject in need thereof. The present claims define methods for treating specific subtypes of non-Hodgkin's lymphoma comprising the administration to a subject of EZH2 inhibitors. Preferred EZH2 inhibitors include tazemetostat (EPZ-6438 E7438) and other compounds. Dosage amounts and regimes are also defined.