Enhancer of zeste homolog 2 inhibitors

A method of treating non-Hodgkin's lymphoma comprising administering to a patient with non-Hodgkin's lymphoma a therapeutically effective amount of a compound of formula (I):

• wherein:
• R1 is methyl;
• R2 is methyl;
• R3 is hydrogen;
• R4 is methyl;
• R5 is —NRaRb;
• R6 is phenyl, wherein said phenyl is optionally substituted by —(C1-C6)alkyl(Rc);
• Rc is —NRaRb;
• and
• Ra and Rb are each independently hydrogen, (C1-C8)alkyl, (C2-C8)alkenyl, (C2-C8)alkynyl, (C3-C10)cycloalkyl, (C5-C8)cycloalkenyl, heterocycloalkyl, or aryl, wherein said (C1-C8)alkyl, (C2-C8)alkenyl, (C2-C8)alkynyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, or aryl group is optionally substituted by 1, 2 or 3 groups independently selected from the group consisting of halo, hydroxyl, (C1-C4)alkoxy, amino, (C1-C4)alkylamino, —N((C1-C4)alkyl)2, —CO2H, —CO2(C1-C4)alkyl, —CONH2, —CONH(C1-C4)alkyl, —CON((C1-C4)alkyl)2, —SO2(C1-C4)alkyl, —SO2NH2, —SO2NH(C1-C4)alkyl, and —SO2N((C1-C4)alkyl)2;
• and wherein said heterocycloalkyl is selected from the group consisting of pyrrolidinyl, tetrahydrofuranyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, and tetrahydropyranyl;
• or Ra and Rb taken together with the nitrogen to which they are attached represent a 5 or 6 membered saturated ring, optionally containing an additional heteroatom selected from oxygen, nitrogen, and sulfur, wherein said ring is optionally substituted by 1, 2 or 3 groups independently selected from the group consisting of (C1-C4)alkyl, (C1-C4)haloalkyl, amino, (C1-C4)alkylamino, ((C1-C4)alkyl)((C1-C4)alkyl)amino, hydroxyl, oxo, (C1-C4)alkoxy, and (C1-C4)alkoxy(C1-C4)alkyl;
• or a pharmaceutically acceptable salt thereof.