SALT FORM OF A HUMAN HISTONE METHYLTRANSFERASE EZH2 INHIBITOR

1 . A composition comprising Polymorph A of N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-yl)amino)-4-methyl-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide hydrobromide, substantially free of Polymorph B of N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-yl)amino)-4-methyl-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide hydrobromide.

2 - 8 . (canceled)

9 . The composition according to claim 1 , wherein the Polymorph A exhibits an X-ray powder diffraction pattern having one or more characteristic peaks expressed in degrees 2-theta at about 3.9+/−0.3 degrees, about 17.5+/−0.3 degrees, and about 22.0+/−0.3 degrees 2-theta.

10 . The composition according to claim 1 , wherein the Polymorph A exhibits an X-ray powder diffraction pattern having characteristic peaks expressed in degrees 2-theta at about 3.9+/−0.3 degrees, about 17.5+/−0.3 degrees, and about 22.0+/−0.3 degrees 2-theta.

11 - 16 . (canceled)

17 . The composition according to claim 1 , wherein the Polymorph A exhibits an X-ray powder diffraction pattern having at least 10 characteristic peaks expressed in degrees 2-theta at about 3.9+/−0.3 degrees, 10.1+/−0.3 degrees, 14.3+/−0.3 degrees, 17.5+/−0.3 degrees, 18.7+/−0.3 degrees, 20.6+/−0.3 degrees, 20.9+/−0.3 degrees, 21.8+/−0.3 degrees, 22.0+/−0.3 degrees, 23.3+/−0.3 degrees and 23.6+/−0.3 degrees 2-theta.

18 . (canceled)

19 . The composition according to claim 1 , wherein the Polymorph A exhibits an X-ray powder diffraction pattern substantially in accordance with FIG. 1 .

20 . The composition according to claim 1 , wherein the Polymorph A exhibits an X-ray powder diffraction pattern substantially in accordance with Table 1.

21 . The composition according to claim 1 , wherein the Polymorph A exhibits a differential scanning calorimetry thermogram having a characteristic peak expressed in units of ° C. at a temperature of 255+/−5° C.

22 . The composition according to claim 1 , wherein the Polymorph A exhibits a differential scanning calorimetry thermogram substantially in accordance with FIG. 3 .

23 - 34 . (canceled)

35 . The composition according to claim 1 , wherein the Polymorph B exhibits an X-ray powder diffraction pattern having characteristic peaks expressed in degrees 2-theta at 8.5±0.2 degrees, 10.9±0.2 degrees, 16.7±0.2 degrees, 17.4±0.2 degrees, 20.9±0.2 degrees, 22.1±0.2 degrees, and 25.7±0.2 degrees 2-theta.

36 . The composition according to claim 9 , wherein the Polymorph B exhibits an X-ray powder diffraction pattern having characteristic peaks expressed in degrees 2-theta at 8.5±0.2 degrees, 10.9±0.2 degrees, 16.7±0.2 degrees, 17.4±0.2 degrees, 20.9±0.2 degrees, 22.1±0.2 degrees, and 25.7±0.2 degrees 2-theta.

37 . The composition according to claim 1 , wherein the Polymorph B exhibits an X-ray powder diffraction pattern substantially as shown in FIG. 10 .

38 . A pharmaceutical composition comprising the composition according to claim 1 , and a pharmaceutically acceptable carrier or diluent.

39 . A method of treating cancer comprising administering to a subject in need thereof a composition according to claim 1 .

40 . The method according to claim 39 , wherein the cancer is follicular lymphoma.

41 . The method according to claim 39 , wherein the cancer is a soft tissue sarcoma.

42 . The method according to claim 39 , wherein the cancer is diffuse large B-cell lymphoma or cutaneous T-cell lymphoma.

43 . A method of inhibiting the histone methyltransferase activity of EZH2 in a subject in need thereof comprising administering to the subject a composition according to claim 1 .

44 . A method of inhibiting the histone methyltransferase activity of EZH2 in vitro comprising administering a composition according to claim 1 .

45 . A method of preparing N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-yl)amino)-4-methyl-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide comprising reacting:

with a salt of

or

a method of preparing Polymorph A of N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-yl)amino)-4-methyl-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide hydrobromide, comprising: combining N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-10 yl)amino)-4-methy 1-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide with hydrobromic acid; or

a method of recrystallizing Polymorph A of N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-yl)amino)-4-methyl-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide hydrobromide, comprising the following steps:

(a) dissolving Polymorph A of N-((4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-5-(ethyl(tetrahydro-2H-pyran-4-yl)amino)-4-methyl-4′-(morpholinomethyl)-[1,1′-biphenyl]-3-carboxamide hydrobromide in a first solvent, and

(b) adding a second solvent, such that said polymorph is recrystallized.

46 . A compound:

or a salt thereof.