Polymorphs of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide

1. A substantially pure crystalline form A of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.9, 9.2, 12.5, 15.2, 18.4, 19.4, 19.7, 19.8, 27.7 and 28.7 (2θ degrees).

2. The substantially pure crystalline form of claim 1 , wherein the x-ray powder diffraction pattern is as shown in FIG. 1 .

3. A substantially pure crystalline form B of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 10.6, 12.1, 13.6, 14.1, 15.7, 16.9, 19.4, 20.3, 22.2, 23.4, 24.4, 24.8, 25.5 and 27.7 (2θ degrees).

4. The substantially pure crystalline form of claim 3 , wherein the x-ray powder diffraction pattern is as shown in FIG. 1 .

5. A substantially pure crystalline form C of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 8.5, 9.7, 11.6, 12.8, 13.6, 15.1, 16.1, 17.1, 18.2, 19.4, 20.4, 21.5, 22.9, 23.4, 24.5, 25.5, 29.9 and 30.5 (2θ degrees).

6. The substantially pure crystalline form of claim 5 , wherein the x-ray powder diffraction pattern is as shown in FIG. 1 .

7. A substantially pure crystalline form H A of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.7, 13.0, 13.4, 14.4, 16.7, 17.5, 17.8, 18.5, 19.8, 20.1, 21.7, 22.0, 22.3, 22.7, 23.3, 24.2, 24.4, 25.6, 27.0, 28.1 and 29.5 (2θ degrees).

8. The substantially pure crystalline form of claim 7 , wherein the x-ray powder diffraction pattern is as shown in FIG. 1 .

9. A substantially pure crystalline form H B of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 8.0, 9.5, 10.2, 14.3, 16.9, 17.7, 18.4, 18.7, 19.1, 19.4, 21.2, 21.4 and 27.4 (2θ degrees).

10. The substantially pure crystalline form of claim 9 , wherein the x-ray powder diffraction pattern is as shown in FIG. 1 .

11. A substantially pure crystalline form A of the maleate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 6.9, 8.9, 9.3, 10.3, 13.7, 16.8, 17.8, 19.6, 20.7, 24.7, 25.4 and 27.7 (2θ degrees).

12. The substantially pure crystalline form of claim 11 , wherein the x-ray powder diffraction pattern is as shown in FIG. 2 .

13. A substantially pure crystalline form H A of the maleate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.0, 8.5, 9.4, 11.0, 11.7, 12.4, 13.7, 23.1, 24.2, 24.9, 28.5 and 30.2 (2θ degrees).

14. The substantially pure crystalline form of claim 13 , wherein the x-ray powder diffraction pattern is as shown in FIG. 2 .

15. A substantially pure crystalline form A of the hemi-tartarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.8, 11.9, 14.2, 15.8, 16.8, 20.2, 21.1, 21.7 and 25.0 (2θ degrees).

16. The substantially pure crystalline form of claim 15 , wherein the x-ray powder diffraction pattern is as shown in FIG. 3 .

17. A substantially pure crystalline form B of the hemi-tartarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.7, 11.9, 13.7, 14.2, 15.8, 17.8, 18.8, 21.2, 21.7, 24.9, 25.9 and 27.9 (2θ degrees).

18. The substantially pure crystalline form of claim 17 , wherein the x-ray powder diffraction pattern is as shown in FIG. 3 .

19. A substantially pure crystalline form C of the hemi-tartarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 10.2, 11.5, 13.3, 16.1, 16.9, 17.2 and 19.8 (2θ degrees).

20. The substantially pure crystalline form of claim 19 , wherein the x-ray powder diffraction pattern is as shown in FIG. 3 .

21. A substantially pure crystalline form A of the mesylate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 4.1, 8.2, 14.5, 18.1, 18.4, 19.8, 23.5 and 24.6 (2θ degrees).

22. The substantially pure crystalline form of claim 21 , wherein the x-ray powder diffraction pattern is as shown in FIG. 4 .

23. A substantially pure crystalline form B of the mesylate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.6, 11.5, 13.8, 15.1, 17.3, 18.9, 20.4, 21.7, 23.7 and 24.0 (2θ degrees).

24. The substantially pure crystalline form of claim 23 , wherein the x-ray powder diffraction pattern is as shown in FIG. 4 .

25. A substantially pure crystalline form of a salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide selected from the group consisting of:

(a) form A of the acetate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.1, 8.2, 8.1, 12.6, 16.3, 21.8 and 23.2 (2θ degrees);

(b) form S A of the acetate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.9, 8.4, 9.0, 16.5, 20.3, 22.6, 23.4 and 24.4 (2θ degrees);

(c) form A of the benzoate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 6.6, 7.9, 13.2, 16.4, 16.8, 19.1, 23.6 and 24.1 (2θ degrees);

(d) form S A of the benzoate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.2, 9.6, 11.5, 12.6, 18.5, 19.4, 23.1 and 23.4 (2θ degrees);

(e) form S B of the benzoate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.3, 11.6, 12.2, 17.9, 21.0, 23.3, 24.1 and 24.6 (2θ degrees);

(f) form A of the hemi-fumarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 11.5, 12.5, 15.8, 17.2, 18.8, 22.9, 24.5 and 25.0 (2θ degrees);

(g) form B of the hemi-fumarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 11.6, 11.9, 12.5, 14.1, 15.8, 22.9, 24.2 and 27.9 (2θ degrees);

(h) form H A of the hemi-fumarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.0, 10.1, 11.2, 15.1, 22.1 and 22.8 (2θ degrees);

(i) form A of the hemi-malate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.7, 12.0, 14.2, 15.9, 16.9, 20.3, 21.4 and 21.9 (2θ degrees);

(j) form S A of the hemi-malate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 6.6, 7.2, 9.4, 16.1, 18.4, 19.0, 21.9 and 22.4 (2θ degrees);

(k) form A of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.3, 9.4, 16.7, 17.7, 18.4, 21.5, 24.3 and 26.9 (2θ degrees);

(l) form S A of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 8.4, 16.5, 20.2, 21.8, 23.6, 25.4 and 31.0 (2θ degrees);

(m) form S B of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 6.2, 7.5, 8.2, 17.9, 22.1, 22.6, 23.7 and 25.5 (2θ degrees);

(n) form H A of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.4, 7.6, 8.3, 16.2, 17.4, 18.1 and 24.4 (2θ degrees);

(o) form A of the propionate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.0, 8.2, 9.5, 12.6, 14.1, 14.5, 18.4, 22.0, 23.9 and 25.5 (2θ degrees);

(p) form S A of the propionate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.0, 8.1, 8.7, 11.2, 12.0, 12.5, 16.1, 19.8 and 22.3 (2θ degrees);

(r) form A of the sulfate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 8.9, 10.2, 13.4, 16.1, 18.5, 22.0, 22.7 and 23.4 (2θ degrees);

(s) form S A of the sulfate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 4.6, 9.1, 13.7, 15.2, 18.4, 20.2, 22.5 and 22.9 (2θ degrees);

(t) form A of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 11.6, 12.5, 15.6, 17.3, 18.8, 23.1 and 24.7 (2θ degrees);

(u) form B of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.2, 7.7, 9.7, 11.5, 13.1, 15.1, 16.1 and 19.1 (2θ degrees);

(v) form S A of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.0, 10.2, 10.6, 11.1, 18.1 and 19.9 (2θ degrees); and

(w) form H A of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide characterized by an x-ray powder diffraction pattern having at least two maxima selected from 7.5, 11.6, 12.5, 14.1, 17.4, 23.0, 24.3 and 28.4 (2θ degrees).

26. The substantially pure crystalline form of claim 25 , wherein the substantially pure crystalline form is selected from the group consisting of:

(a) form A of the acetate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 5 ;

(b) form S A of the acetate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 5 ;

(c) form A of the benzoate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 6 ;

(d) form S A of the benzoate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 6 ;

(e) form S B of the benzoate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 6 ;

(f) form A of the hemi-fumarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 7 ;

(g) form B of the hemi-fumarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 7 ;

(h) form H A of the hemi-fumarate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 7 ;

(i) form A of the hemi-malate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 8 ;

(j) form S A of the hemi-malate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 8 ;

(k) form A of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 9 ;

(l) form S A of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 9 ;

(m) form S B of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 9 ;

(n) form H A of the phosphate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 9 ;

(o) form A of the propionate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 10 ;

(p) form S A of the propionate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 10 ;

(r) form A of the sulfate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 11 ;

(s) form S A of the sulfate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 11 ;

(t) form A of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 12 ;

(u) form B of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 12 ;

(v) form S A of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 12 ; and

(w) form H A of the hemi-succinate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the x-ray powder diffraction pattern is as shown in FIG. 12 .

27. A substantially pure crystalline form A of the DL-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.9, 11.4, 13.8, 15.7, 18.2, 19.7, 20.3, 21.5, 25.3, 27.4 and 30.0 (2θ degrees).

28. A substantially pure crystalline form A of the DL-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by the x-ray powder diffraction patter as shown in FIG. 13A .

29. A substantially pure crystalline form H A of the DL-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 8, 8.5, 9.0, 11.7, 13.7, 14.5, 15.1, 17.1, 17.4, 17.7, 18.5, 20.5 and 21.2 (2θ degrees).

30. The substantially pure crystalline form of claim 29 , wherein the x-ray powder diffraction patter is as shown in FIG. 13B .

31. A substantially pure crystalline form S A of the DL-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.9, 17.2, 17.7, 18.1, 19.5, 20.5, 21.4, 21.7, 22.5, 23.6, 24.6 and 26.1 (2θ degrees).

32. The substantially pure crystalline form of claim 31 , wherein the x-ray powder diffraction patter is as shown in FIG. 13C .

33. A substantially pure crystalline form A of the L-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.9, 11.4, 13.8, 18.1, 18.5, 19.7, 20.2, 21.6, 25.2 and 29.9 (2θ degrees).

34. The substantially pure crystalline form of claim 33 , wherein the x-ray powder diffraction patter is as shown in FIG. 13D .

35. A substantially pure crystalline form A of the D-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized by an x-ray powder diffraction pattern having at least two maxima selected from 9.9, 11.4, 13.8, 18.1, 18.5, 19.7, 20.2, 21.6 and 25.2 (2θ degrees).

36. A substantially pure crystalline form A of the D-lactate salt of N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)ethyl]amino]methyl]phenyl]-2E-2-propenamide, wherein the substantially pure crystalline form is characterized the x-ray powder diffraction patter is as shown in FIG. 13E .

37. A pharmaceutical composition comprising:

(a) a therapeutically effective amount of a substantially pure crystalline form of claim 27 ; and

(b) at least one pharmaceutically acceptable carrier, diluent, vehicle or excipient.

38. A method of treating a disease comprising administering to a subject in need of such treatment a therapeutically effective amount of a substantially pure crystalline form of claim 27 , wherein the disease is cutaneous t-cell lymphoma, acute myeloid leukemia, myelodysplastic syndrome or castration-resistant prostate cancer.

39. A pharmaceutical composition comprising:

(a) a therapeutically effective amount of a substantially pure crystalline form of claim 33 ; and

(b) at least one pharmaceutically acceptable carrier, diluent, vehicle or excipient.

40. A method of treating a disease comprising administering to a subject in need of such treatment a therapeutically effective amount of a substantially pure crystalline form of claim 33 , wherein the disease is cutaneous t-cell lymphoma, acute myeloid leukemia, myelodysplastic syndrome or castration-resistant prostate cancer.

41. A pharmaceutical composition comprising:

(a) a therapeutically effective amount of a substantially pure crystalline form of claim 35 ; and

(b) at least one pharmaceutically acceptable carrier, diluent, vehicle or excipient.

42. A method of treating a disease comprising administering to a subject in need of such treatment a therapeutically effective amount of a substantially pure crystalline form of claim 35 , wherein the disease is cutaneous t-cell lymphoma, acute myeloid leukemia, myelodysplastic syndrome or castration-resistant prostate cancer.