Cytotoxic and anti-mitotic compounds, and methods of using the same

1. A compound having the following structure (I):

wherein:

R 1 and R 2 are independently H or optionally substituted alkyl, wherein the carbon atoms are optionally substituted with: —OH, —I, —Br, —Cl, —F, —CN, —CO 2 H, —CHO, —COSH, or —NO 2 ; or R 2 and R 5 are fused and form a ring;

R 3 and R 4 are independently H or R; or R 3 and R 4 are joined to form a ring, wherein the ring formed by joining R 3 and R 4 is a three- to seven-member cycloalkyl within the definition of R;

R 5 is R or Ar; or R 5 and R 2 are fused and form a ring;

R 6 is H or R;

R 7 and R 8 are independently H or R; and

R 9 is:

R is a saturated or unsaturated linear or branched alkyl containing one to ten carbon atoms, or a cycloalkyl or heterocyclyl containing three to ten carbon atoms and zero to four nitrogen atoms, and the carbon atoms are optionally independently substituted with: ═O, ═S, OH, —OR 10 , —O 2 CR 10 , —SH, —SR 10 , —SOCR 10 , —NH 2 , —NHR 10 , —N(R 10 ) 2 , —NHCOR 10 , —NR 10 COR 10 , —I, —Br, —Cl, —F, —CN, —CO 2 H, —CO 2 R 10 , —CHO, —COR 10 , —CONH 2 , —CONHR 10 , —CON(R 10 ) 2 , —COSH, —COSR 10 , —NO 2 , —SO 3 H, —SOR 10 , or —SO 2 R 10 , wherein R 10 is a linear or branched one to ten carbon saturated or unsaturated alkyl or a three to ten carbon cycloalkyl;

Y is a linear, saturated or unsaturated, one to six carbon alkyl group, optionally substituted with R, or X;

X is selected from the group consisting of: —OH, —OR, ═O, ═S, —O 2 CR, —SH, —SR, —SOCR, —NH 2 , —NHR, —N(R) 2 , —NHCOR, —NRCOR, —I, —Br, —Cl, —F, —CN, —CO 2 H, —CO 2 R, —CHO, —COR, —CONH 2 , —CONHR, CON(R) 2 , —COSH, —COSR, —NO 2 , —SO 3 H, —SOR, and —SO 2 R;

R 14 is selected from the group consisting of optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, —COR 24 , —CSR 24 , —OR 24 , and —NHR 24 , wherein each R 24 is, independently, alkyl optionally substituted with halogen, —OH or —SH;

or a stereoisomer or pharmaceutically acceptable salt thereof.

2. A compound having the following structure (Ia):

wherein:

R 14 is selected from the group consisting of optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted heteroaryl, —COR 24 , —CSR 24 , —OR 24 , and —NHR 24 , wherein each R 24 is, independently, alkyl optionally substituted with halogen, —OH or —SH;

R 15 is selected from the group consisting of optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl;

R 16 is selected from the group consisting of H and C 1-6 alkyl;

R 17 is selected from the group consisting of H and C 1-6 alkyl;

R 18 and R 30 are independently selected from the group consisting of H, C 1-6 alkyl and —SH, with the proviso that R 18 and R 30 cannot both be H;

R 19 , R 20 , R 21 and R 22 are each independently H or C 1-6 alkyl, wherein at least one of R 19 and R 20 is H; or R 20 and R 21 form a double bond, R 19 is H, and R 22 is H or C 1-6 alkyl; and

R 23 is selected from the group consisting of H and C 1-6 alkyl;

or a stereoisomer or pharmaceutically acceptable salt thereof.

3. A compound having the following structure (Ib):

wherein:

R 26 is selected from the group consisting of optionally substituted alkyl and optionally substituted aryl;

R 27 is selected from the group consisting of optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl;

R 16 is selected from the group consisting of H and C 1-6 alkyl;

R 17 is selected from the group consisting of H and C 1-6 alkyl; and

R 18 is selected from the group consisting of C 1-6 alkyl and —SH,

or a stereoisomer or pharmaceutically acceptable salt thereof.

4. The compound according to claim 2 or 3 , wherein each optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl and optionally substituted heteroaryl is, independently, optionally substituted with ═O, ═S, —OH, —OR 24 , —O 2 CR 24 , —SH, —SR 24 , —SOCR 24 , —NH 2 , —N 3 , —NHR 24 , —N(R 24 ) 2 , —NHCOR 24 , —NR 24 COR 24 , —I, —Br, —Cl, —F, —CN, —CO 2 H, —CO 2 R 24 , —CHO, —COR 24 , —CONH 2 , —CONHR 24 , —CON(R 24 ) 2 , —COSH, —COSR 24 , —NO 2 , —SO 3 H, —SOR 24 or —SO 2 R 24 , wherein each R 24 is, independently, alkyl optionally substituted with halogen, —OH or —SH.

5. The compound according to claim 2 or 3 , wherein each optionally substituted aryl and optionally substituted heteroaryl is, independently, selected from the group consisting of optionally substituted phenyl, optionally substituted naphthyl, optionally substituted anthracyl, optionally substituted phenanthryl, optionally substituted furyl, optionally substituted pyrrolyl, optionally substituted thiophenyl, optionally substituted benzofuryl, optionally substituted benzothiophenyl, optionally substituted quinolinyl, optionally substituted isoquinolinyl, optionally substituted imidazolyl, optionally substituted thiazolyl, optionally substituted oxazolyl, and optionally substituted pyridinyl.

6. The compound according to claim 2 , wherein R 15 is selected from one of the following structures (II), (III), (IV) and (V):

wherein:

Q is CR 25 or N;

Z is C(R 25 ) 2 , NR 25 , S, or O;

wherein in structure (V), one instance of Z is CR 25 or N, and the other instance is (CR 25 ) 2 , NR 25 , S or O; and

each R 25 is, independently, selected from the group consisting of H, —OH, —R 24 , —OR 24 , —O 2 CR 24 , —SH, —SR 24 , —SOCR 24 , —NH 2 , —N 3 , —NHR 24 , —N(R 24 ) 2 , —NHCOR 24 , —NR 24 COR 24 , —R 24 NH 2 , —I, —Br, —Cl, —F, —CN, —CO 2 H, —CO 2 R 24 , —CHO, —COR 24 , —CONH 2 , —CONHR 24 , —CON(R 24 ) 2 , —COSH, —COSR 24 , —NO 2 , —SO 3 H, —SOR 24 and —SO 2 R 24 , wherein each R 24 is, independently, alkyl optionally substituted with halogen, —OH or —SH.

7. The compound according to claim 6 , wherein R 15 is selected from the group consisting of:

8. The compound according to claim 7 , wherein R 15 is:

9. The compound according to claim 3 , wherein R 27 is selected from one of the following structures (II), (III), (IV) and (V):

wherein:

Q is CR 25 or N;

Z is C(R 25 ) 2 , NR 25 , S, or O;

wherein in structure (V), one instance of Z is CR 25 or N, and the other instance is (CR 25 ) 2 , NR 25 , S or O; and

each R 25 is, independently, selected from the group consisting of H, —OH, —R 24 , —OR 24 , —O 2 CR 24 , —SH, —SR 24 , —SOCR 24 , —NH 2 , —N 3 , —NHR 24 , —N(R 24 ) 2 , —NHCOR 24 , —NR 24 COR 24 , —R 24 NH 2 , —I, —Br, —Cl, —F, —CN, —CO 2 H, —CO 2 R 24 , —CHO, —COR 24 , —CONH 2 , —CONHR 24 , —CON(R 24 ) 2 , —COSH, —COSR 24 , —NO 2 , —SO 3 H, —SOR 24 and —SO 2 R 24 , wherein each R 24 is, independently, alkyl optionally substituted with halogen, —OH or —SH.

10. The compound of claim 9 , wherein R 27 is selected from the group consisting of:

11. The compound according to claim 10 , wherein R 27 is:

12. The compound according to any one of claims 2 - 8 , wherein R 16 , R 17 , and R 18 , are each methyl.

13. The compound according to any one of claims 2 - 8 , wherein R 16 is H, R 17 is methyl, and R 18 is methyl.

14. A pharmaceutical composition comprising a compound of any one of claims 1 - 13 , or a stereoisomer or pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, diluent or excipient.

15. A method of inhibiting cancer, relieving cancer, or relieving the symptoms of cancer in a mammal comprising administering to a mammal in need thereof an effective amount of a compound of any one of claims 1 - 13 , or a pharmaceutical composition of claim 14 .

16. A method of inhibiting tumor growth in a mammal comprising administering to a mammal in need thereof an effective amount of a compound of any one of claims 1 - 13 , or a pharmaceutical composition of claim 14 .

17. A method of increasing survival of a mammal having cancer, comprising administering to said mammal an effective amount of a compound of any one of claims 1 - 13 , or a pharmaceutical composition of claim 14 .

18. A composition having the following structure (VI):

(T)-(L)-(D)  (VI)

wherein (T) is a targeting moiety, (L) is a linker, and (D) is the compound according to any one of claims 1 - 13 .

19. A pharmaceutical composition comprising the composition of claim 18 , or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, diluent or excipient.

20. A method of inhibiting cancer, relieving cancer, or relieving the symptoms of cancer in a mammal comprising administering to a mammal in need thereof an effective amount of a composition of claim 18 or a pharmaceutical composition of claim 19 .

21. A method of inhibiting tumor growth in a mammal comprising administering to a mammal in need thereof an effective amount of a composition of claim 18 or a pharmaceutical composition of claim 19 .

22. A method of increasing survival of a mammal having cancer, comprising administering to said mammal an effective amount of a composition of claim 18 or a pharmaceutical composition of claim 19 .

23. The compound according to claim 2 , wherein R 14 is optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl or optionally substituted heteroaryl.

24. The compound according to claim 2 , wherein R 14 is optionally substituted alkyl or optionally substituted aryl.

25. The compound according to claim 2 , wherein R 20 and R 21 form a double bond, R 19 is H, and R 22 is H or C 1 -C 6 alkyl.

26. The compound according to claim 3 , wherein R 27 is optionally substituted phenyl.

27. The compound according to claim 3 , wherein R 26 is optionally substituted aralkyl or optionally substituted phenyl.

28. The compound according to claim 3 , wherein R 26 is optionally substituted aralkyl or optionally substituted phenyl, and R 27 is optionally substituted phenyl.

29. A compound having one of the following structures:

or a stereoisomer or pharmaceutically acceptable salt thereof.

30. The composition according to claim 18 , wherein (L) is a cleavable linker.

31. The composition according to claim 30 , wherein the cleavable linker comprises a self-immolative component.

32. The composition according to claim 18 , wherein (L) comprises sulfosuccinimidyl 6-[3′(2-pyridyldithio)-propionamido]hexanoate (sulfo-LC-SPDP), succinimidyl 4[N-maleimidomethyl]cyclohexane-1-carboxylate (SMCC), p-aminobenzylcarbamoyl (PABC) or maleimidocaproyl-valine-citrulline-PABC (MC-VC-PABC).

33. A composition having the following structure (VI):

(T)-(L)-(D)  (VI)

wherein (T) is a targeting moiety, (L) is a linker, and (D) is a compound selected from:

or a stereoisomer or pharmaceutically acceptable salt thereof.

34. The composition of claim 18 , wherein (T)-(L)-(D) has one of the following structures:

35. The composition according to claim 18 , wherein (T) is a monoclonal antibody or antibody fragment.

36. The composition according to claim 18 , wherein (T) is a bispecific antibody or antibody fragment, or a multispecific antibody or antibody fragment.

37. The compound according to claim 1 , wherein R 14 is optionally substituted alkyl, optionally substituted alkylamino, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heterocyclyl or optionally substituted heteroaryl.

38. The compound according to claim 37 , wherein Y is a linear, saturated or unsaturated, one to six carbon alkyl group, optionally substituted with R.