Sulfonamide-containing linkage systems for drug conjugates

1. A conjugate having the following structure (Ia):

[(P) o -(L)] m -(T)  (Ia)

wherein:

(P) is a microtubule disrupting peptide toxin,

(L) is a linker,

(T) is a targeting moiety that specifically binds to a target antigen, the targeting moiety selected from an antibody and an antigen-binding antibody fragment,

m is an integer from 1 to 10, and

o is an integer from 1 to 20;

wherein:

(P) has structure (XX):

and (L)-(T) has structure (III):

wherein:

P 4 is the remaining portion of (P);

R 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;

each AA is independently an amino acid;

(AA) 1 -(AA) x is a dipeptide, a tripeptide, a tetrapeptide or a pentapeptide;

(L′) is the remaining portion of linker (L) or is absent;

the —NH- group bonded to R in structure (XX) forms a junction peptide bond (JPB) with (AA) 1 in structure (III), and

wherein (AA) 1 -(AA) x taken together forms a protease recognition sequence that facilitates cleavage of the JPB.

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

[(P) o -(L)] m -(T)  (Ia)

wherein:

(P) is a microtubule disrupting peptide toxin,

(L) is a linker,

(T) is a targeting moiety that specifically binds to a target antigen, the targeting moiety selected from an antibody and an antigen-binding antibody fragment,

m is an integer from 1 to 10, and

o is an integer from 1 to 20;

wherein:

(P) has structure (XX):

wherein:

P 4 is the remaining portion of (P);

—R-NH- is selected from the group consisting of:

wherein each n is independently an integer from 0-10;

and (L)-(T) has structure (III):

wherein:

each AA is independently an amino acid;

(AA) 1 -(AA) x is a dipeptide, a tripeptide, a tetrapeptide or a pentapeptide;

(L′) is the remaining portion of linker (L) or is absent;

the —NH- group bonded to R in structure (XX) forms a junction peptide bond (JPB) with (AA) 1 in structure (III), and

(AA) 1 -(AA) x taken together forms a protease recognition sequence that facilitates cleavage of the JPB.

3. The conjugate of claim 2 , wherein —R-NH- is selected from the group consisting of:

4. The conjugate of claim 3 , wherein —R-NH- is selected from the group consisting of:

5. A pharmaceutical composition comprising a conjugate of claim 1 , or a stereoisomer or pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, diluent or excipient.

6. A method of treating cancer in a mammal comprising administering to a mammal in need thereof an effective amount of a conjugate of claim 1 .

7. A method of inhibiting tumor growth in a mammal comprising administering to a mammal in need thereof an effective amount of a conjugate of claim 1 .

8. The conjugate of claim 1 , wherein the antibody or antigen-binding antibody fragment specifically binds to an antigen present on a tumor cell.

9. The conjugate of claim 1 , wherein o is 1.

10. The conjugate of claim 1 , wherein (P) has the following structure (XIV):

wherein:

R 6 and R 7 are independently selected from the group consisting of: H and a saturated or unsaturated moiety having a linear, branched, or non-aromatic cyclic skeleton containing one to ten carbon atoms, and the carbon atoms are optionally substituted with: —OH, —I, —Br, —Cl, —F, —CN, —CO 2 H, —CHO, —COSH, or —NO 2 ; or R 7 and R 10 are fused and form a ring;

R 8 and R 9 are independently selected from the group consisting of: H, R′, and ArR′—, or R 8 and R 9 are joined to form a ring, wherein the ring is a three to seven-member non-aromatic cyclic skeleton within the definition of R′;

R 10 is selected from the group consisting of: H, R′, ArR′—, and Ar;

R 11 is selected from the group consisting of: H, R′, and ArR′—;

R 12 and R 13 are independently selected from the group consisting of: H, R′, and ArR′—;

R 14 is:

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′ is a saturated or unsaturated moiety having a linear, branched, or non-aromatic cyclic skeleton containing one to ten carbon atoms, zero to four nitrogen atoms, zero to four oxygen atoms, and zero to four sulfur atoms, and the carbon atoms are optionally substituted with: ═O, ═S, OH, —OR 16 , —O 2 CR 16 , —SH, —SR 16 , —SOCR 16 , —NH 2 , —NHR 16 , —N(R 16 ) 2 , —NHCOR 16 , —NR 16 COR 16 , —I, —Br, —Cl, —F, —CN, —CO 2 H, —CO 2 R 16 , —CHO, —COR 16 , —CONH 2 , —CONHR 16 , —CON(R 16 ) 2 , —COSH, —COSR 16 , —NO 2 , —SO 3 H, —SOR 16 , or —SO 2 R 16 , wherein R 16 is a linear, branched or cyclic, one to ten carbon saturated or unsaturated alkyl group;

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

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′; and

wherein the —NH— group bonded to R 15 in structure (XIV) forms the junction peptide bond (JPB) with (AA) 1 .

11. The conjugate of claim 1 , wherein (AA) 1 -(AA) X , is Val-Cit, Ala-Phe, Phe-Lys, Val-Ala, Val-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp-Cit, Phe-Arg, Val-Lys(Ac), Phe-Lys(Ac), Me-Val-Cit, Gly-Val-Cit, Pro-Pro-Pro, D-Ala-Phe-Lys, (D)-Val-Leu-Lys, Gly-Gly-Arg, Ala-Ala-Asn, Lys-Ser-Gly-Arg, Gly-Phe-Leu-Gly, Leu-Ser-Gly-Arg, Ala-Leu-Ala-Leu, Gly-Gly-Gly-Arg-Arg, Gly-Lys-Ala-Phe-Arg-Arg or HomoGly-Arg-Ser-Arg-Gly.

12. The conjugate of claim 1 , wherein (AA) 1 -(AA) x , is Val-Cit, Phe-Lys, Val-Lys, Ala-Pro, D-Ala-Phe-Lys or D-Phe-Phe-Lys.

13. The conjugate of claim 1 , wherein (L′) comprises a stretcher moiety and —(AA) 1 -(AA) x -(L′)-(T) has one of the structures (VII) or (VIII):

wherein:

L″ is a remaining portion of linker (L) or is absent, and (S) is the stretcher moiety.

14. The conjugate of claim 1 , wherein L′ comprises one or more alkyloxy units.

15. The conjugate of claim 2 , wherein (P) is a monovalent radical of a compound selected from:

16. The conjugate of claim 2 , wherein (P)-(L)- is a monovalent radical of a compound selected from:

17. The conjugate of claim 1 , wherein (P) has the structure (VI):

wherein:

R 1 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 2 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 3 and R 4 are each independently H or C 1-6 alkyl; and

R 5 is C 1-6 alkyl or —SH, and wherein the —NH— group bonded to R 1 in structure (VI) forms the junction peptide bond (JPB) with (AA) 1 .

18. The conjugate of claim 17 , wherein R 1 is optionally substituted aryl.

19. The conjugate of claim 2 , wherein (P) has the structure (VI):

wherein:

—R 1 —NH— is selected from the group consisting of:

wherein each n is independently an integer from 0 to 10;

R 2 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 3 and R 4 are each independently H or C 1-6 alkyl; and

R 5 is C 1-6 alkyl or —SH, and

wherein the —NH— group bonded to R 1 in structure (VI) forms the junction peptide bond (JPB) with (AA) 1 .

20. The conjugate of claim 19 , wherein —R 1 —NH— is selected from the group consisting of:

21. The conjugate of claim 19 , wherein —R 1 —NH— is selected from the group consisting of:

22. The conjugate of claim 17 , wherein R 2 is selected from the group consisting of:

23. The conjugate of claim 1 , wherein R is optionally substituted aryl.

24. The conjugate of claim 2 , wherein R is optionally substituted aryl.

25. The conjugate of claim 2 , wherein o is 1.

26. The conjugate of claim 2 , wherein the antibody or antigen-binding antibody fragment specifically binds to an antigen present on a tumor cell.

27. The conjugate of claim 2 , wherein (AA) 1 -(AA) x is Val-Cit, Ala-Phe, Phe-Lys, Val-Ala, Val-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp-Cit, Phe-Arg, Val-Lys(Ac), Phe-Lys(Ac), Me-Val-Cit, Gly-Val-Cit, Pro-Pro-Pro, D-Ala-Phe-Lys, (D)-Val-Leu-Lys, Gly-Gly-Arg, Ala-Ala-Asn, Lys-Ser-Gly-Arg, Gly-Phe-Leu-Gly, Leu-Ser-Gly-Arg, Ala-Leu-Ala-Leu, Gly-Gly-Gly-Arg-Arg, Gly-Lys-Ala-Phe-Arg-Arg or HomoGly-Arg-Ser-Arg-Gly.

28. The conjugate of claim 2 , wherein (AA) 1 -(AA) x is Val-Cit, Phe-Lys, Val-Lys, Ala-Pro, D-Ala-Phe-Lys or D-Phe-Phe-Lys.

29. The conjugate of claim 2 , wherein (L′) comprises a stretcher moiety and -(AA) 1 -(AA) x -(L′)-(T) has one of the structures (VII) or (VIII):

wherein:

L″ is a remaining portion of linker (L) or is absent, and

(S) is the stretcher moiety.

30. The conjugate of claim 2 , wherein L′ comprises one or more alkyloxy units.

31. The conjugate of claim 19 , wherein R 2 is selected from the group consisting of:

32. The conjugate of claim 31 , wherein —R 1 —NH- is selected from the group consisting of:

33. The conjugate of claim 19 , wherein (AA) 1 -(AA) X is Val-Cit, Ala-Phe, Phe-Lys, Val-Ala, Val-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Ile-Cit, Trp-Cit, Phe-Arg, Val-Lys(Ac), Phe-Lys(Ac), Me-Val-Cit, Gly-Val-Cit, Pro-Pro-Pro, D-Ala-Phe-Lys, (D)-Val-Leu-Lys, Gly-Gly-Arg, Ala-Ala-Asn, Lys-Ser-Gly-Arg, Gly-Phe-Leu-Gly, Leu-Ser-Gly-Arg, Ala-Leu-Ala-Leu, Gly-Gly-Gly-Arg-Arg, Gly-Lys-Ala-Phe-Arg-Arg or HomoGly-Arg-Ser-Arg-Gly.

34. The conjugate of claim 19 , wherein (AA) 1 -(AA) X is Val-Cit, Phe-Lys, Val-Lys, Ala-Pro, D-Ala-Phe-Lys or D-Phe-Phe-Lys.

35. The conjugate of claim 19 , wherein (L′) comprises a stretcher moiety and —(AA) 1 -(AA) X -(L′)-(T) has one of the structures (VII) or (VIII):

wherein:

L″ is a remaining portion of linker (L) or is absent, and

(S) is the stretcher moiety.

36. The conjugate of claim 19 , wherein L′ comprises one or more alkyloxy units.

37. The conjugate of claim 19 , wherein the antibody or antigen-binding antibody fragment specifically binds to an antigen present on a tumor cell.

38. A pharmaceutical composition comprising the conjugate of claim 2 and a pharmaceutically acceptable carrier, diluent or excipient.