Methylene carbamate linkers for use with targeted-drug conjugates

1. A Ligand-Drug Conjugate Compound having the structure of Formula II:

or a pharmaceutically acceptable salt thereof, wherein

L is a Ligand Unit;

Z is a Stretcher Unit;

B is an optional branching unit and is present when subscript t is greater than 1 and is absent when subscript t is 1;

A is an optional Connector Unit;

D is a Drug Unit incorporating a free drug having a hydroxyl; thiol; amine or amide functional group; wherein the functional group has been incorporated into the indicated methylene carbamate unit;

T* is the oxygen; sulfur or optionally substituted nitrogen heteroatom from said functional group;

X is an activateable self-immolative moiety;

R; R 1 and R 2 independently are hydrogen; optionally substituted C 1 −C 6 alkyl; optionally substituted C 6 −C 14 aryl; or optionally substituted C-linked heteroaryl having from 3 to 8 carbon atom ring members and one to four heteroatom ring members independently selected from the group consisting of N, O, P and S; or

wherein R is a Basic Unit wherein the basic functional group of the Basic Unit is an amine or a nitrogen-containing 3, 4, 5, or 6 membered heterocycle, optionally substituted, wherein the heterocycle is C-linked or N-linked, or the basic functional group of the Basic Unit is −N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and C 1 -C 6 alkyl or each R op is methyl;

subscript t ranges from 1 to 4; and

subscript p is an integer ranging from 1 to 16.

2. The Ligand-Drug Conjugate Compound of claim 1 having Formula IIa:

or a pharmaceutically acceptable salt thereof.

3. The Ligand-Drug Conjugate Compound of claim 2 wherein R and R 1 are independently selected from the group consisting of hydrogen, optionally substituted C 1 31 C 6 alkyl and optionally substituted C 6 −C 14 aryl.

4. The Ligand-Drug Conjugate Compound of claim 3 wherein one or more of R, R 1 and R 2 is not substituted.

5. The Ligand-Drug Conjugate Compound of claim 3 wherein the optional substituent is selected from the group consisting of −N(R op ) 2 , −N(R op ) 3 and −C(=NR)N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen, C 1 −C 20 alkyl, C 6 −C 20 aryl, C 3 −C 14 heterocycle, and a protecting group.

6. The Ligand-Drug Conjugate Compound of claim 2 wherein R is a Basic Unit wherein the basic functional group of the Basic Unit is an amine or a nitrogen-containing 3, 4, 5, or 6 membered heterocycle, optionally substituted, wherein the heterocycle is C-linked or N-linked, or the basic functional group of the Basic Unit is −N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and C 1 −C 6 alkyl or each R op is methyl.

7. The Ligand Drug Conjugate Compound of claim 6 wherein the Basic Unit is −CH 2 CH 2 N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and methyl.

8. The Ligand-Drug Conjugate Compound of claim 7 wherein R 1 is hydrogen.

9. The Ligand-Drug Conjugate Compound of claim 8 wherein the free drug has a hydroxyl functional group that has been incorporated into the methylene carbamate unit so that T* represents the oxygen heteroatom from that functional group.

10. The Ligand-Drug Conjugate Compound of claim 9 wherein the free drug is an aliphatic alcohol-containing drug or an aromatic alcohol-containing drug, and wherein attachment of D within the Ligand Drug Conjugate compound is via the oxygen heteroatom of the hydroxyl functional group of the aliphatic or aromatic alcohol, so that T* represents the oxygen atom from that functional group.

11. The Ligand-Drug Conjugate Compound of claim 1 wherein B is absent and subscript t is 1.

12. The Ligand-Drug Conjugate Compound of claim 11 wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A, B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit; and

Y is a self-immolative Spacer Unit,

wherein activation of self-immolation of Y results in release of the free drug.

13. The Ligand-Drug Conjugate Compound of claim 12 wherein activation for self-immolation of Y is by enzymatic cleavage of a covalent bond between W and Y.

14. The Ligand-Drug Conjugate Compound of claim 13 wherein enzymatic cleavage is by a tumor associated protease.

15. The Ligand-Drug Conjugate Compound of claim 14 wherein the tumor associated protease is cathepsin B and W is -Val-Cit-, -Phe-Lys- or -Val-Ala-.

16. The Ligand-Drug Conjugate Compound of claim 15 wherein -W-Y- has the structure of:

wherein the wavy bond to the nitrogen of W indicates covalent linkage to Z, A or B, depending on the presence or absence of A and/or B, and the hash mark (#) indicates covalent attachment of the benzylic carbon of Y to the methylene carbamate unit.

17. The Ligand-Drug Conjugate Compound claim 1 wherein the activateable self-immolative moiety (X) has the structure of formula (ii):

wherein the wavy line indicates covalent attachment of Y to A, B or Z depending on the presence or absence of A and/or B, and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate moiety, and wherein;

W is an Activation Unit; and

Y is a self-immolative Spacer Unit,

wherein activation of self-immolation of Y results in release of the free drug.

18. The Ligand-Drug Conjugate Compound of claim 17 wherein activation for self-immolation of Y is by enzymatic cleavage of a covalent bond between W and Y, wherein enzymatic cleavage is by a glycosidase.

19. The Ligand-Drug Conjugate Compound of claim 18 wherein W is a sugar moiety connected to Y via a glycosidic bond cleavable by a glycosidase for activation of self-immolation of Y, wherein the glycosidase is a glucuronidase.

20. The Ligand-Drug Conjugate Compound of claim 19 wherein −Y(W)− has the structure of:

wherein the wavy line adjacent to the nitrogen of Y indicates covalent attachment of Y to Z, A or B, depending on the presence or absence of A and/or B, and the hash mark (#) indicates covalent attachment of the benzylic carbon of Y to the methylene carbamate unit.

21. The Ligand-Drug Conjugate Compound of claim 1 wherein the Stretcher unit (Z) is comprised of a succinimide moiety or an acid-amide moiety and optionally a Basic Unit, wherein the succinimide or acid-amide moiety is attached to a sulfur atom of the Ligand Unit.

22. The Ligand-Drug Conjugate Compound of claim 21 wherein the Stretcher unit (Z) has the structure of formula Xa′:

wherein the wavy line adjacent to the succinimide ring system indicates covalent attachment to a sulfur atom of the Ligand Unit;

the wavy line adjacent to the carbonyl indicates attachment within the remainder of the Ligand Drug Conjugate Compound;

and R N is −C 2 −C 5 alkylene; wherein the alkylene is substituted by a Basic Unit (BU), wherein BU is −(CH 2 ) x NH 2 , −(CH 2 ) X NHR op ; or −(CH 2 ) x N(R op ) 2 , wherein subscript x is an integer ranging from 1 to 4; and R op is C 1 −C 6 alkyl.

23. The Ligand-Drug Conjugate Compound of claim 21 wherein the Stretcher unit (Z) has the structure of:

wherein the wavy line adjacent to the succinimide ring system indicates covalent attachment to a sulfur atom of the Ligand Unit, and

the wavy line adjacent to the carbonyl indicates attachment to the remainder of the Ligand Drug Conjugate compound.

24. The Ligand-Drug Conjugate Compound of claim 21 wherein the Stretcher unit (Z) has the structure of:

25. The Ligand-Drug Conjugate Compound of claim 24 wherein the Connector Unit (A) is present and has the structure of:

wherein the wavy line adjacent to the carbonyl indicates covalent attachment to the activateable self-immolative moiety X, and

the other wavy line indicates attachment to B, if present, or to Z if B is absent; and

R 13 is −C 1 −C 6 alkylene−, −C 3 −C 8 carbocyclo−, -arylene-, −C 1 −C 10 heteroalkylene−, −C 3 −C 8 heterocyclo−, −C 1 −C 10 alkylene-arylene-, -arylene−C 1 −C 10 alkylene−, −C 1 −C 10 alkylene−(C 3 −C 8 carbocyclo)−, −(C 3 −C 8 carbocyclo)−C 1 −C 10 alkylene−, −C 1 −C 10 alkylene−(C 3 −C 8 heterocyclo)−, or −(C 3 −C 8 heterocyclo)−C 1 −C 10 alkylene−.

26. The Ligand-Drug Conjugate Compound of claim 25 wherein the Connector Unit (A) is present and has the structure of:

27. The Ligand-Drug Conjugate Compound of claim 1 wherein the Ligand Unit is an antibody Ligand Unit.

28. A Ligand-Drug Conjugate composition comprising a plurality of conjugate compounds, each having the structure of Formula (II) of claim 1 in which subscript p is an integer ranging from 1 to 8, wherein the remaining variable groups are as defined in claim 1 ; and a pharmaceutically acceptable carrier.

29. The Ligand-Drug Conjugate Compound of claim 1 ,

wherein the free drug binds to FKBP to inhibit mTOR or calcineurin effector function.

30. The Ligand-Drug Conjugate Compound of claim 29 , wherein the FKBP binding free drug is everolimus, tacrolimus or sirolimus.

31. The Ligand-Drug Conjugate Compound of claim 29 , wherein the Ligand-Drug Conjugate Compound has the structure of:

wherein the Ab-S- moiety is an antibody Ligand Unit; R is hydrogen, ethyl or −CH 2 CH 2 N(CH 3 ) 2 ; and subscript p ranges from 1 to 16 or 1 to 8.

32. The Ligand-Drug Conjugate Compound of claim 1 , wherein the Drug Unit incorporates an auristatin free drug having a hydroxyl functional group, wherein the functional group has been incorporated into the indicated methylene carbamate unit of Formula (II);

T* is the oxygen heteroatom from said functional group; and

wherein the free auristatin drug binds to tubulin to disrupt tubulin function.

33. The Ligand-Drug Conjugate Compound of claim 32 wherein the auristatin free drug is MMAE or auristatin T.

34. A method of treating cancer or an autoimmune disease comprising administering to a subject in need thereof, an effective amount of a Ligand-Drug Conjugate composition of claim 28 , wherein the cancer is Hodgkin's disease, prostate cancer, melanoma, renal cell (kidney) cancer, non-Hodgkin's disease, or erythroleukemia.

35. The Ligand-Drug Conjugate Compound of claim 33 wherein the compound has the structure of:

or a pharmaceutically acceptable salt thereof, wherein the Ab-S- moiety is an antibody Ligand Unit; subscript p is 4; and the Ab-S antibody Ligand Unit is of the chimeric antibody cAC10.

36. The Ligand-Drug Conjugate Compound of claim 2 , wherein R is a Basic Unit, wherein the basic functional group of the Basic Unit is −N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and C 1 −C 6 alkyl.

37. The Ligand-Drug Conjugate Compound of claim 2 , wherein R is a Basic Unit, wherein the basic functional group of the Basic Unit is −N(R op ) 2 , wherein one R op is hydrogen and the other R op is methyl, or both R op are methyl.

38. The Ligand-Drug Conjugate Compound of claim 14 , wherein the tumor associated protease is cathepsin B.

39. The Ligand-Drug Conjugate Compound of claim 14 , wherein W is -Val-Cit-, -Phe-Lys-, or -Val-Ala-.

40. The Ligand-Drug Conjugate Compound of claim 25 , wherein R 13 is −C 1 −C 6 alkylene−.

41. The Ligand-Drug Conjugate Compound of claim 1 , wherein subscript p is an integer ranging from 1 to 8.

42. The Ligand-Drug Conjugate Compound of claim 1 , wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is present and has the structure of:

wherein subscript p is an integer ranging from 1 to 8.

43. The Ligand-Drug Conjugate Compound of claim 1 , wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is absent; and

wherein subscript p is an integer ranging from 1 to 8.

44. The Ligand-Drug Conjugate Compound of claim 2 , wherein R is a Basic Unit having the structure −CH 2 CH 2 N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and methyl;

wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is present and has the structure of:

wherein subscript p is an integer ranging from 1 to 8.

45. The Ligand-Drug Conjugate Compound of claim 2 , wherein R is a Basic Unit having the structure −CH 2 CH 2 N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and methyl;

wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is absent; and

wherein subscript p is an integer ranging from 1 to 8.

46. The Ligand-Drug Conjugate Compound of claim 12 , wherein Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C1−C6 alkyl, −O−(C 1 −C 6 alkyl), halogen, nitro, or cyano; and

m is an integer ranging from 0 to 4.

47. The Ligand-Drug Conjugate Compound of claim 2 ,

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A, B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

wherein Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl, −O−(C 1 −C 6 alkyl), halogen, nitro, or cyano; and

m is an integer ranging from 0 to 4.

48. The Ligand-Drug Conjugate Compound of claim 42 , wherein

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A, B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl, −O−(C 1 −C 6 alkyl), halogen, nitro, or cyano; and

m is an integer ranging from 0 to 4.

49. The Ligand-Drug Conjugate Compound of claim 43 , wherein

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A, B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl, −O−(C 1 −C 6 alkyl), halogen, nitro, or cyano; and

m is an integer ranging from 0 to 4.

50. The Ligand-Drug Conjugate Compound of claim 1 ,

wherein R is a Basic Unit having the structure −CH 2 CH 2 N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and methyl;

wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is present and has the structure of:

wherein subscript p is an integer ranging from 1 to 8;

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A, B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl; −O−(C 1 −C 6 alkyl); halogen, nitro; or cyano; and

m is an integer ranging from 0 to 4.

51. The Ligand-Drug Conjugate Compound of claim 2 ;

wherein R is a Basic Unit having the structure −CH 2 CH 2 N(R op ) 2 ; wherein each R op is independently selected from the group consisting of hydrogen and methyl;

wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is absent;

wherein subscript p is an integer ranging from 1 to 8;

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A, B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl, −O−(C 1 −C 6 alkyl), halogen, nitro, or cyano; and

m is an integer ranging from 0 to 4.

52. The Ligand-Drug Conjugate Compound of claim 1 ,

wherein B is absent and t is 1;

R is a Basic Unit having the structure −CH 2 CH 2 N(R op ) 2 , wherein each R op is independently selected from the group consisting of hydrogen and methyl;

wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is present and has the structure of:

wherein subscript p is an integer ranging from 1 to 8;

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A; B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl; −O−(C 1 −C 6 alkyl); halogen; nitro; or cyano; and

m is an integer ranging from 0 to 4.

53. The Ligand-Drug Conjugate Compound of claim 2 ;

wherein B is absent and t is 1;

R is a Basic Unit having the structure −CH 2 CH 2 N(R op ) 2 ; wherein each R op is independently selected from the group consisting of hydrogen and methyl;

wherein the Stretcher unit (Z) has the structure of:

wherein the Connector Unit (A) is absent;

wherein subscript p is an integer ranging from 1 to 8;

wherein the activateable self-immolative moiety (X) has the structure of formula (i)

wherein the way line indicates covalent attachment of W to A; B or Z depending on the presence or absence of A and/or B and the asterisk (*) indicates covalent attachment of Y to the methylene carbamate unit and wherein;

W is an Activation Unit;

Y has the structure:

wherein the wavy line indicates covalent attachment to the Activation Unit (W) and the hashtag (#) indicates covalent attachment of the benzylic carbon to the methylene carbamate unit;

wherein Q is C 1 −C 6 alkyl, −O−(C 1 −C 6 alkyl), halogen, nitro, or cyano; and

m is an integer ranging from 0 to 4.