AURISTATIN-RELATED COMPOUNDS, CONJUGATED AURISTATIN-RELATED COMPOUNDS, AND METHODS OF USE THEREOF

Abstract

The invention relates generally to novel compounds of the auristatin family, to novel linkers for coupling a payload to another molecule, such a target-binding molecule, to novel linker-toxin molecules, and to novel antibody molecules that allow controlled, site-specific conjugation.

Claims

1. A compound of formula (I): ##STR00031## wherein R1 is a hydrogen or a C.sub.1-6 alkyl group; wherein R is selected from the group consisting of: a hydrogen, a C.sub.1-6 alkyl, a linker, or a group X1-Y1-* wherein * is the point of attachment to the nitrogen; and wherein Y1 is an oxycarbonyl group and X1 is a C.sub.1-6 alkyl group, a 9-fluorenylmethyl group, a benzyl group, or a tert-butyl group.

2. The compound of claim 1, wherein R1 is a methyl group and R is a hydrogen.

3. The compound of claim 1, wherein X1-Y1 is a 9-fluorenylmethoxycarbonyl (Fmoc) group.

4. A compound of formula (II): ##STR00032## wherein R3 is an agent attached to formula (II) where the point of attachment is a nitrogen, sulfur, oxygen, or carbon atom; and wherein R2 is a moiety attached to formula (II) wherein the point of attachment is selected from the group consisting of: a chlorine group, an iodine group, a bromine group, and a thiol group.

5. The compound of claim 4, wherein R2 is a target-binding moiety, wherein the point of attachment at R2 is a thiol group.

6. The compound of claim 5, wherein the thiol group is a side chain thiol group of a cysteine residue.

7. A compound of formula (III): ##STR00033## wherein R2 is a moiety attached to formula (III) wherein the point of attachment is selected from the group consisting of: a chlorine group, an iodine group, a bromine group, and a thiol group.

8. The compound of claim 7, wherein R2 is a target-binding moiety, wherein the point of attachment at R2 is a thiol group.

9. The compound of claim 8, wherein the thiol group is a cysteine side chain thiol group.

10. The compound of any one of claims 4 to 9, wherein the target-binding moiety is an isolated antibody or an antigen binding fragment thereof (AB) that specifically binds to the target.

11. The compound of any one of claims 4 to 9, wherein the target-binding moiety is an activatable antibody that, in an activated state, specifically binds to the target, the activatable antibody comprising: an antibody or an antigen binding fragment thereof (AB) that specifically binds to the target; a masking moiety (MM) coupled to the AB, wherein the MM inhibits the binding of the AB to the target when the activatable antibody is in an uncleaved state; and a cleavable moiety (CM) coupled to the AB, wherein the CM is a polypeptide that functions as a substrate for a protease.

12. The compound of claim 11, wherein the MM has a dissociation constant for binding to the AB that is greater than the dissociation constant of the AB to its target.

13. The compound of claim 11 or claim 12, wherein the MM does not interfere or compete with the AB for binding to its target when the activatable antibody is in a cleaved state.

14. The compound of any one of claims 11 to 13, wherein the MM is a polypeptide of no more than 40 amino acids in length.

15. The compound of any one of claims 11 to 14, wherein the MM polypeptide sequence is different from that of the target sequence.

16. The compound of any one of claims 11 to 15, wherein the MM polypeptide sequence is no more than 50% identical to any natural binding partner of the AB.

17. The compound of any one of claims 10 to 16, wherein the target is selected from the group consisting of CD44, CD147, CD166, ITGa3, ITGb1, PSMA, and SLC34A2.

18. The compound of any one of claims 4 to 6, wherein the agent is selected from the group consisting of auristatin E, monomethyl auristatin F (MMAF), monomethyl auristatin E (MMAE), monomethyl auristatin D (MMAD), maytansinoid DM4, maytansinoid DM1, a calicheamicin, a duocarmycin, a pyrrolobenzodiazepine, and a pyrrolobenzodiazepine dimer.

19. The compound of any one of claims 1 to 3, wherein R is a linker.

20. The compound of claim 19, wherein the linker is a cleavable linker.

21. The compound of claim 19 or claim 20, wherein the linker is linked to a target-binding moiety.

22. The compound of claim 21, wherein the target-binding moiety is an isolated antibody or an antigen binding fragment thereof (AB) that specifically binds to the target.

23. The compound of claim 21, wherein the target-binding moiety is an activatable antibody that, in an activated state, specifically binds to the target, the activatable antibody comprising: an antibody or an antigen binding fragment thereof (AB) that specifically binds to the target; a masking moiety (MM) coupled to the AB, wherein the MM inhibits the binding of the AB to the target when the activatable antibody is in an uncleaved state; and a cleavable moiety (CM) coupled to the AB, wherein the CM is a polypeptide that functions as a substrate for a protease.

24. The compound of any one of claims 21 to 23, wherein the target is selected from the group consisting of CD44, CD147, CD166, ITGa3, ITGb1, PSMA, and SLC34A2.

25. The compound of any one of claims 10 to 23, wherein the antibody or activatable antibody comprises a cysteine residue at Kabat position 328.

26. An IgG1 antibody, wherein position Kabat position 328 is a cysteine.

27. An activatable antibody comprising: an antibody or an antigen binding fragment thereof (AB) that specifically binds to the target; a masking moiety (MM) coupled to the AB, wherein the MM inhibits the binding of the AB to the target when the activatable antibody is in an uncleaved state; and a cleavable moiety (CM) coupled to the AB, wherein the CM is a polypeptide that functions as a substrate for a protease, wherein position Kabat position 328 of the AB is a cysteine.

28. The antibody or claim 26 or the activatable antibody of claim 27, wherein the antibody or the AB specifically binds to a target selected from the group consisting of CD44, CD147, CD166, ITGa3, ITGb1, PSMA, and SLC34A2.

29. A pharmaceutical composition comprising: the compound, antibody, or activatable antibody of any one of claims 1 to 28; and a suitable carrier.

30. A method of conjugating a compound to a polypeptide, the method comprising: conjugating a compound of formula (I) to a polypeptide: ##STR00034## wherein R1 is a hydrogen or a C.sub.1-6 alkyl group; wherein R is selected from the group consisting of: a hydrogen, a C.sub.1-6 alkyl, a linker, or a group X1-Y1-* wherein * is the point of attachment to the nitrogen; and wherein Y1 is an oxycarbonyl group and X1 is a C.sub.1-6 alkyl group, a 9-fluorenylmethyl group, a benzyl group, or a tert-butyl group; wherein at least one equivalent of the compound of formula (I) or a derivative thereof is conjugated to the polypeptide.

31. The method of claim 30, wherein R1 is a methyl group and R is a hydrogen.

32. The method of claim 30, wherein X1-Y1 is a 9-fluorenylmethoxycarbonyl (Fmoc) group.

33. The method of claim 30, wherein R is a linker.

34. The method of claim 33, wherein the linker is a cleavable linker.

35. A method of conjugating a compound to a polypeptide, the method comprising: conjugating a compound formula (III) to a polypeptide: (III), ##STR00035## wherein R2 is a moiety attached to formula (III) wherein the point of attachment is selected from the group consisting of: a chlorine group, an iodine group, a bromine group, and a thiol group.

36. The method of claim 35, wherein the R2 is a halogen group.

37. The method of claim 36, wherein the R2 is an iodine group,

38. The method of claim 36, wherein the R2 is a bromine group.

39. The method of claim 36, wherein the R2 is a chlorine group.

40. The method of any one of claims 30 to 39, wherein at least one compound of formula (I) or (III) is conjugated to the polypeptide via a thiol group on the polypeptide.

41. The method of claim 40, wherein the thiol group is a side chain thiol group of a cysteine residue of the polypeptide.

42. The method of any one of claims 30 to 41, wherein the polypeptide comprises a target-binding moiety.

43. The method of any one of claims 30 to 42, wherein the polypeptide comprises an antibody or an antigen binding fragment thereof (AB) that specifically binds to a target.

44. The method of claim 43, wherein the cysteine residue is at Kabat position 328 of the AB.

45. The method of any one of claims 30 to 44, wherein the method comprises the steps of: (i) reducing the polypeptide with a reducing agent, wherein at least one disulfide group is reduced to a free thiol group; (ii) re-oxidizing the polypeptide with an oxidizing agent without oxidizing the free thiol group; and (iii) conjugating the compound of formula (I) or (III) to the free thiol group.

46. The method of claim 45, wherein the reducing agent is TCEP.

47. A conjugated polypeptide having the formula:
[T]-[L]-[C]; wherein [T] is a target-binding moiety and [L] is a linker moiety; and wherein[C] is a compound comprising a compound of formula (I): ##STR00036## wherein R1 is a hydrogen or a C.sub.1-6 alkyl group; and wherein R is the point of attachment to [L].

48. The conjugated polypeptide of claim 47, wherein R1 is a methyl group.

49. A conjugated polypeptide having the formula:
[T]-[LC]; wherein [T] is a target-binding moiety and [LC] is a linker-toxin; and wherein [LC] is a compound comprising a compound of formula (III): ##STR00037## wherein R2 is the point of attachment to [T].

50. The conjugated polypeptide of claim 47 or claim 48, wherein the linker [L] is a cleavable linker.

51. The conjugated polypeptide of any one of claims 47 to 50, wherein the linker [L] or the linker-toxin [LC] is coupled to the target-binding moiety [T] via a thiol group on the target-binding moiety.

52. The conjugated polypeptide of claim 51, wherein the thiol group is a side chain thiol group of a cysteine residue on the target-binding moiety.

53. The conjugated polypeptide of any one of claims 47 to 52, wherein the target-binding moiety [T] comprises an antibody or an antigen binding fragment thereof (AB) that specifically binds to a target.

54. The conjugated polypeptide of claim 53, wherein the cysteine residue is a cysteine residue at Kabat position 328 of the AB.

55. A method of treating a subject with a disease or disorder comprising: administering to a subject in need thereof an effective amount of a composition comprising the compound of any one of claims 1 to 25, the pharmaceutical composition of claim 29, or the conjugated polypeptide of any one of claims 47 to 54.

56. Use of a compound of any one of claims 1 to 25, a pharmaceutical composition of claim 29, or a conjugated polypeptide of any one of claims 47 to 54 for treating a disease or disorder.

57. A compound of any one of claims 1 to 25, a pharmaceutical composition of claim 29, or a conjugated polypeptide of any one of claims 47 to 54 for use in the preparation of a medicament for treating a disease or a disorder.

58. The method of any one of claims 55 to 57, wherein the disease or disorder is a cancer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a schematic overview of a synthetic path to auristatin species of the present disclosure.

[0021] FIGS. 2A and 2B show graphs depicting the exemplary in vitro stability of a linker of the present disclosure to activated cathepsin B.

[0022] FIGS. 3A and 3B show graphs depicting exemplary in vitro stability of a linker of the present disclosure to activated lysosomes.

[0023] FIG. 4 shows a process flow diagram of an exemplary method of linker-toxin activation and conjugation of the linker-toxin to an antibody.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The present disclosure relates generally to novel compounds of the auristatin family. The present disclosure also generally relates to novel linkers for coupling a payload to another molecule, such a target-binding molecule. The present disclosure also generally relates to novel linker-toxin molecules. Examples of such embodiments are described in the examples below.

[0025] In some embodiments, a target-binding moiety to which compounds of the present disclosure can be conjugated include anti-PSMA antibodies, examples of which are described in the sequences below:

TABLE-US-00001 Table 1 VL CDR Amino Acid Sequences VL CDR1 VL CDR2 VL CDR3 (SEQ ID (SEQ ID (SEQ ID Antibody NO:) NO:) NO:) [Ag]AB-4 SEQUENCE SEQUENCE SEQUENCE cHv75-2a11.G1 (SEQ ID (SEQ ID (SEQ ID (L328C)k NO: 1) NO: 2) NO: 3) RSSQSLLH LGSNRAS MQALQT SDGYNYLD PWT [Ag]AB-5 SEQUENCE SEQUENCE SEQUENCE cHv75-2a7.G1 (SEQ ID (SEQ ID (SEQ ID (C99Y; NO: 4) NO: 5) NO: 6) L328C)k RASQGIS AASSIQS QQANSF NWIA PLT

TABLE-US-00002 TABLE 2 VH CDR Amino Add Sequences VH CDR1 VH CDR2 VH CDR3 (SEQ ID (SEQ ID (SEQ ID Antibody NO:) NO:) NO:) [Ag]AB-4 SE- SE- SE- cHv75- QUENCE QUENCE QUENCE 2a11.Gl (SEQ ID (SEQ ID (SEQ ID (L328C)k NO: 7)  NO: 8) NO: 9) SYDMH VIWYDG VIAART SNKYYA FYYYGM DSLKG DV [Ag]AB-5 SE- SE- SE- cH75- QUENCE QUENCE QUENCE 2a7.G1 (SEQ ID (SEQ ID (SEQ ID (C99Y;k NO: 10) NO: 11) NO: 12) L328C) NYWMS NIKKDGSE EIQLYLOH KFYVDSVKG

TABLE-US-00003 TABLE 3 VL FR Amino Add Sequences VL FR1 VL FR2 VL FR3 VL FR4 (SEQ ID (SEQ ID (SEQ ID (SEQ ID Antibody NO:) NO:) NO:) NO:) [Ag]AB-4 SE- SE- SE- SE- CHV75- QUENCE QUENCE QUENCE QUENCE 2a11.G1 (SEQ ID (SEQ ID (SEQ ID (SEQ ID (1328C)k NO: 13) NO: 14)  NO: 15) NO: 16) DIVMTQSP WYLQK GVPDRFSG FGQGTKV LSLPVTPG SGQSP SGSGTDFT EIKR EPASISC QLLIY LKISRVEA EDVGVYYC SE- SE- SE- SE- [Ag] QUENCE QUENCE QUENCE QUENCE AB-5 (SEQ ID (SEQ ID (SEQ ID (SEQ ID cHv75- NO: 17) NO: 18) NO: 19) NO: 20) 2a7.G1 DIQMTQSP WYQQKP GVPSRFS FGGGTKV (C99Y; SSVSASV GKAPKL GSGSGTD EIKR L328C)k GGRVTITC LIY FTLTISN LQPEDFA SYYC

TABLE-US-00004 TABLE 4 VH FR Amino Acid Sequences VH FR1 VH FR2 VH FR3 VH FR4 (SEQ ID (SEQ ID (SEQ ID (SEQ ID Antibody NO:) NO:) NO:) NO:) [Ag] SE- SE- SE- SE- AB-4 QUENCE QUENCE QUENCE QUENCE cHv75- (SEQ ID (SEQ ID (SEQ ID (SEQ ID 2a11.G1 NO: 21) NO: 22) NO: 23) NO: 24) (L32 QVQLVES WVRQAPGK RFTISRD WGQGTT 8C)k GGGVVQP GLEWVA NSKNTLY VTVSS GRSLRLS LQMNSLR CAASGFT AEDTAVY FS YCAR [Ag] SE- SE- SE- SE- AB-5 QUENCE QUENCE QUENCE QUENCE cHv75- (SEQ ID (SEQ ID (SEQ ID (SEQ ID 2a7.G1 NO: 25) NO: 26) NO: 27) NO: 28) (C99Y; EVQLVES WVRQAP RFTISRD WGQGTL 1328C)k GGGLVQP GKGLE NAKNSLYL VTVSS GGSLRLS WVA QINSLRAE CAASGIT DTAMYYC FS AR

TABLE-US-00005 TABLE 5 VL Domain Amino Add Sequences Variable region (double underline), constant region (dotted underline) Antibody VL (SEQ ID NO:) [Ag] AB-4 cHv75- 2a11.G1 (L328C)k SEQUENCE (SEQ ID NO: 29) [00004] [Ag] AB-5 cHv75- 2a7.G1 (C99Y; L328C)k SEQUENCE (SEQ ID NO: 30) [00005]

TABLE-US-00006 TABLE 6 VH Domain Amino Acid Sequences Variable region (double underline), constant region (dotted underline) Antibody VH (SEQ ID NO:) [Ag] AB-4 cHv75- 2a11.G1 (L328C)k SEQUENCE (SEQ ID NO: 31) [00006] [Ag] AB-5 cHv75- 2a7.G1 (C99Y; L328C)k SEQUENCE (SEQ ID NO: 32) [00007]

TABLE-US-00007 TABLE 7 VL Nucleic Acid Sequences Antibody Nucleotide sequences [Ag]A SEQUENCE B-4 (SEQ ID NO: 33) cHv7 GATATTGTGATGACTCAGTCTCCAC 5- TCTCCCTGCCCGTCACCCCTGGAGA 2a11. GCCGGCCTCCATCTCCTGCAGGTCT G1(L AGTCAGAGCCTCCTGCATAGTGATG 328C) GATACAACTATTTGGATTGGTACCT k GCAGAAGTCAGGGCAGTCTCCACAG CTCCTGATCTATTTGGGTTCTAATC GGGCCTCCGGGGTCCCTGACAGGTT CAGTGGCAGTGGATCAGGCACAGAT TTTACACTGAAAATCAGCAGAGTGG AGGCTGAGGATGTTGGGGTTTATTA CTGCATGCAAGCTCTACAAACTCCG TGGACGTTCGGCCAAGGGACCAAGG TGGAAATCAAACGGACTGTCGCTGC ACCATCTGTCTTCATCTTCCCGCCA TCTGATGAGCAGTTGAAATCTGGAA CTGCCTCTGTTGTGTGCCTGCTGAA TAACTTCTATCCCAGAGAGGCCAAA GTACAGTGGAAGGTGGATAACGCCC TCCAATCGGGTAACTCCCAGGAGAG TGTCACAGAGCAGGACAGCAAGGAC AGCACCTACAGCCTCAGCAGCACCC TGACGCTGAGCAAAGCAGACTACGA GAAACACAAAGTCTACGCCTGCGAA GTCACCCATCAGGGCCTGAGCTCGC CCGTCACAAAGAGCTTCAACAGGGG AGAGTGT [Ag]A SEQUENCE B-5 (SEQ ID NO: 34) cHv7 GACATCCAGATGACCCAGTCTCCTT 5- CTTCCGTGTCTGCATCTGTAGGAGG 2a7.G CAGAGTCACCATCACTTGTCGGGCG 1(C99 AGTCAGGGTATTAGCAACTGGTTAG Y; L3 CCTGGTATCAGCAGAAACCAGGGAA 28) AGCCCCTAAACTCCTGATCTATGCT GCATCCAGTTTGCAAAGTGGGGTCC CATCAAGGTTCAGCGGCAGTGGATC TGGGACAGATTTCACTCTCACCATC AGCAACCTGCAGCCTGAAGATTTTG CAAGTTACTATTGTCAACAGGCTAA CAGTTTCCCCCTCACTTTCGGCGGA GGGACCAAGGTGGAGATCAAACGGA CTGTCGCTGCACCATCTGTCTTCAT CTTCCCGCCATCTGATGAGCAGTTG AAATCTGGAACTGCCTCTGTTGTGT GCCTGCTGAATAACTTCTATCCCAG AGAGGCCAAAGTACAGTGGAAGGTG GATAACGCCCTCCAATCGGGTAACT CCCAGGAGAGTGTCACAGAGCAGGA CAGCAAGGACAGCACCTACAGCCTC AGCAGCACCCTGACGCTGAGCAAAG CAGACTACGAGAAACACAAAGTCTA CGCCTGCGAAGTCACCCATCAGGGC CTGAGCTCGCCCGTCACAAAGAGCT TCAACAGGGGAGAGTGT

TABLE-US-00008 TABLE 8 VH Nucleic Acid Sequences Antibody Nucleotide sequences [Ag]A SEQUENCE B-4 (SEQ ID NO: 35) cHv7 CAGGTGCAGCTGGTGGAGTCTGGGG 5- GAGGCGTGGTCCAGCCTGGGAGGTC 2a11. CCTGAGACTCTCCTGTGCAGCGTCT Gl(L GGATTCACCTTCAGTAGCTATGACA 328C) TGCACTGGGTCCGCCAGGCTCCAGG k CAAGGGGCTGGAGTGGGTGGCAGTT ATTTGGTATGATGGAAGTAATAAAT ACTATGCAGACTCCTTGAAGGGCCG ATTCACCATCTCCAGAGACAATTCC AAGAACACGCTGTATCTGCAAATGA ACAGCCTCAGAGCCGAGGACACGGC TGTGTATTACTGTGCGAGGGTTATA GCAGCTCGTACCTTCTACTACTACG GTATGGACGTCTGGGGCCAAGGGAC CACGGTCACCGTCTCCTCAGCATCC ACCAAGGGCCCATCGGTCTTCCCCC TGGCACCCTCCTCCAAGAGCACCTC TGGGGGCACAGCGGCCCTGGGCTGC CTGGTCAAGGACTACTTCCCCGAAC CGGTGACGGTGTCGTGGAACTCAGG CGCCCTGACCAGCGGCGTGCACACC TTCCCGGCTGTCCTACAGTCCTCAG GACTCTACTCCCTCAGCAGCGTGGT GACCGTGCCCTCCAGCAGCTTGGGC ACCCAGACCTACATCTGCAACGTGA ATCACAAGCCCAGCAACACCAAGGT GGACAAGAAAGTTGAGCCCAAATCT TGTGACAAAACTCACACATGCCCAC CGTGCCCAGCACCTGAACTCCTGGG GGGACCGTCAGTCTTCCTCTTCCCC CCAAAACCCAAGGACACCCTCATGA TCTCCCGGACCCCTGAGGTCACATG CGTGGTGGTGGACGTGAGCCACGAA GACCCTGAGGTCAAGTTCAACTGGT ACGTGGACGGCGTGGAGGTGCATAA TGCCAAGACAAAGCCGCGGGAGGAG CAGTACAACAGCACGTACCGTGTGG TCAGCGTCCTCACCGTCCTGCACCA GGACTGGCTGAATGGCAAGGAGTAC AAGTGCAAGGTCTCCAACAAAGCCT GCCCAGCCCCCATCGAGAAAACCAT CTCCAAAGCCAAAGGGCAGCCCCGA GAACCACAGGTGTACACCCTGCCCC CATCCCGGGAGGAGATGACCAAGAA CCAGGTCAGCCTGACCTGCCTGGTC AAAGGCTTCTATCCCAGCGACATCG CCGTGGAGTGGGAGAGCAATGGGCA GCCGGAGAACAACTACAAGACCACG CCTCCCGTGCTGGACTCCGACGGCT CCTTCTTCCTCTATAGCAAGCTCAC CGTGGACAAGAGCAGGTGGCAGCAG GGGAACGTCTTCTCATGCTCCGTGA TGCATGAGGCTCTGCACAACCACTA CACGCAGAAGAGCCTCTCCCTGTCT CCGGGTAAA [Ag]A SEQUENCE B-5 (SEQ ID NO: 36) cHv7 GAGGTGCAGCTGGTGGAGTCTGGGG 2a7.G GAGGCTTGGTCCAGCCTGGGGGGTC (C99 CCTGAGACTCTCCTGTGCAGCCTCT Y;L3 GGAATCACCTTTAGTAATTATTGGA 28C) TGAGCTGGGTCCGCCAGGCTCCAGG GAAGGGACTGGAGTGGGTGGCCAAC ATAAAGAAAGATGGAAGTGAGAAAT TCTATGTGGACTCTGTGAAGGGCCG ATTCACCATCTCCAGAGACAACGCC AAGAACTCACTGTATCTGCAAATCA ACAGCCTGAGAGCCGAGGACACGGC TATGTATTACTGTGCGAGAGAAATA CAGCTATACCTGCAGCACTGGGGCC AGGGCACCCTGGTCACCGTCTCCTC AGCATCCACCAAGGGCCCATCGGTC TTCCCCCTGGCACCCTCCTCCAAGA GCACCTCTGGGGGCACAGCGGCCCT GGGCTGCCTGGTCAAGGACTACTTC CCCGAACCGGTGACGGTGTCGTGGA ACTCAGGCGCCCTGACCAGCGGCGT GCACACCTTCCCGGCTGTCCTACAG TCCTCAGGACTCTACTCCCTCAGCA GCGTGGTGACCGTGCCCTCCAGCAG CTTGGGCACCCAGACCTACATCTGC AACGTGAATCACAAGCCCAGCAACA CCAAGGTGGACAAGAAAGTTGAGCC CAAATCTTGTGACAAAACTCACACA TGCCCACCGTGCCCAGCACCTGAAC TCCTGGGGGGACCGTCAGTCTTCCT CTTCCCCCCAAAACCCAAGGACACC CTCATGATCTCCCGGACCCCTGAGG TCACATGCGTGGTGGTGGACGTGAG CCACGAAGACCCTGAGGTCAAGTTC AACTGGTACGTGGACGGCGTGGAGG TGCATAATGCCAAGACAAAGCCGCG GGAGGAGCAGTACAACAGCACGTAC CGTGTGGTCAGCGTCCTCACCGTCC TGCACCAGGACTGGCTGAATGGCAA GGAGTACAAGTGCAAGGTCTCCAAC AAAGCCTGCCCAGCCCCCATCGAGA AAACCATCTCCAAAGCCAAAGGGCA GCCCCGAGAACCACAGGTGTACACC CTGCCCCCATCCCGGGAGGAGATGA CCAAGAACCAGGTCAGCCTGACCTG CCTGGTCAAAGGCTTCTATCCCAGC GACATCGCCGTGGAGTGGGAGAGCA ATGGGCAGCCGGAGAACAACTACAA GACCACGCCTCCCGTGCTGGACTCC GACGGCTCCTTCTTCCTCTATAGCA AGCTCACCGTGGACAAGAGCAGGTG GCAGCAGGGGAACGTTTCTCATGCT CCGTGATGCATGAGGCTCTGCACAA CCACTACACGCAGAAGAGCCTCTCC CTGTCTCCGGGTAAA

[0026] In some embodiments, a target-binding moiety to which compounds of the present disclosure can be conjugated include anti-SLC34A2 antibodies, examples of which are described in the sequences below:

TABLE-US-00009 TABLE 9 VL CDR Amino Acid Sequences VL CDR1 VL CDR2 VL CDR3 (SEQ (SEQ (SEQ Antibody ID NO:) ID NO:) ID NO:) [Ag]AB-2 SEQUENCE SEQUENCE SEQUENCE cHv83-3a23. (SEQ ID (SEQ ID (SEQ ID G1(L328C)k NO: 37) NO: 38) NO: 39) RASQSIS VTSSLQS QQSYNT RFLN PIT [Ag]AB-3 SEQUENCE SEQUENCE SEQUENCE cHV83-1b15. (SEQ ID (SEQ ID (SEQ ID G1(L328C)k  NO: 40)  NO: 41)  NO: 42) RASQSI VASS QQSY GTFLN LQS SVPIT

TABLE-US-00010 TABLE 10 VH CDR Amino Acid Sequences VH CDR1 VH CDR2 VH CDR3 (SEQ (SEQ (SEQ Antibody ID NO:) ID NO:) ID NO:) [Ag]AB-2 SEQUENCE SEQUENCE SEQUENCE cHv83- (SEQ ID (SEQ ID (SEQ ID 3a23.G1 NO: 43) NO: 44) NO: 45) (328C)k SYVMH GVSSSG GGITGA DSTFYV PLVFDI DSVKG [Ag]AB-3 SEQUENCE SEQUENCE SEQUENCE cHv83- (SEQ ID (SEQ ID (SEQ ID 1b15.G1 NO: 46) NO: 47) NO: 48) (L328C)k SHIMY GISSNGLS GGRDRV SYYVDSVKG PAVFDY

TABLE-US-00011 TABLE 11 VL FR Amino Acid Sequences VL FR1 VL FR2 VL FR3 VL FR4 (SEQ ID (SEQ ID (SEQ ID (SEQ ID Antibody  NO:) NO:) NO:) NO:) [Ag]AB-2 SEQUENCE SE- SEQUENCE SE- cHv83- (SEQ ID QUENCE (SEQ ID QUENCE 3a23.G1 NO: 49) (SEQ ID NO: 51) (SEQ (L32 DIQMTQS NO: 50) GVPSRFSG ID NO: 8C)k PSSLSAS WYQQKPG SGSGTDFT 52) VGDRVTI KAPKVLIY LTISSLQ FGQGTRL TC PEDFATYYC EIKR [Ag]AB-3 SEQUENCE SEQUENCE SEQUENCE SEQUEN cllv83- (SEQ ID (SEQ ID (SEQ ID CE 1b15.G1 NO: 53) NO: 5 4) NO: 55) (SEQ (L3 DIQMTQS WYQQKPGKA GVPSRFIG ID NO: 28C)k PSSLSAS PKVLIY SGSGTDRL 56) IGDRCTI TISSLQPE FGQGTRL TC DFATYYC EIKR

TABLE-US-00012 TABLE 12 VH FR Amino Acid Sequences VH FR1 VH FR2 VH FR3 VH FR4 (SEQ ID (SEQ ID (SEQ ID NO:) (SEQ ID Antibody NO:) NO:) NO:) [Ag]AB-2 SEQUENCE SE- SE- SE- cHv83- (SEQ ID QUENCE QUENCE QUENCE 3a23.G NO: 57) (SEQ ID (SEQ ID (SEQ ID 1(L3 EVQLV NO: 58)  NO: 59) NO: 60) 28C)k ESGGGL WVRQ RFTISR WGQGTM VQPGGS APGK DNSKNT VTVSS LRLSCA GLEY LYLQMG ASGFTF VS SLRAED S MAVYYC AR Antibody VH FR1 VH FR2 VH FR3 VH FR4 (SEQ ID (SEQ ID (SEQ ID (SEQ ID  NO:) NO:)  NO:) NO:) [Ag]AB-3 SEQUENCE SEQUENCE SEQUENCE SE- cHv83- (SEQ ID (SEQ ID (SEQ ID QUENCE lbl5.G1 NO: 61) NO: 62)  NO: 63) (SEQ ID (L328C) EVQLVE WVRQ RFTISR NO: 64) SGGGW APGK DNSKNL WGQGTL VQPGG GLEY LYVHMG VTVSS SLRLS VS SLKPED CAASG MAMYYC FTFS AR

TABLE-US-00013 TABLE 13 VL Domain Amino Acid Sequences Variable region (double underline), constant region (dotted underline) Antibody VL (SEQ ID NO:) [Ag] AB-2 cHv83- 3a23.G1 (L328C)k SEQUENCE (SEQ ID NO: 65) [00008] [Ag] AB-3 cHv83- 1b15.G1 (L328C)k SEQUENCE (SEQ ID NO: 66) [00009]

TABLE-US-00014 TABLE 14 VH Domain Amino Acid Sequences Variable region (double underline), constant region (dotted underline) Antibody VH (SEQ ID NO:) [Ag] AB-2 cHv83- 3a23.G1 (L328C)k SEQUENCE (SEQ ID NO: 67) [00010] [Ag] AB-3 cHv83- 1b15.G1 (L328C)k SEQUENCE (SEQ ID NO: 68) [00011]

TABLE-US-00015 TABLE 15 VL Nucleic Acid Sequences Antibody Nucleotide sequences [Ag] SEQUENCE AB- (SEQ ID NO: 69) 2 GACATCCAGATGACCCAGTCTCCAT cHv8 CCTCCCTGTCTGCATCTGTAGGAGA 3- CAGAGTCACCATCACTTGCCGGGCA 3a23 AGTCAGAGCATTAGCAGGTTTTTAA .G1 ATTGGTATCAGCAGAAACCAGGGAA (1328 AGCCCCTAAGGTCCTGATCTATGTT C)k ACATCCAGTTTACAAAGTGGGGTCC CATCAAGGTTCAGTGGCAGTGGATC TGGGACAGATTTCACTCTCACCATC AGCAGTCTGCAACCTGAAGATTTTG CAACTTATTACTGTCAACAGAGTTA CAATACCCCTATCACCTTCGGCCAA GGGACACGACTGGAGATTAAACGGA CTGTCGCTGCACCATCTGTCTTCAT CTTCCCGCCATCTGATGAGCAGTTG AAATCTGGAACTGCCTCTGTTGTGT GCCTGCTGAATAACTTCTATCCCAG AGAGGCCAAAGTACAGTGGAAGGTG GATAACGCCCTCCAATCGGGTAACT CCCAGGAGAGTGTCACAGAGCAGGA CAGCAAGGACAGCACCTACAGCCTC AGCAGCACCCTGACGCTGAGCAAAG CAGACTACGAGAAACACAAAGTCTA CGCCTGCGAAGTCACCCATCAGGGC CTGAGCTCGCCCGTCACAAAGAGCT TCAACAGGGGAGAGTGT [Ag] SEQUENCE AB- (SEQ ID NO: 70) 3 GACATCCAGATGACCCAGTCTCCAT cHv CCTCCCTGTCTGCATCTATAGGAGA 83- CAGAGTCACCATCACTTGCCGGGCA 1b15 AGTCAGAGCATTGGCACCTTTTTAA .G1 ATTGGTATCAACAAAAACCAGGGAA (L32 AGCCCCTAAGGTCCTGATCTATGTT SC) GCATCCAGTTTGCAAAGTGGGGTCC k CATCAAGGTTCATTGGCAGTGGATC TGGGACAGATTTCACTCTCACCATC AGCAGTCTGCAACCTGAAGATTTTG CAACTTACTACTGTCAACAGAGTTA CAGTGTTCCGATCACCTTCGGCCAA GGGACACGACTGGAGATTAAACGGA CTGTCGCTGCACCATCTGTCTTCAT CTTCCCGCCATCTGATGAGCAGTTG AAATCTGGAACTGCCTCTGTTGTGT GCCTGCTGAATAACTTCTATCCCAG AGAGGCCAAAGTACAGTGGAAGGTG GATAACGCCCTCCAATCGGGTAACT CCCAGGAGAGTGTCACAGAGCAGGA CAGCAAGGACAGCACCTACAGCCTC AGCAGCACCCTGACGCTGAGCAAAG CAGACTACGAGAAACACAAAGTCTA CGCCTGCGAAGTCACCCATCAGGGC CTGAGCTCGCCCGTCACAAAGAGCT TCAACAGGGGAGAGTGT AGAGGCCAAAGTACAGTGGAAGGTG GATAACGCCCTCCAATCGGGTAACT CCCAGGAGAGTGTCACAGAGCAGGA CAGCAAGGACAGCACCTACAGCCTC AGCAGCACCCTGACGCTGAGCAAAG CAGACTACGAGAAACACAAAGTCTA CGCCTGCGAAGTCACCCATCAGGGC CTGAGCTCGCCCGTCACAAAGAGCT TCAACAGGGGAGAGTGT

TABLE-US-00016 TABLE 16 VH Nucleic Acid Sequences Antibody Nucleotide sequences [Ag] SEQUENCE AB- (SEQ ID NO: 71) 2 GAGGTGCAGCTGGTGGAGTC cHv8 TGGGGGAGGCTTGGTCCAGC 3- CTGGGGGGTCCCTGAGACTC 3a23. TCCTGTGCAGCCTCTGGATT G1 CACCTTCAGTAGTTATGTTA (1328 TGCACTGGGTCCGCCAGGCT C)k CCAGGGAAGGGACTGGAATA TGTTTCAGGTGTTAGTAGTA GTGGGGATAGCACATTTTAT GTAGACTCTGTGAAGGGCAG ATTCACCATCTCCAGAGACA ATTCCAAGAACACGCTTTAT CTTCAAATGGGCAGCCTGAG AGCTGAGGACATGGCTGTGT ATTACTGTGCGAGAGGGGGT ATAACTGGAGCTCCACTGGT TTTTGATATCTGGGGCCAAG GGACAATGGTCACCGTCTCT TCAGCATCCACCAAGGGCCC ATCGGTCTTCCCCCTGGCAC CCTCCTCCAAGAGCACCTCT GGGGGCACAGCGGCCCTGGG CTGCCTGGTCAAGGACTACT TCCCCGAACCGGTGACGGTG TCGTGGAACTCAGGCGCCCT GACCAGCGGCGTGCACACCT TCCCGGCTGTCCTACAGTCC TCAGGACTCTACTCCCTCAG CAGCGTGGTGACCGTGCCCT CCAGCAGCTTGGGCACCCAG ACCTACATCTGCAACGTGAA TCACAAGCCCAGCAACACCA AGGTGGACAAGAAAGTTGAG CCCAAATCTTGTGACAAAAC TCACACATGCCCACCGTGCC CAGCACCTGAACTCCTGGGG GGACCGTCAGTCTTCCTCTT CCCCCCAAAACCCAAGGACA CCCTCATGATCTCCCGGACC CCTGAGGTCACATGCGTGGT GGTGGACGTGAGCCACGAAG ACCCTGAGGTCAAGTTCAAC TGGTACGTGGACGGCGTGGA GGTGCATAATGCCAAGACAA AGCCGCGGGAGGAGCAGTAC AACAGCACGTACCGTGTGGT CAGCGTCCTCACCGTCCTGC ACCAGGACTGGCTGAATGGC AAGGAGTACAAGTGCAAGGT CTCCAACAAAGCCTGCCCAG CCCCCATCGAGAAAACCATC TCCAAAGCCAAAGGGCAGCC CCGAGAACCACAGGTGTACA CCCTGCCCCCATCCCGGGAG GAGATGACCAAGAACCAGGT CAGCCTGACCTGCCTGGTCA AAGGCTTCTATCCCAGCGAC ATCGCCGTGGAGTGGGAGAG CAATGGGCAGCCGGAGAACA ACTACAAGACCACGCCTCCC GTGCTGGACTCCGACGGCTC CTTCTTCCTCTATAGCAAGC TCACCGTGGACAAGAGCAGG TGGCAGCAGGGGAACGTCTT CTCATGCTCCGTGATGCATG AGGCTCTGCACAACCACTAC ACGCAGAAGAGCCTCTCCCT GTCTCCGGGTAAA [Ag] SEQUENCE AB- (SEQ ID NO: 72) 3 GAGGTGCAACTGGTGGAGTC cHv TGGGGGAGGCTGGGTCCAGC 83- CGGGGGGGTCCCTGAGACTC 1b15. TCCTGTGCAGCCTCTGGATT G1 CACCTTCAGTAGTCATATTA (L32 TGTACTGGGTCCGCCAGGCT 8C) CCAGGGAAGGGACTGGAATA k TGTTTCGGGTATTAGCAGTA ATGGACTTAGCTCATATTAT GTTGACTCTGTGAAGGGCAG ATTCACCATCTCCAGAGACA ATTCCAAGAATTTACTGTAT GTTCATATGGGCAGCCTGAA ACCTGAGGACATGGCTATGT ATTACTGTGCGAGAGGGGGC CGGGATAGAGTGCCAGCTGT CTTTGACTACTGGGGCCAGG GAACCCTGGTCACCGTCTCC TCCGCTTCCACCAAGGGCCC ATCGGTCTTCCCCCTGGCAC CCTCCTCCAAGAGCACCTCT GGGGGCACAGCGGCCCTGGG CTGCCTGGTCAAGGACTACT TCCCCGAACCGGTGACGGTG TCGTGGAACTCAGGCGCCCT GACCAGCGGCGTGCACACCT TCCCGGCTGTCCTACAGTCC TCAGGACTCTACTCCCTCAG CAGCGTGGTGACCGTGCCCT CCAGCAGCTTGGGCACCCAG ACCTACATCTGCAACGTGAA TCACAAGCCCAGCAACACCA AGGTGGACAAGAAAGTTGAG CCCAAATCTTGTGACAAAAC TCACACATGCCCACCGTGCC CAGCACCTGAACTCCTGGGG GGACCGTCAGTCTTCCTCTT CCCCCCAAAACCCAAGGACA CCCTCATGATCTCCCGGACC CCTGAGGTCACATGCGTGGT GGTGGACGTGAGCCACGAAG ACCCTGAGGTCAAGTTCAAC TGGTACGTGGACGGCGTGGA GGTGCATAATGCCAAGACAA AGCCGCGGGAGGAGCAGTAC AACAGCACGTACCGTGTGGT CAGCGTCCTCACCGTCCTGC ACCAGGACTGGCTGAATGGC AAGGAGTACAAGTGCAAGGT CTCCAACAAAGCCTGCCCAG CCCCCATCGAGAAAACCATC TCCAAAGCCAAAGGGCAGCC CCGAGAACCACAGGTGTACA CCCTGCCCCCATCCCGGGAG GAGATGACCAAGAACCAGGT CAGCCTGACCTGCCTGGTCA AAGGCTTCTATCCCAGCGAC ATCGCCGTGGAGTGGGAGAG CAATGGGCAGCCGGAGAACA ACTACAAGACCACGCCTCCC GTGCTGGACTCCGACGGCTC CTTCTTCCTCTATAGCAAGC TCACCGTGGACAAGAGCAGG TGGCAGCAGGGGAACGTCTT CTCATGCTCCGTGATGCATG AGGCTCTGCACAACCACTAC ACGCAGAAGAGCCTCTCCCT GTCTCCGGGTAAA

Example 1: Exemplary Preparation of Auristatin Species

[0027] This example provides an exemplary method of preparation of the compound of MMATH (molecule 14), a monomethylauristatin molecule with thiophenylmethyl and hydroxymethyl substituents. A schematic overview of the synthetic preparation of this molecule is depicted in FIG. 1.

##STR00012##

[0028] Referring to the reaction outlined in Scheme 1, to a stirred (0° C.) suspension of Ala(2-TH)-OH (molecule 1; 50.04 g, 0.29 mol) in MeOH (500.00 mL) was added SOCl.sub.2 (100.07 mL, 1.38 mol) over 2 hours. The mixture was stirred at 23° C. After 17 h, volatile things were evaporated under reduced pressure. The residue was dried further for 144 hours. Ala(2-Th)-OMe_HCl was obtained (molecule 2). HPLC rt=0.59 min (standard method), ESI [M+H]+ 186.2.

##STR00013##

[0029] Referring to the reaction outlined in Scheme 2, to a stirred (23° C.) suspension of Ala(2-Th)-OMe_HCl (molecule 2: 64.43 g, 0.29 mol), Boc-Dap-OH_DCHA (molecule 3: 163.64 g, 0.35 mol), WSC_HCl (67.25 g, 0.35 mol) and HOBt_H2O (42.77 g, 0.28 mol) in DCM (1.00 L) was added Et.sub.3N (49.00 mL, 0.35 mol). After 18 h, the reaction mixture was filtered through silica gel pad (approximately 500 g) and filter cake was washed with DCM (1 L). The filtrate was concentrated under reduced pressure until remain was about 500 mL. Undissolved materials were filtered and filter cake was washed with DCM (100 mL). To the filtrate was added 1.0 M HCl aq. (500 mL) and then the mixture was stirred for 30 minutes. After undissolved materials were filtered, the filtrate was separated. The separated organic layer was added 1.0 M HCl aq. (500 mL) again and then the mixture was stirred for 30 minutes. After separation, the organic layer was washed with sat. NaHCO3 aq. (500 mL), Brine (500 mL) and dried over MgSO4. After the organic layer was filtered, the filtrate was concentrated under reduced pressure. The residue was dried further for 3 hours. To the crude material was added AcOEt (200 mL) and then the mixture was heated to 80° C. (internal temperature). The mixture was filtered through Cellite before the filtrate was concentrated under reduce pressure. To the residue was added AcOEt (150 mL) and then the mixture was heat to 80° C. (internal temperature) until materials were dissolved. The mixture was left stand at ambient temperature. After 24 hours, the mixture was filtered and the solid was washed with 50 mL of a 10:1 mixture of Hexane/AcOEt two times. The solid was dried further for 14 hours. Boc-Dap-Ala(2-Th)-OMe (molecule 4; 92.30 g, 0.20 mol) was obtained. HPLC rt=1.52 min (standard method), ESI [M+H]+ 455.2.

##STR00014##

[0030] Referring to Scheme 3; under ice-bath cooling, to a stirred solution of LAH (8.25 g, 0.22 mol) in THF (500.00 mL) was added Boc-Dap-Ala(2-Th)-OMe (molecule 4; 39.10 g, 0.09 mol) in THF (100 mL) with maintaining the inner temperature below 5° C. over 2 hours. The reaction mixture was stirred at the same temperature (inner temp; 5° C.). After 5 min, under ice-bath cooling, to the mixture were added H.sub.2O (8.5 mL) slowly, 15% NaOH aq (8.5 mL) and H.sub.2O (25.5 mL) in this order. The mixture was stirred at ambient temperature for 16 hours. The mixture was filtered through a Celite pad and then filter cake was washed with 100 mL of AcOEt three times. The filtrate was concentrated under reduced pressure. The residue was dried further for 4 hours. To the crude material was added Toluene (110 mL) and then the mixture was heated to 60° C. until all materials were dissolved. The mixture was left stand at ambient temperature. After 24 hours, the mixture was filtered and then the solid was washed with 50 mL of Toluene two times and dried further for 15 hours. Boc-Dap-Ala(2-Th)-CH.sub.2OH (molecule 5; 28.43 g, 0.07 mol) was obtained. HPLC rt=1.38 min (standard method), ESI [M+H]+ 427.3.

##STR00015##

[0031] Referring to the reaction outlined in Scheme 4, to a stirred (23° C.) solution of Boc-Dap-Ala(2-Th)-CH.sub.2OH (molecule 5; 19.42 g, 0.05 mol) in MeOH (100.00 mL) was added HCl/dioxane (91.00 mL, 0.36 mol). After 2 h, volatile things were evaporated under reduced pressure. To the residue was added AcOEt (250 mL) and then the mixture was concentrated in vacuo. This process was repeated twice. The residue was dried further for 20 hours. To the crude material was added 20:1 mixture of ACN/H.sub.2O (38 mL). The mixture was heated to 70° C. (internal temperature) until all materials were dissolved, then the mixture was left stand at ambient temperature. After 24 hours, the mixture was filtered and then the solid was washed with 15 mL of ACN two times. The solid was dried further for 8 hours. H-Dap-Ala(2-Th)-CH.sub.2OH_HCl (12.84 g, 0.04 mol) was obtained. HPLC rt=0.60 min (standard method), ESI [M+H]+ 327.2 to a stirred (0° C.) suspension of Ala(2-TH)-OH (50.04 g, 0.29 mol) in MeOH (500.00 mL) was added SOCl.sub.2 (100.07 mL, 1.38 mol) over 2 hours. The mixture was stirred at 23° C. After 17 h, volatile things were evaporated under reduced pressure. The residue was dried further for 144 hours. Ala(2-Th)-OMe_HCl was obtained (molecule 6). HPLC rt=0.59 min (standard method), ESI [M+H]+ 327.2.

##STR00016##

[0032] Referring to the reaction outlined in Scheme 5, to a stirred (20° C.) solution of (2S)-2-{([(9H-fluoren-9-ylmethoxy)carbonyl]amino}-3-methylbutanoic acid (molecule 7; 100.00 g, 294.65 mmol), tert-butyl (3R,4S,5S)-3-methoxy-5-methyl-4-(methylamino)heptanoate (molecule 8; 63.69 g, 245.54 mmol), and 2-chloro-1-methylpyridin-1-ium iodide (106.64 g, 417.42 mmol) in ethyl acetate (2.50 L) ethyl acetate (2.50 L) was added N,N-diisopropylethylamine (154.38 mL, 883.95 mmol) once consistent mixing was achieved. After 16 h, the crude reaction mixture was filtered and washed with EtOAc. The solution was extracted with 1 L of 1 M HCl, followed by 1 L of water, followed by 0.5 L sodium bicarbonate, followed by 0.5 L brine. The combined organic fraction was dried using magnesium sulfate, filtered and concentrated under reduced pressure. tert-butyl (3R,4S,5S)-4-[(2S)-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]amino}-N,3-dimethylbutanamido]-3-methoxy-5-methylheptanoate (molecule 9; 149.00 g, 0.26 mol) was obtained as a pink solid. HPLC rt=1.55 min (standard method), ESI [M+H]+ 581.4.

##STR00017##

[0033] Referring to the reaction outlined in Scheme 6, to a stirred (20° C.) solution of tert-butyl (3R,4S,5S)-4-[(2S)-2-([(9H-fluoren-9-ylmethoxy)carbonyl]amino)-N,3-dimethylbutanamido]-3-methoxy-5-methylheptanoate (molecule 9; 143.00 g, 246.23 mmol) in ethyl acetate (200.00 mL) was added diethylamine (200.00 mL, 1,930.63 mmol). After 1 h, the crude mixture was concentrated in vacuo. The residue was dissolved in 200 mL of ethyl acetate then concentrated again. This operation was repeated twice. To the residue was added 50 mL of toluene, then concentrated. The residue was dissolved in 1000 mL of hexane. To the mixture was added 500 mL of 1 M hydrochloric acid and 500 mL of water. The mixture was stirred for 5 min. The biphasic mixture was put into separation funnel and aqueous layer was separated. The organic layer was extracted by 500 mL of 0.1 M hydrochloric acid twice. The combined aqueous layer was washed with 500 mL of hexane twice. To the aqueous layer was added potassium carbonate to adjust pH over 10. The aqueous solution was put into separation funnel and was extracted by 500 mL of ethyl acetate 3 times. The combined organic layer was washed with 500 mL brine, dried over magnesium sulfate and concentrated in vacuo. tert-butyl (3R,4S,5S)-4-[(2S)-2-amino-N,3-dimethylbutanamido]-3-methoxy-5-methylheptanoate (molecule 10; 66.80 g, 0.19 mol) was obtained as a pink oil. HPLC rt=0.82 min (standard method), ESI [M+H]+ 359.4.

##STR00018##

[0034] Referring to the reaction outlined in Scheme 7, to a stirred (20° C.) solution of (2S)-2-{[(9H-fluoren-9-ylmethoxy)carbonyl](methyl)amino}-3-methylbutanoic acid (molecule 7; 55.00 g, 155.63 mmol), tert-butyl (3R,4S,5S)-4-[(2S)-2-amino-N,3-dimethylbutanamido]-3-methoxy-5-methylheptanoate (molecule 10; 55.79 g, 0.16 mol), and 2-chloro-1-methylpyridin-1-ium iodide (67.59 g, 264.56 mmol) in ethyl acetate (1.50 L) ethyl acetate (1.50 L) was added N,N-diisopropylethylamine (97.85 mL, 560.25 mmol) once consistent mixing was achieved. After 16 h, the yellow precipitate was removed by celite filtration and washed with 100 mL of EtOAc. The filtrate was put into separation funnel and was washed with 200 mL of 1 M hydrochloric acid twice, 200 mL of water, 200 mL of saturated sodium bicarbonate solution twice and brine. The organic layer was dried over magnesium sulfate and concentrated in vacuo. The residue was dried under hi-vac for 24 hours to give Fmoc-MeVal-Val-Dil-OtBu (molecule 11; 103.53 g, 0.15 mol) as a yellow foam. HPLC rt=1.86 min (standard method), ESI [M+H]+ 694.5.

##STR00019##

[0035] Referring to the reaction outlined in Scheme 8, to a stirred (20° C.) solution of hydrochloric acid (57.64 mL, 230.58 mmol) was added tert-butyl (3R,4S,5S)-4-[(2S)-2-[(2S)-2-{([(9H-fluoren-9-ylmethoxy)carbonyl](methyl)amino}-3-methylbutanamido]-N,3-dimethylbutanamido]-3-methoxy-5-methylheptanoate (molecule 11; 20.00 g, 28.82 mmol). After 16 h, the crude mixture was concentrated in vacuo. The residue was suspended in 50 mL of toluene and concentrated in vacuo. This operation was repeated 3 times. The obtained residue was dried under hi-vac for 24 hours to give Fmoc-MeVal-Val-Dil-OH (molecule 12; 18.00 g, 0.03 mol) as a beige foam. HPLC rt=1.58 min (standard method), ESI [M+H]+ 638.6.

##STR00020##

[0036] Referring to the reaction outlined in Scheme 9, to Dap-(2-Th)Ala-CH.sub.2OH_HCl (molecule 5; 3.94 g, 10.86 mmol) were added Fmoc-MeVal-Val-Dil-OH (molecule 12; 6.30 g, 9.88 mmol), EDC_HCl (2.84 g, 14.82 mmol), HOBt (1.51 g, 9.88 mmol) and DIPEA (4.30 mL, 24.69 mmol). The reaction mixture was stirred at 23° C. After stirring for 18 h, to the mixture was added CH.sub.2Cl.sub.2 (100 mL). The mixture was washed with 0.1M HCl aq (100 mL), sat. NaHCO.sub.3 aq. (100 mL), then brine (100 mL). The organic layer was dried with MgSO.sub.4 and solid was removed by filtration. The organic layer was concentrated in vacuo to give Fmoc-MMATH (“monomethylauristatin thiophenylmethyl hydroxymethyl) (molecule 13; 7.63 g, 0.01 mol). HPLC rt=1.63 min (standard method), ESI [M+H]+ 946.8.

##STR00021##

[0037] Referring to the reaction outlined in Scheme 10, to Fmoc-MMATH (molecule 13; 7.13 g, 7.54 mmol) were added EtOAc (100.00 mL), dodecyl mercaptan (3.61 mL, 15.07 mmol) and DBU (0.23 mL, 1.51 mmol). The reaction mixture was stirred at 23° C. After stirring for 18 h, the crude mixture was put into separation funnel and was extracted with 50 mL of 1.0 M hydrochloric acid twice. The combined aqueous layer was washed with 100 mL of ethyl acetate twice. The aqueous solution was moved to a round bottom flask. To the mixture was added potassium carbonate to adjust the pH of the mixture over 10. The aqueous solution was put into separation funnel and was extracted with 100 mL of ethyl acetate twice. The combined organic layer was washed with brine, dried over magnesium sulfate and concentrated in vacuo. The residue was dried under hi-vac for 16 hours to give MMATH (molecule 14; 4.51 g, 0.01 mol) as a colorless foam. HPLC rt=0.95 min (standard method), ESI [M+H]+ 724.7.

Example 2: Exemplary Preparation of Auristatin Linker-Toxin Species

[0038] This example provides an exemplary method of preparation of the compound of MMATH (molecule 14), a thiophenylmethyl hydroxymethyl auristatin molecule, with a linker suitable for coupling to a targeting molecule.

##STR00022##

[0039] Referring to the reaction outlined in Scheme 11, to a stirred 23° C. solution of Boc.sub.2O (137.0 g, 628 mmol) in THF (600 mL) was added H.sub.2N-Cit-OH (molecule 15; 100.0 g, 571 mmol) and NaCO.sub.3H (71.9 g, 856 mmol) in water (600 mL). After 16 h, a precipitate formed and after 20 h the reaction was complete by LCMS analysis. The volatile organics were removed under reduced pressure and the reaction adjusted to pH 4 2 M HCl and extracted with EtOAC (4×750 mL). The combined organic was washed with Brine and dried with MgSO.sub.4. The solution was filtered and concentrated under reduced pressure to yield 77% of molecule 16 as a white solid.

##STR00023##

[0040] Referring to the reaction outlined in Scheme 12, to a stirred 50° C. solution of Boc-Cit (molecule 16, 120.0 g, 436 mmol) in EtOH (600 mL) was added Paba (64.4 g, 523 mmol) and EEDQ (129.3 g, 523 mmol). The solution was stirred for 24 h and the organic solvents were concentrated to 300 mL. The concentrated crude solution is triturated by adding to 1.0 L of EtOAc followed by addition 2.0 L of Hexanes and stirred for 1 h. The white solid was collected by filtration and dried under reduced pressure to obtained molecule 16 in 77% yield.

##STR00024##

[0041] Referring to the reaction outlined in Scheme 13, to a stirred 23° C. solution of Boc-Cit-Paba (molecule 16; 10.0 g, 26.3 mmol) in MeCN (300 mL) was added Im (1.79 g, 26.3 mmol) and then PNP-COCl (7.95 g, 39.4 mmol). After 16 h, the reaction was concentrated under reduced pressure to give a yellow oil. To the oil was added 300 mL of EtOAc and the solution was triturated for 15 minutes. The white precipitate was collected by filtration and the supernatant was concentrated to 50% volume and the second batch triturated for 15 min and collected by filtration. The combined materials were dried under reduced pressure to yield molecule 17 as a white powder in 69% yield.

##STR00025##

[0042] Referring to the reaction outlined in Scheme 14, to a stirred 23° C. solution of Boc-Cit-Paba-PNP (molecule 17; 1.45 g, 2.65 mmol) in DMF (21 mL) was added MMATH (molecule 14; 1.2 g, 1.66 mmol) and HOAt (83.7 mg, 0.55 mmol), and then NMM (0.73 mL, 6.63 mmol). After 72 h the reaction was diluted with EtOAc (200 mL) and washed with 1.0 M HCl (2×100 mL), followed by Sat. NaHCO.sub.3 (1×100 mL) and Brine (1×100 mL). The organic layer was dried with MgSO.sub.4, filtered and concentrated under reduced pressure. The yellow foam was purified by Flash column chromatography on silica gel using 0% to 10% MeOH in EtOAc to give Boc-Cit-Paba-MMATH (molecule 18) as a white foam in 80% yield.

##STR00026##

[0043] Referring to the reaction outlined in Scheme 15, Boc-Cit-Paba-MMATH (molecule 18, 1.2 g, 1.06 mmol) is dissolved in MeCN (6 mL) using 5 min of sonication. To a stirred 23° C. solution of Boc-Cit-Paba-MMATH (molecule 18; 1.2 g, 1.06 mmol) in MeCN (6 mL) is added H.sub.3PO.sub.4 (6 mL). After 16 h, the solution was diluted with water (15 mL) and adjusted to pH 8 with 10 M aq NaOH. The aqueous layer was extracted with DCM (2×100 mL). The combined organics were dried with MgSO.sub.4, filtered and concentrated under reduced pressure to yield Cit-Paba-MMATH (molecule 19) as yellow foam in 98% yield.

##STR00027##

[0044] Referring to the reaction outlined in Scheme 16, to a stirred 0° C. suspension of β-homoVal (molecule 20; 1000 mg, 7.62 mmol) in MeCN (40 mL) was added 4 M NaOH (3.81 mL, 15.25 mmol) followed by slow addition (1 mL/min) of dilute ClAcCl (0.60 mL, 7.55 mmol) in MeCN (10 mL). After 20 min, the reaction was diluted with 1 M HCl (100 mL) and EtOAc (100 mL). The aqueous layer was removed and the organic layer washed with 1 M HCl (3×100 mL) followed by brine (1×100 ml). The organic layer was dried with MgSO.sub.4, filtered and concentrated under reduced pressure. The crude reaction was purified by RP-HPLC with a Phenomex Gemini-NX column using 5% to 98% MeCN in 0.05% aqueous TFA as the eluent. Molecule 21 was obtained as a colorless oil (1.14 g).

##STR00028##

[0045] Referring to the reaction outlined in Scheme 17, to a stirred 0° C. solution of DMTMMT (55 mg, 0.14 mmol) in DMF (0.5 mL) was added DIPEA (100 μL, 0.57 mmol) followed by H2N-Cit-Paba-MMATH (molecule 19; 105 mg, 0.1 mmol). After stirring the reaction for 5 min, ClAc-β-homoVal (molecule 21; 30 mg, 0.14 mmol) was added. After 1 h, the crude solution was purified preparatory RP-HPLC with a Phenomenex Gemini 10μ, C18 110 Å column using 5% to 98% MeCN in 0.05% aqueous TFA as the eluent. MMATH-L-Cl (molecule 22) was obtained as a white powder (114 mg, 91%).

[0046] In other embodiments of the present disclosure, a MMATH linker-toxin combination includes a bromo- and iodo-derivative of molecule 22, where the chloro group is replaced with a bromo group (molecule 23) or an iodo group (molecule 24), where “Payload” represents a toxin. In some embodiments of the present disclosure, the toxin is MMATH (molecule 22) connected via the N-terminal nitrogen.

##STR00029##

[0047] In some embodiments of the present disclosure, the Payload of molecules 23, 24, or 25 can be represented by an agent, such as a toxin.

[0048] In some embodiments of the present disclosure, a compound is represented by molecule 26, wherein Payload represents an agent, such as a toxin, and R represents a target-binding moiety, such as an antibody or antigen-binding thereof, or any other molecule via a free thiol group.

##STR00030##

Example 3: In Vitro Cytotoxicity of Auristatin Species

[0049] In this exemplary study, an in vitro cytotoxicity was used to evaluate the relatively toxicity of MMATIH (a thiophenylmethyl hydroxymethyl derivative of an auristatin), as shown herein as formula (I), an auristatin species of the present disclosure.

[0050] In this assay, the test cells were plated and grown to an appropriate cell density (e.g., 1500 cells/well (50 μL per well) for SW780 cells). The cells were treated with the drug (MMATH or MMAE (monomethylauristatin E)) at concentrations ranging from 10 μM to 10.sup.−4 nM in triplicate for 5 days. On the day 6 endpoint, the cells were incubated with 20 μL of Presto Blue @ 37 C for 2 hr and the signal was read on a Biotek synergy H4 plate reader. After media background was subtracted, the percent survival was calculated and plotted to determine the EC50, as shown in the exemplary results of Table 1.

TABLE-US-00017 TABLE 1 In Vitro Cytotoxicity of Auristatin Species EC50 (nM) Toxin SW780 SKOV3 SW780 HCC1954 PC3 MMAE 0.31 0.19 0.22 0.03 0.24 MMATH 0.38 0.20 0.26 0.03 0.24

[0051] In an exemplary study, the binding of MMAE and MMATH to tubulin was measured, showing a K.sub.D of 69.9 nM (MMAE) and 204.4 nM (MMATH). The exemplary results show that the novel MMATH auristatin species has a comparable toxicity to MMAE. These exemplary results also show that this comparable in vitro efficacy was achieved with a molecule with a lower affinity to tubulin, its presumed molecular target for efficacy.

Example 4: Stability of Linker Species

[0052] In this exemplary study, an in vitro study was used to evaluate the stability of a linker (molecule 26) of the present disclosure compared to a valine-citrulline (vc) linker.

[0053] In this study, relative kinetic rates of cleavage by a variety of cathepsins for two different cysteine-conjugated drug linkers were measured by LCMS. The enzymes (cathepsins B, D, H, K, L, and S) were activated prior to introduction to substrate. One substrate was the auristatin MMAE linked to cysteine via a valine-citrulline-PAB-carboxy linker (CAS No.: 646502-53-6) and the other was the MMATH auristatin of the present disclosure (molecule 14) linked to a cysteine via a linker of molecule 26.

[0054] Two different thiol-linked cysteine-linked auristatins (MMATH-L-Cys and Cys-vc-MMAE) were incubated at 37° C. with pre-activated enzymes over a 48 h time period. Timepoints were aliquoted directly into 2 M, pH 9 Tris buffer to stop enzymatic activity and then immediately frozen to −80° C. AUCs of MS XICs of both free drug and cysteine-linked drug for each were monitored over time. All samples were run on a Thermo LTQ Velos OrbiTrap mass spectrometer using a Dionex LC front end. The amounts of original cysteine-linked drug, free drug, and cleaved “linker” stubs were measured over time.

[0055] Referring to FIGS. 2A and 2B, the exemplary results show that a cysteine-linked to MMATH with the linker of molecule 26 showed a higher stability than the corresponding cysteine-linked to vcMMAE. In results with cathepsins H, D, L, K, and S, the results showed a similar relatively stability between the two linkers for all cathepsins. Cathepsin D and L cleaved at a rate comparable to cathepsin B, while cathepsin H cleaved relatively slower than cathepsin B. Cathepsins K and S cleaved relatively faster than cathepsin B.

[0056] In another exemplary study, the stability of the two cysteine-linked auristatin species were tested in an activated lysosome-derived lysate. In this study, lysosomes were lysed by three consecutive freeze/thaw cycles, followed by 30 min of sonication. The cysteine-linked auristatins were incubated at 37° C. with pre-activated lysosomes over a 24 h time period. In this study, the cysteine-MMATH-L substrate was incubated with a 5× lysosome concentration. Timepoints were taken throughout the incubation and AUCs of MS XICs for both free drug and cys-DL were monitored over time. All samples were run on a Thermo LTQ Velos OrbiTrap mass spectrometer using a Dionex LC front end. The amounts of original cysteine-linked drug, free drug, and cleaved “linker” stubs were measured over time.

[0057] Referring to FIGS. 3A and 3B, the exemplary results show that a cysteine-linked to MMATH with the linker of molecule 26 showed a comparable stability in activated lysosomes than the corresponding cysteine-linked to vcMMAE, even with the former having been treated with a 5× lysosomal concentration, thus indicating about a 5× slower rate of cleavage than vcMMAE linker.

[0058] In a further exemplary study, the stability of the substrates were determined in the presence of four different carboxylesterases (human or mouse CES-1 and CES-1C). In this study, the enzymes were activated prior to substrate introduction and then incubated with the substrate at 37° C. over a 48 h time period. Timepoints were aliquoted directly into 2 M, pH 9 Tris buffer to stop enzymatic activity and then immediately frozen to −80° C. AUCs of MS XICs of both free drug and cysteine-linked drug for each were monitored over time. All samples were run on a Thermo LTQ Velos OrbiTrap mass spectrometer using a Dionex LC front end. The amounts of original cysteine-linked drug, free drug, and cleaved “linker” stubs were measured over time.

[0059] In this study using CES-1 or CES-1C mouse or human carboxylesterases, no cleavage of either substrate was observed by human or mouse CES-1. However, cysteine-vcMMAE was completely cleaved in 48 hrs by both human and mouse CES-1C. For the MMATH-linker of the present disclosure, cleavage by mouse or human CES-1C begin around 12 hours, and at a rate substantially slower than that observed with vcMMAE.

[0060] These exemplary results show that the linker of molecule 26 has a higher stability than the valine-citrulline linker in both activated enzymes and lysosomes. These exemplary results show that the linker-MMATH of molecule 26 has a higher stability than the vcMMAE in both activated enzymes and lysosomes.

Example 5: Novel Antibody Conjugation Site

[0061] In this exemplary study, a leucine residue located in the FG-loop of the human IgG1 heavy chain constant region. For reference, the leucine in question is found in the context of the sequence KVSNKALPAPI (i.e., position 328 Kabat numbering). In the present disclosure, the leucine at this position was site-specifically modified to cysteine, i.e., KVSNKACPAPI.

[0062] In this study, the monoclonal antibody trastuzumab, which specifically binds the target HER2, was modified at this position from leucine to cysteine to determine the suitability for drug conjugation and other effects. A comparison between the native trastuzumab and the modified version of the present disclosure is presented below.

TABLE-US-00018 trastuzumab trastuzumab (L328C) Drag-Antibody Ratio (DAR)  2 1.7 % Unconjugated 36% 1% % Aggregated  5% 8% In vivo Efficacy of ADC 8/8 FcγR1 binding (pM) 239 701 (2.93× reduction) CI q decrease 1.02× reduction 3.4× reduction

[0063] These exemplary results showed a significant decrease in the binding to the Fcγ receptors of the L328C variant of the present disclosure as compared to the original antibody, while resulting in a specific DAR of approximately 2, yet resulting in a highly efficient conjugation i.e. less than 1% conjugated antibody.

[0064] Other Examples of this Mutations as Described Herein (Anti-PSMA and Anti-SLC34A2 Antibodies)

[0065] These exemplary results demonstrate the advantages of using antibodies or activatable antibodies with this site-specific modification, to provide an efficient, controlled site for conjugation with a specific stoichiometry.

Example 6: Exemplary Method of Conjugation

[0066] In this example, an exemplary conjugation method is described to conjugate an auristatin MMATH of the present disclosure to an antibody molecule.

[0067] Referring to the exemplary process flow diagram of FIG. 4, in an exemplary method of the present disclosure, an antibody having a cysteine residue at Kabat position 328 is provided at a concentration of 14 g/L at a pH of 7.2. The antibody solution is filtered and then reduced with the reducing agent tris(2-carboxyethyl)phosphine (TCEP) at a 9:1 TCEP:antibody molar ratio for 80-120 minutes at 20° C. The reaction was filtered by tangential flow filtration (TFF) at 8 diavolumes and recovered at 12 g/L. The antibody was re-oxidized with (L)-dehydroascorbic acid (DHA) at a 10:1 DHA:antibody molar ratio for 90 minutes at 20° C.

[0068] The MMATH linker-toxin compound having a formula (III), where R2 is a chlorine, was activated with sodium iodide. The activated linker-toxin was added to the re-oxidized antibody at a 9:1 linker-toxin:antibody molar ratio for 12-16 hours at 20° C. to allow conjugation of the linker-toxin to the antibody. The reaction mixture was filtered by TFF at 10 diavolumes and recovered at 17 g/L. Analysis of the conjugated antibody showed site-specific conjugation at the Kabat 328 cysteine positions with a DAR of 2.

[0069] These exemplary results showed that the auristatin derivatives of the present disclosure can be conjugated to an antibody in a site-specific manner to provide an antibody-drug conjugate with a DAR of 2.

[0070] These exemplary results also showed that by conjugating the linker-toxin to a site-specific cysteine at Kabat position 328, the conjugation can proceed using an iodine-activated coupling of the linker-toxin to the cysteine thiol group. In this manner, the conjugated product is less susceptible to deconjugation reactions than thiol-maleimide conjugates, the latter of which can more readily be reversed by thiol exchange, resulting in an undesirable release of the linker-toxin. The use of antibodies with site-specific cysteines for linker-toxin conjugation, such as those at Kabat position 328, also provide a conjugated antibody product with a DAR of 2. The use of such antibodies with site-specific cysteine residues, such as those at Kabat position 328, also allow linker-toxin conjugation to the antibody without disruption of the native intra- or interchain disulfide bonds of the antibody.

Other Embodiments

[0071] While the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following.