Cytotoxic benzodiazepine derivatives

1. A method of treating a cancer in a mammal comprising administering to said mammal a therapeutically effective amount of a conjugate comprising a cytotoxic compound and a cell binding agent (CBA), wherein the cytotoxic compound comprises a linking group which covalently links the cytotoxic compound to the CBA, and wherein said cytotoxic compound represented by the following structural formula:

or a pharmaceutically acceptable salt thereof, wherein:

the double line between N and C represents a single bond or a double bond, provided that when it is a double bond X is absent and Y is —H, or a linear or branched alkyl having 1 to 4 carbon atoms, and when it is a single bond, X is —H, the linking group, or an amine protecting moiety;

Y is a leaving group selected from —OR, —OCOR′, —OCOOR′, —OCONR′R″, —NR′R″, —NR′COR″, —NR′NR′R″, an optionally substituted 5- or 6-membered nitrogen-containing heterocycle, a guanidinum represented by —NR′(C═NH)NR′R″, an amino acid, or a peptide represented by —NRCOP′, wherein P′ is an amino acid or a polypeptide containing between 2 to 20 amino acid units, —SR, —SOR′, —SO 2 M, —SO 3 M, —OSO 3 M, halogen, cyano and an azido;

M is —H or a cation;

R, for each occurrence, is independently selected from the group consisting of —H, an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit —(CH 2 CH 2 O) n —R c , an optionally substituted aryl having 6 to 18 carbon atoms, an optionally substituted 5- to 18-membered heteroaryl ring containing one or more heteroatoms independently selected from nitrogen, oxygen, and sulfur, or an optionally substituted 3- to 18-membered heterocyclic ring containing 1 to 6 heteroatoms independently selected from O, S, N and P;

R′ and R″ are each independently selected from —H, —OH, —OR, —NHR, —NR 2 , —COR, an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit —(CH 2 CH 2 O) n —R c , and an optionally substituted 3-18-membered heterocyclic ring having 1 to 6 heteroatoms independently selected from O, S, N and P;

R c is —H or an optionally substituted linear or branched alkyl having 1 to 4 carbon atoms, or the linking group;

n is an integer from 1 to 24;

X′ is selected from —H, an amine-protecting group, the linking group, an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit —(CH 2 CH 2 O) n —R c , an optionally substituted aryl having 6 to 18 carbon atoms, an optionally substituted 5- to 18-membered heteroaryl ring containing one or more heteroatoms independently selected from nitrogen, oxygen, and sulfur, and an optionally substituted 3- to 18-membered heterocyclic ring containing 1 to 6 heteroatoms independently selected from O, S, N and P;

Y′ is selected from —H, an oxo group, the linking group, an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, an optionally substituted 6- to 18-membered aryl, an optionally substituted 5- to 18-membered heteroaryl ring containing one or more heteroatoms independently selected from nitrogen, oxygen, and sulfur, an optionally substituted 3 to 18-membered heterocyclic ring having 1 to 6 heteroatoms;

R 6 is —H, —R, —OR, —SR, —NR′R″, —NO 2 , halogen or the linking group;

A and A′ are the same or different, and are independently selected from —O—, oxo (—C(═O)—), —CRR′O—, —CRR′—, —S—, —CRR′S—, —N(R 5 )— and —CRR′N(R 5 )—,

R 5 for each occurrence is independently —H or an optionally substituted linear or branched alkyl having 1 to 10 carbon atoms;

L′, L″, and L′″ are the same or different, and are independently selected from —H, an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit —(OCH 2 CH 2 ) n —R c , halogen, guanidinium [—NH(C═NH)NH 2 ], —OR, —NR′R″, —NO 2 , —NR′COR″, —SR, a sulfoxide represented by —SOR′, a sulfone represented by —SO 2 R′, a sulfonate —SO 3 M, a sulfate —OSO 3 M, a sulfonamide represented by —SO 2 NR′R″, cyano, an azido, —COR′, —OCOR′, —OCONR′R″ and the linking group, provided only one of L′, L″, and L′″ is the linking group; and

G is selected from —CH— or —N—,

provided that the compound is not any one of the following compounds:

wherein the cancer is selected from the group consisting of leukemia, lymphoma, multiple myeloma, cervical cancer, non-small cell lung cancer, small-cell lung cancer, head and neck cancer and colon cancer; and

the optional substituent described above is a linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, aryl, heteroaryl, heterocycyclyl, halogen, —NH(C═NH)NH 2 , —OR 100 , NR 101 R 102 , —NO 2 , —NR 101 COR 102 , —SR 100 , —SOR 101 , —SO 2 R 101 , —SO 3 M, —OSO 3 M, —SO 2 NR 101 R 102 , cyano, an azido, —COR 101 , —OCOR 101 , —OCONR 101 R 102 and a polyethylene glycol unit (—OCH 2 CH 2 ) n R 101 wherein M is H or a cation; R 100 , R 101 , R 102 and R 103 are each independently selected from the group consisting of H, linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms, a polyethylene glycol unit (—OCH 2 CH 2 ) n —R 104 , an aryl having from 6 to 10 carbon atoms, a heterocyclic ring having from 3 to 10 carbon atoms and a heteroaryl having 5 to 10 carbon atoms; n is an integer from 1 to 24, and R 104 is H or a linear or branched alkyl having 1 to 4 carbon atoms, wherein the alkyl, alkenyl, alkynyl, aryl, heteroaryl and heterocyclcyl in the groups represented by R 100 , R 101 , R 102 , R 103 and R 104 are optionally substituted with one or more substituents independently selected from the group consisting of halogen, —OH, —CN, —NO 2 and unsubstituted linear or branched alkyl having 1 to 4 carbon atoms.

2. The method of claim 1 , wherein L′ is the linking group, and L″ and L′″ are —H.

3. The method of claim 2 , wherein A and A′ are both —O—, R 6 is —OMe, and G is —CH—.

4. The method of claim 3 , wherein L′ is represented by the following formula:

—W′—R x —V—R y -J,

wherein:

W′ and V are the same or different, and are each independently absent, or selected from —CR e R e′ —, —O—, —O—C(═O)—, —C(═O)—O—, —S—, —SO—, —SO 2 —, —CH 2 —S—, —CH 2 O—, —CH 2 NR e —, —O—(C═O)O—, —O—(C═O)N(R e )—, —N(R e )—, —N(R e )—C(═O)—, —C(═O)—N(R e )—, —N(R e )—C(═O)O—, —N(C(═O)R e )C(═O)—, —N(C(═O)R e )—, —(O—CH 2 —CH 2 ) n —, —SS—, or —C(═O)—, or an amino acid, or a peptide having 2 to 8 amino acids;

R x and R y are the same or different, and are each independently absent or an optionally substituted linear, branched or cyclic alkyl, alkenyl, or alkynyl having 1 to 10 carbon atoms, an aryl bearing 6 to 10 carbon atoms or a 3- to 8-membered heterocyclic ring bearing 1 to 3 heteroatoms selected from O, N or S;

R e and R e′ are the same or different, and are selected from —H, a linear, branched or cyclic alkyl, alkenyl, or alkynyl having 1 to 10 carbon atoms or —(CH 2 —CH 2 —O) n —R k , wherein R k is a —H, a linear, branched cyclic alkyl having 1 to 6 carbon atoms, optionally bearing a secondary amino (—NHR 101 ) or tertiary amino (—NR 101 R 102 ) group or a 5- or 6-membered nitrogen containing heterocycle, such as piperidine or morpholine, wherein R 101 and R 102 are each independently a linear, branched, or cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms; preferably, R 101 and R 102 are each independently a linear or branched alkyl having 1 to 6 carbon atoms;

n is an integer from 1 to 24; and

J is covalently linked to the CBA, and is selected from a succinimide, a acetamido, —S—, —SS—, —CH 2 S—, —CH(Me)S—, —C(Me) 2 S—, —NR c1 —, —CH 2 NR c1 —, —NR c1 N—, and —C(═O)—, wherein R c1 is —H or an optionally substituted linear or branched alkyl having 1 to 4 carbon atoms.

5. The method of claim 4 , wherein:

W′ is —O—, —N(R e )— or —N(R e )—C(═O)—;

R e is —H, -Me, or —(CH 2 —CH 2 —O) n -Me;

n is an integer from 2 to 6;

R x is linear or branched alkyl bearing 1 to 6 carbon atoms;

V and R y are absent; and

J is —C(═O)—.

6. The method of claim 1 , wherein the compound is represented by the following formula:

or a pharmaceutically acceptable salt thereof, wherein:

W′ is absent, or selected from —O—, —N(R e )—, —N(R e )—C(═O)—, —N(C(═O)R e )—, —S—, —CH 2 —S—, or —CH 2 NR e —;

R x is absent or selected from a linear, branched or cyclic alkyl having 1 to 10 carbon atoms;

R e is —H, a linear, branched or cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms or —(CH 2 —CH 2 —O) n —R k , wherein R k is a —H, a linear, branched cyclic alkyl having 1 to 6 carbon atoms, optionally bearing a secondary amino (—NHR 101 ) or tertiary amino (—NR 101 R 102 ) group or a 5 or 6-membered nitrogen containing heterocycle, such as piperidine or morpholine, wherein R 101 and R 102 are each independently a linear, branched, or cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms;

n is an integer from 2 to 6;

Z s is linked to the CBA, and is selected from:

a bond;

wherein:

q is an integer from 1 to 5; and,

M is —H or a cation, such as Na + or K + .

7. The method of claim 6 , wherein W′ is —N(R e )—.

8. The method of claim 7 , wherein R e is —(CH 2 —CH 2 —O) n —R k , wherein R k is a —H, a linear, branched cyclic alkyl having 1 to 6 carbon atoms.

9. The method of claim 8 , wherein R x is a linear or branched alkyl having 1 to 6 carbon atoms.

10. The method of claim 9 , wherein R x is —(CH 2 ) p —(CR f R g )—, wherein R f and R g are each independently selected from H or a linear or branched alkyl having 1 to 4 carbon atoms; and p is 0, 1, 2 or 3.

11. The method of claim 10 , wherein R f and R g are the same or different, and are selected from H and Me; and p is 1.

12. The method of claim 6 , wherein:

the double line between N and C represents a single bond or a double bond, provided that when it is a double bond X is absent and Y is —H, and when it is a single bond, X is —H; Y is —OH or —SO 3 M;

M is —H or a pharmaceutically acceptable cation;

X′ and Y′ are both —H;

A and A′ are both —O—;

R 6 is —OMe; and

R x is a linear or branched alkyl having 1 to 6 carbon atoms.

13. The method of claim 1 , wherein the conjugate is represented by the following formula:

or a pharmaceutically acceptable salt thereof,

wherein r is an integer from 1 to 10, Y is —SO 3 M, and M is —H or a pharmaceutically acceptable cation.

14. The method of claim 13 , wherein the conjugate is represented by the following formula:

or a pharmaceutically acceptable salt thereof.

15. The method of claim 14 , wherein M is —H, Na + or K + .

16. The method of claim 14 , wherein the antibody is huMy9-6.

17. The method of claim 1 , wherein the conjugate comprises 1-10 cytotoxic compounds, each cytotoxic compound comprising the linking group linking the cytotoxic compound to the CBA, and each cytotoxic compound on the conjugate is the same.

18. The method of claim 1 , wherein the cell-binding agent binds to target cells selected from tumor cells, virus infected cells, microorganism infected cells, parasite infected cells, autoimmune cells, activated cells, myeloid cells, activated T-cells, B cells, or melanocytes; cells expressing the CD4, CD6, CD19, CD20, CD22, CD30, CD33, CD37, CD38, CD40, CD44, CD56, EpCAM, CanAg, CALLA, or Her-2 antigens; Her-3 antigens; or cells expressing insulin growth factor receptor, epidermal growth factor receptor, and folate receptor.

19. The method of claim 1 , wherein the cell-binding agent is an antibody, a single chain antibody, an antibody fragment that specifically binds to the target cell, a monoclonal antibody, a single chain monoclonal antibody, or a monoclonal antibody fragment that specifically binds to a target cell, a chimeric antibody, a chimeric antibody fragment that specifically binds to the target cell, a domain antibody, a domain antibody fragment that specifically binds to the target cell, a lymphokine, a hormone, a vitamin, a growth factor, a colony stimulating factor, or a nutrient-transport molecule.

20. The method of claim 1 , wherein the antibody is a resurfaced antibody, a resurfaced single chain antibody, or a resurfaced antibody fragment.

21. The method of claim 1 , wherein the antibody is a monoclonal antibody, a single chain monoclonal antibody, or a monoclonal antibody fragment thereof.

22. The method of claim 1 , wherein the antibody is a humanized antibody, a humanized single chain antibody, or a humanized antibody fragment.

23. The method of claim 1 , wherein the cancer is acute myelogenous leukemia (AML).

24. The method of claim 23 , wherein the conjugate is represented by the following formula:

or a pharmaceutically acceptable salt thereof.

25. The method of claim 24 , wherein the antibody is huMy9-6.