Cytotoxic benzodiazepine derivatives

Abstract

The invention relates to novel benzodiazepine derivatives with antiproliferative activity and more specifically to novel benzodiazepine compounds of formula (I)-(VI). The invention also provides conjugates of the benzodiazepine compounds linked to a cell-binding agent. The invention further provides compositions and methods useful for inhibiting abnormal cell growth or treating a proliferative disorder in a mammal using the compounds or conjugates of the invention.

1 . A cytotoxic compound represented by any one of the following formulas: 
       
         
           
           
               
               
           
         
         or a pharmaceutically acceptable salt thereof, wherein:
 one of L′, L″, and L′″ is represented by the following formula:
   —Z 1 —P—Z 2 —R x -J  (A)
 
 
 
         and the other two 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 —(CH 2 CH 2 O) n —R c , halogen, guanidinium [—NH(C═NH)NH 2 ], —OR, —NR′R″, —NO 2 , —NR′COR″, —SR, —SOR′, —SO 2 R′, —SO 3 H, —OSO 3 H, —SO 2 NR′R″, cyano, an azido, —COR′, —OCOR′, and —OCONR′R″;
 one of the Z 1  and Z 2  is —C(═O)—, and the other is —NR 5 —; 
 P is an amino acid residue or a peptide containing between 2 to 20 amino acid residues; 
 R x  is an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms; 
 J is a moiety comprising a reactive group that is capable of covalently linking the cytotoxic compound to a cell-binding agent; 
 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 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 (e.g., piperidine, tetrahydropyrrole, pyrazole, morpholine, etc. attached through the nitrogen atom), a guanidinum represented by —NR′(C═NH)NR′R″, an amino acid, or a peptide represented by —NRCOP′, —SR, —SOR′, halogen, cyano, azido, —OSO 3 H, sulfite (—SO 3 H or —SO 2 H), metabisulfite (H 2 S 2 O 5 ), mono-, di-, tri-, and tetra-thiophosphate (PO 3 SH 3 , PO 2 S 2 H 2 , POS 3 H 2 , PS 4 H 2 ), thio phosphate ester (R i O) 2 PS(OR i ), R i S—, R i SO, R i SO 2 , R i SO 3 , thiosulfate (HS 2 O 3 ), dithionite (HS 2 O 4 ), phosphorodithioate (P(═S)(OR k′ )(S)(OH)), hydroxamic acid (R k′ C(═O)NOH), and formaldehyde sulfoxylate (HOCH 2 SO 2   − ) or a mixture thereof, wherein R i  is a linear or branched alkyl having 1 to 10 carbon atoms and is substituted with at least one substituent selected from —N(R j ) 2 , —CO 2 H, —SO 3 H, and —PO 3 H; R i  can be further optionally substituted with a substituent for an alkyl described herein; R j  is a linear or branched alkyl having 1 to 6 carbon atoms; R k′  is a linear, branched or cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms, aryl, heterocyclyl or heteroaryl; 
 P′ is an amino acid residue or a polypeptide containing between 2 to 20 amino acid residues, 
 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- to 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; 
 n is an integer from 1 to 24; 
 X′ is selected from —H, an amine-protecting 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, 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 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are each 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 , halogen, guanidinium [—NH(C═NH)NH 2 ], —OR, —NR′R″, —NO 2 , —NCO, —NR′COR″, —SR, —SOR′, —SO 2 R′, —SO 3   − H, —OSO 3 H, —SO 2 NR′R″, cyano, an azido, —COR′, —OCOR′, and —OCONR′R″; 
 R 6  is —H, —R, —OR, —SR, —NR′R″, —NO 2 , or halogen; 
 G is —CH— or —N—; 
 A and A′ are the same or different, and are independently selected from —O—, oxo (—C(═O)—), —CRR′O—, —CRR′—, —S—, —CRR′S—, —NR 5  and —CRR′N(R 5 )—; and 
 R 5  for each occurrence is independently —H or an optionally substituted linear or branched alkyl having 1 to 10 carbon atoms. 
 
       
     
     
         2 . The compound of  claim 1 , wherein one of L′, L″ and L′″ is represented by formula (A), and the others are each independently —H, an linear or branched alkyl having from 1 to 6 carbon atoms, halogen, —OH, (C 1 -C 6 )alkoxy, or —NO 2 . 
     
     
         3 . The compound of any one of  claims 1 - 2 , wherein one of L′, L″ and L′″ is represented by formula (A), and the others are —H. 
     
     
         4 . The compound of  claim 2 , wherein L′ is represented by formula (A); and L″ and L′″ are both —H. 
     
     
         5 . The compound of any one of  claims 1 - 4 , wherein R x  is a linear, branched or cyclic alkyl having 1 to 6 carbon atoms optionally substituted with halogen, —OH, (C 1 -C 3 )alkyl, (C 1 -C 3 )alkoxy, halo(C 1 -C 3 )alkyl, or a charged substituent or an ionizable group Q. 
     
     
         6 . The compound of any one of  claims 1 - 5 , wherein J is a moiety comprising a reactive group selected from the group consisting of NHR c1 , —COOH, and —COE, wherein —COE represents a reactive ester and R c1  is —H or linear or branched alkyl having 1 to 4 carbon atoms optionally substituted with halogen, —OH or (C 1 -C 3 )alkoxy. 
     
     
         7 . The compound of  claim 6 , wherein COE is selected from N-hydroxysuccinimde ester, N-hydroxy sulfosuccinimide ester, nitrophenyl (e.g., 2 or 4-nitrophenyl) ester, dinitrophenyl (e.g., 2,4-dinitrophenyl) ester, sulfo-tetraflurophenyl (e.g., 4-sulfo-2,3,5,6-tetrafluorophenyl) ester, and pentafluorophenyl ester. 
     
     
         8 . The compound of  claim 6 , wherein the reactive group is a N-hydroxysuccinimide ester. 
     
     
         9 . The compound of any one of  claims 1 - 8 , wherein L′ is represented by the following formula:
   —NR 5 —P—C(═O)—(CR a R b ) m -J  (B1);
 
   —NR 5 —P—C(═O)—Cy—(CR a R b ) m′ -J  (B2);
 
   —C(═O)—P—NR 5 —(CR a R b ) m -J  (C1), or
 
   —C(═O)—P—NR 5 -Cy—(CR a R b ) m′ -J  (C2)
 
 wherein:
 J is —COE; 
 R a  and R b , for each occurrence, are each independently —H, (C 1 -C 3 )alkyl or a charged substituent or an ionizable group Q; 
 m is an integer from 1 to 6; 
 m′ is 0 or an integer from 1 to 6; and 
 Cy is a cyclic alkyl having 5 or 6 ring carbon atoms optionally substituted with halogen, —OH, (C 1 -C 3 )alkyl, (C 1 -C 3 )alkoxy, or halo(C 1 -C 3 )alkyl. 
 
 
     
     
         10 . The compound of  claim 9 , wherein R a  and R b  are both H; Cy for formulas (B2) and (C2) is cyclohexane; and R 5  is H or Me. 
     
     
         11 . The compound of  claim 9  or  10 , wherein m′ is 0 or 1. 
     
     
         12 . The compound of any one of  claims 1 - 8 , wherein L′ is represented by the following formula:
   —NR 5 —P—C(═O)—(CR a R b ) m —S-Z s   (B3); or
 
   —C(═O)—P—NR 5 —(CR a R b ) m —S-Z s   (C3),
 
 wherein:
 R a  and R b , for each occurrence, are each independently —H, (C 1 -C 3 )alkyl or a charged substituent or an ionizable group Q; 
 m is an integer from 1 to 6; 
 Z is —H, —SR d , —C(═O)R d1  or is selected from any one of the following formulas: 
 
 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein:
 q is an integer from 1 to 5; 
 n′ is an integer from 2 to 6; 
 U is —H or SO 3 M; 
 M is H + , Na +  or K + ; 
 R d  is a linear or branched alkyl having 1 to 6 carbon atoms or is selected from phenyl, nitrophenyl (e.g., 2 or 4-nitrophenyl), dinitrophenyl (e.g., 2,4-dinitrophenyl), carboxynitrophenyl (e.g., 3-carboxy-4-nitrophenyl), pyridyl or nitropyridyl (e.g., 4-nitropyridyl); and 
 R d1  is a linear or branched alkyl having 1 to 6 carbon atoms. 
 
       
     
     
         13 . The compound of any one of  claims 5 - 9  and  12 , wherein the charged substituent or an ionizable group Q is i) —SO 3 H, —Z′—SO 3 H, —OPO 3 H 2 , —Z′—OPO 3 H 2 , —PO 3 H 2 , —Z′—PO 3 H 2 , —CO 2 H, —Z′—CO 2 H, —NR 11 R 12 , or —Z′—NR 11 R 12 , or a pharmaceutically acceptable salt thereof; or, ii) —N + R 14 R 15 R 16 X −  or —Z′—N + R 14 R 15 R 16 X − ; Z′ is an optionally substituted alkylene, an optionally substituted cycloalkylene or an optionally substituted phenylene; R 14  to R 16  are each independently an optionally substituted alkyl; and X −  is a pharmaceutically acceptable anion. 
     
     
         14 . The compound of  claim 13 , wherein Q is SO 3 H or a pharmaceutically acceptable salt thereof. 
     
     
         15 . The compound of  claim 12 , wherein R a  and R b  are both —H and R 5  is H or Me. 
     
     
         16 . The compound of  claim 12 , wherein —(CR a R b ) m — is —(CH 2 ) m″ —C(Me 2 )— and m″ is an integer from 1 to 5. 
     
     
         17 . The compound of any one of  claims 1 - 16 , wherein P is a peptide containing 2 to 10 amino acid residues. 
     
     
         18 . The compound of  claim 17 , wherein P is a peptide containing 2 to 5 amino acid residues. 
     
     
         19 . The compound of  claim 18 , wherein P is selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Lle-Cit, Trp, Cit, Phe-Ala, Phe-N 9 -tosyl-Arg, Phe-N 9 -nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu, -Ala-Leu-Ala-Leu and Gly-Phe-Leu-Gly, Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, and Met-Ala. 
     
     
         20 . The compound of  claim 19 , wherein P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala, D-Ala-Ala, and D-Ala-D-Ala. 
     
     
         21 . The compound of any one of  claims 1 - 20 , wherein the double line   between N and C represents a double bond. 
     
     
         22 . The compound of any one of  claims 1 - 21 , wherein the double line   between N and C represents a single bond, X is —H or an amine protecting group; and Y is selected from —H, —OR, —OCOR′, —SR, —NR′R,″ an optionally substituted 5- or 6-membered nitrogen-containing heterocycle, —SO 3 H, —SO 2 H and —OSO 3 H. 
     
     
         23 . The compound of  claim 22 , wherein Y is selected from —H, —SO 3 M, —OH, —OMe, —OEt or —NHOH, wherein M is —H, Na +  or K + . 
     
     
         24 . The compound of  claim 23 , wherein Y is —H, —SO 3 M or —OH. 
     
     
         25 . The compound of any one of  claims 1 - 24 , wherein A and A′ are the same or different, and are selected from —O—, —S—, —NR 5 —, and oxo —(C═O)—. 
     
     
         26 . The compound of  claim 25 , wherein A and A′ are the same or different, and are selected from —O— and —S—. 
     
     
         27 . The compound of  claim 26 , wherein A and A′ are —O—. 
     
     
         28 . The compound of any one of  claims 1 - 27 , wherein R 6  is —OMe. 
     
     
         29 . The compound of any one of  claims 1 - 28 , wherein R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are independently —H, halogen, —NO 2 , —OH, (C 1 -C 3 )alkyl, halo(C 1 -C 3 )alkyl or (C 1 -C 3 )alkoxy. 
     
     
         30 . The compound of  claim 29 , wherein R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are all —H. 
     
     
         31 . The compound of any one of  claims 1 - 30 , wherein R, R′, R″ and R 5  are each independently —H or (C 1 -C 3 )alkyl. 
     
     
         32 . The compound of any one of  claims 1 - 19 , wherein:
 the double line   between N and C represents a single bond or 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;   R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are all —H;   R 6  is —OMe;   X′ and Y′ are both —H;   A and A′ are —O—; and   M is H, Na +  or K + .   
     
     
         33 . The compound of  claim 1 , wherein the compound is selected from any one of the following formulas: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         or a pharmaceutically acceptable salt thereof, wherein:
 R 100  is —OH, —OMe or; 
 
       
       
         
           
           
               
               
           
         
         
           Y is —H, —OH or —SO 3 M; 
           M is H + , Na +  or K + ; 
           Z is —H, —SR d , —C(═O)R d1  or is selected from any one of the following formulas: 
         
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein:
 q is an integer fro 1 to 5; 
 n′ is an integer from 2 to 6; 
 U is —H or SO 3 M; and 
 R d  is a linear or branched alkyl having 1 to 6 carbon atoms or is selected from phenyl, nitrophenyl (e.g., 2 or 4-nitrophenyl), dinitrophenyl (e.g., 2,4-dinitrophenyl), carboxynitrophenyl (e.g., 3-carboxy-4-nitrophenyl), pyridyl and nitropyridyl (e.g., 4-nitropyridyl); and 
 R d1  is a linear or branched alkyl having 1 to 6 carbon atoms. 
 
       
     
     
         34 . The compound of  claim 33 , wherein Y is —SO 3 M. 
     
     
         35 . A conjugate comprising a cytotoxic compound and a cell-binding agent (CBA), wherein the cytotoxic compound is covalently linked to the CBA, and wherein said cytotoxic compound is represented by any one of the following formulas: 
       
         
           
           
               
               
           
         
         or a pharmaceutically acceptable salt thereof, wherein:
 one of L′, L″, and L′″ is represented by the following formula:
   —Z 1 —P—Z 2 —R x -J′  (A′)
 
 
 
         and the other two 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 —(CH 2 CH 2 O) 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′, and —OCONR′R″;
 one of the Z 1  and Z 2  is —C(═O)—, and the other is —NR 5 —; 
 P is an amino acid residue or a peptide containing between 2 to 20 amino acid residues; 
 R x  is an optionally substituted linear, branched or cyclic alkyl, alkenyl or alkynyl having from 1 to 10 carbon atoms; 
 J′ is a moiety comprising the linking group that is covalently linked to the cell-binding agent; 
 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 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 (e.g., piperidine, tetrahydropyrrole, pyrazole, morpholine, etc.), a guanidinum represented by —NR′(C═NH)NR′R″, an amino acid residue, or a peptide represented by —NRCOP′, —SR, —SOR′, halogen, cyano, azido, —OSO 3 H, sulfite (—SO 3 H or —SO 2 H), metabisulfite (H 2 S 2 O 5 ), mono-, di-, tri-, and tetra-thiophosphate (PO 3 SH 3 , PO 2 S 2 H 2 , POS 3 H 2 , PS 4 H 2 ), thio phosphate ester (R i O) 2 PS(OR i ), R i S—, R i SO, R i SO 2 , R i SO 3 , thiosulfate (HS 2 O 3 ), dithionite (HS 2 O 4 ), phosphorodithioate (P(═S)(OR k′ )(S)(OH)), hydroxamic acid (R k′ C(═O)NOH), and formaldehyde sulfoxylate (HOCH 2 SO 2   − ) or a mixture thereof, wherein R i  is a linear or branched alkyl having 1 to 10 carbon atoms and is substituted with at least one substituent selected from —N(R j ) 2 , —CO 2 H, —SO 3 H, and —PO 3 H; R i  can be further optionally substituted with a substituent for an alkyl described herein; R j  is a linear or branched alkyl having 1 to 6 carbon atoms; R k′  is a linear, branched or cyclic alkyl, alkenyl or alkynyl having 1 to 10 carbon atoms, aryl, heterocyclyl or heteroaryl; 
 P′ is an amino acid residue or a polypeptide containing 2 to 20 amino acid residues; 
 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- to 18-membered heterocyclic ring having 1 to 6 heteroatoms independently selected from O, S, N and P; 
 R c  is —H or a substituted or unsubstituted linear or branched alkyl having 1 to 4 carbon atoms; 
 n is an integer from 1 to 24; 
 X′ is selected from —H, an amine-protecting 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, 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 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are each 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 , halogen, guanidinium [—NH(C═NH)NH 2 ], —OR, —NR′R″, —NO 2 , —NCO, —NR′COR″, —SR, a sulfoxide represented by —SOR′, a sulfone represented by —SO 2 R′, —SO 3 H, —OSO 3 H, —SO 2 NR′R″, cyano, an azido, —COR′, —OCOR′, and —OCONR′R″; 
 R 6  is —H, —R, —OR, —SR, —NR′R″, —NO 2 , or halogen; 
 G is —CH— or —N—; 
 A and A′ are the same or different, and are independently selected from —O—, oxo (—C(═O)—), —CRR′O—, —CRR′—, —S—, —CRR'S—, —NR 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. 
 
       
     
     
         36 . The conjugate of  claim 35 , wherein one of L′, L″ and L′″ is represented by formula (A′), and the others are —H, an linear or branched alkyl having from 1 to 6 carbon atoms, halogen, —OH, (C 1 -C 6 )alkoxy, or —NO 2 . 
     
     
         37 . The conjugate of  claim 35 , wherein one of L′, L″ and L′″ is represented by formula (A′), and the others are —H. 
     
     
         38 . The conjugate of  claim 37 , wherein L′ is represented by formula (A′); and L″ and L′″ are both —H. 
     
     
         39 . The conjugate of any one of  claims 35 - 38 , wherein R x  is a linear, branched or cyclic alkyl having 1 to 6 carbon atoms optionally substituted with halogen, —OH, —SO 3 H, (C 1 -C 3 )alkyl, (C 1 -C 3 )alkoxy, halo(C 1 -C 3 )alkyl, or a charged substituent or an ionizable group Q. 
     
     
         40 . The conjugate of any one of  claims 35 - 39 , wherein J′ comprises a moiety that is covalently linked to the CBA, and is —NR c1  or —C(═O)—, wherein R″ is —H or linear or branched alkyl having 1 to 4 carbon atoms optionally substituted with halogen, —OH or (C 1 -C 3 )alkoxy 
     
     
         41 . The conjugate of  claim 40 , wherein J′ is —C(═O)—. 
     
     
         42 . The conjugate of any one of  claims 39 - 41 , wherein L′ is represented by the following formula:
   —NR 5 —P—C(═O)—(CR a R b ) m -J′  (B1′);
 
   —NR 5 —P—C(═O)—Cy—(CR a R b ) m′ -J′  (B2′);
 
   —C(═O)—P—NR 5 —(CR a R b ) m -J′  (C1′), or
 
   —C(═O)—P—NR 5 -Cy—(CR a R b ) m′ -J′  (C2′)
 
 wherein:
 J′ is —C(═O)—; 
 R a  and R b , for each occurrence, are each independently —H, (C 1 -C 3 )alkyl or a charged substituent or an ionizable group Q; 
 m is an integer from 1 to 6; 
 m′ is 0 or an integer from 1 to 6; and 
 Cy is a cyclic alkyl having 5 or 6 ring carbon atoms optionally substituted with halogen, —OH, (C 1 -C 3 )alkyl, (C 1 -C 3 )alkoxy, or halo(C 1 -C 3 )alkyl. 
 
 
     
     
         43 . The conjugate of  claim 42 , wherein R a  and R b  are both H; Cy for formulas (B2′) and (C2′) is cyclohexane; and R 5  is H or Me. 
     
     
         44 . The conjugate of  claim 42  or  43 , wherein m′ is 0 or 1. 
     
     
         45 . The conjugate of any one of  claims 35 - 41 , wherein L′ is represented by the following formula:
   —NR 5 —P—C(═O)—(CR a R b ) m —S—Z s1   (B3′); or
 
   —C(═O)—P—NR 5 —(CR a R b ) m —S—Z s1   (C3′),
 
 wherein:
 R a  and R b , for each occurrence, are each independently —H, (C 1 -C 3 )alkyl, or a charged substituent or an ionizable group Q; 
 m is an integer from 1 to 6; 
 Z s1  is selected from any one of the following formulas: 
 
 
       
         
           
           
               
               
           
         
         wherein:
 q is an integer fro 1 to 5; 
 n′ is an integer from 2 to 6; 
 U is —H or SO 3 M; and 
 M is H + , Na +  or K + . 
 
       
     
     
         46 . The conjugate of any one of  claims 39 - 42  and  45 , wherein the charged substituent or an ionizable group Q is i) —SO 3 H, —Z′—SO 3 H, —OPO 3 H 2 , —Z′—OPO 3 H 2 , —PO 3 H 2 , —Z′—PO 3 H 2 , —CO 2 H, —Z′—CO 2 H, —NR 11 R 12 , or —Z′—NR 11 R 12 , or a pharmaceutically acceptable salt thereof; or, ii) —N + R 14 R 15 R 16 X −  or —Z′—N + R 14 R 15 R 16 X − ; Z′ is an optionally substituted alkylene, an optionally substituted cycloalkylene or an optionally substituted phenylene; R 14  to R 16  are each independently an optionally substituted alkyl; and X −  is a pharmaceutically acceptable anion. 
     
     
         47 . The conjugate of  claim 46 , wherein Q is SO 3 H or a pharmaceutically acceptable salt thereof. 
     
     
         48 . The conjugate of  claim 45 , wherein R a  and R b  are both —H and R 5  is H or Me. 
     
     
         49 . The conjugate of  claim 45 , wherein —(CR a R b ) m — is —(CH 2 ) m″ —C(Me 2 )— and m″ is an integer from 1 to 5. 
     
     
         50 . The conjugate of any one of  claims 35 - 49 , wherein P is a peptide containing 2 to 10 amino acid residues. 
     
     
         51 . The conjugate of  claim 50 , wherein P is a peptide containing 2 to 5 amino acid residues. 
     
     
         52 . The conjugate of  claim 50 , wherein P is selected from Gly-Gly-Gly, Ala-Val, Val-Ala, Val-Cit, Val-Lys, Phe-Lys, Lys-Lys, Ala-Lys, Phe-Cit, Leu-Cit, Lle-Cit, Trp, Cit, Phe-Ala, Phe-N 9 -tosyl-Arg, Phe-N 9 -nitro-Arg, Phe-Phe-Lys, D-Phe-Phe-Lys, Gly-Phe-Lys, Leu-Ala-Leu, Ile-Ala-Leu, Val-Ala-Val, Ala-Leu-Ala-Leu, f-Ala-Leu-Ala-Leu, Gly-Phe-Leu-Gly, Val-Arg, Arg-Val, Arg-Arg, Val-D-Cit, Val-D-Lys, Val-D-Arg, D-Val-Cit, D-Val-Lys, D-Val-Arg, D-Val-D-Cit, D-Val-D-Lys, D-Val-D-Arg, D-Arg-D-Arg, Ala-Ala, Ala-D-Ala, D-Ala-Ala, D-Ala-D-Ala, Ala-Met, and Met-Ala. 
     
     
         53 . The conjugate of  claim 52 , wherein P is Gly-Gly-Gly, Ala-Val, Ala-Ala, Ala-D-Ala, D-Ala-Ala, and D-Ala-D-Ala. 
     
     
         54 . The conjugate of any one of  claims 35 - 53 , wherein the double line   between N and C represents a double bond. 
     
     
         55 . The conjugate of any one of  claims 35 - 53 , wherein the double line   between N and C represents a single bond, X is —H or an amine protecting group; and Y is selected from —H, —OR, —OCOR′, —SR, —NR′R,″ an optionally substituted 5- or 6-membered nitrogen-containing heterocycle, —SO 3 H, —SO 2 H and —OSO 3 H. 
     
     
         56 . The conjugate of  claim 55 , wherein Y is selected from —H, —SO 3 M, —OH, —OMe, —OEt or —NHOH, wherein M is —H, Na +  or K + . 
     
     
         57 . The conjugate of  claim 56 , wherein Y is —H, —SO 3 M or —OH. 
     
     
         58 . The conjugate of any one of  claims 35 - 57 , wherein A and A′ are the same or different, and are selected from —O—, —S—, —NR 5 —, and oxo —(C═O)—. 
     
     
         59 . The conjugate of  claim 58 , wherein A and A′ are the same or different, and are selected from —O— and —S—. 
     
     
         60 . The conjugate of  claim 59 , wherein A and A′ are —O—. 
     
     
         61 . The conjugate of any one of  claims 35 - 60 , wherein R 6  is —OMe. 
     
     
         62 . The conjugate of any one of  claims 35 - 61 , wherein R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are independently —H, halogen, —NO 2 , —OH, (C 1 -C 3 )alkyl, halo(C 1 -C 3 )alkyl or (C 1 -C 3 )alkoxy. 
     
     
         63 . The conjugate of  claim 62 , wherein R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are all —H. 
     
     
         64 . The conjugate of any one of  claims 35 - 63 , wherein R, R′, R″ and R 5  are each independently —H or (C 1 -C 3 )alkyl. 
     
     
         65 . The conjugate of any one of  claims 35 - 52 , wherein:
 the double line   between N and C represents a single bond or 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;   R 1 , R 2 , R 3 , R 4 , R 1 ′, R 2 ′, R 3 ′ and R 4 ′ are all —H;   R 6  is —OMe;   A and A′ are —O—; and   M is H, Na +  or K + .   
     
     
         66 . The conjugate of  claim 35 , wherein the compound is selected from any one of the following formulas: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         or a pharmaceutically acceptable salt thereof, wherein:
 r is an integer from 1 to 10; 
 Y is —H, —OH or —SO 3 M; and 
 M is H + , Na +  or K + . 
 
       
     
     
         67 . The conjugate of  claim 66 , wherein Y is —SO 3 M. 
     
     
         68 . The conjugate of any one of  claims 35 - 67 , wherein the cell-binding agent (CBA) 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. 
     
     
         69 . The conjugate of any one of  claims 35 - 67 , 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. 
     
     
         70 . A pharmaceutical composition comprising the conjugate of any one of  claims 35 - 69  and a pharmaceutically acceptable carrier. 
     
     
         71 . A method of inhibiting abnormal cell growth or treating a proliferative disorder, an autoimmune disorder, destructive bone disorder, infectious disease, viral disease, fibrotic disease, neurodegenerative disorder, pancreatitis or kidney disease in a mammal, comprising administering to said mammal a therapeutically effective amount of a compound of any one of  claims 1 - 34  or a conjugate of any one of  claims 35 - 69 , and optionally, a chemotherapeutic agent. 
     
     
         72 . The method of  claim 71 , wherein the method is for treating a condition selected from the group consisting of: cancer, rheumatoid arthritis, multiple sclerosis, graft versus host disease (GVHD), transplant rejection, lupus, myositis, infection, and immune deficiency. 
     
     
         73 . The method of  claim 72 , wherein the method is for treating a cancer. 
     
     
         74 . The method of  claim 73 , wherein the cancer is ovarian cancer, pancreatic cancer, cervical cancer, melanoma, lung cancer (e.g., non small-cell lung cancer), breast cancer, squamous cell carcinoma of the head and neck, prostate cancer, endometrial cancer, lymphoma (e.g., non-Hodgkin lymphoma), myelodysplastic syndrome (MDS), peritoneal cancer, or leukemia (e.g., acute myeloid leukemia (AML), acute monocytic leukemia, promyelocytic leukemia, eosinophilic leukaemia, acute lymphoblastic leukemia (e.g., B-ALL), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML)). 
     
     
         75 . The method of  claim 73 , wherein the cancer is acute myeloid leukemia (AML). 
     
     
         76 . The method of  claim 73 , wherein the cancer is non small-cell lung cancer. 
     
     
         77 . The method of  claim 73 , wherein the cancer is ovarian cancer.