Patent ID: 8580820

Claim:
Tubulysin compounds of formula (A) having a high cytotoxicity wherein: B is selected from CH 2 , CH 2 —CH 2 or CH 2 —CH 2 —CH 2 , D is a heteroaryl having 5 or 6 atoms in the ring, X 1 is alkyl or alkenyl, X 2 is selected from the following groups: X 2a , substituted or non substituted, is selected from: aryl, heteroaryl, arylalkyl, cycloalkylalkyl, heterocycloalkylalkyl, or heteroarylalkyl, and X 2b : alkylene-O-alkyl, wherein alkylene is C 2 -C 10 , X 3 is H, X 4 is selected from OH, (OR 5 ) n —OR 6 , OC(O)R 7 , R 5 is an alkylene, n is zero or an integer from 1 to 10, R 6 and R 7 , equal to or different from each other, have the following meanings: z1: H, alkyl, z2 substituted or non substituted: aryl, heteroaryl, cycloalkyl, heterocycloalkyl, arylalkyl, hetero-arylalkyl, cycloalkylalkyl, heterocycloalkylalkyl, X 5 is substituted or non-substituted aryl or arylalkyl, X 6 is OH, X 7 is H, alkyl or alkenyl, X 8 is selected from H, alkyl or alkenyl, and their hydrates, solvates and pharmaceutically acceptable salts.