Polymer conjugates of K-252A and derivatives thereof

A polymer conjugate of formula (III):

• wherein R1 and R2 are hydrogen,
• R3 is hydrogen, halogen, aryl, carbamoyl, substituted or unsubstituted lower alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted lower alkynyl or amino;
• W1 and W2 are hydrogen,
• X represents -L1-X′ and Y represents -L2-Y′ wherein at least one of X′ and
• Y′ is a polymer, either linear or branched, which is bound by L1 and/or L2 to the tetrahydrofuran ring of the compound of formula (III);
• L1 and/or L2 are a covalent chemical bond or a linker group;
• when Y′ is a polymer, and X′ is not a polymer, L1 is a covalent chemical bond and X′ is selected from the group consisting of
• (a) hydrogen, lower hydroxyalkyl, acyl, carboxy, lower alkoxycarbonyl,
• (b) —CONR17aR17b, wherein R17a and R17b are each independently selected from
• (i) hydrogen, lower alkyl, lower alkenyl, lower alkynyl,
• (ii) —CH2R18;
• wherein R18 is hydroxy, and
• (iii) —NR19R20, wherein R19 or R20 are each independently hydrogen, lower alkyl, lower alkenyl, lower alkynyl or R19 or R20 are independently the residue of an α-amino acid in which the hydroxy group of the carboxyl group is excluded, or R19 or R20 are combined with a nitrogen atom to form a heterocyclic group;
• and
• (c) —CH═N—R21, wherein R21 is hydroxy, lower alkoxy, amino, guanidino, or imidazolylamino;
• when X′ is polymer, and Y′ is not a polymer, L2 is a covalent chemical bond and Y′ is hydroxy, lower alkoxy, aralkyloxy, or acyloxy;
• or a pharmaceutically acceptable salt thereof.