Patent ID: 8334364

Claim:
A high molecular weight derivative of a nucleic acid antimetabolite, in which a carboxyl group in the side chain of a high molecular weight compound comprising a polyethylene glycol moiety and a polymer moiety having a carboxyl group in the side chain is linked to a hydroxyl group of a nucleic acid antimetabolite via an ester linkage, wherein said high molecular weight derivative of a nucleic acid antimetabolite is represented by the following formula (1): wherein R represents a hydrogen atom or a C1-C6 alkyl group; A represents a hydrogen atom, a C1-C6 acyl group or a C1-C6 alkoxycarbonyl group; m represents from 3 to 200 as an average value; n represents from 5 to 2000 as an average value; and X represents a group selected from the group consisting of a nucleic acid antimetabolite residue, a hydroxyl group, a hydrophobic substituent, and —N(R1)CONH(R2) wherein R1 and R2 may be identical or different, and are each a C1-C6 alkyl group which may be substituted with a teritary amino group, X includes a nucleic acid antimetabolite residue and —N(R1)CONH(R2), and the nucleic acid antimetabolite residue is any one of the nucleic acid antimetabolite residues represented by the following formula (2): wherein —Rf represents a group selected from the group of substituents of formula (3):