Antitumor agents

Abstract

An antitumor agent, which is a combination of an oxidoreductase, such as xanthine oxidase chemically conjugated to a polymer such as poly ethylene glycol, for initial administration and accumulation in the tumor tissue followed by administration and of a substrate for the oxidoreductase which releases reactive oxygen species. Improved tumor selective cytotoxic activity results.

What is claimed is:  
     
         1 . (New) Antitumor agent comprising a combination of an oxidoreductase which is chemically conjugated with a polymer, and of a substrate of the oxidoreductase.  
     
     
         2 . (New) The antitumor agent according to  claim 1 , wherein the oxidoreductases is xanthine oxidase and its substrate is hypoxanthine or xanthine.  
     
     
         3 . The antitumor agent according to  claim 1 , wherein the polymer is poly(ethylene glycol).  
     
     
         4 . (New) A method for treating cancer, which comprises administering to a patient in need thereof a therapeutically effective amount of an oxidoreductase which is chemically conjugated with a polymer, and subsequently administering its substrate.  
     
     
         5 . (New) The method according to  claim 4 , wherein the oxidoreductase is xanthine oxidase and its substrate is hypoxanthine or xanthine.  
     
     
         6 . (New) The method according to  claim 4 , wherein the polymer is poly(ethylene glycol).  
     
     
         7 . (New) A method of treating tumors comprising the steps of sequentially administering a first component A, D-amino acid oxidase, which is chemically conjugated with a polyethylene glycol, and thereafter, 
 separately administering component B, D-amino acid, which is a substrate for the xanthine oxidase.