Role of 5'-nucleotidase in thiopurine metabolism: enzyme kinetic profile and association with thio-GMP levels in patients with acute lymphoblastic leukemia during 6-mercaptopurine treatment.

Thiopurines are used for treatment of several diseases. Cytotoxicity is caused by the derived compounds 6-thioguanine nucleotides (TGNs) and methyl-6-thioinosine monophosphate (methylthio-IMP). The 6-thiopurine mononucleotides 6-thio-IMP (thio-IMP), 6-thio-GMP (thio-GMP) and methylthio-IMP can be catabolized by purine 5′-nucleotidase. It has been shown that the various 5′-nucleotidases are key enzymes for (6-thio)-purine metabolism. We aimed to investigate whether the overall 5′-nucleotidase (5′NT) activity is correlated with the efficacy and toxicity of 6-thiopurine nucleotides.