In Vitro Metabolism of 2-Methoxy-N-[3-[4-[3-methyl-4-[(6-methyl- 3-pyridinyl)oxy]anilino]-6-quinazolinyl]prop-2-enyl]acetamide (CP-724,714) by Aldehyde Oxidase and Predicting Its Percent Contribution Relative to CYP-Mediated Metabolism

2-methoxy-N-[3-[4-[3-methyl-4-[(6-methyl-3-pyridinyl)oxy]anilino]-6-quinazolinyl]prop-2-enyl]acetamide (CP-724,714) is an anticancer drug that was discontinued owing to hepatotoxicity found in clinical studies. Metabolite analysis of CP-724,714 was conducted using human hepatocytes, where twelve oxidative metabolites and one hydrolyzed metabolite were formed. Among the three mono-oxidative metabolites, the formation of two was inhibited by adding 1-aminobenzotriazole, a pan-CYP inhibitor. In contrast, the remaining one was not affected by this inhibitor but partially inhibited by hydralazine, indicating that aldehyde oxidase (AO) was involved in metabolizing CP-724,714, which contains a quinazoline substructure, a heterocyclic aromatic quinazoline ring, known to be preferably metabolized by AO. One of the oxidative metabolites of CP-724,714 observed in human hepatocytes was also generated in recombinant human AO. Although CP-724,714 is metabolized by both CYPs and AO in human hepatocytes, the contribution level of AO could not be evaluated using its specific inhibitors because of low AO activity in in vitro human materials. Here, we present a metabolic pathway for CP-724,714 in human hepatocytes and the involvement of AO in CP-724,714 metabolism. We showed here a plausible workflow for predicting AO contribution to the metabolism of CP-724,714 based on DMPK screening data. Significance Statement CP-724,714 was identified as a substrate of aldehyde oxidase (AO) rather than xanthine oxidase. Since CP-724,714 is also metabolized by CYPs, the contribution levels of AO and CYPs in the metabolism of CP-724,714 were estimated simultaneously based on in vitro drug metabolism screening data.