Received for publication July 18, 2008.
Revised August 26, 2008.
Accepted for publication September 10, 2008.

Metabolism of 5-Isopropyl-6-(5-methyl-1,3,4-oxadiazol-2-yl)-N-(2-methyl-1H-pyrrolo[2,3-b]pyridin-5-yl)pyrrolo[2,1-f][1,2,4]triazin-4-amine (BMS-645737): Identification of an Unusual N-Acetylglucosamine Conjugate in the Cynomolgus Monkey

Abstract

5-Isopropyl-6-(5-methyl-1,3,4-oxadiazol-2-yl)-N-(2-methyl-1H-pyrrolo[2,3-b]pyridin-5-yl)pyrrolo[2,1-f][1,2,4] triazin-4-amine (BMS-645737) is a potent and selective VEGF receptor-2 antagonist. In this study, liquid chromatography-tandem mass spectrometry and NMR were used to investigate the biotransformation of BMS-645737 in vitro and in the cynomolgus monkey, dog, mouse and rat. Metabolic pathways for BMS-645737 included multi-step processes involving both oxidation and conjugation reactions. For example, the 2-methyl-1H-pyrrolo moiety underwent CYP-catalyzed hydroxylation followed by oxidation to a carboxylic acid and then conjugation with taurine. Alternatively, the 5-methyl-1,3,4-oxadiazol-2-yl moiety was metabolized by hydroxylation and then conjugation with sulfate. The pyridin-5-yl group underwent direct glucuronidation in hepatocytes (dog, monkey, human) and conjugation with N-acetylglucosamine in the monkey. Conjugation with glutathione and processing along the mercapturic-acid pathway was a minor metabolic pathway in vivo, although BMS-645737 did not form conjugates in the presence of glutathione-supplemented liver microsomes. Other minor biotransformation pathways included oxidative dehydrogenation, dihydroxylation, and hydrolytic opening of the oxadiazole ring followed by either deacetylation or hydrolysis of the resulting diacyl hydrazide. Whereas previous studies have demonstrated the formation of N-acetylglucosamine conjugates of alcohols, arylamines, and other small molecules, this report describes the biotransformation of a heterocyclic aromatic amine via direct conjugation with N-acetylglucosamine.

Key words: anticancer agents, drug discovery, mass spectrometry, metabolite identification, phase II drug metabolism