RT Journal Article
SR Electronic
T1 Identification of the Human Enzymes Involved in the Oxidative Metabolism of Dasatinib: An Effective Approach for Determining Metabolite Formation Kinetics
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1828
OP 1839
DO 10.1124/dmd.107.020255
VO 36
IS 9
A1 Wang, Lifei
A1 Christopher, Lisa J.
A1 Cui, Donghui
A1 Li, Wenying
A1 Iyer, Ramaswamy
A1 Humphreys, W. Griffith
A1 Zhang, Donglu
YR 2008
UL http://dmd.aspetjournals.org/content/36/9/1828.abstract
AB N-(2-Chloro-6-methylphenyl)-2-[[6-[4-(2-hydroxyethyl)-1-piperazinyl]-2-methyl-4-pyrimidinyl]amino]-5-thiazolecarboxamide (dasatinib, Sprycel, BMS-354825; Bristol-Myers Squibb, Princeton, NJ) is a potent protein kinase inhibitor to treat chronic myeloid leukemia. In vivo studies have shown that the primary oxidative metabolites of dasatinib are M4 (N-dealkylation), M5 (N-oxidation), M6 (carboxylic acid formation), M20, and M24 (hydroxylation). To identify the enzymes responsible for the formation of these metabolites, [14C]-dasatinib and nonradiolabeled dasatinib were incubated with human cDNA-expressed enzymes [cytochromes P450 (P450s) and flavin-containing monooxygenase (FMO) 3] or human liver microsome (HLM) in the presence of selective P450 inhibitors (antibodies and chemical inhibitors). The results of these experiments showed that metabolites M4, M20, and M24 were mainly generated by CYP3A4; M5 was primarily formed by FMO3; and M6 was formed by a cytosolic oxidoreductase. The enzyme kinetic analysis showed that the formation of M4 and M5 in HLM followed the Michaelis-Menten kinetics, and the formation data of M20 and M24 fitted well to a partial substrate inhibition kinetic model. The Km values were determined by the kinetic analysis of the substrate-dependent metabolite formation plots from a large number of incubations with the nonlabeled dasatinib; the Vmax values were calculated with the predetermined Km values and the metabolite formation rates from a limited number of incubations with [14C]dasatinib. The intrinsic formation clearance values (Vmax/Km) of 52, 14, 274, and 20 μl/mg protein/min for the formation of M4, M5, M20, and M24, respectively, suggested that the formation of M20 was more efficient than other metabolites. Collectively, multiple in vitro experiments showed that dasatinib was predominately metabolized by CYP3A4. The American Society for Pharmacology and Experimental Therapeutics