DISPOSITION AND METABOLISM OF THE ANGIOGENIC MODERATOR O-(CHLOROACETYLCARBAMOYL) FUMAGILLOL (TNP-470-AGM-1470) IN HUMAN HEPATOCYTES AND TISSUE MICROSOMES

The biotransformation of O-(chloroacetyl-carbamoyl) fumagillol (TNP-47 0; AGM 1470), a potent in vitro inhibitor of angiogenesis, was investi gated in primary cultured human hepatocytes and microsomal fractions o f various human tissues. Exposure of human hepatocytes to 5 mu M [H-3] TNP-470 led to a rapid metabolism of unchanged drug to six metabolic d erivatives within 30 min. The predominant extracellular metabolites we re M-II and M-IV, attaining a maximum level of 3.23 +/- 0.34 and 0.88 +/- 0.10 mu M, respectively. M-II leveled off, while M-IV rapidly decl ined to 0.06 +/- 0.05 mu M by 3 h. TNP-470 was undetectable after 60 m in. M-V and M-VL slowly reached maximal concentrations of 0.26 +/- 0.1 2 and 0.32 +/- 0.16 mu M, respectively. M-I only reached a concentrati on of 0.18 +/- 0.07 mu M at 60 min and leveled at 0.13 +/- 0.06 mu M f or the remaining time of the experiment. The intracellular profile was different, with M-III and M-V representing the major metabolites dete cted. Studies using human liver microsomes demonstrated that M-IV form ation was associated with an esterase-like enzymatic cleavage of TNP-4 70 and that this metabolite was then further metabolized by microsomal epoxide hydrolase to M-II, as evidenced by inhibition of this metabol ic step by cyclohexene oxide, a microsomal epoxide hydrolase inhibitor . Extrahepatic metabolism of TNP-470 was also demonstrated using diffe rent sites of human intestinal, stomach, and kidney microsomes, with m etabolite M-IV as the principal derivative detected in these tissues. Hepatic microsomal samples from seven different donors demonstrated la rge interindividual variations in the formation of both M-II and M-IV. In summary, this study demonstrates a rapid and extensive metabolism of TNP-470 in human tissues. The data emphasize the need to evaluate t he in vivo formation and extent of TNP-470 metabolites to adequately a ssess the pharmacodynamic effects of this novel anticancer drug with a novel mechanism of action.