Abstract
PURPOSE: Trabectedin (Yondelis, ET-743) is a novel anticancer drug with potent activity against various tumors. However, dose-limiting hepatotoxicity was observed during clinical trials. Because recent reports have suggested that cytochrome P450 3A (CYP3A), as well as the drug transporters ABCB1, ABCC2, and ABCC3 might protect against trabectedin-mediated hepatotoxicity, we investigated the individual and combined roles of these detoxifying systems. EXPERIMENTAL DESIGN: Madin-Darby canine kidney cells expressing ABCC2 and ABCC3 were used to study in vitro trabectedin transport. We investigated the hepatotoxicity of trabectedin, and the plasma and liver levels of this drug and its metabolites in mice deficient for CYP3A, Abcb1a/1b, Abcc2, and/or Abcc3 after i.v. trabectedin administration. RESULTS: Trabectedin was transported by ABCC2 but only modestly by ABCC3. Contrary to our expectation, absence of CYP3A resulted in only a marginal increase in hepatotoxicity. Some hepatotoxicity was observed in Abcc2(-/-) mice, but very little in Abcb1a/1b(-/-) and Abcc3(-/-) mice. Strikingly, severe hepatotoxicity was found in Abcb1a/1b/Abcc2(-/-) and Abcc2/Abcc3(-/-) mice. However, hepatotoxicity was drastically decreased in Cyp3a/Abcb1a/1b/Abcc2(-/-) compared with Abcb1a/1b/Abcc2(-/-) mice. This suggests that the formation of CYP3A-specific metabolites is an important prerequisite for trabectedin-mediated hepatotoxicity. Further studies revealed that there is increased accumulation of metabolites of trabectedin, but not of trabectedin itself, in the livers of mice that lack Abcc2 but are CYP3A proficient. CONCLUSIONS: Our data show that ABCB1, ABCC2, and ABCC3 have a profound and partially redundant function in protection from trabectedin-mediated hepatotoxicity, presumably by clearing the liver from hepatotoxic trabectedin metabolites that are primarily formed by CYP3A. (Clin Cancer Res 2009;15(24):7616-23).