期刊
DRUG METABOLISM AND DISPOSITION
卷 42, 期 1, 页码 162-171出版社
AMER SOC PHARMACOLOGY EXPERIMENTAL THERAPEUTICS
DOI: 10.1124/dmd.113.054817
关键词
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资金
- National Institutes of Health National Institute of General Medical Sciences [P01 GM32165]
- National Institutes of Health National Center for Research Resources [UL1-RR025014]
- University of Washington School of Pharmacy Drug Metabolism, Pharmacokinetics, and Transport Research Program
- University of Washington School of Pharmacy Elmer M. Plein Research Award
- UNCF-Merck Science Initiative
Idiosyncratic hepatotoxicity has been associated with the oral tyrosine kinase inhibitor lapatinib, which is used in metastatic breast cancer therapy. Lapatinib is extensively metabolized by cytochrome P450 3A4/5 to yield an O-debenzylated metabolite, which can undergo further oxidation to a reactive quinone imine. A recent clinical study reported that concomitant use of lapatinib with dexamethasone increased the incidence of hepatotoxicity in metastatic breast cancer patients treated with lapatinib, and so we hypothesized that induction of CYP3A enhances the bioactivation of lapatinib to reactive intermediates that contribute to hepatotoxicity. Therefore, we examined the effect of CYP3A4 induction on the cytotoxicity and metabolism of lapatinib in the HepaRG human hepatic cell line. Differentiated HepaRG cells were pretreated with dexamethasone (100 mu M) or the prototypical CYP3A4 inducer rifampicin (4 mu M) for 72 hours, followed by incubation with lapatinib (0-100 mu M) for 24 hours. Cell viability was monitored using WST-1 assays, and metabolites were quantified by liquid chromatography coupled to tandem mass spectrometry. Induction of CYP3A4 by dexamethasone or rifampicin enhanced lapatinib-induced cytotoxicity, compared with treatment with lapatinib alone. A direct comparison of the cytotoxicity of lapatinib versus O-debenzylated lapatinib demonstrated that the O-debenzylated metabolite was significantly more cytotoxic than lapatinib itself. Furthermore, pretreatment with 25 mu M L-buthionine sulfoximine to deplete intracellular glutathione markedly enhanced lapatinib cytotoxicity. Cytotoxicity was correlated with increased formation of O-debenzylated lapatinib and cysteine adducts of the putative quinone imine intermediate. Collectively, these data suggest that CYP3A4 induction potentiates lapatinib-induced hepatotoxicity via increased reactive metabolite formation.
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