Characterization of Genetic Variation in CYP3A4 on the Metabolism of Cabozantinib in Vitro

Cabozantinib is a multityrosine kinase inhibitor and has a wide range of applications in the clinic, whose metabolism is predominately dependent on CYP3A4. This study was performed to characterize the enzymatic properties of 29 CYP3A4 alleles toward cabozantinib and the functional changes of five selected alleles (the wild-type, CYP3A4.2.8.14 and .15) toward cabozantinib in the presence of ketoconazole. Cabozantinib, 1-100 μM, with/without the presence of ketoconazole and CYP3A4 enzymes in the incubation system went through 30 min incubation at 37 °C, and the concentrations of cabozantinib N-oxide were quantified by UPLC-MS/MS to calculate the corresponding kinetic parameters of each variant. Collectively, without the presence of ketoconazole, most variants displayed defective enzymatic activities in different degrees, and only CYP3A4.14 and .15 showed significantly augmented enzymatic activities. With the presence of ketoconazole, five tested CYP3A4 alleles, even CYP3A4.14 and .15, exhibited obvious reductions in intrinsic clearance. Besides, we compared cabozantinib with regorafenib in relative clearance to confirm that CYP3A4 has the property of substrate specificity. As the first study of CYP3A4 genetic polymorphisms toward cabozantinib, our observations can provide prediction of an individual's capability in response to cabozantinib and guidance for medication and treatment of cabozantinib.