1. Academic Validation
  2. Identification of Enzymes Oxidizing the Tyrosine Kinase Inhibitor Cabozantinib: Cabozantinib Is Predominantly Oxidized by CYP3A4 and Its Oxidation Is Stimulated by cyt b5 Activity

Identification of Enzymes Oxidizing the Tyrosine Kinase Inhibitor Cabozantinib: Cabozantinib Is Predominantly Oxidized by CYP3A4 and Its Oxidation Is Stimulated by cyt b5 Activity

  • Biomedicines. 2020 Nov 28;8(12):547. doi: 10.3390/biomedicines8120547.
Radek Indra 1 Katarína Vavrová 1 Petr Pompach 1 Zbyněk Heger 2 3 Petr Hodek 1
Affiliations

Affiliations

  • 1 Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 12800 Prague 2, Czech Republic.
  • 2 Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic.
  • 3 Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 61200 Brno, Czech Republic.
Abstract

Herein, the in vitro metabolism of tyrosine kinase inhibitor cabozantinib, the drug used for the treatment of metastatic medullary thyroid Cancer and advanced renal cell carcinoma, was studied using hepatic microsomal samples of different human donors, human recombinant cytochromes P450 (CYPs), flavin-containing mono-oxygenases (FMOs) and aldehyde oxidase. After incubation with human microsomes, three metabolites, namely cabozantinib N-oxide, desmethyl cabozantinib and monohydroxy cabozantinib, were detected. Significant correlations were found between CYP3A4 activity and generation of all metabolites. The privileged role of CYP3A4 was further confirmed by examining the effect of CYP inhibitors and by human recombinant Enzymes. Only four of all tested human recombinant Cytochrome P450 were able to oxidize cabozantinib, and CYP3A4 exhibited the most efficient activity. Importantly, cytochrome b5 (cyt b5) stimulates the CYP3A4-catalyzed formation of cabozantinib metabolites. In addition, cyt b5 also stimulates the activity of CYP3A5, whereas two other Enzymes, CYP1A1 and 1B1, were not affected by cyt b5. Since CYP3A4 exhibits high expression in the human liver and was found to be the most efficient Enzyme in cabozantinib oxidation, we examined the kinetics of this oxidation. The present study provides substantial insights into the metabolism of cabozantinib and brings novel findings related to cabozantinib pharmacokinetics towards possible utilization in personalized medicine.

Keywords

cabozantinib; cytochrome P450; cytochrome b5; tyrosine kinase inhibitor.

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