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Metabolism of inhibitors of tyrosine kinases, the drugs of new generation
Čillíková, Olívia ; Indra, Radek (advisor) ; Kubíčková, Božena (referee)
Cancer is the second major cause of death after heart-attack in the world. In recent years, research has focused on tyrosine kinase inhibitors (TKIs) as part of targeted chemotherapeutic treatment. Vandetanib is a TKI affecting epidermal growth factor receptor (EGFR), rearrangement during transfection (RET) and vascular endothelial growth factor receptor 2 (VEGFR2). It is primary used for treatment of medullary thyroid cancer. Vandetanib is biotransformed by cytochromes P450 and flavin monooxygenases in human organism. Cytochromes P450 (CYPs) oxidaze vandetanib to only one metabolite, N-desmethyl vandetanib, which exhibits similar efficiency as parental molecule. NADPH is the major cofactor of reaction cycle of CYPs. This bachelor thesis studies the effect of various types of cofactors and pH on oxidation of vandetanib by selected human recombinant cytochromes P450, namely CYP2C8 coexpressed with cyt b5, CYP2D6, CYP3A4 and CYP3A4 coexpressed with cyt b5. Here, we investigate the effect of cofactors NADPH, NADH and their mixture in a 1:1 ratio on the amount of N- desmethyl vandetanib formed during the biotransformation of vandetanib. The effect of pH on the oxidation of vandetanib by CYP 3A4 and CYP 3A4 + b5 was also analysed. We analysed the amount of the metabolite formed at the pH range 7 to 8.5...
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Metabolism of an inhibitor of tyrosine kinase lenvatinib as the anticancer drug with targeting effects
Vavrová, Katarína ; Stiborová, Marie (advisor) ; Kubíčková, Božena (referee)
Lenvatinib is an oral anticancer drug that belongs to a group of tyrosine kinases, which block signal pathway receptors for development and proliferation of various cancer diseases. Lenvatinib was approved in 2015 for a treatment of progressive, locally spread or metastatic, differentiated thyroid cancer refractory to radioiodine treatment. This thesis presents findings about the metabolism of lenvatinib and identification of enzymes responsible for biotransformation of this drug. Utilizing human and rat hepatic microsomes as well as recombinant cytochromes P450 (CYPs) expressed in SupersomesTM , the metabolism of lenvatinib was studied. Used rat microsomal systems were isolated from the liver of uninduced rats and from the liver of rats in which expression of individual CYPs was induced by CYP inducers. The lenvatinib metabolites were separated by HPLC and identified by mass spectroscopy. Using rat microsomal systems, O-desmethyllenvatinib and lenvatinib N-oxide were produced. The highest amount of these lenvatinib metabolites was produced by microsomes of rats pretreated with pregnenolone carbonitrile that is an inducer of CYP3A. Human hepatic microsomes oxidize lenvatinib to O-desmethyllenvatinib and N-descyklopropyllenvatinib. In the case of rat recombinant CYPs, O-desmethyllenvatinib was...
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