Development of a rapid and sensitive UPLC–MS/MS assay for simultaneous quantitation of Vorolanib and its metabolite in human plasma and application to a pharmacokinetics study

Vorolanib is an oral tyrosine kinase inhibitor that targets vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR). A sensitive and specific LC–MS/MS assay was developed and fully validated for simultaneous quantification of vorolanib and its main metabolite X297 in human plasma. The two analytes were extracted from K2-EDTA plasma samples by protein precipitation (PP) with acetonitrile, and chromatographically separated on a C18 reverse-phase column using a gradient elution. A SCIEX 5500 QTRAP® mass spectrometer system was operated in multiple-reaction monitoring mode (MRM) and all components were detected using positive electrospray ionization (ESI). The results successfully demonstrated that the method had satisfactory linearity, sensitivity, and selectivity in the concentration ranges of vorolanib (1.00−1000 ng/mL) and X297 (0.500−500 ng/mL). In this study, two concentration related peaks in the vorolanib and X297 detection channels were observed, which were speculated to be isomers of vorolanib and X297. In order to standardize the sample pretreatment process, the effect of lamp light and pH on the isomer reconversion was evaluated. The results indicated, that the exposure of samples to lamp light during the handling procedures, did not cause the conversion of the isomers. For the first time a robust and specific ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) assay for the high-throughput quantification of vorolanib and X297 in human plasma was established and validated following bioanalytical validation guidelines. The proposed method was successfully applied to clinical trials evaluating the pharmacokinetics of vorolanib tablets in Chinese advanced solid tumor patients.