Development and Validation of a Sensitive LC–MS/MS Method for Determination of Lenvatinib and Its Major Metabolites in Human Plasma and Its Application in Hepatocellular Carcinoma Patients

ABSTRACT Lenvatinib has been demonstrated effective in advanced hepatocellular carcinoma (HCC), but the pharmacokinetic–pharmacodynamics behavior of lenvatinib and its metabolites remains unclear. To investigate the pharmacokinetic–pharmacodynamics behavior of lenvatinib and its active metabolites in advanced HCC patients, it is important to develop a simple and rapid method to analyze the exposures of lenvatinib and its metabolites in human samples. Here, we established and validated a simple and rapid method for determining lenvatinib and its three major metabolites, descyclopropyl lenvatinib (M1), O‐demethyl lenvatinib hydrochloride (M2), and lenvatinib N‐Oxide (M3) by liquid chromatography‐tandem mass spectrometry method. Lenvatinib and its main metabolites were separated on an X‐Terra RP18 column (50 × 2.1 mm, 3.5 µm) at 35°C within 3 min, and the analytes were isocratically eluted with the mobile phase of methanol–water (10:90, v/v) containing 0.1% of formic acid at a flow rate of 0.15 mL/min. The calibration range was 1–1000 ng/mL for lenvatinib, while 0.1–100 ng/mL for M1–M3 under positive electrospray ionization mode. The inter‐ and intra‐batch precisions and accuracy were acceptable for lenvatinib and its metabolites. This method was successfully applied to measure lenvatinib and its metabolites in plasma samples from HCC patients, which provides a robust tool for pharmacokinetic–pharmacodynamics studies of lenvatinib.