Bioanalytical assay for the new-generation ROS1/TRK/ALK inhibitor repotrectinib in mouse plasma and tissue homogenate using liquid chromatography-tandem mass spectrometry

Repotrectinib, a next-generation ROS1/TRK/ALK tyrosine kinase inhibitor, overcomes resistance due to acquired solvent-front mutations involving ROS1, NTRK1-3, and ALK. A bioanalytical assay for quantification of repotrectinib in mouse plasma and seven tissue-related matrices (brain, liver, spleen, kidney, small intestinal tissue, small intestinal content, and testis homogenates) was developed and validated using liquid chromatography with tandem mass spectrometric detection in a high-throughput 96-well format. Protein precipitation was performed by adding acetonitrile, also containing the internal standard axitinib, to 10-µl samples for all matrices. Chromatographic separation of analytes was done on an ACQUITY UPLC® BEH C18 column by gradient elution using ammonium hydroxide in water and methanol. Compounds were monitored with positive electrospray ionization using a triple quadruple mass spectrometer in selected reaction monitoring mode. The method was successfully validated in the 1–1000 ng/ml calibration range. Precisions (intra- and interday) were in the range of 1.3–8.7% and accuracies were in between 90.5% and 107.3% for all levels in all matrices. The developed method was successfully applied to investigate the plasma pharmacokinetics and tissue accumulation of repotrectinib in wild-type mice.