Application of newly developed and validated UPLC-MS/MS method for pharmacokinetic study of ROS1/NTRK inhibitor taletrectinib in beagle dog plasma.

Taletrectinib is a potent selective ROS and pan-NTRK tyrosine kinase inhibitor (TKI) and has been developed to treat non-small cell lung cancer (NSCLC). To facilitate pharmacokinetic and toxicokinetic studies of taletrectinib, we developed a procedure for ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to detect the plasma level of taletrectinib in dogs. This assay procedure was validated in compliance with FDA guidance. The dog plasma samples were spiked with internal standard (IS), followed by protein precipitation, and analyzed using a Waters ACQUITY BEH C 18 column coupled to a Thermo triple quadrupole mass spectrometer. Separation was executed using the acetonitrile-0.1 % formic acid solution with gradient elution, at a flow rate of 0.4 mL/min. Taletrectinib and IS were monitored by multiple reaction monitoring (MRM) with m/z 406.2 > 349.2 and m/z 441.2 > 138.1, respectively. The procedure demonstrated excellent linearity with a correlation coefficient greater than 0.999 within the concentration range of 0.2-200 ng/mL. The inter- and intra-day accuracy ranged from -5.25 % to 5.26 %, and the precision was below 6.39 %. Acetonitrile-mediated protein precipitation showed high extraction efficiency and a recovery above 85 %. The procedure was then applied to quantify taletrectinib in beagle dog plasma after oral and intravenous doses and achieved success. The obtained pharmacokinetic parameters indicated high bioavailability of taletrectinib (>85 %) and extensive tissue distribution (>40 L/kg).