Development and validation of an LC-MS/MS method for the quantification of KRAS^G12C inhibitor opnurasib in several mouse matrices and its application in a pharmacokinetic mouse study.

Abstract

Opnurasib (JDQ-443) is a highly potent and promising KRAS^G12C inhibitor that is currently under clinical investigation. Results of the ongoing clinical research demonstrated the acceptable safety profile and clinical activity of this drug candidate as a single agent for patients with NSCLC harboring KRAS^G12C mutations. In this early stage of development, a deeper insight into pharmacokinetic properties in both preclinical and clinical investigations of this drug is very important. Thus, a reliable quantification method is required. To date, no quantitative bioanalytical assay of opnurasib was publicly available. In this study we present a validated assay to quantify opnurasib in mouse plasma and eight mouse tissue-related matrices utilizing liquid chromatography-tandem mass spectrometry. Erlotinib was used as internal standard and acetonitrile was utilized to treat 10 µl of the sample with protein precipitation in a 96-well plate format. Separation and detection were achieved using a BEH C18 column under basic chromatographic conditions and a triple quadrupole mass spectrometer, respectively. We have fully validated this assay for mouse plasma and partially for eight mouse tissue-related matrices over the range of 2-2000 ng/ml. The accuracy and precision of the assay fulfilled international guidelines (EMA & U.S. FDA) over the validated range. The method was proven selective and sensitive to quantify opnurasib down to 2 ng/ml in all investigated matrices. The recoveries of both analyte and internal standard in mouse plasma were ∼100 % with no significant matrix effect in any of the matrices. Opnurasib in mouse plasma was stable up to 12 h at room temperature, and up to 8 h at room temperature in tissue homogenates (except for kidney up to 4 h). This presented method has been successfully applied to quantify opnurasib in preclinical samples from a mouse study and demonstrated its usability to support preclinical pharmacokinetic studies.