DDRE-12. DETERMINATION OF TOTAL AND UNBOUND LEVELS OF A POTENT INHIBITOR OF FIBROBLAST GROWTH FACTOR RECEPTOR, INFIGRATINIB, IN HUMAN PLASMA, CEREBROSPINAL FLUID AND BRAIN TUMOR BY A VALIDATED LC-MS/MS ASSAY

Abstract

Abstract BACKGROUND Infigratinib is an orally available potent inhibitor of fibroblast growth factor receptor (FGFR) under investigation in a Phase 0 clinical trial for recurrent high-grade gliomas harboring oncogenic FGFR mutation or translocation (NCT04424966). Here, we report on our development and validation of an LC-MS/MS method for determination of total and unbound levels of infigratinib in human plasma, cerebrospinal fluid (CSF) and glioblastoma tissue. METHODS Infigratinib was extracted from human plasma, CSF and glioblastoma homogenate samples by protein precipitation with methanol. Unbound fractions of infigratinib in plasma and brain tissues were determined by equilibrium dialysis. Validation was performed using Sciex ExionLC UHPLC system coupled with Sciex QTRAP 6500+ MS/MS detector using positive electrospray ionization mode. The method was validated according to FDA guidelines and CAP/CLIA regulations. RESULTS The method was validated for 0.2-1000 nmol/L concentration range using plasma as matrix for all biospecimens. The analytical separation was optimized on Phenomenex Kinetex™ F5 column with total run time of 3.5 min using isocratic mode. Maximum coefficient of variation for intra- and inter-day precision was 12.7% and the accuracy was within 88.5-115.0% in all matrixes. The analyte is stable in plasma for at least 19 hours at room temperature (RT). Plasma stability at -20°C was demonstrated for at least 119 days. Stability of stock and working solutions was demonstrated for at least 15 hours (RT) and 60 days (2-8°C). The unbound fraction of infigratinib in pooled human plasma and brain were determined to be 0.01. CONCLUSIONS A sensitive and rapid bioanalytical method is successfully developed and validated to quantify total and unbound infigratinib levels in human plasma, CSF and glioblastoma tissue. The method is presently employed to evaluate plasma pharmacokinetics and CNS penetration of infigratinib in recurrent glioblastoma patients in an ongoing Phase 0 clinical trial.