Quantification of FGFR4 inhibitor BLU-554 in mouse plasma and tissue homogenates using liquid chromatography-tandem mass spectrometry

BLU-554 is a potent, highly selective oral FGFR4 inhibitor. A bioanalytical assay for quantification of BLU-554 in mouse plasma and six tissue homogenates (brain, kidney, liver, lung, small intestine, and spleen) was developed and validated using liquid chromatography with tandem mass spectrometric detection and with erlotinib as internal standard. After protein precipitation with acetonitrile in a 96-well format and separation on an XBridge® Peptide BEH C18 column by gradient elution using 0.2% (v/v) ammonium hydroxide (in water) and methanol, analytes were ionized by positive electrospray and monitored in the selected reaction monitoring mode by triple quadrupole mass spectrometry. The assay was validated in a 1-1000 ng/ml concentration range using calibration in mouse plasma. Precisions (intra-day and inter-day) were in the range 2.8-10.1% and accuracies were in between 88.5 and 96.6% for all levels in all matrices. The assay was successfully applied for a pilot pharmacokinetic and tissue distribution study in wild-type mice.