A novel uHPLC–MS/MS method for the quantitation of AZD7451 (AZ12607092) in human plasma

•We developed and validated a novel uHPLC–MS/MS assay for the quantification of AZD7451.•This method is accurate, precise, and uses a simple liquid extraction procedure that recovers over 80% of drug from human plasma.•AZD7451 demonstrated excellent freeze/thaw, plasma, and post-preparative stability.•Successfully applied to a first-in-humans clinical pharmacokinetic study. Tropomyosin-related kinases (Trk) are tyrosine kinase receptors implicated in tumor proliferation, invasion, and survival signaling across a number of tumors, making them potentially attractive targets for the treatment of cancer. AZD7451 is a potent and selective inhibitor of Trk kinases currently undergoing a Phase I dose escalation in glioblastoma multiforme at the National Cancer Institute. A key part of early clinical testing for AZD7451 involves demonstrating that pharmacokinetic half-life and clinical exposures of AZD7451 are sufficient to inhibit Trk receptors in preclinical models. To address this need, an ultra sensitive analytical method was developed to measure the AZD7451 profile in human plasma. A liquid–liquid extraction recovered >80% of AZD7451 before quantitative analysis by ultra HPLC–MS/MS. A Varian Polaris® C18-A column and a mass transition of m/z 383.5→340.5 (m/z 389.6→342.0 for the internal standard [2H6]-AZD7451) was used, and a dynamic calibration range of 0.5–1000ng/mL was established, which provided a sensitive (