Development and Validation of a Rapid and Simple LC-MS/MS Method for Quantification of the Anti-Microtubule,...

A rapid and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantifying ABT-751, an anticancer agent targeting microtubules. Sample preparation involved protein precipitation using acetonitrile and formic acid (100:1, v/v), providing efficient ABT-751 extraction with minimal ion suppression. Buparlisib (BKM-120) served as the internal standard. Chromatographic separation was achieved on a Zorbax Extend C18 column, with gradient elution from 20 to 95% methanol in 0.1% (v/v) formic acid in water, and MS/MS detection was performed in positive ionization mode. This assay was validated for human plasma, mouse plasma, and various mouse tissues, including brain, liver, lung, and kidney homogenates. Calibrants were prepared in each respective blank biological matrix, except for mouse tumor tissue, and curves were fitted by quadratic regression from 5 to 10,000 nM. For mouse tumor tissue we used human plasma as surrogate matrix for calibrants. Precision and accuracy for intra-day and inter-day measurements were within acceptable limits across low, medium, and high concentrations for all matrices. Stability concerns with ABT-751 in mouse plasma and tissue homogenate samples that were stored for more than 8 months were identified and addressed. A pilot pharmacokinetic study in mice demonstrated the applicability of this validated LC-MS/MS method.