Quantitative Analysis of Bimiralisib in Dried Blood Spots of Mouse Blood Using a Validated LC‐MS/MS Method: An Application to Pharmacokinetic Study

Bimiralisib, a pan-PI3K/mTOR inhibitor, has demonstrated antitumor efficacy in preclinical models. In this study, we present a validated LC-MS/MS method for quantifying bimiralisib from dried blood spots (DBS) in mice. The method was validated in accordance with FDA guidelines. Bimiralisib was extracted from DBS disks using a liquid-liquid extraction technique. Chromatographic separation was achieved on an Atlantis dC18 column (100 × 4.6 mm) using an isocratic mobile phase. The flow rate was set at 0.70 mL/min. Under optimized conditions, the retention times for bimiralisib and the internal standard (IS, Nilotinib) were approximately 1.14 and 1.27 min, respectively, with a total run time of 2.00 min per injection. The monitored MS/MS ion transitions were m/z 412.2 → 141.0 for bimiralisib and 530.4 → 259.0 for the IS. The method employed a broad calibration range (1.00-1434 ng/mL) with a determination coefficient (r²) of 0.996. All validation parameters met the required acceptance criteria, and hematocrit levels had no impact on bimiralisib concentrations in DBS. The validated method was utilized to determine intravenous and oral pharmacokinetic parameters by quantifying bimiralisib in mouse blood, with results correlated to pharmacokinetic data from mice plasma.