Development and validation of an LC-MS/MS method for determination of a novel anticancer agent (CPI-613) in human plasma

Background: This article describes the development and validation of a bioanalytical assay to quantify CPI-613 and its major metabolites, CPI-2850 and CPI-1810, in human plasma matrix using LC-MS/MS. Methodology: Sample extraction procedure following protein precipitation with acetonitrile was optimized to extract all three analytes from plasma with maximum recovery. The final extracted supernatants were diluted with water and injected onto an Xbridge C18 (50 x 2.1 mm; 5 mu m) column for analysis. The analytes were separated by a gradient elution, and detection was performed on a triple quadrupole mass spectrometer (Sciex API 5000) operating in the negative ion mode. Results: The assay was linear over a range of 50-50,000 ng/ml for CPI-613, 250-250,000 ng/ml for CPI-2850 and 10-10,000 ng/ml for CPI-1810. Benchtop stability was established for 24 h, and four freeze-thaw cycles were evaluated for CPI-613 and its metabolites. Long-term freezer (-60 to -80 degrees C) stability for about 127 days was established in this validation. Mean matrix recovery was more than 80% for all analytes. Conclusion: A robust LC-MS/MS method was developed for the quantification of CPI-613 and its major metabolites. The current assay will be used to support ongoing and future CPI-613 clinical trials. Plain language summary To achieve the pharmacokinetic objectives of clinical trials, it was necessary to determine the concentrations of CPI-613 and its metabolites in human plasma samples. In this article, the authors describe the development and validation of a highly sensitive and selective LC-MS/MS assay method for the simultaneous quantification of CPI-613 and its major metabolites, CPI-2850 and CPI-1810, in human plasma. Concentration ranges were selected based on previous data where CPI-613 was detected using the HPLC method (rather than LC-MS/MS).