Bioanalysis of alectinib and metabolite M4 in human plasma, cross-validation and impact on PK assessment

Background: Alectinib is a novel anaplastic lymphoma kinase (ALK) inhibitor for treatment of patients with ALK-positive non-small-cell lung cancer who have progressed on or are intolerant to crizotinib. To support clinical development, concentrations of alectinib and metabolite M4 were determined in plasma from patients and healthy subjects. Methods: LC–MS/MS methods were developed and validated in two different laboratories: Chugai used separate assays for alectinib and M4 in a pivotal Phase I/II study while Roche established a simultaneous assay for both analytes for another pivotal study and all other studies. Conclusion: Cross-validation assessment revealed a bias between the two bioanalytical laboratories, which was confirmed with the clinical PK data between both pivotal studies using the different bioanalytical methods.