Simultaneous quantification of abiraterone, enzalutamide, darolutamide, apalutamide, and their active metabolites: development and analytical validation of a new LC-MS/MS method for the PRECISION study

Abiraterone, enzalutamide, darolutamide, and apalutamide, are anticancer agents used to treat advanced and metastatic castration-resistant prostate cancer (mCRPC). Their therapeutic effects and toxicities are linked to plasma exposure. Despite fixed dosing regimens, plasma concentrations show interindividual variability due to differences in absorption, metabolism, and polypharmacy, making Therapeutic Drug Monitoring (TDM) a potentially valuable tool for optimizing both efficacy and safety. Currently, no validated analytical method is available for the simultaneous quantification of all four drugs and their active metabolites. The Prostate cancer REsearch using Cross-validation of Innovative Sampling, Integrating LC-MS/MS for Optimised therapeutic drug moNitoring (PRECISION) study, an analytical protocol ongoing at Centro di Riferimento Oncologico di Aviano, IRCCS, National Cancer Institute, aims to develop and validate, through cross-validation, an LC-MS/MS method capable of quantifying these compounds in samples collected from human plasma and Dried Blood Spots (DBS). DBS offers an attractive alternative to venous sampling, as it is less invasive, improves sample stability, and enables collection outside healthcare facilities. This thesis describes the development and validation (in accordance with the ICH M10 and FDA guidelines) of the analytical method in human plasma and the initiation of data collection required for cross-validation with DBS. The ultimate goal is to provide a robust and transferable tool to implement TDM in clinical practice for the personalized management of patients with mCRPC.