Intrinsic Validity of Molecular Marker(s) Detection on Tissular Tumoral DNA to Predict the Efficacy of 177Lutetium-PSMA-617 (Lu-PSMA) Treatment for Castration-resistant Metastatic Prostate Cancer

Prostate cancer is the most common cancer in men. Its incidence is rising as the population ages. In the localized stage, the 5-year overall survival rate (OS) is 98%. Metastatic progression and resistance to castration have a negative impact on prognosis. Despite recent advances in management, the 5-year OS is around 30%. Therapeutic advances in this indication have been made mainly by the use of taxanes and second-generation hormone therapy. These treatments have improved OS and progression-free survival (PFS). They are now used as standard therapy. More recently, the Phase III VISION trial confirmed the improvement in OS and radiological PFS achieved by treatment with the radioligand 177Lutetium-PSMA-617 (Lu-PSMA) in patients with advanced metastatic castration-resistant prostate cancer (mCRPC). This treatment is currently available in early access in France. Despite encouraging results, 40% of patients will not respond to Lu-PSMA, and there are currently no validated predictive factors. Studies are currently on going, but the identification of biomarkers seems necessary to better stratify risk in these patients. Numerous tissue prognostic tests based on molecular characteristics or cell proliferation are emerging with this in mind. At present, molecular profiling is not a routine technique for prostate cancer, as it is for other solid cancers. At an early stage, the Decipher® Genomic classification tool has shown prognostic utility independently of therapeutic and clinico-pathological data. According to recent studies, methylome analysis would enable the subdivision of mCRPCs and could help identify new therapeutic targets. In the metastatic phase, certain molecular abnormalities involving DNA repair genes are predictive of response to PARP inhibitors. Molecular analysis (mutations, copy number alterations, gene expression, DNA methylation) could therefore be useful in optimizing the management of mCRPC patients treated with Lu-PSMA. If reliable molecular abnormalities are identified on tissue, a diagnostic technique based on circulating tumor DNA (ctDNA) analysis will be useful in decision-making for these patients. A biological collection will therefore be created during the course of this study, with a view to using ctDNA analysis in subsequent research.