AR Copy Number and AR Signaling-directed Therapies in Castrationresistant Prostate Cancer.

BACKGROUND: Adaptive upregulation of Androgen Receptor (AR) is the most common event involved in the progression from hormone sensitive to Castration-Resistant Prostate Cancer (CRPC). AR signaling remains the main target of new AR signalling-directed therapies such as abiraterone and enzalutamide in CRPC patients. OBJECTIVE: In this review, we discuss general mechanisms of resistance to AR-targeted therapies, with a focus on the role of AR Copy Number (CN). We reported methods and clinical applications of AR CN evaluation in tissue and liquid biopsy, thus to have a complete information regarding its role as predictive and prognostic biomarker. CONCLUSION: Outcomes of CRPC patients are reported to be highly variable as the consequence of tumor heterogeneity. AR CN could contribute to patient selection and tumor monitoring in CRPC treated with new anti-cancer treatment as abiraterone and enzalutamide. Further studies to investigate AR CN effect to these agents and its potential combination with other prognostic or predictive clinical factors are necessary in the context of harmonized clinical trial design.