Circulating Androgen Receptor for Prognosis and Treatment Selection in Prostate Cancer

Analysis of androgen receptor (AR) status, particularly AR copy number, in plasma DNA is a minimally invasive method with the potential to identify treatment resistance in patients with castration-resistant prostate cancer (CRPC) starting enzalutamide or abiraterone. Patients with elevated plasma AR do not have worse outcomes than patients with normal plasma AR when treated with taxanes. Consequently, circulating AR may improve clinical decision-making between AR-directed therapies versus taxanes and probably also between adapted versus standard taxane regimens. The evidence indicates that circulating AR could have a role in overall CRPC management. Promising clinical implications of plasma AR testing are measurement in earlier stages of prostate cancer, disease monitoring, and within the context of a multiplex biomarker strategy to improve treatment selection for CRPC patients. PATIENT SUMMARY: Measurement of the copy number of androgen receptor genes in plasma is a promising tool for guiding personalised treatment in patients with castration-resistant prostate cancer. However, prospective trials to validate these findings are needed.