Molecular Basis of Drug Resistance and Insights for New Treatment Approaches in mCRPC.

Inhibiting androgen receptor (AR) signaling with androgen deprivation therapy (ADT) represents the mainstay of therapy for advanced and metastatic prostate cancer. However, about 20-60% of patients receiving first-line treatment for prostate cancer will relapse, evolving in a more aggressive and lethal form of the disease, the castration-resistant prostate cancer (CRPC), despite the use of ADT. Multiple approved systemic therapies able to prolong survival of patients with metastatic CRPC (mCRPC) exist, but almost invariably, patients treated with these drugs develop primary or acquired resistance. Multiple factors are involved in CRPC treatment resistance and elucidating the mechanisms of action of these factors is a key question and an active area of research. Due to such a complex scenario, treatment personalization is necessary to improve treatment effectiveness and reduce relapse rates in CRPC. In this review, current evidence about the major mechanisms of resistance to the available prostate cancer treatments were examined by introducing insights on new and future therapeutic approaches.