Enzalutamide for the treatment of castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) remains a major clinical challenge, given the mechanistic heterogeneity due to a complex signal transduction network. Enzalutamide (MDV-3100), recently approved by the U.S. Food and Drug Administration (FDA) at a dose of 160 mg/day for the treatment of CRPC, blocks androgen signaling by directly binding to the androgen receptor (AR) and inhibiting nuclear translocation and coactivator recruitment of the ligand-receptor complex. In preclinical studies, enzalutamide has been shown to block the binding of AR to DNA, resulting in apoptosis and retardation of tumor growth. Clinically, a phase I/II study (N = 140) revealed that enzalutamide had an optimal safety profile and significant antitumor activity in patients with CRPC regardless of prior chemotherapy. In the AFFIRM phase III trial (N = 1,199), oral enzalutamide significantly improved survival in men with metastatic CRPC after chemotherapy. Currently, a phase III trial (PREVAIL) is under way to determine the effectiveness of enzalutamide in patients who have not received prior docetaxel chemotherapy.