 This is an investigational study. Abiraterone acetate is FDA approved in combination with prednisone for the treatment of patients with metastatic castration-resistant prostate cancer who have received prior chemotherapy containing docetaxel. Prednisone is FDA approved and commercially available as a corticosteroid. Enzalutamide is FDA approved and commercially available for the treatment of certain types of prostate cancer. Their combination with hormone therapy in patients with prostate cancer is investigational. 