A Safety and Efficacy Study of Oral MDV3100 in Chemotherapy-Naive Patients With Progressive Metastatic Prostate Cancer

Inclusion Criteria

• Histologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation or small cell features
• Ongoing androgen deprivation therapy with a GnRH analogue or bilateral orchiectomy
• Progressive disease despite androgen deprivation therapy as defined by rising PSA levels or progressive soft tissue or bony disease
• No prior treatment with cytotoxic chemotherapy
• Asymptomatic or mildly symptomatic from prostate cancer

Exclusion Criteria

• Severe concurrent disease, infection, or co-morbidity that, in the judgment of the Investigator, would make the patient inappropriate for enrollment
• Known or suspected brain metastasis or active leptomeningeal disease
• History of another malignancy within the previous 5 years other than curatively treated non-melanomatous skin cancer Open-Label Treatment Period: The following inclusion criteria apply to patients receiving enzalutamide or placebo during double-blind treatment. Eligible patients must meet all inclusion criteria.
• Received randomized double-blind treatment in PREVAIL;
• Open-label day 1 visit is within 6 months after this amendment is approved and becomes effective at the study site;
• Is willing to maintain androgen deprivation therapy with a gonadotropin-releasing hormone (GnRH) agonist/antagonist or has had a bilateral orchiectomy; The exclusion criteria apply only to patients starting new treatment with enzalutamide after receiving placebo as randomized treatment. Each patient must not meet any of the following criteria:
• Has taken commercially available enzalutamide (Xtandi);
• Severe concurrent disease, infection, or co-morbidity that, in the judgment of the Investigator, would make the patient inappropriate for enrollment
• Known or suspected brain metastasis or active leptomeningeal disease