A Study of Abiraterone Acetate Plus Low-Dose Prednisone Plus Androgen Deprivation Therapy (ADT) Versus ADT Alone in Newly Diagnosed Patients With High-Risk, Metastatic Hormone-Naive Prostate Cancer (mHNPC)

• Overall survival [ Time Frame: Up to the time of death from any cause (up to Month 60) ] [ Designated as safety issue: No ]
  

• Radiographic progression-free survival [ Time Frame: Up to disease progression or death from any cause (up to Month 60) ] [ Designated as safety issue: No ]
  
• Time to next skeletal-related event [ Time Frame: Up to Month 60 ] [ Designated as safety issue: No ]
  
• Time to prostate specific antigen progression [ Time Frame: Cycles 1-13 Day 1, Day 1 every other cycle starting Cycle 14 to end-of-treatment up to disease progression ] [ Designated as safety issue: No ]
  
• Time to next subsequent therapy for prostate cancer [ Time Frame: Up to Month 60 ] [ Designated as safety issue: No ]
  
• Time to initiation of chemotherapy [ Time Frame: Up to Month 60 ] [ Designated as safety issue: No ]
  
• Change in miRNA expression level [ Time Frame: Cycle 1 Day 1, Cycle 3 Day 1, and end-of-treatment visit (up to 30 days after last dose of study drug) ] [ Designated as safety issue: No ]
  
• Change in mRNA expression level [ Time Frame: Cycle 1 Day 1, Cycle 3 Day 1, and end-of-treatment visit (up to 30 days after last dose of study drug) ] [ Designated as safety issue: No ]
  
• Number of participants affected by an adverse event [ Time Frame: Up to 30 days after the last dose of study drug ] [ Designated as safety issue: Yes ]
  

This is a randomized (the treatment group is assigned by chance), double-blind (neither physician nor patient knows the treatment that the patient receives), placebo (an inactive substance that is compared with a drug to test whether the drug has a real effect in a clinical trial)-controlled study designed to determine if newly diagnosed (within previous 3 months) patients with mHNPC who have high-risk prognostic factors will benefit from the addition of abiraterone acetate and low-dose prednisone to ADT (LHRH agonists or surgical castration). Approximately 1270 patients will be enrolled in this study. Patients will be stratified by presence of visceral disease and Eastern Cooperative Oncology Group performance grade prior to randomization. The study protocol consists of the following phases: screening, double-blind treatment, and follow-up phase of up to 60 months to monitor survival status and subsequent prostate cancer therapy. Patients will be randomized in a 1:1 ratio to the active treatment group (abiraterone acetate 1000 mg daily plus prednisone 5 mg daily plus ADT) or the control group (ADT plus placebos). Treatment in 28-day cycles will continue until disease progression or the occurrence of unacceptable toxicity. Patients will be monitored for efficacy and safety throughout the study. Two interim analyses and a final analysis are planned for this study. In the event of a positive study result at either of the interim analyses or at the time of the final analysis, all participants will have the opportunity to enroll in an open-label extension phase that will allow participants to receive active drug (abiraterone acetate plus prednisone) for up to 3 years.