A Study of Abiraterone Acetate Plus Prednisone in Patients With Metastatic Castration-Resistant Prostate Cancer Who Have Failed Docetaxel-Based Chemotherapy

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 with a randomization allocation ratio of 2:1 between the abiraterone acetate group (abiraterone acetate plus prednisone) and the placebo group (placebo plus prednisone). Approximately 200 (133 in the abiraterone acetate group and 67 in the placebo group) medically or surgically castrated male patients with mCRPC who have failed docetaxel-based chemotherapy will be enrolled in this study for up to 27 months. The study protocol includes the following phases: screening (within 28 days prior to randomization on Cycle 1 Day 1), double-blind treatment (28-day cycles until protocol-defined disease progression or unacceptable toxicity), and survival follow-up (up to Month 60). During the follow-up phase, patients with disease progression will be provided open-label (identity of assigned study drug will be known) extension treatment with abiraterone acetate. In the event of a positive study result at the time of the final analysis, participants in the placebo group who have not shown progressive disease in the double-blind treatment Phase of the study will be enrolled in an open-label extension treatment with abiraterone acetate treatment based on the participant's choice and treating physician's endorsement if they meet the criteria for subsequent abiraterone acetate. Abiraterone acetate 1000 mg tablets or placebo will be taken orally (by mouth) once daily plus prednisone 5 mg tablet orally twice daily. Efficacy and safety will be monitored throughout the study.