This study is comparing the safety and effectiveness of abiraterone acetate alone, followed by the addition of prednisone (when the participant's disease worsens or the physician feels it would lessen symptoms of toxicity) versus the current approved treatment regimen which involves the concomitant use of prednisone in conjunction with abiraterone acetate. Additionally, this study is also examining why participants stop responding to treatment with abiraterone acetate by evaluating blood and tissue.