A Pharmacokinetics Study to Assess Abiraterone Acetate Capsule and Tablet Formulations in Patients With Prostate Cancer

This is an open-label study (identity of assigned study drug will be known) to evaluate the pharmacokinetics of abiraterone acetate in patients with prostate cancer. The study will be conducted in 4 stages: Stage 1 will measure blood levels after patients take 1 daily dose of abiraterone tablet or capsule formulations with and without food; Stage 2 will measure blood levels of single daily doses of abiraterone tablet formulation taken with or without food in parallel design until disease progression (up to 12 cycles \[28 days per cycle\]); Stages 3 and 4 will evaluate the safety and antitumor effects of abiraterone tablet formulation administered with a low dose glucocorticoid in a fasted state for up to 12 months for each stage. As of Protocol Amendment 4, all patients who have completed 12 cycles of abiraterone acetate treatment and continue to receive clinical benefit from such a treatment will enter Stage 4 and receive abiraterone acetate in a fasted condition with a low-dose glucocorticoid. Patients will continue in Stage 4 for an additional 24 cycles. After patients complete the last study visit, they will be followed every 3 months for disease progression and survival for up to 3 years. Serial pharmacokinetic samples will be collected during Stages 1 and 2. Efficacy and safety will be monitored throughout the study.