Decreasing Dosing Regimens of Abiraterone 500 mg in Men With Prostate Cancer to Find Lowest Recommended Dose.

Doctors leading this study plan to collect new information about the lowest effective dose of abiraterone acetate in study participants with prostate cancer who are taking abiraterone in combination with prednisone for the first time. The duration of this study will be about 3 months (12 weeks). How long you stay on abiraterone, and at what dose after completion of the 12 weeks of study drug administration, will be up to you and your treating physician. Therefore, this study will evaluate if alternative dosing strategies with 500 mg pills may be equally effective as taking abiraterone 1000 mg daily. This study will specifically assess whether taking 500 mg of abiraterone every other day with a low-fat meal, or 500 mg with a low-fat meal at less frequent intervals (fewer times per week), is equally effective in treating prostate cancer as the 1000 mg/day dose.