The purpose of this study is to provide access to abiraterone acetate for patients who have completed 12 cycles of abiraterone acetate treatment in Clinical Study COU-AA-001 and continue to receive clinical benefit from this treatment.

This is an open-label (identity of study drug will be known) extended access study to evaluate the safety and efficacy of continued administration of abiraterone acetate in patients who have completed 12 cycles of abiraterone acetate treatment in Clinical Study COU-AA-001 and continue to receive clinical benefit from this treatment. Patients will continue with the same dose regimen administered at the end of Study COU-AA-001 and will receive a low-dose glucocorticoid daily. Patients will be followed every 3 months for disease progression and survival for up to 3 years following study entry. Safety will be monitored throughout the study up to 30 days after the last dose of study medication.

Inclusion Criteria:

• Completed 12 cycles of abiraterone acetate under study COU-AA-001
• Last dose of abiraterone acetate within 14 days prior to treatment in this study
• Demonstrates potential to gain clinical benefit with continued abiraterone acetate treatment
• Serum potassium level >=3.5 mmol/L
• Eastern Cooperative Oncology Group Performance Status of <3 (Karnofsky Performance Status >=30%)
• Agrees to protocol-defined use of effective contraception

Exclusion Criteria:

• Serious or uncontrolled co-existent non-malignant disease, including active and uncontrolled infection
• Uncontrolled hypertension
• Abnormal liver function
• Clinically significant heart disease as evidenced by a myocardial infarction in the past 12 months, severe or unstable angina, or New York Heart Association (NYHA) Class III or IV heart disease (patients with a history of atherosclerotic vascular disease requiring coronary or peripheral artery bypass surgery may be enrolled provided the surgery occurred at least 2 years prior to enrollment and after consultation with a cardiologist to insure that the disease is stable)
• Condition or situation which, in the investigator's opinion, may put the patient at significant risk, may confound the study results, or may interfere significantly with patient's participation in the study