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.

Inclusion criteria

• Men with histologically, cytologically, or biochemically confirmed adenocarcinoma of the prostate
• On-going androgen deprivation with serum testosterone <50 ng/dL (<2.0nmol/L)
• Serum potassium >=3.5 mmol/L
• Eastern Cooperative Oncology Group (ECOG) Performance Status score <2 (Karnofsky Performance Status >=50%)
• No history of adrenal insufficiency or hyperaldosteronism
• Any acute toxicities of prior chemotherapy, radiotherapy have resolved to a NCI CTCAE (version 3.0) grade of <=1 (chemotherapy induced alopecia and grade 2 neuropathy are excluded from this consideration)
• No radiotherapy, chemotherapy, or immunotherapy within 30 days of administration of the study drug 1 (SD1) on Day 1
• No surgery or local prostatic intervention within 28 days of the first dose (any clinically relevant sequelae from the surgery must have resolved prior to SD1 on Day 1)
• Agrees to protocol-defined use of effective contraception
• Life expectancy >12 weeks

Exclusion criteria

• Active or uncontrolled autoimmune disease that may require corticosteroid therapy
• Serious or uncontrolled co-existent non-malignant disease, including active and uncontrolled infection
• Uncontrolled hypertension
• Protocol-defined laboratory values
• 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)
• Other malignancy within the previous 5-years other than basal cell or squamous cell carcinomas of skin with a >30% probability of recurrence within 12 months
• History of gastrointestinal disorders (medical disorders or extensive surgery) which may interfere with the absorption of the study medication
• 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