A Study of Abiraterone Acetate in Metastatic Castration-Resistant Prostate Cancer Participants Who Responded Poorly to the First-line Combined Androgen Blockade Therapy

A Phase 4 Study of Zytiga in Poor-risk mCRPC (Metastatic Castration-Resistant Prostate Cancer) Patients Who Was Failed the First-line CAB (Combined Androgen Blockade) Therapy

The purpose of this study is to evaluate the percentage of participants achieving prostate-specific antigen (PSA) response by 12 weeks of therapy from baseline according to Prostate Cancer Clinical Trials Working Group (PCWG2) criteria.

This is a Phase 4, non-randomized, multi-center (when more than one hospital work on a medical research study), open label (identity of study drug will be known to participant and study staff), single arm study of abiraterone acetate to investigate its efficacy and safety in participants with metastatic castration-resistant prostate cancer (mCRPC) who failed the first-line combined androgen blockade (CAB) therapy. The study consists of Screening Phase (28 days prior to Cycle 1 Day 1), Treatment Phase (up to 2 years), Post Treatment Phase (30 days after the last dose of study drug). Participants will receive 1000 milligram (mg) (four 250 mg tablets) of abiraterone acetate orally once daily. In addition, 5 mg of oral prednisolone will be concomitantly administered twice a day (10 mg per day). A 28-daily dosing cycle will be continued until disease progression or unacceptable toxicity is observed. The total duration of study will be 2 years. Participants will be primarily evaluated for PSA response. Participants' safety will be monitored throughout the study.

Inclusion Criteria:

• Participants who have histologically or cytologically confirm adenocarcinoma of the prostate without neuroendocrine differentiation or small cell histology
• Participants who had prostate-specific antigen (PSA) progression defined as a rise of PSA at least 1 week apart resulting in 25 percent (%) increase in PSA with last PSA greater than (>) 2 nanogram per milliliter (ng/mL) (according to PCWG2) after antiandrogen withdrawal
• Participants who had PSA progression within a year after the start of first-line CAB therapy, or who had PSA progression without having a normal PSA level (less than [<] 4.0 ng/mL) in the first-line combined androgen blockade (CAB) therapy
• Participants who have not been treated with cytotoxic chemotherapy (including estramustine) for the treatment of prostate cancer (neoadjuvant or adjuvant chemotherapy is only allowed if the last dose is greater than or equal to [>=] 1 year from the scheduled date of initial administration of abiraterone acetate)
• Participants who have target or non-target metastatic abnormalities either on screening bone scan, computed tomography (CT) or magnetic resonance imaging (MRI)

Exclusion Criteria:

• A participant who has known allergies, hypersensitivity, or intolerance to abiraterone acetate or its excipients
• A participant who has severe liver dysfunction (Child-Pugh Score C), active or symptomatic viral hepatitis or chronic liver disease
• A participant who has received other hormonal therapy, including any dose of finasteride, dutasteride, any herbal product known to decrease PSA levels (example: Saw Palmetto and PC-SPES) within 4 weeks prior to the scheduled date of initial administration of abiraterone acetate
• A participant who has had surgery or local prostatic intervention within 4 weeks prior to the scheduled date of initial administration of abiraterone acetate
• A participant who has active infection or other medical condition that would make prednisolone use contraindicated