An Efficacy and Safety Study of Apalutamide (JNJ-56021927) in Combination With Abiraterone Acetate and Prednisone Versus Abiraterone Acetate and Prednisone in Participants With Chemotherapy-naive Metastatic Castration-resistant Prostate Cancer (mCRPC)

This is a randomized (study drug assigned by chance), double-blind (neither the Investigator nor the participant know the treatment) placebo-controlled and multicenter (when more than 1 hospital or medical school team work on a medical research study) study to determine if participants with chemotherapy-naive mCRPC will benefit from the addition of apalutamide to AAP compared with AAP alone. The study consists of 3 phases: Screening phase; Treatment phase, and Follow-up phase. At the final analysis, the study will be unblinded. After the Independent Data Monitoring Committee (IDMC) review and the sponsor's subsequent decision participants will be offered to receive treatment either in the Open-Label Extension Phase or the Long-Term Extension Phase of study. Participants' safety will be monitored throughout the study.

Inclusion criteria

• Adenocarcinoma of the prostate
• Metastatic disease as documented by technetium-99m (99mTc) bone scan or metastatic lesions by computed tomography (CT) or magnetic resonance imaging (MRI) scans (visceral or lymph node disease). If lymph node metastasis is the only evidence of metastasis, it must be greater than or equal to (>=) 2 centimeter (cm) in the longest diameter
• Castration-resistant prostate cancer demonstrated during continuous androgen deprivation therapy (ADT), defined as 3 rises of PSA, at least 1 week apart with the last androgen deprivation therapy (PSA) >= 2 nanogram per milliliters (ng/mL)
• Participants who received a first generation anti-androgen (eg, bicalutamide, flutamide, nilutamide) must have at least a 6-week washout prior to randomization and must show continuing disease (PSA) progression (an increase in PSA) after the washout period
• Prostate cancer progression documented by prostate-specific antigen (PSA) according to the Prostate Cancer Clinical Trials Working Group (PCWG2) or radiographic progression of soft tissue according to modified Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST) modified based on PCWG2, or radiographic progression of bone according to PCWG2
• Participants who cross-over from Prednisone alone to open-label apalutamide plus AAP should still be in the double-blind phase of the study, should be receiving AAP alone and should have ECOG 0-1-2.

Exclusion criteria

• Small cell or neuroendocrine carcinoma of the prostate
• Known brain metastases
• Prior chemotherapy for prostate cancer, except if administered in the adjuvant/neoadjuvant setting
• Previously treated with ketoconazole for prostate cancer for greater than 7 days
• Therapies that must be discontinued or substituted at least 4 weeks prior to randomization include the following: a) Medications known to lower the seizure threshold, b) Herbal and non-herbal products that may decrease PSA levels (example [eg], saw palmetto, pomegranate) or c) Any investigational agent
• At Screening need for parenteral or oral opioid analgesics (eg, codeine, dextropropoxyphene)