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)

Prior treatment

• 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

Other

• Small cell or neuroendocrine carcinoma of the prostate
• Known brain metastases
• At Screening need for parenteral or oral opioid analgesics (eg, codeine, dextropropoxyphene)

• 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.