A JNJ-56021927 (ARN-509; Apalutamide) QT/QTc Study

This is an open-label (a study in which the drug, procedure is known to participant and investigator), multicenter, Phase 1b study to investigate the effect of apalutamide on ventricular repolarization at a dose level of 240 milligram (mg daily). Approximately 42 participants with high-risk non-metastatic prostate cancer (NM-CRPC), defined as having a prostate specific antigen (PSA) doubling time less than or equal to (\<=) 10 months, or participants with metastatic CRPC will be enrolled. The study consists of a 28-day Screening Phase, a Treatment Phase and a Follow-up Phase. In the Treatment Phase the study drug will be administrated in cycles of 28 days and the participants will be monitored for safety (including cardiac safety) and pharmacokinetics of the study drug. Adverse Events will be monitored throughout the study and in the Follow-up Phase until 30 days after the last dose of study drug. All participants will continue on study until disease progression, withdrawal of consent, lost to follow-up, the occurrence of unacceptable toxicity, the participant is no longer receiving clinical benefit in the opinion of the investigator, or termination of the study by the sponsor. Upon discontinuation of study drug, the participants will return for an End-of-Treatment (EoT) visit no later than 30 days after their last dose. The end of the study corresponds to the clinical cutoff and end of data collection.