An Efficacy and Safety Study of Niraparib in Men With Metastatic Castration-Resistant Prostate Cancer and DNA-Repair Anomalies

This is a multicenter and open-label (participants and researchers are aware of the treatment that participants are receiving) study that consists of 4 phases: a Prescreening Phase for biomarker evaluation only, a Screening Phase, a Treatment Phase (Cycle 1 Day 1 and will continue until the study drug is discontinued), a Follow-up Phase (every 3 months after end of treatment visit), and a Long-term Extension Phase (until participants no longer derive benefit from treatment or until further notification on different means of study treatment). Participants will be monitored for safety during the study period, and up to 30 days after the last dose of study drug.