Study Comparing Niraparib with Abiraterone Acetate and Prednisone to Abiraterone Acetate and Prednisone Alone for Treating Metastatic Prostate Cancer

Inclusion Criteria

• Have a specific gene change related to DNA repair (HRR gene alteration) or be eligible based on HRR status.
• Have prostate cancer that has spread to other parts of the body, confirmed by scans.
• Have low testosterone levels due to treatment or surgery.
• Be able to continue hormone therapy if not surgically castrated.
• Have a pain score of 3 or less on a pain questionnaire about the worst pain in the last 24 hours.

Exclusion Criteria

• Have previously been treated with a PARP inhibitor.
• Have received certain other cancer treatments, like specific hormone therapies or chemotherapy, for more than 4 months before joining the study.
• Have cancer that has spread to the brain and is causing symptoms.
• Have a history or current diagnosis of certain blood disorders like MDS or AML.
• Have had another type of cancer within the last 2 years, unless it was a non-serious type like certain skin cancers or bladder cancer that is in complete remission.