CJNJ-67652000 and Prednisone for Treatment of Metastatic Castration-Resistant Prostate Cancer and SPOP Gene Mutations

This phase II trial tests how well abiraterone acetate/niraparib (CJNJ-67652000 \[niraparib/abiraterone acetate fixed-dose combination\]) and prednisone works in treating patients with castration-resistant prostate cancer that has spread from where it first started (primary site) to other places in the body (metastatic) and who have a mutation in the SPOP gene. CJNJ-67652000 (niraparib/abiraterone acetate fixed-dose combination) is a drug which stops certain cancer cells from being able to repair themselves from damage, leading to the death of the cancer cell. Prednisone is in a class of medications called corticosteroids. It is used to reduce inflammation and lower the body's immune response to help lessen the side effects of chemotherapy drugs. Giving CJNJ-67652000 and prednisone may kill more tumor cells in patients with metastatic prostate cancer than giving these drugs alone.