This clinical trial is focused on studying a type of prostate cancer known as metastatic castration-sensitive prostate cancer (mCSPC) that has specific genetic changes called homologous recombination repair (HRR) gene mutations. The study is testing a combination of medications to see if they can improve outcomes for patients with this type of cancer. The medications being tested include niraparib, abiraterone acetate, and prednisone. Niraparib is a medication that may help prevent cancer cells from repairing themselves, while abiraterone acetate and prednisone are used to manage prostate cancer by reducing the levels of male hormones that can promote cancer growth.

The purpose of the study is to determine if the combination of niraparib with abiraterone acetate and prednisone is more effective than using abiraterone acetate and prednisone alone. Participants in the study will be randomly assigned to receive either the combination of all three medications or just abiraterone acetate and prednisone. Some participants may receive a placebo instead of niraparib. The study will be conducted over a period of time, and participants will take the medications orally in the form of tablets or capsules. The study aims to observe the effects of these treatments on the progression of the cancer.

Throughout the study, participants will undergo regular monitoring, which may include imaging tests like computed tomography (CT) or magnetic resonance imaging (MRI) to track the cancer’s response to the treatment. The study will help researchers understand if the new combination of medications can provide better outcomes for patients with HRR gene-mutated mCSPC. The study is expected to continue until 2027, with the goal of improving treatment options for this specific type of prostate cancer.