Prostate cancer is a heterogenous disease and recent genomic analyses have highlighted specific germline and somatic mutations and alternative driver growth signaling pathways in patients with metastatic disease. Abiraterone acetate plus prednisone (AA-P) is an established standard of care for the treatment of participants with mCSPC and is included in widely accepted clinical treatment guidelines. Niraparib is an investigational agent in the castration-sensitive cancer population and has been approved for the treatment of ovarian cancer. The addition of niraparib to the AA-P backbone regimen may improve initial disease control and long-term outcomes compared with AA-P alone in a biomarker selected population. The study will consist of 4 phases; a Prescreening Phase for biomarker evaluation for eligibility only, a Screening Phase, a Treatment Phase, and a Follow-up Phase. Efficacy evaluations include the following: tumor measurements by computed tomography (CT), magnetic resonance imaging (MRI; abdomen, chest, and pelvis), Technetium-99m (99mTc) bone scans, serum prostate sensitive antigen (PSA) evaluations, and patient reported outcomes (PROs). Safety evaluations include incidence of adverse events and clinical laboratory parameters.
The purpose of the study is to determine if the combination of niraparib with Abiraterone Acetate (AA) plus prednisone compared with AA plus prednisone in participants with deleterious germline or somatic Homologous Recombination Repair (HRR) gene-mutated Metastatic Castration-Sensitive Prostate Cancer (mCSPC) provides superior efficacy in improving radiographic progression-free survival (rPFS).