Nivolumab in Prostate Cancer With DNA Repair Defects (ImmunoProst Trial)

This is a Phase II, two-stage, multi-center, single-arm, and open-label trial of Nivolumab (BMS-936558) in patients with metastatic castration-resistant prostate cancer (mCRPC) who have progressed to a taxane-based chemotherapy regimen previously. Eligible patients must have ECOG 0-2 and material for biomarker analysis. Prior enzalutamide, abiraterone and cabazitaxel are permitted but not necessary to enrollment. The germline and somatic DRD (BRCA1, BRCA2, ATM, PTEN, CHEK2, RAD51C, RAD51D, PALB2, MLH1, MSH2, MSH6, PMS2.) will be assessed by T-NGS of metastatic sites or by liquid biopsy. The primary endpoint is PSA 50 response rate (PSA50, following the Prostate Cancer Working Group 3 criteria). The trial will meet its endpoint if ≥ 3/29 men achieve a PSA50 response. The secondary endpoints will include progression-free survival (PFS), overall survival, radiologic PFS, PSA response rate at 6 and 12 months.