Nivolumab in Patients With High-Risk Biochemically Recurrent Prostate Cancer

This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug to learn whether the drug works in treating a specific disease. "Investigational" means that the drug is being studied. The FDA (the U.S. Food and Drug Administration) has not approved nivolumab for this specific disease but it has been approved for other uses. Nivolumab is an antibody inhibitor of the programmed death-1 (PD-1) pathway. By blocking PD-1, this medication may allow the immune system to recognize and fight cancer. In this research study, the investigators are investigating whether nivolumab has any activity in patients who have a rising PSA (prostate specific antigen) after previously undergoing surgery or radiation for prostate cancer. Although nivolumab was previously not found to have significant effect in advanced prostate cancer after all other therapies had failed, based on new research, the investigators are testing whether nivolumab could have a greater effect earlier in the disease course and before patients receive hormone therapies.