Stereotactic Body Radiation Therapy With REGN2810 and/or Ipilimumab Before Surgery in Treating Participants With Progressive Advanced or Oligometastatic Prostate Cancer

This phase I trial studies the side effects of anti-PD-1 monoclonal antibody REGN2810 (REGN2810) and/or ipilimumab when given together with stereotactic body radiation therapy before surgery in treating participants with prostate cancer that is growing, spreading, or getting worse, and has spread to other places in the body, or formed a small number of new tumors in one or two other parts of the body. Monoclonal antibodies, such as anti-PD-1 monoclonal antibody REGN2810 and ipilimumab, may interfere with the ability of tumor cells to grow and spread. Stereotactic body radiation therapy is a specialized radiation therapy that sends x-rays directly to the tumor using smaller doses over several days and may cause less damage to normal tissue. Giving anti-PD-1 monoclonal antibody REGN2810 and ipilimumab with stereotactic body radiation therapy before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed.