Inclusion Criteria:

          -  Histological or cytological diagnosis of prostate cancer

          -  Adequate bone marrow, kidney and liver function

          -  Hormone sensitive relapsing prostate cancer after definitive local therapy
             (biochemical relapse) OR

          -  Failed prior therapy with a novel hormone (e.g. enzalutamide, abiraterone) with
             documented progressive disease (post-novel hormone therapy CRPC)

        Exclusion Criteria:

          -  ECOG performance status greater than or equal to 2

          -  Concurrent immunotherapy for prostate cancer

          -  History of or active autoimmune disorders (including but not limited to: myasthenia
             gravis, thyroiditis, pneumonitis, rheumatoid arthritis, multiple sclerosis, systemic
             lupus erythematosus, scleroderma) and other conditions that disorganize or alter the
             immune system.

          -  History of inflammatory bowel disease.

          -  Current use of any implanted electronic stimulation device

          -  For biochemically relapsed patients, no concurrent use of ADT or orchiectomy and no
             known prior or current evidence of any metastatic involvement of distant organs

          -  For post-novel hormone patients, no concurrent treatment with a secondary hormone
             (e.g. enzalutamide, abiraterone), no metastasis to the liver or brain