Despite impressive survival benefits with immunotherapy in patients with various solid tumors, the full potential of these agents in prostate cancer has yet to be realized. Sipuleucel-T demonstrated a survival benefit in this population, indicating that prostate cancer is an immunoresponsive disease; however, these results have not been matched by other agents. A large trial with ipilimumab in prostate cancer failed to meet its primary objective, and small trials with PD-1/PD-L1 inhibitors did not yield a significant improvement in overall response. However, several late-stage clinical trials are underway with other vaccines in prostate cancer. Reports of clinical benefit with immunotherapies, particularly when used in combination or a select population, have provided the framework to develop sound clinical trials. Understanding immunogenic modulation, antigen spread, biomarkers, and DNA-repair defects will also help mold future strategies. Through rational patient selection and evidence-based combination approaches, patients with prostate cancer may soon derive durable survival benefits with immunotherapies.
Animals ; Antineoplastic Agents, Immunological/therapeutic use* ; Antineoplastic Combined Chemotherapy Protocols/therapeutic use* ; B7-H1 Antigen/antagonists & inhibitors* ; Benzamides ; CTLA-4 Antigen/antagonists & inhibitors* ; Cancer Vaccines/therapeutic use* ; Humans ; Immunotherapy ; Ipilimumab/therapeutic use* ; Male ; Nitriles ; Phenylthiohydantoin/analogs & derivatives* ; Programmed Cell Death 1 Receptor/antagonists & inhibitors* ; Prostatic Neoplasms/drug therapy* ; Tissue Extracts/administration & dosage*