Immunotherapy combinations for metastatic castration-resistant prostate cancer – failed trials and future aspects

Purpose of review Immunotherapy, a treatment modality currently synonymous with immune checkpoint blockade remains a challenge for prostate cancer. Despite multiple phase 3 trials using checkpoint inhibitors in combinatorial approaches, there have been no benefits to date in overall survival or radiographic progression free survival. However, newer strategies prevail that are directed to a variety of unique cell surface antigens. These strategies include unique vaccines, chimeric antigen receptor (CAR) T, bispecific T cell engager platforms, and antibody-drug conjugates. Recent findings New antigens are being targeted by various immunologic strategies. These antigens are pan-carcinoma as they may be expressed on a variety of cancers but remains effective targets for therapeutic attack. Summary Immunotherapy with checkpoint inhibitors alone or in combination with a variety of agents such as chemotherapy, poly-ADP ribose polymerase (PARP) inhibitors or novel biologics have met with failure in the endpoints of overall survival (OS) and radiographic progresson-free survival (rPFS). Despite these efforts, other immunologic efforts to develop unique tumor-targeted strategies should be continued.