Adding checkpoint inhibitors to vaccine therapy in prostate cancers is controversial due to the slow progression of disease in many patients and the severe side-effects reported with anti-programmed cell death protein 1 (anti-PD1) and anti-cytotoxic T-lymphocyte associated protein 4 (anti-CTLA4) therapies in conjunction with androgen pathway inhibitors [41]. Here, PDCD1 is linked to prostate cancer.