CD274 and prostate cancer: While immunotherapy targeting cytotoxic T‐lymphocyte antigen 4 (CTLA‐4) and programmed death receptor 1 (PD1)/PD‐L1 immune check points has shown promising outcomes in the treatment for metastatic melanoma, lung cancer, renal cell carcinoma, and head and neck cancers, clinical trial results for prostate cancer have not been satisfactory (Topalian et al., 2012; Yoo et al., 2016).