CD274 and breast carcinoma: From an immunological viewpoint, triple-negative breast cancer (TNBC) is currently considered the most immunogenic breast cancer (BC) subtype due to the high infiltration by tumor-infiltrating lymphocytes (TILs), more frequent tumor expression of programmed death–ligand 1 (PD-L1), and greater tumor mutational burden (TMB) compared with other forms of BC (1).