CD274 and breast neoplasm: Luminal-A breast tumors are less aggressive than TNBC tumors [1,2,3,4,5]; it has been previously demonstrated that the incidence of PD-L1 expression is lower in luminal-A patients than in TNBC patients, and that luminal-A cells in culture express very low levels, if any, of endogenous PD-L1 [26,27,28,29,30].