CD274 and breast cancer: Presumably, the “immune hot” nature characterized by an simultaneous increase in PD-L1 expression and TIL score in BC with a TN or a HER2 subtype result from the enhanced local anti-tumor immune response (IFN-γ secretion by surrounding immune cells) triggered by the strong immunogenicity of BC and subsequent induced expression of PD-L1 on tumor cells mediated by IFN-γ signaling to inhibit potentially excessive immune response [40, 41].