CD274 and breast carcinoma: This, in turn, inhibits the activation and infiltration of macrophages and promotes tumor growth, ultimately resulting in immune escape within breast cancer.650 Particularly, in TNBC, exosome-carried miR-20a-5p is internalized into CD8+ T cells, causing T-cell dysfunction and further conferring resistance to PD-1 therapy in TNBC.651 Moreover, miRNAs can control immune checkpoint molecules like PD-L1, aiding tumor cells in evading immune attacks.