CD274 and melanoma: Cancer cell-derived sEVs harboring PD-L1 can inhibit T cell functions, thus promoting tumor growth as demonstrated by two different studies: the first shows how breast cancer cell-derived sEVs can transfer PD-L1 to other cancer cells and block T cell activity through interaction with PD1 [102]; the second one reported that sEVs from human lung cancer, melanoma, or breast cancer express PD-L1 on their surface and that monitoring these circulating sEVs can be used to predict patient response to anti-PD1 therapy [103].