CD274 and neoplasm: The secretion of immunosuppressive cytokines, namely TGF-βand IL-10; suppressive immune cells, such as myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs) and tumor-associated macrophages (TAMs) or neutrophils (TANs); and checkpoint inhibitory proteins including PD-L1 damage efficient anti-tumor function of the CAR T cells.