In summary, the PD-L1 CCR may kill two birds with one stone: as a universal combinatorial antigen recognition target to reduce on-target off tumor cytotoxicity of engineered T cells in normal tissues but retain their effectiveness to kill tumor cells, and as a switch to turn “an immune brake” into “immune accelerator” and antagonize PD-L1 inhibition to improve the tumor-lytic activity of CAR-T cells [41, 42]. This evidence concerns the gene CD274 and neoplasm.