CD8A and neoplasm: CARs are artificial fusion proteins that consist of extracellular antigen recognition and binding domain (scFvs), hinge; a modified spacer, CD28 or CD8, which redirects CAR-T cells to recognize tumor cells, intracellular signaling domain which activates T cells and transmembrane domains which connect the antigen-binding domain to the signaling domain [49,50,112,113,114] (Figure 2d).