However, several immune checkpoint molecules, mainly cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), programmed death-1 (PD-1), and programmed death-ligand 1 (PD-L1), suppress T-cell-mediated antitumour immune responses in the tumour microenvironment (TME) (45–47). Here, CTLA4 is linked to neoplasm.