CTLA4 and cancer: Particularly important in this context is the overexpression of immunosuppressive immune checkpoints such as cytotoxic T lymphocyte-associated protein-4 (CTLA-4), programmed cell death protein-1 (PD-1), and programmed death-ligand 1 (PD-L1) in the local TME that may prevent the immune system, in particular T cells, from targeting and destroying cancer cells (1).