CTLA4 and cancer: With the discovery of inhibitory pathways in immune cells, so called checkpoint molecules, and the development of antibody-based blockades against these checkpoint molecules such as cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein (PD-1)/PD1 ligand 1(PD-L1), cancer immunotherapy is entering a new era [66].