CTLA4 and cancer: Until now, several immunotherapeutic agents that block immune checkpoints, such as those blocking programmed cell death 1 receptor (PD-1) (nivolumab/pembrolizumab/cemiplimab), PD-ligand-1 (PD-L1) (durvalumab/avelumab/atezolizumab), and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) (ipilimumab/tremelimumab), have been investigated and are now approved in different cancer entities.