CTLA4 and cancer: Immune checkpoint blockade (ICB) brings hope to late-stage cancer patients as its emergence in recent years altered treatment guidelines of many cancers drastically.[1] Currently there are 6 FDA-approved monoclonal antibodies including Nivolumab, Atezolizumab, Durvalumab, Pembrolizumab, Avelumab, and Ipilimumab that target programmed cell death-1 (PD-1) and its ligand (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4).