CD274 and acute myeloid leukemia: Monoclonal antibodies against immune checkpoint proteins such as CTLA‐4 (ipilimumab), PD‐1 (nivolumab and pembrolizumab) and its ligand PD‐L1 (durvalumab), TIM‐3 (MBG453) are under active clinical investigation in high risk as well as refractory/relapsed AML.3