CTLA4 and acute myeloid leukemia: Some immune targets—including cytotoxic T lymphocyte antigen 4 (CTLA4), programmed cell death protein 1 ligand 2 (PDCD1LG2), indoleamine 2,3-dioxygenase 1 (IDO1), and hepatitis A virus cellular receptor 2 (HAVCR2)—promote the progression of AML [27–29].