CD33 and acute myeloid leukemia: Successful targeting of the lymphoid-specific molecule CD19 in chimeric antigen receptor (CAR) T cell therapy of acute lymphocytic leukemia, has led to attempts at also directing CARs to myeloid cell surface antigens, including CD33 (ref. 19), CD123 (ref. 20) and FLT3 (ref. 21), overexpressed on AML cells.