CD33 and acute myeloid leukemia: Strikingly, we observed that there was appreciable and selective killing of CD123+ CD33+ AML blasts as well as BCMA+ CD138+ MM tumor cells in CD123xCD3 and BCMAxCD3 bispecific antibody treated cultures that had low stroma: tumor ratio (0.01x HS-5) and not when the cultures were treated with null controls (Fig. 7a, c).