CD33 and acute myeloid leukemia: In comparison, early clinical trials of the unconjugated CD33 mAb lintuzumab without an added cytotoxic substance showed no clinical efficacy [24], yet clinical trials using conjugations with short-lived radionuclides such as 225Ac (α-particle decay) are underway (e.g., triple combination of venetoclax, azacitidine and lintuzumab-Ac225 in r/r AML patients (NCT03932318)).