CD33 and acute myeloid leukemia: Alternatively, the antibody–thorium-227 radionuclide conjugate was crafted to target CD33-positive AML blast cells using the humanized anti-CD33 IgG1 antibody lintuzumab (5–7), underwent preclinical leukemic cell localized and disseminated xenograft mouse modeling and toxicology (8), and is now positioned to enter the clinic for first-in-human pharmacokinetic and pharmacodynamic studies.