Phase 1 study of lintuzumab conjugated to actinium-225 for relapsed or refractory AML

The anti-CD33 antibody lintuzumab has modest activity against AML. To increase it potency, lintuzumab was conjugated to actinium-225, a radionuclide yielding α-particles. A first-in-human phase 1 trial of patients with relapsed or refractory AML found that treatment with actinium-225-lintuzumab was feasible with an acceptable safety profile. Peripheral blood blasts were eliminated in 10 of 16 evaluable patients (63%) and bone marrow blasts were reduced in 10 of 15 evaluable patients (67%), including one patient with a morphologic leukemia-free state.