Targeted Atomic Nano-Generators (Actinium-225-Labeled Humanized Anti-CD33 Monoclonal Antibody HuM195) in Patients With Advanced Myeloid Malignancies

Inclusion Criteria: * Patients must have one of the following pathologically confirmed diagnoses: * AML in relapse, * AML refractory to at least 2 courses of standard induction chemotherapy or one course of high-dose cytarabine-containing induction chemotherapy, * CML in accelerated phase or myeloid blast crisis that has progressed after treatment with imatinib and a second generation tyrosine kinase inhibitor (e.g., dasatinib or nilotinib) * RAEB with International Prognostic Scoring System (IPSS) score ≥ 2.5, or - CMMOL with IPSS score ≥ 2.5 refractory to or relapsed after a hypomethylating agent (e.g., azacitidine or decitabine) refractory to or relapsed after a hypomethylating agent (e.g., azacitidine or decitabine). * Greater than 25% of bone marrow blasts must be CD33 positive. * Patients must have a life expectancy of at least 6 weeks and a Karnofsky performance status of ≥ 60%. * Adequate renal function as demonstrated by a serum creatinine ≤ 1.5 mg/dl, a creatinine clearance \> 60 ml/min, and \< 1 gram urinary protein/24 hours. * Adequate hepatic function as demonstrated by a bilirubin ≤ 1.5 mg/dl (unless attributable to leukemia or Gilbert's disease) and alkaline phosphatase and AST ≤ 2.5 times the upper limit of normal. Exclusion Criteria: * Untreated AML, regardless of prognostic features. * Treatment with chemotherapy or biologic therapy within 3 weeks of 225Ac- HuM195 administration. Hydroxyurea is permitted but must be discontinued prior to treatment on study. Patients must have recovered from the effects of previous treatment. * Treatment with radiation therapy within 6 weeks of 225Ac-HuM195 administration. Patients must have recovered from the effects of previous treatment. * Active serious infections not controlled by antibiotics. * Pregnant women or women who are breast-feeding. * Concurrent active malignancy requiring therapy. * Clinically significant cardiac disease (NY Heart Association Class III or IV)or pulmonary disease. * Patients with HLA-compatible donor bone marrow who are immediate candidates for bone marrow transplantation. * Patients who are candidates for alternative treatments of known effectiveness. * Patients eligible for protocols of higher priority. * Patients previously treated with any monoclonal antibody for any reason. * Active CNS leukemia * Other serious or life-threatening conditions deemed unacceptable by the principal investigator.