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.