Evaluation of the Anti-CD-33 Immunotoxin Hum-195/rGel in Patients With Advanced Myeloid Malignancies

Inclusion Criteria: 1. Patients with relapsed or refractory acute myelogenous leukemia (AML), Refractory anemia with excess blasts in transformation (RAEB-t), Refractory Anemia with Excess Blasts (RAEB), or chronic myelomonocytic leukaemia (CMML) who failed at least one previous chemotherapy course. Patients with accelerated CML Ph+ or myeloid blastic crisis are eligible. Patients in accelerated phase of non-Philadelphia chromosome + myeloproliferative disorders are also eligible: * P. vera, * myelofibrosis * essential thrombocytopenia with \>5% blasts in the blood or bone marrow. 2. Male or female 18 yrs of age or older who have provided written informed consent 3. Tumor cells must be = or \> 80% CD33 positive by flow cytometry 4. For women of childbearing potential (i.e. exclude post-menopausal women, women who have been surgically sterilized), adequate birth control methods must be used. Acceptable birth control methods are limited to oral contraceptives, implants, diaphragm, IUD or spermicide used with a condom 5. White blood count (WBC) count \<10,000/ml for AML, MDS, and myeloproliferative disorders and up to 30,000 for accelerated CML 6. No cytotoxic chemotherapy for the two weeks prior to entering the study 7. No evidence of residual toxic effects grade 2 or higher from prior chemotherapy 8. Patients with proven bacterial infection are not eligible until resolution of the infection (patient afebrile, not on steroids). Patients with active fungal infections are eligible only if evidence of response to antifungal medications is documented and they do not have fever exceeding 38°C 9. Creatinine - Patients should have values = or \< 1.5 times the upper limit of laboratory normal values 10. Liver function - Patients should have serum bilirubin values = or \< 2.0 times the upper limit of laboratory normal values. Patients should have SGOT and/or SGPT levels = or \< 2.5 times the upper limit of laboratory normal values 11. Cardiac function - Patients with cardiovascular disease should be \< New York Heart Association (NYHA) classification III 12. Pulmonary function - O2 saturation should be = or \> 92% without exogenous O2 administered. 13. Neurologic function - Patients should have normal central nervous system function as well as normal motor function consistent with = or \< Grade 1 toxicity. Patients should have peripheral sensory function damage (neuropathy) not exceeding Grade 1 toxicity Exclusion Criteria: Women who are pregnant or lactating