• To determine the safety and toxicity of HuM-195/rGel immunotoxin in patients with relapsed or refractory myeloid malignancies. [ Time Frame: 2010 ] [ Designated as safety issue: Yes ]
  

• To determine the pharmacology of HuM-195/rGel. To examine the biological effects of HuM-195/rGel including the ability to elicit antileukemic responses, human anti-human antibody (HAHA) and human anti-gelonin antibody (HAGA) responses. [ Time Frame: 2010 ] [ Designated as safety issue: Yes ]
  

Before therapy, all patients will be asked about their medical history, a physical exam will be performed, and vital signs will be taken. A chest X-ray, ECG, complete blood count, serum chemistry and urinalysis will be performed as well. During the study period, we will obtain samples to measure blood counts, serum chemistry, pharmacokinetics and anti-drug antibodies. A bone marrow sample will also be obtained on study day 28.

Patients will receive four injections of the immunotoxin. The immunotoxin is designed to selectively destroy myeloid leukemia cells. The injections will be given through a vein twice weekly for two weeks. Patients will then be evaluated twice weekly for the next two weeks. If there has been improvement in the leukemia, or if there have been no serious side effects of treatment, patients will then receive a second course of immunotoxin injections. These will again be given twice weekly for two weeks. Depending on the effectiveness against leukemia and the side effects, patients may receive maintenance treatment. This would also consist of two weekly injections given for two weeks followed by two weeks of observation. Maintenance therapy may continue for up to four months for partial response and up to two months for complete response.

This is an investigational study. Up to 36 patients will take part in this study.

Optional Procedures: Extra blood (1 tube or about 2 tablespoons) marrow samples will be taken at day 28 of study.

You do not have to agree to take part in the optional procedures in order to receive treatment on this study.

Inclusion Criteria:

1. Patients with relapsed or refractory AML, RAEB-t, RAEB, or CMML who failed at least one previous chemotherapy course. Patients with accelerated CML Ph+ or myeloid blastic crisis are eligible. Patients in blastic phase of non-Philadelphia chromosome + myeloproliferative disorders are also eligible, (blast phase of: 1) P. vera, 2) myelofibrosis, 3) essential thrombocytopenia with >30% 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. WBC count <10,000/ml for AML, MDS, and myeloproliferative disorders and up to 30,000 for accelerated CML.
6. No chemotherapy for the two weeks prior to entering the study.
7. No evidence of residual toxic effects 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 SGPT levels = or < 2.0 times the upper limit of laboratory normal values.
11. Cardiac function - Patients with cardiovascular disease should be < 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:

1) Women who are pregnant or lactating.