Phase II Trial With a Recombinant Humanized Anti-CD33 Monoclonal Antibody (HuM195) in Patients With High Risk Primary Myelodysplastic Syndromes

OBJECTIVES: I. Assess the therapeutic activity of monoclonal antibody HuG1-M195 on peripheral blood and bone marrow blast cell count, blood leukocyte, reticulocyte, and platelet counts, and hemoglobin levels in patients with myelodysplastic syndrome with refractory anemia with excess blasts (RAEB) (greater than 10% bone marrow myeloblasts) or RAEB in transformation. II. Assess the efficacy of this drug in terms of duration of response in these patients. III. Evaluate the toxicity of this drug in these patients.

OUTLINE: Patients receive monoclonal antibody HuG1-M195 IV over 4 hours on days 1-4. Treatment repeats every 2 weeks for 4 courses in the absence of disease progression or unacceptable toxicity. Patients with progressive disease after 2 courses are removed from study. Patients with stable disease receive no further treatment after 4 courses. Patients with complete or partial response receive treatment for 4 additional courses. Patients are followed at 11 and 39 days after end of course 4, monthly for 4 months, then every 3 months thereafter for 1 year from study entry.

PROJECTED ACCRUAL: A total of 14-25 patients will be accrued for this study.