Limited erythropoietic response to combined treatment with recombinant human interleukin 3 and erythropoietin in myelodysplastic syndrome

Twenty-two patients with myelodysplastic syndrome were treated with combined recombinant human erythropoietin and recombinant human interleukin 3 (rHuIL-3). All 22 patients were evaluable for toxicity and 21/22 for response. Thirteen patients (62%) required rHuIL-3 dose reduction because of toxicity. Nineteen experienced a 50% or greater rise in neutrophil count. Of seven patients with initial platelet counts of >100 000, three experienced increases of >15 000/ml while an equal number had a comparable decline. Five patients (21%) experienced a significant rise in reticulocyte count, and two transfusion-dependent patients experienced a significant decrease in transfusions. Erythroid burst-forming units were increased by ≥50% in nine of 11 patients after combined therapy. Similar changes were seen in multipotential colony-forming units. Clinical responses were comparable to results obtained with epo alone while toxicities due to IL-3 were significant.