Recombinant human interleukin-3 hastens trilineage hematopoietic recovery following high-dose (7 g/m2) cyclophosphamide cancer therapy

Background: Interleukin-3, a recombinant cytokine with multilineage stimulatory effect on hematopoietic cells, was administered to 22 previously untreated breast cancer patients following high-dose therapy with cyclophosphamide (7 g/m²). Patients and methods: The growth factor, administered through continuous intravenous infusion at 1 (3 patients), 2.5 (3 patients), 5 (10 patients) and 10 μg/kg/day (6 patients), was well tolerated up to 5 μg/kg/day. Results: Nausea, vomiting, fever and headache prevented administration of the intended dose to all 6 patients in the 10 μg/kg/day cohort. At the maximal tolerable dose (5 μg/kg/day) the growth factor significantly accelerated granulocyte, platelet and reticulocyte recovery as compared to matched historical controls who received high-dose cyclophosphamide without cytokine infusion. Moreover, no platelet transfusions and fewer erythrocyte transfusions were required in interleukin 3-treated patients. In contrast to GM-CSF and G-CSF, interleukin 3 showed no effect on the mobilization of hematopoietic progenitor cells in the peripheral blood. Conclusions: Interleukin-3 represents a well-tolerated cytokine, clinically useful for accelerating trilineage hematopoietic recovery following severely myelotoxic treatments such as high-dose cyclophosphamide.