[Treatment of aplastic anemia with KRN8601 (rhG-CSF)]

Thirty-nine patients with severe or moderate aplastic anemia received treatment with recombinant human granulocyte colony-stimulating factor (rhG-CSF). The first group of eight patients received rhG-CSF in doses of 100 to 400 micrograms/m2/d by a daily 30-minute intravenous infusion for one or two weeks. Doses up to 400 micrograms/m2/d were well tolerated and resulted in increases of neutrophil counts in 5 out of 8 patients. We gave rhG-CSF (400 micrograms/m2/d) to the second group of 26 patients by a daily 30-minute intravenous infusion for two weeks. The treatment resulted in an increase of neutrophil counts in 15 out of 26 patients (3.1 to 29.5 fold). Further, higher doses (800 or 1,200 micrograms/m2/d) were administered in 5 patients who did not respond to the dose of 400 micrograms/m2/d. The treatment increased the neutrophil counts in 3 out of 5 patients. The third group of five patients received rhG-CSF subcutaneously in doses of 20 to 400 micrograms/m2/d. An increase of neutrophil counts was noted in all five patients. Differential counts of bone marrow aspirate revealed an increase of myeloid: erythroid ratios. However, the responses were transient and neutrophil counts returned to basal levels within 1 approximately 2 weeks after discontinuing treatment. No severe toxicity due to rhG-CSF was observed. These results suggest that rhG-CSF is effective on stimulating granulopoiesis in patients with aplastic anemia. This treatment will be particularly useful for the patient with aplastic anemia suffering from bacterial or fungal infections.