Stable Response after Administration of Stem Cell Factor Combined with Granulocyte Colony-Stimulating Factor in Aplastic Anemia

We report successful treatment with 25 microg/kg of recombinant methionyl human stem cell factor (SCF) combined with 400 microg/m2 of recombinant human granulocyte colony-stimulating factor (G-CSF) in 2 patients with aplastic anemia refractory to immunosuppressive therapy. In one patient, hemoglobin levels increased from 6.4 g/dL to 11.3 g/dL after 36 weeks of SCF/G-CSF treatment. Thereafter, the platelet count (24.0 x 10(9)/L) began to improve without the therapy, and as of week 272, the platelet count was 125.0 x 10(9)/L with a leukocyte count of 8.4 x 10(9)/L and a hemoglobin level of 12.9 g/dL. In the other patient, more than 3 years of SCF/G-CSF treatment ameliorated hemoglobin levels and platelet counts from 5.8 g/dL to 15.9 g/dL and 8.0 x 10(9)/L to 50.0 x 10(9)/L, respectively. After cessation of SCF/G-CSF treatment, the positive response was sustained, and the platelet count improved further to 71.0 x 10(9)/L as of week 242. These observations suggest the clinical benefit of SCF/G-CSF administration to patients with refractory aplastic anemia.