Therapy for Neutropenia in Hairy Cell Leukemia with

man granulocyte colony-stimulating factor (G-CSF) is ef-fective in increasing neutrophil counts in patients with hairy cell leukemia and neutropenia. Design: Open label, phase I/II study of G-CSF, given by daily subcutaneous injection for up to 7 weeks. Setting: Outpatient oncology clinic of a university medical center. Patients: A consecutive sample of four patients with hairy cell leukemia complicated by severe neutropenia. Three pa-tients completed the study; one patient was removed after 2 weeks of therapy. Interventions: Granulocyte colony-stimulating factor was given by daily subcutaneous injection. Each patient began therapy with 1 jug/kg body weight • d; after 1 week the dose was increased to 3 jug/kg. d, and 1 week later to 6 fig/ kg • d. Therapy was continued for 5 to 6 weeks. Patients were taught self-injection, and administered treatment at home. Measurements and main results: In three patients, an in-crease in absolute neutrophil counts from less than 0.9 X 10VL to greater than 4.0 X 10VL was noted within 2 weeks of beginning G-CSF therapy. In two patients, infec-tions resolved during therapy. One patient developed acute neutrophilic dermatosis (the Sweet syndrome) while receiv-ing 3 juig/kg • d of G-CSF, and drug therapy was discontin-ued. Conclusions: Granulocyte colony-stimulating factor may increase neutrophil counts within 2 weeks in patients with hairy cell leukemia and neutropenia. This therapy may be a useful adjunct to definitive treatment of hairy cell leukemia with interferon or pentostatin