Therapy for Neutropenia in Hairy Cell Leukemia with Recombinant Human Granulocyte Colony-Stimulating Factor

STUDY OBJECTIVE: To determine whether recombinant human granulocyte colony-stimulating factor (G-CSF) is effective 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 patients 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 microgram/kg body weight.d; after 1 week the dose was increased to 3 micrograms/kg.d, and 1 week later to 6 micrograms/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 increase in absolute neutrophil counts from less than 0.9 X 10(9)/L to greater than 4.0 X 10(9)/L was noted within 2 weeks of beginning G-CSF therapy. In two patients, infections resolved during therapy. One patient developed acute neutrophilic dermatosis (the Sweet syndrome) while receiving 3 micrograms/kg.d of G-CSF, and drug therapy was discontinued. 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.