GRANULOCYTE-COLONY-STIMULATING FACTOR (RH G-CSF) AS AN ADJUNCT TO INTERFERON-ALPHA THERAPY OF NEUTROPENIC PATIENTS WITH HAIRY-CELL LEUKEMIA

Six patients with hairy cell leukemia (HCL) and neutropenia (median ne utrophil count 563/mul, range 30-1200) were treated with recombinant h uman granulocyte colony-stimulating factor (G-CSF) at a dose of 5 mug/ kg by daily subcutaneous injection as an adjunct to interferon-alpha ( IFN-a) therapy, in order to ameliorate neutropenia. Five of six patien ts responded to G-CSF with normalization of neutrophil counts (>1800/m ul) within 2-11 days and a median neutrophil count of 5211/mul (range 4312-10160) at the end of G-CSF therapy. In three of these patients, i nfections resolved when neutropoiesis recovered. In one patient with v ery severe neutropenia (30/mul), in whom myeloid progenitors were not detectable, G-CSF therapy failed to restore granulopoiesis. Cessation or interruption of G-CSF after 2-5 weeks of therapy resulted in a rapi d decline of neutrophil counts to lower or subnormal levels (median va lue 1478/mul, range 770-2739) within 1 week, suggesting that the impro vement of granulopoiesis was dependent on G-CSF and not due to IFN-a t herapy. G-CSF may be a useful adjunct to IFN-a therapy in patients wit h HCL in order to manage or prevent neutropenic complications in the e arly phase of treatment.