A pilot study of low-dose recombinant human granulocyte-macrophage colony-stimulating factor in chronic neutropenia

Recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) is under investigation for the treatment of a wide range of haematological disorders. At commonly used doses of > 120 micrograms/m2/d, extramedullary toxicity is common. We report the effects of low-dose (LD) rhGM-CSF in patients with chronic neutropenia related to HIV infection, myelodysplastic syndrome and idiopathic neutropenia. Nine patients with a mean pre-treatment neutrophil count of 0.6 x 10(9)/l (range 0.2-1.4 x 10(9)/l) received daily rhGM-CSF at doses of between 5 and 15 micrograms/m2. Eight patients responded with a mean post-treatment ANC of 3.2 x 10(9)/l (range 1.9-4.6 x 10(9)/l). There was no significant therapy-related morbidity. We conclude that in chronic neutropenia, LD rhGM-CSF is an acceptable treatment which has important cost/benefit implications.