A PILOT-STUDY OF THE BIOLOGIC AND THERAPEUTIC EFFECTS OF GRANULOCYTE-COLONY-STIMULATING FACTOR (FILGRASTIM) IN PATIENTS WITH ACUTE MYELOGENOUS LEUKEMIA

In a carefully monitored pilot study, the in vivo biologic effects of filgrastim were investigated in eight patients with relapsed/refractor y acute myelogenous leukemia. Within each patient, filgrastim was admi nistered as a single agent prior to any chemotherapy in escalating dos es of 0.12-6.0 mu g/kg/day as a continuous intravenous infusion. The d ose was increased every 14 days until an ANC of greater than or equal to 2500/mm(3) had been achieved or there was evidence of proliferation of the leukemia. In patients who demonstrated growth of the leukemic clone, cytosine arabinoside was initiated at 200 mg/m(2)/day for 5 day s. Throughout the course of therapy, the effects of filgrastim on matu ration and proliferation were assessed by in vitro studies of bone mar row aspirates. Three patients demonstrated a sustained increase in ANC ; one achieved a partial remission and remained on therapy for 31 week s. Two of the three responding patients had hypocellular marrows at th e time of initiating filgrastim and demonstrated a low but normal patt ern of growth in CFU-GM assay early in the treatment course. This sugg ested that these two characteristics may define an environment in whic h filgrastim can induce a growth advantage for the normal residual hem atopoietic elements. In this study of selected patients, filgrastim ap peared safe.