Effect of Granulocyte Colony-Stimulating Factor after Intensive Induction Therapy in Relapsed or Refractory Acute Leukemia

Background. Although colony-stimulating factors have been shown to accelerate recovery from severe neutropenia after intensive chemotherapy or bone marrow transplantation, their use in acute leukemia has been controversial because in vitro they stimulate leukemic colonies as well as normal granulocyte colonies. Methods. We conducted a prospective, randomized, controlled study to determine the safety and efficacy of recombinant human granulocyte colony-stimulating factor (CSF) after a standard course of intensive therapy in 108 patients with relapsed or refractory acute leukemia (67 with acute myelogenous leukemia, 30 with acute lymphocytic leukemia, 9 in blast crisis from chronic myelogenous leukemia, and 2 with acute leukemia arising from myelodysplastic syndromes). Treatment with granulocyte CSF (200 micrograms per square meter of body-surface area per day in a 30-minute infusion) was begun two days after the end of the chemotherapy and continued until the neutrophil count rose above 1500 per cubic millimeter. Results. Treatment with granulocyte CSF accelerated the recovery of neutrophils significantly (P less than 0.01), shortening it by about a week, but it had no effect on platelet recovery. Although the incidence of febrile episodes was almost the same, documented infections were significantly less frequent in the group treated with granulocyte CSF (P = 0.028). There was no evidence that granulocyte CSF accelerated the regrowth of leukemic cells. Fifty percent of 48 patients in the CSF group who could be evaluated and 36 percent of 50 controls had complete remission. The rate of relapse was almost the same in the two groups. Conclusions. It appears that recombinant human granulocyte CSF is safe in acute leukemia, accelerating neutrophil recovery and thereby reducing the incidence of documented infection without affecting the regrowth of leukemic cells. It should be used with caution, however, pending further confirmation of these early results.