Granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor in the treatment of myeloid leukemia.

Hematopoietic growth factors primarily used in patients with acute myelogenous leukemia after chemotherapy could reduce significantly the neutrophil recovery time in all patients. In high-risk acute myelogenous leukemia, trials also reported a reduction in the incidence of documented infections and early mortality rate. Thus in elderly patients with acute myelogenous leukemia and in high-risk patients with acute myelogenous leukemia the use of hematopoietic growth factors seems justified. Whether the rate of infections, particularly of life-threatening fungal infections, can be reduced by granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor after chemotherapy cannot be known without larger studies. A novel strategy in the treatment of acute myelogenous leukemia is the attempt to increase the growth fraction of clonal leukemic cells prior to administration of chemotherapeutic agents by the administration of hematopoietic growth factors. Evidence shows that hematopoietic growth factors enhance anti-leukemic activity of cytosine arabinoside against leukemic cells by recruitment of leukemic cells into cell cycle, an increase of intracellular cytosine arabinoside triphosphate:deoxcytidine 5' triphosphate pool ratios, or by an enhanced cytosine arabinoside incorporation into the DNA of acute myelogenous leukemia blasts. Whether these mechanisms lead to an increase in the complete remission rate and eventually to an improvement in survival must be answered in ongoing larger acute myelogenous leukemia trials using granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor in such a setting.