GM-CSF and G-CSF increase the neutrophil count in patients with severe neutropenia secondary to myelodysplasia. Both neutrophil and eosinophil counts increase following administration of GM-CSF.27 Randomized studies demonstrated a decrease in the duration of neutropenia and improved treatment response associated with the use of G-CSF in patients receiving chemotherapy, or subsequent chemothera-peutic intervention.21'28 29 There was no evidence of any effect on duration of response or survival, although in one study higher remission rates and reduced infection rates allowed consideration of allo-geneic transplantation in a greater number of patients.29 There was no evidence of transformation to leukemia in either in these studies, in spite of theoretical risk to the contrary. However, prolonged administration of G-CSF in patients having more than 5% myeloblast counts is not recommended due to the potential risk of facilitating disease progression.
The use of erythropoietin is based on a relatively small, randomized placebo-controlled trial in low risk (refractory anemia without ring sideroblasts) myelodys-plasia. A fixed erythropoietin dose of 1050 U/kg per week led to an increase of hemoglobin by 1-2 g/dL of hemoglobin in 50% of low-risk patients, versus 6% in the control group.30 The addition of G-CSF or GM-CSF to erythropoietin may also have a synergistic effect on erythropoietic differentiation and response. In at least one study, administration of both G-CSF and erythro-poietin was required in order to generate and maintain an erythrocyte response.31 A predictive model based on serum epo level and prior transfusion requirements has been developed to guide the use of combination of G-CSF and erythropoietin in patients with myelodys-plasia.32
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