The role of erythropoietin in the anemia of myelodysplastic syndrome.
Although erythropoietin (EPO) deficiency is not responsible for the anemia of myelodysplasia, pharmacologic doses of recombinant human EPO (rHuEPO, epoetin alfa) and epoetin beta have been studied extensively as treatment of anemia in myelodysplastic syndrome (MDS). When an epoetin is used as a single growth factor in patients with MDS, clinically meaningful responses occur in only a small minority of patients (16%). Patients who are transfusion-dependent are less likely to respond than patients who are transfusion-independent. Serum EPO level has a weak association with response rate and cannot be used to select or exclude patients from empirical trials of epoetins. The dose schedule commonly used as initial treatment 40,000 U/week, is consistent with clinical observations, but an optimal dose schedule has not been determined. The combination of an epoetin and granulocyte colony-stimulating factor (G-CSF) produces a higher erythroid response rate (36%) than the regimen of epoetin alone, but we have found no randomized trial data to support this point. However, the design of the clinical trials, which included adding G-CSF after epoetin alone had failed, supports the hypothesis that combined use of growth factors, rather than just higher doses of epoetin, is responsible for the high response rate observed with the combination of epoetin and G-CSF. Unfortunately, as in the case of epoetin alone, patients who are transfusion-dependent (> or =2 U red blood cells/month) are less likely to respond to combined growth factor therapy. Although the ability of patients with MDS to show an erythroid response to epoetin is of biologic interest, because of high costs and the limited response rate in transfusion-dependent patients, epoetin therapy, with or without G-CSF, cannot be regarded as a definitive therapy for the anemia of MDS.
Stein
Richard S
RS
Hematology/Oncology Division, Vanderbilt University School of Medicine, Nashville, TN 37232, USA. richard.stein@vanderbilt.edu
D000740:Anemia / Q000150:complications* / Q000209:etiology; D001803:Blood Transfusion; D002986:Clinical Trials as Topic; D004921:Erythropoietin / Q000502:physiology*; D016179:Granulocyte Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D009190:Myelodysplastic Syndromes / Q000150:complications* / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D013997:Time Factors
D004921:Erythropoietin; D016179:Granulocyte Colony-Stimulating Factor