Response to recombinant human erythropoietin in patients with myelodysplastic syndromes.

Recombinant human erythropoietin (rhEPO) at pharmacological doses was used to improve anemia and reduce the transfusional requirements of 43 patients with myelodysplastic syndrome (MDS). rhEPO was given by s.c. injection three times per week for 12 weeks. The EPO dose was started at 150 IU/kg and was increased to 300 IU/kg if after 6 weeks there was no or suboptimal erythroid response. Responses were defined as being a complete response (CR), partial response (PR), or no response (NR). A CR was considered a rise in untransfused hemoglobin concentrations of at least 2 g/dl or a 100% decrease in RBC transfusion requirements over the treatment period. A PR was defined as an increase in untransfused hemoglobin values of 1-2 g/dl or a decrease in RBC transfusion requirements equal to or greater than 50%. NR was defined as responses less than a PR. Patients who responded to therapy were continued on rhEPO at the same dose for 6 additional months. An objective response (CR and PR) was observed in 7 of 42 (16.7%) assessable cases after 6 weeks of treatment at the dose of 150 IU/kg. Dose escalation (300 IU/kg) in nonresponders resulted in another six patients attaining a rise in hemoglobin concentrations. The final response rate was 13 of 41 (31.7%); 4 patients became transfusion independent. Therapy was tolerated well, with no relevant side effects. MDS progression was seen in one case. An elevated bone marrow erythroid infiltration (erythroid index) and detectable pretreatment circulating erythroid progenitors (burst-forming units-erythroid) were the best predictors of hemoglobin response when we controlled for other variables. These data suggest that rhEPO has a role in the treatment of certain patients with MDS, particularly in those with a high erythroid index and detectable circulating erythroid burst-forming units.