Adding growth factors or interleukin-3 to erythropoietin has limited effects on anemia of transfusion-dependent patients with myelodysplastic syndromes unresponsive to erythropoietin alone.

Background and Objectives: Recombinant erythropoietin (r-EPO) induces erythroid responses in patients affected by myelodysplastic syndromes (MDS). However, the response rate declines to 10-15% in MDS with substantial transfusion needs. Both in vitro and in vivo studies have suggested that the addition of growth factors (G-CSF, GM-CSF) or interleukin-3 (IL-3) may potentiate the effect of r-EPO on dysplastic erythropoiesis. The aim of this study was to evaluate the effects of the combination of r-EPO with G-CSF, GM-CSF or IL-3 on the anemia of heavily transfusion-dependent MDS patients, previously unresponsive to r-EPO alone.
Patients and Methods: Sixty patients with transfusion-dependent MDS, already treated without significant erythroid response with r-EPO alone, were scheduled to receive, for at least 8 weeks, r-EPO subcutaneously at the dose of 300 U/kg t.i.w. in combination with G-CSF (300 microcg s.c. t.i.w., 27 patients), or GM-CSF (300 microcg s.c. t.i.w., 23 patients), or IL-3 (5 microcg/kg s.c. t.i.w., 10 patients), after a two-week pre-phase during which G-CSF, GM-CSF and IL-3 were administered daily at the same dose, as single drugs.
Results: Ten patients were not evaluable for erythroid response because of relevant side effects related to GM-CSF or IL-3 administration. Overall, among 50 patients who completed the study, there were 3 erythroid responses (as determined by complete abolition of red-cell transfusions): 1 (4%) in the G-CSF + r-EPO and 2 (10.5%) in the GM-CSF + r-EPO treated groups. No patient responded to the combination of r-EPO + IL-3. All responders had inappropriate serum levels of endogenous EPO and a relatively short disease duration. Both responders to GM-CSF + r-EPO developed acute myeloid leukemia 2-9 months after the start of the combined therapy. A third elderly patient, treated with the same association, developed marrow hypoplasia. A significant increase in leukocyte count occurred in 96% of patients who received r-EPO + G-CSF, 78.9% of those treated with r-EPO + GM-CSF and 66% of subjects receiving r-EPO + IL-3. A significant increase in platelet count was observed in a single patient receiving r-EPO and GM-CSF, while a slight decrease in platelet count with respect to baseline levels occurred in about 20% of patients.
Interpretation and Conclusions: Our results suggest that the combination of r-EPO with G-CSF, GM-CSF or IL-3, at least at the doses and schedules employed in the present study, has limited efficacy on the anemia of heavily transfusion-dependent MDS patients previously unresponsive to r-EPO alone. However, in this setting of patients, the combination of G-CSF or GM-CSF + r-EPO may occasionally be effective in subjects with low circulating levels of serum EPO and short disease duration.