Addition of erythropoietin to granulocyte colony-stimulating factor after priming chemotherapy enhances hemopoietic progenitor mobilization.

Hemopoietic progenitor cell mobilization intended for autotransplantation is now feasible in many patients, following the administration of single cytokines (G-CSF, GM-CSF, IL-3) or their combination. Erythropoietin (EPO) is a cytokine which showed an interesting activity also on non-erythroid progenitors, however the clinical relevance of this activity has not been sufficiently investigated yet. This retrospective study has attempted to assess the effectiveness of the combination of EPO plus G-CSF after priming chemotherapy to increase the number of blood progenitor cells, as compared to the results obtained by G-CSF alone. Thirty-four patients underwent priming chemotherapy followed by cytokine administration: 18 patients received G-CSF 5 micrograms/kg/day and 16 patients G-CSF plus EPO 50 U/kg/day. The two groups were homogeneous as regards the main clinical characteristics which are thought to affect BPC mobilization. As for hemopoietic progenitor cell mobilization, we observed that the combination of EPO and G-CSF was more effective in comparison with G-CSF alone, with a median of 1.9-fold for circulating MNC, 4.0-fold for CFU-GM, 4.7-fold for BFU-E and 2.8-fold increase for CD34+ cells. The results of apheresis collections revealed that the same group of patients showed better results for total blood progenitor cells/kg. The difference was statistically significant both for BPC mobilization and collection. Our findings suggest that EPO has a synergistic activity with G-CSF in mobilizing hemopoietic progenitors; the good results obtained, despite our pretreated patients, suggest that this cytokine combination has both biologic and clinical relevance.