Recombinant human erythropoietin therapy after allogeneic hematopoietic cell transplantation with a nonmyeloablative conditioning regimen: low donor chimerism predicts for poor response.

PURPOSE After allogeneic hematopoietic stem cell transplantation with nonmyeloablative conditioning (NMHCT), many patients experience prolonged anemia and require red blood cell (RBC) transfusions. We enrolled 60 consecutive patients undergoing NMHCT in a phase II trial to determine the optimal utilization of recombinant human erythropoietin (rHuEPO) therapy in this setting. PATIENTS AND METHODS The first 14 NMHCT recipients did not receive rHuEPO (control group). Nineteen patients were scheduled to start rHuEPO on day 0 (EPO group 2) and 27 patients on day 28 after the transplant (EPO group 1). RHuEPO was administered subcutaneously once weekly at a dose of 500 U/kg/wk with the aim of achieving hemoglobin (Hb) levels of 13 g/dL. The 3 groups were well balanced for major characteristics. RESULTS During the first month (p < 0.0001) as well as days 30 to 100 (p < 0.0001) and days 100 to 180 (p < 0.0001), Hb values were higher in patients receiving rHuEPO compared to those not receiving it. However, transfusion requirements were significantly decreased only in the first month in EPO group 2 (p = 0.0169). T-cell chimerism above 60% on day 42 was the best predictor of Hb response (p < 0.0001) or Hb correction (p = 0.0217), but myeloid chimerism above 90% also predicted for Hb response (p = 0.0069). Hb response was also decreased in patients receiving CD8-depleted grafts and increased in the few patients not receiving TBI, but only in univariate analysis. CONCLUSIONS Anemia after NMHCT is sensitive to rHuEPO therapy, but less so than after conventional allogeneic HCT. RHuEPO decreases transfusion requirements only in the first 30 days posttransplant. T-cell chimerism below 60% on day 42 impaired Hb response, suggesting possible inhibition of donor erythropoiesis by residual recipient lymphocytes. A prospective randomized trial should be performed with rHuEPO starting on the day of transplantation to assess its clinical benefit in terms of transfusion requirements and quality of life.