Similar outcomes of peripheral blood stem cells vs. bone marrow for human leukocyte antigen-matched unrelated donor transplantation in adult patients with acute myeloid leukemia using risk-adapted graft-versus-host disease prophylaxis

Background: In unrelated donor allogeneic stem cell transplantation (URD-SCT), most studies reported that peripheral blood stem cells (PBSC) resulted in higher incidence of acute and/or chronic graft-versus-host disease (GVHD) without survival benefits compared with bone marrow (BM). To overcome these shortcomings of PBSC, we have used a risk-adapted GVHD prophylaxis for patients that received HLA-matched URD-SCT, which was adding low-dose rabbit antithymocyte globulin (Thymoglobulin^®, 1.25 mg/kg for 2 d) to conditioning in the transplants with PBSC and not BM. Methods: To determine whether this strategy is effective, we analyzed 115 adult patients with acute myeloid leukemia who received HLA-matched URD-SCT with PBSC (n = 70) or BM (n = 45) using our risk-adapted GVHD prophylaxis strategy. Results: The PBSC group showed faster neutrophil (11 d vs. 13 d; P < 0.01) and platelet (12 d vs. 18 d; P < 0.01) engraftment compared with the BM group. No difference was observed in the incidence of acute GVHD grade II-IV at 100 d (54.3% vs. 64.4%; P = 0.38) and chronic GVHD at 4 yr (65.1% vs. 60.0%; P = 0.83). Other outcomes including the incidence of relapse (30.8% vs. 31.2%; P = 0.53), non-relapse mortality (13.5% vs. 6.9%; P = 0.24), disease-free survival (55.7% vs. 61.9%; P = 0.68), and overall survival (62.2% vs. 63.2%; P = 0.96) at 4 yr were not significantly different. Conclusion: Our risk-adapted GVHD prophylaxis strategy resulted in similar transplant outcomes including comparable incidence of GVHD between the PBSC and BM groups in HLA-matched URD-SCT.