Infused CD34+ cell dose predicts long-term survival in acute myelogenous leukemia patients who received allogeneic bone marrow transplantation from matched sibling donors in first complete remission

Allogeneic stem cell transplantation (ASCT) has improved the outcome of acute myelogenous leukemia (AML). To further improve the treatment outcome of ASCT in AML, finding a modifiable prognostic factor is mandatory. We evaluated the effect of CD34+ cell dose on survival in allogeneic bone marrow transplantation (BMT) from HLA-matched sibling donors for AML patients in first complete remission (CR1). The 99 patients included in our analysis were classified into high CD34+ cell dose group (CD34+ cells ≥ 2.5 × 106/kg) and low CD34+ cell dose group (CD34+ cells < 2.5 × 106/kg). The high CD34+ cell dose patients had better overall survival (5-year overall survival rate, 75% ± 6% vs 52% ± 9%; P = .01) and leukemia-free survival (5-year leukemia-free survival rate, 70% ± 6% vs 44% ± 9%; P = .04). CD34+ cell dose was the only independent prognostic factor in overall survival and leukemia-free survival. The high CD34+ cell dose group had a lower relapse incidence with a borderline statistical significance (5-year relapse rate, 27% ± 6% vs 50% ± 10%; P = .09). There were no differences in the engraftment of neutrophil and platelet, grade II-IV acute graft-versus-host disease (GVHD), extensive-stage chronic GVHD, and transplant-related mortality between the high and low CD34+ cell dose groups. We confirmed that high CD34+ cell dose favorably affects the outcomes in allogeneic BMT for AML. The effort to attain a high CD34+ cell dose should be pursued during bone marrow harvest in allogeneic BMT for AML in CR1.