Association of CD34 Cell Dose with 5-Year Overall Survival after Peripheral Blood Allogeneic Hematopoietic Cell Transplantation in Adults with Hematologic Malignancies

Background : Higher CD34 cell dose is associated with improved engraftment after peripheral blood allogeneic hematopoietic stem cell transplantation (alloHCT), but may also increase the risk of long-term complications, such as graft-versus-host disease (GVHD). Prior studies examining the relationship between CD34 cell dose and long-term survival outcomes have yielded conflicting results. Objective : This study sought to clarify the prognostic impact of CD34 cell dose by examining a large, contemporary cohort of patients undergoing alloHCT with matched sibling peripheral blood stem cell (PBSC) donors. Study Design : We retrospectively examined the impact of CD34 cell dose on overall survival (OS), neutrophil engraftment, platelet engraftment, treatment-related mortality (TRM), relapse, acute GVHD grades II-IV and III-IV, and chronic GVHD in 377 consecutive patients undergoing alloHCT with PBSC graft source from matched sibling donors at the University of Minnesota from 2002-2015. Patients were classified into three groups based on tertile (T) of CD34 cell dose received (T1, Results : Multivariable analysis demonstrated that high CD34 cell dose was associated with superior 5-year OS (hazard ratio [HR] 0.57, P = 0.01) and more rapid platelet engraftment (HR 1.70, P Conclusion : Higher CD34 cell dose (>7.5 × 106/kg) is associated with superior OS at 5 years and improved engraftment but does carry an increased risk of chronic GVHD. These data support a target CD34 cell dose goal of 7.5 × 106/kg for peripheral blood sibling donors.