Impact of CD34+ cell dose on outcomes of haploidentical peripheral blood stem cell transplantation in acute leukemia

Abstract

Purpose Allogeneic hematopoietic stem cell transplantation remains a curative option for acute leukemia. While an adequate CD34+ cell dose is essential for engraftment, the optimal upper threshold in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) remains unclear. Methods We retrospectively analyzed 81 patients with acute leukemia who underwent haplo-PBSCT with reduced-intensity conditioning between 2010 and 2020. Patients were stratified by CD34+ cell dose (< 8 x 106/kg vs. >= 8 x 106/kg). Clinical outcomes, including overall survival (OS), non-relapse mortality (NRM), graft failure, and graft-versus-host disease (GVHD) incidence, were compared. Results A higher CD34+ cell dose was associated with inferior OS (P = 0.022) and increased NRM (P = 0.002), despite similar rates of graft failure and acute GVHD. Chronic GVHD was more frequent in the higher dose group, though the difference was not statistically significant. Multivariate Cox analysis confirmed a high CD34+ cell dose as an independent predictor of poor OS (HR 2.054, P = 0.031). Conclusion These findings suggest that excessively high doses may adversely affect survival by increasing transplant-related toxicity. Graft cell dose should be carefully balanced to optimize outcomes in haplo-PBSCT.