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 × 10⁶/kg vs. ≥ 8 × 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.