A LOW CD34+ cell dose is linked to worse survival after PTCy-haplo PBSCT, while donor age and HLA mismatches impact ATG-haplo outcomes.
T-cell-replete haploidentical peripheral blood stem cell transplantation (PBSCT) is increasingly used in patients without fully matched donors. However, the impact of donor characteristics on post-transplant outcomes remains uncertain, particularly when using post-transplant cyclophosphamide (PTCy) or low-dose antithymocyte globulin (ATG). This study analysed data from 1,677 patients who underwent PBSCT using either a PTCy (n=1,107) or ATG (n=570) protocol to identify factors influencing survival and complications.
Patients receiving PTCy-haplo transplants had worse overall survival (OS) if the donor provided a low CD34+ cell dose (<4 ×10⁶/kg; adjusted hazard ratio [aHR] :1.49, P=0.008). In contrast, for ATG-haplo transplants, increasing donor age (aHR: 1.12 per decade, P=0.008) and human leukocyte antigen (HLA) 2-3 antigen mismatches (aHR : 1.46, P=0.010) were linked to poorer OS. Donor age also influenced the risk of severe acute graft-versus-host disease (GVHD), with each decade of age increasing risk in both PTCy-haplo (HR: 1.32, P=0.009) and ATG-haplo (HR: 1.22, P=0.006) groups. Additionally, offspring donors provided better relapse-free and GVHD-free relapse-free survival compared to sibling donors in ATG-haplo transplants.
These findings offer crucial insights for donor selection in haploidentical PBSCT, highlighting the importance of CD34+ cell dose in PTCy-haplo transplants and donor age and HLA mismatching in ATG-haplo protocols. Clinicians should consider these factors to optimise survival and minimise complications. Further research is needed to refine donor selection criteria and improve transplant outcomes.
Katheeja Imani, EMJ
Reference
Wada Fbet al. Donor selection in T-cell-replete haploidentical donor peripheral blood stem cell transplantation. Leukemia. 2025;1-11.
