The role of collateral related donors in haploidentical hematopoietic stem cell transplantation.

A key issue in the haploiedntical hematopoietic stem cell transplantation (haplo-HSCT) setting is the search for the best donor, because donor selection can significantly impact the clinical outcomes. We aimed to identify the role of collateral related donors (CRDs) in donor selection for haplo-HSCT through comparing the clinical outcomes between CRDs (n = 60) and maternal donors (MDs, n = 296), which were the last choice of donor selection in immediate related donors (IRDs). The cumulative incidence of graft-versus-host disease was comparable between CRDs and MDs. The 5-year cumulative incidence of relapse and non-relapse mortality was 22.0% (95% CI, 11.3%-32.7%) versus 17.4% (95% CI, 13.0%-21.8%) (P = 0.455) and 25.0% (95% CI, 13.9%-36.1%) versus 23.1% (95% CI, 18.2%-28.0%) (P = 0.721) for the CRDs and MDs, respectively. The 5-year probabilities of disease-free survival and overall survival was 53.2% (95% CI, 40.4%-66.0%) versus 59.5% (95% CI, 53.8%-65.2%) (P = 0.406) and 56.5% (95% CI, 43.8%-69.2%) versus 61.8% (95% CI, 56.1%-67.5%) (P = 0.458) for the CRDs and MDs, respectively. Female donor/male recipient (FDMR) CRDs were associated with the poorest clinical outcomes, and the clinical outcomes of non-FDMR CRDs were comparable to those of MDs. In summary, our results showed that CRDs did not showed superiority over MDs. Thus, IRDs should be the first choice of donor selection, and CRDs could only be the donors for those without IRDs.