Who is the best haploidentical donor for acquired severe aplastic anemia? Experience from a multicenter study

Background Haploidentical transplantation has been proposed as an effective treatment for severe aplastic anemia (SAA). The majority of patients have more than one HLA-haploidentical donor. Herein, we compared the outcomes between different donor-recipient relationships for optimal haploidentical donor selection in acquired SAA. Methods We conducted a multicenter study based on a registered database of 392 patients with SAA treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT) between 2006 and 2018. In total, 223 patients received grafts from father donors, 47 from mother donors, 91 from siblings, 29 from children, and 2 from collateral donors. Results Of the 381 patients who survived more than 28 days, 379 (99.5%) recipients were engrafted. The 2-year overall survival (OS) was 86.6 +/- 2.5%, 87.1 +/- 4.9%, 84.3 +/- 3.9%, and 92.2 +/- 5.1% for recipients of father, mother, sibling, and child grafts, respectively, (P = 0.706). The 2-year failure-free survival (FFS) was 82.8 +/- 2.7%, 86.7 +/- 5.1%, 80.8 +/- 4.2%, and 92.5 +/- 5.1% for recipients of father, mother, sibling, and child grafts, respectively, (P = 0.508). There was no difference in the incidence of either acute or chronic graft-versus-host disease (GVHD) among the different donor sources in multivariate analyses. There were also no differences in the OS or FFS among the different donor sources in the Cox regression analysis. However, OS was significantly better in the patients with a shorter history of aplastic anemia (< 12 months), better performance status (ECOG scores 0-1), or moderate graft mononuclear cell (MNC) counts (6-10 x 10(8)/kg), and in female recipients with male donors. The FFS was also higher in patients with a shorter history of aplastic anemia (< 12 months) and better performance status (ECOG scores 0-1). Conclusions Fathers, mothers, siblings, and children are all suitable haploidentical donors for patients with SAA.