Comparable Outcome with a Faster Engraftment of Optimized Haploidentical Hematopoietic Stem Cell Transplantation Compared with Transplantations from Other Donor Types in Pediatric Acquired Aplastic Anemia

Haploidentical family donors have been used as an alternative source in hematopoietic cell transplantation for patients with severe aplastic anemia. We evaluated and compared the outcomes of transplantation in pediatric acquired severe aplastic anemia based on donor type. Sixty-seven patients who underwent transplantation between 1998 and 2017 were included. Fourteen patients received grafts from matched sibling donors, 21 from suitable unrelated donors, and 32 from haploidentical family donors. Ex vivo CD3 ⁺ or αβ ⁺ T cell–depleted grafts were used for haploidentical transplantation. Sixty-five patients (97.0%)achieved neutrophil engraftment at a median of 11 days. Haploidentical transplantation resulted in significantly faster neutrophil engraftment at a median of 10 days, compared with 14 days in cases of matched sibling donors and 12 days in cases of unrelated donor recipients. Nine patients experienced graft failure, and 5 of 7 who underwent a second transplantation are alive. There was no difference in the incidence of acute or chronic graft-versus-host disease based on donor type. The 5-year overall survival and failure-free survival rates were 93.8% ± 3.0% and 83.3% ± 4.6%, respectively, and there was no significant survival difference based on donor type. The survival outcomes of haploidentical transplantation in patients were comparable with those of matched sibling or unrelated donor transplantation. Optimized haploidentical transplantation using selective T cell depletion and conditioning regimens including low-dose total body irradiation for enhancing engraftment may be a realistic therapeutic option for pediatric patients with severe aplastic anemia.