αβ⁺/CD19⁺-depleted haploidentical stem cell transplantation for children with acute leukemia: Is there a protective effect of increased γδ⁺ T-cell content in the graft?

Background: Haploidentical hematopoietic stem cell transplantation (HSCT) with depletion of αβ⁺ T cells and CD19⁺ B cells has emerged as a viable alternative to traditional donors for treating acute leukemia in children. As the use of this innovative approach continues to grow and more experience is gained, it is essential to identify and comprehend the key factors that contribute to successful transplantation and improved outcomes. Methods: We conducted a retrospective analysis of single-center data from 27 children with acute lymphoblastic leukemia and 11 children with acute myeloid leukemia who underwent haploidentical HSCT with depletion of αβ⁺ T cells and CD19⁺ B cells between the years 2013 and 2020. Results: Engraftment was successful in 34 out of 38 patients (90%). The 5-year overall survival and event-free survival rates were 51% and 42%, respectively. There were no cases of grade III–IV acute graft-versus-host disease, and only two patients developed chronic graft-versus-host disease. Patients with a higher content of γδ⁺ T cells in the graft demonstrated a longer event-free survival. Conclusions: αβ⁺/CD19⁺-depleted haploidentical hematopoietic stem cell transplantation can offer long-term remission for children with acute leukemia with minimal graft-versus-host disease.