Matched versus Haploidentical Hematopoietic Stem Cell Transplantation as Treatment Options for Primary Immunodeficiencies in Children.

Primary immunodeficiencies (PIDs) are inherited disorders of the immune system with allogeneic hematopoietic stem cell transplantation (HSCT) as the only curative treatment in some of them. In case an HLA-matched donor is not available, HSCT from a haploidentical family donor may be considered. We compared the outcomes of HSCT from HLA-matched unrelated or related donors (MUDs or MRDs) and mismatched related haploidentical donors (MMRDs) in patients with a variety of PIDs in 2 centers. A total of 44 pediatric patients were evaluated. We reviewed the outcomes of 25 children who underwent transplantation with HLA-matched grafts (MRD, n = 13; MUD, n = 12) and 19 patients receiving haploidentical stem cells. Bone marrow (BM) was transplanted in 85% (MRD) and 75% (MUD) of the matched cohort and peripheral blood stem cells (PBSCs) in 15% (MRD), 25% (MUD), and 100% (MMRD). All but 9 patients (MRD, n = 6; MMRD, n = 3) with severe combined immunodeficiency (SCID) received a chemotherapy-based conditioning regimen. Immune reconstitution of T, B, and natural killer cells was comparable for all groups with an advantage of recipients of MRD grafts in early CD4 reconstitution. However, deaths due to viral infections occurred more often in the haploidentical cohort. The disease-free survival was 91.7% (MRD), 66.7% (MUD), and 62.7% (MMRD), respectively. Grade II to IV acute graft-versus-host disease (GVHD) occurred in 15% (MRD), 8% (MUD), and 21% (MMRD) of the patients. Only 1 patient had severe grade IV GVHD in the MRD group, whereas no grade >II GVHD was observed in the MUD or MMRD cohort. These data indicate that in the absence of a suitable HLA-identical family donor, haploidentical HSCT may be a viable option for patients with life-threatening disease and urgent need of HSCT.