Outcomes of Hematopoietic Cell Transplantation in Children with Inborn Errors of Immunity: A Single-Center Series.

Inborn errors of immunity (IEI) are a heterogenous group of rare monogenic disorders that affect innate or adaptive immunity, resulting in susceptibility to life-threatening infections and autoimmunity. Allogeneic hematopoietic cell transplantation (HCT) is a valuable curative option for children with IEI. We conducted a retrospective single-center study on the outcome of HCT in children with IEI. Primary outcome was overall survival (OS). We gathered data from 55 patients underwent HCT in the period 2014 to 2023. The indications for HCT were CGD (n = 14), HLH (n = 12), SCID (n = 10), and others (n = 19). Median age at HCT was 3 years (range 0.1-17). Donors were HLA-matched related (n = 27), haploidentical (n = 24), and cord (n = 4). The conditioning regimens were myeloablative (n = 34), reduced intensity (n = 18), or no conditioning (n = 3). After a median follow-up of 43 months (range 13-120), 2-year OS was 93%, 2-year EFS 79% and 2 year GvHD-free relapse-free survival (GRFS) was 69%. Univariate analysis showed that bone marrow source was significantly associated with better EFS and GRFS. Cumulative incidence of grade 2-4 acute and moderate/severe chronic GvHD were 21% and 13%, respectively. Incidence of graft failure was 13%. In conclusion, HCT is feasible and curative in children with IEI. Early diagnosis and referral in addition to timely treatment can further improve outcomes.