Effect of Inflammatory Bowel Disease on Clinical Outcomes of Hematopoietic Cell Transplantation for Inborn Errors of Immunity.

Inflammatory bowel disease (IBD) is a phenotype of patients with inborn errors of immunity (IEI). Allogeneic hematopoietic cell transplantation (HCT) is an established curative treatment for IEI; however, the effect of IBD on HCT outcomes is unclear. We evaluated the impact of IBD on post-HCT prognosis in pediatric patients with IEI. We used the Japanese transplant registry database to retrospectively analyze the medical records of 625 patients with pediatric IEI who underwent allogeneic HCT between 2007 and 2022 to evaluate the clinical impact of IBD on these patients. Sixty-six (10.6%) patients had concurrent IBD before HCT. Compared with patients without IBD, those with IBD did not show inferior overall survival, transplant-related mortality, or neutrophil and platelet engraftment. Moreover, no significant differences were observed in the incidence of acute or chronic graft-versus-host disease (GVHD) between the two groups. However, the IBD group had a higher incidence of acute gastrointestinal GVHD. These findings remained consistent even after propensity score matching, accounting for the identified risk factors, including age at HCT, performance status, total HCT-specific comorbidity index score, HLA mismatch, era of HCT, and underlying disease classification. IBD has a limited effect on HCT outcomes in patients with pediatric IEI, despite the higher incidence of acute gastrointestinal GVHD. Nevertheless, in this study, we included patients with heterogeneous and complex disease backgrounds, indicating the need for further investigation to confirm the findings.