Hematopoietic cell transplantation for inborn errors of immunity: an update on approaches, outcomes and innovations

Purpose of review Allogeneic hematopoietic cell transplantation (HCT) is a curative option for many for inborn errors of immunity (IEI). This review highlights recent progress in the field of HCT for IEI. Recent findings Alternative donor transplantation continues to expand donor options for patients with IEI. Reduced intensity and reduced toxicity conditioning approaches are being investigated and optimized. Immunomodulatory bridging therapies are yielding impressive progress in outcomes for primary immune regulatory disorders (PIRD) but require further study in prospective trials. Single-institution, multicenter and consortium studies have improved our understanding of factors that affect overall outcomes in IEI and outcomes in Wiskott–Aldrich syndrome (WAS), chronic granulomatous disease (CGD) and PIRD in particular. Data show that second HCT offers a viable chance of cure to some IEI patients. Late effects in IEI HCT survivors are being better characterized. Preclinical studies of chemo(radiation)-free HCT strategies hold promise for decreasing HCT toxicity. Summary Improvements in our understanding of HCT donor choice, conditioning regimen, immunomodulatory bridging therapies, diagnostic and post-HCT surveillance testing and late effects continue to yield advancements in the field of HCT for IEI.