Post-Transplant Late Complications Increase Over Time for Patients with SCID: A Primary Immune Deficiency Treatment Consortium (PIDTC) Landmark Study

To investigate outcomes of hematopoietic cell transplantation (HCT) for severe combined immunodeficiency (SCID), the Primary Immune Deficiency Treatment Consortium (PIDTC) enrolled children in the United States and Canada in a retrospective, multi-center natural history study. We evaluated the chronic and late effects (CLE) after HCT for SCID in 399 patients transplanted from 1982-2012 at 32 PIDTC centers. Eligibility criteria included survival to at least 2 years post-HCT without need for subsequent cellular therapy. CLE were defined as either conditions present at any time before 2 years from HCT that remained unresolved (chronic), or new conditions that developed beyond 2 years after HCT (late). The cumulative incidence of CLE was 25% in those alive at 2 years, increasing to 41% at 15 years after HCT. CLE were most prevalent in the neurologic (9%), neurodevelopmental (8%) and dental (8%) categories. Chemotherapy-based conditioning was associated with decreased height z-score at 2-5 years post-HCT (p