Outcome of Hematopoietic Cell Transplantation for DNA-Double Strand Breakage Repair Disorders.

Abstract

BACKGROUND: Rare DNA breakage-repair disorders predispose to infection and lympho-reticular malignancies. Hematopoietic cell transplantation (HCT) is curative but co-administered chemo- or radio-therapy is damaging due to systemic radio-sensitivity. We collected HCT outcome data for Nijmegen Breakage syndrome (NBS), DNA ligase IV deficiency (LIG4), Cernunnos-XLF deficiency and ataxia-telangiectasia. METHODS: Data from 38 centres worldwide, including indication, donor, conditioning regimen, graft-versus-host disease (GvHD) and outcome were analyzed. Conditioning was classified as myeloablative (MAC) if it contained radiotherapy or alkylators and reduced intensity (RIC) if no alkylators and/or fludarabine ≤150 mg/m(2) and cyclophosphamide ≤ 40 mg/kg were used. RESULTS: 55 new, 14 updated and 18 previously published patients were analyzed. Median age at HCT was 48 (range 1.5 - 552) months. 29 were transplanted for infection, 21 malignancy, 13 bone marrow failure, 13 pre-emptively, 5 had multiple indications, and 6 had no information. 22 received MAC, 59 RIC, 4 were infused;- information unavailable for 2. 73/77 patients with LIG4, Cernunnos-XLF deficiency or NBS received conditioning. Survival was 53/77 (69%), worse for MAC than RIC (p=0.006). Most deaths occurred early post-transplant suggesting poor tolerance of conditioning. Survival in ataxia-telangiectasia patients was 25%. 41/83 patients experienced aGvHD (49%): less in RIC compared to MAC, 26/56 (46%) vs 12/21 (57%) (p=0.45). Median follow-up was 35 (range 2-168) months. No secondary malignancies were reported during 15 years follow-up. Growth and developmental delay remained post-HCT; immune-mediated complications resolved. CONCLUSION: RIC-HCT resolves DNA repair disorder-associated immunodeficiency. Long-term follow-up is required for secondary malignancy surveillance. Routine HCT for ataxia-telangiectasia is not recommended.