Long-term outcome and lineage-specific chimerism in 194 Wiskott-Aldrich Syndrome patients treated by hematopoietic cell transplantation between 1980-2009: an international collaborative study.

In this retrospective collaborative study, we have analyzed long-term outcome and donor cell engraftment in 194 patients with the Wiskott-Aldrich syndrome who have been treated by hematopoietic cell transplantation (HCT) in the period 1980-2009. Overall survival was 84.0%, and was even higher (89.1% 5-year survival) for those who received HCT since the year 2000, reflecting recent improvement of outcome following transplants from mismatched family donors and for patients who received HCT from an unrelated donor at more than 5 years of age. Patients who went to transplant in better clinical conditions had a lower rate of post-HCT complications. Retrospective analysis of lineage-specific donor cell engraftment showed that stable full donor chimerism was attained by 72.3% of the patients who survived for at least one year after HCT. Mixed chimerism was associated with an increased risk of incomplete reconstitution of lymphocyte count and post-HCT autoimmunity, and myeloid donor cell chimerism <50% was associated with persistent thrombocytopenia. These observations indicate continuous improvement of outcome after HCT for WAS, and may have important implications for the development of novel protocols aiming to obtain full correction of the disease and reduce post-HCT complications.