Allogeneic hematopoietic stem cell transplantation in thalassemia major: results of a reduced-toxicity conditioning regimen based on the use of treosulfan.

Sixty thalassemia patients (median age, 7 years; range, 1-37) underwent allogeneic hematopoietic stem cell transplantation (HSCT) after a preparation combining thiotepa, treosulfan, and fludarabine. Before HSCT, 27 children were assigned to risk class 1 of the Pesaro classification, 17 to class 2, and 4 to class 3; 12 patients were adults. Twenty patients were transplanted from an HLA-identical sibling and 40 from an unrelated donor. The cumulative incidence of graft failure and transplantation-related mortality was 9\% and 7\%, respectively. Eight patients experienced grade II-IV acute GVHD, the cumulative incidence being 14\%. Among 56 patients at risk, 1 developed limited chronic GVHD. With a median follow-up of 36 months (range, 4-72), the 5-year probability of survival and thalassemia-free survival are 93\% and 84\%, respectively. Neither the class of risk nor the donor used influenced outcome. This treosulfan-based preparation proved to be safe and effective for thalassemia patients given allogeneic HSCT.