Long-term survival of beta thalassemia major patients treated with hematopoietic stem cell transplantation compared with survival with conventional treatment

Allogeneic hematopoietic stem cell transplantation (HSCT) in thalassemia remains a challenge. We reported a single-centre case-control study of a large cohort of 516 children and adult patients treated with HSCT or blood transfusion support and iron chelation therapy; 258 patients (median age 12, range 1-45) underwent sibling (67%) or unrelated (33%) HSCT; 97 patients were adults (age ≥ 16 years). The median follow-up after HSCT was 11 years (range 1-30). The conditioning regimen was busulfan (80.6%) or treosulfan-based (19.4%). A cohort of 258 age-sex matched conventionally treated (CT) patients was randomly selected. In transplanted patients the 30-year overall survival (OS) and thalassemia-free survival (TFS) were 82.6±2.7% and 77.8±2.9%, compared to the OS of 85.3±2.7% in CT patients (p=NS); The incidence of grade II-IV acute and chronic graft versus host disease (GvHD) was 23.6% and 12.9% respectively. The probability of rejection was 6.9%. Transplant-related mortality (TRM) (13.8%) was similar to the probability of dying of cardiovascular events in CT patients (12.2%). High-risk Pesaro score (class 3) was associated with lower OS (OR=1.99, 95% C.I.=1.31-3.03) and TFS (OR=1.54, 95% C.I.=1.12-2.12). In adult patients, the 23-years OS and TFS after HSCT were 70±5% and 67.3±5%, compared to 71.2±5% of OS in CT (p=NS). Finally, treosulfan was associated with lower risk of acute GvHD (p=0.004; OR=0.28, 95% C.I.=0.12-0.67). In conclusion, the 30-year survival rate of ex-thalassemia patients after HSCT was similar to that expected in CT thalassemia patients, with the vast majority of HSCT survivors cured from thalassemia. This article is protected by copyright. All rights reserved.