BONE-MARROW TRANSPLANTATION THALASSEMIA

Early trials of allogeneic bone marrow transplantation (BMT) for homoz ygous beta-thalassemia and the analyses of results of transplantation in patients less than 16 years old have allowed us to identify three c lasses of risk based on the following criteria: (a) hepatomegaly, (b) presence of liver fibrosis at histological examination, and (c) qualit y of chelation treatment given before transplant. Patients with none o f these adverse criteria were assigned to Class 1; patients with eithe r one or two adverse criteria comprised Class 2; and patients for whom all three criteria were adverse constituted Class 3. Most patients ol der than 16 years have disease characteristics that place them in Clas s 3, with very few falling into Class 2. All patients with a histocomp atibility leukocyte antigen (HLA)-identical donor are actually assigne d to one of two conditioning regimens on the basis of the class they b elong to at the time of BMT and independently of age. For Class 1, Cla ss 2, and Class 3 patients, the probabilities of survival and event-fr ee survival are 95 and 90%, 86 and 82%, and 87 and 63%, respectively. For those patients older than 16 years at the time of transplant, the probabilities of survival and of event-free survival are 78 and 74%, r espectively. Allogeneic BMT is currently the only rational therapeutic modality for the eradication of beta-thalassemia.