Bone marrow transplantation in thalassemia. The experience of Pesaro.

Early trials of allogenic bone marrow transplantation (BMT) for homozygous beta thalassemia and the analyses of results of transplantation in patients under 17 years of age have allowed us to identify 3 classes of risk using the criteria of degree of hepatomegaly, the degree of portal fibrosis, and the quality of the chelation treatment given before the transplant. Patients for whom all 3 criteria were adverse constituted Class 3, patients with none of the adverse criteria constituted Class 1, and patients with 1 or various associations of 2 of the adverse criteria formed Class 2. Most patients older than 16 years have disease characteristics that place them in Class 3, with very few in Class 2. For all the patients with an HLA identical donor we are actually using 2 protocols to which the patient is assigned on the basis of the Class he belongs to at the time of BMT and independently from the age of the patient. For 104 patients in Class 1 and for 262 patients in Class 2 prepared for the transplant with busulfan 14 mg/kg, cyclophosphamide 200 mg/kg and cyclosporine alone, the probabilities of survival and of event-free survival are 95% and 90% for Class 1 and 87% and 84% for Class 2. For 33 Class 3 patients prepared for the transplant with busulfan 14 mg/kg, cyclophosphamide reduced to 160 mg/kg, cyclosporine, and "short" methotrexate, the probabilities of survival and event-free survival are 89% and 64%. For 57 adult patients (17 to 35 years), who underwent the transplant after preparation with the same protocol used for Class 3, the probabilities of survival and of event-free survival are 70% and 68%, respectively. BMT remains the only form of radical treatment for thalassemia in those patients with an HLA-identical donor.