Allogeneic marrow transplantation for thalassemia.

Thirteen patients with homozygous beta thalassemia underwent allogeneic marrow transplantation from sibling donors, 12 of whom were heterozygous for beta thalassemia. Six patients were transplanted in an advanced stage of their disease while seven were transplanted early in their disease course. Donors and recipients were genotypically identical for the HLA-A, -B and -D loci in 11 cases and mismatched for the D locus in two. A variety of preparative regimens was utilized involving high doses of busulphan (Bu) and/or cyclophosphamide (CY) and/or total body irradiation (TBI). Failure of engraftment or autologous hematologic recovery after transient engraftment was seen after intensive preparative regimens including: CY 200 mg/kg and 800 rad of TBI; Bu 8 mg/kg and CY 200 mg/kg; and Bu 8 mg/kg, CY 200 mg/kg, and 300 rad of TBI. A regimen of Bu 16 mg/kg, CY 200 mg/kg, and 400 rad of TBI resulted in deaths from transplant-related causes in the three patients treated with this regimen. Seven of the 13 patients are surviving 363-665 days after transplant. Five of the seven failed to achieve engraftment or had autologous reconstitution after transient engraftment. Five of the six deaths were transplant related, and one patient died of cardiac failure one year after an unsuccessful transplant attempt. Two patients are surviving with engraftment and without thalassemia major 363 and 491 days after transplantation. Both of these patients were transplanted early in their disease course.