Treatment of chronic myeloid leukemia with allogeneic bone marrow transplantation after preparation with BuCy2

One hundred fifteen patients with chronic myelocytic leukemia (CML) were administered busulphan 4 mg/kg for 4 days and cyclophosphamide 60 mg/kg on each of 2 days (BuCy2) followed by allogeneic bone marrow transplantation from histocompatible sibling donors. For 62 patients in chronic phase, 26 in accelerated phase, and 27 in blast transformation, the actuarial survival at 3 years was 58%, 41%, and 25%, respectively. Actuarial probability of relapse was 3%, 12%, and 27%, respectively. Only two patients in chronic phase showed a transient cytogenetic relapse and one of these died from subsequent transplant-related complications, whereas the other remains cytogenetically normal 697 days posttransplant. Patients who were transplanted within 1 year of diagnosis in chronic phase had a survival of 70% compared with 40% when transplanted beyond 1 year from diagnosis. This significant difference in survival was due to transplant-related complications and was correlated with previous exposure to high doses of busulphan. This study indicates that BuCy2 is a useful conditioning regimen for marrow transplantation in patients with CML and results in similar survival statistics and transplant-related mortality as would be expected with conditioning regimens containing total body irradiation. It is possible that relapse after BuCy2 may be lower than expected with regimens containing total body irradiation, but larger analyses are required.