Melphalan and total body irradiation (TBI) versus cyclophosphamide and TBI as conditioning for allogeneic matched sibling bone marrow transplants for acute myeloblastic leukaemia in first remission

Abstract

Between June 1981 and April 1986 63 patients with acute myeloid leukaemia (AML) in first remission and HLA-identical sibling donors were entered into a prospective study comparing cyclophosphamide (CY) + total body irradiation (TBI) with melphalan + TBI as conditioning therapy prior to transplantation. Thirty-six patients received CY/TBI and 27 received melphalan/TBI. The actuarial probability of remaining in remission for patients receiving melphalan/TBI was 94% compared with 66% following CY/TBI (p greater than 0.01). By including a comparable group of 41 patients with AML in first remission, conditioned with CY/TBI prior to the onset of the study, the greater anti-leukaemic effect of melphalan/TBI compared to CY/TBI was unchanged and statistically the chance of this being wrong is 1 in 10 (p less than 0.1). The overall survival in remission of both arms of the study was the same with 15/27 patients (55%) surviving in remission following melphalan/TBI compared with 19/36 patients (53%) following CY/TBI. The benefit obtained in reduced relapse was offset by the combined nephrotoxic effect of melphalan and cyclosporin which was not identified until the programme had been underway for a period of time. This shows that misinterpretation of 'no survival advantage' for the new treatment may occur due to unforeseen and preventable toxicities.