The value of allogenic bone marrow transplant in patients with acute myeloid leukaemia at differing risk of relapse: results of the UK MRC AML 10 Trial

Patients under 55 years in the United Kingdom Medical Research Council Acute Myeloid Leukaemia 10 trial who entered complete remission were tissue typed (n = 1063). Four hundred and nineteen had a matched sibling donor and 644 had no match. When compared on a donor versus no donor basis the relapse risk was reduced in the donor arm (36%vs 52%; P = 0.001) and the disease-free survival (DFS) improved (50%vs 42%; P = 0.01), but overall survival (OS) was not different (55%vs 50%; P = 0.1). Sixty-one per cent of patients with a donor underwent transplantation. When patients were subdivided into risk groups based on cytogenetics alone or with the addition of blast response to course 1, a reduction in relapse risk was seen in all risk groups and in three age cohorts (0-14, 15-34 and 35+ years). Significant benefit in DFS was only seen in the intermediate-risk cytogenetic group (50%vs 39%; P = 0.004). The OS benefit was only seen in intermediate-risk patients (55%vs 44%; P = 0.02). The reduction in relapse risk in good-risk patients was attributable to patients with t(15;17) and not to patients with t(8;21) or inv(16). Allogeneic transplantation given after intensive chemotherapy was able to reduce relapse in all risk and age groups. However, due to the competing effects of procedural mortality and an inferior response to chemotherapy if relapse does occur, there was a survival advantage only in patients of intermediate risk. This trial found no survival advantage in children, patients over 35 years or good-risk disease.