Chemotherapy versus allogeneic transplantation for very-high-risk childhood acute lymphoblastic leukaemia in first complete remission: comparison by genetic randomisation in an international prospective study

Background The dismal prognosis of very-high-risk childhood acute lymphoblastic leukaemia could be improved by allogeneic haemopoietic cell transplantation. We compared this strategy with intensified chemotherapy protocols, with the aim to improve the outcome of children with very-high-risk acute lymphoblastic leukaemia in first complete remission. Methods A cooperative prospective study was set up in seven countries. Very-high-risk acute lymphoblastic leukaemia in first complete remission was defined by the presence of at least one of the following criteria: (1) failure to achieve complete remission after the first four-drug induction phase; (2) t(9;22) or t(4;11) clonal abnormalities; and (3) poor response to prednisone associated with T immunophenotype, white-blood-cell count of 100x10(9)/L or greater, or both. Children were allocated treatment by genetic chance, according to the availability of a compatible related donor, and assigned chemotherapy or haemopoietic-cell transplantation. The primary outcome was disease-free survival and analysis was by intention to treat. Findings Between April, 1995, and December, 2000, 357 children entered the study, of whom 280 were assigned chemotherapy and 77 related-donor haemopoietic-cell transplantation. 5-year disease-free survival was 40.6% (SE 3.1) in children allocated chemotherapy and 56.7% (5.7) in those assigned transplantation (hazard ratio 0.67 [95% CI 0.46-0.99]; p=0.02); 5-year survival was 50.1% (3.1) and 56.4% (5.9), respectively (0.73 [0.49-1.09]; p=0.12). Interpretation Children with very-high-risk acute lymphoblastic leukaemia benefit from related-donor haemopoietic-cell transplantation compared with chemotherapy. The gap between the two strategies increases as the risk profile of the patient worsens.