Results of syngeneic hematopoietic stem cell transplantation for acute leukemia: risk factors for outcomes of adults transplanted in first complete remission.

BACKGROUND The possibility of performing syngeneic hematopoietic stem cell transplantation is rare and there are concerns about the absence of a graft-versus-leukemia effect following such a strategy. We report the outcomes of a large series of adult patients who underwent syngeneic hematopoietic stem cell transplantation for acute myeloblastic leukemia or acute lymphoblastic leukemia. DESIGN AND METHODS The outcomes of all syngeneic transplants for acute myeloblastic or lymphoblastic leukemia reported to the European Group for Blood and Marrow Transplantation registry were analyzed; a study of prognostic factors was performed for those transplanted in first complete remission. RESULTS One hundred and sixty-two patients, 109 with acute myeloblastic leukemia and 53 with acute lymphoblastic leukemia, were identified; 116 were in first complete remission. Most of the patients did not receive prophylaxis against graft-versus-host disease. Nineteen patients developed acute graft-versus-host disease and only three patients developed chronic graft-versus-host disease. The median follow-up was 60 months. At 5 years the non-relapse mortality was 8 +/- 5%, the relapse incidence 49 +/- 8% and the leukemia-free survival 43 +/- 3%. The corresponding figures for patients in first complete remission were 7 +/- 2%, 40 +/- 4% and 53 +/- 5% at 5 years. Analysis of patients in first complete remission showed that the number of courses of chemotherapy required to induce first complete remission was the main risk factor: the leukemia-free survival at 5 years was 66 +/- 6% when first complete remission was reached after one induction course of chemotherapy and was only 20 +/- 9% when first complete remission was reached after at least two induction courses of chemotherapy (p = 0.0001); the relapse incidence was 30 +/- 6% and 54 +/- 10%, respectively (p = 0.007). CONCLUSIONS Outcomes were better for patients transplanted in first complete remission than in second complete remission or a more advanced phase of the disease. When a syngeneic donor is available for patients with high risk acute leukemia, allotransplantation should be performed as soon as the first complete remission has been achieved, ideally with one course of chemotherapy.