The effect of pretransplant interferon therapy on the outcome of unrelated donor hematopoietic stem cell transplantation for patients with chronic myelogenous leukemia in first chronic phase

Various therapeutic options are available for patients with chronic myelogenous leukemia. Allogeneic stem cell transplantation, though often curative, is associated with high nonrelapse mortality and long-term morbidity, particularly when cells from unrelated donors are used. Many physicians and patients opt for a trial of interferon-α (IFN)–based therapy first, reserving transplantation for patients with inadequate response or intolerance to IFN. Data were analyzed on 740 patients receiving unrelated donor transplants for chronic myelogenous leukemia in first chronic phase provided by the International Bone Marrow Transplant Registry and the National Marrow Donor Program to see whether IFN pretreatment compromised transplantation outcome. A total of 489 (66%) had received IFN prior to transplantation; 251 (34%) had not. Disease characteristics in the 2 groups were similar at diagnosis but at the time of transplantation, hematologic parameters and weight were lower in IFN patients and the interval between diagnosis and transplantation was longer. After adjustment for baseline covariates, no effect of IFN exposure was found on overall survival, leukemia-free survival, nonrelapse mortality, engraftment, relapse, or acute or chronic graft-versus-host disease. Evaluation of effects based on duration of therapy and time off IFN prior to transplantation was limited by missing data and confounding with IFN intolerance and disease responsiveness. In conclusion, no evidence was found for an independent adverse effect of IFN pretreatment on the outcome of subsequent unrelated donor transplantation.