Long-term follow-up of allogeneic hematopoietic stem-cell transplantation with reduced-intensity conditioning for patients with chronic myeloid leukemia

Allogeneic hematopoietic stem-cell transplantation (HSCT) remains an effective strategy for inducing durable remission in chronic myeloid leukemia (CML). Reduced-intensity conditioning (RIC) regimens extend HSCT to older patients and those with comorbidities who would otherwise not be suitable candidates for HSCT. The long-term efficacy of this approach is not established. We evaluated outcomes of 64 CML patients with advanced-phase disease (80% beyond first chronic phase), not eligible for myeloablative preparative regimens due to older age or comorbid conditions, who were treated with fludarabine-based RIC regimens. Donor type was matched related (n = 30), 1 antigen-mismatched related (n = 4), or matched unrelated (n = 30). With median follow-up of 7 years, overall survival (OS) and progression free survival (PFS) were 33% and 20%, respectively, at 5 years. Incidence of treatment-related mortality (TRM) was 33%, 39%, and 48% at 100 days, and 2 and 5 years after HSCT, respectively. In multivariate analysis, only disease stage at time of HSCT was significantly predictive for both OS and PFS. RIC HSCT provides adequate disease control in chronic-phase CML patients, but alternative treatment strategies need to be explored in patients with advanced disease. TRM rates are acceptable in this high-risk population but increase over time.