Myeloablative Reduced-Toxicity i.v. Busulfan-Fludarabine and Allogeneic Hematopoietic Stem Cell Transplant for Patients with Acute Myeloid Leukemia or Myelodysplastic Syndrome in the Sixth through Eighth Decades of Life

The optimal pretransplant regimen for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) in patients ≥55 years of age remains to be determined. The myeloablative reduced-toxicity 4-day regimen i.v. busulfan (Bu) (130 mg/m ²) and i.v. fludarabine (Flu) (40 mg/m ²) is associated with low morbidity and mortality. We analyzed 79 patients ≥55 years of age (median, 58 years) with AML (n = 63) or MDS (n = 16) treated with i.v. Bu-Flu conditioning regimens between 2001 and 2009 (median follow-up, 24 months). The patients who received this regimen had a good performance status. The 2-year overall survival (OS) rates for patients in first complete remission (CR1), second CR (CR2), or refractory disease and for all patients at time of transplantation were 71%, 44%, 32%, and 46%, respectively; 2-year event-free survival (EFS) rates for patients in CR1, CR2, or refractory disease at time of transplantation and for all patients were 68%, 42%, 30%, and 44%, respectively. One-year transplant-related mortality (TRM) rates for patients who were in CR or who had active disease at the time of transplantation were 19% and 20%, respectively. Grade II-IV acute graft-versus-host (aGVHD) disease was diagnosed in 40% of the patients. Our results suggest that age alone should not be the primary reason for exclusion from receiving myeloablative reduced-toxicity conditioning with i.v. Bu-Flu preceding transplantation in patients with AML/MDS.