Conditioning regimen with a 75% dose of standard busulfan/cyclophosphamide plus fludarabine before cord blood transplantation in older patients with AML and MDS

In this retrospective study, we aimed to establish a conditioning regimen for older patients receiving cord blood transplantation (CBT). This study included 21 older patients [median age 65 (58–73) years] with acute myeloid leukemia and myelodysplastic syndrome who underwent single CBT following a conditioning regimen comprising fludarabine (FLU) 125–175 mg/m², busulfan (BU) 9.6 mg/kg, and cyclophosphamide (CY) 90 mg/kg. Twelve patients (57.1%) were considered high or very high risk according to the disease risk index. Nineteen achieved neutrophil engraftment at a median of 19 days (range 14–29 days) after CBT (cumulative incidence 90.5%). During a median observation period of 24.3 months, the overall survival (OS) rates at 100 days and 2 years were 76.2% and 47.6%, respectively, with cumulative 2-year relapse and non-relapse mortality (NRM) rates of 19.0% and 38.1%, respectively. Infectious disease was the leading cause of NRM (n = 5) and occurred within 100 day post-transplantation in two patients. This suggested that the administration of a reduced BU/CY plus FLU regimen to older patients receiving CBT enables an early recovery with high neutrophil engraftment, relapse suppression, and acceptable NRM rates.