Cord-Blood Engraftment Using an Enhanced Dual-Conditioning Regimen for Malignant Hematologic Diseases

To explore a more effective conditioning regimen for umbilical cord blood transplantation (UCBT) to treat hematologic malignancies, we conducted a cohort study of a fludarabine/busulfan/cytarabine plus cyclophosphamide 200 mg/kg regimen. Forty-two consecutive patients with leukemia, myelodysplastic syndrome, or lymphoma received the regimen. The median number of infused total nucleated cells per kilogram was 5.5 × 10⁷ (1.81-20.6), the median number of infused CD34⁺ cells per kilogram was 1.58 × 10⁵ (0.58-6.6), and the median follow-up for surviving patients was 37 months (4.0-79.5 months). The cumulative incidence of neutrophil engraftment at 31 days was 100% [95% confidence interval (CI): 0.9159-1.0], and the median time to neutrophil engraftment was 19 days. The cumulative incidence of nonrelapse mortality was 12.76% (95% CI: 0.0455-0.2356) at 180 days and 3 years. The 3-year overall survival (OS) and disease-free survival (DFS) rates were 71.6% and 59.6%, respectively. Especially in patients who received transplants in the early and intermediate stages, the 3-year OS and DFS rates were 90.3% (95% CI: 0.805-1.0) and 76.2% (95% CI: 0.608-0.956), respectively. The regimen significantly improved engraftment and survival, indicating that the high graft failure of UCBT was caused by rejection.