Background: Unrelated cord blood transplantation (UCBT) is associated with delayed hematopoietic recovery. Intrabone injection of cord blood cells (IB-UCBT) and double-UCBT (dUCBT) are designed to circumvent this problem.
Methods: In a retrospective registry-based analysis, we compared outcomes of 87 IB-UCBT with 149 dUCBT recipients, after myeloablative conditioning regimen adjusting for the differences between the two groups. Median-infused total nucleated cells were 2.5×10/kg for IB-UCBT and 3.9×10/kg for dUCBT (P<0.001).
Results: At day +30, cumulative incidence (CI) of neutrophil recovery was 76% and 62% (P=0.014) with a median time to engraftment of 23 and 28 days (P=0.001), after IB-UCBT and dUCBT, respectively. At day +180, CI of platelets recovery was 74% after IB-UCBT, and 64%, after dUCBT (P=0.003). In multivariate analysis, IB-UCBT was associated with neutrophil and platelets recovery and lower acute graft versus host disease (II-IV) (P<0.01). At 2 years, CI of nonrelapse mortality and relapse incidence were 30% and 25% after IB-UCBT and 34% and 29% after dUCBT, and disease-free survival was 45% and 37%, respectively. However, after landmark analysis at 4.7 months from transplantation, in multivariate analysis, relapse incidence was reduced (P=0.03), and there was a trend for better disease-free survival after IB-UCBT (P=0.09).
Conclusion: Both approaches expand the possibility of offering UCBT to patients with hematopoietic malignancies; IB-UCBT is associated with faster myeloid and platelet recovery and lower acute graft versus host disease and may reduce the total cost. However, studies on cost effectiveness are needed to compare both strategies.