5. Comparison of adult allogeneic umbilical cord blood transplantation between myeloablative and non-myeloablative conditioning regimens

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Aim: To make clear the feasibility of non-myeloablative conditioning on adult allogeneic umbilical cord blood transplantation, we compared the result between patients receiving the myeloablative transplantation and the non-myeloablative transplantation (NST) in point of the engraftment, and the incidence of acute GVHD.

Patients and Methods: Patients who were underwent umbilical cord blood transplantation during May 1999 to Mar 2005 were analyzed retrospectively. The myeloablative group: 30 patients (median age, 33) with AML (n = 10), ALL (n = 10), NHL (n = 6), MDS (n = 3), and CML (n = 1). Conditioning consisted of total body irradiation (TBI)-based regimens or busulfan-based ones. GVHD prophylaxis was with cyclosporine (CyA) alone, CyA with short-term Methotrexate (s-MTX), or Tacrolimus with s-MTX. NST group: 22 patients (median age, 55) with AML (n = 6), ALL (n = 1), MDS (n = 3), CMMoL (n = 1), NHL (n = 7), HD (n = 3), and CLL (n = 1). Conditioning regimen consisted mostly of TBI combined with Fludarabine. GVHD prophylaxis was with CyA, CyA with MMF, or Tacrolimus. The median transplanted cell number, and HLA disparity were similar between two groups.

Results: The rate of engraftment failure including conditioning failure, and autologous recovery was 27% in the myeloablative group and 32% in NST group, respectively. Neutrophils were engrafted at day 23 (median) and at day 21 in the myeloablative and NST group, respectively. The cumulative incidence of grade III-IV acute GVHD was 26% in the myeloablative group and 40% in NST group, respectively.

Conclusion: There were no significant differences in the probability of engraftment and in the duration to the engraftment of neutrophils between two groups. The incidence of grade III-IV GVHD in NST group was higher than that in the myeloablative group. Further observations are needed to ascertain the feasibility of NST using allogeneic umbilical cord blood.