Effect of Transfusion of the Third Party Umbilical Cord Blood on Haplo-Identical Hematopoietic Stem Cell Transplantation

Objective To retrospectively evaluate the effect of the third party umbilical cord blood on haplo-identical hematopoietic stem cell transplantation.

Methods From June 2012 to May 2015, 125 leukemia patients were enrolled, including 41 cases of ALL, 62 cases of AML, 12 cases of MDS, 7 cases of CML-BP, 2 cases of acute mixed leukemia and 1 case of Mother cell dendritic cell tumor. Inclusion criteria: 1) AL patients; 2) halpo-identical HSCT; 3) 3/6 matched cord blood was available. Patients were divided into two groups, ie. group A (HSCT, n=65) and group B (HSCT plus umbilical cord blood transfusion group, n=60). Myeloablative conditioning regimens consisted of BuCy, TBI/FLAG, TBI/Cy, and FLAG that followed by reduced-intensified BUCY. The median dose of mononuclear cells in group A and B were 8.58×10⁸/kg and 9.01×10⁸/kg, respectively. The median dose of CD34⁺ cells for transfusion in each group were 3.67×10⁶/kg and 2.94×10⁶/kg, respectively. The dose of grafted UCB MNCs and CD34⁺ cells for group B were 3.5×10⁷/kg and 2×10⁵/kg, respectively. All patients received cyclosporineA, MMF and methotrexate for GVHD prophylaxis. The endpoints of this study were hematological engraftment, incidence of acute and chronic GVHD, incidence of relapse, transplant-related mortality(TRM), non-relapse mortality(NRM), Overall survival(OS) and Disease-free survival(DFS) in each group.

Results The median follow-up time was 17(3-29) months in group A and 18(3-35) months in group B. Patients in group A reached a sustained ANC of more than 0.5*10⁹/L at a median of 11 days, whereas 14 days in group B. Platelet more than 20*10⁹/L occurred at a median of 19 days in group A, whereas 17 days in group B (P= .4). The rate of aGVHD was not significantly different in the two groups, 56.9% in group A and 48.3% in group B (P= .21). The accumulative incidence of II-IV grade aGVHD was 35.4% in group A and 30% in group B (P= .42). The incidence of chronic GVHD was 79.2% in group A and 71% in group B (P= .47). The incidence of extensive type was lower in group B, 69.2% Vs 35%, P=0.09. The incidence of CMV was lower in group B, 80% Vs 60% (P= .01). The accumulative incidence of EBV was lower in group B, 35.4% Vs 3.3% (P<0.01). At two years, the accumulative incidence of relapse was 24.4% in group A and 17.2% in group B, P=0.13. The two-year accumulative incidence of OS was 72.9% in group A and 84.8% in group B, P=0.07. The one-year accumulative incidence of DFS in each group were 65.7% and 79.4%, respectively, P=0.03. Conclusion Our clinical results have shown that HSCT with transfusion of the third party umbilical cord blood is a promising modality for induction of immunity reconstitution. Better survival results may benefit from lower incidence of GVHD and virus infection.