Long-term outcomes in adults with leukemia treated with transplantation of two unrelated umbilical cord blood units

Background Wide application of umbilical cord blood transplantation （UCBT） in adult patients is limited by low cell-dose available in one umbilical cord blood （UCB） unit. The aim of this study was to investigate the safety and long-term outcomes of UCBT from unrelated donors in adult and adolescent patients with leukemia. Methods Thirteen patients with leukemia received double-unit UCBT with human leukocyte antigen （HLA） mismatched at 0-2 loci. We analyzed the engraftment, graft-versus-host disease （GVHD） and survival. Results Twelve evaluable patients （92.3%） had neutrophil and platelet engraftment at a median of 21 days （range, 16-38 days） and 34 days （range, 25-51 days）, respectively. At day 30, engraftment was derived from one donor in 8 patients （66.7%, 95% Cl 40.0%-93.4%）, and from both donors in 4 patients （33.3%, 95% CI 6.7%-60.0%） with 1 unit predominated. Unit with larger nucleated cell （NC） dose would predominate in engraftment （P=-0.039）, whereas CD34~ cell dose or HLA-match failed to demonstrate any relationship with unit predominance. Only one patient developed grade II acute graft-versus-host disease （aGVHD）. Chronic GVHD （cGVHD） was observed in 2 of 11 patients who survived more than 100 days, and both were limited. The median follow-up after transplantation for the 13 patients was 45 months （range 1.5-121.0 months） and 72 months （range 41.0-121.0 months） for the 8 alive and with full donor chimerism. The 5-year cumulative disease free survival （DFS） was （61.5±13.5）%. Of the 13 patients, 5 patients died in 1 year and 1-year transplantation related mortality （TRM） was 23.1% （95% Cl 0.2%-46.0%）. Conclusion Double-unit UCBT from unrelated donors with HLA-mismatched at 0-2 loci may overcome the cell-dose barrier and be feasible for adults and adolescents with leukemia.