The Embt Risk Score Predicts the Outcome of Patients with Leukaemia Receiving Single Umbilical Cord Blood Transplantation

Aim The European Group for Blood and Marrow Transplantation (EBMT) risk score has been implemented as an important tool to predict patient outcomes following allogeneic haematopoietic stem cell transplantation (allo-HSCT). However, to our knowledge, this score has never been applied in cases of single umbilical cord blood transplantation (sUCBT). The aim of this study was to assess the capacity of the EBMT risk score in predicting the outcomes of patients with leukaemia receiving sUCBT. Methods We retrospectively analysed 218 consecutive patients with leukaemia who received sUCBT at our centre between February 2011 and December 2015. Sixty-eight of the 218 patients had AML, 137 had ALL, 10 had CML, 2 had mixed phenotype AL, and only one patient had plasma cell leukaemia. The median age was 12 years (range, 1-46 years), and the median weight was 40 kg (range, 10-100 kg). All of the patients received an intensified myeloablative conditioning regimen with cyclosporine A (CsA) and mycophenolate mofetil (MMF) as graft-versus-host disease (GVHD) prophylaxis. All of the patients were followed until 31 March 2016, with a median follow-up of 10.7 months (range, 0.5-58.9 months). Results The overall survival (OS) and leukaemia-free survival (LFS) of the entire cohort were 66.8% and 55.4%, respectively, whereas the cumulative incidences of relapse rate and non-relapse mortality (NRM) were 22.4% and 18.0%, respectively. In the univariate analysis, a higher EBMT risk score was associated with worse OS, worse LFS, lower NRM and higher relapse rate, ranging from 80.2%, 74.5%,7.5% and 18.0%, respectively, for patients with a score of 1 to 21.8%, 17.0%, 27.3% and 55.7%, respectively, for patients with a score of 5/6. Hazard ratios of the four indexes all steadily increased for each additional score point. Importantly, the prognostic value of the EBMT risk score on OS, LFS, NRM and relapse was maintained in the multivariate analysis. Moreover, considering the importance of allele-level HLA matching, we developed a modified sUCBT-EBMT risk score using HLA matching situations instead of donor type and found that the modified score could also be used as a predictor for patient outcomes following sUCBT. Conclusions The EBMT risk score is a good predictor of outcomes of patients with leukaemia following sUCBT. The modified sUCBT-EBMT risk score can also be used as a pretransplant risk assessment, but this metric still requires further evaluation with a larger cohort.