Single- or double-unit UCBT following RIC in adults with AL: a report from Eurocord, the ALWP and the CTIWP of the EBMT

BACKGROUND The feasibility of cord blood transplantation (CBT) in adults is limited by the relatively low number of hematopoietic stem/progenitor cells contained in one single CB unit. The infusion of two CB units from different partially HLA-matched donors (double CBT) is frequently performed in patients who lack a sufficiently rich single CB unit. METHODS We compared CBT outcomes in patients given single or double CBT following reduced-intensity conditioning (RIC) in a retrospective multicenter registry-based study. Inclusion criteria included adult (≥18 years) patients, acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL), complete remission (CR) at the time of transplantation, first single (with a cryopreserved TNC ≥ 2.5 × 107/kg) or double CBT between 2004 and 2014, and RIC conditioning. RESULTS Data from 534 patients with AML (n = 408) or ALL (n = 126) receiving a first single (n = 172) or double (n = 362) CBT were included in the analyses. In univariate analysis, in comparison to patients transplanted with a single CB, double CB recipients had a similar incidence of neutrophil engraftment but a suggestion for a higher incidence of grade II-IV acute GVHD (36 versus 28%, P = 0.08). In multivariate analyses, in comparison to single CBT recipients, double CBT patients had a comparable incidence of relapse (HR = 0.9, P = 0.5) and of nonrelapse mortality (HR = 0.8, P = 0.3), as well as comparable overall (HR = 0.8, P = 0.17), leukemia-free (HR = 0.8, P = 0.2) and GVHD-free, relapse-free (HR = 1.0, P = 0.3) survival. CONCLUSIONS These data failed to demonstrate better transplantation outcomes in adult patients receiving double CBT in comparison to those receiving single CBT with adequate TNC after RIC.