One or two umbilical cord blood cell units? Caveat emptor

Cord blood transplantation for acute leukemia

INTRODUCTION

Umbilical cord blood transplantation (UCBT) is a suitable alternative for patients with acute leukemia (AL) in need of an allograft and who lack an HLA-matched donor. Single-institution and registry studies have shown that, in both children and adults with AL, the outcome of UCBT is comparable to that of matched unrelated donor. At the same time, these studies have highlighted some limitations of UCBT, such as increased early mortality and delayed recovery of both hematopoietic and immune compartment, which hamper a more widespread adoption of this approach.

AREAS COVERED

In this review, we will analyze the current results of UCBT in children and adults with AL, including comparisons with other hematopoietic stem cell sources and transplant strategies. We will also discuss important factors to be considered when selecting UCB units, as well as future strategies to further improve the outcome of UCBT recipients.

EXPERT OPINION

The utilization of UCBT for the treatment of AL patients has decreased in recent years. However, recent clinical data suggesting that UCBT might offer better results in patients with minimal residual disease, as well as innovative strategies to facilitate engraftment, reduce transplant-related mortality, and optimize anti-leukemic activity, may pave the way toward a second youth for use of UCB cells.

Prospective Randomized Study Comparing Myeloablative Unrelated Umbilical Cord Blood Transplantation versus HLA-Haploidentical Related Stem Cell Transplantation for Adults with Hematologic Malignancies

In this prospective randomized study, we compared the outcomes of single-unit umbilical cord blood transplantation (UCBT) and unmanipulated haploidentical stem cell transplantation (haplo-SCT) with post-transplantation cyclophosphamide (PTCy) in adults with hematologic malignancies. All patients received a myeloablative conditioning (MAC) regimen consisting of thiotepa, busulfan, and fludarabine, with antithymocyte globulin (ATG) added for UCBT recipients. Nineteen patients were randomized to UCBT and the other 26 to haplo-HSCT. Four patients (15%) allocated to the haplo-HSCT arm lacked a suitable donor and were crossed over to the UCBT arm. Finally, 23 underwent UCBT and 22 underwent haplo-HSCT. The cumulative incidence of neutrophil recovery was 87% at a median of 19 days (range, 13 to 24 days) in the UCBT arm versus 100% at a median of 17 days (range, 13 to 25 days) in the haplo-SCT arm (P = .04). Platelet recovery was 70% at a median of 40 days (range, 18 to 129 days) in the UCBT arm versus 86% at a median of 24 days (range, 12 to 127 days) in the haplo-HCT arm (P = .02). Rates of acute graft-versus-host disease (GVHD) grade II-IV or grade III-IV, overall chronic GVHD, and extensive chronic GVHD in the UCBT and Haplo-SCT arms were 43% versus 36% (P = .8), 9% versus 9% (P = 1), 66% versus 43% (P = .04), and 41% versus 23% (P = .2), respectively. Two-year nonrelapse mortality and relapse in the 2 arms were 52% versus 23% (P = .06) and 17% versus 23% (P = .5), respectively. Two-year disease-free survival, overall survival, and GVHD/relapse-free survival in the 2 arms were 30% versus 54% (P = .2), 35% versus 59% (P = .1), and 17% versus 40% (P = .04), respectively. Our data show that in the context of an MAC regimen, haplo-SCT with PTCy provides improved outcomes compared with ATG-containing single-unit UCBT.

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.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0497-9) contains supplementary material, which is available to authorized users.