Unrelated Umbilical Cord Blood Transplantation: Characteristics and Outcomes In Older Patients With Hematological Malignancies In Europe and United States: A Eurocord/European Group For Blood and Marrow Transplantation (EBMT) and Center For International Blood and Marrow Transplant Research (CIBMTR) Study

Transplantation with umbilical cord blood rather than adult donor cells is a valid alternative for adults with malignant and non-malignant hematological diseases. The use of unrelated umbilical cord blood transplantation (UCBT) in adults has increased recently for 2 reasons: use of 2 cord blood units to obtain an adequate number of cells; and, use of reduced-intensity conditioning regimens (RIC) for older persons who are unable to tolerate myeloablative conditioning regimens. Recent data from Eurocord and CIBMTR indicate that 35% of adults UCBT recipients are older than 50 years. This study describes the increasing use of UCBT and the patient characteristics and transplant strategies used in older (>50 years) patients receiving UCBT in Europe and United States, as well as UCBT outcomes in this population.

Retrospective registry based cross-sectional study on patients transplanted in Europe and North America; Patients: 1529 patients 50 years or older who received UCBT for hematologic malignancies or non-malignant hematologic disorders from 2005 through 2011, and whose transplants were reported to EUROCORD/EBMT or CIBMTR. 848 patients were transplanted in North America; 681 were transplanted in Europe. Acute myeloid leukemia (AML) (50%) was the most frequent indication in both registries, followed by myelodysplastic syndrome (MDS) and non-Hodgkin Lymphoma (NHL). Myeloma (MM) was the indication for UCBT for 15% of patients in Europe, but accounted for only a single case in the US (Refer to table 1 for complete UCBT distribution according to diagnosis). Most AML patients (80%) in both registries were transplanted in CR1 or CR2. RIC regimens were used more frequently for patients in Europe: 76% of patients reported to Eurocord versus 49% reported to CIBMTR for patients in the age range 50-59y and 93% in Eurocord and 69% in CIBMTR for patients 60y or older. Graft-versus-host disease prophylaxis in Europe was predominantly with cyclosporine and prednisone; tacrolimus and mycophenolate was more often used in the US. Double UCBT accounted for 61% of cases reported to Eurocord and for 71% of cases reported to CIBMTR.

Probability of 2-y overall survival (OS) was similar in both cohorts. In Eurocord, 2-y OS rates were 33% for AML in CR1, 48% in CR2, 10% with advanced disease for patients aged 50-59y; corresponding rates in older patients were 58%, 29% and 15%, respectively. In CIBMTR, 2-y OS rates were 41% for AML in CR1, 30% in CR2 and 15% with advanced disease for patients aged 50-59y; corresponding rates for older patients were 22%, 29%, and 16%, respectively. For other malignancies, in Eurocord, for patients aged 50-59y, 2-y OS rates were 57% in MM, 52% in ALL (acute lymphocytic leukemia), 49% in NHL, 47% in CLL (chronic lymphocytic leukemia) and 25% in MDS. In CIBMTR, corresponding OS rates were 54% in ALL, 48% in MDS, 41% in NHL and 40% in CLL

The number of UCBT for the elderly has been increasing over the years, and survival rates are comparable for this population in Europe and North America, with similar trends in both registries. The encouraging results of this survey show that UCBT is a good alternative source of stem cells for elderly patients with hematologic diseases. Comparative studies between umbilical cord blood and other stem cell sources are needed to define the best graft indication for patients aged 50 years and older lacking an HLA identical adult donor.

No relevant conflicts of interest to declare.