Similar Survival Rates in Children Transplanted with One vs. Two Umbilical Cord Blood Units

Children with high-risk blood cancers transplanted with one vs. two umbilical cord blood units had similar survival, according to a multi-center study of 224 cord blood transplants performed between 2006 and 2012 and reported to CIBMTR (Center for International Blood and Marrow Transplant Research). Patient age ranged from 1 to 21 years of age, and patients were randomly assigned to receive one (n=113) or two (n=111 patients) cord blood units (CBUs) after undergoing myeloablative conditioning. One-year overall survival was 65% and 73% among recipients of double and single CBUs, respectively (p=0.17). However, recipients of a single CBU experienced improved platelet recovery and lower incidences of grade III and IV acute and extensive chronic graft-versus-host-disease (GVHD). This prospective clinical trial was developed by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN 0501) and conducted in collaboration with the Children’s Oncology Group

Wagner JE, et al. N Engl J Med

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Expert Commentary

Dennis Confer, M.D., Chief Medical Officer, NMDP/Be The Match

The results of this prospective randomized clinical trial reported by Wagner JE, et al in the New England Journal of Medicine [1] provide important clinical guidance for those physicians considering HCT for their pediatric patients and for physicians performing hematopoietic cell transplantation (HCT) in pediatric patients.

The primary finding - that there were no differences in survival in patients transplanted with one vs. two umbilical cord blood units (CBUs) - means that the cost of a cord blood transplant is reduced for the majority of pediatric transplant patients, and without the risk of reducing the chance of a successful outcome.

In fact, another important result of this multi-center clinical trial is that both arms of the trial experienced good outcomes: One-year survival was 73% and 65% for single- and double-CBU transplants, respectively (p=0.17). In addition, both arms had comparable platelet recovery and no patients in either group had secondary graft failure.

Still, the trial showed some differences. Children in the single-CBU group had faster platelet recovery rates than those in the double-CBU group, and experienced a lower incidence of grade III-IV acute graft-versus-host-disease (GVHD): 13% vs. 23%, respectively (p=0.02). This can have an important impact on the clinical course after HCT and quality of life.

These results mean that pediatric transplant physicians can be confident that a single CBU with an adequate cell dose - and such CBUs can be found for 95-99% of pediatric patients [2] - can yield good outcomes. And if larger children require two CBUs to achieve an adequate dose of hematopoietic stem cells, then that confidence of achieving good results should remain.

1. Wagner JE, Eapen M, Carter S, et al. One-unit versus two-unit cord-blood transplantation for hematologic cancers. New Engl J Med. 2014; 371(18): 1685-1694.
2. Gragert L, Eapen M, Williams E, et al. HLA Match likelihoods for hematopoietic stem-cell grafts in the U.S. registry. New Engl J Med. 2014; 371(4): 339-348.