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Two umbilical cord blood transplants lowered relapse risk in acute leukemias
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Transplantation of two units of partially HLA-matched umbilical cord blood was associated with a reduced risk for relapse in patients with acute lymphoblastic leukemia and acute myeloid leukemia.
All prior studies examining leukemia relapse have shown similar recurrence rates regardless of stem cell source (UCB vs. bone marrow vs. peripheral blood). Double UCB transplantation is relatively new treatment approach.
Researchers at the University of Minnesota in Minneapolis studied 177 patients treated at a single institution between 1994 and 2008. Eighty-eight patients had ALL and 89 had AML. Median age was 16.
Forty-seven percent of patients received one unit of umbilical cord blood. The remaining patients were assigned two units. The choice to receive one vs. two units was based on the number of UCB cells/kg available to the patients. Thus, those who received two units were significantly older and weighed more.
Median follow-up was 5.7 years for those assigned one unit and 2.7 for patients assigned two. Median overall time to relapse was 209 days for the whole group. The overall incidence of relapse was 26% (95% CI, 19%-33%). Rates of relapse were similar for patients with ALL (25%) and AML (27%).
Univariate analysis showed lower risk for relapse among patients in the two-unit group (19%; 95% CI, 11%-27%) compared with the one-unit group (34%; 95% CI, 23%-45%). Patients in second complete remission who received only one unit relapsed at more than twice the rate of those who received two units (40% vs. 18%), according to the researchers.
Multivariate analysis showed that the transplantation of two units was independently associated with a lower risk for relapse (RR=0.5; 95% CI, 0.2-1.0) for patients in first or second remission, even after adjusting for diagnosis, disease status and other potential risk factors.
If two cord blood units results in a reduced risk of relapse, that would fundamentally alter the approach that is being taken for pediatric transplantation in children who are receiving cord blood transplants. At the present time, approximately one-third of children who are getting a transplant are receiving cord blood units and almost all of those are getting a single unit. If this study’s findings can be confirmed, then transplantation with two cord blood units will likely become the new standard of care.
– John Levine, MD
Clinical Director, Pediatric Blood and Marrow Transplantation Program, University of Michigan
Verneris MR. Blood. 2009;doi:10.1182/blood-2009-05-220525.