Cord blood donation

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Single and double cord blood transplants produce similar outcomes, according to a study of young patients with hematologic disorders.

Researchers found that rates of overall and disease-free survival were not significantly different in patients who received a single unit of cord blood and those who received two units.

Other outcome measures, such as neutrophil recovery, relapse, and transplant-related death, were similar between the two groups as well.

However, patients who received a single cord blood unit showed improved platelet recovery, a lower incidence of grade 3-4 acute graft-vs-host disease (GVHD), and a lower rate of extensive chronic GVHD.

John Wagner, Jr, MD, of the University of Minnesota in Minneapolis, and his colleagues reported these results in NEJM. Dr Wagner previously presented results from this study at ASH 2012.

“Based on promising early studies using two cord blood units in adults for whom one unit is often not sufficient, we designed this study in order to determine if the higher number of blood-forming stem cells in two cord blood units might improve survival,” Dr Wagner said. “What we found, however, was that both treatment arms performed very well, with similar rates of white blood cell recovery and survival.”

The researchers enrolled 224 patients, ages 1 to 21 years, with hematologic disorders, including acute and chronic leukemias as well as myelodysplastic syndromes.

Patients were randomized to receive double-unit (n=111) or single-unit (n=113) cord blood transplants after a uniform myeloablative conditioning regimen and immunoprophylaxis for GVHD.

The researchers matched the treatment arms for age, sex, self-reported race, performance status, degree of donor-recipient HLA matching, disease type, and disease status at transplant.

Survival and relapse

The study’s primary endpoint was 1-year survival, which was 65% in the double-unit arm and 73% in the single-unit arm (P=0.17). In a multivariate analysis, the risk of death did not differ significantly between the arms (hazard ratio=1.34, P=0.20).

Similarly, there was no significant difference in 1-year disease-free survival between the double- and single-unit arms—64% and 70%, respectively (P=0.11). In a multivariate analysis, the risk of relapse or death did not differ significantly between arms (hazard ratio=1.48, P=0.08).

It therefore follows that rates of relapse and transplant-related death were similar at 1 year as well. The incidence of relapse was 14% in the double-unit arm and 12% in the single-unit arm (P=0.12). And rates of transplant-related death were 22% and 19%, respectively (P=0.43).

Recovery and GVHD

The incidence of neutrophil recovery was similar between treatment arms—88% in the double-unit arm and 89% in the single-unit arm (P=0.29) at a median of 23 days (range, 11 to 133) and 21 days (range, 11 to 62) after transplant, respectively.

However, the rate of platelet recovery was significantly higher in the single-unit arm—76% vs 65% (P=0.04). Furthermore, the median time to platelet recovery was 58 days (range, 28 to 295) in the single-unit arm and 84 days (range, 22 to 716) in the double-unit arm.

The rate of grade 2-4 acute GVHD was similar between the treatment arms (P=0.78), but patients in the double-unit arm had a higher incidence of grade 3-4 acute GVHD—23% vs 13% (P=0.02).

There was no difference in the incidence of any chronic GVHD at 1 year after transplant—32% in the double-unit arm and 30% in the single-unit arm (P=0.51). But there was a higher incidence of extensive chronic GVHD after double-unit transplant—15% vs 9% (P=0.05).

“This is helpful news for physicians considering the best treatment options for their patients,” said Joanne Kurtzberg, MD, of Duke University Medical Center in Durham, North Carolina.

“We found children who have a cord blood unit with an adequate number of cells do not benefit from receiving two units. This reduces the cost of a cord blood transplant for the majority of pediatric patients needing the procedure. However, for larger children without an adequately dosed single cord blood unit, using two units will provide access to a potentially life-saving transplant.”

Number of cord blood units doesn’t affect survival