A new standard of care for children facing acute myeloid leukemia (AML) may be clear, following a multiyear study published in the New England Journal of Medicine (2014; 371:1685-1694).

The research, led by John Wagner Jr, MD, director of the Pediatric Blood and Marrow Transplantation program at the University of Minnesota and a researcher in the Masonic Cancer Center, University of Minnesota in Minneapolis-St. Paul, compared outcomes in children with acute leukemia and myelodysplastic syndrome who received transplants of either one or two units of partially matched cord blood.

The 1-year overall survival rate was 65% for recipients of double cord-blood units and 73% for recipients of single cord-blood units.

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While the study found similar survival rates in both arms of the study, survival was overall better than in prior reports. This could create a new standard of care for pediatric patients for whom there is often an adequate single unit and adults for whom there is the need for a double unit should a single unit with an adequate number of blood forming stem cells not exist.

Umbilical cord blood, a rich source of blood-forming stem cells, has previously been shown to benefit many patients with leukemia and myelodysplasia and other diseases, including bone marrow failure syndromes, hemoglobinopathies, inherited immune deficiencies, and certain metabolic diseases. Cord blood offers several advantages for leukemia patients, as there is no need for strict human leukocyte antigen (HLA) matching or prolonged search for a donor.

“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,” explained Wagner. “What we found, however, was that both treatment arms performed very well with similar rates of white blood cell recovery and survival.”

Children with blood cancer have previously been shown to benefit from umbilical cord blood (UCB), despite HLA mismatch, making it an important alternative for patients who cannot find a matched unrelated donor.

Despite the similarities in survival rates, some differences were noted. Children transplanted with a single cord unit had faster recovery rates for platelets, the cell components important in clotting, and lower risks of GVHD, a condition where the transplanted donor blood immune cells recognize the patient’s body as foreign causing a number of complications.

“This is helpful news for physicians considering the best treatment options for their patients,” said coauthor Joanne Kurtzberg, MD, at 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.”

One provocative outcome of the study was the finding that significantly HLA mismatched cord blood had no detrimental effect on outcome. Future studies will take a closer look at how the HLA match within the cord blood unit impacts outcomes for patients, particularly those within minority populations.