Mismatched cord blood may serve as option in transplants

Mismatched cord blood may be a viable option for children waiting for a bone marrow transplant, study presenters shared at the American Society for Blood and Marrow Transplantation meeting in Tampa in mid-February.

Transplants using cord blood connected on four of six HLA types among children with malignant and genetic disorders translated to low rates of graft failure and acute and chronic graft-versus-host disease, reported Vinod Prasad, MD, study author. Survival rates were 54.8%, 46.6%, and 43% at 1-, 3- and 10-years respectively.

"For those patients in whom a matched bone marrow donor is not available, unrelated cord blood clearly, even if mismatched, is a very good option," Prasad said in a statement.

Prasad and colleagues assessed potential matches by evaluating effectiveness of 4/6 matched cord blood units in 314 children (63% male; 73% white) who had myeloablative transplantation at Duke University from August 1993 to November 2007. A significant 61% of patients had malignant diagnoses (leukemia, lymphoma, or myelodysplastic syndromes). Others had metabolic or immunodeficiency syndromes, hemoglobinopathies, or marrow failure.

Neutrophil engraftment was experienced in 77.7% of the children by 42 days after the transplant; at 180 days, 52.1% experienced platelet engraftment. Following a 6.9-year median follow-up, primary graft failure was identified in 6.7% of patients. Although Prasad says that number is "slightly higher" than expected in typical bone marrow transplantation, it is still considered low overall.

Survival rates at up to 10 years compared with survival rates of unmatched bone marrow transplants.

"Without these transplants, they all would have died, and for those patients who didn't find an unrelated donor, there was no option for transplant so they obviously would have died," Prasad said.

Mismatched cord blood can open up transplant access to all children, especially for ethnic and racial minority patients, according to Prasad.