One of the most significant limitations of cord blood transplantation, a procedure in which stem cells are collected from the umbilical cord and placenta after a baby is born, is that each cord blood unit contains limited volumes of blood, which translates into limited stem cells available for transplantation. The number of stem cells needed for a successful cord blood transplant is largely dependent on the size and weight of the patient. Often times haematopoietic stem cells from one cord blood donor are not sufficient to transplant one adult patient. In order to increase the number of cells, adult patients may need to receive two units of cord blood from two different donors.

Previous research from the University of Minnesota has shown that patients with acute leukaemia who receive a double infusion of stem cells through an unrelated cord blood transplant have a lower incidence of relapse and a similar rate of leukaemia-free survival, but a higher incidence of acute graft-versus-host disease than patients who receive a single cord blood stem cell transplant.

In order to confirm these findings, an analysis of outcomes from a larger population of patient outcomes was conducted to evaluate the benefits of a double unrelated versus a single unrelated cord blood transplant. Researchers from Eurocord, an international registry that collects and validates data from cord blood transplants, and the Acute Leukaemia Working Party (ALWP), one of the specialized working groups of the European Group for Blood and Marrow Transplantation (EBMT), collaborated to retrospectively analyze data.

This study compared outcomes from 230 double unrelated cord blood stem cell transplants with 377 single unrelated cord blood stem cell transplants in adults with acute myeloid or lymphoblastic leukaemia in remission. The study examined separately outcomes in patients who received a cord blood transplant while in first remission compared with those in second or third remission.

At three years, in patients still in first remission, the unadjusted cumulative relapse incidence was significantly less in patients who received a double as compared to a single transplant (15 percent and 25 percent, respectively). The rates of leukaemia-free survival were also higher in those receiving a double versus a single transplant (53 percent and 39 percent, respectively). Additionally, the incidence of non-relapse mortality was 32 percent in those receiving a double cord blood transplant compared with 36 percent in those who received a single cord blood transplant. There was a significant difference in acute graft-versus-host disease incidence between the two treatment groups, with 45 percent experiencing the complication after a double transplant compared with 27 percent following a single transplant. For those patients in a second or third complete remission, outcomes following the double transplant were not statistically different from those receiving a single transplant.

“Results from this analysis demonstrate that not only is a double cord blood transplant feasible, but the procedure is associated with better overall outcomes, especially when it is used early in the treatment of acute leukaemias,” said Vanderson Rocha, MD, PhD, Scientific Director of Eurocord Registry, Hopital Saint Louis, Paris. “Prospective clinical trials are currently underway in Europe and the United States in order to confirm the results seen in this study.”



Source: ASH