OUTCOMES AMONG 562 RECIPIENTS OF PLACENTAL-BLOOD TRANSPLANTS FROM UNRELATED DONORS

Background A program for banking, characterizing, and distributing pla cental blood, also called umbilical-cord blood, for transplantation pr ovided grafts for 562 patients between August 24, 1992, and January 30 , 1998. We evaluated this experience. Methods Placental blood was stor ed under liquid nitrogen and selected for specific patients on the bas is of HLA type and leukocyte content. Patients were prepared for the t ransplantation of allogeneic hematopoietic cells in the placental bloo d and received prophylaxis against graft-versus-host disease (GVHD) ac cording to routine procedures at each center. Results Outcomes at 100 days after transplantation were known for all 562 patients, and outcom es at 1 year for 94 percent of eligible recipients. The cumulative rat es of engraftment among the recipients, according to actuarial analysi s, were 81 percent by day 42 for neutrophils (median time to engraftme nt, 28 days) and 85 percent by day 180 for platelets (median, day 90). The speed of myeloid engraftment was associated primarily with the le ukocyte content of the graft, whereas transplantation-related events w ere associated with the patient's underlying disease and age, the numb er of leukocytes in the graft, the degree of HLA disparity, and the tr ansplantation center. After engraftment, age, HLA disparity, and cente r were the primary predictors of outcome. Severe acute GVHD (grade III or IV) occurred in 23 percent of patients, and chronic GVHD occurred in 25 percent. The rate of relapse among recipients with leukemia was 9 percent within the first 100 days, 17 percent within 6 months, and 2 6 percent by 1 year. These rates were associated with the severity of GVHD, type of leukemia, and stage of the disease. Conclusions Placenta l blood is a useful source of allogeneic hematopoietic stem cells for bone marrow reconstitution. (N Engl J Med 1998;339:1565-77) (C)1998, M assachusetts Medical Society.