Outcomes After Transplantation of Cord Blood or Bone Marrow From Unrelated Donors in Adults With Leukemia

Abstract

At present, an estimated 1 in 5 leukemic patients receives a bone marrow or stem cell transplant from an unrelated donor or an HLA-mismatched related donor. Cord blood grafts from unrelated donors have been successful, most often in children. Hematopoiesis recovers more slowly than with bone marrow grafts, contributing to relatively high rates of infection and early death. This study examined outcomes in adults with leukemia, from 16 to 60 years of age, who received transplants of hematopoietic stem cells from unrelated donors. Data were acquired from the International Bone Marrow Transplant Registry and from the National Cord Blood Program of the New York Blood Center. Cord blood was mismatched for 1 HLA antigen in 34 cases and for 2 antigens in 116 others. Bone marrow had 1 HLA mismatch in 83 cases, whereas 367 patients received HLA-matched bone marrow. The patients given cord blood were younger than those given marrow transplants and likelier to have advanced leukemia. Median follow-up intervals were 4 years for marrow recipients and 40 months for those given cord blood transplants. For patients whose neutrophils and platelets recovered, recovery times were shorter after marrow transplantation and longest (27 days) after cord blood transplantation. A similar pattern was found for platelet recovery, with a median recovery interval of 60 days after cord blood transplantation. There were no major differences in recovery of either neutrophils or platelets after 12 months. Acute graft-versus-host disease (GVHD) was less likely after transplanting mismatched cord blood than mismatched bone marrow. Among patients who lived 3 months or longer, chronic GVHD was most frequent in patients given cord blood. The fewest treatment-related deaths were in patients given HLA-matched bone marrow transplants. Recurrences were similarly frequent in all groups. Treatment failure was least frequent in patients given HLA-matched bone marrow. After adjusting for other factors, the chance of living 3 years without recurrent leukemia was 19% for mismatched bone marrow recipients, 23% for cord blood recipients, and 33% after transplantation of HLA-matched bone marrow. Transplanting HLA-matched bone marrow was associated with the lowest all-cause mortality. When an HLA-matched marrow donor is not available, cord blood mismatched for 1 or 2 antigens and bone marrow mismatched for 1 antigen are acceptable alternatives.