UNRELATED DONOR BONE-MARROW TRANSPLANTATION FOR HEMATOLOGICAL MALIGNANCIES-CURRENT STATUS

We have explored the efficacy and toxicity of hematopoietic stem cell transplantation from unrelated donors for hematologic malignancies and other disorders. While most marrow donors have been identified throug h the National Marrow Donor Program in cooperation with many internati onal registries, the recent development of unrelated donor umbilical c ord blood (UCB) banks has allowed us to also evaluate this stem cell s ource. Analysis of the first 211 URD BMT performed at the University o f Minnesota shows an overall survival of 33%, with older recipient age and transplant from a donor with a major HLA A or B mismatch independ ently associated with poorer survival. Analysis of engraftment of URD marrow shows increasing risk of delayed or incomplete engraftment with increasing HLA disparity between URD and recipient. GVHD is increased in recipients of URD marrow compared with recipients of related donor marrow. Malignant relapse, however, is less frequent in URD marrow re cipients, perhaps due to an increased, graft-versus-leukemia effect. F ormal assessment shows quality of life in long term URD BMT survivors (beyond 2 years) is excellent, and not different from that seen in sib ling marrow recipients. Data from patients receiving unrelated donor U CB transplantation at the University of Minnesota indicate that UCB is an acceptable alternate source of stem cells, at least for young reci pients, and may be associated with a reduced incidence of GVHD. Ongoin g studies at the University of Minnesota include examination of the ap plicability of unrelated UCB transplantation to adult recipients, and of the degree of HLA-incompatibility which can be tolerated in UCB tra nsplantation. Studies to identify the optimal GVHD prophylaxis for URD BMT, and to examine the role of class II matching in transplant outco me are in progress.