Histocompatible unrelated volunteer donors compared with HLA nonidentical family donors in marrow transplantation for aplastic anemia and leukemia.

We treated 14 patients by transplantation of marrow from unrelated volunteer donors. Eight patients had severe aplastic anemia, 3 had chronic granulocytic leukemia, and 3 had Fanconi's anemia. The results are compared with those of a group of 14 similar patients transplanted concurrently from human leukocyte antigen (HLA)-mismatched family members: Sustained engraftment was achieved in 8 of 14 patients in both groups; one additional patient survived with autologous marrow reconstitution following an unrelated donor transplant. In the unrelated donor group, 6 of 9 evaluable patients developed grade III through IV acute graft-v-host disease, as compared with 4 of 9 patients after family-mismatched transplants. Overall survival was similar in the two groups. In the unrelated donor group 4 of 14 (29%) patients survived (median survival 1,299 days) as compared with 5 of 14 (36%) in the mismatched-family donor group (median survival 808 days). In both groups, patients with HLA phenotypically matched donors fared better than those with donors who were mismatched for one or more HLA antigen. Of the patients transplanted from HLA phenotypically matched donors 6 of 12 patients (50%) survived, as compared with 3 of 16 patients (19%) transplanted from HLA-mismatched donors. We conclude that unrelated donor bone marrow transplantation (BMT) should be considered in those cases of leukemia or bone marrow failure in which the chance of cure using conventional therapy is remote and a HLA genotypically or phenotypically matched family donor is not available.