Unrelated Donor (URD) Searches in African-Americans with Hematologic Malignancies: Paucity of HLA Identical Donors.

Recent analyses have demonstrated the importance of molecular matching in HLA-A, B, C and DRB1 (8/8) for the success of adult URD hematopoetic stem cell transplantation (HSCT). Little is known about the likelihood of identifying an 8/8 HLA identical URD in pts of African-American (AA) descent. From 2/2002 to 5/2007, we performed 51 preliminary (PRLM) URD searches for AA pts using the National Marrow Donor Program (NMDP) and its cooperative international registries. The median age was 38 (range, 1–73), and diseases included AML (n=18), MDS (n=1), ALL (n=1), CLL (n=4), CML (n=4), Hodgkin lymphoma (n=4), NHL (n=4), MM (n=1), severe aplastic anemia (n=4), sickle cell anemia (n=6), and other (n=4). Of the 51 PRLM searches, 13 (25%) pts had at least 1 potential HLA-A, B, and DRB1 (6/6) URD and 37 pts had at least 1 potential URD with a single allele or antigen mismatch at HLA-A, B, or DRB1 (5/6). Of the 13 pts with potential 6/6 donors, 12 proceeded to a formal URD search. After a median formal search duration of 5 months (range 1–39), 3 pts were found to have a high resolution 8/8 HLA identical URD (6% of total AA searches, 25% of formal searches with 6/6), and 2 were found to have an URD with a single allele or antigen mismatch at one of the 8 HLA loci (7/8). Two of the 3 pts with an 8/8 HLA identical URD were transplanted. Twenty-four of the 37 AA pts with a potential 5/6 URD proceeded to formal URD search. The median formal search duration for this group was also 5 months (range 1–29). Eight pts were found to have a high resolution 7/8 HLA URD (33% of formal searches with 5/6), but only 1 went on to HSCT using the 7/8 HLA URD. 275 donors were activated, and 133 were unavailable (48%). These data illustrate the difficulty in locating an appropriate URD in AA pts. In order to allow more AA pts to proceed to HSCT in a timely manner, alternative donor procurement strategies (e.g. haplo-identical or umbilical cord transplantation) should be investigated.