Impact of High-Resolution HLA Matching on Outcomes of Unrelated Donor Hematopoietic Stem Cell Transplantation.

Objective: We assessed the impact of high-resolution genotypic results of human leukocyte antigen (HLA) for all major class I and II loci between donors and recipients in the outcome of unrelated hematopoietic stem cell transplantation (HSCT).

Method: Between 1999 and 2005, high-resolution genotyping for HLA-A, -B, -C and -DRB1 was performed for 23 unrelated HSCT. All the patients were typed as HLA identical by serologic technique and then they were also typed HLA identical by high resolution technique. Unrelated bone marrow transplantation using DNA-based high resolution HLA compatibilities were considered in the analyses of clinical outcomes such as hematopoietic engraftment, acute GVHD, and survival. And then, we compared with patients who received related HSCT (same institute, same duration) and also unrelated HSCT data from IBMTR.

Results: Median follow up duration was 9 months (1–51). Fifteen patients were male and 8 were female. Median age was 22 years (range 6–52). Median time from diagnosis to transplantation was 7 months (range 4–63). Eight patients of acute myeloid leukemia (AML), 6 of chronic myeloid leukemia (CML, 2 of 6 were in blast crisis), 4 of acute lymphoid leukemia (ALL), 3 of severe aplastic anemia and each case of juvenile myelomonocytic leukemia and myelodysplastic syndrome were enrolled. Median value of total nucleated cell and CD34 positive cell count was 3.51 (1.06–20.7) x 10⁸/kg and 4.88 (1.33–46.9) x 10⁶/kg, respectively. The conditioning regimen and prophylaxis for graft versus host disease (GVHD) were not different from conventional HSCT except one case of non-myeloablative transplantation. Median value of granulocytic (absolute granulocyte count > 500/mm³) and platelet (> 20,000/mm³) engraftment were D + 16, D + 17, respectively. Grade II acute GVHD developed in 4 patients (2 patients subsequently proceded to chronic GVHD). Treatment related mortality was 2 out of 23 patients (8.7%). Median value of overall survival duration was 30 months. For AML patients, 3-year survival rate was 72.9 %.

Conclusions: Our survival data for unrelated HSCT based on high resolution genotyped HLA matching was superior to unrelated HSCT. Although the sample size is small, the survival data of AML patients (CR1 at transplant) was superior to the survivals of related HSCT, as well as that of unrelated HSCT. The findings were that transplantation using unrelated donors selected by high-resolution genotype identity improves the transplantation outcomes similar degree to the result of the related HSCT.