In an abstract presented at the 11th Annual Meeting of the Society of Hematologic Oncology (SOHO), Houston, Texas, Yeliz Öğret, MD, Istanbul University Istanbul Medical Faculty Tissue Typing Laboratory, Istanbul, Turkey, presented an investigation on the impact of amino acid sequences in mismatched human leukocyte antigen (HLA) patient-donor pairs on the outcomes of hematopoietic stem cell transplantation (HSCT).
Epitopes, or specific proteins on the surface of HLAs, are regions recognized and targeted by the immune system. To determine the extent that epitope-mismatch between patient and donor affects the development of post-HSCT graft-versus-host disease (GVHD), Öğret et al pulled data on 22 patient-donor pairs from the HLA epitope registry.
The donors in this study were primarily 9/10 matched unrelated donors. HLA grouping and chimerism analyses were conducted using sequencing-based typing and the short tandem repeats method, respectively.
The researchers found that of 11 patients with 0-5 epitope mismatches, 4 developed GVHD; of 5 patients with 6-15 epitope mismatches, 4 developed GVHD; and of 6 patients with >16 epitope mismatches, 5 developed GVHD.
Importantly, the study found that the relapse rate did not show a statistically significant difference across these groups. The frequency of patients with 1 allele but 0-5 epitope mismatches was approximately half, although this difference was not statistically significant.
“We think epitope matching might be useful for identifying patients at high risk for serious complications such as GVHD after HSCT in HLA mismatched unrelated donors,” Dr. Öğret concluded.
Öğret Y, Tiryaki TO, Zanjani BN, et al. Impact of Epitope Match on Stem Cell Transplantation. Abstract CT-128. Presented at the 11th Annual Meeting of the Society of Hematologic Oncology; September 6-9, 2023; Houston, Texas.