Novel Scoring System for Ranking Hematopoietic Stem Cell Transplantation

ABSTRACT Background When human leukocyte antigen (HLA)‐matched donors are not available for hematopoietic stem cell transplants (HSCT), there are no well‐accepted guidelines for ranking 7/8 HLA‐matched unrelated donors to achieve optimal transplant outcomes. A novel scoring system for ranking HLA mismatches for these donors was investigated. Methods High‐resolution HLA types were used to determine amino acid mismatches located in the HLA antigen‐recognition domain. The location and physicochemical properties of mismatched amino acids were used to assign scores for peptide binding, T‐cell receptor docking, and HLA structure/function. The scores were tested using a cohort of 2319 patients with leukemia or myelodysplastic syndrome who received their first unrelated donor transplant using conventional graft‐versus‐host disease (GVHD) prophylaxis between 2000 and 2014. Donors were 7/8 HLA‐matched with a single HLA Class I mismatch. Primary outcomes were overall survival and acute GVHD. Results The scores did not significantly (p