HLA matching in contemporary haematopoietic cell transplantation: Recommendations from the EBMT Practice Harmonisation and Guidelines Committee.

HLA compatibility has been a cornerstone for safe and successful allogeneic haematopoietic cell transplantation (HCT), with human leukocyte antigen (HLA)-mismatched transplants consistently associated with inferior survival. However, recent advances in typing technologies, supportive care, and novel graft-versus-host disease (GvHD) prophylaxes have prompted the revisiting of HLA mismatch relevance in contemporary HCT. Within the framework of the 3rd Workshops of the Practice Harmonization & Guidelines Committee, the EBMT convened a group of experts in histocompatibility & immunogenetics, HCT immunobiology, and clinical HCT, to review the current state of the art and develop a set of consensus-based recommendations on the role of HLA in current HCT. The topics included technological aspects of HLA typing, the role of HLA mismatches in donor selection, and the detection and management of anti-HLA antibodies in HLA-mismatched transplantation. Moreover, the role of HLA matching relative to other non-HLA factors and in the context of novel GvHD prophylaxes, non-malignant disease, and pediatric populations was defined. Finally, the relevance of special models for HLA matching and of post-HCT monitoring of HLA-loss in malignant disease relapse was reviewed. The present document summarizes the expert consensus on these topics, to provide evidence-based recommendations for clinical decision-making.