Abstract
•Advances in GVHD prophylaxis expand access to allogeneic HCT for all patients.•Perform searches concurrently for all donor types informed by search prognosis.•Planned GVHD prophylaxis strategy impacts HLA matching requirements.•Less stringent matching allows prioritization of secondary donor characteristics.
Allogeneic hematopoietic cell transplantation (HCT) remains a curative therapy for many patients with hematologic malignancies, bone marrow failure syndromes, inborn errors of immunity and metabolic disorders. Current donor selection strategies typically prioritize the selection of an HLA-matched donor over HLA mismatched (“alternative”) donor sources, with a hierarchical approach to the donor search. More recent data challenge this rubric, particularly in the context of novel graft-versus-host disease (GVHD) prophylaxis strategies that demonstrate improved outcomes in alternative donor HCT recipients. In this setting, an increased emphasis on non-HLA factors (both donor characteristics and systemic factors) in determining donor selection is now feasible. In this guideline, we review recent evidence from prospective clinical trials as well as high-quality observational studies and provide expert panel recommendations on donor selection algorithms and prioritization in the era of novel GVHD prophylaxis. We then highlight important questions still to be answered in our field.