Clinical and translational advances in regulatory T cell-based strategies in allogeneic hematopoietic stem cell transplantation: highlights from ASH 2025

Regulatory T cells (T regs ), winners of the 2025 Nobel Prize in Physiology or Medicine, emerged as an unsung giant of peripheral immune tolerance after allogeneic hematopoietic stem cell transplantation (allo-HSCT). These cells exert influence across four interconnected immunological axes encompassing graft-versus-leukemia (GVL), graft-versus-host disease (GVHD), relapse, and viral infection. This correspondence highlights key advancements in T reg -based interventions in allo-HSCT, ranging from basic research to clinical applications, as presented at the ASH 2025 Annual Meeting. Accordingly, T regs are used as GVHD prophylaxis via the Orca-T platform and as a therapeutic strategy for steroid-refractory (SR)-GVHD patients. Experimental studies further pave the way to address existing limitations toward next-generation T reg -based cell therapy in allo-HSCT.