Vipul Sheth, PhD, Fred Hutchinson Cancer Research Center, Seattle, USA, discusses the findings of a single center retrospective study of T-cell lineage mixed chimerism as a prognostic factor in acute leukemias and myelodysplastic syndromes (MDS). T-cell depletion, in particular with alemtuzumab, reduces the risk of graft-versus-host disease in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) with unrelated donor peripheral stem cell grafts. However, it has also been associated with an increased occurrence of mixed T-cell chimerism and subsequent relapse. Dr Sheth describes the findings of a study which compared the long-term outcomes of 106 patients with T-cell mixed chimerism to 111 patients with complete chimerism. This interview took place at the virtual European Hematology Association (EHA) Congress 2021.