Mohamad Mohty, MD, PhD of Saint-Antoine Hospital, Paris, France discusses a pair-matched analysis from the Acute Leukemia Working Party of EBMT on allogeneic genetically modified T-cells (HSV-TK) as adjunctive treatment in haploidentical hematopoietic stem cell transplantation (haplo-HSCT) of adult patients with high-risk hematological malignancies. Prof. Mohty explains that we have witnessed an increase in the use of haplo-HSCT over recent years. Despite advances in the field, we are still facing some limitations such as delayed immune reconstitution, higher incidence of opportunistic infections and graft-versus-host disease (GvHD). This is where the introduction of genetically modified TK cells is likely to going to be an important tool for improving immune reconstitution. The results show that in the setting of haplo-HSCT, the infusion of these genetically modified TK cells is capable of improving immune reconstitution, decrease the mortality and incidence of GvHD and improve overall survival (OS). Recorded at the 2016 Annual Meeting of the American Society of Hematology, held in San Diego, CA.