Speaking from the 2018 European Society for Blood and Marrow Transplantation (EBMT) Annual Meeting in Lisbon, Portugal, Denis Claude Roy, MD, FRCP, of the University of Montreal, Montreal, Canada, discusses an innovative new photodynamic technique that eliminates the activated T-cells which can cause GvHD in haploidentical stem cell transplant recipients. This process has potential applications across a huge range of hematological malignancies.