Here, Steven Pavletic, MD, MS, from the National Cancer Institute, Bethesda, MD, discusses the previous management of chronic graft-versus-host disease (GvHD), with the BTK inhibitor ibrutinib having been approved for the treatment of patients with chronic GvHD. From the European Society for Blood and Marrow Transplantation (EBMT) 2018 Annual Meeting, held in Lisbon, Portugal, Dr Pavletic also outlines the biology of the disease and how its understanding has been improved significantly with recently conducted research.