[Treatment of graft-versus-host disease]

Graft-versus-host disease (GVHD) is one of the most important complications after an allogeneic hematopoietic stem cell transplantation (allo-SCT). The current National Institutes of Health's (NIH) consensus is that clinical manifestations, and not the time to symptomatic onset after transplantation, determine whether the clinical syndrome of GVHD is considered acute or chronic. In the past decade, peripheral blood stem cell transplantation from an unrelated donor can be performed in Japan. Furthermore, poor-risk patients without human leukocyte antigen (HLA)-matched donor can receive allo-SCT from HLA haploidentical donor. Therefore, severe or steroid-refractory GVHD would be increased. Corticosteroid, at a dose of 2 mg/kg, is a standard first-line therapy for acute GVHD. If there is no improvement after the first-line therapy, second-line therapy should be administered immediately. Although anti-thymocyte globulin and mesenchymal stem cells are covered by health insurance in Japan, another treatment options should be determined for steroid-refractory acute GVHD. Furthermore, severe chronic GVHD increases patients' mortality and decreases their quality of life. A number of novel drugs targeting specific biological pathways for GVHD are under development. Currently, more than 60 clinical trials are carried out for the treatment of steroid-refractory GVHD worldwide for drug approval. The accumulation of novel evidence for GVHD treatment is expected to be established.