[Therapeutic strategies for graft-versus-host disease in the new era]

Graft-versus-host disease (GVHD), which develops after allogeneic hematopoietic stem cell transplantation, remains a major cause of non-relapse mortality despite advances in prophylactic strategies. Acute GVHD (aGVHD), which typically manifests around 1 month post-transplantation, occurs in 40% to 60% of patients and primarily affects the skin, liver, and gastrointestinal tract. Recently, biomarkers associated with aGVHD have been identified, and novel approaches combining clinical parameters and biomarkers are being employed for risk stratification and in clinical trials. This article provides an overview of a new severity classification system for aGVHD and discusses its implications for preemptive treatment strategies. Chronic GVHD (cGVHD), which typically develops 3 months or more after transplantation, occurs in 30% to 50% of patients and can affect multiple organs throughout the body. The NIH consensus criteria for cGVHD, published in 2005, established standardized diagnostic and severity grading systems, as well as response assessment criteria. These developments have significantly advanced both the understanding of the disease and the development of novel therapeutics. Three new drugs have now been approved in Japan for second-line treatment of cGVHD. This article explores the pathophysiology of cGVHD and examines therapeutic strategies involving these new agents.