Chronic graft-versus-host disease: disease biology and novel therapeutic strategies.

Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation. Chronic GVHD often presents with clinical manifestations that resemble those observed in autoimmune diseases. Standard treatment is 1-2mg/kg/day of prednisone or an equivalent dose of methylprednisolone, with continued administration of a calcineurin inhibitor for steroid sparing. However, the prognosis of steroid-refractory chronic GVHD remains poor. Classically, chronic GVHD was said to involve predominantly Th2 responses. We are now faced with a more complex picture, involving possible roles for thymic dysfunction, transforming growth factor-β (TGF-β) and platelet-derived growth factor (PDGF), B cells and autoantibodies, and Th1/Th2/Th17 cytokines, as well as regulatory T cells (Tregs), in chronic GVHD. More detailed research on the pathophysiology of chronic GVHD may facilitate the establishment of novel strategies for its prevention and treatment.