Additionally, blocking of STAT3 by both Givinostat and Virinostat, was shown to enhance indoleamine 2,3-dioxygenase (IDO) expression in APCs which suppresses APC allo-stimulatory functions and reduced GVHD in a murine allogeneic BM-transplantation model (215). Here, STAT3 is linked to graft versus host disease.