While Fausidil, a small molecule inhibiting ROCK1 and ROCK2 only had moderate ameliorating effects on GVHD-associated colitis (184), the ROCK2 inhibitor Belomosudil (KD025), which shifts the Th17/Treg balance towards homeostasis via an STAT3/STAT5-dependent mechanism, efficiently ameliorated chronic GVHD in multiple models and first clinical studies (185, 227). This evidence concerns the gene STAT3 and graft versus host disease.