Treatment with LDE223 initiated after onset of clinical disease effectively ameliorates clinical and histologic changes of sclerodermatous cGVHD. Treatment with LDE223 on first clinical signs improved clinical features of cGVHD as evidenced by a increased recovery of the body weight after alloBMT (A) and by decreased composite score (B). Treatment with LDE223 (C) reduced dermal thickening, (D) prevented further increase of the hydroxyproline content, and (E) reversed the differentiation of resting fibroblasts into myofibroblasts. Six mice per group were analyzed. synBMT indicates syngeneic controls; and alloBMT, mice receiving alloBMT.