T-ALL human xenograft samples with GLI1 expression are sensitive to hedgehog inhibitors in vivo. (A-B) NSG mice injected with patient-derived T-ALL xenograft samples were treated with GDC-0449 or vehicle for 3 weeks (treatment period indicated by solid bar). Graphs show the percentage of human CD45 positive cells in the peripheral blood of NSG mice over time. (C) NSG mice injected with T-ALL xenograft cells with high GLI1 expression levels exhibit lower leukemic infiltration in bone marrow after treatment with hedgehog inhibitors. (D) Leukemia-free survival of mice injected with samples X09 or X15 treated with GDC-0449 or placebo. (E) Representative example of human leukemic cells and cells that proliferate, as defined by HLA and phospho-histone H3 staining, respectively, in the spleen of mice treated with placebo or GDC-0449. *P < .05; **P < .01; ***P < .001. Error bars indicate SEM.