Inhibition of smoothened by PF-5274857. A, chemical structure of PF-5274857. B, concentration-dependent competitive binding of PF-5274857 to human Smo (amino acid 181–787). C, inhibition of Gli transcription in Gli-luciferase reporter assay in MEF cells. Each point represents the mean of duplicate measurements ± SE. The curves represent the best fit of data to 4-parameter sigmoidal dose–response equation (Prism, GraphPad).
In vivo effects of PF-5274857 in Ptch+/−p53+/− medulloblastoma allograft mice. Ptch+/−p53+/− medulloblastoma allograft mice were dosed once daily for 6 days with PF-5274857 (0, 1, 5, 10, and 30 mg/kg). A, TGI. B, percentage change in body weight (BW). Each point represents the mean of measurements of 6 mice ± SE.
Modulation of Hh pathway genes in tumor (A) and skin (B) in Ptch+/−p53−/− medulloblastoma allograft mice treated with a single dose of 30 mg/kg PF-5274857. The gene expression levels are expressed as percentage relative to the vehicle group. The results are mean values of measurements of 3 mice ± SE.
Pharmacokinetics and biomarker response in single dose study. All data were obtained following a single oral dose of PF-5274857 (0, 5, 10, and 30 mg/kg). A, tumor Gli1 mRNA responses in Ptch+/−p53+/− medulloblastoma allograft mice. B, tumor Gli1 mRNA responses in Ptch+/−p53−/− medulloblastoma allograft mice. C, skin Gli1 mRNA responses in Ptch+/−p53−/− medulloblastoma allograft mice. D, total plasma concentrations. Each point represents the mean of measurements of 3 mice ± SE. The lines represent the model fit.
PF-5274857 penetrates blood–brain barrier in primary Ptch+/−p53−/− medulloblastoma mice. A, effects of PF-5274857 on the expression levels of Hh pathway genes in brain tumor. Primary Ptch+/−p53−/− medulloblastoma mice were treated with PF-5274857 (0, 10, 30, and 100 mg/kg) once daily by oral gavage for 4 days. The expression levels of genes in treated groups are shown as percentage relative to that in the vehicle group. The results are the average of measurements of 3 mice ± SE. B, treatment of primary Ptch+/−p53−/− medulloblastoma mice with PF-5274857 increases the survival rates.
Imaging of Hh pathway in brain of Gli-luc transgenic mice. A, images of Gli-luc transgenic mice treated with either vehicle (n = 4) or PF-5274857 (100 mg/kg, n = 5) by oral gavage once a day for 7 days. Region of the brain circled by red line represented the area for luminescence quantification. B, quantification of Gli signal in the brain of Gli-luc transgenic mice treated with vehicle, 30 or 100 mg/kg PF-5274857. The results were the average ± SE. The Student t test was used to determine the P value (*, P < 0.02; **, P < 0.002).