PF-5274857

PF-5274857 is a novel Smo antagonist that specifically binds to Smo with a K(i) of 4.6 ± 1.1 nmol/L and completely blocks the transcriptional activity of the downstream gene Gli1 with an IC(50) of 2.7 ± 1.4 nmol/L in cells. The μ-opioid receptor is weakly inhibited by PF-5274857 with a dissociation constant of 36 μM subsequently determined in a functional assay. PF-5274857 was orally available and metabolically stable in vivo. PF-5274857 shows significant dose-dependent tumor growth inhibition (TGI) and induces tumor regression at high doses(>10 mg/kg). PF-5274857 is a potentially attractive clinical candidate for the treatment of tumor types including brain tumors and brain metastasis driven by an activated Hedgehog (Hh) signaling pathway. PF-5274857 is also able to cross the blood–brain barrier in rats within 4 hours post-dose.