LY2940680 is a selective inhibitor of Smo receptor and thus inhibits Hh signaling pathway [1].

Smoothened(Smo) receptor is a member of class F G protein-coupled receptors, which plays an important role in the main transducer of the Hedgehog (Hh) signaling pathway that implicated in a wide range of developmental and adult processes [2].

LY2940680 is a potent Smo receptor inhibitor that binds mostly to extracelluar loops and has a different functioning site with the reported Smo receptor inhibitor SANT-1 which binds to 7TM [2]. When tested with cell lines containing a mutation in the gene encoding Smoothened that researchers had previously observed in patient with cancer who developed resistance to vismodegib, LY2940680 inhibited cell proliferation [3].

Many studies have shown that Hh signaling pathway plays a pivotal role in CSCs and Hh inhibition caused many aspects of transformation attributed to CSCs. In patients with basal cell carcinoma and medulloblastoma, LY2940680 showed good efficacy as a monotherapy [1].

References:
[1].? Justilien, V. and A.P. Fields, Molecular pathways: novel approaches for improved therapeutic targeting of Hedgehog signaling in cancer stem cells. Clin Cancer Res, 2015. 21(3): p. 505-13.
[2].? Hoch, L., et al., MRT-92 inhibits Hedgehog signaling by blocking overlapping binding sites in the transmembrane domain of the Smoothened receptor. Faseb j, 2015. 29(5): p. 1817-29.
[3].? Redmond, E.M., et al., Investigational Notch and Hedgehog inhibitors--therapies for cardiovascular disease. Expert Opin Investig Drugs, 2011. 20(12): p. 1649-64.