Secondary Resistance to Vismodegib After Initial Successful Treatment of Extensive Recurrent Periocular Basal Cell Carcinoma with Orbital Invasion.

Vismodegib is proven to be effective in the treatment of locally advanced and metastatic basal cell carcinoma, but evidence of resistance is beginning to emerge. A case of advanced recurrent periocular basal cell carcinoma which responded dramatically to vismodegib after 3 months but recurred after 9 months due to drug resistance, eventually requiring orbital exenteration, is presented. The mechanism of vismodegib resistance is discussed.