Hedgehog pathway inhibitor in combination with radiation therapy for basal cell carcinomas of the head and neck First clinical experience with vismodegib for locally advanced disease

Background Definitive radiotherapy and vismodegib, an oral inhibitor of the hedgehog pathway, are both established treatment options for locally advanced basal cell carcinomas (BCC). Both have shown good results in local tumor control; however, the effects concerning advanced tumors are often not of a lasting nature and to date no systematic data about the combination of the two modalities are available. Patients and methods We retrospectively analyzed four patients who received vismodegib and radiotherapy in combination. Radiation doses varied between 50.4 Gy and 66.0 Gy. Three patients had recurrent BCC. One patient had locoregional lymph node involvement. Vismodegib was taken once a day (150 mg) during the entire time of irradiation and beyond upon instructions of the attending dermatologist. Results In three cases a persistent complete response was observed, in one case the tumor remained stable for approximately 6 months until further tumor progression was documented. The combined therapy was well tolerated in all cases. No exceptional side effects pointing at a drug-radiation interaction were observed. Conclusion The combination of vismodegib and radiation seems feasible and the initial results are promising. In our cohort, there was no increase in unexpected side effects. Further research is needed to evaluate the significance of this combined therapy.