Background: Oral hedgehog inhibitors vismodegib and sonidegib have been used for the treatment of locally advanced (laBCC), metastatic basal cell carcinoma (mBCC) and in basal cell nevus syndrome (BCNS) patients. In the Netherlands, targeted therapy with vismodegib and sonidegib has been available since 2013 and 2021, respectively. No direct comparative studies have been performed between the two oral hedgehog inhibitors (HHI) vismodegib and sonidegib yet . In addition, data for sonidegib are not yet available.

Objective: The aim of this study is 1) to evaluate the effectiveness of oral HHIs in the treatment of laBCC, mBCC and BCNS patients and 2) to compare the oral HHIs vismodegib and sonidegib. Study design: prospective registration study that includes all patients, regardless of age and gender, with histologically proven basal cell carcinoma receiving treatment with either vismodegib or sonidegib in the Netherlands. Patient, tumor and treatment information was gathered from patient records. Main study parameters/endpoints: The primary outcome for measuring efficacy/tumor response was median progression free survival (PFS) where the decrease, stagnation or increase in tumor size is measured by maximum diameter. Secondary outcomes are frequency, severity and reversibility of treatment-emergent adverse events and disease-specific quality of life expressed as mean scores on the EORTC-QLQ-C30 and aBCCdex questionnaires.