Predictive Factors of Non-Response to Vismodegib in Locally Advanced Basal-Cell Carcinoma.

BACKGROUND: Vismodegib has shown clinical efficacy in the management of locally advanced basal cell carcinomas (laBCC). However, non-response to vismodegib is observed in 2-13.5% of patients in clinical studies. The purpose of this study was to identify factors associated with non-response to vismodegib in patients with laBCC.

METHODS: We carried out a retrospective multicenter study, including patients with laBCC treated with vismodegib, from July 2011 to May 2019. Response to treatment was assessed according to the RECIST 1.1 criteria. Patients were categorized as responders with a complete response or a partial response or non-responders with a stable disease or a progressive disease according to what has been observed during follow-up. Patient demographics, tumor profile, and treatment modalities were compared in responders and non-responders.

RESULTS: Eighty-three patients with laBCC were included in the study. Twenty-five (30.1%) were non-responders to vismodegib. History of treatment with radiotherapy, presence of muscle involvement and intermittent treatment with vismodegib were significantly associated with a non-response (p < 0.001, p = 0.025, p < 0.001). Bone involvement (p = 0.2) and morpheaform IaBCC subtype (p = 0.056) were more frequent in non-responders without reaching statistical significance.

CONCLUSION: In this study, non-response of laBCC to vismodegib therapy was associated with muscle involvement. Previous radiotherapy and intermittent use of vismodegib have been identified as causes favoring non-response to vismodegib. Due to the low numbers of patients included in the study, it is difficult to draw firm conclusions. Further studies are needed to confirm these data.