Efficacy, rate of tumor response, and safety of a short course (12-24 weeks) of oral vismodegib in various histologic subtypes (infiltrative, nodular, and superficial) of high-risk or locally advanced basal cell carcinoma, in an open-label, prospective case series clinical trial

Background: Vismodegib demonstrated 60% response rates in the ERIVANCE trial. Basal cell carcinoma has various histopathologies. Their effect on response is unclear. Objective: The purpose of this study was to determine whether basal cell carcinoma histopathology affected vismodegib response. Methods: This phase 2b, single-center, prospective case series study compared the efficacy of vismodegib in infiltrative, nodular, and superficial basal cell carcinomas treated for 12 or 24 weeks in 27 patients. Patients had 1 target lesion and up to 3 nontarget lesions. Results: Twenty-seven patients were enrolled, with 65 tumors (27 target lesions/38 nontarget lesions). At 24 weeks, most basal cell carcinomas achieved histologic clearance, with positive biopsy results in 10.5% of target lesions, 30.4% of nontarget lesions, and 21.4% overall. No statistical differences were observed between histopathologic subtypes. One hundred percent of patients experienced an adverse event, 94% grade 1 or 2. The most common adverse events were dysgeusia/loss of taste (86%), muscle spasms (82%), and alopecia (71%). Clinically progressive disease during treatment was low (1.5%). Two patients had recurrence within 1 year of treatment. Limitations: Limitations included sample size of basal cell carcinoma histopathologic subtypes, sampling punch biopsies, and short follow-up. Conclusions: Basal cell histopathologic subtype did not significantly affect response to vismodegib. Each subtype was observed to completely respond at 12 weeks of therapy, 24 weeks, or both.