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 and/or locally advanced basal cell carcinoma, in an open label prospective case series clinical trial

Abstract Background Vismodegib demonstrated 60% response rates in the ERIVANCE trial. Basal cell carcinoma (BCC) has various histopathologies. Their impact on response is unclear. Objective To determine if BCC histopathology impacted vismodegib response. Methods This phase 2b, single center, prospective case series study, compared the efficacy of vismodegib in infiltrative, nodular, and superficial BCCs treated for 12 or 24 weeks in 27 patients. Patients had one target lesion (TL) and up to 3 non-target lesions (NTL). Results Twenty-seven patients were enrolled, with 65 tumors (27 TL/38 NTL). At 24 weeks, most BCCs achieved histologic clearance, with positive biopsies in 10.5% TLs, 30.4% NTLs and 21.4% overall. No statistical differences were seen between histopathologic subtypes. 100% of patients experienced an adverse event (AE), 94% Grade 1 or 2. The most common AEs were dysguesia/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 Sample size of BCC histopathologic subtypes, sampling punch biopsies, and short follow up. Conclusions Basal cell histopathologic subtype did not significantly impact response to vismodegib. Each subtype was seen to completely respond at 12 and/or 24 weeks of therapy.