Participants 18 years and older who meet the diagnostic criteria for the basal cell nevus (Gorlin) syndrome will be assigned to receive either Patidegib Gel 2% or Placebo (no active medicine) to apply twice daily for 12 months. The assignment will be made according to sex assigned at birth, age, and number of BCC lesions at the treatment area at Baseline. The primary endpoint is a comparison between the 2 treatment arms of the number of new BCCs at Month 12 compared to Baseline. The BCCs will be imaged and tracked consistently throughout the study to identify new BCCs and to confirm their diagnosis by dermoscopy (handheld instrument with a 15x magnification lens and a cross-polarized light source).

Participants will participate in 15 visits over approximately 14 months (attend 6 in person visits along with 9 phone call visits). In addition, participants will receive study medication to apply twice a day for 12 months and undergo clinical tests at various time points, which include blood tests, ECG, complete questionnaires/diary, skin exam and skin photographs.

Compensation is provided for eligible participants.