Inhibition of the hedgehog pathway in patients with basal-cell nevus syndrome: final results from the multicentre, randomised, double-blind, placebo-controlled, phase 2 trial.

BACKGROUND: Aberrant hedgehog signalling underlies the development of basal-cell carcinomas. We previously reported the interim analysis of a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial in patients with the basal-cell nevus (Gorlin) syndrome indicating that the smoothened inhibitor vismodegib reduces basal-cell carcinoma tumour burden and prevents new basal-cell carcinoma growth in patients with basal-cell nevus syndrome. We report the final results of this 36 month trial. METHODS: In our multicentre, randomised, double-blind, placebo-controlled, phase 2 trial we enrolled patients aged 35-75 years with basal-cell nevus syndrome with at least ten surgically eligible basal-cell carcinomas at the Children's Hospital Oakland, Columbia University outpatient dermatology clinic (NY, USA) and a private practice outpatient dermatology office in Newport Beach (CA, USA). Patients were assigned to vismodegib or placebo (2:1) according to a randomisation sequence generated by computer code. The primary endpoint of the trial of 41 patients was to compare the effect of oral vismodegib (150 mg/day) versus placebo on the incidence of new surgically eligible basal-cell carcinomas after 3 months of treatment. In the subsequent, open-label phase (n=37) patients continued vismodegib at two sites for as long as month 36 (n=25) and at the third site were monitored up to month 36 (n=12). Additional endpoints for this phase were: whether continuous versus interrupted dosing differentially affected tumour burden; time to reach various levels of reduction in tumour burden; reduction in tumour size in patients who took less than 50% of the expected number of vismodegib tablets; reduction in the number of surgical excisions required per year before, during, and after treatment; and the effect of vismodegib on hedgehog target gene expression. We monitored patients at visits every 3 months for up to 36 months. The primary endpoint was analysed on a modified intention-to-treat basis. This trial is registered with ClinicalTrials.gov, number NCT00957229. FINDINGS: Between Sept 22, 2009, and Jan 24, 2011, 41 patients were monitored for a median of 36 months (IQR 36-36). Patients treated with vismodegib (n=26) had a mean reduced rate of new surgically eligible basal-cell carcinomas compared with patients randomly assigned to placebo (n=15; two [SD 0·12] new surgically eligible basal-cell carcinomas per patient per year vs 34 [1·32] new surgically eligible basal-cell carcinomas per patient per year, p<0·0001). In the 11 patients initially assigned to placebo, mean cross over to vismodegib reduced the development of new surgically eligible basal-cell carcinomas compared with placebo (0·4 [SD 0·2] new surgically eligible basal-cell carcinomas per patient per year vs 30·0 [7·8] new surgically eligible basal-cell carcinomas per patient per year, p<0·0001). Only three (17%) of 18 patients tolerated vismodegib continuously for the full 36 months. Fewer new surgically eligible basal-cell carcinomas developed in patients receiving vismodegib continuously than in those who interrupted dosing (mean 0·6 [0·72] new surgically eligible basal-cell carcinomas per patient per year vs 1·7 [1·8] new surgically eligible basal-cell carcinomas per patient per year, p<0·0001). Treatment-related grade 3-4 adverse events included weight loss of 20% or more (n=6) and muscle cramps (n=2). Two patients died during the course of the trial, one each from laryngeal and metastatic prostate cancer, deemed probably unrelated to drug. INTERPRETATION: Vismodegib reduces basal-cell carcinoma tumour burden in patients with basal-cell nevus syndrome. Adverse events associated with vismodegib frequently led to interruption of treatment, which is followed by basal-cell carcinoma recurrence. FUNDING: Genentech investigator-initiated trial funding, Clinical and Translational Science Award from the National Institutes of Health, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Cancer Institute, Damon Runyon Cancer Research Foundation Clinical Investigator Award, Swim across America Foundation, and Michael J Rainen Family Foundation.