Phase 2 Trial of Topical Application of the Hedgehog Inhibitor Patidegib in Patients With Gorlin Syndrome.

Background: Patients with Gorlin (basal cell nevus) syndrome (GS) have numerous phenotypic abnormalities due to over-activity of the hedgehog (HH) signaling pathway, most commonly due to a heritable mutation in the PTCH1 gene, which encodes a major inhibitor of this pathway. HH inhibitors (HHi) taken orally can reverse some of the manifestations, most prominent of which is the development of numerous cutaneous basal cell carcinomas (BCCs). In order to improve the benefit:risk ratio, we have developed a gel containing a small cyclopamine-derived molecule that can be applied topically in expectation that this mode of delivery can reduce the burden of BCCs without producing the systemic adverse effects that cause patients to stop treatment with oral HHis.

Objectives: This study attempts to determine whether or not Patidegib Topical Gel, 2% or 4%, can accumulate in high enough concentrations to have local anti-BCC efficacy but not so high that systemic drug levels produce the adverse effects that are typical of oral HHi treatment.

Methods: We conducted a small, randomized, double blinded Phase 2A trial at two sites in the United Kingdom to assess the clinical and molecular efficacy and adverse effects of 6 months of twice daily application of Patidegib Topical Gel to the entire face as well as to treatment-targeted surgically-eligible BCCs at other anatomical sites.

Results: Post hoc analyses suggested that Patidegib Topical Gel reduced the number of new surgically-eligible BCCs and the level of HH signaling with minimal adverse effects.

Conclusions: Patidegib Topical Gel warrants further clinical development.