Nivolumab With Vismodegib in Patients With Basal Cell Nevus Syndrome

This is a single-arm, phase II study to assess the efficacy of combined SMO and PD-1 inhibition with Vismodegib (SMO inhibitor) and Nivolumab (anti-PD-1 antibody) in BCNS patients (target enrollment of 22 patients), with a primary endpoint of 18-month disease control rate. The purpose of this study is to test the hypothesis that Nivolumab and Vismodegib will improve the percentage of BCNS patients who achieve disease control (defined as total tumor burden \<50% of baseline) at 18 months from 50% to 80%. Baseline and on-treatment biopsies will be obtained to characterize the immune effects of combined SMO and PD-1 inhibition.

Basal cell carcinoma (BCC) is by far the most common form of human malignancy, affecting more than 3.5 million Americans each year. Aberrant activation of the Hedgehog (Hh) pathway, typically through loss of the receptor Patched (PTCH) or oncogenic activation of Smoothened (SMO), has been identified as the primary driver of BCC growth and development. In particular, up to 1 in 57,000 individuals in the US are affected by a rare, autosomal dominant disorder characterized by mutations in protein patched homolog 1 (PTCH1) known as basal cell nevus syndrome (BCNS). These patients can develop dozens to hundreds of BCCs at any one time (1-5). Surgical removal of the entire tumor burden is not feasible. Hh-targeted therapies employing inhibitors of SMO (i.e., Vismodegib, Sonidegib) have shown remarkable efficacy in reducing tumor burden in BCC patients. However, the sustained clinical utility of these agents has been hampered by the rapid development of clinical resistance, significant tumor recurrence, and toxicity. Treatment strategies directed at finding additional molecular or immunological targets may enhance the possibility of sustained remission and/or cure of these tumors. Emerging data from our research group and others suggest the therapeutic efficacy of SMO inhibition may be dependent on immunological mechanisms. Hh inhibition appears to increase T cell recruitment and activation as well as upregulate major histocompatibility complex (MHC) class I expression on tumor cells. These data, together with case reports demonstrating the efficacy of cytotoxic T-lymphocyte associated protein 4 (CTLA-4) and programmed death-1 (PD-1) inhibition in Hh inhibitor-naïve and resistant BCCs, support a role for anti-tumor immunity in BCC and underscore the potential enhanced therapeutic efficacy of combined SMO and immunological checkpoint inhibition.