Abstract A021: Development of a novel MEK inhibitor, NFX-179, as a chemoprevention agent for squamous cell carcinoma
Authors: Sarin Kavita Y. , Kincaid John , Sell Brittney , Shahryari Jahanbanoo , Duncton Matthew A. J. , Morefield Elaine , Sun Wenchao , Chavez-Chiang Omar , Plotkin Scott R. , Kochendoerfer Gerd G. , Fenn Peter , Powala Christopher , Tsai Kenneth Y. 
Published: December 2022

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer comprising at least 20% of all non-melanoma skin cancers. While cSCC contributes to significant morbidity and mortality in high-risk individuals, deployment of otherwise effective chemoprevention of cSCC is limited by toxicities. To help address this, we conducted a systematic computational drug repositioning screen which predicted that selumetinib, an FDA-approved MEK inhibitor (MEKi), would reverse transcriptional signatures associated with cSCC development. This is consistent with our genomic analysis implicating ETS2, a transcription factor in the canonical RAS/RAF/MEK/ERK Mitogen-Activated Protein Kinase (MAPK) pathway, as an upstream regulator of cSCC development. Therefore, as a key regulator of the MAPK pathway, we reasoned MEK would be a viable chemopreventive target. Although systemic MEK inhibition suppresses the formation of cSCC in mice, systemic MEKi administration causes significant adverse effects, including diarrhea, peripheral edema, cardiomyopathy and retinal toxicity.

Here, we report the development of a topically formulated, metabolically labile, novel MEKi, NFX-179, designed to potently and selectively suppress the MAPK pathway in the skin prior to rapid metabolism in the systemic circulation. NFX-179 was identified from a targeted drug discovery effort based on its biochemical and cellular potency, selectivity, and rapid metabolism upon systemic absorption. In our UV-induced cSCC mouse model, topical application of NFX- 179 gel reduced the formation of new cSCCs by an average of 60% at doses of 0.1% and greater at 28 days. No systemic or skin toxicities were observed in this model. Furthermore, we conducted a second split-mouse randomized controlled study in which NFX-179 0.5% gel was applied to one half of the back and vehicle was applied to the opposite half of each of the UV-irradiated mice. Near complete suppression of cSCC was observed only in the drug-treated area, demonstrating the targeted and dermal effect of the intervention. NFX-179 inhibits the growth of human SCC cell lines in a dose-dependent manner and topical NFX-179 application penetrates human skin and inhibits MAPK signaling in human cSCC explants. Together our data provide compelling rationale for using topical MEK inhibition through application of NFX-179 gel as an effective strategy for cSCC chemoprevention.

Citation Format: Kavita Y. Sarin, John Kincaid, Brittney Sell, Jahanbanoo Shahryari, Matthew A. J. Duncton, Elaine Morefield, Wenchao Sun, Omar Chavez-Chiang, Scott R. Plotkin, Gerd G. Kochendoerfer, Peter Fenn, Christopher Powala, Kenneth Y. Tsai. Development of a novel MEK inhibitor, NFX-179, as a chemoprevention agent for squamous cell carcinoma [abstract]. In: Proceedings of the Second Biennial NCI Meeting: Translational Advances in Cancer Prevention Agent Development (TACPAD); 2022 Sep 7-9. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_2): Abstract nr A021.