Mekanistic Therapeutics seeks to design, discover, and develop anti-cancer agents that selectively inhibit multiple oncogenic pathways. Among Mekanistic’s portfolio are dual and highly selective inhibitors of EGFR and PI3 kinase, which were rationally designed to only target these two critical oncogenes. The PI3 kinase (PI3K)/AKT/mTOR pathway plays a central role in driving tumor cell survival and progression. Despite intensive efforts of the pharmaceutical industry, PI3K inhibitors, encompassing isoform selective as well as pan-PI3K inhibitors, have largely failed to produce single agent activity against solid tumors. EGFR is a major contributor to the adaptive signaling mechanisms that lead to PI3K inhibitor resistance. Squamous cell carcinomas, which comprise an area of high unmet medical need, exhibit a high incidence of genomic alterations in both EGFR and PI3K. A central goal of this project is to provide preclinical proof of concept to support monotherapy development of a lead EGFR/PI3K inhibitor that is ideally suited to treat squamous head and neck cancers. Our preliminary data generated in multiple head and neck squamous cancer models strongly support this line of investigation. Phase I aims are focused on evaluation of the pre-lead molecule MTX-531 for its antitumor activity against patient-derived head and neck cancer xenografts in parallel with pharmacokinetic profiling in rats and dogs to assess bioavailability.