Project Summary/Abstract Mutant forms of KRAS are a key driver in human tumors but remains refractory to therapeutic intervention despite over three decades of research. Clinical attempts to directly or indirectly inhibit KRAS function have both yielded unsatisfactory results. The difficulty for developing small molecule KRAS inhibitors has heightened the importance of alternative methods targeting the oncogene. One such strategy involves therapeutic nucleic acids, which make it possible to deplete target proteins that are intractable to conventional drug modalities. We have developed a novel form of nucleic acid therapeutics, termed pacDNA, that substantially enhances the antitumor activity of nucleic acid drugs by elevating in vivo stability, accelerating cellular uptake, and improving plasma pharmacokinetics and tumor accumulation, allowing a much lower dosage to be used compared to conventional methods. The pacDNA also suppresses nearly all side effects associated with traditional nucleic acid drugs by reducing unwanted nucleic acid-protein interactions. In this proposal, we aim to build upon our promising preliminary results, and gain deeper insights into the cell biology of the pacDNA with respect to cell uptake mechanism, intracellular trafficking, KRAS depletion and subsequent cell signaling, and demonstrate efficacy in KRAS-dependent non-small cell lung cancer cell lines and 3D models. In addition, we will study the primary pharmacology and antitumor activity of pacDNA in advanced preclinical lung cancer models including an orthotopic tumor model, a patient derived tumor model, and a syngeneic genetically engineered mouse model (GEMM), and perform initial in vivo safety and tolerability studies. The outcome of this project will be a safe and potent anti-KRAS agent that can be readily translated into clinical studies for non-small cell lung cancer and potentially additional cancer classes.