ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is a deadly form of pancreatic cancer with limited treatment options and a low overall survival rate. Oncolytic viruses, particularly vesicular stomatitis virus (VSV), have shown promise in treating therapy-resistant cancers, including PDAC; however, concerns about neurotoxicity and safety have hindered its clinical application. We have developed a novel oncolytic vector platform, VMG, using virus- directed evolution technology, which replaces VSV glycoprotein with the glycoprotein of the Morreton virus and incorporates the M protein of the Malpais spring virus. VMG has demonstrated tumor immune modulation in murine models and a non-neurovirulent and non-pathogenic profile in toxicology studies. The dense stroma in PDAC, consisting of hyaluronic acid and collagen, promotes tumor aggressiveness and resistance to therapies. Our proposed high-risk, high-reward strategy involves VMG-mediated oncolysis and the expression of hyaluronidase and collagenase enzymes to break down the stroma, which will serve to enhance viral biodistribution and immune cell infiltration into the tumor. This dual-stroma disruption strategy aims to improve tumor control and patient survival. Furthermore, VMG-induced cancer cell death could enhance tumor immunogenicity, leading to better recognition and destruction by cytotoxic T lymphocytes. We have also explored the potential of encoding SER, a novel proteolytic enzyme, into VMG to break down the stroma and induce immune cell infiltration. This exciting development offers new avenues for effective PDAC treatment as a standalone approach or in combination with immune checkpoint inhibitors. Another high-risk, high-reward strategy we plan to employ involves VMG vectors expressing murine major histocompatibility complex alloantigens (H-2Kk, H-2Kd) in PDAC cells. This alloantigen expression is expected to trigger a potent allogeneic immune response, leading to tumor rejection. These innovative modifications will enhance drug bioavailability, tumor immunogenicity, and immune response against PDAC cells, potentially improving treatment efficacy in preclinical studies and human patients. Our research addresses critical gaps in PDAC therapy and presents novel approaches to enhance oncolytic virotherapy for this challenging cancer type. This work holds significant potential to revolutionize cancer immunotherapy and improve patient outcomes in PDAC and other stroma-dense and cold tumors.

PUBLIC HEALTH RELEVANCE The tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense and anergic stroma that inhibits vascular perfusion, suppresses immune function, and reduces tumor permeability to drugs and immune cells. We propose developing and evaluating a novel oncolytic virus modified to selectively deliver stroma-degrading enzymes to enhance the expression of neoantigens and increase tumor immunogenicity as well as immune cell infiltration. Currently, advanced PDAC patients have limited treatment options; thus, this project will address a critical unmet need for more effective therapies.