Abstract 947: Engineering a synthetic oncolytic virus to overcome apoptotic resistance and induce immunogenic cell death in pancreatic ductal adenocarcinoma

Abstract Introduction: Oncolytic viruses, particularly vesicular stomatitis virus (VSV), combat cancer through tumor lysis and immune response enhancement. However, pancreatic ductal adenocarcinoma (PDAC) often resists apoptosis due to p53 mutations and overexpression of anti-apoptotic proteins. We developed an innovative VSV variant, VMG, incorporating the glycoprotein of the Morreton virus (MORV-G) to enhance safety, tumor targeting, and immune engagement. VMG was further engineered to encode a proprietary synthetic caspase-activating protein (VMG-apo), activating both intrinsic and extrinsic apoptotic pathways via ER stress and caspase activation. Methods: Experiments were conducted on three PDAC cell lines: HPAFII, HS766T, and Panc1. Viral cytotoxicity was analyzed using the xCELLigence system over 40 hours post-infection. Cells were infected at MOI of 1 and harvested at 15 HPI for proteomic analysis. Additional analyses included apoptosis/necrosis assays, calreticulin expression, and Western blotting. Results: Proteomic analysis revealed distinct responses across cell lines. In Panc1 cells, VMG-apo altered 74 genes, notably downregulating CD9, COL1A1, and NQO1, while inhibiting extracellular matrix remodeling. HPAFII cells showed changes in cell cycle regulation. Both cell lines exhibited strong CASP3 overexpression (fold change >5.60). The resistant HS766T line showed minimal changes. VMG-apo downregulated DAMP and PAMP-associated genes while promoting calreticulin release. Panc1 showed highest sensitivity, with significant cell death at 15 hours post-infection. HPAFII cells underwent primarily apoptosis, while HS766T remained resistant. Calreticulin expression decreased in Panc1 and HPAFII cell lines, while in HS766T remained the same as control. Western blot analyses detected caspase-3 but no cleaved caspase-3. Conclusions: The results provide insights into immunogenic cell death and apoptotic mechanisms in PDAC following VMG-apo treatment. The differential responses across cell lines underscore VMG-apo's therapeutic potential and complexity. The heterogeneous responses indicate the need for personalized strategies in oncolytic virotherapy. These findings advance the understanding of how oncolytic viruses can enhance both direct tumor cell death and anti-tumor immunity, offering a promising avenue for improving PDAC treatment outcomes. Citation Format: Aleksandra Cios,Khandoker Usran Ferdous,Mulu Z. Tesfay,Alicja Urbaniak,Bahaa Mustafa,Steven R. Post,Thomas J. Kelly,Martin J. Cannon,Alexei Basnakian,Omeed Moaven,Bolni Marius Nagalo. Engineering a synthetic oncolytic virus to overcome apoptotic resistance and induce immunogenic cell death in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 947.