Abstract 944: Evaluation of oncolytic herpes simplex virus overexpressing granulocyte-macrophage colony-stimulating factor as a potential therapeutic against pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal and drug-resistant cancers. The 5-year overall survival (OS) for PDAC remains low at 12.8%, largely due to its advanced presentation stage that prevents curative resection, and due to a high tendency for recurrence. The PDAC tumor microenvironment (TME) is desmoplastic and highly immunosuppressive. Oncolytic viruses (OV) are known to transform the TME from ‘cold’ to ‘hot’ by increasing immune cell infiltration within the TME. The primary objective of this study is to investigate the potential of Herpes simplex virus (HSV-1), strain VC2, overexpressing granulocyte-macrophage colony-stimulating factor (GM-CSF), HSV-1 (VC2) GM-CSF, as a potential therapeutic agent in in vitro and in vivo models of PDAC. We will assess the intricate molecular mechanisms involved in the interaction between OV and PDAC TME and perform immunoprofiling. We hypothesize that the administration of HSV-1 (VC2) GM-CSF as a monotherapy or combination therapy will improve treatment outcomes via cytopathic effects (CPE) of OV against cancer cells and immunomodulation of PDAC TME by GM-CSF. We evaluated the effect of HSV-1 (VC2) GM-CSF on human MIA PaCa-2 (KrasG12C, Trp53R248W) and murine KPC (KrasG12D, Trp53R172H, and Cre control) PDAC cell lines. Both cell types showed notable CPE, including cell aggregation, rounding and eventual detachment, following treatment with HSV-1 (VC2) GM-CSF, in contrast to the effects observed with wild-type HSV-1 (VC2) or in uninfected controls after 24 h of viral exposure. The observed CPE was corelated with cell death using trypan blue staining. We determined the viral titers to be 9.6×107 pfu/ml for wild-type HSV-1 (VC2) and 1.2×107 pfu/ml for HSV-1 (VC2) GM-CSF. The infection of both human and murine PDAC cells lines with HSV-1 (VC2) GM-CSF at 0.1, 1.0 and 10 MOIs significantly increased the expression of proinflammatory markers (IL-10, COX-2, iNOS) and upregulated Fas ligand (FasL) and PD-L1 expression suggesting immunomodulatory activity. An orthotopic PDAC model in C57BL/6 mice has been established, providing a solid foundation for further research. Ongoing studies employing advanced 2D and 3D cell culture systems, including cell-derived spheroid co-cultures and patient-derived organoid models, along with preclinical evaluation in established orthotopic mouse models, will elucidate the therapeutic potential of HSV-1 (VC2) GM-CSF, both as a standalone treatment and in combination with anti-PD-L1 immunotherapy and Gemcitabine. Citation Format: Biplov Sapkota, Naveen Chintala Ramulu, Shilpa Thota, Rizwana Begum, Shreya Pokharel, Brent Stanfield, Dayanidhi Raman, Gus Kousoulas, Joseph Francis. Evaluation of oncolytic herpes simplex virus overexpressing granulocyte-macrophage colony-stimulating factor as a potential therapeutic against 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 944.