Abstract C015: Bioengineering and characterization of an oncolytic Vaccinia virus platform for tumor localized lentiviral vector production

Abstract Background: Oncolytic viruses (OVs) are emerging immunotherapeutic agents notably known for their tumor selective replication, ability to deliver therapeutic transgenes, induction of immunogenic cell death and stimulation of antitumor immunity. Despite these advantages, OVs have shown limited progress as monotherapies, reflecting the need to explore combination therapies. As such, more recent studies in the OV field suggest that combination therapies are demonstrating more success. Among the various OV platforms in development, Vaccinia virus (VV) is a well-characterized virus, containing a large DNA genome which can accommodate multiple insertions. Objective: Given the challenges faced by OVs as a monotherapy, the goal of this project is to generate a hybrid viral vector with the goal of enhancing VV based cancer therapy. Methods: VV was sequentially engineered by virus infection followed by transfection of plasmids encoding the lentivirus components (packaging, envelope glycoprotein, and lentivirus genome) containing homology arms for insertion into non-essential VV loci. Western blot and whole genome sequencing were used to confirm the presence of each component form engineered VV. Results: We have established and validated a VV-based platform for production of lentivirus particles in proof-of-concept studies. We successfully produced gfp and cre containing lentivirus particles for transduction of target cells. Electron microscopy performed on supernatant and infected cells revealed the presence of intracellular VV particles and lentivirus particles released into the culture supernatant. Currently, murine studies are in progress to determine platform feasibility in vivo. Conclusion: The multiple modes of VV-mediated tumor cell death combined with delivery of lentivirus particles for delivery of therapeutic genes to tumor cells or immune cells in the tumor microenvironment may represent a promising therapeutic strategy for improving immune recognition of the tumor. Citation Format: Jaahnavi Dave, Carolina Solange. Ilkow, John Cameron. Bell. Bioengineering and characterization of an oncolytic Vaccinia virus platform for tumor localized lentiviral vector production [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr C015.