Abstract LB353: Repurposing varicella zoster virus and human papillomavirus vaccines for local immunotherapy against solid tumors

Abstract Local immunotherapy against solid tumors is considered a viable approach to stimulate the tumor microenvironment (TME) and anti-tumor immunity. We assessed in situ vaccination with licensed subunit vaccines to leverage preexisting anti-vaccine immunity in the TC-1 tumor model expressing HPV16 viral oncogenes E6 and E7. We chose Shingrix, a VZV vaccine containing the glycoprotein E (gE), and Gardasil-9, an HPV vaccine containing L1 virus-like particles (VLP), to preferentially induce CD4 and CD8 T cell responses, respectively. Intratumoral (IT) injection of Shingrix in Shingrix prevaccinated mice led to complete regression in 20% to 50% of treated mice and elicited CD8 T cell responses against the viral oncoprotein E7. IT injection of an MHC-II-restricted gE peptide with polyI: C also led to durable remission, suggesting that gE-specific CD4 T cells played a significant role in tumor control. In contrast, IT injection of Gardasil-9 in Gardasi-9 prevaccinated animals did not delay tumor growth. However, IT injection of an MHC-I-restricted L1 peptide with Shingrix consistently led to complete remissions perhaps by overcoming preexisting antibodies against native HPV VLP which appeared to inhibit the cross-presentation of VLP derived antigens. TME analysis showed that IT injection of Shingrix with Gardasil-derived peptide induced IFN-gamma, TNF-alpha and CXCL9. This treatment also dramatically reshaped the immune cell infiltrate causing the recruitment of T cells and neutrophils and the decrease of tumor-associated macrophage and eosinophils. We are investigating now how these changes may contribute to tumor clearance and epitope spreading against tumor-derived antigens. Finally, IT injection of Shingrix and a E7 viral neoantigen peptide led to the eradication of all primary injected and abscopal tumors. Our results indicate that the ability of Shingrix to induce exceptionally strong Th1 responses makes it a versatile component for in-situ vaccination which can be combined with peptides derived from licensed vaccines or tumor antigens. Because this approach relies on relatively low cost existing vaccines and inexpensively manufactured minimal CD8 restricted peptides, it has the potential for a broadly applicable cancer immunotherapy strategy for use in resource-constrained settings. The approach is currently being evaluated in a phase I clinical trial in companion dogs with spontaneously arising cancers. Citation Format: Nicolas Cuburu, Shiv K. Sethi, Claire E. Bradley, Lukas Bialkowski, Cynthia D. Thompson, Douglas R. Lowy, John T. Schiller. Repurposing varicella zoster virus and human papillomavirus vaccines for local immunotherapy against solid tumors abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (7Suppl): Abstract nr LB353.