Abstract 6551: Exploring oncolytic viral therapy to target osteosarcoma

Abstract Osteosarcoma (OS) is a mesenchymal neoplasm. OS makes up approximately 3% of all malignancies in children. The mortality rate has not changed in the last few decades; therefore, the development of advanced cancer therapies is essential. We hypothesize that next-generation conditionally replicative oncolytic virus with an armed anti-PD1 HcAb will lyse the OS cells and initiate the immune response against tumor cells in the tumor microenvironment.The purpose of the study is to evaluate the oncolytic activity and production/ secretion of anti-PD1 Hcab by conditionally replicative Canine adenovirus armed with anti-PD1 Hcab (CAV 2 AU M3). We have infected canine OS cell lines viz D17-GLP, CF11-GLL, MCKOS and D22-GLP with CAV2 AU M3 and measured its cytotoxicity by performing cell viability assay (Luciferase assay) and cytotoxicity assay (LDH assay). To assess whether the virus can stimulate an immune response or not, we performed an immunogenicity assay (ATP assay). To evaluate the secretion and expression of anti-PD1 HcAb we have performed western blot. Flow cytometry was done to confirm the functionality of anti-PD1 Hcab i.e binding of anti-PD1 HcAb to PD1 receptors and inhibition of PD1 and PDL1 interaction. We have found that CAV2 AU M3 is lytic in OS cell lines (D17-GLP, CF-11-GLL, and MCKOS) in both 2D (Monolayers) and 3D (Tumor spheroids) cell cultures and it also produced and secreted anti-PD1 HcAb, which binds to PD1 receptor efficiently and inhibited the interaction between PD1 and PDL1. We concluded that CAV2 AU M3 is a potent armed oncolytic virus that can lyse and kill OS cells and produce functional anti-PD1 HcAb. Citation Format: Sumbul Khan, Terri Higgins, Isabella Shimko Lofano, Payal Agarwal. Exploring oncolytic viral therapy to target osteosarcoma [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 6551.