Abstract 3299: Development of ONCR-788, a synthetic oncolytic virus based on Seneca Valley virus for the treatment of neuroendocrine tumors

Abstract Oncolytic viruses (OVs) are an emerging therapeutic approach for the treatment of cancer. Clinical benefit has been demonstrated for intratumoral administration. Still, the therapeutic effectiveness of intravenous delivery has been limited by neutralizing antibody responses against the virus. To circumvent this limitation, we developed Synthetic RNA viruses, a novel approach for intravenous and repeated administration of OVs, consisting of a viral RNA genome (vRNA) formulated within lipid nanoparticles. Systemic administration of ONCR-788, the Synthetic RNA virus drug candidate encoding the vRNA of Seneca Valley virus (SVV), led to potent anti-tumor efficacy, even in the presence of OV neutralizing antibodies in the bloodstream. After a single intravenous administration of ONCR-788, we demonstrated vRNA delivery, viral replication, spread, and lysis of tumor cells. Robust anti-tumor efficacy was observed across diverse neuroendocrine tumor models, including tumor CDX and PDX xenografts, lung orthotopic, and GEMM-derived models. In a syngeneic model, ONCR-788 stimulated both tumor lysis and modulation of the tumor microenvironment. Enhanced T cell recruitment and activation, increased expression of PD-L1 on tumor cells and myeloid cells, and M2 to M1 macrophage conversion were observed. Combination of ONCR-788 with anti-PD-1 resulted in improved anti-tumor activity versus the monotherapy arms. Altogether, ONCR-788 provides an innovative approach that enables repeat intravenous administration of viral immunotherapy. Citation Format: Edward M. Kennedy, Agnieszka Denslow, Jacqueline Hewett, Lingxin Kong, Ana De Almeida, Jeffrey Bryant, Jennifer S. Lee, Judy Jacques, Sonia Feau, Hayes Hayes, Elizabeth L. McMichael, Daniel Wambua, Sanmit Adhikari, Jessica Deterling, Matthew Scott, Brian H. Haines, Mitchel H. Finer, Ted Ashburn, Christophe Quéva, Lorena Lerner. Development of ONCR-788, a synthetic oncolytic virus based on Seneca Valley virus for the treatment of neuroendocrine tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3299.