Although oncolytic viruses have shown clinical efficacy for local treatment of cancerous tumors, the ability to induce immune-mediated regression to visceral lesions is not robust. Immune checkpoint modulation has been efficacious in a fraction of cancers associated with an inflamed microenvironment but is associated with toxicity due to nonspecific T-cell activation. Therefore, combining these two strategies has the exciting potential to be an effective cancer therapy. Oncolytic virus can be genetically modified to decrease pathogenicity to normal cells and to increase their lytic potential and ability to stimulate antitumor immunity, thus improving the risk-benefit ratio for cancer patients. Oncorus oHSV (ONCR) are novel oncolytic herpes simplex virus type-1 vectors developed for the treatment of solid tumors. ONCR utilizes a unique conditional-lethal strategy in which tissue-specific miRs binding sites are inserted into early genes essential for viral replication and in the neurovirulence gene ICP34.5. This strategy curtails viral replication in normal cells, including neurons, and limits the expression of g34.5 to tumor cells, thus promoting potent viral replication in presence of type I interferon. Fifteen immunostimulatory transgenes and combination thereof were systematically evaluated in dual flank syngeneic mouse tumor models to test both for oncolysis and abscopal efficacy on the contralateral noninjected tumor. Among the selected transgenes, IL-12 was found to elicit the most potent efficacy on the ipsilateral and contralateral tumors. We demonstrated that the replication of ONCR and the expression of IL-12 was limited to the injected tumors. By contrast, induction of systemic immunity as assessed by IFNg production in contralateral tumors and in plasma was observed. ONCR expressing IL-12 elicited efficacy in multiple subcutaneous and metastatic models. Additional payloads designed to stimulate antigen presentation, recruitment of immune cells and inhibition of tumor immune suppression were identified as further enhancing IL-12 activity. Data supporting the selection of a suite of payloads cloned into a single ONCR vector will be presented. ONCR represents a new class of oncolytic virus that promote antitumor responses through a multiprong mechanism of action dependent on selective tumor cell killing, the induction of systemic antitumor immunity and reversion of immune suppression.

Citation Format: Lorena Lerner, Edward M. Kennedy, Terry Farkaly, Allison Colthart, Caity Montagna, Prajna Behera, Judith Jacques, Peter Grzesik, Jennifer Lee, Agnieszka Denslow, Jacqueline Gursha, Brian Haines, Michael Ball, Daniel Wambua, Cecilia Kwong, Lingxin Kong, Michael Paglia, Laura Viggiano Salta, Lorenz Ponce, Caroline Webb, Mitchell Finer, Christophe Quéva. microRNA attenuated oHSV-1 armed with multiple immunomodulatory payloads mediates robust and selective antitumor immune response in preclinical tumor models [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B23.