Enhancement of the therapeutic effects of oncolytic vaccinia virus by using autologous and allogeneic cell-based delivery platforms.

Abstract

e15271 Background: Clinical trials with oncolytic viruses for cancer treatment have shown limited efficacy due to viruses’ rapid clearance by patients’ innate and adaptive immune systems. In a recent first-in-human clinical trial, we confirmed the safety and feasibility of our approach to enhance oncolytic vaccinia virus (OVV) delivery and improve tumor targeting by utilizing an autologous cell-based cell delivery system (auto-OVV). We also developed an allogeneic cell-based platform (SuperNova1c - SNV1c) aiming to protect and potentiate OVV’s antitumor effects in large patient populations. Methods: We evaluated the immunomodulatory potential of auto-OVV by an extensive time-course analysis of cytokines in patients’ plasma (Luminex profiling) and peripheral blood immune cells (flow cytometry). We also analyzed the ability of SNV1c to protect the OVV from antibody/complement inactivation in vitro and in vivo following intratumoral injection in various mouse tumors. The immune cell infiltrations of the injected tumors were also analyzed. Results: Therapy with auto-OVV induced a coordinated activation of cytokine, T cell and NK responses in patients as early as 1 day, peaking around 1-week and lasting for up to 1-month post treatment. Effective OVV amplification in cancer patients correlated with significant changes of multiple innate and adaptive immune parameters. Patient stratification into groups with transient versus persistent viral DNA was linked to opposing and mutually exclusive patterns of robust activation of NK versus T cell responses, respectively. SNV1c showed significantly enhanced protection of OVV in vitro and led to statistically significant tumor growth inhibition as compared to control non-treated tumors or to naked OVV-treated tumors. Importantly, local administration of SNV1c induced systemic therapeutic effects. Five days after SNV1c administration, tumor infiltrating lymphocytes from both treated and untreated tumors showed increased CD4 and CD8 T-cell infiltrations, decreased Tregs, and improved effector to Treg ratios, associated with tumor growth inhibition at both treated and untreated tumor sites. Conclusions: This study establishes the timeline of treatment-related immunological changes and identifies potential immunological correlates associated with the OVV persistence in vivo. We also demonstrate the ability of our cell-based platforms to protect and potentiate OVV by circumventing innate and adaptive immune barriers, resulting in enhanced oncolytic virotherapy.