Abstract 6352: Combination treatment with recombinant murine IL-12 and anti-PD-1 antibody enhanced anti-tumor efficacy through the activation of cytotoxic T cell response

Abstract

Abstract Introduction: Immune checkpoint inhibitors (ICIs) are widely used in cancer therapy. Among them, anti-PD-1 antibodies are the most used and have been approved by FDA for the treatment of many types of cancer (1). In our previous studies, combination of anti-PD-1 antibody with IL-12 demonstrated significant synergistic effect on tumor growth inhibition. The elevation of IFN-γ mRNA expression suggested the potential roles of CD8 T cells and NK cells in this process. In this study, we used two syngeneic mice tumor models to investigate the mechanisms of synergistic effect by the combination of IL-12 and anti-PD-1 antibody. Methods: We used syngeneic mice tumor models with mice cancer cell lines CT-26 and MC-38. The mice inoculated with tumor cells and were treated until tumors grew to 100 mm3. The mice were divided into three groups to receive the treatment, including rmIL-12 alone, anti-PD1-antibody alone, and the combination of rmIL-12 and anti-PD1-antibody (BIW x 3 weeks). At the end of the study, the mice were sacrificed and tumor resection and splenectomy were performed. The tumor infiltrating lymphocyte subpopulations within the tumor microenvironment were analyzed by flow cytometry and gene expression profile by RNA Seq. Results: The combination of rmIL-12 and anti-PD-1 antibody significantly inhibited tumor growth compared to the treatment with rmIL-12 and anti-PD-1 antibody alone. The combination group demonstrated more CD8+ T cell in the tumor microenvironment via flow cytometry. In addition, RNA Seq showed the combination group increased CD8+ T cells, NK cells, and Th1 populations. The levels of cytotoxicity related genes (IFN-γ, Granzyme B, Perforin) were also higher in combination group. Conclusion: Combination of rmIL-12 and anti-PD-1 antibody increased immune cells infiltration in the tumor microenvironment and enhanced anti-tumor response suggesting the potential of this combination for cancer treatment. Citation:(1). Watson, G.A. et al. (2020) “Novel strategies in immune checkpoint inhibitor drug development: How far are we from the paradigm shift?,” British Journal of Clinical Pharmacology, 86(9), pp. 1753-1768. https://doi.org/10.1111/bcp.14355. Citation Format: Yeng-Jey Yang, Pei-Yi Tsou, Shiuh-Dih Chou, Meng-Na Lee, San-Chi Chen. Combination treatment with recombinant murine IL-12 and anti-PD-1 antibody enhanced anti-tumor efficacy through the activation of cytotoxic T cell response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6352.