Abstract 1733: Wnt antagonists synergize with immune checkpoint inhibitors to enhance anti-tumor responses

Abstract

Abstract Aberrant Wnt signaling through overexpression or activating mutations in Wnt pathway proteins is responsible for the initiation and progression of numerous cancers. While enhanced Wnt signaling has been shown to play a major role in cancer stem cell biology, more recent studies have implicated Wnt in the development of resistance to anti-tumor immune responses. Here, we show that in various syngeneic murine tumor models, targeting Wnt signaling using the Fzd receptor monoclonal antagonist antibody, OMP-18R5 (vantictumab) or the pan-Wnt decoy receptor Fc fusion protein OMP-Fzd8-Fc (ipafricept) in combination with immune checkpoint inhibitors anti-CTLA-4 or anti-PD1 induce synergistic anti-tumor responses leading to decreased tumor volume and increased infiltration of activated CD8+ T cells into the tumor microenvironment. In addition, we show that combined Wnt and immune checkpoint inhibition decrease regulatory T cells (Tregs), enhance cytotoxic T cell activity and increase antigen presentation by APCs. More importantly, we demonstrate that anti-PD1 and the Wnt antagonists decrease immune suppressive myeloid cell populations, which may enhance therapeutic efficacy and anti-tumor responses. Therefore, these results suggest that co-targeting Wnt and immune checkpoint proteins may provide valuable opportunities for novel combination strategies for immunotherapeutic clinical development. Citation Format: Jenny Ross, Timothy Hoey, Ann Kapoun, John Lewicki, Austin Gurney, Christopher L. Murriel. Wnt antagonists synergize with immune checkpoint inhibitors to enhance anti-tumor responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1733.