Abstract 1451: AN3025: A novel anti-human TNFR2 antibody that exhibits immune activation and strong anti-tumor activity in vivo

Abstract

Abstract Background: The unique biology and expression pattern of tumor necrosis factor receptor-2 (TNFR2) make it an attractive therapeutic target for immuno-oncology. TNFR2 highly expresses on a subset of regulatory T cells (Tregs) and MDSCs within tumor microenvironment that can activate these cells through nuclear factor kappa B (NF-kB) pathway. TNFR2+ Treg has been shown to be most suppressive among all Treg populations in tumor. On the other hand, TNFR2 is also abundantly expressed on the surface of many human tumors. TNFR2 blocking antibody is expected to relieve TNFR2-mediated immunosuppression and inhibit TNFR2-expressing tumor cell survival. AN3025 is a novel humanized IgG1 (variant) anti-hTNFR2 antibody under preclinical development. The immunomodulatory and anti-tumor activity of AN3025 were evaluated both in vitro and in vivo. Materials and methods: AN3025 was generated through rabbit immunization followed by phage display, then humanized by CDRs grafting. The binding affinity and specificity were studied by ELISA and FACS. The ability of AN3025 to mitigate TNF/TNFR2 signaling pathway was characterized using TNFR2 overexpressing Jurkat cell line in vitro. The in vivo anti-tumor activity was evaluated in TNFR2 humanized mouse model bearing MC38 tumor. The tumor samples from control and AN3025 treated mice were taken for further FACS and RNA seq analysis. Results: AN3025 binds to the extracellular domain of human TNFR2 with sub-nanomolar affinity and specificity. It cross-reacts with cynomolgus TNFR2 with similar affinity, but not with mouse or rat TNFR2. Mechanistically, AN3025 partially competes with TNFα for binding to TNFR2 receptor and inhibits TNFα induced hTNFR2 overexpressing Jurkat cell death, however it lacks of agonist activity towards TNFR2 even in the presence of hFC crosslinking. In vivo AN3025 significantly inhibits MC38 tumor growth as a monotherapy in hTNFR2 mouse model, while no impact on body weight. Subsequent FACS analysis suggests decreased Tregs% in AN3025 treated tumor. RNA seq suggests immune activation such as increased IFN-gamma and Granzyme expression. In addition, AN3025 enhances anti-tumor efficacy of mPD-1 antibody in a combination study. Conclusions: AN3025 is a novel anti-hTNFR2 antibody and demonstrates immunomodulatory activity and potent anti-tumor efficacy in vivo, supporting its clinical development for the treatment of human cancers. Citation Format: Yonglin Chen, Manxue Jia, Sherry Xu, Yanhui Zhao, Eric Chan, Meng Zhang, Emma Chen, Yi Zhang. AN3025: A novel anti-human TNFR2 antibody that exhibits immune activation and strong anti-tumor activity in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1451.