Abstract 4156: BI-1808 - a first in class ligand-blocking αTNFR2 antibody for cancer immunotherapy

Abstract The pleiotropic TNF-α:TNFR axis plays a central role in immune regulation. While the cellular expression of TNFR1 is broad, TNFR2 expression is mainly restricted to immune cells. The therapeutic potential of targeting TNFR2 for cancer treatment has been previously indicated and to gain further insight, we generated a wide panel of TNFR2-specific antibodies using the n-CoDeR F.I.R.S.T™ target and antibody discovery platforms. We identified antibodies against mouse or human TNFR2 that could block TNF-α binding and showed potent anti-tumor activity in several immune-competent models, both as single agent and in combination with anti-PD1. The mechanism-of-action was shown to be FcγR dependent and likely mediated through a combination of intra-tumor T reg depletion, CD8+ T cell expansion and modulation of innate immune cells e.g. neutrophils and myeloid cells. Toxicological studies of the human lead-candidate BI-1808 in non-human primates (NHP) demonstrated very good tolerability at doses up to 200 mg/kg, and in vitro studies with human cells showed no signs of harmful cytokine release. Furthermore, in vivo studies using immune competent mouse cancer experimental models showed a clear relationship between dose, receptor occupancy (RO) and efficacy. In both murine models and in the NHPs, soluble TNFR2 was clearly modulated by the treatment and closely correlated with RO. In addition, several changes in the immune cells (e.g. T cells and neutrophils) in the blood compartment were observed. Since January 2021, BI-1808 is evaluated in an ongoing Phase I/IIa trial. Similar to the preclinical studies, correlations between dose, RO and soluble TNFR2 has been clearly observed in the patients. In addition, and consistent with TNF-α:TNFR biology being conserved across the species, modulations of T cell and neutrophil numbers are also paralleled between the patients, NHPs and mice, increasing the likelihood of successful clinical translation of our findings. Citation Format: Linda Mårtensson, Kirsty Cleary, Petra Holmkvist, Mathilda Kovacek, Carolin Svensson, Monika Semmrich, Therese Blidberg, Mimoza Demiri, Osman Dadas, Marie Borggren, Vici Pitic, Sean H. Lim, Stephen A. Beers, Susanne Gertsson, Kristoffer S. Rohrberg, Ingrid Karlsson, Andres McAllister, Mark S. Cragg, Björn Frendeus, Ingrid Teige. BI-1808 - a first in class ligand-blocking αTNFR2 antibody for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4156.