Abstract 5794: DX2206, a humanized monoclonal antibody that targets IL1RAP, exhibits potent inhibition of IL-1 pathways and activities against tumors in vitro and in vivo

Abstract Background: The Interleukin-1 Receptor Accessory Protein (IL1RAP) is found on cancer cells, stromal cells, and infiltrating immune cells within the tumor microenvironment (TME) of various cancers. It plays an important role in tumor development at various stages by activating IL-1 superfamily pathway, thus become an interesting target in cancer treatment. Methods: We investigated the correlation between IL1RAP and tumor prognosis through the analysis of the public dataset. An antibody discovery campaign was performed and DX2206 was identified as the top clone against IL1RAP. Epitope of DX2206 was determined by examining the binding of DX2206 with different IL1RAP structural domains and in silico analysis. The activities of DX2206 against IL-1, IL-33, and IL-36 were examined using multiple assays with HEK293-Luc reporter cells, primary HUVEC cells, and A431 human skin squamous carcinoma cells. In vivo efficacy was evaluated in a CDX model. Results: Based on public data, IL1RAP is overexpressed in various types of cancer patients compared to healthy individuals, and high expression of IL1RAP is associated with poor prognosis in multiple cancer types. Furthermore, high expression of the members of the IL-1 superfamily, such as IL1RAP, IL-1, and IL-36, are negatively correlated with pan-Cancer OS. Our epitope analysis indicated that DX2206 binds to a unique epitope within IL1RAP domain 2. In vitro assays demonstrated that DX2206 inhibited the activities of all three pathways, IL-1, IL-33, and IL-36, with sub-nanomolar IC50s. Simultaneously, it induced a potent ADCC effect in the tumor killing assay. Finally, in a CDX model, DX2206 significantly inhibited tumor growth in vivo. Conclusions: We discovered a potent antagonist antibody, DX2206, that binds to a unique epitope of IL1RAP, inhibits all three pathways of signaling, and demonstrates in vitro and in vivo activities against tumors. Considering these characteristics, DX2206 emerges as an outstanding preclinical candidate for cancer therapy. IND enabling study was ongoing to expedite the candidate into clinic. Citation Format: Qinghao Liu, Yaqi Ru, Yan Jiang, Huimin Li, Wenbo Li, Lan Yang, Qian Shi. DX2206, a humanized monoclonal antibody that targets IL1RAP, exhibits potent inhibition of IL-1 pathways and activities against tumors in vitro and in vivo abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5794.