Abstract 6353: AM105: A novel bispecific antibody with Anti 4-1BB affibodies and EGFR antibody

Abstract T cell engaging bispecific antibodies have emerged as promising treatments for hematologic malignancies. While most antibodies are CD3-based, offering therapeutic benefits, they are often associated with severe side effects and limited efficacy in solid tumors. To address these challenges, we present AM105, a groundbreaking anti 4-1BB affibodies based bispecific antibody designed to target EGFR. We carefully engineered AM105 with distinct binding affinities for EGFR (KD = 1.8 nM) and 4-1BB (KD = 60 nM), favoring EGFR binding. Affibody specificity was confirmed through a cross-reactivity test with proteins of TNF-receptor superfamily and 21 cell lines expressing 4-1BB or not. In cytotoxicity assays, AM105 exhibited superior tumor cell killing compared to cetuximab, particularly in EGFR-expressing cell lines. Notably, AM105 displayed remarkable efficacy in cell lines harboring RAS and/or BRAF mutations, traditionally unresponsive to EGFR-targeting treatments. In vivo experiments utilizing humanized 4-1BB mice demonstrated AM105's exceptional tumor cell elimination compared to cetuximab. The anti-tumor effects persisted even in the face of new tumor cell introductions, suggesting the induction of T cell memory function. Our findings collectively establish AM105 as a potent therapeutic agent with strong anti-tumor T cell activity. The unique 4-1BB based Affibodies (AffiMab format) of AM105 holds promise for addressing the limitations of current bispecific antibodies, positioning it as a potential breakthrough in cancer immunotherapy. Citation Format: Dong-Wook Kim, Hyun-Jong Lee, Seong Yeol Kim, Min Yoon, Youngha Lee, In-Sik Hwang, Yoon Lee, Jong-Hoon Kim, Jong-Seo Lee. AM105: A novel bispecific antibody with Anti 4-1BB affibodies and EGFR antibody [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(6_Suppl):Abstract nr 6353.