Abstract 7315: Engineering and characterization of novel T cell engagers (TCEs) directed against colorectal cancer-associated antigens (CEACAM5, CDH17)

Abstract Colorectal cancer (CRC) is one of the most prevalent and deadliest oncological diseases worldwide. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and cadherin-17 (CDH17) have been shown to be selectively expressed in colorectal tissues, and their level of expression and/or co-expression are significantly up-regulated in malignant diseases. Various experimental therapeutic modalities addressing these TAA targets are currently under active exploration. In this study, we engineered several T cell engagers (TCEs) directed against these targets, in multiple molecular formats, such as TAA/CD3 (1+1), TAA/TAA/CD3 (bivalent or biparatopic, 2+1), and TAA1/TAA2/CD3 (trispecific, 1+1+1), and characterized these TCEs in a battery of assays, including binding, T cell activation and tumor cell-killing, production and developability, as well as anti-tumor efficacy in vivo in various animal models. ‘1+1’, ‘2+1’ bivalent, and ‘2+1’ biparatopic formats were designed and constructed for both CEACAM5/CD3 and CDH17/CD3 bispecific TCEs. A trispecific TCE, CEACAM5/ CDH17/CD3 (1+1+1) was also produced. The cell-binding, cytotoxicity, T cell activation and cytokine release mediated by these TCEs were investigated in vitro. The anti-tumor activity of these TCEs were examined in vivo in human PBMC-reconstituted immune-deficient mice implanted with human CEACAM5- and/or CDH17-expressed tumor xenografts. In these TCE molecules, each building blocks, i.e., αCEACAM5, αCDH17, and αCD3 antibodies, were designed and selected regarding their antigen binding affinity and specific epitope. These are followed by various designing of the molecular formats of the TCEs to ensure the balance of multiple parameters, including antigen/cell binding, T cell activation vs tumor cell killing, production and developability, etc. Our studies identified a CEACAM5/CDH17/CD3 trispecific TCE that was more potent than the bispecific TCEs in killing tumor cells, and was broadly effective in killing tumor cells that either express only CEACAM5 or CDH17, or both. The trispecific TCE was also more efficacious than the single-target based TCEs in inhibiting xenograft tumor growth in animal models. Taken together, these findings support further development of the CEACAM5/CDH17/CD3 trispecific TCE as a promising modality for the treatment of CRC patients. Citation Format: Jinxiu Hou, Liang Tian, Chenpeng Su, Rui Shen, Dandan Liu, Jiyuan Tian, Tingting Gu, Xiaoou Xu, Xiaoqian Chen, Lisha Dong, Chuan Chen, Yongxin Shang, Maowei Wang, Jian Peng, Zhenping Zhu. Engineering and characterization of novel T cell engagers (TCEs) directed against colorectal cancer-associated antigens (CEACAM5, CDH17) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7315.