{
  "abstract": "Background Colorectal cancer (CRC) represents a major unmet clinical need. Cadherin-17 (CDH17) is expressed in the majority of CRC, associated with poor prognosis and reduced survival. In normal intestinal tissue, CDH17 is restricted to tight junctions, but its aberrant overexpression and altered localization in tumors make it an attractive target. The success of T cell engagers (TCEs) in solid tumors has been limited by a narrow therapeutic window, due to the scarcity of tumor-specific targets, the need to fine-tune CD3 arm, and limited tumor penetration. Targeting membrane-proximal domains of CDH17 using biparatopic TCEs with affinity-tuned CD3 arm may enhance tumor specificity and therapeutic index in CRC.Methods To generate a diverse panel of VHHs with distinct epitope coverage and variable affinities, we immunized multiple Camelidae species and isolated VHHs using our proprietary VHHMAb® platform. Using an in-house AI-driven design, we engineered and optimized biparatopic TCEs incorporating VHHs targeting distinct CDH17 extracellular domains and anti-CD3 binders with variable T cell binding affinities and activation potencies. Multiple linker formats and domain orientations were systematically evaluated to identify optimal molecular configurations. Candidate TCEs were characterized in vitro for target cell binding, T cell-dependent cellular cytotoxicity (TDCC), and cytokine release. In vivo anti-tumor activity was assessed in humanized mouse models.Results We identified a broad panel of humanized anti-CD3 VHHs with distinct epitopes, diverse affinities, T cell activation and TDCC activities. In parallel, we isolated multiple domain-specific anti-CDH17 VHHs, enabling AI-powered rational design of biparatopic TCEs. These VHHs cross-react with human, cynomolgus, and murine CDH17, facilitating preclinical and translational development. The lead biparatopic CT224 (CDH17×CD3) TCE candidates exhibited potent tumor cell killing with minimal background T cell activation and low cytokine release in PBMC assays, indicating a favorable efficacy and safety profile. Biparatopic CT224 outperformed monospecific comparators in TDCC assays and exhibited IgG-like pharmacokinetics in mice. In humanized mouse models, CT224 achieved superior tumor growth inhibition compared to benchmark TCEs. Furthermore, CT224 demonstrated good developability characteristics, including high expression yield and purification purity, low polyreactivity, and excellent thermal stability—supporting its advancement toward clinical development.Conclusions CT224, a novel biparatopic VHH-based CDH17×CD3 TCE, combines potent antitumor efficacy with a favorable safety profile and small molecular size for improved tumor penetration—addressing key limitations of TCEs in solid tumors. Its cross-species reactivity, favorable pharmacokinetics, and strong developability profile support ongoing preclinical development and potential clinical translation as a first-in-class TCE for CRC.",
  "authors": [
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Toya N Baral"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Weihong Wang"
    },
    {
      "affiliations": [
        "Shanghai Cell Therapy Group Co., Ltd., Shanghai, China"
      ],
      "name": "Jia Yu"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Huiyuan Tang"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "John Lee"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Leo Ng"
    },
    {
      "affiliations": [
        "Shanghai Cell Therapy Group Co., Ltd., Shanghai, China"
      ],
      "name": "Jing Yu"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Yong Wang"
    },
    {
      "affiliations": [
        "Shanghai Cell Therapy Group Co., Ltd., Shanghai, China"
      ],
      "name": "Jiaguo Li"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Xinhao Wang"
    },
    {
      "affiliations": [
        "Shanghai Cell Therapy Group Co., Ltd., Shanghai, China"
      ],
      "name": "Weimin Zhu"
    },
    {
      "affiliations": [
        "Shanghai Cell Therapy Group Co., Ltd., Shanghai, China"
      ],
      "name": "Qijun Qian"
    },
    {
      "affiliations": [
        "Chantibody Therapeutics, Inc., Menlo Park, CA, USA"
      ],
      "name": "Wenfeng Xu"
    }
  ],
  "title": "958 CT224: a novel biparatopic VHH-based CDH17×CD3 T cell engager optimized for safety and efficacy in colorectal cancer",
  "uid": "1181b613-a5d2-5bdc-964e-aad202eb58f8"
}