Abstract 6706: An anti-claudin 18.2/CD3 bispecific antibody for the treatment of claudin 18.2 positive gastric cancer

Abstract The claudin18. 2 (CLDN18. 2) protein shows four transmembrane domains (TMDs) with two extracellular loops (ECL), ECL-1 and ECL-2. It is a highly selective biomarker with limited expression in normal tissues and often exhibits abnormal expression during the occurrence and development of various primary malignant tumors. The specific expression pattern supports the notion that CLDN18. 2 is a distinctive molecule for targeted therapy in various cancers, particularly gastric and pancreatic cancers. Various drugs targeting CLDN18. 2, including monoclonal antibodies, ADCs, CAR-T, and bispecific antibodies, have also entered clinical trials. As of this writing, there are currently no commercially available products worldwide that specifically target CLDN18. 2. However, Zolbetuximab (IMAB362) has successfully reached the Phase III end point, indicating positive clinical outcomes and establishing CLDN18. 2 as a promising cellular and antibody therapeutic option. Here, we describe LNF2007, an anti-CLDN 18. 2/CD3 bispecific antibody that can redirect CD3+ effector T cells to CLDN18. 2+ tumor sites, resulting in the activation of T cells and subsequent killing of target cells. The design of LNF2007 focuses on selecting a relatively weak and reasonable affinity to CD3, accompanied by the suppression of Fc-mediated effector functions. This aim is to minimize off-target toxicity and maximize therapeutic efficacy. In vitro data demonstrate that LNF2007 binds more strongly to CLDN18. 2+cells than to CD3+ cells. LNF2007 exhibited good dose-dependent activation and cytotoxicity against engineered cell lines BXPC3-hCLDN18. 2-Luc and CHOK1-hCLDN18. 2-Luc, which are positive for CLDN18. 2 expression. In the in vivo pharmacodynamics assay, LNF2007 also demonstrated superior efficacy in the humanized NUGC4-CLDN18. 2 model and BxPC3-CLDN18. 2 model. Furthermore, a 4-week repeated dose (up to 1 mg/kg) toxicity study in cynomolgus monkeys showed that LNF2007 was safe and well tolerated. In vitro cytokine release was lower in the LNF2007 group than that in the AMG 910 and AZD5863 (two another anti-claudin18. 2/CD3 bispecific antibody) groups. In conclusion, the novel anti-CLDN18. 2 × anti-CD3 bispecific antibody LNF2007 demonstrates similar efficacy to AMG 910 and AZD5863 and is safer. LNF2007 provides a promising therapy for claudin 18. 2-positive cancer patients. Taishan Industry Leading Talents Project of Shandong Province was a sponsor of this research. Citation Format: Lili Zhao, Guimin Zhang, Zhong Liu, Jinhua Xu, Lizhi Zhao, Guangyan Li, Bin Li, Zhongsong Zhu, Wei Peng, Yuqiang Zhu, Zhaowei Chen, Zhenyu Li. An anti-claudin 18. 2/CD3 bispecific antibody for the treatment of claudin 18. 2 positive gastric cancer 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 6706.