Abstract 6717: Targeting mutant KRAS proteins with novel TCR-mimic fully human antibodies

Abstract Mutated KRAS proteins are ideal cancer targets, as they are expressed frequently and specifically in certain solid tumors. A large proportion of human colorectal cancer and pancreatic ductal adenocarcinoma express the tumor driver KRAS gene mutations G12V/G12D, but drugs targeting G12V/G12D are not available, revealing a huge unmet clinical need. While small molecules often fail to target the KRAS mutation G12V/G12D, T cell receptor-mimic (TCR-mimic) antibodies can specifically recognize KRAS mutations presented by human leukocyte antigen (HLA), opening up possibilities for targeting such intracellular antigens. Here, we discovered novel antibodies highly specific to G12V/HLA and G12D/HLA complexes by immunizing our proprietary RenTCR-mimicTM mice and using high-throughput Beacon-based screening. These TCR-mimic antibodies have higher affinities compared to endogenous TCRs, which may effectively reduce the possibility of tumor escape. Germline distribution analysis indicated their high sequence diversity, which suggests diverse epitope targeting. Although pancreatic cancer is extremely difficult to treat and has an extremely low KRAS mutant peptide-HLA complex density on the cell surface, our TCR-mimic antibodies exhibited potent in vitro tumor lysis activity when assembled into CD3 T cell engagers. Furthermore, these antibodies demonstrated convincing off-target safety. Together, our results indicate promising therapeutic potential of these KRAS mutation-targeted TCR-mimic antibodies for the treatment of solid tumors. Citation Format: Jun Du, Wanbo Tang, Xin Jiao, Limin Zhao, Pengfei Du, Yuqi Zhang, Jian Bao, Han Chen, Chaoshe Guo, W. Frank An. Targeting mutant KRAS proteins with novel TCR-mimic fully human antibodies [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 6717.