Abstract 5621: The GPC3-targeting hYP7 antibody-based gamma/delta TCR-T cell therapy for overcoming antigen mutation and heterogeneity in liver cancer

Abstract Antigen mutation and heterogeneous expression remain major barriers to effective antibody- and chimeric antigen receptor (CAR)-based immunotherapies for hepatocellular carcinoma (HCC). Glypican-3 (GPC3) exhibits variable surface density and epitope alteration in advanced or recurrent HCC tumors. To address these clinically relevant obstacles, we developed a modular antibody-based γ/δ T-cell receptor (γδAbTCR) platform that integrates antibody specificity with intrinsic TCR-CD3 signaling to enhance tumor recognition under conditions of antigen variation. Using two GPC3 antibodies recognizing distinct epitopes (hYP7 and HN3), we generated four γδAbTCR constructs—hYP7-hYP7, hYP7-HN3, HN3-hYP7, and HN3-HN3—and evaluated their functional properties in primary human T cells. Among these, hYP7-hYP7 γδAbTCR-T cells demonstrated the strongest antigen binding and cytotoxic activity against Hep3B and other GPC3+ HCC models, particularly those with low or heterogeneous antigen density. In vivo, hYP7-hYP7 T cells showed superior tumor infiltration, persistence, and control of large, established xenografts compared with other configurations. Mechanistic studies revealed that the hYP7-hYP7 γδAbTCR architecture couples enhanced antigen-binding avidity with coordinated TCR-CD3 and CD30 signaling, leading to potent NF-κB and NFAT activation and rapid induction of caspase-mediated apoptosis in tumor cells. These findings establish hYP7-hYP7 as a lead γδAbTCR design that overcomes the limitations of antigen heterogeneity and mutation in liver cancer, providing a promising framework for next-generation T-cell therapies targeting liver cancer. Citation Format: Dan Li, Tianyuzhou Liang, Hsi-En Tsao, Zhijian Duan, Laura E. Hutchins, Madilyn Gaydos, Iris Yang, Elijah Edmondson, Xiaoshan Wang, Rui Zheng, Jing Zhou, Chin-Hsien (Emily) Tai, Jing Bian, Maggie Cam, Hongbing Zhang, Cheng Liu, Mitchell Ho. The GPC3-targeting hYP7 antibody-based gamma/delta TCR-T cell therapy for overcoming antigen mutation and heterogeneity in liver cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5621.