IF = 81.2, Breaking the Cellular Barrier: A Novel TCR-Mimic Nanobody Enables Precise Targeting of Intracellular Tumor Antigens

New progress has been made in TCR-mimic nanobody–based tumor immunotherapy.

Research team led by Xiaoling Lu from Guangxi Medical University published their findings in “Signal Transduction and Targeted Therapy” (IF = 81.2, top journal).

This study provides new insights into the development of a novel TCR-mimic nanobody-based bispecific T cell engager platform for targeting intracellular tumor antigens and enhancing antitumor immune responses.

Traditional bispecific T cell engagers (BiTEs) based on single-chain variable fragments (scFvs) face challenges such as structural instability, aggregation tendency, and manufacturing difficulties. Moreover, they are limited to targeting extracellular antigens, which represent less than 30% of tumor proteins, leaving the majority of intracellular or secreted antigens inaccessible.

Recent advances in T cell engager protein engineering have introduced nanobodies (Nbs) as promising alternatives to scFvs. Nbs offer advantages including small size, high affinity, excellent tissue penetration, and easy genetic modification. The research team previously developed nanobody-based bispecific and trispecific T cell engager platforms, which demonstrated significant antitumor activity in preclinical models. However, their dependence on cell surface antigens limits therapeutic applications and raises concerns regarding on-target/off-tumor toxicity caused by antigen expression in normal tissues. Therefore, innovative immunotherapy strategies are needed to overcome these limitations and expand the range of targetable tumor antigens.

Peptide–major histocompatibility complex (pMHC) molecules can be recognized by T cell receptors (TCRs) on CD8+ cytotoxic T cells, initiating immune responses. Among these targets, Wilms tumor 1 protein (WT1) and glypican-3 (GPC3) are considered ideal candidates due to their high expression in specific solid tumors or hematological malignancies and low expression in normal tissues. To target these intracellular antigens, researchers have developed TCR-mimic antibodies (TCRm) that recognize intracellular tumor antigens presented as pMHC complexes. TCRm nanobodies targeting HLA-A2/WT1126-134 and HLA-A2/GPC3144-152 complexes have been successfully generated, demonstrating selective and efficient targeting capabilities. However, the therapeutic efficacy of TCRm-based approaches is often limited by the relatively low epitope density of pMHC complexes on tumor cell surfaces.

To overcome this challenge, this study integrated TCRm nanobodies into a fully nanobody-based bispecific T cell engager platform for the first time, generating a novel TCRm bispecific nanobody T cell engager (TCRm Bi-NbTE). One end of this molecule targets CD3ε on T cells, while the other recognizes specific tumor-associated pMHC complexes, enabling TCR-independent redirection of T cell-mediated killing against tumor cells presenting intracellular antigens.

Overall, this study represents the first attempt to incorporate TCRm nanobody specificity into a fully nanobody-based T cell engager framework. The resulting TCRm Bi-NbTE platform provides a universal, modular, and scalable immunotherapeutic strategy capable of recognizing intracellular tumor antigens, supporting the development of next-generation cancer immunotherapies for diverse malignancies.

Experiments using AniView

In this study, the authors used AniView Multimodal In Vivo Imaging System from Guangzhou Biolight Biotechnology to evaluate the therapeutic potential of TCRm Bi-NbTE in vivo.

A xenograft tumor mouse model was established and randomly divided into different treatment groups. After infusion of human peripheral blood mononuclear cells, mice received TCRm Bi-NbTE or control treatments continuously for six days. Longitudinal in vivo imaging at different time points revealed that TCRm Bi-NbTE treatment significantly inhibited tumor growth compared with both control groups.

DOI: org/10.1038/s41392-026-02745-x