IL-18-inducible LMP2A-targeting TCR-T cells demonstrate superior cytotoxicity against EBV-associated malignancies in vitro

Epstein-Barr virus (EBV) infects over 90% of the population, establishing lifelong persistence and causing severe complications like post-transplant lymphoproliferative disorder (PTLD) in immunocompromised patients. EBV latent membrane protein 2A (LMP2A) is expressed in latency stages II/III, driving activation and proliferation of infected B cells, making it a crucial target for EBV-associated malignancies. Current T cell therapies often face challenges like T cell exhaustion and an immunosuppressive tumor microenvironment (TME), necessitating novel strategies to enhance their efficacy against these persistent viral-driven cancers.

Researchers developed novel T cell receptor (TCR)-engineered T cells, designated iIL-18_LMP2A_TCR-T cells. These cells were based on a TCR recognizing the HLA-A*02:01-restricted LMP2A-derived peptide CLGGLLTMV and were equipped with a TCR-inducible cassette for IL-18 release. The study compared the functionality of these iIL-18_LMP2A_TCR-T cells against control LMP2A_TCR-T cells (without inducible IL-18). The primary endpoint was cytotoxicity against HLA-A*02:01+ EBV-infected B-lymphoblastoid cell lines (EBV+ B-LCLA*02:01), serving as an in vitro PTLD model. Further evaluation involved multicellular tumor spheroid (MCTS) models to assess sustained control of tumor growth.

The engineered iIL-18_LMP2A_TCR-T cells demonstrated significantly improved cytotoxicity against HLA-A*02:01+ EBV+ B-LCLA*02:01 cells when compared to LMP2A_TCR-T cells lacking the inducible IL-18 cassette. This enhanced killing capacity was observed in direct cell line assays, indicating a more potent anti-tumor response. The superior functionality of the iIL-18_LMP2A_TCR-T cells was further corroborated in multicellular tumor spheroid (MCTS) models. In these more complex 3D structures, the modified T cells mediated sustained control of EBV+ B-LCLA*02:01 growth over time, suggesting a prolonged therapeutic effect. The inducible IL-18 release is hypothesized to prevent T cell exhaustion and promote a favorable remodeling of the immunosuppressive tumor microenvironment, contributing to the observed improvements. While specific numerical data (e.g., percent killing, fold-change in growth inhibition) were not provided in the abstract, the qualitative improvements were consistently noted across both in vitro models. This indicates a robust enhancement in the therapeutic potential of these next-generation T cells. The strategy aims to overcome common limitations of adoptive T cell therapies by locally boosting immune responses and mitigating exhaustion. This approach represents a significant step towards more effective immunotherapies for EBV-associated malignancies. > The iIL-18_LMP2A_TCR-T cells exhibited improved cytotoxicity against HLA-A*02:01+ EBV+ B-LCLA*02:01 cells and mediated sustained control of tumor spheroid growth, highlighting their potential as an effective therapeutic approach.