Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of hematological malignancies, yet achieving comparable efficacy against solid tumors remains a severe clinical challenge. A primary obstacle is the immunosuppressive tumor microenvironment, which is characterized by high expression of inhibitory immune checkpoints like TIM-3 that aggressively induce T-cell exhaustion and promote tumor evasion. While combining CAR-T cells with systemic checkpoint blockade antibodies is heavily investigated, it often leads to short-lived efficacy and severe immune-related adverse events.

This new research, published in the Genes & Diseases journal by a team from Chongqing Medical University, The Ninth People's Hospital of Chongqing, Chongqing University Cancer Hospital and Sichuan University, investigated a safer, cell-intrinsic strategy by engineering HER2-specific CAR-T cells to simultaneously silence their own TIM-3 expression to combat solid ovarian tumors.

To directly counteract TIM-3-mediated immune evasion, the researchers constructed a dual-promoter lentiviral vector capable of simultaneously expressing a TIM-3-targeting short hairpin RNA (shRNA) and a third-generation CAR recognizing the HER2 antigen. Flow cytometry confirmed that this dual genetic modification efficiently down-regulated TIM-3 without negatively altering the essential phenotype of the CAR-T cells, fundamentally maintaining a high proportion of potent central memory T cells. Extensive in vitro co-culture experiments utilizing Galectin-9-expressing human ovarian cancer (SKOV3) cells demonstrated the functional superiority of this advanced design. The data conclusively revealed that TIM-3-silenced CAR-T cells exhibited profoundly higher lytic cytotoxicity, secreting significantly elevated levels of the critical anti-tumor cytokines IFN-γ and TNF-α compared to standard HER2-CAR-T cells.

Remarkably, in vivo evaluations using an ovarian cancer xenograft model demonstrated that the adoptive transfer of TIM-3-silenced CAR-T cells significantly delayed tumor growth and sharply minimized tumor burden during the early treatment phase compared to conventional CAR-T cells. Because the TIM-3 blockade was localized entirely within the engineered T cells at the tumor site, this strategy inherently bypasses the systemic toxicities associated with injected monoclonal antibodies.

However, researchers observed that the dramatic anti-tumor effect gradually diminished in the later stages of the trial. Comprehensive RNA-sequencing and gene set variation analysis (GSVA) unraveled the underlying adaptive resistance mechanism, revealing that the delayed loss of efficacy was fundamentally driven by a massive compensatory up-regulation of the PD-1 signaling pathway and macrophage activation.

In conclusion, intrinsically targeting the TIM-3 checkpoint offers a powerful new strategy to temporarily shield CAR-T cells from early exhaustion and enhance localized target cell lysis. This profound finding directly positions the development of dual-silenced CAR-T cells—simultaneously knocking down both TIM-3 and PD-1—as highly compelling, next-generation immunotherapies capable of delivering durable clinical remissions for solid tumors.

Reference

Title of Original Paper: Blockade of co-inhibitory receptor immune checkpoint protein TIM3/CD366 augments the anti-cancer activity of CAR-T therapy in solid tumors: An ovarian cancer example

Journal: Genes & Diseases
Genes & Diseases is a journal for molecular and translational medicine. The journal primarily focuses on publishing investigations on the molecular bases and experimental therapeutics of human diseases. Publication formats include full length research article, review article, short communication, correspondence, perspectives, commentary, views on news, and research watch.

DOI: https://doi.org/10.1016/j.gendis.2025.101978

Funding Information:
The National Natural Science Foundation of China (No. 81703057/H1611)
Chongqing Natural Science Foundation (China) (No. CSTB2022NSCQ-MSX0934)

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Genes & Diseases publishes rigorously peer-reviewed and high quality original articles and authoritative reviews that focus on the molecular bases of human diseases. Emphasis is placed on hypothesis-driven, mechanistic studies relevant to pathogenesis and/or experimental therapeutics of human diseases. The journal has worldwide authorship, and a broad scope in basic and translational biomedical research of molecular biology, molecular genetics, and cell biology, including but not limited to cell proliferation and apoptosis, signal transduction, stem cell biology, developmental biology, gene regulation and epigenetics, cancer biology, immunity and infection, neuroscience, disease-specific animal models, gene and cell-based therapies, and regenerative medicine.

Scopus Cite Score: 8.4 | Impact Factor: 9.4

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