Molecular Therapy
Volume 30, Issue 11, 2 November 2022, Pages 3358-3378
Journal home page for Molecular Therapy

Original Article
EBAG9 silencing exerts an immune checkpoint function without aggravating adverse effects

https://doi.org/10.1016/j.ymthe.2022.07.009Get rights and content
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Chimeric antigen receptor (CAR) T cells have revolutionized treatment of B cell malignancies. However, enhancing the efficacy of engineered T cells without compromising their safety is warranted. The estrogen receptor-binding fragment-associated antigen 9 (EBAG9) inhibits release of cytolytic enzymes from cytotoxic T lymphocytes. Here, we examined the potency of EBAG9 silencing for the improvement of adoptive T cell therapy. MicroRNA (miRNA)-mediated EBAG9 downregulation in transplanted cytolytic CD8+ T cells (CTLs) from immunized mice improved their cytolytic competence in a tumor model. In tolerant female recipient mice that received organ transplants, a minor histocompatibility antigen was turned into a rejection antigen by Ebag9 deletion, indicating an immune checkpoint function for EBAG9. Considerably fewer EBAG9-silenced human CAR T cells were needed for tumor growth control in a xenotransplantation model. Transcriptome profiling did not reveal additional risks regarding genotoxicity or aberrant differentiation. A single-step retrovirus transduction process links CAR or TCR expression with miRNA-mediated EBAG9 downregulation. Despite higher cytolytic efficacy, release of cytokines associated with cytokine release syndrome remains unaffected. Collectively, EBAG9 silencing enhances effector capacity of TCR- and CAR-engineered T cells, results in improved tumor eradication, facilitates efficient manufacturing, and decreases the therapeutic dose.

Keywords

cancer immunotherapy
chimeric antigen receptor T cells
secretory pathway
cytolytic capacity
hematologic malignancies
adoptive T cell therapy
multiple myeloma
leukemia

Data availability

The RNA-seq data from this paper were deposited under ENA: PRJEB37843.

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