Optimized clinical protocol to generate dual function human V9V2 T cells as a vaccine to target EBV-positive cancers
Esdy Rozali1, Cheryl Lai-Lai Chiang1, Who-Whong Wang1,2 and Han Chong Toh1,2,* 1National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610; 2Tessa Therapeutics, 8 Temasek Boulevard, #24-02 Suntec Tower 3, Singapore 038988 *Corresponding author
Despite developing monocyte-derived DCs (moDCs) as therapeutic cancer vaccines for 3 decades, there has been limited clinical success. One challenge is obtaining large numbers of moDCs with robust APC function. Here, we propose T cells as a viable alternative. There is relative ease in expanding V9V2 T cells from peripheral blood, and T cells have been reported to show both APC and effector functions. Analysis of ~18 000 human tumors across 39 cancers identified tumor infiltrating T cells as the most favorable prognostic immune population. Here, we report the expansion V9V2 T cells from healthy donors' PBMCs using GMP-grade reagents and its functional and transcriptomic characterization. Following cytokine optimization experiments, we found that specific combinations of IL-2, IL-15 and IL-21 leads to optimal APC or effector functionality. T cells produced in the presence of IL-2 alone or in combination with other cytokines expressed increased APC markers compared to IL-15 alone or in combination. Furthermore, EBV LMP2 antigen-pulsed, cytokine-treated T cells were comparable to moDCs in stimulating the proliferation of naïve CD4+ and CD8+ T cells. NanoString profiling was performed on cytokine-treated T cells compared to moDCs to describe the differences in their immunological transcriptome. On the effector end, stronger tumor cytotoxicity was observed from T cells generated in combination with IL-21 than those generated with IL-2 or IL-15 only. Notably, there was stronger cytotoxic activity against the EBV+ nasopharyngeal carcinoma cell line C666-1 compared to EBV- cell lines. We also used an in vivo EBV+ tumor model to test LMP2-pulsed T cell vaccination alone and in combination treatments, and performed bulk culture optimized T cells expansion as well as LMP2-specific CTL expansion protocol to simulate a large-scale clinical trial setting. In summary, we demonstrated the ability to leverage T cells' APC and effector functions. This study indicates the potential of T cells as therapeutic immunotherapy against EBV-positive cancers.
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