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bioRxiv · 10.1101/2025.06.09.657934

A single MHCII neoepitope mRNA vaccine elicits CD4 T- and B- cell responses promoting endogenous CD8 anti-tumor immunity

Abstract

Recent progress in therapeutic cancer vaccines has shown promising clinical activity, especially when targeting MHC class I (MHCI) neoantigen-specific CD8+ T cell responses in post-surgical patients. To explore the role of CD4+ T cells in vaccine-dependent tumor rejection, we constructed an mRNA lipoplex vaccine encoding a single MHCII-restricted neoantigen. The vaccine elicited Tfh and Th1 cell responses while decreasing Tregs, leading to rejection of established tumors in mice. IL-21 and IFN-{gamma}, crucial for Tfh and Th1 function respectively, contributed to anti-tumor activity. B cells and neoantigen-specific antibodies were also shown to participate in vaccine efficacy. Additionally, conventional type 1 dendritic cells (cDC1s) were essential for eliciting vaccine-induced CD4+ T cells, and both cDC1s and CD4+ T cells were required to enhance endogenous CD8+ responses, which were crucial for tumor control. Our results suggest that immunizing against MHCII neoantigens alone is sufficient to orchestrate a potent and cooperative immune response against cancer.

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BibTeXRIS

Capietto, A.-H., Balanca, C.-C., Bouziat, R., Wu, T., Gober, J., Carbone, C., Nissenbaum, A., Hoshyar, R., Yadav, M., Gutierrez, A., Chestnut, Y., Javinal, V., Menon, H., Darmanis, S., de Simone, M., Sun, Y., Seshasayee, D., Paluch, M., Bulutoglu, B., Jones, T., Wang, Y., Liao, L., Duong, E., Anand, A., Antonelli, A., Oei, Y., Cheung, J., Luoh, S.-M., Ziai, J., Preston, J., Hung, J., Freund, E., Wichner, S., Oh, J., Tahtinen, S., Sahin, U., ElSohly, A., Schartner, J., Delamarre, L., Mellman, I., Linehan, J.. 2025-06-12. A single MHCII neoepitope mRNA vaccine elicits CD4 T- and B- cell responses promoting endogenous CD8 anti-tumor immunity. https://doi.org/10.1101/2025.06.09.657934

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