Abstract IA015: Leveraging mRNA to design a next-generation cell-based therapeutic cancer vaccine

Abstract

Abstract Monocyte-derived dendritic cell (DC)-based cancer vaccines were shown to activate T cell-mediated antitumor immune responses. To ensure high tumor specificity and potency of the DC-vaccine, we leveraged mRNA for the delivery of tumor antigens and proteins that enhance the DCs’ T-cell stimulatory capacity. With regard to tumor antigens, we studied neoantigens. These originate from erroneous DNA in tumor cells, creating a message for novel and unique tumor antigens of which neoepitopes could be presented by the tumor cells to T cells. Identifying neoepitopes has become possible through advances in next-generation sequencing and bioinformatic prediction algorithms. We developed a synthetic DNA template (SDT) to manufacture in vitro transcribed neoepitope mRNA. A benefit of this platform is the high flexibility and speed to create a neoepitope mRNA library. We showed that mRNA produced with the SDT could be used to validate bioinformatically predicted neoepitopes and could potentially be used to produce a DC-vaccine. With regard to potency, we developed a novel mRNA-based adjuvant, building on the knowledge that interleukin-12 produced by DCs correlates with T-cell activation. The novel mRNA mix, referred to as TetraMix, consists of 4 mRNA molecules encoding (1) constitutively active toll-like receptor 4, (2) CD40 ligand, (3) interferon-gamma and (4) a decoy receptor for interleukin-10. DCs electroporated with TetraMix mRNA showed a viral response gene expression profile. The obtained DC-maturation state enabled activation of tumor killing T cells. In summary, we developed a personalized cancer vaccine consisting of mRNA-engineered DCs, which is ready for evaluation in a clinical setting.</aaff> Citation Format: Karine Breckpot. Leveraging mRNA to design a next-generation cell-based therapeutic cancer vaccine [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr IA015.