An Integrated Polymeric mRNA Vaccine without Inflammation Side Effects for Cellular Immunity Mediated Cancer Therapy

Abstract Among the few available mRNA delivery vehicles, lipid nanoparticles (LNPs) are the most clinically advanced but they require cumbersome four components and suffer from inflammation‐related side effects that should be minimized for safety. Yet, a certain level of proinflammatory responses and innate immune activation are required to evoke T‐cell immunity for mRNA cancer vaccination. To address these issues and develop potent yet low‐inflammatory mRNA cancer vaccine vectors, a series of alternating copolymers “PHTA” featured with ortho ‐hydroxy tertiary amine (HTA) repeating units for mRNA delivery is synthesized, which can play triple roles of condensing mRNA, enhancing the polymeric nanoparticle (PNP) stability, and prolonging circulation time. Unlike LNPs exhibiting high levels of inflammation, the PHTA‐based PNPs show negligible inflammatory side effects in vivo. Importantly, the top candidate PHTA‐C18 enables successful mRNA cancer vaccine delivery in vivo and leads to a robust CD8 + T cell mediated antitumor cellular immunity. Such PHTA‐based integrated PNP provides a potential approach for establishing mRNA cancer vaccines with good inflammatory safety profiles.