Tertiary amine N-oxide zwitterionic lipids facilitate muscle-selective mRNA vaccine delivery for enhancing cDC1-mediated antitumor efficacy.

Lipid nanoparticles (LNPs) have emerged as a groundbreaking platform for delivering messenger RNA (mRNA)-based vaccines and therapeutics. However, clinically approved LNPs administered intramuscularly often lead to unintended liver antigen expression, raising safety concerns related to excessive immune activation and potential tissue damage. Extensive research has focused on optimizing LNPs to adjust their tissue specificity and immunogenicity, while the role of helper lipids as structural components has received little attention. Here, we developed a new LNP system by replacing traditional phospholipids with innovative tertiary amine N-oxide zwitterionic lipids (AOLs) synthesized using the Ugi four-component reaction (Ugi-4CR) followed by tertiary amine oxidation. After two rounds of structural screening and optimization, three top-performing AOL-based LNPs demonstrated muscle-selective mRNA delivery with minimal off-target effects. Using ovalbumin (OVA)-encoded mRNA as a model antigen, the optimized LNP-mRNA vaccine effectively activated more migratory and resident cDC1 cells in muscle and lymph nodes (LNs), increasing tumor CD8+ T cell infiltration and thus inhibiting tumor growth in a murine melanoma model, compared to the benchmark SM-102 LNP. Furthermore, co-formulating CpG adjuvants with the LNP-mRNA vaccine amplified cDC1-mediated antitumor efficacy. In addition, AOL-based LNP-mRNA vaccines reduced the infiltration of CD3+ CD45+ T cells in the liver, decreasing the risk of liver inflammatory responses. As a result, we provide a safe and efficient LNP system for muscle-selective mRNA vaccine delivery, enhancing cDC1-mediated antitumor treatment and offering a promising strategy for tumor immunotherapy.