Background The coronavirus disease 2019 (COVID-19) pandemic has facilitated the clinical implementation of messenger RNA (mRNA) vaccines. The successful development of lipid nanoparticles (LNPs)-based mRNA vaccines, such as Spikevax (Moderna) and Comirnaty (BioNTech/Pfizer), has established LNPs as the preferred mRNA delivery carrier, suggesting broader applications beyond infectious diseases, notably in cancer vaccination. However, conventional LNP mRNA vaccines lack cell specificity, particularly for dendritic cells (DCs), which are crucial for eliciting antitumor immune responses,^{1 2} and predominantly distributed to injection sites and non-lymphoid organs. This highlights the need for a mRNA delivery platform that can efficiently target lymphoid organs and enhancing the antitumor efficacy of mRNA vaccines.³ In this study, we report a new LNP for lymph node-specific delivery and DC tropism to enhance the efficacy of mRNA cancer vaccines.

Methods A library of LNPs loaded with firefly luciferase encoding mRNA was constructed by systematically modulating ionizable lipids, helper lipids, and PEGylated lipids along with their compositions (figure 1A). In vitro screening using mouse bone marrow-derived dendritic cells (BMDCs) identified LNPs with enhanced mRNA transfection efficiency specifically in DCs. We evaluated LNP-mediated antigen mRNA expression, antigen presentation, and T cell priming in vitro. In vivo imaging (IVIS) was performed to assess lymph node delivery and mRNA expression of LNPs. The antitumor efficacy of LNP mRNA vaccines was assessed in a murine melanoma B16F10 model expressing a model ovalbumin antigen (B16F10-OVA). We also examined the magnitude and quality of antitumor immune responses in mice post mRNA-LNP vaccination.

Results Among the various LNP formulations screened, one top candidate, designated as LNP^A, significantly enhanced antigen presentation in DCs and CD8⁺ T cell priming in vitro, compared to the LNP formulation utilized in Spikevax (Moderna) (figure 1B). Additionally, this LNP^A exhibited superior mRNA expression and delivery to lymph nodes upon subcutaneous administration in mice, compared to the Spikevax LNP formulation. Further analysis revealed that LNP^A significantly increased DC-specific mRNA expression within the lymph nodes. In an antitumor efficacy study conducted against an established B16F10-OVA tumor model, immunization with LNP^A significantly inhibited tumor growth and increased the survival rate of tumor-bearing mice while markedly increasing antigen-specific memory precursor effector cells (MPECs; CD127⁺KLRG1^-OT-I Tetramer⁺) (figure 1C).

Conclusions We developed a lymph node-targeting LNP mRNA vaccine with DC tropism. This system is expected to serve as a versatile vaccine platform for combating cancer and other diseases.

Acknowledgements This work was supported by NIH (R01AI127070, R01CA210273, U01CA210152, R01DK108901, R01DE026728, R01DE030691, R01DE031951) and the University of Michigan Rogel Cancer Center Support Grant (P30CA46592).

References

1. Zhu Y, Ma J, Shen R, et al. Screening for lipid nanoparticles that modulate the immune activity of helper T cells towards enhanced antitumour activity. Nat Biomed Eng 2024;8(5):544–560. DOI: 10.1038/s41551-023-01131-0.

2. Yin D, Zhong Y, Ling S, et al. Dendritic-cell-targeting virus-like particles as potent mRNA vaccine carriers. Nat Biomed Eng 2024. DOI: 10.1038/s41551-024-01208-4.

3. Chen J, Ye Z, Huang C, et al. Lipid nanoparticle-mediated lymph node-targeting delivery of mRNA cancer vaccine elicits robust CD8(+) T cell response. Proc Natl Acad Sci U S A 2022;119(34):e2207841119. DOI: 10.1073/pnas.2207841119.

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Abstract 1111 Figure 1

(A) LNPs with enhanced mRNA transfection efficiency in DCs were screened. (B) LNP-mediated antigen mRNA expression, surface antigen presentation, and T cell priming in vitro. (C) Therapeutic efficacy of LNP mRNA vaccine against a B16F10-OVA tumor model