Nanoparticle delivery amplifies the adjuvant effects of TLR agonists for cancer vaccines 2310294

Abstract Introduction Nanoparticle delivery systems are widely used to improve vaccine adjuvant effects. IVAX, a nanoparticulate adjuvant system encapsulating a combination of Toll-like receptor (TLR) 4 and TLR9 agonists, has shown significant promise in various vaccine models. However, the role of nanoparticles in the adjuvant system was not well-defined. This study aims to investigate how different nanoparticle carriers affect the immunogenic performance of adjuvanted vaccine formulations in a melanoma vaccine model. Methods Three representative nanoparticles, including nanoemulsion (IVAX-1), cationic lipid nanoparticle (LNP; IVAX-5), and ionizable LNP (IVAX-6), were formulated to encapsulate a combination adjuvant of CpG and MPLA using ovalbumin (OVA) as a model antigen. Physicochemical properties of all three nanoparticles were characterized, followed by the evaluation of NF-κB activation using the RAW-Blue reporter assay. Furthermore, humoral and cellular immune responses, reactogenicity, and antitumor efficacy across vaccine formulations were evaluated in B16F10-OVA melanoma models. Results Nanoparticle-formulated TLR agonist adjuvants enhanced NF-κB activation compared to controls, indicating a nanoparticle-dependent effect on innate immune signaling. Mice immunized with adjuvanted vaccines showed complete tumor protection through the study endpoint, whereas buffer-treated and antigen-only control groups developed progressive tumor growth. Immunoprofiling post-vaccination revealed the differences in immune responses induced by different nanoparticle formulations. Conclusion Together, this study highlights the importance of nanoparticle carrier design in shaping the performance of TLR-agonist adjuvanted cancer vaccines. Funding Source This research was supported by the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health (NIH) under Award Number 1U19AI181968-01 Topic Categories Vaccines and Immunotherapy (VAC)