Vical Reports Expanded Potential Application For Vaxfectin Adjuvant

Vical has announced that systematic in vivo testing of its Vaxfectin adjuvant shows that it increased antibody and T-cell responses primarily by stimulating the immune system rather than simply increasing vaccine uptake.

The results, published in the journal Vaccine, validate encouraging results with the Vaxfectin adjuvant in prior animal and human studies, and position Vaxfectin as a potential ‘universal’ adjuvant for a broad range of vaccines.

Alain Rolland, executive vice president of product development at Vical, said: “Vaxfectin has significantly enhanced immune responses in a variety of vaccine applications and we designed these experiments to provide greater clarity regarding the specific mechanism of action driving these enhanced responses. We were very pleased with the results generated by the relatively new technique of gene expression profiling, which systematized the process of confirming Vaxfectin’s functionality. Our new insights regarding its mechanism of action expand the opportunities to apply Vaxfectin as a universal adjuvant with DNA-, protein- and peptide-based vaccines.”

Vaxfectin has been shown in multiple animal models to dramatically increase the antibody and T-cell immune responses to antigens expressed from plasmid DNA vaccines. Results from two phase 1 clinical trials of Vaxfectin-formulated H5N1 influenza DNA vaccines demonstrated strong antibody responses and achieved T-cell responses in 75% to 100% of subjects in various dose cohorts. Vaxfectin has demonstrated similar effect with protein-based vaccines, and the formulation can be adjusted to favor specific immune responses.

The current study involved expression profiling in mice as well as real-time PCR and flow cytometry. Using DNA microarrays of 39,000 transcripts, the analyses showed a significant increase in genes involved in antigen processing and presentation, apoptosis and innate immunity pathways. In addition, local and systemic levels of cytokines driving both antibody and T-cell responses were increased. Immunohistochemistry of injected muscles also revealed an increase of infiltrated macrophages as early as 24 hours after administration.