Adjuvant Screen Identifies Synthetic DNA-Encoding Flt3L and CD80 Immunotherapeutics as Candidates for Enhancing...

Area of Science:

• Immunology
• Oncology
• Vaccinology

Background:

• Overcoming immune tolerance to tumor-associated antigens is critical for effective cancer vaccine immunotherapy.
• Adjuvants are essential for enhancing anti-tumor immune responses in cancer vaccines.

Purpose of the Study:

• To generate and screen gene-based molecular adjuvants to improve anti-tumor T cell immunity.
• To characterize the mechanisms of direct and indirect T cell stimulation by novel adjuvants.

Main Methods:

• Systematic screening of over twenty gene-based molecular adjuvants (cytokines, chemokines, T cell co-stimulators).
• Evaluation of T cell responses targeting cancer antigens STEAP1 and TERT.
• Characterization of CD80-Fc (direct T cell stimulation) and Flt3L-Fc (dendritic cell activation).
• Assessment of dendritic cell infiltration, trafficking, and gene expression changes in muscle tissue post-Flt3L-Fc administration.
• Quantification of antigen-specific T cell responses (IFNγ, TNFα, CD107a) following CD80-Fc addition.

Main Results:

• Identified robust adjuvants enhancing T cell responses to STEAP1 and TERT.
• Flt3L-Fc administration increased dendritic cell infiltration and activation.
• CD80-Fc addition to STEAP1 vaccine formulations increased T cell responses by 8-fold.
• CD80-Fc enhanced responses in both CD8+ and CD4+ T cells, producing IFNγ, TNFα, and CD107a.
• CD80-Fc demonstrated efficacy across multiple tumor antigens (STEAP1, Survivin, HPV), suggesting universal adjuvant potential.

Conclusions:

• T cell engagement, either directly via CD80-Fc or indirectly via Flt3L-Fc, significantly enhances cancer vaccine efficacy.
• These molecular adjuvants represent a promising strategy for improving T cell-mediated anti-tumor immunity.