Intradermal SynCon® Ebola GP DNA Vaccine is Temperature Stable and Safely Demonstrates Cellular and Humoral Immunogenicity Advantages in Healthy Volunteers.

BACKGROUND: Non-live vaccine approaches that are simple to deliver and stable at room temperature or 2-8°C could be advantageous in controlling future Ebola virus (EBOV) outbreaks. Using an immunopotent DNA vaccine that generates protection from lethal EBOV challenge in small animals and NHPs, we performed a clinical study to evaluate both intramuscular (IM) and novel intradermal (ID) DNA delivery.

METHODS: Two DNA vaccine candidates (INO-4201 and INO-4202) targeting the EBOV glycoprotein (GP) were evaluated for safety, tolerability and immunogenicity in a Phase 1 clinical trial. The candidates were evaluated alone, together, or in combination with plasmid-encoded human cytokine IL-12 followed by in vivo electroporation (EP) using either the CELLECTRA® IM or ID delivery devices.

RESULTS: The safety profile of all five regimens was shown to be benign, with the ID route being better tolerated. Antibodies to EBOV GP were generated by all 5 regimens with the fastest and steepest rise observed in the intradermal group. Cellular immune responses were generated with every regimen.

CONCLUSIONS: Intradermal delivery of INO-4201 was well-tolerated and resulted in 100% seroreactivity after two doses and elicited interferon-γ T cell responses in over 70% of subjects, providing a new approach for EBOV prevention in diverse populations.