An Open Label, Dose Escalation Phase I Trial to Assess Safety and Immunogenicity of the H7HLAII DNA Vaccine, Encoding Influenza Hemagglutinin H7 Directed to HLA Class II, for Prophylaxis of Pandemic Influenza Infection in Healthy Volunteers

H7HLAII is a DNA vaccine that could remedy the current challenges of slow production for conventional influenza vaccines. The prolonged production time of current influenza vaccines has as a consequence that circulating influenza strains often have drifted significantly from the vaccine included strains, and as such reducing vaccine efficacy. The rapid production enabled by the DNA format could enhance efficacy of seasonal influenza vaccines, but is particularly well suited for prophylaxis against an emerging influenza pandemic.

The only vaccine format that can presently be produced and deployed within 2-3 months is DNA. However, DNA vaccines are typically hampered by low immunogenicity. To surpass this challenge, H7HLAII genetically links the influenza H7 HA to a targeting unit that steers the produced vaccine proteins to HLA class II expressing antigen presenting cells (APC). Previously, this strategy has been shown to increase immunogenicity after vaccination in mice, ferrets, pigs, and rhesus macaques, with a particular strength in antibody induction. Of note, antibodies represent a correlate of protection against influenza, as well as most other infectious diseases. It has also been shown that H7HLAII protected immunized ferrets against a homologous H7N9 strain, and with no safety concerns after toxicity testing in guinea pigs.

H7HLAII is designed to induce strong antibody responses against a specific strain of H7N9 influenza. At present, there are several strains of H7N9 that cause concern for future pandemic emergences, in that periodic zoonotic transmissions are observed in Asia. To date, H7N9 viruses do not have the ability to transmit between humans, but the high mortality rates observed after zoonotic transmissions dictates that society ought to be ready for future emergences. H7HLAII is designed to enable rapid exchange of antigen, allowing for accommodation of any HA into the vaccine construct. As such, the strategy could be of great importance for global prophylactic prevention.

Although a pandemic situation might opt for rapid testing, this trial is planned as a cautious phase I trial with healthy volunteers. It should be noted that the safety aspects for a number of DNA vaccines has been good during clinical testing over the past decade, and the first DNA vaccine was recently licensed for human use.