Promising Phase I results for DNA-based Zika vaccine

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A new generation DNA-based Zika vaccine is both safety and immunogenic in humans, according to research from University of Pennsylvania conducted in partnership with The Wistar Institute, Inovio Pharmaceuticals (all PA, USA), and GeneOne Life Science, Inc. (Seoul, South Korea). These promising Phase I results may open the door to further clinical trials.

A vaccine to Zika has remained elusive; the GLS-5700 vaccine tested in this trial is a synthetic DNA candidate, which encodes the Zika premembrane and envelope proteins. The Phase I results, published recently in the New England Journal of Medicine, reported that participants receiving three doses of GLS-5700 generated an immune response against Zika virus with minimal adverse effects.

Author, David Weiner (Wistar institute) commented:  “Synthetic DNA vaccines, such as this Zika vaccine candidate our team has developed, are an important approach to preventing emerging infectious diseases. This novel DNA vaccine was developed and implemented in just months via a platform that has advantages in temperature stability, storage, dose, and distribution compared to most traditional vaccines, making DNA vaccines an important tool to respond quickly to curb an emerging epidemic.”

The team enrolled 40 participants who were split into two groups, receiving either 1mg or 2 mg doses of the vaccine intradermally at baseline, 4 weeks and 12 weeks. Each dosage was followed by electroporation, which acts to facilitate vaccine uptake and subsequent production of an immune response.

The researchers observed that 2 weeks after the final dose, 100% of individuals had generated Zika-specific antibodies, with 80% possessing significant neutralizing antibodies against the virus. Moreover, the team demonstrated that serum obtained from participants could protect immunocompromised mice from developing disease when challenged with Zika virus, indicating the antibodies are sufficient to prevent infection.

Finally the GLS-5700 vaccine proved safe, as no serious adverse effects were reported, and minor side effects included redness and swelling at the injection site. The team stated that further study is required to assess the potential of this candidate; however, these positive results are promising not only for the future of Zika vaccines, but also DNA vaccines as a platform.

Interested in other vaccines currently in clinical trials? Take a look at our update on Zika’s vaccine pipeline.

Author Pablo Tebas (University of Pennsylvania) concluded: “With these new results, we are one step closer to hopefully finding a way to prevent infection, which can cause serious birth defects and developmental delays in babies born to women who are infected with Zika.

“Our results show great promise that synthetic DNA vaccines for Zika and other viruses, such as chikungunya, West Nile virus, pandemic influenza or Ebola, are likely important as viable options for the future of vaccines.”

Sources: Tebas P, Roberts CC, Mthumani K et al. Safety and Immunogenicity of an Anti–Zika Virus DNA Vaccine — Preliminary Report. N. Engl J. Med. doi:10.1056/NEJMoa1708120 (2017) (Epub ahead of print); www.pennmedicine.org/news/news-releases/2017/october/synthetic-dna-based-zika-vaccine-candidate-found-to-be-safe-and-effective

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