A Middle East respiratory syndrome coronavirus (MERS CoV) DNA vaccine candidate was shown to be safe, well-tolerated, and induced a robust immune response in a phase I first-in-human clinical trial.
The open-label, single-arm study enrolled healthy adults aged 18-50 years; excluding people with previous infection or treatment of MERS.
Seventy-five eligible participants were enrolled sequentially using a dose-escalation protocol to receive 0.67 mg (n=25), 2 mg (n=25), or 6 mg (n=25) GLS-5300 MERS Cov vaccine, administered via a single intramuscular 1 mL injection at baseline, week four, and week 12, followed immediately by co-localised intramuscular electroporation.
Vaccine-induced immune responses were similar to those of individuals who had recovered from natural MERS CoV infection.
GLS-5300 was well tolerated with no vaccine-associated serious adverse events. Immune responses were dose-independent, detected in more than 85 per cent of participants after two vaccinations, and durable through 48 weeks of follow-up, post-dose three.
The data supported further development of the vaccine, including additional studies to test the efficacy of GLS-5300 in a region endemic for MERS coronavirus. Research is now advancing through a second phase I/IIa trial in South Korea and a phase II study in the Middle East.
The initial findings are published in the Lancet Infectious Diseases.