MERS-CoV vaccine shows promise in phase 1 trial
Data from a phase 1, open-label, single-arm, dose-escalation trial demonstrated the tolerability, safety and immunogenicity of a vaccine against Middle Eastern respiratory syndrome coronavirus, or MERS-CoV, researchers reported.
It was the first-ever clinical trial of a vaccine to prevent the respiratory illness, which was first reported in humans in 2012.
According to Christine C. Roberts, PhD, director of clinical laboratory development at GeneOne Life Science, MERS-CoV has an overall mortality rate of about 35%, and previous studies have demonstrated that the greatest risk for human transmission is exposure to camels, although many cases have been reported in health care workers who have treated infected patients or in people with no known exposure to camels or other infected individuals.
“We conducted the trial in collaboration with the Walter Reed Army Institute for Research, and it showed that the GLS-5300 DNA vaccine targeting MERS-CoV’s outer spike glycoprotein was well-tolerated and generated strong antibody and T-cell responses in healthy adult volunteers,” Roberts told Infectious Disease News.
Between Feb. 17 and July 22, 2016, the researchers sequentially enrolled 75 healthy adults aged 18 to 50 years using a dose escalation protocol. At baseline, week 4 and week 12, 25 participants received 0.67 mg, 25 received 2 mg and 25 received 6 mg of the vaccine administered via a single intramuscular 1-mL injection.
There were no reported vaccine-associated serious adverse events, according to Roberts and colleagues. The most common adverse events were injection-site reactions, reported by 93% of participants. At least one solicited adverse event occurred for 97% of all participants. These symptoms were self-limiting, and 76% of participants receiving 0.67 mg, 80% receiving 2 mg and 68% receiving 6 mg reported that the solicited symptoms were mild. The most common local solicited symptoms were administration site pain and tenderness, reported by 92% and 84% of all participants, respectively. The most common systemic symptoms were headache and malaise or fatigue.
According to the study, 75% of all participants reported unsolicited symptoms, of which 35% were classified as treatment related. Infections occurred in 36% of participants, of which 8% were possibly related to study treatment.
After two vaccinations, 71% of participants had a T-cell response, and 77% had vaccine-induced humoral and cellular responses at week 60. After three vaccinations, 76% of participants had a T-cell response, and 64% had vaccine-induced humoral and cellular responses at week 60. After 6 weeks, no differences in immune response between the dosage groups were observed.
“The vaccine against the MERS-CoV was shown to generate immune responses in approximately 95% of clinical trial participants, and the immune responses generated were similar to those who recovered from natural MERS-CoV infection as part of the 2015 outbreak in Seoul, South Korea,” Roberts said.
In a related editorial, In-Kyu Yoon, MD, senior advisor for the International Vaccine Institute and director of the Global Dengue & Aedes-Transmitted Diseases Consortium, and Jerome H. Kim, MD, director general of the International Vaccine Institute, said the trial illustrated how developing a vaccine against a novel pathogen can be challenging.
“Completion of the phase 1 trial of GLS-5300 represents an incremental but important step in the development of vaccines against emerging viral global threats,” they wrote.
According to Roberts, more clinical trials are needed to confirm the safety and demonstrate the efficacy of the vaccine.
“This study represents an important first step supporting global public health interests in the development of a vaccine that is safe and effective to fight MERS-CoV,” she said. “The GLS-5300 vaccine might have a valuable role in the response to any future MERS-CoV outbreaks.” – by Marley Ghizzone
Disclosures: Roberts is an employee of GeneOne Life Science. Please see the study for all other authors relevant financial disclosures. Yoon and Kim report that their institution is collaborating with GeneOne Life Science on a MERS coronavirus vaccine trial in South Korea.