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GSK-Medicago COVID-19 Vaccine Elicits High Antibody Responses
After the second dose of the COVID-19 vaccine, both age cohorts responded with neutralizing antibody titers that were 10 times higher than those in patients recovering from coronavirus.
Medicago’s Coronavirus-Like Particle COVID-19 Vaccine Candidate (CoVLP) elicited significant humoral immune response across all age groups when administered in combination with GSK’s pandemic adjuvant, according to a recent press release.
The randomized, placebo-controlled Phase 2 clinical trial dosed health adults 18 to 64 years of age from the US and Canada with two doses of CoVLP, at 3.75 micrograms. The doses were given 21 days apart.
CoVLP is composed of recombinant spike (S) glycoprotein expressed as virus-like particles (VLPs). It mimics the structure of the virus responsible for COVID-19 disease.
This allows the VLPs to be recognized by the immune system response and reduce the amount of antigen required per dose.
Researchers found that CoVLP with GSK’s pandemic adjuvant induced greater humoral response in adults than older adults after a single dose, but after the second dose, both age cohorts responded with neutralizing antibody titers that were nearly 10 times higher than those in patients recovering from COVID-19.
Additionally, CoVLP exhibited an acceptable overall safety profile, while adverse events were generally mild or moderate.
“We are delighted to see that the results suggest a very strong immune response. Medicago’s COVID-19 vaccine candidate combined with GSK’s pandemic adjuvant was also well tolerated, reinforcing its potential benefits,” Thomas Breuer, chief medical officer at GSK, said in the announcement.
“We now look forward to the outcome of the ongoing Phase 3 trial of this refrigerator-stable vaccine candidate as the next step forward in our contribution to the global response to the pandemic,” Breuer continued.
The Phase 2 trial results reiterate the promising profile observed during the Phase 1 trial. In the Phase 1 trial, immunogenicity, as measured by the neutralizing antibody titer, was about 10 times higher than those in a panel of sera from patients recovering from COVID-19.
Due to the promising Phase 1 and Phase 2 results, GSK and Medicago initiated a Phase 3 clinical trial of CoVLP in combination with GSK’s pandemic adjuvant in mid-March.
The trial is a randomized, placebo-controlled, two-way cross-over design that will evaluate the safety and efficacy of the CoVLP formulation compared to placebo in 30,000 adults 18 to 65 years of age, followed by elderly adults over 65 years of age, and adults with comorbidities.
The trial will take place in 10 countries, pending regulatory approvals. The first country will be Canada, followed by the US.
“We are very excited to see such positive results from the Phase 2 data. After two doses, the adjuvanted vaccine candidate induced robust neutralizing antibody and cellular immune responses in all subjects, irrespective of age,” said Nathalie Landry, executive vice president, of scientific and medical affairs at Medicago.
“These results give us confidence as we continue to move forward with our Phase 3 clinical trial. We hope to add another tool in the global fight against COVID-19, particularly as cross-protection emerges as an important consideration in vaccination efforts worldwide,” Landry continued.
When GSK and Medicago announced their collaboration in mid-July 2020, they committed to developing and evaluating COVID-19 vaccine candidates combining Medicago’s recombinant CoVLP with GSK’s pandemic adjuvant system.
The use of an adjuvant system can be beneficial during a pandemic because it can help to boost immune response and reduce the amount of antigen required per dose.
Many vaccines and treatments today use a combination of a protein-based antigen together with an adjuvant. An adjuvant enhances the immune response to viruses and has been proven to create a longer-lasting immunity against infections than the vaccine alone.
Last June, GSK announced that it will manufacture one billion doses of its pandemic vaccine adjuvant system this year to support the development of various adjuvanted COVID-19 vaccine candidates.
The technology system can decrease the amount of vaccine protein required per dose. This allows more vaccine doses to be produced for more individuals.
