The Canadian company behind a new plant-derived COVID-19 vaccine candidate has released the results of their Phase 1 clinical trials, saying two doses of their adjuvanted vaccine spurred a significant antibody response in 100 per cent of the trial subjects.
“They’re even better than we had hoped,” Nathalie Landry, executive vice president of scientific and medical affairs at Medicago, said of the results.
“When we talk about neutralizing antibody responses, we say it’s quite remarkable, especially when we compare with a subject that recovered from the disease.”
Those who received the Medicago adjuvanted vaccine in the Phase 1 trial actually had higher antibody levels than the levels found in those who had contracted COVID-19,
Medicago, a company based in Quebec, launched its first human trials in July.
In Phase 1, they looked at around 180 healthy subjects between the ages of 18 and 55. Participants were given either the vaccine on its own or the vaccine with one of two adjuvants mixed in GlaxoSmithKline (GSK)’s pandemic adjuvant or Dynavax’s CpG 1018.
An adjuvant is a substance that is added to vaccines in order to boost the effects and enable a higher immune response. They can be made from a variety of materials, including plants, aluminum and squalene oil, derived largely from sharks. Researchers wanted to measure what difference adding each adjuvant would make for the immune response.
They found that the vaccine candidate on its own did produce antibodies in the subjects, but demanded a much higher dosage level in order to get proper results.
It was the adjuvanted vaccines that really had an effect.
After two doses of adjuvanted vaccine — no matter which adjuvant was used — the antibody response rose significantly. However, subjects developed anti-spike IgG antibodies after a single dose of the vaccine when mixed with the GSK adjuvant, according to the press release.
“[GSK’s was] the adjuvant that provided us with the best immune response at [a] very low dose,” Landry said.
She explained that although they tested three doses at 3.75, 7.5 and 15 micrograms, the antibody response did not increase as the dosage went up.
“We only need 3.75 micrograms to get to a very significant level of antibody and cellular immune responses,” she said.
Being able to spur an immune response at a lower dose means they would be able to manufacture more of the vaccine — if it clears the rest of the phases.
In October, the company announced that they had reached an agreement with the federal government to supply Canada with up to 76 million doses of their vaccine, subject to approval from Health Canada.
The success of the GSK adjuvant means that moving forward, Medicago will be using only their vaccine candidate mixed with GSK’s pandemic adjuvant in further trials.
This phase also proved the safety of the vaccine candidate to proceed to further trials, as no subjects had any severe adverse side-effects, only mild and short-lived side-effects, according to the release.
Photo credit: THE CANADIAN PRESS/Graham Hughes
News source: CTV News