Some of our experts are involved in the testing of Canadian COVID-19 vaccines. Two recent pre-prints highlight promising results from Providence Therapeutics’ mRNA vaccine and from Medicago’s plant-based vaccine. Although at different stages of development, both vaccines are presented as highly immunogenic and safe.

 

Main conclusions:

  • Providence Therapeutics’ PTX-COVID19-B, a SARS-CoV-2 mRNA vaccine, was shown to be highly immunogenic (elicits a good immune response), safe, and effective in preventing SARS-CoV-2 infection in mice and hamsters. This vaccine is currently in phase 1 human clinical trials.
  • Two doses of Medicago’s plant-based vaccine, administered with adjuvant, was shown to be highly immunogenic and safe in over 500 subjects aged 18 to 88 years, in a phase 2 trial.

 

A collaboration between CITF-funded researchers from University of Toronto Drs. Mario Ostrowski and Anne-Claude Gingras, and Providence Therapeutics performed a preclinical evaluation of Canadian-made SARS-CoV-2 mRNA vaccine PTX-COVID19-B.1 According to a pre-print publication that has not yet been peer reviewed, this vaccine induced robust humoral and cellular immune responses and completely protected mice and hamsters from SARS-CoV-2 infection. The authors report that blood from vaccinated mice was able to neutralize several SARS-CoV-2 variants of concern, including those originally described in the United Kingdom (B.1.1.7), South Africa (B.1.351) and Brazil (P.1). No serious adverse effects were reported in vaccinated animals. Also, very favorable interim phase 1 clinical data in humans were released by the company early this month.

Meantime, CITF-funded researcher Dr. Donald Vinh from McGill University and the Research Institute of the McGill University Health Centre (RI-MUHC), collaborated on a pre-print that summarizes the initial results of the Phase 2 trial for Quebec City-based Medicago’s COVID-19 vaccine. The preprint states that the plant-based vaccine against COVID-19 is showing promising antibody results in hundreds of participants in a phase 2 trial.2

In this trial, one-third of the volunteers were healthy adults between 18 and 64, one-third were over the age of 65, and the remaining third were adults with existing health conditions that could put them at higher risk of severe outcomes if infected with COVID-19. Only results for healthy adults are being reported at this time, while the results for those with existing health conditions are still to come.

The overall reported adverse reactions to the vaccine were mild and very short-lived. After the first dose, adults between 18 and 64 had a more robust immune response than seniors over 65, but both groups showed similar levels of antibodies after the second dose. A cellular immune response was observed in both age groups and that response was boosted after the second dose of the vaccine. As shown with other vaccines, Medicago’s vaccine appears to produce 10 times the antibodies in people who have had COVID-19 when compared to naïve individuals.

A phase 3 trial of the Medicago vaccine with 30,000 volunteers is already underway in Canada, the United States, the United Kingdom, and Brazil. Optimistically, this summer, the results from this phase 3 trial will be reviewed by Health Canada to decide whether or not to approve this vaccine.

If approved, the Medicago vaccine will likely be the first COVID-19 vaccine produced in Canada. The bulk material will be initially manufactured at Medicago’s North Carolina facility, as the manufacturing plant in Quebec is still under construction.  Either way, the vaccine vials are filled in Canada and finished with the GlaxoSmithKline adjuvant (additive that helps enhance the immune response to the vaccine). Canada signed a deal in October 2020 to buy 20 million doses of the Medicago vaccine, with an option for 56 million more. As most Canadians are expected to receive at least one vaccine dose before Medicago’s shot is approved, this Canadian vaccine could be used as the second dose in a ‘mixing and matching’ regimen. Alternatively, they could be donated to the global COVAX vaccine-sharing alliance.

 

References:

  1. Liu J, Budylowski P, Samson R, Griffin BD, Babuadze G, Rathod B, Colwill K, Abioye JA, Schwartz JA, Law R, Yip L, Kyun Ahn S, Chau S, Naghibosadat M, Arita Y, Hu Q, Yun Yue F, Banerjee A, Mossman K, Mubareka S, Kozak RA, Pollanen MS, Martin Orozco N, Gingras AC, Marcusson EG, Ostrowski MA. Preclinical evaluation of a SARS-CoV-2 mRNA vaccine PTX-COVID19-B. bioRxiv. 2021 May 12. doi: 10.1101/2021.05.11.443286.
  2. Gobeil P, Pillet S, Séguin A, Boulay I, Mahmood A, Vinh DC, Charland N, Boutet P, Roman F, Van Der Most R, Ceregido Perez MA, Ward BJ, Landry N. Interim report of a phase 2 randomized trial of a plant-produced virus-like particle vaccine for Covid-19 in healthy adults aged 18-64 and older adults aged 65 and older. medRxiv. 2021 May 17. doi: 10.1101/2021.05.14.21257248.