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A A small biotech company has said it will start testing in humans an experimental Covid-19 vaccine which it hopes can target potential strains of the SARS-CoV-2 virus that could escape current vaccines – if such strains ever exist and become a problem.
“We all hope it won’t be necessary,” said Andrew Allen, CEO of Gritstone Oncology, in an interview with STAT. “I think it’s safe to develop it as a safety net. We are all talking about pandemic preparedness. So that’s what it is.
“We have a good vaccine that brings short-term benefits, but we have to be prepared for scenarios where these vaccines lose their effectiveness, because this has historically been observed time and time again and we should be ready for it and not be caught off guard again. Allen said.
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It is not known whether such a move will be necessary. But the effort, while long-drawn, is evidence of the deep well of pharmaceutical research supporting the vaccination effort.
Preclinical work on the vaccine was supported by the Bill and Melinda Gates Foundation. A phase 1 clinical trial will be conducted by the National Institute of Allergy and Infectious Diseases, with Gritstone paying for the production of the candidate vaccine. There is no publicly available data on preclinical research.
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Gritstone is hardly a major player. The company went public in September 2018, raising $ 100 million. The shares traded as high as $ 28 before falling to current $ 6.39 as investors became less excited about the prospects for the company’s strategy of using vaccine technology to develop immunotherapies against cancer. It currently has a market cap of just $ 300 million.
The company’s effort joins an already robust dissemination of research on the Covid-19 vaccine. The World Health Organization has 64 such projects in development. Two vaccines, one from Pfizer and its partner BioNTech and another from Moderna, have so far been authorized for emergency use in the United States.
But Allen said the emergence of a new strain in South Africa helped convince the company of the importance of developing its own version. In lab experiments, one of the mutations present in the variant identified in South Africa and seen separately in another variant later found in Brazil – called E484K – helped the virus dodge the protective antibodies that are sometimes generated afterwards. an initial infection.
This week, scientists in South Africa reported that the antibodies of some of those previously infected were not recognizing the new variant. There are still no results on how the variant interacts with the antibodies produced after vaccination.
Allen noted that current vaccines are all targeted against what’s called the spike protein, a tool SAR-CoV-2 uses to find its way into cells. Gritstone is said to be aiming for his vaccine to create an innate immune response to other antigens in the virus, making it even more difficult to bypass the virus.
The Gritstone approach combines two different types of vaccines. The first dose would be a vaccine made from adenovirus, a group of viruses that can cause cold-like illnesses. This is similar to vaccines developed by Johnson and Johnson and, separately, by the team at the University of Oxford and AstraZeneca. The virus is used to introduce a gene into cells, which then produce proteins to which the immune system responds. But the second dose would be an mRNA vaccine, just like the vaccines developed by Moderna and the team at Pfizer and BioNTech.
A brand new vaccine is not the only way to fight a new variant. An alternative strategy would be to quickly produce new versions of existing vaccines, such as those from Moderna or Pfizer / BioNTech, to combat a new strain.
One of the challenges in developing a new vaccine will be testing it. The first crop of Covid-19 vaccines has been tested against a placebo in giant clinical trials of 30,000 or more volunteers. But in the coming year, most people will be vaccinated. And with a vaccine available, it may no longer be ethical to conduct placebo-controlled studies.
Researchers have yet to decide how to use other criteria, such as the antibody response created by a vaccine or the activity of immune cells called T cells, to predict whether a vaccine will work.
Daniel Hoft, director of the Center for Vaccine Development at Saint Louis University and principal investigator of the Gritstone COVID study, said large clinical trials may be needed, potentially testing the vaccine against one of the approved vaccines to see whether the new vaccine was roughly equivalent, or not inferior. It could be a long road.
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