A a small biotechnology firm has said it will launch an experimental human-tested Covid-19 vaccine, hoping it could target potential strains of the SARS-CoV-2 virus that could evade current vaccines – if such strains ever exist and can become a problem.
“We all hope it will not be necessary,” Gritstone Oncology CEO Andrew Allen said in an interview with STAT. ‘I think it’s wise to let it develop as a backstop. We all talk about preparedness. So that’s what this’s about. ”
‘We have a good vaccine that can benefit in the short term, but we need to be ready for scenarios where the vaccines are no longer effective, because it has been seen many times historically and we need to be ready for it and not short again. . , ”Allen said.
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It is not clear if such a shot is needed. But the effort, though a long shot, is proof of the deep pit of pharmaceutical research that supports the vaccine effort.
Preclinical work on the vaccine is 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 vaccine candidate. There is no publicly available data on the preclinical research.
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Gritstone is hardly a major player. The company was announced in September 2018 and raised $ 100 million. Shares traded up to $ 28 before dropping to their current $ 6.39 as investors became less excited about the outlook for the company’s strategy to use vaccine technology to develop cancer immunotherapies. It currently has a market capitalization of just $ 300 million.
The company’s effort joins an already strong distribution of Covid-19 vaccine research. The World Health Organization counts 64 such projects in development. Two vaccines, one from Pfizer and partner BioNTech and another from Moderna, have so far been cleared for emergency use in the US.
Allen said that the emergence of a new species in South Africa helps convince the company that it is important to develop its own version. In laboratory 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 to evade the protective antibodies that sometimes go to a initial infection occurs.
This week, scientists in South Africa reported that antibodies from some of those previously infected could not recognize the newer variant. There are still no results on how the variant interacts with antibodies produced after vaccination.
Allen noted that current vaccines are all targeted at what is known as the peak protein, a tool that SAR-CoV-2 uses to wipe cells. Gritstone aims for the vaccine to create an innate immune response to other antigens in the virus, making it even more difficult for the virus to evade.
The Gritstone approach combines two different types of vaccines. The first dose is a vaccine based on adenovirus, a group of viruses that can cause colds. It is similar to the vaccines developed by Johnson and Johnson, and separately by the team from the University of Oxford and AstraZeneca. The virus is used to introduce a gene into cells, which then produces 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 from Pfizer and BioNTech.
A brand new vaccine is not the only way to combat a new variant. An alternative strategy would be to quickly produce new versions of existing vaccines, such as those from Moderna or t Pfizer / BioNTech, to combat a new strain.
One problem with developing a new vaccine is testing it. The first crop of Covid-19 vaccines has been tested against placebo in giant clinical trials of 30,000 volunteers or more. But in the coming year, most people will be vaccinated. And if a vaccine is available, it may no longer be ethical to conduct placebo-controlled studies.
Researchers have not yet decided on the use of other criteria, such as 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 Saint Louis University’s Center for Vaccine Development and lead investigator of the Gritstone COVID study, said major clinical trials would be needed to test the vaccine against one of the approved vaccines to see if the new vaccine is approximately equal, or non-inferior. It can be a long road.