AN A small biotechnology company has said it will start testing an experimental Covid-19 vaccine in humans that it hopes will be able to target potential strains of the SARS-CoV-2 virus that could escape current vaccines – if such strains exist and become a problem. .
“We all hope this is not necessary,” said Andrew Allen, the company’s CEO, Gritstone Oncology, in an interview with STAT. “I think it is prudent to have developed as a backstop. We all talk about preparing for a pandemic. So that’s what this is about. “
“We have a good vaccine that is bringing benefits in the short term, but we need to be ready for scenarios where these vaccines lose effectiveness, because this has historically been seen many times and we must be ready for it and not be discovered again,” said Allen.
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It is not clear whether this shot will be necessary. But the effort, though a long shot, is evidence of the deep well of pharmaceutical research that supports the vaccine effort.
The 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 an important player. The company went public in September 2018, raising $ 100 million. The stock reached $ 28 before dropping to its current $ 6.39, as investors were less enthusiastic about the prospects for the company’s strategy of using vaccine technology to develop cancer immunotherapies. It currently has a market capitalization of just $ 300 million.
The company’s effort joins an already robust dissemination of Covid-19 vaccine research. The World Health Organization has 64 such projects under development. Two vaccines, one from Pfizer and partner BioNTech and the other from Moderna, have been released for emergency use in the US so far.
But Allen said the emergence of a new variety in South Africa helped to convince the company that it was 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 found later in Brazil – called E484K – helped the virus to dodge the protective antibodies that are sometimes generated after an initial infection.
This week, scientists in South Africa reported that antibodies to some of those previously infected failed to recognize 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 directed against what is known as the protein spike, a tool that SAR-CoV-2 uses to cling to cells. Gritstone’s goal would be for its vaccine to create an innate immune response to other antigens in the virus, making it even more difficult to escape.
Gritstone’s approach combines two different types of vaccines. The first dose would be an adenovirus-based vaccine, a group of viruses that can cause cold-type illnesses. This is similar to the vaccines being developed by Johnson and Johnson and, separately, by the team at Oxford University 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, much like the vaccines developed by Moderna and the team at Pfizer and BioNTech.
A completely new vaccine is not the only way to fight a new variant. An alternative strategy would be to rapidly produce new versions of existing vaccines, such as those from Moderna or Pfizer / BioNTech, to combat a new strain.
One difficulty in developing any new vaccine is to test it. The first crop of Covid-19 vaccines was tested against placebo in massive clinical trials of 30,000 volunteers or more. But next year, most people will be vaccinated. And with a vaccine available, it may be unethical to conduct placebo-controlled studies.
The researchers have not yet decided 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 Vaccine Development Center at the University of Saint Louis and principal investigator of the COVID study at Gritstone, said that large clinical trials may be needed, potentially testing the vaccine against one of the approved vaccines to see if the new vaccine was approximately equivalent, or not inferior. This can go a long way.