The most important group of Covid drugs stopped working
The changing nature of the virus also makes it difficult to conduct human clinical trials and get new antibodies for patients in a timely manner so they can work against existing variants. IN meeting in December, drug makers have asked regulators in the US and Europe to consider adopting new standards for approving new antibody-based drugs, especially for immunocompromised people. They suggested that new antibody-based drugs similar to those previously approved should not be subjected to large clinical trials to test their effectiveness. Instead, extensive lab testing and small safety trials, such as what is done for the annual flu vaccine, may suffice.
Researchers are currently searching for the holy grail of antibodies that last longer and are more effective against many variants of SARS-CoV-2, including those that may emerge in the future. Carnahan’s team has identified what he calls a “small panel of antibodies” that, at least in the lab, work against all existing variants of Covid-19, including XBB.1.5. They are now looking for a collaborative company that could develop these antibodies and test them in clinical trials. The group previously partnered with AstraZeneca, which commercialized Evusheld.
Scientists at Regeneron Pharmaceuticals, a New York biotech company, one of the treatments with monoclonal antibodiesidentified an antibody that binds to the region outside receptor binding domain. “We were able to identify one antibody against a section of the virus that is very conserved,” meaning that that part of the virus hasn’t changed much, says Christos Kyratsous, head of infectious disease research at Regeneron. “It has persisted from the beginning of the pandemic until today. This is a very rare antibody because, unlike other antibodies that bind to these conserved sites, it is extremely effective.”
And that gives him hope that the lab-made antibodies designed to recognize this site will continue to work even as the virus’ receptor-binding domain continues to mutate in the future. However, Kyracus says there is often a trade-off between breadth and efficiency. There may be many antibodies that bind to many variants but do not neutralize them well. So far this one seems to do both. This summer, Regeneron plans to test the antibody in clinical trials as both a prevention and treatment for Covid-19.
In December, AstraZeneca began testing a potential replacement for Evusheld in studies of immunocompromised patients. In laboratory studies, the new long-acting antibody has been shown to neutralize all variants of SARS-CoV-2 tested to date, including variants that have been found to be resistant to other monoclonal antibodies. company statement for january. AstraZeneca says it intends to make the new antibody available in the second half of 2023, pending regulatory approval. The company estimates that about 2 percent of the world’s population could benefit from monoclonal antibodies to protect against Covid-19.
For the rest of the population, Adarsh Bhimraj, an infectious disease physician at the Houston Methodist Hospital in Texas, believes our current vaccines and antivirals will be sufficient. “This is not 2020 where we don’t have medicines and the pandemic is causing a lot of deaths and hospitalizations,” he says.
He says there should be a higher bar for getting antibodies approved for Covid-19 treatment now that effective antivirals are available and death and hospitalization rates have dropped. He believes drug makers need to show that new antibodies can relieve symptoms and shorten the duration of illness, not just keep people out of hospitals. “What is important to patients should be explored in trials,” he says.
For now, the FDA recommends that clinics and hospitals keep existing monoclonal antibody preparations on hand in case susceptible variants reappear in the US. “While monoclonal antibodies don’t work right now, there is always the possibility that the circulating Covid-19 variants will change, so monoclonal antibodies may work again in the future,” Wales says. “We don’t know that yet.