A crucial group of Covid drugs has stopped working

 

The changing nature of the virus also makes it difficult to conduct human clinical trials and get a new antibody to patients in time to work against current variants. AT see you in december, drugmakers have asked U.S. and European regulators to consider adopting new standards for approving new antibody-based drugs, especially those for immunocompromised people. 

 

They suggested that new antibody-based drugs similar to those previously approved should not have to go through large clinical trials to test their effectiveness. Instead, extensive lab testing and small safety trials, like what is done for the annual flu shot, may suffice. 

 

Researchers are now looking for the holy grail of antibodies, one that would be more durable and 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 company to partner with that could further develop these antibodies and test them in clinical trials. The group previously partnered with AstraZeneca, which marketed Evusheld. 

 

Scientists at Regeneron Pharmaceuticals, the New York-based biotech company that made one of the monoclonal antibody treatmentshave identified an antibody that binds to a region out the receptor binding domain. “We were able to identify an antibody against a site of the virus that is highly conserved,” meaning that part of the virus hasn’t changed much, says Christos Kyratsous, who leads infectious disease research at Regeneron. “It has been kept since the start of the pandemic until today. It is a very rare antibody because unlike other antibodies that bind to these conserved sites, it is extremely potent. 

 

And that gives him hope that lab-made antibodies developed to recognize this site will continue to work, even if the virus’ receptor-binding domain continues to mutate in the future. Still, Kyratsous says there’s often a trade-off between breadth and power. There may be many antibodies that bind to many variants but do not neutralize them well. So far, this one seems to do both. In clinical trials this summer, Regeneron plans to test the antibody as both a prophylaxis and a treatment for Covid-19.

 

In December, AstraZeneca began testing a potential Evusheld replacement in immunocompromised patient trials. 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 shown to be resistant to other monoclonal antibodies, according to a January company statement. AstraZeneca has announced plans to make the new antibody available in the second half of 2023, pending regulatory approval. The company estimates that around 2% of the world’s population could benefit from monoclonal antibodies for protection against Covid-19.

 

For the rest of the population, Adarsh ​​Bhimraj, an infectious disease physician at Houston Methodist Hospital in Texas, thinks our current vaccines and antivirals will suffice. “We are not in 2020, where we have no medicine and the pandemic is causing many deaths and hospitalizations,” he says. 

 

He says there should be a higher bar for getting antibodies approved for treating Covid-19 now that effective antivirals are available and death and hospitalization rates are falling. He thinks drugmakers should be able to show that new antibodies can lessen symptoms and shorten the duration of illness, rather than just stopping people from going to hospital. “What matters to patients should be studied in trials,” he says.

 

For now, the FDA recommends that clinics and hospitals keep existing monoclonal antibodies on hand in case variants susceptible to them reappear in the United States. “Although monoclonal antibodies may not work at the moment, there is always the possibility that circulating Covid-19 variants will change, so that monoclonal antibodies will work again in the future,” says Wales. “We do not know yet.”

 

 

Source:   Wired