An antibody cocktail designed to prevent and treat COVID-19 is now entering late-stage clinical trials, according to reports.
When naturally infected with COVID-19, the body generates Y-shaped molecules called antibodies that latch onto the virus and mark it for destruction, or hinder its ability to infect healthy cells, Live Science previously reported. These antibodies can be drawn from recovered COVID-19 patients and injected into sick patients to bolster their immune systems against the virus, a treatment known as convalescent plasma therapy.
But convalescent plasma therapy has its limitations; plasma donations from different patients contain different mixtures of antibodies, and some antibodies may target COVID-19 more effectively than others, according to a report published in June in the Journal of Clinical Virology. For instance, some antibodies directly prevent the virus from entering cells in the first place — so-called neutralizing antibodies — while others may not prevent infection, but instead direct other immune molecules to destroy infected cells.
To overcome this limitation, and avoid relying on a limited supply of plasma, several drug developers have turned to monoclonal antibodies — antibodies carefully selected for their ability to target specific pathogens, such as SARS-CoV-2, and then mass-produced in a lab.
Now, one such therapy, known as REGN-COV2, has entered Phase 3 clinical trials to evaluate whether the treatment can prevent COVID-19 infection among healthy people who have had close contact with an infected person, such as a housemate, according to ClinicalTrials.gov. In the trial, 2,000 participants at 100 sites across the U.S. will receive either the drug or a placebo, and the results will show how well the drug works compared with the placebo medication, and if there are any safety concerns that pop up, according to a statement from Regeneron Pharmaceuticals, the biotechnology company that developed the drug. The trial will be jointly run with the National Institute of Allergy and Infectious Diseases (NIAID).
REGN-COV2 contains two antibodies that latch onto and help to neutralize the coronavirus, hampering its ability to infect healthy cells, according to the statement. The two antibodies bind to the virus's spike protein, a structure that juts from the surface of the pathogen and plugs into cells to trigger infection. Regeneron scientists found the two antibodies by studying genetically modified mice with human-like immune systems and antibodies collected from human COVID-19 patients.
The Phase 3 trial will monitor how many participants contract COVID-19 within a month of treatment, using viral genetic tests and evaluations of participants' symptoms, according to ClinicalTrials.gov. Participants will continue to be monitored for infections, hospitalizations and related medical complications for up to eight months post-treatment, as well as any side effects linked to the drug itself.
While the Phase 3 trial assesses REGN-COV2 as a preventative therapy, the drug will also be tested as a treatment for patients already ill with COVID-19. In two Phase 2/3 clinical trials, one for hospitalized patients and one for non-hospitalized patients, the researchers will assess whether the drug reduces the amount of virus shed by infected individuals and improves clinical outcomes, as compared with a placebo. The Phase 2/3 trials will include 850 hospitalized patients and 1,050 non-hospitalized patients at 150 sites in the U.S., Brazil, Mexico and Chile.
"We are running simultaneous adaptive trials in order to move as quickly as possible to provide a potential solution to prevent and treat COVID-19 infections, even in the midst of an ongoing global pandemic," Dr. George Yancopoulos, Co-Founder, President and Chief Scientific Officer of Regeneron, said in the statement.
In addition to Regeneron, the pharmaceutical companies Eli Lilly and AbCellera are currently evaluating antibody treatments against COVID-19 in human trials, CNN reported.
If the FDA approves the drug at the end of Phase 3 trials, REGN-COV2 would then move on to the last phase called Phase 4, during which the drug could enter widespread use and its short- and long-term effects would be monitored in thousands of patients.
Originally published on Live Science.