Regeneron says antibody therapy prevents COVID-19 infections

Regeneron Pharmaceuticals is planning to ask the Food and Drug Administration (FDA) to allow its antibody cocktail to be used as a preventive treatment for COVID-19, the company said Monday.

New results from a clinical trial conducted with the National Institute of Allergy and Infectious Diseases found the drug reduced the risk of symptomatic infection by 81 percent in people who were not infected at the start of the trial, Regeneron said.

The company has already received emergency use authorization from the FDA to use its antibody drugs to treat adults with mild to moderate COVID-19 and pediatric patients at least 12 years old who have tested positive for the virus and are at high risk of severe disease but are not yet hospitalized.

The trial enrolled 1,505 people who were not infected with the virus but lived in the same household as someone who recently tested positive. The patients were randomized to receive either one dose of the antibody therapy or a placebo administered as injections.

After 29 days, 11 people out of the 753 who received a single 1,200 mg dose of the treatment developed symptomatic COVID-19; 59 people who received a placebo out of 752 participants developed symptomatic COVID-19. 

The drug provided 72 percent protection against symptomatic infections in the first week and 93 percent protection in subsequent weeks, Regeneron said. The data has not yet been peer reviewed or published.

Regeneron also said the trial found individuals treated with the therapy who experienced a symptomatic infection resolved their symptoms in one week, compared to three weeks with placebo. 

Infected individuals also cleared the virus faster with the therapy, the company said.

Adverse events occurred in 20 percent of patients who received the antibody drug and 29 percent of those who received a placebo, Regeneron said, but nobody withdrew from the trial because of them.

None of the participants who received the therapy were hospitalized or went to the ER because of COVID-19 over the course of 29 days; four in the placebo group did so. 

There were four deaths in the trial — two in the therapy group and two in the placebo group — but none were reported due to COVID-19 or the drug.

“With more than 60,000 Americans continuing to be diagnosed with COVID-19 every day, the REGEN-COV antibody cocktail may help provide immediate protection to unvaccinated people who are exposed to the virus, and we are also working to understand its potential to provide ongoing protection for immunocompromised patients who may not respond well to vaccines,” George Yancopoulos, president and chief scientific officer at Regeneron, said in a statement.

The trial tested the antibody treatment for use as a “passive vaccine,” which involves directly injecting antibodies into the body. Traditional vaccines rely on a person’s immune system to activate and develop its own antibodies.

That means the treatment may provide immediate benefits, in contrast to active vaccines, which take weeks to provide protection. In addition, using injections rather than an infusion could make administering it more convenient than the currently authorized use for antibody drugs. 

While much of the attention has been focused on vaccines, experts say therapeutic treatments are just as important to ending the pandemic, which has killed more than 562,000 Americans.