Regeneron’s coronavirus antibody cocktail is effective at treating mild to moderate cases of COVID-19, new late-stage trial results suggest.

The treatment is a mixture of drugs casirivimab and imdevimab, and was developed by the New York City-based company in partnership with pharmaceutical firm Roche.

Known as REGEN-COV, the cocktail imitates antibodies that the body generates when fighting the virus in order to boost the immune system.

In trial data released on Tuesday, Regeneron said the combination reduced the risk of hospitalization and death by 70 percent compared to a placebo in non-hospitalized patients.

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Both doses of Regeneron’s antibody cocktail were found to reduce the risk of hospitalization or death by about 70% in mild-to-moderate COVID-19 patients compared to a placebo

Regeneron’s cocktail, a mixture of two drugs, imitates antibodies that the body generates when fighting the virus to boost the immune system. Pictured:  An employee works in a lab at the Regeneron Pharmaceuticals Westchester campus in Tarrytown, New York, making the cocktail, September 2020

‘This is a landmark moment in the fight against COVID-19,’ said trial investigator Dr Suraj Saggar, Chief of Infectious Disease at Holy Name Medical Center in Teaneck, New Jersey, in a statement.

‘With so many people still getting infected…these data underscore the need to rapidly adopt REGEN-COV as standard-of-care to offer high-risk patients their best chance to reduce serious consequences like hospitalization or death.’

The U.S. Food and Drug Administration (FDA) approved the cocktail – which involves 1,200 milligrams (mg) of each drug – for emergency use in November.

However, the drugs have been chronically underused with the Department of Health and Human Services estimating in January that about 75 percent of doses purchased by the government were unused.

For the trial, researchers looked at 4,567 mild-to-moderate COVID-19 patients who were at high risk of developing severe illness.

A smaller group of 736 patients were given a smaller dose – 1,200 mg total, meaning the patients received 600 mg of each drug.

Only about one percent of patients given either dose developed COVID-19-related complications compared to about three percent in the placebo groups.

Both doses were found to reduce the risk of hospitalization or death with 70 percent in the smaller dose group and 71 percent in the larger dose group.

In addition, recovery time was shortened with symptoms only lasting about 10 days in the cocktail group in comparison with 14 days in the placebo group.

The results have yet to be published in a scientific journal and have not yet been reviewed by independent scientists.

‘With approximately 60,000 newly diagnosed individuals in the U.S. every day and 40,000 still in the hospital because of COVID-19, we are committed to working with the government, health care providers and others to support rapid and widespread adoption of REGEN-COV in appropriate patients,’ said Dr George Yancopoulos, Regeneron’s president and chief scientific officer, in a statement.

‘We will rapidly discuss the new data with regulatory authorities and request that the 1,200 mg dose be added to the U.S. Emergency Use Authorization, in order for the anticipated REGEN-COV supply to be available to treat even more patients.’

Regeneron’s partner, Roche, is making the drug at its plants in California and is responsible for sales outside the U.S.

The two companies have stated that they believe they can produce more than two million doses of the cocktail annually.