Regeneron's COVID-19 antibodies breach a new frontier by cutting deaths in some hospitalized patients

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With an array of successful trials, Regeneron's COVID-19 antibody cocktail is gaining users. Wednesday's news that it can help hospitalized patients with no previous antibody response is another boost for the treatment.

Antibody treatments have shown little success in helping COVID-19 patients with  severe disease. But a large study of hospitalized patients reveals that Regeneron’s antibody cocktail can reduce the chance of death in patients who haven't produced their own antibody responses to the disease.

The 9,785-patient study, conducted in the U.K., showed that among those who produced no natural antibody response, REGEN-COV reduced the risk of death by 20%. The data could open up a new group of patients for the antibody cocktail, giving some new oomph to sales that have recently surged.

For patients who had developed antibodies, the treatment didn't work at all, suggesting that antibody testing would be useful for all hospitalized COVID-19 patients, trial investigator and Oxford professor Martin Landray told reporters in a conference call on Tuesday.

“People have been very, very skeptical that any treatment against this particular virus would work by the time people get to the hospital,” Landray said. “If you haven’t cleared the virus, if you haven’t raised antibodies of your own, you really would benefit from getting some in an infusion.”

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Additionally, among the same group of patients—known as seronegative for their lack of antibodies—REGEN-COV reduced the average hospital stay by four days and decreased the chance of a patient requiring a ventilator. 

“There are ways of testing the antibody levels,” Landray said. “The tests are relatively straightforward, but they’re not widely done because there hasn’t been much purpose to it. Now we’ve got a very definite purpose.”

The FDA granted REGEN-COV—a combination of monoclonal antibody treatments casirivimab and imdevimab—emergency authorization for patients with mild to moderate COVID-19 in November of last year. It was slow to gain acceptance because of its hefty price tag and the difficulty of getting patients with mild symptoms to leave home for infusion treatments.

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But with REGEN-COV performing well in other trials and recently receiving an expansion of its FDA green light to include a lower dose and the option of delivering it by subcutaneous injection, the drug has been gaining users. Regeneron plans to take the new data to the FDA for yet another expansion, R&D chief George Yancopoulos said in a statement.

Regeneron reported REGEN-COV sales of $262 million for the first quarter of this year. Some analysts believe the cocktail could hit $5 billion by year-end. In January, the company signed a deal to supply the United States up to 1.25 million doses. 

In the recent study, dubbed the Recovery Trial, half of the patients were given REGEN-COV and half received standard care. Roughly two-thirds of the patients were seropositive, the other third seronegative. The risk of death in those who were seropositive was 15% compared to 30% for those who were seronegative. But Regenron’s cocktail reduced that 30% figure by a fifth, to 24%. 

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COVID-19 patients, upon admission to the hospital, now should be tested for antibody levels, Landray said.

“You test the antibodies, just as you test the blood sugar, the blood pressure, the level of oxygen and everything else,” he said. “In the future it will just be one of those tests you run off to the lab.”  

The trial is another boost for Regeneron’s treatment, which also is under consideration as a preventative for COVID-19.