Regeneron to seek EUA for lower dose of Covid-19 mAb cocktail as new trial shows major drop in risk of hospitalization or death
The success of monoclonal antibody (mAb) cocktails in keeping people with Covid-19 out of the hospital continued Tuesday, with Regeneron announcing that even a lower-than-authorized dose of its combination of mAbs reduced hospitalization or death by 70% in non-hospitalized Covid-19 patients.

“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,” George Yancopoulos, president and CSO of Regeneron, said in a statement.
The placebo-controlled trial of more than 4,500 people showed how casirivimab and imdevimab reduced the risk of hospitalization or death by 70% for the 1,200 mg IV dose, and 71% for the authorized 2,400 mg IV version, when compared to placebo, the company said.
In addition, Regeneron said a dose-ranging Phase II trial of 815 non-hospitalized Covid-19 patients showed “significant and comparable viral reductions” for all doses tested of the mAb combo, including as low as 300 mg. A company spokesperson said further discussions with the FDA will be necessary to discuss subcutaneous administration, and “even lower dose possibilities in the future.”

Walid Gellad, director of the University of Pittsburgh Center for Pharmaceutical Policy and Prescribing, who’s unaffiliated with the results, said that they show yet another example of how effective these mAbs are for outpatient use to reduce hospitalization.
“Companies in a pandemic should be applauded for testing lower doses, which will extend supply,” he added.
Despite the positive new data, doses of the Regeneron and Eli Lilly mAb cocktails have been difficult to come by and states have had to grapple with figuring out new ways to administer the infusions.
A Regeneron spokesperson said the company so far has delivered nearly 300,000 doses to the US (although the government’s website still says it’s distributed about 150,000 as of early February). Beginning in April, Regeneron will deliver supplies of the mAb cocktail under its second contract with the US government, which will provide 750,000 or more doses by mid-year.
“Most recently we have said we expect to provide approximately 750,000 doses at the 2,400 mg dose level by June 30, but now we anticipate being able to provide more if the 1,200 mg dose is added to the EUA,” the spokesperson added.