By Joseph Walker 

Regeneron Pharmaceuticals Inc.'s experimental Covid-19 drug helped reduce virus levels and improve symptoms in sick patients who weren't hospitalized, the company said, advancing development of a medication that could be among the first to treat early-stage illness from the new coronavirus.

The preliminary results from the company's clinical trial could support an emergency use authorization, or EUA, from U.S. regulators, said George D. Yancopoulos, Regeneron president and chief scientific officer, on a conference call with analysts on Tuesday. That may allow the drug to be prescribed before clinical trials are completed showing it is safe and effective.

"The totality of the data and the way it all hangs together really suggests we're impacting viral load," Dr. Yancopoulos said on the call. "It's up to regulators and society to decide" whether and when to make it available more widely to patients, he said. One possibility is that regulators ask the company to confirm the results with an analysis of patients that it has subsequently enrolled in the trial, he added.

Regeneron's drug, code-named REGN-COV2, is part of a class of medicines known as monoclonal antibodies that are designed in labs to mimic the naturally occurring antibodies that the immune system produces to fight off viruses and other foreign invaders. A rival antibody drug in development by Eli Lilly & Co. recently showed encouraging but mixed results in a Phase 2 trial of nonhospitalized patients.

So far, only a few drugs have been shown to work against Covid-19 and only in hospitalized patients. Regeneron is among a number of companies racing to develop effective treatments that can be used before patients become severely ill.

Shares of Regeneron rose 2% in after-hours trading; the stock is up more than 50% so far this year, largely on high expectations for the antibody drug.

The company's Covid-19 drug was most effective in treating patients who hadn't yet developed an effective immune response, which researchers measured by testing patients for antiviral antibodies before beginning treatment, and in patients with high virus levels in their respiratory systems.

The median number of days it took to alleviate symptoms in patients without antibodies was eight days among those who received the highest dose of the drug, six days in those who received the lowest dose, and 13 days in patients who were given placebos, Regeneron said.

In patients without coronavirus antibodies, the reduction in viral load across both doses of Regeneron's drug, compared with placebo, would have been statistically significant if it were a preplanned analysis, the company said.

The study data showed that patients who have low levels of virus, or who have already mounted an immune antibody response, are unlikely to benefit from the drug, Dr. Yancopoulos said in an interview. "If you're mounting an immune response, you're wiping out the virus," he said.

"The greatest treatment benefit was in patients who had not mounted their own effective immune response, suggesting that REGN-COV2 could provide a therapeutic substitute for the naturally-occurring immune response," Dr. Yancopoulos said in a statement. "These patients were less likely to clear the virus on their own, and were at greater risk for prolonged symptoms."

Write to Joseph Walker at


(END) Dow Jones Newswires

September 29, 2020 19:42 ET (23:42 GMT)

Copyright (c) 2020 Dow Jones & Company, Inc.
Regeneron Pharmaceuticals (NASDAQ:REGN)
Historical Stock Chart
From Sep 2020 to Oct 2020 Click Here for more Regeneron Pharmaceuticals Charts.
Regeneron Pharmaceuticals (NASDAQ:REGN)
Historical Stock Chart
From Oct 2019 to Oct 2020 Click Here for more Regeneron Pharmaceuticals Charts.