Regeneron Pharmaceuticals Inc on Tuesday said its experimental two-antibody cocktail reduced viral levels and improved symptoms in non-hospitalized Covid-19 patients, enhancing its chances of becoming a treatment for the disease that has killed over a million people worldwide.
“We hope these data will support an EUA” (emergency use authorization) from the U.S. Food and Drug Administration, Regeneron Chief Scientific Officer George Yancopoulos said on a conference call.
The FDA can authorize emergency use of a drug before completing its review for a formal approval.
Shares of Regeneron, which closed at $573.61, were halted after hours.
Trial results for the first 275 patients showed the greatest effect in those who had not yet mounted their own immune response prior to treatment. That suggests the treatment, REGN-COV2, could help patients whose own immune system is not strong enough to combat the virus, Regeneron said.
REGN-COV2 is part of a class of biotech therapies known as monoclonal antibodies. Several companies are using the technology to manufacture copies of human antibodies to the new coronavirus.
Regeneron believes its dual-antibody formula will limit the ability of the virus to escape detection and attack.
The study tested two different doses of REGN-COV2 in two patient populations: those who had mounted an effective immune response on their own (seropositive), and those whose immune response was not yet adequate, or seronegative.
Among patients given a placebo, those who already had effective natural antibodies had a median time to alleviation of symptoms of 7 days, compared to 13 days for seronegative patients.
Among seronegative patients given the Regeneron cocktail, median time to symptom alleviation was 8 days for the high-dose group, and 6 days for the low-dose group.
Regeneron also said REGN-COV2 rapidly reduced viral load through day 7 in seronegative patients. In addition, patients with higher virus levels at the start of the trial had correspondingly greater reductions in viral load with REGN-COV2, which is given by intravenous infusion.
Serious adverse side effects occurred in two placebo patients and one patient who got the lower dose of REGN-COV2. There were no deaths in the trial.
The treatment is also being studied for use in hospitalized patients, and for prevention of infection in people who have been exposed to Covid-19.
The U.S. government in June awarded Regeneron a $450 million supply contract for the antibody cocktail.
Swiss drugmaker Roche Holding AG last month agreed to boost overall manufacturing capacity for REGN-COV2 by at least three and a half times. Under the deal, Regeneron would handle U.S. sales of the treatment and Roche would be responsible for the rest of the world.