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Infectious disease


Regeneron offers early look at COVID-19 antibody cocktail data

The drug appears to lower viral load in a subset of patients, but its use could be limited

by Lisa M. Jarvis , Megha Satyanarayana
September 30, 2020 | A version of this story appeared in Volume 98, Issue 38


A photo of a scientist standing next to a bioreactor in a room full of bioreactors.
Credit: Regeneron
Regeneron Pharmaceuticals' preclinical manufacturing lab, where early-stage antibodies are made in bioreactors

Regeneron Pharmaceuticals has offered a first glimpse at data from closely watched studies of REGN-COV2, its antibody therapy for COVID-19. Although not a home run, the results do provide insight into where antibodies might fit into the treatment landscape for the deadly respiratory disease.

Regeneron scientists developed REGN-COV2 by exposing genetically engineered mice to the spike protein, which the coronavirus that causes the disease uses to latch onto human cells before dumping its genetic payload inside. The team sifted through the thousands of antibodies the mice produced in response to the protein, as well as antibodies produced by people who had recovered from COVID-19, to find the best neutralizing ones—antibodies that both bind the virus and prevent it from entering human cells.

The end result was a mix of two antibodies that bind in different ways to the receptor binding domain—a patch on the spike protein that locks into the ACE receptor on human cells.

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Regeneron began clinical trials of the treatment in June, eventually enrolling some 2,000 people.

The first swath of data came from 275 people whose infection had not yet put them in the hospital. In a call with investors and reporters, Regeneron cofounder and chief scientific officer George D. Yancopoulos explained that the drug was most effective in people whose immune systems were not yet kicking in to produce antibodies to clear the virus, what are called seronegative patients. In that subset, the drug swiftly knocked down the virus and appeared modestly effective at slowing the progression of the disease.

The question now is whether that is enough for the US Food and Drug Administration to grant the drug emergency use authorization (EUA), which, while not a full approval, would allow it to be used amid the pandemic.

“The EUA is possible” for both Regeneron’s cocktail and a similar one in development by Eli Lilly and Company, says Myron Cohen, an infectious disease doctor at the University of North Carolina and head of the COVID Prevention Network. “Both companies will have to make their cases for who to give the treatment to initially.”

The population that would reasonably benefit from the drugs could be narrow. Because the study was in people with relatively mild disease, the value “is probably more as proof of concept” that antibodies can suppress the virus, says Jeffrey Henderson, an infectious diseases specialist at Washington University Medical School. If deployed, it could help, for example, stem an outbreak at a nursing home or treat people at high risk for developing serious disease.

SVB Leerink stock analyst Geoffrey Porges told investors in a note that “it will be difficult for the FDA to resist” granting REGN-COV2 an EUA. But actually giving the drug to people who have early symptoms but aren’t hospitalized—the group treated in the study—“would be an impossible task.” He said regulatory authorities will want to see data from hospitalized patients.

Another challenge will be identifying seronegative COVID-19 patients. “If the decision is going to be made to deploy such a therapeutic solution in patients who might benefit the most and need it the most, we’re going to have to solve the problem of using the right point-of-care diagnostic tools,” Yancopoulos said. Regeneron is working with Roche to develop tools to detect whether people have developed their own antibodies against the virus or have a high viral load.


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