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As Ebola drug review starts, Regeneron hopes to chart similar path for coronavirus therapy

The Food and Drug Administration has agreed to quickly review an experimental therapy for Ebola virus infections developed by Regeneron, setting an approval decision deadline of Oct. 25 for the New York biotech’s antibody-based treatment.REGN-EB3, as Regeneron calls it, is backed by results from a study of four drug regimens conducted during the 2018 outbreak of Ebola virus in the Democratic Republic of Congo.

Testing was stopped early after an interim look at the data showed study participants with Ebola were living longer on REGN-EB3 and another treatment, called MAb114. The FDA designated REGN-EB3 as both an Orphan Drug and Breakthrough Therapy, programs which allow for closer collaboration and give Regeneron regulatory and financial incentives. Development was funded in part by the U.S. Biomedical Advanced Research and Development Authority, or BARDA.

In announcing the FDA’s fast review, Regeneron compared the research it’s now doing on a treatment for COVID-19 to the steps it took in designing, developing and testing REGN-EB3.

“Regeneron is now applying this same approach to develop an antibody medicine that can potentially prevent and treat COVID-19, with initial clinical trials expected to begin in June,” said George Yancopoulous, the biotech’s outspoken chief scientific officer, in a statement.

The development of a COVID-19 therapy playing out similarly would be good news. But the years-long process of getting REGN-EB3 to the FDA’s desk hints at potential challenges, too.

Regeneron initially developed REGN-EB3, which consists of three antibodies, in response to an outbreak of Ebola in West Africa four years before the study that would prove the treatment’s benefit.

During that 2014 Ebola outbreak, which hit Guinea, Liberia and Sierra Leone the hardest, Regeneron was able to produce the antibodies that compose REGN-EB3 in just six months and test them in healthy volunteers soon after.

But by the time Regeneron was ready for further testing, the outbreak had passed. Regeneron kept its antibodies at the ready so when Ebola emerged in the DRC, the company was ready to advance its drug regimen into clinical tests of infected people.

Similar time pressures could be at play with COVID-19 too. Two studies in China of Gilead’s experimental antiviral remdesivir, which was also tested in the four-drug Ebola study that featured REGN-EB3, were recently terminated due to low enrollment as case numbers in China have fallen rapidly.

Public health officials believe SARS-CoV-2, the virus which causes COVID-19, is here to stay, with new outbreaks potentially occurring in the future even if the current pandemic is curbed. But Regeneron, and its government partners, will still need to be ready for a fast-spreading disease and plan for trial sites to be ready in areas where cases are surging.

A proliferation of clinical studies of potential COVID-19 treatments could also complicate matters, although a public-private effort to better coordinate and plan testing of the most promising therapies is reportedly being planned in the U.S.

BARDA, which supported Regeneron’s Ebola development, is also working with the company on its COVID-19 research.

Should REGN-EB3 be approved on time, roughly one year will have passed from when it stopped the supportive study. In that trial, treatment with REGN-EB3 kept nearly two-thirds of 155 treated patients alive after 28 days, a higher rate than what was observed among study participants given a drug called ZMapp and Gilead’s remdesivir. The fourth therapy, developed by the National Institutes of Health and dubbed MAb114, worked similarly well as REGN-EB3.

The FDA recently approved an Ebola vaccine from Merck & Co. as well.