First Ebola treatment approved by FDA

The US Food and Drug Administration has green-lighted Regeneron Pharmaceuticals’ antibody therapy Inmazeb to treat Ebola virus disease, making it the first approved treatment for the disease.

The approval, following that of Merck and Co.’s Ebola vaccine in 2019, gives clinicians a possible two-pronged approach to addressing outbreaks.

Having a treatment is a vital step in managing the disease, says Kartik Chandran, a virologist and Ebola antibody expert at Albert Einstein College of Medicine. Chandran is collaborating with Mapp Pharmaceutical on next-generation antibody treatments for Ebola disease.

“Emerging viruses like that are very difficult to vaccinate against,” Chandran says. “A treatment is an incredibly important public health policy weapon against emerging infections like this, especially ones with high fatality rates.”

Inmazeb is a mixture of three antibodies, dosed in equal amounts based on the weight of the infected person. Each of the antibodies sticks to a different spot on the Zaire ebolavirus glycoprotein, neutralizing the virus’s ability to infect. It’s most effective when given within the first 5 days of infection, says Sumathi Sivapalasingam, Regeneron’s senior medical director of early clinical development and experimental sciences.

Inmazeb was tested during the 2018 Ebola outbreak in the Democratic Republic of the Congo. In a large trial, the drug was able to clear virus from the blood 12 days earlier than ZMapp, a similar antibody cocktail from Mapp. The approval comes as Regeneron seeks an emergency use authorization for its COVID-19 antibody treatment, which was developed using the same technology as Inmazeb.

For infectious diseases, Regeneron scientists infect mice engineered to have nearly human immune systems with a virus that expresses the protein a pathogen uses to enter human cells. They isolate the antibody candidates from the mice best able to prevent an infection. The antibody mix blocks viral entry but also helps stimulate the natural immune system to kill infected cells, Sivapalasingam says.