Two Ebola treatments prove highly effective in a clinical trial | Science News for Students

Two Ebola treatments prove highly effective in a clinical trial

The ongoing field experiment in Congo will now focus on only the top-performing therapies
Aug 20, 2019 — 6:45 am EST
a photo of a doctor putting on protective gear

In the Congolese city of Beni, a doctor dons protective gear prior to seeing patients with possible Ebola infections. Early reports from a clinical trial in Congo are now in. They found that two drugs were highly effective at preventing death from the disease.

Vincent Tremeau/World Bank/Flickr (CC BY-NC-ND 2.0)

Doctors and scientists have been testing four treatments for Ebola in a clinical trial. That trial has taken place amid an ongoing outbreak in the Democratic Republic of Congo. Two of those treatments have proven to be effective in preventing death, preliminary data now suggest.

The recent Ebola outbreak began August 1, 2018, in the central African nation of Congo. The drug trial began in November. Participants were randomly given one of four experimental treatments. Three were antibody treatments: mAb114, REGN-EB3 and ZMapp. (Antibodies are proteins that the immune system harnesses to help fight germs and other "foreign" materials.) The other treatment was an antiviral drug, remdesivir.

Researchers reviewed data from 499 treated patients on August 9. That review suggests that those people taking mAb114 or REGN-EB3 had a greater chance of survival than those on the remdesivir or ZMapp. Researchers reported the trial results in a news release August 12. However, these findings have yet to be finalized.

“One thing that won’t change [after more study] is that those two therapies are better than the other two — that’s for sure,” says Anthony Fauci. Fauci is director of the National Institute of Allergy and Infectious Diseases. It’s part of the National Institutes of Health in Bethesda, Md. The trial now enters a phase with only the two most effective treatments. Researchers will gather more data on the treatments’ safety and the immune response to each drug. They won’t study enough patients, however, to see which drug works best.

Twenty-nine percent of the patients taking REGN-EB3 died. Among those taking mAb114, 34 percent died. That’s a big improvement over the current 67 percent mortality rate reported for Congo’s outbreak. (Regeneron Pharmaceuticals Inc. makes the REGN-EB3 therapy. Regeneron is a major financial supporter of the Society for Science & the Public. This nonprofit also publishes Science News for Students.)

Results were even better for patients with a low viral load, meaning those with less of the virus in their blood. A low viral load may indicate their infections were caught early. Among such patients, 6 percent taking REGN-EB3 died. Eleven percent of those on mAb114 died.   

The ZMapp antibody treatment showed promise when it was tested briefly on people during 2014. At that time, Ebola had spread through several nations in West Africa. In the new trial, ZMapp was considered the key comparison, or control, group. In the ZMapp group, 49 percent of patients died. Among low-viral load patients on ZMapp, 24 percent succumbed to the disease, Fauci says. Results for remdesivir were slightly worse than for ZMapp.

Antibody treatments provide the immune system with an immediate supply of antibodies that can target a virus. The mAb114 therapy is made of a single antibody cloned from an Ebola survivor of a 1995 outbreak. REGN-EB3 is a cocktail of three antibodies.

The World Health Organization, or WHO, declared Congo’s Ebola outbreak a public health emergency on July 17. Officials say there is a high risk that the disease could spread to neighboring countries. By August 10, the outbreak had killed 1,888 of the 2,816 people who had been reported as infected, WHO says. 

Power Words

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antibody     Any of a large number of proteins that the body produces from B cells and releases into the blood supply as part of its immune response. The production of antibodies is triggered when the body encounters an antigen, some foreign material. Antibodies then lock onto antigens as a first step in disabling the germs or other foreign substances that were the source of those antigens. 

antiviral     A virus-killing substance prescribed as a medicine.

clinical     (in medicine) A term that refers to diagnoses, treatments or experiments involving people.

clinical trial     A research trial that involves people.

control     A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that gives scientists something against which they can compare their experimental data.

data     Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

Ebola     A family of viruses that cause a deadly disease in people. All cases have originated in Africa. Its symptoms include headaches, fever, muscle pain and extensive bleeding. The infection spreads from person to person (or animal to some person) through contact with infected body fluids. The disease gets its name from where the infection was first discovered in 1976 — communities near the Ebola River in what was then known as Zaire (and is now the Democratic Republic of Congo).

immune     (adj.) Having to do with the immunity. (v.) Able to ward off a particular infection. Alternatively, this term can be used to mean an organism shows no impacts from exposure to a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.

immune system     The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

infection     A disease that can spread from one organism to another. It’s usually caused by some type of germ.

infectious     An adjective that describes a type of germ that can be transmitted to people, animals or other living things.

mortality     Deaths. From mortal, meaning deadly.

National Institutes of Health     (or NIH) This is the largest biomedical research organization in the world. A part of the U.S. government, it consists of 21 separate institutes — such as the National Cancer Institute and the National Human Genome Research Institute — and six additional centers. Most are located on a 300 acre facility in Bethesda, Md., a campus containing 75 buildings. The institutes employ nearly 6,000 scientists and provide research funding to more than 300,000 additional researchers working at more than 2,500 other institutions around the world.

outbreak     The sudden emergence of disease in a population of people or animals. The term may also be applied to the sudden emergence of devastating natural phenomena, such as earthquakes or tornadoes.

pharmaceuticals     Medicines, especially prescription drugs.

preliminary     An early step or stage that precedes something more important.

therapy     (adj. therapeutic) Treatment intended to relieve or heal a disorder.

virus     Tiny infectious particles consisting of RNA or DNA surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as live or dead, in fact no virus is truly alive. It doesn’t eat like animals do, or make its own food the way plants do. It must hijack the cellular machinery of a living cell in order to survive.

World Health Organization     An agency of the United Nations, established in 1948, to promote health and to control communicable diseases. It is based in Geneva, Switzerland. The United Nations relies on the WHO for providing international leadership on global health matters. This organization also helps shape the research agenda for health issues and sets standards for pollutants and other things that could pose a risk to health. WHO also regularly reviews data to set policies for maintaining health and a healthy environment.