As the second-largest outbreak of the deadly Ebola virus reached its one-year mark in the Democratic Republic of the Congo, a group of public health organizations announced that researchers have finally found an effective treatment for the devastating sickness.
On August 9, a committee overseeing a clinical trial of four experimental therapeutics for Ebola determined that two relatively new antibody-based treatments were so effective that they would become the new standard of care. When these two treatments were administered within a day of infection, survival rates were around 90 percent. As the first Ebola trial to confirm a medical success, it’s a hopeful development. The Ebola virus, which hijacks the immune system and causes massive hemorrhaging, currently proves fatal for nearly 70 percent of patients.
“From now on, we will no longer say that Ebola is incurable,” Jean-Jacques Muyembe, a longtime Ebola researcher who now directs the D.R.C.’s National Institute of Biomedical Research, said in a conference call with reporters.
The clinical trial began last year in late November, four months after the first cases of Ebola were confirmed in the D.R.C. epidemic that has infected an estimated 2,800 people and killed more than 1,800. Patients of all ages who’d been diagnosed were given one of four treatments that experts at the World Health Organization approved for compassionate use. Because Ebola is so often fatal, the researchers ensured that every participant in the trial would receive some sort of promising treatment—no sugar-pill placebos.
The two treatments that proved most effective—the ones being billed as potential Ebola cures—are both one-time deliveries of antibodies. Antibodies are Y-shaped immune proteins that, in this case, recognize and bind to the Ebola virus, stopping it from entering and infecting a patient’s cells. As Megan Molteni writes for Wired, mAb114, a treatment developed by the N.I.H.’s National Institute of Allergy and Infection Diseases, is an antibody originally derived from the blood of a survivor of a 1995 Ebola outbreak in the D.R.C. (Now, according to W.H.O. documents, researchers use hamster ovary cells to make the antibodies.) The other high-performing treatment is Regeneron Pharmaceuticals’ REGN-EB3, a cocktail of three antibodies first generated using mice infected with the virus. As Molteni explains, the trifecta approach was developed to combat the Ebola virus’ large size and ability to change shape, which makes it more complicated for a single antibody to stop the illness on its own.
As of August 9, 681 patients had been enrolled in the trial. The results from 499 of those patients were staggering enough that they met the predetermined criteria to halt the trial—researchers had gotten an answer about what worked best. Overall, the mortality rate for patients treated with mAB114 was 34 percent, and 29 percent for REGN-EB3. When caretakers gave the patients these intravenous (IV) infusions within an estimated one day of infection, only 11 percent of mAB114 patients and 6 percent of REGN-EB3 patients died, reports Donald McNeil Jr. for the New York Times.
The other treatments, ZMapp and Remdesivir, were found to be less effective; when administered early, patient mortality rates totaled around 24 percent and 33 percent, respectively. Both options had been used to treat some patients in the 2014 outbreak, and ZMapp, which is a mixture of three antibodies developed using genetically-modified tobacco plants, had been administered to 72 people and had seemed “beneficial” from the scant data they’d obtained. Since the trials show that the newer treatments are more successful, however, only mAB114 and REGN-EB3 will be given to patients going forward—either under compassionate use protocols for the seriously ill or in an offshoot clinical trial that will determine which of the two therapeutics helps patients the most, reports Helen Branswell at Stat.
While Ebola has been documented since the 1970s, this is the first Ebola trial to demonstrate an effective treatment. As Amy Maxmen previously explained for Nature, clinical trials were launched during the tail end of the widespread 2014 epidemic, but researchers weren’t able to give promising treatments to enough patients to fully gauge how well they worked.
Finding a reliable treatment for the disease is a groundbreaking step, but “there is also a tragedy linked to this success, and the tragedy is that not enough people are being treated,” Michael J. Ryan, who directs W.H.O.’s Health Emergencies Program, tells the Washington Post’s Claire Parker. For one thing, the outbreak is taking place in an active conflict zone where violence has displaced almost five million people. McNeil writes for the Times that in the eastern part of the country, where the epidemic is centered, people have developed deep-seated distrust of the government. Coupled with misinformation about Ebola, that lack of trust has led to wariness of healthcare providers and even attacks on treatment centers.
Public health experts hope that once the news of an effective treatment spreads, it will encourage people to seek medical care earlier, instead of waiting five or six days after they become symptomatic. While an Ebola vaccine exists, it’s not a cure-all, and the death toll in the D.R.C. continues to mount. Just last month, the W.H.O. declared the outbreak a global health emergency, the first since the 2016 Zika epidemic. However, with the new treatments, says Muyembe, “These advances will help save thousands of lives.”
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