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Promising Ebola drug isn't effective enough after all, study says

When the deadliest Ebola outbreak in history tore through parts of West Africa in 2014, an experimental serum ZMapp was used in the lifesaving treatment of an American doctor infected with the virus in Liberia. After that encouraging first use, many hoped the drug could finally fill the void of available treatment options for the deadly hemorrhagic fever, but the latest findings show it might not be effective enough to fight Ebola after all.


During clinical trials ZMapp appeared to offer some benefits to Ebola patients, but it did not have more of an impact on recovery than standard medical practices already used to treat the hemorrhagic fever, according to a study published on Wednesday in the New England Journal of Medicine from the first controlled trials for the drug.

The trials included 72 patients from the U.S., as well as Liberia, Guinea, and Sierra Leone — the countries hardest-hit by the 2014 spread, which infected 28,000 people. ZMapp is one of the few remaining treatments in development that has a shot at becoming a crucial tool for fighting Ebola. This week’s results hinder efforts to find a viable treatment before the next outbreak hits.

“The outbreak appears to have ended with no incontrovertible evidence that any single treatment intervention, or combination of interventions, was unequivocally superior to the types of supportive medical care typically provided,” the study authors wrote in a report about the trial, funded by the National Institute of Allergy and Infectious Diseases (NIAID).

ZMapp was safe to administer to Ebola patients, but statistically the drug was not effective enough to meet the desired threshold of 97.5 percent, according to the study.

“It looks like ZMapp is not harmful, but you can’t count on it to slow down the virus enough to make a difference, either,” said Benjamin Neuman, a virology professor at the Texas A&M University-Texarkana, who was not involved in the trials.


Despite the shortfalls, researchers behind the study were optimistic about the outcome since overall ZMapp was found to be 91.2 percent effective. NIAID Director Dr. Anthony Fauci told STAT news that he still recommends distributing the serum to Ebola patients in an emergency. The study faced challenges in getting enough patients enrolled in the trial before the outbreak ended, and there is concern that trial participants in later stages of infection provided a poor baseline for the drug’s efficacy.

ZMapp first got notice in 2014 when it was used during the lifesaving treatment of two American missionaries in Liberia. There was no proof ZMapp was a factor in their recovery, but it quickly became a coveted drug as the outbreak spiraled. It was approved by public health officials for emergency use.

Ebola was discovered in 1976 and caused several small outbreaks in Central Africa over the next four decades. By the time the virus showed up for the first time in West Africa, in December 2013, not a single approved vaccine or drug had made it to human trials.

As cases surged, public health officials scrambled to look at options sitting in labs across the world in hopes of finding anything that could help stem the outbreak, which eventually killed 11,000 people. Along with several other promising vaccines and treatment options, ZMapp was expedited through the trial process.

The fast-tracking was crucial, not only for trying to save lives amid the 2014 outbreak but also to take advantage of an unprecedented number of people infected with or exposed to the virus who could participate in trials.

So far, all investigative options far enough along in development during the outbreak have failed to make it through trials. The remaining options are new and have yet to get through to the safety and human phases of the trial process.

“Miracle drugs, one-shot antidotes, instant cures — they make movies exciting, and real-world versions are usually worth a look, but the solution is typically going to be more complicated,” said Neuman.