Experimental Ebola drug ZMapp is “100% effective” in animal trials

Sept. 3, 2014

The only clinical trial data on the experimental Ebola drug ZMapp shows it is 100% effective in studies testing on monkeys, even in later stages of the infection. The researchers, publishing their data in Nature this week, say it is a “very important step forward.”

Researchers have been investigating different combinations of antibodies, a part of the immune system which binds to viruses, as a therapy. Previous combinations have shown some effectiveness in animal studies. ZMapp is the latest cocktail and contains three antibodies.

Trials on 18 rhesus macaques infected with Ebola showed 100% survival. This included animals given the drug up to five days after infection. For the monkeys this would be a relatively late stage in the infection, around three days before it becomes fatal.

Scientists say this is significant, as previous therapies needed to be given before symptoms even appeared. However, there is always caution when interpreting the implications for humans from animal data. Two of seven people who were given the drug so far as a compassionate therapy nevertheless died from the disease.

The course of the infection is slower in humans than macaques, so it has been cautiously estimated that ZMapp may be effective as late as day nine or 11 after infection. Read more about ZMapp from the CDC website.

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