As the Ebola outbreak spread to a fifth African country Friday, researchers announced that the experimental drug pressed into emergency use in recent weeks had cured a group of 18 monkeys of the deadly disease, including some that didn’t receive the treatment for five days after they were injected with the virus.
The research raised new hope for the eventual use of the cocktail of monoclonal antibodies against Ebola, which has no cure or vaccine. It has been fatal to more than half of the 3,069 people who have acquired the virus in Liberia, Guinea, Sierra Leone, Nigeria, and now Senegal, which confirmed its first case Friday.
The research unveiled Friday in the online version of the journal Nature is a huge step forward, said Thomas Geisbert, a professor at the University of Texas Medical Branch at Galveston, who has conducted similar research on the lethal Marburg virus and reviewed the Ebola study for Nature. It’s very, very hard for me to believe that this would not have substantial utility in treating human disease.
The drug, ZMapp, was able to reverse severe Ebola disease leading to full recovery of all treated non-human primates within 28 days after they were infected, the researchers wrote.
The treatment has not been tested on humans, although it was given on an emergency basis to seven people who fell ill in recent weeks, including two American missionaries who recovered. Of the seven who received the drug, two have died – an elderly Spanish priest and a Liberian doctor. Two other doctors in Liberia and a British nurse are still being treated. But it is impossible to determine the drug’s impact on a small sample of people who became infected at different times and received their care under differing circumstances.
The small supply of the drug, perhaps 20 doses, is exhausted, according to Mapp Biopharmaceutical, the tiny San Diego company that developed it.
In a telephone news conference, Gary Kobinger of Canada’s Public Health Agency, one of the authors of the newly released paper, said human subjects should receive three doses of the drug to maximize its effectiveness. He estimated that Kentucky BioProcessing, the company that manufactures the drug in tobacco plants, could produce 20 to 40 doses a month once it is working at full speed – a small fraction of the number that may be needed.
Kobinger said he thinks additional doses should be available for humans by the summer of 2015.
But David Howard, a spokesman for Reynolds American Services, which owns Kentucky BioProcessing, said in an email that any estimate of output or capacity regarding production of ZMapp would be pure speculation at this time, since what constitutes a human dose hasn’t been determined yet. The important issue right now is to focus on the need to proceed through clinical and production process development steps. Until these steps are completed, we can’t know things like dose size or dose frequency.
Asked whether his research shows that ZMapp will work on people, Kobinger said: I think it strongly supports that concept, but it’s not proven.