An experimental Ebola drug kept monkeys from dying when it was administered to them 72 hours after infection. The finding bodes well for a human drug trial that’s already underway in Sierra Leone — a country were nine cases of Ebola were reported just last week.
The Ebola epidemic in West Africa is slowing down. A virus that used to infect hundreds of people every week now infects less than 50 a week worldwide. But for countries where Ebola is still present, the fight is far from over. The total number of infections since the outbreak started has reached 25,900, and more than 10,700 people have died. That’s why figuring out a way to prevent the infection via vaccines and to treat the infection via drugs is so important; Ebola is still a matter of life and death.
Monkeys that got the drug "really didn’t get that sick."
In the study, researchers gave a lethal dose of the Ebola virus to six rhesus monkeys. Then, 72 hours later, the researchers administered an Ebola drug, called TKM-Ebola, to three of those monkeys intravenously. Nine days after being dosed, all the chimps that have been treated with the drug were still alive; those that hadn’t were dead. "All three control animals developed classic hemorrhagic fever and succumbed to the disease," says Thomas Geisbert, an Ebola researcher at the University of Texas and a co-author of the study published in Nature today. The monkeys that got the drug, however, "really didn’t get that sick."
"Any treatment for Ebola that works in a time period where you can actually detect the virus already is something that’s potentially clinically promising — and that’s what you have here," says Darryl Falzarano, a virologist at the University of Saskatchewan in Canada who didn’t participate in this study. "All the treatment animals survived. That sets the stage for a potentially useful clinical treatment."
The monkey trial "sets the stage for a potentially useful clinical treatment."
The drug was originally created to fight the Kikwit Ebola strain — a strain that’s different from the one that spread in West Africa last year. Despite not being tailored for the current Makona strain, TKM-Ebola was given to a handful of patients in the US last year, Geisbert says. All the patients survived, but because these patients received a number of other drugs as well, it’s hard to tell whether the drug helped.
TKM-Ebola, developed by the Vancouver-based Tekmira, works by stopping the production of specific Ebola proteins. If you don’t have that virus protein, you can’t make a functioning Ebola virus, Geisbert says. Moreover, one of these proteins interferes with the immune system of those who are infected. That means that preventing it from being produced indirectly helps infected monkeys battle Ebola. "Not only are you slowing the virus’s growth, but you’re wrecking its ability to interfere with the host’s immune response," he says.
The drug is promising, but it's an intravenous drug, which means it won't be easy to administer in the field. Moreover, it still needs to be tested on humans. That’s happening right now in Sierra Leone, but results aren’t yet available.
In the meantime, Geisbert says that he would like to find out if the drug is effective four or five days after infection, instead of after only three. "There’s a point when someone is so sick that no drug in the world is going to save their life," Geisbert says. "But we want to know how far you can push all of these different technologies and still get some level of protection."