In this undated file photo provided by Kentucky BioProcessing, tobacco plants are grown in a controlled environment at the Kentucky BioProcessing facility in Owensboro, Ky. An experimental Ebola drug, generated in tobacco plants genetically modified to produce specific antibodies, healed all 18 monkeys infected with the deadly virus in a study released Friday, Aug. 29, 2014. Photo: AP Photo/Kentucky BioProcessing, File Canadian scientists have rescued from death monkeys infected with a lethal dose of Ebola in the latest study of an experimental drug that has been used on a handful of Ebola victims in West Africa.
The anti-body based compound known as ZMapp rescued 100 per cent of 18 Ebola infected rhesus macaques, even when the drug was administered up to five days after infection with the virus.
All treated monkeys recovered fully and show no side-effects, said Dr. Gary Kobinger, chief of special pathogens at Canada’s National Microbiology Laboratory in Winnipeg. Three Ebola infected macaques that didn’t receive ZMapp died.
It is the first study reported in monkeys of the version of ZMapp now being administered in the West African outbreak.
The unlicensed cocktail, produced in collaboration with the Public Health Agency of Canada, still requires testing in humans and is unlikely to ever be produced in sufficient enough batches to make an impact on the current Ebola outbreak ravaging parts of West Africa. A notice on the website of ZMapp’s San Diego-based developer, Mapp Biopharmaceuticals Inc, said the available supply has been exhausted.
Gary Kobinger works in a mobile laboratory installed by specialists of the National Public Health Agency of Canada, in Mweka, Congo, Friday, Sept. 28, 2007. The experimental Ebola drug ZMapp was able to save infected monkeys even when treatment was only begun five days after the animals were infected, a new study shows. (THE CANADIAN PRESS/AP, WHO, Christopher Black, HO)
The drug is generated in tobacco plants genetically modified to produce the antibodies and Kobinger said that, from what he understands, it takes one month to produce 20 to 40 doses.
It’s not clear how the experiments in monkeys would translate into humans.
But Kobinger said the results are a promising signal the experimental compound might be the long sought therapy against one of the most deadly pathogens known.
“What’s quite remarkable is that we could rescue some of the animals that had advanced disease. For us, advanced disease is an animal that is just a few days from the end, if not only a few hours,” Kobinger told reporters Friday.
A study published last November testing an earlier version of the drug found Ebola-infected macaques survived after given the mixture within 24 hours of infection.
In the new study, Kobinger expected to see an improvement when the animals were treated further out after infection, which would be more like the case with Ebola infected humans, but it was beyond what he expected.
“I was quite surprised …. that we would be going as far and this time rescue animals up to day five — and all of them — which was fantastic news.”
A security agent controls the temperature of a woman at the entrance of the port of Monrovia on August 29, 2014. (DOMINIQUE FAGET/AFP/Getty Images)
The Canadian-led study was published online Friday in the journal Nature.
Ebola is often fatal in humans. The current outbreak has a case fatality rate of up to 90 per cent, and there is currently no licensed treatment or vaccine available for use in people.
ZMapp, produced in collaboration with Canada’s federal public health agency, is composed of three “humanized” monoclonal antibodies that bind to the protein of the Ebola virus.
The drug has been given to seven patients infected in the West African outbreak, two of whom — a Spanish priest and a Liberian doctor — died despite treatment.
Kobinger suggested that age as well as other underlying health issues or the timing of the dose might have been factors. There also may have already been too much damage to major body organs.
“We know there is a point of no return when there is too much damage to major organs, so there’s a limit,” he said.
But it’s also possible the other health-care workers who recovered after receiving ZMapp might have done so without treatment.
A woman walks past a banner informing about the Ebola virus near the entrance of the port of Monrovia on August 29, 2014.(DOMINIQUE FAGET/AFP/Getty Images)
In humans, Ebola has an incubation period of three to 21 days after exposure to the virus. The first symptom is often a flu-like illness that can rapidly progress to hemorrhage, multiple organ failure and a shock-like syndrome.
In the latest ZMapp experiment, the researchers administered a lethal dose of Ebola to three groups of six animals, and then treated them with three doses of ZMapp spaced three days apart.
All the animals survived and were found to have undetectable viral loads by 21 days after infection.
An accompanying article in Nature called the experiment a “monumental achievement” while others said it provides the most compelling evidence to date that ZMapp may be an effective treatment against Ebola in humans.
“I never thought that 40 years after I encountered the first Ebola outbreak, this disease would still be taking lives on such a devastating scale,” Peter Piot, director of the London School of Hygiene and Tropical Medicine said a statement.
“It is now critical that human trials start as soon as possible.”
Others urged caution.
“The gap between animal studies and first time, in-human studies even in the top institutions in the world is enormous,” said Dr. Jim Lavery, managing director of the Ethical, Social & Cultural Program for Global Health at St. Michael’s Hospital in Toronto and associate professor at the Dalla Lana School of Public Health at the University of Toronto.
The body of a man found in the street, suspected of dying from the ebola virus is sprayed with disinfectant, in the capital city of Monrovia, Liberia. (AP Photo/Abbas Dulleh)
“It’s not ethically neutral to raise hopes in this way,” he said.
“Everyone is on the same page — no one wants everyone to be dying. Everyone wants the game-changer,” Lavery said.
“But I don’t think that it’s responsible or even respectful of the populations that are affected right now to be even reporting these things in ways that suggest it might be simpler than it really is.
“There’s nothing simple about this.”
The monkeys were infected with a strain different to the one behind the current West African outbreak, but Kobinger said that, when tested in cell cultures, ZMapp stopped the new strain from replicating.
The West African Ebola outbreak, the worst on record, has so far claimed at least 1,552 lives, according to figures released this week by the World Health Organization.
Meanwhile, Canada’s public health agency said three mobile lab team members, who were supporting the Ebola outbreak response efforts in Sierra Leone, arrived safely in Canada Friday evening.
The three were pulled back early as a precautionary measure after three people in their hotel complex were confirmed to be infected with Ebola.
The team members arrived on a private charter plane Friday night and travelled to private residences once they were deemed healthy by a Quarantine Officer.
All three will be voluntarily self-isolating for the remainder of the incubation period and their health will be monitored. The agency said the risk to Canadians remains “very low.”
skirkey@postmedia.com
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