First Ebola Treatment Approved: Expert Viewpoint - Forbes
Last week the first treatment for any kind of Ebola, a triple monoclonal antibody combination designed to treat the most severe ‘Zaire’ form of the virus, was approved by the FDA.
The company behind the treatment, Regeneron Pharmaceuticals, has had a lot of attention recently. It is also developing a dual antibody treatment for Covid-19 – famously endorsed by Trump after he was treated with it after becoming infected with the virus.
To find out more about what the Ebola therapy approval means, I spoke to virologist Professor Daniel Bausch from the London School of Hygiene and Tropical Medicine. He has been working to combat emerging tropical viruses such as Ebola and SARS coronavirus for the last 25 years.
What is Ebola?
Ebola is a small RNA virus that has been responsible for a number of serious epidemics in Africa over the last 20 years including a large epidemic in West Africa from 2013-2016 that killed more than 11,000 people.
Ebola virus in the blood 3D rendered Illustration
gettyThere are four species of Ebola viruses known to infect people, Zaire – the most common and most deadly, Bundibugyo, Sudan, and Taï Forest.
It causes a number of symptoms including fever, sore throat, muscular pain, and headaches, often followed by vomiting and diarrhea, liver and kidney problems and internal and external bleeding.
It is not as infectious as Covid-19, but has a much higher death rate. This has ranged from 25-90% depending on the causative species, epidemic and the treatment received by those infected. For example, the death rate is known to be impacted by factors such as whether patients receive enough fluids. But, on average, around 50% of those infected die.
Why is this approval significant?
“We have a disease that is not widespread throughout the world, but nevertheless has caused big outbreaks and has a very high case fatality. So, it's very welcome to have some tools to try to make people better in these very difficult settings,” says Bausch.
TARRYTOWN, NEW YORK, UNITED STATES - 2020/10/02: View of Corporate and Research and Development ... [+]
Pacific Press/LightRocket via Getty ImagesTo fight off any infection, whether caused by a virus, bacteria or parasite, our immune systems produce antibodies. Regeneron’s therapy Inmazeb is a combination of three monoclonal antibodies - atoltivimab, maftivimab, and odesivimab-ebgn - which help the body fight off Ebola.
The newly approved treatment targets Zaire Ebola virus. In a study of 382 adults and children that received it, it cut the risk of dying after 28 days from 51% to 33.8%. While this is still high, Bausch says that it is a significant advance.
“In prior years, we had the sense that mortality was so high with Ebola, people would say, whatever you do, don't go to the isolation center, because that's where people die… if we can change that…not only does it give them the best chance to get better. But it also helps to curtail the outbreak because they don't stay in the community and infect others.”
Why are monoclonal antibodies a good treatment?
Monoclonal antibodies are not a new type of therapy and have been used to treat various types of cancer, as well as autoimmune conditions such as rheumatoid arthritis, for many years. However, they have only been used to treat serious virus infections, such as Ebola and Covid-19, more recently.
Monoclonal antibodies binding to antigens on a cancer cell's surface
gettyThey are highly specific and so Inmazeb can be used to treat Zaire Ebolavirus, but not the other three species of the virus. The three antibodies included in this treatment bind to a protein on the surface of the virus particles and stop them from entering and infecting more cells.
“The downside, if you will, is that they are so specific,” says Bausch. “It's not that you couldn't have a monoclonal antibody for Sudan species, but you'd have to develop that as well. It's not something where you could just take out this drug and say, okay, it's good for any species of Ebola.”
Although Inmazeb is the only approved therapy for Ebola to date, others are being developed and Bausch thinks it will not be long before antibody combinations targeting other Ebola species, or even a cocktail targeting more than one species, become available.
“It has challenges though,” he cautions. “Some patients develop a degree of hypersensitivity, and then the more you put into a cocktail, the more chances of hypersensitivity that you might have.”
Lessons for Covid-19 drug and vaccine developers
Although the 2013-2016 Ebola epidemic, which infected over 28,000 people and resulted in more than 11,000 deaths, may now seem small in comparison to the ongoing Covid-19 pandemic, Bausch thinks there are lessons that can be learned from how drug and vaccine developers responded at the time.
Western Africa where the 2013-2016 Ebola epidemic took place.
getty“I guess in many ways the West Africa outbreak showed us that we weren't ready to do research as rapidly as we needed to in these sorts of settings. For therapeutics, a couple of trials were put in place, but didn't get to the endpoints that they needed to really look at therapeutic efficacy. And some of them kind of never got off the ground for lots of different reasons.”
The first Ebola vaccine, developed by Canadian researchers and now licensed to Merck, had already been developed before the West Africa epidemic, but was only in the early stages of development and had not been tested on humans.
Between 2014 and 2016 the vaccine was pushed through an expedited trial process from phase I up till phase III — the normal clinical trial stages any drug has to get through before it can be approved — due to the urgent requirement of people in the affected countries. Ervebo only received official FDA approval in 2019, but in the meantime was used to successfully vaccinate people and stop the spread of the virus in two outbreaks in the Democratic Republic of Congo in 2018.
“I think this has shown us that we can do these things much faster,” emphasizes Bausch. “Before that, we would have always said that any sort of trial of a vaccine, or a therapeutic is a 10 year, multi-million-dollar process.”
“There's still expense associated with it. But the rapidity with which these trials have been put together for Ebola in West and Central Africa, and then Covid-19, is really showing us that it doesn't have to be a 10-15-year process. We can do this more rapidly if we have the political and economic will to do it.”
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