At least four vaccines are being developed to protect people against Ebola, including one that protects monkeys completely against the deadly virus. Several groups are also working on treatments, but one of the most promising is stuck in safety testing.
They might be farther along if not for one problem: money.
Even though Ebola is burning out of control in West Africa, it’s not a huge potential market for a large pharmaceutical company to sink its teeth — and its assets — into developing. That leaves the U.S. government and small, niche biopharmaceutical companies.
“I don’t see why anybody except the U.S. government would get involved in developing these kinds of countermeasures,” said Dr. Sina Bavari of the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) in Frederick, Maryland. “There is no market in it.”
Ebola has infected more than 1,200 people and killed close to 700 of them. Among the victims are two U.S. charity workers — a doctor and a hygienist who were helping patients in Liberia. And the doctor leading the fight in Sierra Leone died from the virus this week.
An American working for the Liberian government collapsed after he got off a flight in Lagos, Nigeria and died in isolation; Nigerian officials are working to track down at least 59 people who were in contact with him to make sure they were not infected.
Yet the dozens of patients currently being treated for Ebola are getting a bare minimum of care. No specific drug has been shown to help people infected with Ebola, so patients are given saline to replace fluids lost to vomiting and diarrhea; painkillers to reduce fever and to help fight the general misery the virus causes; and antibiotics to prevent what doctors call secondary infections.
"There are at least four vaccines that can protect against Ebola (in monkeys)," says Dr. Thomas Geisbert, whose lab at the University of Texas Medical Branch is working on some of them. "But how do you take this to the next level?"
"There is no market in it."
Ebola is so unpredictable that it would be very difficult to find enough people at high risk to test it in. Diseases such as influenza and even HIV are common and it's easy to test large groups of people. Not so with Ebola.
Various labs have been working for decades to come up with drugs and vaccines to fight Ebola and its close cousin Marburg virus. They are both considered potential bioterrorism agents, which is what drives most of the U.S. government’s interest.
One drug started safety trials in people in January, but it got put on hold by the U.S. Food and Drug Administration earlier this month over concerns about the dose being given to volunteers. It’s made by a Canadian company called Tekmira, with funding from the U.S. government. The drug uses small bits of genetic material called RNA that attach to the virus and target it for destruction by the immune system.
The company hopes to get back on track by the end of the year. “We are mindful of the need for this important therapeutic in situations such as the ongoing Ebola outbreak in West Africa,” Dr. Mark Murray, president and CEO of Tekmira Pharmaceuticals, said in a statement. “However, TKM-Ebola is currently an unapproved agent and the regulatory framework to support its use in Africa has not been established at this time."
Further along in human testing is a drug called favipiravir, or T-705. Approved under the brand name Avigan in Japan, it’s being tested for influenza. But early tests in mice suggest it might also work against Ebola. This one would be especially useful because it’s a small molecule — something that could be taken orally, even in pill form. Bavari says USAMRIID is currently testing it against monkeys, animals whose response to Ebola infections is much closer to humans than mice's are.
The lab is also testing a drug called BCX4430 in animals. A small biotech company called BioCryst is working with USAMRIID to develop that one. It seemed to protect monkeys when given as long as 48 hours after they were infected.
Other drugs are based on monoclonal antibodies, engineered immune system proteins that can home in specifically on a microbe. One collaboration grows them in genetically engineered tobacco plants.
The treatment, called MB-003, provided 100 percent protection to monkeys when given right after exposure to the virus, and helped even after symptoms developed.
There are some promising vaccines, also, says Geisbert. His favorite is made using a virus called vesicular stomatitis virus. It’s genetically engineered to resemble Ebola, and it’s worked well in monkeys. Scientists who have worked with it feel confident it’s effective, Geisbert says. “We would all want it,” he said.
But it uses a “live” virus, which means it can replicate in the body and that could cause side-effects. “Like any live vaccine, you have to worry about safety,” Geisbert said.
Other vaccines have used adenoviruses, which are in the family of viruses that cause the common cold. The trouble with these is that many people already have immunity to adenoviruses because they’ve had colds, and the vaccines may not work in all people.
Then there are vaccines using virus-like particles, an approach that’s worked against other disease. Again, they haven’t been tested in people yet, says Bavari.
“All kinds of questions come up about who do you treat and is it ethical to use it."
Geisbert says he sometimes wonders whether a bad outbreak like this one doesn’t call for unusual measures, like trying some of the experimental drugs or vaccines.
“All kinds of questions come up about who do you treat and is it ethical to use it,” he said. “My own opinion, regardless of the treatment, is that I would love to see one of the vaccines used to vaccinate first responders, lab workers, the people that are on the front line,” he said.
Other experts say an ongoing outbreak is a poor time to try something that could just make matters worse.
Bavari says he hopes the current outbreak will give drug and vaccine development a little impetus.
“Maybe this outbreak will put some life into this. Maybe people will start asking the tough questions, such as do they work in human beings or not,” he said.
First published July 29 2014, 2:08 PM