The unfortunate few infected by Ebola learn quickly that the rare disease is a near-certain death sentence. Outbreaks have led to fatality rates up to 90 percent, according to the World Health Organization. Treatment options are limited: no approved vaccines or drugs for treating Ebola exist, the WHO says.
As the current virus outbreak continues in West Africa, a small Durham, NC, biotechnology company is quietly working on a drug that, if all goes well, could become the first Food and Drug Administration-approved Ebola treatment. BioCryst Pharmaceuticals (NASDAQ: BCRX) is still in the early stages and has yet to test its experimental drug in humans. But its initial results have shown effectiveness treating hemorrhagic fevers in monkeys, and have prompted calls from interested healthcare officials from around the world.
“We can’t do anything about the current outbreak,” BioCryst chief medical officer William Sheridan says. “But we intend to work as hard as we can to figure out how would we make the drug available after we’ve got safety data in people, should there be another outbreak in Africa. And we know there will be. These things will keep happening, we just don’t know where and when.”
Like other viruses, Ebola hijacks an infected person’s cells and uses those cells to produce more viruses, which overwhelm the body’s immune system. In Ebola, initial symptoms of fever, muscle pain, and weakness progress to more severe symptoms including internal and external bleeding. BioCryst’s experimental antiviral drug, called BCX4430, works by preventing virus replication. The goal of an antiviral drug is to suppress virus production enough to allow the human body’s immune system to kick in and make antibodies to fight it, Sheridan explains. The company’s drug is a nucleoside analogue, just like Sovaldi, the Gilead Sciences (NASDAQ: GILD) hepatitis C drug approved last year that has since gone on to become a blockbuster drug. In fact, BCX4430 emerged from BioCryst’s own failed efforts in hepatitis C drug research.
BioCryst’s nucleoside antiviral program in hepatitis C didn’t advance beyond the preclinical stage. Jon Stonehouse, the company’s CEO (pictured), says the compounds showed some activity in hepatitis C but not enough to justify pursuing a new hepatitis C drug. Seeing some activity in hepatitis C, an RNA virus, prompted BioCryst scientists to pursue tests of BCX4430 against other RNA viruses. That’s what led the company to filoviruses, the family of viruses that cause viral hemorrhagic fevers. Both Ebola and Marburg are filoviruses.
Last September, BioCryst entered into a government contract to develop BCX4430 for Marburg virus through the National Institute for Allergy and Infectious Disease (NIAID), a division of the National Institutes of Health. The contract, valued at up to $22 million, would take BCX4430 through testing in animals and as far as phase 1 studies in humans. BioCryst received $5 million upon entering the contract. In June, the NIAID released an additional $1.8 million, allowing the company to continue preclinical work.
Testing against filoviruses requires a biosafety level 4 lab, the highest level of safety for testing life-threatening infectious diseases such as Ebola and Marburg. BioCryst has no such lab, so those tests were done in collaboration with the U.S. Army Medical Research Institute for Infectious Diseases at its facility in Fort Detrick, MD. Preclinical results published earlier this year in the journal Nature showed that all of the monkeys infected with Marburg virus that were treated with BCX4430 survived the two-week trial. Marburg infection killed all of the monkeys in the control group. BioCryst will still need to conduct additional trials in monkeys, including tests of BCX4430 in monkeys infected with Ebola.
A report in the journal Cell Research notes that while there have been small molecules showing efficacy against filovirus infections in lab tests, the BCX4430 results were the first showing efficacy in tests with primates. Monkeys infected with Marburg showed up to 100 percent protection when administered with BCX4430 as late as 48 hours following infection, the report says. In addition to showing efficacy in the animal tests for Marburg virus, the compound also showed efficacy in lab tests for different species of Ebola virus.
The first Marburg epidemics were documented in 1967 in Belgrade, Yugoslavia as well as the German cities of Frankfurt and Marburg, which gave the virus its name, according to the WHO. Ebola was first discovered in Africa in the 1970s. These virus outbreaks are unpredictable. The rarity of the outbreaks and the small numbers of patients affected by these viruses mean the private sector sees few incentives for developing and commercializing treatments.
BioCryst sees the U.S. government as the main customer for its experimental antiviral. The 2004 Project BioShield Act was enacted to spur research and development of bioterror countermeasures by giving the government the authority to fund, develop, and stockpile such drugs. The Centers for Disease Control and Prevention lists Marburg and Ebola as “Category A” bioterrorism agents and diseases, putting them in the same class as anthrax and smallpox.
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