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Although we have had an effective hepatitis B vaccine for a number of years, a cure, or even a specific treatment, has continued to elude scientists. Consequently, in areas where vaccines are not widely available, such as sub-Saharan Africa, as many as 10% of the adult population is chronically infected. But hope could be on the way, as scientists in Australia may have finally found a long sought-after cure.
The promising new treatment, which involves a combination of an antiviral drug and a cancer drug, eliminated the virus in 100% of infected animals tested. And since the drugs are approved and on the market, human safety and efficacy trials are already underway across several cities in Australia. The promising findings have been published in Proceedings of the National Academy of Sciences.
Hepatitis B is a potentially life-threatening infection of the liver caused by the hepatitis B virus (HBV). Normally, healthy adults recover from infection within a year because the presence of the virus triggers a controlled cellular process called apoptosis, which is where cells commit suicide in order to stop the virus persisting and spreading. But unfortunately, the virus is able to interrupt the signals required for this process, and consequently some patients will go on to develop chronic infections that often lead to scarring of the liver or liver cancer, which can be fatal.
Armed with this knowledge, scientists from the Walter and Eliza Hall Institute set out to find a way to interfere with the signaling pathways employed by HBV to prevent cells from destroying themselves. After investigating the behavior of the virus in infected cells, the scientists identified a potential drug candidate: Birinapant.
This drug was actually originally developed as a cancer treatment, but the researchers discovered that it is also capable of flipping HBV’s survival ‘switch,’ thus allowing infected cells to undergo normal apoptosis. Interestingly, the researchers found that they could boost this process by using the drug in conjunction with an existing anti-HBV therapy.
“Birinapant enables the destruction of hepatitis-infected liver cells while leaving normal cells unharmed,” lead researcher Marc Pellegrini said in a statement. “Excitingly, when birinipant was administered in combination with current antiviral drug entecavir, the infection was cleared twice as fast compared with birinapant alone."
When the researchers tested out this combination therapy in infected animals, they were able to cure the virus 100% of the time. This impressive preclinical success led to the initiation of a human trial in December, which will first investigate safety in healthy volunteers and then efficacy in patients with the disease. Hopefully, because the cancer drug does not specifically target bits of the virus, resistance will be difficult to evolve, meaning the treatment should not be quickly rendered ineffective.
Alongside human trials, the researchers would like to continue their work by investigating whether the combination therapy could also be useful in treating other chronic viral diseases, such as herpes or perhaps dengue fever.
