Hepatitis B (HBV) is a viral disease that can be sexually transmitted. In some patients it becomes chronic and can lead to liver scarring, liver failure or cancer. It is much more infectious than HIV and is extremely prevalent, especially in developing countries. There is also a high incidence of co infection with HIV in gay men and in people who inject drugs. It is easy to catch but unfortunately quite hard to treat, so researchers are always looking for new strategies to improve treatments.
Researchers at the University of Hong Kong recently reported on the results of a novel therapy for Hepatitis B. The treatment called ARC-250 uses short interfering RNA (siRNA). These are small pieces of double stranded Ribonucleic Acid ( RNA) that can block expression of messenger RNA. ARC-250 is a new liver specific siRNA therapy that was designed specifically to interfere with the Hepatitis B virus replication cycle as well as its protein production. The researchers had already tested the drug in mice and chimpanzee models where it showed a reduction in the number of viral particles .
One of the problems with Hepatitis B infection is the fact that in some people the disease becomes chronic and this is thought to be due to these viral proteins ( especially Hepatitis B ‘e’ antigen ( HBeAG) and Hepatitis B surface Antigen ( HBsAG) that are implicated in sustaining the infection and also in disease progression. The hope is that by targeting these proteins the immune system might be in a better position to clear the virus.
The current treatments ( Entecavir, tenovofir etc) that we use, can suppress the virus very effectively but they do not always eradicate the virus.
The researchers conducted a phase 2a trial to test the efficacy of a single dose of ARC-250 in reducing levels of HBsAG in HBeAG- negative people taking entecavir long term .The study was randomised and double blinded dose ranging conducted in 24 adults with Hepatitis B. The results showed a significant reduction in HBsAG for up to 43 days following a single injection of ARC-250. This is the first time that such a reduction has been shown to be mediated by RNA interference in Hepatitis B patients. In addition ARC-250 appeared safe and well tolerated with no serious adverse events.
Hopefully further improvements can be made in this exiting field leading to more effective treatments for this killer disease.