Hepatitis Delta (HDV)
Hepatitis Delta is caused by infection with the hepatitis D virus (HDV) and is considered to be the most severe form of viral hepatitis in humans. Hepatitis D occurs only as a co-infection in individuals positive for the HBV surface antigen (HBsAg). HDV requires HBsAg for replication. Chronic HDV infection leads to more severe liver disease than HBV mono-infection and is associated with accelerated fibrosis progression, earlier hepatic decompensation and an increased risk for the development of hepatocellular carcinoma.
HDV is a disease with a significant impact on global health affecting 10–15 million people worldwide. The prevalence of HDV varies between different parts of the world. HDV is estimated to meet criteria for Orphan Designation in the United States and Europe, with rates estimated to be 5% of HBV infected patients. In some parts of the world, including China, Russia, Central Asia, Turkey, Africa, and South America, it has high prevalence rates with up to 30% of HBV infected patient.
No therapeutic is approved anywhere in the world for the treatment of HDV. Despite multiple trials in HDV infected patients, using multiple antiviral agents, only pegylated IFN-α treatment has proven antiviral activity against HDV in humans. Unfortunately, sustained virologic response to therapy, measured in terms of undetectable serum HDV-RNA levels, can only be achieved in about one quarter of patients with Hepatitis D after one year of treatment. In addition, pegylated IFN-α is associated with a variety of adverse events, including flu-like constitutional symptoms, neuropsychiatric events, and hematologic cytopenias. More effective treatment options are needed.