Telaprevir (VX-950) a novel antiviral treatment for Hepatitis C virus patients

Introduction

The hepatitis C virus (HCV) epidemic continues to be a serious health threat, infecting over 170 million people worldwide (Lin et al. 2005). Moreover, three to four million people are newly infected each year (Ressink et al. 2006). The infection is often asymptomatic in its early stages, but the majority of HCV-infected individuals develop chronic hepatitis over time, which eventually advances to liver scarring (cirrhosis), and liver cancer (hepatocellular carcinoma) (Moriishi and Matsuura 2007). The epidemiology of the virus is not well understood. However, it is known that HCV is transmissible through sexual contact and blood-to-blood contact. In the United States, blood-to-blood transmission of HCV is greatest among injecting drug users (IDUs). Although the virus can be acquired through blood transfusions, and contact with other sources of infected blood product (Simmonds 2000).

Standard treatment for Hepatitis C: Interferon alfa-2b plus ribavirin

Since 1998, an antiviral drug that combines interferon alpha-2b and ribavirin has been marketed and used to treat HCV infections (Keeffe 2006). Interferons function by disturbing viral replication through immune response stimulation. More specifically, they activate immune cells, such as natural killer cells and macrophages; they increase recognition of infection by up-regulating antigen presentation to T lymphocytes; and they increase the ability of uninfected host cells to resist new infections (Hunt 2009). The drug’s other component, Ribavirin, is a prodrug which when metabolized resembles purine RNA nucleotides. In this form, it interferes with the RNA metabolism required for viral replication. The mechanism of interference is not well known, but some mechanisms have been proposed (Feld and Hoofnagle 2005). Side effects of the drug range from mild flulike symptoms to severe symptoms like hair loss, bloody stools, depression and suicidal tendencies (AHFS 2010). While the interferon/ribavirin combination drug sustained response rates are 54-56%, these results imply that 40-50% of patients do not have lasting improvements with treatment (Feld and Hoofnagle 2005). Pharmaceutical companies are developing alternative HCV treatments in attempt to improve care for infected individuals.