Hepatitis C
NS3/4A Protease Inhibitors for the Treatment of Hepatitis C Virus Infection
Hepatitis C is a challenging disease to treat and many patients suffering this chronic infection have low response rates from existing therapeutics. In response to the limitations of present treatments for HCV infection, NS3/4A protease inhibitors have emerged as a promising potential additional treatment.
The current standard of care for the treatment of HCV infection is a combination therapy of injected pegylated interferon and orally-administered ribavirin. This first-line treatment for patients chronically infected with HCV is a 48-week course of pegylated interferon alpha-2 plus ribavirin. Unfortunately, approximately half of all patients infected with genotype 1 (the predominant genotype in the U.S.) do not respond to this treatment regimen. Among patients infected with HCV genotype 1 only 42-46% treated under the standard of care achieve a sustained viral response, or SVR, which is defined as the absence of a detectable amount of HCV in the blood six months after completion of therapy.
Additionally, this combination therapy has been associated with serious side effects. The side effect profile of the standard of care, together with its long duration of therapy and the requirement that interferon be administered by injection, may reduce patients’ motivation to initiate or continue HCV therapy under this standard of care.
Unlike interferons, which work by stimulating the immune system's response to viral infection, HCV protease inhibitors directly target the virus by inhibiting NS3/4A protease, a key mechanism implicated in HCV replication. When tested in Phase 2 clinical trials, NS3/4A protease inhibitors have reduced the levels of virus in the blood and, when added to the standard of care, provided greater SVR rates and a shorter duration of therapy compared to the standard of care alone. Based upon our preclinical data, we believe our NS3/4A protease inhibitor may offer an improved dosing regimen over other HCV protease inhibitors currently in development.
Hepatitis C:
The World Health Organization estimates that nearly 180 million people worldwide are infected with hepatitis C virus infections (HCV). Of these individuals, 130 million are chronic HCV carriers with an increased risk of developing liver cirrhosis or liver cancer. It is estimated that three to four million people worldwide are newly infected each year, 75-85% of whom will develop chronic hepatitis C. According to the Centers for Disease Control and Prevention, HCV is the most common chronic blood-borne viral infection in the United States. The virus is a leading cause of liver failure, liver transplants and liver cancer. The CDC estimates that approximately 3.2 million people in the United States are chronically infected with HCV.