Hepatitis C
PHX1766 for the Treatment of Hepatitis C Virus Infection
Our second product candidate, PHX1766, is an orally available NS3/4A protease inhibitor, which we are developing for the treatment of HCV infection. 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 estimate that approximately 3.2 million people in the United States are chronically infected with HCV.
The current standard of care for the treatment of HCV infection is a combination therapy of injected pegylated interferon and orally-administered ribavirin. However, 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. Furthermore, among patients infected with HCV genotype 1, the most prevalent form of HCV in the United States, 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.
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. 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 PHX1766 may offer advantages over other HCV protease inhibitors in development, including an improved dosing regimen, higher potency and greater selectivity.