Antiviral efficacy of NS3-serine protease inhibitor BILN-2061 in patients with chronic genotype 2 and 3 hepatitis C

BILN-2061, a specific and potent peptidomimetic inhibitor of the HCV NS3 protease, has recently been shown to markedly lower serum hepatitis C virus (HCV)-RNA levels in patients chronically infected with HCV genotype I in three 2-day proof of principle studies. The aim of the current study was to assess the antiviral efficacy of BILN-2061 in patients with genotypes 2 and 3 HCV infection. The antiviral efficacy, pharmacokinetics, and tolerability of 500 mg twice-daily BILN-2061 given as monotherapy for 2 days in 10 patients chronically infected with non-genotype 1 HCV (genotype 2: n = 3; genotype 3: n = 7) and minimal liver fibrosis (Ishak score 0-2) were assessed in a placebo-controlled (placebo n = 2), double-blind pilot study. HCV-RNA levels decreased by >= 1 log(10) copies/mL in 4 of 8 patients treated with BILN-2061. One patient showed a weak response of <1 log(10) copies/mL. Three of 8 treated patients showed no response. There was no correlation between baseline viral concentration or genotype and response. BILN-2061 exhibited good systemic exposure after oral administration and was well tolerated. In conclusion, the antiviral efficacy of the HCV serine protease inhibitor BILN-2061 is less pronounced and more variable in patients with HCV genotype 2 or 3 infection compared with previous results in patients with HCV genotype 1. A lower affinity of BILN-2061 for the NS3 protease of genotypes 2 and 3 HCV is most likely a major contributor to these findings.