Antiviral activity of telaprevir (VX-950) and peginterferon alfa-2a in patients with hepatitis C.

UNLABELLED: Telaprevir (VX-950), an inhibitor of the hepatitis C virus (HCV) NS3/4A protease, substantially decreased plasma HCV RNA levels in a prior clinical study. The present study evaluated viral kinetics and safety during dosing with telaprevir alone and in combination with peginterferon alfa-2a for 14 days. Previously untreated patients with genotype 1 hepatitis C were randomized to receive placebo and peginterferon alfa-2a (n = 4); telaprevir (n = 8); or telaprevir and peginterferon alfa-2a (n = 8). Telaprevir was given as 750 mg oral doses every 8 hours; peginterferon alfa-2a was given as weekly 180 mug subcutaneous injections. The median change in HCV RNA from baseline to day 15 was -1.09 log(10) (range, -2.08 to -0.46) in the placebo and peginterferon alfa-2a group; -3.99 log(10) (range, -5.28 to -1.26) in the telaprevir group, and -5.49 log(10) (range, -6.54 to -4.30) in the telaprevir and peginterferon alfa-2a group. Day 15 HCV RNA levels were undetectable in 4 patients who received telaprevir and peginterferon alfa-2a and in 1 patient who received telaprevir alone. No viral breakthrough occurred in patients who received telaprevir and peginterferon alfa-2a. The majority of adverse events were mild. There were no serious adverse events or premature discontinuations. Twelve weeks after starting off-study standard therapy, HCV RNA was undetectable in all 8 patients in the telaprevir and peginterferon alfa-2a group, 5 patients in the telaprevir group, and 1 patient in the placebo and peginterferon alfa-2a group. CONCLUSION: This study confirmed the substantial antiviral effects of telaprevir and showed an increased antiviral effect of telaprevir combined with peginterferon alfa-2a.

Dynamic hepatitis C virus genotypic and phenotypic changes in patients treated with the protease inhibitor telaprevir.

BACKGROUND & AIMS: Telaprevir (VX-950), a hepatitis C virus (HCV) NS3.4A protease inhibitor, has shown strong antiviral activity in phase 1 clinical studies. Because of high levels of HCV replication and the low fidelity of HCV polymerase, selection of resistant isolates during therapy may occur. METHODS: A highly sensitive sequencing method was developed in which approximately 80 clones/sample were analyzed to identify mutations in the NS3 protease catalytic domain in HCV genotype-1-infected patients dosed with 450 mg every 8 hours, 750 mg every 8 hours, or 1250 mg every 12 hours of telaprevir for 14 days. RESULTS: Mutations that confer low-level resistance (V36A/M, T54A, R155K/T, and A156S) and high-level resistance (A156V/T, 36+155, 36+156) to telaprevir were detected and correlated with telaprevir exposure and virologic response. Changes in the frequency of mutations after the end of dosing showed an inverse relationship between in vivo viral fitness and resistance. In the absence of telaprevir selective pressure the majority of resistant variants were replaced by wild-type virus within 3-7 months. CONCLUSIONS: Resistant HCV isolates are selected rapidly during therapy with the highly active protease inhibitor telaprevir. Combination therapy with pegylated interferon-alfa or other direct antiviral drugs seem mandatory to avoid developing resistance.