Amino acid substitutions in the hepatitis C virus core region of genotype 1b affect very early viral dynamics during treatment with telaprevir, peginterferon, and ribavirin

Substitution of amino acid (aa) 70 and 91 in the core region of hepatitis C virus (HCV) genotype 1b can predict the response to pegylated interferon (PEG‐IFN)/ribavirin combination therapy, but its impact on triple therapy of telaprevir/PEG‐IFN/ribavirin is not clear. The aims of this study were to investigate the rate of HCV RNA loss following 12‐week triple therapy, and determine the effect of aa substitutions on very early (within 48 hr) viral dynamics. Sixty‐seven patients infected with HCV genotype 1b (HCV‐1b) and high viral load who received 12‐week triple therapy were studied. RNA loss could be achieved in 2%, 34%, 80%, 92%, 95%, 94%, and 90% of the patients after 1, 2, 4, 6, 8, 10, and 12 weeks of triple therapy, respectively. After 24‐hr treatment, the proportion of patients with Arg70 and Leu91 substitutions with ≥3.0 log fall in HCV RNA was significantly higher than those with <3.0 log fall ( P  = 0.008). However, the aa substitution patterns in the core region did not influence the fall in HCV RNA after 48‐hr treatment. Multivariate analysis identified substitutions of aa 70 and 91 ( P  = 0.014) and level of viremia at baseline (≥7.0 log IU/ml; P  = 0.085) as independent parameters that determined the ≥3.0 log fall in HCV RNA level after 24‐hr triple therapy. It is concluded that 12‐week triple therapy achieved high rates of loss of HCV RNA in Japanese patients infected with HCV‐1b and high viral load, and that the aa substitution pattern in the core region seems to influence very early viral dynamics. J. Med. Virol. 82:575–582, 2010. © 2010 Wiley‐Liss, Inc.