Recently direct-acting
antiviral agents, such as hepatitis C virus (HCV) non-structural 3/4A (
NS3/4A) protease inhibitors (PI), have been introduced, and triple
therapy regimens that include PI with conventional pegylated
interferon α and
ribavirin have significantly improved the sustained virological response (SVR) rate, up to 80% for both treatment-naïve and treatment-experienced patients with HCV genotype 1. We here report for the first time a case of the successful treatment of HCV genotype 1
infection with a first generation PI
drug (
telaprevir) based triple
therapy after treatment failure with a second generation PI
drug (
vaniprevir) based triple
therapy. A 67-year-old treatment-naïve Japanese man with HCV genotype 1b
infection took part in a phase III clinical trial of
vaniprevir-based triple
therapy. His serum HCV
RNA had become undetectable at week 2 and SVR was highly expected, but HCV
RNA reappeared at week 4 after
vaniprevir treatment. Polymerase chain reaction direct sequence of the HCV NS3/4A gene at week 8 after
vaniprevir treatment showed the emergence of a
vaniprevir-resistance mutation (D168V), the probable reason for the treatment failure. Six months later,
retreatment with
telaprevir-based triple
therapy was started. Although the dosages of
telaprevir and
ribavirin had to be reduced due to severe
anemia, the patient achieved an SVR. This case shows the value of repeating PI-based triple
therapy with a different
drug, a process that would reduce the chance of
drug resistant mutation.