Adding the experimental hepatitis C virus (HCV) protease inhibitor telaprevir to standard HCV therapy both increased the response rate and shortened the duration of treatment in HIV-negative patients infected with HCV genotype 1, according to a study published April 30 in The New England Journal of Medicine.

HCV genotype 1 is the most common strain of HCV in the United States. Unfortunately, it is also the most difficult to treat. With standard HCV treatment, consisting of pegylated interferon combined with ribavirin, less than half of people with genotype 1 have a sustained virologic response (SVR), defined as maintaining undetectable HCV levels for at least six months after completing a 48-week course of treatment. SVR rates are even lower for people with genotype 1 who are also infected with HIV.

To determine the safety and efficacy of adding telaprevir to standard treatment, John McHutchison, MD, from Duke University in Durham, North Carolina, and his colleagues conducted a study involving 250 HIV-negative adults infected with HCV genotype 1. People were randomized to receive either a placebo or telaprevir for 12 weeks plus standard HCV treatment. People receiving the placebo took standard HCV treatment for 48 weeks. People receiving telaprevir also took the standard interferon/ribavirin treatment for 12, 24 or 48 weeks.

Adding telaprevir not only shortened the duration of standard treatment required to achieve an SVR, but it also increased the number of people who achieved an SVR. Just 41 percent of people on standard treatment achieved an SVR after 48 weeks of therapy, compared with 61 and 67 percent who achieved an SVR on telaprevir plus 24 weeks or 48 weeks of standard treatment, respectively. Only 36 percent of people on telaprevir plus 12 weeks of standard treatment achieved an SVR, and this arm was not included in the larger analysis.

More people taking telaprevir stopped taking treatment compared with people on the placebo—21 percent compared with 11 percent, mostly due to rash. While it is too early to tell how well telaprevir may improve HCV treatment response rates in people who are also infected with HIV, these study results are encouraging.