Response guided therapy in patients with chronic hepatitis C - yesterday, today and tomorrow.

The rapidity of viral disappearance on antiviral treatment of chronic hepatitis C with peginterferon/ribavirin correlates with the cure rate. The earlier the virus becomes undetectable, the higher are the response rates. This observation is the basis of response-guided therapy. Viral clearance within the first 4 weeks of treatment is called a rapid virologic response (RVR). The rate of RVR varies among various populations, with the highest one observed in Asian patients and the lowest in African-Americans. This can be partly explained by a polymorphism in the region of the 5IL28B gene. In patients infected with genotypes 1 and 4 with RVR treatment with peginterferon/ribavirin can be shortened to just 24 weeks (with SVR rates of >80%). In contrast, patients with a slow decline in viral load (>2 log drop after 12 weeks with still detectable virus) may benefit from treatment extension to 72 weeks. The virologic response criteria were modified for triple therapy (extended RVR; HCV-RNA undetectable: telaprevir week 4 and 12; boceprevir week 8 and 24). Patients with eRVR can be cured by an abbreviated treatment regime. Further modification and unification of response criteria are needed for the currently evaluated interferon-free treatment regimes.