Dynamic evolution of therapy for chronic hepatitis C: how will novel agents be incorporated into the standard of care?

There is a need for improved treatment strategies and new therapeutic agents to increase cure rates in chronic hepatitis C virus (HCV) infection. Ongoing trials are aimed at optimizing sustained virological response rates with pegylated interferon (PEG-IFN) plus ribavirin. For a new agent to supplant the standard of care it must augment the strengths or compensate for the weaknesses of PEG-IFN plus ribavirin. To improve cure rates on its own, a new agent must not only suppress replication of the virus, but also clear infected hepatocytes. It is now clear that new anti-HCV agents will be used, at least initially, against a backbone of PEG-IFN plus ribavirin. A broad spectrum of agents is under investigation and it is hoped that these drugs will ultimately increase cure rates, reduce the required duration of therapy, improve tolerability and possibly simplify therapy. Reductions in serum HCV RNA ranging from 2 to 5 log10 IU/ml have been obtained in human trials with NS3/4A protease inhibitors and polymerase inhibitors. A minimum of additive reductions in serum HCV RNA levels have been observed when agents in these classes have been administered with PEG-IFN plus ribavirin in treatment-naive patients. Preliminary results in non-responders to IFN are less promising. Combinations of small molecules will be needed in order to produce sustained suppression of HCV replication in the absence of the standard of care, and such large clinical trials are several years away. The treatment paradigm for chronic hepatitis C continues to evolve and will eventually incorporate new drugs as they are approved.