TMC-435350 (TMC 435350; TMC 435; TMC-435350) is an inhibitor of NS3/4A protease, which plays an important role in HCV replication. Data from phase I and II clinical trials of TMC-435350 (TMC 435350; TMC 435; TMC-435350) to date have shown that this agent is well tolerated as a once-daily oral therapy and provides potent antiviral activity in HCV genotype 1-infected subjects, with restoration of liver enzymes and no evidence of viral breakthrough.