Moreno et al. investigated the therapeutic potential of TMC435—an NS3/4a protease inhibitor—for patients infected with HCV genotypes 2–6 (TMC435 is already in phase III development for patients with HCV genotype 1 infection). 37 treatment-naive patients were enrolled; treatment consisted of 200 mg TMC435 once daily for 7 days. Antiviral activity at day 8 was greatest for genotype 6, followed by genotypes 4, 2 and 5; however, no antiviral activity was evident against genotype 3.