High sustained virologic response rate after interferon monotherapy in Japanese hepatitis C patients with a low HCV RNA titer and/or HCV genotype 2. A prospective study.

OBJECTIVE: Hepatitis C virus (HCV) RNA titer and HCV genotype are considered to be major determinants of the outcome of interferon monotherapy. To clarify whether interferon monotherapy is really effective in patients with the appropriate viral parameters, we prospectively examined these parameters and treated the patients with interferon monotherapy. METHODS: Sixty-four patients with an HCV RNA titer <100 kIU/ml and/or HCV genotype 2 were enrolled in the study. Eighteen patients with an HCV RNA titer >100 kIU/ml and genotype 1 were also enrolled as controls. All patients were treated with 10 megaunits of interferon-alpha2b every day for 2 weeks and then 3 times a week for 24 weeks. RESULTS: Of the 64 patients with either HCV RNA <100 kIU/ml and/or genotype 2, seven dropped out from the study. Of the remaining 57 who completed the treatment, 48 (84%) showed a virologic sustained response. In contrast, only 4 of the 18 patients (22%) with HCV RNA >100 kIU/ml and genotype 1 were virologic sustained responders (p < 0.001). CONCLUSION: Our current study showed that the patients with HCV RNA <100 kIU/ml and/or HCV genotype 2 are good candidates for interferon monotherapy.