High viral eradication with a daily 12-week natural interferon-beta treatment regimen in chronic hepatitis C patients with low viral load

Virological sustained response (SR) is achieved in 31-49% of patients with chronic hepatitis C with combination therapy using interferon (IFN) -alpha and ribavirin for 24-48 weeks. However, as a period of 24-48 weeks is a bur den for patients, we investigated the effect of daily intravenous administr ation of natural IFN-beta for 12 weeks in this study. In all, 112 patients were enrolled and received a daily administration of 6 MU of natural IFN-be ta intravenously for 12 weeks. Serum HCV-RNA before treatment was assessed by the competitive reverse-transcription polymerase chain reaction assay. T he patients were divided into two groups according to pretreatment viral lo ad: the low viral load group (N = 25, <6.3 x 10(5) copies/ml), and the high viral load group (N = 87, <greater than or equal to>6.3 x 10(5) copies/ml) who were additionally administered IFN-beta thrice weekly for subsequent 1 4 weeks at the patients' request. Virological SR was obtained in 37% (41/11 2) of all the patients; 88% of those with a low viral load, and 22% of pati ents with a high viral load. Virological SR was attained in 21% of patients with HCV subtype 1, and in 67% of those with subtype 2a. In patients with HCV subtype 1b, virological SR was obtained in patients with the mutant-typ e (greater than or equal to4 amino acid mutations in the NSSA(2209-48)) hav ing a low viral load (4/4), but not in those having a high viral load (0/3) . The results suggest that a daily intravenous administration of natural IF N-beta for 12 weeks showed high therapeutic efficacy in patients with a low viral load despite the shorter treatment period and that the therapeutic e fficacy depends on viral load rather than on the number of NS5A(2209-48) am ino acid mutations.