By Liz Highleyman

It is well known that people with hepatitis C virus (HCV) genotypes 2 or 3 respond better to interferon-based therapy than patients with hard-to-treat genotypes 1 or 4. However, HCV genotype 6 -- which occurs primarily in southeast Asia -- has been less extensively studied.

As described in the September 15, 2008 Journal of Infectious Diseases, researchers from Hong Kong conducted a study to evaluate pegylated interferon plus ribavirin for the treatment of genotype 6 chronic hepatitis C, and to compare its efficacy with treatment for HCV genotype 1.

The study included 42 patients with chronic HCV infection, 21 each with genotype 1 and 6. All participants were treated with either pegylated interferon alfa-2a (Pegasys; n = 20) or pegylated interferon alfa-2b (PegIntron; n = 22) plus ribavirin for 48 weeks.

Results

• There was no significant difference between genotypes 1 and genotype 6 patients with regard to rates of early virological response (76% vs 81%; P > 0.05).

• This was also the case for end-of-treatment response (71% for genotype 1 vs 81% for genotype 6; P > 0.05).

• However, patients with genotype 6 had a higher rate of sustained virological response (SVR, or continued undetectable HCV RNA 6 months after completion of therapy) than those with genotype 1 (86% vs 52%; P = 0.019).

• There was no significant difference in the SVR rate between patients receiving Pegasys versus PegIntron.

• In a multivariate analysis, genotype was the only significant factor associated with SVR (P = 0.039).

• The overall adverse events profile was similar in the genotype 1 and genotype 6 groups.

In conclusion, the study authors wrote, "Treatment with pegylated interferon and ribavirin for 48 weeks resulted in a significantly higher rate of SVR in patients infected with genotype 6 than in those infected with genotype 1."

They added that further studies are needed to determine whether lower dosages or shorter duration of therapy -- perhaps 24 weeks, which is the standard of care for patients with genotypes 2 or 3 -- may be sufficient for those with genotype 6.

10/14/08

Reference
J Fung, C-L Lai, I Hung, and others. Chronic hepatitis C virus genotype 6 infection: response to pegylated interferon and ribavirin. Journal of Infectious Diseases 198(6): 808-812. September 15, 2008. (Abstract).