BACKGROUND: Single nucleotide polymorphisms (SNPs) associated with IL28B influence the outcome of peginterferon-α/ribavirin therapy of chronic hepatitis C virus (HCV) infection. We analyzed the kinetics of HCV RNA during therapy as a function of IL28B SNPs.
METHODS: IL28B SNPs rs8099917, rs12979860, and rs12980275 were genotyped in 242 HCV treatment-naïve Caucasian patients (67% genotype 1, 28% genotype 2 or 3) receiving peginterferon-α2a (180 μg weekly) and ribavirin (1000-1200 mg daily) with serial HCV-RNA quantifications. Associations between IL28B polymorphisms and early viral kinetics were assessed, accounting for relevant covariates.
RESULTS: In the multivariate analyses for genotype 1 patients, the T allele of rs12979860 (T(rs12979860)) was an independent risk factor for a less pronounced first phase HCV RNA decline (log(10) 0.89 IU/ml among T carriers vs. 2.06 among others, adjusted P<0.001) and lower rapid (15% vs. 38%, adjusted P=0.007) and sustained viral response rates (48% versus 66%, adjusted P<0.001). In univariate analyses, T(rs12979860) was also associated with a reduced second phase decline (P=0.002), but this association was no longer significant after adjustment for the first phase decline (adjusted P=0.8). In genotype 2/3 patients, T(rs12979860) was associated with a reduced first phase decline (adjusted P=0.04), but not with second phase decline.
CONCLUSION: Polymorphisms in IL28B are strongly associated with the first phase viral decline during peginterferon-α/ribavirin therapy of chronic HCV infection, irrespective of HCV genotype.