Impact of IL28B on treatment outcome in hepatitis C virus G1/4 patients receiving response-guided therapy with peginterferon alpha-2a (40KD)/ribavirin.

UNLABELLED: The IL28B genotype is the most important pretreatment predictor of treatment outcome in patients with chronic hepatitis C. The impact of the rs12979860 genotype on relapse was retrospectively evaluated in genotype 1/4 patients who received response-guided therapy with peginterferon alpha-2a 180 µg/week plus ribavirin 1,000/1,200 mg/day in a large, randomized, multicenter study. Patients with a rapid virologic response (RVR: hepatitis C virus [HCV] RNA <50 IU/mL) at week 4 were treated for 24 weeks; those with a slow virologic response (no RVR but undetectable HCV RNA or ≥ 2-log(10) decrease at week 12) were randomized to 48 (group A) or 72 weeks of treatment (group B). Relapse rates were compared by rs12979860 genotype (C/C versus combined T/C or T/T [T/*]) in patients with confirmed end-of-treatment response and known end-of-follow-up status (sustained virologic response [SVR] or relapse). The rs12979860 genotype was determined for 340/551 study participants. In patients with RVR and C/C or T/* genotype, relapse rates were similar (10.7% versus 15.2%). In patients randomized to groups A and B, relapse rates were similar in patients with C/C genotype randomized to group A (26.9%) and group B (20.0%). In contrast, relapse rates in T/* patients differed markedly between groups A and B, overall (42.9% and 18.8%; P < 0.025, respectively) and in those with low (<400,000 IU/mL: 37.5% versus 18.8%) and high (≥ 400,000 IU/mL: 45.0% versus 18.8%) baseline viral loads. CONCLUSION: The results suggest that the benefits of extended therapy are restricted to patients with a T allele. Relapse rates are highest in patients with T/* genotype and are markedly higher in slow responders treated for 48 weeks compared with 72 weeks.