Interleukin 28B gene variation at rs12979860 determines early viral kinetics during treatment in patients carrying genotypes 2 or 3 of hepatitis C virus.

Single-nucleotide polymorphisms upstream of the interleukin 28B (interferon λ3) gene (IL28B) strongly influence treatment efficacy in patients carrying hepatitis C virus (HCV) of genotype 1. In patients receiving 12 or 24 weeks of interferon-ribavirin therapy for infection with genotype 2 or 3 (n = 341), we found that rs12979860 strikingly determined the first phase of viral elimination (P < .001). In patients treated for 24 weeks, rs12979860 also predicted the rate of sustained virologic response (P = .02), especially among those with high baseline HCV RNA levels (P = .002) or older than 45 years (P = .01). Patients carrying CC(rs12979860) had higher baseline HCV RNA levels (P < .001) and did not, when treated for 12 weeks, achieve sustained virologic response more often than those carrying CT(rs1297986) or TT(rs1297986). The results indicate that IL28B gene testing may identify patients carrying genotype 2 or 3 who could benefit from extended treatment.