IL-28B As a Predictor of Sustained Virologic Response in Patients with Chronic Hepatitis C Virus Infection

Genome-wide association studies have recently identified single nucleotide polymorphisms in proximity to the interleukin-28B (IL-28B) gene that can predict sustained virologic response (SVR) in patients with chronic hepatitis C virus (HCV) infection who are undergoing therapy with pegylated interferon (IFN) a and ribavirin. IL-28B encodes IFN-λ3, a type III IFN involved in host antiviral immunity. Favorable variants of the 2 most widely studied IL-28B polymorphisms, rs1 2979860 and rs8099917, are strong pretreatment predictors of early viral clearance and SVR in patients with genotype 1 HCV infection. Variations in the distribution of IL-28B alleles may partly explain differences in SVR rates among ethnic groups. Further investigations have implicated IL-28B in the development of chronic HCV infection versus spontaneous resolution of acute infection and suggest that IL-28B may be a key factor involved in host immunity against HCV. Clinical trials of IFN-λ as a therapeutic agent for chronic HCV infection are currently underway. The use of IL-28B polymorphisms as a predictive tool will have a major impact on treatment strategies for chronic HCV infection, particularly in the context of emerging therapies and direct-acting antiviral agents.