IFNL3 (also known as IL28B) encodes interferon (IFN)-λ3, a member of IFN-λ family, playing important antiviral and immune-modulatory roles.1
Pegylated (PEG) IFN-α and ribavirin (RBV) are indicated to treat hepatitis C virus (HCV) infection. Eradication of HCV is measured by sustained virologic response (SVR). Various studies have independently associated variations in IFNL3 with PEG-IFN-α and RBV-induced SVR.2 For patients treated with PEG-IFN-α and RBV alone, IFNL3 genotype is the strongest pretreatment predictor of HCV treatment response.3 In many countries including United States and countries of European Union, direct-acting antiviral agents, boceprevir and telaprevir, were approved to treat HCV genotype 1 infection in combination with PEG-IFN-α and RBV. Patients with favorable IFNL3 genotype have higher response rate to the combined treatment of PEG-IFN-α and RBV with boceprevir or telaprevir. The clinical pharmacogenetics implementation consortium (CPIC) guideline on the PEG-IFN-α-based treatment argues that for the patient who is considering whether to under HCV therapy with boceprevir regimen, IFNL3 is the most helpful predictor of the treatment response.3
Click here for the full CPIC guideline for IFNL3 (IL28B) genotype and PEG IFN-α-based regimens.