Protease inhibitors partially overcome the interferon nonresponse phenotype in patients with chronic hepatitis C

The outcome of triple therapy with protease inhibitors (PI) depends on the intrinsic response to interferon. Interferon‐stimulated gene (ISG) expression differs by cell type in the liver and is a strong predictor of interferon responsiveness. Patients who respond well to interferon have low/absent ISG expression in hepatocytes but significant ISG expression in macrophages. Nonresponders (NRs) show the opposite pattern. We aimed to determine the association between cell‐type‐specific ISG staining and treatment outcome with PI‐based triple therapy. Liver biopsy tissue from consecutive patients treated with boceprevir or telaprevir with peginterferon and ribavirin was stained for myxovirus A (MxA). Staining was scored 0–3 in macrophages (M‐MxA) and hepatocytes (H‐MxA), and IL28B genotyping was performed. Of 56 patients included 41 achieved SVR (73%) (sustained virological response), 2 (4%) relapsed, 10 (18%) were NRs, and 3 (5%) were lost to follow‐up. Median M‐MxA staining was stronger and H‐MxA staining was weaker in patients who achieved SVR. MxA staining correlated with IL28B genotype and with the HCV RNA decline during lead‐in phase. However, unlike with dual therapy, the negative predictive value (NPV) of absent or weak M‐MxA staining was poor (42%), while the positive predictive value improved (93%). Although by multivariable logistic regression M‐MxA staining was significantly associated with SVR (OR 4.35, 1.32–14.28, P = 0.012), the predictive ability was inadequate to withhold therapy. The interaction between macrophages and hepatocytes plays a critical role in interferon responsiveness; however, the addition of a PI at least partially overcomes the interferon nonresponse phenotype making the predictive ability of ISG staining less clinically useful.