Simeprevir versus telaprevir with peginterferon and ribavirin in previous null or partial responders with chronic hepatitis C virus genotype 1 infection (ATTAIN): A randomised, double-blind, non-inferiority phase 3 trial

Background: We did a phase 3 study in previous non-responders with chronic hepatitis C virus (HCV) genotype 1 infection and compensated liver disease that related to the standard of care for these patients at the time this study was initiated. We investigated whether simeprevir is non-inferior in terms of efficacy to telaprevir, each in combination with peginterferon alfa-2a and ribavirin. Methods: We did this randomised, double-blind, phase 3 trial at 169 investigational sites in 24 countries. We enrolled adults (≥18 years) with chronic HCV genotype 1 infection, compensated liver disease, and plasma HCV RNA higher than 10 000 IU/mL who were null or partial responders during at least one previous course of peginterferon alfa-2a and ribavirin treatment. We randomly assigned (1:1) patients (stratified by HCV genotype 1 subtype [1a plus other/1b] and previous treatment response [partial or null]) to receive simeprevir (150 mg once a day) plus telaprevir placebo (three times a day 7-9 h apart) or telaprevir (750 mg three times a day) plus simeprevir placebo (once a day) in combination with peginterferon alfa-2a and ribavirin for 12 weeks followed by 36 weeks of peginterferon alfa-2a and ribavirin alone. The primary efficacy endpoint was sustained virological response 12 weeks after end of treatment (SVR12) in the intention-to-treat and the per-protocol population. We compared groups with the Cochran-Mantel-Haenszel test. We established a non-inferiority margin of 12%. Adverse events were reported descriptively. This trial is registered with ClinicalTrials.gov, number NCT01485991. Findings: Patient screening began on Jan 19, 2012, and the last visit was on April 7, 2014. We included 763 patients (472 previous null responders [62%]). Simeprevir and peginterferon alfa-2a and ribavirin was non-inferior to telaprevir and peginterferon alfa-2a and ribavirin for SVR12 (54% [203/379] vs 55% [210/384]; difference -1·1%, 95% CI -7·8 to 5·5; p=0·0007). SVR12 was achieved in 70% (101/145) versus 68% (100/146) of previous partial responders and 44% (102/234) versus 46% (110/238) of previous null responders with simeprevir and peginterferon alfa-2a and ribavirin and telaprevir and peginterferon alfa-2a and ribavirin treatment, respectively. We recorded differences between treatment groups in simeprevir or telaprevir-related adverse events (69% [261/379] in the simeprevir group vs 86% [330/384] in the telaprevir group), serious adverse events (2% [8/379] vs 9% [33/384]), and adverse events leading to simeprevir or telaprevir discontinuation (2% [7/379] vs 8% [32/384]). Interpretation: Simeprevir once a day with peginterferon alfa-2a and ribavirin was well tolerated in HCV genotype 1-infected previous non-responders and was non-inferior to telaprevir, thus providing an alternative treatment in areas of the world where all-oral HCV regimens are not available or accessible. Funding: Janssen.