Durability of sustained virological response to glecaprevir/pibrentasvir and resistance development: A long-term follow-up study

Background and Aims: This study aimed to determine durability of sustained virologic response (SVR) in hepatitis C virus-infected participants treated with glecaprevir- and/or pibrentasvir-containing regimens. Methods: M13-576, a rollover study, evaluated the durability of SVR in a follow-up period of approximately 3 years after hepatitis C virus genotype 1–6-infected participants received a glecaprevir- and/or pibrentasvir-containing regimen in previous phase 2/3 clinical trials. The primary efficacy endpoint was the percentage of participants maintaining SVR and the percentage of participants experiencing relapse or reinfections. Resistance-associated substitutions and safety outcomes related to liver progression were also assessed. Results: Of 384 participants enroled, 377 participants were included in the as-observed population and 287 participants completed the study. In prior studies, 99.7% (376/377) of participants achieved SVR12; of those, an observed 99.5% (374/376) and 100% (286/286) completing the study, maintained SVR. After non-responder imputation of missing data, 286/376 participants (76%) maintained SVR. The participant previously not achieving SVR was a treatment-experienced male with compensated cirrhosis who had NS3 and NS5A substitutions at enrolment, which remained detectable for 12 months. Of the two participants not maintaining SVR, one was re-infected and one experienced late relapse at post-treatment week 60. Five participants (all with a fibrosis stage ≥F3) had hepatocellular carcinoma. No events were deemed related to glecaprevir/pibrentasvir. Conclusions: Glecaprevir/pibrentasvir demonstrated long-term durability of efficacy after SVR12 was achieved. Hepatic-related decompensation events were not seen. Owing to low incidence of virologic failure, conclusions were not drawn on persistence of resistance-associated substitutions.