Resistance analysis and treatment outcomes in hepatitis C virus genotype 3‐infected patients within the Italian network VIRONET‐C

Aim This study aimed to investigate the role of resistance‐associated substitutions (RASs) to direct‐acting‐antivirals (DAAs) in HCV genotype 3 (GT3). Methods Within the Italian VIRONET‐C network, a total of 539 GT3‐infected patients (417 DAA‐naïve and 135 DAA‐failures, of them, 13 at both baseline and failure) were analysed. Sanger sequencing of NS3/NS5A/NS5B was performed following home‐made protocols. Results The majority of patients were male (79.4%), 91.4% were injection drug users, 49.3% were cirrhotic and 13.9% were HIV co‐infected. Phylogenetic analysis classified sequences as GT3a‐b‐g‐h (98%‐0.4%‐0.2%‐1.2%) respectively. Overall, 135 patients failed a DAA regimen: sofosbuvir (SOF)/daclatasvir (DCV) or velpatasvir (VEL)±ribavirin (RBV) (N = 91/15) and glecaprevir (G)/pibrentasvir (P) (N = 9). Moreover, 14.8% of patients were treated with suboptimal regimens for GT3: 3D ± RBV (Paritaprevir/r + Ombitasvir+Dasabuvir, N = 15), SOF + Simeprevir (SIM) (N = 1) or SOF/Ledipasvir (LDV) ± RBV (N = 4). RAS prevalence was 15.8% in DAA‐naïve patients. At failure, 81.5% patients showed at least one RAS: 11/25 (44.0%) in NS3, 109/135 (80.7%) in NS5A, 7/111 (6.3%) in NS5B SOF‐failures. In NS5A‐failures, Y93H RAS was the most prevalent (68.5% vs 5.1% DAA‐naïve, P