Treatment outcomes in hepatitis C virus genotype 1a infected patients with and without baseline NS5A resistance‐associated substitutions

Background&aims The presence of baseline resistance-associated substitutions (RASs) reduced sustained virologic response (SVR) rates in chronic hepatitis C virus (HCV) genotype 1a infected patients treated with Elbasvir/Grazoprevir (EBR/GZR). This study aimed to evaluate the frequency of NS5A RASs and treatment outcomes in patients for whom EBR/GZR was intended. Methods We sequenced NS5A in 832 samples from German genotype1a-infected DAA-naive patients population-based, which were collected in the European Resistance Database. Treatment outcomes and clinical parameters were evaluated in 519 of these patients retrospectively. Results Overall, 6.5% of patients harbored EBR-specific NS5A RASs at baseline, including Q30H/R (3.3%), L31M (1.8%), Y93H (1.6%) and other individual variants. Antiviral treatment, including EBR/GZR, was initiated in 88% of patients. In the absence of RASs, the majority of patients received EBR/GZR for 12 weeks (57%) and the SVR rate was 97% compared to 99% SVR achieved using other DAA regimens (LDV/SOF±RBV, G/P, PrOD+RBV, VEL/SOF). Various regimens were used in the presence of RASs and SVR rates were high following treatment with LDV/SOF (100%), G/P (83%), PrOD/RBV (100%), VEL/SOF (100%), SMV/SOF (100%) and EBR/GZR+RBV for 16 weeks (100%). However, two patients received EBR/GZR for 16 weeks without RBV and one relapsed. Conclusions EBR/GZR treatment with or without RBV for 12 or 16 weeks according to a baseline RAS analysis was highly effective with ≥97% SVR in patients with genotype 1a. EBR/GZR without RBV should be avoided in patients with RASs. High SVR rates were also achieved using other 8 or 12 weeks DAA regimens.