Short‐Duration AL‐335, Odalasvir, With or Without Simeprevir, in Patients With HCV GT1 or 3 Infection Without Cirrhosis

: This open-label, phase IIa study assessed the safety, pharmacokinetics, and efficacy of direct-acting antiviral agent (DAA) regimens in patients with chronic hepatitis C virus (HCV) infection. Multiple 6-12-week oral regimens of 400-800 mg once daily (QD) AL-335 + 50 mg QD/every other day odalasvir ± 75-150 mg QD simeprevir were evaluated in treatment-naive, HCV genotype (GT)1/3-infected patients without cirrhosis. Safety/pharmacokinetic parameters, HCV-RNA, and sequencing data were assessed. Treatment regimens for later study cohorts were adjusted based on emerging data. In total, 112 patients were enrolled. Three serious treatment-emergent adverse events occurred, one of which (a Mobitz type 1 second-degree atrioventricular block [Wenckebach]) was possibly related to high odalasvir exposure and resulted in premature discontinuation of study drugs. No other clinically significant safety findings were identified. GT1-infected patients receiving 3-DAA for 6-8 weeks achieved 100% sustained virologic response 12 weeks and 24 weeks after the end of treatment (sustained virologic response [SVR12/24]). GT1-infected patients receiving 2-DAA or GT3-infected patients receiving 3-DAA had SVR12/24 less than 90%, whether treated for 8 weeks or 12 weeks. Virologic failure was associated with the emergence of generally persistent NS5A and/or transient NS5B resistance-associated substitutions in most patients. Pharmacokinetic characteristics of the three drugs were also elucidated. Conclusions: In treatment-naive subjects without cirrhosis, AL-335 + odalasvir + simeprevir for 6-8 weeks was generally safe and highly efficacious against HCV GT1. However, inadequate efficacy was observed for the 2-DAA regimen in GT1-infected subjects and the 3-DAA regimen in GT3-infected subjects.