Enanta Pharmaceuticals, Inc. announced the initiation by AbbVie of six global phase 3 clinical studies evaluating the safety and efficacy of an all-oral, once-daily, ribavirin-free, investigational hepatitis C virus (HCV)treatment consisting of a co-formulated combination of ABT-493, an NS3/4A protease inhibitor, and ABT-530, an NS5A inhibitor, in patients with genotypes 1-6 (GT1-6) chronic HCV infection. ABT-493 is Enanta's next-generation protease inhibitor being developed by AbbVie and is one of the two direct-acting antivirals in the combination treatment being investigated in the phase 3 studies. The ENDURANCE and EXPEDITION studies are part of AbbVie's Phase 3 HCV pipeline program and will recruit approximately 1,600 patients globally, from over 250 study sites in 27 countries.

The primary efficacy endpoint of all six studies is the rate of sustained virologic response at 12 weeks post-treatment. The four ENDURANCE studies evaluate AbbVie's investigational regimen in patients without cirrhosis for up to 12 weeks. ENDURANCE-1 compares SVR in GT1 chronic HCV infected patients who received ABT-493/ABT-530 treatment durations of 12 weeks and as short as eight weeks.

ENDURANCE-2 evaluates AbbVie's investigational regimen versus placebo in GT2 chronic HCV infected patients. ENDURANCE-3 compares AbbVie's investigational regimen with sofosbuvir/daclatasvir in treatment-naïve patients with GT3 chronic HCV infection. ENDURANCE-4 evaluates GT4-6 chronic HCV infected patients.

The EXPEDITION trials evaluate AbbVie's investigational regimen for 12 weeks in difficult to treat patient populations with chronic HCV infection. EXPEDITION-1 evaluates AbbVie's investigational regimen in GT1, 2, 4-6 chronic HCV infected patients with compensated cirrhosis (Child-Pugh A). EXPEDITION-4 evaluates GT1-6 chronic HCV infected patients with severe renal impairment and end-stage renal disease, with or without compensated cirrhosis.