Achillion Pharmaceuticals’ ACH-2928, a first-generation NS5A inhibitor, has reported positive results in a Phase Ib clinical trial for the treatment of chronic hepatitis C.

The randomised, double-blind, placebo-controlled Phase Ia/Ib clinical trial is intended to evaluate the safety, tolerability, pharmacokinetic profile and antiviral activity of ACH-2928.

The study includes three segments, namely assessment of single ascending oral doses in healthy volunteers, evaluation of three days of oral repeat doses in subjects with genotype Ia or IIb hepatitis C, and a five-day multiple ascending doses segment in healthy volunteers.

The Phase Ib trial has demonstrated that patients treated with ACH-2928 achieved a mean maximum 3.68 log10 reduction in hepatitis C RNA after three-day monotherapy of 60mg once daily, along with good safety and tolerability data both in healthy volunteers and in patients with hepatitis C.

During the oral repeat doses segment, out of 10 patients, two patients received placebo, while eight patients were treated with three doses of 60 mg ACH-2928 administered once daily.

The trial segment of the study demonstrated that ACH-2928 was well tolerated at all doses evaluated up to and including the maximum dose of 500mg with no serious adverse events.

Based on the preliminary results, the ongoing Phase I study will continue to assess the pharmacokinetic, pharmacodynamic, and antiviral profile of ACH-2928. Phase I results are expected during the second quarter of 2012.

The company is also planning to commence clinical development of its second generation NS5A inhibitor ACH-3102 during the first half of 2012.

Achillion president and CEO Michael Kishbauch said NS5A inhibitors with a protease inhibitor, has attained sustained viral responses in clinical trials to treat genotype 1 HCV populations.

"We believe NS5A inhibitors have emerged as an important component for an all-oral, direct acting antiviral regimen," Kishbauch added.

Achillion chief scientific officer Milind Deshpande said that, along with the Phase I study of ACH-2928, the company is also planning to advance ACH-3102, which has shown in preclinical studies to possess the same potent activity against genotype 1a HCV as ACH-2928.

"We believe these results validate our NS5A development program, and look forward to developing an all-oral combination for clinical evaluation that includes one of our protease inhibitors and an NS5A inhibitor next year," Deshpande added.