( -NS4A Antagonist Demonstrates Clinical ...)Achillion Presents Positive Data on Novel Mechanism for Treating,HCV at EASL Annual Meeting,Health

NEW HAVEN, Conn., April 16, 2007 /PRNewswire-FirstCall/ -- Achillion Pharmaceuticals, Inc. today announced the presentation of data validating the clinical antiviral activity of one of Achillion's NS4A antagonists, ACH-806, for the treatment of hepatitis C virus (HCV) infection at the 42nd Annual Meeting of the European Association for the Study of the Liver (EASL). In three separate presentations, Achillion researchers discussed the potent antiviral activity in HCV-infected subjects, synergy with other classes of HCV inhibitors, and the unique mode of action of a NS4A antagonist. Achillion has shown that blocking NS4A, a viral protein that binds to a portion of HCV protease, inhibits HCV replication. This program is part of a collaboration and exclusive license agreement with Gilead Sciences for the research, development and commercialization of compounds for the treatment of chronic HCV.

In a late-breaker session on April 14th at 5:00 PM, John Pottage, M.D., Senior Vice President and Chief Medical Officer at Achillion, discussed clinical data in a presentation titled, "Short-term Antiviral Activity and Safety of ACH-806 (GS-9132), an NS4A Antagonist, in HCV Genotype 1 Infected Individuals." The randomized, double-blind, placebo-controlled dose-escalation trial measured the antiviral activity, safety and pharmacokinetics of 300 mg of ACH-806 or placebo, dosed orally twice daily as a monotherapy over 5 days. The mean change in HCV RNA (log10) at day 5 was a decrease of 0.91 from baseline for treated subjects versus an increase of 0.05 for control subjects. Elevations in serum creatinine (a marker of kidney function) were observed in ACH-806 treated subjects and were reversible after completion of dosing.

"This study provides the first demonstration of human antiviral a
'"/>