IDENIX PROVIDES UPDATE ON DEVELOPMENT PROGRAM FOR VALOPICITABINE

Idenix Pharmaceuticals will begin a Phase III clinical trial of Valopicitabine in treatment-refractory hepatitis C (HCV) patients by the end of the first quarter of 2006. The company is currently sponsoring a Phase IIb clinical trial in treatment-refractory patients, which includes a patient cohort receiving valopicitabine 800 mg plus pegylated interferon.

Valopicitabine, which is administered orally, is intended to block HCV replication by specifically inhibiting the HCV RNA polymerase, the enzyme that makes new copies of HCV viral chromosome inside infected cells. The ongoing clinical trials are designed to evaluate the combination of valopicitabine and pegylated interferon in HCV Genotype 1 patients who previously failed to respond to antiviral treatment, as well as in Genotype 1 patients who have not been treated previously. Preliminary results from trials to date have demonstrated that the antiviral effect of valopicitabine is enhanced when this agent is used in combination with pegylated interferon.