Valopicitabine (NM 283) is an investigational compound for the treatment of hepatitis C that is currently being evaluated in ongoing clinical trials. In a majority of patients who have received valopicitabine, adverse events, most notably gastrointestinal side effects, have occurred. For most of these patients, the side effects are mild-moderate, transient and resolve while remaining on treatment. However, in a minority of patients, the side effects persist resulting in treatment discontinuation.

Valopicitabine Phase III Trial Delayed by FDA Due to GI Side Effects

Shares of Idenix Pharmaceuticals fell 28% last week after the company delayed a Phase III trial of valopicitabine. Idenix announced late Thursday that gastrointestinal toxicity observed in some patients participating in a Phase IIb trial prompted the company to modify the trial. Patient dosing levels were cut from 800 milligrams per day to 200 milligrams or 400 milligrams. As a result of the announcement, Idenix stock was hit by a number of price-target revisions from Wall Street analysts.

The good news is that Idenix’s Swiss pharmaceutical partner Novartis announced this week that it will pay Idenix up to $525 million in upfront payments and commercial milestones for valopicitabine as well as clinical funding of $300 million or more. Novartis is a majority shareholder of Idenix.

EASL Abstracts on Valopicitabine for Chronic Hepatitis C

Nezam Afdhal, Chief of Hepatology at Beth Israel Deaconess Medical Center in Boston and Associate Professor at Harvard Medical School, will present "Valopicitabine (NM283), Alone or with Peg-Interferon, Compared to Peg-Interferon/Ribavirin (PegIFN/RBV) Retreatment in Hepatitis C Patients with Prior Non-Response to PegIFN/RBV: Week 24 Results" in a meeting session on Friday, April 28 at 10:30 a.m. Central European Time (CET). Dr. Afdhal will present full interim 24-week results from the ongoing phase IIb trial evaluating valopicitabine combined with pegylated interferon in 190 treatment- refractory patients.

Douglas Dieterich, Professor of Medicine at the Mt. Sinai School of Medicine, New York, will present "Early Clearance of HCV RNA with Valopicitabine (NM283) plus Peg-Interferon in Treatment-Naive Patients with HCV-1 Infection: First Results from a Phase IIb Trial" in a late-breaking oral presentation session on Saturday, April 29, at 5:15 p.m. CET. Complete 8-week and available 12-week data from this ongoing trial evaluating 174 treatment- naive patients will be presented.

Xiao-Jian Zhou, Idenix's Associate Director, Clinical Pharmacology, will present "Absence of Effect of Pegylated Interferon Alfa-2b on the Pharmacokinetics of Valopicitabine (NM283) in Patients with Chronic Hepatitis C" in the poster session beginning on Thursday, April 27, 2006 at 7:00 p.m. CET.

Zhou will also present "Safety and Pharmacokinetics of NM107 Following Intravenous Infusion of Escalating Doses in Healthy Volunteers: Determination of Absolute Oral Bioavailability of Valopicitabine (NM283)" in the poster session beginning on Thursday, April 27, 2006 at 7:00 p.m. CET.

Vadim Bichko, Idenix's Director, Research, will present "Long-Term Study of NM283 (Valopicitabine) Resistance Using Bovine Viral Diarrhea Virus" in the poster session beginning on Thursday, April 27, 2006 at 7:00 p.m. CET.

03/31/06

Sources
PRNewswire-FirstCall. Idenix Announces Thirteen Data Presentations at the 2006 European Association for the Study of the Liver. March 27, 2006.

http://www.idenix.com.