Idenix Provides Update on Clinical Development Program for Valopicitabine (NM283) for the Treatment of Hepatitis C

CAMBRIDGE, Mass., Dec. 2  /PRNewswire-FirstCall/ -- Idenix Pharmaceuticals, Inc., (NASDAQ:IDIX), announced today that the company met with the United States Food and Drug Administration (FDA) on November 30, 2005 to discuss the clinical development program for valopicitabine (NM283) for the treatment of hepatitis C.  Based upon this meeting, the company anticipates finalizing the study design for a phase III clinical trial in treatment-refractory patients by the end of the first quarter of 2006 and starting to enroll patients thereafter.

At the meeting, the FDA requested additional information from the two ongoing phase IIb clinical trials evaluating valopicitabine. In response, Idenix plans to provide the FDA with comprehensive 24-week data from the ongoing phase IIb clinical trial in treatment-refractory patients.  Idenix also expects to provide initial data from the ongoing phase IIb trial evaluating valopicitabine in treatment-naive patients, which includes a patient cohort receiving valopicitabine 800 mg plus pegylated interferon beginning on day 1 of treatment.  This is the treatment regimen that the company currently expects may be evaluated in phase III clinical trials.  The company anticipates that it will provide in January 2006 these additional data that have been requested and thereafter meet with the FDA to review such additional data.  At that meeting, the company anticipates further discussing with the FDA the proposed phase III clinical trial protocol.

"We are pleased with the interaction we have had with the FDA to date regarding valopicitabine development," said Jean-Pierre Sommadossi, chief executive officer of Idenix. "We are optimistic that we will continue to advance the valopicitabine clinical program, particularly in view of the serious unmet need in the treatment-refractory patient population in hepatitis C," he said.

About Valopicitabine

Valopicitabine, which is administered orally once a day, 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. Initial phase I clinical trials sponsored by Idenix showed that valopicitabine is active in patients infected with the genotype 1 strain of HCV, the strain that infects the majority of patients in North America, Europe, and Japan. The ongoing clinical trials are designed to evaluate the combination of valopicitabine and pegylated interferon in hepatitis C 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 phase II clinical trials to date have demonstrated that the antiviral effect of valopicitabine is enhanced when this agent is used in combination with pegylated interferon.

About Hepatitis C

Hepatitis C is an infectious liver disease caused by the hepatitis C virus. The World Health Organization estimates that 170 million individuals worldwide carry chronic HCV infection, with 3 to 4 million new infections occurring globally each year. It is the most common chronic blood-borne infection in the United States, with 2.7 million people chronically infected. Chronic HCV infection causes inflammation of the liver, which may cause progressive liver damage that can lead to liver scarring, liver cancer, liver failure, and death. Patients infected with HCV genotype 1 are difficult to treat, with half or fewer such patients achieving sustained responses to current standard treatment regimens involving a combination of pegylated interferon plus ribavirin. These "non-responders" or treatment-refractory patients comprise a growing patient population, who have no proven alternative treatments available and who are at risk for progressive HCV-associated liver disease. As the prevalence of severe liver disease attributable to chronic hepatitis C rises, deaths due to complications from hepatitis C infection, currently 8,000 to 10,000 per year in the United States, are expected to increase dramatically over the next 15 to 20 years.

About Idenix

Idenix Pharmaceuticals, Inc. is a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral and other infectious diseases. Idenix's current focus is on the treatment of infections caused by hepatitis B virus, hepatitis C virus and human immunodeficiency virus (HIV).  Idenix's headquarters are located in Cambridge, Massachusetts and it has drug discovery and development operations in Montpellier, France and drug discovery operations in Cagliari, Italy.  For further information about Idenix, please refer to http://www.idenix.com/.

Forward-looking Statements

This press release contains "forward-looking statements" within the meaning of The Private Securities Litigation Reform Act of 1995. Such forward- looking statements can be identified by the use of forward-looking terminology such as, "anticipates," "plans," "expects," "we are optimistic," "will continue to," or similar expressions or by express or implied discussions regarding the company's planned actions in response to the discussions with the FDA, the potential therapeutic benefits and successful development of valopicitabine, or the potential future revenues from valopicitabine. Such forward-looking statements are subject to numerous factors, risks and uncertainties that may cause actual events or results to differ materially from the company's current expectations. There can be no guarantee that valopicitabine will be successfully developed or approved for sale in any market, or that it will reach any particular level of revenue.  In particular, management's expectations regarding valopicitabine could be affected by risks and uncertainties relating to the results of further discussions with the FDA; the timing and success of any submissions to the FDA and other regulatory bodies around the world; the results of clinical trials and other studies with respect to valopicitabine, including any new clinical data, or additional analysis of existing clinical data; the company's dependence on its collaboration with Novartis Pharma AG; the company's ability to obtain additional funding required to conduct its research, development and commercialization activities; the ability of the company to attract and retain qualified personnel; competition in general; and the company's ability to obtain, maintain and enforce patent and other intellectual property protection for valopicitabine. These and other risks which may impact management's expectations regarding valopicitabine are described in greater detail under the caption "Factors That May Affect Future Results" in the company's quarterly report on Form 10-Q for the quarter ended September 30, 2005 and filed with the Securities and Exchange Commission and other filings that the company makes with the Securities and Exchange Commission.

All forward-looking statements reflect the company's expectations only as of the date of this release and should not be relied upon as reflecting the company's views, expectations or beliefs at any date subsequent to the date of this release. Idenix anticipates that subsequent events and developments may cause these views, expectations and beliefs to change. However, while Idenix may elect to update these forward-looking statements at some point in the future, it specifically disclaims any obligation to do so.

Idenix Pharmaceuticals' Contact:

Teri Dahlman: 617-995-9905 

DATASOURCE: Idenix Pharmaceuticals, Inc.



CONTACT:  Teri Dahlman of Idenix Pharmaceuticals, Inc., [phone] 



Web site:  http://www.idenix.com/

Copyright