Telbivudine Achieves Primary Endpoint in Phase III GLOBE Trial, Largest Ever Registration Trial in Hepatitis B

Telbivudine Achieves Primary Endpoint in Phase III GLOBE Trial,
Largest Ever Registration Trial in Hepatitis B
* Idenix and Novartis anticipate first regulatory filing by the end of 2005 *
Complete GLOBE results to be submitted for presentation at American Association
for the Study of Liver Diseases meeting in November 2005 


CAMBRIDGE, Mass., July 28  /PRNewswire-FirstCall/ -- Idenix Pharmaceuticals,
Inc. (NASDAQ:IDIX) and Novartis Pharma AG announced today that the phase III
GLOBE registration trial for telbivudine successfully reached its primary,
composite efficacy endpoint of therapeutic response at one year in chronic
hepatitis B patients. This endpoint, which was designed to assess if
telbivudine was at least as effective as lamivudine, evaluated the combination
of viral suppression (serum HBV DNA suppression below 100,000 copies/mL)
coupled with either improved liver function (ALT normalization) or loss of
detectable hepatitis B e-antigen (HBeAg).

The largest hepatitis B registration trial to date, GLOBE enrolled more than
1,350 patients in over 130 medical centers worldwide. The ongoing trial is
evaluating the safety and efficacy of telbivudine compared to lamivudine in
patients with HBeAg-positive and HBeAg-negative compensated chronic hepatitis B
for two years of treatment in two daily treatment regimens: telbivudine 600 mg
or lamivudine 100 mg.

The one-year analysis of this trial will be the primary data used for preparing
the marketing registration applications. Idenix and Novartis plan to file with
the U.S. Food and Drug Administration (FDA) by the end of 2005 for marketing
approval of telbivudine for the treatment of chronic hepatitis B. Worldwide
marketing filings, including the filing that will be submitted to the European
Medicines Agency (EMEA), are expected in the first quarter of 2006. Idenix and
Novartis are co-developing telbivudine.

The World Health Organization (WHO) has estimated that approximately 350
million people, or 5% of the world's population, are chronically infected with
hepatitis B virus (HBV). Current treatment options are often associated with
limited efficacy, poor tolerability or resistance concerns, and new therapeutic
options are needed to respond to the significant unmet need in treating chronic
hepatitis B.

"We are very pleased that telbivudine met the primary endpoint in the phase III
GLOBE study and may provide an important new therapeutic option for patients
with chronic hepatitis B," commented Nathaniel Brown, M.D., executive vice
president of clinical development and chief medical officer of Idenix.
"Bringing our first clinical candidate through this stage of development is a
major milestone for Idenix, particularly given the large international scope of
the GLOBE study."

The companies anticipate that complete data from the GLOBE study will be
submitted for presentation to the American Association for the Study of Liver
Diseases (AASLD) meeting in San Francisco, California, November 11-15, 2005.

More About Telbivudine

Telbivudine is a specific and selective, oral, once-daily nucleoside that is
unique in its preferential inhibition of 2nd strand HBV DNA synthesis. This
distinct mechanism of action may be responsible for the rapid and profound
viral suppression associated with telbivudine treatment.

The GLOBE study results continue to support a favorable overall safety profile
for telbivudine with no substantial safety issues being identified to date
through the combined two years of treatment in the phase IIb clinical trial and
in the phase III clinical program to date. The most frequently reported adverse
events, regardless of attributability to study treatment, were upper
respiratory infection and fatigue, which were equally common for telbivudine
(14% and 12 %, respectively) and lamivudine (13% and 10% respectively).

An additional phase III trial is evaluating the safety and efficacy of
telbivudine compared to lamivudine in HBeAg-positive and HBeAg-negative
patients with decompensated chronic hepatitis B. This ongoing trial has
enrolled 87 patients to date.

About Hepatitis B

Chronic Hepatitis B is caused by a virus that attacks the liver. The virus,
which is called hepatitis B virus (HBV), can cause lifelong infection,
cirrhosis (scarring) of the liver, liver cancer, liver failure, and death. The
WHO estimates that annually over 50 million people become infected with HBV and
that more than one million individuals die from HBV-related chronic liver
disease.

Idenix/Novartis Collaboration

Idenix is developing its hepatitis B clinical product candidates, telbivudine
and valtorcitabine, in collaboration with Novartis Pharma AG under a
development and commercialization arrangement established in May 2003. The
collaboration arrangement further provides that Novartis and Idenix will co-
promote in the United States, France, Germany, Italy, Spain and the UK those
product candidates Novartis has licensed, including telbivudine and
valtorcitabine, that are approved for marketing. Novartis holds the exclusive
license to telbivudine and valtorcitabine in the rest of the world.

The collaboration also provides Novartis with an exclusive option to license
and collaborate with Idenix in the development and commercialization of other
product candidates in Idenix's portfolio, including valopicitabine (NM283), a
direct antiviral hepatitis C product candidate.

About Idenix

Idenix Pharmaceuticals, Inc. is a biopharmaceutical company engaged in the
discovery, development and commercialization 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. The company also 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
"will be," "plan to," "expected," "anticipates," or similar expressions, or by
express or implied discussions regarding the potential therapeutic benefits,
the potential development or the potential future sales of telbivudine. 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 telbivudine
will be approved for sale in any market, or that telbivudine will achieve any
particular level of sales. Any such commercialization can be affected by, among
other things, uncertainties relating to clinical trials; new clinical data with
respect to telbivudine, or additional analysis of existing clinical data;
uncertainties regarding the timing and success of submission, acceptance and
approval of regulatory filings; 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; government, industry, and general public pricing
pressures; the company's ability to obtain, maintain and enforce patent and
other intellectual property protection for telbivudine and its related
discoveries; as well as other factors discussed under the caption "Factors That
May Affect Future Results" in the company's quarterly report on Form 10-Q for
the quarter ended March 31, 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.

   Contact:
   Idenix Pharmaceuticals, Inc.
   Media: Teri Dahlman [phone]
   Investors: Amy Sullivan [phone]


DATASOURCE: Idenix Pharmaceuticals, Inc.



CONTACT:  Teri Dahlman, Media Contact, [phone], or Amy Sullivan,

Investors Contact, [phone], both Idenix Pharmaceuticals, Inc.



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

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