Idenix Pharmaceuticals Presents Data on IDX184 for the Treatment of Hepatitis C Virus (HCV)

Idenix Pharmaceuticals Presents Data on IDX184 for the Treatment of Hepatitis
C Virus (HCV)

CAMBRIDGE, Mass., Oct. 30 /PRNewswire-FirstCall/ -- Idenix Pharmaceuticals,
Inc. (Nasdaq: IDIX), a biopharmaceutical company engaged in the discovery and
development of drugs for the treatment of human viral diseases, today
announced presentations of data on IDX184, a once-daily novel liver-targeted
nucleotide prodrug of 2'-methyl guanosine (2'MeG) for the treatment of HCV, at
the annual meeting of the American Association for the Study of Liver Diseases
(AASLD) currently being held in Boston, Massachusetts.

Data from a three-day, phase I proof-of-concept study evaluating the safety
and antiviral activity of IDX184 will be presented. This double-blind,
placebo-controlled, monotherapy, dose-escalation study enrolled 41
treatment-naive HCV genotype 1-infected patients into four dosing cohorts (25
mg, 50 mg, 75 mg and 100 mg). IDX184 was well tolerated in this study with no
serious adverse events reported and no discontinuations from the study.
Patterns of adverse events (AEs) were similar between IDX184- and
placebo-treated patients with the most frequent AEs being headache, diarrhea
and dizziness. Mean viral load declines ranged from 0.47 log10 in the 25 mg
group to 0.74 log10 in the 100 mg group after three days of treatment. In the
75 and 100 mg/day cohorts, patients receiving IDX184 experienced improvements
in two key markers of liver injury (AST and ALT), with mean levels of these
enzymes decreasing to within normal range. Pharmacokinetic data demonstrated
that higher plasma levels of 2'MeG were associated with greater reductions in
viral load and ALT levels.

"With favorable safety data and good antiviral activity for IDX184 in HCV
patients, these early results are encouraging," said Dr. Jacob Lalezari,
principal investigator in the study, Director of Quest Clinical Research and
an Assistant Clinical Professor of Medicine at UCSF/Mount Zion Hospital.
"Nucleotides may become an essential component of future STAT-C combinations
for the treatment of hepatitis C. IDX184 has shown a promising early profile
and should be evaluated in longer-term, combination trials."

Results will also be presented from in vitro studies evaluating the
combination of IDX184 with other direct-acting antivirals or standard-of-care
agents, interferon and ribavirin. These in vitro studies suggest that when
IDX184 is combined with compounds from different classes, the antiviral
activity may be enhanced, and in some combinations, synergistic. Specifically,
the triple combination of IDX184, interferon and ribavirin showed strong
synergy in vitro. These in vitro studies also suggest that the combination of
IDX184 with other compounds from different classes may suppress the emergence
of resistance.

"The in vitro combination data for IDX184 are promising," said David
Standring, executive vice president of biology for Idenix. "We look forward
to assessing this potential synergy in the next clinical study evaluating
IDX184 in combination with pegylated interferon and ribavirin in HCV genotype
1-infected patients."

About IDX184
IDX184 is a novel, liver-targeted nucleotide prodrug of 2'-methyl guanosine,
which includes Idenix's proprietary liver-targeting technology. This
technology enables the delivery of nucleoside monophosphate to the liver,
leading to the formation of high levels of nucleoside triphosphate,
potentially maximizing drug efficacy and limiting systemic side effects with
low, once-daily dosing.

About Idenix
Idenix Pharmaceuticals, Inc., headquartered in Cambridge, Massachusetts, is a
biopharmaceutical company engaged in the discovery and development of drugs
for the treatment of human viral diseases. Idenix's current focus is on the
treatment of infections caused by hepatitis C virus. For further information
about Idenix, please refer to 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
"expect," "plans," "anticipates," "will," "expects," "goal" or similar
expressions, or by express or implied statements with respect to the company's
clinical development programs or commercialization activities in hepatitis C,
or any potential pipeline candidates, including any expressed or implied
statements regarding the efficacy and safety of IDX184, the likelihood and
success of any future clinical trials involving IDX184 or successful
development of novel combinations of direct-acting antivirals for the
treatment of hepatitis C. Such forward-looking statements involve known and
unknown risks, uncertainties and other factors that may cause actual results
to be materially different from any future results, performance or
achievements expressed or implied by such statements. There can be no
guarantees that the company will advance any clinical product candidate or
other component of its potential pipeline to the clinic, to the regulatory
process or to commercialization. In particular, management's expectations
could be affected by unexpected regulatory actions or delays; uncertainties
relating to, or unsuccessful results of, clinical trials, including additional
data relating to the ongoing clinical trials evaluating its product
candidates; the company's ability to obtain additional funding required to
conduct its research, development and commercialization activities; changes in
the company's business plan or objectives; 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 its product candidates and its
discoveries. These and other risks which may impact management's expectations
are described in greater detail under the caption "Risk Factors" in the
company's annual report on Form 10-K for the year ended December 31, 2008 and
the Quarterly Report on Form 10-Q for the quarter ended September 30, 2009, as
filed with the Securities and Exchange Commission (SEC) and other filings that
the company makes with the SEC.

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

SOURCE Idenix Pharmaceuticals, Inc.

Teri Dahlman of Idenix Pharmaceuticals, +1-617-995-9905