Achillion's Uridine-Analog Nucleotide Prodrug, ACH-3422, Shows Compelling Preclinical Profile

Achillion's Uridine-Analog Nucleotide Prodrug, ACH-3422, Shows Compelling
Preclinical Profile

New Preclinical Data Being Presented at The Liver Meeting 2013

NEW HAVEN, Conn., Nov. 2, 2013 (GLOBE NEWSWIRE) -- Achillion Pharmaceuticals,
Inc. (Nasdaq:ACHN) today announced a poster presentation detailing the
preclinical profile of ACH-3422, a uridine-analog nucleotide prodrug being
advanced for the potential treatment of chronic hepatitis C viral infection
(HCV). The poster is beingpresented at the 64^th Annual Meeting of the
American Association for the Study of Liver Diseases (The Liver Meeting 2013)
in Washington D.C.

The poster presentation, entitled, "Preclinical Characteristics of ACH-3422: A
Potent Uridine Nucleotide Prodrug for Inhibition of Hepatitis C Virus NS5B RNA
Polymerase," (Poster 475; HCV Therapy: The Developmental Pipeline. Saturday,
November 2, 2013: 2:00 PM – 7:30 PM ET. Poster Hall), details the potent and
specific inhibition of HCV NS5B polymerase by ACH-3422, and the demonstrated
low risk for mitochondrial toxicity based upon in vitro studies with human
cells in static and proliferating conditions, and high efficiency in the
conversion of ACH-3422 into the triphosphate within human hepatocyte cell
lines. These attributes, combined with the previously reported 14-day animal
toxicity study of ACH-3422, continue to support the advancement of this
compound toward clinical studies for use in combination with other direct
acting antiviral agents for the potential pan-genotypic treatment of chronic
HCV.

"These data provide additional insight into the compelling profile of ACH-3422
as a potential NS5B nucleotide inhibitor for the broad treatment of HCV. Based
upon our current development timelines, we anticipate initiating our
first-in-human and proof-of-concept trials with ACH-3422 during the first half
of 2014," commented Milind Deshpande, Ph.D., President and Chief Executive
Officer of Achillion. "We believe that the ability to potentially combine a
potent nucleotide, such as ACH-3422, with our other proprietary assets,
including our differentiated Phase 2 NS5A inhibitor, ACH-3102, and our Phase 2
protease inhibitors, including ACH-2684, provides extensive optionality for
developing a simple and effective all-oral treatment regimen aimed at curing
HCV across broad treatment populations."

A reprint of the poster presentation can be accessed from the Resources
section of our website at http://www.achillion.com.

About ACH-3422

ACH-3422 is a small-molecule, nucleotide prodrug inhibitor of HCV NS5B
polymerase. In vitro, ACH-3422 has demonstrated excellent potency, with
activity demonstrated across all genotypes of HCV and an EC[50] of
approximately 50 to 65 nanomolar against genotype 1 HCV. To date, Achillion
has completed 14-day safety studies in animals, where no significant findings
were noted at the highest dose tested. ACH-3422 appears to have high oral
bioavailability, rapid uptake and conversion of the prodrug into the
monophosphate within the liver, and a pharmacokinetic profile supportive of
once-daily dosing. Manufacturing and preclinical studies to support clinical
development have been initiated, with the expectation of beginning
first-in-human studies during the first half of 2014.

About Achillion Pharmaceuticals

Achillion is an innovative pharmaceutical company dedicated to bringing
important new treatments to patients with infectious disease. Achillion's
discovery, clinical development, and commercial teams have advanced multiple
novel product candidates with proven mechanisms of action into studies and
toward the market. Achillion is focused on solutions for the most challenging
problems in infectious disease including HCV and resistant bacterial
infections. For more information on Achillion Pharmaceuticals, please visit
www.achillion.com or call 1-203-624-7000.

Cautionary Note Regarding Forward-Looking Statements

This press release includes forward-looking statements within the meaning of
the Private Securities Litigation Reform Act of 1995 that are subject to
risks, uncertainties and other important factors that could cause actual
results to differ materially from those indicated by such forward-looking
statements, including statements with respect to: the potential favorable
potency, safety, efficacy and other attributes of ACH-3422 and its potential
benefits when used in combination with other direct acting antiviral agents to
treat HCV; and the Company's plans and timing for progressing ACHN-3422 into
clinical development. We may use words such as "expect," "anticipate,"
"project," "intend," "plan," "believe," "seek," " estimate," and "may" and
similar expressions to identify such forward-looking statements. Among the
important factors that could cause actual results to differ materially from
those indicated by such forward-looking statements are risks relating to,
among other things Achillion's ability to: demonstrate in any potential future
clinical trials the requisite safety, efficacy and combinability of ACH-3422;
advance the preclinical and clinical development ACH-3422 and its other drug
candidates, including ACH-3102, and ACH-2684, under the timelines it projects
in current and future clinical trials; satisfactorily respond to the clinical
hold placed on sovaprevir by the FDA; obtain and maintain necessary regulatory
approvals; obtain and maintain patent protection for its drug candidates and
the freedom to operate under third party intellectual property; establish
commercial manufacturing arrangements; identify, enter into and maintain
collaboration agreements with appropriate third-parties; compete successfully
with other companies that are seeking to develop improved therapies for the
treatment of HCV; manage expenses; manage litigation; raise the substantial
additional capital needed to achieve its business objectives; and successfully
execute on its business strategies. These and other risks are described in the
reports filed by Achillion with the U.S. Securities and Exchange Commission,
including its Quarterly Report on Form 10-Q for the fiscal quarter ended June
30, 2013 and its subsequent SEC filings.

In addition, any forward-looking statement in this press release represents
Achillion's views only as of the date of this press release and should not be
relied upon as representing its views as of any subsequent date. Achillion
disclaims any duty to update any forward-looking statement, except as required
by applicable law.

CONTACT: Company Contact:
         Glenn Schulman
         Achillion Pharmaceuticals, Inc.
         Tel. (203) 624-7000
         gschulman@achillion.com
        
         Media:
         Carol Ready
         Ogilvy PR
         Tel. (212) 880-5211
         carol.ready@ogilvy.com
        
         Investors:
         Mary Kay Fenton
         Achillion Pharmaceuticals, Inc.
         Tel. (203) 624-7000
         mfenton@achillion.com
        
         Investors:
         Seth Lewis
         The Trout Group, LLC
         Tel. (646) 378-2952
         slewis@troutgroup.com

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