Achillion Nominates ACH-3422 as Nucleotide for the Treatment of Chronic HCV

Achillion Nominates ACH-3422 as Nucleotide for the Treatment of Chronic HCV

– Advancement of ACH-3422 Complements Achillion's Portfolio of 2^nd Generation
 Protease and NS5A Inhibitors Providing the Opportunity to Optimize Treatment
                 Duration and Outcomes for All HCV Patients –

      – Conference Call and Webcast to be Hosted Today at 12:00pm EDT –

NEW HAVEN, Conn., May 30, 2013 (GLOBE NEWSWIRE) -- Achillion Pharmaceuticals,
Inc. (Nasdaq:ACHN) today announced the nomination of the preclinical compound,
ACH-3422, a novel small molecule nucleotide prodrug of a uridine analog
designed to inhibit HCV NS5B polymerase. This compound will be advanced as a
development candidate for the treatment of chronic hepatitis C (HCV) viral
infection. Achillion plans to complete regulatory submissions during the first
quarter of 2014, with first-in-human studies anticipated in the first half of
2014, followed by combination development in the second half of 2014.

"Our research and discovery team has always maintained the highest standards
for developing proprietary best-in-class compounds, and this has led to the
nomination of ACH-3422, which we are now advancing toward the clinic,"
commented Milind Deshpande, Ph.D., President and Chief Executive Officer. "The
addition of ACH-3422 gives Achillion a portfolio of assets that also includes
a 2^nd generation protease inhibitor, sovaprevir, and a 2^nd generation NS5A
inhibitor, ACH-3102, which together provide Achillion the opportunity to
potentially optimize treatment outcomes and duration of therapy across all HCV
patients."

Dr. Deshpande further commented, "Along with the nomination of this candidate,
we continue our efforts to accelerate the development time-lines for our
all-oral, interferon-free combination of sovaprevir and ACH-3102, our protease
and NS5A inhibitors, as a regimen for the treatment of HCV. Beginning in the
third quarter of 2013, we expect to begin to report interim results from the
ongoing -007 clinical trial of these agents for the treatment of HCV genotype
1 treatment-naïve patients."

Preclinical profile of 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 IND-enabling studies have been initiated,
with the expectation of submitting an IND to the FDA in the first quarter of
2014.

Conference Call

The Company will host a conference call and simultaneous webcast on Thursday,
May 30, 2013 at 12:00 p.m. Eastern time. To participate in the conference
call, please dial (877) 266-0482 in the U.S. or (631) 291-4567 for
international callers. A live audio webcast of the call will be accessible at
www.achillion.com, under the News Center section of the website. Please
connect to Achillion's website several minutes prior to the start of the
broadcast to ensure adequate time for any software download that may be
necessary.

A replay of the webcast will be available on www.achillion.com. Alternatively,
a replay of the conference call will be available starting at 9:00 p.m.
Eastern time on May 28, 2013, through 11:59 p.m. Eastern time on June 5, 2013
by dialing (855) 859-2056 or (404) 537-3406. The replay passcode is 87685598.

About HCV

The hepatitis C virus is the most common cause of viral hepatitis, which is an
inflammation of the liver. It is currently estimated that more than 170
million people are infected with HCV worldwide including more than 5 million
people in the United States, making HCV more than twice as widespread as HIV.
Three-fourths of the global HCV patient population is undiagnosed; it is a
silent epidemic and a major global health threat. Chronic hepatitis, if left
untreated, can lead to permanent liver damage that can result in the
development of liver cancer, liver failure or death. Few therapeutic options
currently exist for the treatment of HCV infection. The current standard of
care is limited by its specificity for certain types of HCV, significant
side-effect profile, and injectable route of administration.

For additional information on Achillion's ongoing clinical trial please visit:
http://clinicaltrials.gov

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.

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 expected potency,
bioavailability, pharmacokinetic and other characteristics of development
candidate ACH-3422; Achillion's expectations regarding timing for the
commencement, completion and reporting of results of its clinical trials of
ACH-3422, ACH-3102 in combination with ribavirin and sovaprevir in combination
with ACH-3102. 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: successfully advance ACH-3422 into
clinical trials; replicate in later clinical trials positive results found in
preclinical and earlier stage clinical trials of sovaprevir, ACH-3102,
ACH-3422 and its other product candidates; advance the development of its drug
candidates under the timelines it anticipates in current and future clinical
trials; obtain necessary regulatory approvals; obtain 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; and raise the substantial
additional capital needed to achieve its business objectives. These and other
risks are described in the reports filed by Achillion with the U.S. Securities
and Exchange Commission, including its Annual Report on Form 10-K for the
fiscal year ended December 31, 2012 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
        
         Investors:
         Mary Kay Fenton
         Achillion Pharmaceuticals, Inc.
         Tel. (203) 624-7000
         mfenton@achillion.com
        
         Media:
         Sally Barton
         Ogilvy PR
         Tel. (212) 880-5240
         sally.barton@ogilvy.com
        
         Investors:
         Seth Lewis
         The Trout Group, LLC
         Tel. (646) 378-2952
         slewis@troutgroup.com

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