SHAREHOLDER ALERT: Pomerantz Law Firm Has Filed a Class Action Against Achillion Pharmaceutical, Inc. and Certain Officers -- ACHN

November 8, 2013

NEW YORK, NY--(Marketwired - Nov 8, 2013) - Pomerantz Grossman Hufford Dahlstrom & Gross LLP has filed a class action lawsuit against Achillion Pharmaceuticals, Inc. ("Achillion" or the "Company") ( NASDAQ : ACHN ) and certain of its officers. The class action, filed in United States District Court, District of Connecticut, and docketed under 13-cv-1479, is on behalf of a class consisting of all persons or entities who purchased or otherwise acquired securities of Achillion between April 21, 2012 and September 27, 2013 both dates inclusive (the "Class Period"). This class action seeks to recover damages against the Company and certain of its officers and directors as a result of alleged violations of the federal securities laws pursuant to Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder.

If you are a shareholder who purchased Achillion securities during the Class Period, you have until December 7, 2013 to ask the Court to appoint you as Lead Plaintiff for the class. A copy of the Complaint can be obtained at www.pomerantzlaw.com. To discuss this action, contact Robert S. Willoughby at rswilloughby@pomlaw.com or 888.476.6529 (or 888.4-POMLAW), toll free, x237. Those who inquire by e-mail are encouraged to include their mailing address, telephone number, and number of shares purchased.

Achillion is a biopharmaceutical company that discovers and develops solutions for infectious diseases such as HIV, hepatitis, and resistant bacterial infections. The Company focuses its research and development on products for the antiviral and antibacterial markets.

The Complaint alleges that throughout the Class Period, Defendants made false and/or misleading statements, as well as failed to disclose material adverse facts about the Company's business, operations, and prospects, including the safety and suitability of its premier investigative drug for the treatment of hepatitis, sovaprevir. Defendants failed to inform investors that sovaprevir in fact did not interact well with other drugs commonly administered to treat hepatitis and/or HIV. Specifically, the Company misled investors to believe that even though patients in the Company's clinical trials for sovaprevir had elevations in liver enzymes, that these liver enzymes elevations were transient and returned to baseline values and were attributable to non-drug-related factors. As a result of the foregoing, the Company's statements were materially false and misleading at all relevant times.

On July 1, 2013, the Company disclosed that the FDA instituted a clinical hold on "sovaprevir after elevations in liver enzymes associated with significantly higher than anticipated exposures to atazanavir and sovaprevir were noted in a Phase I healthy subject drug-drug interaction study evaluating the effects of concomitant administration of sovaprevir with ritonavir-boosted atazanavir." As a result of this disclosure, Achillion shares declined $2.10 per share or over 25%, to close at $6.26 per share on July 2, 2013.

On September 27, 2013, after the market closed, the Company disclosed that the FDA had continued its clinical hold on sovaprevir, after, "the FDA concluded that the removal of the clinical hold is not warranted." As a result of this disclosure, Achillion shares declined $4.22 per share or over 58%, to close at $3.02 per share on September 30, 2013.

The Pomerantz Firm, with offices in New York, Chicago, Florida, and San Diego, is acknowledged as one of the premier firms in the areas of corporate, securities, and antitrust class litigation. Founded by the late Abraham L. Pomerantz, known as the dean of the class action bar, the Pomerantz Firm pioneered the field of securities class actions. Today, more than 70 years later, the Pomerantz Firm continues in the tradition he established, fighting for the rights of the victims of securities fraud, breaches of fiduciary duty, and corporate misconduct. The Firm has recovered numerous multimillion-dollar damages awards on behalf of class members. See www.pomerantzlaw.com.