ACHN 2018 Proxy Statement

Laboratories, Mr. Van Nostrand served as Executive Vice President and Chief Financial Officer of AGI Dermatics, a private biotechnology company, from July 2007 to September 2008 when the company was acquired. From May 2005 to July 2007, Mr. Van Nostrand served as the Senior Vice President and Chief Compliance Officer of OSI Pharmaceuticals, Inc., or OSI, a biotechnology company, where he previously served as Vice President and Chief Financial Officer from December 1996 through May 2005 and as Vice President, Finance and Administration prior to that. He also served as OSI’s Treasurer from March 1992 to May 2005 and as Secretary from March 1995 to January 2004. Mr. Van Nostrand joined OSI as Controller and Chief Accounting Officer in September 1986. Prior to joining OSI, Mr. Van Nostrand served in a managerial position with the accounting firm, Touche Ross & Co., currently Deloitte. Mr. Van Nostrand is also on the Board of the New York Biotechnology Association and was the former chairman and is on the Foundation Board of Farmingdale University. Mr. Van Nostrand holds a B.S. in Accounting from Long Island University, New York and completed advanced management studies at the Wharton School of the University of Pennsylvania. He is a Certified Public Accountant. Board Committees: Audit (Chair); Compliance Skills and Qualifications: Our Board of Directors believes that Mr. Van Nostrand’s vast board and industry experience in life sciences, his qualification as a financial expert, as well as his experience in transaction structuring and risk management qualifies him to serve on the Board of Directors and make him a significant contributor to our Board of Directors. Nicole Vitullo, age 60. Ms. Vitullo has served as a director of Achillion since September 2010. Ms. Vitullo joined Domain Associates, a venture capital firm with an exclusive focus on life sciences, in 1999 and became a Partner in 2004. In addition to her investment responsibilities, she is involved in the distribution/liquidation strategies for the public companies in Domain’s Venture Capital portfolios. Ms. Vitullo is on the Board of Directors of Celtaxsys, Inc., (since June 2015) a privately-held life sciences company and serves on the Boards of Directors of Esperion Pharmaceuticals, Inc. (since April 2008) and Marinus Pharmaceuticals, Inc., (since September 2005) both publicly traded pharmaceutical companies. Ms. Vitullo previously served on the Board of Directors of Celator, Inc. (from April 2005 until July 2016) which was acquired by Jazz Pharmaceuticals plc in May 2016, and Durata Therapeutics, Inc., (from December 2009 until November 2014) which was sold to Actavis Plc in November 2014. From 1992 through 1999, Ms. Vitullo was Senior Vice President at Rothschild Asset Management, Inc. where she had responsibility for the U.S. public market investments of International Biotechnology Trust plc and Biotechnology Investments Limited. From 1991 to 1992, Ms. Vitullo served as the Director of Corporate Communications and Investor Relations at Cephalon, a publicly traded biotechnology company. Prior to Cephalon, Ms. Vitullo spent 12 years at Eastman Kodak, most recently in Corporate Development where she was involved in the development and management of Eastman Kodak’s venture capital activities. Ms. Vitullo received a B.A. and M.B.A. from the University of Rochester. Board Committees: Nominating and Corporate Governance; Compliance Skills and Qualifications: Our Board of Directors believes that Ms. Vitullo’s extensive industry knowledge and investment experience is valuable in assisting the company in matters such as strategic planning, financing, alliance formation, product development and public market communications and qualifies her to serve on the Board of Directors. Ms. Vitullo’s extensive board membership with other companies provides her with very broad experience across several therapeutic areas in the life sciences industry, and makes her a valuable contributor to our Board of Directors. Board Recommendation The Board of Directors believes that the election of Drs. Deshpande and Fisherman to serve as Class III directors is in the best interests of Achillion and the best interests of our stockholders and, therefore, recommends a vote FOR this proposal. 13