Item 1.01. Entry Into a Material Definitive Agreement

License Agreement

On April 4, 2008, Achillion Pharmaceuticals, Inc. ("Achillion" or the "Company") entered into a license and research agreement with FOB Synthesis, Inc. ("FOB") granting Achillion an exclusive worldwide license for the research, development and commercialization of certain FOB compounds for the treatment of serious bacterial infections.

Under the terms of the agreement, Achillion will pay to FOB a $500,000 upfront license payment. FOB could also receive an additional $500,000 license payment and earn milestone payments of up to $9.5 million per product candidate based upon the achievement of certain specified development and regulatory goals. Achillion will provide FOB with funding at specified levels to collaborate with Achillion on the further characterization and development of the compounds for at least the next year. Achillion has the option to extend the research term for an additional one year period with 30 days written notice to FOB prior to the end of the first year of the research term. Achillion will pay FOB a royalty on net sales of certain future products arising from the collaboration.

The agreement may be terminated by either party based upon material uncured breaches by the other party, or, subject to continued payment by Achillion of collaboration funding for the remainder of the current research term, by Achillion at any time after providing sixty (60) days advance written notice of termination.

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