Press Release

Cellectis S.A. Announces an Agreement with Shire Pharmaceuticals in the field of gene activated proteins

Romainville, France - December the 20^th, 2005 - Cellectis S.A. announced today that they entered into an agreement with Shire Pharmaceuticals, by which Cellectis will grant Shire a worldwide non-exclusive commercial license relating to it site-directed genome engineering technologies for creating and developing genetically engineered cells to produce certain gene activated biopharmaceuticals. Financial terms and conditions of the agreement were not disclosed.

Isabelle Pelletier-Bressac, vice-president Business Development of Cellectis commented, "We are delighted to enter into this agreement with Shire, a leader in gene activation technology for enzyme replacement therapies."

Cellectis SA (www.cellectis.com) was founded in 2000, as a spin-off from the Institut Pasteur. Today, Cellectis is the world leader in applying the technology of Meganuclease Recombination Systems to in vivo genome engineering and genome surgery. The company is focused on the research and development of custom-made Meganucleases for in vivo DNA interventions and also provides new tools for rational reverse genetics and targeted recombination. Cellectis develops Meganucleases that can induce unique site-directed double-strand breaks in a living cell, and can be used for biotechnological and therapeutical applications. The company is focusing on bringing "genome surgery" to clinic as a genuine new molecular medicine approach.

As of today, Cellectis has entered into more than 40 deals on its Genome Engineering technologies.

Shire's strategic goal is to become the leading specialty pharmaceutical company that focuses on meeting the needs of the specialist physician. Shire focuses its business on central nervous system, gastrointestinal, general products and human genetic therapies - all being areas in which Shire has a commercial presence. The structure is sufficiently flexible to allow Shire to target new therapeutic areas to the extent opportunities arise through acquisitions. Shire believes that a carefully selected portfolio of products with strategically aligned and relatively small-scale sales forces will deliver strong results. Shire's strategy is to develop and market products for specialty physicians. Shire's in-licensing and merger and acquisition efforts are focused on products in niche markets with strong intellectual property protection either in the US or Europe.

For further information on Shire, please visit the Company's website: www.shire.com.

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