Press Release

Cellectis signs Worldwide Non-Exclusive License agreement with AstraZeneca covering the use of the Homologous Recombination

Romainville, France December 13^th, 2005 Cellectis SA, the rational genome engineering company and specialist in DNA recombination, announced today that the company has granted AstraZeneca, a worldwide and non-exclusive license under the patent family relating to a process for the specific replacement or insertion of a gene in the receiver genome by homologous recombination.

Through this license agreement, Cellectis grants AstraZeneca the right to use its patented technologies for in vitro and in vivo modifications and manipulations of the genetic material of rodents. Financial terms and conditions of the agreement were not disclosed.

Isabelle Pelletier-Bressac, Vice President Business Development of Cellectis commented "We are delighted to have granted a license to AstraZeneca, who can use the patented technology in their pharmaceutical research and development programs to develop in vivo models using gene addition and gene modification techniques."

Homologous recombination, which relies on natural cellular DNA maintenance and repair mechanisms present in all living organisms, is the technological basis of rational genome engineering, Cellectis' expertise. This robust technology has been widely used and has proven its power for over a decade. Today, it is a world scientific standard for elucidating gene function. Among other applications, homologous recombination is systematically used for gene "knock-outs" and "knock-ins".

About AstraZeneca:

AstraZeneca is a major international healthcare business engaged in the research, development, manufacture and marketing of prescription pharmaceuticals and the supply of healthcare services. It is one of the world's leading pharmaceutical companies with healthcare sales of over $21.4 billion and leading positions in sales of gastrointestinal, cardiovascular, respiratory, oncology and neuroscience products. AstraZeneca is listed in the Dow Jones Sustainability Index (Global) as well as the FTSE4Good Index.

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 35 deals on its Genome Engineering technologies.

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