PARIS–Cellectis S.A. (Paris:ALCLS), the French genome engineering specialist, has announced that the European Patent Office has today upheld European Patent EP 1 485 475 owned by Cellectis and relating to the invention of engineering methods for meganucleases. This method is based on the genetic fusion of meganuclease modules to obtain hybrid meganucleases. In the course of this opposition, the patent underwent a limitation of claims and Cellectis considers appealing this decision. This patent not only broadens the range of genetic targets for the meganucleases but also improves their production and vectorization.

This outcome illustrates the importance of the cutting edge technology developed by Cellectis and protects the integrity of Cellectis’ intellectual property.

Cellectis CEO André Choulika said, “This decision makes us even more determined in our constant fight to defend our intellectual property rights. Intellectual property is a key value of biotechnology companies and is the launch pad for their growth. Our position means that we are able to invest 80% of our income in very high added value research and development projects.”

To date, Cellectis holds a portfolio of 42 granted patents and more than 130 applications for additional patents pending.

About Cellectis S.A.

Cellectis S.A. is a world leader in genome engineering and genome surgery. The company focuses on developing and producing custom meganucleases for use in in vivo genome surgery addressing the therapeutic, agrofood, biomanufacturing and research sectors. Worldwide, Cellectis has entered into more than 50 agreements with major players in the pharma, biotech and agrobiotech industries and has over 20 collaborations with academic research groups. To date, Cellectis has raised over €70 million in both equity operations and public financing and is listed on the NYSE-Euronext Alternext market (ticker code: ALCLS). For more information on Cellectis, visit our website: www.cellectis.com

Disclaimer

This press release and the information contained herein do not constitute an offer to sell or subscribe, or a solicitation of an offer to buy or subscribe, shares in Cellectis in any country. This press release contains forward-looking statements that relate to the Company’s objectives. Such forward-looking statements are based on the current expectations and assumptions of the Company’s management only and involve risk and uncertainties. Potential risks and uncertainties include, without limitation, whether the Company will be successful in implementing its strategies, whether there will be continued growth in the relevant market and demand for the Company’s products, new products or technological developments introduced by competitors, and risks associated with managing growth. Unfavorable developments in connection with these and other risks and uncertainties described, in particular, in the Company’s prospectus prepared in connection with its IPO and on which the French Autorité des marchés financiers (“AMF”) granted its visa n° 07-023 on January 22, 2007, could cause the Company to fail to achieve the objectives expressed by the forward-looking statements above.