Cellectis — Capital/Financing Update 2015

Jan 8, 2015

PRESS RELEASE

Cellectis Plans to Conduct Registered Initial Public Offering in the U.S.

Paris, January 8 - Cellectis SA (Alternext: ALCLS.PA) announced today that it plans to conduct a registered initial public offering in the United States. The timing, number of shares and price of the proposed offering have not yet been determined.

This announcement is being made pursuant to and in accordance with Rule 135 under the Securities Act of 1933. As required by Rule 135, this press release does not constitute an offer to sell or the solicitation of an offer to buy securities, and shall not constitute an offer, solicitation or sale in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of that jurisdiction.

For further information, please contact:

Cellectis Jennifer Moore Tel.: +33 (0)1 81 69 16 00 Email: media@cellectis.com

About Cellectis

Cellectis is a gene-editing company focused on developing immunotherapies based on gene edited engineered CAR-T cells (UCART). The company's mission is to develop a new generation of cancer therapies based on engineered T-cells. Cellectis capitalizes on its 15 years of expertise in genome engineering - based on its flagship TALEN™ products and meganucleases and pioneering electroporation PulseAgile technology - to create a new generation of immunotherapies. CAR technologies are designed to target surface antigens expressed on cells. Using its life-science-focused, pioneering genome-engineering technologies, Cellectis' goal is to create innovative products in multiple fields and with various target markets. Cellectis is listed on the NYSE Alternext market (ticker: ALCLS). To find out more about us, visit our website: www.cellectis.com