PRESS RELEASE

Cellectis to Present Data on its CAR T-Cell Immunotherapy Programs During Upcoming Conferences

New York, August 26, 2015 – Cellectis (Alternext: ALCLS – Nasdaq Global Market: CLLS), a pioneering gene-editing company employing proprietary technologies to develop best-inclass products in the emerging field of immuno-oncology, today announced that pre-clinical data on its engineered allogeneic CAR T-cells will be featured during several conferences in the coming weeks.

The Immunotherapy and Vaccine Summit

August 24th to 28th, 2015, Boston, USA

André Choulika, Ph.D., Chairman and CEO of Cellectis, will be presenting in the panel "Advantages and Disadvantages of Different Gene Editing Technologies" on Thursday, August 27th at 11:45AM.
Dr Choulika will also give a presentation entitled "Allogeneic Universal CAR-T Cells Engineered With TALEN®" during the session "Merging Gene Editing and Immunotherapy" on Thursday, August 27th at 3:05PM.
Julien Valton, Ph.D., Senior Scientist at Cellectis, will give a presentation entitled "A Multidrug Resistant Engineered CAR T-Cell for Allogeneic Combination Immunotherapy" during the session "Chimeric Antigen Receptors" on Thursday, August 27th at 11:15AM.

CRI-CIMT-EATI-AACR Immunotherapy Conference

September 16th to 19th, 2015, New York, USA

Laurent Poirot, Head of Early Discovery at Cellectis, to present a poster entitled "Targeted genome modifications for Improved Adoptive Immunotherapy" on Wednesday, September 16.
Philippe Duchateau, Chief Scientific Officer at Cellectis, to present a poster entitled "Design of a chimeric antigen receptor (CAR) with controllable function via small molecule" on Friday, September 18.
Julianne Smith, VP CAR T Development at Cellectis, to present a poster entitled "Allogeneic CAR T-cells for Adoptive Immunotherapy" on Friday, September 18.

Phacilitate Cell & Gene Therapy

September 29th to 30th, 2015, Barcelona, Spain

• Stéphan Reynier, Chief Regulatory and Compliance Officer at Cellectis, to present as a chairperson during the session: "What is the most realistic, practicable supply chain solution for this particular class of products in Europe? What would be most feasible for rare vs. common indications?" This roundtable discussion will take place on Wednesday, September 30th, from 4:20 to 5:30PM.

About Cellectis

Cellectis is a biopharmaceutical 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 S.A. is listed on the Nasdaq Global Market (ticker: CLLS) and on the NYSE Alternext market (ticker: ALCLS). To find out more about us, visit our website: www.cellectis.com

TALEN® is a registered trademark owned by the Cellectis Group.

For further information, please contact:

Media contacts

Jennifer Moore, VP Communications Phone: 917-580-1088 email: [email protected]

Caitlin Kasunich / Dixon Moretz KCSA Strategic Communications 212.896.1241 / 212.896.1251 [email protected] / [email protected]

For investor relations (IR) matters:

Simon Harnest, VP Finance and Investor Relations Phone: 646-385-9008 email: [email protected]

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