Cellectis

Report Publication Announcement • Apr 10, 2015

PRESS RELEASE

Cellectis Announces Presentations at Upcoming Conferences

April 9, 2015 – New York (USA) Cellectis S.A. (Alternext: ALCLS – Nasdaq Global Market: CLLS) a pioneering gene-editing company employing proprietary technologies to develop best-in-class products in the emerging field of immunooncology, today announced that Cellectis will be present at the following upcoming conferences:

Cancer Advance Boston

Date: Tuesday, April 14, 2015; presentation time: 1:50PM ET Venue: Joseph B. Martin Conference Center at Harvard Medical School, Boston, Massachusetts

Jefferies Immuno-Oncology Summit

Date: Wednesday, April 15, 2015; presentation time: 11:10AM ET Venue: Boston Harbor Hotel, Boston, Massachusetts

AACR Annual Meeting

Date: Saturday-Wednesday, April 18-22, 2015 Venue: Pennsylvania Convention Center, Philadelphia, Pennsylvania

Bank of America Merrill Lynch 2015 Global Health Care Conference

Date: Tuesday-Thursday, May 12-14, 2015 Venue: Encore at the Wynn, Las Vegas, Nevada

BioEquity Europe

Date: Tuesday-Wednesday, May 19-20, 2015 Venue: Hotel InterContinental, Vienna, Austria

Piper Jaffray GenomeRx Symposium

Date: Wednesday-Thursday, May 20-21, 2015 Venue: The Yale Club, New York, New York

ASCO Annual Meeting

Date: Friday-Tuesday, May 29-June 2, 2015 Venue: McCormick Place, Chicago, Illinois

Jefferies 2015 Healthcare Conference

Date: Monday-Thursday, June 1-4, 2015 Venue: Grand Hyatt, New York City, New York

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 genomeengineering 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

For further information, please contact:

Cellectis

Simon Harnest, VP Finance and Investor Relations Phone: +1 646 385-9008 email: simon.harnest@cellectis.com

Jennifer Moore, Director of Communications Phone: +1 917 580-1088 email: media@cellectis.com