PRESS RELEASE

Cellectis to Present Data on its Allogeneic CAR T-Cell Immunotherapy Programs at the European Hematology Association Annual Meeting

June 4, 2015 – New York (USA) – Cellectis (Alternext: ALCLS – Nasdaq Global Market: CLLS), the gene-editing company employing proprietary technologies to develop best-inclass CAR T-cell products in adoptive immunotherapy for cancer, today announced that preclinical data on its engineered allogeneic CAR T-cells will be featured in two oral presentations and one poster presentation at the European Hematology Association (EHA) Annual Meeting. The meeting will be held from June 11th to 14th, 2015, in Vienna, Austria.

The selected presentations are as follow:

Allogeneic adoptive immunotherapy of acute myeloid leukemia (ALM) by targeting CD123 with CAR T-Cells Oral Presentation Session Title: Gene therapy, cellular immunotherapy & vaccination Presentation Time: Saturday, June 13th, 2015, 12:15pm to 12:30pm
UCART19, an Allogeneic "Off-the-Shelf" Adoptive T-Cell Immunotherapy Against CD19+ B-Cell Leukemias Oral Presentation Session Title: Gene therapy, cellular immunotherapy & vaccination

Presentation Time: Saturday, June 13th, 2015, 12:30pm to 12:45pm

• Adoptive immunotherapy of multiple myeloma (MM) with allogeneic CAR T-Cells targeting CS1: enhancement of CAR activity through CS1 gene inactivation in effector cells Poster Presentation

Session Title: Gene therapy, cellular immunotherapy & vaccination Presentation Time: Saturday, June 13th, 2015, 5:15pm to 6:45pm

About Cellectis

Cellectis is a preclinical stage 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 Cellectis Group.

For further information, please contact:

Media contacts

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

BMC Communications

Brad Miles Phone: 646-513-3125 email: [email protected]

IR contacts

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

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