Cellectis

Investor Presentation • Nov 24, 2014

PRESS RELEASE

Cellectis Announces Upcoming Presentations at the 56th Annual Meeting of the American Society of Hematology (ASH)

Paris, November 24, 2014 - Cellectis SA (Alternext: ALCLS.PA), a biopharmaceutical company focused on developing immunotherapies based on gene edited engineered CART-cells (UCART), today announced that three abstracts on the Company's CARTcell development programs were accepted for presentation at the 56th Annual Meeting and Exposition of the American Society of Hematology (ASH) in San Francisco, December 6-9, 2014.

The abstracts are listed below and available on the ASH conference website at: https://ash.confex.com/ash/2014/webprogram/start.html

Poster Presentations

Title: "Multiplex Genome Editing As a Platform for "Off-the-Shelf" Adoptive CAR T-Cell Immunotherapies"

• Abstract Number: 1111
• Date: Saturday, December 6, 2014
• Presentation Time: 5:30 PM 7:30 PM PST

Title: "Allogeneic T-Cells Targeting CD123 for Adoptive Immunotherapy of Acute Myeloid Leukemia (AML)"

• Abstract Number: 1116
• Date: Saturday, December 6, 2014
• Presentation Time: 5:30 PM 7:30 PM PST

Title: "In Vivo Proof of Concept of Activity and Safety of UCART19, an Allogeneic 'Offthe-Shelf' Adoptive T-Cell Immunotherapy against CD19+ B-Cell Leukemias"

• Abstract Number: 4689
• Date: Monday, December 8, 2014
• Presentation Time: 6:00 PM 8:00 PM PST

For further information, please contact:

Cellectis

Philippe Valachs / Jennifer Moore Phone: +33 (0)1 81 69 16 00 e-mail: media@cellectis.com

BMC Communications - New York City Brad Miles Phone: 646-513-3125 e-mail: bmiles@bmccommunications.com

About Cellectis

Cellectis is a biopharmaceutical company focused on developing immunotherapies based on gene edited engineered CART-cells (UCART). The company's mission is to develop a new generation of cancer therapies based on engineered Tcells. Cellectis capitalizes on its 14 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 for treating leukemias and solid tumors. Cellectis' adoptive cancer immunotherapy for chronic and acute leukemias is based on allogeneic T-cell chimeric antigen receptor (CAR) technology. 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.

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 for shares in Cellectis in any country. This press release contains forward-looking statements that relate to the Company's objectives based on the current expectations and assumptions of the Company's management only and involve unforeseeable risk and uncertainties that could cause the Company to fail to achieve the objectives expressed by the forward-looking statements.