Cellectis

Report Publication Announcement • Sep 2, 2014

September 11, 2014 New York, NY

Genome Engineering & CART Cells: At the forefront of immuno-oncology

Cellectis to Host R&D/ Analyst Day on September 11th at Le Parker Meridien Hotel in New York City

September 2, 2014 — New York (NY) — Cellectis (Alternext: ALCLS.PA), a leader in the development of adoptive immunotherapies based on engineered allogeneic CART cells (UCART) will host a R&D/ Analyst Day on Thursday, September 11 at 7:30AM in New York City. Cellectis' scientists will provide an overview of the Company's therapeutic innovations. The event will also feature presentations by key opinion leaders: Pr. Laurence Cooper, MD Anderson Cancer Center ; Dr. Jaume Pons Senior Vice President and CSO of Rinat, the biotech unit of Pfizer and Eric Falcand, Director, Alliance Management & US Licenses at Servier Laboratories.

AGENDA

7:30 REGISTRATION & BREAKFAST

8:00 Welcome Remarks Dr. André Choulika, Ph.D. – Chairman & CEO of Cellectis

8:05 Keynote address – Pr. Laurence Cooper, MD, Ph.D. – University of Texas, MD Anderson Cancer Center, Houston, Texas (25mn)

8:30 The Discovery at Cellectis

Dr. Philippe Duchateau, Ph.D. – Chief Scientific Officer (10 mn)

8:40 Genome Engineering Technologies

Dr. Julien Valton, Ph.D. – Project Leader (20 mn)

9:00 Editing the T Cell Genome

Dr. Laurent Poirot, Ph.D. – Head of Early Discovery (20 mn)

9:20 Dr. Jaume Pons, Ph.D. – Senior Vice President and Chief Scientific Officer of Rinat, the biotech unit of Pfizer, San Francisco, California (15 mn)

9:35 CAR architecture & CAR application Dr. Alexandre Juillerat, Ph.D. – Project Leader (20 mn)

9:55 BREAK

10:05 About UCART19 and UCART123 Dr. Julianne Smith, Ph.D. – Vice President, CART Development (20 mn) 10:25 Eric Falcand – Director, Alliance Management & US Licenses at Servier Laboratories (15 mn)

10:40 Manufacturing & Regulatory

Stéphan Reynier – Head of Regulatory (15 mn)

10:55 Closing remarks and future perspectives for our allogeneic technology Dr. Mathieu Simon, MD – Executive Vice President (20 mn)

11:15 Q&A, OPEN DISCUSSION

Please RSVP with

Cellectis /Jennifer Moore jennifer.moore@cellectis.com The Trout Group /Simon Harnest sharnest@troutgroup.com P: +1-646-378-2919

Location: Le Parker Meridien Hotel - 119 West 56th Street - NEW YORK Time: 7:30 -11:45 AM Upon invitation – limited seats available

About Cellectis

Cellectis is a biopharmaceutical company focused on oncology. The company's mission is to develop a novel generation of therapy based on engineered T-cells to treat cancer. Cellectis capitalizes on its 14 years of expertise in genome engineering, based on TALEN™, meganucleases and the state-of-the-art electroporation technology Pulse Agile, to create a new generation of cancer immunotherapy for treating leukemias and solid tumors. Cellectis adoptive cancer immunotherapy for chronic and acute leukemias is based on the first allogeneic T-cell chimeric antigen receptor (CAR) technology. CAR technologies are designed to target surface antigens expressed on cells. These treatments reduce toxicities associated with current chemotherapeutics and have the potential for curative therapy. The Cellectis Group is focused on life sciences and uses leading genome engineering technologies to build innovative products in various fields and markets. Cellectis is listed on the NYSE Alternext market (ticker: ALCLS). To find out more about us, visit our website: www.cellectis.com.

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.