Cellectis

Regulatory Filings • Sep 5, 2017

PRESS RELEASE

Cellectis to Participate in Upcoming Investor Conferences

September 4, 2017 – New York (N.Y.) – Cellectis (Alternext: ALCLS - Nasdaq: CLLS) a clinical-stage biopharmaceutical company focused on developing immunotherapies based on gene-edited allogeneic CAR T-cells (UCART), will present at several upcoming investor conferences. Three of them will be webcasted live. The replay will be available in the Investor Relations section of the Company's website at http://cellectis.com/en/ investors/events-and-webcasts/

• September 6, 2017, André Choulika, CEO of Cellectis, to present at the Wells Fargo Conference in Boston from 4:10 to 4:40pm ET
• September 11, 2017, André Choulika to present at the Morgan Stanley Global Healthcare Conference in New York from 9:20 to 9:50am ET
• September 26, 2017, André Choulika to present at the Ladenburg Thalmann 2017 Conference in New York from 2:00 to 2:25pm ET
• September 28, 2017, André Choulika to present at the Leerink Rare Disease & Immuno-Oncology Conference in New York at 2:30 pm ET

About Cellectis

Cellectis is a clinical-stage biopharmaceutical company focused on developing a new generation of cancer immunotherapies based on gene-edited T-cells (UCART). By capitalizing on its 17 years of expertise in gene editing – built on its flagship TALEN® technology and pioneering electroporation system PulseAgile – Cellectis uses the power of the immune system to target and eradicate cancer 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 is listed on the Nasdaq market (ticker: CLLS) and on the NYSE Alternext market (ticker: ALCLS). To find out more about us, visit our website: www.cellectis.com

Talking about gene editing? We do it. TALEN® is a registered trademark owned by the Cellectis Group.

For further information, please contact:

Media contacts:

Jennifer Moore, VP of Communications, 917-580-1088, media@cellectis.com Caitlin Kasunich, KCSA Strategic Communications, 212-896-1241, ckasunich@kcsa.com

IR contact:

Simon Harnest, VP of Corporate Strategy and Finance, 646-385-9008, simon.harnest@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 risk and uncertainties that could cause the Company to fail to achieve the objectives expressed by the forward-looking statements above.

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