Cellectis

Pre-Annual General Meeting Information • Jun 9, 2018

PRESS RELEASE

Shareholders' General Meeting of June 26, 2018

June 8, 2018 – Paris (11:45pm CEST) – Cellectis (Euronext Growth: ALCLS - Nasdaq: CLLS), a clinical-stage biopharmaceutical company focused on developing immunotherapies based on gene-edited allogeneic CAR T-cells (UCART), announced today that it will hold its Combined Shareholders' General Meeting on June 26, 2018 at 9:30 a.m. CEST at the Company's headquarters located at 8, rue de la Croix Jarry (4th floor), 75013 Paris, France.

The notice convening the General Meeting states the detailed agenda and is available on the website of the Company: http://www.cellectis.com/en/investors/general-meetings/

Shareholders, regardless of the number of shares they own, shall have the right to attend the meeting, be represented by a proxy or vote by mail.

The right to attend meetings shall be governed by all applicable laws and regulations and be conditional upon the registration, for accounting purposes, of the shares in the name of the shareholder or a designated intermediary on the second working day preceding the shareholders' meeting at midnight, Paris time, either in the registered share accounts kept by the Company or the bearer share accounts kept by the authorized intermediary.

Holders of registered ordinary shares shall not be required to meet any formality and shall be granted access upon proof of identity.

Holders of bearer ordinary shares must submit a certificate of participation, issued by their financial intermediary at least two working days before the date of the meeting.

It is recalled that, pursuant to the applicable law:

• the duly completed proxy form must be received by the Company's registered office or SGSS at least two days prior to the date of the meeting, i.e. no later than June 22, 2018.
• holders of bearer shares must add to their form a certificate of participation issued by the financial intermediary with whom their shares are deposited.

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 18 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 Euronext Growth (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 Cellectis.

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