Cellectis Announces Launch of Follow-On Offering NEW YORK--(BUSINESS WIRE)

Announces Launch of Follow-On Offering

NEW YORK--(BUSINESS WIRE)--April 3, 2018--Regulatory News:

Cellectis S.A. (Paris:ALCLS) (NASDAQ:CLLS) (NASDAQ: CLLS - EURONEXT

GROWTH: ALCLS), a clinical-stage biopharmaceutical company focused on

developing immunotherapies based on gene-edited allogeneic CAR T-cells,

today announced the launch, subject to market conditions, of an

underwritten public offering of $175 million of its American Depositary

Shares ("ADS"), each representing one ordinary share of Cellectis. In

connection with the offering, Cellectis expects to grant the

underwriters a 30-day option to purchase up to an additional 15% of the

aggregate offering size.

Goldman Sachs & Co. LLC and Citigroup are acting as book-running

managers for the offering. Barclays is also acting as a book-running

manager. Nomura is acting as lead manager and Oppenheimer & Co. and

Ladenburg Thalmann are acting as co-managers.

A shelf registration statement on Form F-3 (including a prospectus)

relating to Cellectis' American Depositary Shares was filed with the

Securities and Exchange Commission (the "SEC") and has become effective.

Before purchasing American Depositary Shares in the offering, you should

read the preliminary prospectus supplement and the accompanying

prospectus, together with the documents incorporated by reference

therein. You may obtain these documents for free by visiting EDGAR on

the SEC's website at www.sec.gov. Alternatively, a copy of

the preliminary prospectus supplement (and accompanying prospectus)

relating to the offering may be obtained from Goldman Sachs & Co. LLC,

Attention: Prospectus Department, 200 West Street, New York, NY 10282,

or by telephone at (866) 471-2526 or by email at prospectus-ny@ny.email.gs.com,

Citigroup Global Markets Inc., c/o Broadridge Financial Solutions, 1155

Long Island Avenue, Edgewood, NY 11717, or by telephone at (800)

831-9146 or Barclays Capital Inc., c/o Broadridge Financial Solutions,

1155 Long Island Avenue, Edgewood, New York 11717, or by telephone at

(888) 603-5847 or by email at barclaysprospectus@broadridge.com.

This press release shall not constitute an offer to sell or the

solicitation of an offer to buy these securities, nor shall there be any

sale of these securities in any state or jurisdiction in which such

offer, solicitation or sale would be unlawful prior to registration or

qualification under the securities laws of any such state or

jurisdiction. In particular, no public offering of the ADSs will be made

Special Note Regarding Forward-Looking Statements

This press release contains "forward-looking" statements that are based

on our management's current expectations and assumptions and on

information currently available to management. Forward-looking

statements involve known and unknown risks, uncertainties and other

factors that may cause our actual results, performance or achievements

to be materially different from any future results, performance or

achievements expressed or implied by the forward-looking statements.

Further information on the risk factors that may affect company business

and financial performance is included in Cellectis' Annual Report on

Form 20-F for the year ended December 31, 2017, and subsequent filings

Cellectis makes with the SEC from time to time. Except as required by

law, we assume no obligation to update these forward-looking statements

publicly, or to update the reasons actual results could differ

materially from those anticipated in the forward-looking statements,

even if new information becomes available in the future.

VP of Communications

Kasunich, 212-896-1241

KCSA Strategic Communications

Simon Harnest, 646-385-9008

VP of Corporate Strategy