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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16 of
the Securities Exchange Act of 1934

Date of Report: July 25, 2017
Commission File Number: 001-36891

Cellectis S.A.
(Exact Name of registrant as specified in its charter)

8, rue de la Croix Jarry
75013 Paris, France
+33 1 81 69 16 00
(Address of principal executive office)

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Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F ☑ Form 40-F ⃞

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ⃞

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ⃞

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EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

3

Exhibit 99.1

Calyxt Announces Full Exercise of Over-Allotment Option and Closing of its Initial Public Offering

ST. PAUL, Minn. & NEW YORK--(BUSINESS WIRE)--July 25, 2017--Cellectis S.A. (NASDAQ:CLLS) and Calyxt, Inc. (NASDAQ:CLXT) announced today the closing of Calyxt’s initial public offering of 8,050,000 shares of its common stock at the initial public offering price of $8.00 per share (the “Offering”). The number of shares issued in the Offering includes the exercise in full of the underwriters’ option to purchase up to 1,050,000 additional shares. Calyxt received approximately $64.4 million in proceeds from the offering, before deducting underwriting fees and estimated offering expenses. Calyxt’s shares of common stock are traded on the NASDAQ Global Market under the symbol “CLXT”.

Calyxt is Cellectis’ gene editing agriculture company. Cellectis owns approximately 79.9% of Calyxt’s outstanding shares of common stock.

Citigroup, Jefferies and Wells Fargo Securities acted as joint book-running managers for the proposed offering. BMO Capital Markets and Ladenburg Thalmann acted as co-managers.

A registration statement on Form S-1 relating to these securities was declared effective by the U.S. Securities and Exchange Commission. A copy of the final prospectus relating to this Offering may be obtained from Citigroup Global Markets Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, or by telephone at (800) 831-9146, Jefferies LLC, Attention: Equity Syndicate Prospectus Department, 520 Madison Avenue, 2nd Floor, New York, NY 10022, or by telephone at (877) 547-6340, or by e-mail at Prospectus_Department@Jefferies.com, or Wells Fargo Securities, Attention: Equity Syndicate Department, 375 Park Avenue, New York, New York, 10152, at (800) 326-5897 or by email at cmclientsupport@wellsfargo.com.

The final prospectus is also available at www.sec.gov. 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.

This press release contains inside information within the meaning of Article 7(1) of the EU Market Abuse Regulation.

CONTACT:
Media:
Jennifer Moore, 917-580-1088
VP Communications
media@calyxt.com / media@cellectis.com
or
KCSA Strategic Communications
Caitlin Kasunich, 212-896-1241
ckasunich@kcsa.com
or
Nick Opich, 212-896-1206
nopich@kcsa.com
or
Investor Relations:
Simon Harnest, 646-385-9008
VP Corporate Strategy and Finance
simon.harnest@cellectis.com