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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: September 8, 2015
Commission File Number: 001-36891

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

Cellectis Reports Second Quarter and First Half Year 2015 Financial Results

PARIS--(BUSINESS WIRE)--September 8, 2015--Regulatory News:

Cellectis S.A. (Alternext: ALCLS; Nasdaq: CLLS), a biopharmaceutical company focused on developing immunotherapies based on gene edited CAR-T cells (UCART), today announced its results for the three- and six-month periods ended June 30, 2015.

Recent Corporate Highlights

• Completed U.S. IPO in March 2015 raising more than $228 million of proceeds.
• Opened U.S. research facility at the Alexandria Center in New York City, with more than 12,000 sq. ft. of state-of-the-art laboratories and 15 full time staff, in proximity to Cellectis’s U.S. partners and investors.
• Entered into a strategic collaboration with Weill Cornell Medical College to accelerate the development of targeted immunotherapy for patients with acute myeloid leukemia (AML). This alliance will foster the development of our lead product candidate, UCART123, for treatment of AML.
• Achieved a significant milestone under our collaboration agreement with Servier.
• Entered into a broad preclinical and clinical strategic alliance with MD Anderson Cancer Center to pursue the development of Cellectis’ candidate products UCARTCS1, UCART22, UCART38 in T-cell ALL and UCART123 in a rare non curable disease BPDCN.

Development Update

• Ongoing manufacturing of GMP-compatible CAR T-cell batches in line.
• Presented additional study results on gene-edited allogeneic (“off-the-shelf”) CAR T-cells, strengthening the pre-clinical proof of concept in lead development programs. In particular, Cellectis presented the following results at ASCO and ASGCT:
  • “UCART19, an allogeneic “off-the-shelf” adoptive T-cell immunotherapy against CD19+ B-cell leukemias”
  • “Adoptive immunotherapy of acute myeloid leukemia (AML) with allogeneic CAR T-cells targeting CD123”
  • “A multidrug resistant engineered CAR T-cell for allogeneic combination immunotherapy”
• Publication of a study in Molecular Therapy, a Nature Publishing Group journal, describing the development of the next generation of engineered CAR T-cells compatible with allogeneic adoptive transfer immunotherapy.
• Publication of an article in Cancer Research describing the applicability of TALEN^®-mediated genome editing to a scalable process, enabling the manufacturing of non-alloreactive T-cells from third-party donors in a robust, scalable process, thus allowing "off-the-shelf" CAR T-cell immunotherapies.
• Our plant sciences subsidiary, which changed its name to Calyxt, Inc., continues to show promising developments and commenced field trials of cold storable potatoes in the United States of America and high oleic/low transfat soybean varieties in Argentina and the United States of America.

Financial Results

Since Cellectis did not have consolidated financial statements for individual quarters during fiscal year 2014, no comparative quarterly 2014 figures will be presented during 2015. Cellectis will publish quarter-over-quarter comparative figures starting with the first quarter of 2016.

Cellectis’s consolidated financial statements have been prepared in accordance with International Financial Reporting Standards, or IFRS, as issued by the International Accounting Standards Board (“GAAP”).

Second Quarter 2015 Financial Results

Cash Position: As of June 30, 2015 Cellectis had €283.9 million in cash and cash equivalents compared to €112.3 million as of December 31, 2014. This increase is primarily attributable to the $228 million of proceeds from the U.S. initial public offering in March 2015.

Revenues and Other Income: Total revenues and other income were €8.0 million for the second quarter 2015 and primarily comprised €6.6 million of collaboration revenues and €0.9 million of license revenues.

Total Operating Expenses and Other Operating Income: Total operating expenses for the second quarter of 2015 were €20.1 million, which includes non-cash stock-based compensation expenses of €7.2 million.

R&D Expenses: Research and development expenses for the second quarter of 2015 were €10.6 million, including personnel expenses of €7.6 million and external purchases and other expenses of €3.0 million. Research and development expenses for the second quarter notably reflected the impacts of (i) non-cash stock-based compensation expense of €3.3 million and (ii) social charges related to free shares granted during the second quarter of €1.8 million.

SG&A Expenses: Selling, general and administrative expenses were €9.1 million for the second quarter of 2015, and included personnel expenses of €6.3 million and external purchases and other expenses of €2.8 million. SG&A expenses for the second quarter notably reflected the impacts of (i) non-cash stock-based compensation expense of €3.8 million and (ii) social charges related to free shares granted during the second quarter of €1.8 million.

Financial Loss: Financial loss was €10.0 million for the second quarter of 2015, which is primarily attributable to an unfavorable Euro-Dollar exchange rate applied to U.S. dollar-denominated cash and cash equivalents during the quarter.

Net Loss Attributable to Shareholders of Cellectis: Net loss attributable to shareholders of Cellectis was €22.2 million, or €0.63 per share, for the second quarter of 2015. The decrease of €28.3 million in net earnings, compared to the first quarter 2015 net gain attributable to shareholders of Cellectis of €6.1 million, notably reflects the effects of unfavorable Euro-Dollar exchange rates with respect to our U.S. Dollar cash and cash equivalent accounts and to a lesser extent the impact of non-cash stock-based compensations during the second quarter of 2015. Adjusted net loss attributable to shareholders of Cellectis for the second quarter of 2015, which excludes a non-cash stock-based compensation expense of €7.1 million, was €15.0 million, or €0.43 per share. Please see "Note Regarding Use of Non-GAAP Financial Measures" for a reconciliation of GAAP net income to adjusted net income.

First Half Year 2015 Financial Results

Revenues and Other Income: During the six months ended June 30, 2015 and 2014, Cellectis recorded €17.2 million and €10.3 million, respectively, in revenues and other income. The increase of €7.1 million primarily reflects an increase of €13.2 million in revenues under our collaboration agreements with Servier and Pfizer which were partially offset by a decrease in license, R&D services and Product and Services revenues.

Total Operating Expenses and Other Operating Income: Total operating expenses and other operating income for the first half of 2015 was €32.9 million (€15.3 million for the same period in 2014). Total operating expenses and other operating income for first half of 2015 and 2014 include non-cash stock-based compensation expenses of €8.0 million and €0.4 million, respectively.

R&D Expenses: Cellectis recorded research and development expenses of €16.2 million in the first half of 2015 and €7.7 million in the first half of 2014. These amounts include personnel expenses of €11.1 million and €3.1 million in 2015 and in 2014, respectively, and purchases and external expenses and other expenses of €5.1 million and €4.6 million, respectively. The increase in research and development expenses also reflects expenditures for the development of UCART programs toward their entry into Phase 1 clinical trials, expenses related to the opening of our facility in New York, non-cash stock-based compensation expense of €3.8 million and social charges on stock options and free share grants of €4.1 million in 2015.

SG&A Expenses: SG&A expenses were €16.3 million in the first half year of 2015 compared to €6.2 million in the corresponding period of 2014. SG&A expenses included personnel expenses of €11.2 million in 2015 compared to €3.0 million in 2014, and purchases and external expenses and other expenses of €5.1 million in 2015 compared to €3.2 million in 2014. The increase in SG&A expenses in 2015 was attributable, among other things, to €4.3 million of non-cash stock-based compensation expense, €4.6 million of social charges on stock options and free share grants and an increase in professional costs, in each case in connection with our U.S. IPO in March 2015.

Financial result: Financial loss was €0.2 million for the first half year of 2015 compared to €16,000 financial gain for the corresponding period in 2014. This increase was primarily attributable to an unfavorable Euro-Dollar exchange rate applied to U.S. dollar-denominated cash and cash equivalents during 2015.

Net Loss Attributable to Shareholders of Cellectis: Net loss attributable to shareholders of Cellectis was of €16.0 million, or €0.48 per share, for the first half year of 2015 compared to a net loss attributable to shareholders of Cellectis of €7.4 million, or €0.32 per share, for the corresponding period in 2014. Adjusted net loss attributable to shareholders of Cellectis for the first half year of 2015 was €8.2 million, or €0.25 per share, compared to adjusted net loss attributable to shareholders of Cellectis of €7.1 million, or €0.31 per share, for the corresponding period in 2014. Adjusted net loss attributable to shareholders of Cellectis for the first half year of 2015 and 2014 excludes a non-cash stock-based compensation expense of €7.9 million and €0.3 million, respectively. Please see "Note Regarding Use of Non-GAAP Financial Measures" for a reconciliation of GAAP net income to adjusted net income.

Note Regarding Use of Non-GAAP Financial Measures

Cellectis S.A. provides non-GAAP net income and non-GAAP net income per share measures that include adjustments to figures presented in accordance with GAAP. In presenting non-GAAP net income, GAAP net income is adjusted to exclude non-cash stock-based compensation expense. Cellectis believes that these non-GAAP financial measures, when considered together with the GAAP figures, can enhance an overall understanding of Cellectis' financial performance. The non-GAAP financial measures used by Cellectis may be calculated differently, and therefore may not be comparable to similarly titled non-GAAP financial measures used by other companies. Please refer below for a reconciliation of these non-GAAP financial measures to the comparable GAAP financial measures.

About Cellectis

Cellectis is a biopharmaceutical company focused on developing immunotherapies based on gene edited engineered CAR-T cells (UCART). The company’s mission is to develop a new generation of cancer therapies based on engineered T-cells. Cellectis capitalizes on its 15 years of expertise in genome engineering - based on its flagship TALEN® products and meganucleases and pioneering electroporation PulseAgile technology - to create a new generation of immunotherapies. CAR technologies are designed to target surface antigens expressed on 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 S.A. is listed on the Nasdaq Global Market (ticker: CLLS) and on the NYSE Alternext market (ticker: ALCLS). To find out more about us, visit our website: www.cellectis.com

TALEN® is a registered trademark owned by the Cellectis Group.

Cautionary Statement Regarding Forward-Looking Statements

This press release contains certain “forward - looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by words such as “anticipate,” “believe,” “can,” “could,” “estimate,” “expect,” “intend,” “is designed to,” “may,” “might,” “plan,” “potential,” “predict,” “objective,” “should,” or the negative of these and similar expressions and include, but are not limited to, statements regarding the outlook for Cellectis’ future business and financial performance. Forward-looking statements are based on management’s current expectations and assumptions, which are subject to inherent uncertainties, risks and changes in circumstances, many of which are beyond Cellectis’ control. Actual outcomes and results may differ materially due to global political, economic, business, competitive, market, regulatory and other factors and risks. Cellectis expressly disclaims any obligation to update or revise any of these forward-looking statements, whether because of future events, new information, a change in its views or expectations, or otherwise.

CONTACT:
Media
Jennifer Moore, VP Communications
Phone: +1 917-580-1088
email: media@cellectis.com
or
KCSA Strategic Communications
Caitlin Kasunich / Dixon Moretz
+1 212.896.1241 / +1 212.896.1251
ckasunich@kcsa.com / dmoretz@kcsa.com
or
Investor relations:
Simon Harnest, VP Finance and Investor Relations
Phone: +1 646-385-9008
email: simon.harnest@cellectis.com