SEGMENT FINANCIAL INFORMATION SUPPLEMENT TO CELLECTIS S.A. S INTERIM REPORT FOR THE QUARTER AND SIX-MONTH PERIOD ENDED JUNE 30, 2017. PRELIMINARY NOTE On

SEGMENT FINANCIAL INFORMATION SUPPLEMENT

TO CELLECTIS S.A. S INTERIM REPORT FOR

THE QUARTER AND SIX-MONTH PERIOD ENDED JUNE 30, 2017.

2017, Cellectis filed its interim report for the quarter and six-month period ended June 30, 2017 (the Interim Report ) on Form 6-K. This supplement provides certain segment financial information omitted from the Interim Report

pending the filing of Calyxt, Inc. s initial quarterly report on Form 10-Q. The information included in this report supplements the Interim Report with such segment financial information.

The additional note (the Additional Note ) to the interim consolidated financial statements for the period ended June 30, 2017: Reportable

segments, included as Item 1 of this interim report, supplements the unaudited condensed Interim Consolidated Financial Statements of Cellectis S.A. for the three-month and the six-month periods ended June 30, 2017 filed on August 2,

2017 by Cellectis S.A. with its Current Report on Form 6-K. The Additional Note has been prepared in accordance with International Financial Reporting Standards ( IFRS ) as issued by the International Accounting Standards Board

All references in this interim report to $, US$, U.S.$, U.S. dollars,

dollars, and USD mean U.S. dollars and all references to and euros mean euros, unless otherwise noted.

This interim report, including Management s Discussion and Analysis of Financial Condition and Results of Operations, contains

forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and Section 27A of the Securities Act. All statements other than present and historical facts and conditions contained in this interim report,

including statements regarding our future results of operations and financial position, business strategy, plans and our objectives for future operations, are forward-looking statements. When used in this interim report, the words

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 identify forward-looking statements. Actual results, performance or events may differ materially from those projected in any

forward-looking statement. Factors that may cause actual results to differ from those in any forward-looking statement include, without limitation, those described under Risk Factors and Special Note Regarding Forward-Looking

Statements in our Annual Report on Form 20-F filed with the Securities and Exchange Commission on March 23, 2017 (the Annual Report ). As a result of these factors, we cannot assure you that the forward-looking statements in

this interim report will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not

regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame or at all. We undertake no obligation to publicly update any forward-looking statements,

whether as a result of new information, future events or otherwise, except as required by law.

As used in this interim report, the terms

Cellectis, we, our, us, and the Company refer to Cellectis S.A. and its subsidiaries, taken as a whole, unless the context otherwise requires.

PART I FINANCIAL INFORMATION

Item 1. Condensed Financial Statements (Unaudited) Additional note to the interim consolidated financial statements for the period

ended June 30, 2017: Reportable segments

Reportable segments are identified as components of an enterprise that have discrete financial information available for evaluation by the

Chief Operating Decision Maker ( CODM ), for purposes of performance assessment and resource allocation.

We view our operations and manage our business in

two operating and reportable segments that are engaged in the following activities:

There are inter-segment

transactions between the two reportable segments, including the allocation of corporate general and administrative expenses by Cellectis S.A. and the allocation of research and development expenses among the reportable segments.

With respect to corporate general and administrative expenses, Cellectis S.A. provides Calyxt, Inc. with general sales and administrative

functions, accounting and finance functions, investor relations, intellectual property, legal advice, human resources, communication and information technology pursuant to a management agreement. Under the management agreement, Cellectis S.A.

charges Calyxt, Inc. in euros at cost plus a mark-up ranging between zero to 10%, depending on the nature of the service. Amounts due to Cellectis S.A. pursuant to inter-segment transactions bear interest at a rate of 12-month Euribor plus

The intersegment revenues represent the transactions between segments. Intra-segment transactions

are eliminated within a segment s results and intersegment transactions are eliminated in consolidation as well as in key performance indicators by reportable segment.

Information related to each reportable segment is set out below. Segment revenues and other income, Research and development expenses,

Selling, general and administrative expenses, and Royalties and other operating income and expenses, and Adjusted net income (loss) attributable to shareholders of Cellectis (which does not include non-cash stock-based expense) are used by the CODM

for purposes of making decisions about allocating resources to the segments and assessing their performance. The CODM does not review any asset or liability information by segment or by region.

Adjusted Net Income (Loss) attributable to shareholders of Cellectis is not a measure calculated in accordance with IFRS. Because Adjusted Net

Income (Loss) attributable to shareholders of Cellectis excludes Non-cash stock based compensation expense a non-cash expense, management believes that this financial measure, when considered together with the Company s IFRS financial

statements, can enhance an overall understanding of Cellectis financial performance. Moreover, management views the Company s operations, and manages its business, based, in part, on this financial measure.

Details of key performance indicators by reportable segment for the six-month periods ended June 30, 2016 and

Details of key performance indicators by reportable segment for the three-month periods ended

June 30, 2016 and 2017

Item 2. Management s Discussion & Analysis of Financial Condition and Results of Operations

related to each of our reportable segments is set out below. Segment revenues and other income, Research and development expenses, Selling, general and administrative expenses, and Royalties and other operating income and expenses, and Adjusted net

income (loss) attributable to shareholders of Cellectis (which does not include non-cash stock-based expense) are used by the CODM for purposes of making decisions about allocating resources to the segments and assessing their performance. The CODM

does not review any asset or liability information by segment or by region.

Adjusted Net Income (Loss) attributable to shareholders of

Cellectis is not a measure calculated in accordance with IFRS. Because Adjusted Net Income (Loss) attributable to shareholders of Cellectis excludes Non-cash stock based compensation expense a non-cash expense, we believe that this financial

measure, when considered together with our IFRS financial statements, can enhance an overall understanding of Cellectis financial performance. Moreover, our management views the Company s operations, and manages its business, based, in

part, on this financial measure.

There are inter-segment transactions between the two reportable segments, including the allocation of

corporate general and administrative expenses by Cellectis S.A. and the allocation of research and development expenses among the reportable segments. With respect to corporate general and administrative expenses, Cellectis S.A. provides Calyxt,

Inc. with general sales and administrative functions, accounting and finance functions, investor relations, intellectual property, legal advice, human resources, communication and information technology pursuant to a management agreement. Under the

management agreement, Cellectis S.A. charges Calyxt, Inc. in euros at cost plus a mark-up ranging between zero to 10%, depending on the nature of the service. Amounts due to Cellectis S.A. pursuant to inter-segment transactions bear interest at a

rate of 12-month Euribor plus 5% per annum.

The intersegment revenues represent the transactions between segments. Intra-segment

transactions are eliminated within a segment s results and intersegment transactions are eliminated in consolidation as well as in key performance indicators by reportable segment.

The following table summarizes segment revenues and segment operating profit (loss) for the

six-month periods ended June 30, 2016 and 2017:

Since 2016, we have allocated share-based compensation to the share-related entity (rather than the entity

related to the employee that benefited from such compensation), considering that the share-based compensation is linked to such entity s performance. Consequently, all share-based compensation based on Cellectis shares is charged in the

Therapeutics segment, even if some Calyxt employees are included in a Cellectis stock-option plan.

Therapeutics segment

External revenues and other income in our Therapeutics segment decreased by 10.0 million, from 27.4 million for the

six-month period ended June 30, 2016 to 17.4 million for the six-month period ended June 30, 2017. The decrease was primarily due to a decrease of 10.4 million in revenues under our collaboration agreements, partially

offset by an increase of 0.6 million in research tax credits, as described in sections Revenues and Other income of the Results of Operations presented in the Interim Report.

The decrease in total operating expenses in our Therapeutics segment of 5.6 million

from the six-month period ended June 30, 2016 to the six-month period ended June 30, 2017 resulted primarily from lower personnel expenses, attributable to a decrease of 3.2 million in social charges on stock options grants and

a decrease of 5.0 million in non-cash stock-based compensation expenses, partially offset by an increase of 0.7 million in personnel wages and salaries, an increase of 1.3 million in purchases, external and other

expenses and an increase of 0.5 million in royalties and other expenses.

Operating loss before tax for our Therapeutics

segment decreased by 4.4 million from the six-month period ended June 30, 2016 to the six-month period ended June 30, 2017.

Adjusted net loss attributable to shareholders of Cellectis for our Therapeutics segment increased 9.8 million from the six-month

period ended June 30, 2016 to the six-month period ended June 30, 2017.

External revenues and other income in our Plants segment increased by 0.2 million from 0.2 million for the six-month

period ended June 30, 2016 to 0.4 million for the six-month period ended June 30, 2017, mainly due to an increase of 0.1 million in income tax credits.

The increase in total operating expenses in our Plants segment of 1.9 million from the six-month period ended June 30, 2016 to

the six-month period ended June 30, 2017 resulted primarily from a significant increase in Calyxt, Inc. s activities, resulting in an increase of 1.2 million in non-cash stock-based compensation expenses, an increase of

0.4 million in personnel wages and salaries, and an increase of 0.5 million in purchases, external and other expenses partially offset by a decrease of 0.3 million in royalties expenses.

Operating loss before tax for our Plants segment decreased by 1.7 million from the six-month period ended June 30, 2016 to the

six-month period ended June 30, 2017.

Adjusted net loss attributable to shareholders of Cellectis for our Plants segment increased

0.9 million from the six-month period ended June 30, 2016 to the six-month period ended June 30, 2017.

Reconciliation of Plant result of operations

Since Calyxt, Inc., the agricultural biotechnology subsidiary of Cellectis, is a U.S. entity, its financial statements have been prepared in

accordance with U.S. GAAP. However, the Plant segment operations, as described in the Additional Note, have been prepared in accordance with IFRS. The tables below present a reconciliation of the results of operations of our Plant segment under IFRS

to the results of operations of Calyxt on a stand-alone basis under U.S. GAAP.

Reconciliation of Plant Segment result of operations for the six-month

period ended June 30, 2017

Reconciliation of Plant Segment result of operations for the six-month period ended June 30, 2016

Reconciliation of Plant Segment result of operations for the three-month period ended June 30, 2017