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Cellectis S.A. The information included in this report on Form 6-K, including Exhibit 99.1, shall be deemed to be incorporated by reference in the registration statements of Cellectis S.A. on Form F-3 (Nos. 333-284302 and 333-288491) and Form S-8 (Nos. 333-204205, 333-214884, 333-222482, 333-227717, 333-258514, 333-267760, 333-273777, 333-284301 and 333-290218), to the extent not superseded by documents or reports subsequently filed.

Cellectis S.A.'s interim report for the six-month period ended June 30, 2026

101 The following materials from Cellectis S.A.'s Report on Form 6-K formatted in iXBRL (Inline eXtensible Business Reporting Language): (i) the Interim Condensed Statements of Consolidated Financial Position (Unaudited), (ii) the Interim Condensed Statements of Consolidated Operations (Unaudited), (iii) the Interim Condensed Statements of Consolidated Comprehensive Income (Loss) (Unaudited), (iv) the Interim Condensed Statements of Consolidated Cash Flows (Unaudited), (v) the Interim Condensed Statements of Changes in Consolidated Shareholders' Equity (Unaudited), and (vi) the Notes to the Interim Condensed Consolidated Financial Statements (Unaudited).