Cellectis Announces Withdrawal of Follow-On Offering

NEW YORK, Dec. 15, 2020 (GLOBE NEWSWIRE) — Cellectis (Euronext Growth: ALCLS – Nasdaq: CLLS), a clinical-stage biopharmaceutical company focused on developing immunotherapies based on gene-edited
allogeneic CAR T-cells (UCART), today announced that it has withdrawn the proposed underwritten offering of American Depositary Shares (“ADS”) due to market conditions.

The Company believes that