Cellectis Showcased Preclinical Data at an Oral Presentation and Two Poster Presentations at the 29th International Society for Cell & Gene Therapy (ISCT 2023) Annual Event

• Preclinical data on UCART20x22, Cellectis’ first allogeneic dual CAR T-cell product candidate to treat B-NHL, presented at an oral session

• Encouraging data presented on gene editing process using Cellectis TALEN technology to develop highly efficient HBB gene correction of sickle cell mutation

• Comprehensive analysis to better design efficient TALE Base Editors (TALE-BE) using Cellectis’ TALEN technology presented in a poster

NEW YORK, June 05, 2023 (GLOBE NEWSWIRE) -- Cellectis (the “Company”) (Euronext Growth: ALCLS - NASDAQ: CLLS), a clinical-stage biotechnology company using its pioneering gene-editing platform to develop life-saving cell and gene therapies, showcased preclinical data at an oral presentation and two poster presentations at the International Society for Cell & Gene Therapy (ISCT) 29^th annual event that took place at the Paris Convention Center in Paris, France on May 31 - June 3, 2023.

“Our breadth of scientific presence at the 29th ISCT annual event reflects the type of cutting-edge research our teams undertake, which we believe is essential to address patients’ unmet medical need. We are proud of the pre-clinical results presented and remain deeply focused on the development of our product candidates to deliver breakthrough treatments that could benefit thousands of patients worldwide,” said André Choulika, Ph.D., Chief Executive Officer at Cellectis.

Oral Presentation

UCART20x22: allogeneic dual CAR T-cells for the treatment of B-cell malignancies

Autologous CAR T-cell therapies have shown outstanding responses in the treatment of selected blood cancers, predominantly B-cell malignancies. Nevertheless, long term studies revealed that some patients treated with CD19 or CD22 CAR T-cells can relapse due to low target antigen expression in tumor cells or to antigen loss. The therapeutic options after CAR T-cell relapses are limited, emphasizing the need to develop novel therapies to improve current survival rates. There is also need for allogeneic “off-the-shelf” therapies that could be readily available at the time of treatment decision and overcome limitations of current autologous approaches.