Cellectis Receives FDA RMAT Designation for lasme-cel, the First Allogeneic CAR-T Therapy in a Pivotal Trial for Patients with r/r B-ALL

New York, NY - June 9, 2026 - 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, today announced that the U.S. Food and Drug Administration (FDA) granted Regenerative Medicine Advanced Therapy (RMAT) designation to lasmecabtagene timgedleucel (lasme-cel), its CD22-targeting allogeneic CAR-T cell therapy product candidate, for the treatment of patients with relapsed or refractory B-cell acute lymphoblastic leukemia (r/r B-ALL).

The granting of RMAT designation reflects the FDA's recognition of the potential for lasme-cel to address the unmet medical need faced by patients with r/r B-ALL.

The RMAT designation is supported by Phase 1 BALLI-01 data demonstrating promising efficacy and a manageable safety profile. Final Phase 1 data from the BALLI-01 trial of lasme-cel will be presented in an oral session at the 2026 Congress of the European Hematology Association (EHA) this Saturday, June 13 at 5:15 - 6:30pm CET by Nitin Jain, M.D., Professor of Medicine, Department of Leukemia at MD Anderson Cancer Center in Houston (TX).

"As the company that pioneered allogeneic CAR-T, we see the RMAT designation for lasme-cel as a meaningful recognition of the need for off-the-shelf CAR-T options for patients with relapsed or refractory B-ALL, patients who cannot wait. This designation strengthens our dialogue with the FDA as we advance lasme-cel through its pivotal program" said André Choulika, Ph.D., Co-founder and Chief Executive Officer of Cellectis.

The BALLI-01 trial Pivotal Phase 2 is open for enrollment. Information on participant eligibility and participating clinical centers can be found on clinicaltrials.gov: BALLI-01 (NCT04150497).