Cellectis Appoints Mark Frattini, M.D., Ph.D. as Chief Medical Officer

New York, NY – September 28, 2022 - 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, announced today the appointment of Mark Frattini, M.D., Ph.D., as Chief Medical Officer, effective immediately.

Dr. Frattini has over 20 years of experience in the field of hematological malignancies and joined Cellectis in August 2020 as Senior Vice President of Clinical Sciences. Mark has been responsible for Cellectis’ clinical leadership including the clinical development strategy of the Company’s current immune-oncology UCART product candidates. He has also been serving as a core member of the senior clinical team and has been managing a team of physicians and clinical scientists. As Chief Medical Officer, Dr. Frattini will oversee clinical research and development for Cellectis’ UCART clinical trial programs. He will remain based in Cellectis’ New York office and is joining the Company’s executive committee.

“Mark already had an impressive track record before joining Cellectis. He has continued to lead our clinical teams successfully over the last two years and I am thrilled to continue working with him in this expanded role. We are confident that his extensive experience in clinical development within hematology and oncology along with his strong leadership capabilities are invaluable as we advance our pipeline of next-generation CAR T-cell therapies.” said André Choulika, Ph.D., Chief Executive Officer at Cellectis.

“I am eager to step into the role of Chief Medical Officer and I’m delighted to continue working alongside the Cellectis team as we focus our efforts on advancing our clinical pipeline.“ said Mark Frattini, M.D., Ph.D. “I’ve always been passionate about working on the next generation of cell and gene therapies that can address the unmet medical needs of patients living with blood cancers. I look forward to helping progress our pipeline and leading the ongoing advancement of Cellectis’ clinical programs."

Prior to joining Cellectis, Dr. Frattini was Executive Medical Director, Program Lead, Global Clinical Research & Development at Celgene/Bristol Myer Squibb and was responsible for the oversight and management of several of Celgene’s sponsored programs in the hematology therapeutic area. Before joining Celgene, Dr. Frattini spent over 16 years as a physician-scientist specializing in hematologic malignancies in academia at Memorial Sloan-Kettering Cancer Center and Columbia University where he was a member of the adult leukemia service and the Experimental Therapeutics center at both institutions. At Columbia University from 2013-2018 Mark also served as the Director of Research for Hematologic Malignancies.

Dr. Frattini holds a M.D. and Ph.D. in Biochemistry and Molecular Biology from The University of Chicago and received his Internal Medicine residency and Medical Oncology fellowship training at Johns Hopkins Hospital.