EXHIBIT 99.1

Cellectis to Present Pre-Clinical Data on Multi-armored Allogeneic MUC1-CAR T-cells Targeting Triple-Negative Breast Cancer at the Society for Immunotherapy of Cancer (SITC) 38th Annual Meeting

NEW YORK, Sept. 27, 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, announced today that pre-clinical data on MUC1-CAR T-cells to overcome key challenges of targeting solid tumors, will be presented at the Society for Immunotherapy of Cancer’s 38^th Annual Meeting (SITC 2023), that will take place on November 1-5, 2023 at San Diego Convention Center in San Diego (CA).

Poster Presentation:

Laurent Poirot, SVP Immunology of Cellectis, will present a poster on the benefits of combining potency attributes for TALEN®-edited smart CAR T-cells targeting MUC1 in preclinical models of triple-negative breast cancer.

Title: TGF-Beta Blockade Combined with Activation-Induced IL12 Secretion Synergize to Optimize Potency of MUC1-CAR T-cells in Preclinical Targeting of Triple-Negative Breast Cancer.

Poster Number: 254

Presenter: Laurent Poirot, Ph.D., SVP Immunology, Cellectis.

Date/Time: Poster will be on display Saturday, November 4^th, 2023 from 9:00 a.m. to 8:30 p.m. PDT, at San Diego Convention Center, Hall A.

Full text of the abstract will be made public on October 31, 2023 at 9:00 a.m. EDT on the SITC website and in a Journal for ImmunoTherapy of Cancer (JITC) supplement published on Oct. 31^st, 2023 at 6 a.m. PDT/9 a.m. EDT.

About Cellectis     

Cellectis is a clinical-stage biotechnology company using its pioneering gene-editing platform to develop life-saving cell and gene therapies. Cellectis utilizes an allogeneic approach for CAR-T immunotherapies in oncology, pioneering the concept of off-the-shelf and ready-to-use gene-edited CAR T-cells to treat cancer patients, and a platform to make therapeutic gene editing in hemopoietic stem cells for various diseases. As a clinical-stage biopharmaceutical company with over 23 years of experience and expertise in gene editing, Cellectis is developing life-changing product candidates utilizing TALEN®, its gene editing technology, and PulseAgile, its pioneering electroporation system to harness the power of the immune system in order to treat diseases with unmet medical needs. Cellectis’ headquarters are in Paris, France, with locations in New York, New York and Raleigh, North Carolina. Cellectis is listed on the Nasdaq Global Market (ticker: CLLS) and on Euronext Growth (ticker: ALCLS).     

Forward-looking Statements  

This press release contains “forward-looking” statements within the meaning of applicable securities laws, including the Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by words such as “anticipate,” “expect,” “plan,” “could” and “will,” or the negative of these and similar expressions. These forward-looking statements, which are based on our management’s current expectations and assumptions and on information currently available to management, include statements about the potential benefit of the Company’s candidate products. These forward-looking statements are made in light of information currently available to us and are subject to numerous risks and uncertainties, including with respect to the numerous risks associated with biopharmaceutical product candidate development. With respect to our cash runway, our operating plans, including product development plans, may change as a result of various factors, including factors currently unknown to us. Furthermore, many other important factors, including those described in our Annual Report on Form 20-F and the financial report (including the management report) for the year ended December 31, 2022 and subsequent filings Cellectis makes with the Securities Exchange Commission from time to time, as well as other known and unknown risks and uncertainties may adversely affect such forward-looking statements and cause our actual results, performance or achievements to be materially different from those expressed or implied by the forward-looking statements. Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to update the reasons why actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.   

For further information on Cellectis, please contact:     

Media contact:       

Patricia Sosa Navarro, Chief of Staff to the CEO, +33 (0)7 76 77 46 93, media@cellectis.com  

Investor Relations contacts:       

Arthur Stril, Chief Business Officer, +1 (347) 809 5980, investors@cellectis.com       

Ashley R. Robinson, LifeSci Advisors, +1 617 430 7577 

Attachment

• SITC_2023_curtain raiser_PR (https://ml.globenewswire.com/Resource/Download/4ad4a8cd-fad6-45c3-bef6-09d2ece0635a)