Cellectis to Present Data on Non-Viral Gene Therapy and TALE Base Editors at the ESGCT Annual Congress
Cellectis (NASDAQ: CLLS) will present data at the ESGCT Annual Congress in Sevilla on Oct 7-10, 2025 showing advances in non-viral gene therapy and TALE base editors.
Key highlights: a poster on Oct 8, 2025 reports that kilobase-long circular single-stranded DNA (CssDNA) enabled high gene insertion rates in viable HSPCs and greater engraftment and maintenance of edits in a murine model versus AAV-edited HSPCs. A second poster on Oct 9, 2025 reports a comprehensive nuclear off-target analysis for TALE base editors (TALEB) in primary T cells with no observed bias toward C-to-T off-targets near CTCF sites, supporting TALEB safety for therapeutic engineering.
Cellectis (NASDAQ: CLLS) presenterà dati al Congresso Annual ESGCT a Siviglia dal 7-10 ottobre 2025 mostrando progressi nella terapia genica non virale e negli editor basati su TALE.
Riepiloghi principali: un poster il 8 ottobre 2025 riporta che un DNA circolare a singola elica di lunghezza kilobasica (CssDNA) ha permesso alte velocità di inserimento genico in HSPC vitali e una maggiore engraftment e mantenimento delle modifiche in un modello murino rispetto alle HSPCs editate con AAV. Un secondo poster il 9 ottobre 2025 riporta una analisi completa degli off-target nucleari per gli editor TALE (TALEB) in cellule T primarie con nessuna bias osservata verso off-target C-to-T vicino ai siti CTCF, sostenendo la sicurezza di TALEB per l'ingegneria terapeutica.
Cellectis (NASDAQ: CLLS) presentará datos en el Congreso Anual ESGCT en Sevilla del 7-10 de octubre de 2025 mostrando avances en la terapia génica no viral y en editores TALE basados en bases.
Rasgos clave: un cartel el 8 de octubre de 2025 informa que una ADN circular de cadena sencilla de longitud kilobásica (CssDNA) permitió altas tasas de inserción génica en HSPCs viables y mayor engraftment y mantenimiento de ediciones en un modelo murino frente a HSPCs editadas con AAV. Un segundo cartel el 9 de octubre de 2025 reporta un análisis nuclear integral de off-target para editores TALE (TALEB) en células T primarias sin sesgo observado hacia off-target C a T cerca de sitios CTCF, apoyando la seguridad de TALEB para la ingeniería terapéutica.
Cellectis (NASDAQ: CLLS)는 세비야에서 열리는 ESGCT 연례 학술대회에서 2025년 10월 7-10일에 비바이럴 유전자 치료와 TALE 염기 에디터의 발전을 보여주는 데이터를 발표합니다.
주요 하이라이트: 2025년 10월 8일에 발표된 포스터는 키로베이스 길이의 순환 단일 가닥 DNA(CssDNA)가 생존 가능한 HSPCs에서 높은 유전자 삽입 속도와 AAV로 편집된 HSPCs에 비해 마우스 모델에서 편집의 이식 및 유지에 유리함을 보고합니다. 2025년 10월 9일에 발표된 두 번째 포스터는 TALE 염기 에디터(TALEB)에 대한 핵(off-target) 분석을 일차 T 세포에서 수행했고 CTCF 부위 근처의 C-대 T(off-target) 편향이 관찰되지 않아 치료적 공학에 대한 TALEB의 안전성을 뒷받침합니다.
Cellectis (NASDAQ: CLLS) présentera des données lors du Congrès annuel ESGCT à Séville du 7-10 octobre 2025 montrant les progrès dans la thérapie génique non virale et les éditeurs TALE basés sur les bases.
Faits marquants : une affiche le 8 octobre 2025 indique qu’un ADN circulaire monocaténarisé de longueur kilobasique (CssDNA) permet des taux élevés d’insertion génétique dans des HSPCs viables et un engraftment et une maintenance des modifications supérieurs dans un modèle murin par rapport aux HSPCs éditées par AAV. Une seconde affiche le 9 octobre 2025 rapporte une analyse complète des cibles hors-target nucléaires pour les éditeurs TALE (TALEB) dans des cellules T primaires, sans biais observé vers des hors-target C→T près des sites CTCF, soutenant la sécurité de TALEB pour l’ingénierie thérapeutique.
Cellectis (NASDAQ: CLLS) wird Daten auf dem ESGCT-Jahreskongress in Sevilla vom 7.-10. Oktober 2025 vorstellen und Fortschritte in der nicht-viralen Gentherapie sowie TALE-Basen-Editoren zeigen.
Wichtige Highlights: Ein Poster am 8. Oktober 2025 berichtet, dass kilobasenlanges zirkuläres einzelsträngiges DNA (CssDNA) hohe Gen-Insertionraten in viable HSPCs ermöglicht und eine bessere Engraftment und Aufrechterhaltung der Edits in einem murinen Modell im Vergleich zu AAV-editierten HSPCs zeigt. Ein zweites Poster am 9. Oktober 2025 berichtet eine umfassende nukleare Off-Target-Analyse für TALE-Basen-Editoren (TALEB) in primären T-Zellen mit keiner beobachteten Bias zugunsten von C→T-Off-Targets in der Nähe von CTCF-Stellen, was die Sicherheit von TALEB für die therapeutische Entwicklung unterstützt.
شركة سيليكتيش (NASDAQ: CLLS) ستعرض بيانات في المؤتمر السنوي ESGCT في إشبيلية في الفترة من 7-10 أكتوبر 2025 مبيّنة التقدمات في العلاج الجيني غير الفيروسي ومحررو TALE القاعديون.
أهم النقاط: ملصق بتاريخ 8 أكتوبر 2025 يُبلغ بأن DNA دائري أحادي السلسلة بطول kilobase (CssDNA) سهل جدًّا عمليات إدراج جيني عالية في خلية السلالات الجذعية الدمويّة الفاعلة HSPCs وبأنه يعزز الالتحام والاحتفاظ بالتعديلات في نموذج حيواني مقارنةً بـ HSPCs المحرَّرة باستخدام AAV. ملصق ثانٍ بتاريخ 9 أكتوبر 2025 يُبلغ عن تحليل شامل للأهداف الثانوية النووية لمحرري TALE القاعديين (TALEB) في خلايا T الأولية، دون وجود تحيز نحو أهداف C إلى T قرب مواقع CTCF، مما يدعم أمان TALEB للهندسة العلاجية.
Cellectis (NASDAQ: CLLS) 将在塞维利亚举行的 ESGCT 年度大会上于 2025 年 10 月 7-10 日 展示在非病毒基因治疗和 TALE 基因编辑器方面的进展。
要点如下：2025 年 10 月 8 日 的一份海报显示，千碱基长的环状单链 DNA（CssDNA）在可生存的 HSPCs 中实现了较高的基因插入率，并相较于 AAV 编辑的 HSPCs，在小鼠模型中具有更好的移植与编辑维持。另一份 2025 年 10 月 9 日 的海报则报道对 TALE 基因编辑器（TALEB）在初级 T 细胞中的核外靶点分析，未观察到在靠近 CTCF 位点处的 C-to-T 攻击靶点偏倚，支持 TALEB 在治疗性工程中的安全性。
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NEW YORK, Oct. 07, 2025 (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 findings highlighting the strong potential of circular single-stranded DNA (CssDNA) as a universal, efficient non-viral template for gene therapy, along with a comprehensive study of TALE base editors (TALEB) off-targets in the nuclear genome, will be presented at the European Society of Cell and Gene Therapy (ESGCT) annual congress, that will take place on October 7-10, 2025, in Sevilla, Spain.
Poster presentation:
Title: Circularization of Single-Stranded DNA Donor Template Unleashes the Power of Non-Viral Gene Delivery for Long-Term HSCs editing
Presenter: Julien Valton, Ph.D., Vice President Gene Therapy at Cellectis
Date/Time: Wednesday, October 8, 2025 from 2:00 p.m. to 3:30 p.m. CET
Poster number: P0439
Over the past decade, non-viral DNA template delivery has been used with engineered nucleases to target single-stranded DNA sequences in hematopoietic stem and progenitor cells (HSPCs).
While developed for gene therapy purposes, so far this method has been restricting to gene corrections. To expand this scope, Cellectis developed an editing process using its gene editing technology and kilobase-long circular single-stranded DNA donor templates.
Research data show that:
- CssDNA editing process achieved high gene insertion frequency in viable HSPCs.
- CssDNA-edited HSPCs show a higher propensity to engraft and maintain gene edits in a murine model than adeno-associated viruses (AAV)-edited HSPCs.
These data highlight the strong potential of CssDNA as a universal and efficient non-viral DNA template for gene therapy applications.
The research was also presented as an oral presentation at the Homology-Directed Repair: The Path Forward Workshop in Sevilla on October 6, 2025.
Poster presentation:
Title: Comprehensive analysis of TALEB off-target editing
Presenter: Maria Feola, Ph.D., Senior Scientist, Team Leader Gene Editing at Cellectis
Date/Time: Thursday, October 9, 2025 from 2:00 p.m. to 3:30 p.m. CET
Poster number: P0506
TALE base editors (TALEB) are fusions of a transcription activator-like effector domain (TALE), split-DddA deaminase halves, and an uracil glycosylase inhibitor (UGI).
These recent additions to the genome editing toolbox can directly edit double strand DNA, converting a cytosine (C) to a thymine (T) through the formation of an uracil (U) intermediate without the need of DNA break. Base editing has great potential in therapeutic applications. However, being able to avoid potential off-target effects is key toward this goal.
To evaluate TALEB safety, Cellectis combined advanced bioinformatic predictions with multiple experimental approaches to investigate potential off-target effects in the nuclear genome of primary T cells.
The study found no evidence of biases towards off-site C-to-T editing at sites flanked by CTCF binding sites, a key DNA-binding protein that regulates genome organization and gene expression at genome wide level.
These results provide a strong framework for the safe development of TALEB in therapeutic cell engineering, supporting their potential for future nuclear and mitochondrial applications.
The poster presentations are now published on Cellectis’ website.
About Cellectis
Cellectis is a clinical-stage biotechnology company using its pioneering gene-editing platform to develop life-saving cell and gene therapies. The company 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 develop gene therapies in other therapeutic indications. With its in-house manufacturing capabilities, Cellectis is one of the few end-to-end gene editing companies that controls the cell and gene therapy value chain from start to finish.
Cellectis’ headquarters are in Paris, France, with locations in New York and Raleigh, NC. Cellectis is listed on the Nasdaq Global Market (ticker: CLLS) and on Euronext Growth (ticker: ALCLS). To find out more, visit www.cellectis.com and follow Cellectis on LinkedIn and X.
TALEN® is a registered trademark owned by Cellectis.
Cautionary Statement
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 “potential”, “can”, “future”. These forward-looking statements are based on our management’s current expectations and assumptions and on information currently available to management. Forward-looking statements include statements regarding the potential of our research and development programs. 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 the sufficiency of cash, cash equivalent and fixed-term deposits to fund our operations, which we refer to as our runway, we note that our operating plans, including product development plans, may change as a result of various factors. Furthermore, many other important factors, including those described in our Annual Report on Form 20-F as amended and in our annual financial report (including the management report) for the year ended December 31, 2024 and subsequent filings Cellectis makes with the Securities Exchange Commission from time to time, which are available on the SEC’s website at www.sec.gov, 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 contacts:
Pascalyne Wilson, Director, Communications, + 33 (0)7 76 99 14 33, media@cellectis.com
Patricia Sosa Navarro, Chief of Staff to the CEO, +33 (0)7 76 77 46 93
Investor Relations contact:
Arthur Stril, Chief Financial Officer & Chief Business Officer, investors@cellectis.com
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FAQ
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What was the main TALEB off-target finding Cellectis presented?
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