Cellectis Presents Data on Two TALEN®-based Gene Therapy Preclinical Programs for Patients with Sickle Cell Disease and Mucopolysaccharidosis type I at ESGCT 2022

New York, NY – October 11, 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 that the Company will present both an oral and poster at the European Society of Gene and Cell Therapy’s (ESGCT) 29th Congress, to be held in Edinburgh from October 11-14, 2022.

Arianna Moiani, Ph.D., Senior Scientist & Team Leader Innovation Gene Therapy, will give an oral presentation on encouraging pre-clinical data that leverages TALEN® gene editing technology to develop a hematopoietic stem and progenitor cell (HSPCs)-based gene therapy to treat sickle cell disease.

Eduardo Seclen, Ph.D., Senior Scientist & Team Leader, Gene Editing, will present a poster illustrating a TALEN®-based gene editing approach that reprograms HSPCs to secrete alpha-L-iduronidase (IDUA), a therapeutic enzyme missing in Mucopolysaccharidosis type I (MPS-I).

“The pre-clinical data presented at ESGCT further demonstrate our ability to leverage TALEN® gene editing technology to potentially address genetic diseases, namely, sickle cell disease and lysosomal storage diseases. By correcting a faulty mutation or inserting a corrected gene at the HSPC level, we aim to provide a lifelong supply of healthy cells in a single intervention," said Philippe Duchateau, Ph.D., Chief Scientific Officer at Cellectis. “These new milestones bring us one step closer to our goal: providing a cure to patients that have failed to respond to standard therapy.”

Presentation details

Pre-clinical data presentation on a non-viral DNA delivery associated with TALEN® gene editing that leads to highly efficient correction of sickle cell mutation in long-term repopulating hematopoietic stem cells

Sickle cell disease stems from a single point mutation in the HBB gene which results in sickle hemoglobin.

Cellectis leveraged its TALEN® technology to develop a gene editing process that leads to highly efficient HBB gene correction via homology directed repair, while mitigating potential risks associated to HBB gene knock-out.

Overall, these results show that non-viral DNA delivery associated with TALEN® gene editing reduces the toxicity usually observed with viral DNA delivery and allows high levels of HBB gene correction in long-term repopulating hematopoietic stem cells.

The oral presentation titled “Non-viral DNA delivery associated to TALEN® gene editing leads to highly efficient correction of sickle cell mutation in long-term repopulating hematopoietic stem cells”, will be made on Thursday, October 13th, 8:30 AM-10:45 AM BST by Arianna Moiani, Ph.D., Senior Scientist & Team Leader Innovation Gene Therapy. The presentation can be found on the Cellectis website on the day of the presentation.

Presentation details

Pre-clinical data presentation on TALEN®-mediated engineering of HSPC that enables systemic delivery of IDUA

Mucopolysaccharidosis type I (MPS-I) is caused by deficiencies in the alpha-L-iduronidase (IDUA) gene and it is associated with severe morbidity representing a significant unmet medical need.

Cellectis established a TALEN®-based ex vivo gene editing protocol to insert an IDUA-expression cassette into a specific locus of HSPC.

Editing rates in vivo were 6-9% sixteen weeks after injection, depending on the tissue analyzed (blood, spleen, bone marrow). Lastly, 8.3% of human cells were edited in the brain compartment.

Cellectis established a safe TALEN®-based gene editing protocol procuring IDUA-edited HSPCs able to engraft, differentiate into multiple lineages and reach multiple tissues, including the brain.

The poster presentation titled “TALEN®-mediated engineering of HSPC enables systemic delivery of IDUA”, will be made on Thursday, October 13th, 5:30 PM - 7:15 PM BST by Eduardo Seclen, Ph.D., Senior Scientist & Team Leader, Gene Editing, and can be found on Cellectis website.