Our Genome Engineering Platform

Understanding genetic information

Every cell in the body contains DNA, a molecule that stores the instructions needed for life.

Within DNA are genes, which act as biological blueprints. These genes provide the information cells use to produce proteins, the molecules responsible for carrying out most biological functions. When genetic information is functioning correctly, cells can maintain normal biological activity. When genetic information becomes altered or improperly regulated, disease can emerge.

Understanding, modifying and controlling genetic information is at the foundation of modern genetic medicine.

The genetic origins of disease

Many serious diseases can be traced back to changes in genetic information. In some cases, a gene produces too much of a protein, contributing to disease progression. In others, harmful genetic variants alter how proteins function.

Some diseases arise because specific genes are missing, defective or improperly regulated. Although these diseases may appear very different clinically, they share a common principle: they originate from biological instructions encoded within the genome.

This is why genetic medicines seek to act closer to the root causes of disease.

The Cellectis approach: One disease does not fit one solution

Many genome engineering companies focus on a single modality.At Cellectis, we believe that different diseases require different genomic interventions.

A disease driven by an overactive gene may require a different solution than a disease caused by a pathogenic mutation.

Likewise, a disease driven by abnormal gene regulation may require an intervention that does not alter DNA itself.
Leveraging decades of expertise in programmable DNA-binding proteins, we have built a comprehensive genome engineering platform spanning multiple technologies designed to edit, rewrite, reprogram and regulate genetic information.

Together, these technologies form a differentiated toolbox capable of addressing a broader range of biological mechanisms and th erapeutic opportunities.

Our platform – Edit. Rewrite. Reprogram

TALEN® – Edit

Gene editing

Gene editing enables precise modifications to DNA, the biological code that contains the instructions for life.
TALEN® (Transcription Activator-Like Effector Nucleases) are engineered proteins designed to recognize and bind specific DNA sequences. Once bound to their target, TALEN® creates a highly targeted cut in the DNA, activating the cell’s natural repair mechanisms.

These repair processes can be harnessed to:
• Disrupt disease-causing genes
• Remove unwanted genetic sequences
• Insert new genetic information at defined locations
• Re-engineer cellular functions

Because TALEN® proteins can be programmed to recognize virtually any DNA sequence, they provide a versatile approach to genome engineering across a broad range of therapeutic applications.

For more than two decades, TALEN® has served as the foundation of Cellectis’ genome engineering expertise and remains a core component of the Company’s technology platform.

TALEB – Rewrite

Base editing

Not all diseases require large genomic modifications.

Many disorders result from small changes in DNA, sometimes involving a single genetic letter among billions.
TALEB (TALE Base Editor) is designed to perform precise base editing, allowing targeted DNA letters to be converted without creating a double-strand DNA break.

By combining programmable TALE DNA-binding proteins with a base editing system, TALEB enables highly targeted sequence modifications while preserving the broader genetic structure.

This approach may allow scientists to:
• Correct disease-associated sequence variants
• Introduce beneficial genetic changes
• Reproduce naturally occurring protective mutations
• Modify genes with increased precision

TALEB expands the possibilities of genome engineering by enabling targeted rewriting of genetic information at single-letter resolution.

TALEM – Reprogram

Epigenetic programming & Gene regulation

Genes are not simply turned on or off by their DNA sequence alone.

Cells continuously regulate how genes are expressed through epigenetic mechanisms, molecular signals that control when, where and how strongly genes are activated.
TALEM (TALE Epigenetic Modifier) is designed to precisely influence these regulatory mechanisms without altering the underlying DNA sequence.

Using programmable DNA-binding proteins, TALEM can deliver epigenetic effectors to specific genomic locations, enabling regulation of gene activity and cellular function.

This approach may be used to:
• Reduce excessive gene expression
• Reprogram cellular pathways
• Modulate disease-relevant biological functions

By enabling precise regulation of gene expression, TALEM expands genome engineering beyond editing DNA itself and into the broader regulation and programming of cellular behavior.

Together, TALEN®, TALEB and TALEM provide three complementary ways to modify genetic information: editing DNA, rewriting DNA and programming gene activity. This integrated platform enables Cellectis to pursue a broader range of diseases through the genomic intervention each disease requires.