P25

Development of a gene therapy based on SMaRT technology for Huntington's disease

L Heng(1) N Dufour(1) N Souedet(1) D Fourmy(1) F Ducongé(1) A P Bemelmans(1)

1: MIRCen, CEA

Huntington’s disease is a genetic neurodegenerative disorder characterized by motor, cognitive and psychiatric symptoms that slowly but inevitably lead to the patient’s death. It is caused by an abnormal expansion of a CAG repeat in the HTT gene, leading to toxic protein production and striatal neuron degeneration. There is currently no cure, but gene therapy has emerged as a promising option.

We are exploring SMaRT (Spliceosome-mediated RNA trans-splicing) technology, which replaces mutated exons in pre-mRNA using an artificial RNA called PTM (pre-RNA Trans-splicing Molecule). PTMs compete with endogenous splice sites to generate hybrid, mutation-free mRNA. A major challenge is ensuring efficient trans-splicing by optimizing the PTM’s binding domain (BD), which targets the pre-mRNA intronic sequence.

To address this, we are developing a high-throughput strategy for BD selection. We generate reporter cell lines with fluorescent markers to quantify trans-splicing. BD libraries are screened, successful trans-splicing events are sorted by FACS and analyzed using next-generation sequencing (NGS) to identify the most promising BD candidates. The BD candidates will then be evaluated to select the optimal PTMs that may provide therapeutic benefit for Huntington’s disease.

SMaRT technology has shown promise in other genetic disorders like retinitis pigmentosa and epidermolysis bullosa. With further optimization, it could offer a novel therapeutic approach for Huntington’s disease.