Epigenetic silencing of the C9orf72 hexanucleotide repeat expansion as a therapeutic strategy

• Applicant: Professor Dr. Jared Sterneckert
• Subject Area: Molecular and Cellular Neurology and Neuropathology ; Experimental Models for the Understanding of Nervous System Diseases
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573347400

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are devastating neurodegenerative diseases. As the number of older Europeans increases, the incidence of ALS and FTD cases are expected to significantly increase. New therapeutics are urgently needed. The most prevalent known genetic cause of ALS and FTD is a GGGGCC (G4C2) hexanucleotide repeat expansion (HRE) within the first intron of the gene C9orf72. Thus, therapeutics designed specifically against HRE would benefit a large number of patients. Although antisense oligonucleotides (ASOs) are the most actively investigated therapeutic strategy for C9orf72-ALS, two different ASOs recently failed clinical testing and even exacerbated pathogenesis, suggesting that a new strategy is needed. In addition, ASOs target only one RNA strand – typically the sense strand, leaving the antisense RNA transcript, which induces ALS pathology, unaltered. Also, ASOs have been associated with toxicity, including inflammatory effects, nephrotoxicity, and thrombocytopenia. Multiple lines of evidence suggest that epigenetic silencing of the C9orf72 promoter could be an effective therapeutic strategy. In approximately 30% of ALS as well as FTD cases, mutant C9orf72 is hyper-methylated, and is associated with epigenetic silencing of mutant C9orf72. This methylation driven silencing is associated with reduced pathology, reduced brain atrophy, later age at death and longer disease duration. Thus, we propose to develop a gene therapeutic that epigenetically silences mutant C9orf72. Gene therapeutics using adeno-associated virus (AAV) have shown tremendous promise in pre-clinical and clinical testing for motor neuron diseases. A single administration of AAV to the central nervous system showed therapeutic effects over 250 days later in mice. Here, we propose developing an AAV therapeutic vector that epigenetically silences mutant C9orf72 for a long period of time after a single administration. We will develop this vector using human motor neurons differentiated from induced pluripotent stem cells. A mouse model will be characterized for subsequent testing in vivo. Since AAV is now clinically approved for one motor neuron disorder and multiple companies produce AAV vectors under GMP conditions, our new AAV vectors could be rapidly translated into clinical testing.

• DFG Programme: Research Grants