Variant-selective stereopure oligonucleotides protect against pathologies associated with C9orf72-repeat expansion in preclinical models

A large G(4)C(2)-repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Neuronal degeneration associated with this expansion arises from a loss of C9orf72 protein, the accumulation of RNA foci, the expression of dipeptide repeat (DPR) proteins, or all these factors. We report the discovery of a new targeting sequence that is common to all C9orf72 transcripts but enables preferential knockdown of repeat-containing transcripts in multiple cellular models and C9BAC transgenic mice. We optimize stereopure oligonucleotides that act through this site, and we demonstrate that their preferential activity depends on both backbone stereochemistry and asymmetric wing design. In mice, stereopure oligonucleotides produce durable depletion of pathogenic signatures without disrupting protein expression. These oligonucleotides selectively protect motor neurons harboring C9orf72-expansion mutation from glutamate-induced toxicity. We hypothesize that targeting C9orf72 with stereopure oligonucleotides may be a viable therapeutic approach for the treatment of C9orf72-associated neurodegenerative disorders.C9orf72 expansion mutations are the most common genetic cause of ALS and FTD, which have limited therapies. The authors generate stereopure oligonucleotides that selectively deplete expansion-containing transcripts and protect against expansion-associated pathologies in preclinical models.

Automated summary

C9orf72 expansion mutations, the common genetic cause of ALS and FTD, have limited treatment options. Scientists have developed stereopure oligonucleotides that selectively deplete expansion-containing transcripts and have shown efficacy in preclinical models.