Objective: To determine the effects of WVE-004 on C9orf72 G4C2 repeat-containing transcripts, DPR proteins, and C9orf72 protein levels.
Background: A large G4C2 repeat expansion in the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The repeat expansion reduces gene expression and produces pathogenic RNA foci and dipeptide repeat (DPR) proteins. Wave Life Sciences is developing an investigational oligonucleotide, WVE-004, as a potential therapy for ALS and FTD.
Methods: WVE-004 in vitro activity was assessed in patient-derived induced pluripotent stem cell (iPSC) motor neurons under gymnotic conditions. In vivo activity and distribution were assessed in BAC transgenic mice containing the full human C9orf72 gene with repeat expansion. Mice were given intracerebroventricular (ICV) injections of WVE-004 (50 µg) or PBS at day 0 and day 7. Transcript levels were analyzed using qPCR (Taqman assay), poly-GP DPR was measured by Meso Scale Discovery (MSD) assay. Relative C9orf72 protein levels were measured by Wes capillary-based immunoassay, normalized to HPRT. Oligonucleotides in situ were visualized using ViewRNA® (ThermoFisher Scientific).
Results: WVE-004 potently and selectively reduced repeat-containing transcripts in iPSC motor neurons (IC50 201.7 nM). In transgenic mice, WVE-004 reduced repeat-containing transcripts by 60-80% (p<0.0001) in spinal cord and by 40-50% (p<0.0001) in cortex 6 months after dosing. WVE-004 reduced DPRs by 94.2% (p=0.001) and 87% (p<0.0001) in spinal cord and cortex, respectively, at 6 months. Total C9orf72 protein levels were unaffected. Histochemistry demonstrated widespread and sustained WVE-004 distribution in the nuclei of neurons in the brain including spinal cord and cortex.
Conclusion: In transgenic mice, WVE-004 produces substantial reductions in repeat-containing C9orf72 transcripts and DPR proteins without disrupting total protein expression, sustained for at least 6 months. These results support further development of WVE-004 in patients with C9orf72-associated ALS and FTD.
Supported by Wave Life Sciences.