Development of Spherical Nucleic Acid-Based Anti-Sense Oligos for the Therapeutic Treatment of Pediatric Epilepsy Disorders

Heterozygous mutations in KCNQ2, which encodes a pore-forming K+ channel subunit responsible for neuronal M-current, cause neonatal epileptic encephalopathy (EE), a complex disorder presenting with severe early-onset seizures and impaired neurodevelopment1-5. The condition is exceptionally difficult to treat, partially because the effects of KCNQ2 mutations on the development and function of human neurons are unknown. Using induced pluripotent stem cells (iPSCs) and gene editing we have established KCNQ2-EE disease model systems, and measured the functional properties of patient-derived neurons using electrophysiological and optical approaches at single-cell resolution (Simkin et al., BioRxiv; doi: https://doi.org/10.1101/538371). We find that patient-derived excitatory neurons develop intrinsic and network hyperexcitability that mimics epileptic electroencephalogram (EEG) activity. Using heterologous expression systems, we have also found that some disease-causing variants exhibit a dominant negative effect, reducing the channel activity by more than 50%. We hypothesize that deleting the mutant transcript will restore channel activity and alleviate the associated neuronal firing defects. Here, we propose to collaborate with Exicure Inc, to design, screen and test allele-specific antisense oligonucleotides (ASOs), which will target and degrade the mutant KCNQ2 allele. Exicure, is a clinical stage biotechnology company developing spherical nucleic acid (SNA) based ASOs for genetic disorders. We will assess the specificity of ASOs using established digital droplet PCR assays and examine the efficacy of ASOs by measuring their ability to restore the firing activity of patient-derived neurons. If successful, our work will provide a rational therapeutic approach for this devastating disease.