AAV-dCas9 Epigenetic Editing for CDKL5 Deficiency Disorder

Under the current DISC2 award, we have optimized and validated a dual AAV approach to deliver novel epigenetic editors to reactive the healthy, silent copy of CDKL5 to treat girls with CDKL5 deficiency disorder. We have completed rescue studies using patient-derived brain organoids in which we can see approximately 70% rescue. This level of rescue equated to recovery of neuronal function as measured using microelectrode arrays. Additionally, we validated our surrogate mouse therapeutic in a transgenic mouse model of the disease. Following AAV9 delivery into the cerebral spinal fluid space, we were able to see near complete rescue of motor and cognitive performance. This data will be used for future grant applications to fund the translation of our approach towards an IND application to the FDA.

Through the use of the DISC2 mechanism we have validated the approach for targeted reactivation of CDKL5 from the inactive X chromosome across patient-derived induced pluripotent stem cell models and transgenic mice. We have demonstrated that reactivation of CDKL5 results in restoration of substrate activity and potentially in rescuing neuronal function in patient-derived organoids and neurons. We have also demonstrated that when using a mouse surrogate therapeutic that we can rescue multiple functional domains in the mice. This data is supported by molecular analysis demonstrating significant increases in the number of Cdkl5 positive neurons in the brain, significant increases in the amount of Cdkl5 protein in the brain, and significant rescue of a well-known substrate of Cdkl5. Taken together, this data demonstrates that this approach can rescue CDKL5 function across multiple model systems.