This study focuses on children with KCNT1-related Developmental and Epileptic Encephalopathy, a rare genetic condition that causes severe epilepsy and developmental delays in young children. The study will test a new medication called S230815, which is given through an injection into the spinal fluid. This medication is designed to target a specific gene called KCNT1 that is involved in causing this type of epilepsy.

The purpose of this research is to determine if the medication is safe and how well children’s bodies process it. The study will involve multiple doses of the medication, with the amount being gradually increased over time. The medication is being tested for the first time in humans, specifically in children between 2 and 12 years of age who have confirmed genetic changes in the KCNT1 gene.

During the study, participants will receive the medication through intrathecal injections (delivered directly into the fluid surrounding the spinal cord). The medication is an antisense oligonucleotide, which is a type of drug that can reduce the activity of specific genes. Throughout the study, doctors will monitor how the children respond to the treatment and check for any side effects.