This teen once suffered hundreds of seizures a day. Now he can walk thanks to an experimental drug.

Connor Dalby, 17, who could not walk for the first 14 years of his life, is now able to scamper down hallways after an experimental antisense oligonucleotide (ASO) drug reduced his severe, frequent seizures by about 90%. His mother, Kelley Del Real, says the treatment also brought broader changes: calmer behavior, improved sleep, and a better family quality of life. The drug is not immediate and symptoms can return a week or two before the next dose, with benefits lasting roughly five to six weeks. Connor still has developmental and epileptic encephalopathy and cannot speak for himself. Before treatment, he had seizure clusters, at one point leading to temporary hospice status.