“A clinical benefit of Elevidys, including improved motor function, has not been established.”
Elevidys got accelerated approval for boys aged 4 and 5 because it raises levels of a shortened micro-dystrophin protein. That is a surrogate endpoint. Whether the kids actually walk or move better is still the subject of an ongoing study. The listed side effects include acute liver injury and myocarditis, so families take the risk now and get the evidence later.