A Study to Assess the Safety, Tolerability and Preliminary Efficacy of ASP0367 (MA-0211) in Pediatric Male Participants With Duchenne Muscular Dystrophy (DMD)

This study is comprised of a 4-week pre-treatment screening period, 24-week treatment period and 4-week post-treatment follow-up period. The 24-week treatment period consists of a 12-week double-blind (DB) part and 12-week open-label extension (OLE) part and each part includes a 2 week Low dose Period and a 10-week High-dose Period.