A Phase III Double-blind Study With Idebenone in Patients With Duchenne Muscular Dystrophy (DMD) Taking Glucocorticoid Steroids

The SIDEROS trial is a randomized, placebo controlled, parallel group study of the efficacy of idebenone in delaying the loss of respiratory function, whilst also monitoring safety and tolerability of idebenone in at least 266 DMD patients taking stable dose of concomitant glucocorticoid steroids. The study treatment period will be 18 months/ 78 weeks and the idebenone dose will be 900 mg/day. Participants can use deflazacort or prednisolone and be on any dose regimen. Since glucocorticoid steroids are widely used in ambulant boys from an early age until late into teenage and even adult years, this study will not take age and ambulatory status into account and will only exclude patients that need daytime ventilator assistance. The schedule of assessments will include a Screening Visit and up to 9 protocol visits, including a Follow-up Visit. A Screening Visit will take place a maximum of 4 weeks prior to the Baseline Visit (Visit 1, study day -1). Beginning at Baseline, the patient will receive study medication to be taken at home, and will undergo regular assessments in the clinic throughout the study period until Visit 8 at Week 78 at which time the study will be completed and medication discontinued. All patients completing Visit 8/Week 78, and considered eligible by the Investigator will be able to participate in an open-label extension study (SIDEROS-E) and will continue to receive idebenone until idebenone is commercially available for patients included in the study or SIDEROS-E is terminated by the Sponsor, whichever occurs first. The duration of the SIDEROS-E study will be defined in a separate protocol. For all patients not participating in the extension study (SIDEROS-E), a Follow-up Visit (Visit 9/Follow-up Visit) will take place 4 weeks after end of Treatment at Visit 8/Week 78 or after premature discontinuation of study medication. Each hospital visit will include efficacy assessments (respiratory function assessed by hospital-based spirometry, oxygen saturation, end-tidal CO2) and safety assessments (adverse events, concomitant medication, physical examination, vital signs, safety laboratory evaluations). In addition, respiratory function will be assessed weekly at home with a hand-held device in order to closely monitor respiratory function between hospital visits. The study medication, all medical procedures and laboratory testing, and the visits to the study centre are free of charge. In addition the patients will receive a travel allowance to cover reasonable expenses to and from the study centre. Participants will not otherwise be compensated for this study.