Phase III Study With Idebenone in Patients With Duchenne Muscular Dystrophy (SIDEROS-E)

The study will be an open-label, single-group, multi-center extension study in patients with
DMD receiving glucocorticoid steroids who participated in the SIDEROS study and who meet all
the inclusion criteria and none of the exclusion criteria for this extension study.

The study consists of 4 study visits scheduled every 6 months (Visit 1/Baseline, Visit 2/Week
26, Visit 3/ Week 52 and Visit 4/ Week 78). Visit 8/Week 78 in SIDEROS study is also
SIDEROS-E Visit 1/Baseline.

Inclusion Criteria:

1. Completion of the SIDEROS study at Visit 8/ Week 78

2. Signed and dated Informed Consent Form for SIDEROS-E

Exclusion Criteria:

1. Patients who discontinued SIDEROS study prematurely (i.e. did not attend all visits
from V1 to V8)

2. Safety, tolerability or other issues arising during the course of the SIDEROS study
which in the opinion of the Investigator may put the patient at significant risk or
may interfere significantly with the patient's participation in the SIDEROS-E study

3. Use of any investigational drug other than the study medication