A Study to Assess the Efficacy and Safety of Satralizumab in Duchenne Muscular Dystrophy (DMD)

Inclusion Criteria

• •Signed Informed Consent Form and Signed Assent Form when appropriate
• •Male at birth
• •A definitive diagnosis of DMD prior to screening based on documentation of clinical findings and prior confirmatory genetic testing using a clinical diagnostic genetic test
• •Age ≥ 8 and \< 18 years at the time of signing Informed Consent Form
• •Group 1 participants are required to meet the following criteria:
• •\- Ambulatory (defined as able to walk independently without assistive devices) with a prior history of fractures:
• •1. Prior history of low-trauma fracture defined as: evidence of at least one prevalent vertebral compression fracture of Genant Grade 1 or 2 (or radiographic signs of VF) or history of at least one low-trauma long-bone fracture (upper or lower extremity) OR
• •2. Non-ambulatory, characterized as being non-ambulatory for a minimum of 6 months with onset of non-ambulatory status defined as participant- or caregiver-reported age of continuous wheelchair use approximated to the nearest month, and an North Star Ambulatory Assessment (NSAA) walk score of "0" and inability to perform the 10-Meter Walk/Run (10 MWR) at the baseline visit, with or without fractures
• •Group 2 participants are required to meet the following criteria:
• •* Be fracture naïve, defined as: no history of prior low-trauma fractures before the baseline visit nor any radiological findings indicative of prevalent VF at the screening visit
• •* Be ambulatory defined as able to walk independently without assistive devices
• •* Age ≥ 8 to \< 12 years old at the time of screening
• •Daily oral corticosteroids