Dosing stopped

This study is designed to provide 6-months continuous dosing with the study medication, called HT-100, on participants who successfully completed the predecessor study (HALO-DMD-01). The main purpose of this study is to assess chronic safety, tolerability, pharmacodynamic activity (testing the drug's effect on DMD) and population pharmacokinetics (measuring how much drug is in the bloodstream) in participants with a broad spectrum of Duchenne muscular dystrophy (DMD).

Inclusion Criteria:

• Completed both the single ascending dose (SAD) and multiple ascending dose (MAD) phases of predecessor study HALO-DMD-01
• Maintained the same corticosteroid therapy from the predecessor study HALO-DMD-01
• Ability to provide written informed consent
• Ambulatory or non-ambulatory

Exclusion Criteria:

• Recent, substantial change in use of cardiac medications or medications affecting muscle function
• Clinically significant major disease, not related to DMD
• Significantly compromised cardio-respiratory function
• History of severe allergic or anaphylactic reactions
• Prior treatment with another investigational product in past 6 months
• Inability to undergo magnetic resonance imaging (MRI)
• Current drug or alcohol abuse or prior treatment for abuse