This study is evaluating the long-term safety and tolerability of a new steroid-like intervention called vamorolone in boys with DMD ages 4 to less than 7 years old. Participants who have completed the Phase IIa study (described above) are eligible to enroll. To learn more about the study eligibility and participating sites please visit:https://clinicaltrials.gov/ct2/show/NCT02760277 or contact us at info@trinds.com.