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

This Phase IIb study is a randomized, double-blind, parallel group, placebo and
active-controlled study to evaluate the efficacy, safety, PD, and population PK of vamorolone
administered orally at daily doses of 2.0 mg/kg and 6.0 mg/kg versus prednisone 0.75
mg/kg/day and placebo over a Treatment Period of 24 weeks, and to evaluate persistence of
effect over a Treatment Period of 48 weeks in ambulant boys ages 4 to <7 years with DMD.

The study is comprised of a 5-week Pretreatment Screening Period, a 1-day Pretreatment
Baseline Period, a 24 week Treatment Period #1 (Weeks 1-24), a 4 week Transition Period
(Weeks 25-28), a 20-week Treatment Period #2 (Weeks 28+ 1 day to 48), and a 4-week
Dose-tapering Period (Weeks 49-52).

Subjects will be randomized to one of six treatment groups in a 2:2:1:1:1:1 ratio, where the
two prednisone groups in Treatment Period #1 (Groups 3 and 4) will be combined and the two
placebo groups in Treatment Period #1 (Groups 5 and 6) will be combined, effectively
resulting in a 1:1:1:1 randomization (vamorolone 2.0 mg/kg/day : vamorolone 6.0 mg/kg/day :
prednisone 0.75 mg/kg/day : placebo) for Treatment Period #1.

Subjects will be stratified based on age at study entry (<6 vs. ≥ 6 years). During the 4-week
Transition Period between Treatment Period #1 and Treatment Period #2, all subjects will
continue on the same oral suspension (vamorolone 2.0 mg/kg or 6.0 mg/kg, or matching placebo)
they received during Treatment Period #1 and all subjects will have their tablet dose tapered
to zero. Thus, subjects randomized to receive vamorolone during Treatment Period #1 (Groups 1
and 2) will continue to receive vamorolone at the same dose, while subjects randomized to
receive prednisone will have their dose tapered to zero, and subjects randomized to placebo
will continue to receive placebo.

A total of approximately 120 subjects will be randomized (2:2:1:1:1:1) to treatment.

The prednisone group will be used as an active control comparison for safety and efficacy
endpoints as requested by the European Medicines Agency (EMA). The placebo group will be used
as comparator for efficacy endpoints (superiority model) as requested by the EMA and Food and
Drug Administration (FDA) protocol advisory board.

At the end of the Treatment Period #2, subjects will be given the option of enrolling into a
long-term extension study (VBP15-005) or to transition to standard of care treatment for DMD
(may include glucocorticoids). Subjects completing VBP15-004 and enrolling directly into
VBP15 005 will not need to taper their vamorolone dose prior to enrollment into VBP15 005.
All other subjects will begin a 4 week double blind Dose tapering Period during which the
dose of study medication will be progressively reduced and discontinued.

Inclusion Criteria:

1. Subject's parent(s) or legal guardian(s) has (have) provided written informed consent
and Health Insurance Portability and Accountability Act (HIPAA) authorization, where
applicable, prior to any study-related procedures; participants will be asked to give
written or verbal assent according to local requirements

2. Subject has a centrally confirmed (by TRiNDS central genetic counselor[s]) diagnosis
of DMD as defined as:

- Dystrophin immunofluorescence and/or immunoblot showing complete dystrophin
deficiency, and clinical picture consistent with typical DMD, OR

- Identifiable mutation within the DMD gene (deletion/duplication of one or more
exons), where reading frame can be predicted as 'out-of-frame,' and clinical
picture consistent with typical DMD, OR

- Complete dystrophin gene sequencing showing an alteration (point mutation,
duplication, other) that is expected to preclude production of the dystrophin
protein (i.e., nonsense mutation, deletion/duplication leading to a downstream
stop codon), with a clinical picture consistent with typical DMD;

3. Subject is ≥ 4 years and <7 years of age at time of enrollment in the study;

4. Subject weighs >13.0 kg and ≤ 39.9 kg at the Screening Visit;

5. Subject is able to walk independently without assistive devices;

6. Subject is able to complete the Time to Stand Test (TTSTAND) without assistance in <10
seconds, as assessed at the Screening Visit;

7. Clinical laboratory test results are within the normal range at the Screening Visit,
or if abnormal, are not clinically significant, in the opinion of the Investigator.
[Note: Serum gamma glutamyl transferase (GGT), creatinine, and total bilirubin all
must be ≤ upper limit of the normal range at the Screening Visit];

8. Subject has evidence of chicken pox immunity as determined by presence of IgG
antibodies to varicella, as documented by a positive test result from the local
laboratory at the Screening Visit;

9. Subject is able to swallow tablets, as confirmed by successful test swallowing of
placebo tablets during the Screening Period; and

10. Subject and parent(s)/guardian(s) are willing and able to comply with scheduled
visits, study drug administration plan, and study procedures.

Exclusion Criteria:

1. Subject has current or history of major renal or hepatic impairment, diabetes mellitus
or immunosuppression;

2. Subject has current or history of chronic systemic fungal or viral infections;

3. Subject has had an acute illness within 4 weeks prior to the first dose of study
medication;

4. Subject has used mineralocorticoid receptor agents, such as spironolactone,
eplerenone, canrenone (canrenoate potassium), prorenone (prorenoate potassium),
mexrenone (mexrenoate potassium) within 4 weeks prior to the first dose of study
medication;

5. Subject has a history of primary hyperaldosteronism;

6. Subject has evidence of symptomatic cardiomyopathy [Note: Asymptomatic cardiac
abnormality on investigation would not be exclusionary];

7. Subject is currently being treated or has received previous treatment with oral
glucocorticoids or other immunosuppressive agents [Notes: Past transient use of oral
or inhaled glucocorticoids or other oral immunosuppressive agents for indication other
than DMD for no longer than 3 months cumulative, with last use at least 3 months (or
last use at least one month prior for inhaled glucocorticoids) prior to first dose of
study medication, will be considered for eligibility on a case-by-case basis. Inhaled
and/or topical glucocorticoids prescribed for an indication other than DMD are
permitted if last use is at least 4 weeks prior to first dose of study medication or
are administered at stable dose beginning at least 4 weeks prior to first dose of
study medication, and are anticipated to be used at the stable dose regimen for the
duration of the study];

8. Subject has an allergy or hypersensitivity to the study medication or to any of its
constituents;

9. Subject has used idebenone within 4 weeks prior to the first dose of study medication;

10. Subject has severe behavioral or cognitive problems that preclude participation in the
study, in the opinion of the Investigator;

11. Subject has previous or ongoing medical condition, medical history, physical findings
or laboratory abnormalities that could affect safety, make it unlikely that treatment
and follow-up will be correctly completed or impair the assessment of study results,
in the opinion of the Investigator;

12. Subject is taking (or has taken within 4 weeks prior to the first dose of study
medication) herbal remedies and supplements which can impact muscle strength and
function (e.g., Co-enzyme Q10, creatine, proglandine, etc);

13. Subject is taking (or has taken within 3 months prior to the first dose of study
medication) any medication indicated for DMD, including Exondys51 and Translarna;

14. Subject is currently taking any other investigational drug or has taken any other
investigational drug within 3 months prior to the first dose of study medication; or

15. Subject has previously been enrolled in the study.

Note: Any parameter/test may be repeated at the Investigator's discretion during Screening
to determine reproducibility. In addition, subjects may be rescreened if ineligible due to
a transient condition which would prevent the subject from participating, such as an upper
respiratory tract infection or injury, or if ineligible due to negative anti-varicella IgG
antibody test result.