Protocol Amendment 1 was developed to address issues raised by the central institutional review board including adding a study drug taper followed by a cosyntropin stimulation test and clarifying parent and/or legal guardian consent. Additional minor changes that do not impact study conduct or subject safety were also made.

Protocol Amendment 2 was developed to address the following considerations:  - In a randomized, double-blind, placebo controlled crossover study in patients ages 5 to 8 with Duchenne muscular dystrophy Beenakker et al, 2005 utilized a 2 month washout period between treatment periods with prednisone and placebo and this washout period appeared to be effective. Subsequently a Medical Advisory Board evaluated the current study design and based on their clinical experience recommended allowing the enrollment of subjects who have not received a therapeutic dose of corticosteroids within 2 months prior to the start of the study. - Subjects with asthma are excluded from the study. Therefore, the concomitant use of inhaled corticosteroids (whose approved indication is for asthma) should not be permitted.

To accommodate subject needs, Protocol Amendment 3 was developed primarily to extend the Open Label Extension Period beyond Week 52 (to continue until the subject chooses to discontinue treatment, the investigator feels that treatment is no longer indicated, MNK-1411 is approved and marketed, or the sponsor ceases development of this compound for Duchenne Muscular Dystrophy [DMD]). Open label visits will continue every 12 weeks, with dispensing of study drug every 12 weeks. Along with this change, text has been added stating that if a subject requires a switch in dose during the Open Label Extension Period (eg, switch to low dose due to being unable to tolerate high dose, or switch to high dose based on increased weight [eg, as subject grows with age]), the investigator should consult with the medical monitor. Since subjects will be participating in the study longer, measurements of height have been added to all study visits. Additional major protocol changes are summarized below: -To accommodate the needs of study sites in Israel, the combination of Sunday and Wednesday has been added as possible visit and/or dosage administration days. -Text has been added specifying that subjects who have a hypersensitivity reaction to the study drug are not required to undergo the 2-week taper, or standard cosyntropin stimulation test (250 μg) at the follow-up visit. -Varicella zoster testing has been added along with an inclusion criterion (Inclusion criterion 6) requiring subjects to test positive prior to study entry (since such infections may be serious in patients who are immunosuppressed). -Pharmacokinetic analysis text has been corrected. -Additional guidance on the administration of motor tests has been provided, along with modification of Exclusion criterion 7 to require that subjects be able to complete the 10 Meter Walk/Run test in 10 seconds or less at the Screening and Baseline Visits.