It included following changes: - Deleted exploratory endpoint: Effect of concomitant corticosteroid treatment on LVEF and cardiac fibrosis. - Inclusion criteria was updated to specify wheelchair dependent for <5 years. - Inclusion criteria was updated to increased length of stable regimen of heart failure cardiac medications prior to screening from 6 weeks to 3 months. - Exclusion criteria was updated to mention the need for intravenous diuretics or inotropic support increased from within 6 weeks to at least 3 months prior to screening; and hospitalization for a heart failure exacerbation or arrhythmia increased from last 6 weeks to last 3 months. - Deleted inclusion criteria for the option of no corticosteroid use for at least 6 months prior to screening and throughout the study participation. - Mandated stable treatment with corticosteroids at baseline. - Changed duration of follow-up period from 6 weeks to 10 weeks. - Allowed use of deflazacort, if regarded by the principal investigator as standard of care.

It included following changes: - Replaced forearm muscle MRI with upper arm (bicep) muscle MRI. - Revised Inclusion criterion 8 to allow only enrollment of participants with a ppFVC ≥50. - Dosing based on body weight measured at screening and every 3 months thereafter. - Safety follow-up period reduced from 10 weeks to 4 weeks after the last dose of study drug. - Infusion rate of FG-3019 not to exceed 150 cubic centimeters (cc)/hour. Adjustments to lower infusion rate allowed per investigator’s clinical judgment. - Clarified requirement for local safety labs (including hematocrit) to be drawn prior to conduct of MRIs. - Added stipulation that home health care may be considered for administration of future pamrevlumab infusions during the conduct of the study.

It included following changes: - Replacement of FG-3019 with pamrevlumab. - Decreased study duration from 104 weeks to 52 weeks with option to continue an additional 26 weeks (78 weeks total) for participants who achieve a ≤5% decline from baseline in ppFVC by Week 52. - Updated time on study to reflect weeks vs years (ie, change from 1 year to 52 weeks). - Removed Interim Analysis at Week 52. - Deleted Inclusion criterion: Wheelchair dependency <5 years. - Revised Inclusion criterion to only allow enrollment of participants with a ppFVC between 40 and 90, inclusive. Deleted “estimated annual decline of FVC (% predicted) of ≥5% based upon at least 2 PFTs done in the previous 18 months, in addition to the screening FVC” from Inclusion criterion. Changed criteria to “At least one historical FVC % predicted value within 18 months of baseline”. - Modified Inclusion criterion to “Participants currently receiving heart failure cardiac medications (for example, angiotensin converting enzyme inhibitors, angiotensin-receptor blockers, and beta-blockers) must achieve a stable regimen for at least 3 months prior to screening”. - Modified Exclusion criterion to update time frame of anticipated spine surgery from 2 years to 78 weeks. - Modified Exclusion criterion to clarify that the use of another investigational drug or another approved product for DMD (for example, eteplirsen) within 28 days or 5 half-lives of the product, whichever was longer, prior to first Screening Visit, with the exception of deflazacort, was exclusionary. Allowed use of deflazacort if regarded by the principal investigator as standard of care. - Clarified that any approved product for DMD (for example, eteplirsen) during study treatment was prohibited.

It included following changes: -Sample size changed to reflect that study may enroll up to 32 participants dependent on outcome of interim analysis. - Extended treatment duration from 52 weeks plus extension to 104 weeks; removed extension and added interim analysis. - Changed primary endpoint to annual change in ppFVC during treatment. - Changed Exclusion criteria to reflect increased treatment duration. - Amended language to reflect that only the first infusion was based on the screening weight. - Updated to reflect that infusion reactions are considered an identified risk of pamrevlumab administration and deleted that they did not recur with readministration.

It included following changes: - Primary efficacy endpoint changed from “annual change in ppFVC during treatment with pamrevlumab” to “annual change from baseline to Week 104 in ppFVC during treatment with pamrevlumab”. - Removed sentence about analysis method (“t-test”) for primary efficacy endpoint. - Modified number of participants required for interim analysis from “at least 12” to “at least 10 to 12”. - Clarified PK sample time-point collection. - Extended treatment duration from 104 weeks to 156 weeks with exploratory analyses at Week 156.

It included following changes: - Addition of Appendix: OLE for all participants who completed 104 weeks of treatment on the main study and completed end of treatment (EOT). Modifications made in main study to address addition of Appendix. - Added Respiratory Muscles and Diaphragm MRI in OLE.