Relapses were monitored throughout the study. During the PC Period, two neurologists/physicians assessed subjects' general medical and neurological evaluations separately. A relapse was defined as the appearance of 1+ new neurological abnormalities or the reappearance of 1+ previously observed neurological abnormalities lasting >= 48 hours and immediately preceded by an improving neurological state of at >=30 days from onset of previous relapse. An event was counted as a relapse only when the subject's symptoms were accompanied by observed objective neurological changes, consistent with >= one of the following: - An increase of >= 0.5 in the Expanded Disability Status Scale (EDSS) score as compared to previous evaluation. - An increase of one grade in the actual score of >=2 of the 7 functional systems (FS), as compared to previous evaluation. - An increase of 2 grades in the actual score of one FS as compared to the previous evaluation. Adjusted mean values are displayed.

Intent To Treat (ITT) Analysis Population

T2 lesions are hyperintense brain lesions that show on magnetic resonance imaging (MRI) and are associated with multiple sclerosis. The cumulative number of T2 lesions at Months 6 and 12 that are new or enlarged as compared to the baseline MRI are offered. Note that the two timeframes (Months 6 and 12) are combined. Adjusted mean is based on negative binomial regression, adjusted for baseline number of T2 lesions and country or geographical region as covariates.

ITT. When a subject had both Month 6 and Month 12 scans missing, the subject was excluded from the analysis. When the Month 12 scan was missing, data from Month 6 was used and an offset of log (0.5) introduced. When the Month 6 scan was missing, data from Month 12 was used with an offset of 0.

The cumulative number of gadolinium (Gd)-enhanced lesions on T1-weighted images at Months 6 and 12 as compared to the baseline MRI are offered. Note that the two timeframes (Months 6 and 12) are combined. Adjusted mean is based on negative binomial regression with an "offset" employing the log of the proportion of the number of the available post-baseline scans to adjust for missing MRI scans (if any), adjusted for baseline number of enhancing lesions on T1-weighted images and country or geographical region as covariates.

ITT. When a subject had both Month 6 and Month 12 scans missing, the subject was excluded from the analysis.

The analysis of brain atrophy as defined by the percentage change in normalized brain volume from baseline to Month 12 was based on the outcome of a contrast (GA 40 mg TIW vs. placebo) derived from a baseline-adjusted ANCOVA. In addition to the treatment group, the model included the following covariates: - SIENAX normalized brain volume at baseline. - The number of enhancing lesions on T1-weighted images at baseline. - country or geographical region.

Sienax estimates total brain tissue volume, from a single image, normalised for skull size.

ITT population of participants who had SIENEX brain volume estimates at both baseline and Month 12.

The annualized relapse rate (ARR) was calculated for the study by dividing the cumulative number of confirmed relapses by the number of person-years of exposure to treatment. The analysis of the annualized relapse rate is based on estimating a contrast (early start vs delayed start) derived from a baseline-adjusted, Negative Binomial Regression model to the number of confirmed relapses observed during study (post randomization) with an "offset" based on the log of exposure to treatment.

ITT

All data accumulated from screening, the PC Treatment period up to the end of the Open Label (OL) period are combined and referred to as the Long Term Period. T2 lesions are hyperintense brain lesions that show on magnetic resonance imaging (MRI) and are associated with multiple sclerosis. The number of T2 lesions at Months 6, 12 and 36 that are new or enlarged as compared to the baseline MRI are offered. Adjusted mean is based on negative binomial regression, adjusted for baseline number of T2 lesions and country or geographical region as covariates. An "offset" employing the log of the proportion of the number of the available post-placebo-controlled baseline (PCBL) scans was used to adjust for missing MRI scans.

ITT population of participants with MRIs at both baseline and the designated timeframes.

All data accumulated from screening, the PC Treatment period up to the end of the Open Label (OL) period are combined and referred to as the Long Term Period. The cumulative number of gadolinium (Gd)-enhanced lesions on T1-weighted images at Months 6, 12 and 36 as compared to the baseline MRI are offered. Adjusted mean is based on negative binomial regression The model was fit using an autoregressive covariance structure. Covariates used: number of enhancing lesions on T1-weighted images at placebo-controlled baseline and country or geographical region. The cumulative number is derived from all the data points before it. For example, if the participant skipped one time point in between the baseline and 36 months, then it cannot be calculated.

ITT population of participants with MRIs at both baseline and the designated timeframes, inclusive of the proceeding post-baseline timeframes.

The analysis of brain atrophy as defined by the percentage change in brain volume from baseline to Months 6, 12 and 36 was performed using mixed model for repeated measures (MMRM) with SIENAX normalized brain volume at baseline, number of Gd-enhancing lesions at baseline, and country or geographical region as fixed effects.

Sienax estimates total brain tissue volume, from a single image, normalised for skull size.

ITT population of participants with SIENEX brain scans at both baseline and the designated timeframes.

Adverse events (AEs) summarized in this table are those that began or worsened after treatment with study drug (treatment-emergent AEs). An adverse event was defined in the protocol as any untoward medical occurrence that develops or worsens in severity during the conduct of a clinical study and does not necessarily have a causal relationship to the study drug. Severity was rated by the investigator on a scale of mild, moderate and severe, with severe= an AE which prevents normal daily activities. Relation of AE to treatment was determined by the investigator. Serious AEs include death, a life-threatening adverse event, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, a congenital anomaly or birth defect, OR an important medical event that jeopardized the patient and required medical intervention to prevent the previously listed serious outcomes.

Glatiramer Acetate (GA) - Treated Analysis Set The GA-Treated analysis set includes all subjects randomized into the study and treated with at least 1 dose of GA at any time during the study. Analyses includes data collected for these subjects from the first time GA was administered.