Adverse event (AE) was defined as any untoward medical occurrence in a participant who received investigational medicinal product (IMP) without regard to possibility of causal relationship with this treatment. TEAEs: AEs that developed or worsened or became serious during on-treatment period which was defined as the period from the time of first dose of study drug (in LTS6050) up to 4 weeks (28 days) after last dose of study drug. Serious adverse event (SAE) was defined as any untoward medical occurrence that resulted in any of the following outcomes: death, life-threatening, required initial or prolonged in-patient hospitalization, persistent or significant disability/incapacity, congenital anomaly/birth defect, or considered as medically important event. Any TEAE included both serious and non-serious AEs.

Safety population: all participants randomized in the LTS6050 study and exposed to IMP during the LTS6050 study treatment period, regardless of the amount of treatment administered. The safety analysis was conducted as the treatment received.

Sustained DP defined as sustained increase of at least 1 point from baseline (EFC6049) expanded disability status scale (EDSS) score (0.5 point for participants with baseline EDSS>5.5) persisting for at least 12 weeks. EDSS: an ordinal scale qualifies disability in participants with MS. EDSS total score range: 0 (normal neurological examination) to 10 (death due to Multiple Sclerosis [MS]). Probability of DP at 12 weeks was estimated using Kaplan-Meier method on time to DP defined as date of first DP minus (-) date of randomization in EFC6049 study +1 day. Participants free of DP (no DP observed on treatment) were censored at the date of last on-treatment EDSS evaluation in LTS6050. Kaplan-Meier method consists in computing probabilities of non-occurrence of event at any observed time of event and multiplying successive probabilities for time ≤t by any earlier computed probabilities to estimate the probability of being event-free for the amount of time t.

Intent-to-treat (ITT) (EFC6049+ LTS6050) population: all participants randomized in both EFC6049 and LTS6050 studies that had at least 1-day IMP exposure during both EFC6049 and LTS6050 studies. Analysis for this outcome measure was performed on the combined data of EFC6049 andLTS6050 study, as pre-specified in the protocol.

Sustained DP was defined as sustained increase of at least 1 point from baseline (EFC6049) EDSS score (0.5 point for participants with baseline EDSS>5.5) persisting for at least 24 weeks. EDSS: an ordinal scale qualifies disability in participants with MS. EDSS total score range: 0 (normal neurological examination) to 10 (death due to MS). Probability of DP at 24 weeks was estimated using Kaplan-Meier method on time to DP defined as date of first DP minus (-) date of randomization in EFC6049 study +1 day. Participants free of DP (no DP observed on treatment) were censored at the date of last on-treatment EDSS evaluation in LTS6050. Kaplan-Meier method consists in computing probabilities of non-occurrence of event at any observed time of event and multiplying successive probabilities for time ≤t by any earlier computed probabilities to estimate the probability of being event-free for the amount of time t.

Intent-to-treat (ITT) (EFC6049+ LTS6050) population: all participants randomized in both EFC6049 and LTS6050 studies that had at least 1-day IMP exposure during both EFC6049 and LTS6050 studies. Analysis for this outcome measure was performed on the combined data of EFC6049 andLTS6050 study, as pre-specified in the protocol.

Sustained DP was defined as sustained increase of at least 1 point from baseline (EFC6049) EDSS score (0.5 point for participants with baseline EDSS>5.5) persisting for at least 12 weeks and 24 weeks. EDSS is an ordinal scale in half-point increments that qualifies disability in participants with MS. It consists of 8 ordinal rating scales assessing seven functional systems (visual, brainstem, pyramidal, cerebellar, sensory, bowel/bladder, cerebral) as well as ambulation. EDSS total score ranges from 0 (normal neurological examination) to 10 (death due to MS), where higher scores indicates worse neurological function. Percentage of participants who were considered as free of disability progression confirmed after 12 week sustained progression and 24 week sustained progression were reported. Analysis for this outcome measure was performed on combined data of EFC6049 and LTS6050 study, as pre-specified in protocol.

Intent-to-treat (ITT) (EFC6049 [NCT00134563] + LTS6050) population.

ARR was obtained from total number of confirmed relapses that occurred during treatment period divided by sum of treatment durations in LTS6050 study only. Each episode of relapse - appearance, or worsening of a clinical symptom that was stable for at least 30 days, that persisted for a minimum of 24 hours in the absence of fever was to be confirmed by an increase in EDSS score or Functional System (FS) scores. EDSS: an ordinal scale qualifies disability. EDSS total score range: 0 (normal neurological examination) to 10 (death due to MS). FSS: to assess the neurological function. Total score range: 0 (normal) - 6(worse), higher scores = worse neurological function. To account for the different treatment duration among participants, a Poisson regression model with robust error variance was used (total number of confirmed relapses as response variable; log transformed treatment duration as "offset" variable; treatment group, region of enrolment and baseline EDSS stratum as covariates).

ITT(LTS6050) population: all participants who were randomized in the LTS6050 study and had at least 1-day IMP exposure during the LTS6050 study.

BOD was assessed by cerebral MRI and defined as the total volume of all abnormal brain tissue (calculated as the sum of the total volume of T2-lesion component and T1-hypointense lesion component).

ITT (LTS6050 population). Number of participants analyzed=participants with available data for this outcome measure.