Time to CDP was defined as the time to a sustained increase in Kurtzke's Expanded Disability Status Scale (EDSS) score of at least 1 point if baseline EDSS score was less than or equal to 5.0, or at least 0.5 point if the baseline EDSS score was 5.5, over a period of at least three months. EDSS assesses disability in 8 functional systems with an overall score ranging from 0 (normal) to 10 (death due to multiple sclerosis [MS]). Data is presented as distribution of CDP (number of participants with CDP) sustained for 3 months.

ITT analysis set included all randomized participants.

Brain atrophy was defined by the percent change in brain volume from baseline to Month 15. For participants who prematurely discontinued treatment or completed the placebo-controlled phase before Month 15, the last available measurement was used, provided it was performed at least 9 months following the initiation of study drug.

The modified intent-to-treat 1 (mITT1) analysis set included data from all randomized participants at the Month 15 visit. Here, 'Overall number of participants analyzed' = Participants evaluable for this outcome measure.

Relapse was defined as appearance of one or more new neurological abnormalities or reappearance or worsening of one or more previously observed neurological abnormalities, lasting for at least 48 hours (in absence of fever or any infection) and immediately preceded by an improving neurological state of at least 30 days from onset of previous relapse. An event was counted as a relapse only when the participant's symptoms were accompanied by observed objective neurological changes, consistent with an increase of at least 0.5 in EDSS; or one grade in score of 2 or more of 7 Functional Systems (FS) (excluding changes in bowel or bladder function or cognition); or 2 grades in score of one of the FS as compared to previous evaluation. EDSS assesses disability in 8 FS with an overall score ranging from 0 (normal) to 10 (death due to MS). Data is presented as distribution of relapsing participants (number of participants with confirmed relapse).

ITT analysis set included all randomized participants.

Time to CDP was defined as the time to a sustained increase in Kurtzke's EDSS score of at least 1 point if baseline EDSS score was less than or equal to 5.0, or at least 0.5 point if the baseline EDSS score was 5.5, over a period of at least 6 months. EDSS assesses disability in 8 functional systems with an overall score ranging from 0 (normal) to 10 (death due to MS). Data is presented as distribution of CDP (number of participants with CDP) sustained for 6 months.

ITT analysis set included all randomized participants.

Time to CDP was defined as the time to a sustained increase in Kurtzke's EDSS score of at least 1 point if baseline EDSS score was less than or equal to 5.0, or at least 0.5 point if the baseline EDSS score was 5.5, over a period of at least 9 months. EDSS assesses disability in 8 functional systems with an overall score ranging from 0 (normal) to 10 (death due to MS). Data is presented as distribution of CDP (number of participants with CDP) sustained for 9 months.

ITT analysis set included all randomized participants.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Serious adverse event (SAE) was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. AEs included both SAEs and non-serious AEs.

Safety analysis set included all participants who were randomized and received at least one dose of study drug.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. AEs included both SAEs and non-serious AEs.

Safety analysis set in active-treatment phase included all participants who completed placebo-controlled phase on treatment and continued to either of the 2 laquinimod treatments during active-treatment phase.

Clinically significant vital signs abnormalities included: Pulse rate: greater than or equal to (>=) 120 beats per minute (bpm) and increase from baseline of >=30 bpm, <=45 bpm and decrease from baseline of >=30 bpm; Systolic blood pressure: >=180 millimeters of mercury (mmHg) and increase from baseline of >=30 mmHg, <=90 and decrease from baseline of >=30 mmHg; Diastolic blood pressure: >=100 mmHg and increase from baseline of >=20 mmHg, <=50 mmHg and decrease from baseline of >=20 mmHg.

Safety analysis set included all participants who were randomized and received at least one dose of study drug.

Clinically significant vital signs abnormalities included: Pulse rate: >=120 bpm and increase from baseline of >=30 bpm, <=45 bpm and decrease from baseline of >=30 bpm; Systolic blood pressure: >=180 mmHg and increase from baseline of >=30 mmHg, <=90 and decrease from baseline of >=30 mmHg; Diastolic blood pressure: >=100 mmHg and increase from baseline of >=20 mmHg, <=50 mmHg and decrease from baseline of >=20 mmHg.

Safety analysis set in active-treatment phase included all participants who completed placebo-controlled phase on treatment and continued to either of the 2 laquinimod treatments during active-treatment phase.

ECG parameters included: PR interval, QRS interval, QT interval corrected using the Fridericia formula (QTcF) and QT interval corrected using the Bazett's formula (QTcB). Shifts represented as Baseline - endpoint value (last observed post-baseline value). Abnormal NCS indicated an abnormal but not clinically significant finding. Abnormal CS indicated an abnormal and clinically significant finding.

Safety analysis set included all participants who were randomized and received at least one dose of study drug. Here, 'Overall number of participants analyzed=participants evaluable for this outcome measure.

ECG parameters included: PR interval, QRS interval, QTcF and QTcB. Shifts represented as Baseline - endpoint value (last observed post-baseline value). Abnormal NCS indicated an abnormal but not clinically significant finding. Abnormal CS indicated an abnormal and clinically significant finding.

Safety analysis set in active-treatment phase included all participants who completed placebo-controlled phase on treatment and continued to either of the 2 laquinimod treatments during active-treatment phase and had ECG shift from baseline data available.

Potentially clinically significant serum chemistry abnormalities included: Glucose <=3 and >=13.88 millimoles per liter (mmol/L); Alanine aminotransferase (ALT) (in units per liter [U/L]), aspartate aminotransferase (AST) (in U/L), alkaline phosphatase (in U/L), gamma-glutamyltransferase (GGT) (in U/L), creatine phosphokinase (CPK) (in U/L), C-reactive protein (CRP) (in milligrams per liter [mg/L]), pancreatic amylase (in U/L)>=3 * upper limit of normal (ULN); Fibrinogen >=6 grams per liter (gm/L); Sodium <=130 and >=150 mmol/L; Potassium <=3.2 and >=5.5 mmol/L; Calcium <=1.87 and >=2.75 mmol/L; Phosphate <=0.65 and >=1.61 mmol/L.

Safety analysis set included all participants who were randomized and received at least one dose of study drug. Here, 'Overall number of participants analyzed'=participants evaluable for this outcome measure.

Potentially clinically significant serum chemistry abnormalities included: Glucose <=3 and >=13.88 mmol/L; ALT (in U/L), AST (in U/L), alkaline phosphatase (in U/L), GGT (in U/L), CPK (in U/L), CRP (in mg/L), pancreatic amylase (in U/L)>=3 * ULN; Fibrinogen >=6 gm/L; Sodium <=130 and >=150 mmol/L; Potassium <=3.2 and >=5.5 mmol/L; Calcium <=1.87 and >=2.75 mmol/L; Phosphate <=0.65 and >=1.61 mmol/L; Blood urea nitrogen (in mmol/L); Total bilirubin >=28 micromols per liter (micromols/L); Creatinine >=117 micromols/L; Albumin <=25 gm/L.

Safety analysis set in active-treatment phase included all participants who completed placebo-controlled phase on treatment and continued to either of the 2 laquinimod treatments during active-treatment phase.

Potentially clinically significant hematological abnormalities included: Hemoglobin <=11.5 grams per deciliter (gm/dL) in males and <=10 gm/dL in females; White blood cells (WBCs) count <=2.5 and >=21*10^9 per liter (L); Absolute neutrophil count (ANC) <=1.49*10^9 per L; Platelet count <=100 and >=600*10^9 per L.

Safety analysis set included all participants who were randomized and received at least one dose of study drug. Here, 'Overall number of participants analyzed'=participants evaluable for this outcome measure.

Potentially clinically significant hematological abnormalities included: Hemoglobin <=11.5, >=20 gm/dL in males, and <=10, >=18.5 gm/dL in females; WBCs count <=2.5 and >=21*10^9 per L; ANC <=1.49*10^9 per L; Platelet count <=100 and >=600*10^9 per L.

Safety analysis set in active-treatment phase included all participants who completed placebo-controlled phase on treatment and continued to either of the 2 laquinimod treatments during active-treatment phase.