Tolebrutinib

Potentially clinically significant abnormalities (PCSAs) determined by laboratory tests, electrocardiogram (ECG), or vital signs and safety findings on MRI during the study period.

The EDSS is a disability scale that assesses the following 7 functional domains: visual, brainstem, pyramidal \[motor\], cerebellar \[coordination\], sensory, cerebral, and bowel/bladder. The total EDSS ranges from 0 (normal) to 10 (death due to multiple sclerosis \[MS\]) (0.5 increments from 1-10; next increase after 0 is 1). Higher scores indicated increased disability. Time to onset of 6-month CDP was defined as the time from randomization to the onset of a sustained increase from baseline in EDSS score of \>=1.0 point from the baseline EDSS score when the baseline score was \<=5.0 or of \>=0.5 points when the baseline EDSS score was \>5.0 confirmed after a minimum 6-month interval.

Time to onset of 6-month cCDP defined as follows: Increase over at least 6 months of ≥1.0 point from the baseline expanded disability status scale (EDSS) score when the baseline score is ≤5.5, or ≥0.5 points when the baseline EDSS score is \>5.5, or ≥20% from the baseline T25-FW, or ≥20% from the baseline 9-HPT

Multiple sclerosis (MS) relapse was defined as a monophasic, acute or subacute onset of new neurological symptoms or worsening of previous neurological symptoms with an objective change on neurological examination. Symptoms were attributable to MS, lasted for \>=24 hours with or without recovery, present at normal body temperature, and preceded by \>=30 days of clinical stability.

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study drug, whether or not considered related to the study drug. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent disability/incapacity, was a congenital anomaly/birth defect or was an important medical event. TEAEs were defined as AEs that developed, worsened or became serious during the respective on-treatment periods.

Number of new Gd-enhancing T1-hyperintense lesions was detected by brain MRI at the end of 12 weeks of SAR442168 treatment (i.e., at Week 12 for Cohort 1 participants and Week 16 for Cohort 2 participants). Data was planned to be collected and analyzed on pooled population of participants at each dose level of SAR442168 (either in Cohort 1 and 2) and pooled population of participants receiving placebo in Cohort 2 and was not planned to collected during placebo administration in Cohort 1 (Weeks 12 to 16).

Area under the plasma concentration (AUC) versus time curve extrapolated to infinity

AUC up to the last measurable concentration

Area under the curve, reflects the concentration of drug

Fractional and cumulative percentage of radioactive dose excreted in urine and feces of \[14C\]-SAR442168