In people with radiologically isolated syndrome, teriflunomide resulted in a 62% risk decline for a first clinical event related to the central nervous system.

Radiologically isolated syndrome (RIS) represents the earliest detectable pre-clinical phase of MS. MRI features of RIS are highly similar to MS without clinical symptoms. In a previous study, the use of dimethyl fumarate (DMF) to prevent the clinical onset of MS was associated with a risk reduction of more than 80%. The phase 3 TERIS study aimed to evaluate the efficacy and safety of the disease-modifying treatment (DMT) teriflunomide, with a different mechanism of action, in a cohort of participants with RIS from Europe and Turkey.

Christine Lebrun-Frenay, MD, PhD, FAAN presented the results. She explained that the TERIS study included 89 adult participants who fulfilled the 2009 RIS criteria. Participants were randomized 1:1 to teriflunomide (14 mg daily) or placebo. The primary outcome measure was the time-to-onset of a first clinical symptom that can be attributed to a CNS demyelinating event over 96 weeks. Of randomized participants, 63 (71%) were women, the mean age was 40, and the age at index MRI was 38.

During 96 weeks of follow-up, 28 clinical events were detected, including 8 in the teriflunomide group and 20 in the placebo group. This difference was significant in both the unadjusted and adjusted analyses. In the unadjusted analysis, the HR was 0.37 (95% CI, 0.16-0.84; P=0.018). In the adjusted analysis, the HR was 0.28 (95% CI, 0.11-0.71; P=0.007).

Though not statistically significant, the number of MRI lesions was also lower in the treatment group compared with the placebo group. For the cumulative number of gadolinium-enhanced lesions, the adjusted rate ratio (RR) was 0.33. For new or enlarging T2 lesions, the adjusted RR was 0.57.

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