Slowing of brain atrophy with teriflunomide and delayed conversion to clinically definite MS

Background: We explored the effect of teriflunomide on cortical gray matter (CGM) and whole brain (WB) atrophy in patients with clinically isolated syndrome (CIS) from the phase III TOPIC study and assessed the relationship between atrophy and risk of conversion to clinically definite MS (CDMS).Methods: Patients (per McDonald 2005 criteria) were randomized 1:1:1 to placebo, teriflunomide 7 mg, or teriflunomide 14 mg for ⩽108 weeks (core study). In the extension, teriflunomide-treated patients maintained their original dose; placebo-treated patients were re-randomized 1:1 to teriflunomide 7 mg or 14 mg. Brain volume was assessed during years 1–2.Results: Teriflunomide 14 mg significantly slowed annualized CGM and WB atrophy versus placebo during years 1–2 [percent reduction: month 12, 61.4% (CGM; p = 0.0359) and 28.6% (WB; p = 0.0286); month 24, 40.2% (CGM; p = 0.0416) and 43.0% (WB; p < 0.0001)]. For every 1% decrease in CGM or WB volume during years 1–2, risk of CDMS conversion increased by 14.5% ( p =  0.0004) and 47.3% ( p < 0.0001) during years 1–2, respectively, and 6.6% ( p =  0.0570) and 35.9% ( p = 0.0250) during years 1–5. In patients with the least (bottom quartile) versus most (top quartile) atrophy during years 1–2, risk of CDMS conversion was reduced by 58% (CGM; p = 0.0024) and 58% (WB; p = 0.0028) during years 1–2, and 42% (CGM; p = 0.0138) and 29% (WB; p = 0.1912) during years 1–5.Conclusion: These findings support the clinical relevance of CGM and WB atrophy and early intervention with teriflunomide in CIS.