Long-term safety and efficacy of ponesimod in participants with relapsing multiple sclerosis: results from the phase 3 OPTIMUM 5-year long term extension study

Introduction: In phase 3 OPTIMUM study, ponesimod demonstrated superior efficacy and acceptable safety vs teriflunomide in participants with relapsing multiple sclerosis (RMS). This long-term extension (LTE) study was designed to assess the safety and efficacy of ponesimod 20 mg (P20 mg) during extended treatment. Methods: Participants who completed core OPTIMUM study entered OPTIMUM-LTE; Participants receiving P20 mg once daily (OD) in core continued with the same dose (P20 mg/P20 mg) and those receiving teriflunomide 14 mg OD switched to P20 mg (T14 mg/P20 mg) in the LTE study. Safety assessments included treatment-emergent adverse events (TEAE). Efficacy was assessed using annualized relapse rate (ARR), time to first confirmed relapse up to end of study (EOS), confirmed disability accumulation (CDA), and magnetic resonance imaging (MRI)-based endpoints. Results: Of 1133 participants from core study, 877 were enrolled in 240-week LTE study (ponesimod: 439; teriflunomide:438). During LTE, 93.6% of participants in both groups experienced ≥ 1 TEAE; overall, serious TEAEs were experienced by 12.9% of participants (P20 mg/P20 mg: 12.8%; T14 mg/P20 mg: 13.0%) and TEAEs leading to study treatment discontinuation were experienced by 8.6% of participants (P20 mg/P20 mg: 7.7%; T14 mg/P20 mg: 9.4). In combined analysis period, mean ARR was 0.143 (95% CL: 0.123–0.167) for P20 mg/P20 mg and 0.184 (95% CL: 0.158–0.213) for T14 mg/P20 mg; 44.3% of participants in P20 mg/P20 mg and 49.5% in T14 mg/P20 mg experienced relapse. Overall, more participants in P20 mg/P20 mg vs T14 mg/P20 mg group achieved no evidence of disease activity (NEDA)-3 at end of LTE (17.5% vs 7.5%). Conclusions: Ponesimod demonstrated extended safety and sustained efficacy over 5 years in participants with RMS, without new safety signals. Results suggest that the effects on the MS disease control are maintained with ponesimod over the LTE treatment period.