043 Efficacy of siponimod in secondary progressive multiple sclerosis with active disease: EXPAND study subgroup analysis

Background Siponimod, a selective sphingosine 1-phosphate receptor modulator, demonstrated clini- cally relevant effects in a typical secondary progressive multiple sclerosis (SPMS) population in the Phase 3 EXPAND study, with 21% and 26% reductions in 3- and 6-month confirmed disability progression (CDP) versus placebo. Methods Post hoc subgroup analysis was performed in patients with active disease (defined as the presence of relapses in 2 years before screening and/or ≥1 T1 gadolinium-enhancing [Gd ] lesion at baseline) to assess the efficacy of siponimod 2mg versus placebo in this population. Results This analysis included 779 SPMS patients with active disease (siponimod [n=516], placebo [n=263]). The proportion of patients with relapse in the 2 years prior to study was 76% and with Gd lesions at baseline 45%. Siponimod significantly reduced 3-month CDP risk by 31% (HR [95% CI]: 0.69 [0.53, 0.91]; p=0.0094) and 6-month CDP risk by 37% (HR [95% CI]: 0.63 [0.47, 0.86], p=0.0040) versus placebo. Reductions in risk of 6 month SDMT worsening, ARR, and MRI endpoints were also seen. Conclusions In this subgroup of active SPMS patients from EXPAND, benefits on disability progression were more pronounced with clinically relevant effects across disability progression, cognitive processing speed, and MRI inflammatory disease activity. g.giovannoni@qmul.ac.uk