NMOSD is an autoimmune disorder characterized by acute, unpredictable relapses that result in accumulating disability. Satralizumab, a humanized, monoclonal recycling antibody that targets the interleukin-6 receptor, reduced relapse frequency and had a favourable safety profile vs placebo in two randomized, phase 3 clinical trials: SAkuraSky (satralizumab in combination with baseline immunosuppressants; NCT02028884), and SAkuraStar (satralizumab monotherapy; NCT02073279).
To assess the impact of satralizumab on relapse severity in patients with NMOSD.
Patients in the SAkura studies received satralizumab 120mg or placebo at Weeks 0, 2, 4, and Q4W thereafter. This analysis was performed using data from the pooled intention-to-treat population across the double-blind periods of both studies. We assessed the severity of protocol-defined relapses (PDRs) by comparing patients’ Expanded Disability Status Scale (EDSS) score at PDR vs their score prior to relapse (last scheduled study visit). A similar analysis on optic neuritis PDRs was performed using visual Functional Systems Score (FSS). A PDR was categorised as severe if it resulted in a change of ≥2 points on the EDSS or visual FSS (optic neuritis analysis). Kaplan-Meier analyses were performed to assess time to first severe PDR. Additionally, the number of patients receiving acute therapy for any relapse was compared between treatment groups.
Overall, 178 patients were included in the analyses. In the satralizumab group, 27 of 104 patients (26%) experienced a PDR vs 34 of 74 patients (46%) in the placebo group. The proportion of PDRs that were severe was lower in patients receiving satralizumab vs placebo (5 of 27 events [19%] vs 12 of 34 events [35%]). Similarly, the proportion of optic neuritis PDRs that were severe was lower in patients receiving satralizumab vs placebo (2 of 8 events [25%] vs 5 of 13 events [39%]). Across all patients, there was a 79% reduction in severe PDR risk with satralizumab vs placebo (hazard ratio [95% CI]; 0.21 [0.07–0.61]; p=0.002). A lower proportion of patients receiving satralizumab were prescribed acute relapse therapy vs placebo (38% vs 58%; odds ratio [95% CI] 0.46 [0.25–0.86], p=0.015).
Patients treated with satralizumab had a lower risk of severe relapse, and were less likely to receive acute relapse therapy compared with placebo. The number of patients with severe PDRs was low, so results should be interpreted with caution.