Background
Interleukin-6 (IL-6) is implicated in the immune pathology of neuromyelitis optica spectrum disorder (NMOSD). Satralizumab, a humanized recycling monoclonal antibody that binds to the IL-6 receptor, reduced risk of relapse in patients with NMO or NMOSD as add-on therapy in the SAkuraSky study (NCT02028884) and as monotherapy in the SAkuraStar study (NCT02073279).
Objective
Evaluate the efficacy of satralizumab monotherapy vs placebo for relapse prevention in pre-defined subgroups of the SAkuraStar study.
Methods
SAkuraStar is a randomized, double-blind, Phase 3 study comparing satralizumab monotherapy with placebo. 95 patients with NMO or NMOSD, with ≥1 documented relapse in the year prior to screening, were randomized 2:1 to satralizumab (120 mg s.c.) or placebo. The primary endpoint was time to first protocol-defined relapse (PDR). Pre-specified subgroup analyses assessed treatment response by AQP4-IgG serostatus, prior therapy, and relapse history.
Results
Overall, satralizumab reduced risk of PDR by 55% vs placebo (hazard ratio [HR] 0.45; 95% confidence interval [CI] 0.23–0.89; p = .018). There was a 74% reduction in PDR risk with satralizumab vs placebo in AQP4-IgG-seropositive patients (HR 0.26; 95% CI 0.11–0.63). In AQP4-IgG-seronegative patients, the HR was 1.19 (95% CI 0.30–4.78). HRs for additional subgroups are provided in Table 1. The proportion of relapse-free patients at Weeks 48 and 96 in the AQP4-IgG-seropositive and seronegative subgroups will be presented. Conclusions Satralizumab was effective in reducing risk of PDR in patients with NMO or NMOSD, particularly in AQP4-IgG-seropositive patients. The study was not powered for subgroup analyses; therefore, results should be interpreted with caution.
