Long-term safety and efficacy of zilucoplan in patients with generalized myasthenia gravis: interim analysis of the RAISE-XT open-label extension study

Abstract

Background: Generalized myasthenia gravis (gMG) is a chronic, unpredictable disease associated with high treatment and disease burdens, with a need for more effective and well-tolerated treatments. Objectives: To evaluate the long-term safety, tolerability, and efficacy of zilucoplan in a mild-to-severe, acetylcholine receptor autoantibody-positive (AChR+) gMG population. Design: Ongoing, multicenter, phase III open-label extension (OLE) study. Methods: Eligible patients had completed a qualifying randomized, placebo-controlled phase II or phase III zilucoplan study and received daily, self-administered subcutaneous 0.3 mg/kg zilucoplan. The primary endpoint was incidence of treatment-emergent adverse events (TEAEs). Secondary efficacy endpoints included change from baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) score. Results: = 49, 25%). In patients who received zilucoplan 0.3 mg/kg in the parent study, further improvements in MG-ADL score continued through to Week 24 (least squares mean change [95% confidence interval] from double-blind baseline -6.06 [-7.09, -5.03]) and were sustained through to Week 60 (-6.04 [-7.21, -4.87]). In patients who switched from placebo in the parent study, rapid improvements in MG-ADL score were observed at the first week after switching to zilucoplan; further improvements were observed at Week 24, 12 weeks after switching (-6.46 [-8.19, -4.72]), and were sustained through to Week 60 (-6.51 [-8.37, -4.65]). Consistent results were observed in other efficacy endpoints. Conclusion: Zilucoplan demonstrated a favorable long-term safety profile, good tolerability, and sustained efficacy through to Week 60 with consistent benefits in a broad AChR+ gMG population. Additional long-term data will be available in future analyses. Trial registration: ClinicalTrials.gov identifier: NCT04225871 (https://clinicaltrials.gov/ct2/show/NCT04225871).