To assess the durability of minimal symptom expression (MSE) response during treatment with zilucoplan, a complement component 5 inhibitor, in patients with generalised myasthenia gravis (gMG) in the RAISE-XT (NCT04225871) study.
MSE, defined as a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of 0 or 1, is a rigorous measure of therapeutic efficacy in myasthenia gravis. RAISE-XT is a Phase 3, open-label extension study of zilucoplan.
Adults with anti-acetylcholine receptor antibody-positive gMG who completed a qualifying double-blind, placebo-controlled study (NCT03315130/NCT04115293 [RAISE]) could opt to enter RAISE-XT and self-administer once-daily subcutaneous injections of zilucoplan 0.3 mg/kg. The cumulative proportion of patients who achieved MSE (MG-ADL score of 0 or 1 without rescue therapy) at any time during zilucoplan treatment up to Week 120 and the proportion of time spent in MSE up to Week 120 were assessed post hoc (interim data cut-off: November 11, 2023).
Of 200 patients enrolled in RAISE-XT, 183 received zilucoplan 0.3 mg/kg or placebo in the double-blind studies. The cumulative proportion of patients who achieved MSE at any time from the start of zilucoplan treatment up to Week 120 in the zilucoplan 0.3 mg/kg/zilucoplan 0.3 mg/kg and placebo/zilucoplan 0.3 mg/kg groups was 61% and 64%, respectively. After first achieving MSE during zilucoplan treatment, patients maintained their MSE response for a median (range) of 80.8% (0.8–100.0%) of their remaining time in the study up to Week 120. Treatment-emergent adverse events were experienced by 97.0% (n=194/200) of patients; most were mild or moderate.