Long-term use of rozanolixizumab in generalised myasthenia gravis: final pooled analysis of the phase III MycarinG study and two open-label extensions

Background: Myasthenia gravis (MG) is a rare autoimmune disease characterised by fluctuating and fatigable muscle weakness. In the randomised, double-blind phase III MycarinG study, one 6-week rozanolixizumab cycle significantly improved MG-specific outcomes versus placebo and was generally well tolerated in patients with generalised MG (gMG). Objectives: To assess the efficacy and safety of cyclic rozanolixizumab treatment. Design: A pooled analysis of the MycarinG, MG0004 and MG0007 studies. Methods: Following MycarinG, eligible patients could enrol in the open-label extension studies MG0004 or MG0007 to receive rozanolixizumab 7 or 10 mg/kg. In MG0004, patients received chronic weekly treatment for ⩽52 weeks. In MG0007, after an initial 6-week treatment cycle, subsequent cycles were based on symptom worsening (investigator’s discretion). Final efficacy data were pooled across MycarinG, MG0004 (first 6 weeks) and MG0007 for patients receiving ⩾2 symptom-driven cycles. Efficacy endpoints included change from baseline (CFB) in MG Activities of Daily Living (MG-ADL), MG Composite (MGC) and Quantitative MG (QMG) scores. Safety outcomes were assessed in patients who received ⩾1 cycle with a ⩽8-week follow-up period across MycarinG and MG0007. Results: Overall, 188 patients received ⩾1 cycle and 129 received ⩾2 symptom-driven cycles. Across Cycles 1–13, mean (standard deviation) CFB to Day 43 in MG-ADL score ranged from −3.2 (3.3 (n = 113; Cycle 3)) to −6.0 (3.9 (n = 24; Cycle 12)). Consistent improvements in MGC and QMG scores were also observed across repeated cycles. Treatment-emergent adverse events (TEAEs) were experienced by 175/188 (93.1%) patients; most mild or moderate. Incidence remained stable with repeated cyclic treatment among patients who remained in the study at each cycle. The most common TEAE was headache (n = 94/188 (50.0%)). Conclusion: Repeated rozanolixizumab treatment cycles demonstrated consistent, clinically meaningful improvements in MG-specific outcomes as early as 1 week after the first infusion. Rozanolixizumab was generally well tolerated with an acceptable safety profile, supporting its long-term use as a treatment option for adults with gMG. Trial registration: ClinicalTrials.gov: NCT03971422; NCT04124965; NCT04650854.