GEFURULIMAB significantly improved disease severity in adults with anti acetylcholine receptor antibody positive generalised myasthenia gravis compared with placebo, with clinical benefits emerging rapidly and persisting throughout 26 weeks of treatment. The Phase III PREVAIL trial enrolled adults aged 18 years and older with anti acetylcholine receptor antibody positive generalised myasthenia gravis, Myasthenia Gravis Foundation of America class II–IV disease, and a Myasthenia Gravis Activities of Daily Living total score of five or greater. The primary outcome assessed change from baseline in the Myasthenia Gravis Activities of Daily Living total score at week 26, while the key secondary outcome evaluated change in the Quantitative Myasthenia Gravis total score. Improvements in the Myasthenia Gravis Activities of Daily Living score were observed within 1 week of treatment, while improvements in the Quantitative Myasthenia Gravis score were evident by week 4. Improvements in the Quantitative Myasthenia Gravis score were also greater with gefurulimab than placebo:−4.5 versus−2.4; treatment difference:−2.1; 95% CI:−3.1–−1.1; p<0.001.