Evaluation of the Condition of Patients Receiving EARLY Ravulizumab and Admitted in ICU for gMG Crisis

Myasthenia Gravis (MG) is a rare autoimmune disease that causes muscle weakness and fatigue. It occurs when the immune system produces antibodies that block communication between nerves and muscles. In some patients, the disease can suddenly worsen and cause severe breathing problems. This life-threatening situation is called a myasthenic crisis and requires immediate treatment in an intensive care unit (ICU). During such crises, patients may need to receive respiratory assistance through a ventilator. These episodes are often long and can lead to complications such as infections or heart problems. To manage a myasthenic crisis, doctors usually use treatments that remove or neutralize the harmful antibodies: plasma exchange (PLEX) or intravenous immunoglobulin (IVIg). Although both are effective, recovery can be slow, and many patients remain in the ICU for several weeks. Ravulizumab (Ultomiris®) is a new medicine that targets a specific part of the immune system called the complement system, which contributes to muscle damage in MG. It is already approved for adults with generalized MG who have anti-acetylcholine receptor (AChR) antibodies. Ravulizumab is given by intravenous infusion every eight weeks. Clinical studies have shown that it can improve symptoms within one week of starting treatment. Some doctors have started using ravulizumab early, after PLEX or IVIg, for patients hospitalized in the ICU for a myasthenic crisis. Early use of this treatment could help reduce the duration and severity of the crisis, leading to faster recovery and shorter hospital stays. However, there is currently no national study that systematically collects data on this approach. The EARLY-MG study aims to describe the condition and recovery of patients who receive ravulizumab early during a myasthenic crisis requiring ICU admission. The study will not test an experimental treatment or change medical care. It is an observational study. The main hypothesis of the study is that early administration of ravulizumab, after PLEX or IVIg, may help patients recover faster, improve muscle strength, and reduce complications and hospital stay. Around 30 adult patients with generalized MG and anti-AChR antibodies will be enrolled in 10 centers across France. Each patient will be followed for 26 weeks (about six months). Assessments will be performed at the start of the study and at weeks 2, 4, 10, 18, and 26. Investigators will collect information such as:

• Duration of stay in the ICU and in the hospital after receiving ravulizumab
• Duration of mechanical ventilation, if needed
• Clinical improvement using standard evaluation scales (Myasthenia Gravis Activities of Daily Living, MG Foundation of America classification, and Garches' score)
• Occurrence of any complications or additional treatments The study will last about 18 months in total, including one year for patient inclusion and six months of follow-up per patient. The results may help guide future recommendations and improve patient care in France and worldwide.