A Multicentre open-label, uncontrolled study to evaluate the pharmacokinetics, pharmacodynamics, safety, tolerability, and activity of zilucoplan in paediatric study participants from 2 to less than 18 years of age with acetylcholine receptor antibody positive generalised myasthenia gravis.

Researchers are looking for a better way to treat generalised myasthenia gravis (gMG) in children. In people with gMG, the immune system attacks the places where nerve cells connect to muscles. This can lead to muscle weakness, eye problems, and difficulty breathing. Severe cases of gMG can be life-threatening. There are few treatments available for children with gMG, and the treatments that do exist can cause long-term medical problems. The study medication, zilucoplan, is designed to stop part of the immune system from attacking the body. Researchers think that zilucoplan could be a new treatment option for children with gMG.The aim of the study is to see how safe and effective Zilucoplan is in treating children with positive gMG.This study will include at least 8 participants. All participants will be 2 to 17 years of age and have gMG, across several countries globally. Zilucoplan is injected by the participant or caregiver through a needle just underneath the skin, also called a subcutaneous (SC) injection. Doses of zilucoplan are measured in milligrams (mg) per kilogram (kg) of each participant’s body weight. All participants will receive about 0.3 mg/kg of zilucoplan once a day for 4 weeks. Participants will visit the study site 4 times while they are receiving treatment. Zilucoplan injections will happen at home and during study site visits.Participants will be in this study for up to about 15 weeks. After receiving zilucoplan for 4 weeks in this study, participants may be able to continue receiving zilucoplan in another study. The Sponsor of the study is UCB Biopharma SRL.