PK, PD, Safety, and Efficacy Study of Gefurulimab in Pediatric Patients With AChR+ Generalized Myasthenia Gravis

Inclusion Criteria:

United States of America (USA) specific inclusion criterion:

* Participant must be 12 to \< 18 years of age at the time of signing the informed consent/assent.
* All participants must be vaccinated against meningococcal infection from serogroups A, B, C, W, and Y within 3 years and at least 2 weeks prior to the first dose of study intervention administration.

Rest of World (ROW) specific inclusion criteria:

* Participant must be 6 to \< 18 years of age at the time of signing the informed consent/assent.
* All participants must be vaccinated against meningococcal infection from serogroups A, C, W, Y (and B where available) within 3 years prior to study intervention on Day 1. If vaccination occurs \< 2 weeks prior to Day 1, the participants will receive prophylactic antibiotics for at least 2 weeks after initial meningococcal vaccination for serogroups A,C,W,Y (and B, where available)

Global inclusion criteria:

* Diagnosis of MG with generalized muscle weakness meeting the clinical criteria defined by Myasthenia Gravis Foundation of America (MGFA) Class II, III or IV
* Positive serological test for autoantibodies against AChR

Exclusion Criteria:

* History of thymectomy, or any other thymic surgery within 12 months prior to Screening
* Untreated thymic malignancy, carcinoma, or thymoma
* History of Neisseria meningitidis infection
* Pregnancy, breastfeeding, or intention to conceive during the course of the study