The purpose of this study is to assess the pharmacokinetics, pharmacodynamics, safety, tolerability, immunogenicity and activity of zilucoplan (ZLP) in pediatric study participants with generalized myasthenia gravis (gMG).

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 according to local regulation

Rest of world (ROW) specific inclusion criterion:

- Participant must be 2 to <18 years of age at the time of signing the Informed consent/assent according to local regulation

Global inclusion criteria:

• Participant has a diagnosis of generalized myasthenia gravis (gMG) confirmed by a prior positive serologic test result to acetylcholine receptor (AChR) prior to Screening
• Participant meets the criteria as defined by the Myasthenia Gravis Foundation of America (MGFA) Clinical Classification II to IV at Screening
• Participants with gMG, including:
• An MG-activities of daily living (MG-ADL) total score of 6 or more in adolescents from 12 years to <18 years of age at Screening
• Documented weakness in at least 1 limb, neck, or bulbar muscle in children from 2 years to <12 years of age at Screening (does not apply to US)
• Documented vaccination against meningococcal infections within 3 years prior to study start. If not fully vaccinated, participants must receive appropriate prophylactic antibiotic treatment until at least 2 weeks after the initial dose of vaccine(s)

Exclusion Criteria:

• Participant has known positive serology for muscle-specific kinase
• Participant has any medical or psychiatric condition that, in the opinion of the Investigator, could jeopardize or would compromise the participant's ability to participate in this study
• Participant has had a thymectomy within 6 months prior to Baseline
• Participant has minimal Manifestation Status of MG based on the clinical judgement of the Investigator
• Current or recent systemic infection within 2 weeks prior to Baseline or infection requiring intravenous antibiotics within 4 weeks prior to Baseline

Data from this trial may be requested by qualified researchers six months after product approval in the US and/or Europe, or global development is discontinued, and 18 months after trial completion. Investigators may request access to anonymized individual patient-level data and redacted trial documents which may include: analysis-ready datasets, study protocol, annotated case report form, statistical analysis plan, dataset specifications, and clinical study report. Prior to use of the data, proposals need to be approved by an independent review panel at www.Vivli.org and a signed data sharing agreement will need to be executed. All documents are available in English only, for a prespecified time, typically 12 months, on a password protected portal. This plan may change if the risk of re-identifying trial participants is determined to be too high after the trial is completed; in this case and to protect participants, individual patient-level data would not be made available.

Data from this study may be requested by qualified researchers six months after product approval in the US and/or Europe or global development is discontinued, and 18 months after trial completion.

Qualified researchers may request access to anonymized IPD and redacted study documents which may include: raw datasets, analysis-ready datasets, study protocol, blank case report form, annotated case report form, statistical analysis plan, dataset specifications, and clinical study report. Prior to use of the data, proposals need to be approved by an independent review panel at www.Vivli.org and a signed data sharing agreement will need to be executed.All documents are available in English only, for a pre-specified time, typically 12 months, on a password protected portal.