A Phase 3 Open-Label Study of Eculizumab in Pediatric Participants With Refractory Generalized Myasthenia Gravis (gMG)
A Phase 3 Open-Label Study of Eculizumab in Pediatric Participants With Refractory Generalized Myasthenia Gravis (gMG)
The purpose of this study is to evaluate the efficacy, safety, pharmacokinetics, and
 pharmacodynamics of eculizumab in the treatment of pediatric refractory gMG based on change
 from Baseline in the Quantitative Myasthenia Gravis (QMG) score for disease severity.
The study will consist of an up to 4-week Screening Period, 26-week Primary Evaluation
 Treatment Period, an additional (up to) to 208-week Extension Period, and an 8-week Safety
 Follow-up Period.
Inclusion Criteria:

 -  Male or female pediatric participants 6 to <18 years of age at time of assent/consent.

 -  Vaccinated against Neisseria meningitidis.

 -  Documented vaccination against Haemophilus influenzae and Streptococcus pneumoniae
 infections prior to dosing as per local and country specific immunization guidelines
 for the appropriate age group.

 -  Diagnosis of MG confirmed by positive serologic test for anti-acetylcholine receptor
 antibodies at Screening, and 1 of the following: (a) history of abnormal neuromuscular
 transmission test demonstrated by single-fiber electromyography or repetitive nerve
 stimulation; (b) history of positive anticholinesterase test (for example, edrophonium
 chloride or neostigmine test); or (c) participant demonstrated improvement in MG signs
 on oral acetylcholinesterase inhibitors, as assessed by the Investigator.

 -  Presence of refractory gMG, defined as participants with gMG who have 1 or more of the
 following: (a) failed treatment ≥1 year with at least 1 immunosuppressive therapies
 (IST), defined as follows: (1) persistent weakness with impairment of activities of
 daily living; (2) myasthenia gravis (MG) exacerbation and/or crisis while on
 treatment; or (3) intolerance to ISTs due to side effect or comorbid condition(s). (b)
 Require maintenance plasma exchange (PE) or intravenous immunoglobulin (IVIg) to
 control symptoms; and/or (c) in the opinion of the Investigator, MG poses a
 significant functional burden despite current MG treatment.

 -  MGFA Clinical Classification of Class II to IV at Screening.

 -  In patients aged 12 to 18 years, QMG total score ≥ 12 at Screening; in patients aged 6
 to 11 years, no minimum QMG is required for inclusion; however, patients must have
 documented limb weakness in at least one limb.

 -  All MG-specific treatment has been administered at a stable dosing regimen of adequate
 duration prior to Screening.

 Exclusion Criteria:

 -  Parent or legal guardian is an Alexion employee.

 -  Any active or untreated thymoma. History of thymic carcinoma or thymic malignancy
 unless deemed cured by adequate treatment with no evidence of recurrence for ≥5 years
 before Screening.

 -  History of thymectomy within 12 months prior to Screening.

 -  Are pregnant or lactating.

 -  Any unresolved acute, or chronic, systemic bacterial or other infection, which is
 clinically significant in the opinion of the Investigator and has not been treated
 with appropriate antibiotics.

 -  Use of PE within 4 weeks prior to first dose.

 -  Use of rituximab within 6 months prior to first dose.

 -  Patients who are under 15 kg and are receiving maintenance IVIg.

 -  Participation in another interventional treatment study or use of any experimental
 therapy within 30 days before initiation of study drug on Day 1 in this study or
 within 5 half-lives of that investigational product, whichever is greater.

 -  Have previously received treatment with eculizumab or other complement inhibitors.