An Open-Label, Multicenter Study to Evaluate the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of Eculizumab in Pediatric Patients With Refractory Generalized Myasthenia Gravis
Phase: PHASE3
Conditions: Myasthenia Gravis, Myasthenia Gravis, Juvenile Form, Myasthenia Gravis, Generalized
Sponsor: Alexion Pharmaceuticals, Inc.

Protocol ECU-MG-303, Version 4.0 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
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ECULIZUMAB 
ECU-MG-303 
AN OPEN-LABEL, MULTICENTER STUDY TO 
EVALUATE THE EFFICACY, SAFETY, 
PHARMACOKINETICS, AND PHARMACODYNAMICS 
OF ECULIZUMAB IN PEDIATRIC PATIENTS WITH 
REFRACTORY GENERALIZED MYASTHENIA GRAVIS 
IND 101,219 
EudraCT Number: 2016-001384-37 
Sponsor: 
Alexion Pharmaceuticals, Inc. 
121 Seaport Boulevard 
Boston MA 02210 
USA 
Sponsor Contact: 
 
Alexion Pharmaceuticals, Inc. 
121 Seaport Boulevard, Suite 400  
Boston, MA 02210 USA 
Telephone: 
 
E-mail: 
Medical Monitor: 
 
Alexion Pharmaceuticals Inc. 
121 Seaport Boulevard, Suite 400 
Boston, MA 02210, USA 
Telephone: 
 
E-mail: 
Version 
4.0 
Date of Protocol: 
28 Sep 2020 
Amended: 
Protocol Version 1.0, 07 Mar 2018 
Protocol Version 2.0, Amendment 1, 17 Sep 2018 
Protocol Version 3.0, Amendment 2, 16 Jul 2019 
This protocol contains confidential information and is provided for exclusive use of Investigators. This 
information may only be disclosed to those persons involved in this study who have a need to know with the 
obligation not to further disseminate this information. This information may not be disclosed to other individuals 
unless such disclosure is required by country, federal, or state law or regulations subject to the foregoing. These 
restrictions on disclosure will apply equally to all future oral or written information supplied to you by Alexion 
which is designated as “privileged” or “confidential.” 
NCT #NCT03759366

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INVESTIGATOR’S AGREEMENT 
 
I have received and read the Investigator’s Brochure for eculizumab. I have read the 
ECU-MG-303 (Amendment 3) study protocol and agree to conduct the study in accordance with 
this protocol, all applicable government regulations, the principles of the ICH E6 Guidelines for 
GCP, and the principles of the World Medical Association Declaration of Helsinki. I also agree 
to maintain the confidentiality of all information received or developed in connection with this 
protocol.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Printed Name of Investigator 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Signature of Investigator 
 
 
 
 
 
 
 
 
Date 
 

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PROCEDURES IN CASE OF EMERGENCY 
Emergency Contact Information 
Study Role 
Name 
Address and Telephone Number 
Clinical Project Lead 
 
Alexion Pharmaceuticals, Inc. 
121 Seaport Boulevard, Suite 400 
Boston, MA 02210, USA 
Telephone : 
 
E-mail: 
 
Medical Monitor 
 
Alexion Pharmaceuticals, Inc. 
121 Seaport Boulevard, Suite 400 
Boston, MA 02210, USA 
Telephone: 
 
E-mail: 
 
Serious Adverse Event 
Reporting 
Alexion Pharmaceuticals, 
Inc. 
Email: 
 
Fax: 
 
Investigational Product 
Supply 
Endpoint Clinical, Inc. 
Telephone:  
 (toll-free) 
 (direct dial) 
 
From outside the United States: 
 (direct dial) 
24-Hour Emergency Contact 
24-Hour Telephone 
Number 
Telephone: 
 
 

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1. 
SYNOPSIS 
Name of Sponsor/Company: Alexion Pharmaceuticals, Inc. 
Name of Investigational Product: Eculizumab 
Name of Active Ingredient: h5G1.1-mAb 
Title of Study: An Open-Label, Multicenter Study to Evaluate the Efficacy, Safety, Pharmacokinetics, and 
Pharmacodynamics of Eculizumab in Pediatric Patients with Refractory Generalized Myasthenia Gravis 
Study Centers: Global (North America, Europe, and Asia) 
Study Duration:  
Estimated date first patient enrolled/randomized: Oct 2018 
Estimated date last patient completed: Jun 2025 
Phase of Development: 3 
Planned Duration of Study: up to 246 weeks (approximately 4.7 years) 
Screening Period: 2 to 4 weeks 
Primary Evaluation Treatment Period: 26 weeks 
Extension Period: up to 208 weeks 
Follow-up Period: 8 weeks following the last dose of eculizumab 
Objectives: 
The primary objective of this study is to evaluate the efficacy of eculizumab in the treatment of pediatric 
refractory generalized myasthenia gravis (gMG) based on change from Baseline in the Quantitative Myasthenia 
Gravis score for disease severity (QMG). 
The secondary objectives of the study are to: 
• 
Evaluate the safety and tolerability of eculizumab in the treatment of pediatric refractory gMG 
• 
Evaluate the efficacy of eculizumab in the treatment of pediatric refractory gMG based on change from 
Baseline in the following measures: 
- 
Myasthenia Gravis Activities of Daily Living profile (MG-ADL)  
- 
Myasthenia Gravis Composite score (MGC)  
• 
Evaluate the effect of eculizumab on the following quality of life measures: 
- 
European Quality of Life 5-Dimension Youth (EQ-5D-Y) Questionnaire – EQ-5D-Y Proxy 
version for patients < 8 years of age or EQ-5D-Y version for patients ≥ 8 years of age 
- 
Neurological Quality of Life Pediatric Fatigue (Neuro-QoL Pediatric Fatigue) Questionnaire 
for patients ≥ 8 years of age 
- 
PROMIS Parent Proxy Item Bank v2.0 – Fatigue – Short Form 10a for patients < 8 years of 
age 
• 
Evaluate MGFA Post-Interventional Status over time  
• 
Describe the total number and percentage of patients with clinical deteriorations, myasthenic crises, 
and rescue therapy use over time 
• 
Describe the pharmacokinetics (PK) and pharmacodynamics (PD) of eculizumab treatment in pediatric 
refractory gMG patients to confirm the pediatric dosing regimen selected through modeling and 
simulation following 26 weeks of eculizumab treatment 
The Extension Period objectives are to: 
• 
Characterize long-term safety beyond 26 weeks of eculizumab treatment in pediatric patients with 
refractory gMG 
• 
Characterize long-term efficacy beyond 26 weeks of eculizumab treatment in pediatric patients with 
refractory gMG 

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Endpoints:  
Primary Efficacy Endpoint: 
Change from Baseline in the QMG total score over time regardless of rescue treatment. 
Secondary Efficacy Endpoints: 
• 
Change from Baseline in the MG-ADL total score over time regardless of rescue treatment 
• 
Proportion of patients with ≥ 3-point reduction in the MG-ADL total score over time with no rescue 
treatment 
• 
Proportion of patients with ≥ 3-point reduction in the MG-ADL total score over time regardless of 
rescue treatment 
• 
Proportion of patients with ≥ 5-point reduction in the QMG total score over time with no rescue 
treatment 
• 
Proportion of patients with ≥ 5-point reduction in the QMG total score over time regardless of rescue 
treatment 
• 
Change from Baseline in the MGC total score over time regardless of rescue treatment 
• 
Change from Baseline in EQ-5D-Y over time regardless of rescue treatment 
• 
Change from Baseline in Neuro-QoL Pediatric Fatigue over time regardless of rescue treatment 
• 
MGFA Post-Interventional Status over time regardless of rescue treatment 
Total number and percentage of patients with clinical deteriorations, myasthenic crises, and rescue therapy use 
over time 
Extension Period Efficacy Endpoints: 
• 
Total number and percentage of patients with clinical deteriorations and/or myasthenic crises during 
the study 
• 
Total number and percentage of patients needing rescue therapy during the study 
• 
Change from Baseline in the QMG total score regardless of rescue treatment 
• 
Change from Baseline in the MG-ADL total score regardless of rescue treatment 
• 
Change from Baseline in the MGC total score regardless of rescue treatment 
• 
Change from Baseline in Neuro-QoL Pediatric Fatigue regardless of rescue treatment 
• 
Change from Baseline in EQ-5D-Y regardless of rescue treatment 
• 
Change from Baseline in MGFA Post-Interventional Status regardless of rescue treatment 
Safety Endpoints: 
• 
Frequency of adverse events (AEs) and serious adverse events (SAEs)  
• 
Frequency of adverse events leading to discontinuation 
• 
Incidence of antidrug antibodies (ADA)  
• 
Changes from Baseline in vital signs 
• 
Change from Baseline in electrocardiogram parameters 
• 
Change from Baseline in laboratory assessments 

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Pharmacokinetic and Pharmacodynamic Endpoints: 
• 
Pharmacokinetic/PD parameters including maximum plasma drug concentration (Cmax), terminal 
half-life (t½), trough (Ctrough), clearance, free complement protein 5 (C5), and in vitro hemolytic assay; 
assessed at Baseline and various time points including 24 hours (Day 2), Week 12, and Week 26 
during treatment 
Study Design and Methodology:  
This is an open-label, multicenter study to evaluate the efficacy, safety, PK, and PD of intravenous eculizumab 
in pediatric patients aged 6 to < 18 years with acetylcholine receptor (AChR)-antibody (Ab) positive refractory 
gMG. There will be 4 periods in this study: Screening Period (2 to 4 weeks), Primary Evaluation Treatment 
Period (26 weeks), Extension Period (up to an additional 208 weeks), and Follow-up Period (8 weeks). All 
patients who complete Week 26 of Study ECU-MG-303 will continue receiving eculizumab in the Extension 
Period of this study for up to an additional 208 weeks. The 8-week Follow-up Period is required following the 
last dose of study drug for all patients upon withdrawal or discontinuation from the study or upon completion of 
the study when the patient is not continuing to receive eculizumab treatment.  
Patients may continue use of acetylcholinesterase inhibitors (AChI), intravenous immunoglobulin (IVIg), and 
supportive immunosuppressive therapies (ISTs) during the study where applicable under certain restrictions.  
Screening Period (2 to 4 weeks): 
Patients will be screened for study eligibility only after obtaining the informed assent of the patient and 
informed permission of the parent or other legal guardian. 
To reduce the risk of meningococcal infection, all patients must be vaccinated against meningococcal infections 
within the 3 years prior to, or at the time of, initiating study drug. Patients who initiate study drug treatment less 
than 2 weeks after receiving a meningococcal vaccine must receive treatment with appropriate prophylactic 
antibiotics until 2 weeks after vaccination. Patients must remain within the current national vaccination 
guidelines or local practice for vaccination use with complement-inhibitors. In addition to meningococcal 
vaccination, patients must be vaccinated against Haemophilus influenzae (H influenzae) and Streptococcus 
pneumoniae (S pneumoniae), and strictly adhere to the national vaccination recommendations for each age 
group.  
The site must notify the Sponsor if any patient experiences signs and symptoms of MG worsening that require 
rescue or foreseeable imminent change to the background medication, during the Screening Period. Patients 
whose MG is unstable (as determined by the Investigator) during the Screening Period may be rescreened based 
on discussion and agreement between the Investigator and the Alexion Medical Monitor. 
Primary Evaluation Treatment Period (26 weeks): 
All patients will receive eculizumab by intravenous (IV) infusion during the open-label Primary Evaluation 
Treatment Period. Dosing will be initiated with a weekly weight-based induction regimen and, thereafter, will 
be every 2 weeks.  
Extension Period (up to 208 weeks): 
After completing the 26-week Primary Evaluation Treatment Period, patients will continue receiving 
eculizumab in the Extension Period of this study for up to an additional 208 weeks.  
Follow-up Period: 
• 
Safety Follow-up (8 weeks) 
Patients who do not enter the Extension Period from the Primary Evaluation Treatment Period, who withdraw 
from the study at any time, or who do not continue to receive eculizumab treatment upon study completion will 
be followed for at least 8 weeks from their last dose of eculizumab. Patients who complete the study and 
transition to uninterrupted treatment with commercially available eculizumab will not be required to complete 
an 8-week follow-up visit. 
 

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• 
Post-Treatment Follow-up (up to 1 year) 
The Sponsor may seek to collect follow-up information concerning MG status in patients post-treatment for up 
to 1 year from the end-of-study (EOS)/early termination (ET) visit. 
Clinical Deterioration and Rescue Therapies 
Allowed rescue therapy for clinical deterioration includes but is not limited to high-dose corticosteroids, plasma 
exchange (PE), or IVIg and is at the discretion of the treating physician.  
Number of Patients (Planned): At Least 12 
The study will enroll at least 12 eligible refractory pediatric gMG patients 12 to < 18 years of age to receive 
open-label eculizumab infusion in order to obtain at least 10 evaluable patients aged 12 to < 18 years for the 
primary endpoint taking into account potential dropouts. Additional patients between the ages of 6 and 12 may 
be enrolled, but will not be included in the primary analysis. 
After 6 patients complete their Week 26 assessments, if the observed standard deviation in change in QMG is 
8 or higher, the final sample size will be re-estimated to be at least 14 instead of 12 to preserve adequate power 
for testing the primary endpoint.  
The number of eligible refractory pediatric gMG patients aged 12 to < 18 entering on maintenance IVIg 
treatment in this study will be capped at 6 patients. These patients must have been on maintenance IVIg for at 
least 12 months and on a stable dose ≥ 3 months prior to Screening, with frequency and dose expected to remain 
stable during Screening and for 12 weeks following the first dose of study drug. Efforts will be made to enroll at 
least 1 patient in each geographic region (North America, EU, and APAC). There is no cap on patients 
6 to < 12 years of age. 
Diagnosis and Main Criteria for Inclusion/Exclusion:  
Inclusion Criteria: 
1. Male or female pediatric patients 6 to < 18 years of age at time of assent/consent. 
2. Patient’s legal guardian must be willing and able to give written informed permission and the patient 
must be willing to give written informed assent (if applicable as determined by the central or local 
Institutional Review Board [IRB]/Institutional [or Independent] Ethics Committee [IEC]) and comply 
with the study visit schedule.  
3. Parent or other legal guardian must be willing to comply with study requirements for the duration of 
the study.  
4. Vaccinated against N meningitidis within 3 years prior to, or at the time of, initiating eculizumab. 
Patients who initiate study drug treatment less than 2 weeks after receiving a meningococcal vaccine 
must receive appropriate prophylactic antibiotics until 2 weeks after the vaccination.  
5. Documented vaccination against H influenzae and S pneumoniae infections prior to dosing as per local 
and country specific immunization guidelines for the appropriate age group. 
6. Diagnosis of MG confirmed by positive serologic test for anti-AChR-Ab at Screening, and one of the 
following: 
a. 
History of abnormal neuromuscular transmission test demonstrated by single-fiber 
electromyography or repetitive nerve stimulation, or 
b. 
History of positive anticholinesterase test (eg, edrophonium chloride or neostigmine 
test), or 
c. 
Patient demonstrated improvement in MG signs on oral AChIs, as assessed by the 
Investigator. 
7. Presence of refractory gMG, defined as patients with gMG who have one or more of the following: 
a. 
Failed treatment ≥ 1 year with at least 1 IST, defined as:  

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i. Persistent weakness with impairment of activities of daily living, or 
ii. Myasthenia gravis exacerbation and/or crisis while on treatment, or  
iii. Intolerance to ISTs due to side effect or comorbid condition(s). 
Immunosuppressants include, but are not limited to, corticosteroids, azathioprine (AZA), 
mycophenolate mofetil (MMF), methotrexate (MTX), cyclosporine, tacrolimus, or 
cyclophosphamide. 
b. 
Require maintenance PE or IVIg to control symptoms (ie, patients who require PE or 
IVIg on a regular basis for the management of muscle weakness at least every 3 months 
over the last 12 months prior to Screening). 
c. 
In the opinion of the Investigator, MG poses a significant functional burden despite 
current MG treatment. 
8. Myasthenia Gravis Foundation of America (MGFA) Clinical Classification of Class II to IV at 
Screening. 
9. 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. 
10. All MG-specific treatment has been administered at a stable dosing regimen of adequate duration prior 
to Screening as follows: 
a. 
If patients who enter the study are receiving AZA, they must have been on AZA for 
≥ 6 months and have been on a stable dose for ≥ 2 months prior to Screening. 
b. 
If patients who enter the study are receiving other ISTs (ie, MMF, MTX, cyclosporine, 
tacrolimus, cyclophosphamide), they must have been on the IST for ≥ 3 months and 
have been on a stable dose for ≥ 4 weeks prior to Screening. 
c. 
If patients who enter the study are receiving maintenance IVIg at Screening, they must 
have been on maintenance IVIg for at least 12 months and on a stable dose for ≥ 3 
months prior to Screening, with the frequency and dose expected to remain stable during 
Screening and for 12 weeks following the first dose of study drug. All other patients 
must not have received maintenance IVIg within 3 months of Screening. 
d. 
If patients who enter the study are receiving oral corticosteroids, they must have been on 
a stable dose for ≥ 4 weeks prior to Screening. 
e. 
If patients who enter the study are receiving a cholinesterase inhibitor, they must have 
been on a stable dose for ≥ 2 weeks prior to Screening. 
11. Female patients of childbearing potential (ie, have achieved menarche) and male patients with female  
partners of childbearing potential must follow protocol-specified guidance for avoiding pregnancy 
while  
on treatment and for 5 months after the last dose of study drug.  
12. Male patients with a female spouse/partner of childbearing potential or a pregnant or breastfeeding 
spouse or partner must agree to use double barrier contraception (male condom plus appropriate barrier 
method for the female partner) while on treatment and for at least 5 months after the last dose of study 
drug.  
Exclusion Criteria:  
1. Parent or legal guardian is an Alexion employee.  
2. 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. 
3. History of thymectomy within 12 months prior to Screening. 
4. Weakness only affecting ocular or periocular muscles (MGFA Class I). 

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5. Myasthenia Gravis crisis or impending crisis at or during Screening (MGFA Class V). 
6. Are pregnant or lactating.  
7. 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. 
8. Unresolved meningococcal infection. 
9. For patients who are not receiving a stable maintenance dose of IVIg, as described in the Inclusion 
Criteria, use of IVIg (eg, as rescue therapy) within 4 weeks prior to first dose. 
10. Use of PE within 4 weeks prior to first dose. 
11. Use of rituximab within 6 months prior to first dose. 
12. Patients who are under 15 kg and are receiving maintenance IVIg. 
13. 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.  
14. Have previously received treatment with eculizumab or other complement inhibitors. 
15. Hypersensitivity to murine proteins or to one of the excipients of eculizumab. 
16. Any medical or psychological condition that, in the opinion of the Investigator, might interfere with the 
patient's participation in the study, poses any added risk for the patient, or confounds the assessment of 
the patient.  
17. Known or suspected history of drug or alcohol abuse or dependence within 1 year prior to the start of 
Screening. 

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Investigational Product, Dosage, and Mode of Administration:  
The bodyweight-categorized dosing regimens are provided in Table 1.  
Table 1: 
Weight-based Dosing Regimen of Eculizumab 
Weight Cohorta,b 
Induction Phase 
Maintenance Phase 
≥ 40 kg 
900 mg weekly × 4 doses 
1200 mg at Week 4; then every 2 weeks 
30 to < 40 kg 
600 mg weekly × 2 doses 
900 mg at Week 2; then every 2 weeks 
20 to < 30 kg 
600 mg weekly × 2 doses 
600 mg at Week 2; then every 2 weeks 
10 to < 20 kg 
600 mg weekly × 1 dose 
300 mg at Week 1; then every 2 weeks 
a Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies prohibit 
study drug to be prepared day-of visit, the weight from the most recent study visit should be used. 
bDuring the initial induction phase, if a patient’s weight increases or decreases resulting in a change in weight 
cohort, the Alexion medical monitor must be contacted prior to dosing. 
Supplemental Doses 
For patients who enter the study on maintenance IVIg treatment, a series of supplemental doses of eculizumab 
will be administered to account for the anticipated approximately 50% increase in eculizumab clearance 
according to Table 2. 
Table 2: 
Supplemental Dosing Regimen of Eculizumab in Patients Receiving Maintenance IVIg  
Weight 
Cohorta,b 
Induction Phase 
Supplemental 
Dose 
Induction Phase 
Total Dose 
Maintenance 
Phase 
Supplemental 
Dose 
Maintenance 
Phase 
Total Dose 
≥ 40 kg 
600 mg 
1500 mg 
600 mg 
1800 mg 
30 to < 40 kg 
300 mg 
900 mg 
600 mg 
1500 mg 
20 to < 30 kg 
300 mg 
900 mg 
300 mg 
900 mg 
10 to < 20 kgc 
300 mg 
900 mg 
300 mg 
600 mg 
a Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies prohibit study drug to 
be prepared day-of visit, the weight from the most recent study visit should be used. 
b During the initial induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort, the 
Alexion medical monitor must be contacted prior to dosing. 
c Only patients in 15-20 kg weight category to be included in this group. 
Notes: The timing of supplemental eculizumab dosing varies by IVIg frequency and is provided below: 
• 
If a patient continues to receive IVIg treatment at a dose cycle interval equal to or more frequent than every 
4 weeks during eculizumab treatment, a supplemental dose will be administered at the same time that each 
scheduled dose of eculizumab is administered. 
• 
If a patient receives IVIg treatment at a dose cycle interval less frequent than every 4 weeks during eculizumab 
treatment, a supplemental dose will be administered following the last dose of the IVIg infusion cycle at the 
next scheduled eculizumab dose.  
• 
If a patient receives IVIg treatment within 4 weeks prior to receiving the first dose of eculizumab, a 
supplemental dose of eculizumab will be administered at the same time that the first dose of eculizumab is 
administered (ie, the total dose is the supplemental dose plus the first scheduled dose). 
When IVIg is administered as acute rescue therapy for clinical deterioration, no supplemental dose of 
eculizumab should be administered. However, if a patient receives more than 1 dose cycle of IVIg as rescue 
therapy within a 12-week period, supplemental eculizumab should be administered after the last dose of the 
second IVIg cycle and at the end of each subsequent IVIg dose cycle within the 12-week period in accordance 
with Table 2.  
For patients who undergo PE, plasmapheresis (PP), or receive fresh frozen plasma (FFP), supplemental 
eculizumab dosing should be administered as shown in Table 3. In addition, patients are to continue study drug 
infusion according to the protocol-specified dosing regimen. If the PE/PP/FFP is on the day of a scheduled 

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study drug infusion, the scheduled dose of study drug (instead of the supplemental dose) should be 
administered. 
Table 3: 
Supplemental Dosing Regimen of Eculizumab after Plasma Exchange/Plasma Infusion 
Intervention 
Type of 
Intervention 
Most Recent 
Eculizumab Dose 
Supplemental Eculizumab 
Dose With Each Plasma 
Exchange/Plasma Infusion 
Intervention 
Timing of 
Supplemental 
Eculizumab dose 
Plasmapheresis or 
plasma exchange 
300 mg 
300 mg per each plasmapheresis 
or plasma exchange session 
Within 1 to 2 hours after 
each plasmapheresis or 
plasma exchange 
600 mg or more 
600 mg per each plasmapheresis 
or plasma exchange session 
Fresh frozen plasma 
infusion 
300 mg or more 
300 mg per infusion of fresh 
frozen plasma 
Approximately 
60 minutesa prior to each 
infusion of fresh frozen 
plasma 
a Supplemental dosing of eculizumab should occur 60 ± 15 minutes prior to each infusion of fresh frozen 
plasma. 
Statistical Methods: 
When the target number of patients has been achieved that have completed the 26-week Primary Evaluation 
Treatment Period, all patients including patients who discontinued prior to 26 weeks will be analyzed for 
efficacy, safety, and PK/PD. The planned statistical methods and analyses will be detailed in the statistical 
analysis plan (SAP). Additional interim analyses during the Extension Period may be performed at the 
discretion of the Sponsor. 
Summary statistics for continuous variables will minimally include the number of patients, mean, standard 
deviation, minimum, median, and maximum. For categorical variables, frequencies and percentages will be 
presented. Graphical displays will be provided as appropriate. All statistical analyses will be performed based 
on a 2-sided Type I error of 5% unless noted otherwise. Missing data will not be imputed. 
Efficacy: 
Efficacy analyses will be performed on the Full Analysis Set (FAS), which consists of all patients who received 
at least 1 dose of eculizumab. Analyses of the primary efficacy endpoint and secondary efficacy endpoints will 
be performed on a modified FAS (mFAS), which consists of FAS patients 12 to <18 years of age. 
For all patients in the mFAS, the primary endpoint and the secondary endpoints that involve changes from 
Baseline will be analyzed at a particular visit based on a Repeated-Measures model with effects for the 
particular baseline covariate and visit. Confidence intervals and p-values will be presented by visit. Graphical 
displays over time will be produced by visit. Missing efficacy endpoint assessments will not be imputed.  
For all patients in the mFAS, the proportion of patients with at least a 3-point reduction in the MG-ADL total 
score from Baseline will be summarized by visit over time. Confidence intervals and p-values will be presented. 
Similar analyses will be performed for at least a 5-point reduction in the QMG total score from Baseline. These 
analyses will be done with no rescue and regardless of rescue. 
Descriptive analysis will be used for patients from 6 to < 12 years of age. 
Safety: 
Safety analyses will be performed on the Safety Set, which includes all patients who have received at least 
1 dose of eculizumab. All safety data will be provided in patient listings. 

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Physical Examinations and Vital Signs: 
The number and percentage of patients with abnormal physical examinations will be summarized by visit. 
Absolute values and change from Baseline in vital signs (including weight and height) will be summarized by 
visit.  
Listings of physical examinations and vital signs will be produced.  
Clinical Laboratory Tests: 
Absolute values and change from Baseline over time in clinical chemistry and hematology results will be 
summarized descriptively. Laboratory data abnormality (low, normal, high) with respect to reference range will 
be summarized using shift analysis compared to the abnormality at Baseline. Listings of patients with abnormal 
laboratory values will be provided. 
Adverse Events: 
Pretreatment SAEs, defined as any SAE that starts after signing the informed consent form (ICF) but before the 
first dose of study drug, will be summarized in a listing. 
Treatment-emergent AEs (TEAEs), defined as any AE that starts during or after the first dose of study drug, 
will be summarized as serious and nonserious events. 
The incidence of AEs will be summarized by Medical Dictionary for Regulatory Activities (MedDRA) System 
Organ Class and Preferred Term, seriousness, severity, and relationship to treatment. All AEs will be coded 
using MedDRA version current at the time of the analysis. 
Immunogenicity: 
Immunogenicity findings, including the incidence of positive ADAs to eculizumab will be summarized by visit.  
Pharmacokinetics/Pharmacodynamics: 
Pharmacokinetic and PD laboratory measurements will be summarized for both Induction and Maintenance 
Treatment Period. Pharmacokinetic and PD data will be explored using modeling and simulation methods for 
evaluating the appropriateness of studied pediatric dose. 

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TABLE OF CONTENTS, LIST OF TABLES AND LIST OF FIGURES  
SPONSOR SIGNATURE PAGE ....................................................................................................2 
INVESTIGATOR’S AGREEMENT ...............................................................................................3 
PROCEDURES IN CASE OF EMERGENCY ...............................................................................4 
1. 
SYNOPSIS ...................................................................................................................5 
TABLE OF CONTENTS, LIST OF TABLES AND LIST OF FIGURES ...................................14 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS ................................................22 
2. 
INTRODUCTION ......................................................................................................24 
2.1. 
Epidemiology ..............................................................................................................24 
2.2. 
Unmet Medical Need ..................................................................................................24 
2.3. 
Eculizumab Clinical Program in Refractory Generalized Myasthenia Gravis ...........25 
2.4. 
Eculizumab Dose in Pediatric Refractory gMG Patients ...........................................25 
2.5. 
Rationale for Eculizumab Refractory gMG Pediatric Study ......................................25 
2.6. 
Benefit and Risk Assessment ......................................................................................26 
2.6.1. 
Potential Benefits ........................................................................................................26 
2.6.2. 
Identified and Potential Risks .....................................................................................26 
2.6.2.1. 
Meningococcal Infection and Other Encapsulated Bacterial Infections .....................26 
2.6.2.2. 
Immunogenicity ..........................................................................................................26 
3. 
STUDY OBJECTIVES ..............................................................................................27 
3.1. 
Primary Objective .......................................................................................................27 
3.2. 
Secondary Objectives .................................................................................................27 
3.3. 
Extension Period Objectives .......................................................................................27 
4. 
STUDY DESIGN .......................................................................................................28 
4.1. 
Overall Design ............................................................................................................28 
4.1.1. 
Screening Period (2 to 4 weeks) .................................................................................29 
4.1.2. 
Primary Evaluation Treatment Period (26 weeks) ......................................................29 
4.1.3. 
Extension Period (up to an additional 208 weeks) .....................................................30 
4.1.4. 
Follow-up Period: Safety Follow-up (8 weeks) ..........................................................30 
4.1.5. 
Post-Treatment Follow-up (up to 1 year) ...................................................................30 
4.1.6. 
Clinical Deterioration and Rescue Therapies .............................................................30 
4.1.7. 
Unscheduled Visits .....................................................................................................31 
4.1.8. 
Study Completion .......................................................................................................31 

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4.2. 
Study Flow Diagram and Schedule of Assessments ...................................................31 
4.3. 
Protocol Definitions ....................................................................................................71 
4.3.1. 
Clinical Deterioration and Rescue Therapy ................................................................71 
4.3.2. 
Clinical Evaluator .......................................................................................................71 
4.3.3. 
Responsibilities for Myasthenia Gravis Assessments ................................................71 
5. 
STUDY POPULATION .............................................................................................72 
5.1. 
Inclusion Criteria ........................................................................................................72 
5.2. 
Exclusion Criteria .......................................................................................................74 
5.3. 
Rationale for Inclusion or Exclusion ..........................................................................74 
5.4. 
Discontinuations .........................................................................................................75 
5.4.1. 
Discontinuation of Patients .........................................................................................75 
5.4.2. 
Discontinuation of Study Sites/Site Terminated .........................................................76 
5.4.3. 
Discontinuation of the Study/Study Terminated ........................................................76 
6. 
STUDY DRUG MATERIALS AND MANAGEMENT ...........................................77 
6.1. 
Study Drug ..................................................................................................................77 
6.1.1. 
Study Drug Labeling ...................................................................................................77 
6.1.2. 
Study Drug Storage .....................................................................................................77 
6.1.3. 
Study Drug Preparation ..............................................................................................77 
6.1.4. 
Study Drug Administration .........................................................................................78 
6.1.5. 
Study Drug Accountability .........................................................................................78 
6.1.6. 
Study Drug Handling and Disposal ............................................................................79 
6.2. 
Dosing Regimen .........................................................................................................79 
6.2.1. 
Rationale for Selection of Doses in the Study ............................................................79 
6.2.2. 
Dosing Regimen Preparation and Administration ......................................................80 
6.2.3. 
Supplemental Eculizumab Doses in Patients Receiving Maintenance IVIg 
Treatment ....................................................................................................................81 
6.2.4. 
Supplemental Eculizumab Doses Following Rescue Therapy ...................................82 
6.3. 
Concomitant Medications ...........................................................................................83 
6.3.1. 
Allowed Medications ..................................................................................................83 
6.3.2. 
Disallowed Medications .............................................................................................84 
6.3.3. 
Clinical Deterioration and Rescue Therapies .............................................................84 
6.3.4. 
Vaccination .................................................................................................................84 
6.4. 
Treatment Compliance ................................................................................................85 

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6.5. 
Continued Access to Study Drug ................................................................................85 
7. 
ASSESSMENT OF EFFICACY ................................................................................86 
7.1. 
Quantitative Myasthenia Gravis Score .......................................................................86 
7.2. 
Myasthenia Gravis Activities of Daily Living Score .................................................86 
7.3. 
Myasthenia Gravis Composite Score ..........................................................................86 
7.4. 
Myasthenia Gravis Foundation of America Post-Intervention Status ........................87 
7.5. 
European Quality of Life 5-Dimension ......................................................................87 
7.6. 
Neurological Quality of Life Fatigue Questionnaire ..................................................87 
8. 
ADDITIONAL ASSESSMENTS ...............................................................................88 
8.1. 
Myasthenia Gravis Disease Biomarker ......................................................................88 
8.2. 
Pharmacokinetics and Pharmacodynamics .................................................................88 
9. 
ASSESSMENT OF SAFETY .....................................................................................89 
9.1. 
Physical Examinations ................................................................................................89 
9.2. 
Vital Signs ..................................................................................................................89 
9.3. 
Laboratory Assessments (Pregnancy Screen, Serum Chemistry, and 
Hematology) ...............................................................................................................89 
9.4. 
Electrocardiograms .....................................................................................................90 
9.5. 
Immunogenicity ..........................................................................................................90 
9.6. 
Adverse Event Management .......................................................................................90 
9.6.1. 
Detection of Adverse Events ......................................................................................90 
9.6.2. 
Definition of Adverse Event .......................................................................................90 
9.6.2.1. 
Procedure ....................................................................................................................91 
9.6.2.2. 
Abnormal Test Findings .............................................................................................91 
9.6.2.3. 
Lack of Efficacy .........................................................................................................91 
9.6.2.4. 
Development of Myasthenia Gravis Clinical Deterioration .......................................91 
9.6.3. 
Recording Adverse Events .........................................................................................91 
9.6.4. 
Severity Assessment ...................................................................................................92 
9.6.5. 
Causality Assessment .................................................................................................92 
9.6.6. 
Definition of Serious Adverse Event ..........................................................................92 
9.6.7. 
Serious Adverse Event With Outcome of Death ........................................................93 
9.6.8. 
Hospitalization ............................................................................................................93 
9.6.9. 
Collection and Reporting of Adverse Events .............................................................94 
9.6.9.1. 
All Adverse Events .....................................................................................................94 

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9.6.9.2. 
Serious Adverse Events ..............................................................................................94 
9.6.9.3. 
Suspected Unexpected Serious Adverse Reactions ....................................................95 
9.6.10. 
Sponsor Reporting Requirements ...............................................................................95 
9.6.11. 
Investigator Reporting Requirements .........................................................................95 
9.7. 
Exposure During Pregnancy and Breastfeeding .........................................................95 
9.8. 
Safety Monitoring .......................................................................................................96 
10. 
STATISTICAL CONSIDERATIONS .......................................................................97 
10.1. 
General Considerations ...............................................................................................97 
10.2. 
Hypotheses ..................................................................................................................97 
10.3. 
Determination of Sample Size ....................................................................................97 
10.3.1. 
Interim Monitoring of Variability and Sample Size Re-assessment ..........................98 
10.4. 
Analysis Sets ...............................................................................................................98 
10.4.1. 
Full Analysis Set .........................................................................................................98 
10.4.2. 
Safety Set ....................................................................................................................99 
10.4.3. 
Other Analysis Set ......................................................................................................99 
10.5. 
Demographics and Baseline Characteristics ...............................................................99 
10.6. 
Patient Disposition ......................................................................................................99 
10.7. 
Prior and Concomitant Medications ...........................................................................99 
10.8. 
Efficacy Analyses .......................................................................................................99 
10.8.1. 
Primary Efficacy Analysis ..........................................................................................99 
10.8.1.1. 
Analysis of Primary Endpoint based on Evaluable Patients .....................................100 
10.8.2. 
Analyses of Secondary Efficacy Endpoints ..............................................................100 
10.8.3. 
Extension Period Efficacy Endpoints .......................................................................101 
10.9. 
Safety Analyses ........................................................................................................101 
10.9.1. 
Physical Examinations ..............................................................................................101 
10.9.2. 
Vital Signs ................................................................................................................101 
10.9.3. 
Adverse Events .........................................................................................................102 
10.9.4. 
Clinical Laboratory Tests .........................................................................................102 
10.9.5. 
Immunogenicity ........................................................................................................102 
10.10. 
Pharmacokinetic/Pharmacodynamic Analyses .........................................................102 
10.11. 
Other Statistical Issues ..............................................................................................102 
10.11.1. 
Missing or Invalid Data ............................................................................................102 
10.12. 
Interim Analyses .......................................................................................................102 

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10.13. 
Sample Size Re-Estimation ......................................................................................103 
11. 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS ................................................................................................104 
11.1. 
Study Monitoring ......................................................................................................104 
11.2. 
Audits and Inspections ..............................................................................................104 
11.3. 
Institutional Review Board / Independent Ethics Committee ..................................105 
11.4. 
Quality Control and Quality Assurance ....................................................................105 
11.5. 
Ethics ........................................................................................................................105 
11.5.1. 
Ethics Review ...........................................................................................................105 
11.5.2. 
Ethical Conduct of the Study ....................................................................................105 
11.6. 
Informed Consent and Assent ...................................................................................105 
11.7. 
Data Protection .........................................................................................................106 
11.8. 
Changes or Deviations to Protocol ...........................................................................106 
11.9. 
Data Handling and Recordkeeping ...........................................................................106 
11.9.1. 
Inspection of Records ...............................................................................................106 
11.9.2. 
Retention of Records ................................................................................................107 
11.10. 
Contraceptive Guidance ............................................................................................107 
11.11. 
Publication Policy .....................................................................................................107 
12. 
LIST OF REFERENCES ..........................................................................................108 
APPENDIX 1. .................... QUANTITATIVE MYASTHENIA GRAVIS SCORE FOR DISEASE 
SEVERITY ...............................................................................................................109 
APPENDIX 2. ................. MODIFIED QUANTITATIVE MYASTHENIA GRAVIS SCORE FOR 
DISEASE SEVERITY ..............................................................................................110 
APPENDIX 3. ............. MYASTHENIA GRAVIS ACTIVITIES OF DAILY LIVING (MG-ADL) 
PROFILE ..................................................................................................................111 
APPENDIX 4. ....................................................................... MYASTHENIA GRAVIS COMPOSITE 
SCALE ......................................................................................................................112 
APPENDIX 5. .................................. EUROPEAN QUALITY OF LIFE 5-DIMENSION – YOUTH 
VERSION .................................................................................................................113 
APPENDIX 6. .............. EUROPEAN QUALITY OF LIFE 5-DIMENSION – YOUTH VERSION 
(PROXY) ..................................................................................................................115 
APPENDIX 7. ................................................ NEUROLOGICAL QUALITY OF LIFE PEDIATRIC 
FATIGUE .................................................................................................................117 
APPENDIX 8. ... PROMIS PARENT PROXY ITEM BANK V2.0 – FATIGUE – SHORT FORM 
10A ...........................................................................................................................118 

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APPENDIX 9. .................. MYASTHENIA GRAVIS FOUNDATION OF AMERICA CLINICAL 
CLASSIFICATION ..................................................................................................119 
APPENDIX 10. ................ MYASTHENIA GRAVIS FOUNDATION OF AMERICA THERAPY 
STATUS ...................................................................................................................120 
APPENDIX 11. ........................ MYASTHENIA GRAVIS FOUNDATION OF AMERICA POST-
INTERVENTIONAL STATUS ...............................................................................121 
APPENDIX 12. .................................................... SUMMARY OF LABORATORY PANELS AND 
TESTS .......................................................................................................................122 
APPENDIX 13. .. COLLECTION OF FOLLOW-UP INFORMATION FROM PATIENTS WHO 
WITHDRAW FROM THE STUDY ........................................................................123 
 

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LIST OF TABLES 
Table 1: 
Weight-based Dosing Regimen of Eculizumab ..........................................................11 
Table 2: 
Supplemental Dosing Regimen of Eculizumab in Patients Receiving 
Maintenance IVIg .......................................................................................................11 
Table 3: 
Supplemental Dosing Regimen of Eculizumab after Plasma 
Exchange/Plasma Infusion Intervention .....................................................................12 
Table 4: 
Schedule of Assessments Part I: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 
20 to < 30 kg ...............................................................................................................33 
Table 5: 
Schedule of Assessments Part II: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 
20 to < 30 kg ...............................................................................................................37 
Table 6: 
Schedule of Assessments Part I: Weight Cohort 10 to < 20 kg ..................................40 
Table 7: 
Schedule of Assessments Part II: Weight Cohort 10 to < 20 kg ................................44 
Table 8: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All 
Weight Cohorts) ..........................................................................................................47 
Table 9: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All 
Weight Cohorts) ..........................................................................................................54 
Table 10: Schedule of Assessments (Extension Period): Year 2 through Year 5 (All 
Weight Cohorts) ..........................................................................................................61 
Table 11: Schedule of Assessments (Extension Period): Year 2 through Year 5 (All 
Weight Cohorts) ..........................................................................................................68 
Table 12: Responsibilities for MG Assessments ........................................................................71 
Table 13: Study Drug ..................................................................................................................77 
Table 14: Study Drug Reconstitution .........................................................................................78 
Table 15: Weight-based Dosing Regimen of Eculizumab ..........................................................80 
Table 16: Supplemental Dosing Regimen of Eculizumab in Patients Receiving 
Maintenance IVIg .......................................................................................................82 
Table 17: Supplemental Dosing Regimen of Eculizumab for Plasma Exchange/Plasma 
Infusion .......................................................................................................................83 
Table 18: Causality Assessment Descriptions ............................................................................92 
Table 19: Mean [±SD] Change from Baseline in QMG and MG-ADL for Younger 
Patients (Data from Studies ECU-MG-301 and ECU-MG-302) ................................98 
 
 

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LIST OF FIGURES 
Figure 1: 
Flow Diagram for Study Design .................................................................................32 
 

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LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS 
Abbreviations and Terms 
Definitions 
Ab, Abs 
antibody, antibodies 
AChR 
acetylcholine receptor  
AChI 
acetylcholinesterase inhibitor 
ADA 
antidrug antibody 
AE 
adverse event 
aHUS 
atypical hemolytic uremic syndrome  
AZA 
azathioprine 
C5 
complement protein 5 
Cmax 
maximum plasma drug concentration 
ECG 
electrocardiogram  
eCRF 
electronic Case Report Form 
EOS 
end-of-study 
EQ-5D-Y 
European Quality of Life 5-Dimension Youth version 
ET 
early termination 
EU 
European Union  
FAS 
Full Analysis Set 
FFP 
fresh frozen plasma 
FVC 
forced vital capacity 
GCP 
Good Clinical Practices 
GDS 
Global Drug Safety 
gMG 
generalized myasthenia gravis 
H influenzae 
Haemophilus influenzae 
IB 
Investigator’s Brochure 
ICF 
informed consent form 
ICH 
International Council on Harmonization 
IEC 
Institutional (or Independent) Ethics Committee 
IRB 
Institutional Review Board 
IRT 
Interactive Response Technology 
IST 
immunosuppressant therapy 
IV 
intravenous  
IVIg 
intravenous immunoglobulin  
MedDRA 
Medical Dictionary for Regulatory Activities 
mFAS 
Modified Full Analysis Set 
MG 
myasthenia gravis 
MG-ADL 
Myasthenia Gravis Activities of Daily Living profile 
MGC 
Myasthenia Gravis Composite Scale 
MGFA 
Myasthenia Gravis Foundation of America 
MMF 
mycophenolate mofetil 
MMT 
manual muscle test 
MTX 
methotrexate 
N meningitidis 
Neisseria meningitidis 
Neuro-QoL Fatigue 
Neurological Quality of Life-Fatigue questionnaire 
NMJ 
neuromuscular junction 
PD 
pharmacodynamics 
PDCO 
Paediatric Committee of the European Medicines Agency 
PE 
plasma exchange  
PI 
Principal Investigator 
PIS 
post-intervention status 
PK 
pharmacokinetics  
PNH 
paroxysmal nocturnal hemoglobinuria 

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Abbreviations and Terms 
Definitions 
PP 
plasmapheresis 
PT 
preferred term 
QMG 
Quantitative Myasthenia Gravis 
S pneumoniae 
Streptococcus pneumoniae 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
SOC 
System Organ Class 
TEAE 
treatment-emergent adverse event 
VAS 
Visual Analog Scale 
WHODrug 
World Health Organization Drug Dictionary 

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2. 
INTRODUCTION  
Myasthenia gravis (MG) is a rare, chronic, autoimmune disease of neuromuscular transmission 
that manifests clinically in both children and adults as fluctuating weakness in voluntary muscles 
that is exacerbated during periods of activity and improves after periods of rest (Barnett, 2014; 
Sieb, 2014). The pathological hallmark of both juvenile and adult forms of MG is production of 
antibodies (Abs) against the components of the postsynaptic membrane at the neuromuscular 
junction (NMJ), predominantly the acetylcholine receptor (AChR). Although adults and 
juveniles with MG share aspects of presentation and pathophysiology, there are differences in 
epidemiology and prognosis. Additionally, the ongoing development of children and adolescents 
complicate therapeutic decision making in young patients with MG.  
2.1. 
Epidemiology 
Myasthenia gravis in children and adolescents is uncommon and comprises approximately 10% 
to 20% of all MG cases (Snead, 1980; Szorbor, 1988-1989). The annual incidence of MG in 
children and adolescents has been reported as approximately 1.1 per million in North America 
and 1 to 5 per million in Europe (Phillips, 1992; Andrews, 2004; McGrogan, 2010;  
Della Marina, 2014), with incidence and prevalence varying geographically. Ten percent of 
patients with MG have disease limited to ocular muscles, while the remaining 90% have 
generalized MG (gMG), with muscle weakness involving neck, head, spine, bulbar, respiratory, 
or limb muscles.  
Clinically, gMG in children and adolescents presents as fluctuating and fatigable skeletal muscle 
weakness, which improves with rest, similar to manifestations of the disease in adults. Clinical 
features may include predominantly ocular symptoms with ptosis, ophthalmoplegia, and/or 
diplopia. Bulbar symptoms of dysphagia and/or dysphonia may be present, as well as generalized 
symptoms of exercise intolerance and weakness. As with adults, respiratory muscle weakness 
may be a feature of MG in children and adolescents and may lead to respiratory distress or even 
respiratory failure, particularly if left untreated. In children and adolescents with MG, 
prepubertal patients tend to be more clinically distinct compared to adults with MG, as compared 
with the pubertal/postpubertal group who share more features with adult-onset MG. 
2.2. 
Unmet Medical Need 
While there is no cure for MG, there are a variety of therapies that reduce muscle weakness and 
improve neuromuscular function. Currently available treatments for MG aim to modulate 
neuromuscular transmission, inhibit the production or effects of pathogenic antibodies, or inhibit 
inflammatory cytokines (Kim, 2011). There is currently no specific treatment that targets the 
underlying pathophysiology of NMJ injury specifically: anti-AChR Ab-AChR interactions 
resulting in complement activation via the classical pathway and inflammation, with the resultant 
destruction of the NMJ. With current standard of care, which combines cholinesterase inhibitors, 
corticosteroids and immunosuppressive therapies (ISTs; most commonly azathioprine [AZA], 
cyclosporine, and mycophenolate mofetil [MMF]), the majority of MG patients have their 
disease reasonably well controlled. For the cohort of refractory patients who do not respond 
adequately to ISTs or cannot tolerate ISTs and those who require repeated treatments with 
plasma exchange (PE) and/or intravenous immunoglobulin (IVIg) to maintain clinical stability 
(Conti-Fine, 2006), there is a medical need for alternative treatment strategies targeting different 

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pathophysiological aspects of the disease. There are currently no approved therapies specific for 
the treatment of refractory gMG in pediatric patients. Since complement activation plays a 
pivotal role in the pathophysiology of MG (Vincent, 2002; Conti-Fine, 2006), eculizumab, a 
terminal complement inhibitor, may benefit patients who continue to have generalized weakness 
and bulbar signs and symptoms despite current standard of care.  
2.3. 
Eculizumab Clinical Program in Refractory Generalized Myasthenia 
Gravis 
Alexion has completed 2 clinical studies in adults with refractory gMG, with a Phase 3 extension 
study currently ongoing.  
The totality of the eculizumab clinical data from the pivotal Study ECU-MG-301 and the 
consistency of the eculizumab treatment effect observed over a multitude of independent but 
complementary MG-specific outcome measures have established substantial evidence of 
effectiveness of eculizumab in the treatment of adults with refractory gMG. The safety profile of 
eculizumab observed in adult refractory gMG patients was consistent with the well-established 
safety profile of the drug with over 10 years of clinical and postmarketing use. The data observed 
in the ongoing Study ECU-MG-302 support the long-term safety and maintenance of clinical 
response of eculizumab in adults with refractory gMG.  
Based on the data from these 3 studies, eculizumab was approved for AChR Ab-positive adults 
with refractory gMG in the EU (14 August 2017), gMG in the US (23 October 2017), and gMG 
with symptoms that are difficult to control with high-dose IVIg therapy or PE in Japan 
(25 December 2017). 
Refer to the current Investigator’s Brochure (IB) for further information on the safety and 
efficacy data of eculizumab. 
2.4. 
Eculizumab Dose in Pediatric Refractory gMG Patients 
The safety and efficacy of the 900 mg/1200 mg dose regimen was previously established in 
adults with refractory gMG in Study ECU-MG-301. The categorical dose regimen selected for 
this pediatric study (Study ECU-MG-303) is based on the body weight of the pediatric patient, 
thus allowing for the accommodation of weight changes during the development and maturation 
of the patient. For pediatric gMG patients on stable, maintenance IVIg treatment, a series of 
supplemental doses of eculizumab must be administered. If a patient undergoes plasmapheresis 
(PP)/PE/fresh frozen plasma (FFP) for clinical deterioration during the study, a supplemental 
dose of study drug must be administered. The proposed pediatric dose regimen is supported by 
PK/PD modeling and simulation using data from the MG adult studies, and is identical to that 
approved for pediatric patients with aHUS, except for the supplemental dose with IVIg 
administration.  
2.5. 
Rationale for Eculizumab Refractory gMG Pediatric Study 
The pathophysiology of MG involves auto-Ab-driven uncontrolled terminal complement 
activation with membrane attack complex dependent lysis and activation, which causes 
inflammation at the NMJ, AChR loss, and failure of neuromuscular transmission. Eculizumab 
binds specifically to the human terminal complement component 5 (C5), inhibiting C5 enzymatic 

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cleavage and thereby preventing terminal complement activation. The mechanism of action of 
eculizumab as a potent and selective terminal complement inhibitor supports its use in the 
management of refractory gMG mediated by complement-activating Abs directed against the 
NMJ in both adults and children/adolescents. 
The favorable benefit-risk for eculizumab in the treatment of adult patients with refractory gMG 
that was established in the adult clinical program provides the basis for studying eculizumab in 
the pediatric patient population.  
The clinical development program in adults with refractory gMG has informed the methodology 
of the study design and investigational plan for this first clinical study in pediatric refractory 
gMG patients. 
2.6. 
Benefit and Risk Assessment 
2.6.1. 
Potential Benefits 
Given that MG is a chronic disease, pediatric patients with refractory gMG are at risk of 
substantial morbidity and mortality, including profound weakness, slurred speech, dysarthria, 
choking, the inability to swallow hard and/or soft foods, disorienting vision, shortness of breath 
(both with activity and at rest), significant upper and lower extremity weakness, substantially 
impaired mobility, marked reductions in ability to perform activities of daily living, extreme 
fatigue, and episodes of pulmonary failure requiring mechanical ventilation, all of which can 
have a dramatic impact on quality of life. As there is currently no approved therapy for refractory 
gMG in the pediatric population, the benefit of sustained terminal complement inhibition and the 
consistency of the eculizumab treatment effect observed in the adult population support the 
potential clinical benefit of eculizumab in pediatric refractory gMG patients. 
2.6.2. 
Identified and Potential Risks 
2.6.2.1. 
Meningococcal Infection and Other Encapsulated Bacterial Infections 
Eculizumab blocks terminal complement; therefore, patients may have increased susceptibility to 
encapsulated bacterial infections, in particular Neisseria meningitidis (N meningitidis). Specific 
risk mitigation measures in place are described in Section 6.3.4. 
2.6.2.2. 
Immunogenicity 
As with any humanized monoclonal Ab, administration of eculizumab may be associated with 
the development of anti-drug antibodies. Monitoring of immunogenicity is planned, as described 
in Section 4.2 and Section 9.5. 

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3. 
STUDY OBJECTIVES 
3.1. 
Primary Objective 
The primary objective of this study is to evaluate the efficacy of eculizumab in the treatment of 
pediatric refractory gMG based on change from Baseline in the Quantitative Myasthenia Gravis 
score for disease severity (QMG). 
3.2. 
Secondary Objectives 
The secondary objectives of the study are to: 
• Evaluate the safety and tolerability of eculizumab in the treatment of pediatric 
refractory gMG 
• Evaluate the efficacy of eculizumab in the treatment of pediatric refractory gMG 
based on change from Baseline in the following measures: 
− Myasthenia Gravis Activities of Daily Living profile (MG-ADL)  
− Myasthenia Gravis Composite score (MGC)  
• Evaluate the effect of eculizumab on the following quality of life measures: 
− European Quality of Life 5-Dimension Youth (EQ-5D-Y) Questionnaire – 
EQ-5D-Y Proxy version for patients < 8 years of age or EQ-5D-Y version for 
patients ≥ 8 years of age 
− Neurological Quality of Life Pediatric Fatigue (Neuro-QoL Pediatric Fatigue) 
Questionnaire for patients ≥ 8 years of age 
− PROMIS Parent Proxy Item Bank v2.0 – Fatigue – Short Form 10a for patients 
< 8 years of age 
• Evaluate MGFA Post-Interventional Status over time  
• Describe total number and percentage of patients with clinical deteriorations, 
myasthenic crises, and rescue therapy use over time 
• Describe the pharmacokinetics (PK) and pharmacodynamics (PD) of eculizumab 
treatment in pediatric refractory gMG patients to confirm the pediatric dosing 
selected through modeling and simulation following 26 weeks of eculizumab 
treatment 
3.3. 
Extension Period Objectives 
The Extension Period objectives are to: 
• Characterize long-term safety beyond 26 weeks of eculizumab treatment in pediatric 
patients with refractory gMG 
• Characterize long-term efficacy beyond 26 weeks of eculizumab treatment in 
pediatric patients with refractory gMG 

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4. 
STUDY DESIGN 
4.1. 
Overall Design  
Study ECU-MG-303 is an open-label, multicenter study to evaluate the efficacy, safety, PK, and 
PD of eculizumab for the treatment of pediatric patients aged 6 to < 18 years with AChR-Ab 
positive refractory gMG. At least 12 eligible patients aged 12 to < 18 years are planned to be 
enrolled in the study and receive eculizumab infusion to obtain at least 10 evaluable patients 
aged 12 to < 18 years for the primary endpoint taking into account potential dropouts. There will 
be 4 periods in this study:  
• Screening Period (2-4 weeks) 
• Primary Evaluation Treatment Period (26 weeks) 
• Extension Period (up to an additional 208 weeks) 
• Follow-up Period (8 weeks)  
Patients may continue to receive AChI, IVIg, and ISTs during the study where applicable under 
certain restrictions. For patients who enter the study receiving any background therapy, the dose 
and frequency may not be changed during the Primary Evaluation Treatment Period before 
Week 12, unless deemed necessary per the Investigator based on clinical safety evaluation and 
Sponsor approval is obtained. Dose change with background medication is permitted after 
Week 12 at the Investigator’s discretion and with Sponsor notification. During the Extension 
Period, changes in background medications will be permitted at the Investigator’s discretion and 
with Sponsor notification.  
If a patient withdraws from the study or discontinues eculizumab treatment at any time, the 
patient will be required to complete an Early Termination (ET) visit at the time of withdrawal 
and a Follow-up visit 8 weeks following the last dose of study drug. The overall study duration 
for an individual patient can be up to 246 weeks (approximately 4.7 years) from the Screening 
Period through the Follow-up Period.  
This pediatric study is designed to assess the efficacy and safety of eculizumab in AChR-Ab 
positive refractory pediatric gMG patients, similar to what has been demonstrated in patients 
aged ≥ 18 years in Study ECU-MG-301 (a randomized, double-blind, placebo-controlled study). 
The similar pathogenic autoantibody profile (AChR-Ab), pathophysiology, clinical presentation, 
and treatment responses in AChR-Ab positive patients aged ≥ 18 years and pediatric patients, 
combined with the well-understood mechanism of action of eculizumab in inhibiting terminal 
complement, predict a similar efficacy profile of eculizumab in patients aged ≥ 18 years and 
pediatric patients with refractory gMG. Given the demonstration of the efficacy and safety of 
eculizumab in patients aged ≥ 18 years, randomizing pediatric patients to a placebo treatment 
arm may not be ethically acceptable, so a single arm open-label design was chosen.  
This pediatric study is similar to the study conducted in patients aged ≥ 18 years 
(Study ECU-MG-301) in permitting background IST use. All patients may continue to receive 
ISTs during the study. Given the global nature of the study (multicenter) and experience from the 
study in patients aged ≥ 18 years, it is anticipated that different ISTs will be used based on local 
medical practice and local IST availability; thus, the use of ISTs will not be standardized in this 
study. In contrast to the study in patients aged ≥ 18 years, the number of eligible refractory 

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pediatric gMG patients aged 12 to < 18 years entering on maintenance IVIg therapy will be 
capped at 6 patients. These patients must have been on maintenance IVIg for at least 12 months 
and on a stable dose ≥ 3 months prior to Screening, with frequency and dose expected to remain 
stable during Screening and for 12 weeks following the first dose of study drug. Efforts will be 
made to enroll at least 1 patient in each geographic region (North America, EU, and APAC). 
There will be no limit on the number of patients aged 6 to < 12 years who may enter the study on 
maintenance IVIg. This change was made based on the higher prevalence of maintenance IVIg 
use in children. 
4.1.1. 
Screening Period (2 to 4 weeks) 
Patients will be screened for study eligibility only after obtaining the informed consent of the 
parent or other legal guardian, and the patient’s informed assent, when applicable. Assessment 
will include confirmation of a refractory gMG diagnosis per protocol-defined inclusion/exclusion 
criteria, QMG total score, history of previous MG treatments and therapies, history of MG 
exacerbation or crisis and the treatment for each exacerbation/crisis, and a comprehensive review 
of medical history, including vaccination history, as well as any non-MG comorbid conditions. 
When an eligible patient meets all inclusion criteria, but none of the exclusion criteria, the 
Principal Investigator must notify the Sponsor to obtain Medical Monitor approval prior to 
enrolling the patient. 
To reduce the risk of meningococcal infection, all patients must be vaccinated against 
meningococcal infections within the 3 years prior to, or at the time of, initiating study drug. 
Patients who initiate study drug treatment less than 2 weeks after receiving a meningococcal 
vaccine must receive treatment with appropriate prophylactic antibiotics until 2 weeks after 
vaccination. Patients must be vaccinated or revaccinated according to current national 
vaccination guidelines or local practice for vaccination use with complement-inhibitors (eg, 
eculizumab). In addition to meningococcal vaccination, patients must be vaccinated against 
Haemophilus influenzae (H influenzae) and Streptococcus pneumoniae (S pneumoniae), if not 
already vaccinated, and strictly adhere to the national vaccination recommendations for each age 
group.  
The site must notify the Sponsor if any patient experiences signs and symptoms of MG 
worsening that require rescue or foreseeable imminent change to the background medication 
during the Screening Period. Following discussion with the Sponsor, a decision will be made 
about whether the patient may be enrolled in the study or should be withdrawn. Patients whose 
MG is unstable (as determined by the Investigator) during the Screening Period may be 
rescreened at a later date based on discussion and agreement between the Investigator and the 
Alexion Medical Monitor.  
4.1.2. 
Primary Evaluation Treatment Period (26 weeks) 
All patients will receive eculizumab by IV infusion during the open-label Primary Evaluation 
Treatment Period. Dosing will be initiated with a weekly weight-based induction regimen and, 
thereafter, will be every 2 weeks. Weight may change for an individual patient during the study, 
and dose regimen will be based on the current visit’s recorded body weight. If site/institution 
policies prohibit study drug to be prepared day-of visit, the weight from the most recent study 
visit should be used. 

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Sites must inform patients and their parent or legal guardian of potential signs and symptoms of 
MG worsening or clinical deterioration, including myasthenic crisis, and instruct them to contact 
the Investigator in the event these occur. The Investigator should make every effort to evaluate a 
patient reporting worsening signs and symptoms of MG as soon as possible and within 48 hours 
of notification. The Investigator will assess for clinical deterioration and treat the patient 
accordingly.  
4.1.3. 
Extension Period (up to an additional 208 weeks) 
After completing the 26-week Primary Evaluation Treatment Period, patients will continue 
receiving eculizumab in the Extension Period of this study for up to an additional 208 weeks. 
Weight may change for an individual patient during the study, and dose regimen will be based on 
the current visit’s recorded body weight. If site/institution policies prohibit study drug to be 
prepared day-of visit, the weight from the most recent study visit should be used. Patients may 
have an opportunity to receive study drug administration remotely at a medical facility that is 
located near the patient’s home or at the patient’s home with the permission of the Principal 
Investigator in accordance with all national, state, and local laws or regulations of the pertinent 
regulatory authorities. 
4.1.4. 
Follow-up Period: Safety Follow-up (8 weeks) 
Patients who withdraw or discontinue treatment at any time and for any reason after receiving 
any amount of eculizumab will be required to complete both an ET Visit at the time of 
withdrawal and a Follow-up Visit at 8 weeks following the last eculizumab dose. Adverse events 
leading to patient discontinuation from the study are followed until resolution or are medically 
stable in the opinion of the Investigator. 
Patients who complete the study and transition to uninterrupted treatment with commercially 
available eculizumab will not be required to complete a follow-up visit. The Investigator must 
confirm with the patient or their guardian/caregiver by telephone that the transition to 
commercially available eculizumab occurred within 2 weeks of the last scheduled dose during 
the study. In the event that treatment with commercially available eculizumab is delayed, an 
unscheduled safety Follow-up Visit should occur on the day of initiating commercial eculizumab 
treatment or as soon thereafter as feasible. 
4.1.5. 
Post-Treatment Follow-up (up to 1 year) 
The Sponsor may seek to collect follow-up information concerning MG status in patients 
post-treatment for up to 1 year from the end-of-study (EOS)/ET Visit (see Appendix 13). 
4.1.6. 
Clinical Deterioration and Rescue Therapies 
Allowed rescue therapy for clinical deterioration includes but is not limited to high-dose 
corticosteroids, PE, or IVIg and is at the discretion of the Investigator. Plasma exchange is not 
allowed for prophylaxis or routine maintenance. Every effort should be made to notify the 
Sponsor within 24 hours of administration of rescue therapy. 

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4.1.7. 
Unscheduled Visits 
Additional (Unscheduled) visits outside the specified visits for study procedures, tests, and 
assessments may be performed at the request of the Investigator or Sponsor. If an Unscheduled 
Visit is performed, any tests, procedures, or assessments performed at the Unscheduled Visits 
must be recorded on the electronic case report forms (eCRFs). 
4.1.8. 
Study Completion 
A patient is considered to have completed the study if:  
• The patient has completed all periods of the study including the last visit of the 
Extension Period, or 
• In the event the study is completed early, the patient has completed all applicable 
periods of the study including the ET/End of Study visit, or,  
• The patient completes the study early (and completes an ET visit) because the study 
drug has become registered or approved (in accordance with country-specific 
regulations)  
4.2. 
Study Flow Diagram and Schedule of Assessments 
The flow diagram for the study design is illustrated in Figure 1. The Schedule of Assessments 
during the study for patients in weight cohorts ≥ 40 kg, 30 to < 40 kg and 20 to < 30 kg are 
summarized in Table 4 and Table 5. The Schedule of Assessments for patients in weight cohort 
10 to < 20 kg are summarized in Table 6 and Table 7.Weight cohort may change for an 
individual patient during the study, and dose regimen will be based on the current visit’s 
recorded body weight. If site/institution policies prohibit study drug to be prepared day-of visit, 
the weight from the most recent study visit should be used.

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Figure 1: 
Flow Diagram for Study Design 
 
a Patients may continue to receive AChI, IST, and/or IVIg during the study where applicable under certain restrictions. For patients who enter the study receiving 
any background therapy, the dose/schedule may not be changed during the Primary Evaluation Treatment Period before Week 12, unless deemed necessary per 
the Investigator based on clinical safety evaluation and if Sponsor approval is obtained. Dose change with background medication is permitted after Week 12 at 
the Investigator’s discretion and with Sponsor notification. During the Extension Period, changes in background medications will be permitted at the 
Investigator’s discretion and with Sponsor notification.  
Abbreviation: AChI = acetylcholinesterase inhibitor; IST = immunosuppressant therapy; IVIg = intravenous immunoglobulin 

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Table 4: 
Schedule of Assessments Part I: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 20 to < 30 kg 
Period /Phase 
Screening 
Primary Evaluation Treatment Period 
Visit Locationa 
In Clinic 
In Clinic 
In Clinic 
Study Visitb 
Screening 
Visit (1) 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
CDc ET / 
EOS F/Ud 
Study Week 
-2 to -4 
weeks 
D1 
W1 W2 W3 W4 W6 W8 W10 W12 W14 W16 W18 W20 W22 W24 W26 
 
 
+W8 
Window (Days) 
 
 
±2 
 
 
±2 
Informed Consent 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Medical History 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
MG History 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
MGFA Clinical 
Classification 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Weighte,f 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heightg 
X 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
X 
 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
 
12-Lead ECG 
X 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
 
Concomitant 
Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse Eventh 
Xh 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLi,j 
Xk 
X 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
X 
X 
X 
QMGi,k,l 
Xk 
X 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
X 
X 
X 
MGCi,l 
Xk 
X 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
X 
X 
X 
Neuro-QoL Pediatric 
Fatigue / PROMIS 
Proxy 
 
X 
 
 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
 
X 
 
EQ-5D-Y / Proxy 
 
X 
 
 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
 
X 
 
MGFA-PISi 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
X 
MGFA-Therapy 
Status 
X 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
 
 
AChR Ab 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
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Table 4: 
Schedule of Assessments Part I: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 20 to < 30 kg (Continued) 
Period /Phase 
Screening 
Primary Evaluation Treatment Period 
Visit Locationa 
In Clinic 
In Clinic 
In Clinic 
Study Visitb 
Screening 
Visit (1) 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
CDc ET / 
EOS F/Ud 
Study Week 
-2 to -4 
weeks 
D1 W1 W2 W3 W4 W6 W8 W10 W12 W14 W16 W18 W20 W22 W24 W26 
 
 
+W8 
Window (Days) 
 
 
±2 
 
 
±2 
Clinical Laboratory 
Tests 
X 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
X 
X 
 
Serum Pregnancy 
Testm 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
X 
 
Urine Pregnancy 
Testn 
 
X 
 
 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
PK, Hemolysis, Free 
C5o 
 
B/P 
24h 
T/P 
 
 
T/P 
 
 
 
T/P 
 
 
 
 
 
 
T/P 
X 
X 
 
ADAo 
 
B 
 
 
 
 
 
 
 
T 
 
 
 
 
 
 
T 
T 
T 
 
Medically Indicated 
Testsp 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
N meningitidis 
Vaccinationq 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
H influenzae 
Vaccinationr 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
S pneumonia 
Vaccinationr 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Check for 
Revaccination Statuss 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety 
Information Cardt 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 

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Table 4: 
Schedule of Assessments Part I: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 20 to < 30 kg (Continued) 
Period /Phase 
Screening 
Primary Evaluation Treatment Period 
Visit Locationa 
In Clinic 
In Clinic 
In Clinic 
Study Visitb 
Screening 
Visit (1) 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
CDc ET / 
EOS F/Ud 
Study Week 
-2 to -4 
weeks 
D1 W1 W2 W3 W4 W6 W8 W10 W12 W14 W16 W18 W20 W22 W24 W26 
 
 
+W8 
Window (Days) 
 
 
±2 
 
 
±2 
Study Drug Infusion 
≥40 kgf,u,v 
 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
 
1200 
mgw 
 
Study Drug Infusion 
30 to <40 kgf,u,v 
 
600 
mg 
600 
mg 
900 
mg 
N/A 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 900 mg 
 
900 
mgw 
 
Study Drug Infusion 
20 to <30 kgf,u,v 
 
600 
mg 
600 
mg 
600 
mg 
N/A 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 600 mg 
 
600 
mgw 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Unscheduled visits and procedures will be performed at the Investigator's discretion, and results will be recorded in the eCRF. 
c. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
d. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
e. 
Collect weight with minimal clothing.  
f. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies prohibit 
study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based treatment 
regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the initial 
induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort, the Alexion medical monitor must be contacted prior to 
dosing. 
g. 
Collect height with no shoes or footwear.  
h. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
i. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
j. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days  

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k. 
Recommendation to perform QMG assessment first to confirm eligibility. MG-ADL and MGC assessments only necessary once QMG eligibility is 
confirmed. 
l. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
m. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
n. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion. 
o. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests at 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for 
PK, hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for 
collecting the sample. For further details refer to Section 8.2.  
p. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
q. 
To reduce the risk of meningococcal infection, all patients must be vaccinated against meningococcal infections within the 3 years prior to, or at the time 
of, initiating study drug. Patients who initiate study drug treatment less than 2 weeks after receiving a meningococcal vaccine must receive treatment with 
appropriate prophylactic antibiotics until 2 weeks after vaccination. Patients must be vaccinated or revaccinated according to current national vaccination 
guidelines or local practice for vaccination use with complement-inhibitors (eg, eculizumab). 
r. 
Vaccinate patients against H influenzae and S pneumoniae, if not already vaccinated, prior to receiving the first eculizumab infusion. 
s. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
t. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
u. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
v. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  
w. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
Abbreviations: AChR Ab = acetylcholine receptor antibody; ADA = anti-drug antibodies; B = baseline sample; C5 = complement protein 5; CD = clinical 
deterioration; D = day; ECG = electrocardiogram; eCRF = electronic case report form; EOS = End of Study; EQ-5D-Y = European Quality of Life 
5-Dimension Youth; ET = Early Termination; F/U = Follow-up; MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living profile; 
MGC = Myasthenia Gravis Composite score; MGFA = Myasthenia Gravis Foundation of America; MGFA-PIS = Myasthenia Gravis Foundation of America 
Post-Intervention Status; N/A = not applicable; Neuro-QoL = Quality of Life in Neurological Disorders; P = peak sample; PK = pharmacokinetics; SCR = 
Screening; QMG = Quantitative Myasthenia Gravis score for disease severity; T = trough sample; W = week. 

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Table 5: Schedule of Assessments Part II: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 20 to < 30 kg 
Period /Phase 
Extension Period (Year 1) 
Visit Locationa 
In Clinic/Remote 
In 
Clinic 
In Clinic/Remote 
In 
Clinic 
In Clinic 
Study Visitb 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
CDc 
ET / 
EOS F/Ud 
Study Weeks 
W28 W30 W32 W34 W36 W38 W40 W42 W44 W46 W48 W50 W52 
 
 
+W8 
Window (Days) 
±2 
 
 
±2 
Weighte,f 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heightg 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
X 
 
12-Lead ECG 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
X 
 
Concomitant Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse Eventh 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLi,j 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
X 
QMGi,k,l 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
X 
MGCi,k 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
X 
Neuro-QoL Pediatric 
Fatigue/PROMIS Proxy 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
 
EQ-5D-Y/Proxy 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
 
MGFA-PISi 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
X 
Clinical Laboratory Tests 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
 
Serum Pregnancy Testl 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
Urine Pregnancy Testm 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
PK, Hemolysis, Free C5n 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
X 
 
ADAm 
 
 
 
 
 
 
 
 
 
 
 
 
 
T 
T 
 
Medically Indicated Testso 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 

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Table 5: 
Schedule of Assessments Part II: Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 20 to < 30 kg (Continued) 
Period /Phase 
Extension Period (Year 1) 
Visit Locationa 
In Clinic/Remote 
In 
Clinic 
In Clinic/Remote 
In 
Clinic 
In Clinic 
Study Visitb 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
CDc 
ET / 
EOS F/Ud 
Study Weeks 
W28 W30 W32 W34 W36 W38 W40 W42 W44 W46 W48 W50 W52 
 
 
+W8 
Window (Days) 
±2 
 
 
±2 
Check for Revaccination 
Statusp 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety Information 
Cardq 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Study Drug Infusion ≥40 
kgf,r,s 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
 
1200 
mgt 
 
Study Drug Infusion 30 to 
<40 kgf,r,s 
900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 900 mg 
 
900 mgt 
 
Study Drug Infusion 
20 to <30 kgf,r,s 
600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 600 mg 
 
600 mgt 
 
Transition follow-up callu 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Unscheduled visits and procedures will be performed at the Investigator's discretion and results will be recorded in the eCRF. 
c. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
d. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
e. 
Collect weight with minimal clothing.  
f. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. Dose will be based on the current visit’s recorded body weight. If site/institution policies prohibit study drug 
to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based treatment regimens, refer to 
Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the initial induction phase, if a 
patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted prior to dosing. 
g. 
Collect height with no shoes or footwear.  

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 39 of 123 
Alexion Confidential 
h. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
i. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
j. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days.  
k. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
l. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
m. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion.  
n. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. 
o. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
p. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
q. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
r. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
s. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  
t. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
u. 
The Investigator must confirm with the patient or their guardian/caregiver by telephone that the transition to commercially available eculizumab occurred 
within 2 weeks of the last scheduled dose during the study. In the event that treatment with commercially available eculizumab is delayed, an unscheduled 
safety Follow-up Visit should occur on the day of initiating commercial eculizumab treatment or as soon as feasible. 
Abbreviations: ADA = anti-drug antibodies; B = Baseline sample; C5 = complement protein 5; CD = clinical deterioration; ECG = electrocardiogram; eCRF = 
electronic case report form; EOS = End of Study; EQ-5D-Y = European Quality of Life 5-Dimension Youth; ET = Early Termination; F/U = Follow-up; 
MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living profile; MGC = Myasthenia Gravis Composite score; MGFA = 
Myasthenia Gravis Foundation of America; MGFA-PIS = Myasthenia Gravis Foundation of America Post-Intervention Status; Neuro-QoL = Quality of Life in 
Neurological Disorders; P = peak sample; PK = pharmacokinetics; SCR = Screening; QMG = Quantitative Myasthenia Gravis score for disease severity; T = 
trough sample; W = week. 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 40 of 123 
Alexion Confidential 
Table 6: 
Schedule of Assessments Part I: Weight Cohort 10 to < 20 kg 
Period /Phase 
Screening 
Primary Evaluation Treatment Period 
Visit Locationa 
In Clinic 
In Clinic 
In Clinic 
Study Visitb 
Screening 
Visit (1) 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
CDc ET / 
EOS F/Ud 
Study Weeks 
-2 to -4 
weeks 
D1 
W1 W3 W5 W7 W9 W11 W13 W15 W17 W19 W21 W23 W25 W27 
 
 
+W8 
Window (Days) 
 
 
±2 
 
 
±2 
Informed Consent 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Medical History 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
MG History 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
MGFA Clinical 
Classification 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Weighte,f 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heightg 
X 
X 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
 
12-Lead ECG 
X 
X 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
 
Concomitant Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse Eventh 
Xh 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLi,j 
Xk 
X 
X 
X 
X 
X 
 
 
X 
 
X 
 
X 
 
 
X 
X 
X 
X 
QMGi,k,l 
Xk 
X 
X 
X 
X 
X 
 
 
X 
 
X 
 
X 
 
 
X 
X 
X 
X 
MGCi,l 
Xk 
X 
X 
X 
X 
X 
 
 
X 
 
X 
 
X 
 
 
X 
X 
X 
X 
Neuro-QoL Pediatric 
Fatigue/PROMIS Proxy 
 
X 
 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
 
X 
 
EQ-5D-Y/Proxy 
 
X 
 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
X 
 
X 
 
MGFA-PISi 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
X 
MGFA-Therapy Status 
X 
X 
 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
 
 
AChR Ab 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Clinical Laboratory 
Tests 
X 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
X 
 
X 
X 
 
Serum Pregnancy Testm 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
X 
 
Urine Pregnancy Testn 
 
X 
 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
PK, Hemolysis, Free C5o 
 
B/P/24h T/P 
 
 
T/P 
 
 
T/P 
 
 
 
 
 
 
T/P 
X 
X 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 41 of 123 
Alexion Confidential 
Table 6: 
Schedule of Assessments Part I: Weight Cohort 10 to < 20 kg (Continued) 
Period /Phase 
Screening 
Primary Evaluation Treatment Period 
Visit Locationa 
In Clinic 
In Clinic 
In Clinic 
Study Visitb 
Screening 
Visit (1) 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
CDc ET / 
EOS F/Ud 
Study Weeks 
-2 to -4 
weeks 
D1 
W1 W3 W5 W7 W9 W11 W13 W15 W17 W19 W21 W23 W25 W27 
 
 
+W8 
Window (Days) 
 
 
±2 
 
 
±2 
ADAo 
 
B 
 
 
 
 
 
 
T 
 
 
 
 
 
 
T 
T 
T 
 
Medically Indicated 
Testsp 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
N meningitidis 
Vaccinationq 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
H influenzae 
Vaccinationr 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
S pneumonia 
Vaccinationr 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Check for Revaccination 
Statuss 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety 
Information Cardt 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Study Drug Infusion 
10 to < 20 kgf,u,v,w 
 
600 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
 
300 
mgx 
 
Study Drug Infusion 
20 to <30 kgf,u,v,w 
N/A 
N/A 
600 
mg N/A 600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
 
600 
mgx 
 
Study Drug Infusion 
30 to <40 kgf,u,v,w 
N/A 
N/A 
600 
mg N/A 900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
 
900 
mgx 
 
Study Drug Infusion 
≥40 kgf,u,v,w 
N/A 
N/A 
900 
mg 
900 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
 
1200 
mgx 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Unscheduled visits and procedures will be performed at the Investigator's discretion and results will be recorded in the eCRF. 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 42 of 123 
Alexion Confidential 
c. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
d. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
e. 
Collect weight with minimal clothing.  
f. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies prohibit 
study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based treatment 
regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the initial 
induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted prior to 
dosing. 
g. 
Collect height with no shoes or footwear.  
h. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
i. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
j. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days  
k. 
Recommendation to perform QMG assessment first to confirm eligibility. MG-ADL and MGC assessments only necessary once QMG eligibility is 
confirmed. 
l. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
m. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
n. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion. 
o. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. For further details refer to Section 8.2.  
p. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
q. 
To reduce the risk of meningococcal infection, all patients must be vaccinated against meningococcal infections within the 3 years prior to, or at the time 
of, initiating study drug. Patients who initiate study drug treatment less than 2 weeks after receiving a meningococcal vaccine must receive treatment with 
appropriate prophylactic antibiotics until 2 weeks after vaccination. Patients must be vaccinated or revaccinated according to current national vaccination 
guidelines or local practice for vaccination use with complement-inhibitors (eg, eculizumab). 
r. 
Vaccinate patients against H influenzae and S pneumoniae, if not already vaccinated, prior to receiving the first eculizumab infusion. 
s. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
t. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
u. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
v. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 43 of 123 
Alexion Confidential 
w. 
Should the patient’s weight increase ≥ 20kg during the study, dosing should be based on the most recently recorded body weight at a prior dosing visit and 
adjusted accordingly to ensure the proper dosing regimen per patients current weight. Refer to Table 15 for additional details on weight-based treatment 
regimens. 
x. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
Abbreviations: AChR Ab = acetylcholine receptor antibody; ADA = anti-drug antibodies; B = Baseline sample; C5 = complement protein 5; CD = clinical 
deterioration; D = day; ECG = electrocardiogram; eCRF = electronic case report form; EOS = End of Study; EQ-5D-Y = European Quality of Life 5-
Dimension Youth; ET = Early Termination; F/U = Follow-up; MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living profile; 
MGC = Myasthenia Gravis Composite score; MGFA = Myasthenia Gravis Foundation of America; MGFA-PIS = Myasthenia Gravis Foundation of America 
Post-Intervention Status; N/A = not applicable; Neuro-QoL = Quality of Life in Neurological Disorders; P = peak sample; PK = pharmacokinetics; SCR = 
Screening; QMG = Quantitative Myasthenia Gravis score for disease severity; T = trough sample; W = week. 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 44 of 123 
Alexion Confidential 
Table 7: 
Schedule of Assessments Part II: Weight Cohort 10 to < 20 kg 
Period /Phase 
Extension Period (Year 1) 
Visit Locationa 
In Clinic/Remote 
In 
Clinic 
In Clinic/Remote 
In 
Clinic 
In Clinic 
Study Visitb 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
CDc 
ET / 
EOS F/Ud 
Study Weeks 
W29 W31 W33 W35 W37 W39 W41 W43 W45 W47 W49 W51 W53 
 
 
+W8 
Window (Days) 
±2 
 
 
±2 
Weighte,f 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heightg 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
X 
 
12-Lead ECG 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
Concomitant Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse Eventh 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLi,j 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
X 
QMGi,k 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
X 
MGCi,k 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
X 
Neuro-QoL Pediatric 
Fatigue/PROMIS Proxy 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
 
EQ-5D-Y/Proxy 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
 
MGFA-PISi 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
X 
X 
Clinical Laboratory Tests 
 
 
 
 
 
 
X 
 
 
 
 
 
X 
X 
X 
 
Serum Pregnancy Testl 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
Urine Pregnancy Testm 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
PK, Hemolysis, Free C5n 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
X 
 
ADAn 
 
 
 
 
 
 
 
 
 
 
 
 
 
T 
T 
 
Medically Indicated Testso 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
Check for Revaccination 
Statusp 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety Information 
Cardq 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Study Drug Infusion 10 to 
< 20 kg f,r,s,t 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
300 
mg 
 
300 
mgu 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 45 of 123 
Alexion Confidential 
Table 7: 
Schedule of Assessments Part II: Weight Cohort 10 to < 20 kg (Continued) 
Period /Phase 
Extension Period (Year 1) 
Visit Locationa 
In Clinic/Remote 
In 
Clinic 
In Clinic/Remote 
In 
Clinic 
In Clinic 
Study Visitb 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
CDc 
ET / 
EOS F/Ud 
Study Weeks 
W29 W31 W33 W35 W37 W39 W41 W43 W45 W47 W49 W51 W53 
 
 
+W8 
Window (Days) 
±2 
 
 
±2 
Study Drug Infusion 20 to 
<30 kg f,r,s,t 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
600 
mg 
 
600 
mgu 
 
Study Drug Infusion 30 to 
<40 kg f,r,s,t 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
900 
mg 
 
900 
mgu 
 
Study Drug Infusion ≥40 
kg f,r,s,t 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
1200 
mg 
 
1200 
mgu 
 
Transition follow-up callv 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Unscheduled visits and procedures will be performed at the Investigator's discretion, and results will be recorded in the eCRF. 
c. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
d. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
e. 
Collect weight with minimal clothing.  
f. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. When possible, dose regimen should be based on the current visit’s recorded body weight. If site/institution 
policies prohibit study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based 
treatment regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the 
initial induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted 
prior to dosing. 
g. 
Collect height with no shoes or footwear.  
h. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
i. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 46 of 123 
Alexion Confidential 
j. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days.  
k. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
l. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
m. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion.  
n. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. 
o. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
p. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
q. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
r. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
s. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  
t. 
Should the patient’s weight increase ≥ 20kg during the study, dosing should be based on the most recently recorded body weight at a prior dosing visit and 
adjusted accordingly to ensure the proper dosing regimen per patient’s current weight. Refer to Table 15 for additional details on weight-based treatment 
regimens. 
u. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
v. 
The Investigator must confirm with the patient or their guardian/caregiver by telephone that the transition to commercially available eculizumab occurred 
within 2 weeks of the last scheduled dose during the study. In the event that treatment with commercially available eculizumab is delayed, an unscheduled 
safety Follow-up Visit should occur on the day of initiating commercial eculizumab treatment or as soon as feasible. 
Abbreviations: AChR Ab = acetylcholine receptor antibody; ADA = anti-drug antibodies; C5 = complement protein 5; CD = clinical deterioration; 
ECG = electrocardiogram; eCRF = electronic case report form; EOS = End of Study; EQ-5D-Y = European Quality of Life 5-Dimension Youth; ET = Early 
Termination; F/U = Follow-up; MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living profile; MGC = Myasthenia Gravis 
Composite score; MGFA = Myasthenia Gravis Foundation of America; MGFA-PIS = Myasthenia Gravis Foundation of America Post-Intervention Status; 
Neuro-QoL = Quality of Life in Neurological Disorders; PK = pharmacokinetics; SCR = Screening; QMG = Quantitative Myasthenia Gravis score for disease 
severity; T = trough sample; W = week.

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 47 of 123 
Alexion Confidential 
Table 8: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V31/W54 
(V30/W55) 
V32/W56 
(V31/W57) 
V33/W58 
(V32/W59) 
V34/W60 
(V33/W61) 
V35/W62 
(V34/W63) 
V36/W64 
(V35/W65) 
V37/W66 
(V36/W67) 
V38/W68 
(V37/W69) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V57/W106 
(V56/W107) 
V58/W108 
(V57/W109) 
V59/W110 
(V58/W111) 
V60/W112 
(V59/W113) 
V61/W114 
(V60/W115) 
V62/W116 
(V61/W117) 
V63/W118 
(V62/W119) 
V64/W120 
(V63/W121) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V83/W158 
(V82/W159) 
V84/W160 
(V83/W161) 
V85/W162 
(V84/W163) 
V86/W164 
(V85/W165) 
V87/W166 
(V86/W167) 
V88/W168 
(V87/W169) 
V89/W170 
(V88/W171) 
V90/W172 
(V89/W173) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V109/W210 
(V108/W211
) 
V110/W212 
(V109/W21
3) 
V111/W214 
(V110/W21
5) 
V112/W216 
(V111/W21
7) 
V113/W218 
(V112/W21
9) 
V114/W220 
(V113/W22
1) 
V115/W222 
(V114/W22
3) 
V116/W224 
(V115/W22
5) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Weightf,g 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heighth 
 
 
 
 
 
X 
 
 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
 
 
 
 
 
 
 
 
 
X 
 
12-Lead ECG 
 
 
 
 
 
 
 
 
 
X 
 
Concomitant 
Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse Eventi 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLj,k 
 
 
 
 
 
X 
 
 
X 
X 
X 
QMGj,l 
 
 
 
 
 
X 
 
 
X 
X 
X 
MGCj,l 
 
 
 
 
 
X 
 
 
X 
X 
X 
Neuro-QoL 
Pediatric 
Fatigue/PROMI
S Proxy 
 
 
 
 
 
X 
 
 
 
X 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 48 of 123 
Alexion Confidential 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V31/W54 
(V30/W55) 
V32/W56 
(V31/W57) 
V33/W58 
(V32/W59) 
V34/W60 
(V33/W61) 
V35/W62 
(V34/W63) 
V36/W64 
(V35/W65) 
V37/W66 
(V36/W67) 
V38/W68 
(V37/W69) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V57/W106 
(V56/W107) 
V58/W108 
(V57/W109) 
V59/W110 
(V58/W111) 
V60/W112 
(V59/W113) 
V61/W114 
(V60/W115) 
V62/W116 
(V61/W117) 
V63/W118 
(V62/W119) 
V64/W120 
(V63/W121) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V83/W158 
(V82/W159) 
V84/W160 
(V83/W161) 
V85/W162 
(V84/W163) 
V86/W164 
(V85/W165) 
V87/W166 
(V86/W167) 
V88/W168 
(V87/W169) 
V89/W170 
(V88/W171) 
V90/W172 
(V89/W173) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V109/W210 
(V108/W211
) 
V110/W212 
(V109/W21
3) 
V111/W214 
(V110/W21
5) 
V112/W216 
(V111/W21
7) 
V113/W218 
(V112/W21
9) 
V114/W220 
(V113/W22
1) 
V115/W222 
(V114/W22
3) 
V116/W224 
(V115/W22
5) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
EQ-5D-Y/Proxy 
 
 
 
 
 
X 
 
 
 
X 
 
MGFA-PISj 
 
 
 
 
 
 
 
 
 
X 
X 
Clinical 
Laboratory 
Testsx 
 
 
 
 
 
 
 
 
X 
X 
 
Serum 
Pregnancy Testm 
 
 
 
 
 
 
 
 
 
X 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 49 of 123 
Alexion Confidential 
Table 8: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V31/W54 
(V30/W55) 
V32/W56 
(V31/W57) 
V33/W58 
(V32/W59) 
V34/W60 
(V33/W61) 
V35/W62 
(V34/W63) 
V36/W64 
(V35/W65) 
V37/W66 
(V36/W67) 
V38/W68 
(V37/W69) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V57/W106 
(V56/W107) 
V58/W108 
(V57/W109) 
V59/W110 
(V58/W111) 
V60/W112 
(V59/W113) 
V61/W114 
(V60/W115) 
V62/W116 
(V61/W117) 
V63/W118 
(V62/W119) 
V64/W120 
(V63/W121) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V83/W158 
(V82/W159) 
V84/W160 
(V83/W161) 
V85/W162 
(V84/W163) 
V86/W164 
(V85/W165) 
V87/W166 
(V86/W167) 
V88/W168 
(V87/W169) 
V89/W170 
(V88/W171) 
V90/W172 
(V89/W173) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V109/W210 
(V108/W211
) 
V110/W212 
(V109/W21
3) 
V111/W214 
(V110/W21
5) 
V112/W216 
(V111/W217
) 
V113/W218 
(V112/W21
9) 
V114/W220 
(V113/W22
1) 
V115/W222 
(V114/W22
3) 
V116/W224 
(V115/W22
5) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Urine Pregnancy 
Testn 
 
X 
 
X 
 
X 
 
X 
 
 
X 
PK, Hemolysis, 
Free C5o 
 
 
 
 
 
T 
 
 
X 
X 
 
ADAo 
 
 
 
 
 
T 
 
 
T 
T 
 
Medically 
Indicated Testsp 
 
 
 
 
 
 
 
 
X 
 
 
Check for 
Revaccination 
Statusq 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety 
Information 
Cardr 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 50 of 123 
Alexion Confidential 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V31/W54 
(V30/W55) 
V32/W56 
(V31/W57) 
V33/W58 
(V32/W59) 
V34/W60 
(V33/W61) 
V35/W62 
(V34/W63) 
V36/W64 
(V35/W65) 
V37/W66 
(V36/W67) 
V38/W68 
(V37/W69) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V57/W106 
(V56/W107) 
V58/W108 
(V57/W109) 
V59/W110 
(V58/W111) 
V60/W112 
(V59/W113) 
V61/W114 
(V60/W115) 
V62/W116 
(V61/W117) 
V63/W118 
(V62/W119) 
V64/W120 
(V63/W121) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V83/W158 
(V82/W159) 
V84/W160 
(V83/W161) 
V85/W162 
(V84/W163) 
V86/W164 
(V85/W165) 
V87/W166 
(V86/W167) 
V88/W168 
(V87/W169) 
V89/W170 
(V88/W171) 
V90/W172 
(V89/W173) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V109/W210 
(V108/W211
) 
V110/W212 
(V109/W21
3) 
V111/W214 
(V110/W21
5) 
V112/W216 
(V111/W217
) 
V113/W218 
(V112/W21
9) 
V114/W220 
(V113/W22
1) 
V115/W222 
(V114/W22
3) 
V116/W224 
(V115/W22
5) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Study Drug 
Infusion 10 to 
< 20 kg g,s,t,u 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
 
300 
mgv 
 
Study Drug 
Infusion 20 to 
<30 kgg,s,t,u 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
 
600 
mgv 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 51 of 123 
Alexion Confidential 
Table 8: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V31/W54 
(V30/W55) 
V32/W56 
(V31/W57) 
V33/W58 
(V32/W59) 
V34/W60 
(V33/W61) 
V35/W62 
(V34/W63) 
V36/W64 
(V35/W65) 
V37/W66 
(V36/W67) 
V38/W68 
(V37/W69) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V57/W106 
(V56/W107) 
V58/W108 
(V57/W109) 
V59/W110 
(V58/W111) 
V60/W112 
(V59/W113) 
V61/W114 
(V60/W115) 
V62/W116 
(V61/W117) 
V63/W118 
(V62/W119) 
V64/W120 
(V63/W121) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V83/W158 
(V82/W159) 
V84/W160 
(V83/W161) 
V85/W162 
(V84/W163) 
V86/W164 
(V85/W165) 
V87/W166 
(V86/W167) 
V88/W168 
(V87/W169) 
V89/W170 
(V88/W171) 
V90/W172 
(V89/W173) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V109/W210 
(V108/W211
) 
V110/W212 
(V109/W21
3) 
V111/W214 
(V110/W21
5) 
V112/W216 
(V111/W217
) 
V113/W218 
(V112/W21
9) 
V114/W220 
(V113/W22
1) 
V115/W222 
(V114/W22
3) 
V116/W224 
(V115/W22
5) 
CDd ET / 
EO
S 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Study Drug 
Infusion 30 to 
<40 kgg,s,t,u 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
 
900 
mgv 
 
Study Drug 
Infusion ≥40 
kgg,s,t,u 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
 
1200 
mgv 
 
Transition 
follow-up callw 
 
 
 
 
 
 
 
 
 
X 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Shown as visit/week for Weight Cohorts ≥ 40 kg, 30 to < 40 kg, and 20 to < 30 kg (10 to < 20 kg). 
c. 
Unscheduled visits and procedures will be performed at the Investigator's discretion, and results will be recorded in the eCRF. 
d. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 52 of 123 
Alexion Confidential 
e. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
f. 
Collect weight with minimal clothing. 
g. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. When possible, dose regimen should be based on the current visit’s recorded body weight. If site/institution 
policies prohibit study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based 
treatment regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the 
initial induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted 
prior to dosing. 
h. 
Collect height with no shoes or footwear.  
i. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
j. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
k. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days.  
l. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
m. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
n. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion.  
o. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. 
p. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
q. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
r. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
s. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
t. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  
u. 
Should the patient’s weight increase ≥20kg during the study, dosing should be based on the most recently recorded body weight at a prior dosing visit and 
adjusted accordingly to ensure the proper dosing regimen per patients current weight. Refer to Table 15 for additional details on weight-based treatment 
regimens. 
v. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
w. 
The Investigator must confirm with the patient or their guardian/caregiver by telephone that the transition to commercially available eculizumab occurred 
within 2 weeks of the last scheduled dose during the study. In the event that treatment with commercially available eculizumab is delayed, an unscheduled 
safety Follow-up Visit should occur on the day of initiating commercial eculizumab treatment or as soon as feasible. 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 53 of 123 
Alexion Confidential 
x. 
Clinical laboratory tests are to be performed every 6 months during the extension period. 
Abbreviations: ADA = antidrug antibodies; C5 = complement protein 5; CD = clinical deterioration; ECG = electrocardiogram; eCRF = electronic case report 
form; EOS = End of Study; EQ-5D-Y = European Quality of life 5 Dimension Youth; ET = early termination; MG = myasthenia gravis; 
MG-ADL = Myasthenia Gravis Activities of Daily Living profile; MGC = Myasthenia Gravis Composite; MGFA-PIS = Myasthenia Gravis Foundation of 
America Post-Interventional Status; Neuro-QoL = Quality of Life in Neurological Disorders; PI = Principal Investigator; PK = pharmacokinetics; QMG = 
Quantitative Myasthenia Gravis Score for Disease Severity; T = trough sample; V = visit; W = week 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 54 of 123 
Alexion Confidential 
Table 9: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts)  
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,
c 
V39/W70 
(V38/W71) 
V40/W72 
(V39/W73) 
V41/W74 
(V40/W75) 
V42/W76 
(V41/W77) 
V43/W78 
(V42/W79) 
V44/W80 
(V43/W81) 
V45/W82 
(V44/W83) 
V46/W84 
(V45/W85) 
CDd 
ET/EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,
c 
V65/W122 
(V64/W123) 
V66/W124 
(V65/W125) 
V67/W126 
(V66/W127) 
V68/W128 
(V67/W129) 
V69/W130 
(V68/W13
1) 
V70/W132 
(V69/W133) 
V71/W134 
(V70/W13
5) 
V72/W136 
(V71/W13
7) 
CDd 
ET/EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,
c 
V91/W174 
(V90/W175) 
V92/W176 
(V91/W177) 
V93/W178 
(V92/W179) 
V94/W180 
(V93/W181) 
V95/W182 
(V94/W18
3) 
V96/W184 
(V95/W185) 
V97/W186 
(V96/W18
7) 
V98/W188 
(V97/W18
9) 
CDd 
ET/EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,
c 
V117/W226 
(V116/W22
7) 
V118/W228 
(V117/W22
9) 
V119/W230 
(V118/W23
1) 
V120/W232 
(V119/W23
3) 
(Refer to 
EOS) 
NA 
NA 
NA 
CDd 
ET/EO
S/ 
V121/ 
W234 
(V120/ 
W235) 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Weightf,g 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heighth 
 
 
 
 
X 
 
 
 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
 
 
 
 
 
 
 
 
 
X 
 
12-Lead ECG 
 
 
 
 
 
 
 
 
 
X 
 
Concomitant 
Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse 
Eventi 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLj,k 
 
 
 
 
X 
 
 
 
X 
X 
X 
QMGj,l 
 
 
 
 
X 
 
 
 
X 
X 
X 
MGCj,l 
 
 
 
 
X 
 
 
 
X 
X 
X 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 55 of 123 
Alexion Confidential 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,
c 
V39/W70 
(V38/W71) 
V40/W72 
(V39/W73) 
V41/W74 
(V40/W75) 
V42/W76 
(V41/W77) 
V43/W78 
(V42/W79) 
V44/W80 
(V43/W81) 
V45/W82 
(V44/W83) 
V46/W84 
(V45/W85) 
CDd 
ET/EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,
c 
V65/W122 
(V64/W123) 
V66/W124 
(V65/W125) 
V67/W126 
(V66/W127) 
V68/W128 
(V67/W129) 
V69/W130 
(V68/W13
1) 
V70/W132 
(V69/W133) 
V71/W134 
(V70/W13
5) 
V72/W136 
(V71/W13
7) 
CDd 
ET/EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,
c 
V91/W174 
(V90/W175) 
V92/W176 
(V91/W177) 
V93/W178 
(V92/W179) 
V94/W180 
(V93/W181) 
V95/W182 
(V94/W18
3) 
V96/W184 
(V95/W185) 
V97/W186 
(V96/W18
7) 
V98/W188 
(V97/W18
9) 
CDd 
ET/EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,
c 
V117/W226 
(V116/W22
7) 
V118/W228 
(V117/W22
9) 
V119/W230 
(V118/W23
1) 
V120/W232 
(V119/W23
3) 
(Refer to 
EOS) 
NA 
NA 
NA 
CDd 
ET/EO
S/ 
V121/ 
W234 
(V120/ 
W235) 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Neuro-QoL 
Pediatric 
Fatigue/PRO
MIS Proxy 
 
 
 
 
X 
 
 
 
 
X 
 
EQ-5D-
Y/Proxy 
 
 
 
 
X 
 
 
 
 
X 
 
MGFA-PISj 
 
 
 
 
 
 
 
 
 
X 
X 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 56 of 123 
Alexion Confidential 
Table 9: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V39/W70 
(V38/W71) 
V40/W72 
(V39/W73) 
V41/W74 
(V40/W75) 
V42/W76 
(V41/W77) 
V43/W78 
(V42/W79) 
V44/W80 
(V43/W81) 
V45/W82 
(V44/W83) 
V46/W84 
(V45/W85) CDd ET/EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V65/W122 
(V64/W123) 
V66/W124 
(V65/W125) 
V67/W126 
(V66/W127) 
V68/W128 
(V67/W129) 
V69/W130 
(V68/W13
1) 
V70/W132 
(V69/W13
3) 
V71/W134 
(V70/W13
5) 
V72/W136 
(V71/W13
7) 
CDd ET/EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V91/W174 
(V90/W175) 
V92/W176 
(V91/W177) 
V93/W178 
(V92/W179) 
V94/W180 
(V93/W181) 
V95/W182 
(V94/W18
3) 
V96/W184 
(V95/W18
5) 
V97/W186 
(V96/W18
7) 
V98/W188 
(V97/W18
9) 
CDd ET/EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V117/W226 
(V116/W227
) 
V118/W228 
(V117/W22
9) 
V119/W230 
(V118/W23
1) 
V120/W232 
(V119/W23
3) 
(Refer to 
EOS) 
NA 
NA 
NA 
CDd 
ET/EO
S/ 
V121/ 
W234 
(V120/ 
W235) 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Clinical 
Laboratory 
Testsx 
 
 
 
 
X 
 
 
 
X 
X 
 
Serum 
Pregnancy Testm 
 
 
 
 
 
 
 
 
 
X 
 
Urine Pregnancy 
Testn 
 
X 
 
X 
 
X 
 
X 
 
 
X 
PK, Hemolysis, 
Free C5o 
 
 
 
 
T 
 
 
 
X 
X 
 
ADAo 
 
 
 
 
T 
 
 
 
T 
T 
 
Medically 
Indicated Testsp 
 
 
 
 
 
 
 
 
X 
 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 57 of 123 
Alexion Confidential 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V39/W70 
(V38/W71) 
V40/W72 
(V39/W73) 
V41/W74 
(V40/W75) 
V42/W76 
(V41/W77) 
V43/W78 
(V42/W79) 
V44/W80 
(V43/W81) 
V45/W82 
(V44/W83) 
V46/W84 
(V45/W85) CDd ET/EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V65/W122 
(V64/W123) 
V66/W124 
(V65/W125) 
V67/W126 
(V66/W127) 
V68/W128 
(V67/W129) 
V69/W130 
(V68/W13
1) 
V70/W132 
(V69/W13
3) 
V71/W134 
(V70/W13
5) 
V72/W136 
(V71/W13
7) 
CDd ET/EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V91/W174 
(V90/W175) 
V92/W176 
(V91/W177) 
V93/W178 
(V92/W179) 
V94/W180 
(V93/W181) 
V95/W182 
(V94/W18
3) 
V96/W184 
(V95/W18
5) 
V97/W186 
(V96/W18
7) 
V98/W188 
(V97/W18
9) 
CDd ET/EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V117/W226 
(V116/W227
) 
V118/W228 
(V117/W22
9) 
V119/W230 
(V118/W23
1) 
V120/W232 
(V119/W23
3) 
(Refer to 
EOS) 
NA 
NA 
NA 
CDd 
ET/EO
S/ 
V121/ 
W234 
(V120/ 
W235) 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Check for 
Revaccination 
Statusq 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety 
Information 
Cardr 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Study Drug 
Infusion 10 to 
< 20 kg g,s,t,u 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
 
300 mgv 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 58 of 123 
Alexion Confidential 
Table 9: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit 
Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic/Remote 
In Clinic 
Year 2 
Visit/Weekb,c 
V39/W70 
(V38/W71) 
V40/W72 
(V39/W73) 
V41/W74 
(V40/W75) 
V42/W76 
(V41/W77) 
V43/W78 
(V42/W79) 
V44/W80 
(V43/W81) 
V45/W82 
(V44/W83) 
V46/W84 
(V45/W85) CDd ET/EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V65/W122 
(V64/W123) 
V66/W124 
(V65/W125) 
V67/W126 
(V66/W127) 
V68/W128 
(V67/W129) 
V69/W130 
(V68/W13
1) 
V70/W132 
(V69/W13
3) 
V71/W134 
(V70/W13
5) 
V72/W136 
(V71/W13
7) 
CDd ET/EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V91/W174 
(V90/W175) 
V92/W176 
(V91/W177) 
V93/W178 
(V92/W179) 
V94/W180 
(V93/W181) 
V95/W182 
(V94/W18
3) 
V96/W184 
(V95/W18
5) 
V97/W186 
(V96/W18
7) 
V98/W188 
(V97/W18
9) 
CDd 
ET 
/EOS 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
V117/W226 
(V116/W227
) 
V118/W228 
(V117/W22
9) 
V119/W230 
(V118/W23
1) 
V120/W232 
(V119/W23
3) 
(Refer to 
EOS) 
NA 
NA 
NA 
CDd 
ET/EO
S/ 
V121/ 
W234 
(V120/ 
W235) 
F/Ue 
(+W8) 
Window 
(Days) 
±2 
 
 
(±2) 
Study Drug 
Infusion 20 to 
<30 kgg,s,t,u 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
 
600 mgv 
 
Study Drug 
Infusion 30 to 
<40 kgg,s,t,u 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
 
900 mgv 
 
Study Drug 
Infusion ≥40 
kgg,s,t,u 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
 
1200 mgv 
 
Transition 
follow-up callw 
 
 
 
 
 
 
 
 
 
X 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 59 of 123 
Alexion Confidential 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Shown as visit/week for Weight Cohorts ≥40 kg, 30 to <40 kg, and 20 to <30 kg (10 to <20 kg). 
c. 
Unscheduled visits and procedures will be performed at the Investigator's discretion, and results will be recorded in the eCRF. 
d. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
e. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
f. 
Collect weight with minimal clothing.  
g. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. When possible, dose regimen should be based on the current visit’s recorded body weight. If site/institution 
policies prohibit study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based 
treatment regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the 
initial induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted 
prior to dosing. 
h. 
Collect height with no shoes or footwear.  
i. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
j. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
k. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days.  
l. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
m. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
n. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion.  
o. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. 
p. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
q. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
r. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
s. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 60 of 123 
Alexion Confidential 
t. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  
u. 
Should the patient’s weight increase ≥20kg during the study, dosing should be based on the most recently recorded body weight at a prior dosing visit and 
adjusted accordingly to ensure the proper dosing regimen per patients current weight. Refer to Table 15 for additional details on weight-based treatment 
regimens. 
v. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
w. 
The Investigator must confirm with the patient or their guardian/caregiver by telephone that the transition to commercially available eculizumab occurred 
within 2 weeks of the last scheduled dose during the study. In the event that treatment with commercially available eculizumab is delayed, an unscheduled 
safety Follow-up Visit should occur on the day of initiating commercial eculizumab treatment or as soon as feasible.  
x. 
Clinical laboratory tests are to be performed every 6 months during the extension period. 
Abbreviations: ADA = antidrug antibodies; C5 = complement protein 5; CD = clinical deterioration; ECG = electrocardiogram; eCRF = electronic case report 
form; EQ-5D-Y = European Quality of life 5 Dimension Youth; ET = early termination; F/U = Follow-up; MG = myasthenia gravis; MG-ADL = Myasthenia 
Gravis Activities of Daily Living profile; MGC = Myasthenia Gravis Composite; MGFA-PIS = Myasthenia Gravis Foundation of America Post-Interventional 
Status; NA = not applicable; Neuro-QoL = Quality of Life in Neurological Disorders; PI = Principal Investigator; PK = pharmacokinetics; QMG = Quantitative 
Myasthenia Gravis Score for Disease Severity; T = trough sample; V = visit; W = week 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 61 of 123 
Alexion Confidential 
Table 10: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In Clinic/ 
 
In Clinic/Remote 
In-Clinic 
Year 2 
Visit/Weekb,c 
V47/W86 
(V46/W87) 
V48/W88 
(V47/W89) 
V49/W90 
(V48/W91) 
V50/W92 
(V49/W93) 
V51/W94 
(V50/W95) 
V52/W96 
(V51/W97) 
V53/W98 
(V52/W99) 
V54/W100 
(V53/W101) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V73/W138 
(V72/W139
) 
V74/W140 
(V73/W14
1) 
V75/W142 
(V74/W143) 
V76/W144 
(V75/W145) 
V77/W146 
(V76/W147) 
V78/W148 
(V77/W149) 
V79/W150 
(V78/W151) 
V80/W152 
(V79/W153) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V99/W190 
(V98/W191
) 
V100/W19
2 
(V99/W19
3) 
V101/W194 
(V100/W195
) 
V102/W196 
(V101/W19
7) 
V103/W198 
(V102/W19
9) 
V104/W200 
(V103/W20
1) 
V105/W202 
(V104/W20
3) 
V106/W204 
(V105/W20
5) 
CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA NA 
NA 
Window (Days) 
±2 
 
 
(±2) 
Weightf,g 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Heighth 
 
 
X 
 
 
 
 
 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Physical Exam 
 
 
 
 
 
 
 
 
 
X 
 
12-Lead ECG 
 
 
 
 
 
 
 
 
 
X 
 
Concomitant 
Medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse Eventi 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-ADLj,k 
 
 
X 
 
 
 
 
 
X 
X 
X 
QMGj,l 
 
 
X 
 
 
 
 
 
X 
X 
X 
MGCj,l 
 
 
X 
 
 
 
 
 
X 
X 
X 
Neuro-QoL 
Pediatric 
Fatigue/PROMIS 
Proxy 
 
 
X 
 
 
 
 
 
 
X 
 
EQ-5D-Y/Proxy 
 
 
X 
 
 
 
 
 
 
X 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 62 of 123 
Alexion Confidential 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In Clinic/ 
 
In Clinic/Remote 
In-Clinic 
Year 2 
Visit/Weekb,c 
V47/W86 
(V46/W87) 
V48/W88 
(V47/W89) 
V49/W90 
(V48/W91) 
V50/W92 
(V49/W93) 
V51/W94 
(V50/W95) 
V52/W96 
(V51/W97) 
V53/W98 
(V52/W99) 
V54/W100 
(V53/W101) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V73/W138 
(V72/W139
) 
V74/W140 
(V73/W14
1) 
V75/W142 
(V74/W143) 
V76/W144 
(V75/W145) 
V77/W146 
(V76/W147) 
V78/W148 
(V77/W149) 
V79/W150 
(V78/W151) 
V80/W152 
(V79/W153) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V99/W190 
(V98/W191
) 
V100/W19
2 
(V99/W19
3) 
V101/W194 
(V100/W195
) 
V102/W196 
(V101/W19
7) 
V103/W198 
(V102/W19
9) 
V104/W200 
(V103/W20
1) 
V105/W202 
(V104/W20
3) 
V106/W204 
(V105/W20
5) 
CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA NA 
NA 
Window (Days) 
±2 
 
 
(±2) 
MGFA-PISj 
 
 
 
 
 
 
 
 
 
X 
X 
Clinical Laboratory 
Testsx 
 
 
 
 
 
 
 
 
X 
X 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 63 of 123 
Alexion Confidential 
Table 10: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In Clinic/ 
In Clinic/Remote 
In-Clinic 
Year 2 
Visit/Weekb,c 
V47/W86 
(V46/W87) 
V48/W88 
(V47/W89) 
V49/W90 
(V48/W91) 
V50/W92 
(V49/W93) 
V51/W94 
(V50/W95) 
V52/W96 
(V51/W97) 
V53/W98 
(V52/W99) 
V54/W100 
(V53/W101) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V73/W138 
(V72/W139
) 
V74/W140 
(V73/W14
1) 
V75/W142 
(V74/W143) 
V76/W144 
(V75/W145) 
V77/W146 
(V76/W147) 
V78/W148 
(V77/W149) 
V79/W150 
(V78/W151) 
V80/W152 
(V79/W153) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V99/W190 
(V98/W191
) 
V100/W19
2 
(V99/W19
3) 
V101/W194 
(V100/W195
) 
V102/W196 
(V101/W19
7) 
V103/W198 
(V102/W19
9) 
V104/W200 
(V103/W20
1) 
V105/W202 
(V104/W20
3) 
V106/W204 
(V105/W20
5) 
CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA NA 
NA 
Window (Days) 
±2 
 
 
(±2) 
Serum Pregnancy 
Testm 
 
 
 
 
 
 
 
 
 
X 
 
Urine Pregnancy 
Testn 
 
X 
 
X 
 
X 
 
X 
 
 
X 
PK, Hemolysis, 
Free C5o 
 
 
T 
 
 
 
 
 
X 
X 
 
ADAo 
 
 
T 
 
 
 
 
 
T 
T 
 
Medically 
Indicated Testsp 
 
 
 
 
 
 
 
 
X 
 
 
Check for 
Revaccination 
Statusq 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Patient Safety 
Information Cardr 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Study Drug 
Infusion 10 to < 20 
kg g,s,t,u 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
300 mg 
 
300 
mgv 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 64 of 123 
Alexion Confidential 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In Clinic/ 
In Clinic/Remote 
In-Clinic 
Year 2 
Visit/Weekb,c 
V47/W86 
(V46/W87) 
V48/W88 
(V47/W89) 
V49/W90 
(V48/W91) 
V50/W92 
(V49/W93) 
V51/W94 
(V50/W95) 
V52/W96 
(V51/W97) 
V53/W98 
(V52/W99) 
V54/W100 
(V53/W101) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V73/W138 
(V72/W139
) 
V74/W140 
(V73/W14
1) 
V75/W142 
(V74/W143) 
V76/W144 
(V75/W145) 
V77/W146 
(V76/W147) 
V78/W148 
(V77/W149) 
V79/W150 
(V78/W151) 
V80/W152 
(V79/W153) CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V99/W190 
(V98/W191
) 
V100/W19
2 
(V99/W19
3) 
V101/W194 
(V100/W195
) 
V102/W196 
(V101/W19
7) 
V103/W198 
(V102/W19
9) 
V104/W200 
(V103/W20
1) 
V105/W202 
(V104/W20
3) 
V106/W204 
(V105/W20
5) 
CDd 
ET / 
EO
S 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA NA 
NA 
Window (Days) 
±2 
 
 
(±2) 
Study Drug 
Infusion 20 to <30 
kgg,s,t,u 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
600 mg 
 
600 
mgv 
 

Protocol ECU-MG-303, Version 4.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Alexion Pharmaceuticals, Inc. (Alexion) 
28 Sep 2020 
Page 65 of 123 
Alexion Confidential 
Table 10: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In Clinic/ 
In Clinic/Remote 
In-Clinic 
Year 2 
Visit/Weekb,c 
V47/W86 
(V46/W87) 
V48/W88 
(V47/W89) 
V49/W90 
(V48/W91) 
V50/W92 
(V49/W93) 
V51/W94 
(V50/W95) 
V52/W96 
(V51/W97) 
V53/W98 
(V52/W99) 
V54/W100 
(V53/W101) CDd ET / 
EOS 
F/Ue 
(+W8) 
Year 3 
Visit/Weekb,c 
V73/W138 
(V72/W139
) 
V74/W140 
(V73/W14
1) 
V75/W142 
(V74/W143) 
V76/W144 
(V75/W145) 
V77/W146 
(V76/W147) 
V78/W148 
(V77/W149) 
V79/W150 
(V78/W151) 
V80/W152 
(V79/W153) CDd ET / 
EOS 
F/Ue 
(+W8) 
Year 4 
Visit/Weekb,c 
V99/W190 
(V98/W191
) 
V100/W19
2 
(V99/W19
3) 
V101/W194 
(V100/W195
) 
V102/W196 
(V101/W19
7) 
V103/W198 
(V102/W19
9) 
V104/W200 
(V103/W20
1) 
V105/W202 
(V104/W20
3) 
V106/W204 
(V105/W20
5) 
CDd ET / 
EOS 
F/Ue 
(+W8) 
Year 5 
Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
NA 
Window (Days) 
±2 
 
 
(±2) 
Study Drug 
Infusion 30 to <40 
kgg,s,t,u 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
900 mg 
 
900 
mgv 
 
Study Drug 
Infusion ≥40 
kgg,s,t,u 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
1200 mg 
 
1200 
mgv 
 
Transition 
follow-up callw 
 
 
 
 
 
 
 
 
 
X 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Shown as visit/week for Weight Cohorts ≥40 kg, 30 to <40 kg, and 20 to <30 kg (10 to <20 kg). 
c. 
Unscheduled visits and procedures will be performed at the Investigator's discretion, and results will be recorded in the eCRF. 
d. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
e. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  

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f. 
Collect weight with minimal clothing.  
g. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. When possible, dose regimen should be based on the current visit’s recorded body weight. If site/institution 
policies prohibit study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based 
treatment regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the 
initial induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted 
prior to dosing. 
h. 
Collect height with no shoes or footwear.  
i. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
j. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
k. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days.  
l. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
m. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
n. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion.  
o. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. 
p. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
q. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
r. 
Review the Patient Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
s. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
t. 
For supplemental weight-based eculizumab dosing, refer to Table 16 and Table 17.  
u. 
Should the patient’s weight increase ≥20kg during the study, dosing should be based on the most recently recorded body weight at a prior dosing visit and 
adjusted accordingly to ensure the proper dosing regimen per patients current weight. Refer to Table 15 for additional details on weight-based treatment 
regimens. 
v. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
w. 
The Investigator must confirm with the patient or their guardian/caregiver by telephone that the transition to commercially available eculizumab occurred 
within 2 weeks of the last scheduled dose during the study. In the event that treatment with commercially available eculizumab is delayed, an unscheduled 
safety Follow-up Visit should occur on the day of initiating commercial eculizumab treatment or as soon as feasible.  
x. 
Clinical laboratory tests are to be performed every 6 months during the extension period. 

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Abbreviations: ADA = antidrug antibodies; C5 = complement protein 5; CD = clinical deterioration; ECG = electrocardiogram; eCRF = electronic case report 
form; EOS = End of Study; EQ-5D-Y = European Quality of life 5 Dimension Youth; ET = early termination; F/U = Follow-up; MG = myasthenia gravis; MG-
ADL = Myasthenia Gravis Activities of Daily Living profile; MGC = Myasthenia Gravis Composite; MGFA-PIS = Myasthenia Gravis Foundation of America 
Post-Interventional Status; Neuro-QoL = Quality of Life in Neurological Disorders; PI = Principal Investigator; PK = pharmacokinetics; QMG = Quantitative 
Myasthenia Gravis Score for Disease Severity; T = trough sample; V = visit; W = week 
 

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Table 11: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic 
Year 2 Visit/Weekb,c 
V55/W102 
(V54/W103) 
V56/W104 
(V55/W105) 
CDd 
ET / EOS 
F/Ue 
(+W8) 
Year 3 Visit/Weekb,c 
V81/W154 
(V80/W155) 
V82/W156 
(V81/W157) 
CDd 
ET / EOS 
F/Ue 
(+W8) 
Year 4 Visit/Weekb,c 
V107/W206 
(V106/W207) 
V108/W208 
(V107/W209) 
CDd 
ET / EOS 
F/Ue 
(+W8) 
Year 5 Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
Window (Days) 
±2 
 
 
 
±2 
Weightf,g 
X 
X 
X 
X 
X 
Heighth 
 
X 
 
X 
 
Vital Signs 
X 
X 
X 
X 
X 
Physical Exam 
 
 
 
X 
 
12-Lead ECG 
 
 
 
X 
 
Concomitant Medication 
X 
X 
X 
X 
X 
Adverse Eventi 
X 
X 
X 
X 
X 
MG-ADLj,k 
 
X 
X 
X 
X 
QMGj,l 
 
X 
X 
X 
X 
MGCj,l 
 
X 
X 
X 
X 
Neuro-QoL Pediatric Fatigue/PROMIS 
Proxy 
 
X 
 
X 
 
EQ-5D-Y/Proxy 
 
X 
 
X 
 
MGFA-PISj 
 
 
 
X 
X 
Clinical Laboratory Testsx 
 
X 
X 
X 
 
Serum Pregnancy Testm 
 
 
 
X 
 
Urine Pregnancy Testn 
 
X 
 
 
X 
PK, Hemolysis, Free C5o 
 
T 
X 
X 
 
ADAo 
 
T 
T 
T 
 

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Table 11: 
Schedule of Assessments (Extension Period): Year 2 through Year 5 (All Weight Cohorts) (Continued) 
Phase 
Extension Period 
Visit Locationa 
In Clinic/Remote 
In-Clinic 
In Clinic 
Year 2 Visit/Weekb,c 
V55/W102 
(V54/W103) 
V56/W104 
(V55/W105) 
CDd 
ET / EOS 
F/Ue 
(+W8) 
Year 3 Visit/Weekb,c 
V81/W154 
(V80/W155) 
V82/W156 
(V81/W157) 
CDd 
ET / EOS 
F/Ue 
(+W8) 
Year 4 Visit/Weekb,c 
V107/W206 
(V106/W207) 
V108/W208 
(V107/W209) 
CDd 
ET / EOS 
F/Ue 
(+W8) 
Year 5 Visit/Weekb,c 
NA 
NA 
NA 
NA 
NA 
Window (Days) 
±2 
 
 
 
±2 
Medically Indicated Testsp 
 
 
X 
 
 
Check for Revaccination Statusq 
X 
X 
X 
X 
X 
Patient Safety Information Cardr 
X 
X 
X 
X 
X 
Study Drug Infusion 10 to < 20 kg g,s,t,u 
300 mg 
300 mg 
 
300 mgv 
 
Study Drug Infusion 20 to <30 kgg,s,t,u 
600 mg 
600 mg 
 
600 mgv 
 
Study Drug Infusion 30 to <40 kgg,s,t,u 
900 mg 
900 mg 
 
900 mgv 
 
Study Drug Infusion ≥40 kgg,s,t,u 
1200 mg 
1200 mg 
 
1200 mgv 
 
Transition follow-up callw 
 
 
 
X 
 
a. 
In Clinic – visits must be conducted at the investigational sites; Remote – visits may be conducted remotely at a medical facility that is located near the 
subject’s home or at the subject’s home with the permission of the Investigator in accordance with all national, state, and local laws or regulations of the 
pertinent regulatory authorities. 
b. 
Shown as visit/week for Weight Cohorts ≥40 kg, 30 to <40 kg, and 20 to <30 kg (10 to <20 kg). 
c. 
Unscheduled visits and procedures will be performed at the Investigator's discretion, and results will be recorded in the eCRF. 
d. 
Perform an evaluation visit for CD as soon as possible within 48 hours of notification of symptom onset. The PI may schedule additional evaluation visits 
at their discretion. 
e. 
Patients who complete the study and transition to uninterrupted treatment with commercially available eculizumab will not be required to complete a 
follow-up visit.  
f. 
Collect weight with minimal clothing.  
g. 
Weight changes during the development and maturation of pediatric patients impact the dosing profile of eculizumab and should be adjusted to 
accommodate any growth changes in patients. Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies prohibit 
study drug to be prepared day-of visit, the weight from the most recent study visit should be used. For additional details on weight-based treatment 
regimens, refer to Table 15 for scheduled doses of eculizumab and Table 16 and Table 17 for supplemental doses of eculizumab. During the initial 

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induction phase, if a patient’s weight increases or decreases resulting in a change in weight cohort the Alexion medical monitor must be contacted prior to 
dosing. 
h. 
Collect height with no shoes or footwear.  
i. 
All AEs (serious and nonserious) will be collected from the signing of the informed consent form. 
j. 
Prior to study drug infusion, perform the MG-ADL, QMG, and MGC using a properly trained evaluator, preferably the same evaluator at approximately 
the same time of day throughout the study; MGFA-PIS must be performed by the PI or suitably-trained neurologist, preferably the same evaluator 
throughout the study.  
k. 
The recall period for the MG-ADL is the preceding 7 days, or since the last visit if the visit interval is < 7 days.  
l. 
Withhold acetylcholinesterase inhibitors for at least 10 hours prior to the QMG and MGC tests.  
m. 
Perform serum pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) 
may also be performed at any visit at the PI’s discretion. 
n. 
Perform urine pregnancy tests on all female patients of childbearing potential at the specified time points. Additional pregnancy tests (serum or urine) may 
also be performed at any visit at the PI’s discretion.  
o. 
Obtain Baseline and trough blood samples for PK, hemolysis, free C5, and ADA tests 5 – 90 minutes before study drug infusion. Obtain peak blood 
samples for PK, hemolysis, and free C5 tests 60-120 minutes after the completion of study drug infusion. Obtain 24 hour post dose blood samples for PK, 
hemolysis, and free C5 after study drug infusion at Visit 2 (Day 1). For the sample collected at 24 hours, there will be a window of ±1 hour for collecting 
the sample. 
p. 
Any test(s) medically indicated may be performed at the discretion of the Investigator. 
q. 
Patients must be revaccinated for N meningitidis, H influenzae, and S pneumoniae to provide active coverage according to current medical/country 
guidelines. 
r. 
Review the Participant Safety Information Card with the patient and caregiver to discuss the importance of carrying the safety card at all times. 
s. 
Administer study drug after completion of all other tests and procedures, excluding the peak blood sampling for PK, hemolysis, and free C5 assay.  
t. 
For supplemental weight-based eculizumab dosing please refer to Table 16 and Table 17.  
u. 
Should the patient’s weight increase ≥20kg during the study, dosing should be based on the most recently recorded body weight at a prior dosing visit and 
adjusted accordingly to ensure the proper dosing regimen per patients current weight. Refer to Table 15 for additional details on weight-based treatment 
regimens. 
v. 
Study drug infusion will occur at the EOS visit only. Study drug will not be administered at an ET visit. 
w. 
The Investigator must confirm with the patient or their guardian/caregiver by telephone that the transition to commercially available eculizumab occurred 
within 2 weeks of the last scheduled dose during the study. In the event that treatment with commercially available eculizumab is delayed, an unscheduled 
safety Follow-up Visit should occur on the day of initiating commercial eculizumab treatment or as soon as feasible.  
x. 
Clinical laboratory tests are to be performed every 6 months during the extension period. 
Abbreviations: ADA = antidrug antibodies; C5 = complement protein 5; CD = clinical deterioration; ECG = electrocardiogram; eCRF = electronic case report 
form; EOS = End of Study; EQ-5D-Y = European Quality of life 5 Dimension Youth; ET = early termination; F/U = Follow-up; MG = myasthenia gravis; MG-
ADL = Myasthenia Gravis Activities of Daily Living profile; MGC = Myasthenia Gravis Composite; MGFA-PIS = Myasthenia Gravis Foundation of America 
Post-Interventional Status; Neuro-QoL = Quality of Life in Neurological Disorders; PI = Principal Investigator; PK = pharmacokinetics; QMG = Quantitative 
Myasthenia Gravis Score for Disease Severity; T = trough sample; V = visit; W = week. 

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4.3. 
Protocol Definitions 
4.3.1. 
Clinical Deterioration and Rescue Therapy 
On-study rescue therapy (eg, high dose corticosteroid, plasma exchange [PE], or intravenous 
immunoglobulin [IVIg]) will be allowed when a patient experiences clinical deterioration as 
defined in this protocol. The rescue therapy used for a particular patient will be at the discretion 
of the Investigator. Every effort should be made to notify the Sponsor within 24 hours should a 
patient require rescue therapy.  
For this protocol, clinical deterioration warranting the use of on-study rescue therapy is defined 
as follows: 
• Patients who experience an MG crisis, which is defined as weakness due to MG that 
is severe enough to necessitate intubation or to delay extubation following surgery; 
or, 
• Significant symptomatic worsening that requires rescue medication in the opinion of 
the Investigator; or, 
• Patients for whom the Investigator believes that the patients’ health is in jeopardy if 
rescue therapy is not given. 
4.3.2. 
Clinical Evaluator 
Clinical Evaluators are study staff that have been trained and certified in administering the 
QMG, MG-ADL, and MGC. The Clinical Evaluator may be a neurologist, physical therapist, or 
other study team member delegated by the Investigator. Clinical Evaluator training and 
certification for this protocol will take place either at the Investigator's meeting or via the 
Sponsor's designated online training portal or other mechanism. 
4.3.3. 
Responsibilities for Myasthenia Gravis Assessments 
Responsibilities for MG assessments are summarized in Table 12. Throughout the study, MG 
assessments for an individual patient should be performed at approximately the same time of day 
by a properly trained evaluator, preferably the same evaluator. 
Table 12: 
Responsibilities for MG Assessments 
Assessment 
Evaluator 
MG-ADL 
Clinical Evaluator 
QMG including FVC 
Clinical Evaluator  
MGC (non-MMT Components) 
Clinical Evaluator  
MGC (MMT Components: neck flexion or extension, shoulder abduction, and hip 
flexion) 
PI or Neurologist  
MGFA-PIS  
PI or Neurologist  
MGFA Classification 
PI or Neurologist 
Abbreviations: FVC = forced vital capacity; MG-ADL = Myasthenia Gravis Activities of Daily Living Profile; 
MGC = Myasthenia Gravis Composite; MGFA = Myasthenia Gravis Foundation of America; 
MGFA-PIS = Myasthenia Gravis Foundation of America Post-Intervention Status; MMT = manual muscle test; 
PI = Principal Investigator; QMG = Quantitative Myasthenia Gravis. 

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5. 
STUDY POPULATION 
The study will enroll at least 12 eligible refractory pediatric gMG patients 12 to < 18 years of age 
to receive open-label eculizumab infusion, in order to obtain at least 10 evaluable patients aged 
12 to < 18 years for the primary endpoint, taking into account potential dropouts. Additional 
patients between the ages of 6 and 12 may be enrolled, but will not be included in the primary 
analysis. The number of eligible refractory pediatric gMG patients aged 12 to < 18 entering on 
maintenance IVIg treatment in this study will be capped at 6 patients. These patients must have 
been on maintenance IVIg for at least 12 months and on a stable dose ≥ 3 months prior to 
Screening, with frequency and dose expected to remain stable during Screening and for 12 weeks 
following the first dose of study drug. Efforts will be made to enroll at least 1 patient in each 
geographic region (North America, EU, and APAC). 
After 6 patients complete their Week 26 assessments, if the observed standard deviation in 
change in QMG is 8 or higher, the final sample size will be re-estimated to be at least 14 instead 
of 12 to preserve adequate power for testing the primary endpoint.  
Patients are eligible to be included in the study only if they satisfy all of the following 
inclusion/exclusion criteria. The Sponsor’s Medical Monitor must approve enrollment for each 
eligible patient. 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also known as 
protocol waivers or exemptions, is not permitted. 
5.1. 
Inclusion Criteria 
Patients must meet all of the following inclusion criteria: 
1. Male or female pediatric patients 6 to < 18 years of age at time of assent/consent. 
2. Patient’s legal guardian must be willing and able to give written informed permission and 
the patient must be willing to give written informed assent (if applicable as determined by 
the central or local Institutional Review Board [IRB]/Institutional [or Independent] Ethics 
Committee [IEC]) and comply with the study visit schedule.  
3. Parent or other legal guardian must be willing to comply with study requirements for the 
duration of the study.  
4. Vaccinated against N meningitidis within 3 years prior to, or at the time of, initiating 
eculizumab. Patients who initiate study drug treatment less than 2 weeks after receiving a 
meningococcal vaccine must receive appropriate prophylactic antibiotics until 2 weeks 
after the vaccination.  
5. Documented vaccination against H influenzae and S pneumoniae infections prior to 
dosing as per local and country specific immunization guidelines for the appropriate age 
group. 
6. Diagnosis of MG confirmed by positive serologic test for anti-AChR-Ab at Screening, 
and one of the following: 
a. 
History of abnormal neuromuscular transmission test demonstrated by single-
fiber electromyography or repetitive nerve stimulation, or 

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b. 
History of positive anticholinesterase test (eg, edrophonium chloride or 
neostigmine test), or 
c. 
Patient demonstrated improvement in MG signs on oral AChIs, as assessed by 
the Investigator. 
7. Presence of refractory gMG, defined as patients with gMG who have one or more of the 
following: 
a. Failed treatment ≥ 1 year with at least 1 IST, defined as:  
i. Persistent weakness with impairment of activities of daily living, or 
ii. Myasthenia gravis exacerbation and/or crisis while on treatment, or  
iii. Intolerance to ISTs due to side effect or comorbid condition(s). 
Immunosuppressants include, but are not limited to, corticosteroids, AZA, MMF, 
methotrexate (MTX), cyclosporine, tacrolimus, or cyclophosphamide. 
b. Require maintenance plasma exchange (PE) or IVIg to control symptoms (ie, 
patients who require PE or IVIg on a regular basis for the management of muscle 
weakness at least every 3 months over the last 12 months prior to Screening). 
c. In the opinion of the Investigator, MG poses a significant functional burden 
despite current MG treatment. 
8. Myasthenia Gravis Foundation of America (MGFA) Clinical Classification of Class II to 
IV at Screening. 
9. 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. 
10. All MG-specific treatment has been administered at a stable dosing regimen of adequate 
duration prior to Screening as follows: 
a. If patients who enter the study are receiving AZA, they must have been on AZA 
for ≥ 6 months and have been on a stable dose for ≥ 2 months prior to Screening. 
b. If patients who enter the study are receiving other ISTs (ie, MMF, MTX, 
cyclosporine, tacrolimus, or cyclophosphamide), they must have been on the IST 
for ≥ 3 months and have been on a stable dose for ≥ 4 weeks prior to Screening. 
c. If patients who enter the study are receiving maintenance IVIg at Screening, they 
must have been on maintenance IVIg for at least 12 months and on a stable dose 
for ≥ 3 months prior to Screening, with the frequency and dose expected to 
remain stable during Screening and for 12 weeks following the first dose of study 
drug. All other patients must not have received maintenance IVIg within 3 
months of Screening. 
d. If patients who enter the study are receiving oral corticosteroids, they must have 
been on a stable dose for ≥ 4 weeks prior to Screening. 
e. If patients who enter the study are receiving a cholinesterase inhibitor, they must 
have been on a stable dose for ≥ 2 weeks prior to Screening. 
11. Female patients of childbearing potential (ie, have achieved menarche) and male patients 
with female partners of childbearing potential must follow protocol-specified guidance 
for avoiding pregnancy while on treatment and for 5 months after the last dose of study 
drug. For additional details on contraception guidance, please refer to Section 11.9.  
12. Male patients with a female spouse/partner of childbearing potential or a pregnant or 
breastfeeding spouse or partner must agree to use double barrier contraception (male 

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condom plus appropriate barrier method for the female partner) while on treatment and 
for at least 5 months after the last dose of study drug. For additional details on 
contraception guidance, please refer to Section 11.9. 
5.2. 
Exclusion Criteria 
Patients will be excluded from study enrollment if they meet any of the following criteria: 
1. Parent or legal guardian is an Alexion employee.  
2. 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 
3. History of thymectomy within 12 months prior to Screening. 
4. Weakness only affecting ocular or periocular muscles (MGFA Class I). 
5. Myasthenia Gravis crisis or impending crisis at or during Screening (MGFA Class V). 
6. Are pregnant or lactating.  
7. 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. 
8. Unresolved meningococcal infection. 
9. For patients who are not receiving a stable maintenance dose of IVIg, as described in the 
Inclusion Criteria, use of IVIg (eg, as rescue therapy) within 4 weeks prior to first dose. 
10. Use of PE within 4 weeks prior to first dose. 
11. Use of rituximab within 6 months prior to first dose. 
12. Patients who are under 15 kg and are receiving maintenance IVIg. 
13. 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.  
14. Have previously received treatment with eculizumab or other complement inhibitors. 
15. Hypersensitivity to murine proteins or to one of the excipients of eculizumab. 
16. Any medical or psychological condition that, in the opinion of the Investigator, might 
interfere with the patient's participation in the study, poses any added risk for the patient, 
or confounds the assessment of the patient.  
17. Known or suspected history of drug or alcohol abuse or dependence within 1 year prior to 
the start of Screening 
5.3. 
Rationale for Inclusion or Exclusion 
Study ECU-MG-301 established the efficacy and safety of eculizumab in AChR-Ab positive 
refractory gMG patients aged ≥ 18 years. The inclusion/exclusion criteria in Study ECU-MG-
303 have been selected to characterize a pediatric population comparable to that of patients aged 

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≥ 18 years assessed in Study ECU-MG-301, with allowances for differences in disease 
presentation and treatment practice.  
Efficacy, safety, and PK/PD data obtained from this study, combined with data from the 
refractory gMG clinical program in patients aged ≥ 18 years and data from other indications in 
which eculizumab has been developed and for which pediatric data are available, is designed to 
inform the dose regimen and efficacy and safety profile of eculizumab in pediatric refractory 
gMG patients. 
5.4. 
Discontinuations 
5.4.1. 
Discontinuation of Patients 
The criteria for enrollment must be followed explicitly. If the investigational site identifies a 
patient who did not meet enrollment criteria and who was inadvertently enrolled, the Sponsor 
must be notified. If the Sponsor identifies a patient who did not meet enrollment criteria and who 
was inadvertently enrolled, the investigational site will be notified. A discussion must occur 
between the Sponsor and the Investigator to determine whether the patient may continue in the 
study, with or without study drug. Inadvertently enrolled patients may be maintained in the study 
and on study drug when the Sponsor agrees with the Investigator that it is medically appropriate 
for that patient. The Investigator must obtain documented approval from the Sponsor to allow the 
inadvertently enrolled patient to continue in the study with or without study drug. 
Patients will be permanently discontinued from the study in the following circumstances: 
• Enrollment in any other clinical study involving an investigational product or 
enrollment in any other type of medical research judged not to be scientifically or 
medically compatible with this study 
• Any of the following occur during the study: 
− Serious hypersensitive reactions (eg, anaphylaxis, bronchospasm with wheezing 
or requiring ventilator support or symptomatic hypotension, clinical syndrome 
suggestive of serum sickness, vasculitis)  
− Severe uncontrolled infection 
− Pregnancy or planned pregnancy 
• Adverse Event  
− If the Investigator decides that the patient should be withdrawn because of a 
serious adverse event (SAE) or a clinically significant laboratory value, the study 
drug is to be discontinued and appropriate measures are to be taken. The Sponsor 
or its designee is to be alerted immediately. Refer to Section 9. 
• Investigator Decision [Physician Decision] 
− The Investigator decides that the patient should be discontinued from the study in 
the best interest of the patient. 
• Patient Decision [Withdrawal by Patient or Withdrawal by Parent/Guardian] 

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− The patient or the patient’s legal representative (ie, parents or legal guardian) 
requests to be withdrawn from the study 
• Sponsor Decision 
− The Sponsor or Health Authority may terminate the study for reasonable cause. 
Conditions that may warrant termination of the study include, but are not limited 
to: 
− Discovery of an unexpected, serious, or unacceptable risk to patients enrolled 
in the study 
− Sponsor decision to suspend or discontinue testing, evaluation, or 
development of the study drug 
− Failure of the Investigator to comply with the approved protocol, pertinent 
guideline and/or regulations 
− Submission of knowingly false information from the Investigator to the 
Sponsor and/or regulatory authorities  
− The Sponsor medical monitor deems it is in the best interest of the patient 
Should the study be terminated early, the Sponsor will notify the national competent authority 
and the IRB or IEC according to local requirements.  
Patients who discontinue the study early will have an ET visit at the time of withdrawal and a 
Follow-up Visit at 8 weeks following the last eculizumab dose performed, as shown in the 
Schedule of Assessments (Table 4 through Table 11). If a female patient is permanently 
discontinued from eculizumab treatment due to pregnancy, the Investigator will attempt to 
follow-up with the patient until the outcome of the pregnancy is established.  
5.4.2. 
Discontinuation of Study Sites/Site Terminated  
Study site participation may be discontinued if the Sponsor or its designee, the Investigator, or 
the IRB or IEC of the study site judges it necessary for medical, safety, regulatory, or other 
reasons consistent with applicable laws, regulations, and Good Clinical Practices (GCP). 
5.4.3. 
Discontinuation of the Study/Study Terminated  
The study will be discontinued if the Sponsor or its designee or any regulatory authority judges it 
necessary for medical, safety, regulatory, or other reasons consistent with applicable laws, 
regulations, and GCP. 

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6. 
STUDY DRUG MATERIALS AND MANAGEMENT 
6.1. 
Study Drug 
6.1.1. 
Study Drug Labeling 
The study drug, eculizumab, will be manufactured and supplied by Alexion or a contract 
manufacturing organization in single 30 mL vials as a solution concentration of 10 mg/mL. Each 
vial contains 300 mg of eculizumab for intravenous (IV) administration. Eculizumab will be 
individually packaged in kits. Both vials and kits will be labeled according to the protocol and 
local regulatory requirements. 
Study drug orders will be released to each site upon receipt of all required documents based upon 
applicable regulations. Details are provided in the Pharmacy Manual. 
Table 13: 
Study Drug 
Product Name 
Eculizumab 
Dosage Form 
Concentrate for solution for infusion 
Unit Dose 
300 mg 
Route of Administration 
Intravenous infusion 
Physical Description 
30 mL vial 
Manufacturer 
Alexion or a contract manufacturing organization 
6.1.2. 
Study Drug Storage 
Upon arrival at the center, the study drug should be promptly removed from the shipping cooler 
and stored in refrigerated conditions between 2°C to 8°C. The study drug must be stored in a 
secure, limited-access storage area, and temperature must be monitored daily. On-site storage 
temperature excursions must be reported to the Sponsor in a timely manner.  
Diluted solutions of study drug (dosing solutions) may be stored between 2°C to 8°C (36°F to 
46°F) and at room temperature for a maximum of 24 hours. The 24-hour expiration includes 
preparation time, storage time, warming time, and infusion time. The solution should be allowed 
to warm to room temperature prior to administration. The material must not be heated (eg, by 
using a microwave or other heat source) other than by ambient air temperature.  
Refer to the Pharmacy Manual for additional instructions. 
6.1.3. 
Study Drug Preparation 
Infusions of study drug should be prepared using aseptic technique. Each vial of study drug 
contains 300 mg of active ingredient in 30 mL of product solution. Withdraw the required 
amount of study drug from the vials. Transfer the recommended dose to an infusion bag. Dilute 
the study drug to a final concentration of 5 mg/mL by addition to the infusion bag of the 
appropriate amount (equal volume) of 0.9% Sodium Chloride Injection, USP; 0.45% Sodium 
Chloride Injection, USP; 5% Dextrose in Water Injection, USP; or Ringer’s Injection, USP. The 
final volume of a 5 mg/mL diluted study drug solution is 60 mL for 300 mg doses (1 vial), 
120 mL for 600 mg doses (2 vials), 180 mL for 900 mg doses (3 vials), and 240 mL for 1200 mg 
doses (4 vials) as shown in Table 14. 

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Table 14: 
Study Drug Reconstitution 
Study Drug 
Volume of 
Study Drug 
Volume of Diluenta 
Total Volume of Administration 
300 mg (1 vial) 
30 mL 
30 mL 
60 mL 
600 mg (2 vials) 
60 mL 
60 mL 
120 mL 
900 mg (3 vials) 
90 mL 
90 mL 
180 mL 
1200 mg (4 vials) 
120 mL 
120 mL 
240 mL 
 Choose one of the following diluents: 1) 0.9% sodium chloride; 2) 0.45% sodium chloride; 3) 5% dextrose in 
water; 4) Ringer’s injection. 
Gently invert the infusion bag containing the diluted study drug solution to ensure thorough 
mixing of the product and diluents. Discard any unused portion left in a vial, as the product 
contains no preservatives. The diluted solution should be allowed to warm to room temperature 
by exposure to ambient air prior to administration. 
6.1.4. 
Study Drug Administration 
Study drug should only be administered via IV infusion, using a weight-based schedule 
(Section 6.2). DO NOT ADMINISTER AS AN IV PUSH OR BOLUS INJECTION. 
Prior to study drug administration, the diluted solution should be allowed to warm to room 
temperature by exposure to ambient air. The diluted solution must not be heated in a microwave 
or with any heat source other than ambient air temperature. Parenteral drug products should be 
inspected visually for particulate matter and discoloration prior to administration.  
The diluted study drug should be intravenously administered over 1 to 4 hours in pediatric 
patients. For those patients who reach ≥ 18 years of age during the study, the study drug should 
be administered intravenously over 35 (± 10) minutes. It is not necessary to protect the infusion 
bags from light while study drug is being administered to the patient. The patient should be 
monitored for at least 1 hour following infusion.  
If an AE occurs during administration of the study drug, the infusion may be slowed or stopped 
at the discretion of the Investigator, depending upon the nature and severity of the event; 
however, the overall duration should not exceed 2 hours from the start of the infusion in patients 
aged ≥ 18 years and 4 hours from the start of infusion in pediatric patients. In patients aged ≥ 18 
years on maintenance IVIg, the overall duration should not exceed 4 hours from the start of the 
infusion. The AE must be captured in the patient’s source document and eCRF.  
The actual start and stop times of all dose administrations will be recorded in the patient’s source 
documents and eCRF. Refer to the Pharmacy Manual for additional directions on study drug 
administration. 
Sites must have resuscitation equipment, emergency drugs, and appropriately trained staff 
available during the infusion, and for at least 1 hour after patients have completed their infusion.  
6.1.5. 
Study Drug Accountability 
When a study drug shipment is received at the site, the pharmacist should verify the contents, 
sign the packing invoice provided with the shipment, and maintain the original copy for review 
by the study monitor. Additionally, reception of study drug (as well as reception conditions) 

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must be reported to the Interactive Response Technology (IRT) system to allow drug 
randomization, resupply, estimations, and drug expiration control.  
Unless notified otherwise, empty vials and vials with residual materials should be kept for 
inspection and accountability by the study monitor prior to their destruction or handled per local 
pharmacy standard operating procedures (SOPs) for clinical study drugs. Destruction of used and 
unused vials, either locally or centrally, must be properly documented. Drug accountability will 
be managed through the IRT system and detailed instructions on managing the IRT drug 
accountability module will be included in the IRT User Guide. The IRT module will perform 
accountability in two stages, where site personnel will complete an initial accountability entry in 
the system followed by confirmation by the CRA that the site has correctly entered the 
appropriate status for all IP. The pharmacist or designee must maintain accurate records 
demonstrating dates and amount of IP received, to whom dispensed (subject-by-subject 
accounting), and accounts of any IP accidentally or deliberately destroyed. These drug 
accountability records must be readily available upon request and will be reviewed throughout 
the study. 
Each kit will have a label and a place for the pharmacist to record the patient number and initials.  
The study monitor will examine the inventory during the study. Additionally, the inventory 
records must be readily available to regulatory authorities, the local regulatory agency, or an 
independent auditor’s inspection at any time. 
Refer to the Pharmacy Manual for additional information.  
6.1.6. 
Study Drug Handling and Disposal 
All clinical study material provided to the Investigator will be stored in a secure place and 
allocated and dispensed by appropriately trained personnel. Detailed records of the amounts of 
the study drug received, dispensed, and destroyed will be maintained. 
To satisfy regulatory requirements regarding drug accountability, all remaining eculizumab 
inventory will be reconciled and destroyed or returned to Alexion at the end of the study 
according to applicable regulations. 
Refer to the Pharmacy Manual for further information. 
6.2. 
Dosing Regimen 
6.2.1. 
Rationale for Selection of Doses in the Study 
The doses of eculizumab to be administered in this study have been selected to produce 
eculizumab trough concentration coverage comparable to that observed in Study ECU-MG-301, 
in which the efficacy and safety of eculizumab in adult patients (18 years of age or older) with 
refractory AChR-Ab positive gMG was established. A modeling and simulation study was 
completed to support the planned bodyweight-categorized dose regimens, which is described in 
further detail below. 
Demonstrating PK bridging between aHUS and refractory gMG patients aged ≥ 18 years was 
critical to select dose regimens for pediatric patients with refractory gMG, as substantial 
pediatric data has been generated for pediatric patients with aHUS, and no prior PK data from 

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pediatric patients with refractory gMG exists. The successful PK bridging enables extrapolation 
of the aHUS pediatric data and corresponding PK model to pediatric patients with refractory 
gMG. Simulations using the aHUS PK model and gMG PK model, respectively, demonstrated 
the comparability of eculizumab serum concentration time profiles between patients with aHUS 
and patients with refractory gMG for body weight ≥ 40 kg.  
Demonstrating PD bridging between aHUS/paroxysmal nocturnal hemoglobinuria (PNH) and 
patients aged ≥ 18 years with refractory gMG was also important. Using PK and PD data from 
patients aged ≥ 18 years and pediatric patients with aHUS and patients aged ≥ 18 years and 
pediatric patients with PNH, the PK/PD (hemolysis) analysis identified an eculizumab threshold 
concentration range of 50-100 μg/mL to achieve complete inhibition of hemolysis.  
Using PK and PD data from patients aged ≥ 18 years with refractory gMG from Studies C08-001 
and ECU-MG-301, the PK/PD analysis of hemolysis or free C5 identified an eculizumab 
threshold serum concentration of 85 μg/mL to achieve complete inhibition of hemolysis, which 
is within the range of 50-100 μg/mL identified above in aHUS.  
Therefore, the PD bridging was successfully demonstrated between the 2 indications. 
In both aHUS and gMG PK models, body weight was identified as the only important covariate 
and, therefore, body weight categorical-based dosing is recommended in the pediatric 
population. The body weight exponent for the aHUS PK model was used, because the aHUS PK 
model leveraged the prior pediatric PK data within the weight range of interest.  
The aHUS PK model was used to simulate eculizumab concentration time profiles for the 
pediatric patients with refractory gMG. The simulation results showed that overall the proposed 
dosing regimens across the body weight categories essentially maintained therapeutic levels of 
eculizumab. Hence, the proposed bodyweight-categorized dosing regimens are expected to 
achieve immediate, sustained, and complete inhibition of terminal complement in pediatric 
patients with refractory gMG. 
Complete and sustained inhibition of complement activity will be confirmed with PK/ PD data 
derived from this study. 
6.2.2. 
Dosing Regimen Preparation and Administration 
Eculizumab will be administered weekly during the initial induction phase and every 2 weeks 
during the maintenance phase. The dosing regimen will be based on the pediatric patient’s body 
weight (Table 15). 
Table 15: 
Weight-based Dosing Regimen of Eculizumab 
Weight Cohortab 
Induction Phase 
Maintenance Phase 
≥ 40 kg 
900 mg weekly × 4 doses 
1200 mg at Week 4; then every 2 weeks 
30 to < 40 kg 
600 mg weekly × 2 doses 
900 mg at Week 2; then every 2 weeks 
20 to < 30 kg 
600 mg weekly × 2 doses 
600 mg at Week 2; then every 2 weeks 
10 to < 20 kg 
600 mg weekly × 1 dose 
300 mg at Week 1; then every 2 weeks 
a Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies prohibit 
study drug to be prepared day-of visit, the weight from the most recent study visit should be used 
b During the initial induction phase, if a patient’s weight increases or decreases resulting in a change in 
weight cohort, the Alexion medical monitor must be contacted prior to dosing. 

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Eculizumab 300 mg, 600 mg, 900 mg, or 1200 mg will be administered via IV infusion based on 
the patient’s most recently recorded body weight at a prior dosing visit, as presented in Table 15. 
Doses of study drug must only be prepared and dispensed by qualified study personnel. Study 
drug is to be dispensed only to enrolled patients who are confirmed eligible for participation in 
this study. Once study drug is prepared for a patient, it can only be administered to that patient. 
Vials of study drug are for one-time use only, and any drug product remaining in the vial should 
not be used for another patient. Any drug remaining in the infusion tubing or infusion bag should 
not be used for another patient. 
Further details on preparation and dose administration of eculizumab, as well as disposal of the 
study drug, can be found in the Pharmacy Manual.  
6.2.3. 
Supplemental Eculizumab Doses in Patients Receiving Maintenance IVIg 
Treatment 
Maintenance IVIg treatment may interfere with the endosomal neonatal Fc receptor (FcRn) 
recycling mechanism of monoclonal antibodies and, thus, may decrease serum eculizumab 
concentrations (Jin, 2005; Wang, 2008; Fitzpatrick, 2011). Fitzpatrick et al reported that, in adult 
multifocal motor neuropathy, patients receiving cycles of IVIg 1 g/kg over 1 to 5 days and 
repeated on average at 4-weekly intervals, eculizumab treatment resulted in a significantly lower 
median eculizumab exposure (78.7 μg/mL, interquartile range [IQR] 55–108) compared to 
exposure in patients not receiving IVIg (119.7 μg/mL, IQR 95–147), which translates to an 
approximate median increase of 50% in the clearance of eculizumab under IVIg co-
administration (Fitzpatrick, 2011).  
Therefore, for pediatric gMG patients receiving maintenance IVIg treatment, a series of 
supplemental doses of eculizumab will be administered to account for the anticipated 
approximately 50% increase in eculizumab clearance. For further details on supplemental 
dosing, please refer to Table 16. In addition, patients are to continue eculizumab infusion 
according to the protocol-specified dosing regimen. 
 

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Table 16: 
Supplemental Dosing Regimen of Eculizumab in Patients Receiving 
Maintenance IVIg  
Weight 
Cohorta,b 
Induction 
Phase 
Supplemental 
Dose 
Induction 
Phase 
Total Dose 
Maintenance 
Phase 
Supplemental 
Dose 
Maintenance 
Phase 
Total Dose 
≥ 40 kg 
600 mg 
1500 mg 
600 mg 
1800 mg 
30 to < 40 kg 
300 mg 
900 mg 
600 mg 
1500 mg 
20 to < 30 kg 
300 mg 
900 mg 
300 mg 
900 mg 
10 to < 20 
kgc 
300 mg 
900 mg 
300 mg 
600 mg 
a Dose regimen will be based on the current visit’s recorded body weight. If site/institution policies 
prohibit study drug to be prepared day-of visit, the weight from the most recent study visit should 
be used 
b During the initial induction phase, if a patient’s weight increases or decreases resulting in a 
change in weight cohort, the Alexion medical monitor must be contacted prior to dosing 
c Only patients in 15-20 kg weight category to be included in this group. 
Notes: The timing of supplemental eculizumab dosing varies by IVIg frequency and is provided 
below: 
• 
If a patient continues to receive IVIg treatment at a dose cycle interval equal to or more 
frequent than every 4 weeks during eculizumab treatment, a supplemental dose will be 
administered at the same time that each scheduled dose of eculizumab is administered. 
• 
If a patient receives IVIg treatment at a dose cycle interval less frequent than every 4 weeks 
during eculizumab treatment, a supplemental dose will be administered following the last dose 
of the IVIg infusion cycle at the next scheduled eculizumab dose. 
If a patient receives IVIg treatment within 4 weeks prior to receiving the first dose of eculizumab, a 
supplemental dose of eculizumab will be administered at the same time that the first dose of 
eculizumab is administered (ie, the total dose is the supplemental dose plus the first scheduled 
dose). 
For patients who enter the study on a stable IVIg maintenance dose regimen, PK/PD samples 
will be analyzed after the first 4 weeks of eculizumab administration for the evaluation of 
eculizumab exposure. If the PK concentration values are greater than 1790 µg/mL (Alexion 
Internal Report: ECU-MG-Adult PK-PD Modeling Report, Addendum ECU-MG-302), the 
maximum concentration value observed in Studies ECU-MG-301 and ECU-MG-302 in patients 
with refractory gMG, the supplemental dose of eculizumab may be adjusted downward or 
waived, as appropriate, so that the predicted maximum PK concentration is below 1790 μg/mL. 
6.2.4. 
Supplemental Eculizumab Doses Following Rescue Therapy 
When IVIg is administered as acute rescue therapy for clinical deterioration, no supplemental 
dose of eculizumab should be administered. However, if a patient receives more than 1 dose 
cycle of IVIg as rescue therapy within a 12-week period, supplemental eculizumab should be 
administered after the last dose of the second IVIg cycle and at the end of each subsequent IVIg 
dose cycle within the 12-week period in accordance with Table 16. 
If a patient undergoes PP/PE/FFP for clinical deterioration during the study, a supplemental dose 
of study drug must be administered within 1 to 2 hours after each PP/PE/FFP session unless the 
PP/PE/FFP session is on the day of a scheduled study drug infusion. If FFP has been 
administered, a supplemental dose of study drug must be administered 1 hour prior to each 

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infusion of FFP. If the PP/PE/FFP is on the day of a scheduled study drug infusion, the 
scheduled dose of study drug (instead of the supplemental dose) should be administered within 1 
to 2 hours after the completion of PP/PE/FFP session. For further details on supplemental dosing 
please refer to Table 17. In addition, patients are to continue eculizumab infusion according to 
the protocol specified dosing regimen. 
Table 17: 
Supplemental Dosing Regimen of Eculizumab for Plasma Exchange/Plasma 
Infusion 
Type of 
Intervention 
Most Recent 
Eculizumab 
Dose 
Supplemental Eculizumab 
Dose With Each Plasma 
Exchange/Plasma Infusion 
Intervention 
Timing of Supplemental 
Eculizumab dose 
Plasmapheresis or 
plasma exchange 
300 mg 
300 mg per each 
plasmapheresis or plasma 
exchange session 
Within 1 to 2 hours after each 
plasmapheresis or plasma exchange 
600 mg or more 
600 mg per each 
plasmapheresis or plasma 
exchange session 
Fresh frozen 
plasma infusion 
300 mg or more 
300 mg per infusion of fresh 
frozen plasma 
Approximately 60 minutesa prior to 
each infusion of fresh frozen 
plasma 
a Supplemental dosing of eculizumab should occur 60 ± 15 minutes prior to each infusion of fresh frozen plasma. 
6.3. 
Concomitant Medications  
6.3.1. 
Allowed Medications 
Palliative and supportive care is permitted during the course of the study for underlying 
conditions. Patients may continue to receive AChI, IVIg, and ISTs during the study where 
applicable under certain restrictions. For patients who enter the study receiving any background 
therapy, the dose/schedule may not be changed during the Primary Evaluation Treatment Period 
before Week 12, unless deemed necessary per the Investigator based on clinical safety evaluation 
and if Sponsor approval is obtained. Dose change with background medication is permitted after 
Week 12 at the Investigator’s discretion and with Sponsor notification.  
During the Extension Period, changes in background medications will be permitted at the 
Investigator’s discretion and with Sponsor notification.  
Changes in concomitant medications and/or nondrug therapies and procedures will be recorded 
in the eCRF. 
The following additional restrictions apply: 
• Acetylcholinesterase inhibitors 
− Acetylcholinesterase inhibitor treatment must be withheld for at least 10 hours 
prior to administration of the QMG and MGC tests.  
• Immunosuppressive therapies: 

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− The following ISTs are allowed during the study: corticosteroid, AZA, MMF, 
MTX, tacrolimus, cyclosporine, or cyclophosphamide. The ISTs and the 
appropriate dose levels to be used for an individual patient will be at the 
discretion of the treating physician. During the Primary Evaluation Treatment 
Period, the patient’s IST dose may be adjusted on the basis of 
weight/body-surface/age to account for the child’s growth. 
− High-dose steroid should be reserved for patients that experience clinical 
deterioration as defined by this protocol. Every effort should be made to notify the 
Sponsor within 24 hours of administration should a patient require a rescue 
therapy for clinical deterioration. 
• Intravenous immunoglobulin  
− If a patient enters the study receiving maintenance IVIg, a supplemental dose of 
study drug will be administered at the first scheduled dose. Subsequent 
supplemental dosing will be informed as described in Section 6.2.3.  
• Plasma Exchange/Plasmapheresis/Fresh Frozen Plasma (PE/PP/FFP) 
− Use of PE/PP/FFP will be allowed as rescue therapy for patients who experience a 
clinical deterioration as defined by this protocol. The rescue therapy used for an 
individual patient will be at the discretion of the treating physician. Every effort 
should be made to notify the Sponsor within 24 hours should a patient require a 
rescue therapy.  
− If a patient undergoes PE during the study, a supplemental dose of study drug 
must be administered (Section 6.2.4).  
6.3.2. 
Disallowed Medications 
The use of rituximab and SC Ig is prohibited during the study. 
6.3.3. 
Clinical Deterioration and Rescue Therapies 
The use of permitted on-study rescue therapy is described in Section 4.3.1. 
6.3.4. 
Vaccination 
As with any terminal complement antagonist, the use of eculizumab increases the patient’s 
susceptibility to meningococcal infection (N meningitidis). To reduce the risk of meningococcal 
infection, all patients must be vaccinated against meningococcal infections within the 3 years 
prior to, or at the time of, initiating study drug. Patients who initiate study drug treatment less 
than 2 weeks after receiving a meningococcal vaccine must receive treatment with appropriate 
prophylactic antibiotics until 2 weeks after vaccination. Patients must be vaccinated or 
revaccinated according to current national vaccination guidelines or local practice for 
vaccination use with complement-inhibitors (eg, eculizumab). 
Vaccines against serotypes A, C, Y, W135, and B, where available, are recommended to prevent 
common pathogenic meningococcal serotypes. 

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Patients who cannot be vaccinated must receive antibiotic prophylaxis for the entire treatment 
period and for 5 months following the last dose of eculizumab.  
In addition to meningococcal vaccination, patients must be vaccinated against H influenzae and 
S pneumoniae, and strictly adhere to the national vaccination recommendations for each age 
group.  
Due to the length of the Extension Period of this study, patients may be revaccinated for 
appropriate vaccinations based on adherence to the national vaccination recommendations for 
each age group to provide active coverage according to current medical/country guidelines. 
Investigators will assess the need for revaccination, which will be recorded in the source 
documents and electronic case report form (eCRF). 
6.4. 
Treatment Compliance 
The infusion of study drug into patients will be under the supervision of the Investigator or their 
designee to ensure that the patients received the appropriate dose at the appropriate time-points 
during the study. 
Patients who fail to return for a scheduled visit within the acceptable visit windows (±2 days) 
must be contacted by the site study staff to determine the reason for missing the appointment. 
Patients should be strongly encouraged to return to the investigational site for evaluation if 
clinical deterioration or an AE is suspected to have occurred. In the exceptional circumstance, if 
a patient cannot or does not come to the study site for examination, the patient will be instructed 
to see his or her local neurologist or physician. In this event, the investigational site will (or 
attempt to) obtain relevant medical records as documentation from the local physician’s 
examination, and enter relevant data in the eCRF as appropriate.  
As it is vital to obtain information on any patient’s missing visit (in-clinic or remote) to assure 
the missing appointment was not due to a clinical deterioration or an AE, every effort must be 
made to undertake protocol-specified follow-up procedures (Table 5 and Table 7 based on 
weight cohort). Follow-up due-diligence documentation will consist of 3 phone calls followed by 
1 registered letter to the patient’s last known address, and documented in both the source 
documents and the eCRF. 
Patients should be registered in the IXRS as soon as the Study ECU-MG-303 informed consent 
form (ICF) is signed. The initial shipment of study drug for Study ECU-MG-303 will be 
triggered by the IXRS. 
6.5. 
Continued Access to Study Drug 
After completing the 26-week Primary Evaluation Treatment Period, patients will continue 
receiving eculizumab in the Extension Period for up to additional 208 weeks.  

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7. 
ASSESSMENT OF EFFICACY 
Efficacy assessments will be performed as summarized in the Schedules of Assessments 
(Section 4.2). Preferably, the same parent or guardian is recommended to be available to 
accompany the child to each visit in order to reduce variability in endpoint reporting. 
7.1. 
Quantitative Myasthenia Gravis Score 
The QMG scoring system consists of 13 items: ocular (2 items), facial (1 item), bulbar (2 items), 
gross motor (6 items), axial (1 item), and respiratory (1 item); each graded 0 to 3, with 3 being 
the most severe (Appendix 1). The range of total QMG score is 0 to 39. The QMG scoring 
system is considered to be an objective evaluation of therapy for MG and is based on quantitative 
testing of sentinel muscle groups. The MGFA task force has recommended that the QMG score 
be used in prospective studies of therapy for MG. 
A modified QMG score has been developed for use in patients younger than 12 years of age that 
will be used for patients aged 6 to 11 years at the time of Screening (Goldstein, 2015; 
Appendix 2). The modified QMG omits the assessment of grip strength and uses a modified 
assessment of swallowing (slurp test) compared to the traditional QMG, with total scores ranging 
from 0 to 21. In this study, patients will continue to be evaluated based on the QMG scale 
initially completed upon entry into the study. Change in age during the study will not constitute a 
patient changing the type of survey completed (ie, a patient who enrolls at age 11 will continue 
being assessed with the modified QMG scale even after he or she reaches 12 years of age). The 
QMG assessment will be administered at the protocol-specified time points at approximately the 
same time of day by a properly trained evaluator, preferably the same evaluator, throughout the 
study. 
7.2. 
Myasthenia Gravis Activities of Daily Living Score 
The MG-ADL is an 8-point questionnaire that focuses on relevant symptoms and functional 
performance of activities of daily living in MG patients (Appendix 3). The 8 items of the 
MG-ADL were derived from symptom-based components of the original 13-item QMG to assess 
disability secondary to ocular (2 items), bulbar (3 items), respiratory (1 item), and gross motor or 
limb (2 items) impairment related to effects from MG. In this functional status instrument, each 
response is graded 0 (normal) to 3 (most severe). The range of total MG-ADL score is 0 to 24. 
The recall period for MG-ADL is the preceding 7 days or since the last visit if the visit interval is 
less than 7 days. The MG-ADL assessment will be administered at the protocol-specified time 
points at approximately the same time of day by a properly trained evaluator, preferably the same 
evaluator, throughout the study.  
For patients <12 years of age, caregiver assistance can be provided during the MG-ADL 
assessment. 
7.3. 
Myasthenia Gravis Composite Score 
The MGC is a validated assessment tool for measuring clinical status of patients with MG 
(Burns, 2010). The MGC assesses 10 important functional areas most frequently affected by 
MG, and the scales are weighted for clinical significance that incorporates patient-reported 
outcomes (Appendix 4). The range of total MGC score is 0 to 50. Higher scores indicate more 

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functional impairment. In this study, the MGC assessment will be administered at the 
protocol-specified time points at approximately the same time of day by a properly trained 
evaluator, preferably the same evaluator, throughout the study. 
7.4. 
Myasthenia Gravis Foundation of America Post-Intervention Status 
The MG clinical state will be assessed using the MGFA Post-Intervention Status. Change in 
status categories of Improved, Unchanged, Worse, as well as the Minimal Manifestation will be 
assessed by the PI or the same neurologist skilled in the evaluation of MG patients throughout 
the study (Appendix 11).  
7.5. 
European Quality of Life 5-Dimension  
The EQ-5D-Y (Appendix 5) is a reliable and validated survey of health status in 5 areas: 
mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, each of which is 
completed by the patient for patients ≥ 12 years of age (at time of assessment) and completed by 
the patient’s caregiver or with caregiver assistance for patients <12 years of age (Szende, 2014). 
Each area has 3 levels: Level 1 (no problems), Level 2 (some problems), and Level 3 (extreme 
problems). The EQ visual analogue scale (VAS) records the patient’s self-rated health on a 
vertical, 20 cm VAS where the endpoints are labeled ‘Best imaginable health state, marked as 
100’ and ‘Worst imaginable health state, marked as 0’. Patients will continue to be evaluated 
based on the survey initially completed upon entry into the study. Change in age during the study 
will not constitute a patient changing the type of survey completed. Patients who are younger 
than the lowest age range of the survey (ie, patients < 8 years of age) will be evaluated using the 
proxy version of the EQ-5D-Y (Appendix 6). The parent or legal guardian (the proxy) will be 
asked to rate the child’s health-related quality of life in their (the proxy’s) opinion. The EQ-5D-
Y assessment will be administered at the protocol-specified time points at approximately the 
same time of day throughout the study. 
7.6. 
Neurological Quality of Life Fatigue Questionnaire 
The Neuro-QoL Pediatric Fatigue questionnaire (Appendix 7) is a reliable and validated brief 
11-item survey of fatigue, completed by the patient for patients ≥ 12 years of age (at time of 
assessment) and completed by the patient’s caregiver or with caregiver assistance for patients 
<12 years of age (Cella, 2010). Higher scores indicate greater fatigue and greater impact of MG 
on activities. Patients will continue to be evaluated based on the survey initially completed upon 
entry into the study. Change in age during the study will not constitute a patient changing the 
type of survey completed. Patients who are younger than the lowest age range of the applicable 
scale (ie, patients < 8 years of age) will be evaluated using the PROMIS Parent Proxy Item Bank 
v2.0 – Fatigue – Short Form 10a questionnaire (Appendix 8). The parent or legal guardian (the 
proxy) will complete the measure on the child’s behalf following administration of these 
instructions: “The following questionnaires will ask about your child’s symptoms and activity 
levels; his/her ability to think, concentrate and remember things; questions specific to his/her 
condition, and questions related to his/her quality of life. Please answer the following questions 
based on what you think your child would say.” The Neuro-QoL Pediatric Fatigue questionnaire 
will be administered at the protocol-specified time points at approximately the same time of day 
throughout the study. 

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8. 
ADDITIONAL ASSESSMENTS 
8.1. 
Myasthenia Gravis Disease Biomarker 
Blood samples for assay of the AChR-Ab will be collected at Screening as specified in the 
Schedules of Assessments (Section 4.2). 
8.2. 
Pharmacokinetics and Pharmacodynamics 
Blood samples will be collected at specified time points to study the PK of eculizumab in 
pediatric patients with refractory gMG. Pharmacokinetic parameters such as maximum 
concentration and concentration after the first dose, and during the induction and maintenance 
treatment phase will be obtained. Clearance and terminal half-life will be estimated. 
Blood samples for PD analysis will be collected at specified time points to assess pre-and 
post-treatment serum hemolytic activity and, therefore, C5 complement activity inhibition. 
Baseline PK and PD samples will be collected 5-90 minutes prior to the first dose, and peak 
samples will be collected 60-120 minutes after the first dose and at other time points in the SoA. 
An intermediate blood sample will also be collected 24 hours after completion of the first dose. 
For the sample collected at 24 hours, there will be a window of ± 1 hour for collecting the 
sample. The date and exact time of collection must be recorded on the eCRF and the central 
laboratory requisition form. 
Blood samples collected for PK and PD will be kept frozen and stored at Alexion 
Pharmaceuticals, Inc. for a maximum of 5 years after all the specified PK and PD data will have 
been collected for the study. The frozen samples may be used for future research related to 
eculizumab. Each sample will be given a code. This code will allow the patient sample to be 
used without the researchers knowing the patient’s name. The results of the research may be 
presented at scientific meetings or in publications; however, patient identity will not be 
disclosed. All other blood and urine samples collected during the study will be destroyed after 
the tests have been completed. 

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9. 
ASSESSMENT OF SAFETY 
The collection of AEs will be monitored from the signing of informed consent until study 
completion. Investigators are instructed to follow any AEs through to their conclusion 
(resolution or stabilization) as described in Section 9.6.8. In the event of patient withdrawal from 
the study, AE monitoring should continue through the last patient’s last study visit if possible.  
The timing of the clinical and laboratory assessments to be performed is specified in the 
Schedule of Assessments (Section 4.2). Any clinically significant abnormal results should be 
followed until resolution or stabilization.  
9.1. 
Physical Examinations 
Each examination will include the following assessments: general appearance of skin, head, ears, 
eyes, nose, throat, neck, lymph nodes, chest, heart, abdomen, extremities, and general neurologic 
system. Physical growth (height [cm], weight [kg]) will be assessed. The accurate weighing of 
patients is vital as part of their management, as eculizumab dosing will depend on the patient’s 
recorded body weight at the most recent dosing visit. It is recommended that patients should be 
weighed in the same amount of clothing in each instance where weight is assessed. 
9.2. 
Vital Signs 
Vital sign measurements will be taken after the patient has been resting for at least 5 minutes and 
will include systolic and diastolic blood pressure (millimeters of mercury [mmHg]), heart rate 
(beats/minute), respiratory rate (breaths/minute), and temperature (degrees Celsius [°C] or 
degrees Fahrenheit [°F]). Vital signs will be taken prior to each administration of study drug. 
9.3. 
Laboratory Assessments (Pregnancy Screen, Serum Chemistry, and 
Hematology) 
Samples for urine pregnancy, hematology, and chemistry will be performed at the times 
specified for clinical laboratory tests in the Schedule of Assessments (Section 4.2). Specific 
laboratory assessments are provided in Appendix 12. For clinic visits indicating laboratory 
assessments as required, the samples for laboratory assessments will be collected before 
administration of study drug.  
It is anticipated that some laboratory values may be outside the normal value range due to 
underlying disease. The Investigators should use their medical judgment when assessing the 
clinical significance of these values. Clinical significance is defined as any variation in 
laboratory measurements that has medical relevance and that results in a change in medical care. 
If clinically significant laboratory changes from Baseline resulting in medical intervention are 
noted, the changes will be documented as AEs on the AE eCRF. The Investigator will also assess 
the relationship to study drug for all clinically significant out-of-range values (Section 9.6.5). 
The Investigator will continue to monitor the patient through additional laboratory assessments 
until (1) values have returned to the normal range or baseline level, or (2) in the judgment of the 
Investigator, values that are outside the normal range are not related to the administration of 
study drug or other protocol-specific procedures. 

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9.4. 
Electrocardiograms 
For each patient, 12-lead digital electrocardiograms (ECGs) will be collected according to the 
Schedule of Assessments (Section 4.2). Patients must be supine for approximately 5 to 10 
minutes before ECG collection and remain supine but awake during ECG collection. 
The Investigator or designee will be responsible for reviewing the ECG to assess whether the 
ECG is within normal limits and to determine the clinical significance of the results. These 
assessments will be indicated on the CRF. For any clinically significant abnormal ECG results, 
the Investigator must contact the Medical Monitor to discuss the patient’s continued eligibility to 
participate in this protocol.  
9.5. 
Immunogenicity 
Blood samples will be collected to test for the presence and titer of ADAs to eculizumab in 
serum as indicated in the Schedule of Assessments (Section 4.2). Further characterization of 
antibody responses may be conducted as appropriate, including binding and neutralizing 
antibodies, to PK/PD, safety, and activity of eculizumab.  
Refer to the Laboratory Manual for time windows for sample collection and detailed instructions 
for collecting, processing, storing, and shipping blood samples for immunogenicity analysis. 
9.6. 
Adverse Event Management 
9.6.1. 
Detection of Adverse Events 
The Investigator is responsible for detecting, assessing, documenting, and reporting all AEs. 
Adverse events reported by the patient and/or parent or legal guardian, identified in response to 
an open-ended question from study personnel, or revealed by observation, physical examination, 
or other study procedures must be collected and recorded as described in Section 9.6.3. The same 
parent or guardian is recommended to be available to accompany the patient to each visit, in 
order to reduce subjective variability in assessments. 
9.6.2. 
Definition of Adverse Event 
An AE is any untoward medical occurrence in a patient or clinical study patient administered a 
medicinal product and which does not necessarily have a causal relationship with this treatment. 
An AE can, therefore, be any unfavorable and unintended sign (including an abnormal laboratory 
finding, for example), symptom, or disease temporally associated with the use of a medicinal 
product, whether or not considered related to the medicinal product. 
Exacerbation of a chronic or intermittent pre-existing condition, including either an increase in 
frequency and/or intensity of the condition, and abnormal laboratory findings that are considered 
to be of clinical significance are all to be considered AEs. 
A medication error (including intentional misuse, abuse, and overdose of the product) or use 
other than what is defined in the protocol is not considered an AE unless there is an untoward 
medical occurrence as a result of a medication error. 

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Situations where an untoward medical occurrence did not occur (social and/or elective admission 
to a hospital), and anticipated day-to-day fluctuations of pre-existing disease(s) or condition(s) 
present or detected at the start of the study that do not worsen are not AEs. 
9.6.2.1. 
Procedure 
Elective procedures that were preplanned prior to the time that written ICF was obtained are not 
AEs. Any complication or worsening of a pre-existing condition leading to the procedure must 
be considered an AE. In addition, any AE that could occur as an outcome of the planned 
procedure should be considered as an AE. 
Diagnostic and therapeutic procedures (invasive and noninvasive), such as surgery or 
angiography, should not be reported as an AE or SAE. However, the medical condition or the 
diagnosis that was responsible for the procedure should be recorded. The procedure should be 
recorded in the narrative as treatment for the AE or SAE (eg, laparoscopic cholecystectomy is 
the procedure or treatment for an SAE of necrotic gall bladder). 
9.6.2.2. 
Abnormal Test Findings 
Abnormal test findings may be considered AEs or SAEs; however, Investigators are strongly 
encouraged to report the diagnosis, sign, or symptom instead of just the abnormal result. The 
criteria for an abnormal test finding being classified as an AE or SAE are as follows: 
• Test result is associated with a sign or symptom 
• Test result requires additional diagnostic testing 
• Test result requires a medical or surgical intervention 
• Test result leads to a change in study dosing outside of the protocol defined dosing or 
discontinuation from the study 
• Test result requires significant additional treatment (ie, addition of new medication, 
significant increase in dose of current medication) 
9.6.2.3. 
Lack of Efficacy 
Since eculizumab treatment in pediatric patients with refractory gMG is not an approved 
indication for this population, lack of efficacy should not be reported as an AE. 
9.6.2.4. 
Development of Myasthenia Gravis Clinical Deterioration 
Normal day-to-day fluctuations of the underlying study indication are not considered an AE 
unless it is so in the opinion of the Investigator. Worsening of underlying study indication that 
meets the SAE criteria should be reported as an SAE. 
9.6.3. 
Recording Adverse Events 
Cases of pregnancy that occur during maternal or paternal exposure to the study drug are to be 
reported within 24 hours of Investigator/site awareness. Data on fetal outcome and breastfeeding 
will be collected for regulatory reporting and safety evaluation. 

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All AEs (serious and nonserious) will be collected from the signing of the ICF. An AE reported 
after informed consent but before study drug administration will be considered a pretreatment 
AE. 
Alexion has reporting standards for AEs that are to be followed as described in Section 9.6.8 
regardless of applicable regulatory requirements that may be less stringent.  
9.6.4. 
Severity Assessment 
The severity (intensity) of an AE will be rated by the Investigator as mild, moderate, or severe 
using the following criteria: 
• Mild: events require minimal or no treatment and do not interfere with the patient’s 
daily activities. 
• Moderate: events result in a low level of inconvenience or concerns with the 
therapeutic measures. Moderate events may cause some interference with 
functioning. 
• Severe: events interrupt a patient’s usual daily activity and may require systemic drug 
therapy or other treatment. Severe events are usually incapacitating. 
Change in severity of an AE should be documented based on specific instructions in the eCRF 
Completion Guidelines. 
Severity and seriousness must be differentiated. Severity describes the intensity of an AE, while 
the term seriousness refers to an AE that has met the criteria for an SAE (Section 9.6.6). 
9.6.5. 
Causality Assessment 
An Investigator causality assessment (not related or related) must be provided for all AEs, both 
serious and nonserious based upon the Investigator’s medical judgement and the observed 
symptoms associated with the event (Table 18). This assessment must be recorded in the eCRF 
and any additional forms as appropriate. 
 Table 18: 
Causality Assessment Descriptions 
Assessment 
Description 
Not Related 
This relationship suggests that there is no causal association between the 
study drug and the reported event. 
Related 
This relationship suggests that there is causal association between the 
investigational product and the reported event 
9.6.6. 
Definition of Serious Adverse Event 
Any AE that fulfills any 1 of the criteria listed below must be recorded as an SAE. An SAE 
(experience) or reaction is described as any untoward medical occurrence that at any dose: 
1. Results in death 
2. Is life-threatening 

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NOTE: The term "life-threatening" in the definition of "serious" refers to an event in 
which the patient was at risk of death at the time of the event; it does not refer to an event 
which hypothetically might have caused death if it were more severe. 
3. Requires inpatient hospitalization or prolongation of existing hospitalization 
4. Results in persistent or significant disability/incapacity 
5. Is a congenital anomaly/birth defect 
Important medical events that may not result in death, be immediately life-threatening, or require 
hospitalization, may be considered an SAE when, based upon appropriate medical judgment, 
they may jeopardize the patient or may require intervention to prevent one of the outcomes listed 
above. 
The expectedness of an SAE will be determined by Alexion, based on the current version of the 
eculizumab IB. 
Information pertaining to the collection and reporting of SAEs is provided in Section 9.6.6. 
9.6.7. 
Serious Adverse Event With Outcome of Death 
If a patient experiences an SAE with an outcome of death:  
• The SAE resulting in death should have an outcome documented as death/fatal with 
an end date being the date of death. 
• If the patient had additional AE/SAEs that were ongoing at the time of death, these 
events would be documented as ongoing with no end date. 
• Only one event should have an outcome of death/fatal unless an autopsy report or 
Investigator states otherwise. 
9.6.8. 
Hospitalization 
Adverse events that are associated with hospitalization or prolongation of hospitalization are 
considered SAEs. All admissions to a health care facility meet this criteria, even if less than 
24 hours. Criteria for seriousness are also met if transfer within the hospital is done to receive 
more intense medical / surgical care (eg, medical floor to the intensive care unit [ICU]). 
Hospitalization does not include the following: 
• Rehabilitation facility 
• Hospice facility 
• Nursing facility 
• Emergency Room 
• Same day surgery 
Hospitalization or prolongation of hospitalization not associated with an AE is not an SAE, 
examples include: 
• Admission for a pre-existing condition not associated with either a new AE or with 
worsening of a pre-existing AE 

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• Protocol-specified admission 
• Pre-planned admission 
9.6.9. 
Collection and Reporting of Adverse Events 
9.6.9.1. 
All Adverse Events  
All AEs (serious and nonserious) will be collected from the signing of the ICF until 8 weeks 
after the last dose of study drug for patients who discontinue or until 8 weeks after the last dose 
of study drug for patients who complete the study. All AEs must be recorded on the eCRF upon 
the Investigator or his/her staff becoming aware of their occurrence. 
Investigators will be instructed to report the SAE including their assessment (eg, severity, 
seriousness, and potential relatedness to study drug) to Alexion Global Drug Safety (GDS) 
within 24 hours of first awareness of the event via the Safety Gateway. 
If a patient’s treatment is discontinued as a result of an AE, study site personnel must clearly 
capture the circumstances and data leading to any such dose interruption or discontinuation of 
treatment in the AE and Exposure pages of the eCRF. 
For patients who enter the trial on maintenance IVIg therapy, IVIg administered as part of routine 
maintenance therapy in an inpatient or outpatient setting should not be captured as AEs or SAEs, 
unless identified as such by the Investigator. 
9.6.9.2. 
Serious Adverse Events 
All SAEs must be recorded regardless of the Investigator’s assessment of causality. No time 
limit exists on reporting SAEs that are thought to be causally related to the study drug. 
Investigators are at liberty to report SAEs irrespective of causality at any time.  
For all SAEs, the Investigator must provide the following: 
• Appropriate and requested follow-up information in the time frame detailed above 
• Causality of the serious event(s) 
• Seriousness criteria 
• Treatment of/intervention for the SAE(s) 
• Severity 
• Outcome of the serious event(s) 
• Supporting medical records and laboratory/diagnostic information 
All SAEs must be reported to Alexion GDS within 24 hours of the Investigator or site staff 
awareness. These timelines for reporting SAE information to the Sponsor need to be followed for 
the initial SAE report and for all follow-up SAE information.  
The Investigator or designee must record the SAE data in the eCRF and verify the accuracy of 
the information with corresponding source documents. The SAE report should be submitted 
electronically via the Safety Gateway.  

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In the event that either the electronic data capture or the Safety Gateway is unavailable at the 
site(s), the SAE must be reported utilizing the paper contingency form via Facsimile 
transmission or email. 
Email: 
 
Facsimile: 
 
When further information becomes available, the eCRF should be updated with the new 
information and an updated SAE report should be submitted to Alexion GDS via the Safety 
Gateway.  
If applicable, additional information such as relevant medical records should be submitted to 
Alexion GDS via the email address or fax number noted above accompanied by the Investigator 
signed fax cover page. 
All paper forms and follow-up information submitted to the Sponsor outside of the Safety 
Gateway (eg, discharge summary) should be kept in the appropriate section of the study file.  
9.6.9.3. 
Suspected Unexpected Serious Adverse Reactions 
Suspected unexpected serious adverse reactions (SUSARs) are serious events that are not listed 
in the IB and that the Investigator identifies as related to the study drug or procedure. United 
States 21 CFR 312.32 and European Union Clinical Study Directive 2001/20/EC and the 
associated detailed guidances or national regulatory requirements in participating countries 
require the reporting of SUSARs. Alexion has procedures that will be followed for the recording 
and expedited reporting of SUSARs that are consistent with global regulations and the associated 
detailed guidances. Suspected unexpected serious adverse reactions will be reported to the 
national competent authority and IRBs or IECs where applicable. 
9.6.10. 
Sponsor Reporting Requirements  
Alexion GDS or its legal representative is responsible for notifying the relevant regulatory 
authorities of SAEs meeting the reporting criteria. This protocol will use the current eculizumab 
IB as the Reference Safety Document. The expectedness and reporting criteria of an SAE will be 
determined by the Sponsor from the Reference Safety Document. 
9.6.11. 
Investigator Reporting Requirements  
The Investigator must fulfill all local regulatory obligations required for study Investigators. It is 
the PI’s responsibility to notify the IRB or IEC of all SAEs that occur at his or her site. 
Investigators will also be notified of all SUSAR events that occur during the clinical study. Each 
site is responsible for notifying its IRB or IEC of these additional SAEs. 
9.7. 
Exposure During Pregnancy and Breastfeeding 
Pregnancy data will be collected during this study for all patients and female spouse/partner of 
male patients. Exposure during pregnancy (also referred to as exposure in utero) can be the result 
of either maternal exposure or transmission of drug product via semen following paternal 
exposure. 

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For all Alexion products, both in development or post-approval, exposure during pregnancy must 
be recorded and the pregnancy followed until the outcome of the pregnancy is known (ie, 
spontaneous miscarriage, elective termination, normal birth, or congenital abnormality), even if 
the patient discontinues study drug or withdraws from the study. 
If a female patient or a patient’s female partner becomes pregnant during the conduct of this 
study, the Investigator must submit the “Pregnancy Reporting and Outcome/Breastfeeding” form 
to Alexion GDS via fax or email (Section 9.6.9.2). When the outcome of the pregnancy becomes 
known, the form should be updated and submitted to Alexion GDS. If additional follow-up is 
required, the Investigator will be requested to provide the information. 
Exposure of an infant to an Alexion product during breastfeeding must also be reported (via the 
“Pregnancy Reporting and Outcome Form/Breastfeeding”) and any AEs experienced by the 
infant must be reported to Alexion GDS or designee via email or facsimile (Section 9.6.8). 
Pregnancy in itself is not regarded as an AE unless there is a suspicion that the investigational 
product may have interfered with the effectiveness of a contraceptive medication. However, 
complications of pregnancy and abnormal outcomes of pregnancy are AEs and may meet the 
criteria for an SAE (eg, ectopic pregnancy, spontaneous abortion, intrauterine fetal demise, 
neonatal death, or congenital anomaly). Elective abortions without complications should not be 
reported as AEs. 
9.8. 
Safety Monitoring 
The Alexion medical monitor, GDS physician, or both will monitor safety data throughout the 
course of the study. 
Alexion will review all information pertaining to the SAEs within the time frames mandated by 
company procedures. The Alexion medical monitor will, as appropriate, consult with the GDS 
safety physician, to review trends in safety data.  

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10. 
STATISTICAL CONSIDERATIONS 
10.1. 
General Considerations 
All summary statistics will be computed and displayed by visit where applicable. Descriptive 
statistics for continuous variables will minimally include the following: n, mean, standard 
deviation, minimum, median, and maximum. For categorical variables, frequencies and 
percentages will be presented. Graphical displays will be provided as appropriate. Unless 
otherwise stated, all statistical summaries will be displayed by younger (<12 years) and older (12 
to < 18 years) age groups separately and/or combined. A two-sided Type I error of 5% will be 
used for statistical tests unless otherwise stated. The statistical modeling will be performed for 
the applicable endpoints only for the older age group, as very few patients are anticipated to be 
enrolled in the younger age group. Study data will be summarized by each age group and overall. 
All study data collected on the CRF and from other sources will be listed for individual patients. 
Baseline will be defined as the last non-missing value on or prior to first dose of eculizumab, 
unless otherwise stated. No imputation will be performed for missing efficacy data.  
The statistical analysis plan (SAP) will be developed and finalized prior to the primary analysis 
and will provide further details. The primary analysis will be conducted when all patients have 
completed the 26-week Primary Evaluation Treatment Period or discontinued prior to the 
completion of the Primary Evaluation Treatment Period. This analysis will include all efficacy, 
safety, and PK/PD study data for regulatory submission purpose. Section 10.12 outlines the plan 
for subsequent interim analyses and the final analysis. Another SAP will be developed and 
finalized prior to the completion of the entire study (including the Extension Period). 
Analyses will be performed using the SAS® software Version 9.4 or higher. 
10.2. 
Hypotheses 
The null and alternative hypotheses related to primary endpoint for this study is described as: 
𝐻𝐻0: 𝜇𝜇= 0 𝑣𝑣𝑣𝑣. 𝐻𝐻1: 𝜇𝜇≠0, 
where 𝜇𝜇 represents the mean improvement in QMG from Baseline over time regardless of rescue 
under null and alternate hypotheses. 
10.3. 
Determination of Sample Size 
The sample size will be determined to ensure adequate power for testing the primary endpoint 
for this study in the older age group. The assumptions regarding change from Baseline in QMG 
and MG-ADL scores were based on the subset of a younger patient population treated with 
eculizumab in Studies ECU-MG-301 and ECU-MG-302.  
Based on eleven younger (<25 years) patients from those studies, the mean and SD were 
calculated at both 12 and 26 weeks of eculizumab exposure (Table 19). 

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Table 19: 
Mean [±SD] Change from Baseline in QMG and MG-ADL for Younger 
Patients (Data from Studies ECU-MG-301 and ECU-MG-302)  
 
QMG 
MG-ADL 
Baseline 
20.9 (6.32) 
8.9 (4.46) 
Change at Week 12 
-8.9 (6.86) 
-5.7 (4.27) 
Change at Week 26 
-9.0 (5.58) 
-6.9 (4.93) 
Abbreviations: MG-ADL = Myasthenia Gravis Activities of Daily Living profile; QMG = Quantitative 
Myasthenia Gravis score for disease severity 
Based on a two-sided one-sample t-test with a significance level of 0.05 and assuming an 
improvement in QMG total score at Week 26 with mean (SD) of 9 (7), a total of 10 patients will 
provide approximately 95% power to detect a statistically significant improvement in QMG total 
score from Baseline. Similarly, assuming an improvement in MG-ADL total score at Week 26 
with mean (SD) of 7 (5), a total of 10 patients will provide approximately 97% power. Likewise, 
based on a two-sided one-sample t-test with a significance level of 0.05 and assuming an 
improvement in QMG total score at Week 12 with mean (SD) of 9 (7), a total of 10 patients will 
provide approximately 95% power to detect a statistically significant improvement in QMG total 
score from Baseline. Similarly, assuming an improvement in MG-ADL total score at Week 12 
with mean (SD) of 6 (5), a total of 10 patients will provide approximately 92% power. 
Assuming a loss of 15% of patients due to not meeting evaluability criteria, a total of at least 
12 patients will be planned to be enrolled in the older age group for the primary analysis to enroll 
at least 10 evaluable patients. There will be no statistical considerations to determine the number 
of patients to be enrolled in the younger age group. Section 10.3.1 provides additional 
information about sample size re-estimation.  
In addition, a maximum of 6 patients on maintenance IVIg aged 12 to < 18 years are eligible to 
be enrolled in the study. These patients must have been on maintenance IVIg for at least 
12 months and on a stable dose ≥ 3 months prior to Screening, with frequency and dose expected 
to remain stable during Screening and for 12 weeks following the first dose of study drug. 
Efforts will be made to enroll at least 1 patient in each geographic region (North America, EU, 
and APAC). There is no cap on patients 6 to < 12 years of age. 
10.3.1. 
Interim Monitoring of Variability and Sample Size Re-assessment 
Since the estimates provided in Table 19 are based on a small number of patients and it is 
unknown whether the variability in change in QMG in this study population is consistent with 
patients aged ≥ 18 years, an interim monitoring of the variability in change in QMG from 
Baseline will be performed. After 6 patients complete the Week 26 assessments, if the observed 
standard deviation in QMG change from Baseline is approximately 8 or higher, the final sample 
size will be re-estimated to be at least 14 patients instead of 12 patients to preserve adequate 
power for testing the primary and endpoint. 
10.4. 
Analysis Sets 
10.4.1. 
Full Analysis Set  
Efficacy analyses will be performed on the Full Analysis Set (FAS), which consists of all 
patients who received at least 1 dose of eculizumab. A subset of the FAS that includes older 

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patients (12 to < 18 years of age) only will be used for analyses of the primary and secondary 
endpoints and will be defined as the modified FAS (mFAS). The FAS will be used for other 
efficacy results summaries by including younger patients (< 12 years of age), if any are enrolled. 
10.4.2. 
Safety Set 
Safety analyses will be performed on the Safety Set, which consists of all patients who received 
at least 1 dose of eculizumab. 
10.4.3. 
Other Analysis Set 
Pharmacokinetic/PD analyses will be performed on the PK/PD Analysis Set. The PK/PD 
Analysis Set will include patients who have PK/PD data assessments during this study. 
10.5. 
Demographics and Baseline Characteristics 
Patient demographic and baseline characteristics will be summarized for the Safety Set. 
Summary statistics will be presented. No formal hypothesis testing will be performed. 
10.6. 
Patient Disposition 
The number of patients screened and the number of patients in different analysis sets will be 
summarized. The number and percentage of patients discontinued will be summarized along with 
reasons for discontinuation in the Safety Set.  
10.7. 
Prior and Concomitant Medications 
Prior and concomitant medications will be summarized for all patients in the Safety Set. 
Medications will be coded using the World Health Organization Drug Dictionary (WHODrug; 
the most current version available at the time of the analyses). 
10.8. 
Efficacy Analyses 
10.8.1. 
Primary Efficacy Analysis 
The primary efficacy endpoint is the change from Baseline in the QMG total score over time 
regardless of rescue treatment. The primary efficacy analysis for the change from Baseline in the 
QMG total score will be conducted at Week 12 in order to assess the effect of eculizumab 
treatment during the Primary Evaluation Treatment Period after the 12 weeks during which MG 
medications (ie, ISTs, IVIg) are continued at a stable dose. The Paediatric Committee of the 
European Medicines Agency (PDCO)-specific primary efficacy analysis will be conducted at 
Week 26. The primary efficacy analysis will be performed on the mFAS. A Repeated-Measures 
model will be used to analyze observed change in QMG with baseline QMG score and visits as 
covariates. The least-squares mean at Week 12 will be used to test the primary hypothesis at a 
significance level of 5%. The least-squares mean at Week 26 will be used to test the 
PDCO-specific primary hypothesis at a significance level of 5%. The standard error of the mean 
and 95% confidence interval will be produced. Missing primary endpoints at post-baseline visits 
will not be imputed. 

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10.8.1.1. Analysis of Primary Endpoint based on Evaluable Patients 
The analysis of the primary efficacy endpoint will be performed on the mFAS (evaluable) set.  
10.8.2. 
Analyses of Secondary Efficacy Endpoints 
The secondary efficacy endpoints are:  
• Change from Baseline in the MG-ADL total score over time regardless of rescue 
treatment 
• Proportion of patients with ≥ 3-point reduction in the MG-ADL total score from 
Baseline over time with no rescue treatment 
• Proportion of patients with ≥ 3-point reduction in the MG-ADL total score from 
Baseline over time regardless of rescue treatment 
• Proportion of patients with ≥ 5-point reduction in the QMG total score from Baseline 
over time with no rescue treatment 
• Proportion of patients with ≥ 5-point reduction in the QMG total score from Baseline 
over time regardless of rescue treatment 
• Change from Baseline in the MGC total score over time regardless of rescue 
treatment 
• Change from Baseline in EQ-5D-Y over time regardless of rescue treatment 
• Change from Baseline in Neuro-QoL Pediatric Fatigue over time regardless of rescue 
treatment 
• MGFA Post-Interventional Status over time regardless of rescue treatment 
Total number and percentage of patients with clinical deteriorations, myasthenic crises, and 
rescue therapy use over time 
For all patients in the mFAS, the secondary endpoints that involve change from Baseline will be 
analyzed at a particular visit based on the repeated-measures models with effects for the 
particular baseline covariate and visit. Confidence intervals and p-values will be presented by 
visit. Graphical displays over time will be produced by visit. Missing secondary endpoint 
assessments will not be imputed.  
For all patients in the mFAS, the secondary endpoints that involve proportion of patients with a 
pre-specified response will be summarized at a particular visit. Confidence intervals and p-values 
will be presented by visit.  
The number and percentage of patients with at least one on-study clinical deterioration and/or 
MG crisis during first 26 weeks will be summarized. Use of rescue therapy during the first 
26 weeks will also be summarized. 

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10.8.3. 
Extension Period Efficacy Endpoints 
The efficacy endpoints related to the Extension Period are: 
• Total number and percentage of patients with clinical deteriorations and/or 
myasthenic crisis during the study 
• Total number and percentage of patients needing rescue therapy during the study 
• Change from Baseline in the QMG total score regardless of rescue treatment 
• Change from Baseline in the MG-ADL total score regardless of rescue treatment 
• Change from Baseline in the MGC total score regardless of rescue treatment 
• Change from Baseline in EQ-5D-Y regardless of rescue treatment 
• Change from Baseline in Neuro-QoL Pediatric Fatigue regardless of rescue treatment 
• Change from Baseline in MGFA Post-Interventional Status 
These endpoints will be analyzed similarly as described for the secondary endpoints, but based 
on the FAS population for the entire duration of the study. 
10.9. 
Safety Analyses 
The safety endpoints of the study are: 
• Frequency of AEs and SAEs  
• Frequency of adverse events leading to discontinuation 
• Incidence of antidrug antibodies (ADA)  
• Physical examination assessments 
• Changes from Baseline in vital signs 
• Change from Baseline in electrocardiogram parameters 
• Change from Baseline in laboratory assessments 
Safety analyses will be performed on the Safety Set.  
10.9.1. 
Physical Examinations 
The number and percentage of patients with abnormal physical examinations will be summarized 
by visit.  
10.9.2. 
Vital Signs 
Absolute values and change from Baseline in vital signs (including weight and height) will be 
summarized by visit.  

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10.9.3. 
Adverse Events 
Treatment-emergent AEs (serious and nonserious) will be defined as all AEs starting on or after 
the day of first dose of study drug. Pre-treatment SAEs are any SAEs staring prior to the day of 
first dose of study drug. 
All AEs will be coded using the MedDRA version that is current at the time of the analysis. 
Adverse events will be summarized for the first 26 weeks and separately for the entire study by 
System Organ Class (SOC) and Preferred Term (PT) and, in some cases, by PT only. 
10.9.4. 
Clinical Laboratory Tests 
Absolute values and change from Baseline over time in clinical chemistry and hematology 
results will be summarized descriptively. Laboratory data abnormalities (low, normal, high) with 
respect to the reference range will be summarized using shift analysis compared to the 
abnormality at Baseline. Listings of patients with abnormal laboratory values will be provided. 
10.9.5. 
Immunogenicity  
The number and percentage of patients with positive ADA will be summarized by visit, any time 
during the first 26 weeks and any time during the study. The proportion of patients ever positive 
and the proportion of patients always negative may be summarized. 
10.10. 
Pharmacokinetic/Pharmacodynamic Analyses 
Pharmacokinetic and PD laboratory measurements will be summarized for both Induction and 
Maintenance Treatment Period. Pharmacokinetic and PD data will be explored using modeling 
and simulation methods for evaluating the appropriateness of the studied pediatric dose. A 
separate analysis plan will be written for the PK/PD analyses. 
The PK/PD endpoints of the study include: 
• Pharmacokinetic/PD parameters including maximum plasma drug concentration 
(Cmax), terminal half-life (t½), trough (Ctrough), clearance, free C5, and in vitro 
hemolytic assay; assessed at Baseline and various time points including 24 hours 
(Day 2), Week 12, and Week 26 during the treatment. 
10.11. 
Other Statistical Issues 
10.11.1. 
Missing or Invalid Data 
Missing data will not be imputed unless otherwise noted. 
10.12. 
Interim Analyses 
The primary analysis (ie interim analysis) of the study for regulatory submission will be 
performed after all patients complete the 26-week Primary Evaluation Treatment Period.  

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10.13. 
Sample Size Re-Estimation 
After 6 patients complete their Week 26 assessments, if the observed standard deviation in 
change in QMG is 8 or higher, the final sample size will be re-estimated to be at least 14 instead 
of 12 to preserve adequate power for testing the primary endpoint.  

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11. 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
11.1. 
Study Monitoring 
Before an investigational site can enter a patient into the study, a representative of the Sponsor or 
its designee will visit the investigational study site to: 
• Determine the adequacy of the facilities 
• Discuss with the Investigator(s) and other personnel their responsibilities with regard 
to protocol adherence, and the responsibilities of the Sponsor or the Sponsor’s 
designee or its representatives. This will be documented in a Clinical Study 
Agreement between Alexion Pharmaceuticals, Inc. or its designee and the 
Investigator. 
During the study, a monitor from the Sponsor or its designee or representative will have regular 
contacts with the investigational site, to: 
• Provide information and support to the Investigator(s) 
• Confirm that facilities remain acceptable 
• Confirm that the investigational team is adhering to the protocol, that data are being 
accurately recorded in the eCRFs, and that study drug accountability checks are being 
performed 
• Perform source data verification. This includes a comparison of the data in the eCRFs 
with the patient’s medical records at the hospital or practice, and other records 
relevant to the study. This will require direct access to all original records for each 
patient (eg, clinic charts). 
• Record and report any protocol deviations not previously sent to the Sponsor or its 
designee. 
• Confirm AEs and SAEs have been properly documented on eCRFs and confirm any 
SAEs have been forwarded to the Sponsor or its designee and those SAEs that met 
criteria for reporting have been forwarded to the IRB/IEC. 
The monitor will be available between visits if the Investigator(s) or other staff needs 
information or advice. 
11.2. 
Audits and Inspections 
Authorized representatives of the Sponsor or the Sponsor’s designee, a regulatory authority, and 
an IEC or an IRB may visit the sites to perform audits or inspections, including source data 
verification. The purpose of an audit or inspection is to systematically and independently 
examine all study-related activities and documents to determine whether these activities were 
conducted, and data were recorded, analyzed, and accurately reported according to the protocol, 
GCP guidelines of the ICH, and any applicable regulatory requirements. The Investigator should 
contact the Sponsor or the Sponsor’s designee immediately if contacted by a regulatory agency 
about an inspection. 

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11.3. 
Institutional Review Board / Independent Ethics Committee  
The PI must obtain IRB or IEC approval for the investigation. Initial IRB or IEC protocol 
approval, and all materials that have been submitted and approved by the IRB or IEC for this 
study including the patient ICF and recruitment materials must be maintained by the PI and made 
available for inspection. 
11.4. 
Quality Control and Quality Assurance 
To ensure compliance with GCP and all applicable regulatory requirements, the Sponsor or its 
designee may conduct quality assurance audits as described in Section 11.2. 
11.5. 
Ethics 
11.5.1. 
Ethics Review 
The final study protocol, including the final version of the ICF, must be approved or given a 
favorable opinion in writing by an IRB or IEC as appropriate. The Investigator must submit a 
copy of the written approval to the Sponsor or its designee before enrolling any patients into the 
study. 
The PI is responsible for informing the IRB or IEC of any amendment to the protocol in 
accordance with local requirements. In addition, the IRB or IEC must approve all advertising 
used to recruit patients for the study. The protocol must be reapproved by the IRB or IEC upon 
receipt of amendments and reviewed annually, as local regulations require. 
The PI is also responsible for providing the IRB with reports of any reportable serious adverse 
drug reactions from any other study conducted with the study drug, as required. Alexion 
Pharmaceuticals, Inc. or designee will provide this information to the PI. 
Progress reports and notifications of serious adverse drug reactions will be provided to the IRB 
or IEC according to local regulations and guidelines. 
11.5.2. 
Ethical Conduct of the Study 
The study will be performed in accordance with ethical principles that have their origin in the 
Declaration of Helsinki and are consistent with ICH/GCP and applicable regulatory 
requirements. 
11.6. 
Informed Consent and Assent 
The PI(s) at each center will ensure that each patient and/or parental guardian are given full and 
adequate verbal and written information about the nature, purpose, possible risk, and benefit of 
the study. Patients and/or parental guardian must also be notified that they are free to refuse to 
join the study and may discontinue from the study at any time. The patient and/or parental 
guardian should be given the opportunity to ask questions and allowed adequate time to consider 
the information provided. 
The Investigator is responsible for ensuring that informed consent is given by each patient or the 
patient’s legal representative. This includes obtaining the appropriate signatures and dates on the 

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ICF prior to the performance of any protocol procedures and prior to the administration of study 
drug.  
The PI(s) must maintain the original, signed ICF. If the ICF is amended, the original signed, 
amended version must also be retained. A copy of the signed ICF must be given to the patient 
and/or parental guardian.  
The same parent or guardian is recommended to be available to accompany the child to each 
study visit, in order to reduce subjective variability in assessments. 
As used in this protocol, the term “informed consent” includes all informed assent given by 
patients, informed permission by parent or legal guardian, or, as applicable, informed consent by 
the patient during study participation.  
11.7. 
Data Protection 
The following measures will be implemented for the protection of patients’ personal data: 
• Each patient will be assigned a unique identifier. Any patient records or datasets that 
are transferred to Alexion will contain the identifier only; patient names or any 
information that would make a patient identifiable will not be transferred. 
• The patient and/or parental guardian must be informed that the patient’s personal 
study-related data will be used by Alexion in accordance with local data protection 
law. The level of disclosure must also be explained to the patient and/or parental 
guardian, as well as a notice of the collection, use, and storage of the personal data 
through the informed consent or other privacy notice in accordance with local data 
protection law. 
• The patient and/or parental guardian must be informed that the patient’s medical 
records may be examined by Clinical Quality Assurance auditors or other authorized 
personnel appointed by Alexion, by appropriate IRB/IEC members, and by inspectors 
from regulatory authorities. 
11.8. 
Changes or Deviations to Protocol 
The Investigator may need to deviate from the protocol to eliminate an immediate hazard to a 
study subject without prior notification of the IRB/IEC. Any deviations from the protocol must 
be fully documented. The deviation and the reasons for it should be submitted to the IRB/IEC, 
Sponsor, and appropriate regulatory authority if required (ICH GCP E6 [R1] 4.5.4). After the 
commencement of the clinical study, the Sponsor may make changes to the protocol. If those 
changes are significant, the regulatory authority and applicable IRB/IEC will be notified. 
11.9. 
Data Handling and Recordkeeping 
11.9.1. 
Inspection of Records 
The Sponsor or the Sponsor’s designee will be allowed to conduct site visits to the 
investigational facilities for the purpose of monitoring any aspect of the study. The Investigator 
agrees to allow the monitor to inspect the drug storage area, investigational product stocks, study 

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drug accountability records, patient charts and study source documents, and other records 
relative to study conduct. 
11.9.2. 
Retention of Records 
The PI must maintain all documentation relating to the study according to local regulations or a 
minimum period of 2 years after the last marketing application approval worldwide or, if not 
approved, 2 years following the discontinuance of the test article for investigation. If it becomes 
necessary for the Sponsor or its designee or the regulatory authority to review any documentation 
relating to the study, the Investigator must permit access to such records.  
The PI must maintain the confidentiality of all study documentation and take measures to prevent 
accidental or premature destruction of these documents. 
11.10. 
Contraceptive Guidance  
Female patients of childbearing potential and male patients with female partners of childbearing 
potential, pregnant, or breastfeeding, must use effective methods of contraception (as defined 
below), starting at Screening and continuing for at least 5 months after the last dose of study 
drug.  
Highly effective contraceptive methods include: 
1. Hormonal contraception associated with inhibition of ovulation 
2. Intrauterine device 
3. Intrauterine hormone-releasing system 
4. Bilateral tubal occlusion  
5. Vasectomized partner, provided the partner is the patient’s sole sexual partner 
6. Sexual abstinence, defined as refraining from heterosexual intercourse during the entire 
period of risk associated with the study drug treatment; reliability of sexual abstinence 
needs to be evaluated in relation to the duration of the clinical study and the preferred and 
usual lifestyle of the patient. 
Acceptable contraceptive methods include:  
7. A combination of male condom with either a cap, diaphragm, or sponge with spermicide 
(double barrier methods) 
The above-listed method(s) of contraception chosen for an individual patient can be determined 
by the Investigator with consideration for the patient’s medical history and concomitant 
medications.  
11.11. 
Publication Policy  
The full terms regarding publication of the results of this study are outlined in the applicable 
Clinical Study Agreement. 

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12. 
LIST OF REFERENCES 
Andrews PI. Autoimmune myasthenia gravis in childhood. Semin Neurol. 2004;24(1):101-110. 
Barnett C, Bril V, Kapral M, Kulkarni A, David AM. A conceptual framework for evaluating 
impairments in myasthenia gravis. PLoS One. 2014;9(5):e98089. 
Burns TM, Conaway M, Sanders DB; MG Composite and MG-QoL15 Study Group. The MG 
composite: a valid and reliable outcome measure for myasthenia gravis. Neurology. 
2010;74(18):1434-1440. 
Cella D. Measuring quality of life in neurological disorders: final report of the Neuro-QOL 
study. 2010. 
Conti-Fine BM, Milani M, Kaminski HJ. Myasthenia gravis: past, present, and future. J Clin 
Invest. 2006;116(11):2843-2854. 
Della Marina A, Trippe H, Lutz S, Schara U. Juvenile myasthenia gravis: recommendations for 
diagnostic approaches and treatment. Neuropediatrics. 2014;45(2):75-83. 
Fitzpatrick AM, Mann CA, Barry S, Brennan K, Overell JR, Willison HJ. An open label clinical 
trial of complement inhibition in multifocal motor neuropathy. J Peripher Nerv Syst. 
2011;16(2):84-91. 
Goldstein SD, Culbertson NT, Garrett D, et al. Thymectomy for myasthenia gravis in children: a 
comparison of open and thoracoscopic approaches. J Pediatr Surg. 2015;50(1):92-97. 
Jin F, Balthasar JP. Mechanisms of intravenous immunoglobulin action in immune 
thrombocytopenic purpura. Hum Immunol. 2005;66(4):403-410. 
Kim JY, Park KD, Richman DP. Treatment of myasthenia gravis based on its 
immunopathogenesis. J Clin Neurol. 2011;7(4):173-83. 
McGrogan A, Sneddon S, de Vries CS. The incidence of myasthenia gravis: a systematic 
literature review. Neuroepidemiology. 2010;34(3):171-183. 
Phillips LH 2nd, Torner JC, Anderson MS, Cox GM. The epidemiology of myasthenia gravis in 
central and western Virginia. Neurology. 1992;42(10):1888-1893. 
Sieb, JP. Myasthenia gravis: an update for the clinical. Clin Exp Immunol. 2014;175(3):408-418. 
Snead OC 3rd, Benton JW, Dwyer D, et al. Juvenile myasthenia gravis. Neurology. 1980;30(7 Pt 
1):732-739. 
Szende A, Janssen B, Cabasés, J. Self-reported population health: an international perspective 
based on EQ-5D. 2014. 
Szorbor A, Máttyus A, Molnár J. Myasthenia gravis in childhood and adolescence: report on 209 
patients and review of the literature. Acta Paediatr Hung. 1988-1989;29(3-4):299-312. 
Vincent A, Drachman DB. Myasthenia gravis. Adv Neurol. 2002;88:159-188. 
Wang W, Wang EQ, Balthasar JP. Monoclonal antibody pharmacokinetics and 
pharmacodynamics. Clin Pharmacol Ther. 2008;84(5):548-558. 

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APPENDIX 1. QUANTITATIVE MYASTHENIA GRAVIS SCORE FOR 
DISEASE SEVERITY 
 
 

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APPENDIX 2. MODIFIED QUANTITATIVE MYASTHENIA GRAVIS 
SCORE FOR DISEASE SEVERITY 
Test Item 
None 
Mild 
Moderate 
Severe 
Grade 
0 
1 
2 
3 
Subjective double vision 
None 
Occasional 
Frequent 
Constant 
Ptosis (upward gaze), seconds 
61 
11-60 
1-10 
Spontaneous 
Facial muscles 
Normal lid 
closure 
Complete, weak, 
some resistance 
Complete, 
without resistance 
Incomplete 
Swallowing 4 oz water (slurp 
test) 
<10 seconds 
10-15 seconds 
>15 seconds 
Cannot swallow 
(test not 
attempted) 
Speech (nasal phonation) 
None 
Occasional 
Frequent 
Constant 
Right arm outstretched 
(90 degree sitting), seconds 
240 
90-239 
10-89 
0-9 
Left arm outstretched 
(90 degree sitting), seconds 
240 
90-239 
10-89 
0-9 
Source: Goldstein, 2015 

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APPENDIX 3. MYASTHENIA GRAVIS ACTIVITIES OF DAILY LIVING 
(MG-ADL) PROFILE 
Items 
Grade 0 
Grade 1 
Grade 2 
Grade 3 
Score 
(0,1,2,3) 
1. Talking  
Normal 
Intermittent 
slurring or nasal 
speech 
Constant slurring or 
nasal, but can be 
understood 
 
Difficult to 
understand speech 
 
2. Chewing 
Normal 
Fatigue with solid 
food 
Fatigue with soft 
food 
 
Gastric tube 
 
3. Swallowing  
Normal 
Rare episode of 
choking  
Frequent choking 
necessitating 
changes in diet 
 
Gastric tube 
 
4. Breathing 
Normal 
Shortness of 
breath with 
exertion 
 
Shortness of breath 
at rest 
Ventilator 
dependence 
 
5. Impairment 
of ability to 
brush teeth or 
comb hair 
None 
Extra effort, but no 
rest periods 
needed 
 
Rest periods needed  
Cannot do one of 
these functions 
 
6. Impairment 
of ability to 
arise from a 
chair 
None 
Mild, sometimes 
uses arms  
Moderate, always 
uses arms  
Severe, requires 
assistance 
 
7. Double 
vision 
None 
Occurs, but not 
daily 
 
Daily, but not 
constant 
Constant 
 
8. Eyelid 
droop 
None 
Occurs, but not 
daily 
Daily, but not 
constant 
Constant 
 
 

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APPENDIX 4. MYASTHENIA GRAVIS COMPOSITE SCALE 
 
Permission granted for use from Ted Burns, MD, University of Virginia. 
 

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APPENDIX 5. EUROPEAN QUALITY OF LIFE 5-DIMENSION – 
YOUTH VERSION  
Sample Health Questionnaire (English version for the UK) to be used for patients 8-18 years of 
age  
 

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APPENDIX 6. EUROPEAN QUALITY OF LIFE 5-DIMENSION – 
YOUTH VERSION (PROXY) 
To be used for patients < 8 years of age. 
 

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APPENDIX 7. NEUROLOGICAL QUALITY OF LIFE PEDIATRIC 
FATIGUE 
To be used for patients ≥ 8-17 years of age. 
 
 

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APPENDIX 8. PROMIS PARENT PROXY ITEM BANK V2.0 – FATIGUE 
– SHORT FORM 10A 
To be used in patients < 8 years of age. 
 

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APPENDIX 9. MYASTHENIA GRAVIS FOUNDATION OF AMERICA 
CLINICAL CLASSIFICATION 
 

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APPENDIX 10. MYASTHENIA GRAVIS FOUNDATION OF AMERICA 
THERAPY STATUS 
 
 

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APPENDIX 11. MYASTHENIA GRAVIS FOUNDATION OF AMERICA 
POST-INTERVENTIONAL STATUS 
 

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APPENDIX 12. SUMMARY OF LABORATORY PANELS AND TESTS 
Chemistry Panel  
Sodium 
Potassium 
Chloride 
Bicarbonate 
Blood urea nitrogen 
Creatinine 
Glucose 
Alkaline phosphatase 
Alanine amino transferase  
Aspartate amino transferase  
Total bilirubin 
Albumin 
Total protein 
Uric acid 
Complete Blood Count and Differential 
White blood cell count  
White blood cell differential 
Red blood cell count (RBC) 
RBC mean corpuscular volume 
RBC distribution width 
Hemoglobin 
Hematocrit 
Platelet count 
 
Other  
Human chorionic gonadotropin (urine pregnancy test) 
Anti-acetylcholine receptor (AChR) antibody 
Pharmacokinetics  
Pharmacodynamics  
Free complement component 5 
Anti-drug antibody  

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APPENDIX 13. COLLECTION OF FOLLOW-UP INFORMATION FROM 
PATIENTS WHO WITHDRAW FROM THE STUDY 
To gain understanding of the patient’s post-treatment disease status, the Sponsor may request 
additional Post-Treatment Follow-up information from patients who discontinue prematurely for 
up to 1 year following discontinuation. An ICF (and/or an ICF Addendum) will be provided to 
all patients and/or the parent or other legal guardian (as applicable) describing the reason for 
collecting follow-up information, the information that will be collected, and how the information 
will be used. The ICF (and/or ICF Addendum) will clearly state that the patient and/or the parent 
or legal guardian has the option to accept or reject, and that either decision will have no impact 
on their medical benefits. Prior to collecting any follow-up information, the ICF (and/or ICF 
Addendum) must be signed. 
The Sponsor may obtain patient post-treatment data by querying the patient’s medical records, 
through the study physician or the patient’s current treating physician. The follow-up data to be 
collected from the physician may include the following:  
• How has the patient’s MG status changed since they left Study ECU-MG-303 
(better/worse/unchanged); if better or worse, what are the changes? 
• What are the patient’s current MG medications and the doses, and MG medication 
history since leaving Study ECU-MG-303? 
• Has the patient experienced any exacerbations (clinical deteriorations) of MG, or any 
myasthenic crises since leaving Study ECU-MG-303; if so how many times? 
• Has the patient experienced any MG-related hospitalizations since leaving 
Study ECU-MG-303; if so how many times 
• Has the patient required rescue treatment with IV acetylcholinesterase inhibitors, 
corticosteroids, plasma exchange or IVIg since leaving Study ECU-MG-303; if so 
how many times 
• Has the patient had any assessments using the MG-ADL, QMG, MGC, Neuro-QoL 
Fatigue or EQ-5D-Y scale; if so, what are the results, and was it administered by the 
same person who did the assessment during the clinical study 
• Have there been any changes in non-drug therapy. 
This information will not be entered into the trial Electronic Data Capture systems and will not 
be part of any safety or efficacy analysis that will be included in the ECU-MG-303 clinical study 
report.