A Phase 2, Randomized, Double-Blind, Placebo-Controlled Multicenter Study to Evaluate the Efficacy and Safety of ALXN2050 in Adult Participants With Generalized Myasthenia Gravis
Phase: PHASE2
Conditions: Generalized Myasthenia Gravis, Myasthenia Gravis
Sponsor: Alexion Pharmaceuticals, Inc.

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TITLE PAGE 
Protocol Title: A Phase 2, Randomized, Double-Blind, Placebo-Controlled Multicenter Study to 
Evaluate the Efficacy and Safety of ALXN2050 in Adult Participants with Generalized 
Myasthenia Gravis 
Alexion Protocol Number: ALXN2050-MG-201 
AstraZeneca Protocol Number: D7840C00001 
Compound: ALXN2050 
Study Phase: 2 
Brief Title: Phase 2 Study of ALXN2050 in Generalized Myasthenia Gravis 
Sponsor Name: Alexion Pharmaceuticals, Inc. 
Legal Registered Address: 
Alexion Pharmaceuticals 
121 Seaport Boulevard 
Boston, MA 02210 
USA 
Regulatory Agency Identifier Number(s) 
IND:154567 
EudraCT: 2021-001229-26 
EU CT: 2022-502905-14 
Release Date: 15 Nov 2023 
Sponsor Signatory: 
 
 
Alexion Pharmaceuticals, Inc. 
Date 
The document has been e-signed in Veeva. Please refer to last page for signature details. 
Medical Monitor Name and Contact Information can be found in the study contact list. 
NCT #: NCT05218096

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INVESTIGATOR’S AGREEMENT 
I have read the study protocol amendment and agree to conduct the study in accordance with this 
protocol amendment, all applicable government regulations, the principles of the International 
Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use 
(ICH) E6 Guideline for Good Clinical Practice, 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 amendment. 
 
 
 
 
 
____________________________________ 
Printed Name of Investigator 
 
_____________________________________ 
Signature of Investigator 
 
 
_______________ 
Date 
 

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PROTOCOL AMENDMENT SUMMARY OF CHANGES TABLE 
DOCUMENT HISTORY 
Document 
Date 
Amendment 2.0 
09 Mar 2023 
Amendment 1.0 
22 Jul 2021 
Original Protocol 
28 Apr 2021 
Amendment 3 (Global 15 Nov 2023) 
This amendment is considered to be nonsubstantial based on the criteria set forth in Article 10(a) 
of Directive 2001/20/EC of the European Parliament and the Council of the European Union 
(EU) and in the EU Clinical Trials Regulation (CTR) 536/2014 Article 2, 2 (13). 
OVERALL RATIONALE FOR THE AMENDMENT 
The primary reason for this amendment is to address the requirements for transitioning a clinical 
study under the EU CTR. Further modifications include nonsubstantial changes, minor 
corrections, and harmonized terminology. 
Section # and Name 
Description of Change 
Brief Rationale 
TITLE PAGE and Section 1.1 
Synopsis 
Updated regulatory agency identifier 
name. 
Changed Short Title to Brief Title. 
To provide information 
required under EU CTR 
Section 4.4 End of Study 
Definition 
The EOS is defined as the date of the 
last visit of the last participant for any 
protocol-related activity in the study. 
To align with EU CTR 
requirements. 
Section 6.1 Study 
Intervention(s) Administered 
Section 8.3.5.2 Medication 
Error 
Section 8.3.5.3 Drug Abuse 
Section 8.3.5.4 Drug Misuse 
Section 8.4 Treatment of 
Overdose 
Section 10.4 Medication 
Error, Drug Abuse, and Drug 
Misuse 
Added AxMP = auxiliary medicinal 
product and removed NIMP. 
To align with EU CTR 
requirements. 
Section 8.3.4 Regulatory 
Reporting Requirements for 
SAEs 
Section 10.3.5 Unexpected 
Events 
Described reporting requirements and 
updated definition of unexpected events, 
respectively. 
To align with EU CTR 
requirements. 

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Section # and Name 
Description of Change 
Brief Rationale 
Section 8.3.5.1 Timelines 
Simplified text to reflect that Alexion or 
designee will be informed of an event of 
medication error, drug abuse, or misuse 
immediately. 
To align with EU CTR 
requirements. 
Section 8.4 Treatment of 
Overdose 
Added details on process to capture and 
report an event of overdose. 
To align with EU CTR 
requirements. 
Section 10.4 Medication 
Error, Drug Abuse, and Drug 
Misuse 
Described reporting requirements for 
medication error, drug abuse, and drug 
misuse. 
To align with EU CTR 
requirements. 
Section 10.1.1 Regulatory and 
Ethical Considerations 
Added details on serious breach (including 
personal data breach) prevention, 
identification, notification, and impact 
mitigation 
To align with EU CTR 
requirements. 
Section 10.1.5 Data 
Protection 
Updated text to reflect that unique 
identifier was assigned by a third party 
contracted by Alexion. 
Described data protection measures to 
ensure patient identity remains secure 
To align with EU CTR 
requirements. 
Section 10.1.7 Quality Data 
Assurance 
Specified document retention period at 
investigative site to be at least 25 years 
after study completion. 
To align with EU CTR 
requirements. 
Abbreviations: AxMP = auxiliary medicinal product; CTR = Clinical Trials Regulation; EU = European Union; 
NIMP = non-investigational medicinal product 
 
 

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TABLE OF CONTENTS 
TITLE PAGE 
1 
INVESTIGATOR’S AGREEMENT 2 
PROTOCOL AMENDMENT SUMMARY OF CHANGES TABLE 
3 
OVERALL RATIONALE FOR THE AMENDMENT 3 
TABLE OF CONTENTS 5 
LIST OF TABLES 
11 
LIST OF FIGURES 
11 
List of Abbreviations 
12 
1. 
PROTOCOL SUMMARY 16 
1.1. Synopsis 
16 
1.2. Schema 21 
1.3. Schedule of Activities (SoA) 
22 
2. 
INTRODUCTION 35 
2.1. Study Rationale 35 
2.2. Background 
35 
2.2.1. 
Myasthenia Gravis 
35 
2.2.2. 
ALXN2050 
36 
2.2.3. 
Rationale for Evaluating ALXN2050 in Participants with Generalized Myasthenia Gravis
 
37 
2.3. Benefit/Risk Assessment 
38 
2.3.1. 
Risk Assessment 
38 
2.3.1.1. Coronavirus Disease 2019 
39 
2.3.2. 
Benefit Assessment 
39 
2.3.3. 
Overall Benefit: Risk Conclusion 39 
3. 
OBJECTIVES AND ENDPOINTS 
40 
4. 
STUDY DESIGN 43 
4.1. Overall Design 43 
4.2. Scientific Rationale for Study Design 
45 
4.3. Justification for Dose 
47 
4.4. End of Study Definition 47 
5. 
STUDY POPULATION 
49 

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5.1. Inclusion Criteria 
49 
5.2. Exclusion Criteria 
50 
5.3. Lifestyle Considerations 53 
5.3.1. 
Medications 
53 
5.3.2. 
Meals and Dietary Restrictions 53 
5.4. Screen Failures 53 
6. 
STUDY INTERVENTION 54 
6.1. Study Intervention(s) Administered 
54 
6.1.1. 
Study Intervention(s) Packaging and Labeling 
55 
6.1.2. 
Optional Dosing eDiary Tool 
55 
6.2. Preparation/Handling/Storage/Accountability 
55 
6.2.1. 
Preparation 
55 
6.2.2. 
Storage and Handling 
55 
6.2.3. 
Accountability and Disposal 
56 
6.3. Measures to Minimize Bias: Randomization and Blinding 57 
6.3.1. 
Randomization 57 
6.3.2. 
Blinding 
57 
6.4. Study Intervention Compliance 57 
6.5. Prior and Concomitant Therapies 
58 
6.5.1. 
Allowed Medications and Therapy 
58 
6.5.2. 
Disallowed Medications and Therapy 
59 
6.5.3. 
Rescue Medicine 
60 
6.5.4. 
Vaccine and Antibiotic Prophylaxis 
60 
6.6. Dose Modification 
60 
6.7. Intervention After the End of the Study 60 
7. 
DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL 
61 
7.1. Discontinuation of Study Intervention 
61 
7.2. Participant Discontinuation/Withdrawal from the Study 61 
7.3. Lost to Follow-up 
62 
8. 
STUDY ASSESSMENTS AND PROCEDURES 
63 
8.1. Efficacy Assessments 
63 
8.1.1. 
MG-ADL 
63 

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8.1.2. 
QMG 
63 
8.1.3. 
MGFA-PIS 
64 
8.1.4. 
Neuro-QoL™ Fatigue 
64 
8.2. Safety Assessments 
64 
8.2.1. 
Physical Examinations 64 
8.2.2. 
Vital Signs 
65 
8.2.3. 
Electrocardiograms 
65 
8.2.4. 
Clinical Safety Laboratory Assessments 65 
8.2.4.1. Virus Serology 66 
8.2.4.2. Urinalysis 
66 
8.2.4.3. Follicle-Stimulating Hormone 
66 
8.2.5. 
Clinical Deterioration of Myasthenia Gravis 
66 
8.2.6. 
Suicidal Ideation and Behavior Risk Monitoring 67 
8.2.7. 
Pregnancy 
67 
8.2.8. 
Participant Safety Card 68 
8.3. Adverse Events and Serious Adverse Events 
68 
8.3.1. 
Time Period and Frequency for Collecting AE and SAE Information 
68 
8.3.2. 
Method of Detecting AEs and SAEs 
68 
8.3.3. 
Follow-up of AEs and SAEs 
69 
8.3.4. 
Regulatory Reporting Requirements for SAEs 
69 
8.3.5. 
Medication Error, Drug Abuse, and Drug Misuse 69 
8.3.5.1. Timelines 
69 
8.3.5.2. Medication Error 
70 
8.3.5.3. Drug Abuse 
70 
8.3.5.4. Drug Misuse 
70 
8.4. Treatment of Overdose 70 
8.5. Pharmacokinetics 
71 
8.6. Pharmacodynamics 
71 
8.7. Genetics 
71 
8.8. Biomarkers 
71 
8.9. Immunogenicity Assessments 
72 
8.10. Health Economics Data and/or Medical Resource Utilization 
72 
8.11. Other Assessments and Procedures 
72 

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8.11.1. 
Informed Consent 
72 
8.11.2. 
Demographics 72 
8.11.3. 
Inclusion and Exclusion Criteria 72 
8.11.4. 
Medical History and MG History 72 
8.11.5. 
MGFA Classification 
72 
8.11.6. 
Vaccination or Antibiotic Prophylaxis 
73 
8.11.7. 
Rerandomization 
73 
9. 
STATISTICAL CONSIDERATIONS 74 
9.1. Statistical Hypotheses 74 
9.1.1. 
Primary Hypothesis 
74 
9.1.2. 
Secondary Hypotheses 74 
9.2. Sample Size Determination 
75 
9.3. Populations for Analyses 
75 
9.4. Statistical Analyses 
76 
9.4.1. 
Enrollment and Disposition 
76 
9.4.2. 
Demographics, Baseline Characteristics, Inclusion and Exclusion Criteria, and Protocol 
Deviations 76 
9.4.3. 
Medical/Surgical History, Physical Examination, and Myasthenia Gravis History 76 
9.4.4. 
Prior and Concomitant Medications 
76 
9.4.5. 
Extent of Drug Exposure 
76 
9.4.6. 
Efficacy Analyses 
76 
9.4.6.1. Analyses of Primary Efficacy Endpoint 
77 
9.4.6.2. Analyses of Secondary Efficacy Endpoints 
77 
9.4.6.3. Multiplicity Adjustment 78 
9.4.6.4. Analyses of Exploratory Endpoints 
78 
9.4.7. 
Safety Analyses 80 
9.4.7.1. Analysis of Adverse Events 
80 
9.4.7.2. Analysis of Clinical Laboratory Parameters, Vital Sign Measurements, and 
Electrocardiogram Parameters 80 
9.4.7.3. Other Safety Analyses 80 
9.4.8. 
Analyses of Pharmacokinetics and Pharmacodynamics 80 
9.5. Interim Analysis 80 
9.5.1. 
Other Analyses 81 
9.6. Data Monitoring Committee 
81 

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10. 
SUPPORTING DOCUMENTATION AND OPERATIONAL CONSIDERATIONS 82 
10.1. Regulatory, Ethical, and Study Oversight Considerations 82 
10.1.1. 
Regulatory and Ethical Considerations 82 
10.1.2. 
Financial Disclosure 
83 
10.1.3. 
Informed Consent Process 
83 
10.1.4. 
Recruitment Strategy 
84 
10.1.5. 
Data Protection 84 
10.1.6. 
Dissemination of Clinical Study Data 
86 
10.1.7. 
Data Quality Assurance 86 
10.1.8. 
Source Documents 
86 
10.1.9. 
Study and Site Start and Closure 87 
10.1.10. 
Publication Policy 
88 
10.1.11. 
Good Clinical Practice Compliance 
89 
10.2. Clinical Laboratory Tests 
90 
10.3. Adverse Events: Definitions and Procedures for Recording, Evaluating, Follow-up, and Reporting
 
92 
10.3.1. 
Definition of AE 92 
10.3.2. 
Definition of SAE 
93 
10.3.3. 
Recording and Follow-Up of AE and/or SAE 
94 
10.3.4. 
Reporting of SAEs 
96 
10.3.5. 
Unexpected Events 
96 
10.4. Medication Error, Drug Abuse, and Drug Misuse 98 
10.5. Contraceptive Guidance and Collection of Pregnancy Information 
100 
10.5.1. 
Definitions 
100 
10.5.2. 
Contraception Guidance 
100 
10.5.2.1.Guidance for Female Participants 
101 
10.5.2.2.Guidance for Male Participants 102 
10.5.3. 
Collection of Pregnancy Information 
102 
10.5.3.1.Male Participants with Partners Who Become Pregnant 103 
10.5.3.2.Female Participants Who Become Pregnant 
103 
10.6. Biomarkers 
105 
10.7. Management of Seizures 
106 
10.8. Participant-Reported Outcome Instruments 
108 

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10.9. COVID-19 Risk Assessment 
109 
10.10. 
Prohibited Inducers, Inhibitors, and Substrates of CYP3A 111 
10.11. 
Selected Medications Known to Lower the Seizure Threshold and/or Cause Seizure
 
112 
10.12. 
COVID-19 Vaccine Risk Assessment 
113 
10.13. 
Protocol Amendment History 
114 
11. 
REFERENCES 
115 
 

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LIST OF TABLES 
Table 1: Abbreviations and Specialist Terms 
12 
Table 2: Schedule of Activities (Screening and Primary Evaluation Periods) 
23 
Table 3: Schedule of Activities (Extended Treatment Period) 
28 
Table 4: Schedule of Activities (Open-label Extension Period) 
32 
Table 5: Potential Risks and Mitigation Strategies 
38 
Table 6: Responsibility for the Clinical Evaluation of gMG 43 
Table 7: Scientific Rationale for the Design of Study ALXN2050-MG-201 45 
Table 8: Study Intervention 
55 
Table 9: Allowed Medications and Therapies 
59 
Table 10: 
MGFA Classification System 
73 
Table 11: 
Protocol-Required Laboratory Assessments 
90 
Table 12: 
Potential Risks and Mitigation Measures due to COVID-19 
109 
Table 13: 
List of Prohibited Inducers, Inhibitors, and Substrates of CYP3A 111 
Table 14: 
Potential Risks and Mitigation Measures due to COVID-19 Vaccine 
113 
 
LIST OF FIGURES 
Figure 1: 
ALXN2050-MG-201 Study Design Schematic 
21 
Figure 2: 
Complement Pathways 36 
 
 
 

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LIST OF ABBREVIATIONS 
The following abbreviations and terms are used in this study protocol. 
Table 1: Abbreviations and Specialist Terms 
Abbreviation or 
Term  
Explanation 
AChEI 
acetylcholinesterase inhibitor 
AChR 
acetylcholine receptor 
ADL 
activities of daily living 
AE 
adverse event 
Anti-HBc 
positive hepatitis B core antibody 
Anti-HBs 
anti-HBc with negative surface antibody 
AP 
alternative pathway 
AUC0-24 
area under the concentration-time curve from time zero to 24 hours 
AxMP 
auxiliary medicinal product 
Ba 
Ba fragment of complement factor B 
Bb 
Bb fragment of complement factor B 
bid 
twice daily 
C 
complement component  
CFR 
Code of Federal Regulations 
CI 
confidence interval 
CIOMS 
Council for International Organizations of Medical Sciences 
Cmax 
maximum (peak) plasma concentration of the drug 
COVID-19 
coronavirus disease 2019 
CP 
classical pathway 
CRF 
case report form 
C-SSRS 
Columbia Suicide Severity Rating Scale 
CT 
computed tomography 
CTIS 
Clinical Trials Information System 
CTR 
Clinical Trials Regulation 
Ctrough 
predose concentration 
CYP3A 
cytochrome P450, family 3, subfamily A 
ECG 
electrocardiogram 
eCRF 
electronic case report form 

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Table 1: Abbreviations and Specialist Terms 
Abbreviation or 
Term  
Explanation 
EDC 
electronic data capture 
EEG 
electroencephalogram 
eGFR 
estimated glomerular filtration rate 
EOS 
end of study 
ETP 
Extended Treatment Period 
EU 
European Union 
FAS 
Full Analysis Set 
FB 
factor B 
FcRn 
human neonatal Fc receptor 
FD 
factor D 
FSH 
follicle-stimulating hormone 
GCP 
Good Clinical Practice 
GDS 
Global Drug Safety 
gMG 
generalized myasthenia gravis 
HbsAg 
hepatitis B positive hepatitis surface antigen 
HCV 
hepatitis C virus 
HIV 
human immunodeficiency virus 
HRT 
hormone replacement therapy 
IB 
Investigator Brochure 
ICF 
informed consent form 
ICH 
International Council for Harmonisation of Technical Requirements for 
Pharmaceuticals for Human Use 
IEC 
Independent Ethics Committee 
IgG 
immunoglobulin G 
IL-6 
interleukin 6 
IMP 
investigational medicinal product 
IRB 
Institutional Review Board 
IRT 
interactive response technology 
IST 
immunosuppressive therapy 
IV 
intravenous(ly) 
IVIg 
intravenous immunoglobulin G 

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Table 1: Abbreviations and Specialist Terms 
Abbreviation or 
Term  
Explanation 
LLN 
lower limit of normal 
LP 
lectin pathway 
LRP4 
low density lipoprotein receptor-related protein 4 
MAC 
membrane attack complex 
MedDRA 
Medical Dictionary for Regulatory Activities 
MG 
myasthenia gravis 
MG-ADL 
Myasthenia Gravis Activities of Daily Living 
MGFA 
Myasthenia Gravis Foundation of America 
MGFA-PIS 
Myasthenia Gravis Foundation of America Post-Intervention Status 
MM 
minimal manifestation 
MMP 
matrix metalloproteinase 
MMRM 
mixed-effects model with repeated measures 
MRI 
magnetic resonance imaging 
MuSK 
muscle-specific tyrosine kinase 
Neuro QoL™ 
Fatigue 
Quality of Life in Neurological Disorders Fatigue questionnaire 
NMJ 
neuromuscular junction 
NOAEL 
no-observed-adverse-effect-level 
OLE 
Open-label Extension 
oMG 
ocular myasthenia gravis 
PD 
pharmacodynamic(s) 
PE 
plasma exchange 
PEP 
Primary Evaluation Period 
PK 
pharmacokinetic(s) 
PP 
plasmapheresis 
PPS 
Per Protocol Set 
QMG 
Quantitative Myasthenia Gravis 
QRS 
combination of the Q wave, R wave, and S wave 
QT 
interval between the start of the Q wave and the end of the T wave 
QTc 
corrected QT interval 
QTcF 
corrected QT interval using Fridericia’s formula 

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Table 1: Abbreviations and Specialist Terms 
Abbreviation or 
Term  
Explanation 
RTSM 
Randomization and Trial Supply Management 
SAE 
serious adverse event 
SAP 
Statistical Analysis Plan 
SAS® 
Statistical Analysis System 
SCIg 
subcutaneous immunoglobulin 
SoA 
Schedule of Activities 
SOC 
System Organ Class 
SS 
Safety Set 
SUSAR 
suspected unexpected serious adverse reaction 
SVR 
sustained virologic response 
TEAE 
treatment-emergent adverse event 
TESAE 
treatment-emergent serious adverse event 
ULN 
upper limit of normal 
WOCBP 
woman of childbearing potential 

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1. 
PROTOCOL SUMMARY 
1.1. 
Synopsis 
Protocol Title: A Phase 2, Randomized, Double-Blind, Placebo-Controlled Multicenter Study to 
Evaluate the Efficacy and Safety of ALXN2050 in Adult Participants with Generalized 
Myasthenia Gravis 
Brief Title: Phase 2 Study of ALXN2050 in Generalized Myasthenia Gravis 
Regulatory Agency Identifier: 
IND:154567 
EudraCT: 2021-001229-26 
EU CT: 2022-502905-14 
Rationale: ALXN2050 is a potent, reversible, small molecule inhibitor of complement factor D 
(FD), which is a key component of the alternative pathway (AP). The complement system is 
involved in the pathophysiology of generalized myasthenia gravis (gMG), and its inhibition has 
been proven to generate clinical benefit. ALXN2050 is an oral molecule that has the potential to 
provide a unique option to patients with gMG who suffer from debilitating and often 
incapacitating symptoms. 
Objectives and Endpoints 
Objectives 
Endpoints 
Primary 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
improvement in the MG-ADL total score 
Proportion of participants with an MG-ADL total 
score reduction of ≥ 2 points in any 4 consecutive 
weeks during the first 8 weeks and who did not 
receive rescue therapy 
Secondary 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
improvement in the QMG total score 
• 
Change from baseline in QMG total score at 
Week 8 
• 
Proportion of participants with at least a 3-, 4-, 
5-, 6-, 7-, or 8-point improvement in the QMG 
total score at Week 8 
• 
Proportion of participants with at least a 3-, 4-, 
5-, 6-, 7-, or 8-point improvement in the QMG 
total score in any 4 consecutive weeks during 
the first 8 weeks and who did not receive 
rescue therapy 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
improvement in quality of life measures 
• 
Change from baseline in Neuro-QoL™ Fatigue 
score at Week 8 

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Objectives 
Endpoints 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
additional endpoints involving the MG-ADL total 
score 
• 
Change from baseline in MG-ADL total score 
at Week 8 
• 
Proportion of participants with at least a 3-, 4-, 
5-, 6-, 7-, or 8-point improvement in the 
MG-ADL total score in any 4 consecutive 
weeks during the first 8 weeks and who did not 
receive rescue therapy 
• 
Proportion of participants with at least a 2-, 3-, 
4-, 5-, 6-, 7-, or 8-point improvement in the 
MG-ADL total score at Week 8 
PK/PD 
To characterize the PK/PD of ALXN2050 and to 
establish the PK/PD relationship in participants 
with gMG 
• 
Observed Cmax and Ctrough values over time 
• 
Absolute values and change from baseline in 
plasma Bb concentration and serum AP activity 
over time 
Biomarker 
To assess the effect of FD inhibition on 
complement biomarkers 
Plasma FD concentration, serum C3 concentration, 
and serum CP activity over time 
Safety 
To characterize the overall safety of ALXN2050 
compared with placebo in participants with gMG 
• 
Incidence of TEAEs and TESAEs over time 
• 
Changes from baseline in laboratory 
assessments 

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Objectives 
Endpoints 
Tertiary/Exploratory  
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
other efficacy endpoints 
• 
Proportion of participants with an MG-ADL 
total score reduction of ≥ 2 points and a QMG 
total score reduction of ≥ 3 points in any 
4 consecutive weeks during the first 8 weeks 
and who did not receive rescue therapy 
• 
Proportion of participants with at least a 
2-point improvement in the MG-ADL total 
score for 4 consecutive weeks (measured from 
Day 1 to Week 8 for Groups 1, 2, and 3 and 
from Week 8 to Week 16 for Groups 3a and 
3b) and who did not receive any rescue therapy 
• 
Change from baseline in MG-ADL total score 
at Week 8 for Groups 1, 2, and 3; and from 
Week 8 to Week 16 for Groups 3a and 3b 
• 
Change from baseline in MG-ADL total score 
at Week 26 for Groups 1 and 2a; and from 
Week 8 to Week 34 for Groups 3a and 3ba 
• 
Incidence of Clinical Deterioration of gMG 
over time 
• 
MGFA-PIS at Week 8 and Week 26a 
• 
Proportion of participants with a classification 
of Minimal Manifestations at Week 8 and 
Week 26a (as measured by the MGFA-PIS) 
• 
Proportion of participants who receive rescue 
therapy over time 
To assess the effect of FD inhibition on AChR 
antibody titers in participants with gMG 
Change of anti-AChR antibody titers over time 
To characterize nongenetic biomarkers in adult 
participants with gMG 
• 
Detection of gMG-associated autoantibodies, 
which may include baseline and/or later 
timepoints (eg, MuSK, LRP4) 
• 
In vitro evaluation of autoantibody activity 
(eg, AChR blocking, complement deposition) 
• 
Absolute values and change from baseline in 
levels of complement proteins and complement 
pathway regulators (eg, C5b-9, Properdin) 
• 
Change from baseline in biomarkers of 
inflammation and NMJ damage (eg, MMP-10, 
IL-6) 
a The comparator will be discussed in detail in the Statistical Analysis Plan. 
Abbreviations: AChR = acetylcholine receptor; AP = alternative pathway; Bb = Bb fragment of complement factor 
B; C3 = complement component 3; C5b-9 = terminal complement complex; Cmax = maximum (peak) plasma 
concentration of the drug; CP = classical pathway; Ctrough = predose concentration; FD = factor D; 
gMG = generalized myasthenia gravis; IL = interleukin; LRP4 = low density lipoprotein receptor-related protein 4; 
MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA-PIS = Myasthenia Gravis Foundation of 
America Post-Intervention Status; MMP-10 = matrix metalloproteinase 10; MuSK = muscle-specific tyrosine 
kinase; Neuro-QoL™ Fatigue = Quality of Life in Neurological Disorders Fatigue questionnaire; 
NMJ = neuromuscular junction; PD = pharmacodynamic; PK = pharmacokinetic; QMG = Quantitative 

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Myasthenia Gravis; TEAE = treatment-emergent adverse event; TESAE = treatment-emergent serious adverse 
event 
Overall Design 
This is a Phase 2, randomized, double-blind, parallel-group, placebo-controlled, multicenter 
study to evaluate the efficacy and safety of ALXN2050 in adult participants (≥ 18 years of age) 
diagnosed with gMG with a Myasthenia Gravis Foundation of America (MGFA) Clinical 
Classification between Class II to IV at the Screening Visit and a Myasthenia Gravis Activities 
of Daily Living (MG-ADL) total score ≥ 5 (with at least 50% of the score attributed to 
non-ocular elements) at the Screening Visit and at randomization (Day 1). 
Approximately 70 eligible participants will be stratified by MG-ADL total score at baseline 
(5 to 6 [capped to approximately 10% of total enrollment] versus ≥ 7) and randomized on Day 1 
in a 2:1:2 ratio to 1 of 3 treatment groups: ALXN2050 180 mg twice daily (bid) (Group 1), 
ALXN2050 120 mg bid (Group 2), or placebo (Group 3). Participants randomized to Group 1 
and Group 2 will receive ALXN2050 during the Primary Evaluation Period (PEP; 8 weeks) and 
the Extended Treatment Period (ETP; 26 weeks). Participants in Group 3 will receive placebo 
treatment during the PEP and at the end of the PEP, will be rerandomized in a 1:1 ratio to receive 
either ALXN2050 180 mg bid (Group 3a) or ALXN2050 120 mg bid (Group 3b). During the 
Open-label Extension (OLE) Period (up to approximately 1.5 years), all participants will receive 
ALXN2050 and will be switched to the optimal dose of ALXN2050 if that dose has been 
identified during the study, as long as the participant has completed the first 34 weeks of 
treatment. 
Disclosure Statement: This is a parallel-group treatment study with 3 groups that are participant 
and Investigator blinded during the PEP. 
Number of Participants: Approximately 70 participants will be initially randomized to 1 of 
3 treatment groups. 
Intervention Groups and Duration: 
The study consists of a Screening Period of up to 4 weeks, a PEP of 8 weeks, an ETP of 
26 weeks, and an OLE Period of up to approximately 1.5 years. An End of Study (EOS) Visit 
will occur 30 days after the last dose of study intervention for all participants. 
The overall study duration for an individual participant will be approximately 125 weeks (from 
the Screening Visit through the EOS Visit). 
Data Monitoring Committee: No 
Ethical Considerations and Benefit-Risk Assessment 
This study will be conducted as specified in this protocol and in accordance with the following: 
• Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical 
Sciences (CIOMS) International Ethical Guidelines 
• Applicable ICH Good Clinical Practice (GCP) Guidelines 
• Applicable laws and regulations 

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A thorough benefit-risk assessment has been performed for ALXN2050. Measures will be taken 
to minimize risk to study participants. The potential risks identified in association with 
ALXN2050 are justified by the anticipated benefits that may be afforded to participants with 
gMG (ALXN2050 Investigator’s Brochure [IB]). 
 

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1.2. 
Schema 
The study design is depicted in Figure 1. 
Figure 1: ALXN2050-MG-201 Study Design Schematic 
 
Note: Participants randomized to placebo will only receive placebo for 8 weeks during the study. 
Abbreviations: bid = twice daily; EOS = end of study; N = number of participants 

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1.3. 
Schedule of Activities (SoA) 
Schedules of activities are provided as follows: 
• Screening and Primary Evaluation Periods (Table 2) 
• Extended Treatment Period (Table 3) 
• Open-label Extension Period (Table 4)

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Table 2: Schedule of Activities (Screening and Primary Evaluation Periods) 
 
Period 
Screening 
Period 
Primary Evaluation Period 
 
 
 
Study Day (D) 
Up to 
27 days 
prior to 
D1 
D1 
D8 
D15 
D22 
D29 
D36 
D43 
D50 
D57 
EDa 
CDb 
EOS
a 
Study Week (W) 
NA 
NA 
W1 
W2 
W3 
W4 
W5 
W6 
W7 
W8 
NA 
NA 
NA 
Study Window (days) 
NA 
NA 
±1 
±1 
±1 
±1 
±1 
±1 
±1 
±1 
NA 
NA 
±2 
Eligibility 
 
 
 
 
 
 
 
 
 
 
 
 
 
Informed consent 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Inclusion/exclusion 
X 
Xc 
 
 
 
 
 
 
 
 
 
 
 
Medical historyd 
X 
 
 
 
 
 
 
 
 
 
 
 
 
MG historye 
X 
 
 
 
 
 
 
 
 
 
 
 
 
MGFA classificationf 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Height 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Weight 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Demographics 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Study Administrative 
 
 
 
 
 
 
 
 
 
 
 
 
 
Vaccination or confirmation of vaccination against 
Neisseria meningitidisg 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Screening Laboratory Tests 
 
 
 
 
 
 
 
 
 
 
 
 
 
HIV-1, HIV-2, Hepatitis B and C 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Serum pregnancyh 
X 
 
 
 
 
 
 
 
 
 
X 
 
X 
Urine pregnancyh 
 
X 
 
 
 
X 
 
 
 
X 
 
X 
 
Follicle-stimulating hormonei 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Randomization 
 
 
 
 
 
 
 
 
 
 
 
 
 
Randomized to study interventionj 
 
X 
 
 
 
 
 
 
 
Xk 
 
 
 
Study Intervention 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Table 2: Schedule of Activities (Screening and Primary Evaluation Periods) 
 
Period 
Screening 
Period 
Primary Evaluation Period 
 
 
 
Study Day (D) 
Up to 
27 days 
prior to 
D1 
D1 
D8 
D15 
D22 
D29 
D36 
D43 
D50 
D57 
EDa 
CDb 
EOS
a 
Study Week (W) 
NA 
NA 
W1 
W2 
W3 
W4 
W5 
W6 
W7 
W8 
NA 
NA 
NA 
Study Window (days) 
NA 
NA 
±1 
±1 
±1 
±1 
±1 
±1 
±1 
±1 
NA 
NA 
±2 
Dispensation of study interventionl 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
 
Administration of ALXN2050 or Placebom 
 
X 
X 
X 
X 
X 
X 
X 
X 
Xn 
 
 
 
Complete participant eDiary (optional) 
 
Immediately following administration of study intervention 
 
 
 
Efficacy Assessments 
 
 
 
 
 
 
 
 
 
 
 
 
 
QMGf, o 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
MG-ADLf, p 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
MGFA-PISf 
 
 
 
 
 
X 
 
 
 
X 
X 
 
 
Neuro-QoL™ Fatigue 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
 
Safety Assessments 
 
 
 
 
 
 
 
 
 
 
 
 
 
C-SSRS Baselineq 
 
X 
 
 
 
 
 
 
 
 
 
 
 
C-SSRS Since Last Visitq 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
Electrocardiogram 
X 
X 
 
 
 
 
 
 
 
X 
X 
 
 
Complete physical examination, including 
neurological component 
X 
 
 
 
 
 
 
 
 
 
X 
X 
 
Abbreviated physical examinationr, s 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
 
Vital sign measurementst 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
Adverse event review and evaluation 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Assess for CDb 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
Review Participant Safety Cardu 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
Safety Laboratory Testsv 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Table 2: Schedule of Activities (Screening and Primary Evaluation Periods) 
 
Period 
Screening 
Period 
Primary Evaluation Period 
 
 
 
Study Day (D) 
Up to 
27 days 
prior to 
D1 
D1 
D8 
D15 
D22 
D29 
D36 
D43 
D50 
D57 
EDa 
CDb 
EOS
a 
Study Week (W) 
NA 
NA 
W1 
W2 
W3 
W4 
W5 
W6 
W7 
W8 
NA 
NA 
NA 
Study Window (days) 
NA 
NA 
±1 
±1 
±1 
±1 
±1 
±1 
±1 
±1 
NA 
NA 
±2 
Clinical chemistry 
X 
X 
 
 
 
X 
 
 
 
X 
X 
X 
 
Hematology 
X 
X 
 
 
 
X 
 
 
 
X 
X 
X 
 
Coagulation panel 
X 
X 
 
 
 
X 
 
 
 
X 
X 
X 
 
Urinalysis 
X 
X 
 
 
 
X 
 
 
 
X 
X 
X 
 
PK/PD Testsw 
 
 
 
 
 
 
 
 
 
 
 
 
 
PK 
 
Xx 
 
 
 
Xy 
 
 
 
Xx 
 
Xy 
 
PD: AP activity and Bbz 
 
X 
 
 
 
X 
 
 
 
X 
 
X 
 
Biomarker Tests 
 
 
 
 
 
 
 
 
 
 
 
 
 
Anti-AChR antibody 
X 
Xaa 
 
 
 
X 
 
 
 
X 
X 
X 
 
Factor D, C3, CP activity, nongenetic exploratory 
biomarkers (eg, MuSK, LRP4)ab  
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
 
Other 
 
 
 
 
 
 
 
 
 
 
 
 
 
Concomitant medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Nonpharmacologic treatments and therapies 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
a If a participant is discontinued from the study during the PEP, an ED Visit will be performed, and then an EOS Visit will be performed 30 (±2) days after the 
last dose of study intervention. 
b Evaluation of CD must be performed as soon as possible, within 48 h of notification to the Investigator of symptom onset. If CD occurs between scheduled 
visits, only the assessments for the CD Visit are needed. If CD occurs on a scheduled visit, all scheduled assessments should be performed for that visit as well 
as for the evaluation of CD. Additional evaluation visits may be scheduled at the discretion of the Investigator. 
Table 2: Schedule of Activities (Screening and Primary Evaluation Periods) 
c Confirm on Day 1. 

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d Includes substance usage, and past and current medical conditions, including surgical history. 
e MG history parameters that will be obtained are listed in Section 8.11.4. 
f MG assessments should be performed at approximately the same time of day by a properly trained Clinical Evaluator (preferably the same evaluator) 
throughout the study. The MG-ADL should always be performed first, followed by the QMG. 
Note: A Clinical Evaluator may be a neurologist, neurologist in training, or delegated member of the investigational site staff who has been certified in 
administering the assessments. 
g To reduce the risk of meningococcal infection (Neisseria meningitidis), all participants must be vaccinated against meningococcal infection within 3 years or 
before the administration of study intervention on Day 1. Participants who initiate study intervention treatment less than 2 weeks after receiving a 
meningococcal vaccine must receive treatment with appropriate prophylactic antibiotics until at least 2 weeks after vaccination. 
h Pregnancy tests must be performed on all participants of childbearing potential at the specified time points. Serum pregnancy test will be performed at the 
Screening, ED, and EOS visits; urine pregnancy tests will be performed locally at all other specified time points. Additional pregnancy tests (urine or serum) 
may also be performed at any in-clinic visit at the Investigator’s discretion. 
i Follicle-stimulating hormone may be obtained at the Screening Visit to confirm postmenopausal status in female participants who are considered 
postmenopausal ONLY. This test is not needed for men and will not be conducted in women of childbearing potential. 
j All participants who continue to meet all inclusion criteria and none of the exclusion criteria and have been cleared for randomization by the Investigator will 
be centrally randomized via an interactive response technology. 
k Participants randomized to placebo will be further randomized to 1 of the 2 active treatment groups (ie, ALXN2050 120 or 180 mg bid). 
l Ensure kit and lot number are recorded on the drug accountability log. 
m Dosing is by mouth bid throughout the PEP. 
n Participants will receive newly dispensed study intervention at Week 8 and the first dose will be administered during this visit. The participant will then 
continue at home dosing per protocol. 
o The QMG assessment should be performed by a properly trained Clinical Evaluator (preferably the same evaluator) throughout the study. If a participant is 
taking a cholinesterase inhibitor, the dose must be withheld for at least 8 h prior to the assessment and, whenever possible, the time from the last dose to the 
QMG assessment should be kept similar between visits. 
p The MG-ADL is required to be performed first, followed by the QMG. The MG-ADL assessment should be performed by a properly trained Clinical Evaluator 
(preferably the same evaluator) throughout the study. 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. 
q  C-SSRS will be assessed for both lifetime and past 12 months at Baseline, and Since Last Visit for subsequent visits. 
r The abbreviated physical examination will be performed, if necessary, on the basis of the participant’s health status and the clinical judgment of the 
Investigator. 
s A symptom based neurologic examination should be performed if the participant has any complaints or clinical findings attributable to the central nervous 
system and if positive for findings, a full neurologic examination will need to be performed at that assessment time point and at future time points as needed 
(determined by the Investigator). 
t Vital sign measurements will include systolic and diastolic blood pressure (millimeters of mercury [mmHg]), heart rate (beats/minute), and temperature 
(degrees Celsius [°C] or degrees Fahrenheit [°F]). On dosing days, vital signs will be taken before study intervention administration and after the participant 
has been resting for at least 5 minutes. 
Table 2: Schedule of Activities (Screening and Primary Evaluation Periods) 

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u Participants will be given a safety card prior to the first dose of study intervention. At each visit throughout the study, investigational site staff will ensure that 
the participant has the safety card and will review the guidelines with the participant. 
v  Safety laboratory samples will be analyzed by the central laboratory. A list of parameters that will be obtained during the study are provided in Table 11. 
w Baseline and trough blood samples for serum PK will be collected predose (within 30 minutes prior to the administration of study intervention). Peak blood 
samples for serum PK/PD are to be taken 2 ± 0.5 h and 4 ± 0.5 h postdose. All collection times will be recorded in the participant’s electronic case report form. 
x Trough (within 30 minutes predose) and peak (2 ± 0.5 h and 4 ± 0.5 h postdose). 
y Trough (within 30 minutes predose). 
z AP activity within 30 minutes predose and 2 ± 0.5 h and 4 ± 0.5 h postdose at Day 1 and Week 8, and within 30 minutes predose at Week 4 and CD. Bb 
sampling within 30 minutes predose and 2 ± 0.5 h postdose at Day 1, and within 30 minutes predose at all other in clinic visits. 
aa Collect predose on Day 1. 
ab Collect predose. 
Abbreviations: AChR = acetylcholine receptor; AP = alternative pathway; Bb = Bb fragment of complement factor B; bid = twice daily; C3 = complement 
component 3; CD = Clinical Deterioration; CP = classical pathway; C-SSRS = Columbia Suicide Severity Rating Scale; D = Day; ED = early discontinuation; 
eDiary = electronic diary; EOS = end of study; h = hour(s); HIV = human immunodeficiency virus; LRP4 = low density lipoprotein receptor-related protein 4; 
MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA = Myasthenia Gravis Foundation of America; 
MGFA-PIS = Myasthenia Gravis Foundation of America Post-Intervention Status; MuSK = muscle-specific tyrosine kinase; NA = not applicable; 
Neuro-QoL™ Fatigue = Quality of Life in Neurological Disorders Fatigue questionnaire; PD = pharmacodynamic; PEP = Primary Evaluation Period; 
PK = pharmacokinetic; QMG = Quantitative Myasthenia Gravis score for disease severity; W = Week 

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Table 3: Schedule of Activities (Extended Treatment Period) 
 
Period 
Extended Treatment Perioda 
 
 
 
Study Year 
Year 1 
 
 
 
Study Day (D)  
D64 
D71 
D78 
D85 
D92 
D99 
D106 
D113 
D183 
D239 
EDb 
CDc 
EOSb 
Study Week (W) 
W9 
W10 
W11 
W12 
W13 
W14 
W15 
W16 
W26 
W34 
NA 
NA 
NA 
Visit Type 
Phone 
call 
Phone 
call 
Phone 
call 
In-
clinic 
Phone 
call 
Phone 
call 
Phone 
call 
In-
clinic 
In-
clinic 
In-
clinic 
In-
clinic 
In-
clinic 
In-
clinic 
Study Window (days) 
NA 
NA 
NA 
±3 
NA 
NA 
NA 
±3 
±3 
±3 
NA 
NA 
±2 
Administration of Study Intervention 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dispensation of study interventiond 
 
 
 
X 
 
 
 
X 
X 
X 
 
 
 
Administration of ALXN2050e 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Xf 
 
 
 
Complete participant eDiary (optional) 
Immediately following administration of study intervention 
 
 
 
Efficacy Assessments 
 
 
 
 
 
 
 
 
 
 
 
 
 
QMGg, h 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
MG-ADLg, i 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
MGFA-PISg 
 
 
 
X 
 
 
 
X 
X 
X 
X 
 
 
Neuro-QoL™ Fatigue 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Safety Assessments 
 
 
 
 
 
 
 
 
 
 
 
 
 
C-SSRS Since Last Visitj 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Electrocardiogram 
 
 
 
 
 
 
 
 
X 
X 
X 
 
 
Complete physical examination, 
including neurological component 
 
 
 
 
 
 
 
 
 
 
X 
X 
 
Abbreviated physical examinationk, l 
 
 
 
X 
 
 
 
X 
X 
X 
 
 
 
Vital sign measurementsm 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Adverse event review and evaluation 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Assess for CDc 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
Review Participant Safety cardn 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 

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Table 3: Schedule of Activities (Extended Treatment Period) 
 
Period 
Extended Treatment Perioda 
 
 
 
Study Year 
Year 1 
 
 
 
Study Day (D)  
D64 
D71 
D78 
D85 
D92 
D99 
D106 
D113 
D183 
D239 
EDb 
CDc 
EOSb 
Study Week (W) 
W9 
W10 
W11 
W12 
W13 
W14 
W15 
W16 
W26 
W34 
NA 
NA 
NA 
Visit Type 
Phone 
call 
Phone 
call 
Phone 
call 
In-
clinic 
Phone 
call 
Phone 
call 
Phone 
call 
In-
clinic 
In-
clinic 
In-
clinic 
In-
clinic 
In-
clinic 
In-
clinic 
Study Window (days) 
NA 
NA 
NA 
±3 
NA 
NA 
NA 
±3 
±3 
±3 
NA 
NA 
±2 
Safety Laboratory Testso 
 
 
 
 
 
 
 
 
 
 
 
 
 
Serum pregnancyp 
 
 
 
 
 
 
 
 
 
 
X 
 
X 
Urine pregnancyp 
 
 
 
X 
 
 
 
X 
X 
X 
 
X 
 
Clinical chemistry 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Hematology 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Coagulation panel 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Urinalysis 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
PK/PD Testsq 
 
 
 
 
 
 
 
 
 
 
 
 
 
PK 
 
 
 
Xr 
 
 
 
Xs 
Xr 
Xr 
 
Xr 
 
PD: AP activity and Bbt 
 
 
 
X 
 
 
 
X 
X 
X 
 
X 
 
Biomarker Tests 
 
 
 
 
 
 
 
 
 
 
 
 
 
Anti-AChR antibody 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Factor D, C3, CP activity, nongenetic 
exploratory biomarkers (eg, MuSK, 
LRP4)u 
 
 
 
X 
 
 
 
X 
X 
X 
X 
X 
 
Other 
 
 
 
X 
 
 
 
 
 
 
 
 
 
Concomitant medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Nonpharmacologic treatments and 
therapies 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
a The ETP begins at the Day 57 (Week 8) Visit after all assessments of the visit are performed, but before the administration of ALXN2050 in the clinic and 
postdose PK/PD sampling. 

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Table 3: 
Schedule of Activities (Extended Treatment Period) 
b If a participant is discontinued from the study during the ETP, an ED Visit will be performed, and then an EOS Visit will be performed 30 (±2) days after the 
last dose of study intervention. 
c Evaluation of CD must be performed as soon as possible, within 48 h of notification to the Investigator of symptom onset. If CD occurs between scheduled 
visits, only the assessments for the CD Visit are needed. If CD occurs on a scheduled visit, all scheduled assessments should be performed for that visit as well 
as for the evaluation of CD. Additional evaluation visits may be scheduled at the discretion of the Investigator. 
d Ensure kit and lot number are recorded on the drug accountability log. 
e Dosing is by mouth bid throughout the ETP. 
f Participants will receive newly dispensed study intervention at Week 34 and the first dose will be administered during this visit. The participant will then 
continue at home dosing per protocol. 
g MG assessments should be performed at approximately the same time of day by a properly trained Clinical Evaluator (preferably the same evaluator). The 
MG-ADL should always be performed first, followed by the QMG. 
Note: A Clinical Evaluator may be a neurologist, neurologist in training, or delegated member of the investigational site staff who has been certified in 
administering the assessments. 
h The QMG assessment should be performed by a properly trained Clinical Evaluator (preferably the same evaluator) throughout the study. If a participant is 
taking a cholinesterase inhibitor, the dose must be withheld for at least 8 h prior to the assessment and, whenever possible, the time from the last dose to the 
QMG assessment should be kept similar between visits. 
i The MG-ADL is required to be performed first, followed by the QMG. The MG-ADL assessment should be performed by a properly trained Clinical Evaluator 
(preferably the same evaluator) throughout the study. 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 will be assessed by phone at Weeks 9, 10, 11, 13, 14, and 15. 
j C-SSRS will be assessed Since Last Visit. 
k To be performed, if necessary, on the basis of the participant’s health status and the clinical judgment of the Investigator. 
l A symptom based neurologic examination should be performed if the participant has any complaints or clinical findings attributable to the central nervous 
system and if positive for findings, a full neurologic examination will need to be performed at that assessment time point and at future time points as needed 
(determined by the Investigator). 
m Vital sign measurements will include systolic and diastolic blood pressure (millimeters of mercury [mmHg]), heart rate (beats/minute), and temperature 
(degrees Celsius [°C] or degrees Fahrenheit [°F]). On dosing days, vital signs will be taken before study intervention administration and after the participant 
has been resting for at least 5 minutes. 
n Participants will be given a safety card prior to the first dose of study intervention. At each visit throughout the study, investigational site staff will ensure that 
the participant has the safety card and will review the guidelines with the participant. 
o Safety laboratory samples will be analyzed by the central laboratory. A list of parameters that will be obtained during the study are provided in Table 11. 
p Pregnancy tests must be performed on all participants of childbearing potential at the specified time points. A serum pregnancy test will be performed at the ED 
and EOS visits; urine pregnancy tests will be performed locally at all other specified time points. Additional pregnancy tests (urine or serum) may also be 
performed at any in-clinic visit at the Investigator’s discretion. 
q Trough blood samples for serum PK will be collected predose (within 30 minutes prior to the administration of study intervention). Peak blood samples for 
serum PK/PD are to be taken 2 ± 0.5 h and 4 ± 0.5 h postdose. All collection times will be recorded in the participant’s electronic case report form. 
r Trough (within 30 minutes predose). 
s Trough (within 30 minutes predose) and peak (2 ± 0.5 h and 4 ± 0.5 h postdose). 
 

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Table 3: 
Schedule of Activities (Extended Treatment Period) 
t AP activity within 30 minutes predose at Weeks 12, 26, 34, and CD, and within 30 minutes predose and 2 ± 0.5 h and 4± 0.5 h postdose at Week 16. Bb 
sampling within 30 minutes predose at all visits. 
u Collect predose. 
Abbreviations: AChR = acetylcholine receptor; AP = alternative pathway; Bb = Bb fragment of complement factor B; bid = twice daily; C3 = complement 
component 3; CD = Clinical Deterioration; CP = classical pathway; C-SSRS = Columbia Suicide Severity Rating Scale; D = Day; ED = early discontinuation; 
eDiary = electronic diary; EOS = end of study; ETP = Extended Treatment Period; h = hour(s); LRP4 = low density lipoprotein receptor-related protein 4; 
MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA-PIS = Myasthenia Gravis Foundation of America 
Post-Intervention Status; MuSK = muscle-specific tyrosine kinase; NA = not applicable; Neuro-QoL™ Fatigue = Neurological Quality of Life Fatigue 
questionnaire; PD = pharmacodynamic; PK = pharmacokinetic; QMG = Quantitative Myasthenia Gravis score for disease severity; W = Week 
 
 

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Table 4: Schedule of Activities (Open-label Extension Period) 
Period 
Open-label Extension Perioda 
 
 
 
Study Year 
Year 1 (cont’d) 
Year 2+ 
EDb 
CDc 
EOSb 
Study Day (D)  
D365 
D456 
D547 
D638 
D729 
D820 
NA 
NA 
NA 
Study Week (W) 
W52 
W65 
W78 
W91 
W104 
W117 
NA 
NA 
NA 
Study Window (days) 
±7 
±7 
±7 
±7 
±7 
±7 
NA 
NA 
±2 
Administration of Study Intervention 
 
 
 
 
 
 
 
 
 
Dispensation of study interventiond 
X 
X 
X 
X 
X 
 
 
 
 
Administration of ALXN2050e 
X 
X 
X 
X 
X 
X 
 
 
 
Complete participant eDiary (optional) 
Immediately following administration of study intervention 
 
 
 
Efficacy Assessments 
 
 
 
 
 
 
 
 
 
QMGf,g 
X 
X 
X 
X 
X 
X 
X 
X 
 
MG-ADLf,h 
X 
X 
X 
X 
X 
X 
X 
X 
 
MGFA-PISf 
X 
 
X 
 
X 
X 
X 
X 
 
Neuro-QoL™ Fatigue 
X 
X 
X 
X 
X 
X 
X 
X 
 
Safety Assessments 
 
 
 
 
 
 
 
 
 
C-SSRS Since Last Visiti 
X 
X 
X 
X 
X 
X 
X 
X 
 
Electrocardiogram 
 
 
 
 
 
X 
X 
 
 
Complete physical examination, including 
neurological component 
 
 
 
 
 
X 
X 
X 
 
Abbreviated physical examinationj,k 
X 
X 
X 
X 
X 
 
 
 
 
Vital sign measurementsl 
X 
X 
X 
X 
X 
X 
X 
X 
 
Adverse event review and evaluation 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Assess for CDc 
X 
X 
X 
X 
X 
X 
X 
 
 
Review Participant Safety Cardm 
X 
X 
X 
X 
X 
X 
X 
X 
 
Safety Laboratory Testsn 
 
 
 
 
 
 
 
 
 
Serum pregnancyo 
 
 
 
 
 
 
X 
 
X 

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Table 4: Schedule of Activities (Open-label Extension Period) 
Period 
Open-label Extension Perioda 
 
 
 
Study Year 
Year 1 (cont’d) 
Year 2+ 
EDb 
CDc 
EOSb 
Study Day (D)  
D365 
D456 
D547 
D638 
D729 
D820 
NA 
NA 
NA 
Study Week (W) 
W52 
W65 
W78 
W91 
W104 
W117 
NA 
NA 
NA 
Study Window (days) 
±7 
±7 
±7 
±7 
±7 
±7 
NA 
NA 
±2 
Urine pregnancyo 
X 
X 
X 
X 
X 
X 
 
X 
 
Clinical chemistry 
X 
X 
X 
X 
X 
X 
X 
X 
 
Hematology 
X 
X 
X 
X 
X 
X 
X 
X 
 
Coagulation panel 
X 
X 
X 
X 
X 
X 
X 
X 
 
Urinalysis 
X 
X 
X 
X 
X 
X 
X 
X 
 
PK/PD Testsp 
 
 
 
 
 
 
 
 
 
PKq 
 
 
 
 
 
 
 
X 
 
PD: AP activity and Bbr 
 
 
 
 
 
 
 
X 
 
Biomarker Tests 
 
 
 
 
 
 
 
 
 
Anti-AChR antibody 
X 
 
 
 
 
X 
X 
X 
 
Factor D, C3, CP activity, nongenetic exploratory 
biomarkers (eg, MuSK, LRP4)r 
 
 
 
 
 
 
 
X 
 
Other 
 
 
 
 
 
 
 
 
 
Concomitant medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Nonpharmacologic treatments and therapies 
X 
X 
X 
X 
X 
X 
X 
X 
X 
a The OLE Period begins at the Day 239 (Week 34) visit after all assessments of the visit are performed, but before the administration of ALXN2050 in the clinic 
and postdose PK/PD sampling. The next in-clinic visit will be at Week 52. 
b If a participant is discontinued from the study during the OLE Period, an ED Visit will be performed, and then an EOS Visit will be performed 30 (±2) days 
after the last dose of study intervention. 
c Evaluation of CD must be performed as soon as possible, within 48 h of notification to the Investigator of symptom onset. If CD occurs between scheduled 
visits, only the assessments for the CD Visit are needed. If CD occurs on a scheduled visit, all scheduled assessments should be performed for that visit as well 
as for the evaluation of CD. Additional evaluation visits may be scheduled at the discretion of the Investigator. 
d Ensure kit and lot number are recorded on the drug accountability log. 
Table 4: Schedule of Activities (Open-label Extension Period) 

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e Dosing is by mouth bid throughout the OLE Period. 
f MG assessments should be performed at approximately the same time of day by a properly trained Clinical Evaluator (preferably the same evaluator). The 
MG-ADL should always be performed first, followed by the QMG. 
g The QMG assessment should be performed by a properly trained Clinical Evaluator (preferably the same evaluator) throughout the study. If a participant is 
taking a cholinesterase inhibitor, the dose must be withheld for at least 8 h prior to the assessment and, whenever possible, the time from the last dose to the 
QMG assessment should be kept similar between visits. 
h The MG-ADL is required to be performed first, followed by the QMG. The MG-ADL assessment should be performed by a properly trained Clinical Evaluator 
(preferably the same evaluator) throughout the study. 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. 
i C SSRS will be assessed Since Last Visit. 
j The abbreviated physical examination will be performed, if necessary, on the basis of the participant’s health status and the clinical judgment of the 
Investigator. 
k A symptom based neurologic examination should be performed if the participant has any complaints or clinical findings attributable to the central nervous 
system and if positive for findings, a full neurologic examination will need to be performed at that assessment time point and at future time points as needed 
(determined by the Investigator). 
l Vital sign measurements will include systolic and diastolic blood pressure (millimeters of mercury [mmHg]), heart rate (beats/minute), and temperature 
(degrees Celsius [°C] or degrees Fahrenheit [°F]). On dosing days, vital signs will be taken before study intervention administration and after the participant 
has been resting for at least 5 minutes. 
m Participants will be given a safety card prior to the first dose of study intervention. At each visit throughout the study, investigational site staff will ensure that 
the participant has the safety card and will review the guidelines with the participant. 
n Laboratory samples will be analyzed by the central laboratory. A list of parameters that will be obtained during the study is provided in Table 11. 
Note: A Clinical Evaluator may be a neurologist, neurologist in training, or delegated member of the investigational site staff who has been certified in 
administering the assessments. 
o Pregnancy tests must be performed on all participants of childbearing potential at the specified time points. Serum pregnancy test will be performed at the ED 
and EOS visits; urine pregnancy tests will be performed locally at all other specified time points. Additional pregnancy tests (urine or serum) may also be 
performed at any visit at the Investigator’s discretion. 
p Trough blood samples for serum PK will be collected predose (within 30 minutes prior to the administration of study intervention). All collection times will be 
recorded in the participant’s electronic case report form. 
q Trough (within 30 minutes predose). 
r Collect predose (within 30 minutes). 
Abbreviations: AChR = acetylcholine receptor; AP = alternative pathway; Bb = Bb fragment of complement factor B; bid = twice daily; C3 = complement 
component 3; CD = Clinical Deterioration; CP = classical pathway; C-SSRS = Columbia Suicide Severity Rating Scale; D = Day; ED = early discontinuation; 
eDiary = electronic diary; EOS = end of study; h = hour(s); LRP4 = low density lipoprotein receptor-related protein 4; MG = myasthenia gravis; 
MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA-PIS = Myasthenia Gravis Foundation of America Post-Intervention Status; MuSK = muscle-
specific tyrosine kinase; NA = not applicable; Neuro-QoL™ Fatigue = Neurological Quality of Life Fatigue questionnaire; OLE = Open-label Extension; 
PD = pharmacodynamic; PK = pharmacokinetic; QMG = Quantitative Myasthenia Gravis score for disease severity; W = Week 

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2. 
INTRODUCTION 
2.1. 
Study Rationale 
ALXN2050 is a potent, reversible, small molecule inhibitor of complement FD, which is a key 
component of the AP. The complement system is involved in the pathophysiology of 
anti-acetylcholine receptor (AChR) antibody-positive gMG, and its inhibition has been proven to 
generate clinical benefit (Howard, 2017). ALXN2050 is an oral molecule that has the potential to 
provide a unique option to patients with gMG who suffer from debilitating and often 
incapacitating symptoms. 
2.2. 
Background 
2.2.1. 
Myasthenia Gravis 
Myasthenia gravis is a rare, debilitating, chronic, complement-mediated autoimmune disease 
characterized by the failure of neuromuscular signal transmission. Voluntary muscle contraction 
requires the release of acetylcholine from nerve endings at the neuromuscular junction (NMJ). 
The majority of patients with myasthenia gravis (MG) produce autoantibodies that target the 
AChR. However, a minority of patients instead produce autoantibodies against other targets, 
such as muscle-specific tyrosine kinase (MuSK), which is involved in AChR clustering at the 
surface of muscle fibers (Conti-Fine, 2006; Gilhus, 2015; Nesargikar, 2012). 
MG is clinically characterized by weakness and rapid fatigability of skeletal muscles that is 
exacerbated during periods of activity and improves after periods of rest (Barnett, 2014; Sieb, 
2014). Based on criteria established by the MGFA, clinical severity of the disease is classified 
from Class I for ocular symptoms and signs only to Class V for severe generalized weakness that 
requires intubation for mechanical ventilation or the prevention of aspiration (Jaretzki, 2000). 
Approximately 80% of patients initially present with signs and symptoms consistent with ocular 
weakness: drooping eyelids (ptosis) and impaired eye movements causing double vision 
(diplopia). Of these, close to 85% will develop gMG (Grob, 2008). Generalized MG may affect 
the ability to speak or swallow, involve weakness of neck and limb muscles, lead to breathing 
difficulty, and result in increased general fatigue (Hoffmann, 2016). Muscle weakness and 
fatigue cause disability, impede activities of daily living (ADL), and impact the quality of 
patients’ lives. 
MG has a prevalence of 107 to 278 per million persons and affects men and women in an 
approximately equal ratio (Cetin, 2012; Cortes-Vicente, 2020; Fang, 2015; Heldal, 2009; Murai, 
2011; Park, 2016). In younger people, MG is more prevalent in women than in men, and this 
trend is reversed in older people (Asmail, 2019; Grob, 2008; Keesey, 2004; Park, 2016). Of the 
15% to 20% of patients who will experience a myasthenic crisis during the course of their 
disease, most (75% of patients) will experience an event within 2 years of diagnosis, requiring 
hospitalization and ventilatory support (Grob, 2008). Based on data reported from 2006 through 
2016, mortality among patients with MG is approximately 1.5% (Westerberg, 2020). 
The international consensus guidance for management of gMG includes cholinesterase inhibitors 
for the strengthening of neuromuscular transmission and immunosuppression for the reduction of 

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autoantibodies (Gilhus, 2019; Narayanaswami, 2021); however, in many cases only temporary 
relief of symptoms is provided, and overall disease activity persists (Guptill, 2016). Targeted 
blockade of terminal complement activity is another therapeutic option for patients with gMG 
that has been established to address the unmet need of patients who do not respond, or 
insufficiently respond, to prior treatments (Howard, 2017). 
2.2.2. 
ALXN2050 
ALXN2050 is an orally active, small molecule, complement FD inhibitor that is in development 
for the treatment of complement-mediated diseases. 
FD is a serine protease that catalyzes the cleavage of complement factor B (FB) into Ba and Bb, 
which allows for the formation of the AP complement component (C)3 convertase (C3bBb). 
Factor D was chosen as a therapeutic target because, of the complement proteins, it has the 
lowest abundance in serum, and it catalyzes the essential step of AP activation and amplification, 
which leads to opsonization by C3 fragments and eventual activation of the terminal complement 
cascade. Although ALXN2050 does not inhibit components specific to the classical pathway 
(CP) or lectin pathway (LP), nor does it directly inhibit components of the terminal complement 
pathway, it will inhibit the AP-mediated amplification of complement activity initiated via the 
CP and LP (Harboe, 2004). 
Figure 2: Complement Pathways 
 
Abbreviations: C = complement component; FB = factor B; FD = factor D; MAC = membrane attack complex 
Source: Adapted from (Merle, 2015a; Merle, 2015b; Yuan, 2017) 

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2.2.3. 
Rationale for Evaluating ALXN2050 in Participants with Generalized 
Myasthenia Gravis 
Preclinical and clinical data suggest that activated terminal complement plays a role in the 
destruction of NMJ endplate morphology and impairment of neuromuscular transmission  
(Zhou, 2007). Anti-AChR antibodies bind to the postsynaptic cleft activating complement, which 
ultimately leads to the formation of the membrane attack complex (MAC). The MAC damages 
the NMJ, thus impairing neuromuscular transmission (affecting approximately 85% of patients 
with MG) (Mantegazza, 1988; Somnier, 1993; Vincent, 1985). 
Complement activation by AChR autoantibodies is an important pathophysiological mechanism 
in gMG. The clinical importance of complement activation in gMG was demonstrated by the 
therapeutic benefits that have been achieved with the C5 inhibitor eculizumab (SOLIRIS®) and 
ravulizumab (ULTOMIRIS®). Eculizumab increased muscle strength measured by the 
Quantitative Myasthenia Gravis (QMG) score in Phase 2 and Phase 3 studies involving 
participants with gMG who previously did not respond to immunosuppressive therapy (IST) 
(Howard, 2013; Howard, 2017). Eculizumab also reduced the general fatigue associated with 
gMG (Andersen, 2019). Treatment with ravulizumab resulted in improvements in MG-ADL and 
QMG scores within 1 week that were maintained through the treatment period (Vu, 2022). 
Additional information may be found in the eculizumab and ravulizumab product labels. 
Eculizumab and ravulizumab exert their effects by directly inhibiting the cleavage of C5 into 
C5a and C5b. This prevents the activation of the terminal complement pathway, which results in 
protection of the NMJ from complement-mediated damage, even in the presence of anti-AChR 
antibodies. This preservation of NMJ activity translates clinically into improved muscle strength 
and function. 
While the role of the AP, and specifically FD, has not been studied in as much detail as the CP 
and terminal pathway in gMG, in vitro and preclinical evidence support a contribution of the AP 
to the pathophysiology of gMG. In a preclinical autoimmune MG rat model, direct inhibition of 
FB, another key protein in the AP, was shown experimentally to prevent the passive induction of 
MG (Subias, 2014). Given that FD catalyzes the rate limiting cleavage of AP protein FB into Ba 
and Bb, pharmacologic inhibition of FD will ultimately result in a reduction of FB activity and 
may therefore produce similar effects to direct FB inhibition. 
Additionally, the AP-based amplification loop plays an important role in augmenting the 
function of the CP, including the formation of the terminal complement components that are 
responsible for the NMJ damage observed in patients with gMG. This importance has been 
quantified by in vitro data which shows that decreasing the AP amplification loop via FD 
inhibition results in a greater than 80% reduction of the terminal MAC (Harboe, 2004). 
Factor D is the least abundant complement protein, yet it is a rate limiting component of the AP, 
thus making it an ideal pharmaceutical target. ALXN2050 is a potent inhibitor of FD with 
demonstrated dose-dependent inhibition of complement AP activity after administration to 
healthy volunteers in single-ascending and multiple-ascending dose studies. Plasma Bb 
concentrations also showed significant dose-dependent reductions. 
As an orally administered small molecule, ALXN2050 would provide an important first-in-class 
treatment option for patients with gMG. Available approved therapies, and many of those 
currently in development, rely on intravenous (IV) or subcutaneous administration. This may 

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result in a treatment burden for patients with gMG and their families, especially if the disease 
manifestation is severe enough to impair mobility, vision, or dexterity. An approved, effective, 
oral molecule would provide these patients with a more convenient and accessible option for 
gMG therapy, which may lead to better compliance and clinical outcomes. 
Additional nonclinical and clinical data may be found in the ALXN2050 IB. 
2.3. 
Benefit/Risk Assessment 
2.3.1. 
Risk Assessment 
Potential risks associated with participation in this study and risk mitigation measures are 
presented in Table 5. 
Table 5: Potential Risks and Mitigation Strategies 
Potential Risk of Clinical 
Significance 
Summary of Data/Rationale 
for Risk 
Mitigation Strategy 
Study Intervention(s) 
Meningococcal infection 
Participants receiving Factor D 
complement inhibitor therapy 
may have an increased risk of 
infections, particularly Neisseria 
meningitidis. 
All participants must be vaccinated 
against meningococcal disease within 
3 years prior to, or at the time of, 
initiating the study intervention. 
Participants who initiate study 
intervention less than 2 weeks after 
receiving a meningococcal vaccine 
must receive treatment with appropriate 
prophylactic antibiotics until at least 
2 weeks after vaccination. 
Participants must carry the Participant 
Safety Card dispensed at the Day 1 
Visit at all times to promote rapid 
recognition of any potential signs or 
symptoms of infection. 
Seizure 
Convulsions and/or 
electroencephalogram 
abnormalities have been 
observed during nonclinical 
repeat dose toxicology studies. 
Refer to Section 4.3 for 
information on the safety 
margin. 
Participants with history of seizures are 
excluded. Procedures specified in 
Section 10.7 are to be followed if a 
suspected seizure occurs. 

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Table 5: Potential Risks and Mitigation Strategies 
Potential Risk of Clinical 
Significance 
Summary of Data/Rationale 
for Risk 
Mitigation Strategy 
Other 
Pregnancy exposure or 
lactation 
No studies of ALXN2050 have 
been conducted in pregnant 
women. There are no data 
available on excretion of 
ALXN2050 in breast milk. 
Pregnancy testing will be conducted as 
specified in the Schedule of Activities 
(SoA; Section 1.3). A negative serum 
pregnancy test (Screening Visit) and a 
negative urine pregnancy test (Day 1) 
are required prior to randomization. 
If a pregnancy is reported during the 
study, safety follow-up will be 
performed (Section 10.5.3). 
Pregnant or nursing women are 
excluded from participating in this 
clinical study. Participants and their 
spouses/partners must use a highly 
effective method of contraception 
during the study and for a period of 
30 days following the final dose of 
study intervention.  
2.3.1.1. 
Coronavirus Disease 2019 
The coronavirus disease 2019 (COVID-19) pandemic is active in many countries at the time of 
this protocol amendment. Given this unique circumstance, specific consideration has been given 
to the risks and benefits of the study as they relate to COVID-19, and the global and local 
changes that exist as a result of the pandemic. This assessment is described in Section 10.9. 
2.3.2. 
Benefit Assessment 
Potential benefits include: 
• Targeted therapy with a new treatment for gMG 
• More frequent routine assessments/procedures (eg, physical examinations and vital 
signs assessments) at prespecified in-clinic study visits 
2.3.3. 
Overall Benefit: Risk Conclusion 
Considering the measures taken to minimize risk to participants in this study, the potential risks 
identified in association with ALXN2050 are justified by the anticipated benefits that may be 
afforded to participants with gMG. 
More detailed information about the potential benefits and potential risks of ALXN2050 may be 
found in the IB. 

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3. 
OBJECTIVES AND ENDPOINTS 
Objectives 
Endpoints 
Primary 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
improvement in the MG-ADL total score 
Proportion of participants with an MG-ADL total 
score reduction of ≥ 2 points in any 4 consecutive 
weeks during the first 8 weeks and who did not 
receive rescue therapy 
Secondary 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
improvement in the QMG total score 
• 
Change from baseline in QMG total score at 
Week 8 
• 
Proportion of participants with at least a 3-, 
4-, 5-, 6-, 7-, or 8-point improvement in the 
QMG total score at Week 8 
• 
Proportion of participants with at least a 3-, 
4-, 5-, 6-, 7-, or 8-point improvement in the 
QMG total score in any 4 consecutive weeks 
during the first 8 weeks and who did not 
receive rescue therapy 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
improvement in quality of life measures 
• 
Change from baseline in Neuro-QoL™ Fatigue 
score at Week 8 
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
additional endpoints involving the MG-ADL total 
score 
• 
Change from baseline in MG-ADL total score 
at Week 8 
• 
Proportion of participants with at least a 3-, 
4-, 5-, 6-, 7-, or 8-point improvement in the 
MG-ADL total score in any 4 consecutive 
weeks during the first 8 weeks and who did 
not receive rescue therapy 
• 
Proportion of participants with at least a 2-, 
3-, 4-, 5-, 6-, 7-, or 8-point improvement in 
the MG-ADL total score at Week 8 
PK/PD 
To characterize the PK/PD of ALXN2050 and to 
establish the PK/PD relationship in participants 
with gMG 
• 
Observed Cmax and Ctrough values over time 
• 
Absolute values and change from baseline in 
plasma Bb concentration and serum AP 
activity over time 
Biomarker 
To assess the effect of FD inhibition on 
complement biomarkers 
Plasma FD concentration, serum C3 
concentration, and serum CP activity over time 

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Objectives 
Endpoints 
Safety 
To characterize the overall safety of ALXN2050 
compared with placebo in participants with gMG 
• 
Incidence of TEAEs and TESAEs over time 
• 
Changes from baseline in laboratory 
assessments 
Tertiary/Exploratory  
To assess the efficacy of ALXN2050 compared 
with placebo in the treatment of gMG based on 
other efficacy endpoints 
• 
Proportion of participants with an MG-ADL 
total score reduction of ≥ 2 points and a QMG 
total score reduction of ≥ 3 points in any 
4 consecutive weeks during the first 8 weeks 
and who did not receive rescue therapy 
• 
Proportion of participants with at least a 
2-point improvement in the MG-ADL total 
score for 4 consecutive weeks (measured from 
Day 1 to Week 8 for Groups 1, 2, and 3 and 
from Week 8 to Week 16 for Groups 3a and 
3b) and who did not receive any rescue 
therapy 
• 
Change from baseline in MG-ADL total score 
at Week 8 for Groups 1, 2, and 3; and from 
Week 8 to Week 16 for Groups 3a and 3b 
• 
Change from baseline in MG-ADL total score 
at Week 26 for Groups 1 and 2a; and from 
Week 8 to Week 34 for Groups 3a and 3ba 
• 
Incidence of Clinical Deterioration of gMG 
over times 
• 
MGFA-PIS at Week 8 and Week 26a 
• 
Proportion of participants with a classification 
of Minimal Manifestations at Week 8 and 
Week 26a (as measured by the MGFA-PIS) 
• 
Proportion of participants who receive rescue 
therapy over time 
To assess the effect of FD inhibition on AChR 
antibody titers in participants with gMG 
Change of anti-AChR antibody titers over time 

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Objectives 
Endpoints 
To characterize nongenetic biomarkers in adult 
participants with gMG 
• 
Detection of gMG-associated autoantibodies, 
which may include baseline and/or later 
timepoints (eg, MuSK, LRP4) 
• 
In vitro evaluation of autoantibody activity 
(eg, AChR blocking, complement deposition) 
• 
Absolute values and change from baseline in 
levels of complement proteins and 
complement pathway regulators (eg, C5b-9, 
Properdin) 
• 
Change from baseline in biomarkers of 
inflammation and NMJ damage (eg, 
MMP-10, IL-6) 
a The comparator will be discussed in detail in the Statistical Analysis Plan. 
b Clinical Deterioration is defined in Section 8.2.5. 
Abbreviations: AChR = acetylcholine receptor; AP = alternative pathway; Bb = Bb fragment of complement factor 
B; C3 = complement component 3; C5b-9 = terminal complement complex; Cmax = maximum (peak) plasma 
concentration of the drug; CP = classical pathway; Ctrough = predose concentration; FD = factor D; 
gMG = generalized myasthenia gravis; IL = interleukin; LRP4 = low density lipoprotein receptor-related protein 4; 
MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA-PIS = Myasthenia Gravis Foundation of 
America Post-Intervention Status; MMP-10 = matrix metalloproteinase 10; MuSK = muscle-specific tyrosine 
kinase; Neuro-QoL™ Fatigue = Quality of Life in Neurological Disorders Fatigue questionnaire; 
NMJ = neuromuscular junction; PD = pharmacodynamic; PK = pharmacokinetic; QMG = Quantitative 
Myasthenia Gravis; TEAE = treatment-emergent adverse event; TESAE = treatment-emergent serious adverse 
event 
 

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4. 
STUDY DESIGN 
4.1. 
Overall Design 
This is a Phase 2, randomized, double-blind, parallel-group, placebo-controlled, multicenter 
study to evaluate the efficacy and safety of ALXN2050 in adult participants with gMG. 
Approximately 70 eligible participants will be stratified by MG-ADL total score at baseline 
(5 to 6 [capped to approximately 10% of total enrollment] versus ≥ 7) and randomized on Day 1 
in a 2:1:2 ratio to 1 of 3 treatment groups: ALXN2050 180 mg bid (Group 1), ALXN2050 
120 mg bid (Group 2), or placebo (Group 3). 
Participants will receive the study intervention bid from Day 1 through Week 117. Participants 
may continue to receive a stable regimen of acetylcholinesterase inhibitors (AChEIs), supportive 
IST (with some exceptions as described in Section 6.5.2), and/or corticosteroid therapy that was 
being administered prior to the Screening Visit, but no new AChEIs/ISTs/steroids and no change 
in AChEI/IST/steroid dosages are permitted during the Screening Period, the PEP, or the ETP, 
except for safety reasons as identified by the Investigator. During the OLE Period (ie, after 
34 weeks of treatment), changes in supportive AChEIs/ISTs/steroids can be made at the 
discretion of the Investigator. 
Rescue therapy (eg, plasmapheresis [PP]/plasma exchange [PE], intravenous immunoglobulin 
[IVIg], or high-dose corticosteroid) is allowed at any time for participants who experience a 
protocol-defined Clinical Deterioration of MG (defined in Section 8.2.5). The treatment 
approach for a specific participant should be determined by the Investigator. 
Multiple outcome measures will be administered to evaluate the efficacy and safety objectives. 
In the clinic, assessments should be performed or administered by a properly trained Clinical 
Evaluator (eg, neurologist, neurologist in-training, or delegated member of the investigational 
site staff). 
Table 6: Responsibility for the Clinical Evaluation of gMG 
Study Assessment 
Responsible Study Staff 
MGFA Classification 
Neurologista 
MG-ADL 
Clinical Evaluatorb 
QMG 
Clinical Evaluatorb 
MGFA-PIS 
Neurologista 
Diagnosis of Clinical Deterioration 
Neurologista 
C-SSRS 
Clinical Evaluator 
Neuro-QOL™ Fatigue 
Participant self-assessment 
a Can be an appropriately qualified senior neurology resident in training. 
b Neurologist or appropriately qualified other study team member as delegated by the Investigator, eg, senior 
neurology resident in training, physician assistant, or nurse practitioner. Vital capacity, which is part of the QMG 
assessment, may also be measured by a qualified physical therapist. 
Abbreviations: C-SSRS = Columbia-Suicide Severity Rating Scale; gMG – generalized myasthenia gravis; 
MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA = Myasthenia Gravis Foundation of America; 
MGFA-PIS = Myasthenia Gravis Foundation of America Post-Intervention Status; Neuro-QoL™ 
Fatigue = Neurological Quality of Life Fatigue questionnaire; QMG = Quantitative Myasthenia Gravis score for 
disease severity 

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There will be 4 periods in this study (Figure 1): 
• Screening Period of up to 4 weeks – During this timeframe, participants will present 
to the clinic at least once wherein screening procedures and assessments as indicated 
in the Schedule of Activities (SoA; Section 1.3 [Table 2]) will be performed to 
determine eligibility. The participant may be asked to return to the clinic for 
additional follow-up (eg, blood redraw), although it is not anticipated that this will be 
a frequent occurrence. 
• Primary Evaluation Period of 8 weeks (Day 1 to Week 8) – Treatment during this 
timeframe will be blinded for participants, Investigators, site personnel, and Alexion 
clinical study staff. The participant will present to the clinic every week for the first 
8 weeks for fulfillment of procedures and assessments as specified in the SoA 
(Table 2). For the first visit on Day 1, and after confirmation of eligibility, the 
participant will be randomized to 1 of 3 treatment groups. The participant will be 
provided with sufficient study intervention to last until their next study visit. In the 
clinic, the participant will be administered a dose of study intervention (3 tablets). 
The participant will be instructed to take the second dose of study intervention 
(3 tablets) at home. The participant will also be dispensed the safety card that 
discusses some of the risks associated with treatment, and steps to take in the event of 
an emergency. The participant must be instructed to carry the safety card at all times. 
The last visit for the PEP will be the Week 8 Visit. 
• Extended Treatment Period of 26 weeks (Week 8 to Week 34) – The ETP begins at 
the Day 57 (Week 8) Visit after all assessments of the visit are performed, but before 
the administration of ALXN2050 in the clinic and postdose PK/PD sampling. During 
this timeframe, participants in the ALXN2050 180 mg bid and ALXN2050 120 mg 
bid groups will continue taking the dose to which they are randomized. Participants in 
the placebo group will be stratified by MG-ADL total score at baseline (pre-placebo) 
and re-randomized in a 1:1 ratio to either ALXN2050 180 mg bid (Group 3a) or 
ALXN2050 120 mg bid (Group 3b). All participants will receive active study 
intervention; however, the actual dosage of ALXN2050 will be blinded to 
participants, Investigators, and site personnel. Visits at Weeks 9, 10, 11, 13, 14, and 
15 will be conducted via telephone contact (Table 3). Participants will present for 
in-clinic visits at Weeks 12, 16, 26, and 34. The first dose of study intervention 
during in-clinic visit days will be administered by the site personnel. The participant 
will take the second dose of study intervention at home. The last visit for the ETP will 
be the Week 34 Visit. 
• Open-label Extension Period of up to approximately 1.5 years (Week 34 to 
Week 117) – The OLE Period begins at the Day 239 (Week 34) Visit after all 
assessments of the visit are performed, but before the administration of ALXN2050 in 
the clinic and postdose pharmacokinetics/pharmacodynamics (PK/PD) sampling. 
During this timeframe, all participants will receive active study intervention. If an 
optimal dose of ALXN2050 has been identified, all participants will be switched to 
this optimal dose, as long they have completed the first 34 weeks of treatment. 
However, the actual dose of ALXN2050 will continue to be blinded to participants, 
Investigators, and site personnel during this study period until they are switched to the 

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optimal dose, if one is identified during the study. Participants will return to the clinic 
approximately every 3 months as indicated in the SoA (Table 4). The first dose of 
study intervention during in-clinic visit days will be administered by the site 
personnel. The participant will take the second dose of study intervention at home. 
The last visit for the OLE Period is the EOS Visit. 
An EOS Visit will occur 30 (±2) days after the last dose of study intervention for all participants. 
The overall study duration for an individual participant will be approximately 125 weeks (from 
the Screening Visit through the EOS Visit). 
4.2. 
Scientific Rationale for Study Design 
Justification of specific study design elements is discussed in Table 7. 
Table 7: Scientific Rationale for the Design of Study ALXN2050-MG-201 
Design Element 
Rationale 
Target population  
o There are few available approved treatments 
for gMG. ALXN2050 has the potential to 
address an unmet need by providing a 
convenient, oral treatment option for 
patients with gMG, irrespective of disease 
severity. 
Randomized, double-blind, placebo-controlled 
Primary Evaluation Period (PEP) 
o A randomized, double-blind 
placebo-controlled study or study period 
(eg, PEP) facilitates the unbiased evaluation 
of the efficacy and safety/tolerability of an 
intervention and can thereby establish a 
cause-and-effect relationship between the 
administration of an intervention and 
improved clinical outcomes  
(Vamvakas, 1997). 
Selection of 2 dose levels (ALXN2050 180 mg bid 
and ALXN2050 120 mg bid) 
o Multiple dosage regimens of up to 200 mg 
bid have been evaluated in a healthy 
volunteer study and were noted to be well 
tolerated with sustained PD activity. A 
primary goal of Study ALXN2050-MG-201 
is to identify the dosage regimen that will 
provide the best benefit-risk balance in 
participants with gMG. 
Primary endpoint (MG-ADL) 
o MG-ADL is a validated instrument that is 
used to assess MG disease severity over 
time. A 2-point improvement in the total 
score (ie, decrease in 2 points at any time 
point compared to baseline) indicates 
clinically significant improvement. 

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Table 7: Scientific Rationale for the Design of Study ALXN2050-MG-201 
Design Element 
Rationale 
Secondary endpoints 
o QMG is a scoring system considered to be 
an objective evaluation of MG signs and is 
based on quantitative testing of sentinel 
muscle groups. 
o Neuro-QoL™ Fatigue questionnaire assesses 
the extent of participant fatigue over time. 
Fatigue is a common complaint amongst 
patients with MG which adversely impacts 
quality of life. 
PK/PD and exposure-response analysis 
o The PD biomarkers selected for evaluation 
during this study are appropriate based on 
the mechanism of action of ALXN2050, in 
which factor D inhibition results in 
attenuation of the alternative pathway of the 
complement system. Factor B binds to C3b 
(C3bB complex) and is cleaved by 
complement Factor D into Ba and Bb 
fragments. Bb remains bound to C3b and 
becomes C3 convertase (C3bBb), which 
amplifies the alternative complement 
pathway. 
o The exposure-response analysis will be 
performed to evaluate the PK/PD 
relationship and to determine the 
appropriate Phase 3 dose. 
Safety endpoints 
o Safety endpoints are included in order to 
actively assess risk and ensure the safety of 
participants in the study. 
Duration of study 
o Given the expected rapid onset of action of 
ALXN2050, as well as observations of the 
timing of clinical improvement in prior MG 
studies (both with complement inhibitors 
and medications utilizing other mechanisms 
of action), the 8-week PEP is an adequate 
timeframe for collection of efficacy data 
which will enable determination of a 
treatment effect of ALXN2050 compared 
with placebo to demonstrate 
proof-of-concept. 
o Additionally, the PEP was planned for 
8 weeks as a consideration to participants 
receiving placebo who may benefit from 
direct treatment with active study 
intervention at an earlier time point. 

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Table 7: Scientific Rationale for the Design of Study ALXN2050-MG-201 
Design Element 
Rationale 
o The ETP and OLE Period will facilitate 
collection of longitudinal efficacy and 
additional safety data of ALXN2050 for all 
participants. 
Abbreviations: Ba = Ba fragment of complement factor B; Bb = Bb fragment of complement factor B; bid = twice 
daily; C = complement component; ETP = Extended Treatment Period; gMG = generalized myasthenia gravis; 
MG = myasthenia gravis; MG-ADL = Myasthenia Gravis Activities of Daily Living; MGFA = Myasthenia Gravis 
Foundation of America; Neuro-QoL™ Fatigue = Neurological Quality of Life Fatigue questionnaire; 
OLE = Open-label Extension; PD = pharmacodynamic; PK = pharmacokinetic; QMG = Quantitative Myasthenia 
Gravis score for disease severity 
4.3. 
Justification for Dose 
Clinical PK and PD data have been generated for ALXN2050 in single ascending and multiple 
ascending dose studies in healthy volunteers (Studies ACH228-001 and ACH228-002, 
respectively). In these Phase 1 healthy volunteer studies, ALXN2050 PK exposures increased 
dose-proportionally following single doses and in a greater than dose-proportional manner 
following multiple doses at steady state over the dose range of 40 mg bid to 200 mg bid. 
Corresponding PD activity as determined by AP inhibition in the AP Wieslab assay increased 
with increasing exposure. 
In the multiple-dose Study ACH228-002, the dosage regimens of both 120 mg bid and 
200 mg bid were safe and effective, showing an approximately 10-fold safety margin or greater 
in both maximum plasma concentration (Cmax) and the area under the concentration-time curve 
from time zero to 24 hours (AUC0-24) over the exposures achieved at the 
no-observed-adverse-effect-level (NOAEL) from nonclinical chronic toxicology studies (see IB). 
In addition, both dosage regimens provided complete (> 90%) and sustained inhibition of AP 
activity throughout the 12-hour dosing interval. Therefore, 120 mg bid is selected as the 
minimum therapeutic dosage. 
However, large variabilities were observed in the PK and PD data and in the established PK/PD 
relationship. Intersubject variability in PK and the PK/PD relationship indicated that a dosage 
higher than 120 mg bid, such as 180 mg bid, may be required to ensure more participants reach 
and maintain an ALXN2050 concentration above the threshold for 90% AP inhibition. 
The relationship between exposure and response (AP activity inhibition) has not been established 
specifically in participants in gMG. Therefore, one of the objectives of this study is to develop 
the exposure-response relationship in this target population and evaluate the dose that can 
consistently achieve > 90% AP inhibition at trough steady-state concentrations. Inclusion of the 
120 mg bid group is needed to fully characterize this exposure-response relationship among 
participants with gMG to inform Phase 3 dose selection. Study ALXN2050-MG-201 is designed 
to explore the utility of both the 120 mg bid and the 180 mg bid dosage regimens to fully 
characterize the PK, PD, biomarker, efficacy, and safety data in participants with gMG. 
4.4. 
End of Study Definition 
A participant is considered to have completed the study if: 

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• The participant has completed all periods of the study including the last visit of the 
OLE Period, or 
• In the event the study is stopped early, the participant has completed all applicable 
periods of the study, including the EOS Visit, or 
• The participant completes the study early (and completes the EOS Visit) because the 
study intervention is registered or approved (in accordance with country-specific 
regulations). 
The EOS is defined as the date of the last visit of the last participant for any protocol-related 
activity in the study (SoA; Section 1.3). 

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5. 
STUDY POPULATION 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also known as 
protocol waivers or exemptions, is not permitted. 
5.1. 
Inclusion Criteria 
A participant must meet all inclusion criteria to be eligible to participate in the study. 
Age 
1. Participant must be at least 18 years of age at the time of signing the informed consent 
form (ICF). 
Type of Participant and Disease Characteristics 
2. Diagnosed with MG at least 3 months (90 days) prior to the date of the Screening Visit. 
Confirmation of MG must be made via the following: 
a. Positive serologic test for anti-AChR antibodies at the Screening Visit, and 
b. Abnormal neuromuscular transmission demonstrated by single fiber 
electromyography or repetitive nerve stimulation, or 
c. Positive response to an AChEI test (eg, edrophonium chloride test), or 
d. Improvement of signs or symptoms related to MG during treatment with an oral 
AChEI, as determined by the treating physician 
3. Myasthenia Gravis Foundation of America Clinical Classification Class II to IV at the 
Screening Visit. 
4. MG-ADL total score must be ≥ 5 (with at least 50% of the score attributed to non-ocular 
elements) at the Screening Visit and at randomization (Day 1). 
Note: Enrollment of participants with MG-ADL total score < 7 will be limited to 
approximately 10% of the total enrollment. 
5. Participants receiving treatment with any of the following must have been receiving 
treatment and on a stable dose for the time periods specified below prior to the date of the 
Screening Visit, with no changes to the regimen expected during screening, the PEP, 
and/or the ETP: 
Medication Name/Drug Class Name 
Dosage Regimen Required Prior to the 
Screening Visit 
AZA 
≥ 6 months (180 days) on the medication, with a 
stable dose for ≥ 2 months (60 days) 
Other immunosuppressive therapies, such as 
MMF, MTX, or cyclophosphamide 
≥ 3 months (90 days) on the medication, with a 
stable dose for ≥ 1 month (30 days) 
Corticosteroids (oral), maximum dose 20 mg/day 
prednisone or equivalent 
stable dose for ≥ 4 weeks (28 days) 
Acetylcholinesterase inhibitorsa 
stable dose for ≥ 2 weeks (14 days) 

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Note: If a participant has recently discontinued any of the above medications, a period of time equal to the stable 
dose requirement listed above for that medication (eg, ≥ 2 months for AZA or ≥ 4 weeks for corticosteroids) must 
have passed prior to the first day of the Screening Period. 
a As needed or intermittent acetylcholinesterase inhibitor use is not permitted at any point during the study. 
Abbreviations: AZA = azathioprine; MMF = mycophenolate mofetil; MTX = methotrexate 
Sex 
6. Male or female participant. 
7. Female participants of childbearing potential and male participants must follow 
protocol-specified contraception guidance (Section 10.5.2). 
Informed Consent 
8. Capable of giving signed informed consent as described in Section 10.1.3, which includes 
compliance with the requirements and restrictions listed in the ICF and in this protocol. 
Other Inclusions 
9. Vaccinated against meningococcal infection (Neisseria meningitidis) within 3 years prior 
to, or at the time of, randomization (Day 1). 
Participants who initiate study intervention less than 2 weeks after receiving a 
meningococcal vaccine must receive appropriate prophylactic antibiotics until at least 
2 weeks after the vaccination against N meningitidis. 
5.2. 
Exclusion Criteria 
A participant will be excluded from the study if any exclusion criteria are satisfied. 
Medical Conditions 
1. Any medical condition (eg, cardiac, pulmonary, renal, oncologic, or psychiatric) that, in 
the opinion of the Investigator or the Medical Monitor, might interfere with participation 
in the study, pose any added risk to the participant, or confound the assessment of the 
participant. 
2. History of thymectomy, thymomectomy, or any other thymic surgery within 12 months 
prior to the Screening Visit. 
3. Any untreated thymic malignancy, carcinoma, or thymoma. 
Participants with a history of treated thymic malignancy or carcinoma are eligible for 
enrollment if they meet the following conditions: 
a. Treatment completed > 5 years prior to the Screening Visit 
b. No known recurrence within the 5 years prior to the Screening Visit 
c. No radiological indication of recurrence in a computed tomography (CT) or magnetic 
resonance imaging (MRI) scan, including administration of IV contrast, performed 
within 6 months of randomization (Day 1) 
Participants with a history of treated benign thymoma are eligible if they meet the 
following conditions: 
d. Histopathological or equivalent records indicating the diagnosis of benign thymoma 

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e. Treatment completed > 12 months prior to the Screening Visit 
f. No known recurrence within the 12 months prior to the Screening Visit 
g. No radiological indication of recurrence in a CT or MRI scan, including 
administration of IV contrast, performed within 6 months of randomization (Day 1) 
h. If adequate records confirming the diagnosis of benign thymoma are not available, 
the participant must satisfy the eligibility criteria for thymic malignancy or carcinoma 
stated above. 
Thymomas classified as ≤ Stage II according to the Masaoka Staging System are 
considered benign; thymomas classified as ≥ Stage III are considered malignant 
(Detterbeck, 2014; Masaoka, 2010). 
4. Clinical features that, in the opinion of the Investigator, are consistent with 
Clinical Deterioration of MG at the time of the Screening Visit or at any time during the 
Screening Period prior to randomization (Day 1). 
5. History of seizure. 
6. History of N meningitidis infection. 
7. Evidence of human immunodeficiency virus (HIV antibody positive) infection at the 
Screening Visit. 
8. History of hypersensitivity to any ingredient contained in the study intervention. 
9. Known or suspected history of drug or alcohol abuse or dependence within 1 year prior to 
the Screening Visit. 
10. Evidence of hepatitis B (hepatitis B positive hepatitis surface antigen [HbsAg] or positive 
hepatitis B core antibody [anti-HBc]) with negative surface antibody [anti-HBs] or 
hepatitis C viral infection (hepatitis C virus [HCV] antibody positive, except for patients 
with documented successful treatment and documented sustained virologic response 
[SVR]) at Screening. 
11. History of malignancy within 5 years of the Screening Visit, with the exception of 
nonmelanoma skin cancer or carcinoma in situ of the cervix that has been treated with no 
evidence of recurrence. 
12. History of persistent or recurrent infections prior to the Screening Visit. 
13. Active systemic bacterial, viral, or fungal infection within 14 days prior to study 
intervention administration on Day 1. 
14. Presence of fever as documented by a temperature ≥ 38°C (100.4°F) within 7 days prior 
to administration of study intervention on Day 1. 
15. History or presence of any risk factors for Torsades de Pointes (eg, heart 
failure/cardiomyopathy or family history of Long QT Syndrome), a screening QT interval 
corrected using Fridericia's formula (QTcF) > 450 msec for males and > 470 msec for 
females, or receiving medications known to significantly increase the corrected QT 
interval (QTc). 
16. Laboratory abnormalities at the Screening Visit, including: 
a. Alanine aminotransferase > 2 × the upper limit of normal (ULN) 

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b. Direct bilirubin > 2 × ULN 
17. Estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m2 and/or are on dialysis. 
18. Any other clinically significant laboratory abnormality that, in the opinion of the 
Investigator, would make the participant inappropriate for the study or put the participant 
at undue risk. 
Prior/Concomitant Therapy 
19. Use of the following within the time periods specified below: 
a. IVIg or subcutaneous immunoglobulin (SCIg) within the 4 weeks (28 days) prior to 
the Screening Visit 
b. Use of PE and PP within the 4 weeks (28 days) prior to the Screening Visit 
c. Use of rituximab within the 6 months (180 days) prior to the Screening Visit 
d. Use of tacrolimus or cyclosporine within the 4 weeks (28 days) prior to the Screening 
Visit 
20. Any previous or current treatment with complement inhibitors (eg, eculizumab, 
ravulizumab). 
21. Use of known cytochrome P450, family 3, subfamily A (CYP3A) sensitive substrates, 
moderate or strong CYP3A inducers, and/or moderate or strong CYP3A inhibitors from 
2 weeks or 5 half-lives, whichever is longer, prior to the first administration of study 
intervention on Day 1 (randomization) (full list provided in Table 13). 
22. Use of selected medications known to lower the seizure threshold and/or cause seizure 
(full list provided in Section 10.11). 
23. Current treatment with a biologic medication that may affect immune system functioning 
or has stopped treatment with a biologic medication that may affect immune system 
functioning, and 5 terminal half-lives of the biologic medication have not elapsed by the 
time of the Screening Visit. Participants receiving prior treatment with an FcRn inhibitor 
≥ 5 half-lives before the Screening Visit may be enrolled but the total immunoglobulin G 
(IgG) level must be above the lower limit of normal (LLN) before these participants can 
be randomized. 
Prior/Concurrent Clinical Study Experience 
24. Participation in another interventional treatment study or use of any experimental therapy 
within 30 days before the Screening Visit or within 5 half-lives of the study intervention, 
whichever is greater. 
Other Exclusions 
25. Pregnant, breastfeeding, or intending to conceive during the course of the study. 
26. Inability to travel to the clinic for specified visits or fulfill the logistical requirements of 
study intervention administration. 
27. Planned surgical procedure during the course of the study. 

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5.3. 
Lifestyle Considerations 
5.3.1. 
Medications 
If a participant is taking a cholinesterase inhibitor, the dose must be withheld for at least 8 hours 
prior to the QMG assessment at time points presented in the SoA (Section 1.3). 
5.3.2. 
Meals and Dietary Restrictions 
Certain foods such as grapefruit have been shown to be inhibitors of CYP3A4 enzyme activity. 
Participants should refrain from consuming these foods and beverages from 2 weeks prior to the 
first administration of study intervention on Day 1 (randomization) until 2 weeks after the final 
dose of study intervention. 
5.4. 
Screen Failures 
Screen failures are defined as participants who consent to participate in the clinical study but are 
not subsequently randomized. A minimal set of screen failure information is required to ensure 
transparent reporting of screen failure participants to meet the Consolidated Standards of 
Reporting Trials publishing requirements and to respond to queries from regulatory authorities. 
Minimal information includes demography, screen failure details (eg, failed eligibility criteria), 
and any adverse events (AEs), including any serious adverse events (SAEs) and any related 
concomitant medication, occurring during the Screening Period. 
Individuals who do not meet the criteria for participation in this study (screen failure) due to a 
reason that is expected to resolve, or has resolved, may be rescreened based on discussion and 
agreement between the Investigator and the Medical Monitor. 

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6. 
STUDY INTERVENTION 
Study intervention is defined as any investigational intervention(s), marketed product(s), 
placebo, or medical device(s) intended to be administered to a study participant according to the 
study protocol. 
6.1. 
Study Intervention(s) Administered 
• ALXN2050 drug product will be provided as tablets that are manufactured using a 
common blend. 
− The 60 mg formulation will be used in Study ALXN2050-MG-201. 
• Matching placebo will be manufactured in the same fashion, without the active 
ingredient. ALXN2050 and placebo tablets will be identical in appearance. 
• The participant will be provided with sufficient study intervention to last until their 
next study visit. Additional details will be provided in the interactive response 
technology (IRT) manual. 
• In order to maintain the study blind for participants, Investigators, and site personnel, 
each of the 2 daily doses will consist of 3 tablets that in combination correspond to 
the assigned treatment group. 
− 180 mg: three 60 mg tablets 
− 120 mg: two 60 mg tablets and one placebo tablet 
− Placebo: 3 placebo tablets 
• During in-clinic visits, the participant will be administered the first dose of study 
intervention. The second dose of study intervention is to be taken at home. Whether 
in the clinic or at home, the timing of administration should be consistent. 
• In the event of a missed dose, the participant should be instructed to take the study 
intervention within 6 hours of the originally scheduled time. If more than 6 hours 
have passed, the missed dose should be skipped. In either scenario, the next dose 
should be taken according to the original dosing schedule. 
The specific details of study intervention are presented in Table 8. 

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Table 8: Study Intervention 
Study Intervention Name 
ALXN2050 (Formerly 
ACH-0145228) 
Placebo 
Dose formulation 
tablet 
tablet 
Unit dose strength(s) 
60 mg 
NA 
Dose level(s) and frequency 
120 mg bid or 180 mg bid 
bid 
Route of administration 
oral 
oral 
IMP or AxMP 
IMP 
IMP 
Sourcing 
Alexion Pharmaceuticals, Inc. 
Alexion 
Pharmaceuticals, Inc. 
Abbreviations: AxMP = auxiliary medicinal product; bid = twice daily; IMP = investigational medicinal product; 
NA = not applicable 
6.1.1. 
Study Intervention(s) Packaging and Labeling 
Study intervention will be provided in tamper-proof containers that will be labeled according to 
country-specific regulations. At a minimum, the container will be labeled with: 
• The protocol number 
• Lot number/expiry date 
• Alexion name and address 
• Instructions for use and storage 
6.1.2. 
Optional Dosing eDiary Tool 
Participants will be provided with an optional dosing eDiary tool which is to be used as a 
reminder for taking the assigned study intervention throughout the duration of the study. 
Participants are advised to enter the date on which the assigned study treatment is scheduled and 
mark the chart each time the morning and evening dose is taken. As this is an optional tool, there 
will be no collection of data either by Alexion or the Investigator’s site (ie, it will not be used for 
study intervention accountability). 
6.2. 
Preparation/Handling/Storage/Accountability 
6.2.1. 
Preparation 
The study intervention will be provided by Alexion; therefore, no specific preparation 
instructions are required. 
6.2.2. 
Storage and Handling 
• Study intervention must be stored in the containers as provided at 15ºC to 30ºC. 
Participants should be instructed to keep their study medications in the original 
container at room temperature at home. 

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• Study intervention will be shipped directly to each investigational site. When the 
medication is stored at the investigational site, the Investigator or designee must 
confirm appropriate temperature conditions have been maintained during transit (a 
temperature monitor will accompany each shipment) for all study intervention 
received and that any discrepancies are reported and resolved before dispensation and 
use of the study intervention. 
• Only participants enrolled in the study may receive the study intervention and only 
authorized site staff may supply or administer the study intervention. When the 
medication is stored at the investigational site, all study intervention must be stored in 
a secure, environmentally controlled, and monitored (manual or automated) area in 
accordance with the labeled storage conditions with access limited to the Investigator 
and authorized site staff. 
6.2.3. 
Accountability and Disposal 
• The Investigator, institution, or the head of the medical institution (where applicable) 
is responsible for study intervention accountability, reconciliation, and record 
maintenance (ie, receipt, reconciliation, and final disposition records). 
− This responsibility includes the reporting of any temperature excursions and 
product complaints to AlexionIMPTE@alexion.com and 
productcomplaints@alexion.com within 1 business day of awareness. 
A product complaint is defined as any written, electronic, or oral communication 
that alleges deficiencies related to the identity, quality, durability, reliability, 
usability, safety, effectiveness, or performance of a product or clinical study 
material and/or its packaging components after it is has been released for 
distribution to an end customer that affects the performance of such product. 
• The pharmacist or other designated individual will maintain records of study 
intervention delivered to the study site, the inventory at the study site, the distribution 
to and use by each participant, and the return of materials to the Sponsor for storage 
or disposal/destruction of materials at the study site. These records should include 
dates, quantities, batch/serial numbers, expiration dates, in-clinic temperature log, and 
unique code numbers assigned to the study intervention and study participants. 
• The Investigator will maintain records that adequately document that the participants 
were administered the correct study treatment kits and reconcile the products received 
from the drug dispensing center. Investigational product will not be returned to the 
Sponsor or disposed of until accountability has been fully monitored. 
Further guidance regarding preparation, handling, storage, and accountability and information 
for the final disposition of unused study intervention is provided in the Pharmacy Manual. 

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6.3. 
Measures to Minimize Bias: Randomization and Blinding 
6.3.1. 
Randomization 
All participants will be randomized on Day 1 in a ratio of 2:1:2 to ALXN2050 180 mg bid, 
ALXN2050 120 mg bid, or placebo, using a centralized IRT after the Investigator has verified 
that they are eligible to participate in the study (Section 4.1). 
6.3.2. 
Blinding 
All investigational site personnel, Alexion staff/designees, other staff directly associated with the 
conduct of the study, and all participants will be blinded to the treatment assignment during the 
PEP. The double-blind will be maintained by using identical study treatment kits and labels for 
all participants. The placebo tablet will have an identical appearance to that of ALXN2050. The 
randomization code will be maintained by the IRT provider. Select Alexion staff will be 
unblinded for the analyses of the PEP and will remain unblinded during the ETP and OLE. All 
participants, Investigators, and site personnel will remain blinded to treatment assignment from 
Day 1 through the end of the ETP (ie, Week 34). During the ETP, participants, Investigators, and 
site personnel will be informed that all participants are on active treatment but will remain 
blinded to the actual dose. After 34 weeks (ie, during the OLE Period), participants, 
Investigators, and site personnel will continue to be blinded to the actual dose received until an 
optimal dose is chosen (if this occurs during the study). If an optimal dose is chosen, then all 
participants will be moved to that dose, and participants, Investigators, and site personnel will no 
longer be blinded to treatment assignment/dose. 
In case of an emergency, the Investigator has the sole responsibility for determining if 
unblinding of a participant’s intervention assignment is warranted. Participant safety must 
always be the first consideration in making such a determination. If the Investigator decides that 
unblinding is warranted, the Investigator will be able to unblind the participant’s treatment 
allocation directly using the IRT. If a participant’s intervention assignment is unblinded, Alexion 
or designee must be notified within 24 hours after breaking the blind. The date and reason that 
the blind was broken must be recorded in the source documentation and case report form (CRF), 
as applicable. 
In the event of a suspected unexpected serious adverse reaction (SUSAR), follow reporting 
guidance in Section 8.3.4. The blind will be maintained for persons responsible for the ongoing 
conduct of the study (eg, Monitors, Investigators) and those responsible for data analysis and 
interpretation of results, such as biometrics personnel. 
Unblinded information will only be accessible to those who are involved in safety reporting to 
Health Authorities, Independent Ethics Committees (IECs), and/or Institutional Review Boards 
(IRBs). 
Investigators will receive only blinded information unless unblinded information is judged 
necessary for safety reasons. 
6.4. 
Study Intervention Compliance 
When participants are dosed at the investigational site, they will receive study intervention 
directly from the Investigator or designee, under medical supervision. The date and time of each 

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dose administered in the clinic will be recorded in the source documents and recorded in the 
electronic case report form (eCRF). 
When participants self-administer study intervention at home, compliance with the study 
intervention will be assessed by direct questioning and counting of returned tablets during the 
next in-clinic visit and recorded in the source documents. Deviation(s) from the prescribed 
dosage regimen should be recorded in the eCRF. 
A record of the quantity of study intervention dispensed and administered to/taken by each 
participant must be maintained and reconciled with study intervention records provided to the 
investigational site. Data from the optional dosing eDiary tool is NOT to be considered a source 
document nor to be used as record for reconciliation of study intervention. Intervention start and 
stop dates, including dates for planned and unplanned intervention delays will also be recorded 
in the eCRF. 
6.5. 
Prior and Concomitant Therapies 
Any medication (including over-the-counter or prescription medicines, vitamins, and/or herbal 
supplements) or vaccine that the participant is receiving at the time of enrollment or receives 
during the study must be recorded along with: 
• Reason for use 
• Dates of administration, including start and end dates 
• Dosage information including dose and frequency 
Nonpharmacologic treatments and therapies that the participant receives during the clinical study 
must be recorded along with: 
• Reason for use 
• Dates of administration, including start and end dates 
• Diagnostics administered, if applicable 
• Whether the treatment is ongoing 
The Medical Monitor should be contacted if there are any questions regarding concomitant or 
prior therapy. 
6.5.1. 
Allowed Medications and Therapy 
Participants receiving treatment with any of the medications listed in Table 9 must have been 
receiving treatment and on a stable dose for the time periods specified prior to the date of the 
Screening Visit. 
 

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Table 9: Allowed Medications and Therapies 
Medication Name/Drug Class 
Name 
Dosage Regimen Required Prior to the Screening Visit 
AZA 
≥ 6 months (180 days) on the medication, with a stable dose for 
≥ 2 months (60 days) 
Other immunosuppressive 
therapies, such as MMF, MTX, or 
cyclophosphamide 
≥ 3 months (90 days) on the medication, with a stable dose for 
≥ 1 month (30 days) 
Corticosteroids (oral), maximum 
dose 20 mg/day prednisone or 
equivalent 
stable dose for ≥ 4 weeks (28 days) 
Acetylcholinesterase inhibitorsa 
stable dose for ≥ 2 weeks (14 days) 
Note: If a participant has recently discontinued any of the above medications, a period of time equal to the stable 
dose requirement listed above for that medication (eg, ≥ 2 months for AZA or ≥ 4 weeks for corticosteroids) must 
have passed prior to the first day of the Screening Period. 
a As needed or intermittent acetylcholinesterase inhibitor use is not permitted at any point during the study. 
Abbreviations: AZA = azathioprine; MMF = mycophenolate mofetil; MTX = methotrexate 
During the Screening, PEP, and ETP Periods, any stable regimen of AChEI, supportive ISTs, 
and/or corticosteroid therapy must not be discontinued or have a change in dose, and new 
AChEI, ISTs, and/or corticosteroid therapy must not be added, unless deemed medically 
necessary by the Investigator in order to maintain patient safety. During the OLE Period, changes 
in supportive AChEIs/ISTs/steroids can be made at the discretion of the Investigator. 
Other concomitant medications used in the treatment of gMG may be considered on a 
case-by-case basis by the Investigator in consultation with the Medical Monitor. 
6.5.2. 
Disallowed Medications and Therapy 
The following medications and therapies are prohibited during the study: 
• Known CYP3A sensitive substrates, moderate or strong CYP3A inducers, and/or 
moderate or strong CYP3A inhibitors are prohibited throughout the study, until 
1 week after the final administration of study intervention (see Table 13 for a full list 
of these medications) 
• IVIg or SCIg as maintenance therapy (this is allowed acutely in the setting of a 
Clinical Deterioration of MG) 
• PE/PP as maintenance therapy (this is allowed acutely in the setting of a Clinical 
Deterioration of MG) 
• Rituximab 
• Tacrolimus or cyclosporine 
• Other complement inhibitors 
• Biologic medications that may affect immune system functioning 

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• Experimental interventions or therapies 
• Selected medications known to lower the seizure threshold and/or cause seizure (full 
list provided in Section 10.11) 
• Medications known to significantly prolong the QTc 
6.5.3. 
Rescue Medicine 
Participants who experience Clinical Deterioration of MG (defined in Section 8.2.5) during the 
study may be administered rescue therapy (ie, high-dose corticosteroid, PE/PP, or IVIg) at the 
discretion of the Investigator. Alexion or designee should be notified within 24 hours of 
initiation of treatment with rescue therapy. 
The name, date, and time of the dosage regimen will be recorded on the participant’s eCRF. 
Participants who require rescue medication may continue in the study at the discretion of the 
Investigator. 
6.5.4. 
Vaccine and Antibiotic Prophylaxis 
To mitigate the potential risk of meningococcal infection, all participants must be vaccinated 
within 3 years prior to, or at the time of, initiating the study intervention. Vaccines against 
serotypes A, C, Y, W135, and B, where available, are recommended to prevent common 
pathogenic meningococcal serotypes. Participants who initiate study intervention treatment less 
than 2 weeks after receiving a meningococcal vaccine must receive treatment with appropriate 
prophylactic antibiotics until at least 2 weeks after vaccination. 
Participants must be vaccinated or revaccinated according to current national vaccination 
guidelines or local practice for vaccination use with complement inhibitors. Vaccination may not 
be sufficient to prevent meningococcal infection. All participants should be monitored for early 
signs of meningococcal infection, evaluated immediately if infection is suspected, and treated 
with appropriate antibiotics, if necessary. 
Any participant without sufficient history of these vaccines may be vaccinated or provided 
boosters per national or local guidelines. 
Participants should be vaccinated or revaccinated against other pathogens according to current 
national vaccination guidelines or local practice for vaccination use as part of standard of care. 
6.6. 
Dose Modification 
Dose modification of the study intervention for an individual participant is not permitted. 
If the optimal dose of ALXN2050 is determined during the study, all participants who have 
completed at least 34 weeks of treatment and are not already receiving the optimal dose will be 
switched. 
6.7. 
Intervention After the End of the Study 
Upon completion of the last study visit, participants will return to the care of their treating 
physician. 

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7. 
DISCONTINUATION OF STUDY INTERVENTION AND 
PARTICIPANT DISCONTINUATION/WITHDRAWAL 
7.1. 
Discontinuation of Study Intervention 
Participants must be considered for discontinuation from study intervention if any of the 
following occur during the study: 
• Serious hypersensitivity reaction 
• Pregnancy or planned pregnancy (Section 8.2.7) 
• Severe uncontrolled infection 
• Development of seizures (Section 10.7) 
• Use of disallowed medication (defined in Section 6.5.2) 
• Alexion or the Investigator deems it is necessary for the participant 
• Adverse event that would, in the opinion of the Investigator, make continued 
participation in the study an unacceptable risk 
Temporary discontinuation of study intervention is permitted (eg, in the event of an AE); 
however, the Medical Monitor should be notified if this occurs. If the study intervention is 
permanently discontinued, the participant should be discontinued from the study (described in 
Section 7.2). 
All participants should complete an EOS visit 30 (±2) days after the last dose of study 
intervention as specified in the SoA (Section 1.3). 
7.2. 
Participant Discontinuation/Withdrawal from the Study 
• All efforts should be made to ensure participants are willing to comply with study 
participation prior to conducting the screening procedures. 
• The study staff should notify Alexion or designee and their site monitor of all study 
withdrawals as soon as possible. The reason for participant discontinuation must be 
recorded in the source documents and eCRF. 
• A participant may withdraw from the study at any time at his/her own request. 
− If the participant withdraws consent for disclosure of future information, Alexion 
may retain and continue to use any data collected before such a withdrawal of 
consent, if permitted by local requirements. 
− If a participant withdraws from the study, the participant may request destruction 
of any samples taken and not tested, and the Investigator must document this in 
the site study records. 
• A participant can be withdrawn at any time in the best judgment of the Investigator 
for safety, behavioral, compliance, or administrative reasons, such as: 
 Pregnancy or planned pregnancy 

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 Lack of efficacy 
 Participant noncompliance 
 Intercurrent illness that would affect assessment of clinical status to a 
significant degree 
 Unacceptable toxicity (including a clinically significant laboratory value) 
that compromises the participant’s ability to continue study-specific 
procedures 
 Loss of the ability to provide informed consent 
 Any other condition or circumstance that would jeopardize the welfare of 
participants if they were to continue in the study 
• At the time of discontinuing from the study, if possible, an Early Discontinuation 
Visit should be conducted, as shown in the SoA (Section 1.3). Refer to the SoA for 
data to be collected at the time of study discontinuation and follow-up and for any 
further evaluations that need to be completed. 
7.3. 
Lost to Follow-up 
A participant will be considered lost to follow-up if the participant repeatedly fails to return for 
scheduled visits and is unable to be contacted by the study site. 
The following actions must be taken if a participant fails to return to the clinic for a required 
study visit: 
• The site must attempt to contact the participant to reschedule the missed visit as soon 
as possible, counsel the participant on the importance of maintaining the assigned 
visit schedule, and ascertain whether or not the participant wishes to and/or should 
continue in the study. 
• Before a participant is deemed lost to follow-up, the Investigator or designee must 
make every effort to regain contact with the participant (where possible, 3 telephone 
calls and, if necessary, a certified letter to the participant’s last known mailing 
address or local equivalent methods). These contact attempts should be documented 
in the participant’s medical record. 
• Should the participant continue to be unreachable, he/she will be considered lost to 
follow-up. 
Discontinuation of specific sites or of the study as a whole are handled as part of Section 10.1.9. 

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8. 
STUDY ASSESSMENTS AND PROCEDURES 
• Study procedures and their timing are summarized in the SoA (Section 1.3). 
Adherence to the study design requirements, including those specified in the SoA, is 
essential and required for study conduct. 
• Immediate safety concerns should be discussed with Alexion or designee immediately 
upon occurrence or awareness to determine if the participant should continue or 
discontinue study intervention. 
• All screening evaluations must be completed and reviewed to confirm that potential 
participants meet all eligibility criteria. The Investigator will maintain a screening log 
to record details of all participants screened and to confirm eligibility or record 
reasons for screening failure, as applicable. Eligibility, study administrative, and 
screening assessments are further discussed in Section 8.11. 
• Procedures conducted as part of the participant’s routine clinical management 
(eg, blood count) and obtained before signing of the ICF may be utilized for 
screening or baseline purposes provided the procedures met the protocol-specified 
criteria and were performed within the time frame defined in the SoA (Section 1.3). 
• See Section 10.2 for the list of clinical laboratory tests (that will be conducted at a 
central/specialty laboratory). 
8.1. 
Efficacy Assessments 
8.1.1. 
MG-ADL 
The MG-ADL profile is an 8-item participant-reported scale that focuses on relevant symptoms 
and functional performance of ADL in patients with MG. The 8 items of the MG-ADL 
questionnaire were derived from symptom-based components of the original 13-item QMG scale 
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 of MG. In this functional status instrument, 
each response is graded 0 (normal) to 3 (most severe). The MG-ADL total score ranges from 
0 to 24, with higher scores indicating worse function. The recall period for the MG-ADL profile 
is the preceding 7 days or since the last visit if the visit interval is less than 7 days. A 2-point 
change in the MG-ADL total score is considered clinically meaningful. 
The MG-ADL assessment should be administered by a properly trained Clinical Evaluator 
(preferably the same evaluator) throughout the study. It is anticipated that the form should take 
no more than 10 minutes to complete. The MG-ADL is required to be performed first, followed 
by the QMG. 
8.1.2. 
QMG 
The QMG Score for Disease Severity is 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 (Benatar, 2012). The QMG 
instrument 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 

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severe. The QMG total score ranges from 0 to 39, with higher scores indicating more severe 
disease. The QMG assessment should be performed by a properly trained Clinical Evaluator 
(preferably the same evaluator) throughout the study. 
If a participant is taking a cholinesterase inhibitor, the dose must be withheld for at least 8 hours 
prior to the assessment and, whenever possible, the time from the last dose to the QMG 
assessment should be kept similar between visits. 
8.1.3. 
MGFA-PIS 
The gMG clinical state will be assessed using a modified version of the Myasthenia Gravis 
Foundation of America Post-Intervention Status (MGFA-PIS) (Jaretzki, 2000). Change in status 
categories of Improved, Unchanged, or Worse, as well as the minimal manifestation (MM) state 
will be assessed and recorded by the Investigator or the same neurologist skilled in the 
evaluation of participants with gMG throughout the study. The subscores of MM, ie, MM-0, 
MM-1, MM-2, and MM-3, will not be used in this study. 
8.1.4. 
Neuro-QoL™ Fatigue 
The Quality of Life in Neurological Disorders Fatigue questionnaire (Neuro-QoL™ Fatigue) is a 
reliable and validated brief 19-item survey of fatigue, completed by the participant (Cella, 2010). 
Higher scores indicate greater fatigue and greater impact of MG on activities. 
8.2. 
Safety Assessments 
8.2.1. 
Physical Examinations 
• A complete physical examination will include, at a minimum, assessments of the 
cardiovascular, respiratory, musculoskeletal, gastrointestinal, and neurological 
systems. Height and weight will also be measured and recorded. 
• An abbreviated physical examination will be performed, if necessary, on the basis of 
the participant’s health status and the clinical judgment of the Investigator. 
• A symptom-based neurologic examination should be performed if the participant has 
any complaints or clinical findings attributable to the central nervous system, and if 
positive for findings, a full neurologic examination should be performed at that 
assessment time point and at future time points as needed (determined by the 
Investigator). If a full neurologic examination is required, the Investigator should 
perform the following evaluations: 
− Mental status 
− Cranial nerve examination 
− Motor examination 
− Gait examination 
− Coordination examination 
− Sensory examination 

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8.2.2. 
Vital Signs 
• Body temperature, pulse rate, respiratory rate, and systolic and diastolic blood 
pressure (mm Hg) will be assessed. 
• Blood pressure and pulse measurements will be assessed in a supine or seated 
position with a completely automated device. Manual techniques will be used only if 
an automated device is not available. 
• Blood pressure and pulse measurements should be preceded by at least 5 minutes of 
rest for the participant in a quiet setting without distractions (eg, television, cell 
phones). Ideally, the same arm for each participant should be used for measurements. 
• Vital signs (to be taken before blood collection for laboratory tests) will consist of a 
single pulse check and a single blood pressure measurement. 
8.2.3. 
Electrocardiograms 
• A single 12-lead electrocardiogram (ECG) will be performed to obtain heart rate, PR 
interval (time from the onset of the P wave to the start of the QRS complex), 
combination of the Q wave, R wave, and S wave (QRS) interval, interval between the 
start of the Q wave and the end of the T wave (QT), and the QTc. QT interval will be 
corrected for heart rate using Fridericia’s formula. 
• Participants must be supine for approximately 5 to 10 minutes before ECG collection 
and remain supine but awake during ECG collection. 
• The Investigator will be responsible for reviewing the ECG to assess whether the 
ECG is within normal limits and determine the clinical significance of the results. 
• Results will be recorded on the eCRF. Clinically significant findings should be 
recorded on the AE form. 
8.2.4. 
Clinical Safety Laboratory Assessments 
• The Investigator must review the laboratory report, document this review, and record 
any clinically relevant changes occurring during the study in the AE section of the 
eCRF. The laboratory reports must be filed with the source documents. Clinically 
significant abnormal laboratory findings are those which are not associated with the 
underlying disease, unless judged by the Investigator to be more severe than expected 
for the participant’s condition. 
• All laboratory tests with values considered clinically significantly abnormal during 
participation in the study should be repeated until the values return to normal or 
baseline or are no longer considered clinically significant by the Investigator or 
Medical Monitor. 
− If such values do not return to normal/baseline within a period of time judged 
reasonable by the Investigator, the etiology should be identified, and Alexion 
notified. 

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− All protocol-required laboratory assessments, as defined in Section 10.2, must be 
collected in accordance with the Laboratory Manual and the SoA (Section 1.3). 
− Laboratory assessments performed at the institution’s local laboratory that require 
a change in participant management or are considered clinically significant by the 
Investigator must be recorded in the AE or SAE eCRF. When possible, parameter 
values outside of the reference range should be entered in a free-text field. 
• Repeat or unscheduled laboratory tests may be obtained for safety reasons or for 
technical issues with the samples. 
8.2.4.1. 
Virus Serology 
Testing for HIV-1 and HIV-2 is required for all participants prior to enrollment. Participants who 
are HIV antibody positive will not be enrolled. 
Similarly, participants who are positive at the Screening Visit for HbsAg, anti-HBc with negative 
anti-HBs, or HCV antibody positive (except for participants with documented successful 
treatment and documented SVR) will not be enrolled. 
8.2.4.2. 
Urinalysis 
Urine samples will be analyzed for the parameters listed in Section 10.2. A microscopic 
examination of urine samples will be performed if the results of the macroscopic analysis are 
abnormal. 
8.2.4.3. 
Follicle-Stimulating Hormone 
Follicle-stimulating hormone (FSH) may be obtained to confirm postmenopausal status in female 
participants who are considered postmenopausal. A high FSH level in the postmenopausal range 
may be used to confirm a postmenopausal state in women not using hormonal contraception or 
hormone replacement therapy (HRT). 
This test is not needed for men or women of childbearing potential. 
8.2.5. 
Clinical Deterioration of Myasthenia Gravis 
Clinical Deterioration of MG is defined as any of the following: 
• Patients who experience an MG Crisis, which is defined as weakness from MG that is 
severe enough to necessitate intubation or to delay extubation following surgery. The 
respiratory failure is due to weakness of respiratory muscles. Severe bulbar 
(oropharyngeal) muscle weakness often accompanies the respiratory muscle 
weakness, or may be the predominant feature in some patients; or, 
• A score of 3 or a 2-point worsening from baseline on any one of the 
individual MG-ADL items other than double vision or eyelid droop that, in the 
Investigator’s assessment, is associated with significant symptomatic worsening; or,  

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• Administration of rescue therapy for MG to a patient whose, in the opinion of the 
Investigator or Investigator-designated clinician, health would be in jeopardy if 
rescue therapy were not given (eg, emergent situations). 
Alexion or designee should be notified within 24 hours of initiation of treatment with rescue 
therapy for Clinical Deterioration of MG. 
Evaluation of Clinical Deterioration of MG must be performed as soon as possible (ie, within 
48 hours of notification to the Investigator of symptom onset). If a participant experiences 
Clinical Deterioration of MG during a scheduled study visit or presents to the clinic after an 
event of Clinical Deterioration of MG, refer to the SoA (Section 1.3) for assessments/procedures 
to be obtained. Additional tests may be performed in the best judgment of the Investigator. 
8.2.6. 
Suicidal Ideation and Behavior Risk Monitoring 
The National Institute of Neurological Disorders and Stroke in collaboration with regulatory 
agencies have developed a set of common data elements to be considered when implementing 
clinical studies for a neurologic indication (ie, in participants with gMG). 
Participants being treated with study intervention should be monitored appropriately and 
observed closely for suicidal ideation and behavior or any other unusual changes in behavior, 
especially at the beginning and end of the course of intervention, or at the time of dose changes, 
either increases or decreases. Consideration should be given to discontinuing study intervention 
in participants who experience signs of suicidal ideation or behavior, following a risk 
assessment. 
Families and caregivers of participants being treated with study intervention should be alerted 
about the need to monitor participants for the emergence of unusual changes in behavior, as well 
as the emergence of suicidal ideation and behavior, and to report such symptoms immediately to 
the Investigator. 
Baseline assessment of suicidal ideation and behavior/intervention emergent suicidal ideation 
and behavior will be monitored during Study ALXN2050-MG-201 using the Columbia-Suicide 
Severity Rating Scale (C-SSRS). 
There are 2 types of C-SSRS assessments that will be conducted during the study: “C-SSRS at 
Baseline/Screening” and “C-SSRS-Since Last Visit”. The C-SSRS will be performed by the 
Treating Physician or an appropriately trained designee at visits specified in the SoA 
(Section 1.3) to ensure that participants who are experiencing suicidal thoughts or behavior are 
properly recognized and adequately managed or referred for further evaluation. Additional 
C-SSRS assessments will be permitted as needed. 
8.2.7. 
Pregnancy 
A serum or urine pregnancy test will be administered to all female participants of childbearing 
potential. A negative serum pregnancy test at the Screening Visit and a negative urine pregnancy 
test at Day 1 are required in order to be considered eligible to continue in the study. 
Pregnancy data from female participants and female spouses/partners of male participants will be 
collected from the first dose of study intervention and at the time points specified in the SoA 
(Section 1.3). Any female participant who becomes pregnant during the study will be 

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discontinued from the study intervention and withdrawn from the study. If a pregnancy is 
reported, the Investigator must immediately inform Alexion within 24 hours of awareness of the 
pregnancy and follow the procedures outlined in Section 10.5.3. 
8.2.8. 
Participant Safety Card 
Before the first dose of the study intervention, a Participant Safety Card will be dispensed during 
the Day 1 Visit. The safety card is provided to increase participant awareness of the risk of 
meningococcal infections, promote rapid recognition and disclosure of any potential signs or 
symptoms of infection experienced during the course of the study, and to inform participants of 
what actions must be taken if they are experiencing signs or symptoms of an infection. 
At each visit/contact throughout the study, the study staff will ensure that the participant has the 
Participant Safety Card and review the content of the safety card with the participant. 
Participants are required to carry the safety card until 30 days after the final dose of study 
intervention. 
8.3. 
Adverse Events and Serious Adverse Events 
The definitions of AEs and SAEs can be found in Section 10.3. 
All AEs will be reported to the Investigator or qualified designee by the participant (or, when 
appropriate, by a caregiver, surrogate, or the participant’s legally authorized representative). 
The Investigator and any qualified designees are responsible for detecting, documenting, and 
recording events that meet the definition of an AE or SAE and remain responsible for following 
up AEs that are serious, considered related to the study intervention or study procedures, or that 
caused the participant to discontinue the study intervention (see Section 7). 
Procedures for recording, evaluating, follow-up, and reporting AEs and SAEs are outlined in 
Section 10.3. 
8.3.1. 
Time Period and Frequency for Collecting AE and SAE Information 
All AEs and SAEs will be collected from the signing of the ICF at the time points specified in 
the SoA (Section 1.3). 
All SAEs will be recorded and reported to Alexion immediately and under no circumstance 
should this exceed 24 hours, as indicated in Section 10.3. The Investigator will submit any 
updated SAE data to Alexion within 24 hours of the date the investigational site became aware of 
the event. 
Investigators are not obligated to actively seek AE or SAE data after conclusion of the study 
participation. However, if the Investigator learns of any SAE, including a death, at any time after 
a participant has been discharged from the study, and he/she considers the event to be reasonably 
related to the study intervention or study participation, the Investigator must promptly notify 
Alexion. 
8.3.2. 
Method of Detecting AEs and SAEs 
The method of recording, evaluating, and assessing causality of AEs and SAEs and the 
procedures for completing and transmitting SAE reports are provided in Section 10.3. 

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Care will be taken not to introduce bias when detecting AEs and/or SAEs. Open-ended and 
nonleading verbal questioning of the participant is the preferred method to inquire about AE 
occurrences. 
8.3.3. 
Follow-up of AEs and SAEs 
After the initial AE/SAE report, the Investigator is required to proactively follow-up on each 
participant at subsequent visits/contacts. All SAEs will be followed up until resolution, 
stabilization, the event is otherwise explained, or the participant is lost to follow-up (as defined 
in Section 7.3). Further information on follow-up procedures is provided in Section 10.3. 
8.3.4. 
Regulatory Reporting Requirements for SAEs 
• Prompt notification of an SAE by the Investigator to Alexion is essential so that legal 
obligations and ethical responsibilities towards the safety of participants and the 
safety of a study intervention under clinical investigation are met. 
• Alexion has a legal responsibility to notify both the local regulatory authority and 
other regulatory agencies about the safety of a study intervention under clinical 
investigation. Alexion will comply with country-specific regulatory requirements 
relating to safety reporting to the regulatory authority, IRBs/IECs, and Investigators. 
• Alexion or designee is required to submit individual SUSAR reports (defined in 
Section 10.3.2) in the format of MedWatch 3500 or CIOMS I Form to health 
authorities and Investigators as required. Forms submitted to Investigators will be 
blinded to treatment assignment. In limited circumstances, the blind may be broken in 
the case of urgent safety issues that could compromise participant safety. 
• An Investigator who receives an Investigator safety report describing an SAE or other 
specific safety information (eg, summary or listing of SAEs) from Alexion will 
review and then file it along with the IB and will notify the IRB/IEC, if appropriate 
according to local requirements. 
• Under the EU CTR 536/2014, events other than SAEs (eg, unexpected events) that 
may impact the benefit-risk balance should be reported. See definitions in 
Section 10.3.5. 
8.3.5. 
Medication Error, Drug Abuse, and Drug Misuse 
8.3.5.1. 
Timelines 
If an event of medication error, drug abuse, or drug misuse occurs during the study, then the 
Investigator or other site personnel informs the appropriate Alexion or designee immediately but 
no later than 24 hours of when they become aware of it. 
The full definitions and examples of medication error, drug abuse, and drug misuse can be found 
in Section 10.4. 

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8.3.5.2. 
Medication Error 
For the purposes of this clinical study a medication error is an unintended failure or mistake in 
the treatment process for an investigational medicinal product (IMP) or Alexion AxMP that 
either causes harm to the participant or has the potential to cause harm to the participant. 
8.3.5.3. 
Drug Abuse 
Drug abuse is the persistent or sporadic intentional, non-therapeutic excessive use of IMP or 
Alexion AxMP for a perceived reward or desired non-therapeutic effect. 
8.3.5.4. 
Drug Misuse 
Drug misuse is the intentional and inappropriate use of IMP or Alexion AxMP for medicinal 
purposes outside of the authorized product information, or for unauthorized IMPs or Alexion 
AxMPs, outside the intended use as specified in the protocol and includes deliberate 
administration of the product by the wrong route. 
8.4. 
Treatment of Overdose 
For this study, any dose of IMP or Alexion AxMP greater than that specified in the protocol will 
be considered an overdose. Any blinded dose greater than that specified in the protocol will be 
considered a suspected overdose. 
Alexion does not recommend specific treatment for an overdose. General supportive measures 
are recommended. 
Overdoses are medication errors that are not considered AEs unless there is an untoward medical 
occurrence resulting from the overdose. 
In the event of an overdose or suspected overdose, the Investigator should: 
1. Capture and forward the event, with or without associated AEs, to Alexion Global Patient 
Safety via email or facsimile (clinicalsae@alexion.com or + 1.203.439.9347) using the 
Alexion Clinical Study Overdose Report Form within 24 hours of awareness. 
2. Contact the Medical Monitor immediately. 
3. Evaluate the participant to determine, in consultation with the Medical Monitor, if 
possible. 
4. Closely monitor the participant for any AE/SAE and laboratory abnormalities. 
5. Obtain a plasma sample for PK analysis if requested by the Medical Monitor (determined 
on a case-by-case basis). 
6. For unblinded participants, document the quantity of the excess dose as well as the 
duration of the overdose in the eCRF. 
Decisions regarding dose interruptions or modifications will be made by the Investigator in 
consultation with the Medical Monitor based on the clinical evaluation of the participant. 

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8.5. 
Pharmacokinetics 
• Biomatrix samples (eg, plasma, serum, or whole blood) will be collected for 
measurement of concentrations of ALXN2050 as specified in the SoA (Section 1.3). 
• Instructions for the collection and handling of biological samples will be provided by 
Alexion. The actual date and time (24-hour clock time) of each sample will be 
recorded. 
• Samples will be used to evaluate the PK of ALXN2050. 
• PK data may be used for research to develop methods, assays for prognosis, 
diagnostics, and/or treatment monitoring related to gMG, pathways associated with 
the disease state, and/or mechanism of action of ALXN2050. 
• Study intervention concentration information that would unblind the study will not be 
reported to investigational sites or blinded personnel until the study has been 
unblinded. 
8.6. 
Pharmacodynamics 
• Biomatrix samples (eg, plasma, serum, and whole blood) will be collected for 
measurement of AP activity and Bb as specified in the SoA (Section 1.3). 
• Instructions for the collection and handling of biological samples will be provided by 
Alexion. The actual date and time (24-hour clock time) of each sample will be 
recorded. 
• Samples will be used to evaluate the PD of ALXN2050. Samples collected for 
analyses of ALXN2050 (plasma, serum, whole blood) concentration may also be used 
to evaluate safety or efficacy aspects related to concerns arising during or after the 
study. 
8.7. 
Genetics 
Genetics are not evaluated in this study. 
8.8. 
Biomarkers 
• Samples will be collected for analyses that may include but are not limited to 
evaluation of complement components (eg, FD, C3, CP activity), anti-AChR 
antibody, and other nongenetic exploratory biomarkers (eg, anti-MuSK antibodies, 
anti-low density lipoprotein receptor-related protein 4 [LRP4] antibodies, matrix 
metalloproteinase 10 [MMP-10], interleukin 6 [IL-6]) in adult participants with gMG. 
• Blood samples for biomarker research will be collected from all participants in this 
study. 
• Additional details regarding how biomarkers will be collected and analyzed are 
provided in Section 10.6. 

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8.9. 
Immunogenicity Assessments 
Immunogenicity is not applicable in this study. 
8.10. 
Health Economics Data and/or Medical Resource Utilization 
Medical resource utilization and/or health economics data will not be collected during this study. 
8.11. 
Other Assessments and Procedures 
8.11.1. 
Informed Consent 
Participants or their legally authorized representative must be consented per the informed 
consent process outlined in Section 10.1.3. 
8.11.2. 
Demographics 
A review of demographic parameters, including age, gender, race, and ethnicity, will be 
performed if allowed per country-specific regulations. 
8.11.3. 
Inclusion and Exclusion Criteria 
All inclusion (Section 5.1) and exclusion (Section 5.2) criteria must be reviewed by the 
Investigator or qualified designee to ensure the participant qualifies for study participation. 
8.11.4. 
Medical History and MG History 
The participant’s MG history and relevant medical history, including prior and concomitant 
conditions/disorders, treatment history, substance usage, and history of medical conditions and 
surgeries will be evaluated by the Investigator and documented in the source documents and 
eCRF. 
Myasthenia gravis history will include diagnosis date; initial MG clinical presentation (ocular 
myasthenia gravis [oMG] or gMG); time to gMG, if initial clinical presentation was oMG; 
maximum MGFA classification since diagnosis; ventilatory support since diagnosis; dates of 
MG exacerbation or crisis since diagnosis and prior to Day 1; and any MG-related 
hospitalizations within 2 years prior to the Screening Visit. Myasthenia gravis-specific 
medication or therapy taken within 2 years prior to the Screening Visit should also be recorded. 
8.11.5. 
MGFA Classification 
The MGFA Clinical Classification, a universally accepted grading system for patients with MG, 
will be also used to determine participant eligibility. This system was developed to identify 
subgroups that share distinct clinical features or disease severity that may necessitate different 
prognoses or responses to treatment (Jaretzki, 2000). 

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Table 10: 
MGFA Classification System 
Class I 
Any ocular muscle weakness; may have weakness of eye closure. All other muscle 
strength is normal. 
Class II 
Mild weakness affecting other than ocular muscles; may also have ocular muscle 
weakness of any severity. 
Class IIa Predominantly affecting limb, axial muscles, or both. May also have lesser 
involvement of oropharyngeal muscles. 
Class IIb Predominantly affecting oropharyngeal, respiratory muscles, or both. May also have 
lesser or equal involvement of limb, axial muscles, or both. 
Class III 
Moderate weakness affecting other than ocular muscle; may also have ocular muscle 
weakness of any severity. 
Class IIIa Predominantly affecting limb, axial muscles, or both. May also have lesser 
involvement of oropharyngeal muscles. 
Class IIIb Predominantly affecting oropharyngeal, respiratory muscles, or both. May also have 
lesser or equal involvement of limb, axial muscles, or both. 
Class IV 
Severe weakness affecting other than ocular muscles; may also have ocular muscle 
weakness of any severity. 
Class IVa Predominantly affecting limb and/or axial muscles. May also have lesser 
involvement of oropharyngeal muscles. 
Class IVb Predominantly affecting oropharyngeal, respiratory muscles, or both. May also have 
lesser or equal involvement of limb, axial muscles, or both. 
Class V 
Defined by intubation, with or without mechanical ventilation, except when 
employed during routine postoperative management. Use of a feeding tube without 
intubation places the patient in Class IVb. 
Source: Jaretzki, 2000 
8.11.6. 
Vaccination or Antibiotic Prophylaxis 
All participants must be vaccinated against meningococcal infections within 3 years or before the 
administration of study intervention on Day 1. Participants who initiate study intervention 
treatment less than 2 weeks after receiving a meningococcal vaccine must receive treatment with 
appropriate prophylactic antibiotics until at least 2 weeks after vaccination. 
8.11.7. 
Rerandomization 
All participants who are determined to be eligible for Study ALXN2050-MG-201 by the 
Investigator will be randomized to treatment via an IRT system on Day 1 (Section 4.1). 
Participants randomized to placebo will be further randomized to 1 of the 2 active treatment 
groups (ie, ALXN2050 120 or 180 mg) at Week 8. 

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9. 
STATISTICAL CONSIDERATIONS 
Statistical methods for this study will be further detailed in a separate statistical analysis plan 
(SAP). The SAP will be developed and finalized prior to the database lock. Statistical analyses 
will include tabulations of summary data, inferential analyses, by-participant listings, and 
figures. Inference from efficacy analyses will be based on a 2-sided type I error rate (α) of 10% 
unless stated otherwise. The summary statistics for continuous variables will include, but not be 
limited to, the number of participants, mean, standard deviation, minimum, median, and 
maximum. For categorical variables, frequencies and percentages will be presented. 
All efficacy analyses will be based on the Full Analysis Set (FAS). Supplemental per-protocol 
analyses for primary and secondary efficacy endpoints will be performed based on the Per 
Protocol Set (PPS) in the same manner as done for the FAS. Safety analyses will be performed 
on the Safety Set (SS). 
The baseline value for analysis and reporting will be based on the last nonmissing measurement 
on or prior to the first dose of study intervention unless stated otherwise. 
Analyses will be performed using the Statistical Analysis System (SAS®) software Version 9.4 
or higher. 
Given that this is a proof-of-concept Phase 2 study, all results will be interpreted as exploratory 
in nature. 
9.1. 
Statistical Hypotheses 
9.1.1. 
Primary Hypothesis 
The primary hypothesis is that the ALXN2050 180 mg bid group is superior to the placebo group 
in the proportions of responders in the primary endpoint. The responders are defined as 
participants who achieve an MG-ADL total score reduction of at least 2 points in any 
4 consecutive weeks during the first 8 weeks of the PEP and who did not receive rescue therapy. 
The hypothesis for assessing superiority with respect to the proportions of responders is: 
𝐻𝐻0: 𝑝𝑝3 −𝑝𝑝1 ≤0; 𝐻𝐻1: 𝑝𝑝3 −𝑝𝑝1 > 0 
Where p1 and p3 are the proportions of responders in the primary endpoint for the placebo and 
ALXN2050 180 mg bid groups, respectively. 
9.1.2. 
Secondary Hypotheses 
The secondary hypothesis is that there is an increasing trend in the proportions of responders in 
the primary endpoint among the 3 treatment groups. The hypothesis for assessing the increasing 
trend is: 
𝐻𝐻0: 𝑝𝑝1 = 𝑝𝑝2 = 𝑝𝑝3; 𝐻𝐻1: 𝑝𝑝1 ≤𝑝𝑝2 ≤𝑝𝑝3; with at least 1 strict inequality 
Where p1, p2, and p3 are the proportions of responders in the primary endpoint in the placebo 
group, ALXN2050 120 mg bid group, and ALXN2050 180 mg bid group, respectively. 

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9.2. 
Sample Size Determination 
The study has 3 treatment groups: ALXN2050 180 mg bid, ALXN2050 120 mg bid, and 
placebo. The goals of this study are to establish proof of concept for the treatment of gMG with 
ALXN2050 and to select a dosage for further development of ALXN2050 in gMG. Both trend 
analysis among the 3 treatment groups and differences in proportions of responders between the 
ALXN2050 180 mg bid group and the placebo group in the primary endpoint are used for sample 
size determination. 
Data from the Argenx ADAPT study and the Momenta Vivacity-MG study were used to estimate 
the response rate on placebo with background standard-of-care treatment. Based on the data from 
both studies, the response rate for the placebo group is assumed to be 25%. A sample size of 
54 evaluable participants with a randomization ratio of 1:1 to the placebo group and the 
ALXN2050 180 mg bid group results in approximately 80% power to detect a treatment effect 
(difference in the proportions of responders) of 35% between the 2 treatment groups, using a 
2-sided type I error rate of 0.1 and the exact binomial computation method. An additional 
13 evaluable participants will be enrolled to the ALXN2050 120 mg bid group, for a total of 
67 evaluable participants. 
Assuming that the response rate for the ALXN2050 120 mg bid group is 45%, with a total of 
67 evaluable participants, the study has approximately 80% power to detect the increasing trend 
in the proportions of responders, using Cochran Armitage test at a 2-sided type I error rate of 0.1. 
Assuming about 5% non-evaluability, the study is planned to enroll 70 participants in total. 
The sample size calculations were performed in PASS 2020. 
9.3. 
Populations for Analyses 
For the purpose of analyses, the following populations are defined. The primary efficacy 
analyses will be based on the FAS and safety analyses will be based on the SS. 
Population 
Description 
Randomized Set 
All randomized participants grouped by randomized treatment group. 
FAS 
All randomized participants who receive at least 1 dose of study 
intervention and have a baseline and at least 1 postbaseline efficacy 
assessment. Participants will be analyzed as randomized. 
PK Analysis Set 
All randomized participants who have a baseline PK value and at least 
1 evaluable postdose PK assessment. 
PD Analysis Set 
All randomized participants who have a baseline PD value and at least 
1 evaluable postdose PD assessment. 
PPS 
All participants in the FAS without any important protocol deviations. 
SS 
All randomized participants who receive at least 1 dose of study 
intervention. Participants will be analyzed according to the study 
intervention they actually received. 
OLE Set 
All randomized participants who receive at least 1 dose of ALXN2050 
at the start of the OLE Period. 

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Abbreviations: FAS = Full Analysis Set; OLE = Open-label Extension; PD = pharmacodynamic; 
PK = pharmacokinetic; PPS = Per Protocol Set; SS = Safety Set 
9.4. 
Statistical Analyses 
9.4.1. 
Enrollment and Disposition 
The number of participants screened, screen failed, and randomized will be presented. 
Enrollment information will be grouped by stratification factor and treatment allocation. The 
number of participants discontinued (along with reasons) from the PEP, ETP, OLE Period, and 
the overall study will be summarized. 
9.4.2. 
Demographics, Baseline Characteristics, Inclusion and Exclusion Criteria, and 
Protocol Deviations 
All demographic information and baseline characteristics will be reported by treatment group 
and overall. No statistical test will be performed for homogeneity among treatment groups. 
The number and percentage of participants not meeting a specific inclusion or exclusion criterion 
will be summarized. A similar summary will be provided for important protocol deviations based 
on prespecified categories. 
9.4.3. 
Medical/Surgical History, Physical Examination, and Myasthenia Gravis 
History 
Medical and surgical history will be summarized using the Medical Dictionary for Regulatory 
Activities (MedDRA), Version 23 or later, System Organ Class (SOC) and Preferred Term. 
Myasthenia gravis history and abnormal physical examination findings will also be summarized. 
9.4.4. 
Prior and Concomitant Medications 
For analysis and reporting purposes, any medication started prior to first dose of study 
intervention will be considered prior medication, and medications that were received on or after 
the first dose of study intervention will be considered concomitant medications. All prior and 
concomitant medications including MG-specific medications and rescue therapy during the 
study, if any, will be summarized. 
9.4.5. 
Extent of Drug Exposure 
The cumulative and total drug exposure, dose intensity and relative dose intensity, and treatment 
duration will be summarized by treatment group and study periods. The relative dose intensity 
will be calculated as the percentage of the actual drug exposure divided by the protocol planned 
drug exposure by study period. 
9.4.6. 
Efficacy Analyses 
All efficacy analyses will be based on the FAS. Supplemental per-protocol analyses for primary 
and secondary efficacy endpoints will be performed based on the PPS in the same manner as the 
FAS. 

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9.4.6.1. 
Analyses of Primary Efficacy Endpoint 
9.4.6.1.1. Primary Analysis for the Primary Endpoint 
The primary endpoint is the proportion of participants with an MG-ADL total score reduction of 
≥ 2 points in any 4 consecutive weeks during the first 8 weeks and who did not receive rescue 
therapy. 
The differences in proportions, along with 2-sided 90% confidence intervals (CIs) using Chan 
and Zhang method (Chan, 1999), will be presented between the ALXN2050 180 mg bid group 
and the placebo group. P-value using Barnard’s unconditional exact test to determine whether 
there is a difference in the proportions of responders between the 2 treatment groups will be 
presented. 
9.4.6.1.2. Secondary Analysis for the Primary Endpoint 
The differences in proportions, along with 2-sided 90% CIs using Chan and Zhang method 
(Chan, 1999), will be presented for the following pairwise comparisons: between the ALXN2050 
120 mg bid group and the placebo group, and between the ALXN2050 180 mg bid group and the 
ALXN2050 120 mg bid group. 
In addition, the proportions of responders in each treatment group will be presented along with 
exact 2-sided 90% CIs using the Clopper-Pearson method. 
Trend analysis to detect whether there is an increasing trend in the proportions of responders in 
the primary endpoint will be presented along with the p-value using Cochran Armitage test. 
9.4.6.2. 
Analyses of Secondary Efficacy Endpoints 
For all continuous secondary endpoints (QMG total score, MG-ADL total score, Neuro-QoL™ 
Fatigue score) related to the change from baseline at Week 8, the mixed-effects model with 
repeated measures (MMRM) will be used to estimate the treatment effect using all available 
data, irrespective of whether participants received rescue therapy. Missing data will not be 
imputed for the analysis. For each of the continuous secondary endpoints, the MMRM will 
include change from baseline at each prespecified time point as the response variable, treatment 
group, study visit, and treatment-by-study visit interaction as fixed categorical effects, and 
baseline total score as a covariate. The treatment effect will be evaluated via contrast for the 
treatment-by-visit term at Week 8. An unstructured covariance matrix will be used to model the 
correlations among repeated measurements within each participant. Other covariance structures 
will be implemented if a convergence issue occurs (details to be provided in the SAP). The 
Kenward-Rogers method will be used to estimate the denominator degrees of freedom. 
Trend analysis to detect whether there is a decreasing trend in the change from baseline at 
Week 8 in MG-ADL total score will be presented along with the p-value using 
Jonckheere-Terpstra trend test. 
For the categorical secondary endpoints: 
• Proportion of participants with at least a 3-, 4-, 5-, 6-, 7-, or 8-point improvement in 
the QMG score at Week 8 

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• Proportion of participants with a QMG score reduction of ≥ 3 points in any 
4 consecutive weeks during the first 8 weeks and who did not receive rescue therapy 
• Proportion of participants with at least a 2-, 3-, 4-, 5-, 6-, 7-, or 8-point improvement 
in the MG-ADL total score at Week 8 
• Proportion of participants with at least a 3-, 4-, 5-, 6-, 7-, or 8-point improvement in 
the MG-ADL total score in any 4 consecutive weeks during the first 8 weeks and who 
did not receive rescue therapy 
• Proportion of participants with at least a 4-, 5-, 6-, 7-, or 8-point improvement in the 
QMG total score in any 4 consecutive weeks during the first 8 weeks and who did not 
receive rescue therapy 
The proportions of responders in each treatment group will be presented along with exact 2-sided 
90% CIs using Clopper-Pearson method. The differences in proportions between each of the 
ALXN2050 dosage groups (180 mg bid or 120 mg bid) and the placebo group will be presented, 
along with 2-sided 90% CIs using Chan and Zhang method (Chan, 1999). 
9.4.6.3. 
Multiplicity Adjustment 
This is a Phase 2 study. Multiplicity adjustments are not planned. 
9.4.6.4. 
Analyses of Exploratory Endpoints 
Proportion of participants with both an MG-ADL total score reduction of ≥ 2 points and a 
QMG total score reduction of ≥ 3 points in any 4 consecutive weeks during the first 8 weeks 
and who did not receive rescue therapy: 
Number and proportion of responders will be summarized by treatment group. Exact 
(Clopper-Pearson) 90% CI for each treatment group will be presented. The differences in 
proportions between each of the ALXN2050 dosage groups (180 mg bid or 120 mg bid) and the 
placebo group will be presented, along with 2-sided 90% CIs using Chan and Zhang method 
(Chan, 1999). 
Proportion of participants with at least 2-point improvement in the MG-ADL total score 
for 4 consecutive weeks and who did not receive rescue therapy (measured from Day 1 to 
Week 8 for Groups 1, 2, and 3 and from Week 8 to Week 16 for Groups 3a and 3b): 
The proportion of participants with at least a 2-point improvement in the MG-ADL total score 
for 4 consecutive weeks (measured from Day 1 to Week 8 for Group 1, Group 2, Group 3 and 
from Week 8 to Week 16 for Group 3a and 3b) and who did not receive any rescue therapy will 
be summarized. Exact (Clopper-Pearson) 90% CI for each group will be presented. 
Change from baseline in MG-ADL total score at Week 8 for Groups 1, 2, 3 and from 
Week 8 to Week 16 for Groups 3a and 3b: 
Change from baseline in MG-ADL total score at Week 8 for Group 1, 2, 3 and change from 
baseline in MG-ADL total score at Week 16 for Group 3a and 3b will be summarized in 
descriptive statistics. Change from baseline in MG-ADL total score by study visit up to Week 16 
and treatment group will be summarized in descriptive statistics. 

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Change from baseline in MG-ADL total score at Week 26 for Groups 1 and 2, and from 
Week 8 to Week 34 for Groups 3a and 3b: 
Change from baseline in MG-ADL total score at Week 26 for Group 1 and 2 and change from 
baseline in MG-ADL total score at Week 34 for Group 3a and 3b will be summarized. Change 
from baseline in MG-ADL total score by study visit up to Week 34 and treatment group will be 
summarized. 
Incidence of Clinical Deterioration of gMG over time: 
Incidence of clinical deterioration of gMG during the first 8 weeks for Group 1, 2, 3, and during 
the first 34 weeks for Group 1, 2 and 3/3a/3b will be summarized separately. The number and 
percentage will be presented. Exact (Clopper-Pearson) 90% CIs for the true proportions will be 
presented. 
MGFA-PIS and Minimal Manifestations at Week 8 and Week 26: 
A summary of the MGFA-PIS will be presented by treatment group and study visit (including 
Week 8 and up to Week 26), showing the number and percentage of participants in each category 
(ie, improved, unchanged, or worsened). 
A summary table of the number and percentage of participants who achieved MM will be 
presented by treatment group and study visit. 
Proportion of participants who received rescue therapy over time: 
Proportion of participants who received rescue therapy during the first 8 weeks for Group 1, 2, 3, 
and during the first 34 weeks for Group 1, 2 and 3/3a/3b will be summarized separately. FAS 
will be used for this analysis. The number and percentage will be presented. Exact 
(Clopper-Pearson) 90% CIs for the true proportions will be presented. 
OLE data analysis: 
The following efficacy data collected during the OLE period will be listed and summarized in 
descriptive statistics by dose level which is the dose received at the specific visit during OLE 
period: 
• Change from baseline in MG-ADL total score 
• Change from baseline in QMG total score 
• MGFA-PIS status 
• Change from baseline in Neuro-QoL Fatigue total score 
AE data will be listed and summarized in an aggregated manner (combining data from PEP, 
ETP, OLE) by dose received using SS. Additional safety data collected by study visit during the 
OLE period will be listed and summarized by dose level which is the dose received at the 
specific visit during OLE period (“ALXN2050 180 mg” and “ALXN2050 120 mg”). Available 
PK, PD and biomarker data during OLE will be listed using OLES. 
Detailed analyses of tertiary (exploratory) endpoints will be discussed in the SAP. 

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9.4.7. 
Safety Analyses 
All safety analyses will be performed on the SS. 
The safety and tolerability of ALXN2050 will be assessed based on AEs, clinical laboratory 
findings, ECGs, and vital signs findings. Safety analyses will be performed on the SS and OLE 
Set based on the study period under consideration. 
9.4.7.1. 
Analysis of Adverse Events 
Analysis and reporting for AEs will be based on treatment-emergent adverse events (TEAEs), 
including treatment-emergent serious adverse events (TESAEs), defined as an AE with onset on 
or after the first dose of study intervention in the PEP, and TEAEs leading to discontinuation of 
study intervention. TEAEs, TESAEs, and TEAEs leading to discontinuation of study 
intervention will be summarized using MedDRA SOC and Preferred Terms, by severity, and by 
relationship to the study intervention. Participant-year-adjusted event rates will be generated to 
characterize the long-term safety profile. 
9.4.7.2. 
Analysis of Clinical Laboratory Parameters, Vital Sign Measurements, and 
Electrocardiogram Parameters 
Laboratory measurements, changes from baseline at each visit, and shifts from baseline, if 
applicable, will be summarized descriptively. Significant findings related to ECGs and vital sign 
measurements will also be summarized using descriptive analyses. 
9.4.7.3. 
Other Safety Analyses 
The number and percentage of participants in each of the C-SSRS categories and shift analyses 
will be produced descriptively. 
Results from pregnancy tests will be summarized descriptively. 
9.4.8. 
Analyses of Pharmacokinetics and Pharmacodynamics 
Blood samples will be collected for the determination of plasma ALXN2050 concentrations, 
serum AP activity, and plasma Bb concentrations as specified in the SoAs (Table 2, Table 3, and 
Table 4). Trough and peak concentrations (predose concentration [Ctrough] and Cmax) of 
ALXN2050 will be summarized using descriptive statistics. Absolute values and change from 
baseline in serum AP activity and plasma Bb concentrations will be summarized using 
descriptive statistics. 
Blood samples for additional complement biomarkers (eg, FD, C3, CP activity) and nongenetic 
exploratory biomarkers (eg, MuSK, LRP4, MMP-10, IL-6) will be collected as specified in the 
SoAs (Table 2, Table 3, and Table 4). Absolute values and changes from baseline will be 
summarized using descriptive statistics. 
Population PK and exposure-response analyses will be conducted and reported separately. 
9.5. 
Interim Analysis 
An early interim analysis may be conducted at the discretion of Alexion (based on feasibility) 
when approximately 50% of participants have been randomly assigned to study treatment and 

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have had the opportunity to complete the 8-week Primary Evaluation Period or have 
discontinued from the study treatment before Week 8. This early interim analysis, if performed, 
will be conducted by a separate unblinded team and will be for Phase 3 planning purposes only 
with no impact on the progression of the study. 
9.5.1. 
Other Analyses 
Data at 2 predefined time points will be locked for analysis: the first will be after the last 
randomized participant has completed the Week 8 Visit during the PEP, and the second will be 
after the last randomized participant has completed the Week 34 Visit during the ETP. 
Additional analyses may be performed after the PEP. Final analyses and reporting will be 
performed at the end of the study. 
The SAP will describe the planned analyses in greater detail. 
9.6. 
Data Monitoring Committee 
A Data Monitoring Committee will not be convened for Study ALXN2050-MG-201. 

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10. 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
10.1. 
Regulatory, Ethical, and Study Oversight Considerations 
10.1.1. 
Regulatory and Ethical Considerations 
• This study will be conducted in accordance with the protocol and the following: 
− Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and CIOMS International Ethical Guidelines 
− Applicable ICH GCP Guidelines 
− Applicable laws and regulations 
• The protocol, protocol amendments (ie, modifications), ICF, IB, and other relevant 
documents (eg, advertisements) must be submitted to an IRB/IEC by the 
Investigator/Alexion, and reviewed and approved by the IRB/IEC before the study is 
initiated. 
− If any of these documents require regulatory/health authority approval per local 
regulations, Alexion will also obtain such approval before the study is initiated. 
• Any substantial amendments (ie, modifications) to the protocol will require IRB/IEC 
and regulatory/health authority approval before implementation of changes made to 
the study design, except for changes necessary to eliminate an immediate hazard to 
study participants. 
• For studies to be approved by the Medicines and Healthcare products Regulatory 
Agency: The Investigator will notify the IRB/IEC of deviations from the study 
protocol or GCP as defined by UK legislation as a serious breach or as required by 
IRB/IEC procedures. 
• The Investigator will be responsible for the following: 
− Providing written summaries of the status of the study to the IRB/IEC annually or 
more frequently in accordance with the requirements, policies, and procedures 
established by the IRB/IEC. 
− Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures. 
− Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 Code of Federal Regulations (CFR), ICH guidelines, the 
IRB/IEC, EU CTR 536/2014 for clinical studies, and all other applicable local 
regulations. 
− Promptly notifying Alexion of any (potential) serious breach of the protocol or 
regulations (including if a data breach compromises the integrity, confidentiality, 
or availability of the personal data of participants) so that legal and ethical 
obligations are met. A ‘serious breach’ means a breach likely to affect to a 

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significant degree the safety and rights of a participant or the reliability and 
robustness of the data generated in the clinical study. 
• In certain regions/countries, Alexion has a legal responsibility to notify both the local 
regulatory authority and other regulatory agencies about such breaches. 
− Alexion will comply with country-specific regulatory requirements relating to 
serious breach reporting to the regulatory authority (including data protection 
authorities and, if applicable, affected participants in case of a personal data 
breach), IRB/IEC, and Investigators. Under EU CTR 536/2014, Alexion is 
required to enter details of serious breaches into the European Medicines Agency 
(EMA) Clinical Trials Information System (CTIS). It is important to note that 
redacted versions of serious breach reports will be available to the public via 
CTIS. 
• The Investigator should have a process in place to ensure that: 
− The site staff or service providers delegated by the Investigator/institution are able 
to identify the occurrence of a (potential) serious breach, including personal data 
breaches. 
− A (potential) serious breach is promptly reported to Alexion or delegated party, 
through the contacts (email address or telephone number) provided by Alexion. 
10.1.2. 
Financial Disclosure 
Investigators and Sub-Investigators will provide Alexion with sufficient, accurate financial 
information as requested to allow Alexion to submit complete and accurate financial certification 
or disclosure statements to the appropriate regulatory authorities. Investigators are responsible 
for providing information on financial interests during the course of the study and for 1 year after 
completion of the study. 
10.1.3. 
Informed Consent Process 
• It is the responsibility of the Investigator or designee to obtain signed (written or 
electronic signature) informed consent from all study participants, prior to performing 
any study-related procedures including screening assessments. 
• The Investigator or designee will explain the nature of the study (including but not 
limited to the objectives, potential benefits and risks, inconveniences, and the 
participant’s rights and responsibilities) to the participant, defined according to local 
and country regulations where the study is taking place, and answer all questions 
regarding the study. 
• Patients in vulnerable populations (including those placed in an institution due to an 
official or judicial order) and patients who are dependent on the Sponsor or the 
institution/investigational site are prohibited from providing informed consent in this 
study and are therefore excluded from participation. 
• Participants must be informed that their participation is voluntary. Participants will be 
required to sign a statement of informed consent or a certified translation, if 

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applicable, that meets the requirements of 21 CFR 50, local regulations, EU General 
Data Protection Regulation, ICH GCP guidelines, Health Insurance Portability and 
Accountability Act requirements, where applicable, and the IRB/IEC or study center. 
• The participant’s medical record must include a statement that signed (written or 
electronic) informed consent was obtained before any screening procedures were 
performed with a participant, and the date the written consent was obtained. The 
authorized person obtaining the informed consent must also sign the ICF(s). 
• Participants must be reconsented to the most current version of the ICF(s) during their 
participation in the study, as applicable. 
• A copy of the signed (written or electronic) informed consent documentation (ie, a 
complete set of participant information sheets and fully executed signature pages) 
must be provided to the participant, as applicable. This document may require 
translation into the local language. Original signed (written or electronic) consent 
forms must remain in each participant’s study file and must be available for 
verification at any time. 
Participants who are rescreened outside of the Screening window (Table 2) are required to sign a 
new ICF (Section 5.4). 
10.1.4. 
Recruitment Strategy 
Participants will be identified by qualified research staff. This may be done through a review of 
medical records, external referrals or using databases. Recruitment strategies may include study 
posters, referral letters, recruitment brochures, advertisements, social media posts, and websites, 
where permitted by local regulations. All recruitment materials will be submitted to local 
IRB/EC as required, for review and approval for use. 
10.1.5. 
Data Protection 
• Participants will be assigned a unique identifier by a Trusted Third Party contracted 
by Alexion. Any participant records or datasets that are transferred to Alexion or 
designee will contain the identifier only; participant names, initials, or any 
information which would make the participant identifiable will not be transferred. 
• Participants must be informed that their personal study-related and coded 
(pseudonymized) data will be used in accordance with applicable data protection law, 
and participants must also be informed of any individuals rights they may have with 
regard to their personal data. Participants will be informed about how their personal 
study-related data will be disclosed, and will be required to agree to the information 
contained in the informed consent and provide consent to the processing of their 
personal data, if required by applicable data protection law. 
• Participants must be informed that their medical records may be examined by Clinical 
Quality Assurance auditors or other authorized personnel appointed by Alexion, 
appropriate IRB/IEC members, and inspectors from regulatory authorities. 

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• Alexion as a data controller has implemented privacy and security controls designed 
to help protect participant personal data, including information security controls, 
firewalls, incident detection, and secure transfer measures. 
• The contract between Alexion and study sites specifies responsibilities of the parties 
related data protection, including handling of data security breaches and respective 
communication and cooperation of the parties. 
• Information technology systems used to collect, process, and store study-related data 
are secured by technical and organizational security measures designed to protect 
such data against accidental or unlawful loss, alteration, or unauthorized disclosure or 
access. 
• The EU General Data Protection Regulation (GDPR) defines pseudonymization as 
the processing of personal data in such a way that the personal data can no longer be 
attributed to a specific individual without the use of additional information, provided 
that such additional information is kept separately and protected by technical and 
organizational measures to ensure that the personal data are not attributed to an 
identified or identifiable natural person. 
• Appropriate safeguards will be implemented to protect coded data during and after 
the study that include: 
− Access to the coded data will be limited to specific individuals subject to 
confidentiality obligations (including the obligation to not attempt to re-identify 
individuals/decode the clinical data). 
− The coded data will be protected with security measures to avoid data alteration, 
loss, and unauthorized accesses and further de-identification techniques may be 
applied. 
− A data protection impact assessment (DPIA), where required, will apply to 
identify and mitigate privacy risks, if any, associated with each scientific research. 
− The coded data will not be shared for direct marketing purposes or other purposes 
that are not legal duties or are not considered scientific research according to the 
applicable data protection legislation. In particular, it will not be used to make 
decisions about future services available to the participant, such as insurance. 
• In addition to having the participants’ data and biosamples coded, the data is also 
protected by high-standard technical security means, such as strong access control 
and encryption. 
• Participants are also protected legally by the following means if the level of 
disclosure of the coded data includes sharing of the latter with other third parties, as 
the participants will be explained in the ICF: 
• The participants’ coded data are protected by contractual arrangements, Codes of 
Conduct, or certifications that set the rules for personal information protection to 
those available in European countries or other alternatives set forth in the law, as well 
as any supplementary technical and organizational measures that may results out of 
conducted transfer impact assessments. 

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10.1.6. 
Dissemination of Clinical Study Data 
Study-related information and study results may be posted on publicly accessible clinical study 
databases (eg, the US website www.clinicaltrials.gov or the EU website 
www.clinicaltrialsregister.eu), as appropriate, and in accordance with national, regional, and 
local regulations. However, posting of study results per local regulations may be deferred to a 
later date for one of the following reasons: 
• Study is still ongoing in other countries or regions 
• Study is part of an ongoing review for approval by Health Authorities; study result 
data deferral request can be submitted. 
10.1.7. 
Data Quality Assurance 
• All participant data relating to the study will be recorded on printed CRF or eCRF 
unless transmitted to Alexion or designee electronically (eg, laboratory data). The 
Investigator is responsible for verifying that data entries are accurate and correct by 
physically or electronically signing the CRF. 
• The Investigator must maintain accurate documentation (source data) that supports 
the information entered in the eCRF. 
• The Investigator must permit study-related monitoring, audits, IRB/IEC review, and 
regulatory agency inspections and provide direct access to source data documents. 
• Alexion or designee is responsible for the data management of this study including 
quality checking of the data. 
• Study monitors will perform ongoing source data verification to confirm that data 
entered into the eCRF by authorized site personnel are accurate, complete, and 
verifiable from source documents; that the safety and rights of participants are being 
protected; and that the study is being conducted in accordance with the currently 
approved protocol and any other study agreements, ICH GCP, and all applicable 
regulatory requirements. 
− Remote source data verification may be employed where permitted by local 
regulations. 
− The scope of the source data verification will be described in detail in the Clinical 
Monitoring Plan. 
• Records and documents, including signed ICFs, pertaining to the conduct of this 
study must be retained by the Investigator for at least 25 years after study completion 
(or per local or institutional policy record retention requirements). No records may be 
destroyed during the retention period without the written approval of Alexion. No 
records may be transferred to another location or party without written notification to 
Alexion. 
10.1.8. 
Source Documents 
Source documents provide evidence for the existence of the participant and substantiate the 
integrity of the data collected. The Investigator or designee will prepare and maintain adequate 

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and accurate source documents (eg, medical records, ECGs, AE and concomitant medication 
reporting, raw data collection forms) designed to record all observations and other pertinent data 
for each participant. 
Data reported on the eCRF that are transcribed from source documents must be consistent with 
the source documents or the discrepancies must be explained. The eCRFs must be completed by 
the Investigator or designee as indicated in the site delegation log. The Investigator may need to 
request previous medical records or transfer records, depending on the study. Also, current 
medical records must be available to Alexion, Alexion delegates, and health authorities, as 
requested. Source documents are filed at the investigational site. 
Per ICH E6 (R2) guidelines and good documentation practice requirements, source documents 
and study records in all media (eg, paper, electronic) must be Attributable, Legible, 
Contemporaneous, Original, Accurate, and Complete. 
10.1.9. 
Study and Site Start and Closure 
The study start date is the date on which the clinical study will be open for recruitment of 
participants. 
The first act of recruitment is the first site activation and will be the study start date. 
Alexion reserves the right to close the study site or terminate the study at any time for any reason 
at its sole discretion. Study sites will be closed after the study is completed or following the 
decision to close or terminate the study. A study site is considered closed when all participants 
have completed the EOS Visit, all data have been collected and entered into the electronic data 
capture (EDC) system, all required documents and study supplies have been collected and 
reconciled, and a study-site closure visit has been performed. 
The Investigator may initiate study-site closure at any time, provided there is reasonable cause 
and sufficient notice is given in advance of the intended termination. 
Reasons for the early closure of a study site by Alexion or Investigator may include but are not 
limited to: 
• Failure of the Investigator to comply with the protocol, the requirements of the 
IRB/IEC or local health authorities, Alexion’s procedures, or ICH GCP guidelines 
• Inadequate recruitment of participants by the Investigator 
• Discontinuation of further study intervention development 
• Withdrawal of the local ethics committee/health authority favorable opinion or 
approval 
Alexion 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 of the study intervention to 
participants enrolled or continuing in the study. 
• Alexion decision to suspend or discontinue testing, evaluation, or development of the 
study intervention. 

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If the study is prematurely terminated or suspended, Alexion or designee shall promptly inform 
the Investigators, IRBs/IECs, regulatory authorities, and any contract research organization(s) 
used in the study of the reason for termination or suspension, as specified by the applicable 
regulatory requirements. The Investigator shall promptly inform the participant and should 
assure appropriate participant therapy and/or follow-up. 
10.1.10. 
Publication Policy 
• Where possible, primary manuscripts reporting results of the primary efficacy 
endpoint or the final results will be submitted for publication within 12 to 18 months 
of the primary evaluation date or end of study, whichever is earlier. 
• Investigators who participate as authors in manuscripts derived from 
Alexion-sponsored studies will agree to the prerequisites as outlined in the Alexion 
author engagement agreement prior to engaging in manuscript development. 
• The Investigator agrees to submit proposals for new manuscripts (whether or not the 
proposed analyses are derived from protocol-specified endpoints) to Alexion for 
review and consideration. All manuscripts or abstracts emanating from approved 
proposals are to be submitted to Alexion for review before submission to the 
journal/society. This allows Alexion to protect proprietary information and provide 
comments. 
− The proprietary nature of some development work may preclude publication. In 
some cases, it may be necessary to delay a publication to allow Alexion to ensure 
protection of intellectual property. 
• Primary publications, including congress and journal publications, containing the 
protocol-specified results of a study should occur prior to the publication of 
individual study site results or case reports. Alexion’s policy prohibits duplicate 
publication, whereby the same results must not be published in multiple 
peer-reviewed journal manuscripts. 
− Encore congress publications may be appropriate to allow communication of 
research findings to relevant audience and geographical regions. 
• Alexion will comply with the requirements for publication of study results as defined 
by the Pharmaceutical Research and Manufacturers of America and the International 
Committee of Medical Journal Editors and per the Alexion Publication Policy. In 
accordance with standard editorial and ethical practice, Alexion will generally 
support publication of multicenter studies only in their entirety and not as individual 
site data. In this case, a Coordinating Investigator will be designated by mutual 
agreement. 
• Authorship will be determined by mutual agreement and in line with International 
Committee of Medical Journal Editors authorship requirements and per the Alexion 
Publication Policy. 
• Alexion will publish Patient Lay Summaries and include participants and/or 
caregivers as reviewers for readability and understanding of lay person language. 

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10.1.11. 
Good Clinical Practice Compliance 
Alexion and any third party to whom aspects of the study management or monitoring have been 
delegated will undertake their assigned roles for this study in compliance with all applicable 
industry regulations, ICH GCP Guideline E6 R2, EU Directive 2001/20/EC, as well as all 
applicable national and local laws and regulations. 
Visits to sites are conducted by representatives of Alexion and/or the company 
organizing/managing the research on behalf of Alexion to inspect study data, participants’ 
medical records, and eCRFs in accordance with current GCP and respective local and 
(inter)national government regulations and guidelines. Records and data may additionally be 
reviewed by auditors or by regulatory authorities. 
Alexion ensures that local regulatory authority requirements are met before the start of the study. 
Alexion (or designee) is responsible for the preparation, submission, and confirmation of receipt 
of any regulatory authority approvals required prior to release of study intervention for shipment 
to the site.

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10.2. 
Clinical Laboratory Tests 
• The tests listed in Table 11 will be performed by the central or specialty laboratory as 
appropriate for all participants unless otherwise noted. However, if a participant is not 
able to present to the clinic, a local laboratory may be used to collect the 
protocol-required samples. 
• Protocol-specific requirements for inclusion or exclusion of participants are detailed 
in Section 5. 
• Additional tests may be performed at any time during the study as determined 
necessary by the Investigator or required by local regulations. 
• Women of childbearing potential should only be enrolled after a negative serum 
pregnancy test result at the Screening Visit and a negative urine pregnancy test at 
Day 1. Additional serum or urine pregnancy testing will be employed as required by 
site policies, local regulations, or per the requirements of the IRB/IEC and should be 
performed per the time points specified in the SoA (Table 2, Table 3, and Table 4). 
• Investigators must document their review of each laboratory report. Clinically 
significant findings resulting in an assessment of a TEAE should be recorded on the 
AE eCRF. 
• Laboratory/analyte results that could unblind the study will not be reported to 
investigational sites or other blinded personnel until the study has been unblinded. 
Table 11: Protocol-Required Laboratory Assessments 
Laboratory 
Assessments 
Parameters 
Hematology 
Platelet count 
RBC count 
Hemoglobin 
Hematocrit 
RBC indices: 
Distribution width 
Mean corpuscular volume 
Mean corpuscular 
hemoglobin 
% Reticulocytes 
WBC count with 
differential: 
Neutrophils 
Lymphocytes 
Monocytes 
Eosinophils 
Basophils 
Clinical 
Chemistry 
BUN 
C-reactive protein 
Creatinine 
Chloride 
Potassium 
Bicarbonate 
Sodium 
Glucose (nonfasting) 
Creatine kinase 
AST/SGOT 
ALT/SGPT 
Alkaline phosphatase 
Gamma 
glutamyltransferase 
Total and direct bilirubin 
Total protein 
Albumin 
Uric acid 
Lipids: 
Total cholesterol 
Triglycerides 
LDL-c 
HDL-c 
Coagulation 
International normalized ratio, partial thromboplastin time, prothrombin time 

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Table 11: Protocol-Required Laboratory Assessments 
Laboratory 
Assessments 
Parameters 
Urinalysis 
Appearance, color, specific gravity, pH, glucose, protein, leukocyte esterase, blood, 
ketones, bilirubin, urobilinogen, nitrite, microscopic examination (if blood or protein 
is abnormal)  
Screening tests 
Serum/urine beta-hCG pregnancy test (as needed for female participants of 
child-bearing potential) 
Serum follicle-stimulating hormone test (as needed for female participants who 
consider themselves postmenopausal) 
HIV-1 and HIV-2 antibodies 
Hepatitis B surface antigen 
Hepatitis C antibody 
Complement 
activity 
Pharmacodynamic assays (AP activity and Bb concentration) 
Complement biomarkers (Factor D, C3, C5b-9, Properdin, and CP activity) 
Other 
Biomarker assay (anti-AChR antibody) 
Pharmacokinetic assay (serum ALXN2050 concentration) 
Nongenetic exploratory biomarkers (eg, MuSK, LRP4, MMP-10, IL-6) 
Abbreviations: AChR = acetylcholine receptor; ALT = alanine aminotransferase; AP = alternative pathway; 
AST = aspartate aminotransferase; Bb = Bb fragment of complement factor B; BUN = blood urea nitrogen; 
C = complement component; C5b-9 = terminal complement complex; CP = classical pathway; eCRF = electronic 
case report form; hCG = human chorionic gonadotropin; HDL-c = high-density lipoprotein cholesterol; 
HIV-1 = human immunodeficiency virus type 1; HIV-2 = human immunodeficiency virus type 2; IL = interleukin; 
LDL-c = low-density lipoprotein cholesterol; LRP4 = low density lipoprotein receptor-related protein 4; 
MMP-10 = matrix metalloproteinase-10; MuSK = muscle-specific tyrosine kinase; RBC = red blood cells; 
SGOT = serum glutamic oxaloacetic transaminase; SGPT = serum glutamic pyruvic transaminase; WBC = white 
blood cells

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10.3. 
Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting 
10.3.1. 
Definition of AE 
AE Definition 
• 
An AE is any untoward medical occurrence in a participant or clinical investigation participant 
administered a pharmaceutical product and which does not necessarily have to have a causal 
relationship with this treatment (ICH E2A). 
• 
Note: An AE can therefore be any unfavorable and unintended sign (including an abnormal 
laboratory finding), symptom, or disease [new or exacerbated] temporally associated with the use 
of the study intervention, whether or not considered related to the study intervention. 
 
Events Meeting the AE Definition  
• 
Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or other safety 
assessments (eg, ECG, radiological scans, vital signs measurements), including those that worsen 
from baseline, considered clinically significant in the medical and scientific judgment of the 
Investigator (ie, not related to progression of underlying disease). 
• 
Exacerbation of a chronic or intermittent pre-existing condition including either an increase in 
frequency and/or intensity of the condition. 
• 
New conditions detected or diagnosed after study intervention administration even though it may 
have been present before the start of the study. 
• 
Signs, symptoms, or the clinical sequelae of a suspected drug-drug interaction. 
• 
Signs, symptoms, or the clinical sequelae of a suspected overdose of either study intervention or a 
concomitant medication. Overdose per se will not be reported as an AE/SAE unless it is an 
intentional overdose taken with possible suicidal/self-harming intent. Such overdoses should be 
reported regardless of sequelae. 
 
Events Not Meeting the AE Definition  
• 
Medical or surgical procedure (eg, endoscopy, appendectomy): The condition that leads to the 
procedure is the AE. Situations in which an untoward medical occurrence did not occur (eg, 
hospitalization for elective surgery if planned before signing the ICF, admissions for social reasons 
or for convenience). 
• 
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. 
• 
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. 
• 
Cases of pregnancy that occur during maternal or paternal exposure to study intervention 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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Events Not Meeting the AE Definition  
• 
Any clinically significant abnormal laboratory findings or other abnormal safety assessments which 
are associated with the underlying disease, unless judged by the Investigator to be more severe than 
expected for the participant’s condition. 
• 
The disease/disorder being studied or expected progression, signs, or symptoms of the 
disease/disorder being studied, unless more severe than expected for the participant’s condition. 
• 
Situations in which an untoward medical occurrence did not occur (social and/or convenience 
admission to a hospital). 
• 
“Lack of efficacy” or “failure of expected pharmacological action” per se will not be reported as an 
AE or SAE. Such instances will be captured in the efficacy assessments. However, the signs, 
symptoms, and/or clinical sequelae resulting from lack of efficacy will be reported as AE or SAE if 
they fulfill the definition of an AE or SAE. 
10.3.2. 
Definition of SAE 
If an event is not an AE per definition above, then it cannot be an SAE even if serious conditions 
are met (eg, hospitalization for signs/symptoms of the disease under study, death due to 
progression of disease). 
An SAE is defined as any untoward medical occurrence that, at any dose: 
1. Results in death 
2. Is life-threatening 
The term “life-threatening” in the definition of “serious” refers to an event in which the participant 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 was more severe. 
3. Requires inpatient hospitalization or prolongation of existing hospitalization 
In general, hospitalization signifies that the participant has been detained (usually involving at least an 
overnight stay) at the hospital or emergency ward for observation and/or treatment that would not have 
been appropriate in the physician’s office or outpatient setting. Complications that occur during 
hospitalization are AEs. If a complication prolongs hospitalization or fulfills any other serious criteria, 
the event is serious. When in doubt as to whether “hospitalization” occurred or was necessary, the AE 
should be considered serious. 
Hospitalization for elective treatment of a pre-existing condition that did not worsen from baseline is 
not considered an AE. 
4. Results in persistent disability/incapacity 
• 
The term disability means a substantial disruption of a person’s ability to conduct normal life 
functions. 
• 
This definition is not intended to include experiences of relatively minor medical significance such 
as uncomplicated headache, nausea, vomiting, diarrhea, influenza, and accidental trauma (eg, 
sprained ankle) which may interfere with or prevent everyday life functions but do not constitute a 
substantial disruption. 
5. Is a congenital anomaly/birth defect 
6. Other situations: 
• 
Medical or scientific judgment should be exercised in deciding whether SAE reporting is 
appropriate in other situations such as important medical events that may not be immediately life-

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An SAE is defined as any untoward medical occurrence that, at any dose: 
threatening or result in death or hospitalization but may jeopardize the participant or may require 
medical or surgical intervention to prevent one of the other outcomes listed in the above 
definition. These events should usually be considered serious. 
• 
Examples of such events include invasive or malignant cancers, intensive treatment in an 
emergency room or at home for allergic bronchospasm, blood dyscrasias or convulsions that do 
not result in hospitalization, or development of drug dependency or drug abuse. 
 
A SUSAR is defined as: 
An event that is assessed as serious by the Investigator and/or Alexion that is not listed in the 
appropriate Reference Safety Information (IB) and has been assessed that there is at least a reasonable 
possibility that the event is related to the study intervention by the Investigator and/or Alexion. 
Alexion has procedures that will be followed for the recording, medical assessment, and expedited 
reporting of SUSARs that are consistent with global regulations, legislation, and guidance documents. 
 
Suspected unexpected serious adverse reactions will undergo expedited reporting to the national 
regulatory authorities, IRBs/IECs, and Investigators following local regulatory reporting requirements 
where applicable. 
10.3.3. 
Recording and Follow-Up of AE and/or SAE 
Recording of AE and/or SAE 
• 
When an AE/SAE occurs, it is the responsibility of the Investigator to review all documentation 
(eg, hospital progress notes, laboratory reports, and diagnostics reports) related to the event. 
• 
The Investigator will then record all relevant AE/SAE information in the eCRF. 
• 
It is not acceptable for the Investigator to send photocopies of the participant’s medical records to 
Alexion in lieu of completion of the Alexion AE/SAE eCRF page. 
• 
There may be instances when copies of medical records for certain cases are requested by 
Alexion. In this case, all participant identifiers, with the exception of the participant number, will 
be redacted on the copies of the medical records before submission to Alexion. 
• 
The Investigator will attempt to establish a diagnosis of the event based on signs, symptoms, 
and/or other clinical information. Whenever possible, the diagnosis (not the individual 
signs/symptoms) will be documented as the AE/SAE. 
Assessment of Intensity 
The Investigator will make an assessment of intensity for each AE and SAE reported during the study 
and assign it to one of the following categories from National Cancer Institute CTCAE v5.0, published 
27 Nov 2017: 
• 
Grade 1: Mild (awareness of sign or symptom, but easily tolerated) 
• 
Grade 2: Moderate (discomfort sufficient to cause interference with normal activities) 
• 
Grade 3: Severe (incapacitating, with inability to perform normal activities) 
• 
Grade 4: Life-threatening 
• 
Grade 5: Fatal 

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Recording of AE and/or SAE 
An event is defined as “serious” when it meets at least one of the predefined outcomes as described in 
the definition of an SAE, not when it is rated as severe. 
 
Assessment of Causality 
• 
The Investigator is obligated to assess the relationship between the study intervention and each 
occurrence of each AE or SAE. An Investigator causality assessment must be provided for all AEs 
(both nonserious and serious). This assessment must be recorded in the eCRF and on any 
additional forms, as appropriate. The definitions for the causality assessments are as follows: 
− 
Not related: There is no reasonable possibility the study intervention caused the AE. 
− 
The AE has a more likely alternative etiology; it may be due to 
underlying or concurrent illness, complications, concurrent treatments, or 
effects of another concurrent drug. 
− 
The event does not follow a reasonable temporal relationship to 
administration of the study intervention. 
− 
Related: There is a reasonable possibility the study intervention caused the AE. 
− 
The AE has a temporal relationship to the administration of the study 
intervention. 
− 
The event does not have a likely alternative etiology. 
− 
The event corresponds with the known pharmaceutical profile of the 
study intervention. 
− 
There is improvement on discontinuation and/or reappearance on 
rechallenge. 
• 
The Investigator will use clinical judgment to determine the relationship. 
• 
Alternative causes, such as underlying disease(s), concomitant therapy, and other risk factors, as 
well as the temporal relationship of the event to study intervention administration will be 
considered and investigated. 
• 
The Investigator will also consult the IB and/or Product Information, for marketed products, in 
his/her assessment. 
• 
For each AE/SAE, the Investigator must document in the medical notes that he/she has reviewed 
the AE/SAE and has provided an assessment of causality. 
• 
There may be situations in which an SAE has occurred, and the Investigator has minimal 
information to include in the initial report to Alexion. However, it is very important that the 
Investigator always make an assessment of causality for every event before the initial transmission 
of the SAE data to Alexion. 
• 
The Investigator may change his/her opinion of causality in light of follow-up information and 
send an SAE follow-up report with the updated causality assessment. 
• 
The causality assessment is one of the criteria used when determining regulatory reporting 
requirements. 
 
Follow-up of AEs and SAEs 
• 
The Investigator is obligated to perform or arrange for the conduct of supplemental 
measurements and/or evaluations as medically indicated or as requested by Alexion to elucidate 

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Follow-up of AEs and SAEs 
the nature and/or causality of the AE or SAE as fully as possible. This may include additional 
laboratory tests or investigations, histopathological examinations, or consultation with other 
health care professionals. 
• 
If a participant dies during participation in the study or during a recognized follow-up period, the 
Investigator will provide Alexion with a copy of any postmortem findings including 
histopathology. 
• 
New or updated information will be recorded in the originally completed eCRF. 
• 
The Investigator will submit any updated SAE data to Alexion within 24 hours of receipt of the 
information. 
10.3.4. 
Reporting of SAEs 
SAE Reporting to Alexion via an Electronic Data Collection Tool 
1. All SAEs will be recorded and reported to Alexion immediately and within 24 hours of 
awareness. 
2. The primary mechanism for reporting an SAE to Alexion will be the EDC system. 
3. If the electronic system is unavailable or site staff is unable to process the SAE via the EDC 
system at the time that the Investigator or site becomes aware of an SAE, the site will use the 
paper Contingency Form for SAE Reporting via facsimile or email. Facsimile transmission or 
email may also be used in the event of electronic submission failure. 
− 
Email: clinicalsae@alexion.com or Fax: + 1.203.439.9347 
4. The site will enter the SAE data into the EDC system as soon as it becomes available. 
5. When further information becomes available, the EDC should be updated immediately with the new 
information and an updated SAE report should be submitted to Alexion Global Drug Safety (GDS) within 
24 hours of Investigator/site awareness. 
6. After the participant has completed the study, no new data or changes to existing data are 
expected to be entered in the EDC system. 
a. If a site receives a report of a new SAE from a study participant which the Investigator 
considers to be related to the study intervention, or the site receives updated data on a 
previously reported SAE after the EDC system has been taken offline, then the site can 
report this information on a paper Contingency Form for SAE Reporting via facsimile or 
email. 
10.3.5. 
Unexpected Events 
Apart from the reporting of SUSARs, there may be other events which are relevant in terms of 
benefit-risk balance and which should be reported in a timely manner according to regional and 
national requirements. It is important for participant safety that, in addition to SAEs and 
reactions, all unexpected events that might materially influence the benefit-risk assessment of the 
study intervention or that would lead to changes in the administration of the study intervention or 
that would lead to changes in the administration of the study intervention or in overall conduct of 
a clinical trial should be reported. Examples of such unexpected events include an increase in the 
rate of occurrence of expected serious adverse reactions which may be clinically important, a 
significant hazard to the patient population, such as lack of efficacy of a medicinal product, or a 
major safety finding from a newly completed animal study (such as, carcinogenicity). 

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Under the EU CTR 536/2014 (49), where unexpected events require an urgent modification of a 
clinical trial, it should be possible for Alexion and the Investigator to take urgent safety measures 
without awaiting prior authorization. If such measures constitute a temporary halt of the clinical 
trial, Alexion should apply for a substantial modification before restarting the clinical trial.

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10.4. 
Medication Error, Drug Abuse, and Drug Misuse 
Medication Error 
For the purposes of this clinical study a medication error is an unintended failure or mistake in 
the treatment process for an IMP or Alexion AxMP that either causes harm to the participant or 
has the potential to cause harm to the participant. 
Any events of medication error, with or without associated AEs, are to be captured and 
forwarded to Alexion Global Patient Safety via email or facsimile (clinicalsae@alexion.com or 
+ 1.203.439.9347) using the Alexion Clinical Study Medication Error Report Form. 
A medication error is not lack of efficacy of the drug, but rather a human or process related 
failure while the drug is in control of the study site staff or participant. 
Medication error includes situations where an error: 
• Occurred 
• Was identified and intercepted before the participant received the drug 
• Did not occur, but circumstances were recognized that could have led to an error 
Examples of events to be reported in clinical studies as medication errors: 
• Drug name confusion 
• Dispensing error, eg, medication prepared incorrectly, even if it was not actually 
given to the participant 
• Drug not administered as indicated, eg, wrong route or wrong site of administration 
• Drug not taken as indicated, eg, tablet dissolved in water when it should be taken as a 
solid tablet 
• Drug not stored as instructed, eg, kept in the refrigerator when it should be at room 
temperature 
• Wrong participant received the medication (excluding IRT/Randomization and Trial 
Supply Management [RTSM] errors) 
• Wrong drug administered to participant (excluding IRT/RTSM errors) 
Examples of events that do not require reporting as medication errors in clinical studies: 
• Errors related to or resulting from IRT/RTSM – including those which led to one of 
the above listed events that would otherwise have been a medication error 
• Participant accidentally missed drug dose(s), eg, forgot to take medication 
• Accidental overdose (will be captured as an overdose, see Section 8.4) 
• Participant failed to return unused medication or empty packaging 
Medication errors are not regarded as AEs but AEs may occur as a consequence of the 
medication error. 

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Drug Abuse 
For the purpose of this study, drug abuse is defined as the persistent or sporadic intentional, 
non-therapeutic excessive use of IMP or Alexion AxMP for a perceived reward or desired 
non-therapeutic effect. 
Any events of drug abuse, with or without associated AEs, are to be captured and forwarded to 
Alexion Global Patient Safety via email or facsimile (clinicalsae@alexion.com or 
+ 1.203.439.9347) using the Alexion Clinical Study Drug Misuse or the Drug Abuse Form. This 
form should be used both if the drug abuse happened in a study participant or if the drug abuse 
involves a person not enrolled in the study (such as a relative of the study participant). 
Examples of drug abuse include but are not limited to: 
• The drug is used with the intent of getting a perceived reward (by the study 
participant or a person not enrolled in the study) 
• The drug in the form of a tablet is crushed and injected or snorted with the intent of 
getting high 
Drug Misuse 
Drug misuse is the intentional and inappropriate use of IMP or Alexion AxMP for medicinal 
purposes outside of the authorized product information, or for unauthorized IMPs or Alexion 
AxMPs, outside the intended use as specified in the protocol, including deliberate administration 
of the product by the wrong route. 
Events of drug misuse, with or without associated AEs, are to be captured and forwarded to 
Alexion Global Patient Safety via email or facsimile (clinicalsae@alexion.com or 
+ 1.203.439.9347) using the Alexion Clinical Study Drug Misuse or Drug Abuse Report Form. 
This form should be used both if the drug misuse happened in a study participant or if the drug 
misuse involves a person not enrolled in the study (such as a relative of the study participant). 
Examples of drug misuse include but are not limited to: 
• The drug is used with the intention to cause an effect in another person 
• The drug is sold to other people for recreational purposes 
• The drug is used to facilitate assault in another person 
• The drug is deliberately administered by the wrong route 
• The drug is split in half because it is easier to swallow, when it is stated in the 
protocol that it must be swallowed whole 
• Only half the dose is taken because the study participant feels that he/she is feeling 
better when not taking the whole dose 
• Someone who is not enrolled in the study intentionally takes the drug 
 

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10.5. 
Contraceptive Guidance and Collection of Pregnancy Information 
10.5.1. 
Definitions 
Woman of Childbearing Potential (WOCBP) 
A woman is considered fertile following menarche and until becoming postmenopausal unless 
permanently sterile (see below). 
If fertility is unclear (eg, amenorrhea in adolescents or athletes) and a menstrual cycle cannot be 
confirmed before first dose of study intervention, additional evaluation should be considered. 
Women in the Following Categories Are Not Considered WOCBP 
1. Premenarchal 
2. Premenopausal female with one of the following: 
• Documented hysterectomy 
• Documented bilateral tubal ligation or bilateral salpingectomy 
• Documented bilateral oophorectomy 
For individuals with permanent infertility due to an alternate medical cause other than the 
above, (eg, Mullerian agenesis, androgen insensitivity), Investigator discretion should be 
applied to determining study entry. 
Note: Documentation can come from the site personnel’s review of the participant’s 
medical records, medical examination, or medical history interview. 
3. Postmenopausal female 
• A postmenopausal state is defined as no menses for 12 months without an alternative 
medical cause prior to the Day 1 Visit. 
− A high FSH level in the postmenopausal range may be used to confirm a 
postmenopausal state in women not using hormonal contraception or HRT. 
However, in the absence of 12 months of amenorrhea, confirmation with more 
than one FSH measurement may be required. In the absence of 12 months of 
amenorrhea the reason for not obtaining FSH levels should be documented by the 
Investigator at the time of the Screening Visit. 
• Females on HRT and whose menopausal status is in doubt will be required to use one 
of the non-estrogen hormonal highly effective contraception methods if they wish to 
continue their HRT during the study. Otherwise, they must discontinue HRT to allow 
confirmation of postmenopausal status before study enrollment. 
4. Permanent sterilization at least 6 weeks prior to the Day 1 Visit. 
10.5.2. 
Contraception Guidance 
Contraceptive use by male or female participants should be consistent with local regulations 
regarding the methods of contraception utilized for those participating in clinical studies. If 
teratogenic effects are suspected to be transferred to a fetus/embryo from a female spouse/partner 

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of a male participant, pregnancy follow-up information will be obtained for the partner who 
becomes pregnant (refer to Section 10.5.3.1). In these cases, follow-up will be conducted on the 
pregnant partner in the same manner as a female participant who becomes pregnant during the 
study. 
10.5.2.1. Guidance for Female Participants 
Female participants of childbearing potential must have a negative serum pregnancy test as 
required by local regulations at the Screening Visit and a negative urine pregnancy test before 
the first dose of study intervention on Day 1. Additional requirements for pregnancy testing 
during and after dosing with study intervention are indicated in the SoAs (Table 2, Table 3, and 
Table 4). 
The Investigator is responsible for the review of medical history, menstrual history, and recent 
sexual activity to decrease the risk for inclusion of a woman with an early undetected pregnancy. 
The Investigator should evaluate the potential for contraceptive method in relationship to the first 
dose of study intervention. 
Female participants of childbearing potential must use a highly effective method of 
contraception, including at least 1 of the following until at least 30 days after the final dose of 
study intervention. 
1. Intrauterine device in place for at least 6 weeks prior to first dose of study intervention. 
2. Progestogen-only hormonal contraception associated with inhibition of ovulation (either 
oral, injectable, or implantable) for at least 6 weeks prior to first dose of study 
intervention. 
3. Intrauterine progestogen releasing system for at least 6 weeks prior to first dose of study 
intervention. 
4. Bilateral tubal occlusion for at least 6 weeks prior to first dose of study intervention. 
5. Combined (estrogen- and progestogen containing) hormonal contraception (either oral, 
intravaginal, or transdermal) for at least 6 weeks prior to first dose of study intervention. 
6. Surgical sterilization of the male partner (medical assessment of azoospermia is required 
if vasectomy was performed within 6 months prior to first dose of study intervention). 
Male partner is still required to use condom during sexual intercourse. 
7. Sexual abstinence for female participants: 
a. Sexual abstinence is considered a highly effective method only if defined as 
refraining from heterosexual intercourse. In this study, abstinence is only acceptable 
if consistent with the participant’s preferred and usual lifestyle. Abstinent female 
participants must refrain from heterosexual intercourse for at least 30 days after the 
final dose of study intervention. 
Female participants must not donate ova from the Day 1 Visit at least until 30 days after their 
final dose of study intervention. 
The following methods are considered unacceptable (not allowed) in this study: 
− Periodic abstinence (calendar, symptothermal, or post-ovulation methods) 

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− Withdrawal (coitus interruptus) 
− Spermicides only 
− Lactational amenorrhea method 
− Female condom and male condom should not be used together 
10.5.2.2. Guidance for Male Participants 
Contraception is the responsibility of the heterosexually active male participants in the study, 
regardless of his female partner’s method of contraception. 
Male participants who have had a vasectomy > 6 months prior to the first dose of study 
intervention must use a condom during heterosexual intercourse. Male participants who have had 
a vasectomy < 6 months prior to the first dose study intervention and those who have not had a 
vasectomy must use a condom (with or without spermicide) during heterosexual intercourse for 
at least 90 days (ie, 1 spermatogenesis cycle) after their final dose of study intervention. 
10.5.2.2.1. Sexual Abstinence for Male Participants 
Sexual abstinence is considered a highly effective method only if defined as refraining from 
heterosexual intercourse. In this study, abstinence is only acceptable if consistent with the 
participant’s preferred and usual lifestyle. Abstinent male participants who become 
heterosexually active must use a condom and spermicide during intercourse. 
Periodic abstinence (eg, calendar, symptothermal, or post ovulation methods for a female 
partner) is not considered a highly effective method of contraception for male participants. 
Male participants must not donate sperm from the Day 1 Visit until 90 days after their final dose 
of study intervention. 
10.5.3. 
Collection of Pregnancy Information 
Pregnancy data will be collected during this study for all female participants, and female 
spouses/partners of male participants, from the first dose of study intervention until the last study 
visit. Any female participant who becomes pregnant during the study will be discontinued from 
the study intervention and withdrawn from the study. Exposure during pregnancy (also referred 
to as exposure in utero) can be the result of either maternal exposure or transmission of study 
intervention via semen following paternal exposure. If a female participant or a male 
participant’s female spouse/partner becomes pregnant during the conduct of this study, the 
Investigator must submit the “Pregnancy/Breastfeeding Reporting and Outcome Form” to 
Alexion GDS via facsimile or email. 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 study intervention during breastfeeding must also be reported (via the 
“Pregnancy/Breastfeeding Reporting and Outcome Form”) and any AEs experienced by the 
infant must be reported to Alexion GDS via email or facsimile. 
Pregnancy is not regarded as an AE unless there is a suspicion that the study intervention may 
have interfered with the effectiveness of a contraceptive medication. However, complications of 

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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. 
10.5.3.1. Male Participants with Partners Who Become Pregnant 
• The Investigator will attempt to collect pregnancy information on any male 
participant’s female partner who becomes pregnant while the male participant is in 
this study. This applies only to male participants who receive study intervention. 
• After obtaining the necessary signed informed consent from the pregnant female 
partner directly, the Investigator will record pregnancy information on the appropriate 
“Pregnancy/Breastfeeding Reporting and Outcome Form” and submit it to Alexion 
within 24 hours of learning of the partner’s pregnancy. The female partner will also 
be followed to determine the outcome of the pregnancy. Information on the status of 
the mother and child will be forwarded to Alexion. Generally, the follow-up will be 
no longer than 3 months following the delivery date. Any termination of the 
pregnancy will be reported regardless of fetal status (presence or absence of 
anomalies) or indication for the procedure. 
10.5.3.2. Female Participants Who Become Pregnant 
• The Investigator will collect pregnancy information on any female participant who 
becomes pregnant while participating in this study. The initial Information will be 
recorded on the appropriate form and submitted to Alexion within 24 hours of 
learning of a participant’s pregnancy. 
• For all Alexion products, both in development or postapproval, 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 participant discontinues the study intervention 
or withdraws from the study. The Investigator will collect follow-up information on 
the participant and the neonate and the information will be forwarded to Alexion. 
Generally, follow-up will not be required for longer than 3 months beyond the 
estimated delivery date. Any termination of pregnancy will be reported, regardless of 
fetal status (presence or absence of anomalies) or indication for the procedure. 
• Pregnancy is not considered as an AE unless there is a suspicion that the study 
intervention may have interfered with the effectiveness of a contraceptive medication. 
While pregnancy itself is not considered to be an AE or SAE, any pregnancy 
complication or elective termination of a pregnancy for medical reasons will be 
reported as an AE or SAE. A spontaneous abortion (occurring at < 22 weeks 
gestational age) or still birth (occurring at > 22 weeks gestational age) is always 
considered to be an SAE and will be reported as such. Any poststudy 
pregnancy-related SAE considered reasonably related to the study intervention by the 
Investigator will be reported to Alexion. While the Investigator is not obligated to 
actively seek this information in former study participants, he or she may learn of a 
TESAE through spontaneous reporting. 

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• Any female participant who becomes pregnant during the study will discontinue 
study intervention and be discontinued from the study.

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10.6. 
Biomarkers 
• Blood biomarker matrix samples will be collected for biomarker analyses and the data 
will be used for research (eg, exploratory) related to study intervention or gMG and 
related diseases. The samples may also be used to develop tests/assays including 
diagnostic tests related to study intervention and gMG. 
• The samples may be analyzed as part of a multistudy assessment of biomarkers in the 
response to the study intervention or to understand gMG or related conditions. 
• The results of biomarker analyses may be reported in the clinical study report or in a 
separate report. 
• Alexion or designee will store the samples obtained for biomarker analyses in a 
secure storage space with adequate measures to protect confidentiality. 
• The samples will be retained while research on study intervention continues but no 
longer than 5 years after all data have been collected for the study or other 
period/time point per local requirements. 
 

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10.7. 
Management of Seizures 
Seizure is considered a potential risk that is to be closely monitored in participants. Seizures are 
defined as a transient occurrence of clinical signs and/or symptoms that are due to abnormal 
excessive or synchronous neuronal activity in the brain. 
Convulsions and/or electroencephalogram (EEG) abnormalities have been observed during dog 
and mouse repeat-dose toxicology studies. The dog is the most sensitive nonclinical species 
studied, and the NOAEL based on the dog 13-week toxicology study is 62.5 mg/kg/day. 
Should a suspected seizure occur during the study, the following procedures should be 
performed: 
• Participants and/or family members should be instructed to call an ambulance or 
report to a medical facility if the participant experiences a seizure. In general, most 
seizures are self-limiting and do not require acute pharmacologic intervention. 
• For seizures that are not self-limiting, the participant should be treated medically 
according to local protocols for ongoing seizure. 
• Participants and family members should be instructed to call the Investigator to 
inform them of the seizure. 
• Treatment with study intervention should be suspended until a complete work up is 
performed. 
• The following assessments are recommended for all participants with suspected 
seizure: 
− Blood samples should be taken to evaluate electrolytes (including calcium and 
magnesium), glucose, complete blood count, renal function tests, liver function 
tests, creatine kinase, toxicology screen, ethanol level, and serum lactate. Any 
other tests or investigations determined to be pertinent should also be performed 
(eg, brain imaging, blood, and urine cultures). 
− Blood samples should be taken to evaluate PK levels. 
− An EEG should be performed. 
• If the etiology of the seizure is assessed as related to the study intervention, the study 
intervention will be discontinued, and the participant will be also discontinued from 
the study. 
• If an alternative cause for the seizure is determined, dosing with study intervention 
may resume as deemed appropriate by the Investigator in consultation with the 
Medical Monitor. 
Any event of seizure or suspected seizure must be reported to Alexion within 24 hours of the 
Investigator’s awareness as a TESAE. The following clinical information in addition to the 
above recommended assessments should also be collected: 
• Seizure start date and time 
• Description of the seizure 

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− The type of seizure (eg, generalized tonic-clonic seizure, partial seizure) 
− A detailed description of what the participant was doing before, during, and after 
each seizure. If possible, describe all aspects from start to end. 
− What was the earliest sign of seizure onset? 
− Duration of seizure(s) 
− Was the participant unconscious, unaware, or confused? 
− Was there evidence of bowel or bladder dysfunction? 
− Post-ictal period duration and signs 
− Neurologic examination findings 
− EEG results 
− Evidence of injury from the seizure (eg, tongue bites, bruises, or other injuries) 
− How did the participant recover after the seizure? 
• Document identifiable seizure triggers 
− Was there any recognizable trigger that may have provoked the seizures for the 
participant? Please include any recent medication changes, illness, or sleep 
deprivation. 
− Was there any history of alcohol or drug use, or recent discontinuation of alcohol 
use? 
• Past medical and surgical history review 
− Is there relevant medical history? 
− Document concomitant medications

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10.8. 
Participant-Reported Outcome Instruments 
Participant-reported Outcomes or Clinician-reported Outcomes (Clinical Outcome Assessments) 
may be collected electronically.

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10.9. 
COVID-19 Risk Assessment 
Generalized MG is a debilitating chronic disease sometimes associated with severe generalized 
weakness requiring intubation for mechanical ventilation or the prevention of aspiration 
(Jaretzki, 2000). As such, and due to the limited number of available treatment options, the 
benefit a participant may receive from joining an investigational study with a therapeutic 
treatment is potentially significant. In this particular case, the fact that the study contains an ETP 
and an OLE Period, where every participant is treated with the study intervention, also 
contributes to the potential benefit a participant may derive from partaking in the study. Given 
that treatment for gMG does involve immunosuppression in many patients, there is a theoretical 
concern that the risk for infection may be higher than in participants not receiving 
immunosuppressants. However, there is no specific data to further inform this risk. The site 
Investigator will therefore balance the risk/benefit considerations in the study participant taking 
these factors into account. 
Table 12: Potential Risks and Mitigation Measures due to COVID-19 
Risks category 
Summary of Data/ 
Rationale for Risk 
Mitigation Strategy 
Potential risks 
Healthcare 
institution 
availability for 
non-COVID-19 
related activities  
The COVID-19 pandemic may impact the 
workload of healthcare institutions globally and 
may reduce staff availability to perform 
non-urgent activities and non-COVID-19 
related activities. 
 
During the time that the 
COVID-19 pandemic is 
active, Alexion will not open 
study sites or enroll new 
participants at sites unless 
the sites have the resourcing 
and capabilities to implement 
the study per protocol. 
Data quality and 
integrity 
Lack of availability of site personnel to perform 
study assessments and capture study specific 
data in a timely manner and to maintain 
adequate quality standards. 
Lack of availability of site personnel to ensure 
adequate and continuous chain of custody, 
storage conditions, and monitoring for 
investigational product and biological samples. 
Inability of study monitors and quality 
personnel to conduct in-person visits to exercise 
adequate oversight of study execution at 
investigational sites. 
Missing data (the COVID-19 pandemic may 
impact study visit schedules and increase 
missed visits and/or participant study 
discontinuations inadvertently resulting in 
During the time that the 
COVID-19 pandemic is 
active, Alexion will only 
open study sites that report 
enough personnel capacity to 
sufficiently conduct clinical 
study-related activities. 
During this timeframe, site 
capacity will be reviewed by 
the site Investigator and the 
study Medical Monitor prior 
to Screening. Each site is 
also evaluated for the 
capacity to perform remote 
monitoring visits and remote 
source data verification. 

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Table 12: Potential Risks and Mitigation Measures due to COVID-19 
Risks category 
Summary of Data/ 
Rationale for Risk 
Mitigation Strategy 
missing data [eg, for protocol-specified 
procedures]). 
During the time that the 
COVID-19 pandemic is 
active, it will be important to 
capture specific information 
in the eCRF that explains the 
reason the data is missing 
(eg, missed study visits or 
participant study 
discontinuations due to 
COVID-19). 
Abbreviations: COVID-19 = coronavirus disease 2019; eCRF = electronic case report form 

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10.10. 
Prohibited Inducers, Inhibitors, and Substrates of CYP3A 
Table 13: List of Prohibited Inducers, Inhibitors, and Substrates of CYP3A 
Classification 
 
Medication 
Table Numbera 
Strong CYP3A 
inhibitors 
boceprevir, cobicistat, danoprevir and ritonavir, 
elvitegravir and ritonavir, grapefruit juice, indinavir and 
ritonavir, itraconazole, ketoconazole, lopinavir and 
ritonavir, paritaprevir and ritonavir and (ombitasvir 
and/or dasabuvir), posaconazole, ritonavir, saquinavir 
and ritonavir, telaprevir, tipranavir and ritonavir, 
telithromycin, troleandomycin, voriconazole, 
clarithromycin, idelalisib, nefazodone, and nelfinavir 
3-2 
Moderate CYP3A 
inhibitors 
aprepitant, ciprofloxacin, conivaptan, crizotinib, 
cyclosporine, diltiazem, dronedarone, erythromycin, 
fluconazole, fluvoxamine, imatinib, tofisopam, and 
verapamil 
3-2 
Strong inducers of 
CYP3A 
apalutamide, carbamazepine, enzalutamide, mitotane, 
phenytoin, rifampin, and St. John’s wort 
3-3 
Moderate inducers of 
CYP3A 
bosentan, efavirenz, etravirine, phenobarbital, and 
primidone 
3-3 
Sensitive substrates of 
CYP3A 
alfentanil, avanafil, buspirone, conivaptan, darifenacin, 
darunavir, ebastine, everolimus, ibrutinib, lomitapide, 
lovastatin, midazolam, naloxegol, nisoldipine, 
saquinavir, simvastatin, sirolimus, tacrolimus, 
tipranavir, triazolam, vardenafil, budesonide, dasatinib, 
dronedarone, eletriptan, eplerenone, felodipine, 
indinavir, lurasidone, maraviroc, quetiapine, sildenafil, 
ticagrelor, tolvaptan 
3-1 
a Table number from the US FDA Table of Clinical CYP Inhibitors and Inducers 
Note: This list is complete as of 25 Jan 2021. Please visit the link below for the most up-to-date information. 
http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm09
3664.htm. 
Abbreviation: CYP3A = cytochrome P450, family 3, subfamily A 

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10.11. 
Selected Medications Known to Lower the Seizure Threshold and/or 
Cause Seizure 
The following medications are PROHIBITED while on the study: 
• Meperidine/pethidine 
• Tramadol 
• Typical (1st generation) antipsychotics 
• Clozapine 
• Olanzapine 
• Lithium 
• Tricyclic antidepressants 
• Bupropion 
• Aminophylline/Theophylline 

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10.12. 
COVID-19 Vaccine Risk Assessment 
Following a review of the available COVID-19 vaccine data (eg, Pfizer/BioNTech, Moderna, 
AstraZeneca, and Johnson & Johnson), it is unlikely that the immune response to a COVID-19 
vaccine (and therefore the efficacy of the vaccination) would be diminished with concomitant 
ALXN2050 administration, based on ALXN2050’s mechanism of action. There is currently no 
information available evaluating the safety and efficacy of COVID-19 vaccines in participants 
treated with ALXN2050. The same precautions should be taken as described in Section 6.5.4. 
Vaccination may further activate complement. As a result, patients with complement-mediated 
diseases may experience increased signs and symptoms of their underlying disease. If possible, 
consider vaccination when the underlying complement mediated disease is clinically controlled. 
Patients should be closely monitored for disease symptoms after recommended vaccination. 
Local and national guidelines should be consulted for recommendations related to COVID-19 
vaccination. 
The potential risks identified and mitigation measures put in place in light of the COVID-19 
vaccination rollout are provided in Table 14. 
Table 14: Potential Risks and Mitigation Measures due to COVID-19 Vaccine 
Risks category 
Summary of Data/Rationale for Risk 
Mitigation Strategy 
Potential risks 
Data quality and 
integrity 
Missing data due to appointments for 
COVID-19 vaccination or side effects of 
COVID-19 vaccine may impact study visit 
schedules, and increase missed visits and/or 
participant study discontinuations, 
inadvertently resulting in missing data (eg, 
for protocol-specified procedures). 
Capture specific information in 
the eCRF that explains the 
reason the data is missing (eg, 
missed study visits due to 
appointments for COVID-19 
vaccination or side effects of 
COVID-19 vaccine)  
Abbreviations: COVID-19 = coronavirus disease 2019; eCRF = electronic case report form 
 

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10.13. 
Protocol Amendment History 
The Protocol Amendment Summary of Changes Table for the current amendment is located 
directly after the List of Figures. 
DOCUMENT HISTORY 
Document 
Date 
Overall Rationale for the Amendment 
Original Protocol 
28 Apr 2021 
Not applicable 
Protocol Amendment 1 (Global) 
22 Jul 2021 
Update the list of exclusion criteria with a renal 
impairment criterion and to indicate that 
medications known to significantly prolong the 
corrected QT interval are not allowed during the 
study 
Protocol Amendment 1.1 (Germany) 02 Jun 2022 
Germany-specific amendment to incorporate, 
where appropriate, the changes made at the 
request of the Ethics Committee of the State of 
Berlin. The informed consent process, participant 
withdrawal, study/site closure, statistical 
interpretation and primary analyses were clarified 
further or modified. 
Protocol Amendment 1.2 (Serbia) 
26 Jul 2022 
Serbia-specific amendment to update the 
informed consent process, participant withdrawal, 
study/site closure, statistical interpretation, and 
primary analyses. 
Protocol Amendment 2 (Global) 
09 Mar 2023 The primary reason for this amendment was to 
address the requirements for conducting a clinical 
study under the EU CTR. 
Protocol Amendment 3 (Global) 
15 Nov 2023 The primary reason for this amendment was to 
address the requirements for transitioning a 
clinical study under the EU CTR. 

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11. 
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