A Phase 3, Randomized, Open-Label, Parallel-Group Study to Compare the Pharmacodynamics, Pharmacokinetics, Efficacy, Safety, Tolerability, and Immunogenicity of Multiple Subcutaneous Injections of Efgartigimod PH20 SC With Multiple Intravenous Infusions of Efgartigimod in Patients With Generalized Myasthenia Gravis
Phase: PHASE3
Conditions: Generalized Myasthenia Gravis
Sponsor: argenx

Clinical Study Protocol ARGX-113-2001 v2.0 
02 Jul 2021
Efgartigimod IV and SC 
argenx BV 
Confidential
1
TITLE PAGE 
Protocol Title: 
A Phase 3, Randomized, Open-Label, Parallel-Group Study to Compare the Pharmacodynamics, 
Pharmacokinetics, Efficacy, Safety, Tolerability, and Immunogenicity of Multiple Subcutaneous 
Injections of Efgartigimod PH20 SC With Multiple Intravenous Infusions of Efgartigimod in 
Patients With Generalized Myasthenia Gravis 
 
Protocol Number: ARGX-113-2001 
Amendment Number: 1 
Compound: Efgartigimod 
Brief Title: Evaluating the Pharmacodynamic Noninferiority of Efgartigimod PH20 
Administered Subcutaneously as Compared to Efgartigimod Administered Intravenously in 
Patients With Generalized Myasthenia Gravis 
Study Phase: 3 
Acronym: ADAPTSC 
Sponsor Name: argenx BV 
Legal Registered Address:  
Industriepark Zwijnaarde 7 
9052 Zwijnaarde (Ghent) 
Belgium 
Phone: +32 9 310 34 00 
Fax: +32 9 310 34 99 
Regulatory Agency Identifier Number(s):  
IND: 
 
EudraCT: 2020-004085-19 
Approval Date: 02 Jul 2021 
 
 

Clinical Study Protocol ARGX-113-2001 v2.0 
02 Jul 2021 
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DOCUMENT HISTORY 
Document 
Date 
Amendment 1 
02 Jul 2021 
Original Protocol 
15 Oct 2020 
Amendment 1 (02 Jul 2021) 
This amendment is considered to be substantial 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. 
Overall Rationale for the Amendment: 
Increase sample size from 46-76 participants to approximately 110 participants. Minor editorial 
changes, including the correction of typographical errors and formatting inconsistencies, are not 
summarized. 
Protocol Amendment Summary of Changes Table    
Section # and 
Name 
Description of Change 
Brief Rationale 
Drug Safety 
Reporting 
Updated information: 
Email:
  
Toll-free Fax: 
  
The email address and fax number for 
drug safety reporting have been updated. 
1.1 Synopsis 
9.2 Sample Size 
Determination 
Increase sample size to approximately 
110 participants 
Although 76 participants would provide 
enough data to establish non-inferiority 
between SC and IV formulations based 
on IgG reduction at day 29, the increase 
in sample size to approximately 110 
participants will allow better 
quantification of the clinical safety and 
efficacy profile of the SC formulation in 
patients with gMG while the IV 
formulation will serve as a reference 
treatment in this randomized study.  
2.3.1 
Efgartigimod 
Risk 
Assessment 
Section 11 
References 
Updated text: 
Participants who are women of 
childbearing potential (WOCBP) must 
use highly effective or acceptable 
method of contraception (see inclusion 
criterion 8 and Section 10.5) 
The potential risk to 
teratogenicity/fetotoxicity mitigation 
strategy was updated to align with the 
current Investigator’s Brochure (IB) (IB 
version 9.0). However, in this protocol 
amendment, the contraception 
requirements are unchanged from the 
original protocol dated 15 Oct 2020. 
Additionally, the IB reference was 
updated to reflect the current version.  
6.8.3 Prohibited 
Medication and 
Procedures 
Updated text:  
PLEX, Ig therapy (IVIg and SCIg), 
immunoadsorption, or a change in 
The text was updated for alignment 
throughout the protocol because any type 
of immunoglobulin therapy, regardless 

Clinical Study Protocol ARGX-113-2001 v2.0 
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Section # and 
Name 
Description of Change 
Brief Rationale 
dosage or type of corticosteroid are 
considered rescue therapy if both of the 
following conditions apply: 
of the formulation, is considered rescue 
therapy.  
8.2.6 Clinical 
Safety 
Laboratory 
Assessments 
Updated text: 
The actual sample collection date and 
time must be collected in the 
participant’s source document and 
included in the central laboratory data 
transfer. 
As the sample collection date and time is 
already collected on the central lab 
requisition forms and loaded into the 
database from the lab data transfer, there 
is no need to collect this data on the 
laboratory assessment eCRF page in 
duplicate 
10.1.3 Informed 
Consent Process 
Updated text: 
Prior to signing the ICF, the study 
participants will be instructed not to 
participate in any other clinical study 
that involves a therapeutic intervention 
until the completion of the study. 
It is not required to exclude or 
discontinue participants who are 
participating in a study that does not 
involve another intervention because this 
does not constitute a safety concern for 
participants. 
10.4.2 
Definition of 
SAE 
Removed text: 
An SAE is defined as any untoward 
medical occurrence that, at any dose: Is 
a suspected transmission of any 
infectious agent via an authorized 
medicinal product 
This item does not need to be considered 
an SAE in this study, and as such this 
item must be disregarded. 
10.7.3.5 
Mandatory Site 
Visits and Home 
Visits 
Removed text: 
If needed, all of the previously listed 
visits can be performed by a home nurse 
except the screening visit. 
Home nurse services are not a part of this 
study, so this sentence must be 
disregarded. 

Clinical Study Protocol ARGX-113-2001 v2.0 
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TABLE OF CONTENTS 
DOCUMENT HISTORY .................................................................................................................3 
Protocol Amendment Summary of Changes Table .........................................................................3 
1. 
PROTOCOL SUMMARY ..........................................................................................10 
1.1. 
Synopsis ......................................................................................................................10 
1.2. 
Schema ........................................................................................................................15 
1.3. 
Schedule of Activities .................................................................................................16 
2. 
INTRODUCTION ......................................................................................................20 
2.1. 
Study Rationale ...........................................................................................................20 
2.2. 
Background .................................................................................................................20 
2.3. 
Benefit/Risk Assessment ............................................................................................21 
2.3.1. 
Efgartigimod Risk Assessment ...................................................................................21 
2.3.2. 
Efgartigimod Benefit Assessment ..............................................................................22 
2.3.3. 
rHuPH20 Risk Assessment .........................................................................................23 
2.3.4. 
rHuPH20 Benefit Assessment ....................................................................................24 
2.3.5. 
Overall Benefit/Risk Conclusion ................................................................................24 
3. 
OBJECTIVES AND ENDPOINTS ............................................................................25 
4. 
STUDY DESIGN .......................................................................................................27 
4.1. 
Overall Design ............................................................................................................27 
4.2. 
Scientific Rationale for Study Design ........................................................................27 
4.3. 
Justification for Dose ..................................................................................................28 
4.4. 
End of Study Definition ..............................................................................................28 
5. 
STUDY POPULATION .............................................................................................29 
5.1. 
Inclusion Criteria ........................................................................................................29 
5.2. 
Exclusion Criteria .......................................................................................................30 
5.3. 
Lifestyle Considerations .............................................................................................32 
5.3.1. 
Meals and Dietary Restrictions ...................................................................................32 
5.4. 
Screen Failures ............................................................................................................32 
5.5. 
Criteria for Temporarily Delaying Administration of Study Intervention .................33 
6. 
STUDY INTERVENTION(S) AND CONCOMITANT THERAPY ........................34 
6.1. 
Study Intervention(s) Administered ...........................................................................34 
6.2. 
Preparation/Handling/Storage/Accountability ............................................................34 

Clinical Study Protocol ARGX-113-2001 v2.0 
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6.2.1. 
Preparation ..................................................................................................................35 
6.2.2. 
Handling .....................................................................................................................35 
6.2.3. 
Storage ........................................................................................................................35 
6.2.4. 
Accountability .............................................................................................................35 
6.3. 
Measures to Minimize Bias: Randomization and Blinding ........................................35 
6.4. 
Study Intervention Compliance ..................................................................................36 
6.4.1. 
Handling Missed Doses of the IMP ............................................................................37 
6.4.2. 
Protocol Deviations ....................................................................................................37 
6.5. 
Dose Modification ......................................................................................................37 
6.6. 
Continued Access to Study Intervention After the End of the Study .........................37 
6.7. 
Treatment of Overdose ...............................................................................................37 
6.8. 
Concomitant Therapy .................................................................................................37 
6.8.1. 
Prior Medication and Procedures ................................................................................38 
6.8.2. 
Permitted Concomitant Medication and Procedures ..................................................38 
6.8.3. 
Prohibited Medication and Procedures .......................................................................38 
7. 
DISCONTINUATION OF STUDY INTERVENTION AND 
PARTICIPANT DISCONTINUATION/WITHDRAWAL .......................................40 
7.1. 
Discontinuation of Study Intervention ........................................................................40 
7.2. 
Participant Discontinuation/Withdrawal From the Study ...........................................40 
7.3. 
Lost to Follow-up .......................................................................................................41 
8. 
STUDY ASSESSMENTS AND PROCEDURES ......................................................42 
8.1. 
Efficacy Assessments .................................................................................................42 
8.1.1. 
Pharmacodynamics .....................................................................................................42 
8.1.2. 
Clinical Efficacy Assessments ....................................................................................42 
8.1.2.1. 
MG-ADL ....................................................................................................................42 
8.1.2.2. 
QMG ...........................................................................................................................43 
8.1.3. 
Myasthenia Gravis Quality of Life Questionnaire (15-item Scale Revised) ..............43 
8.1.4. 
EuroQoL 5 Dimensions 5 Levels ...............................................................................43 
8.2. 
Safety Assessments .....................................................................................................44 
8.2.1. 
Demographics .............................................................................................................44 
8.2.2. 
Physical Examinations ................................................................................................44 
8.2.3. 
Vital Signs ..................................................................................................................45 
8.2.4. 
Electrocardiograms .....................................................................................................45 

Clinical Study Protocol ARGX-113-2001 v2.0 
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8.2.5. 
Medical and Surgical History .....................................................................................45 
8.2.6. 
Clinical Safety Laboratory Assessments ....................................................................45 
8.2.6.1. 
Hematology, Clinical Chemistry, and Urinalysis .......................................................46 
8.2.6.2. 
Virus Serology ............................................................................................................47 
8.2.6.3. 
Follicle-Stimulating Hormone Level ..........................................................................47 
8.2.6.4. 
SARS-CoV-2 Test ......................................................................................................47 
8.2.7. 
Assessment of Administration Site .............................................................................47 
8.2.8. 
Pregnancy Testing ......................................................................................................47 
8.2.9. 
Immunogenicity ..........................................................................................................47 
8.2.9.1. 
ADA Against Efgartigimod ........................................................................................47 
8.2.9.2. 
ADA Against rHuPH20 ..............................................................................................48 
8.2.10. 
Suicidal Ideation and Behavior Risk Monitoring .......................................................48 
8.3. 
Adverse Events (AEs), Serious Adverse Events (SAEs), and Other Safety 
Reporting ....................................................................................................................49 
8.3.1. 
Time Period and Frequency for Collecting AE and SAE Information .......................49 
8.3.2. 
Method of Detecting AEs and SAEs ..........................................................................49 
8.3.3. 
Follow-up of AEs and SAEs .......................................................................................50 
8.3.4. 
Regulatory Reporting Requirements for SAEs ...........................................................50 
8.3.5. 
Pregnancy ...................................................................................................................50 
8.3.6. 
Adverse Events of Special Interest .............................................................................51 
8.4. 
Pharmacokinetics ........................................................................................................51 
8.5. 
Genetics and/or Pharmacogenomics ...........................................................................52 
8.6. 
Biomarkers ..................................................................................................................52 
8.7. 
Immunogenicity Assessments ....................................................................................52 
8.8. 
Medical Resource Utilization and Health Economics ................................................52 
8.9. 
Storage of Blood Samples After the Study .................................................................52 
9. 
STATISTICAL CONSIDERATIONS .......................................................................54 
9.1. 
Statistical Hypotheses .................................................................................................54 
9.2. 
Sample Size Determination ........................................................................................54 
9.3. 
Analysis Sets ...............................................................................................................56 
9.4. 
Statistical Analyses .....................................................................................................56 
9.4.1. 
General Considerations ...............................................................................................57 
9.4.2. 
Primary Endpoint ........................................................................................................57 

Clinical Study Protocol ARGX-113-2001 v2.0 
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9.4.3. 
Secondary Endpoints ..................................................................................................58 
9.4.4. 
Exploratory Endpoints ................................................................................................58 
9.5. 
Interim Analysis ..........................................................................................................58 
10. 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS ..................................................................................................59 
10.1. 
Appendix 1: Regulatory, Ethical, and Study Oversight Considerations ....................59 
10.1.1. 
Regulatory and Ethical Considerations ......................................................................59 
10.1.2. 
Financial Disclosure ...................................................................................................59 
10.1.3. 
Informed Consent Process ..........................................................................................60 
10.1.4. 
Data Protection ...........................................................................................................61 
10.1.5. 
Committees Structure .................................................................................................61 
10.1.5.1. 
Data Safety Monitoring Board ....................................................................................61 
10.1.6. 
Dissemination of Clinical Study Data ........................................................................62 
10.1.7. 
Data Quality Assurance ..............................................................................................62 
10.1.7.1. 
Data Handling and Record Keeping ...........................................................................63 
10.1.7.2. 
Quality Assurance Audit .............................................................................................63 
10.1.7.3. 
Quality Control ...........................................................................................................63 
10.1.8. 
Source Documents ......................................................................................................64 
10.1.9. 
Study and Site Start and Closure ................................................................................65 
10.1.10. 
Publication Policy .......................................................................................................65 
10.2. 
Appendix 2: Clinical Laboratory Tests .......................................................................67 
10.3. 
Appendix 3: Total Blood Volume Collected From Each Participant .........................69 
10.4. 
Appendix 4: AEs and SAEs: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting ........................................................................70 
10.4.1. 
Definition of AE .........................................................................................................70 
10.4.2. 
Definition of SAE .......................................................................................................71 
10.4.3. 
Recording and Follow-up of AEs and/or SAEs ..........................................................71 
10.4.4. 
Reporting of SAEs ......................................................................................................73 
10.5. 
Appendix 5: Contraceptive and Barrier Guidance ......................................................74 
10.5.1. 
Definitions ..................................................................................................................74 
10.6. 
Appendix 6: Administrative Structure ........................................................................77 
10.7. 
Appendix 7: Possible Adaptations to Study Protocol During the COVID-19 
Pandemic .....................................................................................................................79 

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10.7.1. 
COVID-19 Risk Assessment for Participant Safety ...................................................79 
10.7.2. 
COVID-19 Risk Mitigation ........................................................................................79 
10.7.3. 
Possible Changes in Study Design Due to the COVID-19 Pandemic ........................80 
10.7.3.1. 
Implementation of This Appendix ..............................................................................80 
10.7.3.2. 
Testing for COVID-19 ................................................................................................80 
10.7.3.3. 
Study Protocol Changes ..............................................................................................80 
10.7.3.4. 
Critical Parameters to Be Collected During the Study ...............................................80 
10.7.3.5. 
Mandatory Site Visits and Home Visits .....................................................................80 
10.8. 
Appendix 8: Interpretation of Hepatitis B Serologic Test Results .............................82 
10.9. 
Appendix 9: Abbreviations and Definitions ...............................................................83 
10.9.1. 
Definitions ..................................................................................................................83 
10.9.2. 
Abbreviations ..............................................................................................................83 
11. 
REFERENCES ...........................................................................................................87 
 
LIST OF TABLES 
Table 1: 
Schedule of Activities for Study ARGX-113-2001 ....................................................16 
Table 2: 
Analysis Sets ...............................................................................................................56 
Table 3: 
Protocol-Required Laboratory Tests ...........................................................................68 
Table 4: 
List of Vendor Information .........................................................................................77 
 
LIST OF FIGURES 
Figure 1: 
Schema for Study ARGX-113-2001 ...........................................................................15 
Figure 2: 
Statistical Modeling on MG-ADL Change From Baseline With IgG Percent 
Reduction From Baseline as a Predictor and Patient as a Random Effect in 
All Efgartigimod IV Treated Patients in Study ARGX-113-1704 (mITT 
Analysis Set) ...............................................................................................................55 
 
 
 

Clinical Study Protocol ARGX-113-2001 v2.0 
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1. 
PROTOCOL SUMMARY 
1.1. 
Synopsis 
Protocol Title: 
A Phase 3, Randomized, Open-Label, Parallel-Group Study to Compare the Pharmacodynamics, 
Pharmacokinetics, Efficacy, Safety, Tolerability, and Immunogenicity of Multiple Subcutaneous 
Injections of Efgartigimod PH20 SC With Multiple Intravenous Infusions of Efgartigimod in 
Patients With Generalized Myasthenia Gravis 
Brief Title: Evaluating the Pharmacodynamic Noninferiority of Efgartigimod PH20 SC 
Administered Subcutaneously as Compared to Efgartigimod Administered Intravenously in 
Patients With Generalized Myasthenia Gravis  
Rationale: 
The aim of this study is to investigate the pharmacodynamics (PD), pharmacokinetics (PK), 
safety, tolerability, immunogenicity, and clinical efficacy of efgartigimod coformulated with 
recombinant human hyaluronidase PH20 (rHuPH20) administered subcutaneously (SC) 
(efgartigimod PH20 SC) as compared to efgartigimod intravenously (IV) infused (efgartigimod 
IV) in patients with generalized myasthenia gravis (gMG). 
Objectives and Endpoints:  
Objectives 
Endpoints 
Primary 
 
x To demonstrate that the PD effect of 
injections of 1000 mg efgartigimod PH20 
SC, administered once per week (q7d) for 
4 administrations, is noninferior to that of 
IV infusions of efgartigimod at a dose of 
10 mg/kg administered q7d for 4 
administrations. 
x Percent reduction from baseline in total 
immunoglobulin G (IgG) levels at day 
29, ie, 7 days after the fourth IV or SC 
administration 

Clinical Study Protocol ARGX-113-2001 v2.0 
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Objectives 
Endpoints 
Secondary 
 
x To compare the PD effect of efgartigimod 
PH20 SC and efgartigimod IV over time 
x Absolute values, change from baseline, 
and percent reduction from baseline in 
total IgG levels over time 
x Absolute values, change from baseline, 
and percent reduction from baseline in 
acetylcholine receptor binding 
autoantibodies (AChR-Ab) levels over 
time in AChR-Ab positive patients 
x Absolute values, change from baseline, 
and percent reduction from baseline in 
IgG subtype levels (IgG1, IgG2, IgG3, 
and IgG4) over time  
x Area under the effect curve (AUEC) of 
the percentage reduction from baseline 
total IgG and similar AUEC for each IgG 
subtype per dosing interval (days 1–8, 
days 8–15, days 15–22, and days 22–29), 
days 1–29, and over the entire study 
(days 1–71) 
x To evaluate the PK of efgartigimod PH20 
SC and efgartigimod IV 
x PK parameters: maximum concentration 
(Cmax) (after all doses for the IV 
treatment arm), concentration observed 
predose (Ctrough) 
x To evaluate the safety, tolerability, and 
immunogenicity of efgartigimod PH20 
SC and efgartigimod IV 
x Incidence and prevalence of anti-drug 
antibodies (ADAs) against efgartigimod  
x Incidence and prevalence of ADAs 
against rHuPH20 in the SC treatment arm 
x Incidence and severity of adverse events 
(AEs), incidence of serious adverse 
events (SAEs), and changes in laboratory 
test results, physical examination results, 
vital signs, and electrocardiogram (ECG) 
results 

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Brief Summary: 
The purpose of this study is to investigate the PD, PK, safety, tolerability, immunogenicity, and 
clinical efficacy of efgartigimod coformulated with recombinant human hyaluronidase PH20 
(rHuPH20) as compared to efgartigimod IV infused in patients with gMG to evaluate the PD 
noninferiority of the SC formulation compared to the intravenous formulation. Study details 
include: 
Study Duration: 12 weeks 
Treatment Duration: 3 weeks 
Health Measurements: Total levels of immunoglobulin G (IgG), levels of IgG subtypes, AChR-
Ab levels, MG-ADL, QMG 
Visit Frequency: Every week through visit 9, followed by a 2-week period between visit 9 and 
the end of the study visit 
Number of Participants: 
Approximately 110 participants will be enrolled and randomized in a 1:1 ratio to receive either 
efgartigimod PH20 SC or efgartigimod IV in addition to their concomitant gMG therapy. 
Approximately 110 participants are considered sufficient to allow better quantification of the 
safety and efficacy between the IV and SC routes of administration for efgartigimod. See also 
Section 9.2. Randomization will be stratified by Japanese versus non-Japanese participants. 
Within non-Japanese participants, randomization will be further stratified by AChR-Ab status. 
Up to 20% of participants included in the study will be AChR-Ab seronegative Japanese and up 
to 20% will be AChR-Ab seronegative non-Japanese patients. 
Note: “Enrolled” means a participant, or their legally acceptable representative, has agreed to 
participate in a clinical study following completion of the informed consent process and 
screening. Potential participants screened to determine study eligibility but who do not 
participate in the study are not considered enrolled unless otherwise specified by the protocol. 
“Randomized” means that an enrolled participant has been randomly assigned to a treatment 
arm. 
Intervention Groups and Duration: 
The study duration is approximately 12 weeks, spanning the following study periods: 
x screening period: approximately 2 weeks, with an additional 5 days allowed if needed 
to ensure AChR-Ab test results have been received 
x treatment period: 3 weeks 
x follow-up period: 7 weeks 
On day 1, participants will be randomized to receive either efgartigimod IV 10 mg/kg or 
efgartigimod PH20 SC 1000 mg during the treatment period. All participants will receive a total 
of 4 administrations of the assigned IMP, administered q7d. Participants receiving efgartigimod 
PH20 SC 1000 mg or their caregivers will be trained to administer the IMP. Participants will be 
discontinued from treatment if it is in the participant’s best interest, as determined by the 
investigator or sponsor. 

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Data Monitoring/Other Board: Yes (see Section 10.1.5.1)  

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1.2. 
Schema 
Figure 1: 
Schema for Study ARGX-113-2001 
 
EoS=end of study; gMG=generalized myasthenia gravis; IMP=investigational medicinal product; IV=intravenous(ly); PH20=rHuPH20 (recombinant human 
PH20 hyaluronidase); SC=subcutaneous; V=visit 
a Participants will be randomized in a 1:1 ratio to either the efgartigimod IV 10 mg/kg treatment arm or the efgartigimod PH20 SC 1000 mg treatment arm. 
Participants will receive IMP every 7 days for 4 administrations. 
b Participants receiving efgartigimod PH20 SC or their caregivers will be trained in self-administration of the IMP. Once a participant or caregiver is considered 
competent to self-administer, they will be allowed to self-administer the IMP on site under supervision of the site staff starting at V2. 
c The follow-up period consists of weekly visits through V9, followed by a 2-week period between V9 and EoS. 

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1.3. 
Schedule of Activities  
Table 1: 
Schedule of Activities for Study ARGX-113-2001 
  
Screening 
Treatment Period 
Follow-up Period 
End 
of 
Study 
Unscheduled 
Visit 
 
V1 
Baseline 
V2 
V3 
V4 
V5 
V6 
V7 
V8 
V9 
EoSa 
UNSb 
Study Day (visit window) -14 
to  
-1  
1 
8(±1) 15(±1) 22(±1) 29(±2) 36(±2) 43(±2) 50(±2) 57(±2) 71(±3) 
 
Activity 
Informed consentc 
X 
 
 
 
 
 
 
 
 
 
 
 
Inclusion/exclusion 
criteria 
X 
X 
 
 
 
 
 
 
 
 
 
 
SARS-CoV-2 testd 
X 
 
 
 
 
 
 
 
 
 
 
X 
Medical/surgical historye 
X 
 
 
 
 
 
 
 
 
 
 
 
Demographic data 
X 
Height and weightf 
X 
X 
 
 
 
 
 
 
 
 
X 
X 
MG-ADL 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
QMGg 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
MG-QoL15r 
 
X 
 
 
 
 
 
 
 
 
X 
 
EQ-5D-5L 
 
X 
 
 
 
 
 
 
 
 
X 
 
Physical examination 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Vital signsh 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
SIB risk monitoringi 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 

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Screening 
Treatment Period 
Follow-up Period 
End 
of 
Study 
Unscheduled 
Visit 
V1 
Baseline 
V2 
V3 
V4 
V5 
V6 
V7 
V8 
V9 
EoSa 
UNSb 
Study Day (visit window) -14 
to  
-1  
1 
8(±1) 15(±1) 22(±1) 29(±2) 36(±2) 43(±2) 50(±2) 57(±2) 71(±3) 
 
Activity 
Clinical laboratory testsj 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
AChR-Ab serotype 
X 
Single 12-lead ECGk 
X 
X 
 
 
X 
 
 
 
 
 
X 
X 
Urinalysis 
X 
X 
 
 
X 
X 
 
 
 
 
X 
X 
Pharmacokineticsl 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Pharmacodynamicsm 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Immunogenicityn 
X 
X 
X 
 
 
X 
X 
X 
Pregnancy testo 
X 
X 
X 
X 
X 
X 
 
 
 
 
X 
X 
Viral screenp 
X 
 
 
 
 
 
 
 
 
 
 
 
Randomizationq 
 
X 
 
 
 
 
 
 
 
 
 
 
Training for self-
administration of SC IMPr 
 
X 
X 
X 
X 
(X) 
(X) 
(X) 
(X) 
(X) 
(X) 
(X) 
Administration of IMPs 
X 
Xt 
Xt 
Xt 
Assessment of 
administration siteu 
Continuous monitoring 
Hospitalization 
monitoringv 
Continuous monitoring 

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Screening 
Treatment Period 
Follow-up Period 
End 
of 
Study 
Unscheduled 
Visit 
V1 
Baseline 
V2 
V3 
V4 
V5 
V6 
V7 
V8 
V9 
EoSa 
UNSb 
Study Day (visit window) -14 
to  
-1  
1 
8(±1) 15(±1) 22(±1) 29(±2) 36(±2) 43(±2) 50(±2) 57(±2) 71(±3) 
 
Activity 
Prior/concomitant 
therapyv 
Continuous monitoring 
Adverse eventsv 
Continuous monitoring 
Ab= antibody; AChR-Ab=acetylcholine receptor binding autoantibody; AChE=acetylcholinesterase; ADA=anti-drug antibodies; ECG=electrocardiogram; EoS=end of study; 
EQ-5D-5L=EuroQoL 5 Dimensions 5 Levels; ER=emergency room; FSH= follicle-stimulating hormone; ICU=intensive care unit; IgG=immunoglobulin G; 
IMP=investigational medicinal product; IV=intravenous; MG-ADL=Myasthenia Gravis-Activities of Daily Living total score; MGFA=Myasthenia Gravis Foundation of 
America; MG-QoL15r=Myasthenia Gravis Quality of Life Questionnaire (15 item scale revised); NAb=neutralizing antibody; PD=pharmacodynamics; PHQ=Patient Health 
Questionnaire; PK=pharmacokinetics; PR= atrioventricular node delay interval; QMG=Quantitative Myasthenia Gravis score; QRS=duration of ventricular depolarization; 
QT=total duration of ventricular depolarization; QTcF=rate-corrected QT intervals using Fridericia’s formula; PH20= recombinant human hyaluronidase PH20 (rHuPH20); 
RR= time between heartbeats; SARS-CoV-2=severe acute respiratory syndrome coronavirus 2; SC=subcutaneous; SIB=Suicide Ideation and Behavior; SoA=Schedule of 
Activities; UNS=unscheduled; V=visit 
Note: All activities are performed predose on dosing days unless otherwise indicated. It is recommended to perform the MG-ADL scale prior to all other assessments. 
a After a participant completes the study and all EoS visit activities, the participant will be allowed, if eligibility criteria are met, to roll over into the open-label extension study 
ARGX-113-2002 to receive efgartigimod PH20 SC 1000 mg. 
b A UNS visit can occur at the request of the participant or the investigator. During the UNS visit, activities as indicated in the SoA can be performed at the discretion of the 
investigator, depending on the reason for the UNS visit. 
c No study-related activities will be initiated before the participant signs the informed consent form. 
d A nasopharyngeal swab will be performed to sample nasal and throat mucosal cells. Participants may be retested as needed (see Section 10.7) 
e Medical history will also include all ER visits, hospitalizations, and ICU admissions that have occurred in the previous 12 months. All available vaccination history will be 
recorded. For vaccines where multiple doses or boosters are received, only the most recent must be recorded. See Section 8.2.5. 
f Height will only be measured at screening and weight will be measured at screening, at baseline, at the EoS visit, and at UNS visits. 
g AChE inhibitors must be withheld for at least 12 hours before the QMG assessment (consistent with the revised manual for the QMG test as recommended by the MGFA). 
h It is recommended that the method used to measure body temperature at screening is maintained throughout the study for each patient. 
i The SIB Risk Monitoring assessment is based on question 9 of the PHQ. See Section 8.2.10. 
j Blood samples for clinical laboratory (hematology/clinical chemistry and FSH, if applicable) safety assessments will be collected predose on dosing days. In addition, total IgG 
at screening is to be assessed for defining eligibility. Participants need to be in a fasted state (defined as no food or drink, except for water, which is allowed until at least 4 hours 
prior to sampling) for at least 8 hours prior to each sampling.  
k The following ECG intervals will be measured: RR, PR, QRS, QT, and QTcF. 

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l On dosing days, PK samples will be collected predose (within 1 hour prior to start of administration) and at the end of each infusion for IV (within 1 hour after end of infusion). 
No postdose PK samples will be collected in case of IMP administration by SC injection. 
m The PD analysis comprises levels of total IgG, IgG subtypes (IgG1, IgG2, IgG3 and IgG4) and levels of AChR-Abs (for AChR-Ab seropositive participants only). 
n Titers of ADA against efgartigimod and presence of NAbs against efgartigimod will be measured in serum in both the IV and SC treatment arms. Plasma titer levels of ADA and 
NAbs against rHuPH20 will be measured in the SC treatment arm only. 
o Female participants of childbearing potential will be tested for pregnancy using a serum test at screening and a urine test at all other visits. 
p The virology screen includes relevant tests to comply with exclusion criteria 7 and is performed on samples taken at screening. 
q Randomization will be performed after screening within approximately 2 weeks and only after confirmation of the eligibility of the patient. If the AChR-Ab test result is not 
available in time (ie, within the 2 weeks screening window), the screening window can be increased by a maximum of 5 calendar days as needed. 
r Applicable to participants in the SC treatment arm only. These participants and their caregivers will be trained in self-administration of efgartigimod PH20 SC and the training 
can continue until the participant or their caregiver is capable of self-administration. Training sessions marked with parentheses “(X)” are optional. 
s The IMP (efgartigimod IV or efgartigimod PH20 SC) will be administered at visits 1, 2, 3, and 4 either as an 1-hour IV infusion or an SC injection. Participants will remain at 
the site for at least 1 hour following the end of the drug administration to be monitored for safety. 
t Participants randomized to the SC treatment arm or their caregivers will be allowed to administer efgartigimod PH20 SC at the site under supervision if the self-
administration/caregiver-supported administration training is completed and documented and if the site staff determine that the participant is ready to do so. 
u The assessment of the administration site will be performed prior to dosing and 1 hour postdose on dosing days, in addition to continuous monitoring by the participant in 
between visits. 
v Adverse events, use of concomitant therapies, use of rescue therapy, medical procedures performed on the participants, and hospitalizations will be collected from the time the 
informed consent form is signed until the last study-related activity. Relevant prior therapy and all available vaccination history will only be collected at screening. See 
Section 6.8 and Section 8.3. 
 

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2. 
INTRODUCTION 
Efgartigimod is a human immunoglobulin (Ig) G1 (IgG1)-derived Fc fragment that binds with 
nanomolar affinity to human FcRn that is being developed for the treatment of generalized 
myasthenia gravis. 
2.1. 
Study Rationale 
The aim of this study is to investigate the pharmacodynamics (PD), pharmacokinetics (PK), 
safety, tolerability, immunogenicity, and clinical efficacy of efgartigimod coformulated with 
recombinant human hyaluronidase PH20 (rHuPH20, brand name Hylenex®) administered 
subcutaneously (SC) (efgartigimod PH20 SC) as compared to efgartigimod intravenously (IV) 
infused (efgartigimod IV) in patients with generalized myasthenia gravis (gMG).  
The PD of efgartigimod IV at 10 mg/kg and efgartigimod PH20 SC at a fixed dose of 1000 mg 
will be evaluated, as per the primary objective. The SC formulation of efgartigimod will include 
rHuPH20 because the enzyme allows manual SC injection within a few minutes and using larger 
volumes than what is possible without rHuPH20.  
2.2. 
Background 
gMG is a rare, chronic, neuromuscular autoimmune disease caused by pathogenic IgGs targeting 
the neuromuscular junction (NMJ), producing reduced neuromuscular transmission and 
debilitating and potentially life-threatening muscle weakness and chronic fatigue. Generalized 
muscle weakness results in difficulties in mobility, speech, swallowing, vision, and respiration. 
Up to 20% of patients develop potentially life-threatening myasthenic crisis involving respiratory 
failure requiring mechanical ventilation.1,2 
ARGX-113 (efgartigimod) is an investigational antibody fragment and a first-in-class neonatal 
Fc receptor (FcRn) antagonist that is being evaluated for the treatment of patients with severe 
autoimmune diseases mediated by pathogenic IgG autoantibodies, including gMG. 
Approximately 90% of patients with gMG have detectable levels of IgG autoantibodies in the 
serum. Most commonly, these antibodies are against the acetylcholine receptor (AChR).3 
Efgartigimod leads to degradation circulating disease-causing pathogenic antibodies by blocking 
FcRn. 
FcRn is present throughout life and expressed predominantly in endothelial cells and cells of 
myeloid lineage. FcRn has a specific role in IgG homeostasis, recycling all IgG subtypes, which 
rescues them from lysosomal degradation. This FcRn-mediated recycling results in the longer 
half-life and higher concentrations of IgG, including pathogenic IgG autoantibodies, as 
compared to other Igs that are not recycled by FcRn. FcRn also promotes transcytosis of IgG into 
tissues. Additionally, FcRn recycles albumin using a site that is distinct from the IgG binding 
site. 
Efgartigimod is a human IgG1 antibody Fc fragment, a natural ligand of FcRn, engineered for 
increased FcRn affinity at both physiological and acidic pH. Efgartigimod outcompetes 
endogenous IgG binding, preventing FcRn-mediated recycling of IgGs and increasing IgG 
degradation.  

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In the phase 3 study ARGX-113-1704 in patients with gMG, treatment with efgartigimod IV 
resulted in a statistically significant increase in the percentage of participants responding to 
treatment based on the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score and 
the Quantitative Myasthenia Gravis (QMG) score as compared to placebo. Additionally, 
efgartigimod IV treatment resulted in a substantial mean percent decrease in total IgG levels as 
compared to no observable change in participants who received placebo, which further supported 
the results of the phase 2 study ARGX-113-1602.  
The efgartigimod PH20 SC formulation was tested in healthy subjects in study ARGX-113-1901, 
which resulted in a dose-dependent decrease in total IgG levels. 
A detailed description of the chemistry, pharmacology, efficacy, and safety of efgartigimod is 
provided in the Investigator’s Brochure (IB). For more information on rHuPH20, refer to the IB 
for rHuPH20. 
2.3. 
Benefit/Risk Assessment 
More detailed information about the known and expected benefits and risks and reasonably 
expected adverse events (AEs) of efgartigimod may be found in the IBs for efgartigimod4 and 
rHuPH205.  
2.3.1. 
Efgartigimod Risk Assessment 
Overall, efgartigimod IV has been well tolerated in healthy participants subjects as well as in 
patients with gMG. Efgartigimod PH20 SC was well tolerated in healthy participants. No major 
safety findings have arisen in ongoing and completed studies with either formulation of 
efgartigimod. Further information can be found in the IB4. 
Potential Risk of Clinical 
Significance 
Summary of Data/Rationale 
for Risk 
Mitigation Strategy 
Study Intervention (s) 
Immune modulation leading to 
increased infection risk 
Efgartigimod reduces IgG 
levels, potentially hindering 
immune response and increasing 
the infection risk. However, no 
opportunistic infection with 
efgartigimod has been observed. 
Efgartigimod treatment may be 
associated with a small increase 
in the frequency of infections. 
However, the type and severity 
of these infections are not 
different to those which patients 
with gMG are ordinarily 
susceptible. There is no increase 
in the type of infectious events 
that might be expected from 
high degrees of 
immunosuppression 
Participants with clinically 
significant uncontrolled 
infections, malignancies, recent 
surgeries, and/or the presence of 
certain viral infections are 
excluded (see Section 5.2). 
Administration of efgartigimod 
to a participant will be 
interrupted if a clinically 
significant infection occurs. 
Infections are considered an 
adverse event of special interest 
(AESI) and a detailed 
questionnaire will be completed 
for any infectious events.  

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Potential Risk of Clinical 
Significance 
Summary of Data/Rationale 
for Risk 
Mitigation Strategy 
Study Intervention (s) 
(eg, tuberculosis or 
opportunistic infections).  
Injection and/or infusion-related 
reactions (IRRs) 
All therapeutic proteins have the 
potential to elicit antibody or 
other immune or nonimmune 
mediated responses, potentially 
resulting in hypersensitivity or 
allergic reactions such as rash, 
urticaria, angioedema, serum 
sickness, and anaphylactoid or 
anaphylactic reactions. 
None of the participants treated 
with either efgartigimod 
formulation had a treatment-
emergent adverse event (TEAE) 
that was a drug hypersensitivity 
or anaphylactic reaction 
Participants will be monitored at 
the site for 1 hour after 
administration and 
administration site reactions will 
be monitored continuously (see 
Section 1.3). 
Potential risk to 
teratogenicity/fetotoxicity 
No clinical studies have been 
performed to evaluate 
reproductive risks. However, 
nonclinical studies performed 
suggest that there is no risk of 
teratogenicity or fetotoxicity. 
Pregnant women are excluded. 
Participants who are women of 
childbearing potential 
(WOCBP) must use a highly 
effective or acceptable method 
of contraception (see inclusion 
criterion 8 and Section 10.5) 
2.3.2. 
Efgartigimod Benefit Assessment 
Efgartigimod has been shown to effectively reduce IgG antibodies in several clinical studies, 
including in healthy subjects, patients with immune thrombocytopenia (ITP), patients with 
pemphigus vulgaris, and patients with gMG (see the IB). Patients with gMG also saw 
improvements in gMG symptoms and quality of life. Studies involving patients with gMG are 
described in the following text. 
x A phase 2 study (ARGX-113-1602) enrolled patients with gMG that were 
seropositive for AChR binding autoantibodies (AChR-Ab) and had an MG-ADL total 
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Participants received efgartigimod IV 10 mg/kg or placebo q7d for 4 infusions.  
 Efgartigimod IV showed statistically significant improvements as compared to 
placebo in clinical evaluations of MG symptoms, including the MG-ADL and the 
QMG. 
 The efgartigimod IV treatment arm showed a substantial percent reduction from 
baseline in total IgG levels as compared to the placebo arm, where no discernable 
difference from baseline was observed. 

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 Efgartigimod IV was safe and well tolerated, with all treatment-emergent adverse 
events (TEAEs) classified as mild or moderate. 
x A phase 3 study (ARGX-113-1704) enrolled patients with gMG with an MG-ADL 
WRWDO VFRUH  ZLWK PRUH WKDQ  RI WKH WRWDO VFRUH FRPLQJ IURP QRQRFXODU
symptoms, regardless of AChR-Ab presence in the serum. Participants received 
efgartigimod IV 10 mg/kg or placebo q7d for 4 infusions, with additional treatment 
cycles allowed based on the clinical response of the participant as evaluated by the 
MG-ADL total score. 
 The efgartigimod IV treatment arm had a statistically significantly higher 
percentage (67.7%) of MG-ADL responders as compared to the placebo arm 
(29.7%) among AChR-Ab positive patients. In the overall population (AChR-Ab 
positive and AChR-Ab negative participants), the efgartigimod treatment arm also 
reported a significantly higher percentage of MG-ADL responders (67.9%) 
compared to the placebo arm (37.3%). 
 The efgartigimod IV treatment arm had a statistically significantly higher 
percentage of QMG responders (63.1%) as compared to the placebo arm (14.1%) 
among AChR-Ab positive participants.  
 In the AChR-Ab seropositive population, the maximum mean percent change 
from baseline in total IgG levels was approximately 61% 1 week after the last 
infusion of a treatment cycle. No substantial mean percent change in total IgG 
levels from baseline was observed in the placebo arm. The results were 
comparable between AChR-Ab seropositive participants and the overall 
population. 
 Efgartigimod IV 10 mg/kg q7d was safe and well tolerated. The efgartigimod IV 
arm had a lower percentage of participants reporting TEAEs than the placebo 
arm. The majority of TEAEs reported were mild or moderate in severity. 
2.3.3. 
rHuPH20 Risk Assessment 
More information on the use of rHuPH20 (brand name Hylenex) is available in the rHuPH20 
IB5. 
SC injections were well tolerated in healthy subjects, dehydrated pediatric patients, hospice and 
palliative care patients, patients with type 1 and 2 diabetes, and patients with rheumatoid 
arthritis. SC injections of rHuPH20 alone or in combination with lactated Ringer’s solution, 
normal saline, co-injected drugs (eg, morphine, ceftriaxone, ondansetron), peptides (eg, insulin 
and insulin analogs), or proteins (IgG and adalimumab) have been well tolerated in all clinical 
studies. 
Most AEs observed were mild, transient injection site reactions, including erythema, pain, 
bruising, pruritus, burning, tenderness, edema, induration, irritation, paresthesia, numbness, and 
rash. Moderate injection site reactions, which occurred less frequently, include burning, 
erythema, pain, and numbness. Mild-to-moderate headache was also reported.  
Hylenex prescribing information as of February 2016 contains the following warnings and 
precautions: 

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x rHuPH20 should not be injected into or around an infected or acutely inflamed area 
because of the danger of spreading a localized infection. rHuPH20 should not be used 
to reduce the swelling of bites or stings. 
x rHuPH20 should not be applied directly to the cornea. It is not for topical use. 
2.3.4. 
rHuPH20 Benefit Assessment 
rHuPH20 locally degrades hyaluronan under physiological conditions, acting as a permeation 
enhancer in the SC space. rHuPH20 activity allows for increased dispersion and absorption of 
coadministered therapies and facilitates the delivery of larger volumes in rapid SC injections 
with limited swelling, induration, or pain. rHuPH20 may enhance the dispersion and absorption 
of efgartigimod, allowing an SC injection to achieve the target exposure, PD effect, and 
associated clinical benefit. This formulation and SC administration are expected to improve 
patient convenience as compared to the IV formulation, as participants or their caregivers will be 
permitted to administer efgartigimod PH20 SC once they are competent to do so. 
2.3.5. 
Overall Benefit/Risk Conclusion 
Taking into account the measures taken to minimize risk to study participants, the potential risks 
identified in association with efgartigimod and rHuPH20 are justified by the anticipated benefits 
that may be afforded to participants with gMG. 

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3. 
OBJECTIVES AND ENDPOINTS 
Objectives 
Endpoints 
Primary 
 
x To demonstrate that the PD effect of 
injections of 1000 mg efgartigimod PH20 
SC, administered once per week (q7d) for 
4 administrations, is noninferior to that of 
IV infusions of efgartigimod at a dose of 
10 mg/kg administered q7d for 
4 administrations. 
x Percent reduction from baseline in total 
IgG levels at day 29, ie, 7 days after the 
fourth IV or SC administration 
Secondary 
 
x To compare the PD effect of efgartigimod 
PH20 SC and efgartigimod IV over time 
x Absolute values, change from baseline 
and percent reduction from baseline in 
total immunoglobulin (IgG) levels over 
time 
x Absolute values, change from baseline 
and percent reduction from baseline in 
AChR-Ab levels over time in AChR- Ab 
positive patients 
x Absolute values, change from baseline, 
and percent reduction from baseline in 
IgG subtype levels (IgG1, IgG2, IgG3, 
and IgG4) over time  
x Area under the effect curve (AUEC) of 
the percentage reduction from baseline 
total IgG and similar AUEC for each IgG 
subtype per dosing interval (days 1–8, 
days 8–15, days 15–22, and days 22–29), 
days 1–29, and over the entire study 
(days 1–71) 
x To evaluate the PK of efgartigimod PH20 
SC and efgartigimod IV 
x PK parameters: maximum concentration 
(Cmax) (after all doses for the IV 
treatment arm), concentration observed 
predose (Ctrough) 

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4. 
STUDY DESIGN 
4.1. 
Overall Design 
x This is a phase 3, multicenter, randomized, open-label, parallel-group study to evaluate 
the noninferiority of the PD effect of efgartigimod PH20 SC 1000 mg as compared to 
efgartigimod IV 10 mg/kg in patients with gMG. The safety, clinical efficacy, 
immunogenicity, PK of efgartigimod PH20 SC 1000 mg and efgartigimod IV 10 mg/kg 
will also be assessed. 
x The total study duration is approximately 12 weeks: 
o approximately 2 weeks of screening, with an additional 5 days allowed as needed 
to ensure AChR-Ab test results have been received 
o 3 weeks of treatment 
o 7 weeks of follow-up 
x The primary target population is adult patients with generalized myasthenia gravis 
(gMG), who have an MG-ADL total score  points and greater than 50% of the total 
score attributed to nonocular symptoms, at screening and baseline. Participants must be 
receiving a stable dose of concomitant treatment for gMG. 
x Serum from participants will be tested to determine their AChR-Ab status. Up to 20% of 
the participants randomized can be seronegative for AChR-Abs in both the overall 
population and the Japanese participant population.  
x Randomization will be stratified by Japanese versus non-Japanese participants. Within 
non-Japanese participants, randomization will be further stratified by AChR-Ab status. 
x After confirmation of eligibility, participants will be randomized 1:1 at the day 1 visit to 
receive efgartigimod IV 10 mg/kg or efgartigimod PH20 SC 1000 mg every 7 days (q7d) 
for 4 administrations.  
x Efgartigimod IV will be administered by a 1-hour IV infusion performed by the site staff. 
x Efgartigimod PH20 SC will be administered by injection into the abdominal 
subcutaneous tissue. Participants receiving efgartigimod PH20 SC or their caregivers will 
be trained in self-administration or caregiver-supported administration of the IMP. If the 
participant or the caregiver successfully completes the training to the satisfaction of the 
investigator and the participant, the participant or the caregiver may administer the 
second, third and/or fourth injections at the site under supervision. 
x At End of Study (EoS), eligible participants will be offered the option to roll over into a 
single-arm extension study ARGX-113-2002 to receive efgartigimod PH20 SC. 
Participants who complete this study may be eligible to participate in the extension study. 
4.2. 
Scientific Rationale for Study Design 
The aim of this study is to assess the PD, PK, safety, tolerability, immunogenicity, and clinical 
efficacy of efgartigimod coadministered with rHuPH20 subcutaneously (efgartigimod PH20 SC) 
as compared to efgartigimod IV in patients with gMG. IgG autoantibodies lead to gMG 

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symptoms, resulting from destruction of important molecules in the NMJ, including AChR. IgG 
antibody total levels, levels of IgG subtypes (IgG1, IgG2, IgG3, and IgG4), and levels of AChR-
Abs will be evaluated as an objective surrogate measure for gMG treatment efficacy, as study 
ARGX-113-1704 showed that reduction total IgG levels and AChR-Ab levels (in AChR-Ab 
seropositive participants) correlate with reductions in the MG-ADL total score. Clinical efficacy 
will be measured by the MG-ADL total score and the QMG score, which are well-established 
measures for assessing disease severity. 
The PD of efgartigimod IV at 10 mg/kg and efgartigimod PH20 SC at a fixed dose of 1000 mg 
will be compared, as per the primary objective of this study (see Section 3). The SC formulation 
of efgartigimod will include rHuPH20 because the enzyme facilitates the SC delivery of volumes 
greater than ~2 mL and may increase the absorption and dispersion of efgartigimod. rHuPH20 
has been approved in the United States as Hylenex recombinant as a permeation enhancer for SC 
delivery of fluid for achieving hydration and as an adjuvant to increase the dispersion and 
absorption of other injected drugs. rHuPH20 depolymerizes hyaluronan under physiologic 
conditions, allowing for a larger volume to be used in rapid SC injections with limited swelling, 
induration or pain.5,6 
The open-label design used in this study will have no impact on the assessment of the PD, PK, 
and immunogenicity parameters and thus is not expected to impact the primary endpoint and 
most of the secondary endpoints. Importantly, a double blind study design would be more 
burdensome for the participants. 
4.3. 
Justification for Dose 
The selection of the efgartigimod IV dosage (10 mg/kg q7d) was made based on results from 
prior clinical studies, including a phase 3 study in participants with gMG (ARGX-113-1704). 
Administration of efgartigimod IV 10 mg/kg q7d for 4 infusions achieved near-maximal total 
IgG reduction, resulted in a reduction of pathogenic autoantibodies, and was associated with 
clinical efficacy in participants with gMG. Furthermore, this dose was well tolerated with no 
safety concerns in all populations tested thus far. 
The efgartigimod PH20 SC dose selected targets a similar total IgG reduction as compared to the 
efgartigimod IV 10 mg/kg dose, anticipating a similar clinical response. PK/PD modeling 
indicated that weekly or biweekly doses of efgartigimod PH20 SC 1000 mg result in a 
comparable effect on IgG levels when compared to efgartigimod IV 10 mg/kg administered q7d 
or biweekly (q2w).  
No safety concerns have been identified to date with SC administration of efgartigimod PH20 SC 
in the completed phase 1 study ARGX-113-1901 or in ongoing studies in healthy subjects. 
4.4. 
End of Study Definition 
The end of the study is defined as the date of the last visit of the last participant in the 
ARGX-113-2001 study. A participant is considered to have completed the study if he/she 
completed the EoS visit at day 71 (±3 days), even if the participant did not complete treatment. 

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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 
Participants are eligible to be included in the study only if all of the following criteria apply: 
 Must be capable of giving signed informed consent as described in Section 10.1, which
includes compliance with the requirements and restrictions listed in the informed consent
form (ICF) and in this protocol
 At least 18 years of age at the time of signing the ICF
 Diagnosed with gMG with confirmed documentation and supported by at least 1 of the
following:
D
History of abnormal neuromuscular transmission demonstrated by single fiber
electromyography or repetitive nerve stimulation
E
History of positive edrophonium chloride test
F
Demonstrated improvement in MG signs upon treatment with oral
acetylcholinesterase (AChE) inhibitors as assessed by the treating physician
 Meeting the clinical criteria as defined by the Myasthenia Gravis Foundation of America
(MGFA) class II, III, IVa, or IVb
 Abdominal skin tissue allows for absorption and assessment of local safety of the planned
SC injection, as determined by the investigator
 An MG-$'/ WRWDO VFRUH RI  SRLQWV ZLWK PRUH WKDQ  RI WKH VFRUH GXH WR QRQRFXODU
symptoms at screening and baseline
 Receiving a stable dose of other gMG treatment (concomitant gMG treatment) prior to
screening. For patients receiving nonsteroidal immunosuppressants (NSIDs), steroids,
and/or AChE inhibitors as concomitant medications, the following dose conditions apply:
D
NSIDs (eg, azathioprine, methotrexate, cyclosporine, tacrolimus, mycophenolate
mofetil, and cyclophosphamide): treatment initiated at least 6 months prior to
screening and no changes to dose in the 3 months before screening
E
Steroids: treatment initiated at least 3 months prior to screening and no dose changes
in the month before screening
F
AChE inhibitors: stable dose with no dose escalation during the 2 weeks before
screening. AChE inhibitors must be withheld for at least 12 hours before the QMG
assessment, to be consistent with the revised manual for the QMG test, as
recommended by the MFGA
 Contraceptive use should be consistent with local regulations regarding the methods of
contraception for those participating in clinical studies and:
D
Male participants are eligible to participate if they agree to the following during the
intervention period and for at least 90 days after the last study dose of the IMP:

Refrain from donating sperm

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Plus either 
 Be abstinent from heterosexual intercourse as their preferred and usual lifestyle 
(abstinent on a long term and persistent basis) and agree to remain abstinent 
Or 
 Must agree to use a male condom with a female partner using an additionally 
highly effective contraceptive method with a failure rate of <1% per year as 
described in Section 10.5. when having sexual intercourse with a woman of 
childbearing potential who is not currently pregnant 
Or 
 Be a sterilized man who has had a documented absence of sperm post-procedure 
b. Female participants are eligible to participate if they are not pregnant or 
breastfeeding, and they are 1 of the following: 
 Women of nonchildbearing potential (WONCBP), as defined in Section 10.5.1. 
Or 
 Women of childbearing potential (WOCBP) as defined in Section 10.5.1 and is 
using a contraceptive method that is highly effective (with a failure rate of <1% 
per year) during the study intervention and for at least 90 days after the last study 
dose of the IMP. The investigators should evaluate the potential for contraceptive 
method failure (eg, noncompliance) in relationship to the first dose of the study 
intervention 
 WOCBP must have a negative highly sensitive serum pregnancy test within the 
screening period before the first dose of study IMP, see Section 8.2.8. 
 Additional requirements for pregnancy testing during and after study intervention 
are located in Section 8.2.8. 
 The investigator is responsible for review of medical history, menstrual history, 
and recent sexual activity to decrease the risk for inclusion of a woman with an 
early undetected pregnancy 
 
5.2. 
Exclusion Criteria  
Participants are excluded from the study if any of the following criteria apply: 
1. Are pregnant or lactating, or intend to become pregnant during the study or within 90 
days after the last dose of IMP 
2. Has any of the following medical conditions: 
a. Clinically significant uncontrolled active or chronic bacterial, viral, or fungal 
infection at screening 
b. Any other known autoimmune disease that, in the opinion of the investigator, would 
interfere with an accurate assessment of clinical symptoms of myasthenia gravis or 
put the participant at undue risk 

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c.
History of malignancy unless deemed cured by adequate treatment with no evidence
RI UHRFFXUUHQFH IRU  years before the first administration of the IMP. Participants
with the following cancers can be included at any time:

adequately treated basal cell or squamous cell skin cancer

carcinoma in situ of the cervix

carcinoma in situ of the breast

incidental histological findings of prostate cancer (TNM Classification of
Malignant Tumors stage T1a or T1b)
d. Clinical evidence of other significant serious diseases, or the participant has had a
recent major surgery, or who have any other condition that, in the opinion of the
investigator, could confound the results of the study or put the participant at undue
risk
 Worsening muscle weakness secondary to concurrent infections or medications
(aminoglycosides, beta-blockers, etc.)
 A documented lack of clinical response to plasma exchange (PLEX)
 Received a live-attenuated vaccine fewer than 28 days before screening. Receiving an
inactivated subunit, polysaccharide, or conjugate vaccine any time before screening is not
exclusionary
 Received a thymectomy <3 months prior to screening or 1 is planned to be performed
during the study period
 The following results from these diagnostic assessments will be considered exclusionary:
D
Positive serum test at screening for an active viral infection with any of the following
conditions:

Hepatitis B virus (HBV) that is indicative of an acute or chronic infection
(https://www.cdc.gov/hepatitis/HBV/PDFs/SerologicChartv8.pdf, see
Section 10.8)

Hepatitis C virus (HCV) based on HCV antibody assay

Human immunodeficiency virus (HIV) based on a CD4 count of 200 cells/mm3
or test results that are associated with an acquired immunodeficiency syndrome
(AIDS)-defining condition, such as: Cytomegalovirus retinitis with loss of vision,
Pneumocystis jiroveci pneumonia, chronic intestinal cryptosporidiosis, HIV-
related encephalopathy, Mycobacterium tuberculosis (pulmonary or
extrapulmonary), or invasive cervical cancer
E
Positive nasopharyngeal swab test for SARS-CoV-2
 Using the following prior or concomitant therapies:
D
Use of an investigational product within 3 months or 5 half-lives (whichever is
longer) before the first dose of IMP
E
Use of any monoclonal antibody within 6 months before the first dose of the IMP

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c. Use of Ig administered intravenously (IVIg), SC (SCIg), or intramuscularly within 
4 weeks of screening 
d. Use of PLEX within 4 weeks of screening 
e. Previously participated in a clinical study with efgartigimod and/or products 
coformulated with rHuPH20 and received at least 1 administration of IMP 
9. Total IgG levels <6 g/L at screening 
10. Current or history of (ie, within 12 months of screening) alcohol, drug, or medication 
abuse 
11. A known hypersensitivity reaction to efgartigimod, rHuPH20, or any of its excipients 
5.3. 
Lifestyle Considerations 
5.3.1. 
Meals and Dietary Restrictions 
Participants will need to be fasted for each visit. Fasted is defined as no food or drink except for 
water for at least 8 hours prior to the visit. Water is allowed until 4 hours prior to the visit. 
5.4. 
Screen Failures 
Screen failures are defined as participants who consent to participate in the clinical study but are 
not subsequently enrolled. Participants who fail to meet the eligibility criteria will be considered 
screen failures. 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 
(CONSORT) publishing requirements and to respond to queries from regulatory authorities. 
Minimal information includes demography, screen failure details, eligibility criteria, and any 
serious adverse event (SAE). See the eCRF completion guidelines for a complete list of what 
will be collected for screen failures. 
Individuals who do not meet the criteria for participation in this study may be rescreened 
(ie, redoing the full assessments as per the Schedule of Activities (SoA) in Section 1.3. or 
retested once (ie, redoing assessments) after sponsor’s written approval.  
Examples of conditions under which rescreening may be considered include the following: 
x Individuals who required treatment for an acute illness (eg, infection) may be 
rescreened once the illness is resolved or the medical problem stabilized. 
Examples of conditions under which retesting may be considered include the following: 
x Individuals who have clinical laboratory tests value meeting 1 or more exclusion 
criteria which are not in line with the medical history and clinical evaluation of the 
individual, may be retested to confirm the value of the tests, if still allowed within the 
screening period. If not feasible, the individual should be rescreened. 
Rescreened participants should be assigned a new participant number for every 
screening/rescreening event. 

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5.5. 
Criteria for Temporarily Delaying Administration of Study 
Intervention 
Delaying the administration of the IMP must occur if it is deemed in the best interest of the 
participant, as determined by the investigator. If the IMP cannot be administered within the 
specified time window, then that dose of the IMP must be missed. See Section 7.1.  

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6.2.1. 
Preparation 
x Efgartigimod for IV administration will be provided as a sterile, colorless, clear 
concentrate for solution for infusion in glass vials. Appropriate dilutions in a 0.9% 
saline solution in an infusion bag will be prepared at the site prior to administration. 
x Efgartigimod for SC administration will be provided as a sterile, colorless to 
yellowish solution for injection in glass vials. 
x The IMP will be manufactured in accordance with Good Manufacturing Practice 
regulations.  
6.2.2. 
Handling 
x The investigator or designee must confirm appropriate temperature conditions have 
been maintained during transit for all IMP received and any discrepancies are 
reported and resolved before use of the study intervention. 
x Only participants enrolled in the study may receive IMP and only authorized site staff 
may supply the IMP. IMP administration must be performed by site staff or, in the SC 
treatment arm only, by an adequately trained and supervised participant or caregiver. 
All IMP 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. 
Storage 
x The IMP will be supplied to the pharmacy at the designated investigational site by 
and under the responsibility of the sponsor’s designated IMP supply vendor, who will 
also provide the investigator with the certificate of analysis, certificate of conformity, 
and European Union qualified person release documents. 
x The IMP must be stored refrigerated (2°C to 8°C or 35°F to 46°F) in its secondary 
packaging. It should not be exposed to freezing temperature or shaken, and it should 
be protected from direct sunlight during storage at the clinical site. 
x The investigator (or his/her designee) is responsible for the correct and safe storage of 
the IMP assigned to the clinical site, in a locked, secure storage facility maintained 
within the appropriate temperature ranges, with access limited to those individuals 
authorized to dispense the IMP. 
6.2.4. 
Accountability 
x The investigator, institution, or the head of the medical institution (where applicable) 
is responsible for IMP accountability, reconciliation, and record maintenance 
(ie, receipt, reconciliation, and final disposition records). 
6.3. 
Measures to Minimize Bias: Randomization and Blinding 
x This is an open-label study; potential selection bias will be reduced by central 
randomization. 

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x Participants will be assigned a unique patient identification number at screening. 
Upon randomization, the participant will be assigned to a treatment arm according to 
the randomization schedule generated prior to the start of the study.  
x Randomization will be stratified by Japanese versus non-Japanese participants. 
Within the non-Japanese participants, randomization will be further stratified by 
AChR-Ab status. 
6.4. 
Study Intervention Compliance 
x All participants will be dosed at the site. Participants in the SC treatment arm or their 
caregivers will be trained in self-administration of the IMP. These participants or 
their caregivers will receive specific training for self-administration or caregiver-
supported administration and guidance on preparation, handling, storage and 
administration of the IMP. The first dose of efgartigimod PH20 SC must be 
administered by the investigator or designee, under medical supervision. After 
participants or caregivers are trained in administration, the subsequent doses of 
efgartigimod PH20 SC may be administered by the participant or caregiver under 
supervision by the investigator or designee (see Section 6.2.2). All administrations in 
the IV treatment arm will be performed by the investigator or designee, under medical 
supervision. The date and time of each dose administered in the clinic will be 
recorded in the source documents. The dose of study intervention and study 
participant identification will be confirmed at the time of dosing by a member of the 
study-site staff other than the person administering the study intervention.  
x The investigator should promote treatment compliance by stating that compliance is 
necessary for the participant’s safety and the validity of the study. The prescribed 
dose, timing, and mode of administration cannot be changed. All dates, start and end 
times of IMP administration, and any deviations from the intended regimen must be 
recorded in the eCRF. 
x A sponsor’s designated contract research organization (CRO) monitor will review the 
pharmacy records at each site including the drug accountability and dispensing 
records on which the pharmacist or designated person should record all IMP released 
for participant use. The sponsor’s designated CRO monitor will compare the 
dispensing record and vials with the individual participant’s identifiers, kit number, 
and visit schedule to confirm that the participant received the correct treatment and 
dose, and that the dosing schedule is correct. 

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x Errors that are identified will be communicated to the site personnel to ensure that the 
errors are not repeated. The sponsor’s designated CRO monitor’s report will include 
details of any missed doses, errors in dose, treatment or scheduling errors, and the 
associated explanations. It will be evaluated if these dosing errors will be reported as 
protocol deviations in the clinical database. All supplies and pharmacy documentation 
must be made available throughout the study for the sponsor’s designated CRO 
monitor to review. 
6.4.1. 
Handling Missed Doses of the IMP 
All efforts will be made to ensure that the participant receives all administrations of IMP on the 
scheduled day. If a participant misses any scheduled doses, he/she will not be discontinued from 
the study (see Section 7.1).  
6.4.2. 
Protocol Deviations 
The investigator should not implement any deviation from or changes to the approved protocol 
without agreement of the sponsor and prior review and documented approval of an amendment 
from the Institutional Review Board/Independent Ethics Committee (IRB/IEC) and regulatory 
authority as per local regulation, except where necessary to eliminate an immediate hazard to 
study participants, or when the change involves only logistical or administrative aspects of the 
study (eg, change of telephone numbers). The investigator (or designee) should document and 
explain a deviation from the approved protocol.  
6.5. 
Dose Modification 
No dose modification is planned for this study. 
6.6. 
Continued Access to Study Intervention After the End of the Study 
At the EoS visit on day 71±3, participants will be offered the option to roll over into a single-
arm, open-label, extension study (ARGX-113-2002) to receive efgartigimod PH20 SC 1000 mg. 
Participants who complete the study may be eligible to participate in the extension study.  
6.7. 
Treatment of Overdose 
For this study, any dose of efgartigimod IV or efgartigimod PH20 SC greater than 10% of the 
planned dosage amount (see Section 1.3) will be considered an overdose. There is no 
recommended specific treatment for an overdose of efgartigimod IV or efgartigimod PH20 SC. 
In case of suspected overdose, the participant should be treated according to standard medical 
practice based on the investigator’s judgment. The suspected overdose should be documented in 
the source documents and the eCRF, including any observed AEs. 
6.8. 
Concomitant Therapy 
Any medication or vaccine (including over-the-counter or prescription medicines, recreational 
drugs, vitamins, and/or herbal supplements) that the participant is receiving at the start of the 
study or receives during the study must be recorded in the eCRF along with: 
x Reason for use 

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x Dates of administration including start and end dates 
x Dosage information including dose and frequency 
x Brand name (for vaccines only)   
The medical monitor should be contacted if there are any questions regarding concomitant or 
prior therapy. 
6.8.1. 
Prior Medication and Procedures 
Clinically relevant prior medication and procedures received by the participant must be recorded 
in the eCRF, including the start and stop dates of the therapy and if the therapy is ongoing. 
Clinically relevant prior medications and procedures includes: 
x Prior gMG medications and procedures from 1 year prior to screening, including the 
participant’s response to the therapy and the reason for changing the medication or 
dose 
x Prior non-gMG medication and procedures from 6 months prior to screening 
x All available vaccination history. When a vaccine requires multiple doses (eg, 
influenza vaccine) or a booster, only the most recent vaccination must be recorded 
6.8.2. 
Permitted Concomitant Medication and Procedures 
Participants are required to be on a stable dose of concomitant therapy for gMG. (inclusion 
criterion 7). Permitted concomitant therapy for gMG includes: 
x NSIDs (eg, azathioprine, methotrexate, cyclosporine, tacrolimus, mycophenolate 
mofetil, and cyclophosphamide) 
x steroids 
x AChE inhibitors 
Administration of AChE inhibitors must be withheld for at least 12 hours prior to performing the 
QMG assessment. Complying with this requirement will not be considered a change in the 
patient’s concomitant gMG treatment. 
Participants are allowed to receive vaccines that do not use live or live-attenuated biological 
material. Any inactivated subunit, polysaccharide, or conjugate vaccine is allowed at the 
discretion of the investigator and when administered at least 48 hours predose or 48 hours 
postdose of the IMP. Any vaccination done within 28 days of screening until 28 days after the 
final dose of the IMP must be recorded in the eCRF with the brand name of the vaccine. 
Standard therapies for concurrent medical conditions are permitted if they are not listed as 
prohibited in the following section. 
6.8.3. 
Prohibited Medication and Procedures 
Participants must discontinue from the study intervention if any prohibited therapies are used. 
During the study, participants may NOT receive: 

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x any monoclonal antibody 
x other experimental/study IMP 
x live or live-attenuated vaccines 
x a change in the dose or frequency of their current gMG medication 
x a change in concomitant therapy for gMG 
x PLEX, IVIg, immunoadsorption, or a change in dosage or type of corticosteroid used 
as a monotherapy or in combination 
PLEX, Ig therapy (IVIg and SCIg), immunoadsorption, or a change in dosage or type of 
corticosteroid are considered rescue therapy if both of the following conditions apply: 
1. The treating physician believes that the participant’s health is in jeopardy if rescue 
therapy is not provided, and 
2. The participant is deteriorating clinically according to the protocol-defined criteria, which 
includes at least 1 of the following: 
a. new or worsening of respiratory/bulbar symptoms, or 
b. at least a 2-point increase in any individual nonocular items on the MG-ADL scale as 
compared to the previous visit 
The date and time of rescue medication administration, as well as the name, dosage regimen, and 
response to the rescue medication will be recorded in the eCRF. 

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7. 
DISCONTINUATION OF STUDY INTERVENTION AND 
PARTICIPANT DISCONTINUATION/WITHDRAWAL 
7.1. 
Discontinuation of Study Intervention 
Administration of the IMP may be withheld if, in the opinion of the investigator, it could put the 
participant at undue risk. If the IMP is being withheld and it cannot be administered during the 
scheduled time window, then that dose of IMP must be missed. The subsequent scheduled dose 
of IMP can be administered to the participant at the next scheduled treatment period (TP) visit if 
the investigator determines that the undue risk has been resolved. The participant may continue 
with the study even if they miss multiple doses. 
It may be necessary for a participant to permanently discontinue study intervention.  
Participants must discontinue the study intervention if: 
x It is in the participant’s best interest; discussion with the sponsor’s medical director is 
encouraged prior to discontinuation 
x The participant receives prohibited medication (Section 6.8.3) 
x A severe hypersensitivity reaction to the IMP occurs 
x The participant is pregnant 
x The sponsor requests discontinuation (eg, following DSMB advice, see 
Section 10.1.5.1) 
If study intervention is permanently discontinued, the participant will remain in the study and 
will complete all scheduled visits and the EoS visit on day 71 (±3 days), even though the 
participant will not receive any more doses of the IMP. See the SoA (Section 1.3) for data to be 
collected at the EoS visit. 
7.2. 
Participant Discontinuation/Withdrawal From the Study 
x Early discontinuation from the study is defined as the permanent cessation of further 
participation in the study prior to its planned completion. 
x The reason for early discontinuation from the study will be clearly documented by the 
investigator. 
x A participant may withdraw from the study at any time at his/her own request.  
x The participant will be permanently discontinued both from the study intervention 
and from the study at that time. 
x Participants who discontinue from the study will not be replaced. The sample size is 
inflated to account for attrition. See Section 9.2. 
x If the participant withdraws consent for disclosure of future information, the sponsor 
may retain and continue to use any data collected before such a withdrawal of 
consent. 

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x If a participant withdraws from the study, he/she may request destruction of any 
samples taken and not tested, and the investigator must document this request in the 
site study records and inform the sponsor as soon as possible. 
7.3. 
Lost to Follow-up 
A participant will be considered lost to follow-up if he/she 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: 
x The site must attempt to contact the participant and reschedule the missed visit as 
soon as possible and 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. 
x 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. 
x Should the participant continue to be unreachable, he/she will be considered to have 
withdrawn from the study.  
x Site personnel, or an independent third party, will attempt to collect the vital status of 
the participant within legal and ethical boundaries for all participants randomized, 
including those who did not get study intervention. Public sources may be searched 
for vital status information.  If vital status is determined as deceased, this will be 
documented and the participant will not be considered lost to follow-up. Sponsor 
personnel will not be involved in any attempts to collect vital status information. 
Discontinuation of specific sites or of the study as a whole are handled as part of Section 10.1. 

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8. 
STUDY ASSESSMENTS AND PROCEDURES 
x Study procedures and their timing are summarized in the SoA (Section 1.3). Protocol 
waivers or exemptions are not allowed. 
x Immediate safety concerns should be addressed by the site staff upon occurrence or 
awareness. The investigator may decide whether to discontinue the IMP. If possible, 
the sponsor should be involved in the decision. 
x Adherence to the study design requirements, including those specified in the SoA 
(Section 1.3), is essential and required for study conduct. 
x All screening evaluations must be completed and reviewed, and confirmed by the 
sponsor and/or the sponsor’s designated CRO 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. 
x At screening, all eligibility assessments should be performed after obtaining informed 
consent. 
x When a protocol-required procedure cannot be performed, the investigator will 
document the reason, and any corrective and preventative actions that he/she has 
taken to ensure that the protocol processes are adhered to in the source documents. 
The study team should be informed of these incidents in a timely manner. These 
incidents will be considered a protocol deviation and will be recorded accordingly.  
8.1. 
Efficacy Assessments 
Planned time points for all efficacy assessments are provided in the SoA (Section 1.3). 
8.1.1. 
Pharmacodynamics 
Total immunoglobulin G (IgG), IgG subtypes (IgG1, IgG2, IgG3, and IgG4) levels, and 
AChR-Ab levels will be measured using validated methods from blood sampled as indicated in 
Section 1.3. AChR-Ab levels will only be measured in AChR-Ab seropositive participants. The 
actual date and time of the blood sample collection will be collected and included in the central 
laboratory data transfer. 
8.1.2. 
Clinical Efficacy Assessments 
The MG-ADL and the QMG assessments should be administered by the same evaluator 
throughout the study for a given participant when possible. It is recommended to perform the 
MG-ADL scale prior to all other assessments. 
8.1.2.1. 
MG-ADL  
The MG-ADL is an 8-item patient-reported scale that assesses MG symptoms and their effects 
on daily activities. It evaluates a participant’s capacity to perform different activities in their 
daily life, including talking, chewing, swallowing, breathing, brushing their teeth, combing their 
hair, or getting up from a chair. The MG-ADL also assesses double vision and eyelid droop. It is 
a discrete quantitative variable in which the 8 items are rated by the participant on a scale of 0 to 

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3. The total score can range from 0 to 24, with higher total scores indicating more impairment. 
The MG-ADL assessment does not require any equipment to perform. The scoring of the MG-
ADL should be performed by a trained and certified evaluator. 
8.1.2.2. 
QMG 
The QMG quantifies disease severity based on impairments of body function and structures as 
defined by the International Classification of Functioning, Disability and Health. The QMG 
consists of 13 items that assess ocular, bulbar, and limb function. Six of the 13 items are timed 
endurance tests measured in seconds. Each item has a possible score from 0 to 3. The total 
possible score is 39, where higher total scores indicate more severe impairments. It is based on 
qualitative testing of specific muscle groups to assess limb function. The QMG requires minimal 
equipment, such as a spirometer, mouthpieces that fit the spirometer, nose clips, a stopwatch, 
cups and water for the swallowing tests, a goniometer, and a dynamometer. The scoring of the 
QMG should be performed by a trained evaluator and the scoring is based on the evaluator’s 
examination. 
8.1.3. 
Myasthenia Gravis Quality of Life Questionnaire (15-item Scale Revised) 
The Myasthenia Gravis Quality of Life Questionnaire (15 item scale revised) (MG-QoL15r) is a 
15-item survey of a patient’s perceived health-related quality of life and addresses attributes 
known to be meaningful to a patient with gMG, such as psychological well-being and social 
functioning. The patient assesses statements using a 3-point (0–2) Likert scale on the following 
domains: 
x mobility (9 items) 
x symptoms (3 items) 
x general contentment (1 item) 
x emotional well-being (2 items) 
Each item will be participant-scored using a 3-point severity scale ranging from 0 (not at all) to 2 
(very much), with a maximum possible score of 30. The MG-QoL15r is helpful in determining 
the participant’s perception of the extent and dissatisfaction of MG-related dysfunction. 
8.1.4. 
EuroQoL 5 Dimensions 5 Levels 
The EuroQoL 5 Dimensions 5 Levels (EQ-5D-5L) is a standardized measure of health status and 
was developed by the EuroQoL Group to provide a simple, generic measure of health status for 
clinical and economic appraisal. The descriptive system comprises 5 dimensions:  
x mobility 
x self-care 
x usual activities 
x pain/discomfort 
x anxiety/depression 

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Each dimension has 5 levels: 
x no problem 
x slight problem 
x moderate problem 
x severe problem 
x extreme problem 
The participant will be asked to indicate his/her health state by ticking (or placing an “x” in) the 
box against the most appropriate statement in each of the 5 dimensions. This decision results in a 
1-digit number expressing the level selected for that dimension. The digits for 5 dimensions were 
combined in a 5-digit number describing the respondent’s health state. A unique health state is 
defined by combining 1 level from each of the 5 dimensions. A total of 3125 possible health 
states could be defined in this way. Each state is referred to in terms of a 5-digit code. For 
example, state 11111 would indicate no problems in any of the 5 dimensions, while state 12345 
would indicate no problem with mobility, slight problems with washing or dressing, moderate 
problems with doing usual activities, severe pain or discomfort, and extreme anxiety or 
depression.  
A visual analog scale is included in the questionnaire. Respondents are asked to mark the health 
status from 0 to 100 on the day the interview is conducted, with a score of 0 corresponding to 
“the worst health you can imagine” and 100 corresponding to “the best health you can imagine.” 
8.2. 
Safety Assessments 
Planned time points for all safety assessments are provided in the SoA (Section 1.3). 
8.2.1. 
Demographics 
Demographic characteristics comprise age, year of birth, gender, race, and ethnicity (per local 
regulations). Source data verification will be performed on race and ethnicity unless it is 
prohibited by local regulations. 
8.2.2. 
Physical Examinations 
x A complete physical examination will include, at a minimum, assessments of the 
participant’s general appearance, skin, lymph nodes, musculoskeletal/extremities, 
abdomen, cardiovascular, respiratory, and neurological systems. 
x Height will be measured at screening only.  
x Weight will also be measured at screening, baseline, and at the EoS visit. The 
participant is allowed to wear indoor daytime clothing with no shoes. 
x Investigators should pay special attention to clinical signs related to previous serious 
illnesses. 

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8.2.3. 
Vital Signs 
x Vital signs (to be taken before blood collection for laboratory tests) will be measured 
in a semi-supine position after 5 minutes rest and will include temperature, systolic 
and diastolic blood pressure, and pulse.  
x It is recommended that the method used to measure body temperature at screening is 
maintained throughout the study. 
x Blood pressure and pulse measurements will be assessed in a supine position with a 
completely automated device. Manual techniques will be used only if an automated 
device is not available. 
x 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). 
8.2.4. 
Electrocardiograms 
Single 12-lead ECG will be obtained after the participant has rested in a supine position for 
5 minutes as outlined in the SoA (see Section 1.3) using an ECG machine that automatically 
calculates the heart rate and measures time between heart beats (RR), atrioventricular nodal 
delay (PR), duration of ventricular depolarization (QRS), total duration of ventricular 
depolarization (QT), and rate-corrected QT intervals using Fridericia’s formula (QTcF). ECGs 
will be performed predose on dosing days. 
8.2.5. 
Medical and Surgical History 
Medical history will include: 
x All relevant medical history (eg, significant findings, surgeries and pre-existing 
conditions present at screening) must be recorded in the eCRF regardless of whether 
it is related to gMG. 
x Previous emergency room (ER) visits, hospitalizations, and intensive care unit (ICU) 
admissions from 1 year prior to screening, including the number of days admitted. 
x Abnormalities in physical examination, vital signs and ECG at screening must be 
reported as medical history in eCRF. At all other visits, new abnormal or worsened 
pre-existing conditions will be reported as AE. 
8.2.6. 
Clinical Safety Laboratory Assessments 
x See Section 10.2 for the list of clinical laboratory tests to be performed and to the 
SoA (Section 1.3) for the timing and frequency. The details of sampling, handling, 
storage, and transportation of the samples will be described in the laboratory manual. 
The actual sample collection date and time must be collected in the participant’s 
source document and included in the central laboratory data transfer. 
x The investigator must review the laboratory report, document this review, and record 
any clinically significant changes occurring during the study as an AE. The laboratory 
reports must be filed with the source documents.  

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x All routine laboratory safety assessments must be performed by the central 
laboratory. 
x Abnormal laboratory findings associated with the underlying disease are not 
considered clinically significant unless judged by the investigator to be more severe 
than expected for the participant's condition. 
x 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 any values do not return to normal/baseline within a period of time judged 
reasonable by the investigator, the etiology should be identified, and the sponsor 
notified. 
 All protocol-required laboratory tests, as defined in Section 10.2, must be 
conducted in accordance with the laboratory manual and the SoA (Section 1.3).  
 If laboratory values from nonprotocol specified laboratory tests performed at the 
institution’s local laboratory require a change in participant management or are 
considered clinically significant by the investigator (eg, SAE or AE or dose 
modification), then the outcomes must be recorded. 
8.2.6.1. 
Hematology, Clinical Chemistry, and Urinalysis 
Blood and urine samples for clinical safety laboratory assessments, including hematology, blood 
chemistry, and urinalysis, will be collected at the timepoints specified in the SoA (Section 1.3). 
The list of clinical safety laboratory parameters for hematology, clinical chemistry, and 
urinalysis are provided in Table 3. 
x Blood samples for clinical laboratory assessments will be taken while the participant 
is in the fasted condition, defined as no food or drink (except for water) for 8 hours. 
Water is permitted up to 4 hours prior to the assessment. 
x Blood samples for safety assessments will be collected according to the laboratory 
manual. 
x The samples will be analyzed at the central laboratory. 
x Clinical laboratory tests will be reviewed for potential clinically significant findings 
at all time points throughout the study. Findings meeting the definition of an AE (see 
Section 10.4) must be recorded on an AE page of the eCRF. See Section 10.4.3 for 
information on following up of clinically significant abnormalities. 
x Laboratory tests with values considered clinically significantly abnormal during the 
study that meet the definition of an AE will be monitored until the values return to 
normal or baseline or are no longer considered clinically significant by the 
investigator or medical monitor. 

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8.2.6.2. 
Virus Serology 
For exclusion criterion 7.a, blood will be sampled and evaluated for virus serology as described 
in Section 10.2.  
8.2.6.3. 
Follicle-Stimulating Hormone Level 
Female participants must have their follicle-stimulating hormone (FSH) level measured at the 
time points listed in the SoA (Section 1.3) as described in Section 10.2. 
8.2.6.4. 
SARS-CoV-2 Test 
Nasal and throat mucosal cell samples will be collected according to the laboratory manual at the 
time points specified in the SoA (Section 1.3) to be tested for SARS-CoV-2. 
8.2.7. 
Assessment of Administration Site 
The injection site of participants receiving efgartigimod PH20 SC will be continuously assessed 
by the participant (see Section 1.3). On dosing days, the assessment will be performed by the 
investigator prior to dosing and 1 hour after dosing. After participants have received 
efgartigimod the assessment will include asking the participants about any injection site reactions 
that occurred between visits. Any injection site reaction will be reported as an AE (Section 8.3). 
8.2.8. 
Pregnancy Testing 
x Refer to inclusion criteria 8.b for pregnancy testing entry criteria. 
x Pregnancy testing at screening will be a highly sensitive serum test, and all 
subsequent pregnancy testing will be done using urine tests. Pregnancy testing should 
be conducted as indicated in the SoA (Section 1.3) during the study. If local 
regulations require more frequent or sensitive testing, then the local regulations will 
be followed. 
x Pregnancy testing (urine or serum as required by local regulations) should be 
conducted at the end of relevant systemic exposure. 
x Additional serum or urine pregnancy tests may be performed, as determined 
necessary by the investigator or required by local regulations, to establish the absence 
of pregnancy at any time during the subject's participation in the study. 
8.2.9. 
Immunogenicity 
8.2.9.1. 
ADA Against Efgartigimod 
Blood samples will be collected to assess the serum levels of ADA against efgartigimod as 
indicated in the SoA (Section 1.3). Sampling will be done predose on IMP administration visits. 
As per regulations, all samples will be analyzed in a 3-tiered approach using validated methods8: 
1. First, all samples will be evaluated in a screening assay (tier 1) and scored as ADA 
positive or negative. 

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2. Samples that screen positive in tier 1 will be evaluated in the confirmatory ADA assay to 
assess the specificity of the ADA response. The samples will be scored as either 
confirmed positive (ie, positive immunodepletion) or confirmed negative (ie, negative 
immunodepletion). 
3. Samples confirmed to be positive for ADA in tier 2 will be further analyzed in a titration 
assay to characterize the magnitude of the ADA response and a neutralizing antibody 
(NAb) assay to assess the ADA for neutralizing activity. 
If no sample was taken, the reason will be recorded. 
8.2.9.2. 
ADA Against rHuPH20 
Blood samples will be collected to assess the plasma levels of ADA against rHuPH20 as 
indicated in the SoA (Section 1.3). Sampling will be done predose on IMP administration visits. 
As per regulations, all samples will be analyzed in a 3-tiered approach using validated methods8: 
1. First, all samples will be analyzed in a screening assay (tier 1), which identifies putative 
positive or negative samples. 
2. Samples that screen positive in tier 1 will be evaluated in the confirmatory ADA assay to 
assess the specificity of the ADA response. The samples will be scored as either 
confirmed positive or negative. 
3. Samples confirmed to be positive for ADA in tier 2 will be further analyzed in a titration 
assay to characterize the magnitude of the ADA response and a neutralizing antibody 
(NAb) assay to assess the ADA for neutralizing activity. 
If no sample was taken, the reason will be recorded in the relevant section of the eCRF. 
8.2.10. 
Suicidal Ideation and Behavior Risk Monitoring 
x Efgartigimod is being developed for a neurologic indication, so suicidal ideation and 
risk behavior monitoring (SIB) is required. 
x Participants being treated with efgartigimod 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. 
x Participants who experience signs of suicidal ideation or behavior, should undergo a 
risk assessment. All factors contributing to suicidal ideation and behavior (SIB) 
should be evaluated and consideration should be given to discontinuation of the study 
intervention. 
x Baseline assessment of suicidal ideation and behavior and intervention emergent 
suicidal ideation and behavior will be monitored by asking the following question 
derived from the Patient Health Questionnaire (PHQ) item 9: "Over the last 2 weeks, 
how often have you been bothered by thoughts that you would be better off dead, or 
of hurting yourself in some way?" 

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8.3. 
Adverse Events (AEs), Serious Adverse Events (SAEs), and Other 
Safety Reporting 
x The definitions of AEs and SAEs can be found in Section 10.4. 
x AEs will be reported by the participant (or, when appropriate, by a caregiver, 
surrogate, or the participant's legally authorized representative). 
x 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). 
x An unexpected AE is any adverse drug event, which is not listed in the reference 
safety information in the current IB or is not listed at the specificity or intensity that 
has been observed in the current study. 
x Suspected adverse drug reaction means any AE for which there is a reasonable 
possibility that the IMP caused the AE. 
x Each AE is to be evaluated for duration, severity (using the Common Terminology 
Criteria for Adverse Events [CTCAE] criteria version 5.0), seriousness, and causal 
relationship to the IMP or study procedures. The action taken with the investigational 
drug and the outcome of the event must also be recorded. 
x 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 10.4. 
8.3.1. 
Time Period and Frequency for Collecting AE and SAE Information 
x All AEs and SAEs will be collected from the signing of the ICF until the EoS visit at 
the time points specified in the SoA (Section 1.3). 
x All SAEs will be recorded and reported to the sponsor or designee immediately and 
under no circumstance should this exceed 24 hours from awareness of the site staff, 
as indicated in Section 10.4. The investigator will submit any updated SAE data to the 
sponsor within 24 hours of it being available. 
x Investigators are not obligated to actively seek information on AEs or SAEs 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 the sponsor. 
8.3.2. 
Method of Detecting AEs and SAEs 
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. 

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8.3.3. 
Follow-up of AEs and SAEs 
After the initial AE/SAE report, the investigator is required to proactively follow each participant 
at subsequent visits/contacts. All SAEs and AEs of special interest (AESI) as defined in 
Section 8.3.6 will be followed 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 10.4.3. 
8.3.4. 
Regulatory Reporting Requirements for SAEs 
x Prompt notification by the investigator to the sponsor of an SAE is essential so that 
legal obligations and ethical responsibilities toward the safety of participants and the 
safety of a study intervention under clinical investigation are met. 
x The sponsor 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. The sponsor will comply with country-specific regulatory requirements 
relating to safety reporting to the regulatory authority, IRB/IEC, and investigators. 
x An investigator who receives an investigator safety report describing an SAE or other 
specific safety information (eg, summary or listing of SAEs) from the sponsor will 
review and then file it along with the IB and will notify the IRB/IEC, if appropriate 
according to local requirements. 
x The sponsor (or its designee) will be responsible for reporting suspected unexpected 
serious adverse reactions (SUSARs) to the relevant regulatory authorities and the 
IEC/IRB as per applicable regulatory requirements. The sponsor (or its designee) will 
also be responsible to forward SUSAR reports to all investigators involved in the 
study, who will also be required to report these SUSARs to their respective 
IECs/IRBs, as per their local regulatory requirements. 
8.3.5. 
Pregnancy 
x Details of all pregnancies in female participants will be collected after the start of 
study intervention and until 90 days after the last dose of the study IMP. 
x Attempts will be made to obtain details of all pregnancies in female partners of male 
participants that occurred after the start of study intervention and until 90 days after 
the last dose of IMP. Female partners will be asked to sign a relevant ICF. 
x If a pregnancy is reported, the investigator will record pregnancy information on the 
appropriate form and submit it to the sponsor within 24 hours of learning of the 
female participant or female partner of male participant (after obtaining the necessary 
signed informed consent from the female partner) pregnancy. 
x 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. 

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x Abnormal pregnancy outcomes (eg, spontaneous abortion, fetal death, stillbirth, 
congenital anomalies, ectopic pregnancy) are considered SAEs and will be reported 
as such. 
x The pregnant participant will be followed to determine the outcome of the pregnancy. 
The investigator will collect follow-up information on the participant and the neonate 
and the information will be forwarded to the sponsor. 
x If a female partner of a male participant consents, the female partner will be followed 
to determine the outcome of the pregnancy. In this case, the investigator will collect 
follow-up information on the female partner and the neonate and the information will 
be forwarded to the sponsor. 
x Any post-study pregnancy-related SAE considered reasonably related to the study 
intervention by the investigator will be reported to the sponsor as described in 
Section 8.3.4. While the investigator is not obligated to actively seek this information 
in former study participants or pregnant female partners of former male study 
participants, he/she may learn of an SAE through spontaneous reporting. 
x Any female participant who becomes pregnant while participating in the study will be 
discontinued from the study intervention and will continue with all remaining visits, 
including the EoS visit. 
8.3.6. 
Adverse Events of Special Interest 
An AESI is an event of scientific and medical concern specific to the sponsor’s product or 
program (eg, an underlying condition being investigated, a mechanism of action/potential 
immunosuppression). An AESI can be serious or nonserious and related or unrelated to study 
IMP or procedures. Further characterizing information will be collected in the eCRF.  
Efgartigimod treatment induces reductions in the IgG levels and there is a potential risk for 
infections associated with low IgG levels. As such, any infections are considered AESIs in this 
study. Further information to be collected in the eCRF will include: 
x Location of the infection 
x Relationship to the underlying condition, medical history, and concomitant 
medications 
x Reoccurrence of previous infection 
x Previous rescue therapy 
x Any confirmatory procedure, culture, or urgent medical intervention 
8.4. 
Pharmacokinetics 
x Blood samples for pharmacokinetics (PK) will be collected from each participant as 
specified in the SoA (Section 1.3). Concentrations of efgartigimod will be determined 
using a validated method. 

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x Instructions for the collection and handling of biological samples will be provided by 
the sponsor. The actual date and time (24-hour clock time) of each sample will be 
recorded. 
x Samples collected for analyses of efgartigimod concentration may also be used to 
evaluate safety or efficacy aspects related to concerns arising during or after the 
study. 
x At visits during which blood samples for the determination of multiple aspects of 
efgartigimod will be taken, 1 sample of sufficient volume can be used. 
x For the efgartigimod IV treatment arm, PK sampling will be performed both predose 
(within 1 hour prior to the start of the infusion) and postdose (within 1 hour after the 
end of the infusion) on dosing days. For the efgartigimod PH20 SC treatment arm, PK 
sampling will only be done predose (within 1 hour prior to the injection) on dosing 
days. 
x The following PK parameters will be measured: Cmax of efgartigimod (after all doses 
for the IV treatment arm) and Ctrough of efgartigimod in both arms.  
8.5. 
Genetics and/or Pharmacogenomics 
Genetics are not evaluated in this study. 
8.6. 
Biomarkers 
See Section 8.1.1 for assessments of total IgG levels, IgG subtype levels, and AChR-Ab levels. 
8.7. 
Immunogenicity Assessments 
See Section 8.2.9 for immunogenicity assessments. 
8.8. 
Medical Resource Utilization and Health Economics 
Medical resource utilization and health economics data including ER visits, hospitalizations, and 
ICU admissions for any reason from 12 months prior to screening will be collected as medical 
history. All hospitalizations, ER visits, and ICU admissions will be collected during the study 
and analyzed, even if they are not classified as AEs, to compare medical resource utilization 
before and after efgartigimod treatment. These data will also be collected in the extension study 
ARGX-113-2002. 
8.9. 
Storage of Blood Samples After the Study 
Any samples remaining after the laboratory analyses defined in the protocol have been 
completed may be stored for up to 15 years after the end of the study for additional medical, 
academic, or scientific research to address any scientific questions related to efgartigimod, FcRn 
biology, or gMG. The samples may be stored in the laboratory or long-term storage designated 
by the sponsor or research partners worldwide. The storage and future use of samples obtained 
during this study is permitted unless local regulations do not allow it or if the participant did not 
consent.  

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In addition, blood samples may be used to validate methods to measure efgartigimod, antibodies, 
and biomarkers. 

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9. 
STATISTICAL CONSIDERATIONS 
The statistical analysis will be performed by the sponsor’s designated CRO using statistical 
analysis systems (SAS) software (SAS Institute, Cary, NC, United States) version 9.4 or higher, 
and the software package R, if applicable. The standard operating procedures (SOPs) and work 
instructions of the sponsor’s designated CRO will be used as the default methodology if not 
otherwise specified.  
A detailed and comprehensive Statistical Analysis Plan (SAP) will be written and signed-off 
prior to final analysis database lock. Minor changes to the statistical methods set out in this 
protocol do not require a protocol amendment but will be documented (as changes from the 
protocol) in the SAP and in the clinical study report(s). The below sections contain the main 
general features of the statistical analysis. More details will be provided in the SAP. 
9.1. 
Statistical Hypotheses 
The confirmation of the noninferiority (NI) of efgartigimod PH20 SC with efgartigimod IV will 
be based on the total IgG percent reduction at day 29 utilizing a noninferiority margin of 10. See 
Section 9.2 for justification of the noninferiority margin. The hypotheses for the evaluation of 
noninferiority are as follows: 
x Null hypothesis: the difference in percent reduction from baseline of total IgG at 
day  IRU WKH 6& WUHDWPHQW DUP DV FRPSDUHG WR WKH ,9 WUHDWPHQW DUP ZLOO EH 
(ie, ȝIV - ȝSC  
x Alternate hypothesis: the difference in percent reduction from baseline of total IgG at 
day 29 for the SC treatment arm as compared to the IV treatment arm will be <10 
(ie, ȝIV - ȝSC <10) 
9.2. 
Sample Size Determination 
The noninferiority (NI) evaluation will be based on the percent reduction from baseline in total 
IgG levels at day 29. 
To evaluate the relationship between changes in total IgG and MG-ADL, statistical modeling on 
MG-ADL change from study baseline with total IgG percent reduction from study baseline as a 
predictor and participant as a random effect was performed among all study ARGX-113-1704 
participants on the efgartigimod IV 10 mg/kg treatment arm in the modified intention-to-treat 
(mITT) analysis set. Data from all cycles in the study were included. To minimize potential 
modeling bias introduced by outlier data points, only week 1 to week 6 data were included and 
data after week 6 were excluded. The modeling results demonstrate that total IgG percent change 
from study baseline and MG-ADL change from study baseline were highly correlated 
(p-value <0.0001) as illustrated in Figure 2. With a difference of 10 in the mean total IgG percent 
reduction (eg, from total IgG percent reduction of 63 to total IgG percent reduction of 53) the 
mean difference in MG-ADL improvement (ie, decrease from baseline) is expected to be 0.35 
(2-sided 95% confidence interval, 0.236 to 0.465). In the phase 3 study ARGX-113-1704, the 
mean of MG-ADL improvement at week 4 of cycle 1 was 4.5 (standard error 0.36) in the 
efgartigimod treatment group and 2.0 (standard error 0.27) in the placebo treatment arm, which 
translates to a treatment effect of 2.5 (2-sided 95% confidence interval, 1.62 to 3.38). The 
corresponding mean of total IgG percent reduction at week 4 of cycle 1 was 62.2 (standard error 

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0.82) in the efgartigimod treatment arm and 0.1 (standard error 2.23) in the placebo treatment 
arm, which translates to a treatment effect of 62.1 (2-sided 95% confidence interval, 57.44 to 
66.76). With a NI margin of 10 in IgG percent reduction, 84% (1–10/62.2 x 100%) of the PD 
effect as assessed by total IgG reduction is expected to be preserved, whereas 86% (1–0.35/2.5 x 
100%) of the clinical effect as assessed by MG-ADL change is expected to be preserved. 
Figure 2: 
Statistical Modeling on MG-ADL Change From Baseline With IgG Percent 
Reduction From Baseline as a Predictor and Patient as a Random Effect in 
All Efgartigimod IV Treated Patients in Study ARGX-113-1704 (mITT 
Analysis Set) 
 
IgG= immunoglobulin G; IV=intravenous(ly); MG-ADL=Myasthenia Gravis Activities of Daily Living; 
mITT=modified intention-to-treat 
Note: To minimize potential modeling bias introduced by outlier data points, only week 1 to week 6 data from all 
cycles in study ARGX-113-1704 were included. 
 
Based on data from the phase 3 study ARGX-113-1704, the mean percent decrease in total IgG 
levels with the IV formulation is expected to be approximately 62 (standard deviation 7.5). 
Assuming the total IgG percent reduction from baseline with the SC formulation is 60 (2 less 
compared to the IV formulation) along with a standard deviation of 7.5, 20 participants per 
treatment arm are needed to reach 90% power to detect noninferiority using a 1-sided 2-sample t-
test at a 2.5% level of significance. To account for participant discontinuation, 3 additional 
participants per treatment arm have been added. A sample size of 46 participants will need to be 
enrolled and randomized, allowing for a 13% attrition rate. 

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The assumptions utilized in the sample size calculations will be evaluated in study 
ARGX-113-1907, which will compare the PD, PK, safety, and tolerability of multiple doses of 
efgartigimod PH20 SC and efgartigimod IV in healthy participants. Study ARGX-113-1907 will 
use the same dosage as in the current study and will provide a detailed assessment of the PD 
effect in healthy participants, which is expected to represent the effect in participants with gMG. 
If the results of study ARGX-113-1907 indicate that the pooled standard deviation of the mean 
percent decrease in total IgG levels is larger than 7.5, the sample size will be adapted 
accordingly. If the pooled standard deviation is:  
x 8.5, then a total of 50 participants will be recruited, with 6 additional participants 
added to account for discontinuations for a total of 56 participants (based on a pooled 
standard deviation of 8.5) 
x 10.0, then a total of 68 participants will be recruited, with 8 additional participants 
added to account for discontinuations for a total of 76 participants (based on a pooled 
standard deviation of 10) 
Seventy-six participants would suffice for the noninferiority comparison between SC and IV 
based on IgG reduction at day 29; however, increasing the sample size to approximately 110 
participants will provide better quantification of the clinical safety and efficacy profile of the SC 
formulation in patients with gMG while the IV formulation will serve as a reference treatment in 
this randomized study. 
Note: “Enrolled” means a participant's, or their legally acceptable representative’s, agreement to 
participate in a clinical study following completion of the informed consent process and 
screening. Potential participants who are screened to determine eligibility for the study, but do 
not participate in the study, are not considered enrolled unless otherwise specified by the 
protocol. “Randomized” means that an enrolled participant has been randomly assigned to a 
treatment arm. 
9.3. 
Analysis Sets 
The following analysis sets are defined: 
Table 2: 
Analysis Sets 
Analysis Sets 
Description 
Safety analysis set  
All randomized participants who are exposed to 
the IMP  
Intention-to-treat set  
All randomized participants with a value for total 
IgG levels at baseline and at least 1 post-baseline 
timepoint 
PK analysis set 
Subset of safety analysis set with at least 1 
postdose PK measurement 
9.4. 
Statistical Analyses 
The SAP will be finalized before database lock and will include a more technical and detailed 
description of the statistical analyses described in this section. This section is a summary of the 

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planned statistical analyses of the most important endpoints including primary and key secondary 
endpoints. 
9.4.1. 
General Considerations 
x The baseline value will be defined as the last assessment prior to the first 
administration of efgartigimod. 
x All study visits will be recalculated based on actual dates and will be referred to as 
“analysis visits,” which will be used in the statistical analyses. The rules for 
calculating the analysis visits will be documented in the SAP. Rules for inputting 
partial dates or missing dates will also be documented in the SAP. 
9.4.2. 
Primary Endpoint 
Definition of the Estimand for the Primary Endpoint 
x Population: intention-to-treat (ITT) analysis set (see Table 2) 
x Variable: Percent reduction from baseline in total IgG levels at day 29 
x Main intercurrent events: 
 early treatment discontinuation for any reason prior to day 29 
 initiation of Ig therapy (IVIg and SCIg) as rescue therapy prior to day 29 
 missed doses 
Handling of Main Intercurrent Events 
For early treatment discontinuation or missed doses, the observation captured 7 days after the 
last dose will be used. If Ig therapy is used as rescue therapy prior to day 29, the last observation 
prior to the initiation of Ig therapy will be used. 
Estimation of Treatment Effect and Statistical Inference 
An analysis of covariance model (ANCOVA) will be used to estimate the mean percent 
reduction in total IgG levels from baseline at day 29 for each treatment arm, as well as the 
2-sided 95% confidence interval for the difference between the 2 treatment arms. The model will 
include treatment as a factor and baseline total IgG level as a covariate. 
When the upper limit of the 95% confidence interval (mean percent reduction with IV – mean 
percent reduction with SC) is below the margin of 10, the SC formulation will be considered 
noninferior to the IV formulation. 
Complementary Analyses 
To facilitate interpretation of the estimated treatment effect in the primary analysis, sensitivity 
analyses will be conducted where the main intercurrent events will be handled differently. 
Details will be provided in the SAP. 

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9.4.3. 
Secondary Endpoints 
All secondary endpoints will be summarized with descriptive statistics by treatment arm and 
overall among all participants in an appropriate analysis set. Categorical variables will be 
summarized with the number and percent of participants in each category. Continuously 
variables will be summarized with N, mean, standard deviation, 95% 2-sided confidence interval, 
median, first quartile (Q1), third quartile (Q3), minimum, and maximum. 
In addition, the difference in the percentage of MG-ADL responders between the 2 treatment 
arms will be analyzed using the meta-analysis predictive approach while incorporating the 
treatment cycle 1 data from the efgartigimod IV treatment arm in study ARGX-113-1704 as 
historical active controls.7  
9.4.4. 
Exploratory Endpoints 
Exploratory endpoints will be summarized with descriptive statistics by treatment arm and 
overall among all participants in the ITT analysis set. 
9.5. 
Interim Analysis 
Interim analyses may be performed to support questions from authorities and/or submissions. 

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10. 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
10.1. 
Appendix 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 with the following: 
x Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical 
Sciences (CIOMS) International Ethical Guidelines 
x Applicable International Council for Harmonisation (ICH) Good Clinical Practice 
(GCP) Guidelines 
x Applicable laws and regulations 
The protocol, protocol amendments, ICF, IB, and other relevant documents (eg, advertisements) 
must be submitted to an Institutional Review Board/Independent Ethics Committee (IRB/IEC) 
by the investigator and reviewed and approved by the IRB/IEC before the study is initiated. 
x Any amendments to the protocol will require IRB/IEC approval before 
implementation of changes made to the study design, except for changes necessary to 
eliminate an immediate hazard to study participants.  
x Protocols and any substantial amendments to the protocol will require health 
authority approval prior to initiation except for changes necessary to eliminate an 
immediate hazard to study participants. 
The investigator will be responsible for the following: 
x 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 
x Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures 
x 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, 
European regulation 536/2014 for clinical studies, and all other applicable local 
regulations 
10.1.2. 
Financial Disclosure 
The sponsor will fund the study as outlined in the clinical study agreement. 
The sponsor will obtain adequate global/local insurance for the study participants including the 
study participants for the required duration of time. 

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The sponsor maintains an insurance coverage for this study in accordance with the laws and 
regulations of the countries in which the study is performed. Liability and insurance provisions 
for this study are specified in the investigator’s contract. The terms and conditions will apply as 
specified in the policy document. 
Investigators and sub-investigators will provide the sponsor with sufficient accurate financial 
information as requested to allow the sponsor to submit complete and accurate financial 
certification or disclosure statements to the appropriate regulatory authorities. Investigator 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 
x Prior to signing the ICF, the study participants will be instructed not to participate in 
any other clinical study that involves a therapeutic intervention until the completion 
of the study. 
x Any participant that provides informed consent will be assigned a unique participant 
ID via the Interactive Response Technology (IRT) system. 
x The investigator or his/her representative will explain to the participant all of the 
following: the nature of the study, its purpose, the procedures involved, the expected 
duration, any potential discomfort, potential alternative procedure(s) or course(s) of 
treatment available, and the extent of maintain the confidentiality of the participant’s 
records. The investigator or his/her representative will answer all questions from the 
participant regarding the study. 
x Participants must be informed that their participation is voluntary, that they may 
withdraw from the study at any time, and that withdrawal of consent will not affect 
their subsequent medical treatment or relationship with the treating physician. 
x Participants will be required to sign a statement of informed consent, after receipt of 
detailed information on the study, that meets the requirements of 21 CFR 50, local 
regulations, ICH guidelines, Health Insurance Portability and Accountability Act 
(HIPAA) requirements, where applicable, and the IRB/IEC or study center. 
x The ICF will be used to explain the potential risks and benefits of study participation 
to the participant in simple terms before the participant is screened. 
x The medical record must include a statement that written informed consent was 
obtained before the participant was enrolled in the study and the date the written 
consent was obtained. The authorized person obtaining the informed consent must 
also sign the ICF. 
x A separate ICF will be issued in case of pregnancy of a female partner of a male 
participant. If required by local regulations, a separate pregnancy ICF will be issued 
for female participants who become pregnant.  
x All participant information and ICFs must be available in the local and vernacular 
languages required at the site and include participant information sheets/brochures 

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that outline the study procedures. All ICF(s) must be signed and dated by the 
participant. 
x Participants must reconsent to the most current version of the ICF(s) during their 
participation in the study. 
x The investigator is responsible for ensuring that informed consent is obtained from 
each participant and for obtaining the appropriate signatures and dates on the ICF 
prior to the performance of any protocol procedures and prior to the administration of 
the IMP. 
x A copy of the signed and dated ICF(s) must be provided to the participant. 
x A participant who is rescreened or retested is not required to sign another ICF if the 
rescreening occurs within the screening period. 
10.1.4. 
Data Protection 
x Participants will be assigned a unique identifier by the sponsor. Any participant 
records or datasets that are transferred to the sponsor will contain the identifier only; 
participant names or any information which would make the participant identifiable 
will not be transferred. 
x The participant must be informed that his/her personal study-related data will be used 
by the sponsor in accordance with local data protection law. The level of disclosure 
must also be explained to the participant who will be required to give consent for 
their data to be used as described in the informed consent.  
x The participant must be informed that his/her medical records may be examined by 
Clinical Quality Assurance auditors or other authorized personnel appointed by the 
sponsor, by appropriate IRB/IEC members, and by inspectors from regulatory 
authorities. 
10.1.5. 
Committees Structure 
10.1.5.1. Data Safety Monitoring Board 
x Participant safety will be monitored by an independent DSMB, which includes safety 
signal detection at any time during the study. 
x The DSMB will consist of an independent group of clinical experts who are not 
involved in the study management. The objective of the DSMB will be to review and 
evaluate all available safety data. The planning and frequency of the meetings will be 
detailed in the DSMB charter. Additionally, ad hoc meetings can be requested at any 
time during the study by the sponsor or the DSMB.  
x The DSMB will advise the sponsor regarding continuation, modification, temporary 
discontinuation, or termination of the study after every meeting. 
x The composition, objectives, role, and responsibilities of the DSMB will be described 
in the DSMB charter, which will be agreed to by the DSMB members and the 

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sponsor. The DSMB charter will also define and document the content of safety 
summaries and general procedures, including communications. 
10.1.6. 
Dissemination of Clinical Study Data 
x The sponsor or designee and auditor may access participant records for the purpose of 
monitoring this study, auditing, and managing progress details. The investigator must 
be fully aware that the sponsor or designee and auditor can inspect or verify 
documents to verify participant’s chart and eCRF records. Such information must be 
kept confidential in locked facilities that allow for this. The investigator will prepare 
and maintain adequate and accurate source documents to record all observations and 
other pertinent data for each participant screened for the study. 
x The investigator is responsible for maintaining source documents. These will be made 
available for verification by the sponsor’s designated CRO monitor at each 
monitoring visit. The investigator must submit an eCRF for each participant, 
regardless of duration of participation or administration of IMP (ie, an eCRF has to be 
submitted for screen failures as well). All supportive documentation submitted with 
the eCRF, such as laboratory or hospital records, should be clearly identified with the 
study and participant number. Any personal information, including participant name, 
should be removed or rendered illegible to preserve data privacy. 
10.1.7. 
Data Quality Assurance 
x All participant data relating to the study will be recorded on printed or electronic CRF 
unless transmitted to the sponsor or designee electronically (eg, laboratory data). The 
investigator is responsible for verifying that data entries are accurate and correct by 
electronically signing the CRF. 
x The investigator must maintain accurate documentation (source data) that supports 
the information entered in the eCRF if and where applicable. No source data 
verification will be performed on race and ethnicity only if requested per local 
regulations. 
x Guidance on completion of eCRFs will be provided in the eCRF completion 
guidelines by the designated CRO.  
x The investigator must permit study-related monitoring, audits, IRB/IEC review, and 
regulatory agency inspections and provide direct access to source data documents. 
x Monitoring details describing strategy (eg, risk-based initiatives in operations and 
quality such as Risk Management and Mitigation Strategies and Analytical Risk-
Based Monitoring), methods, responsibilities and requirements, including handling of 
noncompliance issues and monitoring techniques (central, remote, or on-site 
monitoring) are provided in the monitoring plan. 
x The sponsor or designee is responsible for the data management of this study, 
including quality checking of the data. 
x The sponsor assumes accountability for actions delegated to other individuals 
(eg, CROs). 

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x 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.  
10.1.7.1. Data Handling and Record Keeping 
It is the investigator’s responsibility to maintain essential study documents (records and 
documents pertaining to the conduct of this study and the distribution of IMP, including 
regulatory documents, eCRFs, signed participant ICFs, laboratory test results, IMP inventory 
records, source documents, relevant correspondence, AE reports, and all other supporting 
documentation) as required by the applicable national regulatory requirements. The study site 
should plan on retaining such documents for approximately 25 years after study completion. The 
study site should retain such documents until at least 2 years after the last approval of a 
marketing application in an ICH region and until there are no pending or contemplated marketing 
applications in an ICH region, or at least 2 years after the formal discontinuation of clinical 
development of the IMP. The sponsor will notify the principal investigator of these events.  
These documents should be retained for a longer period if required by the applicable regulatory 
requirements or the hospital, institution, or private practice in which the study is being 
conducted. Participant identification codes (participant names and corresponding study numbers) 
will be retained for this same period of time. These documents may be transferred to another 
responsible party, acceptable to the sponsor, who agrees to abide by the retention policies. The 
investigator is required to notify the sponsor (or an authorized representative) in writing prior to 
changing the location or status of any essential clinical study documents. The investigator must 
contact the sponsor prior to disposing of any study records. 
No records may be destroyed during the retention period without the written approval of the 
sponsor. No records may be transferred to another location or party without written notification 
to the sponsor. 
For studies conducted outside the US under an US investigational new drug (IND), the principal 
investigator must comply with US Food and Drug Administration IND regulations and with 
those of the relevant national and local health authorities. 
10.1.7.2. Quality Assurance Audit 
Study processes, study sites (including, but not limited to site visits, central laboratories, 
vendors), the study database, and study documentation may be subject to quality assurance audit 
during the course of the study by the sponsor or sponsor’s designee (CRO or other vendor) on 
behalf of sponsor. In addition, inspections may be conducted by regulatory bodies at their 
discretion. Such audits/inspections can occur at any time during or after completion of the study. 
10.1.7.3. Quality Control 
Quality control will be applied to each stage of study-related activities. 

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The following steps will be taken to ensure the accuracy, consistency, completeness, and 
reliability of the data: 
x Investigator meetings 
x Central laboratories for clinical laboratory parameters 
x Site initiation visit 
x Routine site monitoring 
x Ongoing site communication and training 
x Ongoing oversight by sponsor’s designated CRO monitors of safety parameters and 
adherence to selection criteria 
x Data management quality control checks 
x Continuous data acquisition and cleaning 
x Quality control check of the clinical study report (CTR) 
x To avoid interobserver variability, every effort should be made to ensure that the 
same individual who made the initial baseline determinations completes all efficacy 
and safety evaluations 
In addition, periodic audits can be performed as specified in Section 10.1.7.2. 
When audits or inspections are conducted, access must be authorized for all study-related 
documents including medical history and concomitant medication documentation to authorized 
sponsor’s representatives and regulatory authorities. 
10.1.8. 
Source Documents 
x Source documents provide evidence for the existence of the participant and 
substantiate the integrity of the data collected. Source documents are filed at the 
investigator’s site. 
x Data entered in the eCRF that are transcribed from source documents must be 
consistent with the source documents or the discrepancies must be explained. The 
investigator may need to request previous medical records or transfer records, 
depending on the study. Also, current medical records must be available. 
x Definition of what constitutes source data can be found in the data management plan. 
x The investigator must maintain accurate documentation (source data) that supports 
the information entered in the eCRF. 
x 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. 

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10.1.9. 
Study and Site Start and Closure 
First Act of Recruitment 
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 open and will be the study start date. 
Study/Site Termination 
The sponsor or designee reserves the right to close the study site or terminate the study at any 
time for any reason at the sole discretion of the sponsor. Study sites will be closed upon study 
completion. A study site is considered closed when all required documents and study supplies 
have been collected 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 the sponsor or investigator may include but are 
not limited to: 
For study termination: 
x Discontinuation of further study intervention development 
For site termination: 
x Failure of the investigator to comply with the protocol, the requirements of the 
IRB/IEC or local health authorities, the sponsor's procedures, or GCP guidelines 
x Inadequate or no recruitment (evaluated after a reasonable amount of time) of 
participants by the investigator 
x Total number of participants included earlier than expected 
If the study is prematurely terminated or suspended, the sponsor shall promptly inform the 
investigators, the IECs/IRBs, the regulatory authorities, and any CROs 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 
x All information regarding ARGX-113 supplied by the sponsor to the investigator and 
all data generated as a result of this study are considered confidential and remain the 
sole property of the sponsor. The results of the study will be reported in a clinical 
study report (CSR). The CSR will be written in accordance with the ICH E3 guideline 
and will be submitted in accordance with local regulations. 
x Any manuscript, abstract, other publication, presentation of the results, or information 
arising in connection with the study must be prepared with the sponsor and must be 
submitted to the sponsor for review and comment prior to submission for publication 

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or presentation. Study participant identifiers will not be used in the publication of 
results. 
x The sponsor will comply with the requirements for publication of study results. In 
accordance with standard editorial and ethical practice, the sponsor 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. 
x Authorship will be determined by mutual agreement and in line with International 
Committee of Medical Journal Editors authorship requirements. 
 
 

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10.2. 
Appendix 2: Clinical Laboratory Tests 
x The tests detailed in Table 3 will be performed by the central laboratory. 
x Protocol-specific requirements for inclusion or exclusion of participants are detailed 
in Section 5 of the protocol. 
x Additional tests may be performed at any time during the study as determined 
necessary by the investigator or required by local regulations. 
x Investigators must document their review of each laboratory safety report. 

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Table 3: 
Protocol-Required Laboratory Tests 
Laboratory 
Assessment 
Parameters 
Hematology 
Platelet count 
Red blood cell (RBC) 
count 
Hemoglobin 
Hematocrit 
RBC Indices: 
Mean corpuscular 
volume (MCV) 
%Reticulocytes 
White blood cell count 
with differential (% and 
absolute numbers) 
Neutrophils 
Lymphocytes 
Monocytes 
Eosinophils 
Basophils 
Clinical chemistry 
Blood urea nitrogen 
(BUN) 
Creatinine 
Glucose (fasting for 8 
hours) 
Calcium 
Glycosylated 
hemoglobin (HbA1c) 
Potassium 
Sodium 
Alkaline phosphatase 
(ALP)a 
Lactate dehydrogenase 
(LDH) 
C-reactive protein 
(CRP) 
Aspartate 
aminotransferase (AST) 
Alanine 
aminotransferase 
(ALT) 
Ȗ *OXWDP\O WUDQVIHUDVH
(GGT) 
Bilirubin, total and 
direct 
Albumin 
 
Cholesterol: 
Total 
LDL 
HDL 
Triglycerides 
International 
Normalized Ratio 
(INR) 
Activated Partial 
Thromboplastin Time 
(aPTT) 
Routine urinalysis 
Specific gravity 
pH, glucose, protein, blood, ketones, bilirubin, nitrite, leukocyte esterase by 
dipstick 
Highly sensitive urine human chorionic gonadotropin (hCG) pregnancy test 
(for female participants of childbearing potential) 
Microscopic evaluation 
Screening tests 
Virology: HIV 1&2 screen/p24 antigen, hepatitis B core, hepatitis B surface, 
and hepatitis be surface antigen; and hepatitis C antibody, SARS-CoV-2 
testing 
Highly sensitive serum hCG pregnancy test (for female participants of 
childbearing potential) 
Total immunoglobulin (IgG) levels 
AChR-Ab serology 
Follicle-stimulating hormone (FSH) (for female participants) 
a If alkaline phosphatase is elevated, consider fractioning. 
 
 

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10.3. 
Appendix 3: Total Blood Volume Collected From Each Participant 
The maximum amount of blood collected from each participant is 350 mL. Repeat or 
unscheduled samples may be taken for safety reasons or technical issues with samples. 
 
 

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10.5. 
Appendix 5: Contraceptive and Barrier Guidance 
10.5.1. 
Definitions 
Women of Childbearing Potential (WOCBP) 
Women in the following categories are considered WOCBP (fertile): 
1. Following menarche 
2. From the time of menarche until becoming postmenopausal unless permanently sterile 
(see below) 
x A postmenopausal state is defined as no menses for 12 months without an alternative 
medical cause. 
 A high FSH level in the postmenopausal range may be used to confirm a 
postmenopausal state in women not using hormonal contraception or hormonal 
replacement therapy (HRT). However, in the absence of 12 months of 
amenorrhea, confirmation with more than 1 FSH measurement is required.  
 Females on HRT and whose menopausal status is in doubt will be required to use 
1 of the nonestrogen 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. 
x Permanent sterilization methods (for the purpose of this study) include: 
 Documented hysterectomy 
 Documented 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, gonadal 
dysgenesis), 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. 
x 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. 
Woman of Nonchildbearing Potential (WONCP) 
Women in the following categories are considered WONCBP: 
1. Premenopausal female with permanent infertility due to 1 of the following: 
a. Documented hysterectomy 
b. Documented bilateral salpingectomy 
c. Documented bilateral oophorectomy 

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d. For individuals with permanent infertility due to an alternate medical cause other than 
the above (eg, Mullerian agenesis, androgen insensitivity, gonadal dysgenesis), 
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. 
1. Postmenopausal female 
a. A postmenopausal state is defined as no menses for 12 months without an alternative 
medical cause. 
 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 1 FSH measurement is required. 
 Females on HRT and whose menopausal status is in doubt must discontinue HRT 
to allow confirmation of postmenopausal status before study enrollment. 
Contraception Guidance 
CONTRACEPTIVESa ALLOWED DURING THE STUDY INCLUDE: 
Highly Effective Methodsb That Have Low User Dependency Failure rate of <1% per year when used 
consistently and correctly. 
Implantable progestogen-only hormone contraception associated with inhibition of ovulationc 
Intrauterine device (IUD) 
Intrauterine hormone-releasing system (IUS)c 
Bilateral tubal occlusion 
Azoospermic partner (vasectomized or due to a medical cause) 
Azoospermia is a highly effective contraceptive method provided that the partner is the sole sexual partner of the 
woman of childbearing potential and the absence of sperm has been confirmed. If not, an additional highly 
effective method of contraception should be used. Spermatogenesis cycle is approximately 90 days. 
Note: documentation of azoospermia for a male participant can come from the site personnel’s review of the 
participant’s medical records, medical examination, or medical history interview. 
Highly Effective Methodsb That Are User Dependent Failure rate of <1% per year when used consistently 
and correctly. 
Combined (estrogen- and progestogen-containing) hormonal contraception associated with inhibition of 
ovulationc 
oral 
intravaginal 
transdermal 
injectable 
Progestogen-only hormone contraception associated with inhibition of ovulationc 
oral 
injectable 
Sexual abstinence 

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CONTRACEPTIVESa ALLOWED DURING THE STUDY INCLUDE: 
Sexual abstinence is considered a highly effective method only if defined as refraining from heterosexual 
intercourse during the entire period of risk associated with the study intervention. The reliability of sexual 
abstinence needs to be evaluated in relation to the duration of the study and the preferred and usual lifestyle of 
the participant. 
Note: Periodic abstinence (calendar, symptothermal, post-ovulation methods), withdrawal (coitus interruptus), 
spermicides only, and lactational amenorrhea method are not acceptable methods of contraception. Male 
condom and female condom should not be used together due to risk of failure from friction 
a Contraceptive use by men or women should be consistent with local regulations regarding the use of contraceptive 
methods for those participating in clinical studies. 
b Failure rate of <1% per year when used consistently and correctly. Typical use failure rates differ from those when 
used consistently and correctly. 
c Male condoms must be used in addition to hormonal contraception. If locally required, in accordance with Clinical 
Trial Facilitation Group (CTFG) guidelines, acceptable contraceptive methods are limited to those which inhibit 
ovulation as the primary mode of action. 
 
 
 

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Data management and biostatistics 
Belgium 
 
 
 
 
Drug safety reporting 
United States 
 
 
 
 
 
 

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10.7. 
Appendix 7: Possible Adaptations to Study Protocol During the 
COVID-19 Pandemic 
During the coronavirus disease-2019 (COVID-19) pandemic, study sites and participants are 
facing unprecedented challenges. As a result of this crisis, the sponsor has considered changes 
that are necessary to protect the safety of the participants as well as the site staff, while still 
evaluating the noninferiority of efgartigimod PH20 SC as compared to efgartigimod IV. All sites 
and participants will follow local regulations and guidance regarding preventing the spread of 
COVID-19.  
The risk assessment, risk mitigation plan, and changes that may occur in response to an increase 
in COVID-19 cases is described in the following sections. 
10.7.1. 
COVID-19 Risk Assessment for Participant Safety 
Efgartigimod administration results in the reduction of all immunoglobulin G (IgG) subtypes, 
potentially hindering immune response and increasing the risk of all infections, including 
COVID-19. However, efgartigimod does not affect the levels of other immunoglobulin subtypes, 
such as IgA and IgM. Also, previous studies have shown that the maximum mean reduction of 
total IgG ranges from 60% to 70% and total IgG levels return to baseline within a few weeks of 
stopping efgartigimod treatment. Furthermore, other elements of the immune system are not 
impacted by efgartigimod treatment. The doses used in study ARGX-113-2001 have been 
administered to over 250 participants, including healthy volunteers and patients with generalized 
myasthenia gravis (gMG), immune thrombocytopenia (ITP), and pemphigus, with no infection-
related safety concerns identified. Therefore, despite the immunomodulating properties of 
efgartigimod, efgartigimod treatment is not expected to increase the risk of severe acute 
respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or developing COVID-19 in 
participants.  
10.7.2. 
COVID-19 Risk Mitigation 
All participants with clinically significant uncontrolled infections, malignancies, recent surgeries, 
and/or the presence of certain viral infections are excluded (see Section 5.2). The screening tests 
include a test for SARS-CoV-2 and a positive test excludes the participant. If at any point a 
participant tests positive for SARS-CoV-2 or reports COVID-19 symptoms, they will be 
discontinued from the study intervention. Furthermore, administration of efgartigimod to a 
participant will be interrupted if a clinically significant infection occurs. Infections are also 
considered an AESI subject to structured safety reporting and a detailed questionnaire, so a 
participant contracting COVID-19 would be recorded as an AESI. 
During the entire study the sites will implement all recommendations issued by the local 
government regarding minimizing the spread of COVID-19 (eg, social distancing, disinfection, 
hygiene, face mask requirements, and use of personal protection equipment [PPE] by site staff), 
including specific guidelines related to clinical research performed in clinical research centers.  

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10.7.3. 
Possible Changes in Study Design Due to the COVID-19 Pandemic 
10.7.3.1. Implementation of This Appendix 
Implementation for all sites includes social distancing where possible, PPE, and a telephone call 
before each study visit to check for COVID-19 symptoms. The adaptations to the visits and 
procedures described are acceptable alternatives to the main protocol procedures only under 
exceptional circumstances and after approval of the sponsor and/or CRO. Approval will be 
granted based on the possibility of participants going to the site and per local and/or site 
regulations. 
This appendix is intended for sites in areas where COVID-19 has affected the workload of study 
sites, severe movement restrictions have been imposed, or where there is a risk to participants or 
site staff when attending visits at the site. The duration of these changes will be agreed upon 
between the site and sponsor/CRO and can be extended based on the local epidemic status. 
10.7.3.2. Testing for COVID-19 
Additional testing for COVID-19 beyond what is mandated by relevant local authorities and 
listed in the SoA (Section 1.3) is not required during the study. However, it is recommended that 
participants who develop COVID-19 symptoms during the study be tested again. 
During the pandemic, the site staff should contact participants prior to each visit to inquire about 
COVID-19 symptoms (ie, fever, cough, sneezing, loss of taste/smell, difficulties breathing/chest 
tightness) and exposure to determine if it is safe for the participant to proceed with the visit as 
planned. If a participant tests positive for SARS-CoV-2 or has symptoms of COVID-19, he/she 
should not return to the site for visits until the investigator decides it is safe for the participant to 
return, based on local regulations and guidance from the site staff. 
10.7.3.3. Study Protocol Changes 
If the COVID-19 pandemic results in significant participant discontinuation, the sites may 
increase the recruitment of potential participants to replace the lost participants.  
10.7.3.4. Critical Parameters to Be Collected During the Study 
All assessments should be performed as indicated in the SoA (Section 1.3) if possible. In the 
event that some assessments cannot be performed due to the COVID-19 pandemic, the following 
critical parameters must be collected: all AE reporting, administration site reactions, SIB 
monitoring, IMP administration, who performed the administration, training and competency to 
perform self-administration, MG-ADL total score, and IgG levels from the first visit through 
day 29. 
10.7.3.5. Mandatory Site Visits and Home Visits 
All visits must be performed at the site if possible. If adaptations are required due to the COVID-
19 pandemic, the following visits must be performed at the site if possible. 
x screening visit 
x all TP visits 

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x first follow-up visit on day 29 
x EoS visit 
All other visits may be performed by phone if necessary, and all activities that do not require the 
participant to be on site will be performed. 
 
 

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10.8. 
Appendix 8: Interpretation of Hepatitis B Serologic Test Results 

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10.9. 
Appendix 9: Abbreviations and Definitions 
10.9.1. 
Definitions 
Enrolled: A participant’s, or their legally acceptable representative’s, agreement to participate in 
a clinical study following completion of the informed consent process and screening. Potential 
participants who are screened for the purpose of determining eligibility for the study, but do not 
participate in the study, are not considered enrolled, unless otherwise specified by the protocol.  
Japanese participant: A participant whose parents and 4 grandparents are Japanese, who has 
the Japanese nationality, was born in Japan, has not lived outside of Japan for a total of >10 
years, and currently lives in Japan. 
MG-ADL responder: A participant who shows a decrease of at least 2 points from baseline on 
the MG-ADL score for at least 4 consecutive weeks with the first of these decreases occurring at 
the latest 1 week after last administration of IMP. 
QMG responder: A participant who shows a decrease of at least 3 points from baseline on the 
QMG score for at least 4 consecutive weeks with the first of these decreases occurring at the 
latest 1 week after last administration of IMP. 
Randomized: An enrolled participant has been randomly assigned to a treatment arm. 
10.9.2. 
Abbreviations 
AChE 
acetylcholinesterase 
AChR 
acetylcholine receptor 
AChR-Ab 
acetylcholine receptor binding autoantibodies 
ADA 
anti-drug antibodies 
ADL 
activities of daily living 
AE 
adverse event 
AESI 
adverse event of special interest 
AIDS 
acquired immunodeficiency syndrome 
AUC 
area under the serum concentration-time curve 
AUEC 
area under the effect curve 
CIOMS 
Council for International Organizations of Medical Sciences 
CL 
total clearance 
CL/F 
apparent total clearance 
Cmax 
maximum concentration 
Ctrough 
concentration observed predose 
CONSORT 
Consolidated Standards of Reporting Trials 
COVID-19 
coronavirus disease-2019 
CRO 
contract research organization 

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CTCAE 
Common Terminology Criteria for Adverse Events 
CTFG 
Clinical Trial Facilitation Group 
DSMB 
Data Safety Monitoring Board 
ECG 
electrocardiogram 
eCRF 
electronic case report form 
ELISA 
enzyme-linked immunosorbent assay 
EoS 
end of study 
EQ-5D-5L 
EuroQoL 5-Dimensions 5-Level 
ER 
emergency room 
FcRn 
neonatal Fc receptor 
FSH 
follicle-stimulating hormone 
gMG 
generalized myasthenia gravis 
GCP 
Good Clinical Practice 
HBV 
hepatitis B virus 
hCG 
human chorionic gonadotropin 
HCV 
hepatitis C virus 
HIPAA 
Health Insurance Portability and Accountability Act 
HIV 
human immunodeficiency virus 
IB 
Investigator’s Brochure 
ICF 
informed consent form 
ICH 
International Council for Harmonisation 
ICU 
intensive care unit 
IRR 
injection and/or infusion-related reaction 
IEC 
Independent Ethics Committee  
Ig 
immunoglobulin 
IgG 
immunoglobulin G 
IMP 
investigational medicinal product 
IRB 
Institutional Review Board 
IRT 
Interactive Response Technology 
ITP 
immune thrombocytopenia 
ITT 
intention-to-treat 
IV 
intravenous 
IVIg 
intravenous immunoglobulin 

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MG-ADL 
Myasthenia Gravis Activities of Daily Living 
MGFA 
Myasthenia Gravis Foundation of America 
MG-QoL15r 
Myasthenia Gravis Quality of Life 15 item scale revised 
mITT 
modified intention-to-treat 
NAb 
neutralizing antibody 
NMJ 
neuromuscular junction 
NCI 
National Cancer Institute 
NSID 
nonsteroidal immunosuppressant 
PD 
pharmacodynamics 
PH20 
recombinant human hyaluronidase PH20 (rHuPH20) 
PHQ 
Patient Health Questionnaire 
PK 
pharmacokinetics 
PLEX 
plasma exchange 
PPE 
personal protective equipment 
PR 
atrioventricular node delay interval 
QMG 
Quantitative Myasthenia Gravis 
QoL 
quality of life 
QRS 
duration of ventricular depolarization 
QT 
total duration of ventricular depolarization 
QTcF 
rate-corrected QT intervals using Fridericia’s formula 
RR 
time between heart beats 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
SARS-CoV-2 
severe acute respiratory syndrome coronavirus 2 
SAS 
statistical analysis systems 
SC 
subcutaneous 
SCIg 
subcutaneous immunoglobulin 
SIB 
suicidal ideation and behavior 
SoA 
Schedule of Activities 
SOP 
Standard Operating Procedures 
SUSAR 
suspected unexpected serious adverse reaction 
TEAE 
treatment-emergent adverse event 
WOCBP 
women of childbearing potential 

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WONCBP 
women of nonchildbearing potential 

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
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