A Randomized, Double-Blind, Placebo-Controlled, Multicenter Phase 3 Trial to Evaluate the Efficacy, Safety and Tolerability of ARGX-113 in Patients With Myasthenia Gravis Having Generalized Muscle Weakness
Phase: PHASE3
Conditions: Generalized Myasthenia Gravis
Sponsor: argenx

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Clinical Trial Protocol 
 
 
Protocol Title: 
A 
Randomized, 
Double-Blind, 
Placebo-
Controlled, Multicenter Phase 3 Trial to Evaluate 
the Efficacy, Safety and Tolerability of ARGX-113 
in Patients with Myasthenia Gravis Having 
Generalized Muscle Weakness 
Protocol Number: 
ARGX-113-1704 (ADAPT) 
Date of Protocol: 
11 July 2019, Version 3.0, Final 
Product: 
ARGX-113 
IND No: 
 
EudraCT No: 
2018-002132-25 
Trial Phase: 
3 
Sponsor: 
argenx BVBA 
Industriepark Zwijnaarde 7 
B-9052 Zwijnaarde 
BELGIUM 
Phone: 
 
Medical Director: 
 
argenx BVBA 
Industriepark Zwijnaarde 7 
B 9052 Zwijnaarde 
BELGIUM 
Phone: 
 
 
PPD
PPD
PPD
PPD
CCI

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Contract Research Organization 
(CRO): 
Syneos Health™ group company 
including INC Research, LLC, together with INC 
Research UK Limited 
3201 Beechleaf Court 
Suite 600 
Raleigh, North Carolina 27604-1547 
US 
Phone: 
 
The following additional numbers are also available for urgent contact 
24 Hour Urgent Medical Helpline 
Number: 
 
For drug safety reporting, contact the below e-mail address 
Safety Mailbox/Fax: 
 
 
Confidentiality Statement 
This confidential information in this document is provided to you as an Investigator or consultant for review 
by you, your staff, and the applicable Institutional Review Board/Independent Ethics Committee. Your 
acceptance of this document constitutes agreement that you will not disclose the information contained herein 
to others without written authorization from the Sponsor. 
 
 
 
 
 
 
 
PPD
PPD
PPD

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SIGNATURE OF INVESTIGATOR 
PROTOCOL TITLE:  
A Randomized, Double-Blind, Placebo-Controlled, Multicenter 
Phase 3 Trial to Evaluate the Efficacy, Safety and Tolerability of 
ARGX-113 in Patients with Myasthenia Gravis Having 
Generalized Muscle Weakness 
PROTOCOL NO:  
ARGX-113-1704 (ADAPT) 
This protocol is a confidential communication of argenx BVBA. I confirm that I have read this 
protocol, I understand it, and I will work according to this protocol. I will also work consistently 
with the ethical principles that have their origin in the Declaration of Helsinki and that are 
consistent with good clinical practices and the applicable laws and regulations. Acceptance of 
this document constitutes my agreement that no unpublished information contained herein will 
be published or disclosed without prior written approval from argenx BVBA. 
 
Instructions to the Investigator: Please SIGN and DATE this signature page. PRINT your 
name, title, and the name of the site in which the trial will be conducted. Return the signed 
original copy to the local representative of your Sponsor’s designated CRO. 
 
I have read this protocol in its entirety and agree to conduct the trial accordingly: 
Signature of Investigator: 
 
Date: 
 
Printed Name: 
 
 
 
Investigator Title: 
 
 
 
Name/Address of Site: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Section 
Change 
Rationale 
- the patients has a total MG-ADL score of 
 5 points with more than 50% of the total 
score due to non-ocular symptoms, and 
- no clinically meaningful improvement 
(decrease in total MG-ADL score from 
TC1B < 2).” 
SYNOPSIS 
Trial Duration 
“The trial duration is 26 weeks preceded by 
a Screening period of maximum 2 weeks.” 
changed to 
‘The trial duration is 26 weeks preceded by a 
Screening period of approximately 2 weeks.’ 
In some cases, the 
screening period can be 
extended with up to 5 days 
SYNOPSIS 
Methodology: TREATMENT 
CYCLES AND BASELINES 
4.1 Summary of Trial Design 
“The trial will include a Screening period 
(pre-randomization) of maximum 2 weeks, 
…” 
changed to 
“The trial will include a Screening period 
(pre-randomization) of approximately 
2 weeks, …” 
 
Table 1 General Schedule of 
Assessments 
Footnote d: 
“Randomization (at the first Treatment 
Cycle Baseline [TC1B] only) should be 
performed as soon as possible after 
Screening with a maximum of 2 weeks, 
however only after confirmation of 
eligibility of the patient.” 
changed to 
“Randomization (at the first Treatment 
Cycle Baseline [TC1B] only) should be 
performed as soon as possible after 
Screening with approximately 2 weeks, 
however only after confirmation of 
eligibility of the patient.” 
 

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Section 
Change 
Rationale 
SYNOPSIS 
ROLL-OVER 
“Patients who discontinue early from 
randomized treatment for rescue or 
pregnancy reasons or for a (serious) adverse 
event ([S]AE) that might jeopardize the 
safety of the patient will also not be offered 
the option to roll over to the follow-on trial.” 
changed to 
“Patients who discontinue early from 
randomized treatment for rescue or 
pregnancy reasons or for a serious adverse 
event (SAE) that is likely to result in a life-
threatening situation or pose a serious safety 
risk will also not be offered the option to roll 
over to the follow-on trial.” 
Change of wording to 
clarify that there needs to 
be a serious safety risk in 
order to have the patient 
discontinued. 
4.4.2. Early Discontinuation 
from Randomized Treatment 
“x Patient develops an (S)AE that might 
jeopardize the safety of the patient.” 
changed to 
“x Patient develops an SAE that is likely to 
result in a life-threatening situation or pose a 
serious safety risk.” 
 
4.1. Summary of Trial Design 
4.5. Roll-Over to Follow-on 
Trial 
“Patients who discontinue early from 
randomized treatment for rescue or 
pregnancy reasons or for an (S)AE that 
might jeopardize the safety of the patient 
will also not be offered the option to roll 
over to the follow-on trial.” 
changed to 
“Patients who discontinue early from 
randomized treatment for rescue or 
pregnancy reasons or for an SAE that is 
likely to result in a life-threatening situation 
or pose a serious safety risk will also not be 
offered the option to roll over to the 
follow-on trial.” 
 

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Section 
Change 
Rationale 
5.2. Screening 
“x Sampling to determine the 
AChR/MuSK-Ab serotype (seronegative or 
seropositive) of the patient. In case the 
AChR-Ab result is not available in time 
(within the 2 weeks screening window), the 
value found in the Medical History of the 
patient will be used for randomization.” 
changed to 
“x Sampling to determine the 
AChR/MuSK-Ab serotype (seronegative or 
seropositive) of the patient. In case the 
AChR-Ab result is not available in time (i.e. 
within the 2 weeks screening window), the 
screening window can be enlarged on an ad-
hoc base with maximum 5 calendar days.” 
The AChR-Ab medical 
history value will not be 
used anymore. Enlarging 
the screening window 
should allow sufficient 
time for the result to be 
provided by the central 
laboratory. This to 
maximize our consistency 
in our testing methods and 
results throughout the trial. 
5.3. Randomization 
“Randomization should be performed as 
soon as possible after Screening with a 
maximum of 2 weeks, however …” 
changed to 
“Randomization should be performed as 
soon as possible after Screening in 
approximately 2 weeks with a possible ad-
hoc extension of maximum 5 calendar days 
in case of non-availability of AchR AB 
status, however …” 
 
6.8. Prior Treatments and 
Concomitant Medications 
Addition of the following sentence: 
“Vaccines (except for live/live-attenuated 
vaccines) will be allowed during the trial 
when administered at least 48 hours pre-
infusion or 48 hours post-infusion of IMP.” 
For patient safety, 
allowing for vaccines to be 
administered according to 
common clinical practice. 
Also to reduce the risk of 
confusing vaccination-
related adverse adverse 
events (such as fever) with 
IMP-infusion related 
adverse events 
6.8.1. Prohibited Medications 
during the Trial 
“Vaccines” 
changed to 
“Live/live-attenuated vaccines” 
 

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Section 
Change 
Rationale 
7.2.1.1. Adverse Events of 
Special Interest 
New section added: 
“An AESI (serious or non-serious, related or 
not related) is an event of scientific and 
medical concern specific to the sponsor’s 
product or program. 
ARGX-113 treatment induces reductions in 
IgG levels, and there is a potential risk for 
infections associated with the low IgG 
levels. As such, any infection will be 
considered AESI in this trial. Further 
characterizing information will be collected 
in the eCRF, such as: location of infection, 
relationship to underlying condition, medical 
history and concomitant medication, 
reoccurrence of previous infection, previous 
rescue therapy, any confirmatory procedure, 
culture or urgent medical intervention.” 
Since the mechanism of 
action of ARGX-113 
induces reductions in IgG 
levels there is a potential 
of infection risk. 
Therefore, infections will 
be captured as AESIs, in 
order to collect the data in 
a systematic way. 
Appendix 6 
Laboratory 
Evaluations 
Footer 
“2 In case the AChR-Ab result is not 
available in time (within the 2 weeks 
screening window), the value found in the 
Medical History of the patient will be used 
for randomization.” 
changed to 
“2 In case the AChR-Ab result is not 
available in time (i.e. within the 2 weeks 
screening window), the screening window 
can be enlarged on an ad-hoc base with 
maximum 5 calendar days. 
The AChR-Ab medical 
history value will not be 
used anymore. Enlarging 
the screening window 
should allow sufficient 
time for the result to be 
provided by the central 
laboratory. This to 
maximize our consistency 
in our testing methods and 
results throughout the trial. 
 

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Changes from Protocol Version 1.0 compared to Protocol Version 2.0 are summarized below. 
Of note: updates of headers/footers and tables of contents as well as editorial changes regarding 
layout, font, and format are not captured in this summary. 
Section 
Change 
Rationale 
SYNOPSIS 
SAMPLE SIZE AND 
STRATIFICATION 
4.1. Summary of Trial Design 
SAMPLE SIZE AND 
STRATIFICATION 
6.5. Method of Assigning 
Patients to Treatment Group 
“ethnicity” was removed and “patients” 
was added after “non-Japanese”. The 
definition of “Japanese patient” was added. 
“Japanese” is a race and not 
an ethnicity. Definition of 
“Japanese patient” added for 
completeness. 
SYNOPSIS 
STANDARD of CARE (SoC) 
4.1. Summary of Trial Design 
STANDARD of CARE (SoC) 
Addition of the following sentences: 
“In case these medications are taken for 
another indication than MG, same 
conditions apply.” 
“Following this requirement, this possible 
temporary change in dosing regimen of 
AChE inhibitors will not be considered as 
a change in SoC.” 
Sentences added for extra 
clarification. 
SYNOPSIS 
RE-TREATMENT 
4.1. Summary of Trial Design 
RE-TREATMENT 
“Each patient may start …” 
changed to 
“Each patient will start …” 
Language changed to clarify 
that according to the study 
design, in this situation, the 
patient will get re-treatment 
(it is not a free choice). 
The first bullet has been changed from 
“The patient has completed the previous 
Treatment Cycle (including the 
assessments of the corresponding Visit 9) 
AND” 
to 
“The patient has completed the previous 
Treatment Cycle (i.e. an 8-week time 
period after first dosing date) AND” 
Wording adjusted to cover 
the situation where Visit 9 
would be missing. 
SYNOPSIS 
RE-TREATMENT 
4.1. Summary of Trial Design 
RE-TREATMENT 
Addition of the following sentence: 
“Re-treatment with IMP may be 
reconsidered at next time where conditions 
for re-treatment are met, providing that at 
least 4 weeks have past after other MG 
treatment (see Appendix 9)” 
Wording and appendix 
added for clarification. 

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Section 
Change 
Rationale 
SYNOPSIS 
RESCUE THERAPY 
4.1. Summary of Trial Design 
RESCUE THERAPY 
- 
“If necessary, patients may receive 
rescue therapy, which will be limited to 
Plasma Exchange (PLEX), …” 
changed to 
“Rescue therapy will be limited to 
Plasma Exchange (PLEX), …” 
Wording adjusted to 
enhance clarification. 
 
- 
“In situations where rescue therapy is 
given, patients will be discontinued 
early from randomized treatment.” 
changed to 
“In situations where the treatments as 
listed above are given under the 
protocol defined rescue criteria, 
patients will be discontinued early from 
randomized treatment.” 
 
SYNOPSIS 
Inclusion Criteria 
4.3.1 Inclusion Criteria 
Criterion no. 5: 
“Note: AChE inhibitors must be held for at 
least …” 
changed to 
“Note: AChE inhibitors must be halted for 
at least …” 
Administrative change 
SYNOPSIS 
Exclusion Criteria 
4.3.2 Exclusion Criteria 
Criterion no. 7: 
“Patients with known autoimmune disease 
other than MG (i.e., autoimmune 
thyroiditis) that …” 
changed to 
“Patients with known autoimmune disease 
other than MG (for example autoimmune 
thyroiditis, rheumatoid arthritis, …) that 
…” 
Typo/wrong use of “i.e.” 
was corrected, additional 
example provided. 
SYNOPSIS 
Statistical Methods and Plan 
8.4.1. Primary Endpoint 
Analyses 
“ethnicity” was replaced twice with 
“Japanese/non-Japanese patient, AChR-
Ab”. 
Administrative changes 
(added for completeness). 

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Section 
Change 
Rationale 
Table 1 General Schedule of 
Assessments 
Trial Day (Visit Window). 
Visit window corrected. 
Changes to the table footer: 
- 
“k Samples for clinical laboratory tests 
(hematology and clinical chemistry)” 
changed to 
“k Samples for clinical laboratory tests 
(hematology, clinical chemistry and 
FSH, if applicable)” 
Administrative changes. 
 
- 
“q Samples for anti-drug antibodies 
(ADAs) will be collected pre-dose on 
dosing days. As from … of the 
corresponding Treatment Cycle.” 
changed to 
“q Samples for anti-drug antibodies 
(ADAs) will be collected pre-dose if 
sampling is to be performed on dosing 
days. During the first Treatment Cycle, 
samples for ADA will be taken at 
Visits 1, 4, 6 and 9. As from … of the 
corresponding Treatment Cycle and 
EoS/ED.” 
 
 
- 
“r Pharmacokinetic (PK) samples will 
be collected at Visits 1, 2, 3, 4, 5, and 
6.” 
changed to 
“r Pharmacokinetic (PK) samples will 
be collected at Visits 1, 2, 3, 4, 5, and 6 
and EoS/ED.” 
 
 
- 
“u During the UNS visit, additional 
assessments can be performed at …” 
changed to 
“u During the UNS visit, additional 
assessments as indicated in the SoA 
can be performed at …” 
 
LIST OF APPENDICES 
Appendix 8 and Appendix 9 were added 
For completeness. 
LIST OF ABBREVIATIONS 
Cmax 
“Maximum observed plasma 
concentration” 
changed to 
“Maximum observed serum concentration” 
Correction 

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Section 
Change 
Rationale 
4.6. Protocol Deviations 
“prior review and documented approval 
from the Institutional Review 
Board/Independent Ethics Committee 
(IRB/IEC) of an amendment, except …” 
changed to 
“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 
…” 
Administrative change 
4.9. End of Trial Definition 
The following was added: 
“4.9. End of Trial Definition 
End of trial is defined as last patient last 
visit.” 
Added for completeness 
(was missing in the previous 
version). 
5.2. Screening 
12th bullet: 
“Sampling to determine the AChR/MuSK-
Ab serotype (seronegative or seropositive) 
of the patient.” 
changed to 
“Sampling to determine the AChR/MuSK-
Ab serotype (seronegative or seropositive) 
of the patient. In case the AChR-Ab result 
is not available in time (within the 2 weeks 
screening window), the value found in the 
Medical History of the patient will be used 
for randomization. ” 
To avoid missing 
information on stratification 
factor (at time of 
randomization) in case of 
late lab results 
5.3. Randomization 
Last paragraph: 
“…3 stratification factors: ethnicity 
(Japanese vs. non-Japanese), AChR-Ab 
status …” 
changed to 
“…3 stratification factors: Japanese vs. 
non-Japanese patients, AChR-Ab status 
…” 
“Japanese” is a race and not 
an ethnicity. 
 
“… recorded as a screen failure in the 
IRT.” 
changed to 
“… recorded as a screen failure in the 
EDC system.” 
Correction. 

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Section 
Change 
Rationale 
6.8.1. Prohibited Medications 
- 
“The following medications or 
treatments will not be permitted as 
from signing the ICF during the trial:” 
changed to 
“The following medications or 
treatments will lead to discontinuation 
from randomized treatment:” 
Wording added for 
clarification. 
 
- 
“Rescue therapy” 
changed to 
“Rescue therapy when used in patients 
who meet the criteria to be rescued” 
 
 
- 
Additional bullet: 
“Use of PLEX or immunoadsorption 
more than once during study period” 
 
6.8.2. Rescue Therapy 
- 
First sentence (“If necessary, patients 
may receive rescue therapy if their 
gMG deteriorates.”) deleted. 
To be in line with the 
corresponding section in the 
Synopsis, Section 4.1, and 
Section 6.8.1. 
 
- 
The following sentence added at the 
end of the section: 
“In situations where the treatments as 
listed above are given under the 
protocol defined rescue criteria, 
patients will be discontinued early from 
randomized treatment.” 
 
- 
Last sentence (“In situations where 
rescue therapy is given, patients will be 
discontinued early from randomized 
treatment.”) deleted. 
 
6.11. Handling Missed Doses in 
the Investigational Medicinal 
Product 
“In case a dose needs to be delayed for 
more than 5 days, …” 
changed to 
“In case a dose needs to be delayed for 
more than 3days, …” 
Correction 
7.1.2. Quantitative Myasthenia 
Gravis 
End of section, one but last sentence: 
“…dynamometer, and is based on 
physician’s examination.” 
changed to 
“…dynamometer, and is based on the 
trained rater’s examination.” 
Updated because the rater 
needs to be a trained person, 
but not necessarily a 
physician. 

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Section 
Change 
Rationale 
7.1.3. Myasthenia Gravis 
Composite 
First sentence: 
“The MGC has 10 items (Appendix 3) 
combining physician examination and 
patient reported outcomes.” 
changed to 
“The MGC has 10 items (Appendix 3) 
combining a trained rater’s examination 
and patient reported outcomes.” 
Updated because the rater 
needs to be a trained person, 
but not necessarily a 
physician. 
7.2.1.3. Follow-up of Adverse 
Events and Serious Adverse 
Events 
- 
Second paragraph: 
“Every effort should be made to follow 
all AEs …” 
changed to 
“Every effort should be made to follow 
all (S)AEs …” 
Table deleted and text 
updated to clarify that all 
SAEs are to be followed-up 
until resolution. 
 
- 
Table 3 deleted 
 
7.2.1.4.1 Pregnancies in Female 
Patients 
The following sentence has been added: 
“If required by local regulations, the 
female participant will be requested to sign 
a separate pregnancy ICF.” 
Added for completeness. 
7.3. Pharmacokinetics 
“(PK)” was added to the section title. 
Added for completeness. 
7.4. Pharmacodynamics 
“(PD)” was added to the section title. 
Added for completeness. 
7.5. Anti-Drug Antibodies 
“(ADA)” was added to the section title. 
Added for completeness. 
 
Second sentence: 
“At Baseline (SEB and TCnB), 
confirmatory and titer analysis will be 
performed using a validated ADA assay.” 
changed to 
“At Baseline (SEB and TCnB), Screening, 
confirmatory and titer analysis will be 
performed using a validated ADA assay.” 
Added for completeness 
(3-step analysis). 
8.4.3. Tertiairy Endpoint 
Analyses 
- 
Last paragraph: 
“…using individual concentration data 
in plasma and actual sampling times:” 
changed to 
“…using individual concentration data 
in serum and actual sampling times:” 
Correction (ARGX-113 is to 
be measured in serum and 
not in plasma). 
 
- 
“Cmax: maximum observed plasma 
concentration” 
changed to 
“Cmax: maximum observed serum 
concentration” 
 

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Section 
Change 
Rationale 
8.4.3. Tertiairy Endpoint 
Analyses 
- 
“Ctrough: plasma concentration observed 
pre-dose at Visits 2, 3 and 4” 
changed to 
“Ctrough: serum concentration observed 
pre-dose at Visits 2, 3 and 4” 
 
11.1 Data Handling and Record 
Keeping 
- 
First sentence: 
“It is the Investigator’s responsibility to 
maintain essential trial documents 
(including regulatory documents, 
eCRFs, signed patient ICFs, source 
documents, …” 
changed to 
“It is the Investigator’s responsibility to 
maintain essential trial documents 
(records and documents pertaining to 
the conduct of this trial and the 
distribution of IMP, including 
regulatory documents, eCRFs, signed 
patient ICFs, laboratory test results, 
IMP inventory records, source 
documents, …” 
Updated to avoid duplication 
of information. 
 
- 
Third paragraph ("The United States 
(US) Food and Drug Administration 
(FDA) regulations … the Principal 
Investigator of these events.”) deleted. 
 
 
- 
The following sentence was added to 
the end of the first paragraph: 
“The Sponsor will notify the Principal 
Investigator of these events.” 
 
Appendix 6 
Laboratory 
Evaluations 
Clinical Chemistry 
- 
“*” changed to “1” 
Updated for extra 
clarification. 
AChR-/MuSK-antibody 
serotype 
- 
“2” was added to the end of the 
description. 
 
Footer 
- 
“*” changed to “1” 
 
 
- 
“2 In case the AChR-Ab result is not 
available in time (within the 2 weeks 
screening window), the value found in 
the Medical History of the patient will 
be used for randomization.” was added. 
 
CCI

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Section 
Change 
Rationale 
Appendix 8 
Decision Tree for 
Re-treatment – Part A 
Figure and footnote added. 
Added for completeness 
Appendix 9 
Decision Tree for 
Re-treatment – Part B 
Figure and footnote added. 
Added for completeness 
 

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SYNOPSIS 
Name of Sponsor: 
argenx BVBA 
Name of Investigational 
Medicinal Product (IMP): 
ARGX-113 (efgartigimod) 
Name of Active Ingredient: 
A human anti-neonatal Fc- receptor (FcRn) immunoglobulin G1 (IgG1) 
Fc fragment 
Indication: 
Treatment of patients with generalized myasthenia gravis (gMG) 
Title of Trial: 
A randomized, double-blind, placebo-controlled, multicenter Phase 3 trial to evaluate 
the efficacy, safety and tolerability of ARGX-113 in patients with myasthenia gravis 
having generalized muscle weakness 
Protocol No: 
ARGX-113-1704 (ADAPT) 
Trial Sites: 
This trial is a global, multicenter trial 
Trial Duration: The trial duration is 26 weeks preceded by a Screening 
period of maximum approximately 2 weeks. 
Phase: 3 
Objectives: 
Primary Objective: 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of “Myasthenia Gravis Activities of 
Daily Living (MG-ADL) responders” after the first Treatment Cycle in the acetylcholine receptor 
(AChR)-antibody (Ab) seropositive population. 
 
Secondary Objectives: 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of “Quantitative Myasthenia Gravis 
(QMG) responders” after the first Treatment Cycle in the AChR-Ab seropositive population. 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of “MG-ADL responders” after the 
first Treatment Cycle in the overall population (AChR-Ab seropositive and AChR-Ab seronegative 
patients). 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of time that patients show a 
“clinically meaningful improvement” in total MG-ADL score during the trial (up to and including Day 
126) in the AChR-Ab seropositive population. 
x 
To evaluate the efficacy of ARGX-113 as assessed by the time to qualification for first re-treatment in the 
AChR-Ab seropositive population. 
x 
To evaluate the onset of efficacy of ARGX-113 as assessed by the percentage of “early MG-ADL 
responders” after the first Treatment Cycle in the AChR-Ab seropositive population. 
x 
To evaluate the safety and tolerability of ARGX-113 in the overall population and in subgroups. 
 
Tertiary Objective: 
x 
To assess additional efficacy and safety parameters, pharmacodynamics (PD) and immunogenicity. 
Definitions 
An “MG-ADL responder” is defined as a patient who shows a decrease of at least 2 points on the total 
MG-ADL score (compared to the corresponding Treatment Cycle Baseline [TCB]) for at least 4 consecutive 
weeks with the first of these decreases occurring at the latest 1 week after last infusion of IMP of the 
corresponding cycle. The scoring of MG-ADL should be performed by a trained and certified evaluator. 
 

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A “QMG responder” is defined as a patient who shows a decrease of at least 3 points on the total QMG 
score (compared to the corresponding TCB) for at least 4 consecutive weeks with the first of these decreases 
occurring at the latest 1 week after last infusion of IMP of the corresponding cycle. The scoring of QMG 
should be performed by a trained evaluator. 
 
An “early MG-ADL responder” is defined as a patient who shows a decrease of at least 2 points on the total 
MG-ADL score (compared to the corresponding TCB) for at least 4 consecutive weeks with the first of these 
decreases occurring after 1 or maximum 2 infusions of IMP of the corresponding cycle. The scoring of 
MG-ADL should be performed by a trained and certified evaluator. 
 
An MG-ADL “clinically meaningful improvement” is defined as a decrease of at least 2 points on the total 
MG-ADL score compared to either Study Entry Baseline (SEB) or corresponding TCB. 
 
A QMG “clinically meaningful improvement” is defined as a decrease of at least 3 points on the total QMG 
score compared to either SEB or corresponding TCB. 
 
Methodology:  
 
DESCRIPTION 
This is a randomized, double-blind, placebo-controlled, multicenter Phase 3 trial to evaluate the efficacy, 
safety, tolerability, quality of life and impact on normal daily activities of ARGX-113 in patients with gMG-. 
The trial duration is 26 weeks, which consists of: 
x 
a treatment part where all randomized patients will be treated with IMP, and 
x 
a re-treatment part where patients may be re-treated with IMP on an “as needed basis” during the 
timeframe of the trial. 
The trial will include patients on a stable standard of care (SoC) with a total MG-ADL score of  5 points at 
Screening and Baseline and with more than 50% of the total score attributed to non-ocular symptoms. 
The time between Treatment Cycles is based on the duration of the treatment effect and may vary from patient 
to patient and within each patient from cycle to cycle (patient-tailored approach).  
 
SAMPLE SIZE AND STRATIFICATION 
Approximately 150 patients will be stratified according to 3 stratification factors:  
Japanese vs. non-Japanese patients, AChR-Ab status (seropositive vs. seronegative) and SoC (patients on non-
steroidal immunosuppressive drugs [NSIDs] vs. patients not on NSIDs) and randomized (1:1) within each 
stratum to be treated with either placebo or ARGX-113, on top of their current SoC. A maximum of 20% of 
AChR-Ab seronegative patients will be allowed in the trial. 
Definition: Japanese patient is defined as a patient whose parents and four 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. 
 
TREATMENT CYCLES AND BASELINES 
The trial will include a Screening period (pre-randomization) of approximately 2 weeks, a first Treatment 
Cycle and a variable number of subsequent Treatment Cycles administered on an “as needed basis”. Each 
Treatment Cycle consists of 9 weekly visits over a period of 8 weeks, consisting of a Treatment period of 3 

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weeks (4 weekly infusions) and a Follow-up (FU) period of 5 weeks (see Figure 1). The SEB and the (first) 
Treatment  
Cycle Baseline (TC[1]B) will both be set at randomization (Visit 1), whilst the Baseline of each subsequent 
Treatment Cycle (TCnB) will be set at Visit 1 of each corresponding Treatment Cycle. 
 
SCREENING AND TREATMENT 
During the Screening period, patient’s eligibility for trial participation will be evaluated. 
During the Treatment Cycles, eligible patients will receive, on top of their current SoC and in a blinded 
fashion, 4 weekly infusions of either 10 mg/kg ARGX-113 or placebo at Visit 1, Visit 2, Visit 3 and Visit 4 of 
the corresponding Treatment Cycle.  
 
STANDARD of CARE (SoC) 
Patients should be on a stable dose and frequency of SoC prior to Screening (inclusion criterion n°5). 
Permitted SoC for MG treatment under this protocol include NSIDs (e.g., azathioprine, methotrexate, 
cyclosporine, tacrolimus, mycophenolate mofetil, and cyclophosphamide), steroids, as well as 
acetylcholinesterase (AChE) inhibitors. In case these medications are taken for another indication than MG, 
same conditions apply. 
For the entire duration of the trial, a change in the type or dose/regimen of SoC (replacing, adding or 
removing SoC, or adjustment of the SoC dose and/or frequency) is not allowed. Administration of AChE 
inhibitors must be halted for at least 12 hours prior to performing the QMG assessment. Following this 
requirement, this possible temporary change in dosing regimen of AChE inhibitors will not be considered as a 
change in SoC. 
 
TIME BETWEEN TREATMENT CYCLES 
At the end of each Treatment Cycle, patients will enter a variable Inter Treatment Cycle (ITC) period during 
which they will be treated with their SoC only. The length of the ITC period may vary from patient to patient 
and for each patient from cycle to cycle (patient-tailored approach). The visit frequency in the ITC period is 
every two weeks, starting 14 days (± 2 days) from the last visit of the previous Treatment Cycle. 
 
RE-TREATMENT 
Each patient will start a new Treatment Cycle with ARGX-113 or placebo when all the following criteria 
apply: 
x 
The patient has completed the previous Treatment Cycle (i.e. an 8-week time period after first dosing 
date) AND 
x 
The patient has a total MG-ADL score of  5 points with more than 50% of the total score due to non-
ocular symptoms AND 
x 
The Treatment Cycle can start at the latest on Day 127 and can be completed within the timeframe of the 
trial (26 weeks) AND 
x 
In case the patient was an MG-ADL responder at the previous Treatment Cycle: if he/she has lost the 
response.  
Loss of response is defined as a patient who no longer shows a decrease of at least 2 points on the total 
MG-ADL score compared to the corresponding TCB. 
However, patients may not receive re-treatment with ARGX-113 or placebo if, at the time of re-treatment, 
patients have clinical evidence of bacterial, viral or fungal disease, or any other significant disease which 
could confound the results of the trial or put patients at undue risk. Patients who are in need of an additional 
treatment but who are not eligible to receive re-treatment for reasons listed here will remain in the trial to 
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Re-treatment with IMP may be re-considered at next time where conditions for re-treatment are met, 
providing that at least 4 weeks have past after other MG treatment (see Appendix 9). 
ROLL-OVER 
At the End of Study (EoS) visit, patients will be offered the option to roll over into a long-term, single-arm, 
open-label follow-on trial (ARGX-113-1705) where they will be treated with ARGX-113 (10 mg/kg of body 
weight) on an “as needed basis”.  
Patients who need re-treatment but cannot complete a Treatment Cycle within the time frame of the 
ARGX-113-1704 trial (i.e., require re-treatment after Day 127), may roll over immediately to the follow-on 
trial to receive treatment with ARGX-113. 
Patients who discontinue early from trial ARGX-113-1704, will not be offered the option to roll over in the 
follow-on trial.  
Patients who discontinue early from randomized treatment for rescue or pregnancy reasons or for a serious 
adverse event (SAE) that is likely to result in a life-threatening situation or pose a serious safety risk will also 
not be offered the option to roll over to the follow-on trial. Patients who discontinue early from randomized 
treatment for other reasons and patients who have a temporary interruption from randomized treatment may 
be offered the option to roll over to the follow-on trial. 
 
RESCUE THERAPY 
Rescue therapy will be limited to Plasma Exchange (PLEX), intravenous immunoglobulin (IVIg), 
immunoadsorption or use of a new type of corticosteroid or an increased dose of the current corticosteroids 
used as stand-alone therapy or in combination. Rescue therapy is permitted for patients experiencing protocol-
defined MG clinical deterioration AND if, in addition, the treating physician believes that the patient’s health 
is in jeopardy if rescue therapy is not given. An MG clinical deterioration permitting rescue therapy to be 
given is defined as a patient experiencing at least one of the following: (1) new or worsening of respiratory / 
bulbar symptoms or (2) at least 2-point increase of individual non-ocular MG-ADL items. Whenever possible, 
prior to giving rescue therapy to a patient, the Medical Director at the Sponsor and the Medical Monitor at the 
Sponsor’s designated Contract Research Organization (CRO) should be informed. 
In situations where the treatments as listed above are given under the protocol defined rescue criteria, patients 
will be discontinued early from randomized treatment.  
 
EARLY DISCONTINUATION FROM THE TRIAL 
Any patient prematurely discontinuing the trial should perform the EoS/ED assessments. 
 
EARLY DISCONTINUATION FROM RANDOMIZED TREATMENT 
Patients who discontinue early from randomized treatment within a Treatment Cycle will have to complete 
the End of Treatment (EoT) assessments and complete the remaining visits in the current Treatment Cycle, 
according to the general schedule of assessments (SoA) (Table 1). These patients will not receive any further 
IMP administration during the trial and will continue to be followed for safety and disease severity (limited to 
MG-ADL and QMG) as per the SoA for Patients that Discontinued Early from Randomized Treatment (Table 
2). 
Patients who discontinue early from randomized treatment in the ITC period will have to complete the EoT 
assessments and then continue into the Safety and Disease Severity Follow-up period as per Table 2. 
 
TEMPORARY INTERRUPTION FROM RANDOMIZED TREATMENT 
A patient that does not need to be discontinued early from randomized treatment might still have a temporary 
interruption from randomized treatment which is defined as a discontinuation only from the current Treatment 

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Cycle. Therefore, these patients might still be eligible for further additional treatments with IMP within this 
trial. 
Planned Number of Patients: 
Approximately 150 patients will be randomized. 
Criteria for Inclusion and 
Exclusion: 
Inclusion Criteria: 
1. Patients with the ability to understand the requirements of the trial, 
provide written informed consent, and comply with the trial protocol 
procedures. 
2. Male or female patients aged  18 years. 
3. Diagnosis of MG with generalized muscle weakness meeting the 
clinical criteria for diagnosis of MG as defined by the Myasthenia 
Gravis Foundation of America (MGFA) class II, III, IVa and IVb. 
The confirmation of the diagnosis should be documented and 
supported by at least 1 of the following 3 tests: 
o 
History of abnormal neuromuscular transmission demonstrated 
by 
single-fiber 
electromyography 
or 
repetitive 
nerve 
stimulation, or 
o 
History of positive edrophonium chloride test, or 
o 
Patient has demonstrated improvement in MG signs on oral 
AChE inhibitors as assessed by the treating physician. 
4. A total MG-ADL score of  5 points at Screening and Baseline 
(SEB) with more than 50% of the total score due to non-ocular 
symptoms. 
5. Patients are required to be on a stable dose of their MG treatment 
(SoC) prior to Screening. The SoC is limited to AChE inhibitors, 
steroids and NSIDs. For patients receiving NSIDs, steroids, and/or 
AChE inhibitors as concomitant medications the following stability 
dose conditions will apply: 
o 
Non-steroidal immunosuppressive drugs (e.g., azathioprine, 
methotrexate, cyclosporine, tacrolimus, mycophenolate mofetil, 
and cyclophosphamide): treatment initiated at least 6 months 
prior to Screening and no dose changes in the last 3 months 
before Screening. 
o 
Steroids: treatment initiated at least 3 months prior to Screening 
and no dose changes in the last month before Screening. 
o 
Acetylcholinesterase inhibitors: stable dose with no dose 
escalation in the past 2 weeks before Screening. 
Note: AChE inhibitors must be halted for at least 12 hours 
consistent with the revised manual for the QMG test as 
recommended by the MGFA, before the QMG assessment. 
 
Exclusion Criteria: 
1. Pregnant and lactating women, and those intending to become 
pregnant during the trial or within 90 days after the last dosing. 
Women of childbearing potential (see DEFINITION OF TERMS) 
should have a negative serum pregnancy test at Screening and a 
negative urine pregnancy test at Baseline (SEB) prior to 
administration of IMP.  

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Note: Women of childbearing potential should use a highly effective 
method of contraception (i.e., pregnancy rate of less than 1% per 
year) during the trial and for 90 days after the last administration of 
the IMP. They must be on a stable regimen, for at least 1 month, of 
combined estrogen and progestogen hormonal contraception with 
inhibition of ovulation, progestogen-only hormonal contraception 
associated with inhibition of ovulation, intrauterine device (IUD), 
intrauterine hormone-releasing system, bilateral tubal occlusion, 
vasectomized partner, or agree upon continuous abstinence from 
heterosexual sexual contact. 
2. Male patients who are sexually active and do not intend to use 
effective methods of contraception (as mentioned above) during the 
trial or within 90 days after the last dosing or male patients who plan 
to donate sperm during the trial or within 90 days after the last 
dosing. 
Note: Sterilized male patients who have had vasectomy with 
documented aspermia post-procedure, or male patients who have a 
partner of non-childbearing potential, can be included. 
3. MGFA Class I and V patients. 
4. Patients with worsening muscle weakness secondary to concurrent 
infections or medications (aminoglycosides, fluoroquinolones, beta-
blockers, etc.). 
5. Patients with known seropositivity or who test positive for an active 
viral infection at Screening with: 
o 
Hepatitis B Virus (HBV) (except patients who are seropositive 
because of HBV vaccination) 
o 
Hepatitis C Virus (HCV) 
o 
Human Immunodeficiency Virus (HIV) 
6. Patients with any known severe bacterial, viral or fungal infection or 
any major episode of infection that required hospitalization or 
injectable antimicrobial therapy in the last 8 weeks prior to 
Screening.  
7. Patients with known autoimmune disease other than MG (for 
example autoimmune thyroiditis, rheumatoid arthritis, …) that would 
interfere with an accurate assessment of clinical symptoms. 
8. Patients with total IgG level < 6 g/L at Screening. 
9. Patients with documentation of a lack of clinical response to PLEX. 
10. Use of investigational drug within 3 months or 5 half-lives of the 
drug (whichever is longer) prior to Screening. 
11. Immunoglobulins given by IV (IVIg), subcutaneous or intramuscular 
route, or PLEX, each within 1 month prior to Screening. 
12. Patients who have a history of malignancy, including malignant 
thymoma, or myeloproliferative or lymphoproliferative disorders, 
unless deemed cured by adequate treatment with no evidence of 
recurrence for  3 years before Screening. Patients with completely 
excised non-melanoma skin cancer (such as basal cell carcinoma or 

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squamous cell carcinoma) or cervical carcinoma in situ would be 
permitted at any time. 
13. Thymectomy when performed < 3 months prior to Screening or 
planned to be performed during the trial period. 
14. Patients with clinical evidence of other significant serious disease or 
patients who underwent a recent major surgery, which could 
confound the results of the trial or put the patient at undue risk. 
Patients with renal/hepatic function impairment can be included. 
15. Patients who previously participated in a clinical trial with 
ARGX-113. 
16. Patients who received a vaccination (e.g., influenza vaccine) within 
the last 4 weeks prior to Screening. 
17. Use of any monoclonal antibody, such as rituximab and eculizumab, 
within 6 months prior to first dosing. 
Test Product, Dose and Mode 
of Administration: 
In this trial, the test product is ARGX-113, which is a human anti-
neonatal Fc receptor IgG1 Fc fragment. At Visits 1, 2, 3 and 4 of each 
Treatment Cycle, a dose of 10 mg/kg of body weight of ARGX-113 will 
be administered as an intravenous (IV) infusion over a period of 1 hour.  
The total dose per IMP infusion is capped at 1200 mg for patients with 
body weight  120 kg. 
Placebo, Dose, and Mode of 
Administration: 
Matching placebo with same buffer components as the test product, but 
without the active substance will be administered as an IV infusion over a 
period of 1 hour at Visits 1, 2, 3 and 4 of each Treatment Cycle. 
Criteria for Evaluation: 
Primary Endpoint: 
x Percentage of patients who, after the first Treatment Cycle, have a decrease of at least 2 points on the total 
MG-ADL score (compared to TC1B) for at least 4 consecutive weeks with the first of these decreases 
occurring at the latest 1 week after the last infusion of the IMP in the active versus placebo group in 
AChR-Ab seropositive patients. 
Secondary Endpoints: 
x Percentage of patients who, after the first Treatment Cycle, have a decrease of at least 3 points on the total 
QMG score (compared to TC1B) for at least 4 consecutive weeks with the first of these decreases 
occurring at the latest 1 week after the last infusion of the IMP in the active versus placebo group in 
AChR-Ab seropositive patients. 
x Percentage of patients who, after the first Treatment Cycle, have a decrease of at least 2 points on the total 
MG-ADL score (compared to TC1B) for at least 4 consecutive weeks with the first of these decreases 
occurring at the latest 1 week after the last infusion of the IMP in the active versus placebo group in the 
overall population (AChR-Ab seropositive and AChR-Ab seronegative patients). 
x Percentage of time that patients have a “clinically meaningful improvement” in total MG-ADL score 
compared to SEB during the trial (up to and including Day 126) in the active versus placebo group in 
AChR-Ab seropositive patients. 
x Time from TC1V5 to qualification for re-treatment, as assessed by monitoring the total MG-ADL score 
(compared to TC1B), in the active versus placebo group in the AChR-Ab seropositive patients. 
x Percentage of patients who, after the first Treatment Cycle, show a decrease of at least 2 points on the 
total MG-ADL score (compared to TC1B) for at least 4 consecutive weeks with the first of these decreases 
occurring at the latest after 1 or maximum 2 infusions of the IMP in the active versus the placebo group in 
AChR-Ab seropositive patients.  

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Tertiary Endpoints: 
x Percentage of patients who, from the second Treatment Cycle on, have a decrease of at least 2 points on 
the total MG-ADL score (compared to each corresponding TCB) for at least 4 consecutive weeks with the 
first of these decreases occurring at the latest 1 week after the last infusion of the IMP in the active versus 
placebo group in AChR-Ab seropositive patients. 
x Percentage of patients who, from the second Treatment Cycle on, have a decrease of at least 3 points on 
the total QMG score (compared to each corresponding TCB) for at least 4 consecutive weeks with the first 
of these decreases occurring at the latest 1 week after the last infusion of the IMP in the active versus 
placebo group in AChR-Ab seropositive patients. 
x Percentage of patients who, from the second Treatment Cycle on, have a decrease of at least 2 points on 
the total MG-ADL score (compared to each corresponding TCB) for at least 4 consecutive weeks with the 
first of these decreases occurring at the latest 1 week after last infusion of the IMP in the active versus 
placebo group in the overall population (AChR-Ab seropositive and AChR-Ab seronegative patients). 
x Percentage of time that patients have a “clinically meaningful improvement” in total MG-ADL score 
compared to SEB during the trial (up to and including Day 126) in the active versus placebo group in the 
overall population (AChR-Ab seropositive and AChR-Ab seronegative patients). 
x Total 15 item Quality of life scale for Myasthenia Gravis [revised version] (MG-QoL15r) score change 
from Baseline - SEB and TCnB (Visit 1) - to each time point in the active and placebo group. 
Statistical Methods and Plan 
The null hypothesis H0 states that there is no difference in proportion of MG-ADL responders between 
patients treated with placebo and ARGX-113. The trial is powered at 90% using significance level of 5% 
2-sided to test the alternative hypothesis of that the difference in the proportion of responders is 29% in favor 
of patients treated with ARGX-113. The proportion MG-ADL responders amongst patients treated with 
placebo is hypothesized to be 30%. In order to test this alternative hypothesis, a sample size of 150 patients is 
needed, with this allowing for 10% attrition rate. 
A Statistical Analysis Plan detailing all statistical methods and analyses will be issued before the database 
lock. A summary of the plan is described below. 
The efficacy endpoints will be tested in the modified Intention-To-Treat (mITT) and the Per Protocol (PP) 
populations. The primary endpoint is tested by means of a 2-sided exact test (using logistic regression) 
stratified for the stratification factors Japanese/non-Japanese patient, AChR-Ab serotype and SoC at the 
2-sided 5% significance level, in the AChR-Ab seropositive patients. Percentage responders will be compared 
between ARGX-113 and placebo using logistic regression model with Baseline total score as covariate and 
Japanese/non-Japanese patient, AChR-Ab serotype and SoC as stratification variables.  
The set of primary and secondary efficacy hypotheses will be tested using hierarchical testing principle at 5% 
significance level in the following order: 
1. 
MG-ADL responders after the first Treatment Cycle in AChR-Ab seropositive patients 
2. 
QMG responders after the first Treatment Cycle in AChR-Ab seropositive patients 
3. 
MG-ADL responders after the first Treatment Cycle in overall population (AChR-Ab seropositive and 
AChR-Ab seronegative patients) 
4. 
Percentage of time patients have a “clinically meaningful improvement” in total MG-ADL score in 
AChR-Ab seropositive patients 
5. 
Time from TC1V5 to qualification for re-treatment monitored by total MG-ADL score in AChR-Ab 
seropositive patients if: 
- the patients has a total MG-ADL score of  5 points with more than 50% of the total score due to 
 non-ocular symptoms, and 
- no clinically meaningful improvement (decrease in total MG-ADL score from TC1B < 2). 
6. 
Early MG-ADL responders after the first Treatment Cycle in AChR-Ab seropositive patients 

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The secondary endpoints “QMG responders after the first Treatment Cycle in AChR-Ab seropositive patients, 
MG-ADL responders after the first Treatment Cycle in the overall population, and early MG-ADL responders 
after the first Treatment Cycle in AChR-Ab seropositive patients” will be analyzed using the same 
methodology as for the primary endpoint. The secondary endpoint “Percentage of time patients have a 
clinically meaningful improvement in total MG-ADL score in AChR-Ab seropositive patients” will be 
analyzed using an analysis of covariance (ANCOVA) model with terms for randomized treatment and 
Baseline total MG-ADL score as a covariate; the model will be stratified for the stratification variables. The 
secondary endpoint “Time from TC1V5 to qualification for re-treatment monitored by total MG-ADL score in 
AChR-Ab seropositive patients” will be analyzed using Kaplan-Meier time to event analysis (stratified log-
rank test), stratified for the stratification variables. 
The continuous endpoints, i.e., total score changes from Baseline, between treatment groups at a specific day 
post-Baseline (SEB and TCnB), will be analyzed by means of Mixed Models for Repeated Measurements 
(MMRM). Baseline total score values will be included in the MMRM as well as the stratification factors. 
Moreover, summary statistics will be provided for all continuous endpoints. 
Frequency tables will be made for all binary variables, including AEs. 

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d 
Randomization (at the first Treatment Cycle Baseline [TC1B] only) should be performed as soon as possible after Screening with approximately 2 weeks, however only after confirmation of 
eligibility of the patient. 
e 
Efficacy and quality of life assessments should be completed pre-dose on each dosing day and should be performed prior to any other trial-specific assessment, except for obtaining informed 
consent at Screening and the weight assessment, if applicable. The MG-ADL scale needs to be performed prior to all other efficacy or quality of life assessments. Acetylcholinesterase 
(AChE) inhibitors must be halted for at least 12 hours before the QMG assessment (consistent with the revised manual for the QMG test as recommended by the Myasthenia Gravis 
Foundation of America Inc [MGFA]). A total MG-ADL score  5 with more than 50% of this total score attributed to non-ocular symptoms should be met at Screening and Baseline (TCnB). 
f 
Suicidal ideation and behavior will be assessed pre-dose on dosing days via a targeted question based on the Patient Health Questionnaire item 9 (PHQ-9) (Simon, Rutter et al. 2013). 
g 
The physical examination will be performed pre-dose on dosing days. See Section 7.2.3 for an overview of the different assessments. 
h 
Height will be measured at Screening only and weight will be measured at Screening, at the EoS/ED visit, and when there is an obvious weight change compared to the last weight 
assessment. 
i 
Vital signs (supine blood pressure, heart rate, body temperature) will be performed pre-dose on dosing days. It is recommended that the method used to measure body temperature at 
Screening is maintained throughout the trial for each patient. 
j 
ECG will be performed pre-dose on dosing days. 
k 
Samples for clinical laboratory tests (hematology, clinical chemistry and FSH, if applicable) will be collected pre-dose on dosing days (see Appendix 6). In addition, total IgG at Screening is 
to be assessed for defining eligibility. Patients need to be fasted at least 8 hours prior to each sampling. 
l 
Urine samples will be collected pre-dose on dosing days (see Appendix 6). 
m 
A serum pregnancy test will be performed on the samples taken for clinical laboratory tests (only for women of childbearing potential, see DEFINITION OF TERMS). 
n 
A urine pregnancy test will be performed on the urine samples taken for urinalysis (pre-dose on dosing days) (only for women of childbearing potential, see DEFINITION OF TERMS). 
o 
Samples for pharmacodynamic (PD) biomarkers will be collected pre-dose on dosing days (see Appendix 6). Anti-AChR antibodies will be measured in AChR-Ab seropositive patients 
only. Anti-MuSK antibodies will be measured in MuSK-Ab seropositive patients only. 
p 
Viral tests will be performed on samples taken at Screening (see Appendix 6).  
q 
Samples for anti-drug antibodies (ADAs) will be collected pre-dose if sampling is to be performed on dosing days. During the first Treatment Cycle, samples for ADA will be taken at Visits 
1, 4, 6 and 9. As from the second Treatment Cycle onwards, samples for ADA will only be taken at Visits 1 and 9 of the corresponding Treatment Cycle and EoS/ED. 
r 
Pharmacokinetic (PK) samples will be collected at Visits 1, 2, 3, 4, 5, and 6 and EoS/ED. On dosing days, PK samples will be collected pre-dose (within 1 hour prior to start of infusion) and 
after the end of each infusion (within 1 hour after end of infusion). 
s 
The Investigational Medicinal Product (IMP; ARGX-113 or placebo) will be administered as an intravenous (IV) infusion over a period of 1 hour at Visits 1, 2, 3, and 4. Patients will remain 
at the site for at least 1 hour following the end of the infusion for safety monitoring based on the patient’s clinical status. 
t 
At TCnV1, the conditions for re-treatment will be checked before administration of the IMP. 
u 
An unscheduled (UNS) visit can be on request of the patient or the Investigator. During the UNS visit, additional assessments as indicated in the SoA can be performed at the discretion of 
the Investigator, depending on the reason for the UNS visit. 
v 
For patients who discontinue early from randomized treatment, the assessments will depend on the visit at which it was decided that the patient had to discontinue early from randomized 
treatment (see Section 5.6). Patients who discontinue early from randomized treatment within a Treatment Cycle will have to complete the EoT assessments and complete the remaining 
visits in the current Treatment Cycle prior to entering the Safety and Disease Severity Follow-up (FU) period as per the SoA for Patients who Discontinued Early from Randomized 
Treatment (Table 2). These patients will not receive any further IMP administration during the trial. Patients who discontinue early from randomized treatment in the ITC period will have to 
complete the EoT assessments and then continue into the Safety and Disease Severity Follow-up period as per Table 2. 
w 
Clinically relevant prior treatment will only be recorded once at Screening. 

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Figure 1 
Trial Design 
 
 

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TABLE OF CONTENTS 
SIGNATURES OF SPONSOR .......................................................................... 3 
SIGNATURE OF INVESTIGATOR ................................................................ 4 
DOCUMENT HISTORY ................................................................................... 5 
SUMMARY OF CHANGES .............................................................................. 5 
SYNOPSIS ......................................................................................................... 18 
TABLE OF CONTENTS ................................................................................. 33 
LIST OF TABLES ............................................................................................ 37 
LIST OF FIGURES .......................................................................................... 37 
LIST OF APPENDICES .................................................................................. 37 
LIST OF ABBREVIATIONS .......................................................................... 38 
DEFINITION OF TERMS .............................................................................. 40 
1. 
INTRODUCTION .................................................................................... 43 
1.1. 
Background Information ....................................................................................43 
1.2. 
Investigational Medicinal Product ....................................................................44 
1.3. 
Standard of Care and Rationale for Use of ARGX-113 ..................................45 
1.4. 
Benefit-Risk Assessment .....................................................................................47 
2. 
TRIAL OBJECTIVES ............................................................................. 48 
2.1. 
Primary Objective ...............................................................................................48 
2.2. 
Secondary Objectives ..........................................................................................48 
2.3. 
Tertiary Objective ...............................................................................................49 
3. 
TRIAL ENDPOINTS ............................................................................... 49 
3.1. 
Primary Endpoint ...............................................................................................49 
3.2. 
Secondary Endpoints ..........................................................................................49 
3.3. 
Tertiary Endpoints ..............................................................................................50 
4. 
INVESTIGATIONAL PLAN .................................................................. 51 

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4.1. 
Summary of Trial Design ...................................................................................51 
4.2. 
Discussion of Trial Design ..................................................................................54 
4.3. 
Selection of Trial Population ..............................................................................56 
4.3.1. 
Inclusion Criteria ...................................................................................................... 56 
4.3.2. 
Exclusion Criteria ..................................................................................................... 57 
4.4. 
Early Discontinuation .........................................................................................58 
4.4.1. 
Early Discontinuation from Trial ............................................................................. 59 
4.4.2. 
Early Discontinuation from Randomized Treatment ............................................... 59 
4.4.3. 
Temporary Interruption from Randomized Treatment ............................................. 60 
4.4.4. 
Missed Doses ........................................................................................................... 60 
4.5. 
Roll-Over to Follow-on Trial .............................................................................60 
4.6. 
Protocol Deviations .............................................................................................61 
4.7. 
Screen Failures, Rescreening, and Retesting ....................................................61 
4.8. 
Early Termination of Trial or Site ....................................................................62 
4.9. 
End of Trial definition ........................................................................................62 
5. 
TRIAL PROCEDURES ........................................................................... 62 
5.1. 
Informed Consent ...............................................................................................63 
5.2. 
Screening ..............................................................................................................63 
5.3. 
Randomization ....................................................................................................64 
5.4. 
Treatment Cycle ..................................................................................................66 
5.4.1. 
Treatment Period ...................................................................................................... 66 
5.4.2. 
Follow-up Period ...................................................................................................... 67 
5.5. 
Inter Treatment Cycle Period ............................................................................68 
5.6. 
End of Treatment ................................................................................................69 
5.7. 
Safety and Disease Severity Follow-up Period for Patients who Discontinued 
Early from Randomized Treatment ..................................................................69 
5.8. 
End of Study and Early Discontinuation (EoS/ED) Visit ................................70 
5.9. 
Unscheduled Visit ................................................................................................70 
6. 
TRIAL TREATMENTS ........................................................................... 71 
6.1. 
Treatments Administered...................................................................................71 

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6.2. 
Identity of Investigational Medicinal Products ................................................71 
6.3. 
Packaging and Labeling .....................................................................................72 
6.4. 
Storage of Investigational Medicinal Products ................................................72 
6.5. 
Method of Assigning Patients to Treatment Group .........................................72 
6.6. 
Timing of Dose for Each Patient ........................................................................73 
6.7. 
Blinding ................................................................................................................73 
6.8. 
Prior Treatments and Concomitant Medications ............................................73 
6.8.1. 
Prohibited Medications during the Trial .................................................................. 74 
6.8.2. 
Rescue Therapy ........................................................................................................ 74 
6.9. 
Medical Care of Patients after End of Study ....................................................74 
6.10. 
Treatment Compliance .......................................................................................75 
6.11. 
Handling Missed Doses of the Investigational Medicinal Product .................75 
6.12. 
Accountability of Investigational Medicinal Product ......................................75 
6.13. 
Storage of Blood Samples in the Trial ...............................................................75 
7. 
TRIAL ASSESSMENTS .......................................................................... 75 
7.1. 
Efficacy and Quality of Life ...............................................................................75 
7.1.1. 
Myasthenia Gravis-Activities of Daily Living ......................................................... 76 
7.1.2. 
Quantitative Myasthenia Gravis ............................................................................... 76 
7.1.3. 
Myasthenia Gravis Composite ................................................................................. 76 
7.1.4. 
15-Item Quality of Life Scale for Myasthenia Gravis .............................................. 77 
7.1.5. 
EQ-5D-5L ................................................................................................................ 77 
7.2. 
Safety ....................................................................................................................77 
7.2.1. 
Adverse Events ......................................................................................................... 78 
7.2.2. 
Clinical Laboratory Evaluations ............................................................................... 84 
7.2.3. 
Vital Signs, Physical Examination, and ECG .......................................................... 85 
7.2.4. 
Suicidality Assessment ............................................................................................. 85 
7.2.5. 
Medical and Surgical History ................................................................................... 86 
7.2.6. 
Data Safety Monitoring Board (DSMB) .................................................................. 86 
7.2.7. 
Visit Reminder/Subject ID Card .............................................................................. 86 
7.3. 
Pharmacokinetics (PK) .......................................................................................86 

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7.4. 
Pharmacodynamics (PD) ....................................................................................87 
7.5. 
Anti-Drug Antibodies (ADA) .............................................................................87 
8. 
STATISTICS ............................................................................................. 87 
8.1. 
Determinations of Sample Size ..........................................................................87 
8.2. 
Analysis Populations ...........................................................................................88 
8.3. 
Patient Disposition, Characteristics and Concomitant Medication ...............88 
8.4. 
Statistical Methods ..............................................................................................88 
8.4.1. 
Primary Endpoint Analyses ...................................................................................... 88 
8.4.2. 
Secondary Endpoint Analyses .................................................................................. 89 
8.4.3. 
Tertiary Endpoint Analyses ...................................................................................... 89 
8.5. 
Interim Analyses .................................................................................................91 
9. 
QUALITY CONTROL AND QUALITY ASSURANCE ..................... 91 
9.1. 
Investigator’s Responsibility ..............................................................................91 
9.2. 
Quality Control of Data ......................................................................................92 
9.3. 
Monitoring ...........................................................................................................92 
9.4. 
Data Management ...............................................................................................93 
9.5. 
Quality Assurance Audit ....................................................................................94 
10. ETHICS ..................................................................................................... 94 
10.1. 
Institutional Review Board or Independent Ethics Committee......................94 
10.2. 
Ethical Conduct of the Trial ..............................................................................95 
10.3. 
Patient Information and Informed Consent .....................................................95 
10.4. 
Patient Data Protection ......................................................................................96 
11. TRIAL ADMINISTRATION .................................................................. 96 
11.1. 
Data Handling and Record Keeping .................................................................96 
11.2. 
Direct Access to Source Data/Documents .........................................................96 
11.3. 
Investigator Information ....................................................................................97 
11.3.1. 
Investigator Obligations ........................................................................................... 97 
11.3.2. 
Protocol Signatures .................................................................................................. 97 
11.3.3. 
Publication Policy .................................................................................................... 97 

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11.3.4. 
Financing and Insurance........................................................................................... 98 
12. REFERENCES.......................................................................................... 99 
13. APPENDICES ......................................................................................... 101 
 
LIST OF TABLES 
Table 1 
General Schedule of Assessments.................................................................................... 28 
Table 2 
Schedule of Assessments for Patients who Discontinued Early from Randomized 
Treatmenta ........................................................................................................................ 31 
 
LIST OF FIGURES 
Figure 1 
Trial Design ..................................................................................................................... 32 
 
LIST OF APPENDICES 
Appendix 1 Myasthenia Gravis-Activities of Daily Living ............................................................... 101 
Appendix 2 Quantitative Myasthenia Gravis Score .......................................................................... 102 
Appendix 3 Myasthenia Gravis Composite Scale ............................................................................. 103 
Appendix 4 Revised Version of 15-Item Quality of Life Scale for Myasthenia Gravis (MG-QoL15r)
 ....................................................................................................................................... 104 
Appendix 5 EQ-5D-5L (UK English Sample Version) ..................................................................... 105 
Appendix 6 Laboratory Evaluations .................................................................................................. 107 
Appendix 7 
 
Appendix 8 Decision Tree for Re-treatment – Part A ....................................................................... 109 
Appendix 9 Decision Tree for Re-treatment – Part B ....................................................................... 110 
 
CCI

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LIST OF ABBREVIATIONS 
Ab 
Antibody 
ABDEG™ 
Antibody that enhances IgG degradation 
AChE 
Acetylcholinesterase 
AChR 
Acetylcholine receptor 
ADA 
Anti-drug antibodies 
ADL 
Activities of daily living 
ADR 
Adverse drug reaction 
AE 
Adverse event 
ANCOVA 
Analysis of covariance 
CI 
Confidence interval 
CIOMS 
Council for International Organizations of Medical Sciences 
Cmax 
Maximum observed serum concentration 
CRO 
Contract research organization 
CTCAE 
Common Terminology Criteria for Adverse Events 
CTR 
Clinical trial report 
DSMB 
Data Safety Monitoring Board 
ECG 
Electrocardiogram 
eCRF 
electronic Case Report Form 
EDC 
Electronic data capture 
EoS 
End of Study 
EoT 
End of Treatment 
EQ-5D-5L 
EuroQoL 5 Dimensions 5 Levels 
Fc 
Fragment, crystallized 
FcRn 
neonatal Fc Receptor 
FDA 
Food and Drug Administration 
FSH 
Follicle-Stimulating Hormone 
FU 
Follow-up 
GCP 
Good Clinical Practice 
gMG 
Generalized myasthenia gravis 
HBV 
Hepatitis B virus 
HCV 
Hepatitis C virus 
HIV 
Human immunodeficiency virus 
IB 
Investigator brochure 
ICF 
Informed consent form 
ICH 
International Council for Harmonization 
IEC 
Independent Ethics Committee 
IgG 
Immunoglobulin G 
IMP 
Investigational medicinal product 

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IND 
Investigational New Drug 
IRB 
Institutional Review Board 
IRT 
Interactive Response Technology 
ITC 
Inter treatment cycle 
IV 
Intravenous 
IVIg 
Intravenous immunoglobulin 
LRP4 
Lipoprotein receptor-related protein-4 
LS 
Least square means 
MG 
Myasthenia gravis 
MG-ADL 
Myasthenia Gravis Activities of Daily Living 
MGC 
Myasthenia Gravis Composite 
MGFA 
Myasthenia Gravis Foundation of America 
MG-QoL15r 
15-item Quality of life scale for Myasthenia Gravis [revised 
version] 
mITT 
modified Intention-To-Treat 
MMRM 
Mixed Models for Repeated Measurements 
MuSK 
Muscle-specific kinase 
NCI 
National Cancer Institute 
NSID 
Non-steroidal immunosuppressive drug 
PD 
Pharmacodynamics 
PHQ-9 
Patient Health Questionnaire item 9 
PLEX 
Plasma Exchange 
PK 
Pharmacokinetics 
PP 
Per protocol 
QMG 
Quantitative Myasthenia Gravis 
SAE 
Serious adverse event 
SEB 
Study entry baseline 
SoA 
Schedule of assessments 
SoC 
Standard of care 
SOP 
Standard operating procedures 
SUSAR 
Suspected unexpected serious adverse reaction 
TCB 
Treatment cycle baseline 
TC1B 
First Treatment Cycle Baseline 
TCnB 
Subsequent Treatment Cycle Baseline 
TEAE 
Treatment-emergent adverse event 
UN 
Unstructured covariance structure 
UNS 
Unscheduled visit 
US 
United States 
WBC 
White blood cell  
WHO(-DD) 
World Health Organization (drug dictionary) 

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DEFINITION OF TERMS 
Blinding: 
A procedure in which one or more parties to the trial are kept 
unaware of the treatment assignment in order to reduce the 
risk of biased trial outcomes. The level of blinding is 
maintained throughout the conduct of the trial, and only 
when the data are cleaned to an acceptable level of quality 
will appropriate personnel be unblinded or when required in 
case of a (serious) adverse event ([S]AE). In a double-blind 
trial, the subject, the Investigator and Sponsor staff who are 
involved in the treatment or clinical evaluation of the 
subjects and the review or analysis of data are all unaware of 
the treatment assignment.  
Childbearing potential: 
Women of childbearing potential are defined as all female 
participants unless they are postmenopausal (defined by 
continuous amenorrhea) for at least 2 years with a follicle-
stimulating hormone (FSH) > 40 IU/L or are surgically 
sterile (i.e., who had a hysterectomy, bilateral oophorectomy, 
or have current documented tubal ligation or any other 
permanent female sterilization procedure). Determination of 
FSH levels can be used to confirm postmenopausal status in 
amenorrheic patients not on hormonal replacement therapy if 
the test result is within the postmenopausal range per the 
central laboratory. 
Council for International 
Organizations of Medical 
Sciences (CIOMS): 
The Council for International Organizations of Medical 
Sciences (CIOMS) is an international, non-governmental, 
non-profit organization established jointly by the World 
Health Organization (WHO) and UNESCO in 1949. They 
provide a set of ethical principles regarding human 
experimentations, including International Reporting of 
Adverse Drug Reactions and International Reporting of 
Periodic Drug-Safety Update Summaries. 
The CIOMS form provides a standardized format for the 
reporting of suspected adverse reactions to any particular 
medical product and is the acceptable and widely used 
format for reporting suspect adverse drug reaction 
(ADR)/suspected unexpected serious adverse reaction 
(SUSAR) in clinical trials. 

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Contract research 
organization (CRO): 
A person, or a group of persons (commercial, academic, or 
other), who as an independent contractor with argenx BVBA, 
assume(s) one or more obligations of argenx BVBA, 
e.g., development of a protocol, selection and/or monitoring 
of Investigators, evaluation of reports, preparation of 
materials to be submitted to Health Authorities. 
Database lock: 
An action taken to prevent further changes to a trial database. 
A database is locked after review, query resolution, data 
cleaning and determination that it is ready for analysis. 
Data Safety Monitoring 
Board (DSMB): 
Independent group of experts that advises and whose 
responsibilities are to periodically review and evaluate the 
accumulated trial data for participant safety, trial conduct and 
progress and, when appropriate, efficacy and to make 
recommendation to the Sponsor concerning the continuation, 
modification or termination of the trial. 
Eligible: 
Qualified for randomization into the trial based upon strict 
adherence to inclusion/exclusion criteria. 
Good clinical practices 
(GCP): 
A standard for the design, conduct, performance, monitoring, 
auditing, recording, analyses, and reporting of clinical trials 
that provides assurance that the data and reported results are 
credible and accurate, and that the rights, integrity, and 
confidentiality of trial subjects are protected. (International 
Council for Harmonization [ICH] E6). 
Institutional Review 
Board (IRB)/Independent 
Ethics Committee (IEC): 
An independent body (a review board or a committee, 
institutional, regional, national, or supranational), constituted 
of medical professionals and non-medical members, whose 
responsibility it is to ensure the protection of the rights, 
safety and well-being of human subjects involved in a trial 
and to provide public assurance of that protection, by, among 
other things, reviewing and approving / providing favorable 
opinion on, the trial protocol, the suitability of the 
Investigator(s), facilities, and the methods and material to be 
used in obtaining and documenting informed consent of the 
trial subjects. 

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Informed consent/ 
Informed consent form 
(ICF): 
A process by which a clinical investigation participant 
voluntarily confirms his or her willingness to participate in a 
particular clinical trial, after having been informed of all 
aspects of the trial that are relevant to the participant’s 
decision to participate. Informed consent is documented by 
means of a dated and signed informed consent form (ICF). 
International Conference 
on Harmonization (ICH): 
The International Conference on Harmonization of Technical 
Requirements for Registration of Pharmaceuticals for Human 
Use (ICH) is a project that brings together the regulatory 
authorities of Europe, Japan and the United States and 
experts from the pharmaceutical industry in the three regions 
to discuss scientific and technical aspects of pharmaceutical 
product registration. 
Investigational medicinal 
product: 
A pharmaceutical form of an active ingredient or placebo 
being tested or used as a reference in a clinical trial, 
including a product with a marketing authorization when 
used in a way different from the approved form, or when 
used for an unapproved indication, or when used to gain 
further information about an approved use.  
Protocol amendment: 
A written description of a change(s) to or formal clarification 
of a protocol. 
Randomization: 
Process of random attribution of treatment to subjects in 
order to reduce bias of selection. 
Treatment: 
Term used throughout the clinical trial to denote a set of 
investigational product(s) or marketed product(s) or placebo 
intended to be administered to a subject, identified by a 
unique number, according to the trial randomization or 
treatment allocation. 

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1. 
INTRODUCTION 
1.1. 
Background Information 
Myasthenia gravis (MG) is an autoimmune disorder characterized in most cases by T-cell 
and antibody responses to neuromuscular junction proteins such as skeletal muscle nicotinic 
acetylcholine receptor (AChR). Antibodies against epitopes of the AChR of the 
neuromuscular junction cause failure of neuromuscular transmission, resulting in the 
characteristic fatigue and weakness associated with this severe disorder. The muscle 
weakness fluctuates with activity, and periods of rest offer only a temporary reprieve 
(Howard, Barohn et al. 2013).  
Autoimmune MG has a reported worldwide prevalence of 40-180 per million people and an 
annual incidence of 4-12 per million people. Overall, MG incidence and prevalence shows 
little geographic variation (Gilhus and Verschuuren 2015).  
Autoimmune MG is characterized by the presence of antibodies against several components 
of the neuromuscular junctions. The most common antibody found in autoimmune MG is 
directed against post-synaptic AChRs. Anti-AChR antibodies are present in approximately 
80% of all autoimmune MG patients. Less frequent autoantibodies found in autoimmune MG 
include the anti-muscle-specific kinase (MuSK) antibody (4% of the cases) and the anti-
lipoprotein receptor-related protein-4 (LRP4) antibody (2% of the cases) directed against 
LPR4. All these autoantibodies belong to the immunoglobulin G (IgG) class (Gilhus and 
Verschuuren 2015; Gilhus 2016).  
In approximately 5-20% of the MG patients, no serum antibodies against neuromuscular 
junction proteins can be detected (Vincent, Lang et al. 2006; Kaminski 2016). Although in 
some seronegative MG patients the disease may not be mediated by antibodies, in other cases 
the (apparent) absence of specific autoantibodies in patients may be due to insufficient 
sensitivity of the assay. Indeed, one third of MG patients, who are seronegative on standard 
testing, are seropositive on cell-based testing. The seronegative group probably includes 
some patients with anti-AChR, -MuSK or -LRP4 antibodies that are not detected because of 
insufficient test sensitivity (Gilhus 2016).  
The treatment of MG is based on a variety of medications and medical procedures used either 
alone or in combination (see Section 1.3). 
Given the pathogenic role of autoantibodies in MG, a possible novel therapeutic approach to 
this disease may include the use of drugs that lower the level of pathogenic autoantibodies 
rapidly and sustainably. Since all the specific autoantibodies found in MG belong to the IgG 
isotype, agents that specifically lower the level of these antibodies without affecting the level 
of other isotypes such as IgA, IgE and IgM may be of special interest. 

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One such strategy involves inhibition of the neonatal Fc receptor (FcRn). FcRn was shown to 
play a central role in trafficking IgGs and albumin into recycling pathways rescuing them 
from lysosomal degradation. Molecules that block the interaction of FcRn with IgGs are 
expected to induce degradation and fast clearance of pathogenic IgGs leading to a lowering 
of their serum level (Roopenian and Akilesh 2007; Challa, Velmurugan et al. 2014). 
Thus, targeting the FcRn-IgG interaction would be a rational therapeutic approach to rapidly 
clear pathogenic autoantibodies in IgG-driven autoimmune diseases such as MG. 
1.2. 
Investigational Medicinal Product 
ARGX-113 is a human IgG1-derived Fc fragment of the za allotype that binds with 
nanomolar affinity to human FcRn. ARGX-113 encompasses IgG1 residues D220-K447 (EU 
numbering scheme) and has been modified with the so-called ABDEG™ technology 
(ABDEG™ = antibody that enhances IgG degradation) (Vaccaro, Zhou et al. 2005) to 
increase its affinity for FcRn at both physiological and acidic pH. The increased affinity for 
FcRn of ARGX-113 at both acidic and physiological pH results in a constitutively blockage 
of FcRn-mediated recycling of IgGs. 
Given the essential role of the FcRn receptor in IgG homeostasis, inhibiting this FcRn 
function, as achieved by ARGX-113, leads to rapid degradation of IgGs, which is expected to 
include autoantibodies in IgG-driven autoimmune diseases. 
This concept has been validated in various murine disease models together with 
pharmacokinetic/pharmacodynamic (PK/PD) studies in cynomolgus monkeys, either by 
using ARGX-113 or a full-length mAb analogue (HEL-ABDEG™) (Patel, Puig-Canto et al. 
2011; Challa, Bussmeyer et al. 2013). 
The antibody clearing properties of ARGX-113 were confirmed in PK/PD studies in 
cynomolgus monkeys. A single infusion of ARGX-113 resulted in a decrease of IgG up to 
55% without altering serum albumin concentrations nor IgM or IgA levels. This PD effect as 
measured with a tracer IgG molecule was proven to be more potent than intravenous 
immunoglobulin (IVIg), both in rapidity of onset as in depth of the effect. Repeated dosing 
could improve the PD effect up to a maximum IgG reduction of 75%. 
These nonclinical data validated the further development of ARGX-113 for assessing its 
therapeutic potential in IgG driven autoimmune indications. 
To date, a Phase 1 (ARGX-113-1501) and a Phase 2 (ARGX-113-1602) trial are completed 
as part of the clinical development of ARGX-113 for the treatment of generalized myasthenia 
gravis (gMG).  
ARGX-113-1501 was a randomized, double-blind, placebo-controlled, First-in-Human (FIH) 
Phase 1 trial conducted in 62 healthy volunteers to assess the safety and tolerability and to 
evaluate the PK and PD characteristics of single and multiple ascending intravenous (IV) 
doses of ARGX-113. The trial showed that a single administration of ARGX-113 reduced 

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IgG levels up to 50%, while multiple dosing further lowered IgGs up to approximately 70%. 
IgG levels returned to Baseline approximately 8 weeks following the last administration of 
ARGX-113. IV administration of ARGX-113 at single doses up to 25 mg/kg and multiple 
doses of 10 mg/kg and 25 mg/kg were safe and well tolerated.  
Based on an optimal PD effect combined with minimal number of observed adverse events 
(AEs) (compared to the 25 mg/kg dose level), the dose of 10 mg/kg once weekly for 4 weeks 
provided the most favorable risk-benefit profile and was therefore selected for further testing 
in the Phase 2 trial. The outcome of the Phase 2 trial indicated the efficacy and safety of 
10 mg/kg in 4 weekly infusions in gMG patients. 
ARGX-113-1602 was a randomized, double-blind, placebo-controlled, multicenter Phase 2 
trial to evaluate the safety, efficacy, and PK of ARGX-113 for the treatment of autoimmune 
MG patients with generalized muscle weakness. Eligible patients (24 in total) were 
randomized at a 1:1 ratio to receive ARGX-113 (10 mg/kg) or placebo in 4 infusions 
administered one week apart in addition to standard of care (SoC). The clinical effect of 
ARGX-113 was explored in this trial using validated efficacy scales commonly used in MG 
clinical research and practice: Myasthenia Gravis Activities of Daily Living (MG-ADL), 
Quantitative Myasthenia Gravis (QMG), Myasthenia Gravis Composite (MGC), and 15 item 
Quality of life scale for Myasthenia Gravis [revised version] (MG-QoL15r). The efficacy 
data of the 4 scales consistently point in the same direction and show a rapid onset of action, 
and a relevant and long-lasting clinical improvement over placebo. More specifically, on the 
MG-ADL scale, 75% of the patients treated with ARGX-113 had a sustained clinically 
relevant reduction in total MG-ADL scores (defined as a reduction of at least 2 points from 
Baseline) for a period of at least 6 consecutive weeks (starting at the latest 1 week after last 
infusion of the Investigational Medicinal Product [IMP]) versus 25% of patients on placebo 
(difference was found to be statistically significant). Furthermore, this clinical improvement 
observed in all scales was in line with the observed PD data, namely a reduction of total IgG 
and subtypes and a decreased level of AChR autoantibodies. 
The proposed Phase 3 trial aims to establish the efficacy, safety and tolerability of ARGX-
113 in class II-IVb gMG patients, and thereby validating the concept of autoantibody 
reduction as a therapeutic treatment modality in this indication. 
This trial will be performed in compliance with the protocol, International Council for 
Harmonization, Good Clinical Practice (ICH GCP), Declaration of Helsinki, and other 
applicable regulatory requirements. 
1.3. 
Standard of Care and Rationale for Use of ARGX-113 
Several drugs and medical procedures are routinely used in the management of gMG. 
Acetylcholinesterase (AChE) inhibitors are frequently used in treatment of MG particularly 
in the mild forms of the disease. These agents include drugs such as pyridostigmine, 

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neostigmine, and edrophonium and their effectiveness varies widely. These drugs act by 
inhibiting the enzyme AChE, which is responsible for the degradation of acetylcholine. This 
prolongs the exposure of acetylcholine, which leads to an amelioration of the 
signs/symptoms of MG. Acetylcholinesterase inhibitors provide a symptomatic treatment of 
MG and do not act on the underlying pathogenic mechanism of the disease. 
Acetylcholinesterase inhibitors however do not work in all patients with MG and usually 
have a short duration of action requiring to be taken several times a day. 
Corticosteroids and non-steroidal immunosuppressive drugs (NSIDs) are also used in the 
treatment of MG. These drugs are frequently used in the more advanced stage of the disease. 
Corticosteroids and NSIDs are typically characterized by delayed onset of effects. Because of 
their multiple side effects, the lowest effective dose of corticosteroids is recommended for 
long-term treatment that is often indicated for chronic conditions such as MG. Non-steroidal 
immunosuppressive drugs are commonly used and include azathioprine, mycophenolate 
mofetil, cyclosporine, and cyclophosphamide. The use of corticosteroids and NSIDs however 
is associated with dose-dependent, frequent and often serious side effects whose management 
requires to lower the dose and to use these drugs in various combinations to find the right 
balance between efficacy and side effects (Gilhus and Verschuuren 2015; Gilhus 2016).  
Apart from the SoC described above, new biologic agents such as rituximab and eculizumab 
are also used in the treatment of specific cases of MG, such as resistant and refractory forms. 
However, the use of these drugs is also associated with serious and sometimes life-
threatening side effects (Nowak, Dicapua et al. 2011; Howard, Utsugisawa et al. 2017). 
Exacerbations of MG are treated using either therapeutic Plasma Exchange (PLEX), 
immunoadsorption or IVIg. In the case of PLEX, typically one exchange, removing one to 
two plasma volumes, is done every other day up to a total of four to six times, to improve 
muscle strength or ameliorate a myasthenic crisis. Unfortunately, this treatment is invasive 
and has frequent side effects such as hypotension, paresthesia, infections, and thrombotic 
complications. IVIg is widely used for patients with exacerbating MG. The mechanism of 
action of IVIg in MG is still unclear, and may include interference with autoantibodies, 
B-cell modulation, saturation of FcRn and complement (Meriggioli and Sanders 2009; Liu, 
Wang et al. 2010). In addition, the use of IVIg is burdensome for the patient. 
These approaches however are not always available in all clinical centers since they require 
specific facilities and instrumentation (Gilhus and Verschuuren 2015; Gilhus 2016). 
Finally, in selected cases, surgical removal of the thymus gland is also used to ameliorate the 
clinical manifestations of MG. However, thymectomy is not always effective in all patients 
and is associated with surgery-specific risks (Drachman 1994; Gilhus and Verschuuren 2015; 
Gilhus 2016; Wolfe, Kaminski et al. 2016). 
Following administration of ARGX-113 (10 mg/kg) in 4 infusions administered one week 
apart in addition to SoC in patients with autoimmune MG with generalized muscle weakness 

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in the Phase 2 trial (ARGX-113-1602, also see Section 1.2), overall ARGX-113 was well 
tolerated and demonstrated a good safety profile consistent with Phase 1 data. No serious or 
severe AEs were reported. The following events were reported as related to ARGX-113 
administration: rhinorrhea, gingivitis, headache, nausea, pruritus, paresthesia, myalgia, 
lymphocyte count decreased, monocyte count decreased, neutrophil count decreased, 
contusion, feeling hot, infusion site pain and pruritus, and herpes zoster. All these events 
were reported as mild, except the herpes zoster, which was considered as moderate and 
occurred in a patient concomitantly treated with a systemic corticosteroid and NSID. 
ARGX-113 demonstrated a relevant and long-lasting improvement over placebo of the 
clinical manifestations of MG as measured by all 4 clinical efficacy MG scales, which 
reached statistical significance at specific timepoints on the MG-ADL, QMG, and 
MGQoL15r scales. Pharmacokinetic, PD, and immunogenicity profiles were consistent with 
Phase 1 data. In addition, a potent and long-lasting reduction of AChR autoantibodies was 
observed. 
Myasthenia gravis is considered a highly autoantibody driven disease. ARGX-113 is a highly 
targeted therapy postulated to result in reduced autoantibody levels. Results from the Phase 2 
trial indicate that it induces a strong and long-lasting improvement of the disease as measured 
by different efficacy scales while showing a favorable safety profile. Furthermore, this 
clinical improvement was in line with the observed PD data, namely a reduction of total IgG 
and subtypes and a decreased level of AChR autoantibodies. Therefore, ARGX-113 is 
believed to be a promising treatment to reduce autoantibodies in gMG patients. 
1.4. 
Benefit-Risk Assessment 
Benefits 
The clinical effect of ARGX-113 was explored using clinical activity tools commonly used 
in MG clinical research and practice: total MG-ADL, QMG, MGC, and MG-QoL15r scores. 
A mean total score change from Baseline in total MG-ADL, QMG, MGC, and MG-QoL15r 
scores was observed as early as Day 8 in patients treated with ARGX-113. A long-lasting 
reduction in total MG-ADL and MGC scores was observed, with the reduction in total scores 
still seen at Day 78 (End of Study, EoS). ARGX-113 showed a statistically significant 
reduction in total MG-ADL, QMG, and MG-QoL15r scores compared with placebo at 
specific time points, indicating a clinical improvement in ARGX-113 treatment over placebo. 
For all MG scales, a greater maximum mean change from Baseline (reduction) was observed 
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Risks 
There have been no major safety findings arising from the ongoing and completed studies or 
any pattern of AEs which would raise concerns or alter the potential benefit-risk profile of 
ARGX-113.  
Please refer to the current Investigator Brochure (IB), Section 5.5, for the summary of 
potential risks and benefits of ARGX-113. 
An independent Data Safety Monitoring Board (DSMB) is responsible for ongoing safety 
monitoring during the trial and will meet on a regular basis (see Section 7.2.6). 
Taking into account the efficacy and safety data collected up to date and the design of the 
trial, which minimizes the risk to patients participating in this trial, the potential risks 
identified in association with ARGX-113 are justified by the potential benefits that may be 
afforded to patients receiving ARGX-113. 
2. 
TRIAL OBJECTIVES 
2.1. 
Primary Objective 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of “MG-ADL 
responders” after the first Treatment Cycle in the AChR-antibody (Ab) seropositive 
population. 
2.2. 
Secondary Objectives 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of “QMG 
responders” after the first Treatment Cycle in the AChR-Ab seropositive population. 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of “MG-ADL 
responders” after the first Treatment Cycle in the overall population (AChR-Ab 
seropositive and AChR-Ab seronegative patients). 
x 
To evaluate the efficacy of ARGX-113 as assessed by the percentage of time that 
patients show a “clinically meaningful improvement” in total MG-ADL score during the 
trial (up to and including Day 126) in the AChR-Ab seropositive population. 
x 
To evaluate the efficacy of ARGX-113 as assessed by the time to qualification for first 
re-treatment in the AChR-Ab seropositive population. 
x 
To evaluate the onset of efficacy of ARGX-113 as assessed by the percentage of “early 
MG-ADL responders” after the first Treatment Cycle in the AChR-Ab seropositive 
population. 
x 
To evaluate the safety and tolerability of ARGX-113 in the overall population and in 
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2.3. 
Tertiary Objective 
x 
To assess additional efficacy and safety parameters, PD and immunogenicity. 
Definitions 
An “MG-ADL responder” is defined as a patient who shows a decrease of at least 2 points on 
the total MG-ADL score (compared to the corresponding Treatment Cycle Baseline [TCB]) 
for at least 4 consecutive weeks with the first of these decreases occurring at the latest 1 week 
after last infusion of IMP of the corresponding cycle. The scoring of MG-ADL should be 
performed by a trained and certified evaluator. 
A “QMG responder” is defined as a patient who shows a decrease of at least 3 points on the 
total QMG score (compared to the corresponding TCB) for at least 4 consecutive weeks with 
the first of these decreases occurring at the latest 1 week after last infusion of IMP of the 
corresponding cycle. The scoring of QMG should be performed by a trained evaluator. 
An “early MG-ADL responder” is defined as a patient who shows a decrease of at least 
2 points on the total MG-ADL score (compared to the corresponding TCB) for at least 
4 consecutive weeks with the first of these decreases occurring after 1 or maximum 2 infusions 
of IMP of the corresponding cycle. The scoring of MG-ADL should be performed by a trained 
and certified evaluator. 
An MG-ADL “clinically meaningful improvement” is defined as a decrease of at least 2 points 
on the total MG-ADL score compared to either Study Entry Baseline (SEB) or corresponding 
TCB. 
A QMG “clinically meaningful improvement” is defined as a decrease of at least 3 points on 
the total QMG score compared to either SEB or corresponding TCB. 
3. 
TRIAL ENDPOINTS 
3.1. 
Primary Endpoint 
x 
Percentage of patients who, after the first Treatment Cycle, have a decrease of at least 
2 points on the total MG-ADL score (compared to TC1B) for at least 4 consecutive 
weeks with the first of these decreases occurring at the latest 1 week after the last 
infusion of the IMP in the active versus placebo group in AChR-Ab seropositive 
patients. 
3.2. 
Secondary Endpoints 
x 
Percentage of patients who, after the first Treatment Cycle, have a decrease of at least 
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with the first of these decreases occurring at the latest 1 week after the last infusion of 
the IMP in the active versus placebo group in AChR-Ab seropositive patients. 
x 
Percentage of patients who, after the first Treatment Cycle, have a decrease of at least 
2 points on the total MG-ADL score (compared to TC1B) for at least 4 consecutive 
weeks with the first of these decreases occurring at the latest 1 week after the last 
infusion of the IMP in the active versus placebo group in the overall population 
(AChR-Ab seropositive and AChR-Ab seronegative patients). 
x 
Percentage of time that patients have a “clinically meaningful improvement” in total 
MG-ADL score compared to SEB during the trial (up to and including Day 126) in the 
active versus placebo group in AChR-Ab seropositive patients. 
x 
Time from TC1V5 to qualification for re-treatment, as assessed by monitoring the total 
MG-ADL score (compared to TC1B), in the active versus placebo group in the AChR-
Ab seropositive patients. 
x 
Percentage of patients who, after the first Treatment Cycle, show a decrease of at least 
2 points on the total MG-ADL score (compared to TC1B) for at least 4 consecutive 
weeks with the first of these decreases occurring at the latest after 1 or maximum 
2 infusions of the IMP in the active versus the placebo group in AChR-Ab seropositive 
patients. 
3.3. 
Tertiary Endpoints 
x 
Percentage of patients who, from the second Treatment Cycle on, have a decrease of at 
least 2 points on the total MG-ADL score (compared to each corresponding TCB) for 
at least 4 consecutive weeks with the first of these decreases occurring at the latest 
1 week after the last infusion of the IMP in the active versus placebo group in 
AChR-Ab seropositive patients. 
x 
Percentage of patients who, from the second Treatment Cycle on, have a decrease of at 
least 3 points on the total QMG score (compared to each corresponding TCB) for at 
least 4 consecutive weeks with the first of these decreases occurring at the latest 1 week 
after the last infusion of the IMP in the active versus placebo group in AChR-Ab 
seropositive patients. 
x 
Percentage of patients who, from the second Treatment Cycle on, have a decrease of at 
least 2 points on the total MG-ADL score (compared to each corresponding TCB) for 
at least 4 consecutive weeks with the first of these decreases occurring at the latest 
1 week after last infusion of the IMP in the active versus placebo group in the overall 
population (AChR-Ab seropositive and AChR-Ab seronegative patients). 
x 
Percentage of time that patients have a “clinically meaningful improvement” in total 
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active versus placebo group in the overall population (AChR-Ab seropositive and 
AChR-Ab seronegative patients). 
x 
Total MG-QoL15r score change from Baseline - SEB and TCnB (Visit 1) - to each time 
point in the active and placebo group. 
4. 
INVESTIGATIONAL PLAN 
4.1. 
Summary of Trial Design 
DESCRIPTION 
This is a randomized, double-blind, placebo-controlled, multicenter Phase 3 trial to evaluate 
the efficacy, safety, tolerability, quality of life and impact on normal daily activities of 
ARGX-113 in patients with gMG. 
The trial duration is 26 weeks, which consists of: 
x 
a treatment part where all randomized patients will be treated with IMP, and  
x 
a re-treatment part where patients may be re-treated with IMP on an “as needed basis” 
during the timeframe of the trial. 
The trial will include patients on a stable SoC with a total MG-ADL score of  5 points at 
Screening and Baseline and with more than 50% of the total score attributed to non-ocular 
symptoms. 
The time between Treatment Cycles is based on the duration of the treatment effect and may 
vary from patient to patient and for each patient from cycle to cycle (patient-tailored 
approach). 
SAMPLE SIZE AND STRATIFICATION 
Approximately 150 patients will be stratified according to 3 stratification factors: Japanese 
vs. non-Japanese patient, AChR-Ab status (seropositive vs. seronegative) and SoC (patients 
on NSIDs vs. patients not on NSIDs) and randomized (1:1) within each stratum to be treated 
with either placebo or ARGX-113, on top of their current SoC. A maximum of 20% of 
AChR-Ab seronegative patients will be allowed in the trial. 
Definition: A Japanese patient is defined as a patient whose parents and four 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. 
 
TREATMENT CYCLES AND BASELINES 
The trial will include a Screening period (pre-randomization) of approximately 2 weeks, a 
first Treatment Cycle and a variable number of subsequent Treatment Cycles administered on 
an “as needed basis”. Each Treatment Cycle consists of 9 weekly visits over a period of 

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8 weeks, consisting of a Treatment period of 3 weeks (4 weekly infusions) and a Follow-up 
(FU) period of 5 weeks (see Figure 1). The SEB and the (first) Treatment Cycle Baseline 
(TC[1]B) will both be set at randomization (Visit 1), whilst the Baseline of each subsequent 
Treatment Cycle (TCnB) will be set at Visit 1 of each corresponding Treatment Cycle. 
SCREENING AND TREATMENT 
During the Screening period, patient’s eligibility for trial participation will be evaluated.  
During the Treatment Cycles, eligible patients will receive, on top of their current SoC and in 
a blinded fashion, 4 weekly infusions of either 10 mg/kg ARGX-113 or placebo at Visit 1, 
Visit 2, Visit 3 and Visit 4 of the corresponding Treatment Cycle. 
STANDARD OF CARE (SoC) 
Patients should be on a stable dose and frequency of SoC prior to Screening as detailed in 
Section 4.3.1 (inclusion criterion n°5). Permitted SoC for MG treatment under this protocol 
include NSIDs (e.g., azathioprine, methotrexate, cyclosporine, tacrolimus, mycophenolate 
mofetil, and cyclophosphamide), steroids, as well as AChE inhibitors. In case these 
medications are taken for another indication than MG, same conditions apply. 
For the entire duration of the trial, a change in the type or dose/regimen of SoC (replacing, 
adding or removing SoC, or adjustment of the SoC dose and/or frequency) is not allowed. 
Administration of AChE inhibitors must be halted for at least 12 hours prior to performing 
the QMG assessment (consistent with the revised manual for the QMG test as recommended 
by the Myasthenia Gravis Foundation of America Inc [MGFA]) (Barohn 2000). Following 
this requirement, this possible temporary change in dosing regimen of AChE inhibitors will 
not be considered as a change in SoC. 
TIME BETWEEN TREATMENT CYCLES 
At the end of each Treatment Cycle, patients will enter a variable Inter Treatment Cycle 
(ITC) period during which they will be treated with their SoC only. The length of the ITC 
period may vary from patient to patient and for each patient from cycle to cycle (patient-
tailored approach). The visit frequency in the ITC period is every two weeks, starting 14 days 
(± 2 days) from the last visit of the previous Treatment Cycle. 
RE-TREATMENT 
Each patient will start a new Treatment Cycle with ARGX-113 or placebo when all the 
following criteria apply (see Appendix 8): 
x 
The patient has completed the previous Treatment Cycle (i.e. an 8-week time period after 
first dosing date) AND 
x 
The patient has a total MG-ADL score of  5 points with more than 50% of the total 
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x 
The Treatment Cycle can start at the latest on Day 127 and can be completed within the 
timeframe of the trial (26 weeks) AND 
x 
In case the patient was an MG-ADL responder at the previous Treatment Cycle: if he/she 
has lost the response.  
Loss of response is defined as a patient who no longer shows a decrease of at least 
2 points on the total MG-ADL score compared to the corresponding TCB. 
However, patients may not receive re-treatment with ARGX-113 or placebo if, at the time of 
re-treatment, patients have clinical evidence of bacterial, viral or fungal disease, or any other 
significant disease which could confound the results of the trial or put patients at undue risk. 
Patients who are in need of an additional treatment but who are not eligible to receive re-
treatment for reasons listed here will remain in the trial to receive appropriate alternative MG 
treatment. Re-treatment with IMP may be reconsidered at next time where conditions for 
re-treatment are met, providing that at least 4 weeks have past after other MG treatment (see 
Appendix 9). 
 
ROLL-OVER 
At the EoS visit, patients will be offered the option to roll over into a long-term, single-arm, 
open-label follow-on trial (ARGX-113-1705) where they will be treated with ARGX-113 
(10 mg/kg of body weight) on an “as needed basis”.  
Patients who need re-treatment but cannot complete a Treatment Cycle within the time frame 
of the ARGX-113-1704 trial (i.e., require re-treatment after Day 127), may roll over 
immediately to the follow-on trial to receive treatment with ARGX-113. 
Patients who discontinue early from trial ARGX-113-1704, will not be offered the option to 
roll over in the follow-on trial.  
Patients who discontinue early from randomized treatment for rescue or pregnancy reasons or 
for an SAE that is likely to result in a life-threatening situation or pose a serious safety risk 
will also not be offered the option to roll over to the follow-on trial.  
Patients who discontinue early from randomized treatment for other reasons and patients who 
have a temporary interruption from randomized treatment may be offered the option to roll 
over to the follow-on trial. 
RESCUE THERAPY 
Rescue therapy will be limited to PLEX, IVIg, immunoadsorption or use of a new type of 
corticosteroid or an increased dose of the current corticosteroids used as stand-alone therapy 
or in combination. Rescue therapy is permitted for patients experiencing protocol-defined 
MG clinical deterioration AND if, in addition, the treating physician believes that the 
patient’s health is in jeopardy if rescue therapy is not given. An MG clinical deterioration 
permitting rescue therapy to be given is defined as a patient experiencing at least one of the 

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following: (1) new or worsening of respiratory / bulbar symptoms or (2) at least 2-point 
increase of individual non-ocular MG-ADL items. Whenever possible, prior to giving rescue 
therapy to a patient, the Medical Director at the Sponsor and the Medical Monitor at the 
Sponsor’s designated Contract Research Organization (CRO) should be informed. 
In situations where the treatments as listed above are given under the protocol defined rescue 
criteria, patients will be discontinued early from randomized treatment (see Section 4.4.2). 
 
EARLY DISCONTINUATION FROM THE TRIAL 
Any patient prematurely discontinuing the trial should perform the EoS/ED assessments. 
EARLY DISCONTINUATION FROM RANDOMIZED TREATMENT 
Patients who discontinue early from randomized treatment within a Treatment Cycle will 
have to complete the End of Treatment (EoT) assessments and complete the remaining visits 
in the current Treatment Cycle, according to the general schedule of assessments (SoA) 
(Table 1). These patients will not receive any further IMP administration during the trial and 
will continue to be followed for safety and disease severity (limited to MG-ADL and QMG) 
as per the SoA for Patients who Discontinued Early from Randomized Treatment (Table 2). 
Patients who discontinue early from randomized treatment in the ITC period will have to 
complete the EoT assessments and then continue into the Safety and Disease Severity 
Follow-up period as per Table 2. 
TEMPORARY INTERRUPTION FROM RANDOMIZED TREATMENT 
A patient that does not need to be discontinued early from randomized treatment might still 
have a temporary interruption from randomized treatment which is defined as a 
discontinuation only from the current Treatment Cycle. Therefore, these patients might still 
be eligible for further additional treatments with IMP within this trial. 
A schematic of the trial design is presented in Figure 1. 
4.2. 
Discussion of Trial Design 
In the current trial, ARGX-113 will be administered in patients with gMG, with the aim to 
evaluate the efficacy, safety, tolerability and quality of life of ARGX-113.  
This trial is designed as a randomized, double-blind, and placebo-controlled trial to 
distinguish the effect of ARGX-113 from other influences such as placebo effect or biased 
observation. The trial consists of a treatment part where all randomized patients will be 
treated with the IMP and a re-treatment part where patients may be re-treated with the IMP 
on an “as needed basis” in subsequent Treatment Cycles. The time between Treatment 
Cycles is based on the duration of the treatment effect and may vary from patient to patient 
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Patients will continue to receive their SoC during the trial irrespective of the treatment they 
receive (ARGX-113 or placebo) which will be administered as an add-on therapy to the SoC. 
It serves as a rational therapeutic approach for IgG-mediated immune diseases such as MG 
by targeting the FcRn-IgG interaction and alleviating autoimmune disease symptoms by 
rapidly clearing pathogenic autoantibodies. 
The chosen primary endpoint in this trial is the percentage of patients who, after the first 
Treatment Cycle, have a decrease of at least 2 points on the total MG-ADL score (compared 
to TC1B) for at least 4 consecutive weeks with the first of these decreases occurring at the 
latest 1 week after the last infusion of the IMP in the active versus placebo group in AChR-
Ab seropositive patients. The MG-ADL is a standardized 8-item patient-reported scale to 
assess MG symptoms and their effects on daily activities and is largely used by Investigators 
in several trials. MG-ADL is a widely used and validated tool to monitor the severity of MG 
and to assess the effect of treatment on the clinical manifestations of the disease. A reduction 
of at least 2 points of the MG-ADL is generally considered clinically meaningful (Wolfe, 
Herbelin et al. 1999; Muppidi, Wolfe et al. 2011). 
All secondary endpoints are complementary to the primary endpoint. These endpoints 
provide more information related to specific aspects of the efficacy. The QMG test is a 
validated and widely used clinical tool to measure disease severity in MG patients. In 
contrast to MG-ADL, which is based on patient reporting, QMG provides quantitative 
assessments of symptoms / signs of the disease based on the Investigator’s assessment 
(Barohn, McIntire et al. 1998; Katzberg, Barnett et al. 2014). 
Both MG AChR-Ab seropositive as well as MG AChR-Ab seronegative patients will be 
included in the trial. AChR-Ab seronegative patients are patients in which AChR-Ab cannot 
be detected in serum using routine laboratory methods. However, there is evidence that in 
these seronegative patients, MG is also driven by other autoantibodies of the Ig class such as 
MuSK, LRP4 or by other so far unidentified autoantibodies to other antigens of the 
neuromuscular junction. In addition, in other cases, the absence of AChR-Ab may be due to 
the insufficient sensitivity of the routine assays which are unable to detect low affinity 
autoantibodies. Therefore, given the mechanism of action of ARGX-113 and the IgG 
pathogenesis of MG in most of the so-called seronegative patients, there is reason to believe 
that, similarly to the AChR-Ab seropositive patients, AChR-Ab seronegative patients will 
also benefit from treatment with ARGX-113. 
The choice of the dose/regimen of ARGX-113 (4 weekly infusions of 10 mg/kg) was made 
because, as observed in a Phase 1 trial in human volunteers, it causes a marked and long-
lasting decrease of IgG level believed to be related to efficacy with only few mild AEs. In the 
same trial, higher doses did not result in significant further reductions of IgG while, at the 
same time, the number of subjects experiencing ARGX-113-related AEs increased. On the 
other hand, a lower dose of 2 mg/kg resulted in substantially less reduction of IgG 
concentrations (2.3-fold difference in maximum IgG decrease). As suggested by the PK/PD 

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modelling, lower doses (e.g., 5 mg/kg) will result in a less marked decrease of the IgG level 
and therefore may result in a less pronounced therapeutic effect. In addition, in a Phase 2 trial 
(ARGX-113-1602) in patients with gMG, the dose/regimen chosen for the current trial 
induced a clinically meaningful improvement on the MG-ADL and QMG scales and, at the 
same time, confirming the acceptable safety profile of the drug. Therefore, the dose of 
10 mg/kg of ARGX-113 administered weekly for 4 weeks seems to provide the best 
benefit/risk ratio and was selected for future trials. 
All efficacy, quality of life and safety assessments used in this trial are standard, i.e., widely 
used and generally recognized as reliable, accurate, and relevant. 
4.3. 
Selection of Trial Population 
4.3.1. 
Inclusion Criteria 
Patients will be randomized in this trial only if they meet all of the following criteria: 
1. 
Patients with the ability to understand the requirements of the trial, provide written 
informed consent, and comply with the trial protocol procedures. 
2. 
Male or female patients aged  18 years. 
3. 
Diagnosis of MG with generalized muscle weakness meeting the clinical criteria for 
diagnosis of MG as defined by the MGFA class II, III, IVa and IVb. 
The confirmation of the diagnosis should be documented and supported by at least 1 of 
the following 3 tests: 
o 
History of abnormal neuromuscular transmission demonstrated by single-fiber 
electromyography or repetitive nerve stimulation, or 
o 
History of positive edrophonium chloride test, or 
o 
Patient has demonstrated improvement in MG signs on oral AChE inhibitors as 
assessed by the treating physician. 
4. 
A total MG-ADL score of  5 points at Screening and Baseline (SEB) with more than 
50% of the total score due to non-ocular symptoms. 
5. 
Patients are required to be on a stable dose of their MG treatment (SoC) prior to 
Screening. The SoC is limited to AChE inhibitors, steroids and NSIDs. For patients 
receiving NSIDs, steroids, and/or AChE inhibitors as concomitant medications the 
following stability dose conditions will apply: 
o 
Non-steroidal immunosuppressive drugs (e.g., azathioprine, methotrexate, 
cyclosporine, tacrolimus, mycophenolate mofetil, and cyclophosphamide): 
treatment initiated at least 6 months prior to Screening and no dose changes in the 
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o 
Steroids: treatment initiated at least 3 months prior to Screening and no dose 
changes in the last month before Screening. 
o 
Acetylcholinesterase inhibitors: stable dose with no dose escalation in the past 
2 weeks before Screening. 
Note: AChE inhibitors must be halted for at least 12 hours consistent with the 
revised manual for the QMG test as recommended by the MGFA, before the 
QMG assessment. 
4.3.2. 
Exclusion Criteria 
Patients will not be randomized in this trial if they meet any of the following criteria: 
1. 
Pregnant and lactating women, and those intending to become pregnant during the trial 
or within 90 days after the last dosing. Women of childbearing potential (see 
DEFINITION OF TERMS) should have a negative serum pregnancy test at Screening 
and a negative urine pregnancy test at Baseline (SEB) prior to administration of IMP.  
Note: Women of childbearing potential should use a highly effective method of 
contraception (i.e., pregnancy rate of less than 1% per year) during the trial and for 
90 days after the last administration of the IMP. They must be on a stable regimen, for 
at least 1 month, of combined estrogen and progestogen hormonal contraception with 
inhibition of ovulation, progestogen-only hormonal contraception associated with 
inhibition of ovulation, intrauterine device (IUD), intrauterine hormone-releasing 
system, bilateral tubal occlusion, vasectomized partner, or agree upon continuous 
abstinence from heterosexual sexual contact. 
2. 
Male patients who are sexually active and do not intend to use effective methods of 
contraception (as mentioned above) during the trial or within 90 days after the last 
dosing or male patients who plan to donate sperm during the trial or within 90 days 
after the last dosing. 
Note: Sterilized male patients who have had vasectomy with documented aspermia 
post-procedure, or male patients who have a partner of non-childbearing potential, can 
be included. 
3. 
MGFA Class I and V patients. 
4. 
Patients with worsening muscle weakness secondary to concurrent infections or 
medications (aminoglycosides, fluoroquinolones, beta-blockers, etc.). 
5. 
Patients with known seropositivity or who test positive for an active viral infection at 
Screening with: 
o 
Hepatitis B Virus (HBV) (except patients who are seropositive because of HBV 
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o 
Hepatitis C Virus (HCV) 
o 
Human Immunodeficiency Virus (HIV) 
6. 
Patients with any known severe bacterial, viral or fungal infection or any major episode 
of infection that required hospitalization or injectable antimicrobial therapy in the last 
8 weeks prior to Screening.  
7. 
Patients with known autoimmune disease other than MG (for example autoimmune 
thyroiditis, rheumatoid arthritis…) that would interfere with an accurate assessment of 
clinical symptoms. 
8. 
Patients with total IgG level < 6 g/L at Screening. 
9. 
Patients with documentation of a lack of clinical response to PLEX. 
10. 
Use of investigational drug within 3 months or 5 half-lives of the drug (whichever is 
longer) prior to Screening. 
11. 
Immunoglobulins given by IV (IVIg), subcutaneous or intramuscular route, or PLEX, 
each within 1 month prior to Screening. 
12. 
Patients who have a history of malignancy, including malignant thymoma, or 
myeloproliferative or lymphoproliferative disorders, unless deemed cured by adequate 
treatment with no evidence of recurrence for  3 years before Screening. Patients with 
completely excised non-melanoma skin cancer (such as basal cell carcinoma or 
squamous cell carcinoma) or cervical carcinoma in situ would be permitted at any time. 
13. 
Thymectomy when performed < 3 months prior to Screening or planned to be 
performed during the trial period. 
14. 
Patients with clinical evidence of other significant serious disease or patients who 
underwent a recent major surgery, which could confound the results of the trial or put 
the patient at undue risk. Patients with renal/hepatic function impairment can be 
included. 
15. 
Patients who previously participated in a clinical trial with ARGX-113. 
16. 
Patients who received a vaccination (e.g., influenza vaccine) within the last 4 weeks prior 
to Screening. 
17. 
Use of any monoclonal antibody, such as rituximab and eculizumab, within 6 months 
prior to first dosing. 
4.4. 
Early Discontinuation 
The criteria for screening and randomization are to be followed explicitly. If it is noted that a 
patient who does not meet one or more of the inclusion and/or meets one or more of the 

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exclusion criteria is inadvertently randomized and dosed, the Medical Monitor at Sponsor’s 
Designated CRO and the Sponsor’s Medical Director must be contacted immediately. 
4.4.1. 
Early Discontinuation from Trial 
Early discontinuation from the trial is defined as the permanent cessation of further 
participation in the trial prior to its planned completion. Patients must be discontinued early 
from the trial and complete the EoS/ED visit if: 
x 
they withdraw their consent 
x 
the randomization code is broken prematurely by the Investigator or his/her staff 
x 
the Investigator, after discussion with the Sponsor’s Medical Director, deems it is in the 
patient’s best interest. 
All patients are free to withdraw consent from participation in the trial at any time, for any 
reason, specified or unspecified, and without prejudice to further treatment. Prior to actual 
withdrawal of consent, an effort should be made to perform a final set of assessments as per 
EoS/ED visit in the general SoA (Table 1). Investigators will make and document all efforts 
made to contact those patients who do not return for scheduled visits. 
The reason for early discontinuation from the trial will be clearly documented by the 
Investigator. 
4.4.2. 
Early Discontinuation from Randomized Treatment 
Early discontinuation from randomized treatment means that the patient stops receiving the 
ongoing treatment and will never start a new Treatment Cycle for the entire duration of the 
trial; however informed consent is not withdrawn. These patients will continue to be 
followed up in the trial according to the SoA for Patients who Discontinued Early from 
Randomized Treatment (Table 2). 
Patients must be discontinued early from randomized treatment if: 
x 
Patient is pregnant 
x 
Patients receives rescue therapy  
x 
Patient develops an SAE that is likely to result in a life-threatening situation or pose a 
serious safety risk. 
x 
Prohibited medication is taken (see Section 6.8.1) 
Patients might discontinue early from randomized treatment: 

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x 
In case the patient has clinical evidence of bacterial, viral or fungal disease or any other 
significant disease which could confound the results of the trial or put the patient at 
undue risk. In this situation, decision on whether or not to discontinue patients early from 
randomized treatment will depend on the evaluation on a case by case basis. Patients 
who, after evaluation of the above situations, are not discontinued from randomized 
treatment, may have a temporary interruption from randomized treatment (see 
Section 4.4.3). 
Patients who discontinue early from randomized treatment within a Treatment Cycle will 
have to complete the EoT assessments and complete the remaining visits in the current 
Treatment Cycle, according to the general SoA (Table 1). These patients will not receive any 
further IMP administration during the trial and will continue to be followed for safety and 
disease severity (limited to MG-ADL and QMG) as per the SoA for Patients who 
Discontinued Early from Randomized Treatment (Table 2). 
Patients who discontinue early from randomized treatment in the ITC period will have to 
complete the EoT assessments and then continue into the Safety and Disease Severity 
Follow-up period as per Table 2. 
4.4.3. 
Temporary Interruption from Randomized Treatment 
A patient that does not need to be discontinued early from randomized treatment might still 
have a temporary interruption from randomized treatment. A temporary interruption from 
randomized treatment is defined as a discontinuation of the current Treatment Cycle but the 
patient might still be eligible for further additional treatments with IMP within this trial. 
Patients for whom treatment is interrupted will have to complete the current Treatment Cycle 
and will continue the trial as per general SoA (Table 1).  
4.4.4. 
Missed Doses 
Patients who miss one, two or three infusions per Treatment Cycle will stay in the trial and 
will follow the assessments as per general SoA (Table 1). These patients may be eligible for 
further Treatment Cycles during the trial. 
4.5. 
Roll-Over to Follow-on Trial 
At EoS, patients will be offered the option to roll over into a long-term, single-arm, open-
label follow-on trial (ARGX-113-1705) where they will be treated with ARGX-113 
(10 mg/kg of body weight) on an “as needed basis”.  
Patients who need re-treatment but cannot complete a Treatment Cycle within the time frame 
of the ARGX-113-1704 trial (i.e., require re-treatment after Day 127), may roll over 
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Patients who discontinue early from trial ARGX-113-1704, will not be offered the option to 
roll over in the follow-on trial.  
Patients who discontinue early from randomized treatment for rescue or pregnancy reasons or 
for an SAE that is likely to result in a life-threatening situation or pose a serious safety risk 
will also not be offered the option to roll over to the follow-on trial. Patients who discontinue 
early from randomized treatment for other reasons and patients who have a temporary 
interruption from randomized treatment may be offered the option to roll over to the follow-
on trial. 
4.6. 
Protocol Deviations 
The Investigator should not implement any deviation from, or changes of the protocol 
without agreement by 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 trial patients, or when the change involves only logistical or 
administrative aspects of the trial (e.g., change of telephone numbers, …). The Investigator 
(or delegate) should document and explain any deviation from the approved protocol. 
Planned protocol exemptions or waivers will not be approved by the Sponsor. 
4.7. 
Screen Failures, Rescreening, and Retesting 
Evaluations at Screening and confirmation at Visit 1 will be used to determine the eligibility 
of each patient for randomization at SEB (Visit 1). Patients who fail to meet the eligibility 
criteria will be considered screen failures. 
Patients may be rescreened (i.e., redoing the full assessments as per general SoA, Table 1) or 
retested once (i.e., redoing 1 assessment) after Sponsor’s written approval. 
Examples of conditions under which rescreening may be considered include the following: 
x 
Patients who required treatment for an acute illness (e.g., a urinary tract infection) or 
have a chronic medical problem (e.g., uncontrolled hypertension) may be rescreened 
once the illness resolved or the medical problem stabilized.  
Examples of conditions under which retesting may be considered include the following: 
x 
Patients who have clinical laboratory tests value meeting one or more exclusion criteria 
which are not in line with the medical history and clinical evaluation of the patient, may 
be retested to confirm the value of the tests, if still allowed within the Screening period. 
If not feasible, the patient should be rescreened. 

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4.8. 
Early Termination of Trial or Site 
The trial may be terminated at any time by the Sponsor for safety concerns due to serious 
adverse events (SAEs), inability to achieve the recruitment target within reasonable time or if 
in the Sponsor's judgment, there are no further benefits to be expected from the trial. In such 
a case, the Sponsor or delegate will inform the trial Investigators, institutions, and all 
regulatory authorities. 
The trial can also be terminated by the Regulatory Authority for any reason or if 
recommended by the DSMB, or at a site level by the IRB/IEC. The Sponsor may close 
individual trial sites prematurely for reasons such as poor protocol compliance or 
unsatisfactory recruitment of patients. 
4.9. 
End of Trial definition 
End of trial is defined as last patient last visit. 
5. 
TRIAL PROCEDURES 
Every effort should be made to ensure that the protocol-required tests and procedures are 
completed as described. When a protocol-required procedure cannot be performed, the 
Investigator will document the reason and any corrective and preventive actions that he/she 
has taken to ensure that the normal processes are adhered to in source documents. The trial 
team should be informed of these incidents in a timely manner. 
Patients should be seen for all visits on the designated days or as closely as possible to the 
original planned visit schedule. There is a permissible window of ±1 day for Treatment Cycle 
visits (Visit 1 to Visit 9) and of ± 2 days for ITC visits. Every effort should be made to 
schedule every visit on the exact day (which is relative to the Baseline visit [SEB or TCnB]) 
within the window as described in the general SoA (Table 1). 
Each Treatment Cycle consists of 9 weekly visits over a period of 8 weeks, consisting of a 
Treatment period of 3 weeks (4 weekly infusions) and a FU period of 5 weeks. 
The SEB and TC[1]B will both be set at randomization (Visit 1), whilst the Baseline of each 
subsequent Treatment Cycle (TCnB) will be set at Visit 1 of each corresponding Treatment 
Cycle. 
At all visits, the efficacy and quality of life assessments should be performed first, prior to 
any other trial-specific procedure with the only exception of obtaining informed consent at 
Screening and the weight assessment (if applicable). The MG-ADL scale needs to be 
performed prior to all other efficacy or quality of life assessments (QMG, MGC, EuroQoL 
5 Dimensions 5 Levels [EQ-5D-5L] and MG-QoL15r). Acetylcholinesterase inhibitors must 
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As from signature of informed consent until EoS, all AEs that occur and all concomitant 
medications, whether allowed or not, that are taken during the trial are to be recorded on the 
appropriate pages in the electronic Case Report Form (eCRF). 
Patients who discontinue early from randomized treatment, after they have completed the 
EoT assessments and, if applicable, the remaining visits of the current Treatment Cycle, will 
return every month (30 ± 3 days) for Follow-up visits until Day 182 as per SoA for Patients 
who Discontinued Early from Randomized Treatment (Table 2). These patients will then 
continue in the trial to be followed for safety and disease severity (limited to MG-ADL and 
QMG). 
5.1. 
Informed Consent 
The patient must sign the informed consent form (ICF) prior to any trial-related assessment. 
Prior to signing the ICF, trial patients will be instructed not to participate in any other clinical 
trial that involves an intervention or collection of data until the completion of the current 
trial. 
Any patient who provides informed consent is being assigned a patient identification number. 
5.2. 
Screening 
After informed consent has been obtained, patients will be screened at the site for eligibility 
based on the inclusion and exclusion criteria defined in Sections 4.3.1 and 4.3.2, respectively.  
In addition to obtaining written informed consent, the following assessments will be 
performed at Screening: 
x 
Assign patient identification number. 
x 
Eligibility evaluation (review of in- and exclusion criteria). 
x 
Clinically relevant medical and surgical history, clinically relevant prior treatment and 
all concomitant medications (see Sections 7.2.5 and 6.8). 
x 
Demographic characteristics (date of birth, sex, race, and ethnicity, per national 
regulations). 
x 
The efficacy assessment MG-ADL should be done prior to any other trial-specific 
assessment at Screening, except for obtaining informed consent and the weight 
assessment. A total MG-ADL score  5 with more than 50% of this total score attributed 
to non-ocular symptoms should be met at Screening. 
x 
Suicidal ideation and behavior will be assessed via a targeted question based on the 
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x 
Complete physical examination, including at a minimum: general appearance, skin, 
lymph nodes, musculoskeletal/extremities, abdomen, cardiovascular, respiratory, and 
neurological systems. 
x 
Height and weight. 
x 
Vital signs (supine blood pressure, heart rate, body temperature). It is recommended that 
the method used to measure body temperature at Screening is maintained throughout the 
trial for each patient. 
x 
Electrocardiogram (ECG) (heart rate, PR, QT and QRS interval). 
x 
Clinical laboratory tests (see Appendix 6 for an overview of the clinical laboratory tests 
that will be assessed). In addition, total IgG will be assessed at central lab for defining 
eligibility. Patients need to be fasted at least 8 hours prior to sampling. 
x 
Sampling to determine the AChR/MuSK-Ab serotype (seronegative or seropositive) of 
the patient. In case the AChR-Ab result is not available in time (i.e. within the 2 weeks 
screening window), the screening window can be enlarged on an ad-hoc base with 
maximum 5 calendar days.  
x 
Urinalysis. 
x 
Serum pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS). 
x 
Viral tests (see Appendix 6 for more details). 
x 
Assess AEs if any. 
5.3. 
Randomization 
The results of all Screening procedures required to determine eligibility must be available 
prior to randomization at Visit 1 of the first Treatment Cycle (TC1B). 
The following assessments should be performed at Visit 1 of the first Treatment Cycle 
(randomization visit): 
x 
Eligibility evaluation (review of specified in- and exclusion criteria).(*) 
x 
Efficacy and quality of life assessments should be performed prior to any other trial-
specific assessment, except for the weight assessment (if applicable), with the MG-ADL 
scale to be performed prior to all other efficacy or quality of life assessments (QMG, 
MGC, EQ-5D-5L and MG-QoL15r). A total MG-ADL score  5 with more than 50% of 
this total score attributed to non-ocular symptoms should be met at Visit 1 (SEB). If the 
total MG-ADL score differs from the one at Screening, the total score at SEB will be 
taken into account for the analyses.(*) 

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x 
Suicidality assessment.(*) 
x 
Physical examination.(*) 
x 
Weight will only be measured in case there is an obvious weight change compared to the 
last weight assessment.(*) 
x 
Vital signs.(*) 
x 
Electrocardiogram.(*) 
x 
Clinical laboratory tests. Patients need to be fasted at least 8 hours prior to sampling.(*) 
x 
Urinalysis.(*) 
x 
Urine pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS).(*) 
x 
Pharmacodynamic biomarkers (anti-AChR antibodies in AChR-Ab seropositive patients 
only, total IgG and subtypes [IgG1, IgG2, IgG3 and IgG4], and anti-MuSK antibodies in 
MuSK-Ab seropositive patients only).(*) 
x 
Anti-drug antibodies (ADA).(*) 
x 
Pharmacokinetic sampling within 1 hour prior to start of infusion(*) and within 1 hour 
after the end of infusion. 
x 
Administration of the IMP (ARGX-113 or placebo) as an IV infusion over a period of 
1 hour. Patients will remain at the site for at least 1 hour following the end of the 
infusion for safety monitoring based on the patient’s clinical status. 
x 
Review of concomitant medication. 
x 
Assess AEs if any. 
(*) These assessments should be performed prior to administration of the IMP (pre-dose). 
Randomization should be performed as soon as possible after Screening in approximately 
2 weeks with a possible ad-hoc extension of maximum 5 calendar days in case of non-
availability of AchR AB status, however only after confirmation of eligibility of the patient. 
If a patient meets all the trial eligibility criteria and after approval from the Sponsor, he/she 
will be stratified via Interactive Response Technology (IRT) according to 3 stratification 
factors: Japanese vs. non-Japanese patients, AChR-Ab status (seropositive vs. seronegative) 
and SoC (patients on NSIDs vs. patients not on NSIDs). Within each stratum, the patient will 
be randomized (1:1) via IRT to be treated with either placebo or ARGX-113, on top of their 
current SoC. A maximum of 20% AChR-Ab seronegative patients will be allowed in the 
trial. If the patient is not eligible, then he/she should be recorded as a screen failure in the 
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5.4. 
Treatment Cycle 
5.4.1. 
Treatment Period 
After randomization (including Visit 1 of the first Treatment Cycle; see Section 5.3), the 
following assessments will be performed at Visit 2 to Visit 4 of the first Treatment Cycle and 
at Visit 1 to Visit 4 of the subsequent Treatment Cycles.  
x 
Efficacy and quality of life assessments should be performed prior to any other trial-
specific assessment, except for the weight assessment (if applicable), with the MG-ADL 
scale to be performed prior to all other efficacy or quality of life assessments (QMG, 
MGC, EQ-5D-5L and MG-QoL15r).(*) 
x 
Suicidality assessment.(*) 
x 
Physical examination.(*) 
x 
Weight will only be measured in case there is an obvious weight change compared to the 
last weight assessment.(*) 
x 
Vital signs.(*) 
x 
Electrocardiogram.(*) 
x 
Clinical laboratory tests. Patients need to be fasted at least 8 hours prior to sampling.(*) 
x 
Urinalysis.(*) 
x 
Urine pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS).(*) 
x 
Pharmacodynamic biomarkers (anti-AChR antibodies in AChR-Ab seropositive patients 
only, total IgG and subtypes [IgG1, IgG2, IgG3 and IgG4], and anti-MuSK antibodies in 
MuSK-Ab seropositive patients only).(*) 
x 
Anti-drug antibodies at Visit 4 of the first Treatment Cycle. As from the second 
Treatment Cycle onwards, samples for ADA will only be taken at Visit 1 of the 
corresponding Treatment Period.(*) 
x 
Pharmacokinetic sampling within 1 hour prior to start of infusion(*) and within 1 hour 
after the end of infusion. 
x 
Administration of the IMP (ARGX-113 or placebo) as an IV infusion over a period of 
1 hour. Patients will remain at the site for at least 1 hour following the end of the 
infusion for safety monitoring based on the patient’s clinical status.  
x 
Review of concomitant medication and rescue therapy.(*) 
x 
Assess AEs if any. 

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(*) These assessments should be performed prior to administration of the IMP (pre-dose). 
At Visit 1 of each subsequent Treatment Cycle, the conditions for re-treatment will be 
checked before administration of the IMP (see Section 4.1). 
Patients may not receive re-treatment with ARGX-113 or placebo if, at the time of re-
treatment, patients have clinical evidence of bacterial, viral or fungal disease, or any other 
significant disease which could confound the results of the trial or put patients at undue risk. 
Patients who are in need of an additional treatment but who are not eligible to receive re-
treatment for reasons listed here will remain in the trial and will be discontinued early from 
randomized treatment to receive appropriate alternative MG treatment. 
For the entire duration of the trial, a change in the type or dose/regimen of SoC (replacing, 
adding or removing SoC, or adjustment of the SoC dose and/or frequency) is not allowed. 
5.4.2. 
Follow-up Period 
The FU period within a Treatment Cycle will include weekly assessments starting at Visit 5 
up to Visit 9 of the corresponding Treatment Cycle.  
The following assessments will be performed: 
x 
Efficacy and quality of life assessments should be performed prior to any other trial-
specific assessment, except for the weight assessment (if applicable), with the MG-ADL 
scale to be performed prior to all other efficacy or quality of life assessments (QMG, 
MGC, EQ-5D-5L and MG-QoL15r). 
x 
Suicidality assessment. 
x 
Physical examination. 
x 
Weight will only be measured in case there is an obvious weight change compared to the 
last weight assessment. 
x 
Vital signs. 
x 
Electrocardiogram. 
x 
Clinical laboratory tests. Patients need to be fasted at least 8 hours prior to sampling. 
x 
Urinalysis. 
x 
Urine pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS). 
x 
Pharmacodynamic biomarkers (anti-AChR antibodies in AChR-Ab seropositive patients 
only, total IgG and subtypes [IgG1, IgG2, IgG3 and IgG4], and anti-MuSK antibodies in 
MuSK-Ab seropositive patients only). 

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x 
Anti-drug antibodies at Visits 6 and 9 from the first Treatment Cycle. As from the 
second Treatment Cycle onwards, samples for ADA will only be taken at Visit 9 of the 
corresponding FU period. 
x 
Pharmacokinetic sampling (only at Visits 5 and 6). 
x 
Review of concomitant medication and rescue therapy. 
x 
Assess AEs if any. 
5.5. 
Inter Treatment Cycle Period 
The ITC period will consist of visits every 2 weeks, starting 14 days (± 2 days) from the last 
visit of the previous Treatment Cycle. 
At each ITCnV, an evaluation of the need for re-treatment should be done. In case the patient 
is not in need of re-treatment, assessments for ITCnV should be performed as listed below 
and per general SoA (Table 1). However, in case the evaluation shows that the patient is in 
need of re-treatment and is also eligible for re-treatment, the assessments according to TCnV1 
are to be performed instead. 
The following assessments will be performed: 
x 
Efficacy and quality of life assessments should be performed prior to any other trial-
specific assessment, except for the weight assessment (if applicable), with the MG-ADL 
scale to be performed prior to all other efficacy or quality of life assessments (QMG, 
MGC, EQ-5D-5L and MG-QoL15r). 
x 
Suicidality assessment. 
x 
Physical examination. 
x 
Weight will only be measured in case there is an obvious weight change compared to the 
last weight assessment. 
x 
Vital signs. 
x 
Electrocardiogram. 
x 
Clinical laboratory tests. Patients need to be fasted at least 8 hours prior to sampling. 
x 
Urinalysis. 
x 
Urine pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS). 
x 
Pharmacodynamic biomarkers (anti-AChR antibodies in AChR-Ab seropositive patients 
only, total IgG and subtypes [IgG1, IgG2, IgG3 and IgG4], and anti-MuSK antibodies in 
MuSK-Ab seropositive patients only). 

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x 
Review of concomitant medication and rescue therapy. 
x 
Assess AEs if any. 
5.6. 
End of Treatment 
Patients who do not discontinue early from randomized treatment will perform the 
assessments on Visit 4 of the last Treatment Cycle as indicated in the general SoA (Table 1) 
(see Section 5.4.1). 
For patients who discontinue early from randomized treatment, the assessments will 
depend on the visit at which it was decided that the patient had to discontinue early from 
randomized treatment. 
Patients who discontinue early from randomized treatment within a Treatment Cycle will 
perform the planned assessments of that corresponding visit (see Section 5.4), and complete 
the remaining visits in the current Treatment Cycle according to the general SoA (Table 1). 
These patients will not receive any further IMP administration during the trial and will 
continue to be followed for safety and disease severity (limited to MG-ADL and QMG) as 
per the SoA for Patients who Discontinued Early from Randomized Treatment (Table 2). 
Patients who discontinue early from randomized treatment in the ITC period will perform 
the planned assessments of the current ITC visit as per Table 1 (see Section 5.5), prior to 
entering the Safety and Disease Severity Follow-up period as per SoA for Patients who 
Discontinued Early from Randomized Treatment (Table 2). 
5.7. 
Safety and Disease Severity Follow-up Period for Patients who 
Discontinued Early from Randomized Treatment 
After the decision of early discontinuation from randomized treatment, and after the patient 
completed either the current Treatment Cycle, or the EoT assessments of the current ITC 
visit if the decision was made in the ITC period, the patient should return every month for FU 
visits until Day 182 as per SoA for Patients who Discontinued Early from Randomized 
Treatment (Table 2). 
The following assessments will be performed: 
x 
Assessments of disease severity. MG-ADL scale needs to be performed prior to the 
QMG scale and prior to any other assessments. 
x 
Urine pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS). 
x 
Review of concomitant medication and rescue therapy. 
x 
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5.8. 
End of Study and Early Discontinuation (EoS/ED) Visit 
In case of early discontinuation from the trial, the same assessments as scheduled for EoS 
(Day 182) must be performed as follows: 
x 
Efficacy and quality of life assessments should be performed prior to any other trial-
specific assessment, except for the weight assessment (if applicable), with the MG-ADL 
scale to be performed prior to all other efficacy or quality of life assessments (QMG, 
MGC(*), EQ-5D-5L(*) and MG-QoL15r(*)). 
x 
Suicidality assessment.(*) 
x 
Physical examination.(*) 
x 
Weight.(*) 
x 
Vital signs.(*) 
x 
Electrocardiogram.(*) 
x 
Clinical laboratory tests. Patients need to be fasted at least 8 hours prior to sampling.(*) 
x 
Urinalysis.(*) 
x 
Urine pregnancy test (only for women of childbearing potential, see DEFINITION OF 
TERMS). 
x 
Pharmacodynamic biomarkers (anti-AChR antibodies in AChR-Ab seropositive patients 
only, total IgG and subtypes [IgG1, IgG2, IgG3 and IgG4], and anti-MuSK antibodies in 
MuSK-Ab seropositive patients only).(*) 
x 
Anti-drug antibodies.(*) 
x 
Pharmacokinetic sampling.(*) 
x 
Review of concomitant medication and rescue therapy. 
x 
Assess AEs if any. 
(*) Only applicable for patients following Table 1. 
5.9. 
Unscheduled Visit 
It is at the Investigator’s discretion, or on request of the patient, to initiate an unscheduled 
(UNS) visit, if deemed necessary for the patient’s safety and well-being. All such visits will 
be documented in the eCRF with any additional required documentation based on the nature 
of UNS visit. 

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6. 
TRIAL TREATMENTS 
6.1. 
Treatments Administered 
ARGX-113 or matching placebo will be administered weekly for 3 weeks (4 infusions) as an 
IV infusion (total volume of 125 mL and a dose of 10 mg/kg of body weight) at Visits 1, 2, 3, 
and 4 of each Treatment Cycle. A variation of ± 10% of the amount, as planned per protocol, 
of ARGX-113 administered to the patient, will not be considered an overdose/underdose. In 
case of a significant (> 10%) change in body weight, the dose will be recalculated. 
Although ARGX-113 was administered over a period of 2 hours in all the other clinical trials 
conducted so far, in this trial, for patient’s convenience and because no safety concerns are 
anticipated based on observations in the other trials, ARGX-113 will be administered over a 
period of 1 hour. Please refer also to the IB, Section 6.3. 
Details on infusion rate and time will be given in the IMP management manual (pharmacy 
manual). 
6.2. 
Identity of Investigational Medicinal Products 
The IMP (ARGX-113 or placebo) will be supplied to the Investigator or designated site staff 
at the investigational site, by and under the responsibility of the Sponsor’s designated IMP 
supply vendor, who will also provide the Investigator with certificate of analysis, certificate 
of conformity and European Union Qualified Person (EU QP) release documents. 
The IMP will be manufactured in accordance with Good Manufacturing Practice (GMP) 
regulations. Detailed instructions on IMP management on site (including preparation of the 
IMP) will be included in the IMP management manual (pharmacy manual). 
The dose will be 10 mg/kg (total dose per IMP infusion is capped at 1200 mg for patients 
with body weight  120 kg). 
CCI

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6.3. 
Packaging and Labeling 
The IMP will be labeled and secondary packed in accordance to local laws and regulatory 
requirements. 
6.4. 
Storage of Investigational Medicinal Products 
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 with access limited to 
those individuals authorized to dispense the IMP, and maintained within the appropriate 
temperature ranges. The IMP must be stored as specified at delivery and in the original 
packaging. The placebo and ARGX-113 labeling and packaging will be identical. 
The IMP must be stored refrigerated (2-8°C or 35-46°F) in their secondary packaging, should 
not be exposed to freezing temperatures, should not be shaken, and should be protected from 
direct sunlight during storage at the clinical site. 
Further requirements on temperature logging during storage and information on how to 
handle temperature excursions can be found in the IMP management manual (pharmacy 
manual). 
6.5. 
Method of Assigning Patients to Treatment Group 
Once the patient has provided informed consent and eligibility has been confirmed by the 
Sponsor, patients will be stratified according to 3 stratification factors: Japanese vs. non-
Japanese patient, AChR-Ab status (seropositive vs. seronegative) and SoC (patients on 
NSIDs vs. patients not on NSIDs) and randomized at Visit 1 of the first Treatment Cycle via 
IRT within each stratum to be treated with either ARGX-113 or placebo, on top of their 
current SoC. A maximum of 20% AChR-Ab seronegative patients will be allowed in the 
trial. A patient identification number will be allocated, and upon confirmation of eligibility at 
Visit 1 of the first Treatment Cycle, the site, after confirmation by the Sponsor, will 
randomize the patient via IRT, which will assign a patient randomization number. 
Definition: A Japanese patient is defined as a patient whose parents and four 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. 
 
The randomization code will be held by the IRT vendor. Patients will be randomized in a 1:1 
ratio to ARGX-113 or placebo. No blinded trial team members from the Sponsor or the 
Sponsor’s designated blinded CRO team will have access to this randomization code until 
after final database lock. 

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6.6. 
Timing of Dose for Each Patient 
ARGX-113 or placebo will be administered IV over a period of 1 hour as 4 weekly infusions 
at Visits 1, 2, 3, and 4 of each Treatment Cycle. Patients will be asked to remain at the site 
for a minimum of 1 hour after the end of infusion as part of routine safety monitoring at 
Visits 1, 2, 3, and 4 of each Treatment Cycle. 
6.7. 
Blinding 
This is a randomized, double-blind, placebo-controlled trial with limited access to the 
randomization code. ARGX-113 and placebo will be identical in physical appearance. The 
treatment that each patient receives will not be disclosed to the Investigator, investigational 
site staff, patient, Sponsor, and the Sponsor’s designated CRO. The trial will only be 
unblinded following the database lock, except in the situation of unblinding for safety 
reasons. 
Emergency Unblinding Procedure 
Code-breaking and unblinding in the event of medical emergencies can be done by the 
Investigator via IRT, which will be accessible 24 hours per day/7 days per week. 
Unblinding by the Investigator should occur only in the event of an AE for which it is 
necessary to know the randomized treatment to determine an appropriate course of therapy 
for the patient. The Investigator should first discuss options immediately with the Medical 
Monitor and Sponsor if possible with due consideration of the safety of the patient. If the 
Investigator must identify the treatment assignment of an individual patient, the Principal 
Investigator/Sub-Investigator is to contact the IRT.  
Patients for whom the code has been broken by the Investigator will have to be discontinued 
from the trial and all efforts must be made to conduct the ED visit. 
Pertinent information regarding the circumstances of unblinding of a patient’s treatment code 
must be documented in the patient’s source documents and eCRFs. 
6.8. 
Prior Treatments and Concomitant Medications 
Clinically relevant prior treatments received by the patient including (1) previous MG 
treatments (including SoC) with patient’s response and reason for changing treatment/dose in 
the last 12 months and (2) non-MG treatment in the last 6 months must be recorded in the 
eCRFs. Information should include start and stop dates and tick box for those continuing as 
concomitant medication. 
Vaccines (except for live/live-attenuated vaccines) will be allowed during the trial when 
administered at least 48 hours pre-infusion or 48 hours post-infusion of IMP. 
All concomitant medications whether allowed or not must be recorded in the eCRFs. 

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6.8.1. 
Prohibited Medications during the Trial 
The following medications or treatments will lead to discontinuation from randomized 
treatment: 
x 
Any IgG therapy 
x 
A change in the type or dose/regimen of SoC (replacing, adding or removing SoC, or 
adjustment of the SoC dose and/or frequency), even if used for indications other than 
MG 
x 
Any monoclonal antibody for immunomodulation 
x 
Live/live-attenuated vaccines 
x 
Rescue therapy when used in patients who meet the criteria to be rescued 
x 
Use of PLEX or immunoadsorption more than once during study period 
6.8.2. 
Rescue Therapy 
Rescue therapy is permitted for patients experiencing protocol-defined MG clinical 
deterioration AND if in addition the treating physician believes that the patient’s health is in 
jeopardy if rescue therapy is not given. An MG clinical deterioration permitting rescue 
therapy to be given is defined as a patient experiencing at least one of the following: (1) new 
or worsening of respiratory / bulbar symptoms or (2) at least 2-point increase of individual 
non-ocular MG-ADL items. Rescue therapy will be limited to PLEX, IVIg, 
immunoadsorption or use of a new type of corticosteroid or an increased dose of the current 
corticosteroids used as stand-alone therapy or in combination. The type of rescue therapy 
used should be documented. 
In case a patient needs rescue therapy according to the treating Investigator, the Medical 
Director at the Sponsor should be informed in addition to the Medical Monitor at the 
Sponsor’s designated CRO; whenever possible prior to actual implementation of the rescue 
therapy. 
In situations where the treatments as listed above are given under the protocol defined rescue criteria, 
patients will be discontinued early from randomized treatment. 
6.9. 
Medical Care of Patients after End of Study 
After a patient has completed the trial and will not roll over into the follow-on trial 
ARGX-113-1705, or has withdrawn/discontinued early, usual treatment will be administered, 
if required, in accordance with the trial site’s SoC and generally accepted medical practice 
depending on the patient’s individual needs. The Sponsor will not provide any additional care 
to these patients neither will the IMP be provided on a compassionate use program. 

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6.10. 
Treatment Compliance 
The Investigator should promote treatment compliance by stating that compliance is 
necessary for the patient’s safety and the validity of the trial. The prescribed dose, timing, 
and mode of administration may not be changed. All dates and start and end time of IMP 
administration and any deviations from the intended regimen must be recorded. 
6.11. 
Handling Missed Doses of the Investigational Medicinal Product 
Patients will receive 4 weekly IV infusions of IMP at a dose of 10 mg/kg over a period of 
1 hour during each Treatment Cycle. 
All efforts will be done to ensure that the patient receives the 4 administrations of IMP within 
the allowed time windows. However, if a patient misses 1 or more doses in any Treatment 
Cycle, the patient will not be discontinued early from the trial or from further randomized 
treatment and will complete all further visits and assessments according to the general SoA 
(Table 1). This patient may be eligible for further Treatment Cycles during the trial. 
In case a dose needs to be delayed for more than 3days, the dosing should be skipped to 
ensure two consecutive doses are given with an interval of at least 3 days. 
6.12. 
Accountability of Investigational Medicinal Product 
Detailed instructions on accountability of the IMP will be included in the IMP management 
manual (pharmacy manual). 
6.13. 
Storage of Blood Samples in the Trial 
Any remaining samples after the analysis per protocol has been completed may be stored for 
up to 15 years for future additional research to address any scientific questions related to 
ARGX-113 or MG, unless this would not be allowed according to local regulations or the 
patient would not agree. 
7. 
TRIAL ASSESSMENTS 
7.1. 
Efficacy and Quality of Life 
Efficacy assessments will be assessed using MG-ADL, QMG, and MGC, and quality of life 
will be measured using MG-QoL15r and EQ-5D-5L. All these assessments have to be 
performed pre-dose on all IMP infusion days and following the order specified in the general 
SoA (Table 1), and prior to any other assessment at each visit except for the assessment of 
weight (if applicable) and signing of the ICF at the Screening visit. 
The MG-ADL, QMG, and MGC assessments for a given patient are preferentially assessed 
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For patients who are unable to read and write, the patient questionnaires MG-QoL15r and 
EQ-5D-5L can be completed by a caregiver. In that case, the caregiver should read out loud 
the questions (without given any personal interpretation or explanation to the patient) and 
complete the exact answer as given by the patient. 
7.1.1. 
Myasthenia Gravis-Activities of Daily Living 
The MG-ADL is an 8-item patient-reported scale (Appendix 1) to assess MG symptoms and 
their effects on daily activities. It evaluates the capacity to perform different activities of 
daily living such as talking, chewing, swallowing, breathing, brushing the teeth/combing the 
hair, or arising from the chair and it also assesses double vision and eyelid droop. It is a 
discrete quantitative variable in which the 8 items are rated from 0 to 3 and the total score 
can point from 0 to 24, with higher total scores indicating more impairment. The assessments 
to be performed using MG-ADL (Appendix 1) do not require any equipment to assess MG 
symptoms and their effects on daily activities. The scoring of MG-ADL should be performed 
by a trained and certified evaluator. 
7.1.2. 
Quantitative Myasthenia Gravis 
The QMG quantifies disease severity based on impairments of body functions and structures 
as defined by the International Classification of Functioning, Disability and Health 
(WHO 2001). 
The QMG consists of 13 items (Appendix 2) that assess ocular, bulbar, and limb function. 
Out of the 13 items, 6 are timed tests of endurance measured in seconds. Each item has a 
possible score from 0-3. The total possible score is 39, where higher total scores indicate 
more severe impairments. It is based on quantitative testing of specific muscle groups to 
assess limb function. It requires minimal equipment such as spirometer, mouthpieces that fit 
the spirometer, nose clips, stopwatch, cups and water for swallowing tests, goniometer, 
dynamometer, and is based on the trained rater’s examination. The scoring of QMG should 
be performed by a trained evaluator. 
7.1.3. 
Myasthenia Gravis Composite 
The MGC has 10 items (Appendix 3) combining a trained rater’s examination and patient 
reported outcomes. The 2 ocular items are derived from QMG. It has 3 items on muscle 
strength (deltoids, hip flexors, and neck flexors or extensors) and 4 items on bulbar function 
(swallowing, chewing, breathing, and speech functions), based on the clinical history. Each 
item is scored on an ordinal scale with 4 possible categories, but the items are weighted, 
whereby bulbar impairments weigh more than ocular ones. The impairments that need to be 
examined by the Investigator include ptosis or upward gaze, double vision, eye closure, neck 
flexion, shoulder abduction, and hip flexion. The patient reported outcomes under MGC are 
talking, chewing, swallowing, and breathing. The maximum total possible score is 50, with 

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higher total scores reflecting more severe impairments. The scoring of MGC should be 
performed by a trained evaluator. 
7.1.4. 
15-Item Quality of Life Scale for Myasthenia Gravis 
The MG-QoL15r (Appendix 4) is a quality of life scale or survey of patient’s responses and 
addresses MG-specific psychological well-being and social functioning. It is a brief 
questionnaire that is to be completed by the patient that uses 3 response options. The MG-
QoL15r is helpful in informing the clinician about the patient’s perception of the extent of 
and dissatisfaction with MG-related dysfunction. Each item is scored from 0 to 2 according 
to its frequency, with a maximum total score of 30. 
7.1.5. 
EQ-5D-5L 
EQ-5D (5 level version) is a standardized measure of health status developed by the EuroQol 
Group in order to provide a simple, generic measure of health for clinical and economic 
appraisal (Appendix 5). The descriptive system comprises 5 dimensions (mobility, self-care, 
usual activities, pain/discomfort, anxiety/depression). Each dimension now has 5 levels: no 
problems, slight problems, moderate problems, severe problems, and extreme problems. The 
respondent is asked to indicate his/her health state by ticking (or placing a cross) 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 
can be 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 is defined in this way. Each state is referred to in terms of a 
5-digit code. For example, state 11111 indicates no problems on any of the 5 dimensions, 
while state 12345 indicates no problems with mobility, slight problems with washing or 
dressing, moderate problems with doing usual activities, severe pain or discomfort and 
extreme anxiety or depression.  
7.2. 
Safety 
Safety assessments will consist of monitoring and recording all AEs, pregnancies, suicidality 
assessment, safety laboratory testing, measurement of vital signs, ECGs, physical 
examinations; and other tests that are deemed critical to the safety evaluation of the trial in all 
patients who receive at least 1 dose of the IMP. As discussed in Section 7.2.1.5, any 
pregnancy that occurs while a patient is enrolled into the trial will also be monitored and 
reported according to the appropriate regulations. 
The DSMB will evaluate the safety data periodically (see Section 7.2.6). 

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7.2.1. 
Adverse Events 
The Investigator is responsible for recording all AEs observed during the trial from the time 
the patient signs the ICF until the last contact of the patient. 
Definition of AE: An AE is any untoward medical occurrence in a clinical trial patient 
whether or not a pharmaceutical product is administered and which does not necessarily have 
a causal relationship with this treatment. An AE can therefore be any unfavorable and 
unintended sign (including an abnormal laboratory finding), symptom, or disease temporally 
associated with the use of a medicinal product or IMP, whether or not considered related to 
the medicinal product or IMP. 
An AE can also be a new disease or exacerbation of an existing disease (a worsening in the 
character, frequency, or severity of a known condition), if considered clinically relevant by 
the Investigator. 
Abnormal laboratory values, or test results, physical examination findings, and other 
abnormal investigational findings (i.e., ECG) should not be reported as AEs unless they are 
considered clinically significant, e.g., require therapy (e.g., hematologic abnormality that 
requires transfusion or hematological stem cell support) or lead to treatment discontinuation. 
Death is not considered an AE but an outcome. 
MG disease worsening, if considered clinically relevant by the Investigator, can be reported 
as AE, provided that it is supported by a clinically relevant change in total MG-ADL score 
(as compared to SEB). The Investigator should contact the Sponsor in case of clinically 
relevant worsening of the disease. 
Adverse Drug Reaction (ADR): Any untoward and unintended response in a patient to an 
IMP, which is related to any dose administered to that patient. 
Definition of Serious AE (SAE): An SAE, experience or reaction, is any untoward medical 
occurrence (whether considered to be related to IMP or not) that at any dose: 
x 
Results in death, 
x 
Is life-threatening (the patient is at a risk of death at the time of the event; it does not 
refer to an event, which hypothetically might have caused death if it was more severe), 
x 
Requires inpatient hospitalization or prolongation of existing hospitalization. However, a 
planned hospitalization related to the administration of IMP, is not considered an SAE. 
(Hospital admissions and/or surgical operations planned before a trial are not considered 
SAEs or if the illness or disease, which caused hospitalization, existed before the patient 
was enrolled in the trial, provided that it did not deteriorate in an unexpected way during 
the trial. However, the condition for which the surgery is required may be an AE), 
x 
Results in persistent or significant disability or incapacity, OR 

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x 
Is a congenital abnormality or birth defect. 
x 
Other: Medically significant events, which do not meet any of the criteria above, but 
may jeopardize the patient and may require medical or surgical intervention to prevent 
one of the other serious outcomes listed in the definition above. Examples of such events 
are blood dyscrasias (e.g., neutropenia or anemia requiring blood transfusion, etc.) or 
convulsions that do not result in inpatient hospitalization. 
Suspected Unexpected Serious Adverse Reactions (SUSARs) and Unexpected Adverse 
Reactions: Any suspected adverse reaction that is serious, unexpected, and considered to be 
related to drug exposure is defined as a SUSAR. 
An unexpected AE is any adverse drug event, which is not listed in the current IB or is not 
listed at the specificity or intensity that has been observed. 
Suspected adverse reaction means any AE for which there is a reasonable possibility that the 
drug caused the AE. 
An untoward and unintended post-dosing response to a non-trial drug is, by definition, not a 
SUSAR, but is, however, an AE. 
Each AE is to be evaluated for duration, severity, seriousness and causal relationship to the 
IMP or trial procedures. The action taken with the investigational drug and the outcome of 
the event must also be recorded. 
Treatment-emergent adverse event (TEAE): Any AE temporally associated with the use of 
IMP, whether considered related to the IMP or not. TEAEs are recorded from the start of 
IMP administration, until completion of the patient’s last visit. 
Overdose 
For the purposes of this trial, exceeding the dosage requirements specified in this protocol 
represents an overdose (see Section 6.1). In case of suspected overdose, the patient should be 
treated according to standard medical practice based on the Investigator’s judgment. 
Severity 
All AEs observed will be graded using the National Cancer Institute (NCI) Common 
Terminology Criteria for Adverse Events (CTCAE) version 5.0. The NCI CTCAE is a 
descriptive terminology, which can be utilized for AE reporting. A grading (severity) scale is 
provided for each AE term. Grade refers to the severity of the AE. If a particular AE’s 
severity is not specifically graded by the guidance document, the Investigator is to use the 
general NCI-CTCAE definitions of Grade 1 through Grade 5 following his or her best 
medical judgment. The CTCAE displays Grades 1 through 5 with unique clinical 
descriptions of severity for each AE based on the following general guideline: 
x 
Grade 1: Mild; asymptomatic or mild symptoms; clinical or diagnostic observations 
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x 
Grade 2: Moderate; minimal, local or noninvasive intervention indicated; limiting age-
appropriate instrumental activities of daily living (ADL). 
x 
Grade 3: Severe or medically significant but not immediately life-threatening; 
hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care 
ADL. 
x 
Grade 4: Life-threatening consequences; urgent intervention indicated. 
x 
Grade 5: Death related to AE. 
Relationship 
The causal relationship between the IMP/trial procedures and the AE has to be characterized 
as unrelated, unlikely, related, possible, and probable. 
x 
Events can be classified as “unrelated” if there is not a reasonable possibility that the 
IMP caused the AE. 
x 
An “unlikely” relationship suggests that only a remote connection exists between the 
IMP and the reported AE. Other conditions, including chronic illness, progression or 
expression of the disease state, or reaction to concomitant medication, appear to explain 
the reported AE. 
x 
A “related” relationship suggests that the AE follows a reasonable temporal sequence 
from administration of IMP, it follows a known or expected response pattern to the IMP, 
and it cannot reasonably be explained by known characteristics of patient’s clinical state. 
x 
A “possible” relationship suggests that the association of the AE with the IMP is 
unknown; however, the AE is not reasonably supported by other conditions. 
x 
A “probable” relationship suggests that a reasonable temporal sequence of the AE with 
drug administration exists and, in the Investigator’s clinical judgment, it is likely that a 
causal relationship exists between the drug administration and the AE, and other 
conditions (concurrent illness, progression or expression of disease state, or concomitant 
medication reactions) do not appear to explain the AE. 
In final evaluation for reporting, the relationship will be converted into “Binary 
Determination” as per Council of International Organizations of Medical Sciences (CIOMS). 
Unrelated and Unlikely will be clubbed into “Unrelated” and Related, Possible and Probable 
will be clubbed into “Related” for final reporting purpose. 
7.2.1.1. 
Adverse Events of Special Interest 
An AESI (serious or non-serious, related or not related) is an event of scientific and medical 
concern specific to the sponsor’s product or program. 

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ARGX-113 treatment induces reductions in IgG levels, and there is a potential risk for 
infections associated with the low IgG levels. As such, any infection will be considered AESI 
in this trial. Further characterizing information will be collected in the eCRF, such as: location 
of infection, relationship to underlying condition, medical history and concomitant medication, 
reoccurrence of previous infection, previous rescue therapy, any confirmatory procedure, 
culture or urgent medical intervention. 
7.2.1.2. 
Reporting of Adverse Events and Serious Adverse Events 
All AEs that occur during the trial from signature of the ICF until EoS are to be recorded on 
the appropriate AE pages (either ‘serious’ or ‘non-serious’) in the eCRF. The Investigator 
should complete all the details requested, including dates of onset, time of onset, stop date 
(when applicable), stop time (when applicable), severity, action taken, outcome, and 
relationship to IMP, and to trial procedures. Each event should be recorded separately in the 
eCRF. 
All AEs spontaneously reported by the patient or reported in response to the open question 
from the trial personnel: ‘Have you had any health problems since the previous visit or since 
you were last asked?’, or revealed by observation will be collected and recorded in the eCRF. 
When collecting AEs, the recording of diagnoses is preferred (when possible) to recording a 
list of signs and symptoms. However, if a diagnosis is known and there are other signs or 
symptoms that are not generally part of the diagnosis, the diagnosis and each sign or 
symptom will be recorded separately. 
Any SAE, including death due to any cause, which occurs during this trial after signature of 
the ICF, whether or not related to the IMP, must be reported immediately (within 24 hours of 
the trial site’s knowledge of the event). All SAEs will be recorded (within 24 hours) on the 
paper SAE Report Form and the AE form in the eCRF, the Investigator or delegated site staff 
should check that all entered data is consistent. An alert email for the SAE report in the eCRF 
will then automatically be sent by email to the Sponsor’s designated CRO safety mailbox via 
the electronic data capture (EDC) system. The paper SAE Report Form should be faxed or 
emailed to the Sponsor’s designated CRO (see the Safety Mailbox/Fax details on the title 
page of this protocol). 
The report will contain as much available information concerning the SAE to enable the 
Sponsor (or an authorized representative) to file a report, which satisfies regulatory reporting 
requirements. These timelines apply to initial reports of SAEs and to all follow-up reports. 
Criteria for documenting the relationship to IMP as well as severity, outcome, and action 
taken will be the same as those previously described. 
The Investigator shall report within 24 hours any SAE (s)he becomes aware of after a 
patient’s last visit if a causal relationship with the investigational product is suspected. Such 

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a serious adverse reaction (SAR) is to be collected and reported as previously described for 
SAEs.  
Additional follow-up information should be completed and entered on a paper SAE Report 
Form and sent by fax/email to the Sponsor’s designated CRO. 
7.2.1.3. 
Reporting of Serious Adverse Events to Regulatory Authorities and 
Investigators 
The Sponsor’s designee will be responsible for reporting all SUSARs, the Analysis of 
Similar Events (AOSE), and any other applicable reports to regulatory authorities, ethics 
committees, and Investigators, in accordance with national regulations in the countries where 
the trial is conducted. Relative to the first awareness of the event by/or further provision to 
the Sponsor’s designee, SUSARs will be submitted within 7 days for fatal and life-
threatening events and 15 days for other SUSARs, unless otherwise required by national 
regulations. The Sponsor’s designee will also prepare an expedited report for other safety 
issues where applicable. 
The investigational site will also forward a copy of all expedited reports to his or her 
IRB/IEC in accordance with national regulations. 
7.2.1.4. 
Follow-up of Adverse Events and Serious Adverse Events 
Any AEs observed from signing the ICF to the EoS visit will be followed up to resolution, 
until the patient is lost to follow-up, or until the patient withdraws consent. Resolution means 
that the patient has returned to a Baseline state of health or the Investigator does not expect 
any further improvement or worsening of the AE. 
Every effort should be made to follow all (S)AEs considered to be related to IMP or trial 
procedures until an outcome can be reported. If the patient is lost to follow-up, all AEs will 
be categorized based on the Investigator’s last assessment. 
All SAEs that are spontaneously reported after the EoS visit are to be collected and reported 
as previously described (as per Section 7.2.1.1) and will be followed up. During the trial 
period, resolution of SAEs (with dates) should be documented on the SAE page of the eCRF 
and in the patient’s medical record to facilitate source data verification. If, after follow-up, 
return to the Baseline status or stabilization cannot be established, an explanation should be 
recorded on the SAE page of the eCRF. 
All pregnancies reported during the trial should be followed until pregnancy outcome. 
For SAEs, non-serious AEs, and pregnancies, the Sponsor’s designee may follow-up by 
telephone, fax, electronic mail, and/or a monitoring visit to obtain additional case details and 
outcome information (e.g., from hospital discharge summaries, consultant reports, or autopsy 
reports) in order to perform an independent medical assessment of the reported case. 

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7.2.1.5. 
Reporting and Follow-up Requirements for Pregnancies 
7.2.1.5.1. Pregnancies in Female Patients 
Serum pregnancy tests will be performed centrally at Screening. Urine pregnancy tests will 
be conducted and analyzed locally before randomization and thereafter at visits as detailed in 
the general SoA (Table 1). 
If a patient becomes pregnant after the administration of IMP and up to 90 days after the 
patient received the last infusion, the Sponsor and/or Sponsor’s designee should be informed 
immediately (i.e., within 24 hours of the trial site’s knowledge of the event). The following 
actions will be performed: 
x 
The patient should immediately be discontinued from randomized treatment. 
x 
The patient should have EoT assessments. 
x 
All assessments for EoT (see Sections 4.4.2 and 5.6) must be performed unless 
contraindicated by pregnancy (harmful to fetus) or unless the patient withdraws 
informed consent. 
The Investigator must update the patient with information currently known about potential 
risks and about available treatment alternatives. The pregnancy should be followed-up to 
determine outcome, including spontaneous or voluntary termination, details of the birth, and 
the presence or absence of any birth defects, congenital abnormalities, or maternal and/or 
newborn complications. 
If required by local regulations, the female participant will be requested to sign a separate 
pregnancy ICF. 
Full details will be recorded on a paper Pregnancy Report Form and submitted via email or 
fax (see the Safety Mailbox/Fax details on the title page of this protocol), and reporting 
details will be specified in the trial manual. The Investigator will update the Pregnancy 
Report Form with additional information as soon as the outcome of the pregnancy is known. 
If the outcome of the pregnancy is an SAE, then this must be additionally reported as an SAE 
on the appropriate SAE Report Form. 
7.2.1.5.2. Pregnancies in Female Partners of Male Patients 
Male patients will be instructed through the ICF to immediately inform the Investigator if 
their partner becomes pregnant during the trial or up to 90 days after they received the last 
infusion of IMP. A Pregnancy Report Form should be completed by the Investigator within 
24 hours after learning of the pregnancy and submitted via email or fax (see the Safety 
Mailbox/Fax details on the title page of this protocol). Attempts should be made to collect 

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and report details of the course and outcome of any pregnancy in the partner of a male patient 
exposed to the IMP. 
The pregnant partner will need to sign an ICF to allow for follow-up on her pregnancy. Once 
the ICF has been signed, the Investigator will update the Pregnancy Report Form with 
additional information on the course and outcome of the pregnancy. An Investigator, who is 
contacted by the male patient or his pregnant partner, may provide information on the risks of 
the pregnancy and the possible effects on the fetus, to support an informed decision in 
cooperation with the treating physician and/or obstetrician. 
7.2.2. 
Clinical Laboratory Evaluations 
Blood and urine samples for determination of clinical chemistry, hematology, urinalysis, PK, 
PD, viral testing, and ADA will be analyzed at a central lab as indicated in the general SoA 
(Table 1) and Appendix 6. Patients need to be fasting for at least 8 hours prior to the 
sampling for clinical laboratory tests as from Screening up to EoS. Retesting is allowed once 
after Sponsor’s written approval (see Section 4.7). 
Additional safety samples may be collected if clinically indicated at the discretion of the 
Investigator. 
For all patients of childbearing potential, a serum pregnancy test will be performed centrally 
at Screening (on the samples taken for clinical laboratory tests), and a urine pregnancy test 
will be conducted and analyzed locally at the site (on the urine samples taken for urinalysis) 
at all visits, except at Screening.  
The estimated total maximum blood volume needed for a patient during the trial (when 
completing the trial up until the last visit) is between 225 mL for a patient who receives 
1 Treatment Cycle only and 385 mL for a patient who receives the maximum of 3 treatment 
cycles. 
Clinical laboratory tests will be reviewed for results of potential clinical significance at all 
time points throughout the trial. The Investigator will evaluate any change in laboratory 
values. If the Investigator determines a laboratory abnormality to be clinically significant, it 
will be considered as a laboratory AE; however, if the abnormal laboratory value is 
consistent with a current diagnosis, it may be documented accordingly without being 
reported as an AE. 
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 
entered in the patient’s source documents and on the central lab assessment eCRF page. 
Besides the urine pregnancy test which will be conducted and analyzed locally, all samples 
will be analyzed centrally. 
 
CCI

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7.2.3. 
Vital Signs, Physical Examination, and ECG 
Assessment of vital signs (supine blood pressure, heart rate, and body temperature) physical 
examination and ECG will be performed at the time points indicated in the general SoA 
(Table 1) (pre-dose at dosing days). 
Supine blood pressure and heart rate will be measured using standard equipment after 
10 minutes rest on a bed. 
It is recommended that the method used to measure body temperature at Screening is 
maintained throughout the trial for each patient. 
A physical examination will include at a minimum an assessment of general appearance, 
skin, lymph nodes, musculoskeletal/extremities, abdomen, cardiovascular, respiratory, and 
neurological system.  
Height will be measured at Screening only and weight will be measured at Screening and at 
the EoS/ED visit. Weight measurement can be repeated at any visit when there is an obvious 
weight change compared to the last weight assessment. For the assessment of height and 
weight, patients will be required to remove their shoes and wear light indoor clothing for 
these measurements. 
A 12-lead ECG will be recorded locally as per local regulations in the supine position after 
the patient has rested in this position for at least 10 minutes. The assessments on heart rate, 
PR, QT and QRS intervals will be read centrally. 
7.2.4. 
Suicidality Assessment 
As is recommended for trials involving a biological product for a neurological indication, a 
prospective assessment for suicidal ideation and behavior will be included in this clinical 
trial. 
This so-called suicidality assessment will be conducted by specifically asking the following 
question, derived from the PHQ-9: 
x "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?" 
The patient will be asked this question at each visit and the response documented. Response 
options as per the PHQ-9 are limited to the following: "not at all", "several days", "more 
than half the days" or "nearly every day". 
This specific question was selected for the reported significant linear relationship between 
the item 9 score of the PHQ-9 and the risk of subsequent suicide attempt (Simon, Rutter et al. 
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7.2.5. 
Medical and Surgical History 
Clinically significant findings and pre-existing conditions present in a patient prior to 
Screening must be reported on the relevant medical history/current medical conditions page 
of the eCRF. 
Information should be provided on medical and surgical history and concomitant medical 
conditions specifying those ongoing at Screening. 
7.2.6. 
Data Safety Monitoring Board (DSMB) 
The Sponsor will appoint a DSMB consisting of an independent group of clinical experts, 
who are not participating in the trial. They will be supplemented by an independent 
statistician. The objective of the DSMB will be to review all unblinded safety data (including 
the overall number of patients treated up to that point, rates, and patient-level details) and 
determine if there is an imbalance in the treatment arms with respect to these events, based 
on clinical judgment of the DSMB. Fixed meetings will be scheduled based on the 
recruitment rate into the trial, and incidence of (S)AEs. In addition, ad hoc meetings can be 
requested at any time during the trial by either the Sponsor or the DSMB. The DSMB will 
advise the Sponsor concerning continuation, modification or termination of the trial after 
every meeting. 
The composition, objectives, and role and responsibilities of the independent DSMB will be 
described in a DSMB charter, agreed with the DSMB members and Sponsor. The DSMB 
charter will also define and document the content of the safety summaries, and general 
procedures (including communications). 
7.2.7. 
Visit Reminder/Subject ID Card 
Patients must be provided with the address and telephone number of the main contact for 
information about the clinical trial. The Investigator must therefore provide a “Visit 
Reminder/Subject ID Card” to each patient. In an emergency situation this card serves to 
inform the responsible attending physician that the patient is in a clinical trial and that 
relevant information may be obtained by contacting the Investigator. Patients must be 
instructed to keep the card in their possession at all times. 
7.3. 
Pharmacokinetics (PK) 
Blood samples for PK will be collected from each patient as presented in Table 1. 
Concentrations of ARGX-113 will be determined using a validated assay. The actual date 
and time of collection of the blood sample will be recorded in the relevant section of the 
eCRF. 

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7.4. 
Pharmacodynamics (PD) 
The PD markers (total IgG and IgG subtypes [IgG1, IgG2, IgG3 and IgG4], and 
autoantibodies (anti-AChR antibodies for the AChR-Ab seropositive patients and anti-MuSK 
antibodies for the MuSK-Ab seropositive patients) will be measured at the time points as 
indicated in Table 1.  
These PD markers will be determined using validated assays. The actual date and time of 
collection of the blood sample will be recorded in the relevant section of the eCRF. 
7.5. 
Anti-Drug Antibodies (ADA) 
Blood samples to assess ADA will be collected pre-dose at the time points as indicated in 
Table 1. At Baseline (SEB and TCnB), Screening, confirmatory and titer analysis will be 
performed using a validated ADA assay. Samples having a positive ADA titer will be further 
investigated in a neutralizing ADA assay. The actual date and time of collection of the blood 
sample will be recorded in the relevant section of the eCRF. 
8. 
STATISTICS 
The statistical analyses will be performed by Sponsor’s designated CRO using statistical 
analysis systems SAS® (SAS Institute, Cary, NC, United States [US]) version 9.2 or higher, 
and the software package R, if applicable. The standard operating procedures (SOPs) and 
work instructions of Sponsor’s designated CRO will be used as the default methodology if 
not otherwise specified. 
Any change to the data analysis methods described underneath will be mentioned in the 
statistical analysis plan (SAP). Any additional analysis, and the justification for making the 
change, will be described in the clinical trial report (CTR). Additional exploratory analyses 
of the data will be conducted as deemed appropriate. 
8.1. 
Determinations of Sample Size 
The null hypothesis H0 states that there is no difference in proportion of MG-ADL 
responders between patients treated with placebo and ARGX-113. The trial is powered at 
90% using significance level of 5% 2-sided to test the alternative hypothesis of that the 
difference in the proportion of responders is 29% in favor of patients treated with 
ARGX-113. The 29% is a weighted average of 80% AChR-Ab seropositive patients with 
treatment difference of 35% and 20% AChR-Ab seronegative patients with treatment 
difference of 5%. The proportion MG-ADL responders amongst patients treated with placebo 
is hypothesized to be 30%. In order to test this alternative hypothesis, a sample size of 
150 patients is needed, with this allowing for 10% attrition rate. 

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8.2. 
Analysis Populations 
The efficacy analyses will be done in the modified Intention-To-Treat (mITT: all randomized 
patients who have a Baseline efficacy total score for MG-ADL and at least one post-Baseline 
total MG-ADL score) and in the Per Protocol (PP) populations for sensitivity analyses of 
primary and secondary endpoints. PP is defined as subset of mITT, i.e., all randomized 
patients who have a Baseline efficacy total score for MG-ADL and at least one post-Baseline 
total MG-ADL score and that received at least 3 out of 4 infusions (in any order), and 
without a major protocol deviation. Safety analysis will be performed on safety set 
comprising all patients in the randomized population who received at least one dose or part 
of a dose. The safety analysis will be based on the actual treatment received. 
8.3. 
Patient Disposition, Characteristics and Concomitant Medication 
A tabular presentation of the patient disposition will be provided. It will include the number 
of patients screened, randomized, completed, as well as the number of early discontinuations 
from randomized treatment (including rescued patients) and trial, with reasons for 
discontinuation from treatment or trial, and major protocol deviations. 
A listing will be presented to describe dates of Screening, randomization or assigned 
treatment, screen failure with reason, completion or early discontinuation and the reason for 
discontinuation, if applicable, for each patient. 
Patient characteristics will be recorded prior to randomization and will be listed and 
summarized by treatment. Overall summaries will include descriptive statistics for 
continuous measures (number of observations, mean, standard deviation, median, minimum 
and maximum) and for categorical measures (frequency and percent). Patient characteristics 
include, but are not limited to age, sex, race, weight, and body mass index (BMI). 
Use of concomitant medication will be summarized by treatment with frequency and 
percentage. All concomitant medications used will be listed. 
8.4. 
Statistical Methods 
8.4.1. 
Primary Endpoint Analyses 
The primary endpoint is tested by means of a 2-sided exact test (using logistic regression) 
stratified for the stratification factors Japanese vs non-Japanese patients, AChR-Ab serotype 
and SoC at the 2-sided 5% significance level, in the AChR-Ab seropositive patients. 
Percentage MG-ADL responders will be compared between ARGX-113 and placebo using 
logistic regression model with Baseline total score as covariate and Japanese/non-Japanese 
patient, AChR-Ab serotype and SoC as stratification variables. 

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The treatment effect will be presented as the odds ratio together with its 95% confidence 
interval (CI) and 2-sided p-value. 
8.4.2. 
Secondary Endpoint Analyses 
The primary efficacy endpoint will be tested at the 5% 2-sided alpha level and will act as 
gatekeeper for the testing of secondary endpoints. Subject to meeting significance for the 
primary endpoint, secondary endpoints will be tested at the 5% 2-sided significance level in a 
strict hierarchical order as follows: 
Secondary endpoints: 
1. Comparison of proportion responders based on QMG between active and placebo group 
after the first Treatment Cycle, in AChR-Ab seropositive patients. 
2. Comparison of proportion responders based on MG-ADL between active and placebo 
group after the first Treatment Cycle, in overall population (AChR-Ab seropositive and 
AChR-Ab seronegative patients). 
3. Comparison of proportion of time that patients have a “clinically meaningful 
improvement” in total MG-ADL score between active and placebo group in AChR-Ab 
seropositive patients. 
4. Time from start of TC1V5 to qualification for re-treatment monitored by total MG-ADL 
score between active and placebo group in AChR-Ab seropositive patients if: 
- the patient has a total MG-ADL score of  5 points with more than 50% of the total 
 score due to non-ocular symptoms, and 
- no clinically meaningful improvement (decrease in total MG-ADL score from 
 TC1B < 2). 
5. Comparison of percentage early MG-ADL responders based on the total MG-ADL score 
between active and placebo group after the first Treatment Cycle, in AChR-Ab 
seropositive patients.  
Secondary endpoints n°1, n°2 and n°5 will be analyzed using the same statistical approach as 
described for the analysis of the primary endpoint. Secondary endpoint n°3 will be analyzed 
using an analysis of covariance (ANCOVA) model with terms for randomized treatment and 
Baseline total MG-ADL score as a covariate; the model will be stratified for the stratification 
variables. Secondary endpoint n°4 will be analyzed using Kaplan-Meier time to event 
analysis (stratified log-rank test), stratified for the stratification variables. 
8.4.3. 
Tertiary Endpoint Analyses 
The tertiary endpoints will be analyzed in a descriptive manner.  

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Summary statistics will be provided for the continuous endpoints in terms of absolute values 
and changes from Baseline (SEB and TCnB). 
In addition, difference in total score change from Baseline between treatment groups at the 
different post-Baseline (SEB and TCnB) time points will be analyzed by means of Mixed 
Models for Repeated Measurements (MMRM) (using all available data at all time points). 
The model will include treatment, visit and treatment by visit interaction terms as fixed 
effects, with Baseline value as a covariate; the analysis will be stratified for randomization 
strata. An unstructured (UN) covariance matrix for the repeated measures within patient will 
be specified for the analysis and the following statistics will be presented for each visit: 
x 
Least Square (LS) Means per treatment group 
x 
Standard error of LS Means 
x 
95% CI 
x 
LS Mean Difference (ARGX-113 – placebo) 
x 
Standard error of LS Mean Difference 
x 
95% CI for LS Mean Difference 
x 
2-sided p-value for testing differences between treatment groups 
If the model does not converge upon using UN, the following covariance structures will be 
tested for convergence: heterogeneous Toeplitz (TOEPH), heterogeneous autoregressive 1 
(ARH[1]), heterogeneous compound symmetry (CSH), TOEP, AR(1) and CS covariance 
structures. 
Percentage of time that patients have a clinically meaningful improvement during the trial, 
will be analyzed using an ANCOVA model similar to that described for the percentage of 
time showing a clinically meaningful improvement.  
The tertiary endpoints “MG-ADL responders from the second Treatment Cycle on 
(compared to each corresponding TCB) in AChR-Ab seropositive patients and in overall 
population”, and “QMG responders from the second Treatment Cycle on (compared to each 
corresponding TCB) in AChR-Ab seropositive patients”, will be analyzed using the same 
methodology as for the primary endpoint.  
Frequency tables will also be presented for all binary variables, including AEs. 
In addition, descriptive statistics will be provided for PD (IgG and subtypes, and also anti-
AChR and anti-MuSK antibodies), PK and ADA.  
ARGX-113 serum concentration data will be summarized and PK calculations will be 
performed with standard non-compartmental methods. The following PK parameters will be 
calculated after single and multiple administrations of ARGX-113 using individual 
concentration data in serum and actual sampling times: 

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Cmax: maximum observed serum concentration 
Ctrough: serum concentration observed pre-dose at Visits 2, 3 and 4 
Rac: accumulation ratio, calculated as Visit 4 Cmax /Visit 1 Cmax 
8.5. 
Interim Analyses 
Not applicable 
9. 
QUALITY CONTROL AND QUALITY ASSURANCE 
9.1. 
Investigator’s Responsibility 
The Investigator will comply with the protocol (which has been approved/given favorable 
opinion) by the Ethics Committee, ICH GCP, and applicable regulatory requirements. The 
Investigator is ultimately responsible for the conduct of all aspects of the trial at the trial site 
and verifies by signature the integrity of all data transmitted to the Sponsor. The term 
“Investigator” as used in this protocol as well as in other trial documents, refers to the 
Investigator or authorized trial personnel that the Investigator has designated to perform 
certain duties. Sub-Investigators or other authorized trial personnel are eligible to sign for the 
Investigator, except where the Investigator’s signature is specifically required. 

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9.2. 
Quality Control of Data 
Quality control will be applied to each stage of data handling. 
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 and ECGs. 
x 
Site initiation visit. 
x 
Routine site monitoring. 
x 
Ongoing site communication and training. 
x 
Ongoing oversight by Clinical Trial 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 CTR. 
x 
To avoid inter-observer 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, Sponsor and/or Sponsor’s designated CRO Clinical Quality Assurance (CQA) 
Department may conduct periodic audits of the trial processes, including, but not limited to 
trial site, or site visits, central laboratories, vendors, clinical database, and final CTR. When 
audits are conducted, access must be authorized for all trial-related documents including 
medical history and concomitant medication documentation to authorized Sponsor’s 
representatives and regulatory authorities. 
9.3. 
Monitoring 
The Sponsor has engaged the services of a CRO to perform all clinical trial monitoring 
functions within this clinical trial. Sponsor’s designated CRO monitors will work in 
accordance with SOPs of the CRO.  
Monitoring visits must be conducted according to the applicable ICH-GCP guidelines to 
verify that, amongst others, the: 
x 
Data are authentic, accurate, and complete. 
x 
Safety and rights of subjects are being protected. 

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x 
Trial is conducted in accordance with the currently approved protocol, any other trial 
agreements and all applicable regulatory requirements. 
The Investigator and the head of the medical institution (where applicable) agrees to allow 
the Clinical Trial Monitor direct access to all relevant documents. 
The Investigator must ensure provision of reasonable time, space and qualified personnel for 
monitoring visits. 
The Clinical Trial Monitor will perform an eCRF review and Source Document Verification 
(SDV).  
The Source Documentation Agreement Form describes the source data for the different data 
in the eCRF. This document should be completed and signed by the Clinical Trial Monitor 
and Investigator and should be filed in the Investigator’s trial file. Any data item for which 
the eCRF will serve as the source must be identified, agreed and documented in the Source 
Documentation Agreement Form. 
Upon completion or premature discontinuation from the trial, the Clinical Trial Monitor will 
conduct site closure activities with the Investigator and site staff as appropriate, in 
accordance with applicable regulations, ICH GCP guidelines and CRO/Sponsor procedures. 
9.4. 
Data Management 
Data generated within this clinical trial will be handled according to the SOPs of the Data 
Management and Biostatistics departments of the Sponsor’s designated CRO. 
Case report forms are provided for each patient in electronic format. It will be transcribed by 
the trial site staff from the source documents onto the eCRF. Date must be entered in English 
and guidelines for eCRF completion, including the collection of Investigator’s e-signature, 
will be provided by the CRO. Appropriate training and security measures will be completed 
with the Investigator and all authorized trial site staff prior to the trial being initiated and any 
data being entered into the system for any trial patient at the site. 
The eCRF is essentially considered a data entry form and should not constitute the original 
(or source) medical records unless otherwise specified. Source documents are all documents 
used by the Investigator or hospital that relate to the patient’s medical history, that verify the 
existence of the patient, the inclusion and exclusion criteria, and all records covering the 
patient’s participation in the trial. They can include laboratory notes, ECG results, 
memoranda, pharmacy dispensing records, patient files, etc. The eCRFs should be completed 
by the Investigator or a qualified designee from the site as soon as the data are available. 
As a matter of regulation, the Investigator is responsible for the accuracy and authenticity of 
all clinical data entered onto eCRFs. Prior to database lock, each completed eCRF must be 
reviewed for accuracy by the Investigator, corrected as necessary and then approved. The 
Investigator’s e-signature serves to attest that the information contained on the eCRFs has 

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been reviewed by the Investigator and is true and accurate. The Investigator will be required 
to electronically sign off the eCRF. 
The data will be verified for missing data, inconsistencies, and for necessary medical 
clarifications. Queries arising from these checks will be flagged to the trial site, and the trial 
site staff will correct data, confirm or clarify data as appropriate. The CRO will provide the 
details of the review process in a data management plan and monitoring plan. Any change, 
including the issuing of queries, will be fully audit trailed by the EDC application, meaning 
the name of the person, time, and date stamp are captured, as well as the reason for change. 
Data will also be provided by third party vendors, such as the results generated by the central 
labs, IRT provider, or centralized ECG reading. This data will need to be reconciled with the 
data recorded in the eCRF before it can be merged with the eCRF data into the clinical 
database. The CRO will provide a data management plan detailing this reconciliation. 
Adverse events, concomitant diseases/medical history terms will be assigned to a lowest 
level term (LLT) and a preferred term (PT) and will be classified by high level term (HLT), 
high level group term, and primary system organ class (SOC) according to the Medical 
Dictionary for Regulatory Activities (MedDRA) thesaurus. 
Prior and concomitant medications will be classified according to active drug substance using 
the World Health Organization Drug Dictionary (WHO-DD). The generic name, the 
preferred name, and the WHO name will be assigned using WHO-DD thesaurus. 
The Anatomical Therapeutic Chemical (ATC) classes will be assigned to the prior and 
concomitant medications. 
9.5. 
Quality Assurance Audit 
Trial sites, the trial database and trial documentation may be subject to Quality Assurance 
audit during the course of the trial 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. 
10. 
ETHICS 
10.1. 
Institutional Review Board or Independent Ethics Committee 
The Investigator will provide the Sponsor or designee with documentation of IRB/IEC 
approval of the protocol and informed consent documents before the trial may begin at the 
trial sites. The Investigator will supply documentation to the Sponsor or designee of the 
required IRB/IEC’s annual renewal of the protocol, and any approvals of revisions to the 
informed consent document or amendments to the protocol. 

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The Investigator will report promptly to the IRB/IEC, any new information that may 
adversely affect the safety of patients or the conduct of the trial. Similarly, the Investigator 
will submit written summaries of the trial status to the IRB/IEC annually, or more frequently 
if requested by the IRB/IEC. Upon completion of the trial, the Investigator will provide the 
IRB/IEC with a brief report of the outcome of the trial, if required. 
10.2. 
Ethical Conduct of the Trial 
This trial will be conducted and the informed consent will be obtained according to the 
ethical principles stated in the Declaration of Helsinki (2008), the applicable guidelines for 
GCP, or the applicable drug and data protection laws and regulations of the countries where 
the trial will be conducted. 
10.3. 
Patient Information and Informed Consent 
The ICF will be used to explain the risks and benefits of trial participation to the patient in 
simple terms before the patient is screened. A separate ICF will be given in case of 
pregnancy of a female partner of male patient. The ICF contains a statement that the consent 
is freely given, that the patient is aware of the risks and benefits of entering the trial, and that 
the patient is free to withdraw from the trial at any time. Written consent must be given by 
the patient and/or legally acceptable representative, after the receipt of detailed information 
on the trial. 
All ICFs must be available in the local and vernacular languages required at the site and 
include patient information sheets/brochures that outline the trial procedures. All ICF(s) must 
be signed and dated by the patient or a legally acceptable representative. 
For patients who are unable to read and write, the patient information sheet and ICF(s) 
should be read to the patient in his/her native language in the presence of a legally acceptable 
representative who is literate and not affiliated with the trial. The patient having understood 
the information given to him/her in the presence of a legally acceptable representative will 
thumbprint the ICF(s) and the same will be countersigned by the legally acceptable 
representative. If the patient or legally acceptable representative cannot read, then an 
impartial witness will witness and attest the entire consent process and will be required to 
sign the ICF. 
Confirmation of a patient’s informed consent must also be documented in the patient’s 
medical record prior to any testing under this protocol, including Screening tests and 
assessments. 
The Investigator is responsible for ensuring that informed consent is obtained from each 
patient or legally acceptable representative and for obtaining the appropriate signatures and 
dates on the informed consent document prior to the performance of any protocol procedures 

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and prior to the administration of IMP. The Investigator will provide each patient with a copy 
of the signed and dated ICF(s). 
10.4. 
Patient Data Protection 
The ICF will incorporate (or, in some cases, be accompanied by a separate document 
incorporating) wording that complies with relevant data protection and privacy legislation. 
11. 
TRIAL ADMINISTRATION 
11.1. 
Data Handling and Record Keeping 
It is the Investigator’s responsibility to maintain essential trial documents (records and 
documents pertaining to the conduct of this trial and the distribution of IMP, including 
regulatory documents, eCRFs, signed patient 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 trial site 
should plan on retaining such documents for approximately 25 years after trial completion. 
The trial 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 trial is 
being conducted. Patient identification codes (patient names and corresponding trial 
numbers) will be retained for this same period of time. These documents may be transferred 
to another responsible party, acceptable to 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 trial documents. 
The Investigator must contact Sponsor prior to disposing of any trial records. 
No records should be disposed of without the written approval of argenx BVBA. 
For trials conducted outside the US under a US Investigational New Drug (IND), the 
Principal Investigator must comply with US FDA IND regulations and with those of the 
relevant national and local health authorities. 
11.2. 
Direct Access to Source Data/Documents 
The Sponsor or designee and auditor may access patient records for the purpose of 
monitoring this trial, 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 

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patient chart and eCRF records. Such information must be kept confidential and must have 
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 patient 
enrolled into the trial. 
The Investigator is responsible for maintaining source documents. These will be made 
available for inspection by the Clinical Trial Monitor at each monitoring visit. The 
Investigator must submit a completed eCRF for each patient who receives IMP, regardless of 
duration. All supportive documentation submitted with the eCRF, such as laboratory or 
hospital records, should be clearly identified with the trial and patient number. Any personal 
information, including patient name, should be removed or rendered illegible to preserve 
individual confidentiality. 
11.3. 
Investigator Information 
11.3.1. 
Investigator Obligations 
The Investigator is responsible for ensuring that all trial site personnel, including Sub-
Investigators, adhere to all applicable regulations and guidelines, including local laws and 
regulations, regarding the trial, both during and after trial completion. The Investigator is 
responsible for informing the IRB/IEC of the progress of the trial and for obtaining annual 
IRB/IEC renewal. The Investigator is responsible for informing the IRB/IEC of completion 
of the trial and will provide the IRB/IEC with a summary of the results of the trial. 
11.3.2. 
Protocol Signatures 
After reading the protocol, each Investigator will sign the protocol signature page and send a 
copy of the signed page to the Sponsor or representative. By signing the protocol, the 
Investigator confirms in writing that he/she has read, understands, and will strictly adhere to 
the trial protocol and will conduct the trial in accordance with ICH Tripartite Guidelines for 
GCP and applicable regulatory requirements. The trial will not be able to start at any site 
where the Investigator has not signed the protocol. 
11.3.3. 
Publication Policy 
All information regarding ARGX-113 supplied by the Sponsor to the Investigator and all 
data generated as a result of this trial, are considered confidential and remain the sole 
property of the Sponsor. The results of the trial will be reported in a CTR. 
The CTR written in accordance with the ICH E3 Guideline, will be submitted in accordance 
with local regulations. 
Any manuscript, abstract or other publication or presentation of results or information arising 
in connection with the trial must be prepared in conjunction with the Sponsor and must be 

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submitted to the Sponsor for review and comment prior to submission for publication or 
presentation. Trial patient identifiers will not be used in publication of results. 
Authorship will be granted based on scientific input, recruitment efforts, and will be granted 
upon decision of a publication committee. This committee will include among others the 
Coordinating Investigator and the Sponsor. 
The Sponsor will register and/or disclose the existence of and the results of clinical trials as 
required by law. 
11.3.4. 
Financing and Insurance 
The Sponsor will fund the trial as outlined in the Clinical Trial Agreement.  
The Sponsor will obtain adequate global/local insurance for the trial participants including 
the trial patients for the required duration of time. 
The Sponsor maintains an insurance coverage for this trial in accordance with the laws and 
regulations of the countries in which the trial is performed. Liability and insurance provisions 
for this trial are specified in the Investigator’s contract. The terms and conditions will apply 
as specified in the policy document. 

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12. 
REFERENCES 
1. 
Barohn, R. J., Herbelin, L. (2000). "The Quantitative Myasthenia Gravis Test Manual, 
Myasthenia Gravis Foundation of America, Inc. Revised March 25, 2000. University 
of 
Texas, 
Southwestern 
Medical 
Center, 
Dallas, 
Texas.", 
from 
http://myasthenia.org/LinkClick.aspx?fileticket=9U5kP6SfCJs%3D&tabid=125. 
2. 
Barohn, R. J., D. McIntire, L. Herbelin, et al. (1998). "Reliability testing of the 
quantitative myasthenia gravis score." Ann N Y Acad Sci 841: 769-772. 
3. 
Benatar, M., D. B. Sanders, T. M. Burns, et al. (2012). "Recommendations for 
myasthenia gravis clinical trials." Muscle Nerve 45(6): 909-917. 
4. 
Burns, T. M., C. K. Grouse, M. R. Conaway, et al. (2010). "Construct and concurrent 
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5. 
Burns, T. M., C. K. Grouse, G. I. Wolfe, et al. (2011). "The MG-QOL15 for following 
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6. 
Challa, D. K., U. Bussmeyer, T. Khan, et al. (2013). "Autoantibody depletion 
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Immunol 382: 249-272. 
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Drachman, D. B. (1994). "Myasthenia gravis." N Engl J Med 330(25): 1797-1810. 
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Howard, J. F., Jr., R. J. Barohn, G. R. Cutter, et al. (2013). "A randomized, double-
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Howard, J. F., Jr., K. Utsugisawa, M. Benatar, et al. (2017). "Safety and efficacy of 
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Kaminski, H. J. (2016). "Seronegative Myasthenia Gravis-A Vanishing Disorder?" 
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Katzberg, H. D., C. Barnett, I. S. Merkies, et al. (2014). "Minimal clinically important 
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Meriggioli, M. N. and D. B. Sanders (2009). "Autoimmune myasthenia gravis: 
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18. 
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Nowak, R. J., D. B. Dicapua, N. Zebardast, et al. (2011). "Response of patients with 
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Patel, D. A., A. Puig-Canto, D. K. Challa, et al. (2011). "Neonatal Fc receptor blockade 
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27. 
Wolfe, G. I., L. Herbelin, S. P. Nations, et al. (1999). "Myasthenia gravis activities of 
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Wolfe, G. I., H. J. Kaminski and I. B. Aban, et al (2016). "Randomized Trial of 
Thymectomy in Myasthenia Gravis." N Engl J Med 375(6): 511-522. 
 

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Appendix 5 EQ-5D-5L (UK English Sample Version) 
 

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Source: website EuroQoL, EQ-5D-5L(EuroQoL 2009) 

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Appendix 6 Laboratory Evaluations 
Hematology 
Hemoglobin, platelet count, white blood cell (WBC) count with WBC 
differential 
Clinical Chemistry 
Creatinine, creatinine clearance, blood urea nitrogen (BUN), glucose, 
glycosylated hemoglobin [HbA1c], alanine aminotransferase (ALT), 
aspartate aminotransferase (AST), total bilirubin, gamma-glutamyl 
transferase (GGT), C-reactive protein (CRP), alkaline phosphatase (ALP), 
lactate dehydrogenase (LDH), uric acid, albumin, potassium, sodium, 
calcium, lipid panel (total cholesterol, high density lipoprotein [HDL], low 
density lipoprotein [LDL], and triglycerides), international normalized ratio 
(INR) and activated partial thromboplastin time (aPTT). 
Total IgG at Screening only1 
Urinalysis 
Color, clarity/appearance, specific gravity, pH, protein, glucose, ketones, 
blood, bilirubin, urobilinogen, nitrite, leukocyte esterase, and microscopic 
examination including red blood cell (RBC) count, WBC, cast crystals, 
bacteria. 
Serology 
Human immunodeficiency virus (HIV) antibodies (1 and 2), Hepatitis B 
surface antigen (HBsAg), antibodies to the surface and core antigens of the 
hepatitis B virus (anti-HBs and anti-HBc), hepatitis C virus antibody 
(HCV-Ab) 
Other 
Serum and urine human chorionic gonadotrophin (ß-HCG), 
Follicle-stimulating hormone (FSH) test 
Pharmacokinetics (PK) 
Concentration levels of ARGX-113 
AChR-/MuSK-antibody 
serotype 
AChR-antibody (binding) levels and anti-muscle-specific kinase (MuSK) 
antibodies (in all patients; at Screening only)2 
Pharmacodynamic (PD) 
markers 
Total IgG and subtypes (IgG1, IgG2, IgG3, and IgG4), and AChR-Ab 
(binding) levels in AChR-Ab seropositive patients only and anti-MuSK 
antibodies in MuSK-Ab seropositive patients only  
Anti-drug antibodies 
(ADA) 
Levels of anti-ARGX-113 binding and neutralizing antibodies (if applicable) 
Note: All blood and urine samples will be collected locally (pre-dose on dosing days) and analyzed centrally.  
1 For eligibility purpose, total IgG will be measured (as part of clinical lab) centrally at Screening. At all other 
timepoints, total IgG will be analyzed, together with the other PD parameters, by a specialty lab. 
2 In case the AChR-Ab result is not available in time (i.e. within the 2 weeks screening window), the screening 
window can be enlarged on an ad-hoc base with maximum 5 calendar days. 

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CCI

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Appendix 8 Decision Tree for Re-treatment – Part A 
 
1 MG-ADL decrease of  2 points (compared to the corresponding TC baseline) for at least 4 consecutive weeks 
with the first of these decreases occurring at the latest 1 week after last infusion of IMP of the corresponding 
cycle. 
2 Retreat at the first timepoint when all re-treatment conditions apply and if no infection or confounding 
conditions exist (see also section 4.1). 
3 MG-ADL decrease of < 2 compared to corresponding TC baseline. 
 
 

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Appendix 9 Decision Tree for Re-treatment – Part B 
 
 
 
1 Conditions that may interfere with the correct interpretation of the data or put the patient at undue risk. 
2 Re-treatment with IMP may be reconsidered at next time where conditions for re-treatment are met, providing 
that at least 4 weeks have past after other MG treatment. 
3 Provided that it is not a SoC or a prohibited medication.