A Phase 2 Trial to Investigate the Efficacy, Safety, and Tolerability of Efgartigimod PH20 SC in Adult Patients With Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
Phase: PHASE2
Conditions: Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
Sponsor: argenx

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
1
TITLE PAGE
Protocol Title: 
A Phase 2 Trial to Investigate the Efficacy, Safety, and Tolerability of 
Efgartigimod PH20 SC in Adult Patients With Chronic Inflammatory 
Demyelinating Polyneuropathy (CIDP)
Protocol Number: 
ARGX-113-1802 
Amendment Number:
4 (protocol version 5.0) 
Acronym: 
ADHERE
Compound:
Efgartigimod (ARGX-113) 
Investigational Medicinal 
Product:
Efgartigimod PH20 SC (efgartigimod co-formulated with recombinant 
human hyaluronidase PH20 [rHuPH20] for subcutaneous [SC] 
administration) / Placebo (placebo with rHuPH20 for SC administration) 
Trial Phase: 
2
Sponsor:
argenx BVBA
Industriepark Zwijnaarde 7
9052 Zwijnaarde (Ghent)
Belgium 
Phone: +32 (0)9 310 34 00
Contract Research 
Organization: 
Pharmaceutical Product Development (PPD) Global Ltd 
Granta Park, Great Abington 
Cambridge, CB21 6GQ, United Kingdom   
Phone: +44 1223 374100 
Serious Adverse Event 
Reporting:
Parexel International
8 Federal Street, Billerica, MA 01821, United States of America
For drug safety reporting, contact the following email address:
Safety Mailbox/Fax: 
Email: safety@argenx.com 
Fax: +1 (833) 874-7325 
Regulatory Agency 
Identifiers:
EudraCT number: 2019-003076-39 
Protocol Approval Date:
12 Oct 2022

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
2
NOTIFICATION: POSSIBLE ADAPTATIONS OF TRIAL PROTOCOL 
DURING THE COVID-19 PANDEMIC
The aim of the ARGX-113-1802 trial is to investigate a new subcutaneous (SC) treatment option 
for patients with chronic inflammatory demyelinating polyneuropathy (CIDP). This SC treatment 
consists of efgartigimod with recombinant human hyaluronidase PH20 (rHuPH20) (called 
efgartigimod PH20 SC) and could offer clinically significant benefits to CIDP patients. 
argenx has performed a critical assessment of the use of efgartigimod during the COVID-19 
pandemic. Following careful evaluation, the risk/benefit profile of efgartigimod use in ongoing 
clinical trials has not changed in the context of this pandemic. This decision was made based on 
efgartigimod’s mechanism of action, the safety data generated to date, and provisions made in all 
clinical trials with efgartigimod for safety reporting and withholding treatment upon evidence of 
infection. This assessment will be reviewed regularly to consider new information about the 
pandemic and the ongoing, continuous assessment of adverse events reported during argenx 
clinical trials.
During the COVID-19 pandemic, it may not be possible to perform all assessments as planned 
for this trial (see Schedule of Activities [SoA] in Section 1.3).
In order to provide patients with CIDP the opportunity to continue the trial during the COVID-19 
pandemic, an Appendix with possible adaptations to the ARGX-113-1802 trial has been 
developed so that sites can follow this Appendix in case a patient cannot have a trial visit at the 
hospital site and a visit at home or an alternative convenient location will be performed. This 
Appendix describes a minimum number of assessments required to guarantee the safety and 
well-being of patients during the trial and to secure the collection of the critical parameters for 
analysis. This Appendix is included in Section 11.12 (Appendix 12) of this protocol. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
3
SIGNATURE OF SPONSOR
Protocol Title:
A Phase 2 Trial to Investigate the Efficacy, Safety, and Tolerability of 
Efgartigimod PH20 SC in Adult Patients With Chronic Inflammatory 
Demyelinating Polyneuropathy (CIDP) 
Protocol Number: 
ARGX-113-1802 
Acronym: 
ADHERE
Sponsor Representative:
See appended signature page
, MD, PhD
Chief Medical Officer, argenx BVBA
Date

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
4
SIGNATURE OF INVESTIGATOR
Protocol Title:  
A Phase 2 Trial to Investigate the Efficacy, Safety, and Tolerability of 
Efgartigimod PH20 SC in Adult Patients With Chronic Inflammatory 
Demyelinating Polyneuropathy (CIDP) 
Protocol Number: 
ARGX-113-1802 
Acronym: 
ADHERE
This protocol is a confidential document 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. 
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:

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
5
DOCUMENT HISTORY
Previous version number 
Effective date
1.0
30 Oct 2019 
2.0 (global protocol amendment 1) 
10 Jan 2020 
3.0 (global protocol amendment 2) 
04 May 2020 
4.0 (global protocol amendment 3) 
30 Nov 2020 
Current version number 
5.0 (global protocol amendment 4) 
12 Oct 2022 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
7
Section(s)
Change
Rationale
Section 1.3.1,
Section 1.3.2,
Section 11.12.1, 
Section 9.10
Stage B and Follow-up (normal and During COVID-19
Pandemic): 
… IgG testing must not be performed locally.
Section 9.10. Pharmacodynamics was revised to add the 
following:
Note that local IgG testing must not be performed.
(efgartigimod PH20 SC or 
placebo). 
Section 1.1, 
Section 6.1, 
Section 6.2, 
Section 11.3
The following changes have been made in these sections:
The inclusion criterion regarding the period of 
contraception use for WOCBP was updated: An 
acceptable method of contraception should now be used 
from signing the ICF until the date of the last IMP dose 
(instead of from baseline to 90 days after the last IMP 
dose). 
The previous inclusion criterion for male patients to not 
donate sperm during the trial period and 90 days 
thereafter was deleted. 
The exclusion criterion that women cannot become 
pregnant until at least 90 days after the last IMP dose 
was updated to not becoming pregnant during the trial. 
These changes are based on 
nonclinical teratogenicity and 
reprotoxicity data.
Section 1.1,
Section 1.2, 
Section 10.3
The following change was made in Section 1.1. Synopsis
and Section 1.2. Schema (footnote):
Approximately 360 patients aged 18 years and older are 
planned to be enrolled in Stage A with a maximum of 
180 randomized patients in Stage B. 
The following change was made in Section 1.1. Synopsis
and Section 10.3. Sample Size Determination:  
A maximum of 180 patients will be randomized in order 
to observe the 88 events in Stage B. To obtain a 
sufficient number of patients randomized into 
Stage B, up to approximately 360 patients would be 
required to be enrolled into Stage A. Patients will 
continue to be randomized into Stage B until 
88 events are observed as per the sample size 
calculation, the trial will end when the 88th event is 
observed.
In this event-driven trial, a total of 
88 events are required to detect a 
hazard ratio of 0.5 with 90% power 
at a 1-sided alpha level of 0.025 
using a log-rank test. The protocol 
has been updated to avoid 
ambiguity in the number of 
patients that need to be randomized 
to observe 88 events. This depends 
on several factors and cannot be 
exactly estimated (this protocol 
provides several scenarios under 
various assumptions around the 
median time to event). This change 
also clarifies that up to
approximately 360 patients are 
expected to be enrolled in Stage A
to ensure that the number of 
patients randomized in Stage B 
will be sufficient to observe the 
required 88 events.
Section 3.3.2
Section 3.3.2. Risks was updated to align with the current
argenx protocol template. 
These changes to the Risks 
section reflect additional safety 
data that have become available 
since the start of the trial. 
Section 5.1.1,
Section 11.1.6, 
Section 11.5
Section 5.1.1. Screening:
Note that additional assessments may be asked for to
support the confirmation of CIDP diagnosis (see
Section 11.1.6).
Section 11.1.6. CIDP Confirmation Committee (CCC): 
These changes clarify that 
additional tests may be performed
to confirm the CIDP diagnosis. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
8
Section(s)
Change
Rationale
In case the information provided to the CCC is not 
sufficient to confirm a definite or probable CIDP 
diagnosis per the EFNS/PNS 2010 criteria,2 
additional assessments may be asked for (as listed in 
Section 11.5 Appendix 5) to support the confirmation 
of diagnosis.
Section 11.5. Appendix 5: CIDP Diagnostic Tests was 
added. 
Addition of Table 2 from the EFNS/PNS 2010 
Guideline,2 which lists possible investigations to confirm 
CIDP diagnosis. 
Section 5.1.1.1,
Section 7.4, 
Section 9.1.1, 
Section 11.1.3, 
Section 11.4.1
Deletion of legally authorized/acceptable representative 
(according to local regulations). 
This trial is for adult patients 
capable of giving consent, and
therefore, a legally 
authorized/acceptable
representative is not needed. 
Section 5.3 
Section 5.3. Justification for Dose has been updated.
This section has been updated with 
the currently available data. 
Section 7.2
The following change was made in Section 7.2. 
Preparation, Handling, Storage, Administration, and 
Accountability:
Instructions about confirming appropriate temperature 
conditions were deleted, and a cross-reference to the 
Pharmacy Manual was added for further details.
New temperature stability data 
allow the IMP to be stored under 
less strict conditions. 
Section 7.3
The following was added in Section 7.3. IMP 
Compliance:
In case of lack of compliance, the number of missed 
doses will be captured, but the patient can remain in 
the trial (unless the patient withdraws his/her 
consent). 
This change clarifies that the 
patient can remain in the trial if 
there is a lack of IMP compliance. 
This is to avoid unnecessary 
dropouts. 
Section 1.1,
Section 6.2,
Section 7.4.2
Exclusion criterion #9 was updated to include: 
• Patients who (intend to) use prohibited medications 
and therapies (see Section 7.4.2) during the trial.
The following change was made to Section 7.4.2. 
Prohibited Medications: 
• Use of complementary therapies, including 
traditional Chinese medicines and herbal remedies, 
containing any of the following: naturally derived 
glucocorticoids; medication with clinical evidence-
based immunosuppressive, immunomodulatory, 
peripheral or central nervous system effects; or 
procedures (eg, acupuncture) for any neurological 
condition within 4 weeks or 5 half-lives (whichever 
is longer) prior to IMP dosing and agreed not to use 
during the trial.
Prohibited medications and 
therapies were updated to align this 
section among all geographic areas.
Section 8.2
The following change was made in Section 8.2. 
Permanent Early Discontinuation of IMP:
This change clarifies when a 
patient needs to discontinue IMP 
permanently. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
9
Section(s)
Change
Rationale
• Development of an SAE that is likely to result in a 
life threatening situation or pose a serious safety risk.
• Patient develops an SAE or AE that 
contraindicates further administration of IMP in 
the investigator’s opinion, or an AE of CTCAE 
grade 4 that is considered related to IMP by the 
sponsor.
Section 9.5.3, 
Section 11.2
The following changes were made in Section 9.5.3. 
Clinical Safety Laboratory Assessments: 
• The samples will be analyzed at a centralized certified 
laboratory. In the exceptional circumstances that 
samples cannot be sent to a central laboratory, a 
local laboratory can be used.
• Clinical laboratory tests will be reviewed for results 
of potential clinical significance at all time points 
throughout the trial, with the exception of total 
protein and albumin results after the Stage B
baseline visit, which will be kept blinded for the 
site. A system will be implemented to notify the 
investigator in case of out-of-range values to allow 
for appropriate safety follow-up.
The following footnote was added to “Total protein” and 
“Albumin” in Section 11.2. Appendix 2: Clinical 
Laboratory Tests:
In the exceptional circumstances that using a central 
laboratory is not possible: Do not measure total 
protein and albumin after the Stage B baseline visit.
These changes clarify the 
following:
A local laboratory can be used in 
the exceptional circumstance 
that a central laboratory cannot 
be used. 
As an additional blinding 
precaution, total protein and 
albumin results from a central 
laboratory will not be sent to the 
site after the Stage B baseline
visit, and total protein and 
albumin must not be measured 
after the Stage B baseline visit if
a local laboratory is used.
Section 11.3.2
Progesterone Progestogen-only hormonal 
contraception associated with inhibition of ovulation
Progesterone Progestogen-only oral hormonal 
contraception, where inhibition of ovulation is not the 
primary mode of action
Terminology was corrected.
Section 11.4
The following changes were made:
Section 11.4.1 Definition of AE
- Events to be Collected as AEs: 
Lack of efficacy by itself will not be reported as an 
AE or SAE. Such instances will be captured in the 
efficacy assessments. However, the signs, symptoms, 
and/or clinical sequelae resulting from lack of efficacy 
will be reported as an AE or SAE if they fulfill the 
definition of an AE or SAE. 
The following was deleted from the explanation of 
hospitalization in Section 11.4.2. Definition of SAE
- Requires inpatient hospitalization or prolongation of 
existing hospitalization
“(usually involving at least an overnight stay)” 
These changes to Appendix 4 for 
AEs/SAEs have been made to align
the definitions with the current 
argenx protocol template. 
Section 11.4.4
The following changes were made to Section 11.4.4. 
Reporting of SAEs and AESIs:
SAE and AESI Reporting via paper form: 
These changes clarify the SAE and 
AESI reporting procedures.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
10
Section(s)
Change
Rationale
• All SAEs and AESIs (Section 9.6.2) will be recorded 
(within 24 hours) on the paper SAE report form and 
the AE form in of the eCRF. SAEs will also be 
recorded on the paper SAE report form. 
• The investigator or designated site staff should check 
that will ensure all entered data are consistent. 
• An alert email for the SAE and AESI reports in on
the eCRF will then automatically be sent by email to 
the sponsor or designee’s SAE coordinator's safety 
mailbox via the electronic data capture (EDC) system. 
• The paper SAE report form should will be faxed or 
emailed to the sponsor’s designee SAE coordinator
(see the Serious Adverse Event Reporting details 
on the first page of this protocol). Contacts for SAE 
reporting can be found on the frontpage.
Appendix 12
This Appendix with the Administrative Structure has 
been deleted 
This information will be captured 
in the Trial Master File. 
Appendix 14 
An Appendix was added to provide the Country-Specific 
requirements
The specific requirements of 
certain countries were added in an 
Appendix of this global protocol to 
align with the new EU Clinical 
Trials Regulation. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
11
TABLE OF CONTENTS
NOTIFICATION: POSSIBLE ADAPTATIONS OF TRIAL PROTOCOL DURING 
THE COVID-19 PANDEMIC ......................................................................................2
SIGNATURE OF SPONSOR ..........................................................................................................3
SIGNATURE OF INVESTIGATOR ..............................................................................................4
TABLE OF CONTENTS ...............................................................................................................11
1.
PROTOCOL SUMMARY ..........................................................................................17
1.1.
Synopsis ......................................................................................................................17
1.2.
Schema ........................................................................................................................25
1.3.
Schedule of Activities (SoA) ......................................................................................26
1.3.1. 
SoA for Screening, Run-in, and Stage A ....................................................................26
1.3.2. 
SoA for Stage B and Follow-up..................................................................................29
2.
ABBREVIATIONS AND DEFINITIONS OF TERMS ............................................32
2.1.
Abbreviations ..............................................................................................................32
2.2.
Definitions of Terms ...................................................................................................35
3.
INTRODUCTION ......................................................................................................37
3.1.
Trial Rationale ............................................................................................................37
3.2.
Background .................................................................................................................38
3.3.
Benefit/Risk Assessment ............................................................................................39
3.3.1. 
Benefit .........................................................................................................................39
3.3.2. 
Risks ...........................................................................................................................40
4.
OBJECTIVES .............................................................................................................42
4.1.
Stage A: Open-Label Efgartigimod PH20 SC (4–12 Weeks, With Optional 
1 Additional Week) .....................................................................................................42
4.1.1. 
Primary Objective .......................................................................................................42
4.1.2. 
Secondary Objectives .................................................................................................42
4.1.3. 
Exploratory Objectives ...............................................................................................42
4.2.
Stage B: Double-Blind, Randomized-Withdrawal of Efgartigimod PH20 SC 
or Placebo (up to 48 Weeks) .......................................................................................42
4.2.1. 
Primary Objective .......................................................................................................42
4.2.2. 
Secondary Objectives .................................................................................................43
4.2.3. 
Exploratory Objectives ...............................................................................................43
5.
TRIAL DESIGN .........................................................................................................44

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
12
5.1.
Overall Design ............................................................................................................44
5.1.1.
Screening ....................................................................................................................44
5.1.2.
Run-in Period ..............................................................................................................46
5.1.3. 
Stage A ........................................................................................................................47
5.1.4. 
Stage B ........................................................................................................................48
5.1.5. 
Unscheduled Visit .......................................................................................................49
5.1.6.
Follow-up ....................................................................................................................49
5.2.
Scientific Rationale for Trial Design ..........................................................................50
5.3.
Justification for Dose ..................................................................................................51
5.4.
Measures to Minimize Bias: Randomization and Blinding ........................................52
5.4.1. 
Two Physician Concept ..............................................................................................53
5.4.2. 
Emergency Unblinding Procedure ..............................................................................54
5.5.
End of Trial Definition ...............................................................................................55
5.6.
Roll Over to Open-label Extension (OLE) Trial ........................................................55
5.7.
Protocol Deviations ....................................................................................................56
6.
TRIAL POPULATION ..............................................................................................57
6.1.
Inclusion Criteria ........................................................................................................57
6.2.
Exclusion Criteria .......................................................................................................58
6.3.
Lifestyle Considerations .............................................................................................59
7.
TREATMENTS AND THERAPIES DURING THE CONDUCT OF THE 
TRIAL .........................................................................................................................60
7.1.
IMP(s) Administered ..................................................................................................60
7.1.1.
Run-in Period ..............................................................................................................60
7.1.2. 
Stage A: Open-label ....................................................................................................61
7.1.3. 
Stage B: Double-blind, Randomized-withdrawal .......................................................62
7.2.
Preparation, Handling, Storage, Administration, and Accountability ........................62
7.3.
IMP Compliance .........................................................................................................63
7.4.
Prior Treatments and Concomitant Medications ........................................................63
7.4.1. 
Permitted Medication ..................................................................................................64
7.4.2. 
Prohibited Medications ...............................................................................................65
7.5.
Medical Care of Patients after End of Trial ................................................................66
7.6.
Dose Modification ......................................................................................................66
7.7.
Intervention After the End of the Trial .......................................................................66

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
13
8.
DISCONTINUATION OF IMP AND PATIENT 
DISCONTINUATION/WITHDRAWAL ..................................................................67
8.1.
Temporary Interruption of IMP ..................................................................................67
8.2.
Permanent Early Discontinuation of IMP ...................................................................68
8.3.
Early Withdrawal From the Trial ...............................................................................69
8.4.
Replacement ...............................................................................................................70
8.5.
Re-screening ...............................................................................................................70
8.6.
Lost to Follow-up .......................................................................................................70
9.
TRIAL ASSESSMENTS AND PROCEDURES .......................................................71
9.1.
Serology Testing for Infections at Screening .............................................................71
9.1.1. 
Vaccination History and Vaccinations During the Trial ............................................73
9.2.
Columbia-Suicide Severity Rating Scale (C-SSRS) at Screening ..............................73
9.3.
Medical History ..........................................................................................................73
9.4.
Efficacy Assessments .................................................................................................73
9.4.1. 
Adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) 
Disability Score ..........................................................................................................73
9.4.2. 
Medical Research Council (MRC) Sum Score ...........................................................74
9.4.3. 
Inflammatory Rasch-built Overall Disability Scale (I-RODS) ..................................75
9.4.4. 
Mean Grip Strength ....................................................................................................75
9.4.5. 
Timed Up and Go (TUG) Test ....................................................................................75
9.5.
Safety Assessments .....................................................................................................75
9.5.1. 
Vital Signs and Physical Examination ........................................................................75
9.5.2.
Electrocardiograms .....................................................................................................76
9.5.3. 
Clinical Safety Laboratory Assessments ....................................................................76
9.6.
Adverse Events and Serious Adverse Events .............................................................77
9.6.1. 
Pregnancy ...................................................................................................................77
9.6.2. 
Adverse Events of Special Interest (AESI) ................................................................77
9.7.
Medication Error .........................................................................................................78
9.8.
Patient Card ................................................................................................................78
9.9.
Pharmacokinetics ........................................................................................................78
9.10.
Pharmacodynamics .....................................................................................................79
9.11.
Genetics ......................................................................................................................79
9.12.
Biomarkers ..................................................................................................................79

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
14
9.13.
Immunogenicity Assessments: Anti-drug Antibodies (ADA) ....................................79
9.14.
Additional Patient-reported Outcome (PRO) Tools ...................................................80
9.14.1.
EuroQol 5 Dimensions and 5 Levels Health-related Quality-of-Life 
Questionnaire (EQ-5D-5L) .........................................................................................80
 
 
 
 
 
9.15.
Suicidality Assessment During the Trial ....................................................................81
10.
STATISTICAL CONSIDERATIONS .......................................................................82
10.1.
Statistical Methods ......................................................................................................82
10.1.1. 
Summary Tables, Figures, and Listings .....................................................................82
10.1.2. 
Hypothesis Testing and Confidence Intervals ............................................................82
10.1.3. 
Populations for Analyses ............................................................................................82
10.1.4. 
Randomization and Stratification ...............................................................................83
10.1.5. 
General Considerations ...............................................................................................83
10.1.6. 
Blinded Data Review Meeting ....................................................................................84
10.2.
Statistical Hypotheses .................................................................................................84
10.3.
Sample Size Determination ........................................................................................84
10.4.
Endpoints ....................................................................................................................85
10.4.1. 
Stage A ........................................................................................................................85
10.4.2.
Stage B ........................................................................................................................86
10.4.3. 
Exploratory Endpoints ................................................................................................87
10.5.
Statistical Analyses .....................................................................................................88
10.5.1. 
Demographic and Baseline Characteristics ................................................................88
10.5.2. 
Patient Disposition ......................................................................................................88
10.5.3. 
Populations for Analyses and Protocol Deviations ....................................................88
10.5.4. 
Efficacy Endpoints ......................................................................................................88
10.5.5. 
Stage A and Stage B: Other Efficacy and PK, PD, and Immunogenicity 
Endpoints ....................................................................................................................89
10.5.6. 
Stage A and Stage B: PRO EQ-5D-5L Endpoint .......................................................89
10.5.7. 
Stage A and Stage B: Safety Endpoints ......................................................................89

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
15
10.5.8. 
Exploratory Endpoints ................................................................................................90
10.6.
Interim Analyses .........................................................................................................90
10.7.
Independent Data Safety Monitoring Board (DSMB) ................................................90
11.
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS ..................................................................................................91
11.1.
Appendix 1: Regulatory, Ethical, and Trial Oversight Considerations ......................91
11.1.1.
Regulatory and Ethical Considerations ......................................................................91
11.1.2.
Financial Disclosure ...................................................................................................91
11.1.3. 
Informed Consent Process ..........................................................................................91
11.1.4. 
Data Protection ...........................................................................................................92
11.1.5. 
Independent Data and Safety Monitoring Board (DSMB) .........................................92
11.1.6. 
CIDP Confirmation Committee (CCC) ......................................................................93
11.1.7. 
Dissemination of Clinical Trial Data ..........................................................................93
11.1.8. 
Data Quality Assurance ..............................................................................................93
11.1.9. 
Source Documents ......................................................................................................94
11.1.10. 
Trial and Site Start and Closure ..................................................................................94
11.2.
Appendix 2: Clinical Laboratory Tests .......................................................................96
11.3.
Appendix 3: Contraceptive and Barrier Guidance ......................................................98
11.3.1. 
General Instructions and Definitions ..........................................................................98
11.3.2. 
Female Contraception for Women of Childbearing Potential ....................................98
11.3.3. 
Male Contraception ....................................................................................................99
11.4.
Appendix 4: Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting ......................................................................100
11.4.1. 
Definition of AE .......................................................................................................100
11.4.2. 
Definition of SAE .....................................................................................................101
11.4.3. 
Recording and Follow-up of AE and/or SAE ...........................................................102
11.4.4. 
Reporting of SAEs and AESIs ..................................................................................105
11.5.
Appendix 5: CIDP Diagnostic Tests .........................................................................106
11.6.
Appendix 6: CIDP Disease Activity Status (CDAS) ................................................107
11.7.
Appendix 7: Inflammatory Neuropathy Cause and Treatment (INCAT) 
Disability Scale .........................................................................................................108
11.8.
Appendix 8: Medical Research Council Scale .........................................................109
11.9.
Appendix 9: Inflammatory Rasch-built Overall Disability Scale (I-RODS) ............110

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
16
11.10. 
 
11.11.
Appendix 11: Columbia-Suicide Severity Rating Scale (C-SSRS ) .........................113
11.12.
Appendix 12: Possible Adaptations of Trial Protocol During COVID-19 
Pandemic ...................................................................................................................115
11.12.1. 
Schedule of Activities (SoA) During COVID-19 Pandemic ....................................123
11.13. 
Appendix 13: Protocol Amendment History ............................................................131
11.14.
Appendix 14: Country-Specific Requirements .........................................................155
11.14.1.
Denmark-Specific Protocol Requirements ...............................................................155
11.14.2. 
Germany-Specific Protocol Requirements ...............................................................155
11.14.3. 
Japan-Specific Protocol Requirements .....................................................................156
11.14.4. 
UK-Specific Protocol Requirements ........................................................................159
12.
REFERENCES .........................................................................................................160

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
17
1.
PROTOCOL SUMMARY
1.1.
Synopsis
Protocol number: ARGX-113-1802
Drug: ARGX-113/efgartigimod
Title of the trial: A Phase 2 Trial to Investigate the Efficacy, Safety, and Tolerability of Efgartigimod PH20 
SC in Adult Patients With Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
Number of patients (total):
Approximately 360 patients aged 18 years and older are planned to be enrolled in Stage A.
Investigator(s): Multicenter trial
Site(s) and region(s): Approximately 140 sites globally
Trial start (planned):  2019
Clinical phase:
Phase 2
Objectives:
Stage A (open-label, efgartigimod PH20 SC; 4-12 weeks [+ 1 optional additional week])
Primary objective: 
To assess the activity of efgartigimod PH20 SC (efgartigimod co-formulated with recombinant human 
hyaluronidase PH20 [rHuPH20]) based on the percentage of patients classified as treatment responders.
Secondary objectives: 
To assess the time to clinical improvement.
To determine the treatment effect of efgartigimod PH20 SC based on clinical functional assessments of 
motor function and muscle strength.
To assess the short-term safety and tolerability of efgartigimod PH20 SC.
To assess the pharmacokinetics (PK) of efgartigimod PH20 SC.
To assess the pharmacodynamic (PD) effect of efgartigimod PH20 SC.
To assess the immunogenicity of efgartigimod and rHuPH20.
To assess the EuroQol 5 dimensions and 5 levels health-related quality-of-life questionnaire (EQ-5D-5L). 
Stage B (double-blind, randomized-withdrawal, efgartigimod PH20 SC or placebo; up to 48 weeks)
Primary objective: 
To determine the efficacy of efgartigimod PH20 SC compared to placebo based on the time needed for the 
occurrence of the first evidence of clinical deterioration.
Secondary objectives: 
To determine the efficacy of efgartigimod PH20 SC compared to placebo based on clinical functional 
assessments of disease disability and motor function and muscle strength.
To assess the safety and tolerability of efgartigimod PH20 SC.
To assess the PK of efgartigimod PH20 SC.
To assess the PD effect of efgartigimod PH20 SC.
To assess the immunogenicity of efgartigimod and rHuPH20.
To assess the EQ-5D-5L.
Rationale
CIDP is considered an autoimmune disease. An unmet medical need exists for an efficacious treatment of CIDP 
with a favorable safety and tolerability profile and more convenient administration than that provided by current 
treatments. A weekly subcutaneous (SC) treatment option consisting of efgartigimod PH20 SC administered 
within a few minutes could offer clinically significant benefits to CIDP patients. In this trial, patients with CIDP 
will be administered efgartigimod PH20 SC at the dose of 1000 mg. This dose was well-tolerated in the prior 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
18
Phase 1 trial ARGX-113-1901 in healthy adult subjects and reduced immunoglobulins G (IgGs) to a level 
associated with clinical benefit in prior trials in patients with an autoimmune disease (ie, patients with 
generalized myasthenia gravis [gMG] and patients with primary immune thrombocytopenia [ITP]).
Investigational product, dose, and mode of administration:
The investigational medicinal product (IMP) by trial stage will be as follows:
Stage A:
1000 mg efgartigimod PH20 SC
Stage B:
1000 mg efgartigimod PH20 SC, and
placebo (containing an equivalent amount of rHuPH20) SC
Methodology:
This is a Phase 2, prospective, multicenter trial on the efficacy, safety, tolerability, immunogenicity, PK, and PD 
of efgartigimod PH20 SC administered SC in patients aged 18 years and older with CIDP.
This trial will be conducted in 2 stages: An open-label Stage A and a randomized-withdrawal, double-blind, 
placebo-controlled Stage B.
During the screening period of a maximum of 28 days, diagnosis of CIDP will be confirmed by a CIDP 
confirmation committee (CCC), and overall eligibility will be confirmed by the medical monitor.
Eligible patients receiving treatment for CIDP at screening will discontinue that treatment and enter the run-in 
period for up to 12 weeks until evidence of clinically meaningful deterioration (ECMD)* is confirmed 
(ie, observed during a trial visit), at which time eligible patients will enter Stage A at baseline (D1A). Eligible 
patients who are treatment-naïve or discontinued treatment with corticosteroids and/or intravenous 
immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg) at least 6 months prior to screening (who are 
considered equal to treatment-naïve patients) will enter Stage A directly, if during screening documented 
evidence for worsening on the total adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) 
disability score, further referred to as “adjusted INCAT score,” within 3 months prior to screening is available 
compared to previous adjusted INCAT score within 6 months prior to screening.
Patients eligible for Stage A will receive open-label IMP as weekly SC administrations of efgartigimod PH20 
SC for up to 12 weeks (with optional 1 additional week for confirmation of evidence of clinical improvement 
[ECI†], if needed), with a minimum of 4 administrations. During Stage A, patients will be monitored for ECI.
* Evidence of clinically meaningful deterioration (ECMD) is defined as fulfilling of any of the following criteria during the run-
in period only: 1)
point from the first visit of the run-in period (RI-V1), and/or 2) I-RODS 
points (using the centile metric) from RI-V1, and/or 3)
8 kiloPascal (kPa) in 1 
hand using the handheld vigorimeter from RI-V1.
† Evidence of clinical improvement (ECI) will be determined during Stage A is defined as follows:
For non-naïve patients:
Patients who deteriorate in adjusted INCAT score during the run-
point versus the first visit of the run-in 
period [RI-V1]) can only be entered in Stage B if they show improvement in adjusted INCAT score during Stage A (decrease 
point versus Stage A baseline [D1A]). These patients can enter Stage B at the time the improvement on the adjusted INCAT 
score is confirmed.
Patients who have no change in adjusted INCAT score during the run-in period can be entered in Stage B in the following 
cases: 
When improvement on the adjusted INCAT score 
point) versus D1A is confirmed.
When no change in adjusted INCAT score is observed during Stage A and:
When improvement during Stage A on I-
points versus D1A) is confirmed in case deterioration on 
only I-
points) was observed during run-in.
When improvement during Stage
kPa versus D1A) is confirmed in case deterioration 
kPa) was observed during run-in.
When improvement during Stage A on either I-
points versus D1A) or grip strength (increase 
kPa versus D1A) is confirmed in case deterioration was observed on both I-
points) and grip 
kPa) during run in.
For naïve patients: 
Naïve patients, who did not enter the run-in period and who show an improvement during Stage A of at least 1 grade on the 
adjusted INCAT score (ie, decrease by 
point) compared to D1A, can enter Stage B at the time the improvement on the 
adjusted INCAT score (decrease 
point) is confirmed.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
19
Patients who fulfilled the criteria for ECI at 2 consecutive visits (confirmed ECI status), will roll over to the 
randomized-withdrawal, placebo-controlled Stage B. Patients who do not have confirmed ECI are not eligible 
for Stage B and will end the trial after performing the safety follow-up visit 28 days after the last administration 
of the IMP.
After the first 30 patients have reached the end of Stage A, an interim analysis will be conducted on the 
proportion of patients with confirmed ECI using the exact (Clopper-Pearson) 90% 1-sided lower confidence 
interval (CI) for a go/no-go decision to continue the trial. During the interim analysis, the trial will continue 
without any interruption, neither for trial enrollment nor for visits or treatments of patients participating in any 
trial period.
Patient for whom ECI in Stage A has been confirmed, will enter the double-blind, randomized-withdrawal 
Stage B and will be randomized at Stage B baseline (D1B) in a 1:1 ratio to receive weekly IMP consisting of 
efgartigimod PH20 SC or placebo. The randomized-withdrawal Stage B will last for up to 48 weeks.
All patients randomized to the double-blind, randomized-withdrawal Stage B will be dosed with IMP weekly 
but will return to the clinic in 4-week intervals (every 4 weeks). Administration of randomized IMP treatment 
can only occur after completion of all indicated assessments. Patients will be discharged from the center if there 
are no safety concerns in the opinion of the investigator. In between the trial visits in Stage B, patients will be 
given the option to come to the trial center weekly for drug administration or will be provided with home nurse 
service for IMP injecting. Upon agreement with the investigator, site personnel, and the patient, the most 
suitable solution will be provided. Administration of IMP will occur always within a time window of ± 2 days 
with respect to the pre-planned date of administration.
Patients completing Week 48 and in the opinion of the investigator benefit from trial treatment at Week 48 or 
patients having an event of worsening on the adjusted INCAT score of 1 point or a worsening on the adjusted 
INCAT score
points compared to Stage B baseline (for the latter, no confirmation is needed) will be 
allowed to roll over to the open-label extension (OLE) trial when they are receiving IMP. Patients completing 
Week 48 who will not roll over to the OLE trial as well as patients with an early discontinuation, will have a 
safety follow-up visit 28 days after the last IMP administration, will stop the trial, and will be treated as 
considered appropriate by the investigator.
When eighty-eight (88) events have been observed for the primary endpoint analysis of Stage B (see sample size 
section), then the trial will stop. In that case, patients in Stage A and Stage B will perform an early 
discontinuation visit and patients who are receiving IMP will be given the opportunity to continue efgartigimod 
PH20 SC treatment in the OLE trial. Additionally, at the time of the 88th event, patients in run-in will also be 
given the option to roll over to the OLE trial after performing an early discontinuation visit. Patients who will 
not roll over to the OLE trial, will attend a follow-up visit 28 days after the last IMP dose.
From Stage A onwards, patients will receive training for self-administration of IMP, which is foreseen in the 
OLE trial (not in the ARGX-113-1802 trial).
Inclusion and exclusion criteria:
Inclusion criteria:
Patients are eligible to be included in the trial only if all of the following criteria apply:
1.
Ability to understand the requirements of the trial, provide written informed consent (including consent 
for the use and disclosure of research-related health information), willingness and ability to comply 
with the trial protocol procedures (including required trial visits).
2.
Male or female patient aged 18 years or older, at the time of signing the informed consent.
3.
Diagnosed with probable or definite CIDP according to criteria of the European Federation of 
Neurological Societies/Peripheral Nerve Society (EFNS/PNS, 2010),2 progressing or relapsing forms.
4.
CIDP Disease Activity Status (CDAS)3
5.
 at the first run-in visit (RI-V1; for patients entering run-in) or Stage A baseline 
(A-V1; for treatment-naïve patients with documented evidence for worsening on the total adjusted 
INCAT disability score within 3 months prior to screening). Patients with an INCAT score of 2 at trial 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
20
entry must have this score exclusively from the leg disability score; for patients with an INCAT score 
6.
Fulfilling any of the following treatment conditions:
Currently (ie, within the last 6 months) treated with pulsed corticosteroids, oral corticosteroids 
mg/day, and/or IVIg or SCIg, and the patient is willing to 
discontinue this treatment at the first run-in visit (RI-V1); OR
Without previous treatment (treatment-naïve); OR
Treatment with corticosteroids and/or IVIg or SCIg discontinued at least 6 months prior to screening.
Note: Patients not treated with monthly or daily corticosteroids, IVIg or SCIg for at least 6 months prior to 
screening are considered as equal to treatment-naïve patients.
7.
Women of childbearing potential who have a negative serum pregnancy test at screening and a negative 
urine pregnancy test up to Stage A baseline (D1A).
8.a. Women of childbearing potential must use an acceptable method of contraception from signing the ICF 
until the date of the last dose of IMP.
9.
Inclusion criterion removed in protocol amendment 4. 
Exclusion criteria:
Patients are excluded from the trial if any of the following criteria apply:
1.
Pure sensory atypical CIDP (EFNS/PNS definition).2
2.
Polyneuropathy of other causes, including the following:
Multifocal motor neuropathy;
Monoclonal gammopathy of uncertain significance with anti-myelin-associated glycoprotein 
immunoglobulin M (IgM) antibodies;
Hereditary demyelinating neuropathy;
Polyneuropathy, organomegaly, endocrinopathy, monoclonal protein and skin change 
syndromes;
Lumbosacral radiculoplexus neuropathy;
Polyneuropathy most likely due to diabetes mellitus;
Polyneuropathy most likely due to systemic illnesses;
Drug- or toxin-induced polyneuropathy.
3.
Any other disease that could better explain the patient’s signs and symptoms.
4.
Any history of myelopathy or evidence of central demyelination.
5.
Current or past history (within 12 months of screening) of alcohol, drug or medication abuse.
6.
Severe psychiatric disorder (such as severe depression, psychosis, bipolar disorder), history of suicide 
attempt, or current suicidal ideation that in the opinion of the investigator could create undue risk to the 
patient or could affect adherence with the trial protocol.
Note: At screening, suicidality will be assessed using the Columbia-suicide severity rating scale (C-SSRS); 
patients with a high suicide risk will be excluded from the trial (ie, patients will be excluded with a positive 
answer to questions #4 and/or #5 of the suicidal ideation subscale [over the past 3 months]; and/or any 
positive answer to the suicidal behavior subscale [over the past year]). Any positive answer to the above 
questions under “Lifetime/Time he/she felt most suicidal” should be carefully evaluated for any current risk 
of suicide by the investigator prior to trial entry.
7.
Patients with clinically significant active or chronic uncontrolled bacterial, viral, or fungal infection at 
screening, including patients who test positive for an active viral infection at screening with:
Active Hepatitis B Virus (HBV): serologic panel test results indicative of an active (acute or 
chronic) infection;
Active Hepatitis C Virus (HCV): serology positive for HCV-Ab;

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
21
Human Immunodeficiency Virus (HIV) positive serology associated with an Acquired 
Immune Deficiency Syndrome (AIDS)-defining condition or with a cluster of differentiation 4
cells/mm3. 
8.
Total IgG level <6 g/L at screening.
9.a. Treatment with the following:
Within 3 months (or 5 half-lives of the drug, whichever is longer) before screening: plasma 
exchange or immunoadsorption, any concomitant fragment crystallizable (Fc)-containing 
therapeutic agents or other biological, or any other investigational product;
Within 6 months before screening: rituximab, alemtuzumab, any other monoclonal antibody, 
cyclophosphamide, interferon, tumor necrosis factor–alpha inhibitors, fingolimod, methotrexate, 
azathioprine, mycophenolate, any other immunomodulating or immunosuppressive medications, 
and oral daily corticosteroids >10 mg/day.
Note:
mg/day can be 
included.
Patients who (intend to) use prohibited medications and therapies (see Section 7.4.2) during the 
trial.
10. a. Pregnant and lactating women and those intending to become pregnant during the trial.
11. Patients with any other known autoimmune disease that, in the opinion of the investigator, would 
interfere with an accurate assessment of clinical symptoms of CIDP.
12.a. Patients who received a live-attenuated vaccine fewer than 28 days before screening. Receiving an 
inactivated, sub-unit, polysaccharide, or conjugate vaccine any time before screening is not 
exclusionary.
13. Patients who have a history of malignancy unless deemed cured by adequate treatment with no 
years before the first IMP administration. Patients with the following 
cancer can be included anytime:
Adequately treated basal cell or squamous cell skin cancer,
Carcinoma in situ of the cervix,
Carcinoma in situ of the breast, or
Incidental histological finding of Prostate cancer (TNM [tumor, nodes, and metastases 
classification] stage T1a or T1b).
14. Patients who previously participated in a trial with efgartigimod and have received at least 1
administration of IMP.
15. Patients with known medical history of hypersensitivity to any of the ingredients of IMP.
16. Patients with clinical evidence of other significant serious disease or patients who underwent a recent 
or have a planned major surgery, or any other reason which could confound the results of the trial or 
put the patient at undue risk.
Maximum duration of patient involvement in the trial: After a screening period of up to 28 days and a run-in 
period up to 12 weeks, the total duration of IMP dosing is up to 61 weeks and includes 2 treatment stages: 
Stage A will be up to 12 weeks (with optional 1 additional week) open-label treatment of efgartigimod PH20 SC 
and Stage B will be up to 48 weeks of double-blind treatment with IMP (efgartigimod PH20 SC or placebo). 
Follow-up period for patients not rolling over into the extension trial or for patients who prematurely 
discontinue IMP, will be 28 days after the last dose of IMP.
The maximum total trial duration is 80 weeks with a maximum of 61 weeks on IMP: 
Screening period: up to 28 days
Run-in period: up to 12 weeks (not required for treatment-naïve patients)
Stage A: 4–12 weeks (with optional 1 additional week)
Stage B: up to 48 weeks
Follow-up period: 28 days after the last dose of IMP for patients who do not enroll into the OLE trial 
ARGX-113-1902.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
22
Endpoints and statistical analysis
Populations for Analyses
Safety population: The Stage A safety population (SAF-A) will include all patients who received at least 1 dose 
of IMP in Stage A. The Stage B safety population (SAF-B) will include all patients who received at least 
1 dose of IMP in Stage B.
Modified intent-to-treat (mITT) population: The mITT population will include all randomized patients who 
received at least 1 dose of IMP in Stage B.
Per protocol (PP) population: The PP population comprises all Stage B patients in the mITT population for whom 
no major protocol deviation was reported.
Note: Below the primary and secondary endpoints are listed of Stage A and Stage B. In addition, there are 
exploratory endpoints 
 that are described in the body text of the 
protocol.
Stage A 
Primary endpoint: Percentage of patients with confirmed ECI.
Secondary endpoints: 
Evidence of clinical activity:
Time to initial confirmed ECI.
Change from Stage A baseline (D1A) over time in:
o
Adjusted INCAT score
o
Medical Research Council (MRC) sum score
o
24-item Inflammatory Rasch-built Overall Disability Scale (I-RODS) disability scores
o
Timed Up and go (TUG) score
o
Mean grip strength assessed by Martin vigorimeter
Safety:
Exposure adjusted occurrence of treatment-emergent adverse events (TEAEs) and serious adverse 
events (SAEs) by system organ class (SOC) and preferred term (PT);
Incidence of clinically significant laboratory abnormalities.
PK profile:
Pre-dosing efgartigimod serum concentrations over time during Stage A.
PD profile:
Changes of serum IgG levels (total IgG) over time during Stage A.
Immunogenicity:
Percentage of patients with and titers of binding antibodies (BAb) toward efgartigimod and/or 
rHuPH20 during Stage A.
Presence of neutralizing antibodies (NAb) against efgartigimod and titers of NAb against rHuPH20 
during Stage A.
PRO:
Changes from D1A in EQ-5D-5L over time during Stage A. 
Stage B
Primary Endpoint: 
Time to first adjusted INCAT deterioration compared to Stage B baseline. 
Note: Time to first adjusted INCAT deterioration is defined by the time from first dose of double-blind IMP to the 
first adjusted INCAT score increase of 1 point compared to Stage B baseline, if the deterioration is confirmed at a 
consecutive visit 3-7 days after the first adjusted INCAT score increase of 1 point. For patients with an increase of 
2 or more points on the adjusted INCAT score compared to Stage B baseline, no confirmation is required.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
23
Secondary Endpoints:
Clinical Efficacy:
Time to CIDP disease progression.
Note: Time to CIDP disease progression is defined by the time from first dose of double-blind IMP to the first 
I-
points compared to Stage B baseline using the centile metric.
Percentage of patients with improved functional level compared to Stage B baseline as measured by an 
increase in the 24-item I-RODS score up to Week 48.
Change from Stage B baseline over time in:
o
Adjusted INCAT score
o
MRC Sum score
o
24-item I-RODS disability scores
o
TUG score
o
Mean grip strength assessed by Martin vigorimeter
Time to 10% decrease in the 24-item I-RODS during Stage B.
Safety:
Incidence of TEAEs and SAEs by SOC and PT during Stage B.
Incidence of clinically significant laboratory abnormalities during Stage B.
PK Profile:
Pre-dosing efgartigimod serum concentrations over time during Stage B.
PD Profile:
Changes of serum IgG levels (total IgG) over time during Stage B.
Immunogenicity:
Percentage of patients with and titers of BAb toward efgartigimod and/or rHuPH20 during Stage B.
Presence of NAb against efgartigimod and titers of NAb against rHuPH20 during Stage B.
PRO:
Changes from Stage B baseline in EQ-5D-5L over time during Stage B. 
Hypothesis: 
Stage A 
For the interim analysis, the percentage of ECI responders on efgartigimod PH20 SC will be summarized 
using an exact Clopper-Pearson 90% 1-sided lower CI. For the final analysis, the percentage of ECI 
responders on efgartigimod PH20 SC will be summarized using an exact Clopper-Pearson 2-sided 95% CI.
Stage B 
Null hypothesis: The event rate of efgartigimod PH20 SC compared to placebo is 1 (ie, hazard ratio = 1).
Alternative hypothesis: The event rate of efgartigimod PH20 SC compared to placebo is 1 (ie, hazard 
ratio 1).
Stage A and Stage B testing will be on different populations and hence are not considered to be multiple 
comparisons. Therefore, no adjustment for multiplicity will be made.
Primary Efficacy Analyses:
The primary endpoint of time to an adjusted INCAT deterioration compared to Stage B baseline will be 
analyzed via Cox regression modeling in the mITT population. Patients without adjusted INCAT deterioration 
will be censored at week 48. The analysis will be stratified for randomization stratification factors (ie, according 
to their prior CIDP medication and the adjusted INCAT score during Stage A). A fixed effect term will be 
included as a covariate for randomized treatment. The hazard ratio will be estimated from the model along with 
the associated 95% CI and 2-sided p-value. The data will also be displayed using Kaplan-Meier curves and 
median times will be estimated.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
24
Secondary Efficacy Analyses
The time to CIDP disease progression during Stage B up to week 48, defined by I-RODS deterioration of 
points compared to Stage B baseline, will be analyzed in the same fashion as the primary endpoint.
The percentage of patients with improved functional level (compared to Stage B baseline) as measured by the 
I-RODS score during Stage B up to week 48 will be analyzed by exact logistic regression. A fixed effect term 
will be included for randomized treatment and Stage B baseline I-RODS score will be included as a covariate. 
The odds ratio will be estimated from the model along with the associated 95% CI and 2-sided p-value. Exact 
Clopper-Pearson 2-sided 95% CI limits will be calculated for the proportion of patients with disease progression 
in each arm.
The change from Stage B baseline over time in clinical functional assessments of motor function and muscle 
strength and PROs will be summarized descriptively in addition to the analysis for time to 10% decrease in 
24-item I-RODS.
PRO: EQ-5D-5L Analysis 
EQ-5D-5L scores and changes from baseline (ie, changes from D1A over time during Stage A and changes from 
Stage B baseline over time during Stage B) will be presented using standard summary statistics. 
Safety Analyses
Summaries of adverse events (AEs) and other safety parameters will be provided for Stage A (SAF-A), Stage B
(SAF-B) (by treatment arm), and Stage A and Stage B combined (SAF-A and SAF-B) (for efgartigimod PH20 
SC treatment).
AEs will be classified using the latest version of the Medical Dictionary for Regulatory Activities (MedDRA) 
classification system. AEs reported from the first dose of IMP until 30 days after the last dose of IMP will be 
considered as TEAEs and will be summarized descriptively. TEAEs and Adverse Events of Special Interest 
(AESIs) will be listed corresponding to SOC and MedDRA PT. Multiple occurrences of a single PT in a patient 
will only be counted once at the maximum severity/grade. The severity will be assessed using the common 
terminology criteria for AEs (CTCAE). All AEs will be summarized by relatedness to IMP. Any AEs leading to 
death or discontinuation of IMP will also be summarized. Clinically significant laboratory abnormalities will be 
summarized descriptively.
PK, PD, and Immunogenicity Analysis
PK, PD, and immunogenicity parameters will be summarized descriptively.
Sample Size Considerations:
If it is hypothesized that the event rate of efgartigimod PH20 SC compared to placebo is 0.50 (ie, hazard ratio of 
0.50), then 88 events are required to provide 90% power at a 1-sided alpha level of 0.025 using a log-rank test. 
An event is defined as an adjusted INCAT increase during Stage B. The events will be monitored in a blinded 
way to ensure the trial is sufficiently powered. The expected sample size assumes a 48-week maximum follow-
up period for each patient, an accrual rate of 4 patients per month during the first 6 months and an accrual rate 
of 7.8 patients per month thereafter. To obtain a sufficient number of patients randomized into Stage B, up to 
approximately 360 patients would be required to be enrolled into Stage A. Patients will continue to be 
randomized into Stage B until 88 events are observed as per the sample size calculation, the trial will end when 
the 88th event is observed.
Date of Protocol: 12 Oct 2022 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
25
1.2.
Schema
Abbreviations: d = day; efgartigimod PH20 SC = efgartigimod with rHuPH20 (co-formulation) for SC administration; OLE=open-label extension; 
placebo = placebo with rHuPH20; Q1W = once a week; rHuPH20 = recombinant human hyaluronidase PH20; SC = subcutaneous(ly); q1w=once weekly;
w = week.
Note: Patients who show ECI only at the last visit of the 12-weeks Stage A period may be allowed to extend Stage A for a further week with 1 additional 
consecutive visit in order to get ECI confirmed at a consecutive visit. Only patients with confirmed ECI will be randomized and receive double-blind IMP in 
Stage B.
Note: Approximately 360 patients aged 18 years and older are planned to be enrolled in Stage A.
Note: After the first 30 patients have reached the end of Stage A, an interim analysis will be conducted on the proportion of patients with confirmed ECI for a 
go/no-go decision to continue the trial.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
26
1.3.
Schedule of Activities (SoA)
1.3.1.
SoA for Screening, Run-in, and Stage A 
Screeninga
Run-in 
Period 
weeksb
Stage A: Open-Label Period 
Weeks (With Optional 1 Additional Week)c
Unsche-
dulede
Safety 
Follow-
upf
RI-V1 RI-V2 
to 
RI-V4
A-V1 A-V2 A-V3 A-V4 A-V5 A-V6c A-V7c A-V8c A-V9c A-V10c A-V11c A-V12c A-V13c
(Addi-
tional)
EOSA/
EDd
UnschV 28 (±3)
Days 
After 
Last IMP 
Dose
Up to 
28 days
D1A
D8
D15
D22
D29
D36c D43c D50c
D57c
D64c
D71c
D78c
D85
Assessment/Procedure
±0 
days
±2 
days
±0 
days
±2 days
Informed consent
Demographics
In-/exclusion criteria
Medical historyg
12-lead ECGs
CDAS
Physical exam and vital 
signs
h
i
i
i
i
i
i
i
i
i
i
i
i
i
i
i
i
i
i
Pregnancy test
j
k
k
k
k
k
k
k
k
Adjusted INCAT score
(
)l
(
)l
(
)l
(
)l
MRC Sum score
(
)l
(
)l
(
)l
(
)l
I-RODS score
Mean grip strength
TUG test
EQ-5D-5L
m

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
29
n. At screening, suicidality will be assessed with the Columbia-suicide severity rating scale (C-SSRS) (see Section 9.2). During the trial, suicidality will be assessed by specifically 
answering 1 question from the PHQ-9 depression questionnaire (see Section 9.15). 
o. At screening, total IgG will be measured (by central laboratory as part of the blood chemistry tests) to determine eligibility.
p. Serology can be retested only during the screening period.
q. For PK, pre-dose (within 2 hours prior to start of IMP administration at the trial visits) samples will be taken. At these time points, blood samples will also be taken for PD 
analysis. PD analysis includes the measurement of total IgG. IgG testing must not be performed locally.
r. Blood samples for immunogenicity testing will be taken pre-dose at the trial visits to measure ADA against efgartigimod (measured in serum) and antibodies against rHuPH20 
(measured in plasma).
s. Optional blood samples will be taken for autoantibodies testing (serum) and serum-sample storage for future testing.
t. Patients will be trained to self-administer IMP (foreseen in the OLE trial; not in the ARGX-113-1802 trial) during the first 4 visits when IMP is administered; thereafter, training
for self-administration is optional (only if needed).
u. IMP will be administered weekly at the site in Stage A (IMP administration will be after blood samples have been taken for laboratory safety, PK, PD, immunogenicity, and/or 
biomarker analyses and after all assessments needed for determination of ECI). Patients will receive a minimum of 4 IMP administrations in Stage A. Note that IMP in Stage A
will not be administered if ECI is confirmed at the visit (and the patient has received at least 4 IMP administrations). When ECI is confirmed (ie, ECI observed at the second 
consecutive visit), the patient will be randomized and receive the first double-blind IMP administration in Stage B (ie, the visit at which ECI is confirmed will be a combination of 
the EOSA visit and the Stage B baseline [D1B] visit [see Section 1.3.2]). 
v. AEs and intake of concomitant medication(s) will be monitored continuously from signing the ICF until the last trial-related activity. In case of early discontinuation, any 
AEs/SAEs should be assessed for 30 days following the ED visit or until satisfactory resolution or stabilization.
w.Blood samples may also be used to cross-validate the PK, PD, biomarker, and ADA assays in CIDP matrix (serum and plasma).
1.3.2.
SoA for Stage B and Follow-up
Stage B: Randomized-Withdrawal Treatment 
Weeks
UNS
Safety 
Follow-upd
B-V1
B-V2
B-V3
B-V4
B-V5
B-V6
B-V7
B-V8
B-V9
B-V10
B-V11
B-V12
B-V13
UNS Vc
28 (±3) Days 
After Last 
IMP Dose
D1Ba
W4
W8
W12
W16
W20
W24
W28
W32
W36
W40
W44
W48/EDb
Assessment/Procedure
±0 days
±2 days
Randomization
12-lead ECGs
Physical exam and vital signse
Pregnancy testf
Adjusted INCAT score
MRC sum score

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
32
2.
ABBREVIATIONS AND DEFINITIONS OF TERMS
2.1.
Abbreviations
Abbreviation
Expansion/Definition
21 CFR
Title 21 of the Code of Federal Regulations
Ab
Antibody
AChR-Ab
anti-acetylcholine receptor antibody
Ag
Antigen
ADA
anti-drug antibodies
AE
adverse event
AESI
adverse event of special interest
AIDS
Acquired Immune Deficiency Syndrome
ASCT
autologous stem cell transplant
BAb
binding antibodies
CCC
CIDP confirmation committee
CD4
cluster of differentiation 4
CD8
cluster of differentiation 8
CDAS
CIDP disease activity status
CDER
Center for Drug Evaluation and Research
CI
confidence interval
CIDP
chronic inflammatory demyelinating polyneuropathy
CIOMS
Council for International Organizations of Medical Sciences
CNS
central nervous system
CRO
contract research organization
C-SSRS
Columbia-suicide severity rating scale
CTCAE
common terminology criteria for adverse events
CTR
clinical trial report
D1A
baseline of stage A
D1B
baseline of stage B
DSMB
Data Safety Monitoring Board
ECG
Electrocardiogram
ECI
evidence of clinical improvement
ECMD
evidence of clinically meaningful deterioration
eCRF
electronic case report form
ED
early discontinuation
efgartigimod PH20 SC efgartigimod co-formulated with rHuPH20 for SC administration
EFNS/PNS
European Federation of Neurological Societies/Peripheral Nerve Society

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
33
EOSA
end of Stage A 
EQ-5D-5L
EuroQol 5 dimensions and 5 levels health-related quality-of-life questionnaire
EU
European Union
Fc
fragment crystallizable
Fc gamma receptor
FcRn
neonatal Fc receptor
FDA
Food and Drug Administration
FSH
follicle stimulating hormone
GBS
Guillain-Barré syndrome
GCP
good clinical practice
gMG
generalized myasthenia gravis
HBV
hepatitis B virus
HCV
hepatitis C virus
HDL
high-density lipoprotein cholesterol
HIV
human immunodeficiency virus
IB
Investigator’s Brochure
ICF
informed consent form
ICH
International Council for Harmonisation of Technical Requirements for Pharmaceuticals for 
Human Use
IEC
Independent Ethics Committees
Ig
Immunoglobulin
IgG
immunoglobulin G
IgM
immunoglobulin M
IMP
investigational medicinal product
INCAT
inflammatory neuropathy cause and treatment
IRB
Institutional Review Board
I-RODS
Inflammatory-Rasch-built Overall Disability Scale
IRR
infusion-related reaction
IRT
interactive response technology
ITP
immune thrombocytopenia
IUD
intrauterine device
IUS
Intrauterine hormone-releasing system
IV
intravenous(ly)
IVIg
intravenous immunoglobulin
LDL
low-density lipoprotein cholesterol
MedDRA
Medical Dictionary for Regulatory Activities

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
34
MG
myasthenia gravis
MG-ADL
Myasthenia Gravis Activities of Daily Living
MGUSP
gammopathy-related polyneuropathy
mITT
modified intent-to-treat
MRC
Medical Research Council
NAb
neutralizing antibodies
NCI
National Cancer Institute
OLE
open-label extension
PD
pharmacodynamic(s)
PHQ-9 
Patient Health Questionnaire-9 
PK
pharmacokinetic(s)
PP
per protocol
PRO
patient-reported outcome
PT
preferred term
OLE
open-label extension
QTcF
Fridericia corrected QT interval
rHuPH20
recombinant human hyaluronidase PH20
SAE
serious adverse event
SAF-A 
Stage A safety population
SAF-B 
Stage B safety population
SAP
statistical analysis plan
SC
subcutaneous(ly)
SCIg
subcutaneous immunoglobulin
SoA
schedule of activities
SOC
system organ class
SOP
standard operating procedure
SUSAR
suspected unexpected serious adverse reactions
TB
Tuberculosis
TEAE
treatment-emergent adverse event
TUG
timed up-and-go
Unsch
Unscheduled
US
United States
V 
Visit
W 
week
WHO
World Health Organization

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
35
2.2.
Definitions of Terms
Evidence of clinically meaningful deterioration during the run-in period, evidence of clinical 
improvement during Stage A, and adjusted INCAT deterioration during Stage B are defined as follows: 
Term
Definition
ECMD
Evidence of clinically meaningful deterioration (ECMD) is defined as the fulfilling of any of the 
following criteria during the run-in period only:
Total adjusted
-in period (RI-
V1), (Section 9.4.1), and/or
I-
-V1 (Section 9.4.3), and/or
1 hand using the handheld vigorimeter from RI-V1 
(Section 9.4.4).
Note: Any patient showing ECMD at the trial site during the run-in period will enter Stage A immediately.
ECI
For non-naïve patients:
Patients who deteriorate in adjusted INCAT score during the run-
point versus 
the first visit of the run-in period [RI-V1]) can only be entered in Stage B if they show improvement 
in adjusted INCAT score during Stage
point versus Stage A baseline [D1A]). These 
patients can enter Stage B at the time the improvement on the adjusted INCAT score is confirmed.
Patients who have no change in adjusted INCAT score during the run-in period and deteriorated on 
I-RODS and/or grip strength during run-in can be entered in Stage B in the following cases:
point) versus D1A is confirmed.
When no change in adjusted INCAT score is observed during Stage A and:
o
When improvement during Stage A on I-
points versus D1A) is 
confirmed in case deterioration on only I-
points) was observed during 
run-in.
o
When improvement during Stage
kPa versus D1A) is 
kPa) was observed 
during run-in.
o
When improvement during Stage A on either I-RODS 
points versus D1A) or 
kPa versus D1A) is confirmed in case deterioration was observed 
on both I-
kPa) during run-in.
For naïve patients: 
Naïve patients, who did not enter the run-in period and who show an improvement during Stage A of 
at least 1 grade on the adjusted INCAT score (ie, decrease by 
point) compared to D1A, can enter 
Stage B at the time the improvement on the adjusted INCAT score (decrease 
point) is confirmed.
Adjusted 
INCAT 
deterioration
A deterioration of the adjusted INCAT score is defined as an increase (ie, worsening) of 1 point on 
the adjusted INCAT score compared to Stage B baseline which is confirmed at a consecutive visit 
3-7 days after the first adjusted INCAT score increase of 1 point. For patients with an increase of 
2 or more points on the adjusted INCAT score compared to Stage B baseline, no confirmation is 
required.
D1A = baseline of Stage A; ECI = evidence of clinical improvement; ECMD = evidence of clinically meaningful deterioration; 
I-RODS = Inflammatory Rasch-built Overall Disability Scale; INCAT = Inflammatory Neuropathy Cause and Treatment

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
36
Investigational medicinal product in Stage A and Stage B is defined as follows:
Term
Definition
IMP
Investigational medicinal product by trial stage:
IMP in Stage A is efgartigimod PH20 SC.
IMP in Stage B is efgartigimod PH20 SC and placebo SC (containing an equivalent 
amount of rHuPH20).
Efgartigimod PH20 SC = efgartigimod co-formulated with rHuPH20 for SC administration; IMP = investigational medicinal 
product; rHuPH20= recombinant human hyaluronidase PH20; SC = subcutaneous(ly).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
37
3.
INTRODUCTION
3.1.
Trial Rationale
The term chronic inflammatory demyelinating polyneuropathy (CIDP) has been used to identify 
a chronically progressive or relapsing symmetric sensorimotor disorder with cytoalbuminologic 
dissociation and interstitial and perivascular endoneurial infiltration by lymphocytes and 
macrophages. A number of variants of CIDP have been described that have immune or 
inflammatory aspects and electrophysiologic and/or pathologic evidence of demyelination in 
common. No consensus exists on the best approach to the nomenclature of these disorders. CIDP 
variants include disorders with predominantly sensory symptoms, distal symmetric disorder 
(DADS), multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) also 
known as Lewis-Sumner syndrome, and CIDP with associated central nervous system (CNS) 
demyelination or with other systemic disorders.4,5
CIDP most commonly has an insidious onset with either a chronic progressive or a relapsing 
course. Occasionally, complete remission occurs. The estimated prevalence of CIDP is 1.8–8.9 
per 100000.6 CIDP may occur at any age, but it is more common in the fifth and sixth decades. 
A relapsing course is associated with younger age of patients (third and fourth decades). 
The most common treatments are currently immunosuppressive or immunomodulatory 
interventions. These agents include intravenous immunoglobulin (IVIg) subcutaneous 
immunoglobulin (SCIg), plasmapheresis, prednisone, azathioprine, methotrexate, 
mycophenolate, cyclosporine, and cyclophosphamide. Their use is based on the proposed 
pathogenesis of CIDP as an immune-mediated condition, though for some of these agents, there 
is no clear evidence of a beneficial treatment effect.
However, an unmet medical need exists for an efficacious treatment of CIDP with a more 
specific mechanism of action maintaining quality of life (QoL) at the highest levels for the 
longest period possible, a favorable safety and tolerability profile, and more convenient 
administration that has a significantly lower impact on daily routines than that provided by 
current treatments.
While the abiding theory of CIDP pathogenesis is that cell-mediated and humoral mechanisms 
act together in an aberrant immune response to cause damage to peripheral nerves, the relative 
contributions of T cell and autoantibody responses remain largely undefined, though the role of 
humoral immune responses in these disorders has been emphasized.7 However, there are several 
lines of evidence to support the conclusion that CIDP is an autoimmune disease mediated by 
humoral and/or cellular immunity against yet undefined Schwann cell/myelin antigens.8
Both sera and immunoglobulin G (IgG) molecules from patients with CIDP induce peripheral 
demyelination in susceptible animals and inhibit nerve conduction in several models of 
peripheral neuropathies.9
The autoimmune etiology is supported by the efficacy of treatments that target the immune 
system, including IVIg, plasma exchange and corticosteroids, and by evidence of an 
inflammatory response in the blood and peripheral nerves. Importantly, depletion of serum IgGs 
from CIDP patients showed promising efficacy in small scale trials.10

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
38
Critically, there is now evidence to suggest that nodal antigens are important in some cases of 
CIDP. Devaux et al. (2012)11 found that 30% of patients with CIDP have serum IgG that binds to 
either the nodes of Ranvier or the paranodes in teased nerve fibers and in some cases identified 
the target antigens as neurofascin, gliomedin or contactin. Further, several trials have specifically 
identified autoantibodies against cell adhesion molecules at the nodes of Ranvier and paranodal 
regions in patients with CIDP.7
While further work is needed to examine the pathophysiological significance of nodal antigenic 
targets in CIDP, any disruption of nodal function is likely to interfere with normal nerve 
excitability and membrane potentials, contributing to conduction failure by interfering with 
saltatory conduction and ion channel function. In support of this, axonal excitability trials in 
patients with CIDP have revealed a range of findings demonstrating aberrant membrane 
excitability and membrane potential.7
regulatory system is disturbed in patients with CIDP.9
expression might provide a clinical benefit for patients with CIDP. 
A subcutaneous (SC) treatment option consisting of efgartigimod with recombinant human 
hyaluronidase PH20 (rHuPH20) could offer clinically significant benefits to CIDP patients. 
3.2.
Background
Efgartigimod (ARGX-113) is a human immunoglobulin (Ig) G1-derived Fc of the za allotype 
that binds with nanomolar affinity to human neonatal Fc receptor (FcRn). Efgartigimod 
encompasses IgG1 residues D221-K447 (European Union [EU] numbering scheme) and has 
been modified with the so-called ABDEG™ technology (ABDEG™ = antibody that enhances 
IgG degradation)12 to increase its affinity for FcRn at both physiological and acidic pH. The 
increased affinity for FcRn of efgartigimod at both acidic and physiological pH results in a 
blockage of FcRn-mediated recycling of IgGs.
Given the essential role of the FcRn receptor in IgG homeostasis, inhibiting this FcRn function, 
as is achieved by efgartigimod, leads to rapid degradation of all IgGs, including 
disease-associated autoantibodies of the IgG isotype. This approach is thought to result in 
alleviation of signs and symptoms in IgG-driven autoimmune diseases. 
The safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of intravenous (IV) 
administrations of efgartigimod have been investigated in the first-in-human trial 
ARGX-113-1501 in healthy adult subjects. A second trial ARGX-113-1702 in healthy adult 
subjects investigated the bioavailability, safety, tolerability, immunogenicity, PK, and PD 
following SC administration of efgartigimod and evaluated the reduction of the IV infusion time 
from 2 hours to 1 hour. 
Phase 2 trials in immune thrombocytopenia (ITP; ARGX-113-1603) and myasthenia gravis 
(MG; ARGX-113-1602) have indicated that efgartigimod administered by IV infusion is 
well-tolerated, induces a specific, rapid PD effect (ie, reduction in IgG levels, including 
autoantibody levels), and is associated with improvement in clinical signs and symptoms in 
patients with ITP and MG, separately.13 Additionally, the safety and tolerability of efgartigimod 
has been evaluated for the treatment of patients with pemphigus in the Phase 2 trial ARGX-113-
1701 and for the treatment of patients with MG in the Phase 3 trial ARGX-113-1704. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
39
For this Phase 2 trial in patients with CIDP, a fixed dose of efgartigimod PH20 SC was selected 
based on the results of the Phase 1 trial ARGX-113-1901 in healthy subjects that achieved a 
similar pharmacodynamic effect as that observed in generalized myasthenia gravis (gMG) and 
ITP, ie, IgG reduction, at steady state as achieved by weekly 10 mg/kg IV infusions. Doses of 
10 mg/kg efgartigimod IV have demonstrated a favorable safety and efficacy profile across 
Phase 2 trials in MG and ITP patients. To select the fixed SC dose, an open-label, parallel group 
trial in healthy male subjects (ARGX-113-1901) has been performed to investigate the PK, PD, 
safety, and tolerability of different single fixed SC dose levels of efgartigimod co-administered 
with rHuPH20. 
In the current trial, efgartigimod is co-formulated with the permeation enhancer rHuPH20 
(efgartigimod PH20 SC). rHuPH20 acts as a spreading factor that increases the dispersion and 
absorption of other co-administered drugs and allows SC dosing of greater volumes than without 
rHuPH20. SC injections of rHuPH20 with fluids, small molecules, peptides, and proteins 
(eg, IgG) were well-tolerated in all clinical trial populations studied to date.14
3.3.
Benefit/Risk Assessment
3.3.1.
Benefit
Efgartigimod has been shown to effectively reduce IgG antibody levels in clinical trials in 
healthy subjects and in patients with gMG and ITP. 
In both Phase 2 clinical trials, treatment with efgartigimod IV induced a specific, rapid, and 
profound PD effect and was associated with improvement in clinical signs and symptoms in 
patients with primary ITP and gMG, separately. In addition, Phase 3 studies with efgartigimod 
IV in patients with gMG showed that the trial’s primary endpoint was met with statistical 
significance. The primary endpoint was defined as the “percentage of anti-acetylcholine receptor 
antibody (AChR-Ab) seropositive patients who, during the first cycle, have a reduction of 
points in the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score compared 
 consecutive weeks, with the first reduction occurring no later than 
1 week after the last investigational medicinal product (IMP) infusion.” A total of 67.7% of 
AChR-Ab positive patients treated with efgartigimod achieved the primary endpoint compared 
with 29.7% on placebo (p<0.0001). In the overall patient population (AChR-Ab seropositive and 
seronegative patients), 67.9% of the patients treated with efgartigimod were MG-ADL 
responders compared with 37.3% on placebo (p<0.0001). Other key secondary endpoints for this 
study were also met with high statistically significance.13
Efgartigimod is under development for both the IV and SC administration route. For this Phase 2 
CIDP trial, SC administration is planned with a newly developed co-formulation of efgartigimod 
with rHuPH20 (efgartigimod PH20 SC). The co-formulated material will allow a manual SC 
injection within a few minutes of greater volumes than without rHuPH20. 
Due to the unmet medical need in CIDP for an efficacious treatment with a favorable safety and 
tolerability profile and more convenient administration for CIDP patients, a SC treatment option 
for efgartigimod could offer clinically significant benefits to CIDP patients.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
40
There are several lines of evidence to support the conclusion that CIDP is an autoimmune 
disease mediated by humoral and/or cellular immunity against yet undefined Schwann 
cell/myelin antigens (see Section 3.1).8
The autoimmune etiology is supported further by the efficacy of treatments that target the 
immune system, including IVIgs, plasma exchange, and corticosteroids, and by evidence of an 
inflammatory response in the blood and peripheral nerves. Importantly, depletion of serum IgGs 
from CIDP patients showed promising efficacy in small scale trials.10
3.3.2.
Risks
To date, no major safety findings have arisen in any of the ongoing and completed trials with 
efgartigimod (either with the IV or PH20 SC dosing formulations), nor has any pattern of 
adverse events (AEs) been detected that would raise concerns or alter the potential benefit-risk 
profile of efgartigimod. The table below lists the potential risks that may be encountered in the 
trial and the associated strategies to mitigate these risks.
Potential Risks and Mitigation Strategies in Patients With CIDP
Potential clinically 
significant risk
Summary of 
data/rationale for risk
Mitigation strategy
Serious infection
Efgartigimod reduces IgG 
levels, potentially hindering 
immune response and 
increasing the risk of 
infection. 
Exclusion criteria in the current trial (ARGX-113-1802): 
Patients with clinically significant active or chronic 
uncontrolled bacterial, viral, or fungal infections are 
excluded (exclusion criterion #7). 
Patients with total IgG serum levels <6 g/L are excluded 
(exclusion criterion #8). 
Infections are considered AESIs and will be monitored, 
recorded, and reported as described in Section 9.6.2.
If a clinically significant infection occurs, IMP
administration may be interrupted (Section 8.1).
An independent DSMB reviews unblinded data from the 
current trial (ARGX-113-1802) and from the open-label 
extension trial (ARGX-113-19802), and will recommend 
discontinuation or adaptation of the trial if any safety 
concern is identified (Section 11.1.5). 
Injection site 
reactions 
All therapeutic proteins can 
elicit immune responses, 
potentially resulting in 
hypersensitivity or allergic 
reactions such as rash, 
urticaria, angioedema, serum 
sickness, and anaphylactoid 
or anaphylactic reactions. 
Patients will be assessed for injection site reactions at every 
treatment period visit (Section 1.3 and Section 9.5.1. 
IMP administration will be performed by trained/authorized 
site staff or by a trained and authorized home nurse. IMP 
self-administration or administration by a caregiver is not 
permitted in the current trial (ARGX-113-1802) and will 
only be permitted in the open-label extension trial
(ARGX-113-1902) after they have completed training and 
are deemed competent enough to do so by site staff.
AESI=adverse event of special interest; DSMB=data safety monitoring board; IgG=immunoglobulin G; IMP=investigational 
medicinal product (efgartigimod PH20 SC); rHuPH20=recombinant human hyaluronidase PH20
Safety for use during pregnancy has not been established. Therefore, efgartigimod should not be 
administered to pregnant or lactating women.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
41
In summary, efgartigimod has been well-tolerated in clinical trials conducted to date.
Please refer to the current Investigator’s Brochure (IB), for a full safety and efficacy summary.9
An independent Data Safety Monitoring Board (DSMB) will be responsible for ongoing safety 
monitoring during the trial and will meet on a regular basis (see Section 10.7).
Considering the efficacy and safety data collected to date and the design of the trial that has 
appropriate measures ensuring safe trial participation, which minimizes the risk to patients 
participating in this trial, the potential risks identified in association with efgartigimod are 
justified by the potential benefits gained by patients receiving efgartigimod PH20 SC.  

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
44
5.
TRIAL DESIGN
5.1.
Overall Design
This is a Phase 2, prospective, multicenter trial to investigate the efficacy, safety, tolerability, 
PK, and PD of efgartigimod PH20 SC in patients aged 18 years and older with CIDP. This trial 
will be conducted in 2 stages: An open-label Stage A and a randomized-withdrawal Stage B. 
After a screening period for all patients and a run-in period for applicable patients (not for 
treatment-naïve patients; see Section 5.1.2), all patients will enter the open-label Stage A at 
baseline (D1A) and receive weekly trial treatment (efgartigimod PH20 SC) for up to 12 weeks 
(with optional 1 additional week). Within this period, upon evidence of clinical improvement 
(ECI) which is confirmed at 2 consecutive visits, patients will move into the randomized-
withdrawal, placebo-controlled Stage B and be randomized at Stage B baseline (D1B) in a 
1:1 ratio to efgartigimod PH20 SC or placebo. The randomized-withdrawal Stage B will last up 
to 48 weeks.
The trial will include the following periods:
Screening period: up to 28 days (see Section 5.1.1).
Run-in period: up to 12 weeks (not for treatment-naïve patients; see Section 5.1.2). 
Stage A will be a period of up to 12 weeks (with optional 1 additional week) of 
open-label treatment of efgartigimod PH20 SC (weekly trial visits) (see 
Section 5.1.3).
Stage B will be a period of up to 48 weeks of double-blind, randomized-withdrawal 
treatment of efgartigimod PH20 SC or of placebo (trial visits once every 4 weeks) 
(see Section 5.1.4).
Follow-up: 28 days after the last dose of IMP if the patient does not intend to roll 
over to the open-label extension (OLE) trial ARGX-113-1902. 
Total trial duration for each patient can be up to 80 weeks with a maximum of 61 weeks on IMP. 
An independent DSMB will be used in this trial (see Section 11.1.5).
During the different trial periods (run-in, Stage A, and Stage B), there is a permissible window of 
±2 days for the trial visits (and ±3 days for the safety follow-up visit) as described in the SoA 
(see Section 1.3).
The trial schema is provided in Section 1.2.
Patients who discontinue early from treatment, after they have completed the assessments of the 
current visit will be encouraged to return for all remaining scheduled visits as per SoA (see 
Section 1.3), unless they withdraw consent (see Section 8).
Trial assessments and procedures are described in Section 9.
5.1.1.
Screening
During the screening period of a maximum of 28 days, diagnosis of CIDP will be confirmed by a 
CIDP confirmation committee (CCC; see Section 11.1.6), and overall eligibility will be 
confirmed by the medical monitor. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
45
See the SoA in Section 1.3 for the trial procedures that will be performed at screening. Note that 
additional assessments may be asked for to support the confirmation of CIDP diagnosis (see 
Section 11.1.6).
If needed, the medical monitor assigned by the sponsor can authorize the extension of the 
screening period, if this would not impact the analysis of the primary endpoint. 
5.1.1.1.
Informed Consent
The patient must sign the informed consent form (ICF) prior to any trial-related assessment.
Prior to giving informed consent, patients will be instructed not to participate in any other 
clinical trial that involves a medical intervention or collection of data until the completion of the 
current trial.
5.1.1.2.
Eligibility
Once the patient has provided informed consent prior to any protocol-required assessments that 
are not part of this patient’s routine care, a unique patient identification number will be assigned. 
Should the patient be withdrawn from the trial, his/her identification number will not be 
reallocated.
Patients will be classified as eligible if all of the inclusion criteria (see Section 6.1) and none of 
the exclusion criteria (see Section 6.2) are fulfilled, and eligibility CIDP diagnosis has been 
confirmed by a CCC (see Section 11.1.6) and by the medical monitor. 
If the patient is not eligible, then he/she should be recorded as a screen failure and the reason for 
screening failure should be documented in the electronic case report form (eCRF). 
5.1.1.3.
Screen Failures, Re-screening, and Re-testing
A patient who does not meet the eligibility criteria will be considered a screen failure and 
recorded as such.
A re-test in case of an out-of-range clinical laboratory test value to determine a patient’s 
eligibility is allowed at the discretion of the investigator and in agreement with the sponsor. 
A patient may be re-screened once (ie, repeat the full assessments as per general SoA, see 
Section 1.3.1), only if the patient has not started treatment in Stage A and with the sponsor’s 
written approval. 
Examples of conditions under which re-screening may be considered include the following: 
Patients who required treatment for an acute illness (eg, a urinary tract infection) or have a 
chronic medical problem (eg, uncontrolled hypertension) may be re-screened once the 
illness has resolved or the medical problem has stabilized.
The patient has a clinical laboratory test result meeting 1 or more exclusion criteria, which 
are not consistent with the medical history and clinical evaluation of the patient.
The patient might not have fulfilled the criteria for evidence of clinically meaningful 
deterioration (ECMD; see Section 2.2) during the run-in period, but after classification as 
run-in failure, has fulfilled the criteria of a treatment-naïve patient (ie, not treated with 
monthly or daily corticosteroids, IVIg or SCIg for at least 6 months) with evidence of 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
46
disease activity (ie, documented evidence for worsening on the total adjusted Inflammatory 
Neuropathy Cause and Treatment [INCAT] disability score, further referred to as “adjusted 
INCAT score,” within 3 months prior to screening compared to previous adjusted INCAT 
score within 6 months prior to screening).
5.1.2.
Run-in Period
After a screening period of maximum 28 days and depending on the type of permitted previous 
treatments for CIDP, eligible patients will start a run-in period, which will last up to 12 weeks. 
The following will be done, depending on the prior or current treatment of the patient at 
screening:
1. Patients, who are treatment-naïve for treatments for CIDP are allowed to skip the run-in 
period, if there is documented evidence for worsening on the adjusted INCAT score 
within 3 months prior to screening compared to previous adjusted INCAT score within 
6 months prior to screening; 
Note: Patients not treated with pulsed monthly or daily corticosteroids, IVIg or SCIg for at least 6 months 
prior to screening are considered as equal to treatment-naïve patients.
2. Patients, who are treated with IVIg or SCIg during screening will stop treatment with 
IVIg or SCIg at the start of the run-in period (ie, RI-V1);
3. Patients, who are treated with pulsed corticosteroids (IV or oral) or daily oral 
mg during screening will stop treatment with corticosteroids 
at the start of the run-in period (ie, RI-V1).
Patients are monitored by collecting the grip strength, Inflammatory-Rasch-built Overall 
Disability Scale (I-RODS) score, Medical Research Council (MRC) sum scoring, adjusted 
INCAT score, and the Timed Up and Go (TUG) test data. Regular scheduled visits at the trial 
site are planned every 4 weeks.
Patients will receive appropriate training and instructions to assess every week the disability 
status by means of I-RODS and grip strength. The patient’s I-RODS score and the mean grip 
strength will be captured, calculated, and transferred to the eCRF. If the patient observes any of 
the following signals of deterioration, a trial visit should be arranged within 5 working days for 
an assessment by a physician: 
an I-
 points (using the centile metric), and/or 
 kPa in 1 hand using the handheld 
vigorimeter.
Note: Patients will be performing 3 assessments for each hand in arbitrary order (with approximately 
30 seconds rest between each assessment) always at approximately the same time during the day. The 
mean grip strength for each hand will be used to determine disease activity.
At the trial site, the evaluating physician will then assess if deterioration can be confirmed by 
fulfilling the criteria for ECMD; see Section 2.2 for definition. 
Any patient showing ECMD at the trial site will enter Stage A immediately. If the patient is not 
providing evidence of ECMD by the end of the run-in period, then he/she should be recorded as 
a run-in failure.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
47
See the SoA in Section 1.3.1 for other specific trial procedures that will be performed at each 
visit of the run-in period. 
5.1.3.
Stage A 
All patients with ECMD will start Stage A with the first administration of open-label IMP at 
Stage A baseline (D1A). After completing all pretreatment baseline assessments, these patients 
will receive weekly SC administrations of IMP, consisting of efgartigimod PH20 SC, for up to 
12 weeks (with optional 1 additional week), with a minimum of 4 SC injections of IMP. 
The procedures that will need to be completed at D1A and at the other trial visits are provided in 
the SoA in Section 1.3.1.
If no safety concerns exist in the opinion of the investigator, patients will be discharged from the 
center after all planned procedures for that visit according to the SoA have been performed. 
Each patient will remain in Stage A and return weekly to the trial site as described in the SoA in 
Section 1.3.1 until ECI relative to D1A has been identified by the evaluating investigator at 
2 consecutive visits (see Section 2.2 for a definition of ECI).
An interim analysis of results will be performed after the first 30 patients in Stage A have 
reached the end of Stage A (EOSA), see Section 10.6. During the interim analysis, the trial will 
continue without any interruption, neither for trial enrollment nor for visits or treatments of 
patients participating in any trial period. 
Patients who have not shown ECI at 2 consecutive visits during Stage A will be classified as 
non-responders. Non-responders will end the trial, will attend a follow-up visit after 28 days after 
the last administration of IMP, and will be treated by the investigator as considered appropriate. 
All patients with confirmed ECI will be randomized to 1 of the 2 treatment arms (SC 
administration of efgartigimod PH20 SC or placebo) and will start Stage B. Randomization 
should be performed on the same day as the confirmation of ECI. Therefore, patients with 
confirmed ECI will have a combination of the EOSA visit and the Stage B baseline (D1B) visit.
Patients who show ECI only at normally the last visit of Stage A (ie, 1 week after A-V12) will be 
allowed to extend Stage A for a further week with 1 additional consecutive visit. This visit, at 
which ECI is observed for the first time, will be called the A-V13 visit and will be followed by a 
consecutive visit 1 week later. The reason for this possible extension of Stage A with 1 week is 
to get ECI confirmed at a consecutive visit 1 week later (and, if ECI is confirmed, to randomize 
the patient [ie, the patient will start Stage B]). In case ECI is not confirmed after an additional 
week of Stage A, an EOSA visit will be performed and the patient will end the trial (after a 
follow-up visit 28 days following the last IMP administration). See also Section 7.1.2 for 
detailed information of IMP administration in Stage A.
During Stage A, IMP will be administered at the site after blood samples have been taken for 
laboratory safety, PK, PD, immunogenicity, and/or biomarker analyses and after all assessments 
needed for determination of ECI. 
During Stage A, all patients will receive training for self-administration of IMP (foreseen in the 
OLE trial, not in the ARGX-113-1802 trial) as specified in the SoA in Section 1.3.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
48
5.1.4.
Stage B 
Evaluations at screening, during the run-in period (visit RI-V1 to visit RI-V4), and confirmation 
at Stage A baseline (D1A; visit A-V1) before first treatment in Stage A and the treatment 
response during Stage A will be used to determine each patient’s eligibility for randomization in 
Stage B at Stage B baseline (D1B).
Patients with ECI during Stage A will be randomized at Stage B baseline (D1B) in a 1:1 ratio to 
receive weekly SC administrations of efgartigimod PH20 SC or placebo. 
All patients randomized to the double-blind, randomized-withdrawal Stage B will be dosed with 
IMP weekly but will return to the clinic at 4-week intervals (once every 4 weeks). At each of 
these visits, specific procedures, as specified in the SoA in Section 1.3.2, will be performed. 
Patients will be discharged from the trial center after all planned procedures for that visit 
according to the SoA in Section 1.3.2 have been performed and if no safety concerns exist in the 
opinion of the investigator. 
For the purpose to lessen the burden on patients as much as possible, the following solutions for 
in-between site visit IMP SC administrations will be proposed: Administration by a home nurse 
or concierge service for visit at the trial site. Upon agreement with the investigator, site 
personnel, and the patient, the most suitable solution will be provided for IMP administration in 
between trial visits. Administration of IMP will occur always within a time window of ±2 days 
with respect to the pre-planned date of administration. Patients will receive a treatment schedule 
plan to ensure that timing of IMP administration will be observed. The patient will be asked to 
return used and unused medication at the next visit, during which IMP accountability will be 
performed. On the scheduled trial visits, IMP will be administered at the site after blood samples 
have been taken for laboratory safety, PK, PD, immunogenicity, and/or biomarker analyses and 
after all assessments needed for determination of clinical deterioration.
When 88 events have been observed for the primary endpoint analysis of Stage B (see sample 
size determination for Stage B in Section 10.3), then the trial will stop. In that case, patients in 
Stage A and Stage B will perform an early discontinuation visit and patients who are receiving 
IMP will be given the opportunity to continue efgartigimod PH20 SC treatment in the OLE trial 
(in this case the early discontinuation visit of the ARGX-113-1802 trial can coincide with the roll 
over visit). Additionally, at the time of the 88th event, patients in run-in will also be given the 
option to roll over to the OLE trial after performing an early discontinuation visit. Patients who 
will not roll over to the OLE trial, will attend a follow-up visit 28 (±3) days after the last IMP 
dose. 
Patients will be given the opportunity to continue efgartigimod PH20 SC treatment in an OLE 
trial ARGX-113-1902 if any of the following 3 conditions occur: 
1. The patient experiences clinical deterioration (ie, worsening in adjusted INCAT score) 
during Stage B.
Note: Clinical deterioration needs to be confirmed by an unscheduled visit that is to be planned 3-7 days 
after the first adjusted INCAT score increase of 1 point (or at a following trial visit if planned at that time). 
For patients with an increase of 2 or more points on the adjusted INCAT score compared to Stage B 
baseline, no confirmation is required. In case the patient experiences clinical deterioration, the visit will 
become an early discontinuation visit of ARGX-113-1802 and the patient can roll over to the 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
49
ARGX-113-1902 trial (in this case the early discontinuation visit will be combined with the first visit of the 
ARGX-113-1902 trial).
2. The patient completes week 48 visit of Stage B without any clinical deterioration (see 
Section 2.2).
3. Recording of the 88th event during Stage B and the patient is receiving IMP in either 
Stage A or Stage B. An event is a worsening of the adjusted INCAT score in any of 
patients treated during Stage B (see Section 2.2 and Section 10.3).
Additionally, at the time of the 88th event, patients in run-in will also be given the option to roll 
over to the OLE trial after performing an early discontinuation visit. 
The OLE will be a separate trial ARGX-113-1902 with details described in its own protocol. 
During Stage B, patient will receive further training for self-administration of IMP (foreseen in 
the OLE trial, not in the ARGX-113-1802 trial) as specified in the SoA in Section 1.3.2.
Patients who have clinical deterioration or who complete the week 48 visit also have the 
possibility to enter the safety follow-up period and complete the trial without rolling over to the 
OLE trial. These patients will be treated as considered appropriate by the investigator.
5.1.5.
Unscheduled Visit
It is at the investigator’s discretion, or on request of the patient, to initiate an unscheduled visit, if 
deemed necessary for the patient’s safety and well-being. 
An unscheduled visit is to be planned for: 1) safety reasons, 2) assessment of ECMD during the 
run-in period, 3) assessment of efficacy during Stage B (eg, confirmation of worsening on the 
adjusted INCAT score of 1 point), or 4) any other reason. 
All such visits will be documented in the eCRF with any additional required documentation 
based on the nature of unscheduled visit. 
Procedures that can be performed at an unscheduled visit are defined in the SoA in Section 1.3.
The investigator can decide which of the assessments need to be performed at each unscheduled 
visit. If, for example, the unscheduled visit is used to confirm ECMD during run-in (which needs 
to be observed at the trial site) or clinical deterioration during Stage B, the assessments as listed 
for the scheduled visits in the corresponding period will need to be performed (see the SoA in 
Section 1.3).
The date and reason for the unscheduled visit must be recorded in the source documentation. 
If an unscheduled visit is necessary, then additional diagnostic tests may be performed based on 
investigator assessment as appropriate, and the results of these tests should be entered on the 
unscheduled visit page of the eCRF. 
5.1.6.
Follow-up
A follow-up visit will be planned 28 days after the last dose of IMP (in case of early 
discontinuation from IMP or the trial), or in case a patient does not meet the criteria for ECI in 
Stage A [non-responder]) or 28 days after the last dose in Stage B if the patient does not intend 
to roll over to the OLE trial ARGX-113-1902. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
50
Procedures performed at the follow-up visit are defined in the SoA in Section 1.3.
5.2.
Scientific Rationale for Trial Design
The trial design uses some key elements from the PATH trial (van Schaik et al, 2018).15
A treatment period (Stage A) is foreseen for all patients who showed evidence of disease activity 
during the run-in period. 
The run-in period has 2 purposes: 
Selecting for patients with evidence of clinical disease activity (enrichment design);
Ensure that both, the half-life of the previous drug (if applicable) had elapsed and the 
clinical effect would not jeopardize the efficacy analysis of the current trial.
The pre-randomization observation period on treatment (Stage A) can be of any length between 4 
and 13 weeks. The post-withdrawal observation period (ie, for patients in the placebo group 
during Stage B) in this trial has a maximum duration of 48 weeks, but applies during this period 
the time to event approach (early escape design). As with the early escape design, careful 
attention has been paid to procedures for monitoring patients and assessing trial endpoints to 
ensure that patients failing on an assigned treatment are rapidly identified. 
The advantages of this trial design are that individuals receiving the experimental intervention 
continue to do so only if they respond, whereas individuals receiving placebo do so only until 
their symptoms return. 
Additional advantage of this design is to study the long-term efficacy or safety (withdrawal 
effect). A disadvantage is the longer overall trial period, which has been extended from typical 
24 weeks to 48 weeks.
This trial design allows to collect information on the onset of therapeutic effect as well as 
information if the effect continues after withdrawal from medication or if there is a rebound 
phenomenon (placebo group). Furthermore, this trial will also generate data of the placebo 
response in such a population that is of interest for further clinical development. 
Any difference that emerges between the group receiving continued treatment and the group 
randomized to placebo in Stage B will demonstrate the effect of the active treatment.
All eligible patients will start the participation in this trial through an open-label period 
(Stage A), in which they will all receive active treatment. Such a choice was perceived necessary 
for the purpose to offer to all patients with active disease a minimal treatment with efgartigimod 
PH20 SC, even for those patients who would be randomized to the placebo arm after this period 
(in Stage B). Stage A has a variable duration at minimum 4 weeks up to 12 weeks (with optional 
1 additional week), during which the patient will be treated with weekly SC administrations until 
clinical improvement has been achieved and maintained in 2 concurrent visits. This variable 
duration has been chosen to achieve the maximal IgG reduction, which will maximize the 
duration of effect. A maximum number of injections is set at 12 (or 13 in case of an optional 
additional week), in line with clinical practice for other therapies (3 months). 
As introduction into the placebo arm, an initial open-label treatment with efgartigimod PH20 SC 
(Stage A) is foreseen for all patients. This allows patients to receive active treatment before 
potential randomization to placebo (during Stage B), which would make the design more 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
52
Dosing higher or more frequently than weekly is not expected to result in an improved 
PD effect (ie, further lowering of autoantibodies) and/or clinical effect and may be 
associated with a less optimal risk/benefit ratio. Dosing lower is expected to result in a 
lower PD effect and thus is likely to result in a less consistent and/or incomplete clinical 
response, which is undesirable given the serious and chronic manifestations of CIDP. 
Therefore, weekly dosing is favorable until patients are in a stable clinical condition.
3. Demonstrated a favorable safety profile in Phase 2 trials in MG and ITP patients.
In addition, based on favorable phase 3 results in patients with MG, efgartigimod IV at a dose 
of10 mg/kg has been approved in the United States (US) and in the EU (in both regions for 
AChR-Ab seropositive patients) and in Japan (for patients who do not have sufficient response to 
steroids or nonsteroidal immunosuppressive therapies). 
A study in healthy participants demonstrated that after 4 weekly injections of efgartigimod 
PH20 SC 1000 mg, the pattern of total IgG level reduction over time was comparable to that 
observed after 4 weekly infusions of efgartigimod IV 10 mg/kg. 
rHuPH20, as Hylenex, has been approved in the US. Coformulations of rHuPH20 with other 
active ingredients have been approved in the US and the EU (eg, HERCEPTIN 
HYLECTA/Herceptin SC, RITUXAN HYCELA/MabThera SC, HYQVIA/HyQvia, 
respectively), with a rHuPH20 concentration of 2000 U/mL for a SC injection volume in the 
range of 5 to 13.4 mL.
5.4.
Measures to Minimize Bias: Randomization and Blinding
Stage A will be open-label with administration of efgartigimod PH20 SC.
In Stage B, patients will be randomized to double-blind SC efgartigimod PH20 SC or placebo in 
a 1:1 ratio. Patients will be stratified according to their prior CIDP medication and the decrease 
of adjusted INCAT score during Stage A by the following: 
Prior CIDP medication:
Treatment-naïve (see inclusion criterion #6 in Section 6.1 for definition); 
Pulsed corticosteroid treatment or oral corticosteroids equivalent to 
 mg/day; 
IVIg or SCIg treatment. 
Adjusted INCAT score: 
No change in adjusted INCAT score during Stage A;
 point during Stage A.
Except for unblinding for safety reasons, Stage B will be double-blind to treatment assignment 
during the entire randomized-withdrawal period, even if the patient withdraws from the trial or 
enters the OLE trial ARGX-113-1902. The treatment that each patient receives will not be 
disclosed to the investigator, investigational site staff, patient, sponsor, or the sponsor’s 
designated contract research organization (CRO). The trial will be unblinded following the final 
database lock.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
53
Refer to Section 7.2 for the preparation and administration of the IMP, thereby keeping the blind 
during Stage B.
The sponsor will appoint a DSMB consisting of an independent group of clinical experts, who 
will not participate in the trial as active investigators. The DSMB will be supplemented by an 
independent statistician. The objective of the DSMB will be to review all unblinded safety data 
and determine if there is an imbalance in treatment arms assignment regarding safety events. The 
DSMB will advise the sponsor on the continuation, modification, or termination of the trial. 
More detail on the DSMB is provided in Section 11.1.5.
5.4.1.
Two Physician Concept
In addition to the double blinding of IMP in Stage B of the trial, the two physician concept will 
be used to achieve blinding for the evaluation of clinical endpoints, in which there will be 
2 physician roles: a treating physician and an evaluating physician. 
For each role, preferably 1 deputy will be nominated at each center. Therefore, in total at least 
4 staff members should be involved in the treatment and evaluation of patients at each center.
Throughout this protocol, references to the “treating physician” and “evaluating physician”
include their respective deputies.
The (principal) investigator who is responsible for the conduct of the trial and for supervision of 
the management of individual patients at the center should not take the role of the evaluating 
physician. 
5.4.1.1.
Treating Physician 
The treating physician will be responsible for all aspects of treatment and clinical management of 
the patient, including the management of clinical symptoms. He/she will have the same level of 
blinding as the patient. 
The treating physician will perform the following activities:
Physical examinations 
Assessment of vital signs
Evaluation of the patient’s subjective findings (eg, how the patient feels and if there 
were any symptoms suggesting an AE) 
Assigning (through interactive response technology [IRT] randomization) and 
monitoring the administration of the trial medication
Evaluating and managing (serious) AEs, concomitant medication and laboratory 
results
Loading patient’s data into the electronic system, including the results from ECI 
and/or ECMD related assessments
Undertaking relevant steps in response to ECI or ECMD evidence (which will be 
provided by the evaluating physician) 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
54
The treating physician cannot be involved in evaluating adjusted INCAT and I-RODS scores or 
assessment of mean grip strength, MRC, and TUG test. However, the treating physician will 
have access to results of ECI and ECMD assessments.
5.4.1.2.
Evaluating Physician 
The evaluating physician will oversee the scoring of: 
adjusted INCAT and I-RODS, and
and all the standardized neurological examinations needed, including the assessment 
of:
mean grip strength 
MRC
TUG test
The evaluating physician will make an assessment of clinical deterioration. 
He/she will also oversee the evaluation of the following PRO tools: 
EuroQol 5 dimensions and 5 levels health-related quality-of-life questionnaire 
(EQ-5D-5L)
See Section 9 for a description of the different assessments.
Throughout the whole duration of the trial, the evaluating physician will not seek nor collect any 
treatment-related information (eg, AEs, treatment compliance, interruption or discontinuation, 
etc.) from the patient or from the treating physician. 
The interaction with the patient will be restricted to the neurological evaluation. The evaluating 
physician will not be allowed to talk with the patient about AEs, or any other issue that could 
potentially disclose the patient’s treatment.
Thus, the Evaluating Physician will be completely blinded to all aspects related to the patient’s 
treatment, including the assessment of side effects and drug administration problems. 
5.4.2.
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 and 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. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
55
If possible, the investigator should first discuss options immediately with the medical monitor 
and sponsor, with due consideration of the safety of the patient. If the investigator must identify 
the treatment assignment of an individual patient, the principal investigator/treating physician is 
to contact the IRT.
If the blind is broken, it may be broken only for the patient concerned, and the IMP treatment 
assignment should not be revealed to the trial team members from the sponsor, nor from the 
sponsor’s designated CRO, or pharmacy personnel. 
Patients for whom the code has been broken by the investigator will be withdrawn from the trial 
and all efforts should be made to conduct the early discontinuation visit as well as the follow-up 
visit 28 days after the last IMP dose (see Section 8.3). All efficacy data up until the code break 
will be included in the modified intent-to-treat (mITT) and per protocol (PP; in case of no major 
protocol deviations until the code break) analysis sets. 
Pertinent information regarding the circumstances of unblinding of a patient’s treatment code 
must be documented in the patient’s source documents and eCRFs. 
5.5.
End of Trial Definition
The end of trial is defined as the last patient last visit in the ARGX-113-1802 trial, ie, any of the 
following: 
the last visit before roll over to the OLE trial, or
the follow-up visit 28 days after the last IMP dose for patients not participating in the 
OLE trial.
See Section 11.1.10 for trial and site start and closure.
5.6.
Roll Over to Open-label Extension (OLE) Trial
Patients who are receiving IMP, and in the opinion of the investigator benefit from trial treatment 
at week 48 or who, while on treatment, experienced clinical deterioration during Stage B
(ie, worsening in adjusted INCAT score; see Section 5.1.4) will be offered the option to roll over 
to a long-term, single-arm, OLE trial, during which they will be treated weekly with SC 
efgartigimod PH20 SC. The dose and frequency used in the OLE is the same as is given to 
patients enrolled to Stage A of this trial.
Patients who are receiving IMP in Stage A or Stage B, or are in run-in at the moment of 
recording of the 88th event in the trial, will perform an early discontinuation visit and will be 
offered the option to roll over to the OLE trial, as the ARGX-113-1802 will stop at this moment. 
An event is a worsening of the adjusted INCAT score (see Section 2.2 and Section 10.3) in any 
of patients treated during Stage B.
Patients who discontinue early from randomized treatment for pregnancy reasons or for an 
(S)AE that might jeopardize the safety of the patient will not be offered the option to roll over to 
the OLE trial.
It will be documented if a patient will roll over to the OLE trial.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
56
5.7.
Protocol Deviations
The investigator should not implement any deviation from, or changes to 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 (eg, change of 
telephone numbers, …). The investigator (or designee) should document and explain any 
deviation from the approved protocol. 
Protocol exemptions or waivers will not be approved by the sponsor. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
57
6.
TRIAL POPULATION
Prospective approval of protocol deviations to recruitment and enrollment criteria, also known as 
protocol waivers or exemptions, is not permitted. 
6.1.
Inclusion Criteria
Patients are eligible to be included in the trial only if all of the following criteria apply: 
1. Ability to understand the requirements of the trial, provide written informed consent 
(including consent for the use and disclosure of research-related health information), 
willingness and ability to comply with the trial protocol procedures (including required 
trial visits).
2. Male or female patient aged 18 years or older, at the time of signing the informed 
consent. 
3. Diagnosed with probable or definite CIDP according to criteria of the European 
Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS, 2010),2
progressing or relapsing forms. 
4. CIDP Disease Activity Status (CDAS)3
see Section 11.6).
5.
-in visit (RI-V1; for patients entering run-in) or 
Stage A baseline (A-V1; for treatment-naïve patients with documented evidence for 
worsening on the total adjusted INCAT disability score within 3 months prior to 
screening). Patients with an INCAT score of 2 at trial entry must have this score 
entry, there are no specific requirements for arm or leg scores.
6. Fulfilling any of the following treatment conditions: 
Currently (ie, within the last 6 months) treated with pulsed corticosteroids, oral 
 mg/day, and/or IVIg or 
SCIg, and the patient is willing to discontinue this treatment at the first run-in visit 
(RI-V1); OR
Without previous treatment (treatment-naïve); OR
Treatment with corticosteroids and/or IVIg or SCIg discontinued at least 6 months 
prior to screening. 
Note: Patients not treated with monthly or daily corticosteroids, IVIg or SCIg for at least 6 months 
prior to screening are considered as equal to treatment-naïve patients.
7. Women of childbearing potential who have a negative pregnancy test at screening and a 
negative urine pregnancy test up to Stage A baseline (D1A).
8.a. Women of childbearing potential must use an acceptable method of contraception from 
signing the ICF until the date of the last dose of IMP (see Section 11.3).
9. Inclusion criterion removed in protocol amendment 4. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
58
6.2.
Exclusion Criteria
Patients are excluded from the trial if any of the following criteria apply: 
1. Pure sensory atypical CIDP (EFNS/PNS definition2).
2. Polyneuropathy of other causes, including the following: 
Multifocal motor neuropathy 
Monoclonal gammopathy of uncertain significance with anti-myelin-associated 
glycoprotein immunoglobulin M (IgM) antibodies 
Hereditary demyelinating neuropathy 
Polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin 
change syndromes 
Lumbosacral radiculoplexus neuropathy 
Polyneuropathy most likely due to diabetes mellitus 
Polyneuropathy most likely due to systemic illnesses 
Drug- or toxin-induced polyneuropathy 
3. Any other disease that could better explain the patient’s signs and symptoms. 
4. Any history of myelopathy or evidence of central demyelination. 
5. Current or past history (within 12 months of screening) of alcohol, drug or medication 
abuse.
6. Severe psychiatric disorder (such as severe depression, psychosis, bipolar disorder), 
history of suicide attempt, or current suicidal ideation that in the opinion of the 
investigator could create undue risk to the patient or could affect adherence with the trial 
protocol. 
Note: At screening, suicidality will be assessed using the Columbia-suicide severity rating scale 
(C-SSRS) (see Section 9.2); patients with a high suicide risk will be excluded from the trial (ie, patients 
will be excluded with a positive answer to questions #4 and/or #5 of the suicidal ideation subscale [over 
the past 3 months]; and/or any positive answer to the suicidal behavior subscale [over the past year]).
Any positive answer to the above questions under “Lifetime/Time he/she felt most suicidal” should be 
carefully evaluated for any current risk of suicide by the investigator prior to trial entry.
7. Patients with clinically significant active or chronic uncontrolled bacterial, viral, or 
fungal infection at screening, including patients who test positive for an active viral 
infection at screening with (see Section 9.1 for more information):
Active Hepatitis B Virus (HBV): serologic panel test results indicative of an active 
(acute or chronic) infection; 
Active Hepatitis C Virus (HCV): serology positive for HCV-Ab;
Human Immunodeficiency Virus (HIV) positive serology associated with an 
Acquired Immune Deficiency Syndrome (AIDS)-defining condition or with a cluster 
of differentiation
cells/mm3. 
8. Total IgG level <6 g/L at screening.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
59
9.a.Treatment with the following:
Within 3 months (or 5 half-lives of the drug, whichever is longer) before screening:
plasma exchange or immunoadsorption, any concomitant Fc-containing therapeutic 
agents or other biological, or any other investigational product; 
Within 6 months before screening: rituximab, alemtuzumab, any other monoclonal 
antibody, cyclophosphamide, interferon, tumor necrosis factor–alpha inhibitors, 
fingolimod, methotrexate, azathioprine, mycophenolate, any other immunomodulating 
or immunosuppressive medications, and oral daily corticosteroids >10 mg/day. 
Note:
mg/day 
can be included.
Patients who (intend to) use prohibited medications and therapies (see Section 7.4.2)
during the trial. 
10.a. Pregnant and lactating women and those intending to become pregnant during the trial. 
11. Patients with any other known autoimmune disease that, in the opinion of the 
investigator, would interfere with an accurate assessment of clinical symptoms of CIDP.
12.a. Patients who received a live-attenuated vaccine fewer than 28 days before screening. 
Receiving an inactivated, sub-unit, polysaccharide, or conjugate vaccine any time 
 
before screening is not exclusionary. 
13. Patients who have a history of malignancy unless deemed cured by adequate treatment 
years before the first IMP administration. Patients 
with the following cancer can be included anytime: 
Adequately treated basal cell or squamous cell skin cancer,
Carcinoma in situ of the cervix, 
Carcinoma in situ of the breast, or 
Incidental histological finding of Prostate cancer (TNM [tumor, nodes, and 
metastases classification] stage T1a or T1b). 
14. Patients who previously participated in a trial with efgartigimod and have received at 
least 1 administration of IMP.
15. Patients with known medical history of hypersensitivity to any of the ingredients of IMP. 
16. Patients with clinical evidence of other significant serious disease or patients who 
underwent a recent or have a planned major surgery, or any other reason which could 
confound the results of the trial or put the patient at undue risk.
6.3.
Lifestyle Considerations
There are no specific lifestyle considerations for this trial.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
60
7.
TREATMENTS AND THERAPIES DURING THE CONDUCT OF 
THE TRIAL
IMP is defined as any investigational intervention(s), marketed product(s), placebo, or medical 
device(s) intended to be administered to a trial patient according to the trial protocol. 
In open-label Stage A, IMP is efgartigimod PH20 SC. In the double-blind Stage B, IMP is 
efgartigimod PH20 SC and placebo. 
7.1.
IMP(s) Administered
Efgartigimod is a modified human IgG1 Fc fragment with increased affinity to human FcRn. 
rHuPH20 is an enzyme used to increase the dispersion and absorption of co-administered 
therapeutics when administered SC. Efgartigimod and rHuPH20 are co-formulated and will be 
administered as a single SC injection.
IMP will be provided by the sponsor and is manufactured in accordance with Good 
Manufacturing Practice regulations.
The efgartigimod PH20 SC formulation will be provided in a vial at a concentration of 
165 mg/mL or 180 mg/mL (new concentration) for efgartigimod and 2000 U/mL for rHuPH20 
(also referred to as ARGX-113/rHuPH20). Each dose of efgartigimod PH20 SC will include 
1000 mg efgartigimod. Note that there will be a transition period during which both formulations 
of efgartigimod PH20 SC (with efgartigimod at a concentration of 165 mg/mL or 180 mg/mL) 
will be used. After this transition period, all patients will receive the efgartigimod PH20 SC 
formulation with efgartigimod at the higher concentration of 180 mg/mL. The formulation with 
the higher concentration of efgartigimod (180 mg/mL) reduces the dosing volume for each SC 
injection.
Placebo will be vehicle (with 2000 U/mL of rHuPH20) provided in a vial as ready SC 
formulation. For both efgartigimod PH20 SC formulations (with efgartigimod at a concentration 
of 165 mg/mL or 180 mg/mL), a corresponding placebo is available containing placebo drug 
product at the same volume and in the same vial as the active drug product. 
Refer to the pharmacy manual for detailed instruction of IMP administration. 
The vials will be labeled as required per country requirements. 
7.1.1.
Run-in Period
No IMP will be administered during the run-in period. 
All eligible patients who are not considered treatment-naïve (for definition see inclusion 
criterion #6 in Section 6.1) will participate in the run-in period. Eligible patients, who are treated 
at time of screening with pulsed corticosteroids, or oral corticosteroids equivalent to 
 mg/day, and/or IVIg or SCIg will stop taking their current 
treatment for CIDP at the time they start the run-in period (ie, RI-V1).
Eligible treatment-naïve patients, including patients not treated with corticosteroids, IVIg or 
SCIg for at least 6 months prior to screening, will start immediately with Stage A after the 
screening period, if during screening documented evidence for worsening on the adjusted 
INCAT score within 3 months prior to screening is available compared to previous adjusted 
INCAT score within 6 months prior to screening. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
61
7.1.2.
Stage A: Open-label
IMP will be administered to all patients in Stage A as efgartigimod PH20 SC in the abdominal 
skin area. IMP will be administered weekly until ECI is observed by the investigator for 
2 consecutive visits, thereby considered confirmed ECI. Each patient will receive at least 4 and 
maximum 12 weekly doses of IMP (up to the A-V12 visit). Patients who show ECI only at the 
last visit in Stage A (ie, 1 week after A-V12) will be allowed to extend Stage A for a further 
week with 1 additional consecutive visit (A-V13) with an injection at week 12 (ie, a 13th
injection). The reason for this possible extension is to get ECI confirmed at a consecutive visit 
(and, if confirmed, to randomize the patient in Stage B). In case the ECI is not confirmed after an 
additional week of Stage A, the patient will have an EOSA visit, followed by a safety follow-up 
visits 28 days after last IMP administration and will end the ARGX-113-1802 trial (see 
Section 5.1.3).
Below is an overview of the minimum and maximum IMP administrations in Stage A:
Minimum number of IMP 
administrations in Stage A 
4 IMP administrations at: A-V1 (ie, D1A), A-V2, A-V3, and 
A-V4.
In case ECI is observed at A-V4 and also 1 week after 
A-V4, the patient will be randomized and will start 
Stage B; ie, in this case, the patient will not have a A-V5 
visit, EOSA procedures will be followed and the patient 
will have a D1B visit (this visit will be a combination of 
EOSA and D1B).
Normal maximum number of 
IMP administrations in Stage A 
12 IMP administrations at: A-V1 (ie, D1A) through A-V12. 
In case ECI is observed at A-V12 and also 1 week after 
A-V12 (ie, ECI is confirmed), the patient will be 
randomized and will start Stage B; ie, in this case, the 
patient will have a combination of the EOSA visit and 
the D1B visit 1 week after A-V12. 
In case no ECI is observed at A-V12 and also not 1 week 
after A-V12, this visit 1 week after A-V12 will then be 
the EOSA visit (and the patient will end the trial after 
performing a safety follow-up visit 28 days after the last 
IMP administration).
Optional 1 additional week of 
IMP administration
In case no ECI is observed at A-V12, but the patient has 
ECI 1 week after A-V12, this visit 1 week after A-V12 
will then become an additional visit called A-V13 at 
which the patient will receive another IMP administration
(resulting in a total of 13 IMP administrations). The 
patient will then need to come back 1 week after the 
A-V13 visit for the EOSA visit to confirm ECI. If the 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
62
patient has ECI at this visit (ie, ECI is confirmed), the 
patient will be randomized and will start Stage B (ie, the 
patient will have a combination of the EOSA visit and 
the D1B visit 1 week after the A-V13 visit). If the patient 
does not have ECI at the EOSA visit 1 week after the 
A-V13 visit, the patient will end the trial after performing 
a safety follow-up visit 28 days after the last IMP 
administration.
7.1.3.
Stage B: Double-blind, Randomized-withdrawal 
IMP in Stage B will be either efgartigimod PH20 SC or placebo, administered in the abdominal 
skin area.
During Stage B, all patients will receive IMP weekly up to 48 weeks.
Patients who have clinical deterioration or who complete the week 48 visit will have the 
possibility to enter the safety follow-up period and complete the ARGX-113-1802 trial or have 
the possibility to roll over to the OLE trial (see Section 5.1.4).
7.2.
Preparation, Handling, Storage, Administration, and Accountability
Refer to the Pharmacy Manual for information about the temperature conditions for IMP transit 
and storage and the IMP preparation, including the volume of efgartigimod PH20 SC or placebo 
to be administered. 
Efgartigimod PH20 SC will be provided as a sterile, clear to opalescent, yellowish solution for 
SC injection.
Placebo will be provided as a sterile, colorless, clear solution for injection in glass vials with the 
same formulation as the efgartigimod PH20 SC solution for injection, but without the active 
ingredient. 
The vials for the double-blind Stage B will be covered with a blinding shell. 
The trained and authorized staff will use an amber colored syringe for preparation and 
administration of IMP. The administration is then performed by the site staff who prepared the 
syringe. 
For each injection, the initiation and completion times (hour and minute) and details of any 
interruptions or premature discontinuation of injections will be recorded and will be transferred 
to the eCRF. The start will be marked as the moment of start pressing the plunger and the end
will be marked as the completion time of administration of the total volume of IMP.
Only patients enrolled in the trial shall receive IMP and only authorized site staff shall supply 
IMP, administer IMP, or train the home nurse on IMP administration. Each patient will receive a 
specific training for self-administration (foreseen in the OLE trial, not in the ARGX-113-1802 
trial) and a manual on preparation, handling, storage and administration of the IMP. The mode of 
administration (at the site during a trial visit, home nurse, or concierge service for visit at the trial 
site) will be recorded in the eCRF or (in case of administration by a home nurse or concierge 
service for visit at the trial site) will be documented and transferred to the eCRF.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
63
The investigator, institution, or the head of the medical institution (where applicable) is 
responsible for IMP accountability, reconciliation, and record maintenance (ie, receipt, 
reconciliation, and final disposition records). 
Further guidance and information for the final disposition of unused IMP are provided in the 
pharmacy manual.
7.3.
IMP Compliance
Patients will receive weekly SC administrations of IMP over a maximal treatment period of 
61 weeks (up to 12 weeks with optional 1 additional week in Stage A and 48 weeks in Stage B).
During Stage A, all efforts will be made to ensure that the patient receives at least 
4 administrations of IMP within the allowed time windows. In addition, during the rest of the 
trial, also all efforts will be made to ensure that the patient receives the IMP as planned.
The treating physician should ensure treatment compliance by stating that compliance is 
necessary for the potential effectiveness of patient’s treatment and for the validity of the trial.
The prescribed dose, timing, and mode of administration cannot be changed. All dates and start 
and end time of IMP administration and any deviations from the intended regimen must be 
recorded (see Section 7.2).
Any patient who misses a single dose (within the window of ±2 days of the planned 
administration day) will not make up for the missed dose and will receive the next dose as 
scheduled in the SoA (see Section 1.3). Also, in case a dose needs to be delayed for more than 
5 days, the dosing should be skipped to ensure 2 consecutive doses are given with an interval of 
at least 3 days. 
The patient must not miss more than 2 consecutive doses and must not miss more than 10% of 
the total planned doses that should have been taken (for example, 1 missed dose in Stage A is 
allowed and a maximum of 4 missed doses during the 48-week Stage B period will be permitted, 
if doses missed are not consecutive) (see also Section 9.7).
If a patient misses more than 2 consecutive doses or more than 10% of the total planned doses 
that should have been taken, the patient will be excluded from the per protocol analysis. 
In case of lack of compliance, the number of missed doses will be captured, but the patient can 
remain in the trial (unless the patient withdraws his/her consent). The investigator should discuss 
the reason with the patient and should stress the importance of IMP compliance. 
7.4.
Prior Treatments and Concomitant Medications
Eligible patients, who are treated at the time of screening with pulsed corticosteroids, or oral 
 mg/day, and/or IVIg or SCIg will stop 
taking their current treatment for CIDP at the time they start the run-in period (ie, RI-V1).
Clinically relevant prior treatments received by the patient including: 
Previous treatments or procedures for CIDP with patient’s response and reason for 
changing treatment/dose 
Previous Non-CIDP treatment or procedures in the last 6 months 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
64
Treatment related to malignancies in at least the last 3 years
must be recorded in the eCRFs. Information should include start and stop dates and tick box for 
those continuing as concomitant medication. 
All concomitant medications whether allowed or not must be recorded in the eCRFs. 
Prior and concomitant medications will be coded using the World Health Organization (WHO) 
Drug Dictionary drug codes. Concomitant medications will be further coded to the appropriate 
Anatomical Therapeutic Chemical code indicating therapeutic classification.
Any vaccine or medication, including over-the-counter and prescription medicines, vitamins, 
and/or herbal supplements, that the patient is receiving at the time of enrollment or receives 
during the trial must be recorded with the following information provided: 
Reason for use 
Dates of administration including start and end dates 
Dosage information including dose and frequency 
As part of prior medication, details collected at screening should include all information the 
patient or caregiver can remember about previous vaccinations received, including 
administration date and brand name, if known (note: if in the past a same vaccine was received 
more than once, including as booster, only the last one is to be collected). Any vaccination 
received during the trial, including administration date and brand name, will be entered as 
concomitant medication.
The medical monitor should be contacted if there are any questions regarding concomitant or 
prior therapy. 
Symptomatic treatments will be left to the discretion of the investigators.
7.4.1.
Permitted Medication
Medication not used for the treatment of CIDP is permitted, if not part of the groups of 
medication specifically prohibited in Section 7.4.2.
Any kind of vaccination, except for live-attenuated vaccines, is allowed at the discretion of the 
investigator. In patients who receive a vaccination during the trial, data on the interaction 
vaccine-IMP and on the efficacy of the vaccine shall be collected.
7.4.1.1.
Patient’s Medication in Between Trial Visits
As this is an outpatient trial, special care will be taken in questioning the patients on any 
medication, and patients will be asked to document details of concomitant medications, which 
will be evaluated by site personnel and transferred by an authorized trial team member to the 
eCRF. In addition, for IMP administrations in between trial visits, the home nurse will record the 
IMP dosing information on a source document and will provide this source document to the trial 
site for entry in the eCRF. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
65
7.4.1.2.
Treatment in the Event of Clinical Deterioration During Stage B 
If clinical deterioration, defined as an increase of adjusted INCAT score with respect to Stage B
baseline (see Section 2.2), is detected in any patient during Stage B, then the patient will be 
eligible immediately for enrollment in the OLE trial ARGX-113-1902 after completing the early 
discontinuation visit (which corresponds with the first visit of the OLE trial). Patients will also 
have the possibility to enter the safety follow-up period and complete the trial without rolling 
over to the OLE trial. These patients will be treated as considered appropriate by the investigator 
(see Section 5.1.4).
Double-blinding will be maintained about the original treatment assignment during the whole 
trial, even at the time of trial completion or withdrawal from the trial.
7.4.2.
Prohibited Medications
Medication for treatment of CIDP will be continued during the screening period and will be 
discontinued from the start of the run-in period (RI-V1) onwards: 
Intravenous or subcutaneous immunoglobulin therapy;
Pulsed corticosteroids and
 mg/day. 
Note: If tapering is required, it should be initiated during the screening period according 
to local practice. 
The following medications or treatments are not permitted from signing the ICF at screening 
during the entire trial:
Plasmapheresis;
Total lymphoid irradiation; 
Any other IgG therapy; 
Any stem cell-based therapy, including bone marrow transplantation like autologous stem 
cell transplant (ASCT) and allogenic cells transplants;
Any cytokine or anti-cytokine therapy; 
Systemic corticosteroids, including oral, for any other indication than CIDP; 
Cyclophosphamide, interferon, tumor necrosis factor–alpha inhibitors, fingolimod, 
methotrexate, azathioprine, mycophenolate, or any other immunomodulating or 
immunosuppressive medications or procedures; 
Rituximab, alemtuzumab, or any other monoclonal antibody for immunomodulation; 
Any investigational drug or experimental procedure; 
Live-attenuated vaccines 
Note: Receiving an inactivated, sub-unit, polysaccharide, or conjugate vaccine any time 
before screening is not prohibited. 
Use of complementary therapies, including traditional Chinese medicines and herbal 
remedies, containing any of the following: naturally derived glucocorticoids; medication 
with clinical evidence-based immunosuppressive, immunomodulatory, peripheral or 
central nervous system effects; or procedures (eg, acupuncture) for any neurological 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
66
condition within 4 weeks or 5 half-lives (whichever is longer) prior to IMP dosing and 
agreed not to use during the trial.
If the administration of a non-permitted concomitant drug becomes necessary during the clinical 
trial, eg, because of AEs, the patient has to discontinue IMP, as described in Section 8.2.
7.5.
Medical Care of Patients after End of Trial
After a patient has completed the trial, but is not eligible or not willing to participate in the OLE 
trial ARGX-113-1902, or has withdrawn/discontinued early, the most appropriate treatment will 
be administered, if required, in accordance with the trial site’s standard of care and generally 
accepted medical practice depending on the patient’s individual needs. 
7.6.
Dose Modification
There will be only 1 dose of IMP for each IMP administration. Dose modification is not allowed 
during the trial. 
7.7.
Intervention After the End of the Trial
The OLE trial ARGX-113-1902 will be open to patients if the following criteria are met:
Clinical deterioration during Stage B (defined as an increase of adjusted INCAT score 
with respect to Stage B baseline; see Section 2.2);
Completion of the week 48 visit of Stage B without any clinical deterioration (see 
Section 2.2);
The 88th event needed for the primary endpoint analysis is observed (see 
Section 10.3); in this case all patients who are receiving IMP in either Stage A or 
Stage B have the possibility to roll over to the OLE trial (see Section 5.6).
Additionally, at the time of the 88th event, patients in run-in will also be given the option to roll 
over to the OLE trial after performing an early discontinuation visit. 
Patients who are defined as a non-responder during Stage A and/or discontinue the trial will be 
treated as considered appropriate by the investigator (see Section 7.5).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
67
8.
DISCONTINUATION OF IMP AND PATIENT 
DISCONTINUATION/WITHDRAWAL
Patients will be informed that they have the right to withdraw from the trial at any time, without 
prejudice to their medical care, and that they are not obliged to state their reasons. Any 
discontinuation/withdrawal must be fully documented in the eCRF and source documents, 
including the reason (if stated), and should be followed up by the investigator. 
Patients can have a temporary treatment discontinuation (see Section 8.1), a premature 
permanent treatment discontinuation (see Section 8.2), or can withdraw from further trial 
participation (see Section 8.3).
For premature permanent treatment discontinuation and withdrawal from further trial 
participation, the following general rules apply: 
As far as possible, any withdrawal of a patient should be decided after consultation 
with the medical monitor, who acts on behalf of the sponsor. However, withdrawal 
remains at the discretion of the treating physician. 
The reasons for any withdrawal are to be fully documented in the eCRF. 
The criteria for screening and randomization are to be followed explicitly. However, the 
development of a condition that would have prevented a patient’s entry into the trial according to 
the selection criteria is not a reason per se for withdrawal. If it is noted that a patient who does 
not meet 1 or more of the inclusion criteria and/or meets 1 or more of the exclusion criteria is 
inadvertently dosed, the medical monitor at the sponsor’s designated CRO and the sponsor’s 
medical director must be contacted immediately.
If a patient has failed to attend scheduled trial assessments, the investigator must determine the 
reasons and the circumstances as completely and accurately as possible.
In particular, attempts should be made to contact the patient to determine whether or not the 
reason for not returning is an AE. Likewise, if a patient declares his/her wish to discontinue from 
the trial, eg, for personal reasons, an attempt should be made to establish whether or not the true 
reason is an AE (bearing in mind that the patient is not obliged to state his/her reasons).
8.1.
Temporary Interruption of IMP
A patient who does not need to be permanently discontinued from treatment might have a 
temporary interruption from treatment up to 2 consecutive doses or not more than 10% of the 
total planned doses that should have been taken (see Section 7.3). This implies that a patient can 
miss 1 IMP dose during Stage A and up to 4 IMP doses during Stage B (but not more than 
2 consecutive doses). 
Patients who interrupted the trial medication for a longer time will be excluded from the 
per-protocol analysis.
Patients for whom treatment is temporarily interrupted will have to complete the assessments of 
the corresponding visit (see SoA in Section 1.3) unless they withdraw their consent. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
68
8.2.
Permanent Early Discontinuation of IMP
Permanent early discontinuation from treatment means that the patient stops receiving the 
ongoing IMP treatment and does not restart IMP treatment, however, informed consent is not 
withdrawn. These patients will continue to be followed up for safety and efficacy/disease 
severity in the trial according to the SoA for the remaining visits of Stage A (excluding the 
optional additional visit at A-V13) or the remaining visits of Stage B, whichever is applicable 
(see Section 1.3), including the safety follow-up visit in case IMP was stopped less than 28 days 
before the last trial visit. Note that patients with an early discontinuation from treatment during 
Stage A will not be randomized in Stage B. These patients will stop the trial at the End of 
Stage A visit. Furthermore, patients with an early discontinuation from treatment during Stage B
will not be able to roll over to the OLE trial (see Section 5.6).
A patient must be permanently discontinued from further trial medication in the event of any of 
the following: 
If in the opinion of the investigator and/or sponsor, the discontinuation of the IMP is 
necessary for the patient’s safety.
Patient develops an SAE or AE that contraindicates further administration of IMP in the 
investigator’s opinion, or an AE of CTCAE grade 4 that is considered related to IMP by 
the sponsor. 
Use of non-permitted concomitant drug, as defined in Section 7.4.2.
Psychiatric conditions. 
Note: In the case of severe depression, suicidal ideation, or attempted suicide, trial 
medication must be at least temporarily interrupted until the patient’s psychiatric 
condition has been fully evaluated. A psychiatrist should be consulted whenever 
necessary. Treatment may be resumed only after consultation with the sponsor. 
Withdrawal from the trial is mandatory in case of meeting any of the withdrawal criteria (see 
Section 8.3 ‘Early Withdrawal From the Trial’).
A patient may discontinue receiving clinical trial medication under the following circumstances:
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 
treatment will depend on the evaluation on a case by case basis, which should be taken 
after discussion with the medical monitor. Patients who, after evaluation of the above 
situations, are not discontinued from treatment, may have a temporary interruption from 
treatment (see Section 8.1).
If permanent discontinuation from IMP occurs, the patient will be encouraged to continue with 
trial-related assessments for the remaining visits of Stage A (excluding the optional additional 
visit at A-V13) or the remaining visits of Stage B, whichever is applicable, according to the 
general SoA (see Section 1.3), including the safety follow-up visit in case IMP was stopped less 
than 28 days before the last trial visit. No Early Discontinuation visit should be conducted unless 
the patient requests to withdraw from the trial or in case of deterioration (see Section 2.2 and 
Section 8.3). 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
69
It is not mandatory to withdraw the patients from the trial, if withdrawal criteria are not met (see 
Section 8.3).
8.3.
Early Withdrawal From the Trial
Early withdrawal from the trial is defined as the permanent cessation of further participation in 
the trial prior to its planned completion.
Patients are free to discontinue the trial at any time without giving their reasons. 
A patient must be withdrawn from further trial participation in the event of any of the following: 
Withdrawal of the patient’s consent.
A patient’s participation is to be terminated immediately upon his/her request. The 
investigator should seek to obtain the reason and record this in the eCRF. 
The IMP treatment code is broken.
Occurrence of pregnancy.
The investigator, after discussion with the sponsor’s medical director, deems it is in 
the patient’s best interest.
Death or lost to follow-up. 
For patients who permanently discontinued IMP and continue their current stage of 
the trial: In case they deteriorate (defined as an increase of adjusted INCAT score 
with respect to baseline of their current stage; see Section 2.2).
(During Stage 
 points from Stage A
baseline (D1A).
In case of premature withdrawal from the trial, all trial assessments scheduled for the Early 
Discontinuation visit (see Section 1.3) shall be performed, if possible, preferably immediately 
after the patient’s last administration of trial drug, and all efforts should be made that the patient 
will have a final follow-up visit 28 days after the last IMP dose. The treating physician will then 
offer the patient the best available alternative treatment. In any case, the appropriate eCRF 
section must be completed. 
The primary reason for discontinuation must be recorded in the appropriate section of the eCRF 
and all efforts must be made to complete and report the assessments as thoroughly as possible. 
A complete final evaluation at the time of the patient’s withdrawal should be made and any AEs 
should be followed up until resolution. 
A termination eCRF page should be completed for every patient who receives investigational 
product, whether or not the patient completes the trial. The reason for any early discontinuation 
should be indicated on this form. 
If the patient withdraws consent for disclosure of future information, the sponsor may retain and 
continue to use any data collected before such a withdrawal of consent. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
70
8.4.
Replacement
Patients, who prematurely discontinued from the trial after having received trial treatment, will 
not be replaced and their unique identification and treatment randomization numbers will not be 
reallocated.
8.5.
Re-screening
Patient who withdrew from the trial during the screening or run-in phase and before the trial 
medication was started may be re-screened once if in the opinion of the investigator the patient 
would benefit from the trial treatment and the withdrawal reasons or criteria no longer apply, and 
permission has been granted by the medical monitor. 
8.6.
Lost to Follow-up
A patient will be considered lost to follow-up if he or she repeatedly fails to return for scheduled 
visits and is unable to be contacted by the trial site. 
The following actions must be taken if a patient fails to return to the clinic for a required trial 
visit:
The site must attempt to contact the patient and reschedule the missed visit as soon as 
possible and counsel the patient on the importance of maintaining the assigned visit 
schedule and ascertain whether or not the patient wishes to and/or should continue in 
the trial.
Before a patient is deemed lost to follow-up, the investigator or designee must make 
every effort to regain contact with the patient (where possible, 3 telephone calls and, 
if necessary, a certified letter to the patient’s last known mailing address or local 
equivalent methods). These contact attempts should be documented in the patient’s 
medical record.
Should the patient continue to be unreachable, he/she will be considered withdrawn 
from the trial.
Discontinuation of specific sites or of the trial as a whole are handled as part of Appendix 1 (see 
Section 11.1.10).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
71
9.
TRIAL ASSESSMENTS AND 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 the 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. 
The timing of all trial procedures is provided in the SoAs in Section 1.3. Protocol waivers or 
exemptions are not allowed. Immediate safety concerns should be discussed with the sponsor 
immediately upon occurrence or awareness to determine if the patient should continue or 
discontinue IMP. Adherence to the trial design requirements, including those specified in the 
SoA, is essential and required for trial conduct. All screening evaluations must be completed and 
reviewed to confirm that potential patients meet all eligibility criteria. The investigator will 
maintain a screening log to record details of all patients screened and to confirm eligibility or 
record reasons for screening failure, as applicable.
A re-test in case of an out-of-range clinical laboratory test value to determine a patient’s 
eligibility is allowed at the discretion of the investigator and in agreement with the sponsor. 
The maximum amount of blood collected from each patient over the duration of the trial, 
including any extra assessments that may be required, will be approximately 500 mL (with a 
maximum of 40 mL per trial visit).
At each trial visit, all assessments as listed in the SoA in Section 1.3 should be completed before 
IMP administration at the site.
9.1.
Serology Testing for Infections at Screening
At screening, an assessment is made if patients have clinical symptoms and/or signs of an active 
infection. These patients cannot be included in the trial (see exclusion criterion #7 in 
Section 6.2). Patients who might have serology results indicative of presence of microorganisms 
in the body, but who do not present evidence of an active infection, are not excluded. If an 
infection occurs during the trial, it shall be reported as an AE and treated accordingly. If deemed 
necessary, in selected cases, patients may be discontinued from the trial.
Specific attention is given to the following infections: 
Hepatitis B Virus (HBV):
Patients with an active HBV infection (acute or chronic) at screening cannot be included 
in the trial. The following serologic combinations of serologic markers will be used to 
identify an active HBV infection (US Centers for Disease Control and Prevention): 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
72
HBsAg
Anti-HBc
Anti-HBs
Note
POSITIVE
POSITIVE
NEGATIVE
Acute or chronic active hepatitis B: patient 
cannot be enrolled in the trial
NEGATIVE
POSITIVE
NEGATIVE
Patient cannot be enrolled in the trial if 
considered to be an indicator of a ¨Low 
level” chronic infection with impairment of 
liver functions*
* As determined by a medical doctor with sufficient expertise in the field of hepatology or infectious diseases 
(may require performance of additional tests such as HBV viral load)
Abbreviations: HBc = hepatitis B core; HBs = hepatitis B surface; HBsAg = hepatitis B surface antigen.
Patients who are seropositive because of an HBV vaccination or who are positive due 
to naturally recovered infection can be included.
Hepatitis C Virus (HCV):
Patients with an active HCV infection (acute or chronic) at screening cannot be included 
in the trial. The following serologic marker will be used to identify an active HCV 
infection (US Centers for Disease Control and Prevention): 
HCV-Ab
Note
POSITIVE
Acute or chronic active hepatitis C: patient cannot be enrolled in the trial
Abbreviations: Ab = antibody; HCV = hepatitis C virus.
Human Immunodeficiency Virus (HIV): 
HIV positive patients with no AIDS-defining condition* or CD4 count >200 cells/mm3
can be included in the trial.
HIV positive patients with an AIDS-defining condition* (or CD4 count 
cells/mm3) at screening cannot be included in the trial. 
HIV
Clinical Condition or CD4 count
Note
POSITIVE
AIDS-defining condition* or CD4 count 
cells/mm3
Diagnosis of AIDS: patient 
cannot be included in the trial
* AIDS-defining conditions are defined as any of the following:
- Cytomegalovirus retinitis with loss of vision
- Pneumocystis Jiroveci Pneumonia
- Chronic Intestinal Cryptosporidiosis
- HIV-related encephalopathy
- Mycobacterium tuberculosis (pulmonary or extrapulmonary)
- Invasive cervical cancer
Mycobacterium tuberculosis (TB): 
Patients with clinical symptoms/signs of TB cannot enter the trial. TB test (Quantiferon) 
will be performed at screening and may be repeated during the trial, if necessary. If a 
negative Quantiferon test at screening turns positive during the trial, a clinical work up 
will be applied. If clinical symptoms or signs of TB occur, it will be reported as an AE 
and treated accordingly. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
73
9.1.1.
Vaccination History and Vaccinations During the Trial 
At screening, the investigator will ask the patient about all vaccination received in the past. Any 
vaccination information the patient or caregiver can remember should be recorded in the eCRF 
(with the brand name of the vaccine and date of vaccine administration recorded, if possible). If
in the past a same vaccine was received more than once, including as booster, only the last one is 
to be collected. Any vaccination received during the trial, including administration date and 
brand name, will be entered as concomitant medication (see Section 7.4).
For patients who provide separate consent, the titers of produced vaccination antibodies will be 
measured using retained blood samples (left over blood samples taken for other tests) during the 
trial (see Section 11.2).
9.2.
Columbia-Suicide Severity Rating Scale (C-SSRS) at Screening
At screening, suicidality will be assessed using the Columbia-suicide severity rating scale (C-
SSRS). The questionnaire is included in Section 11.11. Patients with a high suicide risk will be 
excluded from the trial. Patients with a high suicide risk are defined as patients with a positive 
answer to questions #4 and/or #5 of the suicidal ideation subscale (over the past 3 months); 
and/or any positive answer to the suicidal behavior subscale (over the past year). Any positive 
answer to the above questions under “Lifetime/Time he/she felt most suicidal” should be 
carefully evaluated for any current risk of suicide by the investigator prior to trial entry. 
During the trial, suicidality will be assessed by specifically answering 1 question from the 
PHQ-9 (Patient Health Questionnaire-9) depression questionnaire (see Section 9.15).
9.3.
Medical 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. 
9.4.
Efficacy Assessments
Planned time points for all efficacy assessments are provided in the SoA in Section 1.3.
During all visits, the efficacy assessments should be performed first, before any other 
trial-specific procedure, except for the ICF process during screening.
Where required, training will be provided for the efficacy instruments. 
9.4.1.
Adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) Disability 
Score
The INCAT score (see Section 11.7) is a 10-point scale that covers the functionality of legs and 
arms and has been successfully used to measure treatment effects in various CIDP trials. Scores 
for arm disability range from 0 ("No upper limb problems") to 5 ("Inability to use either arm for 
any purposeful movement"), and scores for leg disability range from 0 ("Walking not affected") 
to 5 ("Restricted to wheelchair, unable to stand and walk a few steps with help"). The INCAT 
(total) score is the sum of these 2 scores and ranges from 0 to 10. For the "adjusted" INCAT 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
74
score, changes in the function of the upper limbs from 0 (normal) to 1 (minor symptoms) or from 
1 to 0 will not be recorded as deterioration or improvement because these changes are not 
considered clinically significant.
There are 3 different baseline INCAT scores during the trial, at the beginning of each stage. Each 
baseline INCAT score is always the total INCAT score (not the adjusted INCAT score, which is 
used for post-baseline assessments):
Baseline run-in period = Total INCAT score at the first visit of the run-in period (RI-
V1)
Baseline Stage A = Total INCAT score at D1A (ie, the first visit of Stage A [A-V1])
Baseline Stage B = Total INCAT score at D1B (ie, the first visit of Stage B [B-V1])
Note: The baseline total INCAT score is calculated as the sum of the arm and leg sub 
score, without adjustment of the arm sub score.  
For the post-baseline visits, the adjusted INCAT score calculation is based on the baseline of the 
corresponding stage. 
Sites are selected based on their documented experience and expertise in the use of the 
assessments and questionnaires used in this trial. All sites will have a document knowledge and 
recent experience in the use of INCAT.
9.4.2.
Medical Research Council (MRC) Sum Score
The 6-point MRC sum score evaluates motor strength/weakness (see also Section 11.8):
0= complete paralysis
1= minimal contraction
2= Active movement with gravity eliminated
3= Weak contraction against gravity 
4= Active movement against gravity and resistance 
5= Normal strength 
The MRC Sum Score is evaluated bilaterally on 6 muscle groups of upper and lower limbs in 
order to obtain a summed score between 0 and 60: 
Arm abductors 
Elbow flexors 
Wrist extensors
Hip flexors 
Knee extensors 
Foot dorsiflexors 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
75
9.4.3.
Inflammatory Rasch-built Overall Disability Scale (I-RODS)
The I-RODS (see Section 11.9) is a PRO measure on disability and assesses the limitations of 
activities and social participation in patients with inflammatory neuropathies like Guillain-Barré 
syndrome (GBS), CIDP, and gammopathy-related polyneuropathy (MGUSP). The I-RODS is a 
24-item scale, with each item representing a common daily activity that range from very difficult 
to do, like running or dancing, to very easy to do, like eating or reading a book. Higher scores 
indicate less disability. The raw sum scores of the I-RODS (range: 0 to 48) will be converted to a 
centile metric score, ranging from 0 (most severe activity and social participation restrictions) to 
100 (no activity and social participation limitations).19
Although the I-RODS as a PRO can be considered subjective, the scale has shown to correlate 
well with grip strength, which is a direct measure of muscle strength.20
When assessed at home, the patient will record the measurements.
9.4.4.
Mean Grip Strength
A handheld Martin vigorimeter will be used for this assessment. Patients will perform 
3 assessments for each hand in an arbitrary order (with a rest period of approximately 30 seconds 
between each assessment) always at approximately the same time during the day. The mean grip 
strength for each hand will be used to determine disease activity. 
When assessed at home, the patient will record the measurements.
9.4.5.
Timed Up and Go (TUG) Test
The TUG test is a simple test used to assess a person's mobility and requires both static and 
dynamic balance.21
In the TUG test, the time expended to rise from a chair, walk 3 meters, turn around, walk back to 
the chair, and sit down is measured. During the test, the person is expected to wear their regular 
footwear and use any mobility aids that they would normally require.
9.5.
Safety Assessments
Planned time points for all safety assessments are provided in the SoA in Section 1.3.
9.5.1.
Vital Signs and Physical Examination
The assessment of vital signs (systolic and diastolic blood pressure, heart rate, and body 
temperature) will be performed at the time points indicated in the SoA (see Section 1.3). Vital 
signs will be measured before blood collections. 
Blood pressure (systolic and diastolic) and heart rate will be measured using standard equipment 
in semi-supine position after having rested for at least 5 minutes.
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 during 
the trial as indicated in the SoA (see Section 1.3). For the assessment of height and weight, 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
76
patients will be required to remove their shoes and wear light indoor clothing. Unintentional 
weight loss of >10% of normal body weight over a period of 6 months or less should be reported 
as an AE. Clinically relevant findings observed after signing informed consent and meeting the 
definition of an AE (new AE or worsening of previously existing condition) must be recorded on 
an AE page of the eCRF.
9.5.2.
Electrocardiograms
At screening and during the trial (as indicated in the SoA in Section 1.3), 12-lead ECGs will be 
recorded with the patient in a supine position, suitably rested (for at least 5 minutes).
At screening and baseline of Stage A (D1A), triplicate 12-lead ECGs will be performed before 
administration of the first dose of IMP; the results should be reviewed by the investigator to 
confirm that the patient may be dosed (see exclusion criteria in Section 6.2). A local cardiology 
consult should be sought if the investigator deems it necessary. 
ECGs will be acquired according to instructions provided by a centralized ECG reading facility 
where the ECGs will be centrally assessed. At a minimum, interval data (PR, QT, QTcF 
[Fridericia corrected QT interval], and QRS intervals), ventricular rate, and overall interpretation 
will be recorded for each ECG. Data will be transferred electronically for inclusion in the 
database.
Clinically relevant findings observed after signing informed consent and meeting the definition 
of an AE (new AE or worsening of previously existing condition) must be recorded on an AE 
page of the eCRF.
9.5.3.
Clinical Safety Laboratory Assessments
Blood and urine samples for safety assessments (hematology, biochemistry, and urinalysis) will 
be taken at screening, on D1A before IMP dosing, and further during the trial as specified in the 
SoA in Section 1.3. See Section 11.2 for a list of clinical laboratory tests to be performed.
Blood and urine samples for clinical chemistry, hematology, urinalysis, and serology testing will 
be collected according to the local standard procedures. 
The samples will be analyzed at a centralized certified laboratory. In the exceptional 
circumstances that samples cannot be sent to a central laboratory, a local laboratory can be used.
Further details of sampling, handling, storage, and transportation of the samples will be 
described in the laboratory manual. The actual sample collection date and time will be collected. 
The fasting status will also be collected. If the glucose or lipids results from the screening visit 
are elevated, a repeat sample under fasting condition (for at least 8 hours) will be required. 
Clinical laboratory tests will be reviewed for results of potential clinical significance at all time 
points throughout the trial, with the exception of total protein and albumin results after the 
Stage B baseline visit, which will be kept blinded for the site. A system will be implemented to 
notify the investigator in case of out-of-range values to allow for appropriate safety follow-up. 
Clinically relevant findings observed after signing informed consent and meeting the definition 
of an AE (new AE or worsening of previously existing condition) must be recorded on an AE 
page of the eCRF.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
77
Additional safety samples may be collected if clinically indicated at the discretion of the 
investigator. These additional samples will be analyzed centrally, too. Only laboratory testing 
needed for the assessment of a specific AE/SAE, which is not already foreseen in the laboratory 
test battery, will be analyzed locally. Such a request and the medical need has to be discussed 
a priori with the medical monitor. The results of this local testing will be added to the AE/SAE 
follow-up documentation. 
For all female patients of childbearing potential, a serum pregnancy test will be performed 
centrally at screening, and a urine pregnancy test will be conducted and analyzed locally at the 
site (on the urine samples taken for urinalysis) every 4 weeks during the rest of the trial. 
Besides the urine pregnancy test and additional safety samples performed at the discretion of the 
investigator which will be conducted and analyzed locally, all samples for safety assessments 
will be analyzed centrally.
9.6.
Adverse Events and Serious Adverse Events
AEs, defined in Section 11.4, will be reported by the patient and/or by the investigator. The 
treating physician (see Section 5.4.1 for the two physician concept) and any qualified designees 
are responsible for detecting, documenting, and recording events that meet the definition of an 
AE or SAE (see Section 11.4) and remain responsible for following up AEs that are serious, 
considered related to IMP administration or trial procedures, or that caused the patient to 
discontinue the IMP or the trial (see Section 8). These AEs will be monitored until stabilization, 
resolution, or loss to follow-up (for serious events, SAE forms need to be completed; see 
Section 11.4).
9.6.1.
Pregnancy
All initial reports of pregnancy in female patients and in female partners of male patients who 
participate in the trial will be collected after the first administration of IMP (Stage A baseline 
[D1A]) until the last trial visit.
Note that in this trial patients must comply with recommendations for contraceptive use in order 
to avoid exposure to IMP of an existing embryo/fetus to IMP (see inclusion criteria in 
Section 6.1).
If a pregnancy is reported, the investigator should inform the sponsor within 24 hours of learning 
of the pregnancy and will contact the patient at the expected time of delivery for follow-up. 
Abnormal pregnancy outcomes (eg, spontaneous abortion, fetal death, stillbirth, congenital 
abnormality, ectopic pregnancy, birth defect) will be considered SAEs and will be reported as 
such. 
9.6.2.
Adverse Events of Special Interest (AESI)
An adverse event of special interest (AESI, which can be serious or non-serious, and/or related 
or not related) is 1 of scientific and medical concerns specific to the sponsor’s product or 
program (eg, underlying condition being investigated, mechanism of action/potential 
immunosuppression), for which ongoing monitoring and rapid communication by the 
investigator to the sponsor can be appropriate. Such an event might warrant further investigation 
in order to characterize and understand it. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
78
Efgartigimod treatment induces reductions in IgG levels, and there is a potential risk for 
infections associated with the reduction in IgG levels. The occurrence of an infection will be an 
AESI. This interest pertains to both newly diagnosed or reactivated, latent infections. Hereby any 
occurrences of an infection will have to be reported accordingly. 
9.7.
Medication Error
For this trial, a variation less than ±10% of the amount of efgartigimod PH20 SC that should be 
injected for each administration will not be considered an overdose/underdose or medication 
error, while a variation greater than ±10% of the intended amount of efgartigimod PH20 SC will 
be considered a medication error and/or overdose with or without AEs. 
A patient must not miss more than 2 consecutive doses and must not miss more than 10% of the 
total planned doses that should have been taken. Furthermore, 2 consecutive doses should be 
given with an interval of at least 3 days (see Section 7.3).
An overdose is defined as a deliberate or accidental administration of IMP to a patient, at a dose 
greater than that which was assigned to that patient per the trial protocol. 
A medication error is any preventable incident that may cause or lead to inappropriate IMP use 
or patient harm while the IMP is in the control of the health care professionals. Such incident 
may be due to health care professional practice, product labeling, packaging and preparation, 
procedures for administration, and systems, including the following: prescribing, order 
communication, nomenclature, compounding, dispensing, distribution, administration, education, 
monitoring, and use. 
In case of suspected overdose or medication error, the patient should be treated according to 
standard medical practice based on the investigator’s judgment. The suspected overdose or 
medication error with the quantity of the excess dose should be documented in the eCRF 
including the additional AE, if any. 
9.8.
Patient Card
Patients must be provided with the address and telephone number of the Treating Physician, and 
of the main contact for information about the clinical trial. The investigator must therefore 
provide a “Patient 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 or sponsor designee. Patients must be instructed 
to keep the card in their possession at all times.
9.9.
Pharmacokinetics
Blood samples for determination of serum concentrations of efgartigimod will be collected from 
D1A pre-dose onwards and at certain time points up to the follow-up visit as specified the SoA 
in Section 1.3.
Blood for the PK samples will be collected as described in the laboratory manual. Blood samples 
may also be used to cross-validate the PK assay in CIDP matrix (serum).
Concentrations of efgartigimod in serum will be determined using a validated assay. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
82
10.
STATISTICAL CONSIDERATIONS
The statistical analyses will be performed by the sponsor’s designated CRO using statistical 
analysis systems SAS® (SAS Institute, Cary, NC, US) version 9.4 or higher, and the software 
package R, if applicable. The standard operating procedures (SOPs) and work instructions of the 
sponsor’s designated CRO will be used as the default methodology if not otherwise specified.
A detailed and comprehensive Statistical Analysis Plan (SAP) will be written and signed-off 
prior to final analysis database lock. For the Stage A interim analysis (see Section 10.6), a 
separate stand-alone interim SAP will be written and signed-off prior to interim database lock. 
Minor changes to the statistical methods set out in this protocol do not require a protocol 
amendment but must be documented (as changes from the protocol) in the SAP and in the trial 
report(s).
The final statistical analyses will be performed once all patients have rolled over to the OLE trial 
ARGX-113-1902 or have withdrawn, and the database has been cleaned and locked.
10.1.
Statistical Methods
10.1.1.
Summary Tables, Figures, and Listings 
Summary tables will summarize endpoints (outcomes) by treatment group and time point 
(eg, visit). For continuous variables, the number of patients (with non-missing values), mean, 
standard deviation, median, quartiles, minimum and maximum will be presented. For categorical 
variables, for each category, the number of patients (count) and percentage will be presented for 
patients without missing values.
All summary Tables and Figures will be supported by full patient listings. 
10.1.2.
Hypothesis Testing and Confidence Intervals
Unless otherwise stated, all statistical tests will be two-sided and will be conducted at a 5% 
significance level. Two-sided 95% confidence intervals (CIs) will be provided. 
10.1.3.
Populations for Analyses 
Safety population: The Stage A safety population (SAF-A) will include all patients who 
received at least 1 dose of IMP in Stage A. The Stage B safety population (SAF-B) will include 
all patients who received at least 1 dose of IMP in Stage B.
The safety data analysis will be presented as follows:
Stage A will be done on the Stage A safety population (SAF-A).
Stage B will be done on the Stage B safety population (SAF-B).
Stages A and B combined on the Stage A safety population (SAF-A).
Stages A and B combined on the Stage B safety population (SAF-B).
Pharmacokinetic population: The PK population will include all patients in the safety 
population for whom at least 1 serum PK concentration is available.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
83
Pharmacodynamic population: The PD population will include all patients in the safety 
population for whom at least 1 serum PD concentration is available.
Immunogenicity population: The immunogenicity population will include all patients in the 
safety population for whom at least 1 ADA sample is available.
Modified intent-to-treat (mITT) population: The mITT population will include all randomized 
patients who received at least 1 dose of IMP in Stage B.
Per protocol (PP) population: The PP population comprises all Stage B patients in the mITT 
population for whom no major protocol deviation was reported. 
The efficacy analyses for the Stage B will be based on the mITT population. Supportive analyses 
for the primary endpoint will be conducted on the PP population. 
The Stage A efficacy analysis will be conducted on the Stage A safety population (SAF-A).
10.1.4.
Randomization and Stratification
Stage A is non-randomized; all patients will receive efgartigimod PH20 SC in an open-label 
manner.
In Stage B, patients will be randomized to double-blind efgartigimod PH20 SC or placebo in a 
1:1 ratio. Patients will be stratified according to their prior CIDP medication and the decrease of 
adjusted INCAT score during Stage A by the following: 
Prior CIDP medication
Treatment-naïve (see inclusion criterion #6 in Section 6.1 for definition); 
Pulsed corticosteroid treatment or oral corticosteroids equivalent to 
 mg/day; 
IVIg or SCIg treatment. 
Adjusted INCAT score 
No change in adjusted INCAT score during Stage A;
Adjusted INCAT 
 point during Stage A.
The randomization list for Stage B will be created using permutated blocks and implemented 
using the IRT. 
10.1.5.
General Considerations 
10.1.5.1.
Trial Baselines
The baseline value for the run-in period will be the assessment recorded at visit R1-V1.
The baseline value for Stage A will be the last assessment prior to the first dose of open-label 
trial medication in Stage A.
The baseline value for Stage B will be the last assessment prior to the first dose of double-blind 
trial medication in Stage B.
10.1.5.2.
Visits and Dates
All trial visits will be recalculated based on actual dates and will be referred to as “analysis 
visits” which will be used in the statistical analyses. The rules for calculating the analysis visits 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
84
will be documented in the SAP. The actual visit recorded in the database and the analysis visits 
will be presented in the listings.
Rules for imputing partial dates or missing dates will also be documented in the SAP. 
10.1.6.
Blinded Data Review Meeting
A blinded data review meeting will be convened after the data has been cleaned but before the 
final lock and unblinding. A data review meeting will also be convened before the interim 
analysis database lock. The review will be performed per the requirements of International 
Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use 
(ICH) Guideline E9.33
10.2.
Statistical Hypotheses
The statistical hypotheses were derived from the trial objectives as stated in Section 4.
Stage A:
For the interim analysis, the percentage of ECI responders on efgartigimod PH20 SC will 
be summarized using an exact one-sided Clopper-Pearson 90% CI. For the final analysis, 
the percentage of ECI responders on efgartigimod PH20 SC will be summarized using an 
exact Clopper-Pearson 2-sided 95% CI. This 95% two-sided Clopper-Pearson CI will be 
used to compare the results of this study with results obtained in historical controls such as 
the PATH trial (van Schaik et al, 2018)15
Stage B:
Null hypothesis: The event rate of efgartigimod PH20 SC compared to placebo is 1
(ie, hazard ratio = 1)
(ie,
As Stage A and Stage B testing will be on different populations, adjustments for multiplicity do 
not need to be made.
10.3.
Sample Size Determination
If it is hypothesized that the event rate of efgartigimod PH20 SC to placebo is 0.50 (ie, hazard 
ratio of 0.50), then 88 events are required to provide 90% power at a 1-sided alpha level of 0.025 
using a log-rank test. An event is defined as an adjusted INCAT increase during Stage B (an 
increase [worsening] of 1 point will need to be confirmed at a consecutive visit 3-7 days after the 
first adjusted INCAT score increase of 1 point. For patients with an increase of 2 or more points 
on the adjusted INCAT score compared to Stage B baseline, no confirmation is required; see 
Section 2.2). The events will be monitored in a blinded way to ensure the trial is sufficiently 
powered. The table below shows the expected sample size for different scenarios for median 
time to event for the placebo arm, assuming a 48-week maximum follow-up period for each 
patient, an accrual rate of 4 patients per month during the first 6 months and an accrual rate of 
7.8 patients per month thereafter. To obtain a sufficient number of patients randomized into 
Stage B, up to approximately 360 patients would be required to be enrolled into Stage A. Patients 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
85
will continue to be randomized into Stage B until 88 events are observed as per the sample size 
calculation, the trial will end when the 88th event is observed. 
Median Time to Eventa for Placebo
Expected Sample Size for Stage B
1 month
96 patients
2 months
107 patients
3 months
119 patients
4 months
132 patients
5 months
146 patients
6 months
159 patients
7 months
173 patients
8 months
186 patients
a Event = increase in adjusted INCAT score relative to Stage B baseline in the adjusted INCAT score (see 
Section 2.2).
10.4.
Endpoints
The endpoints of the trial are separated into 2 periods according to the 2 defined trial stages.
10.4.1.
Stage A 
10.4.1.1.
Primary Endpoint:
Percentage of patients with confirmed ECI during Stage A 
10.4.1.2.
Secondary Endpoints for Evidence of Clinical Activity
Time to initial confirmed ECI during Stage A.
Change from Stage A baseline (D1A) over time during Stage A in:
Adjusted INCAT score 
MRC Sum score 
24-item I-RODS disability scores
TUG score
Mean grip strength assessed by Martin vigorimeter
10.4.1.3.
Secondary Endpoints for Safety
Exposure adjusted occurrence of TEAEs and SAEs by SOC and PT during Stage A 
Incidence of clinically significant laboratory abnormalities during Stage A 
10.4.1.4.
Secondary Endpoint for PK
Pre-dosing efgartigimod serum concentrations over time during Stage A 
10.4.1.5.
Secondary Endpoint for PD
Changes of serum IgG levels (total IgG) over time during Stage A 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
86
10.4.1.6.
Secondary Endpoint for Immunogenicity
Percentage of patients with and titers of binding antibodies (BAb) toward efgartigimod
and/or rHuPH20 during Stage A. Presence of neutralizing antibodies (NAb) against 
efgartigimod and titers of NAb against rHuPH20 during Stage A 
10.4.1.7.
Secondary Endpoint for PRO: 
Changes from D1A in EQ-5D-5L over time during Stage A 
10.4.2.
Stage B 
10.4.2.1.
Primary Endpoint
Time to first adjusted INCAT deterioration compared to Stage B baseline (defined by the 
time from first dose of double-blind IMP to the first adjusted INCAT deterioration 
compared to Stage B baseline; see Section 2.2)
10.4.2.2.
Secondary Endpoints for Efficacy
Time to CIDP disease progression (defined by the time from first dose of double-blind 
IMP to the first I-
 points compared to Stage B baseline using the 
centile metric)
Percentage of patients with improved functional level compared to Stage B baseline as 
measured by an increase in the 24-item I-RODS score up to week 48 
Change from Stage B baseline over time in:
Adjusted INCAT score
MRC Sum score 
24-item I-RODS disability scores
TUG score
Mean grip strength assessed by Martin vigorimeter 
Change from Stage A baseline over time for subjects randomized to efgartigimod PH20 SC 
in: 
Adjusted INCAT score 
MRC Sum score 
24-item I-RODS disability scores
TUG score
Mean grip strength assessed by Martin vigorimeter 
Time to 10% decrease in the 24-item I-RODS during Stage B 
10.4.2.3.
Secondary Endpoints for Safety
Incidence of TEAEs and SAEs by SOC and PT during Stage B 
Incidence of clinically significant laboratory abnormalities during Stage B 
10.4.2.4.
Secondary Endpoint for PK
Pre-dosing efgartigimod serum concentrations over time during Stage B 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
88
10.5.
Statistical Analyses
The SAP will be finalized before database lock and will include a more technical and detailed 
description of the statistical analyses described in this section. This section is a summary of the 
planned statistical analyses of the most important endpoints including primary and key secondary 
endpoints. 
For the Stage A interim analysis (see Section 10.6 for details), a separate stand-alone interim 
SAP will be written and signed-off prior to interim database lock. 
10.5.1.
Demographic and Baseline Characteristics
Patient demographic and baseline characteristics data, including prior and concomitant therapies, 
will be summarized using standard summary statistics (see Section 10.1.1).
10.5.2.
Patient Disposition
Patient disposition and withdrawals will be fully accounted for in a summary. The number of 
patients entering and leaving each phase of the trial will be clearly indicated and where relevant 
will be presented by treatment group. The major reason for discontinuation will also be given by 
stage and where relevant by treatment group. 
10.5.3.
Populations for Analyses and Protocol Deviations 
The number of patients for each population for analysis, as described in Section 10.1.3, will be 
presented in a table and listing. 
Major protocol deviations, by treatment group and trial stage, will be summarized in a table and 
presented in a listing. 
10.5.4.
Efficacy Endpoints
10.5.4.1.
Stage A: Confirmed ECI
For the interim analysis, the proportion of patients with confirmed ECI will be calculated with 
the exact Clopper-Pearson 90% 1-sided lower CI. For the final analysis, the proportion of
patients with confirmed ECI will be calculated using an exact Clopper-Pearson 2-sided 95% CI. 
10.5.4.2.
Stage A: Evidence of Clinical Activity Time 
A Kaplan-Meier table and graph will be presented for the clinical activity time to initial 
confirmed improvement. No formal statistical analysis will be present as Stage A only has 
1 treatment group. However, the Kaplan-Meier table and graph will present CIs.
10.5.4.3.
Stage B: Adjusted INCAT Score
The primary endpoint of time to clinical deterioration (defined as the time from first dose of 
double-blind trial medication to the first adjusted INCAT deterioration compared to Stage B
baseline; see Section 2.2) will be analyzed via Cox regression modeling in the mITT population. 
Patients without clinical deterioration will be censored at their last follow-up visit. The analysis 
will be stratified for randomization stratification factors (see Section 10.1.4). A fixed effect term 
will be included as a covariate for randomized treatment. The hazard ratio will be estimated from 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
89
the model along with the associated 95% CI and 2-sided p-value. The data will also be displayed 
using Kaplan-Meier curves and median times to clinical deterioration will be estimated.
As the endpoint is a time to event, missing data methods will not be used as all patients will have 
a last know visit (including at minimum randomization) at which they can be censored. 
The primary analysis will only consider deterioration through the adjusted INCAT score. 
Patients who withdraw will be censored at the time of withdrawal. The effect of withdrawals and 
other factors will be investigated as part of the sensitivity analysis which will be documented in 
the SAP.
10.5.4.4.
Stage B: I-RODS Score
The time to CIDP disease progression (defined by I-RODS deterioration) during Stage B up to 
week 48 will be analyzed using the same Cox’s model as for the adjusted INCAT score (see 
Section 10.5.4.3).
The percentage of patients with improved functional level (compared to Stage B baseline) as 
measured by the I-RODS score during Stage B up to week 48 will be analyzed by exact logistic 
regression. A fixed effect term will be included for randomized treatment and I-RODS score at 
end of Stage A will be included as a covariate. The odds ratio will be estimated from the model 
along with the associated 95% CI and 2-sided p-value. Exact Clopper-Pearson 2-sided 95% CI 
limits will be calculated for the proportion of patients with disease progression in each arm. 
10.5.5.
Stage A and Stage B: Other Efficacy and PK, PD, and Immunogenicity 
Endpoints
Descriptive statistics will be provided for efficacy endpoints other than described above (clinical 
functional assessments of motor function and muscle strength, and PROs) and for PK, PD, and 
immunogenicity data. 
10.5.6.
Stage A and Stage B: PRO EQ-5D-5L Endpoint
EQ-5D-5L scores and changes from baseline (ie, changes from D1A over time during Stage A
and changes from Stage B baseline over time during Stage B) will be presented using standard 
summary statistics.
10.5.7.
Stage A and Stage B: Safety Endpoints
Summaries AEs and other safety parameters will be provided for Stage A, Stage B (by treatment 
arm), and Stage A and B combined (for efgartigimod PH20 SC treatment). 
AEs will be classified using the latest version of the Medical Dictionary for Regulatory 
Activities (MedDRA) classification system. AEs reported from the first dose of trial drug until 
30 days after the last dose of trial drug will be considered as TEAEs and will be summarized 
descriptively. TEAEs (including AESIs) will be listed corresponding to system organ class and 
MedDRA preferred term. Patients with multiple occurrences of events will only be counted once 
at the maximum severity/grade to trial drug for each PT, SOC. The severity will be assessed 
using the common terminology criteria for AEs (CTCAE) (see Section 11.4). Any AEs with 
missing severity or relationship to trial drug will be classified as severe and treatment-related, 
respectively. All AEs will be summarized by relatedness to trial medication. Any AEs leading to 
death or discontinuation of trial medication will also be summarized.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
91
11.
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS
11.1.
Appendix 1: Regulatory, Ethical, and Trial Oversight Considerations
11.1.1.
Regulatory and Ethical Considerations 
This trial will be conducted and the informed consent will be obtained according to the ethical 
principles stated in the current Declaration of Helsinki, the applicable guidelines for good 
clinical practice (GCP), or the applicable drug and data protection laws and regulations of the 
countries where the trial will be conducted. 
The protocol, protocol amendments, ICF, IB, and other relevant documents (eg, advertisements) 
must be submitted to an IRB/IEC by the investigator and reviewed and approved by the IRB/IEC 
before the trial is initiated.
Any amendments to the protocol will require IRB/IEC approval before implementation of 
changes made to the trial design, except for changes necessary to eliminate an immediate hazard 
to trial patients.
The investigator will be responsible for the following: 
Providing written summaries of the status of the trial to the IRB/IEC annually or more 
frequently in accordance with the requirements, policies, and procedures established by 
the IRB/IEC
Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures 
Providing oversight of the conduct of the trial at the site and adherence to requirements of 
Title 21 of the Code of Federal Regulations (21 CFR), ICH guidelines, the IRB/IEC, 
European regulation 536/2014 for clinical trials (if applicable), and all other applicable 
local regulations 
11.1.2.
Financial Disclosure
Investigators and sub-investigators will provide the sponsor with sufficient, accurate financial 
information as requested to allow the sponsor to submit complete and accurate financial 
certification or disclosure statements to the appropriate regulatory authorities. Investigators are 
responsible for providing information on financial interests during the course of the trial and for 
1 year after completion of the trial.
11.1.3.
Informed Consent Process
The investigator or his/her representative will explain the nature of the trial to the patient and 
answer all questions regarding the trial. 
Patients must be informed that their participation is voluntary. Patients will be required to sign a 
statement of informed consent that meets the requirements of 21 CFR 50, local regulations, ICH 
guidelines, Health Insurance Portability and Accountability Act (HIPAA) requirements, where 
applicable, and the IRB/IEC or trial center.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
92
The medical record must include a statement that written informed consent was obtained before 
any screening assessment was performed and the date the written consent was obtained. The 
authorized person obtaining the informed consent must also sign the ICF. 
Patients must be re-consented to the most current approved version of the ICF(s) during their 
participation in the trial.
A copy of the ICF(s) must be provided to the patient. 
A patient can be re-screened only if the patient has not started treatment in Stage A and with the 
sponsor’s written approval. 
11.1.4.
Data Protection 
Patients will be assigned a unique identifier by the sponsor. Any patient records or datasets that 
are transferred to the sponsor will contain this identifier; patient names or any information that 
would make the patient identifiable will not be transferred. 
The patient must be informed that his/her personal trial-related data will be used by the sponsor 
in accordance with local data protection law. The level of disclosure must also be explained to 
the patient who will be required to give consent for their data to be used as described in the 
informed consent. 
The patient must be informed that his/her medical records may be examined by clinical quality 
assurance auditors or other authorized personnel appointed by the sponsor, by appropriate 
IRB/IEC members, and by inspectors from regulatory authorities. 
11.1.5.
Independent Data and Safety Monitoring Board (DSMB)
An independent DSMB will be used in this trial. 
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). For Stage B, the DSMB will 
also 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 achievement 
of 25%, 50% and 75% recruitment targets 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 DSMB will be described in a 
charter. The DSMB charter will also define and document the content of the safety summaries, 
and general procedures (including communications). 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
93
11.1.6.
CIDP Confirmation Committee (CCC)
Misdiagnosis of CIDP has been reported to occur frequently among less experienced physicians. 
Therefore, in this trial the investigator’s diagnosis of CIDP will be reviewed by an independent 
committee (ie, CCC) during the screening period. Patients for whom the diagnosis cannot be 
confirmed, will not be eligible to enter the trial.
The CCC will be composed of neurologists with at least 10 years of experience in the diagnosis 
of CIDP and a documented track record of at least 100 diagnosis of CIDP. 
The CCC is responsible to ensure, that the CIDP trial population included in this trial is fulfilling 
the official EFNS/PNS 2010 diagnostic criteria.2
These are used to define probable or definitive progressing or relapsing forms of CIDP in which 
both sensory symptoms and limited motor functions, or limited motor functions only have to be 
present to qualify the patient to the trial.
A patient profile will be presented for CCC member review.
In case the information provided to the CCC is not sufficient to confirm a definite or probable 
CIDP diagnosis per the EFNS/PNS 2010 criteria,2 additional assessments may be asked for (as 
listed in Section 11.5 Appendix 5) to support the confirmation of diagnosis. 
A specific CCC Charter will describe the review process, which will be properly documented. 
Each site will be instructed about the procedure of the review process.
11.1.7.
Dissemination of Clinical Trial Data
All information regarding efgartigimod PH20 SC 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, presentation of results, or information arising in 
connection with the trial must be prepared in conjunction with the sponsor and must be 
submitted to the sponsor for review and comment prior to submission for publication or 
presentation. Trial patient identifiers will not be used in the publication of results.
Authorship will be granted according to the International Committee of Medical Journal Editors 
criteria, based on scientific input and 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. 
11.1.8.
Data Quality Assurance 
All patient data relating to the trial will be recorded on the eCRF unless transmitted to the 
sponsor or designee electronically (eg, laboratory data). The investigator is responsible for 
verifying that data entries are accurate and correct by electronically signing the CRF. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
94
The investigator must maintain accurate documentation (source data) that supports the 
information entered in the CRF. 
The investigator must permit trial-related monitoring, audits, IRB/IEC review, and regulatory 
agency inspections and provide direct access to source data documents. 
Monitoring details describing strategy (eg, risk-based initiatives in operations and quality such as 
Risk Management and Mitigation Strategies and Analytical Risk-Based Monitoring), methods, 
responsibilities and requirements, including handling of non-compliance issues and monitoring 
techniques (central, remote, or on-site monitoring) are provided in the Clinical Monitoring Plan. 
The sponsor or designee is responsible for the data management of this trial including quality 
checking of the data.
The sponsor assumes accountability for actions delegated to other individuals (eg, CROs).
Trial monitors will perform ongoing source data verification to confirm that data entered into the 
CRF by authorized site personnel are accurate, complete, and verifiable from source documents; 
that the safety and rights of patients are being protected; and that the trial is being conducted in 
accordance with the currently approved protocol and any other trial agreements, ICH GCP, and 
all applicable regulatory requirements.
Records and documents, including signed ICFs, pertaining to the conduct of this trial must be 
retained by the investigator for 25 years after trial completion unless local regulations or 
institutional policies require a longer retention period. No records may be destroyed during the 
retention period without the written approval of the sponsor. No records may be transferred to 
another location or party without written notification to the sponsor. 
11.1.9.
Source Documents
Source documents provide evidence for the existence of the patient and substantiate the integrity 
of the data collected. Source documents will be filed at the investigator’s site. These data are
usually later entered in the eCRF.
Data reported on the CRF or entered in the eCRF that are transcribed from source documents 
must be consistent with the source documents or the discrepancies must be explained. The 
investigator may need to request previous medical records or transfer records, depending on the 
trial. Also, current medical records must be available.
The Investigator Source Data Agreement Form describes the source data for the different data in 
the eCRF. This document should be completed and signed by the 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 Investigator Source Data Agreement Form.
11.1.10.
Trial and Site Start and Closure
The trial start date is the date on which the first patient signs the ICF in this trial.
The sponsor designee reserves the right to close the trial site or terminate the trial at any time for 
any reason at the sole discretion of the sponsor. Trial sites will be closed upon trial completion. 
A trial site is considered closed when all required documents and trial supplies have been 
collected and a trial-site closure visit has been performed.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
95
The investigator may initiate trial-site closure at any time, provided there is reasonable cause and 
sufficient notice is given in advance of the intended termination. 
Reasons for the early closure of a trial site by the sponsor or investigator may include but are not 
limited to: 
Failure of the investigator to comply with the protocol, the requirements of the IRB/IEC or 
local health authorities, the sponsor's procedures, or GCP guidelines; 
Inadequate recruitment of patients by the investigator; 
Discontinuation of further IMP development. 
If the trial is prematurely terminated or suspended, the sponsor shall promptly inform the 
investigators, the IECs/IRBs, the regulatory authorities, and any CRO(s) used in the trial of the 
reason for termination or suspension, as specified by the applicable regulatory requirements. The 
investigator shall promptly inform the patient and should assure appropriate patient therapy 
and/or follow-up. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
96
11.2.
Appendix 2: Clinical Laboratory Tests
Safety Laboratory Testing 
Hematology 
Red blood cell count
Hemoglobin
Hematocrit
Mean cell volume
Mean cell hemoglobin
Mean cell hemoglobin concentration
Red cell distribution width
Platelets
White blood cell count
Lymphocytes count
Monocytes
Eosinophils
Basophils
Neutrophils count
Coagulation 
International normalized ratio
Activated partial thromboplastin 
time
Prothrombin time
Blood Chemistry Tests
Glucose
Creatinine
Total protein§
Albumin§
Bilirubin
Alkaline phosphatase
Aspartate transferase
Alanine transferase
Gamma glutamyl transferase
Cholesterol*
High-density lipoprotein 
cholesterol*
Low-density lipoprotein cholesterol 
(LDL)*
Total cholesterol/HDL ratio*
Triglycerides*
Estimated glomerular filtration rate#
high-sensitive C reactive protein
Blood urea nitrogen
Hemoglobin A1c
Lactate dehydrogenase
Uric acid
Potassium
Sodium
Calcium
Serum pregnancy test*
Total immunoglobulin G (IgG)*
* At screening visit only
§ In the exceptional circumstances that using a central laboratory is not possible: Do not measure total protein and albumin 
after the Stage B baseline visit.
# Chronic Kidney Disease – Improved Prediction Equations (CKD-EPI) will be used for estimating glomerular filtration rate; 
it will be reported as creatinine clearance. 
Blood Screening for Infections
HIV§ (Ag/Ab test)
Viral Hepatitis (HBsAg, anti-HBc 
Ab, Anti-HBs, Anti-HCV Ab [HCV 
RNA if reactive])
Tuberculosis (Quantiferon)
Abbreviations: Ab=antibody; Ag=antigen; HBc=hepatitis B core; HBs=hepatitis B surface; HBsAg=hepatitis B surface 
antigen; HCV=hepatitis C virus; HIV=human immunodeficiency virus.
§ CD4 count to be analyzed in case of positive HIV (see exclusion criterion #7)

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
98
11.3.
Appendix 3: Contraceptive and Barrier Guidance
11.3.1.
General Instructions and Definitions
Contraceptive use by men and women should be consistent with local regulations regarding the 
methods of contraception. 
Women of childbearing potential must have a negative serum pregnancy test at the screening 
visit and a negative urine pregnancy test at baseline before IMP can be administered.
A woman is considered of childbearing potential unless she is either: 
Postmenopausal, defined by continuous amenorrhea for at least 1 year without an 
alternative medical cause with a follicle stimulating hormone (FSH) measurement of 
>40 IU/L. A historical pretreatment FSH measurement of >40 IU/L is accepted as proof 
of a postmenopausal state for women on hormone replacement therapy.  
Surgically sterilized: Women who have had a documented permanent sterilization 
procedure (ie, hysterectomy, bilateral salpingectomy, or bilateral oophorectomy). 
11.3.2.
Female Contraception for Women of Childbearing Potential 
Women of childbearing potential should use an acceptable method of contraception during the 
trial. 
The following methods of contraception, described in the Recommendations Related to 
Contraception and Pregnancy Testing in Clinical Trials,34 are allowed in this trial:
Combined (estrogen- and progestogen-containing) hormonal contraception associated 
with inhibition of ovulation: 
Oral
Intravaginal 
Transdermal
Progestogen-only hormonal contraception associated with inhibition of ovulation: 
Oral
Injectable
Implantable 
Progestogen-only oral hormonal contraception, where inhibition of ovulation is not the 
primary mode of action 
Intrauterine device (IUD)
Intrauterine hormone-releasing system (IUS)
Bilateral tubal occlusion 
Vasectomized partner
Sexual abstinence
Male or female condom with or without spermicide 
Cap, diaphragm, or sponge with spermicide 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
99
11.3.3.
Male Contraception
An acceptable method of contraception is a condom. 
1

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
106
11.5.
Appendix 5: CIDP Diagnostic Tests
In the event that the CCC cannot confirm the CIDP diagnosis based on the data presented by the 
investigator, they can suggest additional evaluations according to the following table. Based on 
the table below, any finding suggestive of any concomitant disease should be investigated 
according to the investigator’s clinical practice.
Investigations to be Considered to Confirm CIDP Diagnosis (Taken From EFNS/PNS 2010 Guideline,2
Table 2, Illustrating the Good Practice Points):
To diagnose chronic inflammatory demyelinating polyradiculoneuropathy
Electrodiagnostic studies including sensory and motor nerve conduction studies, which may be repeated, 
performed bilaterally, or use proximal stimulation for motor nerves
CSF examination including cells and protein
MRI spinal roots, brachial plexus, and lumbosacral plexus
Nerve biopsy
To detect concomitant diseases
(a) Recommended studies
aSerum and urine paraprotein detection by immunofixationb
Fasting blood glucose
Complete blood count
Renal function
Liver function
Antinuclear factor
Thyroid function
(b) Studies to be performed if clinically indicated
aSkeletal survey
Oral glucose tolerance test
Borrelia burgdorferi serology
C reactive protein
Extractable nuclear antigen antibodies
Chest radiograph
Angiotensin-converting enzyme
HIV antibody
To detect hereditary neuropathy
Examination of parents and siblings
Appropriate gene testing (especially PMP22 duplication and connexin 32 mutations)
Nerve biopsy
a Repeating these should be considered in patients who are or become unresponsive to treatment. 
b Immunofixation is not available in some participating countries of this study. In that case, serum protein 
electrophoresis can be used as the first screen. Any abnormalities detected in the immunoglobulin band will be 
further investigated using a local/internationally acceptable method.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
107
11.6.
Appendix 6: CIDP Disease Activity Status (CDAS)
The following CDAS classification is based upon the clinical assessment of the treating 
physician (taking into account the duration of the disease, clinical response, neurological 
examination status, and duration of treatment) (from Gorson et al, 20193):

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
108
11.7.
Appendix 7: Inflammatory Neuropathy Cause and Treatment 
(INCAT) Disability Scale
Arm disability (05)
1 or both arms, not affecting the ability to perform any of the 
following functions: Doing all zips and buttons; washing or brushing hair; using a 
knife and fork together; handling small coins
1 arm or both arms, affecting but not preventing any of the above-
mentioned functions
1 arm or both arms, preventing 1 or 2 of the above-mentioned 
functions
1 arm or both arms, preventing 3 or all of the functions listed, but 
some purposeful movements still possible
Leg disability (05)
1 arm) to walk outdoors
2 arms) to walk outdoors
with help
Overall disability = Arm disability + Leg disability
The INCAT score is a 10-point scale that covers the functionality of legs and arms. Scores for 
arm disability range from 0 to 5, and scores for leg disability also range from 0 to 5. 
The INCAT (total) score is the sum of these 2 scores and ranges from 0 to 10. 
For the “adjusted” INCAT score, changes in the function of the upper limbs from 0 (normal) to 1 
(minor symptoms) or from 1 to 0 will not be recorded as deterioration or improvement, because 
these changes are not considered clinically significant.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
109
11.8.
Appendix 8: Medical Research Council Scale
MRC Scale35
0
Complete paralysis
1
Minimal contraction
2
Active movement with gravity eliminated
3
Weak contraction against gravity
4
Active movement against gravity and resistance
5
Normal strength
The scale is bilaterally applied to 6 muscle groups of the upper and lower limbs in order to obtain a 
summed score ranging from 0 to 60 for the MRC scale: 1) arm abductors; 2) elbow flexors; 3) wrist 
extensors; 4) hip flexors; 5) knee extensors; and 6) foot dorsiflexors. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
110
11.9.
Appendix 9: Inflammatory Rasch-built Overall Disability Scale (I-
RODS)

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
111

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
112
11.10.
Appendix 10: 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
115
11.12.
Appendix 12: Possible Adaptations of Trial Protocol During COVID-
19 Pandemic
Introduction
The aim of the ARGX-113-1802 trial is to investigate a new subcutaneous (SC) treatment option 
for patients with chronic inflammatory demyelinating polyneuropathy (CIDP). This SC treatment 
consists of efgartigimod with recombinant human hyaluronidase PH20 (rHuPH20) (called 
efgartigimod PH20 SC) and could offer clinically significant benefits to CIDP patients. 
argenx has performed a critical assessment of the use of efgartigimod during the COVID-19 
pandemic. Following careful evaluation, the risk/benefit profile of efgartigimod use in clinical 
trials has not changed in the context of this pandemic. This decision was made based on 
efgartigimod’s mechanism of action, the safety data generated to date, and provisions made in 
the clinical trials with efgartigimod for safety reporting and withholding treatment upon evidence 
of infection. This assessment will be reviewed regularly to consider new information about the 
pandemic and the ongoing, continuous assessment of adverse events reported during argenx 
clinical trials.
Based on this risk-benefit assessment, the clinical trial ARGX-113-1802 can be conducted, 
however, because of the pandemic argenx acknowledges that considerable difficulties for 
participating centers to meet all previously planned assessments might occur (see SoA in 
Section 1.3). Therefore, an Appendix with possible adaptations to this trial has been developed 
so that sites can follow this Appendix in case a patient cannot have the visit at the trial site (see 
below) and a visit at home or an alternative convenient location will be performed. This 
Appendix describes a minimum number of assessments required to guarantee the safety and 
well-being of the patients during the trial and to secure the collection of the critical parameters 
for analysis. It remains at the investigator’s discretion to assess if it is in the best interest of the 
patient to participate/continue in the trial.
Note that a “home visit” as described in this Appendix could also be a visit at an alternative 
convenient location. 
Note that the home nurse, who will go to the patient in case of a home visit, could also be 
another qualified person to perform all tasks (eg, a physician). In addition, a home nurse can be 
qualified personnel from an alternative convenient location if the trial visit cannot be performed 
at the trial site.
POSSIBLE ADAPTATIONS TO ARGX-113-1802 TRIAL PROTOCOL DURING 
COVID-19 PANDEMIC
Implementation of This Appendix
Implementation for all sites includes social distancing, personal protective equipment 
(PPE), and a telephone call before each trial visit for checking of COVID-19 
symptoms. 
The adaptations to the visits and procedures described in this Appendix that are 
acceptable alternatives to the main protocol procedures should only be implemented 
in exceptional cases and after approval of the sponsor and/or CRO. Approval will be 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
116
granted based on the possibility of the patient to go to the site and per local and/or 
hospital regulations. 
The Appendix is intended for countries and/or sites in geographical areas where COVID-19 has 
affected trial sites’ workload, severe movement restrictions have been imposed, or when there is 
a risk to patients/trial staff if attending trial sites for trial visits. The initial duration of the 
implementation of this Appendix will be agreed and can be extended based on the local epidemic 
status.
When a (home) visit is performed under this COVID-19 Appendix, it should be documented as a 
COVID-19 (home) visit in the eCRF for the applicable visit. 
Testing for COVID-19 
Additional testing for COVID-19 beyond that mandated by relevant local authorities is not 
required at the start of the study. However, argenx recommends patients who develop symptoms 
of COVID-19 during the trial to be tested. 
Protecting Home Nurse and Site Staff From COVID-19 
The home nurse and site staff as well as qualified personnel from an alternative convenient 
location. Staff should apply appropriate social distancing and use personal protection equipment 
according to the local hospital and governmental regulations/recommendations; see also below. 
Patients With COVID-19 (Either a Positive Test or With Symptoms [Suspicion of 
COVID-19 Infection])
Patients with a COVID-19 infection should not enter the trial. In case a patient develops a 
COVID-19 infection when he/she is in the trial, the following applies. 
The instructions to manage an infection that are in the main protocol are also applicable in case 
of an infection with COVID-19 (ie, it will be considered an AESI similar to all infections). 
Treatment should be interrupted until the patient is considered recovered from COVID-19 
(according to the local recommendations). 
During the pandemic, the trial site staff should contact patients prior to each visit to enquire 
about COVID-19 symptoms and exposure using the flow charts below and make a decision on 
proceeding or postponing the visit according to the following flow charts. 
The following symptoms should be specifically addressed during that phone call: Fever, cough, 
sneezing, loss of taste/smell, difficulties breathing/chest tightness.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
117

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
118
Patient with symptoms of COVID-19 infection will be treated for this infection as guided by the 
local health care system. Patients will be monitored by the trial site by telephone contact. In case 
the patient will have to be in self-isolation for a longer period than 2 weeks, it will be discussed 
on a case by case basis with the sponsor and/or with the CRO whether the patient can remain in 
the trial.
Once a patient has recovered, the patient can continue the trial and receive trial medication, 
provided that he/she has not received/is not receiving prohibited medication (see Section 7.4.2).
Critical Parameters to be Collected During the Trial
Please note that, if feasible, all assessments, including those that are not critical (ie, indicated as 
assessments that are not mandatory in the SoA in Section 11.12.1) should be performed. 
The critical parameters which are mandatory to be collected during the trial, are summarized 
below: 
During the COVID-19 pandemic, the collection of these critical parameters is specified in the 
SoA for both stages of the trial in Section 11.12.1 (indicated in red solid dots).
The evaluation of eligibility for the trial will be as described in the main protocol. The 
screening visit must be performed at the trial site (see below).
For the evaluation of efficacy, safety, and for the IMP administration and accountability, 
certain modifications compared to the main protocol are allowed in this protocol compared 
to the main protocol (see below). 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
119
Mandatory Site Visits and Allowed Home Visits
In order to collect the critical parameters of the trial, certain visits have to be performed at the 
site and other visits can be at home:
Screening Visit
The screening visit of the trial needs to be performed at the trial site. If it is not possible to go 
to the trial site due to the COVID-19 situation, the screening visit is to be postponed and has to 
wait until the situation changes and the patient is able to go to the trial site. Note that 
transportation to the trial site can be facilitated if the situation due to the COVID-19 pandemic 
allows this.
Baseline Visits of Stage A and Stage B 
The baseline visit of Stage A (D1A) and the baseline visit of Stage B (D1B) have to be 
performed at the trial site. If it is not possible to go to the trial site for these baseline visits due 
to the COVID-19 situation, the sponsor or CRO have to be contacted as soon as possible to 
discuss viable options. 
Other Trial Visits
All trial visits, other than the screening visit and the baseline visits of Stage A and Stage B that 
are originally planned to be site visits can be performed at home (or at an alternative 
convenient location) during the COVID-19 pandemic. A home nurse will travel to the patient’s 
home to conduct this visit (or the patient will go to an alternative convenient location). The 
treating physician will talk to the patient via an audio or video interview to elicit AE, 
concomitant medications, and general well-being of the patient. The evaluating physician will 
perform efficacy assessments using a video interview (or via a telephone only if a video 
interview is not possible) with the patient. The assessments via an audio or video interview will 
be conducted before the home nurse administers the trial medication. The division of tasks 
between the treating physician, evaluating physician, and home nurse are indicated in the 
following scheme. 
Stage B visits that were originally planned as home visits for IMP administration, remain as 
described in the main protocol. 
Note that a “home visit” as described in this Appendix could also be a visit at an alternative convenient location.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
120
Scheme for Home Visitsa
Critical Assessments
Performed by
Method of Assessment
ICF Addendum (not initial ICF at screening, explained to 
patient)
Treating Physician
Audio or video interview
Adverse events
Concomitant medication
Confirmation that IMP can be administered
Adjusted INCAT
Evaluating 
Physician
Video interview (or via 
telephone if video interview 
is not possible)
Grip strength
Bring device for efficacy assessments; including I-RODS 
and the patients reported outcomes questionnaire PHQ-9
Home nurse
In person at patient’s homea
Vital signs
Blood draw
IMP administration
a.
Note that a “home visit” could also be a visit at an alternative convenient location.
Efficacy Assessments
The 3 critical efficacy assessments of the trial are:
-
Adjusted INCAT
-
I-RODS
-
grip strength 
During home visits, 2 similar devices will be used to capture these assessments. One device will 
remain at the site with the evaluating physician and the other device will be taken by the home 
nurse to the patient. The evaluating physician will perform the adjusted INCAT and grip strength 
assessments via video link between the 2 devices (or via a telephone only if a video interview is 
not possible). The home nurse will thereafter provide the other device to the patient to perform 
the I-RODS assessment.
MRC Sum Score and TUG are considered non-critical variables and will not be measured at 
home visits.
Patient-Reported Outcomes (PROs)
During a home visit, patient-reported outcomes (PROs) will be performed by the patient on 
the device provided by the home nurse. 
The PHQ-9 depression questionnaire (suicidality question) needs to be done at all scheduled 
visits, also if this visit is performed at the patient’s home (or at an alternative convenient 
location). 
Other PROs are not considered as critical data and be performed only if feasible during a 
home visit (or during a visit at an alternative convenient location). 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
121
Safety Assessments
Adverse event
During home visits, a telephone/video interview will be conducted by the treating physician or 
designee about possible AEs. Any suspected COVID-19 infection relevant signs or symptoms 
(including an abnormal laboratory findings) will be reported as an AE, with clear distinction 
whether it is a confirmed test positive COVID-19 infection or suspected infection if not tested. 
Vital signs
During home visits, vital signs (heart rate, body temperature, and blood pressure) will be 
measured by the home nurse at the beginning of the home visit and the results will be 
communicated to the treating physician. If pyrexia is detected, the home nurse should call the 
trial site immediately and await further instructions from the treating physician.
Safety laboratory testing 
During home visits, the home nurse will take blood samples for safety laboratory testing 
immediately before IMP administration. Ideally, tubes from the central laboratory will be used. 
However, if needed, local laboratory tubes and venipuncture equipment can be used after prior 
agreement with the central laboratory.
During home visits, urine samples will be taken for safety laboratory testing and for pregnancy 
testing (if applicable).
In case transfer of laboratory samples to the central laboratory is not available or may be 
prolonged, a local laboratory can be used. A certification of the local laboratory is required. 
Laboratory reports should be sent to and reviewed by the investigator and any abnormalities will 
be evaluated for clinical significance and any significant laboratory findings should be recorded 
as AEs. The laboratory report should be kept as a source document. 
Electrocardiogram (ECG)
At screening, Stage A visit 1 and Stage B visit 1 (which are performed at the site), ECGs are 
required. A local ECG machine from the site can be used in case equipment from the central 
ECG laboratory does not arrive at the site. A test transfer to the central ECG laboratory 
(eResearch Technology [ERT]) with an anonymized test ECG is required. Requirement for the 
test ECG and test transfer are described in the user guide (“site upload tool quick guide”) from 
ERT. Except for screening, an ECG is not considered as critical data at other visits and will not 
be done in case of a home visit. 
Blood Sampling for Tests Other Than Safety Laboratory Testing 
During home visits, the home nurse will draw the blood samples for laboratory parameter 
evaluation. Blood sampling will be performed immediately before IMP administration. 
Concomitant Medication 
At the time of the home visit, the site treating physician will telephone/video interview the 
patient about concomitant medications. It will be documented whether concomitant medication is 
taken for a confirmed test positive COVID-19 infection or suspected infection (if not tested). 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
122
IMP Administration
IMP can be administered at home by a qualified person (eg, home nurse) after confirmation of 
the treating physician. 
Trial Endpoint
The criteria for the trial endpoint for a patient in Stage A or Stage B as described in the main 
protocol, also apply to this Appendix. 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
123
11.12.1.
Schedule of Activities (SoA) During COVID-19 Pandemic 
In the SoA for Stage A and Stage B of the ARGX-113-1802 trial (see below), the mandatory assessments are indicated in red solid 
dots. The assessments that need to be performed only if feasible during the COVID-19 pandemic are indicated in black open circles. 
At site visits, all assessments have to be performed (critical [red solid dots] and non-critical [black open circles]). At home visits (or a 
visit at an alternative convenient location): assessments can be limited to the mandatory assessments (critical [red solid dots]).
SoA for Screening, Run-in, and Stage A During COVID-19 Pandemic 
Screeninga
Run-in 
Period 
weeksb
Stage A: Open-label Period 
Weeks (With Optional 1 Additional Week)c
Unsche-
dulede
Safety 
Follow-
upf
RI-V1 RI-V2 
to 
RI-V4
A-V1A-V2 A-V3 A-V4 A-V5 A-V6c A-V7cA-V8c A-V9c A-V10c A-V11cA-V12cA-V13c
(Addi-
tional)
EOSA/
EDd
UnschV 28 (±3)
Days 
After 
Last IMP 
Dose
Up to 
28 days
D1A
D8
D15
D22
D29
D36c D43c D50c
D57c
D64c
D71c
D78c
D85
Assessment/Procedure
±0 
days
±2 
days
±0 
days
±2 days
Informed consent
Demographics
In-/exclusion criteria
o
Medical historyg
12-lead ECGs
o
o
o
CDAS
Physical exams
h
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
Vital signsi
o
Pregnancy test
j
k
k
k
k
k
k
ok
k
Adjusted INCAT score
(
)l
(
)l
(
)l
(
)l
o
MRC sum score
o
o
o
o
o
o
(o)l
o
(o)l
o
(o)l
o
(o)l
o
o
o
I-RODS score
o

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
125
Screeninga
Run-in 
Period 
weeksb
Stage A: Open-label Period 
Weeks (With Optional 1 Additional Week)c
Unsche-
dulede
Safety 
Follow-
upf
RI-V1 RI-V2 
to 
RI-V4
A-V1A-V2 A-V3 A-V4 A-V5 A-V6c A-V7cA-V8c A-V9c A-V10c A-V11cA-V12cA-V13c
(Addi-
tional)
EOSA/
EDd
UnschV 28 (±3)
Days 
After 
Last IMP 
Dose
Up to 
28 days
D1A
D8
D15
D22
D29
D36c D43c D50c
D57c
D64c
D71c
D78c
D85
Assessment/Procedure
±0 
days
±2 
days
±0 
days
±2 days
IMP self-administration 
trainingt
ot
ot
ot
ot
ot
ot
ot
ot
ot
ot
ot
ot
IMP administration (SC)u
u
u
u
u
u
u
u
u
u
u
IMP accountabilityv
Adverse eventsw
‹-------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------›
Concomitant therapiesg,w
‹-------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------›
Footnotes are on next page

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
127
n. At screening, suicidality will be assessed with the Columbia-suicide severity rating scale (C-SSRS) (see Section 9.2). During the trial, suicidality will be assessed by specifically 
answering 1 question from the PHQ-9 depression questionnaire (see Section 9.15). 
o. At screening, total IgG will be measured (by central laboratory as part of the blood chemistry tests) to determine eligibility.
p. Serology can be retested only during the screening period.
q. For PK, pre-dose (within 2 hours prior to start of IMP administration at the trial visits) samples will be taken. At these time points, blood samples will also be taken for PD analysis. PD 
analysis includes the measurement of total IgG. IgG testing must not be performed locally.
r. Blood samples for immunogenicity testing will be taken pre-dose at the trial visits to measure ADA against efgartigimod (measured in serum) and antibodies against rHuPH20 (measured
in plasma).
s. Optional blood samples will be taken for autoantibodies testing (serum) and serum-sample storage for future testing.
t. Patients will be trained to self-administer IMP at the site (foreseen in the OLE trial; not in the ARGX-113-1802 trial) during the first 4 visits when IMP is administered; thereafter, 
training for self-administration is optional (only if needed).
u. IMP will be administered weekly at the site/home in Stage A (IMP administration will be after blood samples have been taken for laboratory safety, PK, PD, immunogenicity, and/or 
biomarker analyses and after all assessments needed for determination of ECI). The first IMP administration in Stage A can be within 24 hours after observing ECMD during the run-in 
period. Patients will receive a minimum of 4 IMP administrations in Stage A. Note that IMP in Stage A will not be administered if ECI is confirmed at the visit (and the patient has 
received at least 4 IMP administrations). When ECI is confirmed (ie, ECI observed at the second consecutive visit), the patient will be randomized and receive the first double-blind 
IMP administration in Stage B (ie, the visit at which ECI is confirmed will be a combination of the EOSA visit and the Stage B baseline [D1B] visit).
v. IMP kits will be returned to the site where IMP accountability will be performed when the kits are available, preferably every 4 weeks.
w.AEs and intake of concomitant medication(s) will be monitored continuously from signing the ICF until the last trial-related activity. In case of early discontinuation, any AEs/SAEs 
should be assessed for 30 days following the ED visit or until satisfactory resolution or stabilization.
x. Blood samples may also be used to cross-validate the PK, PD, biomarker, and ADA assays in CIDP matrix (serum and plasma).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
128
SoA for Stage B and Follow-up During COVID-19 Pandemic 
Stage B: Randomized-withdrawal Treatment 
weeks
Un-
scheduled
Safety 
Follow-upd
B-V1
B-V2
B-V3
B-V4
B-V5
B-V6
B-V7
B-V8
B-V9
B-V10
B-V11
B-V12
B-V13
UnschVc 28 (±3) days 
after last 
IMP dose
D1Ba
W4
W8
W12
W16
W20
W24
W28
W32
W36
W40
W44
W48/EDb
Assessment/Procedure
±0 
days
±2 days
Randomization
12-lead ECGs
o
o
o
o
o
o
Physical exame
o
o
o
o
o
o
o
o
o
o
o
o
o
o
Vital signsf
Pregnancy testg
Adjusted INCAT score
MRC Sum score
o
o
o
o
o
o
o
o
o
o
o
o
o
I-RODS score
Mean grip strength
TUG test
o
o
o
o
o
o
o
o
o
o
o
o
o
EQ-5D-5L
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
Suicidality assessment
Blood & urine safety tests
o
Blood sampling for PK and 
PD analysish
o
o
o
o
o
o
o
o
o
o
o
o
o
o

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
131
11.13.
Appendix 13: Protocol Amendment History
General Amendment 3, General Protocol Version 4.0:
The major changes from Protocol Version 3.0 compared to Protocol Version 4.0 are summarized 
in the table below. Deleted text is indicated in strikethrough; a bold and underlined font is used 
to indicate added text. Minor administrative editorial changes (eg, to improve readability or 
correct spelling mistakes) are not summarized in the following table: 
Summary of Changes Between Protocol Version 3.0 and Protocol Version 4.0 
Section(s)
Change 
Rationale
Front page
Serious Adverse Events Reporting:
Parexel International  
8 Federal Street, Billerica, MA 01821, United States of 
America SGS Belgium NV, Life Sciences Division,
Noorderlaan 87, 2080 Antwerp, Belgium
For drug safety reporting, contact the following email 
address: Safety Mailbox/Fax:
Email: 248700ADR@parexel.com be.life.saefax ma@sgs.com
Fax: +1 833 644-0806 +32 (0)15 29 93 94
Updated contact information 
for SAE reporting.
Synopsis, 
Section 6.1
Inclusion criterion:
5.
, with a score of 2 exclusively from 
leg disability, at the first run-in visit (RI-V1; for patients 
entering run-in) or Stage A baseline (A-V1; for 
treatment-naïve patients with documented evidence for 
worsening on the total adjusted INCAT disability score 
within 3 months prior to screening). Patients with an 
INCAT score of 2 at trial entry must have this score 
exclusively from the leg disability score; for patients 
no specific requirements for arm or leg scores.
Clarification of inclusion 
criterion based on an INCAT 
score of 2 or higher.
Synopsis, 
Section 6.1
Inclusion criterion:
6. Fulfilling any of the following treatment conditions:
Currently (ie, within the last 6 months) treated with 
pulsed corticosteroids, oral corticosteroids equivalent 
mg/day, and/or IVIg 
or SCIg, if this treatment has been started within the 
last 5 years before screening, and the patient is willing 
to discontinue this treatment at the first run-in visit 
(RI-V1); OR …
Clarification of what we mean 
with currently treated and 
adapted further, because 
patients treated with IVIg or 
SCIg for more than 5 years 
before screening could also 
benefit from treatment with 
efgartigimod PH20 SC.
Synopsis, 
Section 6.1, 
Section 11.3
Inclusion criteria:
8. Women of childbearing potential must use a highly 
effective or acceptable method of contraception 
(failure rate of less than 1% per year) from screening to 
90 days after the last administration of IMP
9a. Male patients agree not to donate sperm during the 
trial period and 90 days thereafter. Non-sterilized 
male patients who are sexually active with a female 
partner of childbearing potential must use a condom and 
his partner must use a highly effective method of 
contraception (failure rate of less than 1% per year) 
from screening to 90 days after the last administration 
Reproductive toxicity studies 
with efgartigimod IV have 
been completed in rats and 
rabbits. Efgartigimod did not 
show a teratogenic effect (rats 
and rabbits), nor did it 
adversely affect male and 
female fertility or any other 
reproductive and 
developmental performance 
(rats). Therefore, acceptable 
methods of contraception can 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
132
Section(s)
Change 
Rationale
of IMP. Male patients practicing true sexual abstinence 
(when this is in line with the preferred and usual life 
style of the participant) can be included. Sterilized male 
patients who have had vasectomy with documented 
aspermia post procedure can be included. In addition, 
male patients are not allowed to donate sperm from 
screening to 90 days after the last administration of 
IMP.
Section 11.3 “Appendix 3: Contraceptive and Barrier
Guidance”:
11.3.1. General Instructions and Definitions
Contraceptive use by men and women should be 
consistent with local regulations regarding the 
methods of contraception.
Male patients are not allowed to donate sperm during 
the period from signing of ICF, throughout the 
duration of the trial, and for 90 days after the last 
administration of IMP (trial medication injection).
Women of childbearing potential must have a 
negative serum pregnancy test at the screening visit 
and a negative urine pregnancy test at baseline before 
IMP can be administered.
A woman is considered of childbearing potential 
unless she is either:
Postmenopausal, defined by continuous 
amenorrhea for at least 1 year without an 
alternative medical cause with a follicle 
stimulating hormone (FSH) measurement of 
>40 IU/L. A historical pretreatment FSH 
measurement of >40 IU/L is accepted as proof of 
a postmenopausal state for women on hormone 
replacement therapy. 
Surgically sterilized: Women who have had a 
documented permanent sterilization procedure 
(ie, hysterectomy, bilateral salpingectomy, or 
bilateral oophorectomy).
11.3.2. Female Contraception for Women of 
Childbearing Potential
Women of childbearing potential should use a highly 
effective or acceptable method of contraception 
during the trial and for 90 days after the last 
administration of the IMP. 
The following highly effective and/or acceptable 
methods of contraception, described in the 
Recommendations Related to Contraception and 
Pregnancy Testing in Clinical Trials8, are allowed in 
this trial:
Combined (estrogen and progestogen containing) 
hormonal contraception associated with 
inhibition of ovulation:
Oral
Intravaginal
be used in addition to highly 
effective methods.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
133
Section(s)
Change 
Rationale
Transdermal
Progesterone-only hormonal contraception 
associated with inhibition of ovulation:
Oral
Injectable
Implantable
Progesterone-only oral hormonal contraception, 
where inhibition of ovulation is not the primary 
mode of action
Intrauterine device (IUD)
Intrauterine hormone-releasing system (IUS)
Bilateral tubal occlusion
Vasectomized partner
Sexual abstinence
Male or female condom with or without 
spermicide
Cap, diaphragm, or sponge with spermicide
11.3.3. Male Contraception
An acceptable method of contraception is a condom.
1. Women of childbearing potential must have a negative 
serum pregnancy test at the screening visit and a negative 
urine pregnancy test at baseline before trial medication 
(injection) can be administered. Women are considered of 
childbearing potential unless they are postmenopausal 
(defined by continuous amenorrhea) for at least 1 year with 
a follicle stimulating hormone (FSH) of >40 IU/L or are 
surgically sterilized (ie, women who had a hysterectomy, 
both ovaries surgically removed, or have a documented 
permanent female sterilization procedure including tubal 
ligation). FSH can be used to confirm postmenopausal 
status in amenorrheic patients not on hormonal replacement 
therapy. For patients on hormonal replacement therapy, a 
historical FSH value that was measured prior to initiation of 
hormonal replacement therapy is acceptable to determine 
postmenopausal status.
2. Women of childbearing potential should use a highly 
effective method of contraception (ie, 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 containing) 
hormonal contraception associated with inhibition of 
ovulation:
o
oral
o
intravaginal
o
transdermal
progestogen-only hormonal contraception associated 
with inhibition of ovulation:
o
oral
o
injectable
o
implantable

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
135
Section(s)
Change 
Rationale
Section 1.3 and Section 11.11.1 “Schedule of Activities for 
Stage B and Follow-up” (normal and during COVID-19
Pandemic): 
Addition of the following footnote to “Concomitant 
therapies”:
Any vaccination received during the trial (from screening 
onwards) will be entered as concomitant medication.
Note: For patients who provide separate consent, the titers 
of produced vaccination antibodies will be measured 
using retained blood samples (left over blood samples 
taken for other tests) during the trial.
Section 7.4 “Prior Treatments and Concomitant 
Medications”:
…
As part of prior medication, details collected at screening 
should include all information the patient, his/her legally 
authorized representative (according to local 
regulations), or caregiver can remember about previous 
vaccinations received, including administration date and 
brand name, if known (note: if in the past a same vaccine 
was received more than once, including as booster, only 
the last one is to be collected). Any vaccination received 
during the trial, including administration date and brand 
name, will be entered as concomitant medication.
Section 9.1.1 “Vaccination History and Vaccinations 
During the Trial” 
At screening, the investigator will ask the patient about 
all vaccination received in the past. Any vaccination 
information the patient, his/her legally authorized 
representative (according to local regulations), or 
caregiver can remember should be recorded in the 
eCRF (with the brand name of the vaccine and date of 
vaccine administration recorded, if possible). If in the 
past a same vaccine was received more than once, 
including as booster, only the last one is to be collected. 
Any vaccination received during the trial, including 
administration date and brand name, will be entered as 
concomitant medication (see Section 7.4).
For patients who provide separate consent, the titers of 
produced vaccination antibodies will be measured using 
retained blood samples (left over blood samples taken 
for other tests) during the trial (see Section 11.2).
Section 11.2 “Appendix 2: Clinical Laboratory Tests”: 
…
# Blood samples may also be used to cross-validate the PK, PD, 
biomarker and ADA assays in CIDP matrix (serum and plasma),
as well as used for vaccination antibody testing.
Section 2.2
Section 2.2 “Definition of Terms”
Definition of ECI:
…
Patients who have no change in adjusted INCAT score 
during the run-in period and deteriorated on I-RODS 
Clarification of ECI, based on 
I-RODS and grip strength.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
136
Section(s)
Change 
Rationale
and/or grip strength during run-in can be entered in 
Stage B in the following cases:
…
Section 3.3.1, 
Section 3.3.2
Section 3.3.1 “Benefit”
… In addition, Phase 3 studies with efgartigimod IV in 
patients with gMG showed that the trial’s primary 
endpoint was met with statistical significance. The 
primary endpoint was defined as the “percentage of 
anti-acetylcholine receptor antibody (AChR-Ab) 
seropositive patients who, during the first cycle, have a 
points in the Myasthenia Gravis 
Activities of Daily Living (MG-ADL) total score 
consecutive 
weeks, with the first reduction occurring no later than 
1 week after the last investigational medicinal product 
(IMP) infusion.” A total of 67.7% of AChR-Ab positive 
patients treated with efgartigimod achieved the primary 
endpoint compared with 29.7% on placebo (p<0.0001).
In the overall patient population (AChR-Ab seropositive 
and seronegative patients), 67.9% of the patients treated 
with efgartigimod were MG-ADL responders compared 
with 37.3% on placebo (p<0.0001). Other key secondary 
endpoints for this study were also met with high 
statistically significance.
Section 3.3.2 “Risks”:
… In clinical trials to date, efgartigimod has been well-
tolerated in healthy adult subjects and patients with gMG 
and ITP, separately; efgartigimod was administered 
either IV or SC: the majority of treatment-emergent 
adverse events (TEAEs) were considered to be mild 
(grade 1) or moderate (grade 2) in severity. No TEAEs of 
grade
suspected to be related to efgartigimod is headache; 
however, there is no evidence that headache occurs more 
frequently in patients administered efgartigimod than in 
patients administered placebo.  
In the Phase 3 trials in patients with gMG, the majority 
of TEAEs were reported as mild (grade 1) or moderate 
reported TEAEs during all cycles of efgartigimod 
10 mg/kg treatment in the overall population who 
received at least 1 dose of efgartigimod were headache, 
nasopharyngitis, upper respiratory tract infection, 
diarrhea, urinary tract infection, nausea, myalgia, and 
occurred in >2 patients who received efgartigimod were 
headache and myasthenia gravis. The only TEAE that 
led to efgartigimod discontinuation reported in 
>2 patients was myasthenia gravis. No SAEs were 
assessed by the investigator as related to efgartigimod 
treatment.
Sections updated to align with 
the current version of the 
Investigator’s Brochure 
(version 9.0).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
137
Section(s)
Change 
Rationale
Four fatal cases have been reported, however, none of 
the fatal events were assessed by the investigator as 
related to efgartigimod treatment. Causes of death was 
unknown in a patient who died at home without 
witness. The other 3 patients died due to myasthenia 
gravis crisis, lung cancer Stage IV, and acute 
myocardial infarction. These 4 patients were between 
55 and 79 years old and all had clear comorbidities, 
including underlying gMG.
Adverse drug reactions were identified based on safety 
data from the Phase 3 double-blind, placebo-controlled 
trial in patients with gMG and include upper 
respiratory tract infection, urinary tract infection, 
bronchitis, myalgia, and procedural headache. Most 
AESIs were mild or moderate in severity. Few patients 
had severe or serious AESIs reported, and no SAEs of 
AESIs were assessed by the investigator as related to
efgartigimod treatment.
Due to the efgartigimod mechanism of action of 
reducing IgG levels, AEs in the Infections and 
Infestations SOC have been defined as AESIs. In the 
Phase 3 trials with efgartigimod IV in patients with 
gMG, the most frequently reported treatment-emergent 
AESIs by PT were nasopharyngitis, upper respiratory 
tract infection, urinary tract infection, and bronchitis.
Injection or catheter site reactions are AEs for which there 
exists a reasonable possibility of a causal relationship with 
the efgartigimod administration procedure, although there 
is no evidence that these AEs are related to efgartigimod 
itself. Chills were reported in healthy subjects administered 
efgartigimod IV 25 mg/kg. However, infusion related 
reactions (IRRs) are reactions that are unpredictable, 
non dose related, generally unrelated to the drug's 
pharmacological activity, and usually resolve when 
treatment is discontinued. IRRs include hypersensitivity 
reactions and cytokine release syndromes. These reactions 
can occur during the infusion of a cytotoxic or monoclonal 
antibody therapy (uniphasic reaction) and/or within hours 
of an infusion (biphasic/delayed reaction) and may be 
caused by the therapeutic agent, diluent, or delivery 
vehicle. IRR symptoms, caused by the release of cytokines 
from the cells, include nausea, headache, tachycardia, 
hypotension, rash, flushing, dyspnea, bronchospasm, back 
pain, fever, urticaria, and edema. All therapeutic proteins 
have the potential to elicit immune responses, 
potentially resulting in hypersensitivity or allergic 
reactions. As with any IV injection, the potential exists 
for infusion-related reactions (IRRs) to occur during or 
within 48 hours following the administration of 
efgartigimod. Overall, the frequency of IRRs in the 
clinical trials was low. At the preferred term (PT) level, 
no TEAEs of drug hypersensitivity or anaphylactic 
reaction were reported. None of the IRRs reported 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
138
Section(s)
Change 
Rationale
were serious. Most IRRs were mild in severity and no 
IRRs resulted in a change in efgartigimod 
administration. Because these reactions are difficult to 
evaluate in prospective randomized clinical trials and due 
to the unexpected nature of these events, patients infused 
IV with efgartigimod are proactively monitored at the site, 
based on the patient’s clinical status, for at least 1 hour 
following the end of the infusion. For administration of 
efgartigimod PH20 SC, the local injection site will be 
monitored during the trial.
In the Phase 3 trial with efgartigimod IV in patients 
with gMG, no differences or imbalances were observed 
between the efgartigimod and placebo groups in the 
incidence or rates of abnormal values in clinical 
laboratory parameters. There was no reduction in 
levels of serum albumin with the administration of 
efgartigimod. In the extension trial in patients with 
abnormalities were lymphocyte count decreased.
There has been no evidence of an increased risk of 
infection. No clinically significant changes in vital signs 
and/or electrocardiogram (ECG) findings have been 
observed in clinical trials to date.
No deaths have occurred in any efgartigimod clinical trial.
Section 5.4
Section 5.4 “Measures to Minimize Bias: Randomization 
and Blinding”
…
Refer to Section 7.2 for the preparation and 
administration of the IMP, thereby keeping the blind 
during Stage B.
…
Reference added to section 
with explanation how blind of 
IMP is kept for Stage B.
Section 7.1
Section 7.1 “IMP(s) Administered”
…
IMP will be provided by the sponsor and is manufactured in 
accordance with Good Manufacturing Practice 
regulations. 
The efgartigimod PH20 SC formulation will be provided in a 
vial at a concentration of 165 mg/mL or 180 mg/mL (new 
concentration) for efgartigimod and 2000 U/mL for rHuPH20 
(also referred to as ARGX-113/rHuPH20). Each dose of 
efgartigimod PH20 SC will include 1000 mg efgartigimod. 
Note that there will be a transition period during which 
both formulations of efgartigimod PH20 SC (with
efgartigimod at a concentration of 165 mg/mL or 
180 mg/mL) will be used. After this transition period, all 
patients will receive the efgartigimod PH20 SC formulation 
with efgartigimod at the higher concentration of 
180 mg/mL. The formulation with the higher concentration 
of efgartigimod (180 mg/mL) reduces the dosing volume 
for each SC injection.
Placebo will be vehicle (with 2000 U/mL of rHuPH20) 
provided in a vial as ready SC formulation. For both 
Efgartigimod PH20 SC will 
be used with efgartigimod at a 
higher concentration 
(180 mg/mL instead of 
165 mg/mL), thereby reducing 
the dosing volume for each 
SC injection.
The only difference between 
the 165 mg/mL and 
180 mg/mL batches is a 
higher protein concentration 
(±10% higher protein 
concentration with 
180 mg/mL compared to 
165 mg/mL) and a slight 
reduction of the dosed amount 
of rHuPH20 with the new 
formulation. This difference is 
not expected to result in a 
different activity or safety 
profile.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
139
Section(s)
Change 
Rationale
efgartigimod PH20 SC formulations (with efgartigimod at 
a concentration of 165 mg/mL or 180 mg/mL), a 
corresponding placebo is available containing placebo drug 
product at the same volume and in the same vial as the 
active drug product.
Section 7.2
Section 7.2 “Preparation, Handling, Storage, 
Administration, and Accountability”
…
For Stage B IMP will be provided in a blinded vial. The 
trained and authorized site staff will blind the syringe for 
administration using a yellow blinding foil covering the barrel 
of the syringe before withdrawing IMP from the blinded vial. 
The administration is then performed by the site staff who 
prepared the syringe.
Efgartigimod PH20 SC will be provided as a sterile, clear 
to opalescent, yellowish solution for SC injection.
Placebo will be provided as a sterile, colorless, clear 
solution for injection in glass vials with the same 
formulation as the efgartigimod PH20 SC solution for 
injection, but without the active ingredient.
The vials for the double-blind Stage B will be covered 
with a blinding shell.
The trained and authorized staff will use an amber 
colored syringe for preparation and administration of 
IMP. The administration is then performed by the site 
staff who prepared the syringe.
Clarification of IMP 
presentation, preparation, 
administration, and blinding 
methods.
Section 9.4.1, 
Section 10.1.5.1
Section 9.4.1 “Adjusted Inflammatory Neuropathy Cause 
and Treatment (INCAT) Disability Score”:
…
There are 3 different baseline INCAT scores during the 
trial, at the beginning of each stage. Each baseline 
INCAT score is always the total INCAT score (not the 
adjusted INCAT score, which is used for post-baseline 
assessments):
Baseline run-in period = Total INCAT score at the 
first visit of the run-in period (RI-V1)
Baseline Stage A = Total INCAT score at D1A 
(ie, the first visit of Stage A [A-V1])
Baseline Stage B = Total INCAT score at D1B (ie, the 
first visit of Stage B [B-V1])
Note: The baseline total INCAT score is calculated as 
the sum of the arm and leg sub score, without 
adjustment of the arm sub score.
For the post-baseline visits, the adjusted INCAT score 
calculation is based on the baseline of the 
corresponding stage.
Section 10.1.5.1. “Trial Baselines”
The baseline value for the run-in period will be the 
assessment recorded at visit R1-V1. The baseline value 
Clarification of INCAT 
baseline.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
140
Section(s)
Change 
Rationale
for Stage A will be the last assessment prior to the first dose 
of open-label trial medication in Stage A. …
Section 11.4
Section 11.4 “Appendix 4: Adverse Events: Definitions and 
Procedures for Recording, Evaluating, Follow-up, and 
Reporting.”
Section 11.4.1 “Definition of AE”:
AE Definition:
An AE is any untoward medical occurrence in a patient or
clinical trial patient, …
Definition of Unsolicited and Solicited AE:
An unsolicited AE is an AE that was not solicited using a 
Patient Diary and that is communicated by a patient who 
has signed the informed consent (or was signed by the 
patient’s legally authorized representative [according to 
local regulations]). Unsolicited AEs include serious and 
non-serious AEs.
Potential unsolicited AEs may be medically attended 
(ie, symptoms or illnesses requiring a hospitalization, or 
emergency room visit, or visit to/by a health care 
provider). The patient will be instructed to contact the 
site as soon as possible to report medically attended 
event(s), as well as any events that, though not medically 
attended, are of patient’s concern. Detailed information 
about reported unsolicited AEs will be collected by 
qualified site personnel and documented in the patient’s 
records.
Unsolicited AEs that are not medically attended nor 
perceived as a concern by the patient will be collected 
during interview with the patient and by review of 
available medical records at the next visit.
Solicited AEs are predefined local (at the injection site) 
and systemic events for which the patient is specifically 
questioned, and which are noted by the patient in his/her 
diary.
Events to be collected as AEs Meeting the AE Definition
…
Events NOT to be collected as AEs Meeting the AE 
Definition
…
Section 11.4.2 “Definition of SAE”:
An SAE is defined as any untoward medical occurrence 
that, at any dose:
c. Requires inpatient hospitalization or prolongation of 
existing hospitalization
… Complications that occur during hospitalization are 
AEs. If a complication prolongs hospitalization or fulfills 
any other seriousness criteria, the event is will be 
considered as serious. … Hospitalization for elective 
treatment of a pre-existing condition that did not worsen 
from baseline is not considered collected as an AE.
Appendix for AEs/SAEs 
updated to align with the 
current protocol template of 
argenx, including addition of 
causality assessment and 
clarification of SAE reporting.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
141
Section(s)
Change 
Rationale
Section 11.4.3 “Recording and Follow-up of AE and/or of 
SAE
AE and SAE Recording:
… It is not acceptable for the investigator to send 
photocopies of the patient’s medical records to the SAE 
coordinator/sponsor SGS in lieu of completion of the 
AE/SAE CRF page or SAE form.
There may be instances when copies of medical records for 
certain cases are requested by eg, the SAE coordinator
SGS or the sponsor. …
Assessment of Event Severity:
The investigator will make an assessment of severity for 
each AE and SAE reported during the trial.  
All events (AEs and SAEs) 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. The 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, using. The 
CTCAE displays grades 1 through 5 with unique clinical 
descriptions of severity for each AE based on the following 
general guideline:
Grade 1: … 
Grade 2: moderate; minimal, local or noninvasive 
intervention indicated; limiting age-appropriate 
instrumental activities of daily living (eg, preparing 
meals, shopping for groceries or clothes, using the 
telephone). 
Grade 3: severe or medically significant but not 
immediately life-threatening; hospitalization or 
prolongation of hospitalization indicated; disabling; 
limiting self-care activities of daily living (ie, bathing, 
dressing and undressing, feeding self, using the toilet, 
taking medications, and not bedridden). 
Grade 4: …; or urgent intervention indicated.
Assessment of Causality:
The investigator is obligated to assess the relationship 
between IMP and each occurrence of each AE/SAE., using 1 
of the following categories:
Not related: events can be classified as “not 
related” if there is not a reasonable 
possibility that the IMP caused the AE.
Unlikely related: 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, 

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
142
Section(s)
Change 
Rationale
or reaction to concomitant medication, 
appear to explain the reported AE.
Possibly related: 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.
Probably related: 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.
Related: 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.
In final evaluation for reporting, the assigned 
relationship, as per Council for International 
Organizations of Medical Sciences (CIOMS), will be 
converted into a “binary determination” as follows: 
Events with an assigned relationship of “unrelated” or 
“unlikely related” will be grouped into the “unrelated” 
category. Events with an assigned relationship of
“related,” “possibly related,” or “probably related” will 
be grouped into the “related” category.
…
There may be situations in which an SAE has occurred, and 
the investigator has minimal information to include in the 
initial report to the SAE coordinator/sponsor SGS.
However, it is important that the investigator always makes 
an assessment of causality for every event before the initial 
transmission of the SAE data to the SAE 
coordinator/sponsor SGS. …
Follow-up of AE and SAE:
The investigator is obligated to perform or arrange for the 
conduct of supplemental measurements and/or evaluations as 
medically indicated or as requested by the SAE 
coordinator/sponsor SGS to elucidate the nature and/or 
causality of the AE or SAE as fully as possible. … 
Thereafter, new/updated information will be collected in the 
safety database at the SAE coordinator SGS. The 
investigator will submit any updated SAE data to the SAE 
coordinator SGS within 24 hours of receipt of the 
information.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
143
Section(s)
Change 
Rationale
Section 11.4.4 “Reporting of SAEs
SAE Reporting via Paper Form:
Facsimile transmission of the paper SAE form is the 
preferred method to transmit this information to SGS.
In rare circumstances and in the absence of facsimile 
equipment, notification by telephone is acceptable with a 
copy of the SAE data collection tool sent by overnight mail 
or courier service.
Initial notification via telephone does not replace the need 
for the investigator to complete and sign the SAE CRF pages 
within the designated reporting time frames.
All SAEs will be recorded (within 24 hours) on the paper 
SAE report form and the AE form in the eCRF. The 
investigator or designated site staff should check that all 
entered data are consistent. An alert email for the SAE report 
in the eCRF will then automatically be sent by email to the 
sponsor’s designated CRO SAE coordinator's 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 SAE coordinator.
Section 11.11
Throughout the Appendix:
Efficacy is planned to be assessed using a video interview 
between the evaluating physician and the patient. However, it 
has been added that a telephone interview can be performed 
instead, in case a video interview is not possible.
Scheme for Home Visits: Tasks for Treating Physician
Confirmation that IMP can be administered
IMP Administration
IMP can be administered at home by a qualified person 
(eg, home nurse) after confirmation of the treating 
physician.
Further clarification how to 
perform a home visit during 
the COVID-19 pandemic 
Section 11.11.1
Section 11.11 “Schedule of Activities (SoA) During 
COVID-19 Pandemic”: 
Section 11.11.1 “SoA for Screening, Run-in, and Stage A
During COVID-19 Pandemic”: 
Training for IMP self-administration during the second, 
third, and fourth visits of Stage A will only be performed if 
feasible during the COVID-19 pandemic (indicated in 
black open circles in the Schedule of Activities) and are not 
mandatory (indicated in red solid dots in the Schedule of 
Activities); these trainings are only mandatory in the 
“normal situation” (as indicated in the Schedule of 
Activities in Section 1.3.1).
Correction that training for 
IMP self-administration at 
certain visits of Stage A is not 
mandatory for special visits 
(as described in Appendix 11) 
during the COVID-19
pandemic.
Footnote d:
Note: Patients with ECI preferably have a combined visit that 
includes the last visit of Stage A (EOSA) and the first visit of 
Stage B (D1B). In this case, all assessments at EOSA are 
mandatory. 
Explanation which 
assessments are mandatory at 
the last visit of Stage A for 
patients who start Stage B, 
and at the last visit of Stage B

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
145
Section(s)
Change 
Rationale
An Appendix has been added to this protocol with 
the minimum assessments required to perform the 
trial during the COVID-19 pandemic in case the 
patient cannot attend the visit at the hospital site.
perform all assessment as planned for this 
trial (as outlined in the Schedule of 
Activities). Therefore, an Appendix to the 
protocol for this trial has been developed, 
with the minimum assessments required to 
guarantee the safety and well-being of the 
patients during the trial, and to secure the 
collection of the critical parameters for 
analysis.
Synopsis
Stage A
No formal hypothesis testing will be conducted for 
Stage A. For the interim analysis, the percentage of 
ECI responders on efgartigimod PH20 SC will be 
summarized using an exact Clopper-Pearson 90% 
1-sided lower CI.
Stage B
Alternative hypothesis: The event rate of 
efgartigimod PH20 SC compared to placebo is < 1
(ie, hazard ratio < 1).
Typo –update was left out from the 
synopsis during previous protocol 
amendment (when changed were made in 
Section 10.2 of the protocol).
Synopsis, 
Section 1.3.1, 
Section 5.1.1.3, 
Section 5.1.2, 
Section 7.1.1.
Synopsis and Section 5.1.1.3:
… documented evidence for worsening on the 
total adjusted Inflammatory Neuropathy Cause 
and Treatment (INCAT) disability score, further 
referred to as “adjusted INCAT score.” within 
3 months prior to screening is available 
compared to previous adjusted INCAT score 
within 6 months prior to screening. 
Section 1.3.1 (SoA footnote “a”), Section 5.1.2, 
and Section 7.1.1:
… documented evidence for worsening on the 
adjusted INCAT score within 3 months prior to 
screening is available compared to previous 
adjusted INCAT score within 6 months prior 
to screening. 
Clarification that for “documented 
evidence for worsening on the adjusted 
INCAT score,” the reference INCAT 
score should be 6 months before 
screening.
Synopsis, 
Section 5.1
Synopsis:
- Run-in period: 4
up to 12 weeks …
Section 5.1: 
- Run-in period: 4  up to 12 weeks …
Correction that the run-in period is up to 
12 weeks and that there is no minimum of 
4 weeks required in the run-in period (as 
was erroneously stated at some places in 
the protocol) before going to Stage A of 
the trial.
Footnotes from 
Schedules of 
Activities and 
Section 9.5.1
Schedule of Activities for Screening, Run-in, and 
Stage A: 
g. Includes physical examination, height, weight, 
semi-supine blood pressure, and heart rate, and 
body temperature.
h. Includes physical examination, weight, semi-supine 
blood pressure, and heart rate, and body 
temperature.
The vital signs blood pressure and heart 
rate are measured in a semi-supine 
position.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
147
Section(s)
Change 
Rationale
Section 11.1.3 “Informed Consent Process”
… legally authorized representative (according to 
local regulations) …(3 times)
Section 5.1.4, 
Section 7.2
Section 5.1.4 “Stage B”
Patients with ECI during Stage A will be 
randomized at Stage B baseline (D1B) in a 1:1 
ratio to receive weekly SC administrations of 
efgartigimod PH20 SC or matching placebo.
Section 7.2 “Preparation, Handling, Storage, 
Administration, and Accountability”:
For Stage B, IMP will be provided in a blinded 
vial. The trained and authorized site staff will 
blind the syringe for administration using a 
yellow blinding foil covering the barrel of the 
syringe before withdrawing IMP from the 
blinded vial. The administration is then 
performed by the site staff who prepared the 
syringe.
A completely matching placebo is 
currently not available; however, 
blinding will be ensured as described in 
Section 7.2.
Synopsis, 
Section 6.2, 
Section 7.4.1, 
Section 7.4.2
Synopsis and Section 6.2 “Exclusion Criteria”:
12.a. Patients who received a live-attenuated 
vaccine fewer than 28 days before 
screening. Receiving an inactivated, 
sub-unit, polysaccharide, or conjugate 
vaccine any time before screening is not 
exclusionary.
Section 7.4.1 “Permitted Medication”: 
Any kind of vaccination, except for 
live-attenuated vaccines, is allowed at the 
discretion of the investigator.
Section 7.4.2 “Prohibited Medications”:
Live-attenuated vaccines (Note: Receiving 
an inactivated, sub-unit, polysaccharide, or 
conjugate vaccine any time before screening 
is not prohibited).
Live-attenuated vaccines are not allowed 
from 28 days before screening through 
28 days after the last IMP dose, 
consistent with the updated text in the 
efgartigimod Investigator’s Brochure 
(Version 8.0).
Synopsis and 
Section 6.2
Use of an investigational drug within 3 months or 
5 half lives of the drug (whichever is longer) 
prior to first IMP administration.
(Note: This exclusion criterion is replaced by
the exclusion of patients who received a 
live-attenuated vaccine fewer than 28 days 
before screening; see above [ie, exclusion 
criterion 12.a.])
Exclusion criterion #12 is captured 
already in #9: “Within 3 months [or 
5 half-lives of the drug, whichever is
longer] before screening: plasma 
exchange or immunoadsorption, any 
concomitant Fc containing therapeutic 
agents or other biological, or any other 
investigational product.”
Section 7.4
Clinically relevant prior treatments received by the 
patient including:
Previous treatments or procedures for CIDP in the 
last 2 years with patient’s response and reason for 
changing treatment/dose in the last 12 months. 
All previous medications should be 
collected in order to check inclusion 
criterion #6 (which states that 
corticosteroids and/or IVIg or SCIg 
should have started within the last 5 years 
before screening).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
148
Section(s)
Change 
Rationale
Section 8.3
(During Stage A only:) Adjusted INCAT 
2 points from Stage A
baseline (D1A).
Addition of withdrawal criterion, because 
it is unlikely that these patients will 
benefit from efgartigimod PH20 SC.
Section 11.4.4
SAE Reporting to SGS via an Electronic Data 
Collection Tool
The primary mechanism for reporting an SAE to 
SGS will be the electronic data collection tool.
If the electronic system is unavailable, then the site 
will use the paper SAE data collection tool (see 
next section) in order to report the event within 24 
hours.
The site will enter the SAE data into the electronic 
system as soon as it becomes available.
After the trial is completed at a given site, the 
electronic data collection tool will be taken off-line 
to prevent the entry of new data or changes to 
existing data.
If a site receives a report of a new SAE from a trial 
patient or receives updated data on a previously 
reported SAE after the electronic data collection 
tool has been taken off-line, then the site can report 
this information on a paper SAE form (see next 
section) or to SGS by telephone.
Contacts for SAE reporting can be found on the 
frontpage.
SAE Reporting to SGS via Paper Form
Facsimile transmission of the paper SAE form is the 
preferred method to transmit this information to 
SGS.
In rare circumstances and in the absence of 
facsimile equipment, notification by telephone is 
acceptable with a copy of the SAE data collection 
tool sent by overnight mail or courier service.
Initial notification via telephone does not replace the 
need for the investigator to complete and sign the 
SAE CRF pages within the designated reporting 
time frames.
All SAEs will be recorded on the paper SAE 
report form and the AE form in the eCRF. The 
investigator or designated site staff should check 
that all entered data are 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.
Clarification of SAE reporting system.
Section 11.12 
“Appendix 12”
An Appendix has been added to this protocol with 
the administrative structure.
For completeness, the vendors contracted 
by argenx have been added.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
149
General Amendment 1, General Protocol Version 2.0: 
The major changes from Protocol Version 1.0 compared to Protocol Version 2.0 are summarized 
in the table below. Deleted text is indicated in strikethrough; a bold and underlined font is used 
to indicate added text. Minor administrative editorial changes (eg, to improve readability or 
correct spelling mistakes) are not summarized in the following table: 
Summary of Changes Between Protocol Version 1.0 and Protocol Version 2.0 
Section(s)
Change 
Rationale
General change 
throughout the 
protocol of 
primary 
endpoint of 
Stage B: 
Confirmation of 
deterioration in 
Stage B
3-7 days after 
the first adjusted 
INCAT 
deterioration of 
1 point; and no 
confirmation 
needed in case 
of adjusted 
INCAT 
deterioration of 
points
Stage B: Primary Endpoint:
Time to first confirmed adjusted INCAT 
deterioration compared to Stage B baseline. 
Note: Time to first confirmed adjusted INCAT 
deterioration is defined by the time from first dose 
of double-blind IMP to the first adjusted INCAT 
score increase of 1 point compared to Stage B
baseline, if the deterioration is confirmed at a 
consecutive visit one week 3-7 days after the first 
adjusted INCAT score increase of 1 point. For 
patients with an increase of 2 or more points on 
the adjusted INCAT score compared to Stage B 
baseline, no confirmation is required.
The time window for confirmation of 
INCAT deterioration has been shortened 
to reduce the time of clinical 
deterioration, and offer follow-up
treatment as soon as possible. The 
minimal interval is shorted to the shortest 
interval of IMP injection allowed in the 
protocol, ie, 3 days.
The confirmation of clinical deterioration 
during Stage B for those patients with an 
adjusted INCAT increase of 2 points or 
more compared to Stage B baseline has 
been deleted to prevent further 
deterioration. It is considered to be more 
appropriate to give these patients the 
possibility to roll over immediately when 
this level of deterioration is observed or 
receive standard of care treatment.
Title page
Addition of the logo of the trial.
Addition of the logo of the trial.
Title page 
and signature 
pages
Moved the trial name ‘ADHERE’ to a separate row 
(ie, ‘acronym: ADHERE’) instead of adding this 
after the title.
The acronym is not part of the title of the 
trial.
Section 1.3.1
k. These tests are optional and are only required for 
confirmation of improvement (for patients with 
improvement in the previous visit).
Update of footnote k of the Schedule of 
Activities for Screening, Run-in, and 
Stage A.
General 
change 
throughout the 
protocol: 
The safety 
follow-up visit 
in Stage B
should be 
performed 
28 days after 
the last IMP 
dose
W48/ED + 28 (±3) days after last IMP dose
Follow-up: 28 days after the last dose of 
investigational medicinal product (IMP) or the 
Week-48 visit if the patient does not intend to roll 
over into the open-label extension (OLE) trial 
ARGX-113-1902.
The safety follow-up visit in Stage B
should be performed 28 days after the 
last IMP dose instead of 28 days after the 
week 48 visit. As the last IMP dose is 
administered at week 47, the safety 
follow-up visit should be performed at 
week 51, instead of week 52, and the 
total trial duration will be 80 weeks 
(instead of 81 weeks).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
150
Section(s)
Change 
Rationale
Section 2.2
A deterioration of the adjusted INCAT score is 
defined as an increase (ie, worsening) of 1 point 
on the adjusted INCAT score compared to 
Stage B baseline which is confirmed at a 
consecutive visit 3-7 days after the first adjusted 
INCAT score increase of 1 point. For patients 
with an increase of 2 or more points on the 
adjusted INCAT score compared to Stage B 
baseline, no confirmation is required.
Addition of definition of adjusted 
INCAT deterioration
Synopsis, 
Section 5.1.4,  
and 
Section 7.7
Patients completing week 48 and in the opinion of 
the investigator benefit from trial treatment at 
week 48 or patients having an event of confirmed 
worsening on the adjusted INCAT score of 1 point 
or a worsening on the adjusted INCAT score of 
points compared to Stage B baseline (for the 
latter, no confirmation is needed) will be allowed 
to roll over to the open-label extension (OLE) trial 
when they are receiving IMP. Patients completing 
week 48 who will not roll over to the OLE trial as 
well as patients with an early discontinuation, will 
have a safety follow-up visit 28 days after the week 
48 visit (or 28 days after the last IMP administration
if the patient is discontinuing from the trial), will 
stop the trial, and will be treated as considered 
appropriate by the investigator.
When 88 events have been observed for the primary 
endpoint analysis of Stage B (see sample size 
determination for Stage B in Section 10.3), then the 
trial will stop. In that case, patients in Stage A and 
Stage B will perform an early discontinuation 
visit and patients who are receiving IMP will be 
given the opportunity to continue efgartigimod 
PH20 SC treatment in be allowed to roll over to
the OLE trial at their next visit. Patients who will 
not roll over to the OLE trial, will attend a 
follow-up visit 28 days after the last IMP dose.
Better explanation when patient can roll 
over to the open-label extension trial and 
to make clearer that in case 88 events 
have been observed, an early 
discontinuation visit needs to be 
performed (and the patients can then roll 
over to open-label extension trial or have 
a follow-up visit after 28 days in case 
they will not roll over).
Section 5.1.5
An unscheduled visit is to be planned for: 1) safety 
reasons, 2) assessment of ECMD during the run-in 
period, and 3) assessment of efficacy during 
Stage B (eg, confirmation of clinical deterioration 
during Stage B (worsening in on the adjusted 
INCAT score 
of 1 point), if no trial visit is 
planned at that time, or 4) any other reason. 
Clarification when an unscheduled visit 
can be performed.
Inclusion 
criterion #5 in 
synopsis and 
Section 6.1
5. An adjusted
with a score of 2 
exclusively from leg disability, in at least one 
leg at the first run-in visit (RI-V1; for patients 
entering run-in) or Stage A baseline (A-V1; for 
treatment-naïve patients with documented 
evidence for worsening on the total adjusted 
INCAT disability score within 3 months prior to 
screening).
During the trial, the total score for the 
deterioration is observed. For screening, 
the minimal INCAT score was set at 2, 
to make sure there is still room for 
improvement during IMP treatment. For 
a low INCAT score of 2, we want to 
make sure that these 2 points come from 
the leg (as was done the FORCIDP1 trial 
in patients with CIDP).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
151
Section(s)
Change 
Rationale
Furthermore, as this is the first INCAT 
assessment in the trial, “adjusted” is 
deleted.
Exclusion 
criterion #11 
in synopsis 
and 
Section 6.2
11.Patients with any other known autoimmune 
disease that, in the opinion of the investigator, 
would interfere with an accurate assessment of 
clinical symptoms of CIDP “trial indication.” 
Addition of the trial indication in the 
exclusion criterion.
Section 3.1
The term chronic inflammatory demyelinating 
polyneuropathy (CIDP) has been used to identify 
patients with a chronically progressive or relapsing 
symmetric sensorimotor disorder with 
cytoalbuminologic dissociation and interstitial and 
perivascular endoneurial infiltration by 
lymphocytes and macrophages. A number of 
variants of CIDP have been described that have
immune or inflammatory aspects and 
electrophysiologic and/or pathologic evidence of 
demyelination in common. No consensus exists on 
the best approach to the nomenclature of these 
disorders. CIDP variants include disorders patients
with predominantly sensory symptoms, distal 
symmetric disorder (DADS), multifocal acquired 
demyelinating sensory and motor neuropathy 
(MADSAM) also known as Lewis-Sumner 
syndrome, and those with CIDP with associated 
central nervous system (CNS) demyelination or 
with other systemic disorders.1,21
CIDP most commonly has an insidious onset with 
either a chronic progressive or a relapsing course. 
Occasionally, complete remission occurs. The 
estimated prevalence of CIDP is 1.8-8.9 per 
100000.20 CIDP may occur at any age, but it is 
more common in the fifth and sixth decades. 
A rRelapsing course is associated with younger age 
of patients (third and fourth decades).
The most common treatments are currently 
immunosuppressive or immunomodulatory 
interventions. These agents include intravenous
immunoglobulin (IVIg), subcutaneous 
immunoglobulin (SCIg), plasmapheresis, 
prednisone, azathioprine, methotrexate, 
mycophenolate, cyclosporine, and 
cyclophosphamide. Their use is based on the 
proposed pathogenesis of CIDP as an immune-
mediated condition, though for some of these 
agents, there is no clear evidence of a beneficial 
treatment effect.
However, an unmet medical need exists for an 
efficacious treatment of CIDP with a more 
specific mechanism of action maintaining quality 
of life (QoL) at the highest levels for the longest 
Minor updates in the section “Trial 
Rationale” to align with the text for this 
section in the open-label extension trial.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
152
Section(s)
Change 
Rationale
period possible, a favorable safety and 
tolerability profile, and more convenient 
administration that has a significantly lower 
impact on daily routines than that provided by 
current treatments.
However, an unmet medical need exists for an 
efficacious treatment of CIDP with a favorable 
safety and tolerability profile and more convenient 
administration than that provided by current 
treatments.
It has been recognized from recent treatment trials 
that many CIDP patients are over treated and have 
stable disease off therapy, and there have been 
placebo response rates as high as 40%.16,33
Therefore, there is an unmet need in CIDP for a 
treatment with a more specific mechanism of 
action, which allows to have a significantly lower 
impact on daily routines, maintaining quality of life 
at the highest levels for the longest period possible, 
with less adverse drug reactions and lower 
treatment burden.
Section 7.4.2
Pulsed corticosteroids and oral daily 
mg/day.
Note: If tapering is required, it should be 
initiated during the screening period 
according to local practice.
…
If the administration of a non-permitted 
concomitant drug becomes necessary during the 
clinical trial, eg, because of AEs, the patient has 
to discontinue IMP be withdrawn from the trial,
as described in Section 8.2.
The note is added to clarify when 
tapering of the corticosteroids should be 
performed.
In case non-permitted concomitant drug 
is taken, the patient has to discontinue 
IMP (not the trial).
Section 9.1
Mycobacterium tuberculosis (TB):
Patients with clinical symptoms/signs of TB 
cannot enter the trial. TB test (Quantiferon) 
will be performed at screening and may be 
repeated during the trial, if necessary. If
positive at screening, the patient cannot enter the 
trial. If a negative Quantiferon test at 
screening turns positive during the trial, a 
clinical work up will be applied. If clinical 
symptoms or signs of TB occurs, it will be 
reported as an AE and treated accordingly.
Text updated to only exclude patients 
with clinical symptoms/signs of TB to 
enter the trial.
Section 9.4.2
The MRC sum score is evaluated bilaterally on 6
muscle groups of upper and lower limbs in order to 
obtain a summed score between 0 and 60:
Arm abductorsion of the arm
Elbow flexorsion of the forearm
Wrist extensorsion of the wrist
Hip flexorsion of the leg or hip flexion
Knee extensorsion of the knee
Updated to the original names of the 
movement of the muscles.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
153
Section(s)
Change 
Rationale
Foot dorsiflexorsal flexion of the foot
Section 9.8
Visit Reminder/Patient ID Card
Deletion of “Visit Reminder” and “ID” 
as this will be called a “Patient Card” in 
this trial.
Section 9.9
The actual date and time of collection of the blood 
sample will be recorded in the relevant section of the 
eCRF, as well as the reason in case no sample was 
taken.
Sentence is deleted from the 
pharmacokinetic assessment section, as 
the actual date and time of collection of 
samples will not be recorded in the 
eCRF.
Section 10.2
The statistical hypotheses were derived from the 
trial objectives as stated in Section 4.
Stage A:
No formal hypothesis testing will be conducted for 
Stage A. For the interim analysis, the percentage 
of ECI responders on efgartigimod PH20 SC will 
be summarized using an exact one-sided Clopper-
Pearson 90% CI. For the final analysis, the 
percentage of ECI responders on efgartigimod 
PH20 SC will be summarized using an exact 
Clopper-Pearson 2-sided 95% CI. This 95% two-
sided Clopper-Pearson CI will be used to 
compare the results of this study with results 
obtained in historical controls such as the 
PATH trial (van Schaik et al, 2018)15
Stage B:
Null hypothesis: The event rate of efgartigimod 
PH20 SC compared to placebo is 1 (ie, hazard 
ratio = 1).
Alternative hypothesis: The event rate of 
efgartigimod PH20 SC compared to placebo is 
< 1 (ie, hazard ratio < 1).
The statistical hypotheses section has 
been updated to better describe the 
currently planned analyses; ie, to 
compare Stage A with historical data 
using the Clopper-Pearson CI, and to 
hypothesis testing is two-sided.
Section 10.4.2.2
Change from Stage A baseline over time for 
subjects randomized to efgartigimod PH20 SC 
in:
Adjusted INCAT score.
MRC sum score.
24-item I-RODS disability scores.
TUG score.
Mean grip strength assessed by Martin 
vigorimeter.
Addition of a secondary efficacy 
endpoint to learn how subjects improve 
over longer time period (longer than the 
4–12 weeks in Stage A) when treated 
with efgartigimod PH20 SC.
Section 10.6
After the first 30 patients have reached the end of 
Stage A, an interim analysis will be performed and 
the proportion of patients with confirmed ECI will 
be calculated with the exact Clopper-Pearson 90% 
1-sided lower CI. If 19 of the 30 (63%) patients have 
a confirmed response, then there is 90% confidence 
that the true response rate is at least 50%. A non-
binding futility rule will be used to guide 
continuation of the study. If 9 or less of the first 
30 subjects have a confirmed ECI, the 
The language for the in interim analysis 
was m
subjects 
of the first 30 subjects will have 
confirmed ECI, the recommendation will 
be to stop the trial.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
154
Section(s)
Change 
Rationale
Clopper-Pearson 90% 1-sided lower CI will not 
exclude a rate of 21%, (placebo rate observed in 
ICE trial16), and the recommendation will be to 
stop the trial. The DSMB charter will contain full 
details on the non-binding futility rule and 
guidance to continue the trial. The decision to 
continue the trial will be advised by an independent 
DSMB (see Section 11.1.5) and the final decision 
will be taken by the sponsor.
Section 11.2 
Appendix 2 
Blood Screening for Infections:
HIV§ (Ag/Ab test)
§ CD4 count to be analyzed in case of positive HIV 
(see exclusion criterion #7)
Addition of footnote to HIV test 
(belonging to blood screening for 
infections) to make sure CD4 count is 
determined in case of a positive HIV test.
Section 11.7 
‘Appendix 7’
The scale is bilaterally applied to 6 muscle groups of 
the upper and lower limbs in order to obtain a summed 
score ranging from 0 to 60 for the MRC scale: 1) arm 
abductors; 2) elbow flexors; 3) wrist extensors; 4) hip 
flexors; 5) knee extensors; and 6) foot dorsiflexors.
Addition of footnote to explain the MRC 
scale, which was erroneously deleted 
during the writing of the protocol.
Section 12
‘References’
Hughes R, Dalakas M, Merkies I, et al. Oral 
fingolimod for chronic inflammatory demyelinating 
polyradiculoneuropathy (FORCIDP Trial): a double-
blind, multicenter, randomized controlled trial. The 
Lancet Neurology 2018;17(8):689-698.
Addition of a publication of the 
FORCIDP trial in patients with CIDP.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
155
11.14.
Appendix 14: Country-Specific Requirements
11.14.1.
Denmark-Specific Protocol Requirements
The Denmark-specific protocol requirements are summarized in the table below. Changes from 
the global protocol are indicated as follows: deleted text is indicated in strikethrough; a bold and 
underlined font is used to indicate added text. 
Denmark-specific Protocol Requirements
Section(s)
Change vs Global Protocol
Rationale
Section 1.3.1, 
Section 7.1.2, 
Section 11.12 
Section 1.3.1 and Section 11.12 (Appendix 12): Schedule 
of Activities for Screening, Run-in, and Stage A, footnote 
belonging to IMP administration; addition of the following:
Patients will be monitored for at least 1 hour after 
each of their first 3 IMP administrations.
Section 7.1.2 Stage A: Open-label; addition of the 
following:
Patients will be monitored for at least 1 hour after their 
first 3 IMP injections by a health care professional 
trained in the diagnosis and treatment of acute 
hypersensitivity reactions, with immediate access to 
equipment and medication to treat such reactions.
Based upon feedback of the 
Danish Medicines Agency 
(DKMA), patients will be 
monitored for at least 1 hour 
after the first 3 SC injections 
with efgartigimod PH20 SC by a 
trained health care professional. 
11.14.2.
Germany-Specific Protocol Requirements
The Germany-specific protocol requirements are summarized in the table below. Changes from 
the global protocol are indicated as follows: deleted text is indicated in strikethrough; a bold and 
underlined font is used to indicate added text. 
Germany-specific Protocol Requirements
Section(s)
Change vs Global Protocol
Rationale
Throughout the protocol 
(ie, Synopsis, Section 1.3 
[in both Schedules of 
Activities], Section 5.1, 
Section 5.1.3, Section 5.1.4, 
Section 5.1.6, Section 5.4.2, 
Section 5.5, Section 7.1.2, 
Section 8.2, Section 8.3, 
Section 11.12) 
Extension of safety follow-up period from 
28 days to 42 days:
…28 42 days…
Based upon feedback of the 
German Competent Authority 
(Paul Ehrlich Institut), the safety 
follow-up duration is extended 
from 28 days to 42 days.
Synopsis, Section 5.1
Synopsis:
The maximum total trial duration is 8280 weeks 
with a maximum of 61 weeks on IMP
Section 5.1 “Overall Design”: 
Total trial duration for each patient can be up to 
8280 weeks with a maximum of 61 weeks on 
IMP.
Correction; The total trial 
duration is 82 weeks instead of 
80 weeks, because the follow-up
period has been extended from 
28 days to 42 days.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
156
11.14.3.
Japan-Specific Protocol Requirements
The Japan-specific protocol requirements are summarized in the table below. Changes from the 
global protocol are indicated as follows: deleted text is indicated in strikethrough; a bold and 
underlined font is used to indicate added text. 
Japan-specific Protocol Requirements
Section(s)
Change vs Global Protocol
Rationale
Synopsis and 
Section 6.1
Addition of the following inclusion criterion:
10.For Japanese patients enrolled in sites in Japan only: A 
Japanese patient is defined as a patient whose parents 
and 4 grandparents are Japanese, who has the 
Japanese nationality, was born in Japan, has not lived 
outside of Japan for a total of >10 years, and currently 
lives in Japan.
The definition of a Japanese 
patient was added for 
clarification and completeness.
Section 1.3.1, 
Section 9.9, 
Section 
11.12.1
Addition of the following in the: 
- Schedule of Activities in Section 1.3.1 and Section 11.12.1
(added as a footnote to Blood sampling for PK and PD analysis 
at visits A-V1 and A-V4); and
- Section 9.9 Pharmacokinetics:
Two additional PK samples will be taken; ie, one sample 48 to 
96 hours after the 1st IMP injection and one sample 48 to 96 
hours after the 4th IMP injection in approximately 
10 Japanese patients in Stage A. Note that no additional PD 
samples will be taken at these timepoints.
See also below in the Japan-specific SoA
As a result of the outcome of 
the PMDA consultation, there 
will be additional PK sampling 
points around the time of the 
anticipated maximum 
concentration of efgartigimod 
during Stage A of the trial to 
better characterize the PK of 
efgartigimod in Japanese 
patients. 
Section 1.3 and 
Section 11.12.1 
Schedule of Activities for Screening, Run-in, and Stage A: 
-
Additional samples for blood & urine clinical laboratory 
safety tests at the 9th visit of Stage A, ie, visit A-V9 
(Day 57).
Schedule of Activities for Stage B and Follow-up: 
-
Additional samples for blood & urine safety tests at the 
2nd visit of Stage B, ie, visit B-V2 (Week 4).
Based upon feedback from the 
PMDA, extra samples for blood 
and urine clinical laboratory 
safety tests will be taken.
This sampling regimen allows 
weekly follow-up for the first 
4 weeks  of IMP dosing, and 
monthly assessments for the 
next few months, depending on 
the number of weeks a patient 
will be in Stage A. Once a 
patient is established into the 
treatment regimen in Stage B, 
laboratory safety tests will be 
performed every 3 months.
Note that additional laboratory 
safety tests can be requested by 
the investigator (eg, in case of 
any abnormality).
Section 1.3, 
Section 5.1.3. 
Section 5.1.4, 
Section 7.2, 
Section 11.12.1
Section 1.3.1: Schedule of Activities for Screening, Run-in, 
and Stage A; addition of the following in footnote to IMP 
administration: 
… Note: Patients will be asked to remain at the site for at 
least 1 hour after the end of the first 2 IMP injections 
(ie, at visits A-V1 and A-V2) and for at least 15 minutes 
after the end of the following IMP injections (from visit 
A-V3 onwards) in order to observe the patients for adverse 
events.
Based upon feedback from the 
PMDA, patients will be 
observed for adverse events 
after the end of each IMP 
injection for at least 1 hour (for 
the first 2 injections) or for at 
least 15 minutes (after the 
following injections).

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
157
Section(s)
Change vs Global Protocol
Rationale
Section 1.3.2: Schedule of Activities for Stage B and 
Follow-up; addition of the following in footnote to IMP 
administration: 
… Note: In order to observe the patients for adverse events, 
patients will be asked to remain at the site for at least 
15 minutes after the end of each IMP injection administered 
at the site; in case of IMP administration by a home nurse, 
the home nurse will observe the patients for adverse events 
after each IMP injection.
Section 5.1.3 Stage A; addition of the following:
… Patients will be asked to remain at the site for at 
least 1 hour after the end of the first 2 IMP injections 
(ie, at visits A-V1 and A-V2) and for at least 
15 minutes after the end of the following IMP 
injections (from visit A-V3 onwards) in order to 
observe the patients for adverse events. …
Section 5.1.4 Stage B; addition of the following:
… Patients will be asked to remain at the site for at 
least 15 minutes after the end of each IMP injection 
administered at the site in order to observe the 
patients for adverse events; in case of IMP 
administration by a home nurse (see below), the home 
nurse will observe the patients for adverse events after 
each IMP injection. … 
Section 7.2 Preparation, Handling, Storage, Administration, 
and Accountability; addition of the following: 
… In order to observe the patients for adverse events, 
patients will be asked to remain at the site for at least 
1 hour after the end of the first 2 IMP injections (ie, at 
visits A-V1 and A-V2 of Stage A) and for at least 
15 minutes after the end of the following IMP 
injections (from visit A-V3 of Stage A onwards and 
during Stage B) after each IMP injection administered 
at the site; in case of IMP administration by a home 
nurse, the home nurse will observe the patients for 
adverse events after each IMP injection. …
Section 11.12.1 (in “Appendix 12”): Schedule of Activities 
for Screening, Run-in, and Stage A; addition of the 
following in footnote to IMP administration:
… Note: In order to observe the patients for adverse events, 
patients will be asked to remain at the site for at least 1 hour 
after the end of the first 2 IMP injections (ie, at visits A-V1 
and A-V2) and for at least 15 minutes after the end of the 
following IMP injections (from visit A-V3 onwards) for each 
IMP injection that is administered at the site; in case of IMP 
administration by a home nurse, the home nurse will 
observe the patients for adverse events after each IMP 
injection.
Section 11.12.1 (in “Appendix 12”): Schedule of Activities 
for Stage B and Follow-up; addition of the following in 
footnote to IMP administration: 
… Note: In order to observe the patients for adverse events,
patients will be asked to remain at the site for at least 
15 minutes after the end of each IMP injection administered 
at the site; in case of IMP administration by a home nurse, 
the home nurse will observe the patients for adverse events
after each IMP injection.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
158
Japan-specific SoA for Screening, Run-in, and Stage A:
Additional PK sampling at visits A-V1 and A-V4 (see footnote §): 
Screening
Run-in 
Period 
weeks
Stage A: Open-Label Period 
1 Additional Week)
Unsche-
duled
Safety 
Follow-up
RI-
V1
RI-V2 
to 
RI-V4
A-V1
A-V2 A-V3
A-V4
A-V5 A-V6 A-V7 A-V8 A-V9 A-V10 A-V11 A-V12 A-V13
(Addi-
tional)
EOSA/
ED 
UnschV
28 (±3)
Days After 
Last IMP 
Dose
Up to 
28 days
D1A D1A 
+ 48 
to 96 
hours
D8
D15 D22 D22 
+ 48 
to 96 
hours
D29 D36
D43
D50
D57
D64
D71
D78
D85
Assessment/Procedure
±0 
days
±2 
days
±0 
days
±2 
days
±2 
days
±2 
days
±2 days
Blood sampling for PK 
and PD analysis
§
§
§
Two additional PK samples will be taken; ie, one sample 48 to 96 hours after the 1st IMP injection and one sample 48 to 96 hours after the 4th IMP injection in approximately 
10 Japanese patients in Stage A. Note that no additional PD samples will be taken at these timepoints.

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
159
11.14.4.
UK-Specific Protocol Requirements
The UK-specific requirements are summarized in the table below. Changes from the global 
protocol are indicated as follows: deleted text is indicated in strikethrough; a bold and underlined 
font is used to indicate added text. 
UK-specific Protocol Requirements
Section(s)
Change vs Global Protocol
Rationale
Section 5.2
In the PATH trial, the median time to relapse in the 
placebo arm was 3 to 4 months and at the end of the 24 
weeks of double-blind phase, 37% of placebo patients had 
not yet deteriorated based on the adjusted INCAT score. 
It is anticipated that efgartigimod may induce a greater 
reduction of autoantibodies. Therefore, sufficient time is 
required to allow enough cases of adjusted INCAT 
deteriorations (events) to occur for the primary efficacy 
analysis. For this reason, the double-blind phase (Stage B) 
is planned with a duration of 48 weeks. This duration will 
allow a potential longer carry-over effect from Stage A in 
addition to the median 3 to 4 months of relapse time 
observed in the placebo group in the PATH trial. The 
48-week duration is expected to allow the differences 
between active and placebo to become apparent. The 
current assumption is a 2-fold difference between time to 
deterioration of the two treatment groups. The trial is 
powered based on the number of events (88; see 
Section 10.3). The number of patients enrolled, the 
estimated relapse rate, and the duration of 48 weeks are 
expected to allow the sponsor to come to a satisfactory 
conclusion of the trial.
Based upon feedback of the 
MHRA, an explanation has been 
added for the duration of up to 
48 weeks for Stage B of the trial 
(with double-blind, randomized-
withdrawal treatment of 
efgartigimod PH20 SC or of 
placebo).
Section 8.2
Psychiatric conditions.
Note: In the case of severe depression, suicidal ideation, 
or attempted suicide, trial medication must be at least 
temporarily interrupted until the patient’s psychiatric 
condition has been fully evaluated. A by a psychiatrist 
should be consulted whenever necessary. Treatment may 
be resumed only when psychiatric condition has been 
excluded and after consultation with the sponsor’s 
agreement.
Based upon feedback of the 
MHRA, in case of possible 
depression, the trial medication 
will be discontinued, and the 
patient will be referred to 
psychiatrist before trial 
medication can be resumed.
Section 8.2, 
Section 8.3
Section 8.2 Permanent Early Discontinuation of IMP + 
Section 8.3 Early Withdrawal From the Trial; the 
following applies to both sections:
It is the investigator’s decision, and not the sponsor’s 
representative (eg, medical monitor or medical director) 
whether treatment and/or participation in the trial should 
continue or not if the treatment and/or trial
discontinuation criteria are fulfilled as required per 
protocol.
Based upon feedback of the 
MHRA, in alignment with GCP 
ICH guidance, the investigator 
is responsible for all trial-related 
medical decisions

Clinical Trial Protocol – Version 5.0 
12 Oct 2022 
Efgartigimod (ARGX-113) 
argenx
Confidential 
160
12.
REFERENCES
1. Hughes R, Dalakas M, Merkies I, et al. Oral fingolimod for chronic inflammatory 
demyelinating polyradiculoneuropathy (FORCIDP Trial): a double-blind, multicenter, 
randomized controlled trial. Lancet Neurol. 2018;17(8):689-698. 
2. EFNS Task Force. Members of the Task Force: Van den Bergh PYK, Hadden RDM, 
Bouche P, et al. European Federation of Neurological Societies/Peripheral Nerve Society 
(EFNS/PNS) guideline on management of chronic inflammatory demyelinating 
polyradiculoneuropathy: Report of a joint task force of the European Federation of 
Neurological Societies and the Peripheral Nerve Society — First Revision. Eur J Neurol.
2010;17:356-363. 
3. Gorson KC, van Schaik IN, Merkies ISJ, et al. Chronic inflammatory demyelinating 
polyneuropathy disease activity status: recommendations for clinical research standards 
and use in clinical practice. J Peripher Nerv Syst. 2010;15:326-333. 
4. Allen JA, Lewis RA. CIDP diagnostic pitfalls and perception of treatment benefit. 
Neurology. 2015;85:498-504. 
5. Lewis RA. Chronic inflammatory demyelinating polyneuropathy. Curr Opin Neurol.
2017;30(5):508-512. 
6. Laughlin RS, Dyck PJ, Melton LJ, et al. Incidence and prevalence of CIDP and the 
association of diabetes mellitus. Neurology. 2009;73(1):39-4. 
7. Mathey EK, Park SB, Hughes RAC, et al. Chronic inflammatory demyelinating 
polyradiculoneuropathy: from pathology to phenotype. J Neurol Neurosurg Psychiatry.
2015;86(9):973-985. 
8. Kieseier BC, Mathey EK, Sommer C, et al. Immune-mediated neuropathies. Nat Rev Dis 
Primers. 2018;4(1):31. 
9.
expression in patients with CIDP. Neurol Neuroimmunol Neuroinflamm. 2015;2(5):e148. 
10. Zinman LH, Sutton D, Ng E, Nwe P, Ngo M, Bril V. A pilot study to compare the use of 
the Excorim staphylococcal protein immunoadsorption system and IVIG in chronic 
inflammatory demyelinating polyneuropathy. Transfus Apher Sci. 2005;33(3):317-24. 
11. Devaux JJ, Odaka M, Yuki N. Nodal proteins are target antigens in Guillain-Barré 
syndrome. J Peripher Nerv Syst. 2012;17(1):62-71. 
12. Vaccaro C, Zhou J, Ober RJ, Ward ES. Engineering the Fc region of immunoglobulin G 
to modulate in vivo antibody levels. Nat Biotechnol. 2005;23(10):1283. 
13. Efgartigimod (ARGX-113) Investigator’s Brochure, version 10.0, November 2021. 
14. Recombinant Human Hyaluronidase PH20 (rHuPH20) Investigator’s Brochure, version 
10.0,February 2022. 
15. van Schaik IN, Bril V, van Geloven N, et al. Subcutaneous immunoglobulin for 
maintenance treatment in chronic inflammatory demyelinating polyneuropathy (PATH):