A Randomized, Double-blind, Placebo-controlled, Multicenter, Phase 3 Study to Evaluate the Efficacy and Safety of Izokibep in Subjects With Moderate to Severe Hidradenitis Suppurativa
Phase: PHASE3
Conditions: Hidradenitis Suppurativa
Sponsor: ACELYRIN Inc.

Protocol Number: 22107 
 
Official Title: A Randomized, Double-blind, Placebo-controlled, Multicenter, Phase 3 Study to 
Evaluate the Efficacy and Safety of Izokibep in Subjects with Moderate to Severe Hidradenitis 
Suppurativa 
 
NCT Number: NCT05905783 
 
Document Date: 14 May 2024 

CONFIDENTIAL 
ACELYRIN Izokibep Protocol 22107
 
Date: 10 May 2024 – Version 2.0
 
 
1 
Title Page 
Protocol Title: 
A Randomized, Double-blind, Placebo-controlled, Multicenter, Phase 3 Study to Evaluate 
the Efficacy and Safety of Izokibep in Subjects with Moderate to Severe Hidradenitis 
Suppurativa 
Protocol Number: 22107 
Protocol Version: 2.0 
Protocol Date: 10 May 2024 
Compound: Izokibep 
Brief Title: Hidradenitis Suppurativa Phase 3 Study of Izokibep 
Study Phase: 3 
Sponsor Name: ACELYRIN, INC. 
Legal Registered Address: 
4149 Liberty Canyon Rd. 
Agoura Hills, CA 91301 United States of America 
 
The medical monitor’s name and contact information will be provided separately. 
Regulatory Agency Identifier Number(s): 
Registry 
ID 
EU Clinical Trial Number 
2022-503160-33-00 
 
Previous version 
Date 
1.0 
24 March 2023 

CONFIDENTIAL 
ACELYRIN Izokibep Protocol 22107
 
Date: 10 May 2024 – Version 2.0
 
 
2 
Amendment 1 (10 May 2024) 
This amendment is substantial based on the criteria set forth in Article 10(a) of Directive 
2001/20/EC of the European Parliament and the Council of the European Union. 
Overall Rationale for the Amendment: 
The main purpose of this amendment is to update the timepoint for the primary and secondary 
endpoints, and improve the method of handling missing data for the primary and secondary 
endpoints. 
Summary of Changes 
Section # 
Description of Change 
Brief Rationale 
Title page 
Removed sponsor signatory. 
Sponsor approval is provided and maintained 
within the regulatory information management 
system. 
1.1 
Removed exploratory endpoints from the 
synopsis. 
To streamline the synopsis to include only critical 
information. 
1.1, 4.1, 4.1.3  
Revised description on the number of 
subjects to be enrolled for the study from 
approximate to planned. 
Change incorporated from country-specific 
protocol (CSP) Europe v.1.2 made in response to 
request from European Medicines Agency (EMA). 
1.1, 3, 4.1, 4.2, 
8.1.12, 9.1, 
9.1.1, 9.2, 
9.3.2, 9.3.3, 
9.4, 9.5 
Updated the timepoint for the primary 
and secondary objectives and endpoints 
from Week 16 to Week 12. 
This change was made to account for the 
unanticipated and historically high placebo 
response rates between weeks 12 and 16 and a 
high rate of dropouts among responders that was 
largely unrelated to safety observed in Phase 2b 
Study 21102. 
1.1, 4.1.1 
Updated frequency of data monitoring 
committee (DMC) meetings every 
6 months to more flexible language. 
Added flexibility to the frequency of DMC 
meetings, to allow for meetings less frequent than 
every 6 months. 
1.3 
Added visit windows to the table and 
made changes to the footnotes to reduce 
redundancy between footnotes and 
between the main body of the document. 
Clarity and readability. 
1.3, 8 
Updated maximum allowed window 
between dose from 10 days to 13 days. 
To correct a potential inconsistency for cases 
where +3-day windows are utilized on both sides 
of the weekly dose, resulting in 13 days between 
doses, rather than the previous 10 day maximum.   
1.3 
Added assessments to Week 12, 
including Hurley staging, 
electrocardiogram, optional 
photography, 12 Item Short Form 
Survey, urinalysis, fasting lipids, and 
hemoglobin A1C. 
To align with change of primary endpoint 
timepoint to Week 12. 
1.3 
Removed the Week 18 visit. 
To correct an error that was a carryover from the 
Phase 2 Study 21102 protocol. 
1.3 
Added collections of Hidradenitis 
Suppurativa -Patient Global Impression 
of Change (PGIC) at Week 24. 
Collection of PGIC at Week 24 is included in the 
exploratory endpoints but was inadvertently left 
out of the schedule of assessments. 

CONFIDENTIAL 
ACELYRIN Izokibep Protocol 22107
 
Date: 10 May 2024 – Version 2.0
 
 
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Section # 
Description of Change 
Brief Rationale 
2.2.3.3 
Added high-level safety data from 
Study 21102. 
New data became available after the primary 
analysis of Study 21102. 
2.2.3.2 
Added high-level efficacy data from 
Study 21102. 
New data became available after the primary 
analysis of Study 21102. 
2.3.2 
The benefit/risk assessment was updated 
to reflect the allowance of the use of a 
stable dose of oral antibiotics in up to 
30% of subjects enrolled and the 
rationale for the cap was added. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
3 
Updated the timepoint for the 
exploratory objectives and endpoints 
from Week 12 to Week 16. 
To align with primary and secondary endpoints 
and avoid duplication. 
3 
Added a Week 24 timepoint for the 
exploratory endpoints of the hidradenitis 
suppurativa clinical response (HiSCR) 
values (HiSCR50, HiSCR75, HiSCR90, 
and HiSCR100). 
Consistency with other exploratory endpoints. 
3 
Corrected exploratory endpoints for 
Numeric Rating Scale (NRS) Patient 
Global Assessment of Skin Pain. 
To capture the intended objectives/endpoints for 
assessment of change from baseline in both NRS 
Patient Global Assessment of Skin Pain questions: 
“In the last 24 hours, which number best describes 
your skin pain at its worst due to your HS?” and 
“In the last 24 hours, which number best describes 
your skin pain on average due to your HS?” 
3 
Updated estimands for the primary and 
secondary objectives. 
To clarify and align with the new missing data 
handling approach. 
Inclusion 
criterion 2 of 
Section 5.1 
Removed cap of ≤ 75 years of age by 
deleting inclusion criterion 2 and adding 
inclusion criterion 12. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
Inclusion 
criterion 7 of 
Section 5.1 
Added flexibility for the requirement of 
daily use of topical antiseptic to allow a 
minimum use of 3 days a week. 
Change incorporated from CSP Europe v.1.2 made 
in response to a request from EMA for consistency 
with Section 6.8.2.1. 
Inclusion 
criterion 9 of 
Section 5.1 
Added allowance of subjects with a 
known history of active tuberculosis 
(TB) if adequately treated according to 
World Health Organization/Center for 
Disease Control and Prevention 
therapeutic guidance and determined to 
be fully recovered by a TB specialist. 
To add flexibility to include subjects that had 
active TB in the past but were treated and no 
longer have active TB. 

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ACELYRIN Izokibep Protocol 22107
 
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Section # 
Description of Change 
Brief Rationale 
Inclusion 
criterion 10 of 
Section 5.1 and 
Section 8.2.8 
Clarified that for interferon-gamma 
release assay (IGRA) TB test 
(QuantiFERON recommended) 
indeterminate results, subjects are 
permitted to retest once. If the retest 
results are negative, the subject is 
eligible for the study. If the retest results 
are positive or remain indeterminate, the 
subject may not be randomized without 
further evaluation by a TB specialist and 
for positive IGRA TB test results, 
subjects may not be randomized without 
further evaluation by a TB specialist. 
To reduce confusion and provide clear instructions 
on how to handle various TB testing results. 
Exclusion 
criterion 13 of 
Section 5.2 
Updated timing of the chest x-ray 
requirement within 3 months of the first 
dose of study drug or screening to within 
3 months prior to screening. 
Previous language was ambiguous and could cause 
confusion if a subject’s chest x-ray was more than 
3 months prior to the first dose but less than 
3 months prior to screening. 
Exclusion 
criterion 26 of 
Section 5.2 
Reorganized for readability, content was 
maintained. 
Clarity. 
1.3, 3, 8.6, 
Table 5 of 
Section 10.2 
Specified that exploratory biomarker 
sampling and analysis applies to the 
United States only. 
Operational feasibility. 
6.1.1, 6.4, 
8.2.1.2 
Moved instructions for home dosing of 
study drug from 6.4 and 8.2.1.2 to 6.1.1. 
To include relevant information in the correct 
section. 
6.3.4 
Added clarification to allow investigator 
unblinding in response to urgent 
therapeutic intervention without 
notifying the medical monitor before the 
unblinding event, as long as the 
unblinding event is reported to the 
medical monitor within 1 business day. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
6.8.2.3 
Wording reorganized but content was 
maintained.  
To clarify how to manage subjects on non-opioid 
analgesic that is used for hidradenitis suppurativa 
(HS) pain (but not listed as one of the allowed HS 
pain medications) on a stable dose prior to 
enrollment. 
6.8.3 
Added exception that prescription 
topical corticosteroids can be used to 
treat localized erythema, edema, or 
pruritis at the injection site without 
medical monitor approval. 
To mitigate the symptoms of injection site 
reactions 
7.1 
Consolidated reasons for discontinuation 
of study drug. 
To reduce redundancy and better align with 
electronic data capture and clinical data 
interchange standards consortium allowable terms. 

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ACELYRIN Izokibep Protocol 22107
 
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Section # 
Description of Change 
Brief Rationale 
7.3 
Removed redundancy that if the subject 
continues to be unreachable, they will be 
considered withdrawn from the study 
and added that where permitted by local 
regulations and approved by Institutional 
Review Board/Independent Ethics 
Committee, third-party vendors may be 
employed by the site (funded by the 
sponsor) to assist the site in 
re-establishing contact. 
To reduce redundancy and improve 
discontinuation rates in the study. 
8.28 
Defined TB terms and clarified how to 
handle various IGRA TB test results.  
Clarity. 
8.3.6 
Clarified that major adverse 
cardiovascular and cerebrovascular 
events includes cerebrovascular accident 
and transient ischemic attack, non-fatal 
myocardial infarction or unstable angina, 
and cardiovascular death. 
Clarified that for infections, only those 
that are serious, opportunistic, or fungal 
are included as adverse events of 
interest. 
Improved the clarity of the definitions for events 
that qualify as adverse events of special interest. 
 
8.6 
Language updated to align with the 
informed consent form (ICF) regarding 
storing samples for future use and 
removed reference to a future use 
consent form. 
There is only a single ICF for this study, not a 
separate ICF for future use. 
9.2 
Added clarification to the analyses for 
the full analysis set and safety analysis 
set for timepoints after Week 16. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
9.3.1 
Added a statement that all hypothesis 
tests will use a type I error rate of 5%. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
9.3.1 
Clarified how safety and efficacy data 
after Week 16 will be summarized. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
9.3.2, 9.3.3 
Updated statistical analyses to use a 
multiple imputation method for the 
primary analysis of the primary and 
secondary endpoints in place of the 
non-response imputation analysis 
method for handling of dropouts and 
missing data. 
Following the primary analysis of Study 21102, 
ACELRYIN believes that the single imputation 
procedure of non-response imputation is 
potentially misleading and is not an appropriate 
approach for the primary analysis of Study 22107 
and that multiple imputation methods better 
represent missing data and can be appropriately 
used for the primary analysis of Study 22107. 
9.3.3 
Clarified that the imputation model for 
analyzing the secondary endpoint of 
experiencing flare will use baseline 
lesion counts, demographics (age, sex, 
race, stratification factors), and counts at 
prior post-randomization visits. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 

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ACELYRIN Izokibep Protocol 22107
 
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Section # 
Description of Change 
Brief Rationale 
9.4 
Added details for a potential futility 
assessment. 
To allow for a futility assessment and limit 
exposure to new subjects in the event that the 
efficacy results of izokibep are not positive. 
10.1.1 
Clarified that the study will be 
conducted in accordance with 21 Code 
of Federal Regulations and European 
Regulation 536/2014 for clinical studies. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
10.1.3 
Clarified that the ICF will meet the 
requirements of European Regulation 
536/20141. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
10.1.4 
Added data protection information. 
Change incorporated from CSP Europe v.1.2 made 
in response to request from EMA. 
10.3.5 
Added new section to provide a list of 
adverse events and laboratory 
abnormalities that could lead to 
discontinuation of study drug, including 
the addition of serious adverse event and 
common terminology criteria for adverse 
events version 5.0 grade 3 adverse event. 
Clarity and readability. New reasons for 
discontinuation of study drug incorporated from 
CSP Europe v.1.2 made in response to request 
from EMA. 
11 
Added references: Ali et al, 2020; 
Deckers and Prens, 2016; and Gulliver 
et al, 2016. 
New data were added to the clinical overview and 
benefit/risk sections, requiring additional 
references. 
Global 
Minor editorial and document formatting 
revisions. 
Administrative change. 
Global 
Version and date were revised on the 
title page and in the header throughout 
the document. 
Administrative change. 

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ACELYRIN Izokibep Protocol 22107
 
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Table of Contents 
 
Title Page ........................................................................................................................................1 
Table of Contents ...........................................................................................................................7 
List of Tables ................................................................................................................................11 
List of Figures ...............................................................................................................................11 
1. 
Protocol Summary ........................................................................................................12 
1.1. 
Synopsis ..........................................................................................................................12 
1.2. 
Schema ............................................................................................................................17 
1.3. 
Schedule of Activities .....................................................................................................18 
2. 
Introduction ...................................................................................................................21 
2.1. 
Study Rationale ...............................................................................................................21 
2.2. 
Background .....................................................................................................................21 
2.2.1. 
Disease Background........................................................................................................21 
2.2.2. 
Interleukin-17 ..................................................................................................................22 
2.2.3. 
Izokibep Background ......................................................................................................22 
2.3. 
Benefit/Risk Assessment ................................................................................................26 
2.3.1. 
Risk Assessment .............................................................................................................26 
2.3.2. 
Benefit Assessment .........................................................................................................27 
2.3.3. 
Overall Benefit-Risk Conclusion ....................................................................................28 
2.3.4. 
COVID-19 Benefit/Risk Assessment .............................................................................28 
3. 
Objectives, Endpoints, and Estimands .......................................................................30 
4. 
Study Design ..................................................................................................................37 
4.1. 
Overall Design ................................................................................................................37 
4.1.1. 
Independent Data Monitoring Committee ......................................................................37 
4.1.2. 
Number of Sites ..............................................................................................................38 
4.1.3. 
Number of Subjects.........................................................................................................38 
4.1.4. 
Study Duration for Subjects ............................................................................................38 
4.2. 
Scientific Rationale for Study Design ............................................................................38 
4.3. 
Justification for Dose ......................................................................................................39 
4.4. 
End of Study Definition ..................................................................................................40 
5. 
Study Population ...........................................................................................................41 
5.1. 
Inclusion Criteria ............................................................................................................41 
5.2. 
Exclusion Criteria ...........................................................................................................43 
5.3. 
Lifestyle Considerations .................................................................................................46 
5.4. 
Screen Failures ................................................................................................................46 
5.5. 
Criteria for Temporarily Delaying Dosing .....................................................................46 
5.6. 
COVID-19-related Precautions.......................................................................................47 
6. 
Study Drug(s) and Concomitant Therapy ..................................................................48 
6.1. 
Study Drug(s) Administered ...........................................................................................48 
6.1.1. 
Dosage, Administration, and Schedule ...........................................................................48 

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6.2. 
Preparation, Handling, Storage, and Accountability ......................................................49 
6.3. 
Measures to Minimize Bias: Randomization and Blinding ............................................49 
6.3.1. 
Subject Enrollment..........................................................................................................49 
6.3.2. 
Rescreening .....................................................................................................................50 
6.3.3. 
Treatment Assignment/Randomization ..........................................................................51 
6.3.4. 
Site Personnel Access to Individual Treatment Assignments.........................................51 
6.4. 
Study Drug Compliance..................................................................................................51 
6.5. 
Dose Modification ..........................................................................................................52 
6.6. 
Continued Access to Study Drug After the End of the Study ........................................52 
6.7. 
Overdose .........................................................................................................................52 
6.8. 
Prior and Concomitant Therapy ......................................................................................52 
6.8.1. 
Prior Therapies ................................................................................................................52 
6.8.2. 
Concomitant Therapies ...................................................................................................53 
6.8.3. 
Prohibited Medications ...................................................................................................55 
6.8.4. 
Rescue Medicine .............................................................................................................56 
7. 
Discontinuation of Study Drug and Subject 
Discontinuation/Withdrawal........................................................................................57 
7.1. 
Discontinuation of Study Drug .......................................................................................57 
7.1.1. 
Liver Chemistry Stopping Criteria ..................................................................................58 
7.1.2. 
Rechallenge .....................................................................................................................58 
7.2. 
Subject Discontinuation/Withdrawal from the Study .....................................................59 
7.3. 
Lost to Follow-up............................................................................................................60 
8. 
Study Assessments and Procedures.............................................................................61 
8.1. 
Efficacy Assessments .....................................................................................................61 
8.1.1. 
Hidradenitis Suppurativa Clinical Response ..................................................................61 
8.1.2. 
Lesion and AN Count .....................................................................................................62 
8.1.3. 
Hurley Stage....................................................................................................................62 
8.1.4. 
Numeric Rating Scale Patient Global Assessment of Skin Pain.....................................62 
8.1.5. 
Dermatology Life Quality Index .....................................................................................63 
8.1.6. 
Modified Sartorius Score ................................................................................................63 
8.1.7. 
International Hidradenitis Suppurativa Severity Score System ......................................63 
8.1.8. 
Hidradenitis Suppurativa-Physician’s Global Assessment .............................................63 
8.1.9. 
European Quality of Life-5 Dimensions .........................................................................64 
8.1.10. Short Form 12 .................................................................................................................64 
8.1.11. Hidradenitis Suppurativa Quality of Life .......................................................................64 
8.1.12. Hidradenitis Suppurativa Patient Global Impression of Change ....................................64 
8.1.13. Hospital Anxiety and Depression Scale ..........................................................................64 
8.1.14. Photography (Optional Substudy)...................................................................................65 
8.2. 
Safety Assessments .........................................................................................................65 
8.2.1. 
Medical and Medication History ....................................................................................65 
8.2.2. 
Physical Examinations ....................................................................................................65 
8.2.3. 
Vital Signs .......................................................................................................................65 
8.2.4. 
Physical Measurements ...................................................................................................66 
8.2.5. 
Electrocardiograms .........................................................................................................66 
8.2.6. 
Chest X-ray .....................................................................................................................66 

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8.2.7. 
Clinical Safety Laboratory Tests ....................................................................................66 
8.2.8. 
Tuberculosis Test ............................................................................................................66 
8.2.9. 
Pregnancy Testing ...........................................................................................................68 
8.2.10. IBD Screening .................................................................................................................69 
8.2.11. Suicidal Ideation and Behavior Risk Monitoring ...........................................................69 
8.2.12. Home Study Drug Administration Diary ........................................................................70 
8.3. 
Adverse Events, Serious Adverse Events, and Other Safety 
Reporting ........................................................................................................................70 
8.3.1. 
Time Period and Frequency for Collecting Adverse Event and 
Serious Adverse Event Information ................................................................................70 
8.3.2. 
Method of Detecting Adverse Events and Serious Adverse 
Events ..............................................................................................................................71 
8.3.3. 
Follow-up of Adverse Events and Serious Adverse Events ...........................................71 
8.3.4. 
Regulatory Reporting Requirements for Serious Adverse Events ..................................71 
8.3.5. 
Pregnancy ........................................................................................................................71 
8.3.6. 
Adverse Events of Special Interest .................................................................................72 
8.3.7. 
Overdose .........................................................................................................................72 
8.4. 
Pharmacokinetics ............................................................................................................73 
8.5. 
Genetics ..........................................................................................................................73 
8.6. 
Biomarkers (United States Only) ....................................................................................73 
8.7. 
Immunogenicity Assessments.........................................................................................74 
8.8. 
Health Economics ...........................................................................................................74 
9. 
Statistical Considerations .............................................................................................75 
9.1. 
Statistical Hypotheses .....................................................................................................75 
9.1.1. 
Multiplicity Adjustment and Type I Error Rate ..............................................................75 
9.2. 
Analysis Sets ...................................................................................................................76 
9.3. 
Statistical Analyses .........................................................................................................77 
9.3.1. 
General Considerations ...................................................................................................77 
9.3.2. 
Primary Endpoint and Estimand .....................................................................................78 
9.3.3. 
Secondary Endpoints and Estimands ..............................................................................78 
9.3.4. 
Exploratory Endpoints ....................................................................................................79 
9.3.5. 
Safety Analyses ...............................................................................................................79 
9.4. 
Interim Analysis and Early Stopping Rules ....................................................................80 
9.5. 
Sample Size Determination ..........................................................................................81 
10. 
Supporting Documentation and Operational Considerations ..................................82 
10.1. 
Regulatory, Ethical, and Study Oversight Considerations .............................................82 
10.1.1. Regulatory and Ethical Considerations ...........................................................................82 
10.1.2. Financial Disclosure........................................................................................................82 
10.1.3. Informed Consent Process ..............................................................................................83 
10.1.4. Data Protection................................................................................................................83 
10.1.5. Dissemination of Clinical Study Data.............................................................................84 
10.1.6. Monitoring and Data Quality Assurance ........................................................................85 
10.1.7. Source Documents ..........................................................................................................86 
10.1.8. Study and Site Start and Closure ....................................................................................86 
10.1.9. Publication Policy ...........................................................................................................87 

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10.2. 
Clinical Laboratory Tests................................................................................................88 
10.3. 
AEs and SAEs: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting ............................................................................90 
10.3.1. Definition of AE .............................................................................................................90 
10.3.2. Definition of SAE ...........................................................................................................91 
10.3.3. Recording and Follow-up of AE and/or SAE .................................................................92 
10.3.4. Reporting of SAEs ..........................................................................................................94 
10.3.5. AEs and Laboratory Abnormalities That Could Lead to 
Discontinuation of Study Drug .......................................................................................95 
10.4. 
Contraceptive and Barrier Guidance ...............................................................................96 
10.4.1. Definitions.......................................................................................................................96 
10.4.2. Contraception Requirements ...........................................................................................97 
10.5. 
Liver Safety: Required Actions and Follow-up Assessments ........................................99 
10.6. 
Abbreviations and Definitions ......................................................................................102 
11. 
References ....................................................................................................................104 
 

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ACELYRIN Izokibep Protocol 22107
 
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List of Tables 
Table 1-1. Schedule of Activities.................................................................................................. 18 
Table 4-1. Cmax and AUC0-τ at NOAEL in Cynomolgus Monkey Versus Predicted Exposure 
Levels in Humans and Respective Margins .................................................................................. 39 
Table 4-2. Predicted Exposure at Steady State for 160 mg Izokibep SC QW .............................. 40 
Table 6-1. Study Drug(s) Administered ........................................................................................ 48 
Table 8-1. Tuberculosis Terms and Definitions ........................................................................... 67 
Table 8-2. Tuberculosis Testing Results and Required Actions ................................................... 68 
Table 10-1. Protocol-required Safety Laboratory Tests ............................................................... 89 
 
List of Figures 
 
Figure 1. Study Design ................................................................................................................. 17 
Figure 2. Observed and Simulated PK Profiles for 10 mg/kg IV Q2W x 4 Secukinumab Versus 
Simulated Profiles for 160 mg Izokibep SC Q1W and Q2W ....................................................... 39 
Figure 3. Phase 2 Liver Chemistry Stopping Criteria and Increased Monitoring Algorithma ...... 58 
 
 

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ACELYRIN Izokibep Protocol 22107
 
Date: 10 May 2024 – Version 2.0
 
 
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Brief Summary 
The number of subjects planned to be enrolled is 250 (125 subjects per treatment group). 
Subjects will be screened within 28 days of study drug administration. Subjects meeting 
eligibility criteria will be randomized 1:1 to 1 of 2 treatment groups on Day 1, and will receive 
the following via subcutaneous injection: 
• Group 1 (n = 125): placebo every week (QW) from Day 1/Week 0 to Week 15, then 
izokibep 160 mg QW from Week 16 to Week 51. 
• Group 2 (n = 125): izokibep 160 mg QW from Day 1/Week 0 to Week 51. 
Randomization will be stratified by prior TNFi use for HS (Yes/No) and Hurley Stage (II or III). 
The AN count is the sum of abscesses and inflammatory nodules. Subjects enrolled with stable 
concomitant antibiotic use (dosing regimen has been stable for ≥ 4 weeks prior to first dose of 
study drug) will be capped at approximately 30%. 
Subjects will complete study assessments according to the study visits outlined in the schedule of 
activities (Section 1.3). The primary endpoint will be assessed at Week 12. The last dose of study 
drug will be administered on Week 51. 
An end of treatment visit will be conducted at Week 52 (± 5 days). A safety follow-up visit will 
be conducted at Week 59 (± 5 days). For subjects who early terminate, the end of treatment visit 
should be completed 1 week after last dose of study drug, and the safety follow-up visit should 
be completed 8 weeks after last dose of study drug (± 5 days), where possible. 
The final analysis of primary and secondary endpoints will be conducted after the last subject has 
had the opportunity to complete Week 12 assessments or early terminates from the study. 
Number of Subjects: 
The number of subjects planned to be enrolled is 250 (125 subjects per treatment group). 
Intervention Groups and Duration: 
• Group 1 (n = 125): placebo QW from Day 1/Week 0 to Week 15, then izokibep 160 mg 
QW from Week 16 to Week 51 
• Group 2 (n = 125): izokibep 160 mg QW from Day 1/Week 0 to Week 51 
Izokibep and matching placebo (collectively referred to as study drug) will be visually 
indistinguishable to prevent unblinding during preparation or administration of study material. 
Study drug doses are fixed and will not be adjusted for individual subjects during the study. 
Eligibility Criteria: 
Refer to Section 5 in Protocol. 

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Data Monitoring/Other Committee: 
An independent data monitoring committee (DMC) will be established to monitor data on an 
ongoing basis to ensure the continuing safety of the subjects enrolled in this study and to make 
recommendations on further development activities for izokibep. 
The DMC will consist of at least 1 medical expert with expertise in the relevant therapeutic area 
and at least 1 statistician and will have a minimum of 3 members, 1 of whom will serve as the 
Chair. The DMC responsibilities, members (including their qualifications and possible conflicts 
of interest), authorities, meeting frequency to review unblinded interim data, and procedures will 
be documented in the DMC charter. The committee will meet as needed to review significant 
safety findings. After each review, the DMC will make recommendations regarding the 
continuation of the study based on safety. The DMC will not be empowered to recommend 
stopping this study or changing the sample size due to a demonstration of positive efficacy. The 
study team operationalizing the day-to-day of the study, the subjects, and the investigators will 
remain blinded to these interim results until after the study is completed. 
Statistical Considerations 
Summaries of continuous variables will include mean, median, standard deviation, minimum, 
and maximum; change from baseline will additionally include standard error. Summaries of 
dichotomous, categorical, and ordinal variables will include counts and percentages. 
Baseline characteristics and demographics will be summarized by randomized treatment group 
using the last value obtained before randomization. Efficacy and safety data will be summarized 
by randomized treatment group during the first 16 weeks of treatment; these data will also be 
summarized by randomized treatment group over 52 weeks, and additionally over the last 
36 weeks for only the subjects who received placebo in the first 16 weeks and received at least 
1 dose of izokibep. Efficacy variables (primary, secondary, and exploratory) will be summarized 
at each planned collection timepoint. Incidence of treatment-emergent adverse events (TEAEs) 
and serious adverse events (SAEs; percent of subjects reporting each TEAE and each SAE) will 
be summarized. Anti-drug antibodies (ADAs) will be summarized at each planned collection 
timepoint. 
Comparisons of efficacy will test izokibep versus placebo in a single analysis. Response rates 
will be compared with a stratified test for differences: the strata used for randomization (prior 
TNFi use for HS [Yes/No] and Hurley Stage [II or III]), using Cochran-Mantel-Haenszel 
weights. The p-values for comparing izokibep versus placebo will be reported, with a 2-sided 
95% confidence interval on the difference in response rates. Continuous endpoints will be 
analyzed with a longitudinal model using values at each post-randomization timepoint. 
The primary efficacy comparison will be of hidradenitis suppurativa clinical response 
(HiSCR75), which is a 75% reduction in AN count with no increase in the number of abscesses 
or the number of draining fistulae. The AN count is the sum of the number of abscesses and the 
number of inflammatory nodules. Testing will be reported at α = 0.05, 2-sided. 
Secondary endpoints will be tested analogously. The sequence will consider the secondary 
endpoints in a pre-specified order, comparing izokibep to placebo. If all prior tests showed 
statistically significant differences compared with placebo, testing will proceed using α = 0.05. If 

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any comparison (primary or secondary) results in p > 0.05, p-values for subsequent comparisons 
will be reported but not considered conclusive. 
Exploratory endpoints will be compared analogously, with the exception of a pre-specified 
alpha-controlling testing strategy. The p-values for exploratory endpoints will be considered 
descriptive and not considered conclusive. The primary efficacy analyses will use the treatment 
policy estimands except as noted, using all available data from all randomized subjects 
regardless of treatment compliance. Subjects will be analyzed in the group to which they are 
randomized. Subjects who do not have an evaluation for a dichotomous endpoint at a given 
timepoint will be imputed as non-responders or imputed with multiple imputation. Subjects who 
do not have a continuous measure at a given timepoint will have available data at other 
timepoints included in the longitudinal model, resulting in an analysis that is robust to data that 
are missing at random or missing completely at random. Sensitivity and supplementary analyses 
will be used to assess the impact of missing data assumptions. 
Incidence of TEAEs over the first 12 weeks will be summarized by treatment group. No p-values 
will be reported. Incidence will also be summarized over all 52 weeks for subjects who received 
izokibep in the first 16 weeks and summarized over the last 40 weeks for subjects who received 
placebo for the first 16 weeks (and received at least 1 dose of izokibep after 16 weeks of 
placebo). Serious adverse events will be summarized analogously. Subjects will be summarized 
for safety according to the treatment they actually received. 
Available pharmacokinetic data will be summarized by dose group of izokibep. 
Incidence of ADAs at any time will be summarized by treatment group and overall. 
At Week 12, HiSCR75 response rates are expected to be 15% for placebo and 35% for izokibep. 
With 125 subjects receiving placebo and 125 subjects receiving izokibep, this study will have 
95% power for the true difference in HiSCR75 response rates of 20 percentage points. 

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1.2. 
Schema 
Figure 1. Study Design 
 
 
EOS = end of study; EOT = end of treatment; QW = every week 
a Randomization will be stratified by any prior TNFi use for hidradenitis suppurativa (Yes/No) and Hurley Stage (II or III). 
b Subjects in Group 1 (placebo QW) will receive placebo QW until Week 15, then izokibep QW beginning at Week 16 until Week 51. 
Subjects in Group 2 (izokibep QW) will receive izokibep QW. 
c An ‘end of treatment visit’ will be conducted at Week 52 (± 5 days). A ‘safety follow-up visit’ will be conducted at Week 59 (± 5 days). 
For subjects who early terminate, the end of treatment visit should be completed 1 week after the last dose of study drug and safety 
follow-up visit completed 8 weeks after the last dose of study drug (± 5 days), where possible. 

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ADA = anti-drug antibody; AE = adverse event; AN = abscess and inflammatory nodule; CRF = case report form; C-SSRS = Columbia-Suicide Severity Rating Scale; d = day; 
DLQI = Dermatology Life Quality Index; ECG = electrocardiogram; EOS = end of study; EOT = end of treatment; EQ-5D = European Quality of Life 5-dimension; ET = early 
termination; HADS = Hospital Anxiety and Depression Scale; HBV = Hepatitis B virus; HCV = Hepatitis C virus; HiSQOL = Hidradenitis Suppurativa Quality of Life; 
HIV = human immunodeficiency virus; HS-PGA = Hidradenitis Suppurativa-Physician’s Global Assessment; HS-PGIC = Hidradenitis Suppurativa Patient Global Impression of 
Change; IGRA = interferon-gamma release assay; NRS = Numeric Rating Scale; PK = pharmacokinetic; SAE = serious adverse event; SF-12 = 12-Item Short Form Survey; 
TB = tuberculosis; US = United States; WOCBP = women of childbearing potential. 
a Visit/dosing windows of ± 3 days on either side of the scheduled visits/dosing are permitted; however, the investigator should try to keep the subjects on the original visit/dosing 
schedule. In case of a delayed or missed dose, the investigator should return subjects on the original visit/dosing schedule in relation to Day 1 for subsequent doses. The window of 
± 3 days is relative to Day 1 and applicable for all subsequent visits/dosing. The time between doses should be no less than 4 days and no more than 13 days. 
b The EOT visit will be completed at Week 52 (± 5 days) and safety follow-up visit completed at Week 59 (± 5 days). For subjects who early terminate, these visits should be 
completed 1 week (± 5 days) and 8 weeks (± 5 days) after the last dose of study drug. 
c Vital signs include measurements of temperature, respiratory rate, systolic and diastolic blood pressure, and pulse. 
d Chest x-ray (posterior/anterior or anterior/posterior) will be performed at screening only for subjects who do not have a chest x-ray available within 3 months prior to screening. 
Women of childbearing potential must have a negative pregnancy test before x-ray is performed. 
e The ‘Baseline/Screening’ version of the C-SSRS will be conducted during the screening visit and the ‘Since Last Visit’ version of the C-SSRS will be completed at all other 
timepoints. 
f Serious AEs will be recorded from the signing of informed consent through the 8-week follow-up visit (ie, 8 weeks after the last dose of study drug); AEs will be recorded from 
Day 1 (ie, administration of study drug) until 4 weeks after the last dose of study drug. 
g Confirm ongoing antiseptic wash requirement at every visit. From screening through Week 16, subjects will complete a daily diary of their analgesic use. For Week 17 through 
Week 52 subjects will be required to tell site staff if they took any analgesics within 24 hours of their site visit. Subjects will refrain from taking analgesics 12 hours before the site 
visit, if possible. 
h Lesion count must address all relevant anatomical regions in each subject. The AN count is the sum of abscesses and inflammatory nodules. Any unscheduled visit for disease 
worsening based on the investigator judgment will include AN count and will be recorded in the appropriate CRF. 
i From screening through Week 16, subjects will complete a daily diary of their skin pain at home. For Week 17 through Week 32 and Week 52 visits, subjects will complete a 
single skin pain assessment at the site. Note: Subject may not be randomized if pain diaries are not completed for ≥ 3 out of 7 days (at a minimum) prior to the Day 1 visit. 
j For subjects who consent to the optional photography substudy at selected sites, photographs will be taken. 
k IGRA TB test (QuantiFERON recommended) will be performed. Note: See Table 8-2 for guidance for handling various TB test results. 
l Serum pregnancy test required for screening and urine pregnancy test required at all other visits for WOCBP. Local authorities may require more frequent pregnancy testing. 
m Fecal calprotectin at screening only required if subject has a) prolonged or recurrent diarrhea b) prolonged or recurrent abdominal pain or c) blood in stool. 
n Administration of study drug should be done last after all study procedures unless indicated otherwise. 
o After Week 4, qualified subjects may perform home dosing of study drug at weeks without study visits (starting from Week 5) and do not need to return to the clinical site on 
those weeks. For example, prior to commencing study drug self-administration at home at Week 5, at the Day 1/Week 0, Week 1, and Week 2 site visits, site staff will administer 
study drug to the subject, and will train the subject on study drug handling, dose preparation, and self-administration of the study drug. At the Week 3 and 4 site visits, the subject 
will demonstrate their ability to self-administer study drug prior to the site allowing them to start home dosing at Week 5. Otherwise, the subject will need to return to the site for 
all injections. The last dose of study drug is Week 51. 
p Subjects will be monitored at the site for at least 1 hour after study drug administration. 
q A dosing diary will be completed for every home dosing administration. 

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2. 
Introduction 
Izokibep is a potent and selective inhibitor of interleukin (IL)-17A that is being developed for the 
treatment of hidradenitis suppurativa (HS). 
2.1. 
Study Rationale 
Izokibep is a small protein molecule that acts as a selective, potent inhibitor of IL-17A, to which 
it binds with high affinity. Izokibep has been investigated in non-clinical and clinical studies in 
healthy subjects, and subjects with HS. The clinical development plan also includes axial 
spondyloarthritis, uveitis, psoriasis, and psoriatic arthritis (PsA). This study investigates izokibep 
in subjects with active HS, including tumor necrosis factor-alpha inhibitor (TNFi) naïve subjects, 
and those who had an inadequate response or intolerance to TNFi, or for whom TNFi is 
contraindicated. The study is intended to be 1 of 2 adequate and well-controlled studies to 
support a claim of efficacy of izokibep in subjects with HS. 
2.2. 
Background 
2.2.1. 
Disease Background 
Hidradenitis suppurativa is a chronic inflammatory skin disease characterized by occlusion of 
hair follicles as a primary pathogenic factor associated with a chronic cycle of inflammation, 
healing, and scarring (Sabat et al, 2020). A recent meta-regression analysis found an overall HS 
prevalence of 0.40% (95% confidence interval [CI]: 0.26% to 0.63%) among the populations 
studied around the world (Jfri et al, 2021). In a population-based analysis, the overall point 
prevalence of HS in the United States (US) was 0.10%, or 98 per 100 000 persons. Prevalence 
was highest among women (137 per 100 000), those aged 30 to 39 years (172 per 100 000), and 
African American (296 per 100 000) and biracial (218 per 100 000) patient groups (Garg et al, 
2017). Patients with HS develop painful inflamed nodules, abscesses, and pus-discharging tracts 
and fistulas, which typically occur in skin folds of axillary (armpits), inguinal (groin), gluteal, 
and perianal areas of the body. Hidradenitis suppurativa causes severe pain, purulent secretions 
that smell bad, and movement restrictions that have a profound negative influence on patients’ 
lives (Sabat et al, 2020). 
A genetic predisposition, smoking, obesity, and hormonal factors are established etiological 
factors for HS (Sabat et al, 2020). Cutaneous changes begin around hair follicles and involve 
activation of cells of the innate and adaptive immune systems, with pivotal roles for 
proinflammatory cytokines such as tumor necrosis factor-α (TNF-α), IL-1β, and IL-17 
(Sabat et al, 2020). 
Clinical management of HS is challenging and consists of both medical and surgical approaches. 
Topical therapies, systemic antibiotics, hormonal therapies, and immunosuppressant medications 
have been used. However, there are patients where HS remains resistant to conventional 
treatment particularly those with moderate to severe disease (Alikhan et al, 2019). The TNFi, 
adalimumab is currently the only approved biologic immunomodulator by the US Food and Drug 
Administration for treating moderate to severe HS (HUMIRA® USPI 2021) Only around 50% of 
subjects achieved a clinical response at Week 12 in the 2 randomized, double-blind, 

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placebo-controlled studies of adalimumab in a total of 633 adult subjects with moderate to severe 
HS. During the second part of both studies (up to 36-week treatment duration), approximately 
40% of subjects who initially responded to adalimumab weekly therapy continued to benefit 
from this drug (Kimball et al, 2016). 
In summary, there continues to be a significant unmet medical need for additional therapies to 
treat patients with HS. Additional therapies are needed to manage pain, abscess formation, and 
disease progression. In addition, given the significant reduction in quality of life and functional 
impairment experienced by patients diagnosed with HS, there is an unmet need for medical 
therapies that can have a substantial impact on improving a patient’s quality of life. 
2.2.2. 
 Interleukin-17 
A broad range of immune mediators are highly expressed in established HS lesions compared 
with healthy control skin. Patients with HS have imbalances in the T-helper 17 cell (Th17) axis 
that are similar to those in patients with psoriasis (Wolk et al, 2020). They have high serum 
levels of the proinflammatory cytokine IL-17A, which leads to neutrophil recruitment and 
provides positive feedback to maintain the population of proinflammatory Th17 cells 
(Matusiak et al, 2017). These imbalances improved in patients treated with TNFi. It is 
hypothesized that by reducing circulating IL-17A, anti-IL-17A inhibitors like izokibep may also 
provide benefit for patients with HS. Clinical evidence for this benefit comes from 2 open-label 
studies with secukinumab 300 mg and brodalumab 270 mg, where 70% of 20 subjects and 100% 
of 10 subjects, respectively, responded at 24 weeks based on the hidradenitis suppurativa clinical 
response (HiSCR) (Casseres et al, 2020; Frew et al, 2020). In addition, bimekizumab 320 mg 
dosed every 2 weeks appeared to deliver greater efficacy than adalimumab dosed based on the 
prescribing information, at 12 weeks based on the HiSCR75 and HiSCR90 responses (Glatt et al, 
2021). Phase 3 studies in subjects with HS for secukinumab and bimekizumab are underway. 
2.2.3. 
Izokibep Background 
Izokibep is a biologic that binds IL-17A with high affinity and with a potency corresponding to 
clinically tested monoclonal antibodies in terms of blocking the biological activity of IL-17A. 
Izokibep has the potential to be an efficacious treatment for a variety of IL-17A-related diseases. 
The smaller size of izokibep compared with monoclonal antibodies offers advantages in terms of 
required dosing volumes and potential for alternative pharmacological formulations. 
Izokibep is based on a small protein binding to and blocking the biological effect of the cytokine 
IL-17A. The izokibep protein molecule also contains an albumin-binding domain, which confers 
specific binding to a single site on endogenous serum albumin and thereby a prolonged half-life 
(t½) in the circulation and in tissues after parenteral administration. 
IL-17 inhibitors have already demonstrated efficacy and a favorable safety profile in different 
inflammatory diseases, including psoriasis and PsA. These include secukinumab (Cosentyx®) 
and ixekizumab (Taltz®) in the US, Canada, and the European Union. 
Doses up to 160 mg every other week (Q2W) have been tested and were well tolerated. A 
detailed description of the chemistry, pharmacology, efficacy, and safety of izokibep is provided 
in the Investigator’s Brochure. 

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2.2.3.1. 
Non-clinical Studies 
Assessments of target binding specificity have demonstrated high specificity and affinity of 
izokibep to IL-17A and to albumin. The in vitro and in vivo pharmacodynamics evaluations 
show that izokibep has a 3- to 5-fold higher potency than the anti-IL-17A monoclonal antibody 
secukinumab on a molar basis and appears to be approximately equipotent to ixekizumab. 
Pharmacokinetic (PK) data for intravenous (IV)- and subcutaneous (SC)-administered izokibep 
have been obtained in rat and monkey. Pharmacokinetic assessments in rat and monkey indicate 
that the time course of izokibep concentrations after a bolus IV injection and SC injection is well 
described by a 2- or 3-compartment model. Pharmacokinetic assessments indicate that the 
elimination rate of izokibep is similar to that of albumin in the respective species. 
Repeated (10-day to 3-month) SC or IV administration of izokibep to cynomolgus monkeys was 
well tolerated with no observed adverse effect levels (NOAELs) of 40 mg/kg/dose (IV, 28-day 
study) and 20 mg/dose (SC, 28-day) and 20 mg/kg/week (SC, 3-month study), being the highest 
dose levels tested in the respective studies. 
In the 26-week repeated-dose toxicity study in cynomolgus monkeys, weekly SC injection of 10, 
20, or 40 mg/kg/week izokibep to monkeys for 26 weeks was generally well tolerated. 
However, due to the presence of local abscesses and systemic sequelae in 1 female administered 
40 mg/kg/week, which was considered adverse, the NOAEL for SC administration is considered 
to be 20 mg/kg/week. 
In the enhanced pre- and post-natal developmental toxicity study in cynomolgus monkeys, SC 
izokibep administration of up to 40 mg/kg/week to pregnant monkeys for approximately 
21 weeks was well tolerated. The NOAEL was 40 mg/kg/week. 
The results from the immunotoxicity screening assays do not suggest that izokibep has an 
intrinsic capacity for immune system activation. 
Metabolism and genotoxicity have not been investigated, since izokibep is a protein molecule 
and contains only naturally occurring amino acids. 
For additional information, please refer to the Investigator’s Brochure. 
2.2.3.2. 
Clinical Overview 
A first-in-human multipart clinical study (Study ABY-035-001, EudraCT number 
2015-004531-13, NCT02690142) has been conducted with the parenteral formulation of 
izokibep. Izokibep was administered IV and SC to healthy subjects and subjects with plaque 
psoriasis, in doses ranging from 2 mg to 40 mg in a single- or multiple-dose regimen. 
A Phase 2 dose-finding study in subjects with moderate to severe plaque psoriasis was recently 
completed with up to 3 years of exposure (Study ABY-035-002, EudraCT number 
2017-001615-36, NCT03591887). One hundred eight subjects were randomized into 5 dose 
groups: 2 mg, 20 mg, 80 mg, and 160 mg izokibep or placebo. The treatment period consisted of 
an induction period (12 weeks), an optimization period (12 weeks), and an individualization 

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period including 4 weeks follow-up (28 weeks), and 2 further years of extension. The induction 
period was double blind and placebo controlled. 
The primary endpoint of the study was the proportion of subjects who achieved a Psoriasis Area 
and Severity Index (PASI) response of 90% (PASI90) after 12 weeks of treatment. The PASI90 
at 12 weeks was 71.4% and 59.1% in subjects treated with 80 mg and 160 mg Q2W of izokibep, 
respectively. In the lower dose groups, 2 mg and 20 mg izokibep, only 5.0% and 19.0% of 
subjects, respectively, reached the primary endpoint. None of the subjects receiving placebo 
reached PASI90 response at Week 12. At Week 24, PASI90 responses were comparable between 
the initial 80 mg and 160 mg treatment groups. The safety and efficacy data obtained from the 
52-week core period of the study with izokibep suggest a favorable benefit-risk profile in plaque 
psoriasis. 
A Phase 2 clinical study in subjects with active PsA has recently been completed 
(Study ABY-035-202). Study ABY-035-202 is a dose-finding study of 40 mg or 80 mg izokibep 
or placebo SC Q2W. The primary endpoint was the ACR 50% (ACR50) response at Week 16; 
further key secondary endpoints comprise other ACR responses, PASI scores, enthesitis 
endpoints, proportion of subjects achieving minimal disease activity, adverse events (AEs; 
safety), and izokibep blood levels (PK), and anti-drug antibody (ADA) assessments. 
The primary endpoint of ACR50 at 16 weeks was met with 52% response rate in subjects 
receiving 80 mg Q2W of izokibep versus 13% for placebo (p-value = 0.0006). Subjects receiving 
40 mg Q2W had an ACR50 response rate of 48%. The PASI response of 75%, in subjects with a 
minimum psoriasis body surface area ≥ 3% at baseline, at 16 weeks was 85% and 83% in 
subjects treated with 80 mg and 40 mg Q2W, respectively versus 14% for those receiving 
placebo. In subjects with enthesitis at baseline utilizing the Leeds Enthesitis Index, resolution of 
enthesitis was achieved by 88% of subjects receiving 80 mg Q2W, 63% of subjects receiving 
40 mg Q2W of izokibep, and 10% receiving placebo. 
Recent data from the primary analysis of the ongoing Phase 2b Study 21102 in subjects with 
moderate to severe HS showed early HiSCR100 responses in nearly 30% of subjects, consistency 
in directionality of the data for both izokibep doses (160 mg QW and 160 mg Q2W) compared 
with placebo, a consistent dose effect as seen with HiSCR responses favoring a 160 mg every 
week (QW) dose and aligned with dose-response analyses, and no evidence of safety or 
tolerability limitations. However, the primary endpoint of HiSCR75 at week 16 did not meet 
statistical significance. Assessment of the data determined that the lack of significance was 
primarily due to 2 factors: 1) unanticipated, historically high placebo (41% HiSCR50) response 
rates compared with 10% to 30% placebo response rates in previous HS studies (Ali et al, 2020), 
and 2) high drop-out rates among 160 mg QW HiSCR responders that were largely not related to 
safety but imputed as non-responders in the primary analysis. 
2.2.3.3. 
Safety Overview 
In the first-in-human study in healthy subjects and subjects with psoriasis (Study ABY-035-001), 
doses of up to 40 mg IV and SC of izokibep (n = 62) were well tolerated, with no deaths or 
treatment-related serious AEs (SAEs). Intravenous administration (single doses up to 40 mg in 
46 subjects in total) resulted in the following treatment-emergent AEs (TEAEs) by preferred 
term: oropharyngeal pain (10.9%), nasopharyngitis (6.5%), diarrhea (4.3%), and headache 

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(4.3%). A further 9 TEAEs were reported, which affected 1 subject each (2.2% each). 
Subcutaneous administration (single and multiple doses up to 40 mg in 21 subjects in total) 
resulted in the following TEAEs by preferred term: injection site reaction (61.9%) and injection 
site pain (28.6%). A further 11 TEAEs were reported, which affected 1 subject each (5.2% each). 
The majority of the injection site reactions (ISR)s were of mild intensity and required no 
treatment or limited therapy. 
In the Phase 2, 52-week core period in subjects with plaque psoriasis (ABY-035-002), multiple 
doses of up to 160 mg Q2W SC of izokibep (n = 108) were well tolerated with no deaths or 
treatment-related SAEs. A total of 65 subjects (60.2%) experienced at least 1 izokibep-related 
TEAE. The most common izokibep-related TEAEs (n/%) were ISR (42/38.9%), nasopharyngitis 
(13/12.0%), diarrhea (7/6.5%) and fatigue (6/5.6%) consistent with the first-in-human study. 
In the Phase 2, randomized, double-blind, placebo-controlled clinical study in subjects with 
active PsA (ABY-035-202), doses of 40 mg and 80 mg Q2W were well tolerated. Safety 
evaluation showed no serious or severe AEs up to Week 16. Treatment-emergent AE rate overall 
was 52.3% for placebo, 65.9% for 40 mg Q2W and 55.3% for 80 mg Q2W. The most common 
AEs (≥ 5% in either arm with active treatment) were ISR or erythema, headache, hyperkalemia, 
and upper respiratory tract infection. Three subjects had AEs of special interest: 2 subjects 
experienced ISR and 1 subject experienced vulvovaginal candidiasis. 
In the primary analysis from part A (Week 12) of the ongoing Phase 2b Study 21102 in subjects 
with moderate to severe HS, a total of 24 (80%) subjects experienced at least 1 TEAE during the 
study. Mild-to-moderate ISRs, injection site pruritus, and injection site erythema were the most 
common AEs. Three serious adverse events (SAEs) were reported in 2 subjects: Crohn’s disease 
(1 subject) and colonic abscess/sepsis in another subject with known diverticulosis. No candida 
infections were reported during the first 12 weeks of part A. 
In the primary analysis from part B (Week 16) of Study 21102, a total 135 of (77.1%) subjects 
experienced at least 1 TEAE during the study. The most common (> 5%) AEs were injection site 
erythema and injection site pruritus. A total of 7 SAEs occurred in 5 subjects. An event of 
Epstein-Barr (mononucleosis) virus infection was the only SAE considered possibly related to 
study drug by the investigator; this event was considered resolved and the subject resumed 
therapy and remained in the study. The other SAEs included arthritis, cutaneous vasculitis, 
elevated liver enzymes, scrotal abscess, staphylococcal wound infection, and sepsis, which 
affected 1 subject each. None of these events were considered related to study drug by the 
investigators. No deaths occurred during the study. Five events of candida, all mild, were 
reported. There were no reports of inflammatory bowel disease (IBD). 
For more details on the safety and tolerability of izokibep, refer to the Investigator’s Brochure. 
2.2.3.4. 
Pharmacokinetics 
Following SC administration of single izokibep doses in the first-in-human study 
(Study ABY-035-001), median time to maximum observed concentration (tmax) was 60 hours 
post-dose. After reaching maximum observed plasma concentration (Cmax), plasma levels of 
izokibep declined in an apparent mono- or bi-phasic manner with the geometric mean t½ being 
278 hours, which was similar to that after IV administration (288 hours). Individual t½ estimates 

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ranged from 199 to 464 hours and 220 to 340 hours for SC and IV treatments, respectively. In 
general, as assessed by the geometric percent coefficient of variation (CV%) low 
between-subject variability was noted for area under the concentration-time curve (AUC) 
extrapolated to infinity (AUC0-∞) and Cmax for both dose routes, with values ranging from 20% to 
22% and 14% to 15%, respectively. 
Following 40 mg repeated SC doses, Cmax occurred at a median tmax of 48.0 hours post-dose on 
Days 1 and 29 (individual range: 24.0 to 71.0 hours post-dose). On Day 85, median tmax was 
slightly later at 71.6 hours post-dose (individual range: 66.6 to 73.1 hours post-dose). After 
reaching Cmax on Day 85, plasma concentrations of izokibep declined in an apparent mono- or 
bi-phasic manner with a geometric mean t½ of 279 hours with individual subjects ranging from 
229 to 423 hours. Pre-dose trough izokibep plasma concentrations showed that steady state was 
achieved by Day 71, following 5 doses of izokibep administered Q2W. There was evidence of 
accumulation following repeated dosing by Day 85 with geometric mean accumulation ratio, 
based on AUC over a dosing interval (AUC0-τ), of 1.95, and individual subjects ranging from 
1.35 to 5.09. Between-subject variability, based on geometric CV%, was moderate on the 
monitored study days for AUC0-τ with values ranging from 29.4% to 36.0%, and 
low-to-moderate for Cmax with values ranging from 20.4% to 28.8%. 
For more details on the PK of izokibep, refer to the Investigator’s Brochure. 
2.3. 
Benefit/Risk Assessment 
More detailed information about the known and expected benefits and risks and reasonably 
expected AEs of izokibep may be found in the Investigator’s Brochure. 
2.3.1. 
Risk Assessment 
Izokibep is a biologic that binds IL-17A with high affinity and with a potency corresponding to 
clinically tested monoclonal antibodies in terms of blocking the biological activity of IL-17A. 
• IL-17A inhibitors, including secukinumab at 10 mg/kg and 30 mg/kg and ixekizumab as 
well as izokibep at doses up to 160 mg SC, do not appear to have dose-limiting AEs. 
• Class effects and potential risks seen with other IL-17 inhibitors have not been identified 
with izokibep. Given small numbers of subjects treated to date, class effects and potential 
risks of IL-17 inhibitors will be explicitly monitored (ie, events of special interest) and 
have been taken into consideration in the development of inclusion and exclusion criteria. 
These events include candida infections, IBD, and suicidal ideation and behavior risk 
monitoring. 
• Non-serious, mild-to-moderate ISRs are the most common AE reported in association 
with SC administration of izokibep. These are typically self-resolving, however 
additional measures to mitigate/manage ISRs include the following: 
o Allow study drug to warm to room temp prior to administration, about 15 to 
20 minutes. 
o Administer study drug slowly. 
o Use ice/ice packs following study drug administration. 
o Rotate sites of administration; avoid injecting the same site twice during any visit. 

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o Use of oral antihistamines. 
o Use of acetaminophen or ibuprofen for pain or discomfort. 
o Topical corticosteroids may be used for localized erythema, edema, or pruritis. 
• No genotoxicity or carcinogenicity is foreseen as izokibep is a protein consisting of 
natural amino acids. However, since no data are available at this stage of clinical 
development on possible effects on the reproductive system, the following precautionary 
measure will be taken: 
o Females of childbearing potential as well as reproductive female partners of male 
subjects must use an adequate method of contraception while participating in the 
clinical study until at least 8 weeks after the last dose of study drug. Pregnancy 
testing will be performed at regular intervals prior to, during treatment, and after 
the end of treatment (ie, 8 weeks after the last investigational medicinal product 
[IMP] dosing). 
2.3.2. 
Benefit Assessment 
The potential benefit of izokibep is that it is designed to demonstrate whether treatment is 
associated with a reduction in the extent of inflammation in patients with moderate to severe HS, 
manifested as a specific reduction in the number of inflammatory nodules and abscesses. As 
these inflammatory lesions are associated with considerable pain and impairment in quality of 
life, a reduction in the number of such lesions could directly benefit patients. 
Safety, efficacy, and PK data obtained in clinical studies with izokibep in healthy volunteers and 
in subjects with psoriasis, PsA, and HS suggest a favorable benefit-risk profile. Based on 
published data showing efficacy and safety for other IL-17 inhibitors, including in patients with 
HS, the benefit-risk relationship appears favorable and justifies clinical development of izokibep 
in HS as well. Due to its small molecular size as compared with monoclonal antibodies and its 
binding to albumin, izokibep may have the potential to better reach inflamed tissues and may 
provide higher exposure relative to monoclonal antibodies. 
A 16-week, placebo-controlled period does not entail any additional risk of irreversible harm to 
subjects. Although there is no active comparator in Study 22107, the use of tetracyclines is in 
line with evidence-based treatment of HS (Gulliver et al, 2016; Deckers and Prens, 2016). The 
study permits concomitant use of oral antibiotic therapy (eg, minocycline or doxycycline) for the 
treatment of HS provided the dosing regimen (dose and frequency) has been stable for 
≥ 4 consecutive weeks prior to the first dose of study drug and remains stable throughout the 
placebo-controlled period (Week 16 assessment). Specified analgesics are permitted for 
HS-associated pain. The study also requires that subjects use daily or at a minimum of 3 days a 
week topical antiseptic on areas of their body affected with HS lesions, throughout the duration 
of the study. For subjects with increases in abscess and inflammatory nodule (AN) counts 
(≥ 150% of Day 1 AN count), investigators may provide permitted antibiotic rescue therapy. 
Additionally, subjects with a draining fistula count > 20 at screening or Day 1 are excluded from 
enrolling in the study to exclude the most severe forms of the disease that may place subjects at a 
higher risk of disease-related complications. The implementation of these measures will prevent 
any irreversible harm to subjects particularly in the 16-week placebo-controlled period, therefore 
allowing the ability to adequately assess efficacy and safety of izokibep when compared with 
placebo. 

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Given the value in assessing the effect of study drug on a wide variety of subgroups in the target 
patient population, including subjects on chronic antibiotic treatment (as one of those 
subgroups), the study will permit enrollment of subjects with stable concomitant antibiotic use, 
as described above. Enrollment of subjects with stable concomitant antibiotic use will be capped 
at approximately 30%, which is considered a low enough proportion to not confound efficacy 
analysis outcomes. 
The investigator is referred to the current Investigator's Brochure where additional and more 
detailed information (including non-clinical toxicology, metabolism, pharmacology, and safety 
experience) regarding potential risks and benefits of izokibep can be found. 
2.3.3. 
Overall Benefit-Risk Conclusion 
The following considerations are important for the benefit-risk assessment: 
• Only subjects with moderate to severe HS will be enrolled. Subjects must have HS 
lesions present in at least 2 distinct anatomic areas, one of which is Hurley Stage II or 
Hurley Stage III and AN count of ≥ 5. Subjects with draining fistula count of > 20 at 
screening or Day 1 will be excluded. 
• The inclusion and exclusion criteria will ensure that subjects who might be predisposed 
to a higher risk of drug-related TEAEs are either excluded or identified and treated with 
caution. Class effects seen with other IL-17 inhibitors have been considered when 
designing the eligibility criteria. Subjects with active infections or with a history of 
autoimmune, chronic inflammatory, or connective tissue disease will be excluded from 
participating in the study. 
• Subjects will be monitored at the site for at least 1 hour after administration of izokibep at 
designated visits. 
• After enrollment and through the end of the study, if the subject’s AN count is ≥ 150% of 
Day 1 AN count, antibiotic rescue medication is permitted. 
• Participation in the study is voluntary. Each subject may refuse to participate or withdraw 
from the study, at any time, without penalty or loss of benefits to which the subject is 
otherwise entitled. 
Considering the measures taken to minimize risk to subjects participating in this study, and the 
lack of clear dose-limiting AEs associated with izokibep, the pre-existing data on the effects of 
IL-17 inhibitors in hidradenitis, the potential risks identified in association with izokibep are 
justified by the anticipated benefits that may be afforded to subjects with HS. 
2.3.4. 
COVID-19 Benefit/Risk Assessment 
A benefit-risk assessment related to severe acute respiratory syndrome coronavirus 
(SARS-CoV-2) has been considered for this study and concluded that the coronavirus disease of 
2019 (COVID-19) pandemic does not alter the overall benefit-risk for conducting this study. 
Risk mitigation measures will be implemented based on the prevailing situation during study 
conduct, at the investigator’s discretion and in accordance with local and institutional guidelines 
as applicable. The risk-benefit of the study in relation to the COVID-19 pandemic will continue 

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to be assessed during the study and additional or revised measures may be implemented based on 
any updates to the benefit-risk assessment. 

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• Modified Sartorius Score after 4, 8, 12, 
16, 24, 32, and 52 weeks of treatment 
• Modified Sartorius Score at baseline, 
Weeks 4, 8, 12, 16, 24, 32, and 52 
• HS flare rates through 4 and 52 weeks of 
treatment 
• HS flares through Weeks 4 and 52 
• IHS4, after 4, 8, 12, 16, 24, 32, and 52 
weeks of treatment 
• IHS4 scores at Weeks 4, 8, 12, 16, 24, 32, 
and 52 
• Hidradenitis Suppurativa-Physician’s 
Global Assessment (HS-PGA) 
• Change from baseline to Weeks 4, 8, 12 
and 16, 24, 32, and 52 in HS-PGA 
• Mean change from baseline in draining 
tunnel count 
• Change from baseline in the number of 
draining tunnels at Weeks 4, 8, 12, 16, 24, 
32, and 52 
To explore the effect of izokibep on 
Patient-reported Outcomes (PROs) as 
measured by change from baseline over time 
in:  
 
 
• European Quality of Life-5 Dimensions 
(EQ-5D) 
 
• Change from baseline to Weeks 4, 8, 12, 
16, and 52 in EQ-5D 
• Hidradenitis Suppurativa Quality of Life 
(HiSQOL) 
 
• Change from baseline to Weeks 4, 8, 12, 
16, and 52 in HiSQOL 
• Hospital Anxiety and Depression Scale 
(HADS) 
• Change from baseline to Weeks 4, 8, 12, 
16, and 52 in HADS, HADS-anxiety and 
HADS-depression 
• Patient Global Impression of Change 
(PGIC) 
• PGIC at Weeks 4, 8, 12, 16, 24, and 52 
• DLQI 
• Change from baseline to Weeks 4, 8, 16, 
24, and 52 in DLQI 
• Short Form-12v2™ Health Survey 
(SF-12v2) 
• Change from baseline to Weeks 8, 12, 16, 
24, and 52 in SF-12v2 
To estimate the mean trough plasma level 
izokibep in subjects with HS 
• Trough plasma concentrations of izokibep 
at collected timepoints 

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To assess the immunogenicity of izokibep as 
measured by the presence of ADAs 
• ADAs 
To assess biomarkers of anti-IL-17A 
treatment and biomarkers associated with HS 
efficacy (United States Only) 
• Change in inflammatory cytokines and 
biomarkers associated with HS 
pathophysiology 
ADA = anti-drug antibody; AN = abscess and inflammatory nodule; HiSCR = hidradenitis suppurativa clinical response; 
HS = hidradenitis suppurativa; IHS4 = International Hidradenitis Suppurativa Severity Score; NRS = numeric rating scale; 
SAE = serious adverse event; SF-12v2 = Short Form-12v2; TEAE = treatment-emergent adverse event 
a The HiSCR75 is defined as at least a 75% reduction from baseline in the total AN count, with no increase from baseline in 
abscess or draining fistula count. 
b The HiSCR90 is defined as at least a 90% reduction from baseline in the total AN count, with no increase from baseline in 
abscess or draining fistula count. 
c The HiSCR100 is defined as 100% reduction from baseline in the total AN count, with no increase from baseline in abscess or 
draining fistula count. 
d The HiSCR50 is defined as at least a 50% reduction from baseline in the total AN count, with no increase from baseline in 
abscess or draining fistula count. 
e Flare defined as ≥ 25% increase in AN count with a minimum increase of 2 AN relative to baseline. 
Primary Estimand 
Estimands are discussed in Section 9.3.2 
The components of the estimand to address the primary objective are as follows: 
• Treatment: izokibep versus placebo. 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria. 
• Variable of interest: achievement of HiSCR75 after 12 weeks of treatment. 
• Summary measure: response rate, achievement of HiSCR75 (Yes/No). 
• Intercurrent event (ICE) handling: treatment policy strategy, in general, with all subjects 
included in the analysis regardless of treatment discontinuation, concomitant 
medication/rescue medication, protocol deviations, or other actions. Subjects who receive 
antibiotic therapy that could affect HS will be included in the primary analysis by 
assigning non-response at subsequent timepoints. Multiple imputation will be used to 
handle other types of missing data. Additional details described in Section 9.3.2. 
Secondary Estimands 
Estimands are discussed in Section 9.3.3 
The 5 components of the estimand to address each secondary objective are as follows. 
First secondary objective: 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria 
• Variable of interest: percentage of subjects achieving HiSCR90 at Week 12 

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• Summary measure: response rate, achievement of HiSCR90 at Week 12 (Yes/No) 
• ICE handling: treatment policy strategy, in general, with all subjects included in the 
analysis regardless of treatment discontinuation, concomitant medication/rescue 
medication, protocol deviations, or other actions. Subjects who receive antibiotic therapy 
that could affect HS will be included in the analysis by assigning non-response at 
subsequent timepoints. Multiple imputation and non-response imputation will be used to 
handle certain other types of missing data, analogously to the primary endpoint. 
Second secondary objective: 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria 
• Variable of interest: percentage of subjects achieving HiSCR100 at Week 12 
• Summary measure: response rate, achievement of HiSCR100 at Week 12 (Yes/No) 
• ICE handling: treatment policy strategy, in general, with all subjects included in the 
analysis regardless of treatment discontinuation, concomitant medication/rescue 
medication, protocol deviations, or other actions. Subjects who receive antibiotic therapy 
that could affect HS will be included in the analysis by assigning non-response at 
subsequent timepoints. Multiple imputation and non-response imputation will be used to 
handle certain other types of missing data, analogously to the primary endpoint. 
Third secondary objective: 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria 
• Variable of interest: percentage of subjects achieving HiSCR50 at Week 12 
• Summary measure: response rate, achievement of HiSCR50 at Week 12 (Yes/No) 
• ICE handling: treatment policy strategy, in general, with all subjects included in the 
analysis regardless of treatment discontinuation, concomitant medication/rescue 
medication, protocol deviations, or other actions. Subjects who receive antibiotic therapy 
that could affect HS will be included in the analysis by assigning non-response at 
subsequent timepoints. Multiple imputation and non-response imputation will be used to 
handle certain other types of missing data, analogously to the primary endpoint. 
Fourth secondary objective 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria 
• Variable of interest: change in HS flares after 12 weeks of treatment 
• Summary measure: response rate, improvement in HS flare occurrence (Yes/No) 

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• ICE handling: treatment policy strategy, with all subjects included in the analysis 
regardless of treatment discontinuation, concomitant medication/rescue medication, 
protocol deviations, or other actions. All subjects with missing abscess, inflammatory 
nodule, and draining tunnel counts will be included using multiple imputation, 
analogously to the analysis of the primary endpoint. Subjects who receive antibiotic 
therapy that could affect HS will be included in the analysis by assigning non-response at 
subsequent timepoints. Multiple imputation and non-response imputation will be used to 
handle certain other types of missing data, analogously to the primary endpoint. 
Fifth secondary objective 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria 
• Variable of interest: change in Dermatology Life Quality Index (DLQI) after 12 weeks of 
treatment 
• Summary measure: mean change from baseline in DLQI 
• ICE handling: treatment policy strategy, in general, with all subjects included in the 
analysis regardless of treatment discontinuation, concomitant medication/rescue 
medication, protocol deviations, or other actions 
Sixth secondary objective: 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria and 
with baseline Hurley Stage II 
• Variable of interest: achievement of AN count of 0, 1, or 2 at Week 12 
• Summary measure: response rate, achievement of AN count of 0, 1, or 2 at Week 12 
(Yes/No) 
• ICE handling: treatment policy strategy, in general, with all subjects included in the 
analysis regardless of treatment discontinuation, concomitant medication/rescue 
medication, protocol deviations, or other actions. Subjects who receive antibiotic therapy 
that could affect HS will be included in the analysis by assigning non-response at 
subsequent timepoints. Multiple imputation and non-response imputation will be used to 
handle certain other types of missing data, analogously to the primary endpoint. 

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Seventh secondary objective: 
• Treatment: izokibep versus placebo 
• Population of interest: subjects with HS who meet all inclusion/exclusion criteria and 
have a baseline numeric rating scale (NRS) ≥ 4 
• Variable of interest: change in NRS score after 12 weeks of treatment 
• Summary measure: response rate, reduction in NRS scores, specifically, at least a 3-point 
reduction from baseline in NRS in Patient Global Assessment of Skin Pain at its worst, at 
Week 12 (Yes/No) 
• ICE handling: hybrid estimand, with treatment policy strategy used for most ICEs and 
hypothetical strategy used to account for use of prohibited pain medications due to 
non-HS-related pain, when taken near a visit. All pain scores after such use of prohibited 
pain medication will be omitted from the dataset and replaced via multiple imputation in 
a model analogous to that used for multiple imputation of the primary endpoint. Multiple 
imputation and non-response imputation will be used to handle certain other types of 
missing data, analogously to the primary endpoint. 

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4. 
Study Design 
4.1. 
Overall Design 
This is a Phase 3, pivotal, confirmatory, randomized, double-blind, placebo-controlled, 
parallel-group study to evaluate the efficacy and safety of izokibep in subjects with moderate to 
severe HS. Subjects must have HS lesions present in ≥ 2 distinct anatomic areas, one of which 
must be Hurley Stage II or Hurley Stage III, and a total AN count of ≥ 5. Subjects with draining 
fistula count of > 20 at screening or Day 1will be excluded. 
Overall, 250 subjects (125 subjects per treatment group) with moderate to severe HS are planned 
to be enrolled at sites globally in North America, Europe, and Asia Pacific. Additional sites and 
regions may be added. 
Subjects meeting eligibility criteria will be randomized into 1 of 2 treatment groups in a 1:1 ratio 
as follows: 
• Group 1 (n = 125): placebo QW from Day 1/Week 0 through Week 15, then izokibep 
160 mg QW from Weeks 16 to 51. 
• Group 2 (n = 125): izokibep 160 mg QW from Day 1/Week 0 through Week 51. 
The first dose of study drug (ie, izokibep or placebo) will be administered on Day 1 (Week 0). 
Randomization will be stratified by prior TNFi use for HS (Yes/No) and Hurley Stage (II or III). 
The AN count is the sum of abscesses and inflammatory nodules. Subjects enrolled with stable 
concomitant antibiotic use (dosing regimen has been stable for ≥ 4 weeks prior to first dose of 
study drug) will be capped at approximately 30%. 
Subjects will complete study assessments according to the study visits outlined in the schedule of 
activities (SoA) (Section 1.3). The primary endpoint will be assessed at Week 12. The last dose 
of study drug will be administered on Week 51. 
An end of treatment visit will be conducted at Week 52 (± 5 days). A safety follow-up visit will 
be conducted at Week 59 (± 5 days). For subjects who early terminate, the end of treatment visit 
should be completed 1 week after last dose of study drug (± 5 days), and safety follow-up visit 
should be completed 8 weeks after last dose of study drug (± 5 days), where possible. 
The final analysis of primary and secondary endpoints will be conducted after the last subject has 
had the opportunity to complete Week 12 assessments or early terminates from the study. 
Analysis of data at later timepoints may occur after all subjects have had the opportunity to 
complete that timepoint. 
4.1.1. 
Independent Data Monitoring Committee 
An independent data monitoring committee (DMC) will be established to monitor data on an 
ongoing basis to ensure the continuing safety of the subjects enrolled in this study and to make 
recommendations on further development activities for izokibep. 

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The DMC will consist of at least 1 medical expert with expertise in the relevant therapeutic area 
and at least 1 statistician and will have a minimum of 3 members, 1 of whom will serve as the 
Chair. The DMC responsibilities, members (including their qualifications and possible conflicts 
of interest), authorities, meeting frequency to review unblinded interim data, and procedures will 
be documented in the DMC charter. The committee will meet as needed to review significant 
safety findings. After each review, the DMC will make recommendations regarding the 
continuation of the study based on safety. 
4.1.2. 
Number of Sites 
Approximately 95 sites across North America, Europe, and Asia Pacific will participate in this 
study. Additional sites and regions may be added. Sites that do not screen subjects within 
2 months of site initiation may be closed. 
4.1.3. 
Number of Subjects 
Participants in this clinical investigation shall be referred to as “subjects”. The number of 
subjects planned to be enrolled is 250 (125 subjects per treatment group). Subjects who are 
withdrawn or removed from treatment or the study will not be replaced. 
4.1.4. 
Study Duration for Subjects 
The maximum planned length of participation in the study for an individual subject is up to 
63 weeks, which includes the following: 
• screening period of up to 28 days (4 weeks) 
• treatment period of 51 weeks 
• follow-up visit at 8 weeks after the last dose of study drug. 
 
4.2. 
Scientific Rationale for Study Design 
The design of this clinical study was chosen to evaluate the efficacy of izokibep in the treatment 
of subjects with moderate to severe HS. 
The primary aim of the study is to evaluate the efficacy of izokibep administered SC 160 mg 
QW for the treatment of active HS. The primary endpoint of HiSCR75 response will be 
evaluated after all subjects have either completed Week 12 or terminated early from the study. 
Subjects will continue their randomized treatment until Week 16. After Week 16, subjects 
randomized to placebo will receive blinded active treatment (izokibep 160 mg QW) until 
Week 51. Long-term efficacy beyond Week 12 will be explored up to Week 52 and safety will 
be explored up to the end of study visit at Week 59. 
Standard statistical procedures will be utilized in this study. Efficacy measurements in this study 
have been selected or designed to assess disease activity in subjects with active HS. All clinical 
and laboratory procedures in this study are standard and generally accepted. 
Men and women 18 years of age and older with HS who meet all inclusion criteria and who do 
not meet any of the exclusion criteria are eligible for this study. The population being studied 

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Table 4-2. Predicted Exposure at Steady State for 160 mg Izokibep SC QW 
Parameter 
Unit 
Value 
Unit 
Value 
Cmax 
nmol/L 
2190 
µg/mL 
40.8 
Cmin 
nmol/L 
1460 
µg/mL 
27.2 
Caverage 
nmol/L 
1870 
µg/mL 
34.8 
AUC0-τ 
h·nmol/L 
31.5·104 
h·µg/mL 
5850 
AUC0-τ = area under the concentration-time curve over the dose interval; Caverage = average observed plasma concentration; 
Cmax = maximum observed plasma concentration; Cmin = minimum observed plasma concentration; h = hour; QW = once a week; 
SC = subcutaneous. 
The doses of izokibep used in this study support the maximum likelihood of demonstrating the 
potential efficacy for izokibep in subjects with HS within an acceptable safety profile. 
Measures have also been taken to ensure the well-being of subjects by applying appropriate 
inclusion and exclusion criteria to recruit a broad population that is most likely to benefit from 
treatment, while excluding subjects with an unacceptable risk to enter the study (Section 5). 
Further, during the study, measures are in place to monitor the safety of subjects on a regular 
basis. An independent DMC will also review the data on an ongoing basis. 
4.4. 
End of Study Definition 
The end of the study is defined as the date of the last scheduled procedure including the final 
follow-up shown in the SoA for the last subject in the study globally. 
A subject is considered to have completed the study if the subject has completed all periods of 
the study including the last scheduled procedure shown in the SoA. 

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5. 
Study Population 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also known as 
protocol waivers or exemptions, is not permitted. 
5.1. 
Inclusion Criteria 
Subjects are eligible to be included in the study only if all of the following criteria apply: 
General 
1. Subject has provided signed informed consent including consenting to comply with the 
requirements and restrictions listed in the informed consent form (ICF) and in this 
protocol. 
2.  The inclusion criterion was removed and replaced with inclusion criterion 12. 
12. Subject must be 18 years of age (or the legal age of consent in the jurisdiction in 
which the study is taking place) or older, at the time of signing the informed consent. 
Type of Subject and Disease Characteristics 
3. Diagnosis of HS for ≥ 6 months prior to first dose of study drug. 
4. Hidradenitis suppurativa lesions present in ≥ 2 distinct anatomic areas (eg, left and 
right axilla; or left axilla and left inguino-crural fold), one of which is Hurley Stage II 
or Hurley Stage III at screening and Day 1 prior to enrollment/randomization. 
5. A total AN count of ≥ 5 at screening and Day 1 prior to enrollment/randomization. 
6. Subject must have had an inadequate response to oral antibiotics (defined as ≥ 3-month 
treatment with an oral antibiotic for treatment of HS) OR exhibited recurrence after 
discontinuation to, OR demonstrated intolerance to, OR have a contraindication to oral 
antibiotics for treatment of their HS as assessed by the investigator through subject 
interview and review of medical history. 
7. Must agree to use daily or a minimum of 3 days a week (throughout the duration of the 
study) one of the following over-the-counter topical antiseptics on their body areas 
affected with HS lesions: chlorhexidine gluconate, triclosan, benzoyl peroxide, diluted 
bleach in bathwater, or as otherwise determined acceptable by ACELYRIN medical 
monitor. 
8. Subject must be willing to complete a daily skin pain diary 7 consecutive days prior to 
Day 1; if skin pain diaries are not completed for at least 3 of the 7 consecutive days 
prior to the Day 1 visit, the subject may not be enrolled/randomized. 
Other Inclusions 
9. No known history of active tuberculosis (TB) unless adequately treated according to 
World Health Organization/Center for Disease Control and Prevention therapeutic 
guidance and determined to be fully recovered by a TB specialist (see Section 8.2.8). 

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10. Subject has a negative interferon-gamma release assay (IGRA) TB test (QuantiFERON 
recommended) at screening, is not at high risk of acquiring TB infection, and has no 
current or history of nontuberculous mycobacterium infection (see Section 8.2.8): 
• For indeterminate IGRA TB test results, subjects are permitted to retest once. If retest 
results are negative, the subject is eligible for the study. If retest results are positive or 
remain indeterminate, the subject may not be randomized without further evaluation by 
a TB specialist. 
• For positive IGRA TB test results, subjects may not be randomized without further 
evaluation by a TB specialist. 
Sex and Contraceptive/Barrier Requirements 
11. Male and female subjects: 
Contraceptive use by men and women should be consistent with local regulations regarding 
the methods of contraception for those participating in clinical studies. 
a. Male subjects: 
Male subjects are eligible to participate if they agree to the following during the study drug 
period and for at least 8 weeks after the last dose of study drug: 
• Refrain from donating semen, plus either: 
o Be abstinent from heterosexual intercourse as their preferred and usual 
lifestyle (abstinent on a long-term and persistent basis) and agree to 
remain abstinent. 
OR 
o Must agree to use contraception/barrier as detailed below: 
▪ Agree to use a male condom (and should also be advised of the 
benefit for a female partner to use a highly effective method of 
contraception as a condom may break or leak) when having sexual 
intercourse with a woman of childbearing potential (WOCBP) who 
is not currently pregnant. 
b. Female subjects: 
A female subject is eligible to participate if she is not pregnant or breastfeeding, and 1 of the 
following conditions applies: 
• Is a woman of nonchildbearing potential as defined in the protocol 
(Section 10.4.1). 
OR 
• Is a WOCBP, and uses a contraceptive method that is highly effective, with 
a failure rate of < 1%, as described in the protocol (Section 10.4.2) during 
the study drug period and for at least 8 weeks after the last dose of study 
drug. The investigator should evaluate the potential for contraceptive 

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method failure (eg, non-compliance, recently initiated) in relationship to the 
first dose of study drug. 
A WOCBP must have a negative highly sensitive serum pregnancy test at screening and a 
negative urine pregnancy test on Day 1 prior to the first dose of study drug. 
 
5.2. 
Exclusion Criteria 
Subjects are excluded from the study if any of the following criteria apply: 
Medical Conditions 
1. Draining fistula count of > 20 at screening or Day 1 prior to enrollment/randomization. 
2. Outpatient surgery ≤ 8 weeks prior or inpatient surgery ≤ 12 weeks prior to 
enrollment/randomization. 
3. Other active skin disease or condition (eg, bacterial, fungal or viral infection) that 
could interfere with study assessments. 
4. History of active IBD 
OR 
Any of the following symptoms (of unknown etiology) or any signs or symptoms 
within the last year that in the opinion of the investigator may be suggestive of IBD, 
with fecal calprotectin > 500 µg/g; OR if fecal calprotectin > 150 to < 500 µg/g without 
confirmed approval from a gastroenterology consultation that an IBD diagnosis is 
clinically unlikely (see Section 8.2.10) when the following clinical signs and symptoms 
are present: 
a. prolonged or recurrent diarrhea 
b. prolonged or recurrent abdominal pain 
c. blood in stool 
5. Chronic pain not associated with HS (eg, fibromyalgia). 
6. Uncontrolled, clinically significant system disease such as diabetes mellitus, 
cardiovascular disease including moderate to severe heart failure (New York Heart 
Association class III/IV), moderate to severe renal disease, moderate to severe liver 
disease or hypertension, as determined by investigator. 
7. History of demyelinating disease (including myelitis) or neurological symptoms 
suggestive of demyelinating disease. 
8. Malignancy within 5 years except treated and considered cured cutaneous squamous or 
basal cell carcinoma, in situ cervical cancer, or in situ breast ductal carcinoma. 

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9. Risk of self-harm or harm to others as evidenced by past suicidal behavior or endorsing 
items 4 or 5 on the Columbia-Suicide Severity Rating Scale (C-SSRS) assessed at 
screening. Subjects with major depressive disorder are permitted in the study if they 
are considered by the investigator to be stable and are taking no more than 
1 medication. If on medication for major depressive disorder, subjects must have been 
on a stable antidepressant dose for at least 3 months prior to the first dose of study drug 
and agree to continue for the duration of the study or as indicated by their treating 
psychiatrist. 
10. History or evidence of any clinically significant disorder (including psychiatric), 
condition, or disease that, in the opinion of the investigator, may pose a risk to subject 
safety or interfere with the study evaluation, procedures, or completion. 
11. Active infection or history of infection as follows: 
a. Any active infection for which oral anti-infectives (antibiotics, antivirals, 
antifungals) were used ≤ 14 days prior to first dose of study drug (except for the use 
of a stable dose allowable antibiotics [doxycycline or minocycline only] for HS). 
b. A serious infection requiring hospitalization or IV anti-infectives (antibiotics, 
antivirals, antifungals) ≤ 30 days prior to first dose of study drug. 
c. Recurrent or chronic infections or other active infections that in the opinion of the 
investigator might cause this study to be detrimental to the subject. 
12. Candida infection requiring systemic treatment within 3 months prior to first dose of 
study drug. 
13. Tuberculosis or fungal infection seen on available chest x-ray taken within 3 months 
prior to screening (Exception: documented evidence of completed treatment and 
clinical resolution). 
14. Known history of human immunodeficiency virus (HIV) or positive HIV test at 
screening. 
Washout and Non-permitted Drugs 
15. Previous exposure to izokibep or any other IL-17 inhibitor and IL-17 receptor 
inhibitors (eg, secukinumab, ixekizumab, bimekizumab, brodalumab). 
16. Prior exposure to biologics that had a potential or known association with progressive 
multifocal leukoencephalopathy (ie, natalizumab [Tysabri], rituximab [Rituxan], or 
efalizumab [Raptiva]). 
17. Exposure to TNFi, IL-1, IL-12, IL-23, or IL-12/23 receptor inhibitors within 
5 half-lives prior to first dose of study drug. 
18. Exposure to any of the following. 
• Exposure to the following ≤ 12 weeks prior to first dose of study drug 
o Other experimental or commercially available biologic or biosimilar therapies 
(within 12 weeks or 5 half-lives, whichever is longer). 
o IV gamma-globulin or Prosorba column therapy. 

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• Exposure to the following ≤ 4 weeks prior to first dose of study drug 
o Janus-kinase (JAK) inhibitors (eg, tofacitinib, upadacitinib) 
o Oral or injectable corticosteroids (including intralesional injections) 
o Cyclosporine, azathioprine, tacrolimus 
o Other systemic treatments for autoimmune/inflammatory conditions not listed 
above or below (eg, mycophenolate mofetil, retinoids, fumarates, apremilast, or 
phototherapy [eg, psoralen plus ultraviolet-A radiation, ultraviolet-B radiation]), 
except for allowable stable dose antibiotics (doxycycline or minocycline) 
o Laser or intense pulse light therapy in anatomic areas of HS lesions 
19. Exposure of the following ≤ 2 weeks prior to first dose of study drug 
• Prescription topical therapies 
• Opioid analgesics 
• Non-oral concomitant analgesics (eg, IV, SC). 
20. For subjects entering study with a permitted oral antibiotic treatment (doxycycline or 
minocycline only) for HS: not on a stable dose for ≥ 4 weeks prior to first dose of study 
drug. 
21. For subjects entering study with oral, non-opioid analgesics: not on a stable dose for 
≥ 5 days prior to first dose of study drug. Exception is acetaminophen is allowed ≤ 2 g 
per day. 
22. Required or is expected to require, opioid analgesics for any reason (excluding 
tramadol) during the study. 
23. History of hypersensitivity or allergy to izokibep or its excipients. 
24. Received live vaccination ≤ 12 weeks prior to dosing or scheduled to receive a live 
vaccine ≤ 12 weeks following the last dose of study drug. 
25. Participating in another clinical study or participated in a clinical study involving 
administration of an IMP within the following time period prior to dosing: 12 weeks, 
5 half-lives, or twice the duration of the biological effect of the IMP (whichever is 
longer). 
Diagnostic Assessments 
26. Concurrent acute or chronic viral hepatitis B or C. Note: subjects who have evidence of 
or tested positive for hepatitis B or hepatitis C at screening are excluded. 
• A positive test for the hepatitis B virus is defined as any of the following: 
o Positive for hepatitis B surface antigen 
o Positive for anti-hepatitis B core antibody 
o Hepatitis B virus DNA detected on polymerase chain reaction 
• A positive test for the hepatitis C virus (HCV) is defined as positive for hepatitis C 
antibody (anti-HCV antibody) 

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27. Laboratory abnormalities at screening: 
• Hemoglobin < 9 g/dL 
• Platelet count < 100 000/mm3 
• White blood cell count < 3000 cells/mm3 
• Aspartate aminotransferase and/or alanine aminotransferase ≥ 2.5 times the upper limit 
of normal 
• Moderate or severe renal impairment (ie, creatinine clearance < 60 mL/min) 
(Modification of Diet in Renal Disease formula) 
• Note: Laboratory assessments due to value(s) out of range due to sampling error or that 
could be within range with repeat sampling may be repeated up to 2 times 
28. Any other laboratory abnormality that in the opinion of the investigator will pose a risk 
to subject safety or interfere with the study evaluation, procedures, or completion 
Other Exclusion Criteria 
29. Previously enrolled, randomized to, or withdrawn from this study. 
30. Active substance abuse (drug or alcohol) within 24 weeks prior to first dose of study 
drug, as determined by the investigator. 
31. Any condition that compromises the ability of the subject to give written informed 
consent, or the subject’s unwillingness or inability to comply with study procedures. 
5.3. 
Lifestyle Considerations 
The investigator should encourage subjects to limit alcohol consumption to ≤ 2 per day, 
≤ 7 alcoholic drinks per week. An alcoholic drink is defined as a 6 oz (175 mL) glass of wine, a 
1 oz (30 mL) glass of hard liquor (eg, whiskey), or an 8 oz (250 mL) glass of beer. 
5.4. 
Screen Failures 
Screen failures are defined as subjects who consent to participate in the clinical study but are not 
subsequently enrolled/randomized to the study. A minimal set of screen failure information is 
required to ensure transparent reporting of screen failure subjects to meet the Consolidated 
Standards of Reporting Trials publishing requirements and to respond to queries from regulatory 
authorities. Minimal information includes demography, screen failure details, eligibility criteria, 
and any SAEs. 
Individuals who do not meet the criteria for participation in this study (screen failure) may be 
rescreened up to 2 times (ie, total of 3 screens including initial screen). Refer to Section 6.3.2 for 
details on rescreening. 
5.5. 
Criteria for Temporarily Delaying Dosing 
Subject should be dosed within the window as detailed in the SoA (Section 1.3). 
All missed or delayed doses should be documented. If the investigator determines a subject 
should not be dosed within the defined window for a safety reason (eg, an AE, SAE), then a 
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5.6. 
COVID-19-related Precautions 
Risk mitigation measures, including COVID-19-related precautions and procedures (including 
SARS-CoV-2 testing/screening) will be implemented based on the prevailing situation during the 
study conduct, at the investigator’s discretion, and in accordance with local and institutional 
guidelines as applicable. 
Subjects should be routinely monitored for any AEs at every visit, including signs or symptoms 
of infection. Should subjects demonstrate any symptoms or AEs (including known COVID-19 
symptoms or tested positive for COVID-19), the symptoms or AEs will be reported to the site as 
per study procedures and assessed by the investigator. As with any AEs, AE data will be 
collected on the appropriate electronic case report form (eCRF). 
If a subject has received, or is planning to receive, COVID-19 vaccination, the investigator 
should refer to vaccine considerations in eligibility criteria (Section 5.2) and concomitant 
medications (Section 6.8) requirements in the protocol. 

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6. 
Study Drug(s) and Concomitant Therapy 
Study drugs are all pre-specified, investigational, and non-IMPs, medical devices and other 
interventions (eg, surgical and behavioral) intended to be administered to the study subjects 
during the study conduct. 
6.1. 
Study Drug(s) Administered 
 
Table 6-1. Study Drug(s) Administered 
 
Investigational Drug 
Placebo 
Drug name: 
 
Izokibep 
Placebo 
Pharmacological group: 
Biologic: IL-17A inhibitor 
None 
Dosage formulation: 
 
Solution for injection 
Solution for injection 
Unit dose 
strength(s)/Dosage level(s): 
Each 2R (2 mL) glass vial contains 
1.2 mL of izokibep (nominal 
concentration 80 mg/mL ± 10%)  
Not applicable 
Route of administration:  
SC injection 
SC injection 
Non-active ingredients 
(excipients) 
10 mM sodium phosphate 
150 mM NaCl 
0.5 mM EDTA 
10 mM sodium phosphate 
150 mM NaCl 
0.5 mM EDTA 
 
Packaging and labeling 
 
Each vial will be labeled as required 
per country requirement.  
Each vial will be labeled as required 
per country requirement. 
Special storage 
recommendations 
Vials are to be stored at 2°C to 8°C. 
The filled syringe must be stored in the 
refrigerator at 2°C to 8°C (protected 
from light) if not used for immediate 
dose administration. Once removed 
from the refrigerator, the solution 
should be allowed to warm to room 
temperature (about 15 to 20 minutes) 
prior to administration. For further 
details, refer to Pharmacy Manual. 
Store at room temperature (do not 
store above 25°C). 
Given placebo and izokibep will be 
provided in blinded, matching vials, 
both should be stored at 2°C to 8°C. 
Once removed from the refrigerator, 
the solution should be allowed to 
warm to room temperature (about 15 
to 20 minutes) prior to administration. 
For further details, refer to Pharmacy 
Manual.  
EDTA = ethylenediaminetetraacetic acid; IL = interleukin; NaCl = sodium chloride; SC = subcutaneous 
6.1.1. 
Dosage, Administration, and Schedule 
Study drug (izokibep 160 mg QW or placebo) will be dosed by SC injection as described below. 
Study drug vials for placebo and izokibep will be visually indistinguishable. 
Study drug doses are fixed and will not be adjusted for individual subjects during the study. 
Throughout treatment period, 2 SC injections are to be given for each study drug administration. 
The anatomical sites for administration of study drug are the upper arm, upper thigh, or 
abdomen. 
At the site, only authorized investigational site staff members are to administer study drug 
(see Section 6.2). Subjects should be monitored for 1 hour after the first 2 study drug 
administrations at Visits Day 1/Week 0, Week 1, Week 16, and Week 17. 

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• Group 1: placebo QW from Day 1/Week 0 to Week 15, then izokibep 160 mg QW from 
Week 16 to Week 51 
• Group 2: izokibep 160 mg QW from Day 1/Week 0 to Week 51 
After Week 4, qualified subjects may perform home dosing of study drug. Site staff will 
administer the first 2 doses of study drug and train the subject on handling and 
self-administration of study drug during those study visits. The subject must self-administer the 
next 2 doses of study drug at the site and demonstrate competency prior to being allowed to 
perform home dosing. A subject’s caregiver or designee can also be trained on home dosing 
based on the subject’s preference. Only those subjects/caregivers or designees who demonstrate 
competency to perform home dosing will be allowed to do so; otherwise, the subject will need to 
return to the site for all study drug administrations. 
The dosing schedule is described by a schema in Section 1.2. 
6.2. 
Preparation, Handling, Storage, and Accountability 
• The investigator or designee must confirm appropriate temperature conditions have been 
maintained during transit for all study drug received, and any discrepancies are reported 
and resolved before use of the study drug. 
• Only subjects randomized in the study may receive study drug. All study drug must be 
stored prior to dispensing in a secure, environmentally controlled, and monitored (manual 
or automated) area in accordance with the labeled storage conditions with access limited 
to the investigator and authorized site staff. 
• The investigator, institution, or the head of the medical institution (where applicable) is 
responsible for study drug accountability, reconciliation, and record maintenance 
(ie, receipt, reconciliation, and final disposition records). 
• Further guidance and information for the final disposition of unused study drugs are 
provided in the Pharmacy Manual. 
6.3. 
Measures to Minimize Bias: Randomization and Blinding 
6.3.1. 
Subject Enrollment 
Before subjects begin participation in any study-specific activities/procedures, the sponsor or 
designee requires a copy of the site’s written Institutional Review Board (IRB)/Independent 
Ethics Committee (IEC) approval of the protocol, ICF, and all other subject information and/or 
recruitment material, if applicable (see Section 10.1.3). All subjects must personally sign and 
date the ICF before the commencement of study-specific activities/procedures. 
A subject is considered enrolled when the investigator decides that the subject has met all 
eligibility criteria and registered the subject as enrolled/randomized within the Interactive 
Voice/Web Response System (IXRS). The investigator is to document this decision and date in 
the subject’s medical record. The screening period starts when the subject signs and dates the 
ICF and ends when the subject is enrolled/randomized, or screen failed. The screening period is 
up to 28 days. Certain initial screening period procedures may be repeated during the original 
initial screening period. (Note: Repeating procedures during the original initial screening period 

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is a part of screening and is not considered “rescreening.”) These procedures include laboratory 
assessments due to value(s) out of range due to a potential sampling error or that could be within 
range with repeat sampling. Laboratory value(s) out of range due to sampling error or that might 
be within range after medically appropriate supplementation may be repeated up to 2 times 
within the screening window before the subject is considered a screen failure. 
All subjects who enter the screening period for the study receive a unique subject identification 
number assigned by the IXRS. This number will be used to identify the subject throughout the 
clinical study and must be used on all study documentation related to that subject. The subject 
identification number must remain constant throughout the entire clinical study; it must not be 
changed after initial assignment, including if a subject is rescreened. 
The subject identification number consists of 12 digits that correspond to the site number 
(9 digits) plus the sequential number (3 digits) as follows: 
• Site number (first 9 digits) 
o First 3 digits correspond to the last 3 digits of the study protocol number (ie, 107) 
o Middle 3 digits correspond to the 3-digit ISO 3166-1 number code for the country 
(eg, US country code = 840; For country codes with only 2 digits, a lead “0” will 
be added) 
o Last 3 digits are sequential numbers given to sites within a country (eg, For a US 
site = 107840001) 
• Sequential numbering of subjects within a site (last 3 digits) 
o The last 3 digits are sequential numbers assigned by IXRS within a site (eg, For 
US Site 107840001, their first subject = 107840001001) 
A subject who is determined to be ineligible must be registered as a screen fail in the IXRS. 
6.3.2. 
Rescreening 
Investigators may rescreen a subject if the investigator is reasonably certain that reasons for 
screen failure will be resolved prior to or during a repeat screening attempt. Reasons to rescreen 
may include but are not limited to the following: 
• Laboratory value(s) out of range due to sampling error or that might be within range after 
medically appropriate supplementation. (Note: Before screen failing and then rescreening 
the subject, efforts should be made to repeat the laboratory assessment(s) during the 
original initial screening period.). 
• The subject has a medical condition that can be stabilized or resolved prior to the repeat 
screening/rescreening attempt; or 
• Additional time is required following the subject’s last dose of an excluded medication. 
Investigators are encouraged to consult with the medical monitor prior to rescreening subjects for 
other reasons. 
A subject must provide informed consent prior to the initiation of any rescreening procedures 
only if 30 or more days have elapsed since the date of the subject’s initial informed consent. The 
subject is entered into rescreening in the IXRS, and all screening procedures must be repeated 

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except as noted in the inclusion/exclusion criteria. A subject may be screened up to 3 times (ie, 
no more than 2 rescreens). Near to the end of study enrollment, sites may be notified when no 
additional subjects will be screened or rescreened. 
If a subject rescreens, a chest x-ray does not need to be repeated if a previous chest x-ray was 
performed ≤ 3 months prior to Day 1. 
If a subject rescreens, hepatitis, TB, HIV, urinalysis, and electrocardiogram (ECG) tests do not 
need to be repeated if a previous test was performed < 60 days prior to Day 1. 
6.3.3. 
Treatment Assignment/Randomization 
Subjects will be randomized to the study drug or placebo (in a 1:1 ratio) on Day 1 by the IXRS. 
The subject, site personnel, and sponsor/Contract Research Organization (CRO) study personnel 
and designees will be blinded to the randomization treatment group assignment (ie, izokibep or 
placebo). The randomization dates are to be documented in the subject’s medical record. 
Randomization will be stratified by prior TNFi use for HS (Yes/No) and Hurley Stage (II or III). 
Izokibep and matching placebo will be visually indistinguishable to prevent unblinding during 
preparation or administration of study material. 
6.3.4. 
Site Personnel Access to Individual Treatment Assignments 
A subject’s treatment assignment should be unblinded only when knowledge of the treatment is 
essential for the further management of the subject in this study. Unblinding at the site for any 
other reason will be considered a protocol deviation. The investigator should contact the medical 
monitor before unblinding any subject’s treatment assignment, whenever possible. If an urgent 
therapeutic intervention is necessary that warrants unblinding prior to contacting the medical 
monitor, the investigator can directly access the IXRS, or call the 24-hour emergency medical 
coverage line to unblind without medical monitor notification or agreement but must contact the 
medical monitor within 1 working day after the unblinding event. 
If an SAE requires an expedited regulatory report to be sent to 1 or more regulatory agencies, 
sponsor/designee’s safety staff may unblind the intervention assignment for the subject. A copy 
of the report, identifying the subject’s intervention assignment, may be sent to that regulatory 
agency in accordance with local regulations. 
Please refer to the Study Pharmacy Manual for details. 
6.4. 
Study Drug Compliance 
When subjects are dosed at the site, they will receive study drug directly from the investigator or 
designee, under medical supervision. The date and time of each dose administered in the clinic 
will be recorded in the source documents. 
When study drug is administered at home by the subject/caregiver, compliance with study drug 
will be assessed at each visit. Compliance will be assessed by review of the subject dosing diary 
during the site visits and documented in the source documents and relevant form. Deviation(s) 
from the prescribed dosage regimen should be recorded and reported to the sponsor (or 
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A record of the quantity of study drug dispensed and administered to each subject must be 
maintained and reconciled with study drug and compliance records. Study drug dose dates, 
including study drug delays will also be recorded. Partial dose administration will be explained. 
6.5. 
Dose Modification 
No dose modifications are allowed in the study. 
6.6. 
Continued Access to Study Drug After the End of the Study 
There is no plan to continue access to study drug after the end of study. The choice of further 
therapy for HS at the end of the clinical study depends on the subject's individual needs and is 
left at the physician's discretion. 
6.7. 
Overdose 
Excessive dosing (beyond that prescribed in this protocol and including overdose) should be 
recorded in the case report form (CRF). Any SAE or non-serious AE associated with excessive 
dosing must be followed as any other SAE or non-serious AE as specified in (Section 10.3.3). 
These events are only considered AEs or SAEs if there are associated clinical signs and 
symptoms or if the act of taking the excess medicine itself is an AE or SAE (eg, suicide attempt). 
6.8. 
Prior and Concomitant Therapy 
Any medication or vaccine (including over-the-counter or prescription medicines, vitamins, 
and/or herbal supplements) that the subject is receiving at the time of enrollment or receives 
during the study must be recorded along with: 
• reason for use 
• dates of administration including start and end dates 
• dosage information including route, dose, and frequency. 
Concomitant medications should be used in alignment with the approved label in the respective 
country, and per doses as outlined below. 
The medical monitor should be contacted if there are any questions regarding concomitant or 
prior therapy. 
6.8.1. 
Prior Therapies 
Any treatments used for HS since the initial diagnosis (as determined through medical history 
records or through subject interview) prior to study entry will be recorded in the source 
documents and on the CRF, along with the reason for discontinuation. 
A detailed history of prior antibiotic and biologic (including but not limited to TNFi, IL-1, IL-12, 
IL-23, or IL-12/23 receptor inhibitors) use, response, and reason for discontinuation will be 
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6.8.2. 
Concomitant Therapies 
Upon initiation or discontinuation of investigational product, investigators should consider 
potential effects on metabolism of cytochrome P450 substrates with narrow therapeutic indices 
including, but not limited to, methotrexate, tacrolimus, cyclosporine, certain tricyclic 
antidepressants (including amitriptyline and nortriptyline), baricitinib, warfarin, and tamoxifen. 
The concomitant medications/treatments in the following sections are permitted during the study. 
6.8.2.1. 
Antiseptic Therapy 
Subjects are required to use an antiseptic wash on their HS lesions daily or at a minimum of 
3 days a week. Antiseptic wash use should be consistent during the study. Allowable antiseptic 
washes are limited to one of the following: chlorhexidine gluconate, triclosan, benzoyl peroxide, 
or dilute bleach in bathwater. If a different antiseptic wash is required during the study, the 
medical monitor should be consulted. 
6.8.2.2. 
Wound Care 
Concomitant use of wound care dressings on HS wounds is allowed; however, options are 
limited to alginates, hydrocolloids, and hydrogels. If a different option for wound care is required 
during the study, the medical monitor should be consulted. 
6.8.2.3. 
Analgesic Therapy 
For a subject entering the study on oral non-opioid analgesic: 
• If taken for a non-HS medical condition (eg, osteoarthritis), the subject may continue the 
analgesic, provided the dose is stable for 5 days prior to the first dose of study drug and is 
anticipated to remain stable throughout study participation. 
• If taken for HS-related pain but is not any of the oral non-opioid analgesics permitted for 
HS-related pain listed below, the non-permitted analgesic can be continued only if the 
HS-related pain is under control and the dose is stable for 5 days prior to the first dose of 
study drug and is anticipated to remain stable throughout study participation. If the 
HS-related pain becomes uncontrolled after Day 1, the subject must switch to permitted 
analgesics for HS-related pain listed below. 
If an enrolled subject experiences pain (HS-related or non-HS-related) after Day 1, they may 
initiate analgesic therapy at any time as follows: 
For HS-related pain, permitted analgesics are limited to: 
• Ibuprofen (at a dose of up to 800 mg by mouth every 6 hours) not to exceed 
2.0 grams/per 24 hours; AND/OR acetaminophen/paracetamol as per local labeling. 
• If HS-related pain is uncontrolled with ibuprofen or acetaminophen/paracetamol at the 
above dosing regimens after the Day 1 visit, subjects can be prescribed tramadol (at a 
dose of up to 100 mg po every 4 hours), not to exceed 400 mg per 24 hours. 
• From screening through Week 16, subjects will complete a daily diary of their analgesic 
use. From Week 16 through Week 59, subjects will be required to tell site staff if they 
took any analgesics within 24 hours of their site visit. All analgesics and dose 
adjustments will be captured in the source and on the appropriate CRF. 

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• Subjects will be encouraged not to take analgesics 12 hours prior to a study visit. 
For non-HS-related Pain: 
• Opioid analgesics are prohibited. 
• All other analgesics (including tramadol) are allowed at the recommended or prescribed 
dose. 
6.8.2.4. 
Antibiotic Therapy 
In approximately 30% of subjects, concomitant antibiotic use is permitted if dosing regimen has 
been stable for ≥ 4 weeks prior to first dose of study drug, and dosing regimen is maintained 
through the placebo-controlled period (Week 16 assessment). Antibiotics taken on an 
‘as-needed’ basis are not considered a stable dose. 
Permitted oral concomitant antibiotics include: 
• Oral: doxycycline (at a dose of up to 100 mg twice daily [BID]); minocycline (at a dose 
of up to 100 mg, BID). 
• If another oral concomitant antibiotic for HS is medically necessary at the time of 
enrollment/randomization, the medical monitor must be contacted for approval. If 
systemic antibiotics are used concomitantly, the dose should remain stable and constant. 
For non-HS-related AEs requiring antibiotic use: 
Concomitant antibiotic use for the treatment of an AE other than HS may be permitted per 
standard of care (eg, for treatment of pneumonia, tonsillitis) and should be captured and 
documented appropriately. 
6.8.2.5. 
Lesion Intervention 
If an acutely painful lesion occurs that requires an immediate intervention, the investigator will 
have the option to perform protocol-allowed interventions. Only 2 types of interventions are 
allowed: injection with intralesional triamcinolone acetonide suspension (at a concentration of up 
to 5 mg/mL, up to 1 cc) and incision and drainage. 
If incision and drainage is performed, the required over-the-counter antiseptic wash should 
continue to be used. New systemic and topical therapies following incision and drainage 
(including antibiotics), are prohibited. Concomitant use of wound care dressings is allowed; 
however, options are limited to alginates, hydrocolloids, and hydrogels. 
Subjects should continue using any ongoing oral and topical therapies (including antibiotics, 
with the constraints as described in Section 6.8.2.4) during the study. 
Concomitant medications associated with the lesion intervention(s) must be captured in the 
source and on the appropriate CRF. 
A total of 2 protocol-allowed interventions are permissible up until Week 16 visit. An 
intervention can occur on maximally 2 different lesions at the same or different visits or on the 
same lesion at 2 different study visits. The same lesion cannot be treated 2 times at the same 

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visit. If a subject requires more than 2 interventions within the first 16 weeks, then they must be 
discontinued from study drug. After Week 16, maximally 2 interventions every 4 weeks are 
permitted. If a subject requires more than 2 interventions within a 4-week period or has 2 of the 
same interventions on the same lesion within that period, then they must be discontinued from 
the study drug. 
All study visit evaluations must occur before any interventions are performed. Any lesion that 
undergoes an intervention will be documented in the source documents. The site will be required 
to count any lesion that undergoes an intervention as permanently present from the date of the 
intervention and must account for it in the source documents and on the appropriate CRF. 
6.8.3. 
Prohibited Medications 
The following medications are prohibited from enrollment through 2 weeks after the last dose of 
study drug: 
• All other biologic therapies with a potential therapeutic impact on HS including but not 
limited to TNFi, IL-1, IL-12, IL-17, IL-23, or IL-12/23 inhibitors 
• Any other immunomodulatory therapy (eg, cyclosporine, azathioprine, tacrolimus, IV 
gamma-globulin, or Prosorba column therapy) 
• JAK inhibitors (eg, tofacitinib, upadacitinib) 
• Other systemic treatments for HS including but not limited to antibiotics (except as 
specified in Section 6.8.2.4 or Section 6.8.4), methotrexate, cyclosporine, retinoids, and 
fumaric acid esters 
• Prescription topical therapies for HS. Prescription topical therapies are allowed for other 
indications (other than HS) only if approved by the medical monitor (exception: 
prescription topical corticosteroids can be used to treat localized erythema, edema, or 
pruritis at the injection site without medical monitor approval) 
• Oral analgesics for HS not listed in Section 6.8.2.3 
• Oral opioid analgesics 
• Non-oral concomitant analgesics (eg, IV, SC) 
• Live vaccines (during the study and for 12 weeks after the last dose of study drug) 
• Oral or injectable corticosteroids (except as allowed per Section 2.3.1) 
• Phototherapy 
• Any investigational agents 
• Over-the-counter topical antiseptic washes, creams, soaps, ointments, gels and liquids 
containing antibacterial agents to treat HS not listed in Section 6.8.2.1 
• Surgical or laser intervention for an HS lesion except as outlined in Section 6.8.2.5. 

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6.8.4. 
Rescue Medicine 
If a subject experiences an increase in their AN count such that the total count is ≥ 150% of their 
Day 1 AN count, antibiotic rescue medication may be initiated. 
Subjects who qualify may initiate treatment with minocycline or doxycycline up to 100 mg BID. 
The dosing regimen must remain stable throughout study participation. In the case that a subject 
was previously intolerant or has a contraindication to both minocycline and doxycycline for the 
treatment of HS, the medical monitor should review to determine whether another rescue 
medication would be more appropriate. Rescue antibiotic therapy should be captured in the 
source and on the appropriate electronic CRF. The date and time of rescue medication 
administration as well as the name and dosage regimen of the rescue medication must be 
recorded. 

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7. 
Discontinuation of Study Drug and Subject 
Discontinuation/Withdrawal 
Discontinuation of specific sites or of the study as a whole are detailed in Section 10.1.8. 
7.1. 
Discontinuation of Study Drug 
In rare instances, it may be necessary for a subject to permanently discontinue study drug. The 
reason for permanent discontinuation of drug will be documented. If study drug is permanently 
discontinued, the subject should, if at all possible, remain in the study to be evaluated for safety 
and efficacy. 
Subjects should continue to complete study assessments as outlined in the SoA (Section 1.3) 
where possible, with the exception of study drug administration. Reasons for removal from study 
drug include any of the following: 
• death 
• eligibility criteria violation(s) after the subject started study drug that may put the subject 
at risk by continued administration of study drug, as determined by the medical monitor 
and investigator 
• non-compliance with study procedures, study drug, or concomitant medications 
(including TB prophylaxis) that may put the subject at risk by continued administration 
of study drug, as determined by the investigator 
• AE that may put the subject at risk by continued administration of study drug, as 
determined by the investigator (see Section 10.3.5): 
• lost to follow-up 
• lack of efficacy: 
o subject requires more than 2 lesion interventions within the first 16 weeks of the 
study 
o after Week 16, subject requires more than 2 lesion interventions within a 4-week 
period or has 2 of the same interventions on the same lesion within that period 
• study terminated by sponsor 
• subject pregnancy 
• disease progression 
o subjects with disease progression or not responding to treatment, at the investigator’s 
discretion 
• withdrawal of consent 

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7.1.1. 
Liver Chemistry Stopping Criteria 
Discontinuation of study drug for abnormal liver tests is required by the investigator when a 
subject meets one of the conditions outlined in the algorithm or in the presence of abnormal liver 
chemistries not meeting protocol-specified stopping rules if the investigator believes that it is in 
best interest of the subject. 
Figure 3. Phase 2 Liver Chemistry Stopping Criteria and Increased Monitoring Algorithma 
 
Abbreviations: ALT = alanine transaminase; AST = aspartate transaminase; INR = international normalized ratio; SAE = serious 
adverse event; Tbili = total bilirubin; ULN = upper limit of normal. 
aLiver chemistry stopping criteria are outlined in detail in Section 10.5. 
7.1.2. 
Rechallenge 
7.1.2.1. 
Study Drug Restart or Rechallenge After Liver Stopping Criteria Met 
Study drug restart/rechallenge after liver chemistry stopping criteria are met is allowed in this 
study. If the subject meets liver chemistry stopping criteria, do not restart/rechallenge the subject 
with study drug unless: 
• Liver tests have returned to the subject’s baseline values. 
• Sponsor medical monitor approval is granted. 
• Ethics and/or IRB approval is obtained, if required. 

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NOTE: If study drug was interrupted for suspected intervention-induced liver injury, the 
subject should be informed of the risk of death, liver transplantation, hospitalization, and 
jaundice before resumption of dosing. 
Refer to Section 10.5 for details on the restart/rechallenge process. 
If sponsor medical monitor approval to restart/rechallenge the subject with study drug is not 
granted, then the subject must permanently discontinue study drug and may continue in the study 
for protocol-specified study assessments. 
7.2. 
Subject Discontinuation/Withdrawal from the Study 
Reasons for removal of a subject from the study are: 
• termination of study by sponsor 
• death 
• withdrawal of consent from study 
• lost to follow-up. 
Withdrawal of consent from study: 
• A subject may withdraw from the study at any time without jeopardizing subsequent 
medical care. 
• At the time of discontinuing from the study, if possible, an early discontinuation visit 
should be conducted, as shown in the SoA. See SoA (Section 1.3) for data to be collected 
at the time of study discontinuation and follow-up and for any further evaluations that 
need to be completed. 
• The subject will be permanently discontinued from the study drug and the study at that 
time. 
• If the subject withdraws consent for disclosure of future information, the sponsor may 
retain and continue to use any data collected before such a withdrawal of consent. 
• If a subject withdraws from the study, he/she may request destruction of any samples 
taken and not tested, and the investigator must document this in the site study records and 
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7.3. 
Lost to Follow-up 
A subject will be considered lost to follow-up if the subject repeatedly fails to return for 
scheduled visits and is unable to be contacted by the site. 
The following actions must be taken if a subject fails to return to the clinic for a required study 
visit: 
• The site must attempt to contact the subject and reschedule the missed visit as soon as 
possible, counsel the subject on the importance of maintaining the assigned visit schedule 
and ascertain whether the subject wishes to and/or should continue in the study. 
• Before a subject is deemed lost to follow-up, the investigator or designee must make 
every effort to regain contact with the subject (where possible, [3] telephone calls, and if 
necessary, a certified letter to the subject’s last known mailing address or local equivalent 
methods). These contact attempts should be documented in the subject’s medical record. 
• Where permitted by local regulations and approved by IRBs/IECs, third-party vendors 
may be employed by the site (funded by the sponsor) to assist the site in re-establishing 
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8. 
Study Assessments and Procedures 
• Informed consent must be obtained before any study-related procedures are performed. In 
regions where the legal age of consent is older than 18 years, informed consent must be 
obtained from and signed by the subject. 
• Study procedures and their timing are summarized in the SoA (Section 1.3). Protocol waivers 
or exemptions are not allowed. 
• Day 1 corresponds to the date of the first dose of study drug. 
• Visit/dosing windows of ± 3 days on either side of the scheduled visits/dosing are permitted; 
however, the investigator should try to keep the subjects on the original visit/dosing 
schedule. The window of ± 3 days is relative to Day 1 and applicable for all subsequent 
visits/dosing. The time between doses should be no less than 4 days and no more than 13 
days. 
• All assessments are to be completed before study drug administration, unless otherwise 
specified. It is recommended that patient-reported outcome assessments be completed first. 
• Immediate safety concerns should be discussed with the sponsor immediately upon 
occurrence or awareness to determine if the subject should continue or discontinue study 
drug. 
• Adherence to the study design requirements, including those specified in the SoA, is essential 
and required for study conduct. 
• All screening evaluations must be completed and reviewed to confirm that potential subjects 
meet all eligibility criteria. The investigator will maintain a screening log to record details of 
all subjects screened and to confirm eligibility or record reasons for screening failure, as 
applicable. 
• Procedures conducted as part of the subject’s routine clinical management (eg, x-rays) and 
obtained before signing of the ICF may be utilized for screening or baseline purposes 
provided the procedures met the protocol-specified criteria and were performed within the 
timeframe defined in the SoA. 
• Repeat or unscheduled samples may be taken for safety reasons or for technical issues with 
the samples. 
8.1. 
Efficacy Assessments 
Planned timepoints for all efficacy and/or immunogenicity assessments are provided in the SoA. 
The site should make every attempt to have the same investigator conduct efficacy assessments 
throughout the study for each subject. 
8.1.1. 
Hidradenitis Suppurativa Clinical Response 
The HiSCR was developed to address issues with available HS scoring systems and is a 
validated measure that is responsive to improvement in disease activity, simplifies the scoring 
process, and increases the sensitivity to detect HS-specific lesions (Kimball et al, 2014; 
Kimball et al, 2016). The HiSCR50 is defined as at least a 50% reduction from baseline in the 
total AN count, with no increase from baseline in abscess or draining fistula count. HiSCR75, 

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HiSCR90, and HiSCR100 are defined as at least 75%, 90% or 100% reduction respectively from 
baseline in the total AN count, with no increase from baseline in abscess or draining fistula 
count. 
8.1.2. 
Lesion and AN Count 
The number of inflammatory and non-inflammatory nodules, abscesses, draining and 
nondraining fistulas, and hypertrophic scars, as well as the physical location (eg, right/left axilla, 
right/left inframammary, intermammary, right/left buttock, right/left inguino-crural fold, 
perianal, perineal, other) will be recorded at the designated study visits listed in SoA 
(Section 1.3). The AN count is the sum of abscesses and inflammatory nodules. In addition, 
lesions counts will be performed at any time if the subject experiences a disease flare. The 
longest distance between 2 relevant lesions (if only 1 lesion, measure diameter of lesion) and 
whether the lesions are clearly separated by normal-appearing skin (yes or no) will be measured. 
The calculation of the HiSCR, International Hidradenitis Suppurativa Severity Score System 
(IHS4), and modified Sartorius score will be performed by the sponsor or designee based on the 
lesion counts entered by the study investigator(s) on the appropriate CRFs. In addition, the 
sponsor or designee will utilize the lesions counts entered by the investigator on the CRF to 
establish the rate of flares. 
Treatment decisions made during the conduct of the study will not be based on the HiSCR. 
8.1.3. 
Hurley Stage 
The Hurley Stage is a severity classification for HS that was developed in 1989 and is widely 
used for the determination of the severity of HS (Hurley, 1989). The Hurley Stage is defined by 
the following criteria: 
• Stage I: Abscess formation, single or multiple, without sinus tracts and cicatrization 
(scarring). 
• Stage II: Recurrent abscesses with tract formation and cicatrization, single or multiple, 
widely separated lesions. 
• Stage III: Diffuse or near-diffuse involvement, or multiple interconnected tracts and 
abscesses across the entire area. 
The study investigator will determine the Hurley Stage in each affected anatomical region at the 
designated study visits listed in the SoA (Section 1.3). If more than 1 stage is present in a region, 
the worst state in each region should be entered. 
8.1.4. 
Numeric Rating Scale Patient Global Assessment of Skin Pain 
The NRS Patient Global Assessment of Skin Pain will be completed on a daily diary by subjects 
from screening through Week 16, and at the designated study visits after Week 16, listed in SoA 
(Section 1.3). If pain diaries are not completed for at least 3 of the 7 consecutive days prior to the 
Day 1 visit, the subject may not be randomized. 
The Patient Global Assessment of Skin Pain is a unidimensional NRS that allows for rapid (often 
1 item) measures of pain that can be administered multiple times with minimal administrative 
burden. The NRS consists of scores from 0 to 10 with 0 indicating “no skin pain” and 10 

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indicating “pain as bad as you can imagine”. The pain will be described as “skin pain at its worst 
in the last 24 hours” and “skin pain on average in the last 24 hours”. 
The subject should complete the questionnaire before site personnel perform any clinic 
assessments and before any interaction with the site personnel has occurred to avoid biasing the 
subject’s response. 
8.1.5. 
Dermatology Life Quality Index 
Subjects will complete the DLQI questionnaire at the designated study visits listed in SoA 
(Section 1.3). The DLQI will be used to assess the symptoms and the impact of skin problems on 
quality of life. The DLQI can be used to evaluate 6 areas: symptoms and feelings, daily 
activities, leisure, work and school, personal relationships, and treatment (Finlay and Khan 
1994). Subjects will be asked to respond to the 10 items of the DLQI based on a recall period of 
“the last week”. Decreased scores indicate improved health-related quality of life. The subject 
should complete the questionnaire before site personnel perform any clinic assessments and 
before any interaction with the site personnel has occurred to avoid biasing the subject’s 
response. 
8.1.6. 
Modified Sartorius Score 
The Sartorius scale was created as a more detailed and dynamic HS severity scale and was 
modified in order to further develop and simplify this assessment for the clinical setting 
(Sartorius et al, 2009; Sartorius et al, 2010). The modified Sartorius score was the first 
disease-specific instrument for dynamically measuring clinical severity. The main parameter in 
the modified Sartorius score is the counting of individual nodules and fistulas. The modified 
Sartorius score includes an assessment of the anatomical regions involved, the numbers and 
scores of lesions for each region, the longest distance between 2 relevant regions (or size of a 
single lesion), and whether all lesions are separated by normal skin (yes or no). 
8.1.7. 
International Hidradenitis Suppurativa Severity Score System 
The IHS4 is a validated tool to dynamically assess HS severity to be used both in real-life and 
clinical study setting. The determination of IHS4 requires counting the nodules, abscesses, and 
draining fistulas/sinus tracts. The IHS4 score (points) = (number of nodules × 1) + (number of 
abscesses × 2) + (number of draining tunnels [fistulae/sinuses] × 4). A score of ≤ 3 signifies mild 
HS, a score of 4 to 10 signifies moderate HS, and a score of ≥ 11 signifies severe 
(Zouboulis et al, 2017). 
8.1.8. 
Hidradenitis Suppurativa-Physician’s Global Assessment 
The hidradenitis suppurativa-Physician’s Global Assessment (HS-PGA) is a validated 6-point 
scale that is used to measure improvement in inflammatory nodules, abscesses, and draining 
fistulas (Kimball et al, 2012; Zouboulis et al, 2015). The HS-PGA scale is defined by the 
following: 
• Clear: No inflammatory or non-inflammatory nodules 
• Minimal: Only the presence of non-inflammatory nodules 
• Mild: < 5 inflammatory nodules or 1 abscess or draining fistula and no inflammatory 
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• Moderate: ≥ 5 inflammatory nodules or 1 abscess or draining fistula and 
≥ 1 inflammatory nodule or 2 to 5 abscesses or draining fistulas and < 10 inflammatory 
nodules 
• Severe: 2 to 5 abscesses or draining fistulas and ≥ 10 or more inflammatory nodules 
• Very severe: > 5 abscesses or draining fistulas. 
8.1.9. 
European Quality of Life-5 Dimensions 
The European Quality of Life-5 Dimensions (EQ-5D) comprises 5 questions on mobility, 
self-care, pain, usual activities, and psychological status with 3 possible answers for each item 
(1 = no problem, 2 = moderate problem, 3 = severe problem). A summary index with a 
maximum score of 1 can be derived from these 5 dimensions by conversion with a table of 
scores. The maximum score of 1 indicates the best health state, by contrast with the scores of 
individual questions, where higher scores indicate more severe or frequent problems. In addition, 
there is a visual analog scale to indicate the general health status with 100 indicating the best 
health status. 
8.1.10. 
Short Form 12 
The acute Short Form-12v2™ Health Survey (SF-12v2) is a 7-day recall, 12-item subset of the 
Short Form-36v2™ questionnaire that measures the same 8 domains of health including physical 
functioning, role-function, bodily pain, general health, vitality, social functioning, 
role-emotional, and mental health. The SF-12 is a brief, reliable measure of overall health status 
with scores general for physical component and mental components. Each item on the SF-12 is 
score on 3- or 5-item Likert scales and the domains scales are standardized to 0 to 100 scale 
where 0 represents lower quality of life and 100 represents higher quality of life. The subject 
should complete the questionnaire before site personnel performs any clinic assessments and 
before any interaction with the site personnel has occurred to avoid biasing the subject’s 
response. 
8.1.11. 
Hidradenitis Suppurativa Quality of Life 
Subjects will complete Hidradenitis Suppurativa Quality of Life (HiSQOL) scale at the 
designated study visits listed in the SoA (Section 1.3). The 17-item HiSQOL questionnaire 
includes 4 symptom items, 8 activity-adaptation items, and 5 psychosocial items. The item scores 
are summed to create a total ranging from 0 to 68, with higher scores indicating a more severe 
impact on health-related quality of life (Kirby et al, 2020). 
8.1.12. 
Hidradenitis Suppurativa Patient Global Impression of Change 
Subjects will complete the HS Patient Global Impression of Change (PGIC) questionnaire at the 
designated study visits listed in SoA (Section 1.3). The PGIC consists of 1 self-administered item 
that assesses change in the severity of skin pain due to HS. Subjects are asked to indicate their 
impression of change compared with their last visit, except at Week 12 and Week 16, when the 
subject will also be asked about their pain since treatment began on this study. 
8.1.13. 
Hospital Anxiety and Depression Scale 
In addition, depression and anxiety will be monitored with the Hospital Anxiety and Depression 
Scale (HADS). The HADS was chosen for its well-established psychometric properties and its 
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(Langley et al, 2010). The HADS scores for anxiety and for depression range from 0 to 21 with 
higher scores indicating a worse state. A score < 8 is considered to be normal, whereas a score of 
≥ 11 is considered clinically significant (Snaith, 2003). 
The HADS questionnaire will be presented in local language and is to be completed by the 
subject at the designated study visits listed in the SoA (Section 1.3). 
8.1.14. 
Photography (Optional Substudy) 
Subjects at a subset of selected sites will be invited to participate in an optional substudy to have 
photographs taken of their disease response during the study. Subjects who consent to this 
optional substudy will have photographs taken at the designated study visits listed in the SoA 
(Section 1.3). Sites participating in the photography substudy will be trained and receive 
standardized photographic equipment from the central photography vendor. Sites will submit the 
digital images to the central photography vendor. Photographs will be anonymized. 
8.2. 
Safety Assessments 
Planned timepoints for all safety assessments are provided in the SoA (Section 1.3). 
8.2.1. 
Medical and Medication History 
A complete medical and medication history, as well as a history of alcohol and nicotine use, will 
be obtained from each subject during the screening visit. An updated medical history will be 
obtained at the Day 1 visit prior to study drug administration and updated as necessary 
throughout the study. 
A HS history obtained at screening will capture date of onset of HS. 
Any systemic treatment for HS since diagnosis will be recorded. Any other treatment used for 
any other reasons (including contraception) prior to randomization will be recorded as per eCRF 
Completion Guidelines. 
Any changes in concomitant medication will be recorded throughout the study, from Day 1 until 
end of study at Week 59. 
8.2.2. 
Physical Examinations 
A complete physical examination will include, at a minimum, assessments of the dermatological, 
cardiovascular, respiratory, gastrointestinal, and neurological systems. 
Clinically significant findings observed prior to the first dose of study drug should be listed as 
medical history in the CRF and reported as AEs if observed after first dose of study drug. 
8.2.3. 
Vital Signs 
Vital signs will be measured in a sitting position after 5 minutes rest and will include 
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8.2.4. 
Physical Measurements 
Height and weight measurements are to be performed at the timepoints indicated in the SoA and 
data will be recorded in centimeters and kilograms respectively. Height and weight are to be 
measured without shoes. 
8.2.5. 
Electrocardiograms 
Triplicate 12-lead ECGs will be obtained after subject has been supine for at least 5 minutes as 
outlined in the SoA (Section 1.3) using an ECG machine that automatically calculates the heart 
rate and measures PR, QRS, and QT intervals. 
8.2.6. 
Chest X-ray 
Only subjects with a positive or indeterminate IGRA TB test will undergo a chest x-ray 
(posterior/anterior or anterior/posterior). A subject must not be included in the study if his/her 
chest x-ray reveals evidence of active TB (refer to Section 5.1). Women of childbearing potential 
must have a negative pregnancy test before an x-ray is performed. 
8.2.7. 
Clinical Safety Laboratory Tests 
• See Section 10.2 for the list of clinical laboratory tests to be performed and the SoA 
(Section 1.3) for the timing and frequency. 
• The investigator must review the laboratory results, document this review, and record any 
clinically significant changes occurring during the study as an AE. The laboratory results 
must be retained with source documents. 
• Abnormal laboratory findings associated with the underlying disease are not considered 
clinically significant unless judged by the investigator to be more severe than expected for 
the subject’s condition. 
• All laboratory tests with values considered clinically significantly abnormal during 
participation in the study or within 8 weeks after the last dose of study drug should be 
repeated until the values return to normal or baseline or are no longer considered clinically 
significant by the investigator or medical monitor. 
o If clinically significant values do not return to normal/baseline within a period of time 
judged reasonable by the investigator, the etiology should be identified, and the sponsor 
notified. 
o All protocol-required laboratory tests, as defined in Section 10.2, must be conducted in 
accordance with the laboratory manual and the SoA (Section 1.3). 
o If laboratory values from non-protocol-specified laboratory tests performed at the 
institution’s local laboratory require a change in subject management or are considered 
clinically significant by the investigator (eg, SAE or AE or dose modification), then the 
results must be recorded within source documents. 
8.2.8. 
Tuberculosis Test 
Determination of TB status will be required before the subject’s inclusion in the study. An IGRA 
TB test (QuantiFERON recommended), chest x-ray (unless already performed within 3 months 
prior to screening), and examination for signs and symptoms of TB will be performed on each 

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subject to assess TB status at screening. Table 8-1 provides TB terms and definitions for the 
purpose of the study, and Table 8-2 provides guidance for handling various TB test results. 
Table 8-1. Tuberculosis Terms and Definitions 
Term 
Definition 
Known TB 
• Active TB or presence of symptoms (pulmonary 
or extra-pulmonary) consistent with TB 
• History of active TB or findings consistent with 
TB, unless there is documented evidence of 
completed treatment and clinical resolution, by a 
TB specialist 
• Radiological or other imaging modalities findings 
consistent with previously active TB that is not 
reported in the subject’s medical history 
High risk of acquiring TB 
• Close contact with a person with active TB within 
the 3 months prior to screening 
• Working in or attending a healthcare setting or 
facility housing persons with TB where there is a 
high risk of transmission 
Latent TB 
• Positive IGRA TB test (or 2 indeterminate IGRA 
TB test results) with absence of symptoms 
(pulmonary or extra-pulmonary) and radiological 
or other imaging modalities findings consistent 
with active TB 
• If available, respiratory or other specimens must 
also be smear and culture negative for TB (Center 
for Disease Control diagnosis of latent TB; 
http://www.cdc.gov/TB/topic /testing/default.htm) 
Nontuberculous mycobacterial infection 
• Clinical manifestation of infection caused by 
mycobacteria species other than M tuberculosis 
CDC = Centers for Disease Control and Prevention; IGRA = interferon-gamma release assay; TB = tuberculosis; WHO = World 
Health Organization 

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Table 8-2. Tuberculosis Testing Results and Required Actions 
Initial IGRA TB Testa Results for Eligibility 
Negative 
Indeterminate 
Positive 
Required action 
No further action is needed, subject 
is eligible for the study 
Repeat IGRA TB test (must be 
completed during the protocol-
defined screening period) 
• If negative, no further action is 
needed, subject is eligible for 
the study 
• If indeterminate or positive, 
subject must be referred to a 
TB specialist for further 
evaluation 
o 
If subject is determined to 
be negative for latent or 
active TB by the TB 
specialist, subject is 
eligible for the study 
o 
If diagnosed with active 
TB by the TB specialist, 
subject is NOT eligible 
for the study 
o 
If diagnosed with latent 
TB by the TB specialist, 
eligibility must be 
discussed with the 
medical monitor and the 
subject must complete at 
least 4 weeks of 
prophylaxis in accordance 
with WHO/CDC 
guidelines prior to first 
dose of study drug and 
continue to the full 
treatment course to 
completion 
• Subject must be referred to a 
TB specialist for further 
evaluation 
o 
If subject is determined to 
be negative for latent or 
active TB by the TB 
specialist, subject is 
eligible for the study 
o 
If diagnosed with active 
TB by the TB specialist, 
subject is NOT eligible for 
the study 
o 
If diagnosed with latent 
TB by the TB specialist, to 
be eligible for the study, 
subject must complete at 
least 4 weeks of 
prophylaxis in accordance 
with WHO/CDC 
guidelines prior to first 
dose of study drug and 
continue to the full 
treatment course to 
completion 
CDC = Centers for Disease Control and Prevention; IGRA = interferon-gamma release assay; TB = tuberculosis; WHO = World 
Health Organization 
aQuantiFERON recommended. 
8.2.9. 
Pregnancy Testing 
• Refer to Section 5.1 Inclusion Criteria for pregnancy testing entry criteria. 
• Pregnancy testing in WOCBP will be conducted throughout the study. A serum pregnancy 
test will be performed at screening and urine pregnancy testing will be performed at 
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• Additional serum or urine pregnancy tests may be performed, as determined necessary by the 
investigator or required by local regulation or regulatory agency, to establish the absence of 
pregnancy at any time during the subject’s participation in the study. 
• The investigator is responsible for review of medical history, menstrual history, and recent 
sexual activity to decrease the risk for inclusion of a woman with an early undetected 
pregnancy. 
8.2.10. 
IBD Screening 
Given that subjects with HS appear to have a higher lifetime risk of IBD compared with the 
general population and given that approved IL-17 inhibitors have reported worsening or new 
onset IBD in clinical studies, all subjects will be screened for IBD by history and a subset will 
undergo additional laboratory screening. 
During screening, all subjects will be assessed for the following symptoms within the last year: 
• prolonged or recurrent diarrhea without established etiology 
• prolonged or recurrent abdominal pain without established etiology 
• blood in stool without established etiology 
• any other symptoms in the opinion of the investigator that may be suggestive of IBD. If 
any are marked affirmative, a fecal calprotectin test must be performed. 
• If the resulting fecal calprotectin level is > 150 to 500 µg/g, the subject must undergo a 
gastrointestinal consultation and obtain documented approval from the gastrointestinal 
consultation to enroll in the clinical study before continuing with the screening process. If 
the consultation cannot be completed within the screening window, the subject will be 
screen failed but may rescreen. 
• Fecal calprotectin levels > 500 µg/g will be exclusionary. 
8.2.11. 
Suicidal Ideation and Behavior Risk Monitoring 
Subjects with HS may occasionally develop suicidal ideation or behavior. Furthermore, suicidal 
ideation and behavior has been identified as a potential risk with other IL-17 class products. 
Suicidal ideation and behavior will be assessed during the study by trained study personnel using 
the C-SSRS. The visits at which the C-SSRS assessments will be performed are specified in the 
SoA (Section 1.3). The C-SSRS is a standardized and validated instrument developed for the 
assessment of the severity and frequency of suicidal ideation and behavior (Posner et al, 2011). 
Subjects respond to standardized clinical questions that are presented in a uniform fashion. The 
C-SSRS defines 5 subtypes of suicidal ideation and behavior in addition to self-injurious 
behavior with no suicidal intent. The C-SSRS takes approximately 3 to 10 minutes to complete. 
Subjects should be monitored appropriately and observed closely for suicidal ideation and 
behavior or any other unusual changes in behavior, especially at the beginning and end of the 
course of study drug. Subjects who experience signs of suicidal ideation and behavior should 
undergo a risk assessment which may or may not include examination by a mental health care 

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professional. All factors contributing to suicidal ideation and behavior should be evaluated and 
consideration should be given to discontinuation of the study drug. 
8.2.12. 
Home Study Drug Administration Diary 
The subject (or caregiver/designee) will complete a diary for every study dose taken outside of 
the site (ie, at home). The study drug should be administered on the dates as directed by the site 
staff. Information regarding the study drug administration (eg, date and time of study drug 
administration, if the full dose was administered) will be recorded on the study drug 
administration diary. Instructions on proper study drug administration will be provided to the 
subject (caregiver/designee). Subjects will be instructed to call the site if they are having 
problems administering the study drug or have missed or delayed administering a dose. Subjects 
will be instructed to bring the study drug administration diary to each study visit. 
8.3. 
Adverse Events, Serious Adverse Events, and Other Safety 
Reporting 
The definitions of AEs and SAEs can be found in Section 10.3.1 and Section 10.3.2, 
respectively. 
Adverse events will be reported by the subject (or, when appropriate, by a caregiver, surrogate, 
or the subject’s legally authorized representative). 
The investigator and any qualified designees are responsible for detecting, documenting, and 
recording events that meet the definition of an AE or SAE. The investigator is responsible for 
following up on all AEs that are serious, considered related to the study drug or study 
procedures, or that caused the subject to discontinue the study drug (see Section 7). 
Currently all SAEs require immediate reporting by the investigator to ACELYRIN. There are no 
SAEs that do not require immediate reporting. If this changes during the study, the protocol will 
be amended, as appropriate. 
The method of recording, evaluating, and assessing causality of AEs and SAEs and the 
procedures for completing and transmitting SAE reports are provided in Section 10.3.3 and 
Section 10.3.4, respectively. 
8.3.1. 
Time Period and Frequency for Collecting Adverse Event and Serious Adverse 
Event Information 
All SAEs will be collected from the signing of the ICF until the 8-week follow-up visit as 
specified in the SoA (Section 1.3). 
All AEs will be collected from the first dose of study drug until 4 weeks after the last dose of 
study drug as specified in the SoA (Section 1.3). 
Medical occurrences that begin before the start of study drug but after obtaining informed 
consent will be recorded as medical history/current medical conditions, not as AEs. 
All SAEs will be recorded and reported to the sponsor or designee immediately and under no 
circumstance should this exceed 24 hours from investigator’s knowledge of the event, as 

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indicated in Section 10.3.4. The investigator will submit any updated SAE data to the sponsor 
within 24 hours of it being available. 
Investigators are not obligated to actively seek information on AEs or SAEs after the conclusion 
of the study participation. However, if the investigator learns of any SAE, including death, at any 
time after a subject has been discharged from the study, and he/she considers the event to be 
reasonably related to the study drug or study participation, the investigator must promptly notify 
the sponsor or its designee (see Section 10.3.4). 
8.3.2. 
Method of Detecting Adverse Events and Serious Adverse Events 
Care will be taken not to introduce bias when detecting AEs and/or SAEs. Open-ended and 
non-leading verbal questioning of the subject is the preferred method to inquire about AE 
occurrences. 
8.3.3. 
Follow-up of Adverse Events and Serious Adverse Events 
After the initial AE/SAE report, the investigator is required to proactively follow each subject at 
subsequent visits/contacts. All SAEs and AEs of special interest (as defined in Section 10.3.2 
and Section 8.3.6, respectively) will be followed until resolution, stabilization, the event is 
otherwise explained, or the subject is lost to follow-up (as defined in Section 7.3). Further 
information on follow-up procedures is provided in Section 10.3.3. 
8.3.4. 
Regulatory Reporting Requirements for Serious Adverse Events 
• Prompt notification by the investigator to the sponsor of an SAE is essential so that legal 
obligations and ethical responsibilities toward the safety of subjects and the safety of a study 
drug under clinical investigation are met. 
• The sponsor has a legal responsibility to notify both the local regulatory authority and other 
regulatory agencies about the safety of a study drug under clinical investigation. The sponsor 
will comply with country-specific regulatory requirements relating to safety reporting to the 
regulatory authority, IRBs/IECs, and investigators. This includes reporting of events that 
meet suspected unexpected serious adverse reaction (SUSAR) criteria via Eudravigilance, as 
applicable. 
• An investigator who receives an investigator safety report describing an SAE or other 
specific safety information (eg, summary or listing of SAEs) from the sponsor will review 
and then file it along with the Investigator’s Brochure and will notify the IRB/IEC, if 
appropriate according to local requirements. 
• Investigator safety reports must be prepared for SUSARs according to local regulatory 
requirements and sponsor policy and forwarded to investigators as necessary. 
8.3.5. 
Pregnancy 
• Details of all pregnancies in female subjects and, if indicated, female partners of male 
subjects will be collected after the start of study drug and until 8 weeks after the last dose of 
study drug. 
• If a pregnancy is reported, the investigator will record pregnancy information on the 
appropriate form and submit it to the sponsor or designee within 24 hours of learning of the 

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female subject or female partner of male subject (after obtaining the necessary signed 
informed consent from the female partner) pregnancy. 
• While pregnancy itself is not considered to be an AE or SAE, any pregnancy complication or 
elective termination of a pregnancy for medical reasons will be reported as an AE or SAE. 
• Abnormal pregnancy outcomes (eg, spontaneous abortion, fetal death, stillbirth, congenital 
anomalies, ectopic pregnancy) are considered SAEs and will be reported as such. 
• The subject/pregnant female partner will be followed to determine the outcome of the 
pregnancy. The investigator will collect follow-up information on the subject/pregnant 
female partner and the neonate, and the information will be forwarded to the sponsor or 
designee. 
• Any post-study pregnancy-related SAE considered reasonably related to the study drug by 
the investigator will be reported to the sponsor or designee as described in Section 8.3.4. 
While the investigator is not obligated to actively seek this information in former study 
subjects/pregnant female partner, they may learn of an SAE through spontaneous reporting. 
• Any female subject who becomes pregnant while participating in the study will discontinue 
study drug. 
8.3.6. 
Adverse Events of Special Interest 
Based on the class effects or potential risks with IL-17 inhibitors, the following events of special 
interest will be monitored: 
• Candida infection 
• IBD 
• Suicidal ideation 
• Malignancies 
• Major adverse cardiovascular and cerebrovascular events (cerebrovascular accident and 
transient ischemic attack, non-fatal myocardial infarction or unstable angina, and 
cardiovascular death) 
• TB 
• Infections (opportunistic, serious, or fungal only) 
• Cytopenias (anemia, neutropenia, lymphopenia, monocytopenia, thrombocytopenia) 
• Systemic hypersensitivity reactions. 
8.3.7. 
Overdose 
These events are only considered AEs or SAEs if there are associated clinical signs and 
symptoms or if the act of taking the excess medicine itself is an AE or SAE (eg, suicide attempt). 
Refer to Section 6.7. 

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If an overdose occurs associated with an SAE in the course of the study, then the investigator 
follows the immediate safety reporting requirement for SAE with describing the overdose in an 
SAE description. 
8.4. 
Pharmacokinetics 
• Blood samples will be collected for measurement of plasma concentrations of izokibep as 
specified in the SoA (Section 1.3). 
• Instructions for the collection and handling of biological samples will be provided in the 
Laboratory Manual by the sponsor or designee. The actual date and time (24-hour clock 
time) of each sample will be recorded. 
• Samples will be used to evaluate the PK of izokibep. Each plasma sample may be divided 
into 2 aliquots (1 each for PK and a backup). Samples collected for analyses of izokibep 
(plasma) concentration may also be used to evaluate safety or efficacy aspects related to 
concerns arising during or after the study. 
• Genetic analyses will not be performed on these plasma samples. 
• Study drug concentration information will not be reported to investigative sites. 
• Pharmacokinetic samples collected may be used for assay validation and related assay 
development purposes. 
• Pharmacokinetic samples will be shipped frozen from clinical sites to the central laboratory 
and later shipped from central laboratory to the PK laboratory for analysis. The PK plasma 
samples will be stored in a secure storage space with adequate measures to protect 
confidentiality. 
• The PK samples will be retained while research on izokibep or study drugs of this class or 
HS continues but no longer than 20 years or other period as per local requirements. 
8.5. 
Genetics 
Genetics are not evaluated in this study. 
8.6. 
Biomarkers (United States Only) 
• Serum and blood (PAXgene) samples will be collected for exploratory biomarker analysis as 
specified in the SoA (Section 1.3). These samples will be tested by the sponsor or sponsor’s 
designee. 
• Instructions for the collection and handling of biological samples will be provided in the 
Laboratory Manual by the sponsor or designee. 
• Samples will be used to assess biomarkers of anti-IL-17A treatment and biomarkers 
associated with HS efficacy. mRNA transcriptomic analyses will be performed on the whole 
blood PAXgene samples. 
• Exploratory biomarker samples will be shipped frozen from clinical sites to the central 
laboratory and later shipped from central laboratory to the laboratory for analysis. The 

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samples will be stored in a secure storage space with adequate measures to protect 
confidentiality. 
• The exploratory samples will be retained while research on izokibep or study drugs of this 
class or HS continues but no longer than 20 years or other period as per local requirements. 
8.7. 
Immunogenicity Assessments 
• Antibodies to izokibep will be evaluated in serum samples collected from all subjects 
according to the SoA (Section 1.3). Additionally, serum samples should also be collected at 
the final visit from subjects who discontinued study drug or were withdrawn from the study. 
These samples will be tested by the sponsor or sponsor’s designee. 
• Instructions for the collection and handling of biological samples will be provided in the 
Laboratory Manual by the sponsor or designee. 
• Samples testing positive for binding antibodies may be further characterized and may be 
tested for neutralizing antibodies. 
• The detection and characterization of antibodies to izokibep will be performed using a 
validated assay method by or under the supervision of the sponsor. 
• Antibody samples collected may be used for assay validation and related assay development 
purposes. 
• ADA serum samples will be shipped frozen from clinical sites to the central laboratory and 
later shipped from the central laboratory to the ADA laboratory for analysis. The ADA serum 
samples will be stored in a secure storage space with adequate measures to protect 
confidentiality. 
• Samples will be retained while research on izokibep or study drugs of this class or HS 
continues but no longer than 20 years or other period as per local requirements. 
8.8. 
Health Economics 
Refer to Section 8.1.9 EQ-5D and Section 8.1.10 Short Form-12v2. 

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9. 
Statistical Considerations 
This section is a summary of the planned statistical analyses of the most important endpoints 
including primary and secondary endpoints. 
9.1. 
Statistical Hypotheses 
The primary objective of this study is to demonstrate that izokibep is superior to placebo in the 
proportion of subjects achieving HiSCR75 at Week 12 of the study. The statistical null and 
alternative hypotheses to be used to assess the primary objective are: 
H0: πABY – πPBO = 0 
HA: πABY – πPBO ≠ 0 
where πABY and πPBO are the proportion achieving HiSCR75 at Week 12 among subjects randomly 
assigned to receive izokibep and placebo, respectively. 
Analogous statistical hypotheses will be used for the secondary objective of assessing the 
percentage of subjects who achieve HiSCR90 at Week 12, who achieve HiSCR100 at Week 12, 
who achieve HiSCR50 at Week 12, who experience a flare through Week 12, who achieve an 
AN count of 0, 1, or 2 at Week 12, or who achieve a 3-point reduction in pain NRS at Week 12. 
For the last secondary objective, to demonstrate that izokibep is efficacious compared with 
placebo, as measured by change in DLQI, the statistical null and alternative hypotheses are: 
H0: µABY – µPBO = 0 
HA: µABY – µPBO ≠ 0 
where µABY and µPBO are the mean changes in DLQI from baseline to Week 12 among subjects 
randomly assigned to receive izokibep and placebo, respectively. 
9.1.1. 
Multiplicity Adjustment and Type I Error Rate 
Hypotheses tested will be adjusted to control the familywise error rate in the strong sense at 
α = 0.050, 2-sided. 
As described in Section 9.4, an adjustment of 0.0001 will be made to account for the unblinded 
data summaries reviewed by the DMC. The hypotheses will therefore be tested at α = 0.0499. 
The statistical comparisons for the primary efficacy endpoint and the secondary endpoints, all at 
Week 12, will be carried out in sequential order. The primary endpoint, comparing izokibep to 
placebo, will be tested first, with significance concluded if p < 0.0499. Testing of secondary 
endpoints will only be carried out if all prior tests, including the test of the primary endpoint, 
first show significance with p < 0.0499. If all prior tests are significant, testing will proceed in 
the following order: 
• The first secondary endpoint, proportion of subjects achieving HiSCR90 at Week 12. 
• The second secondary endpoint, proportion of subjects achieving HiSCR100 at Week 12. 

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• The third secondary endpoint, proportion of subjects achieving HiSCR50 at Week 12. 
• The fourth secondary endpoint, proportion of subjects who experience flares through 
Week 12. 
• The fifth secondary endpoint, change in DLQI from baseline to Week 12. 
• The sixth secondary endpoint, achieving AN count of 0, 1, or 2 at Week 12 among subjects 
with baseline Hurley Stage II. 
• The seventh secondary endpoint, proportion of subjects who achieve a reduction in pain NRS 
of at least 3 points from baseline to Week 12, among subjects with a pain NRS score of at 
least 4 at baseline. 
If a null hypothesis is not rejected, p-values for subsequent hypotheses in the sequence will be 
reported as nominal and will not be used to assess objectives or make determinations of efficacy. 
9.2. 
Analysis Sets 
The following analysis sets will be used for reporting. 
Full Analysis Set (FAS) 
For assessing the primary and secondary efficacy objectives, all subjects randomized will be 
included in the analyses as FAS. Intercurrent events such as missed assessments, missed or 
discontinued treatment, and protocol deviations, will be addressed as described in the definition 
of the estimands in Section 9.3. Subjects will be included according to randomized treatment. 
For assessment of the sixth secondary endpoint, the proportion of subjects who achieve AN of 0, 
1, or 2 at Week 12, only the subset of subjects in the FAS who have Hurley Stage II at baseline 
will be included in the assessment. For the seventh secondary endpoint, achievement of a 
reduction in pain NRS of at least 3 points, only the subset of subjects in the FAS who have pain 
NRS of at least 4 at baseline will be included in this assessment. Both will be called the FAS for 
reporting purposes. 
The FAS analyses for timepoints after Week 16 will include all subjects who receive any amount 
of izokibep at or after Week 16. Subjects will be summarized according to the original 
randomization (izokibep or placebo) for such summaries. 
Safety Analysis Set 
For assessing the safety objectives, all subjects randomized who receive at least 1 administration 
of test material will be included in the summaries and analyses. If a subject receives incorrect 
study treatment, that subject will be grouped according to treatment received. If a subject 
receives both treatments, the subject will be grouped with the treatment received most often. 
The safety analysis set summaries for timepoints after the Week 16 visit will include all subjects 
who receive any amount of izokibep at or after Week 16 visit. Subjects will be summarized 
according to the original randomization (izokibep or placebo) for such summaries. 

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PK Analysis Set 
For assessing PK parameters, all subjects who receive at least 1 administration of test material 
and have at least 1 sample collected and analyzed for drug concentration will be included in 
summaries and analyses. 
ADA Analysis Set 
For assessing ADA, all subjects who receive at least 1 administration of test material and have 
both baseline ADA and at least 1 post-dose ADA measurement will be included in summaries 
and analyses. 
9.3. 
Statistical Analyses 
9.3.1. 
General Considerations 
All data collected will be summarized by planned timepoint without imputation. Continuous data 
will be summarized with count, mean, median, standard deviation, minimum, and maximum. 
Change from baseline will additionally include standard error. Categorical data will be 
summarized with count and percent. Time to event data will be summarized with product-limit 
estimators of median and quartiles. 
All hypothesis tests will be reported with 2-sided p-values. All CIs will be 2-sided with nominal 
95% coverage. Hypotheses tested will be adjusted to control the familywise error rate in the 
strong sense at α = 0.050, 2-sided. All hypothesis tests will use a type I error rate of 5%. 
Data will be summarized by planned timepoint, using data collected at the visit. Study day will 
be calculated as post-baseline date minus randomization date, plus 1 (except that study day for 
pre-randomization dates will not include the plus 1). Day range windows will not be applied for 
summaries (but may be applied for protocol deviations). Baseline values will be the last value 
collected before randomization and change from baseline will be calculated as post-baseline 
value minus baseline value. 
Stratified tests will use the 4 strata from the randomization process. If a subject is incorrectly 
classified during the randomization process, the analysis will use the correct classification, not 
the classification used during randomization. 
After Week 16, efficacy and safety data will be summarized. Data for subjects who were 
randomly assigned to receive placebo during the first 16 weeks will be summarized separately 
from data for subjects who were randomly assigned to receive izokibep during the first 16 weeks. 
Subgroup analyses (including, age, race, sex, baseline disease characteristics, geography, 
concomitant antibiotic use, and other factors) will be reported. 
Any deviation from the planned analyses made after breaking the blind will be documented in 
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9.3.2. 
Primary Endpoint and Estimand 
The primary endpoint is HiSCR75, the proportion of subjects who achieve at least a 75% 
reduction from baseline in the total AN count, with no increase from baseline in abscess or 
draining fistula count, as defined in Section 8.1.1. The primary timepoint for analysis is 
Week 12. 
The treatment policy strategy approach for the estimand will be used in general for intercurrent 
events, so subjects will be included using observed data at Week 12 regardless of treatment 
compliance, use of rescue medications except as noted below, or any other protocol deviations. 
The null hypothesis of equal response rates will compare the izokibep group to the placebo 
group. A stratified test of response rates will be used. Within each of the 4 strata used for 
randomization, the response rate for each treatment group and corresponding standard error will 
be calculated. The difference in response rates (risk difference) will be calculated for each 
stratum. The common risk difference among the 4 strata and associated standard error will be 
estimated by combining the observed risk differences using Cochran-Mantel-Haenszel 
weighting. The estimated risk difference divided by the standard error will be used as the test 
statistic and a p-value calculated assuming that the test statistic follows a standard normal 
distribution under the null hypothesis. Analyses at other timepoints when data to calculate the 
HiSCR75 scores are collected will also be presented using the same methodology. The p-values 
from earlier timepoints will be presented for descriptive purposes and will not be part of the 
alpha-preserving multiple testing strategy. 
Subjects who receive antibiotic therapy that could affect HS will be included in the primary 
analysis by assigning non-response at subsequent timepoints. A list of all oral antibiotic therapy 
that results in such imputation will be finalized after review of all oral antibiotic therapy received 
by any subject and before unblinding of the study, and will include tetracycline, clindamycin, 
and possibly other products. Similarly, subjects who discontinue treatment due to an AE or lack 
of efficacy, and subsequently have missing efficacy responses, will be included by imputing 
non-response. Other subjects with missing data will have efficacy data imputed using multiple 
imputation. The imputation model will use data from placebo subjects and include baseline 
characteristics and demographics, factors used for stratification of randomization, and observed 
efficacy at earlier timepoints, and will be fully defined before unblinding. The model will impute 
components of the primary endpoint (abscess count, inflammatory nodule count, and draining 
tunnel count) separately. The imputation model will be run multiple times (eg, 100 times) and 
the results analyzed for each run using the primary analysis methodology. Results from all runs 
will be combined using Rubin’s rule, resulting in a single point estimate, a single CI, and a single 
p-value. The number of subjects imputed with non-response imputation and the number imputed 
with multiple imputation will be tabulated with reasons for imputation at Week 12. 
Supportive analyses using other assumptions about ICEs will also be reported. These will be 
defined before the database is locked and treatment assignments are unblinded. 
9.3.3. 
Secondary Endpoints and Estimands 
The secondary endpoints are HiSCR90; HiSCR100; HiSCR50; percentage of subjects who 
experience flare through Week 12; percentage of subjects with baseline Hurley Stage II who 
achieved an AN count of 0, 1, or 2; percentage of subjects with a decrease in pain score of at 

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least 3 points at Week 12; and change in DLQI at Week 12. The treatment policy strategy will be 
used to construct estimands for each secondary endpoint analogously to the primary estimand, 
except as noted below. 
The secondary endpoint of experiencing flare will be analyzed using multiple imputation for 
subjects who have missing assessments. All subjects with missing abscess, inflammatory nodule, 
and draining tunnel counts will be included using multiple imputation, analogously to the 
analysis of the primary endpoint. 
The secondary endpoint of pain score will use a hybrid estimand, with treatment policy strategy 
used for most ICEs and hypothetical strategy used to account for use of prohibited pain 
medications due to non-HS-related pain, when taken near a visit. All pain scores after such use of 
prohibited pain medication will be omitted from the dataset and replaced via multiple imputation 
in a model analogous to that used for multiple imputation of the primary endpoint. The imputed 
pain scores will be used to determine which subjects meet the criteria of a decrease of at least 
3 points. Sensitivity analyses will include a nonlinear mixed effects model with repeated 
measures (MMRM), using observed change in pain score at all scheduled post-baseline 
assessments. 
The secondary endpoints of percentage of subjects who experience flare and percentage of 
subjects with baseline Hurley Stage II who achieved AN count of 0, 1, or 2 will be analyzed 
analogously to the primary endpoint. Only subjects with Hurley Stage II at baseline will be 
included in the hypothesis test for AN count, while other subjects will be summarized, and a p-
value reported for descriptive use only. 
The secondary endpoint of change in DLQI will use MMRM to account for subjects with 
missing data. The factors used for stratification will be included as covariates in the model, as 
will baseline DLQI score. 
9.3.4. 
Exploratory Endpoints 
Exploratory endpoints will be analyzed analogously to primary and secondary endpoints with the 
same strategies for ICEs. Binary endpoints will be analyzed with a stratified test of risk 
difference and continuous endpoints will be analyzed with an MMRM model. Continuous data at 
timepoints before and including the primary timepoint will use all data from planned assessments 
up to and including the primary timepoint; continuous data after the primary timepoint will use 
all data from all planned assessments. 
Pharmacokinetic concentration data will be summarized at all planned collections with mean, 
geometric mean, minimum, and maximum. Pharmacokinetic data collected from this study may 
also be combined with PK data collected from other studies for comprehensive modeling of drug 
concentrations. 
9.3.5. 
Safety Analyses 
Safety data will include summaries of exposure, AEs, SAEs, and laboratory data. No inferential 
statistics (p-values) will be reported for safety data. 

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Exposure will include the number of doses administered (including complete and incomplete 
doses) and reasons for missed or incomplete doses. Exposure will be reported through the 
planned collection at Week 12, Week 16, and for the entire study. For subjects assigned to 
receive placebo who later receive izokibep, exposure will further be summarized by placebo and 
izokibep. 
Adverse events and SAEs reported before the first administration of study drug will be listed. All 
summaries will include only treatment-emergent events. The number of subjects who report 1 or 
more AEs, the number who report 1 or more severe AEs, the number who report 1 or more 
SAEs, and the number who report 1 or more AEs that leads to discontinuation of study drug will 
be summarized by treatment during the primary phase of the study and overall. Subjects who 
receive placebo during the primary phase will additionally be summarized by phase 
(placebo-controlled and after crossing over to active). 
Laboratory data and vital signs will be summarized at each planned collection timepoint. 
Subjects with positive ADA results will be summarized by timepoint. 
9.4. 
Interim Analysis and Early Stopping Rules 
Data may be summarized for a DMC at regular intervals during the study to ensure safety of 
study subjects. The type I error rate for hypothesis tests at the end of the study will be decreased 
by 0.0001 to account for each interim summary of unblinded data. An assessment for futility 
may be performed at the DMC, when at least 100 randomized subjects (50 subjects in each arm) 
have completed the Week 12 visit or permanently discontinued the study early. 
The futility assessment, if undertaken, will be based on a combination of the calculated 
conditional power and the observed difference between treatment groups of selected study 
efficacy endpoints, calculated using the interim data cut. 
The details of the futility analysis plan including futility criteria; logistics of generating data, 
reviewing unblinded data; and making nonbinding recommendation to sponsor will be 
documented before any unblinding of the data. The sponsor will not see the unblinded data 
unless the DMC determines it is necessary for the sponsor to understand a recommendation to 
stop the study for futility. 
After all subjects have had an opportunity to complete the Week 12 visit (complete the visit, or 
complete a subsequent visit, or permanently discontinue the study before Week 12), the primary 
endpoint analyses may be conducted. Site staff, and all sponsor staff who interact with site staff, 
will remain blinded to individual subject treatment assignment until the final subject has 
completed the final visit and the database lock has occurred. 
At various points after the primary analysis, analyses of data collected after Week 12 will be 
reported for regulatory submission purposes or other reasons. These analyses will be 
documented. No adjustment to the type I error rate will be applied due to these summaries, 
because the inferential statistics will already have been determined. 

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9.5. 
Sample Size Determination 
In prior studies (Glatt et al, 2021; Kirby et al, 2022), HiSCR75 response rates among placebo 
recipients after 12 to 16 weeks of treatment have been approximately 10% to 20%. At Week 12 
in this study, HiSCR75 response rates are expected to be 15% for placebo recipients and 35% for 
izokibep recipients. With 125 subjects receiving each treatment, this study will have 
approximately 95% power to demonstrate a difference in HiSCR75 response rates between arms. 
This calculation uses an unstratified test, with α = 0.05, two-sided. 

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10. 
Supporting Documentation and Operational Considerations 
10.1. 
Regulatory, Ethical, and Study Oversight Considerations 
10.1.1. 
Regulatory and Ethical Considerations 
• This study will be conducted in accordance with the protocol and with the following: 
o Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical 
Sciences (CIOMS) international ethical guidelines. 
o Applicable International Council for Harmonisation (ICH) Good Clinical Practice 
(GCP) guidelines. 
o Applicable laws and regulations, including 21 Code of Federal Regulations (CFR) 
and European Regulation 536/2014 for clinical studies. 
• The protocol, protocol amendments, ICF, Investigator’s Brochure, 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 study is initiated. 
• Any amendments to the protocol will require IRB/IEC approval before implementation of 
changes made to the study design, except for changes necessary to eliminate an immediate 
hazard to study subjects. 
• Protocols and any substantial amendments to the protocol will require health authority 
approval prior to initiation except for changes necessary to eliminate an immediate hazard to 
study subjects. 
• The investigator will be responsible for the following, as applicable: 
o Providing written summaries of the status of the study to the IRB/IEC annually or 
more frequently in accordance with the requirements, policies, and procedures 
established by the IRB/IEC. 
o Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures. 
o Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR, ICH guidelines, the IRB/IEC, European 
Regulation 536/2014 for clinical studies, and all other applicable local regulations. 
10.1.2. 
Financial Disclosure 
Investigators and subinvestigators 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 study and for 1 year after 
completion of the study. 

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10.1.3. 
Informed Consent Process 
• The investigator or the investigator’s representative will explain, in a language and at a level 
of complexity understandable by the subject, the nature of the study, including the risks and 
benefits, to the potential subject and answer all questions regarding the study and its 
alternatives. 
• Potential subjects must be informed that their participation is voluntary, and they may 
withdraw their consent to participate in the study at any time. They will be required to sign 
and date a statement of informed consent that meets the requirements of 21 CFR 50, Clinical 
trials Regulation (EU) 536/20141, local regulations, ICH guidelines, privacy and data 
protection requirements, where applicable, and the IRB/IEC or study center. 
• The medical record must include a statement that written informed consent was obtained 
before the subject was enrolled in the study and the date the written consent was obtained. 
The authorized person obtaining the informed consent must also sign the ICF. 
• If the ICF is amended during the study, subjects must be reconsented to the most current 
version of the ICF(s) during their participation in the study. 
• A copy of the ICF(s) must be provided to the subject. 
• A subject who is rescreened is not required to sign another ICF if the rescreening occurs 
within 30 days from the previous ICF signature date. 
10.1.4. 
Data Protection 
• Subjects will be assigned a unique identifier to pseudonymize the subject records by the 
IXRS. Any subject records or datasets that are transferred to the sponsor will contain the 
identifier only; subject names or any information which would make the subject identifiable 
will not be transferred to the sponsor. 
• Subjects’ data will be captured in an electronic cloud-based data capture system. Access to 
the production servers requires multi-factor authentication through a virtual private network 
and all communication is encrypted. Access to the public facing application is encrypted via 
transport layer security encryption protocols. Transport layer security is provisioned to help 
ensure secure transmission over the Internet for the platform. In addition, a virtual firewall is 
utilized to restrict access. 
• The subject must be informed that the subject’s personal study-related data will be used by 
the sponsor in accordance with the data protection and privacy principles set forth by 
institutional policies, regulatory agencies, local and country-specific laws, regulations, and 
guidelines including the European Union General Data Protection Regulation [2016/679] 
(“GDPR”) or other country-specific privacy regulation. The level of disclosure must also be 
explained to the subject who will be required to give consent for their data to be used as 
described in the informed consent. 
• The subject must be informed that their personal study-related data may be transferred by or 
on behalf of the sponsor to countries outside the country where the study subject’s personal 
data is being collected. In any event, these transfers will be in accordance with all applicable 
data protection laws including Article 46 of the GDPR, and that the sponsor has implemented 
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times to the same level as required in the country where the study subject’s personal data is 
being collected. Subjects will also be advised of their rights under applicable data protection 
laws to access and control their personal data and documented via informed consent. 
• The subject must be informed that the subject’s 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 competent regulatory authorities, 
including in the United States. 
• The sponsor and investigator will implement appropriate measures to monitor and identify 
any breach of security leading to accidental or unlawful destruction, loss, alteration, 
unauthorized disclosure or access to that data (a “data breach”). In the event of a personal 
data breach, the sponsor and investigator will take appropriate measures to address the 
breach, including measures to mitigate its adverse effects. The investigator will notify the 
sponsor or its designee without undue delay after having become aware of the breach. Such 
notification will contain the details of a contact point where more information can be 
obtained, a description of the nature of the breach (including, where possible, categories and 
approximate number of data subjects and personal data records concerned), its likely 
consequences, and the measures taken or proposed to address the breach including, where 
appropriate, measures to mitigate its possible adverse effects. Upon becoming aware of any 
data breach, the sponsor and investigator will ensure that all competent data protection 
authorities are notified of the breach, where required by local regulations. Where feasible and 
permissible by applicable law, such notification will occur within 72 hours of the responsible 
controller becoming aware of the data breach. Such notification will contain the details of a 
contact point where more information can be obtained, a description of the nature of the 
breach in accordance with applicable laws, its likely consequences, and the measures taken 
or proposed to address the breach including, where appropriate, measures to mitigate its 
possible adverse effects. 
• Considering the nature, scope, context and purpose of the processing, and the risks for the 
rights and freedoms of natural persons, the investigator will implement technical and 
organizational measures to ensure adequate security and confidentiality of the data. Such 
measures will include without limitation pseudonymization and data encryption in transit and 
at rest. Additional measures may include measures to prevent unauthorized physical access to 
premises and facilities holding personal data; logical identity and access management 
procedures to prevent authorized users from accessing data beyond their authorized access 
rights and the unauthorized input, reading, copying, removal, modification, or disclosure of 
personal data; and network perimeter and endpoint protection using firewalls and other 
intrusion detection systems. All such measures will be in accordance with regularly updated 
documented policies taking account of the state-of-the-art, and regular training of all 
personnel responsible for the processing of personal data. 
10.1.5. 
Dissemination of Clinical Study Data 
The results of the study will be reported in a clinical study report generated by the sponsor and 
will contain eCRF data from all sites that participated in the study. Recruitment performance or 
specific expertise related to the nature and the key assessment parameters of the study will be 
used to determine a coordinating investigator. Study subject identifiers will not be used in 
publication of results. Any work created in connection with the performance of the study and 

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contained in the data that can benefit from copyright protection (except any publication by the 
investigator see Section 10.1.9) shall be the property of the sponsor as author and owner of 
copyright in such work. 
Registration of Clinical Studies and Disclosure of Results 
The sponsor will register and/or disclose the existence of and the results of clinical studies as 
required by law including posting company-sponsored study information on the US National 
Institutes of Health’s website www.clinicaltrials.gov. 
10.1.6. 
Monitoring and Data Quality Assurance 
• Qualified, assigned monitors from the sponsor (or designee) will conduct regular on-site and 
remote monitoring visits to monitor various aspects of the study. These visits and 
communications, along with regular inspection of the eCRFs, will be conducted to assess 
subject enrollment, compliance with protocol procedures, completeness and accuracy of data 
entered on the eCRFs, verification of data against source documents, and occurrence of AEs, 
etc. The investigator must provide the monitor with full access to all source and study 
documents. 
• All subject data relating to the study will be recorded on eCRFs 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 signing the eCRF. 
• Guidance on completion of eCRFs will be provided. 
• The investigator or site staff will promptly report to the sponsor (or designee) all deviations 
that occur at their clinical site, and report protocol deviations to their IRB/EC according to 
local requirements. 
• Sponsor (or designee) may audit investigator sites regarding, but not limited to, the informed 
consent process, presence of required documents, adherence to protocol, accountability and 
storage of drug supplies, comparison between eCRF with source documents, etc. All medical 
records and study-related documents must be available for audit, and the investigator and 
study staff agree to participate and cooperate in audits conducted in a reasonable manner. 
• Government regulatory authorities and ethics committees may also inspect the investigator 
site during or after the study. The investigator or designee should contact the sponsor (or 
designee) immediately if this occurs. The investigator must cooperate fully with regulatory 
authorities or other audits conducted in a reasonable manner. 
• The sponsor or designee is responsible for the data management of this study, including 
quality checking of the data. 
• The sponsor assumes accountability for actions delegated to other individuals (eg, CROs). 
• Records and documents, including signed ICFs, pertaining to the conduct of this study must 
be retained by the investigator until at least 2 years after the last approval of a marketing 
application in an ICH region and until there are no pending or contemplated marketing 
applications in an ICH region or at least 2 years have elapsed since the formal 
discontinuation of clinical development of the study drug. These documents should be 

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retained for a longer period, however, if required by the applicable regulatory requirements 
or by an agreement with the sponsor. 
• 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. 
• Quality Tolerance Limits will be defined before the start of the study and monitored by the 
CRO and sponsor during the study. They will also be reported in the clinical study report. 
10.1.7. 
Source Documents 
• Source documents provide evidence for the existence of the subject and substantiate the 
integrity of the data collected. Source documents are filed at the investigator’s site. 
• Source documents contain the results of original observations and activities of a clinical 
investigation. Source documents include, but are not limited to, medical records (progress 
notes), computer printouts, screening logs, and recorded data from automated instruments. 
Information from medical records and other source documents will be promptly transcribed 
to the appropriate section of the eCRF. The eCRF is not considered and should not be used as 
source documentation. 
• Data reported on the eCRF that are transcribed from source documents must be consistent 
with the source documents or the discrepancies must be explained. The investigator may 
need to request previous medical records or transfer records, depending on the study. Also, 
current medical records must be available. 
• The investigator must maintain accurate documentation (source data) that supports the 
information entered in the eCRF. 
• Study monitors will perform ongoing source data verification to confirm that data entered 
into the eCRF by authorized site personnel are accurate, complete, and verifiable from source 
documents; that the safety and rights of subjects are being protected; and that the study is 
being conducted in accordance with the currently approved protocol and any other study 
agreements, ICH GCP, and all applicable regulatory requirements. 
10.1.8. 
Study and Site Start and Closure 
Study Start 
The study start date is the date on which the first subject is enrolled into the study. 
Study/Site Termination 
The sponsor or designee reserves the right to close the site or terminate the study at any time for 
any reason at the sole discretion of the sponsor. Sites will be closed upon study completion. A 
site is considered closed when all required documents and study supplies have been collected and 
a study-site closure visit has been performed. 
The investigator may initiate study-site closure at any time, provided there is reasonable cause 
and sufficient notice is given in advance of the intended termination. 

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Reasons for the early closure of a site by the sponsor or investigator may include but are not 
limited to: 
For study termination: 
• Discontinuation of further study drug development 
For site termination: 
• 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 or no recruitment (evaluated after a reasonable amount of time) of subjects by 
the investigator 
• Total number of subjects included earlier than expected 
If the study is prematurely terminated or suspended, the sponsor shall promptly inform the 
investigators, the IECs/IRBs, the regulatory authorities, and any CRO(s) used in the study of the 
reason for termination or suspension, as specified by the applicable regulatory requirements. The 
investigator should promptly inform the subject and should assure appropriate subject therapy 
and/or follow-up. 
10.1.9. 
Publication Policy 
• The results of this study may be published or presented at scientific meetings. If this is 
foreseen, the investigator agrees to submit all manuscripts or abstracts to the sponsor before 
submission. This allows the sponsor to protect proprietary information and to provide 
comments. 
• The sponsor will comply with the requirements for publication of study results. In 
accordance with standard editorial and ethical practice, the sponsor will generally support 
publication of multicenter studies only in their entirety and not as individual site data. In this 
case, a coordinating investigator will be designated by mutual agreement. 
• Authorship will be determined by mutual agreement and in line with International Committee 
of Medical Journal Editors’ authorship requirements. 

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10.2. 
Clinical Laboratory Tests 
• The tests detailed in Table 10-1 will be performed by the central laboratory. 
• Protocol-specific requirements for inclusion or exclusion of subjects are detailed in 
Section 5. 
• Additional tests may be performed at any time during the study as determined necessary by 
the investigator or required by local regulations. 
• All study-required laboratory tests will be performed by a central laboratory, with the 
exception of: 
o urine pregnancy test 
• Investigators must document their review of each laboratory safety report. 

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10.3. 
AEs and SAEs: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting 
10.3.1. 
Definition of AE 
AE Definition 
• An AE is any untoward medical occurrence in a clinical study subject, temporally associated 
with the use of study drug, whether or not considered related to the study drug. 
• NOTE: An AE can therefore be any unfavorable and unintended sign (including an abnormal 
laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the 
use of study drug. 
Events Meeting the AE Definition 
• Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or other 
safety assessments (eg, ECG, radiological scans, vital signs measurements), including those 
that worsen from baseline, considered clinically significant in the medical and scientific 
judgment of the investigator (ie, not related to progression of underlying disease, or more 
severe than expected for the subject’s condition) 
• Exacerbation of a chronic or intermittent pre-existing condition including either an increase 
in frequency and/or intensity of the condition 
• New condition detected or diagnosed after study drug administration even though it may 
have been present before the start of the study 
• Signs, symptoms, or the clinical sequelae of a suspected drug-drug interaction 
• Signs, symptoms, or the clinical sequelae of a suspected overdose of either study drug or a 
concomitant medication. Overdose per se will not be reported as an AE/SAE unless it is an 
intentional overdose taken with possible suicidal/self-harming intent. Such overdoses should 
be reported regardless of sequelae 
• Lack of efficacy or failure of expected pharmacological action per se will not be reported as 
an AE or SAE. Such instances will be captured in the efficacy assessments. However, the 
signs, symptoms, and/or clinical sequelae resulting from lack of efficacy will be reported as 
AE or SAE if they fulfill the definition of an AE or SAE 
 
Events NOT Meeting the AE Definition 
• Pre-existing diseases, conditions, or laboratory abnormalities present or detected before the 
first dose of study drug that do not worsen; such events should be recorded as medical history 
eCRF 
• Any clinically significant abnormal laboratory findings or other abnormal safety assessments 
that are associated with the underlying disease, unless judged by the investigator to be more 
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• The disease/disorder being studied or expected progression, signs, or symptoms of the 
disease/disorder being studied, unless more severe than expected for the subject’s condition 
• Medical or surgical procedure (eg, endoscopy, appendectomy): The condition that leads to 
the procedure is the AE 
• Situations in which an untoward medical occurrence did not occur (social and/or convenience 
admission to a hospital) 
• Anticipated day-to-day fluctuations of pre-existing disease(s) or condition(s) present or 
detected at the start of the study that do not worsen. 
10.3.2. 
Definition of SAE 
An SAE is defined as any untoward medical occurrence that, at any dose, meets one or more of 
the criteria listed: 
a. Results in death 
b. Is life threatening 
The term life threatening in the definition of serious refers to an event in which the subject was 
at risk of death at the time of the event. It does not refer to an event, which hypothetically might 
have caused death, if it were more severe. 
c. 
Requires inpatient hospitalization or prolongation of existing hospitalization 
• In general, hospitalization signifies that the subject has been admitted (usually involving 
at least an overnight stay) at the hospital or emergency ward for observation and/or 
treatment that would not have been appropriate in the physician’s office or outpatient 
setting. Complications that occur during hospitalization are AEs. If a complication 
prolongs hospitalization or fulfills any other serious criteria, the event is serious. When in 
doubt as to whether hospitalization occurred or was necessary, the AE should be 
considered serious. 
• Hospitalization for elective treatment of a pre-existing condition that did not worsen from 
baseline is not considered an AE. 
d. Results in persistent or significant disability/incapacity 
• The term disability means a substantial disruption of a person’s ability to conduct normal 
life functions. 
• This definition is not intended to include experiences of relatively minor medical 
significance such as uncomplicated headache, nausea, vomiting, diarrhea, influenza, and 
accidental trauma (eg, sprained ankle) that may interfere with or prevent everyday life 
functions but do not constitute a substantial disruption. 
e. 
Is a congenital anomaly/birth defect 

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f. 
Other situations: 
• Medical or scientific judgment should be exercised by the investigator in deciding 
whether SAE reporting is appropriate in other situations such as important medical events 
that may not be immediately life threatening or result in death or hospitalization but may 
jeopardize the subject or may require medical or surgical intervention to prevent one of 
the other outcomes listed in the above definition. These events should usually be 
considered serious. 
o Examples of such events include invasive or malignant cancers, intensive 
treatment in an emergency room or at home for allergic bronchospasm, blood 
dyscrasias, convulsions not resulting in hospitalization, or development of 
intervention dependency or intervention abuse. 
10.3.3. 
Recording and Follow-up of AE and/or SAE 
AE and SAE Recording 
• When an AE/SAE occurs, it is the responsibility of the investigator to review all 
documentation (eg, hospital progress notes, laboratory reports, and diagnostics reports) 
related to the event. 
• The investigator will then record all relevant AE/SAE information in the required eCRF 
and SAE Report Form (if applicable). 
• It is not acceptable for the investigator to send photocopies of the subject’s medical 
records to the sponsor or designee of in lieu of completion of the required eCRF and SAE 
Report Form (if applicable). 
• There may be instances when copies of medical records for certain cases are requested by 
the sponsor or designee. In this case, all subject identifiers, with the exception of the 
subject number, should be fully redacted on the copies of the medical records before 
submission. 
• The investigator will attempt to establish a diagnosis of the event based on signs, 
symptoms, and/or other clinical information. Whenever possible, the diagnosis (not the 
individual signs/symptoms) will be documented as the AE/SAE. 
Assessment of Severity 
The investigator is responsible for assessing the severity for each AE and SAE according to the 
National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) 
version 5.0: 
• Mild (Grade 1): Asymptomatic or mild symptoms; clinical or diagnostic observations only; 
intervention not indicated. 
• Moderate (Grade 2): Minimal, local, or noninvasive intervention indicated; limiting 
age-appropriate instrumental activities of daily living (ADL). Instrumental ADL refers to 
preparing meals, shopping for groceries or clothes, using the telephone, managing money, 
etc. 

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• Severe (Grade 3): Severe or medically significant but not immediately life-threatening; 
hospitalization or prolongation of hospitalization indicated; disabling, limiting self-care 
ADL. Self-care ADL refers to bathing, dressing and undressing, feeding self, using the toilet, 
taking medications, and not bedridden. 
• Life-threatening (Grade 4): Life-threatening consequences; urgent intervention indicated. 
• Death (Grade 5): Events that result in death. 
Many common AEs are able to be graded according to CTCAE. Adverse events that do not have 
a corresponding CTCAE term will be assessed according to the general guidelines for grading 
used in CTCAE version 5.0 as stated above. Additional considerations when assessing severity 
are outlined below: 
• The seriousness of an AE should not be confused with its severity. Severity is a measure 
of intensity (eg, Grades 1 through 5 or mild, moderate, severe), whereas seriousness is 
based on subject/event outcome as defined by the criteria in Section 10.3.2. 
• It is important to distinguish between category (AE versus SAE) and intensity (Grades 1 
to 5) of AEs. Seriousness, not severity, serves as a guide for defining regulatory reporting 
obligations. 
• An AE of severe intensity is not necessarily considered serious. For example, nausea that 
persists for several hours may be considered grade 3 nausea, but not an SAE. On the 
other hand, minor cardiac chest pain that results in hospitalization may be considered 
grade 1 but would be an SAE. 
Assessment of Causality 
• The investigator is obligated to assess the relationship between study drug and each 
occurrence of each AE/SAE. The investigator will use clinical judgment in the assessment of 
causality according to the following categories: 
• Not related: Another documented cause of the AE is most plausible; and/or the 
administration of study drug and occurrence of AE are not reasonably related in time; 
and/or causal relationship is considered biologically implausible. 
• Related: There is clear evidence to suggest that the AE is more likely explained by the 
study drug and other possible contributing factors can be ruled out; a causal relationship 
is clinically/biologically plausible, and there exists a plausible time sequence between 
onset of the AE and administration of the study drug. 
Additional factors in the assessment of causality include the following: 
• A reasonable possibility of a relationship conveys that there are facts, evidence, and/or 
arguments to suggest a causal relationship, rather than a relationship cannot be ruled out. 
• Alternative causes, such as underlying disease(s), concomitant therapy, and other risk 
factors, as well as the temporal relationship of the event to study drug administration, will 
be considered and investigated. 
• The investigator will also consult the Investigator’s Brochure and/or product information, 
for marketed products, in his/her assessment. 

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• For each AE/SAE, the investigator must document in the medical notes that he/she has 
reviewed the AE/SAE and has provided an assessment of causality. 
• There may be situations in which an SAE has occurred, and the investigator has minimal 
information to include in the initial report to the sponsor or designee. However, it is very 
important that the investigator always assess causality for every event before the initial 
transmission of the SAE data to the sponsor or designee. 
• The investigator may change his/her opinion of causality considering follow-up 
information and send an SAE follow-up report with the updated causality assessment. 
The causality assessment is one of the criteria used when determining regulatory reporting 
requirements. 
Follow-up of AEs and SAEs 
• The investigator is obligated to perform or arrange for the conduct of supplemental 
measurements and/or evaluations as medically indicated or as requested by the sponsor or 
designee to elucidate the nature and/or causality of the AE or SAE as fully as possible. 
This may include additional laboratory tests or investigations, histopathological 
examinations, or consultation with other health care professionals. 
• If a subject dies during participation in the study or during a recognized follow-up period, 
the investigator will provide the sponsor or designee with a copy of any postmortem 
findings including histopathology. 
• New or updated information will be recorded in the originally submitted documents. 
• The investigator will submit any updated SAE data to the sponsor/designee within 
24 hours of receipt of the information. 
10.3.4. 
Reporting of SAEs 
SAE Reporting to Sponsor/Designee via the SAE Report Form 
• The primary mechanism for reporting an SAE to the sponsor/designee will be the SAE 
Report Form. 
• All SAEs will be recorded and reported to the sponsor or designee immediately and under 
no circumstance should this exceed 24 hours from investigator’s knowledge of the event. 
• Email transmission of the SAE Report Form is the preferred method to transmit this 
information to the sponsor/designee. 
• In the rare circumstance email is not available, the SAE Report Form may be sent by 
facsimile as a backup reporting method. 
• Investigator signature is required to be collected on the SAE Report Form prior to 
submission. With rare exception, the form may be sent without signature to meet the 
reporting deadline; however, investigator signature is required to be obtained as soon as 
possible after submission. 
• Contacts for SAE reporting can be found on the SAE Report Form. 

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10.3.5. 
AEs and Laboratory Abnormalities That Could Lead to Discontinuation of 
Study Drug 
The following lists should not be viewed as exhaustive but serve to provide examples of AEs and 
laboratory abnormalities that could lead to a decision to discontinue the subject from study drug. 
AEs: 
• SAE or AE CTCAE version 5.0 grade 3, considered related to study drug 
• serious infections (eg, sepsis) that cannot be adequately controlled within 4 weeks by 
anti-infective treatment or may put the subject at risk by continued administration of study 
drug, as determined by the investigator 
• malignancy, except for localized non-melanoma skin cancer or carcinoma in situ of the 
cervix 
• CTCAE version 5.0 grade 3 or higher cardiovascular AE(s) that would put the subject at risk 
by continued administration of study drug, as determined by the investigator or medical 
monitor 
• CTCAE version 5.0 grade 4 AE (life-threatening consequences; urgent intervention 
indicated, considered related to study drug) 
• subject develops an illness where, in the opinion of the investigator, the risk of continuing 
with study drug outweighs the potential benefit 
• subject with newly diagnosed IBD during the study 
• active suicidal ideation as indicated by a positive response (Yes) to questions 4 or 5 of the 
C-SSRS, or any suicidal behavior since the last visit 
• liver chemistry stopping criteria (see Section 7.1.1) 
Laboratory abnormalities: 
• neutrophil count < 1.0 × 109/L 
• platelets < 50 000/mm3 
• hemoglobin < 8.5 g/dL with decrease of at least 2 g/dL from baseline 
• creatinine >2 × baseline 
• any other laboratory abnormality that may put the subject at risk by continued administration 
of study drug, as determined by the investigator 

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10.4. 
Contraceptive and Barrier Guidance 
10.4.1. 
Definitions 
Woman of Childbearing Potential 
Women in the following categories are considered WOCBP (fertile): 
1. Following menarche 
• From the time of menarche until becoming postmenopausal unless permanently sterile 
(see below) 
• A postmenopausal state is defined as no menses for 12 months without an alternative 
medical cause. 
o A high follicle-stimulating hormone (FSH) level in the postmenopausal range may be 
used to confirm a postmenopausal state in women not using hormonal contraception 
or hormonal replacement therapy (HRT). However, in the absence of 12 months of 
amenorrhea, confirmation with more than 1 FSH measurement is required. 
o Females on HRT and whose menopausal status is in doubt will be required to use one 
of the non-estrogen hormonal highly effective contraception methods if they wish to 
continue their HRT during the study. Otherwise, they must discontinue HRT to allow 
confirmation of postmenopausal status before study enrollment. 
• Permanent sterilization methods (for the purpose of this study) include: 
o Documented hysterectomy 
o Documented bilateral salpingectomy 
o Documented bilateral oophorectomy 
o For individuals with permanent infertility due to an alternate medical cause other than 
the above (eg, Mullerian agenesis, androgen insensitivity, gonadal dysgenesis), 
investigator’s discretion should be applied to determining study entry. 
Note: Documentation can come from the site personnel’s review of the subject’s medical 
records, medical examination, or medical history interview. 
• If fertility is unclear (eg, amenorrhea in adolescents or athletes) and a menstrual cycle 
cannot be confirmed before first dose of study drug, additional evaluation should be 
considered.

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10.4.2. 
Contraception Requirements 
 
CONTRACEPTIVESa ALLOWED DURING THE STUDY INCLUDE: 
Highly Effective Methodsb That Have Low User Dependency Failure rate of < 1% per year when used 
consistently and correctly. 
• Implantable progestogen-only hormone contraception associated with inhibition of ovulation 
• Intrauterine device  
• Intrauterine hormone-releasing system  
• Bilateral tubal occlusion 
• Azoospermic partner (vasectomized or due to a medical cause) 
Azoospermia is a highly effective contraceptive method provided that the partner is the sole sexual partner of 
the woman of childbearing potential and the absence of sperm has been confirmed. If not, an additional 
highly effective method of contraception should be used. Spermatogenesis cycle is approximately 90 days. 
Note: Documentation of azoospermia for a male subject can come from the site personnel’s review of the 
subject’s medical records, medical examination, or medical history interview. 
Highly Effective Methodsb That Are User Dependent Failure rate of < 1% per year when used consistently 
and correctly. 
Combined (estrogen- and progestogen-containing) hormonal contraception associated with inhibition of 
ovulation 
− oral 
− intravaginal 
− transdermal 
− injectable 
Progestogen-only hormone contraception associated with inhibition of ovulation 
− oral 
− injectable 
Sexual abstinence 
Sexual abstinence is considered a highly effective method only if defined as refraining from heterosexual 
intercourse during the entire period of risk associated with the study drug. The reliability of sexual abstinence 
needs to be evaluated in relation to the duration of the study and the preferred and usual lifestyle of the subject.) 
Effective Methodsc That Are Not Considered Highly Effective Failure rate of ≥ 1% per year when used 
consistently and correctly. 
• Progestogen-only oral hormonal contraception where inhibition of ovulation is not the primary mode of 
action 
• Male or female condom with or without spermicide 
• Cervical cap, diaphragm, or sponge with spermicide 
• A combination of male condom with either cervical cap, diaphragm, or sponge with spermicide 
(double-barrier methods) 

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a Contraceptive use by men or women should be consistent with local regulations regarding the use of 
contraceptive methods for those participating in clinical studies. 
b Failure rate of < 1% per year when used consistently and correctly. Typical use failure rates differ from those 
when used consistently and correctly. 
c Considered effective but not highly effective - failure rate of ≥ 1% per year. 
Note: Periodic abstinence (calendar, symptothermal, post-ovulation methods), withdrawal (coitus interruptus), 
spermicides only, and lactational amenorrhea method are not acceptable methods of contraception. Male 
condoms and female condoms should not be used together (due to risk of failure from friction). 
 

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10.5. 
Liver Safety: Required Actions and Follow-up Assessments 
Phase 2 liver chemistry stopping criteria are designed to assure subject safety and to evaluate 
liver event etiology. The guidelines provided below are based on the European Association for 
the Study of the Liver Clinical Practice Guidelines: Drug-induced Liver Injury (2019) and Food 
and Drug Administration 2009 Guidance for Industry Drug-induced Liver Injury: Premarketing 
Clinical Evaluation. 
Phase 2 Liver Chemistry Stopping Criteria and Follow-up Assessments 
 
 
Liver Chemistry Stopping Criteria 
ALT or AST-absolute ALT or AST  5 × ULN 
ALT or AST Increase ALT or AST  3 × ULN persists for  4 weeks 
Bilirubina,b 
ALT or AST  3 × ULN and total bilirubin 2 × ULN (> 35% direct 
bilirubin) 
International 
Normalized Ratio 
(INR)b 
ALT or AST  3 × ULN and INR > 1.5 
Cannot Monitor 
ALT or AST  3 × ULN and cannot be monitored twice weekly for 
4 weeks 
Symptomaticc 
ALT or AST  3 × ULN associated with symptoms (new or 
worsening) believed to be related to liver injury or hypersensitivity 
 
Suggested Actions, Monitoring, and Follow-up Assessments  
Actions 
Follow-up Assessments 
• Immediately discontinue study drug. 
• Report the event to the sponsor/designee 
within 24 hours. 
• Complete an SAE eCRF if the event met the 
criteria for an SAE.b 
• Perform follow-up assessments as described 
in the Follow-up Assessment column. 
• Monitor the subject until liver chemistry test 
abnormalities resolve, stabilize, or return to 
baseline. 
• Viral hepatitis serology.c 
• Obtain blood samples for PK analysis 
after the most recent dose.d 
• Obtain serum creatine phosphokinase, 
lactate dehydrogenase, gamma 
glutamyl transferase, glutamate 
dehydrogenase, and serum albumin. 
• Fractionate bilirubin if total bilirubin 
 2 × ULN. 
• Obtain complete blood count with 
differential to assess eosinophilia. 

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MONITORING: 
If ALT or AST  3 × ULN AND total bilirubin 
 2 × ULN or INR > 1.5: 
• Repeat liver chemistry tests (include ALT, 
AST, alkaline phosphatase, total bilirubin, and 
INR) and perform liver event follow-up 
assessments within 24 hours. 
• Monitor subject twice weekly until liver 
chemistry test abnormalities resolve, stabilize, 
or return to baseline. 
• A hepatology consultation is recommended. 
If ALT or AST  3 × ULN AND total bilirubin 
< 2 × ULN and INR 1.5: 
• Repeat liver chemistry tests (include ALT, 
AST, alkaline phosphatase, total bilirubin, and 
INR) and perform liver chemistry follow-up 
assessments within 24 to 72 hours. 
• Monitor subjects twice weekly until liver 
chemistry abnormalities resolve, stabilize, or 
return to baseline, or the study drug has been 
discontinued; then decrease monitoring to 
once weekly or less. 
• Do not restart/rechallenge subject with study 
drug unless allowed per-protocol and sponsor 
approval is granted. 
 
• Record the appearance or worsening of 
clinical symptoms of liver injury, or 
hypersensitivity, on the eCRF. 
• Record use of concomitant 
medications (including acetaminophen, 
herbal remedies, and other 
over-the-counter medications) on the 
concomitant medications eCRF. 
• Record alcohol use on the liver event 
alcohol intake form. 
If ALT or AST  3 × ULN AND total 
bilirubin  2 × ULN or INR > 1.5 obtain 
the following in addition to the 
assessments listed above: 
• Antinuclear antibody, anti-smooth 
muscle antibody, type 1 anti-liver 
kidney microsomal antibodies, and 
quantitative total immunoglobulin G or 
gamma globulins. 
• Serum acetaminophen adduct assay, 
when available, to assess potential 
acetaminophen contribution to liver 
injury in subjects with definite or likely 
acetaminophen use in the preceding 
week. 
• Liver imaging (ultrasound, magnetic 
resonance, or computerized 
tomography) to evaluate liver disease. 
• Liver biopsy may be considered and 
discussed with local specialist if 
available, for instance: 
o In subjects when serology raises 
the possibility of autoimmune 
hepatitis. 
o In subjects when suspected 
drug-induced liver injury 
progresses or fails to resolve on 
withdrawal of study drug. 

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o In subjects with acute or chronic 
atypical presentation. 
• If liver biopsy conducted provides 
biopsy information. 
Abbreviation: ALT = alanine transaminase; AST = aspartate transaminase; eCRF = electronic case report form; 
PK = pharmacokinetic; SAE = serious adverse event; ULN = upper limit of normal. 
a Serum bilirubin fractionation should be performed if testing is available. If serum bilirubin fractionation testing is unavailable, 
record the absence/presence of detectable urinary bilirubin on dipstick which is indicative of direct bilirubin elevations 
suggesting liver injury. 
b All events of ALT or AST 3 × ULN and total bilirubin 2 × ULN (> 35% direct bilirubin) or ALT or AST 3 × ULN and 
INR > 1.5 may indicate severe liver injury (possible “Hy’s Law”) and must be reported to sponsor in an expedited manner 
and as an SAE. The INR stated threshold value will not apply to subjects receiving anticoagulants. 
c New or worsening symptoms believed to be related to liver injury (such as fatigue, nausea, vomiting, right upper quadrant pain 
or tenderness, or jaundice) or hypersensitivity (such as fever, rash, or eosinophilia). 
d Record the date/time of the PK blood sample draw and the date/time of the last dose of study drug prior to the blood sample 
draw on the eCRF. If the date/time of the last dose is unclear, provide the subject’s best approximation. If the date/time of the last 
dose cannot be approximated OR a PK sample cannot be collected in the time period indicated above, do not obtain a PK sample. 
Instructions for sample handling and shipping are in the Study Laboratory Manual. 

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10.6. 
Abbreviations and Definitions 
Abbreviation 
Definition 
ADA 
anti-drug antibody 
ADL 
activities of daily living 
AE  
adverse event 
AN 
abscess and inflammatory nodule 
AUC 
area under the concentration-time curve 
AUC0-∞ 
area under the plasma concentration-time curve extrapolated to infinity 
AUC0-τ 
area under the plasma concentration-time curve over a dosing interval 
BID 
twice daily 
CFR 
Code of Federal Regulations 
CI 
confidence interval 
Cmax 
maximum observed plasma concentration 
COVID-19  
coronavirus disease of 2019 
CRF 
case report form 
CRO  
Contract Research Organization 
C-SSRS  
Columbia-Suicide Severity Rating Scale 
CTCAE 
Common Terminology Criteria for Adverse Events 
CV% 
percent coefficient of variation 
DLQI  
Dermatology Life Quality Index 
DMC  
data monitoring committee 
DNA 
deoxyribonucleic acid 
ECG  
electrocardiogram 
eCRF  
electronic case report form 
EQ-5D 
European Quality of Life-5 Dimensions 
EudraCT  
European Union Drug Regulating Authorities Clinical Trials 
FAS  
Full Analysis Set 
FSH  
follicle-stimulating hormone 
GCP  
Good Clinical Practice 
HADS 
Hospital Anxiety and Depression Scale 
HiSCR50 
hidradenitis suppurativa clinical response 50 is defined as at least a 50% 
reduction from baseline in the total abscess and inflammatory nodule count, 
with no increase from baseline in abscess or draining fistula count 
HiSCR75  
HiSCR75 defined as at least a 75% reduction from baseline in the total abscess 
and inflammatory nodule count, with no increase from baseline in abscess or 
draining fistula count 
HiSCR90  
HiSCR90 defined as at least a 90% reduction from baseline in the total abscess 
and inflammatory nodule count, with no increase from baseline in abscess or 
draining fistula count 
HiSCR100 
HiSCR100 defined as a 100% reduction from baseline in the total abscess and 
inflammatory nodule count, with no increase from baseline in abscess or 
draining fistula count 
HiSQOL 
Hidradenitis Suppurativa Quality of Life 
HIV  
human immunodeficiency virus 
HRT 
hormonal replacement therapy 
HS 
hidradenitis suppurativa 
HS-PGA 
Hidradenitis Suppurativa-Physician’s Global Assessment 
IBD  
inflammatory bowel disease 
ICE 
intercurrent event 
ICH  
International Council for Harmonisation 

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Abbreviation 
Definition 
ICF  
informed consent form 
IGRA 
interferon-gamma release assay 
IEC  
Independent Ethics Committee 
IHS4  
International Hidradenitis Suppurativa Severity Score System 
IL  
interleukin 
IL-17A 
Interleukin-17A 
IMP  
investigational medicinal product 
IRB  
Institutional Review Board 
ISR 
injection site reaction 
IV 
intravenous(ly) 
IXRS  
Interactive Voice/Web Response System 
JAK 
Janus-kinase 
MMRM 
nonlinear mixed effects model with repeated measures 
NOAEL 
no observed adverse effect level 
NRS  
numeric rating scale 
PASI 
Psoriasis Area and Severity Index  
PASI90 
Psoriasis Area and Severity Index response of 90% 
PGIC 
Patient Global Impression of Change 
PK  
pharmacokinetic(s) 
PsA 
psoriatic arthritis 
QW 
every week 
Q2W 
every other week 
SAE  
serious adverse event 
SARS-CoV-2 
severe acute respiratory syndrome coronavirus 
SC 
subcutaneous(ly) 
SF-12v2 
Short Form-12v2™ Health Survey 
SoA 
Schedule of Activities 
SUSAR 
suspected unexpected serious adverse reaction 
t½ 
half-life 
TB 
tuberculosis 
TEAE  
treatment-emergent adverse events 
Th17  
T-helper 17 cell 
tmax 
time to maximum observed concentration 
TNF-α  
tumor necrosis factor-α 
US  
United States 
USPI 
United States prescribing information 
WOCBP 
women of childbearing potential 

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11. 
References 
Izokibep [Investigator’s Brochure] ACELYRIN INC., Version 8.0, 2022 
Ali AA, Seng EK, Alavi A, Lowes MA. Exploring changes in placebo treatment arms in 
hidradenitis suppurativa randomized clinical trials: A systematic review. J Am Acad Dermatol. 
2020;82(1):45-53. 
Alikhan A, Sayed C, Afsaneh A, et al. North American clinical management guidelines for 
hidradenitis suppurativa: A publication from the United States and Canadian hidradenitis 
suppurativa foundations: Part I: Diagnosis, evaluation, and the use of complementary and 
procedural management. J Am Acad Dermatol. 2019;81(1):76-90. 
https://doi.org/10.1016/j.jaad.2019.02.067. 
Casseres RG, Prussick L, Zancanaro P, et al. Secukinumab in the treatment of moderate to severe 
hidradenitis suppurativa: Results of an open-label trial. J Am Acad Dermatol. 
2020;82(6):1524-1526. https://doi.org/10.1016/j.jaad.2020.02.005. 
Deckers IE, Prens EP. An update on medical treatment options for hidradenitis suppurativa. 
Drugs. 2016;76(2):215-229. 
Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI)--a simple practical measure for 
routine clinical use. Clin Exp Dermatol. 1994;19(3):210–216. https://doi.org/10.1111/j.1365-
2230.1994.tb01167.x. 
Frew JW, Navrazhina K, Grand D, et al. The effect of subcutaneous brodalumab on clinical 
disease activity in hidradenitis suppurativa: An open-label cohort study. J Am Acad Dermatol. 
2020;83(5):1341–1348. https://doi.org/10.1016/j.jaad.2020.05.007. 
Garg A, Kirby JS, Lavian J, Lin G, Strunk A. Sex- and age-adjusted population analysis of 
prevalence estimates for hidradenitis suppurativa in the United States. JAMA Dermatol. 
2017;153(8):760-764. https://doi.org/10.1001/jamadermatol.2017.0201. 
Glatt S, Jemec GBE, Forman S, et al. Efficacy and safety of bimekizumab in moderate to severe 
hidradenitis suppurativa: A phase 2, double-blind, placebo-controlled randomized clinical trial. 
JAMA Dermatol. 2021;157(11):1279-1288. https://doi.org/10.1001/jamadermatol.2021.2905. 
Gulliver W, Zouboulis CC, Prens E, Jemec GB, Tzellos T. Evidence-based approach to the 
treatment of hidradenitis suppurativa/acne inversa, based on the European guidelines for 
hidradenitis suppurativa. Rev Endocr Metab Disord. 2016;17(3):343-351. 
HUMIRA® USPI. 2021. “HUMIRA® USPI. 2021, Highlights of Prescribing Information.” 
www.fda.gov/medwatch. 
Hurley H. Axillary hyperhidrosis, apocrine bromhidrosis, hidradenitis suppurativa, and familial l 
benign pemphigus: Surgical approach. In Roenigk RK, Roenigk HH, eds. Dermatological 
Surgery. New York: Marcel Dekker;1989:729-739. 

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Date: 10 May 2024 – Version 2.0 
 
 
105 
Jfri A, Nassim D, O’Brien E, Gulliver W, Nikolakis G, Zouboulis CC. Prevalence of hidradenitis 
suppurativa: A systematic review and meta-regression analysis. JAMA Dermatol. 
2021;157(8):924–931. https://doi.org/10.1001/jamadermatol.2021.1677. 
Kimball AB, Kerdel F, Adams D, et al. Adalimumab for the treatment of moderate to severe 
hidradenitis suppurativa: A parallel randomized trial. Ann Intern Med. 2012;157(12):846-855. 
https://doi.org/10.7326/0003-4819-157-12-201212180-00004. 
Kimball AB, Jemec GB, Yang M, et al. Assessing the validity, responsiveness and 
meaningfulness of the hidradenitis suppurativa clinical response (HiSCR) as the clinical endpoint 
for hidradenitis suppurativa treatment. Br J Dermatol. 2014;171(6):1434-1442. 
https://doi.org/10.1111/bjd.13270. 
Kimball B, Okun MM, Williams DA, et al. Two phase 3 trials of adalimumab for hidradenitis 
suppurativa. N Engl J Med. 2016;375(5):422-434. https://doi.org/10.1056/NEJMoa1504370. 
Kirby JS, Okun MM, Alavi A, et al. Efficacy and safety of the janus kinase 1 inhibitor 
povorcitinib (INCB054707) in patients with hidradenitis suppurativa: Results from a 
randomized, placebo-controlled, phase 2 dose-ranging study. Poster presented at: 31st European 
Academy of Dermatology and Venereology (EADV) Congress, September 7-10, 2022. Milan, 
Italy. 
Kirby JS, Thorlacius L, Villumsen B, et al. The Hidradenitis Suppurativa Quality of Life 
(HiSQOL) Score: Development and validation of a measure for clinical trials. Br J Dermatol. 
2020;183(2):340-348. https://doi.org/10.1111/bjd.18692. 
Langley R, Feldman S, Han C, et al. Ustekinumab significantly improves symptoms of anxiety, 
depression, and skin-related quality of life in patients with moderate-to-severe psoriasis: Results 
from a randomized, double-blind, placebo-controlled phase III trial. J Am Acad of Dermatol. 
2010;63(3):457-465. 
Matusiak Ł, Szczęch J, Bieniek A, Nowicka-Suszko D, Szepietowski JC. Increased interleukin 
(IL)-17 serum levels in patients with hidradenitis suppurativa: Implications for treatment with 
anti-IL-17 agents. J Am Acad Dermatol. 2017;76(4):670-675. 
https://doi.org/10.1016/j.jaad.2016.10.042. 
Posner K, Brown GK, Stanley B, et al. The Columbia-Suicide Severity Rating Scale: Initial 
validity and internal consistency findings from three multisite studies with adolescents and 
adults. Am J Psychiatry. 2011;168(12):1266-1277. 
https://doi.org/10.1176/appi.ajp.2011.10111704. 
Sabat R, Jemec GBE, Matusiak Ł, Kimball AB, Prens E, Wolk K. Hidradenitis suppurativa. 
Nat Rev Dis Primers. 2020;6(1):18. https://doi.org/10.1038/s41572-020-0149-1. 
Sartorius K, Emtestam L, Jemec GBE, Lapins J. Objective scoring of hidradenitis suppurativa 
reflecting the role of tobacco smoking and obesity. Br J Dermatol. 2009;161(4):831-839. 
https://doi.org/10.1111/j.1365-2133.2009.09198.x. 

CONFIDENTIAL 
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Date: 10 May 2024 – Version 2.0 
 
 
106 
Sartorius K, Killasli H, Heilborn J, Jemec GBE, Lapins J, Emtestam L. Interobserver variability 
of clinical scores in hidradenitis suppurativa is low. Br J Dermatol. 2010;162(6):1261-1268. 
https://doi.org/10.1111/j.1365-2133.2010.09715.x. 
Snaith RP. The Hospital Anxiety and Depression Scale. Health Qual Life Outcomes. 2003;1:29. 
https://doi.org/10.1186/1477-7525-1-29. 
Wolk K, Join-Lambert O, Sabat R. Aetiology and pathogenesis of hidradenitis suppurativa. 
Br J Dermatol. 2020;183(6):999-1010. https://doi.org/10.1111/bjd.19556. 
Zouboulis CC, Tzellos T, Kyrgidis A, et al. Development and validation of the International 
Hidradenitis Suppurativa Severity Score System (IHS4), a novel dynamic scoring system to 
assess HS severity. Br J Dermatol. 2017;177(5):1401–1409. https://doi.org/10.1111/bjd.15748. 
Zouboulis CC, Del Marmol V, Mrowietz U, Prens EP, Tzellos T, Jemec GBE. Hidradenitis 
suppurativa/acne inversa: Criteria for diagnosis, severity assessment, classification and disease 
evaluation. Dermatology. 2015;231(2):184-190. https://doi.org/10.1159/000431175. 

Signature Page for VV-CLIN-000136 v1.0
Signature Page for VV-CLIN-000136 v1.0
Approval Task Task
Verdict: Approved
14-May-2024 14:45:43 GMT+0000