A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Efficacy and Safety of Bimekizumab in Subjects With Active Ankylosing Spondylitis
Phase: PHASE3
Conditions: Ankylosing Spondylitis
Sponsor: UCB Biopharma SRL

UCB 
 
16 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
Confidential 
Page 1 of 187 
PROTOCOL AS0011 AMENDMENT 4 
A PHASE 3, MULTICENTER, RANDOMIZED, DOUBLE-BLIND, 
PLACEBO-CONTROLLED STUDY EVALUATING THE 
EFFICACY AND SAFETY OF BIMEKIZUMAB IN SUBJECTS 
WITH ACTIVE ANKYLOSING SPONDYLITIS 
PHASE 3 
EudraCT Number: 2017-003065-95 
IND Number: 128708 
Sponsor: 
UCB Biopharma SRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
Protocol/Amendment number 
Date 
Type of amendment 
Final protocol 
26 Nov 2018 
Not applicable 
Protocol Amendment 0.1 (Japan) 
26 Feb 2019 
Not applicable 
Protocol Amendment 0.2 (Germany) 
23 Apr 2019 
Nonsubstantial 
Protocol Amendment 1 
11 Sep 2019 
Substantial 
Protocol Amendment 1.1 (Japan) 
13 Sep 2019 
Substantial 
Protocol Amendment 1.2 (Germany) 
18 Sep 2019 
Substantial 
Protocol Amendment 2 
17 Oct 2019 
Substantial 
Protocol Amendment 2.1 (Japan) 
24 Oct 2019 
Substantial 
Protocol Amendment 2.2 (Germany) 
29 Oct 2019 
Substantial 
Protocol Amendment 3 
16 Dec 2019 
Nonsubstantial 
Protocol Amendment 3.1 (Japan) 
16 Dec 2019 
Nonsubstantial 
Protocol Amendment 3.2 (Germany) 
16 Dec 2019 
Nonsubstantial 
Protocol Amendment 4 
16 Feb 2021 
Substantial 
Confidential Material 
Confidential 
This document is the property of UCB and may not – in full or in part – be passed on, 
reproduced, published, or otherwise used without the express permission of UCB. 
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16 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
Confidential 
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STUDY CONTACT INFORMATION 
Sponsor 
UCB Biopharma SRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
Sponsor Study Physician 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Straße 10 
40789 Monheim am Rhein 
GERMANY 
Phone: 
 
Clinical Project Manager 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Straße 10 
40789 Monheim am Rhein 
GERMANY 
Phone: 
 
Clinical Trial Biostatistician 
Name: 
 
Address: 
UCB BIOSCIENCES Ltd. 
208 Bath Road 
Slough SL1 3WE 
UNITED KINGDOM 
Phone: 
 
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16 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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Clinical Monitoring Contract Research Organization 
Name: 
PAREXEL International (IRL) Limited-Ireland 
Address: 
Ireland Limited at 70 Sir John Rogerson’s Quay 
Dublin 2 
Ireland 
Phone: 
+353 (1) 477 3171 
Fax: 
+353 (1) 477 3308 
  
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16 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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SERIOUS ADVERSE EVENT REPORTING 
Serious adverse event reporting (24h) 
All SAEs will be reported and transmitted to Patient Safety through the eCRF 
system. The numbers below are to be used to send ancillary documentation only 
(discharge summaries, death certificates, etc) or in the event that the electronic 
reporting (eCRF) is not available. 
Fax 
Europe and Rest of the World: +32 2 386 24 21 
US and Canada: +1 800 880 6949 or +1 866 890 3175 
Email 
Global: DS_ICT@ucb.com  
 
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16 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
Confidential 
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TABLE OF CONTENTS 
LIST OF ABBREVIATIONS .................................................................................................. 12 
1 
SUMMARY ..................................................................................................................... 17 
2 
INTRODUCTION ........................................................................................................... 18 
2.1 Axial spondyloarthritis ..................................................................................................... 18 
2.1.1 
axSpA epidemiology ........................................................................................... 18 
2.1.2 
Current treatments for axSpA .............................................................................. 19 
2.2 Bimekizumab ................................................................................................................... 19 
2.2.1 
Nonclinical ........................................................................................................... 19 
2.2.2 
Clinical ................................................................................................................. 20 
2.2.2.1 
Completed studies ..................................................................................... 20 
2.2.2.2 
Ongoing studies ......................................................................................... 20 
3 
STUDY OBJECTIVE(S) ................................................................................................. 21 
3.1 Primary objective ............................................................................................................. 21 
3.2 Secondary objectives ....................................................................................................... 21 
3.3 Other objectives ............................................................................................................... 21 
4 
STUDY VARIABLES ..................................................................................................... 21 
4.1 Primary variable ............................................................................................................... 21 
4.1.1 
Primary efficacy variable ..................................................................................... 21 
4.2 Secondary variables ......................................................................................................... 21 
4.2.1 
Secondary efficacy variables ............................................................................... 21 
4.2.2 
Secondary safety variables .................................................................................. 22 
4.3 Other variables ................................................................................................................. 22 
4.3.1 
Other efficacy variables ....................................................................................... 22 
4.3.2 
Other safety variables .......................................................................................... 24 
4.3.3 
Pharmacokinetic variable ..................................................................................... 24 
4.3.4 
Pharmacogenomic variables ................................................................................ 24 
4.3.5 
Immunological variables ..................................................................................... 24 
5 
STUDY DESIGN ............................................................................................................. 25 
5.1 Study description ............................................................................................................. 25 
5.1.1 
Screening Period/Baseline ................................................................................... 25 
5.1.1.1 
Within-study rescreening/retesting requirements ...................................... 26 
5.1.1.2 
Cross-study screening requirements .......................................................... 26 
5.1.2 
Treatment Period ................................................................................................. 27 
5.1.2.1 
Double-Blind Treatment Period ................................................................ 27 
5.1.2.2 
Maintenance Period ................................................................................... 28 
5.1.3 
Early Termination Visit ....................................................................................... 28 
5.1.4 
Safety Follow-Up Visit ........................................................................................ 28 
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5.1.5 
Study duration per subject ................................................................................... 29 
5.1.6 
Planned number of subjects and site(s) ............................................................... 29 
5.1.7 
Anticipated regions and countries ....................................................................... 29 
5.2 Schedule of study assessments ......................................................................................... 29 
5.3 Schematic diagram ........................................................................................................... 35 
5.4 Rationale for study design and selection of dose ............................................................. 36 
5.4.1 
Study design ......................................................................................................... 36 
5.4.2 
Dose selection ...................................................................................................... 36 
6 
SELECTION AND WITHDRAWAL OF SUBJECTS ................................................... 36 
6.1 Inclusion criteria .............................................................................................................. 36 
6.2 Exclusion criteria ............................................................................................................. 38 
6.3 Withdrawal criteria .......................................................................................................... 41 
6.3.1 
Potential drug-induced liver injury IMP discontinuation criteria ........................ 44 
7 
STUDY TREATMENTS ................................................................................................. 45 
7.1 Description of investigational medicinal products .......................................................... 45 
7.2 Treatment(s) to be administered ...................................................................................... 45 
7.2.1 
Double-Blind Treatment Period .......................................................................... 45 
7.2.2 
Maintenance Period ............................................................................................. 46 
7.3 Packaging ......................................................................................................................... 46 
7.4 Labeling ........................................................................................................................... 46 
7.5 Handling and storage requirements.................................................................................. 46 
7.6 Drug accountability .......................................................................................................... 46 
7.7 Procedures for monitoring subject compliance ................................................................ 47 
7.8 Concomitant medications/treatments ............................................................................... 47 
7.8.1 
Permitted concomitant treatments (medications and therapies) .......................... 54 
7.8.2 
Prohibited concomitant treatments (medications and therapies) ......................... 54 
7.8.3 
Nonbiologic rescue therapy ................................................................................. 54 
7.8.4 
Vaccines ............................................................................................................... 54 
7.9 Blinding ............................................................................................................................ 54 
7.9.1 
Procedures for maintaining and breaking the treatment blind ............................. 54 
7.9.1.1 
Maintenance of study treatment blind ....................................................... 54 
7.9.1.2 
Breaking the treatment blind in an emergency situation ........................... 55 
7.10 Randomization and numbering of subjects ...................................................................... 55 
8 
STUDY PROCEDURES BY VISIT ............................................................................... 55 
8.1 Screening (Visit 1) ........................................................................................................... 56 
8.2 Baseline (Visit 2, Day 1, first dose of IMP) .................................................................... 57 
8.3 Double-Blind Treatment Period ....................................................................................... 59 
8.3.1 
Week 1 (±3 days) (Visit 3) .................................................................................. 59 
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AS0011 
 
 
 
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8.3.2 
Week 2 (±3 days) (Visit 4) .................................................................................. 59 
8.3.3 
Week 4 (±3 days) (Visit 5) .................................................................................. 59 
8.3.4 
Week 8 (±3 days) (Visit 6) .................................................................................. 60 
8.3.5 
Week 12 (±3 days) (Visit 7) ................................................................................ 61 
8.3.6 
Week 16 (±3 days) (Visit 8) ................................................................................ 61 
8.4 Maintenance Period ......................................................................................................... 63 
8.4.1 
Week 20 (±4 days) (Visit 9) ................................................................................ 63 
8.4.2 
Week 24 (±4 days) (Visit 10) .............................................................................. 63 
8.4.3 
Week 28 (±4 days) (Visit 11) .............................................................................. 64 
8.4.4 
Week 32 (±4 days) (Visit 12) .............................................................................. 64 
8.4.5 
Week 36 (±4 days) (Visit 13) .............................................................................. 65 
8.4.6 
Week 40 (±4 days) (Visit 14) .............................................................................. 66 
8.4.7 
Week 44 (±4 days) (Visit 15) .............................................................................. 66 
8.4.8 
Week 48 (±4 days) (Visit 16) .............................................................................. 66 
8.4.9 
Week 52 (±4 days) (Visit 17) .............................................................................. 67 
8.5 Early Termination Visit (if applicable) ............................................................................ 68 
8.6 Safety Follow-Up Visit (-3 days/+7 days) ....................................................................... 69 
8.7 Unscheduled Visit ............................................................................................................ 69 
9 
ASSESSMENT OF EFFICACY ...................................................................................... 70 
9.1 ASAS20, 40, ASAS 5/6 response, and ASAS-PR ........................................................... 70 
9.2 ASQoL ............................................................................................................................. 71 
9.3 Inflammation – BASDAI (mean of Questions 5 and 6) .................................................. 71 
9.4 BASDAI ........................................................................................................................... 71 
9.5 Physical function – BASFI .............................................................................................. 72 
9.6 SF-36 72 
9.7 MOS-12 ............................................................................................................................ 73 
9.8 PGADA ............................................................................................................................ 73 
9.9 Total and nocturnal spinal pain ........................................................................................ 73 
9.10 FACIT-Fatigue subscale .................................................................................................. 73 
9.11 EQ-5D-3L ........................................................................................................................ 73 
9.12 TJC and SJC (44/44) ........................................................................................................ 74 
9.13 WPAI-SHP v2.0 ............................................................................................................... 74 
9.14 CRP 74 
9.15 ASDAS ............................................................................................................................ 75 
9.16 MASES ............................................................................................................................ 75 
9.17 BASMI ............................................................................................................................. 75 
9.18 PhGADA .......................................................................................................................... 76 
9.19 Occurrence of extra-articular manifestations ................................................................... 76 
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9.20 Imaging evaluation ........................................................................................................... 76 
9.20.1 
Sacroiliac joint x-ray (AP Pelvis Joint Film for modified New York Criteria) ... 76 
9.20.2 
Spine x-ray ........................................................................................................... 77 
9.20.3 
Sacroiliac joint and spine MRI assessment substudy .......................................... 77 
10 ASSESSMENT OF PHARMACOKINETIC AND PHARMACOGENOMIC 
VARIABLES ................................................................................................................... 78 
10.1 Pharmacokinetic variables ............................................................................................... 78 
10.2 Pharmacogenomic variables ............................................................................................ 79 
11 ASSESSMENT OF IMMUNOLOGICAL VARIABLES ............................................... 79 
12 ASSESSMENT OF SAFETY .......................................................................................... 80 
12.1 Adverse events ................................................................................................................. 80 
12.1.1 
Definitions ........................................................................................................... 80 
12.1.1.1 
Adverse event ............................................................................................ 80 
12.1.1.2 
Serious adverse event ................................................................................ 80 
12.1.1.3 
Adverse events of special interest ............................................................. 82 
12.1.1.4 
Other safety topics of interest .................................................................... 83 
12.1.2 
Procedures for reporting and recording adverse events ....................................... 83 
12.1.2.1 
Description of adverse events .................................................................... 83 
12.1.2.2 
Rule for repetition of an adverse event...................................................... 83 
12.1.2.3 
Additional procedures for reporting serious adverse events ..................... 83 
12.1.3 
Follow up of adverse events ................................................................................ 84 
12.2 Pregnancy ......................................................................................................................... 84 
12.3 Suspected transmission of an infectious agent ................................................................. 85 
12.4 Overdose of investigational medicinal product ............................................................... 86 
12.5 Safety signal detection ..................................................................................................... 86 
12.6 Laboratory measurements ................................................................................................ 86 
12.6.1 
Evaluation of PDILI ............................................................................................ 88 
12.6.1.1 
Consultation with Medical Monitor and local hepatologist ...................... 92 
12.6.1.2 
Immediate action: determination of IMP discontinuation ......................... 92 
12.6.1.3 
Testing: identification/exclusion of alternative etiology ........................... 93 
12.6.1.4 
Follow-up evaluation ................................................................................. 95 
12.7 Other safety measurements .............................................................................................. 95 
12.7.1 
Vital signs ............................................................................................................ 95 
12.7.2 
Body weight and height ....................................................................................... 96 
12.7.3 
Physical examination ........................................................................................... 96 
12.7.4 
12-lead electrocardiogram ................................................................................... 96 
12.7.5 
Assessment and management of TB and TB risk factors .................................... 96 
12.7.5.1 
Tuberculosis assessment by IGRA .......................................................... 100 
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Bimekizumab 
AS0011 
 
 
 
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12.7.5.2 
Chest x-ray for tuberculosis .................................................................... 100 
12.7.5.3 
Tuberculosis questionnaire ...................................................................... 100 
12.7.5.4 
Tuberculosis management ....................................................................... 100 
12.7.6 
Pregnancy testing ............................................................................................... 101 
12.7.7 
PHQ-9 ................................................................................................................ 101 
12.7.8 
Assessment of suicidal ideation and behavior ................................................... 101 
13 OTHER STUDY MEASUREMENTS .......................................................................... 102 
13.1 Demography ................................................................................................................... 102 
13.2 Medical and ankylosing spondylitis history .................................................................. 102 
13.3 Prior and concomitant medications ................................................................................ 102 
14 STUDY MANAGEMENT AND ADMINISTRATION ............................................... 102 
14.1 Adherence to protocol .................................................................................................... 102 
14.2 Monitoring ..................................................................................................................... 102 
14.2.1 
Definition of source data ................................................................................... 103 
14.2.2 
Source data verification ..................................................................................... 103 
14.3 Data handling ................................................................................................................. 104 
14.3.1 
Case Report Form completion ........................................................................... 104 
14.3.2 
Database entry and reconciliation ...................................................................... 104 
14.3.3 
Subject Screening and Enrollment log/Subject Identification Code list............ 104 
14.4 Termination of the study ................................................................................................ 104 
14.5 Archiving and data retention .......................................................................................... 105 
14.6 Audit and inspection ...................................................................................................... 105 
14.7 Good Clinical Practice ................................................................................................... 105 
15 STATISTICS ................................................................................................................. 106 
15.1 Definition of analysis sets .............................................................................................. 106 
15.2 General statistical considerations ................................................................................... 106 
15.3 Planned efficacy analyses .............................................................................................. 107 
15.3.1 
Analysis of the primary and secondary efficacy variables ................................ 107 
15.3.1.1 
Analysis of the primary efficacy variable ............................................... 108 
15.3.1.2 
Analyses of the secondary efficacy variables .......................................... 110 
15.3.2 
Analyses of other efficacy variables .................................................................. 111 
15.3.3 
Subgroup analyses ............................................................................................. 112 
15.4 Planned safety analyses .................................................................................................. 112 
15.4.1 
Safety analyses ................................................................................................... 112 
15.5 Planned other analyses ................................................................................................... 113 
15.5.1 
Pharmacokinetic analyses .................................................................................. 113 
15.5.2 
Immunological analyses .................................................................................... 113 
15.6 Handling of protocol deviations ..................................................................................... 113 
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Clinical Study Protocol 
Bimekizumab 
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15.7 Handling of dropouts or missing data ............................................................................ 113 
15.8 Planned interim analysis and data monitoring ............................................................... 114 
15.8.1 
Interim analyses ................................................................................................. 114 
15.8.2 
Data monitoring and Adjudication Committees ................................................ 115 
15.9 Determination of sample size ......................................................................................... 115 
15.9.1 
Power calculation for primary endpoint ............................................................ 115 
15.9.2 
Power calculations for secondary endpoints in the hierarchical testing ............ 116 
16 ETHICS AND REGULATORY REQUIREMENTS .................................................... 117 
16.1 Informed consent ........................................................................................................... 117 
16.2 Subject identification cards ............................................................................................ 118 
16.3 Institutional Review Boards and Independent Ethics Committees ................................ 118 
16.4 Subject privacy ............................................................................................................... 119 
16.5 Protocol amendments ..................................................................................................... 119 
17 FINANCE, INSURANCE, AND PUBLICATION ....................................................... 119 
18 REFERENCES .............................................................................................................. 120 
19 APPENDICES ............................................................................................................... 125 
19.1 ASAS classification criteria for axial SpA .................................................................... 125 
19.2 Modified New York (mNY) Classification Criteria for AS .......................................... 126 
19.3 Protocol Amendment 1 .................................................................................................. 127 
19.4 Protocol Amendment 2 .................................................................................................. 161 
19.5 Protocol Amendment 3 .................................................................................................. 163 
19.6 Protocol Amendment 4 .................................................................................................. 164 
20 DECLARATION AND SIGNATURE OF INVESTIGATOR ..................................... 186 
21 SPONSOR DECLARATION ........................................................................................ 187 
 
LIST OF TABLES 
Table 5‒1: 
Cross-study screening requirements ................................................................ 27 
Table 5-2: 
Schedule of study assessments......................................................................... 30 
Table 7‒1: 
Overview on dosing during the Double-Blind Treatment Period .................... 45 
Table 7‒2: 
Exclusionary, concomitant, and rescue medication ......................................... 48 
Table 9‒1: 
Tenderness and swelling grading ..................................................................... 74 
Table 12‒1: 
Anticipated serious adverse events for the population of subjects with AS .... 82 
Table 12‒2: 
Laboratory measurements ................................................................................ 87 
Table 12‒3: 
Required investigations and follow-up for PDILI ........................................... 89 
Table 12‒4: 
PDILI laboratory measurements ...................................................................... 94 
Table 12‒5: 
PDILI information to be collected ................................................................... 95 
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Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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Table 19‒1: 
ASAS classification criteria for axial SpA (for subjects with chronic back 
pain of at least 3 months and age at onset <45 years) .................................... 125 
Table 19‒2: 
Modified New York (mNY) Classification Criteria for AS .......................... 126 
 
LIST OF FIGURES 
Figure 5‒1: 
Schematic diagram: study overview ................................................................ 35 
Figure 12‒1: Schematic diagram of TB test results and study eligibility ............................. 98 
Figure 12‒2: Schematic diagram of TB test results during the study ................................... 99 
Figure 15‒1: Sequential testing procedure of primary/secondary efficacy endpoints ........ 108 
 
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Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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LIST OF ABBREVIATIONS 
ACR 
American College of Rheumatology 
AE 
adverse event 
AESI 
adverse event of special interest 
ALP 
alkaline phosphatase 
ALT 
alanine aminotransferase 
ANCOVA 
analysis of covariance 
AP 
Anterior Posterior 
AS 
ankylosing spondylitis 
ASAS 
Assessment of SpondyloArthritis International Society 
ASAS20, 40, 5/6 
Assessment of SpondyloArthritis International Society 20%, 40%, 5 out of 6 
response criteria 
ASAS-PR 
Assessment of SpondyloArthritis International Society partial remission 
ASDAS-CRP 
Ankylosing Spondylitis Disease Activity Score-C-reactive protein 
ASDAS-MI 
Ankylosing Spondylitis Disease Activity Score major improvement 
ASspiMRI-a 
Ankylosing Spondylitis spine Magnetic Resonance Imagine-activity 
ASQoL 
Ankylosing Spondylitis Quality of Life 
AST 
aspartate aminotransferase 
axSpA 
axial spondyloarthritis 
BASDAI 
Bath Ankylosing Spondylitis Disease Activity Index 
BASFI 
Bath Ankylosing Spondylitis Functional Index 
BASMI 
Bath Ankylosing Spondylitis Metrology Index 
BP 
blood pressure 
CAT 
Computed Axial Tomography 
CDC  
Centers for Disease Control  
CDMS 
clinical data management system 
CHO 
Chinese Hamster Ovarian 
CI 
confidence interval 
CMV 
cytomegaly virus 
COVID-19 
coronavirus disease 2019 
COX-2 inhibitor 
cyclooxygenase 2 inhibitor 
CPM 
Clinical Project Manager 
CPMP 
Committee for Proprietary Medicinal Products 
CRO 
contract research organization 
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CRP 
C-reactive protein 
eC-SSRS 
electronic Columbia-Suicide Severity Rating Scale 
CZP 
certolizumab pegol 
DMARD 
disease-modifying antirheumatic drug 
DMC 
Data Monitoring Committee 
DVU 
disco-vertebral unit 
EAM 
extra-articular manifestation 
ECG 
electrocardiogram 
eCRF 
electronic Case Report Form 
ePRO 
electronic Patient-Reported Outcomes 
EDC 
electronic data capture 
EQ-5D-3L 
European Qol-5 Dimensions 3-Level 
ES 
Enrolled Set 
ET 
Early Termination 
EULAR 
European League Against Rheumatism 
FACIT 
Functional assessment of chronic illness therapy 
FAS 
Full Analysis Set 
FDA 
Food and Drug Administration 
GCP 
Good Clinical Practice 
GI 
gastrointestinal 
GMP 
Good Manufacturing practice 
HbcAb  
hepatitis B core antibody 
HbsAg  
hepatitis B surface antigen 
HBV 
hepatitis B virus 
HCQ 
hydroxychloroquine 
HCV 
hepatitis C virus 
HD 
high disease 
HIV 
human immunodeficiency virus 
HLA 
human leukocyte antigen 
HRQoL 
health-related quality of life 
IB 
Investigator’s Brochure 
IBD 
inflammatory bowel disease 
ICF 
Informed Consent Form 
ICH 
International Council for Harmonisation 
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ID 
inactive disease 
IEC 
Independent Ethics Committee 
IGRA 
Interferon-Gamma Release Assay 
IL 
interleukin 
im 
intramuscular 
IMP 
investigational medicinal product 
IMS 
International Menopause Society 
IRB 
Institutional Review Board 
IUD 
intrauterine device 
IUS 
intrauterine hormone-releasing system 
iv 
intravenous 
IXRS 
interactive voice or web response system  
LEF 
leflunomide 
LD 
low disease 
LTB 
latent tuberculosis 
LTBI 
latent tuberculosis infection  
MAR 
missing at random 
MASES 
Maastricht Ankylosing Spondylitis Enthesitis Index 
MCID 
minimal clinically important difference 
MCMC 
Markov-Chain Monte Carlo 
MCP 
metacarpophalangeals 
MCS 
mental component summary 
MedDRA® 
Medical Dictionary for Regulatory Activities 
MI 
multiple imputation 
MNAR 
missing not at random 
mNY 
Modified New York (criteria) 
MOS 
Medical Outcomes Study 
MRI 
magnetic resonance imaging 
MTX 
methotrexate 
nr-axSpA 
nonradiographic axial spondyloarthritis 
NRI 
nonresponder imputation 
NRS 
Numeric Rating Scale 
NSAID 
nonsteroidal anti-inflammatory drug 
NTMB 
nontuberculous mycobacteria 
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OC 
observed cases 
OMERACT 
Outcome Measures in Rheumatology Clinical Trials 
PASI  
Psoriasis Area and Severity Index  
PCS 
physical component summary 
PD 
pharmacodynamics 
PDILI 
potential drug-induced liver injury 
PFS 
prefilled syringe 
PGADA 
Patient’s Global Assessment of Disease Activity 
PhGADA 
Physician’s Global Assessment of Disease Activity 
PHQ-9 
Patient Health Questionnaire 9 
PIP 
proximal interphalangeal 
PK 
pharmacokinetics 
PK-PPS 
Pharmacokinetic Per-Protocol Set 
PPS 
Per-Protocol Set 
PRN 
as needed 
PS 
Patient Safety 
PsA 
psoriatic arthritis 
PSO 
psoriasis 
Q4W 
every 4 weeks  
r-axSpA 
radiographic axSpA 
RA 
rheumatoid arthritis 
RNA 
ribonucleic acid 
RS 
Randomized Set 
SAE 
serious adverse event 
SAP 
Statistical Analysis Plan 
sc 
subcutaneous(ly) 
SD 
standard deviation 
SF-36 
Short-Form 36-item Health Survey 
SFU 
Safety Follow-Up 
SJC 
swollen joint count 
SpA 
spondyloarthritis 
SPARCC 
Spondyloarthritis Research Consortium of Canada 
SPARTAN 
Spondyloarthritis Research and Treatment Network 
SS 
Safety Set 
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SSZ 
sulfasalazine 
STIR 
short-tau-inversion recovery 
t½ 
half-life 
TB 
tuberculosis 
TEAE 
treatment-emergent adverse event 
TJC 
tender joint count 
TNFα 
tumor necrosis factor alpha 
ULN 
upper limit of normal 
VAS 
visual analog scale 
vHD 
very high disease 
WHO 
World Health Organization 
WPAI-SHP 
Work Productivity and Activity Impairment Questionnaire-specific health 
problem 
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1 
SUMMARY 
This is a multicenter, Phase 3, randomized, double-blind, placebo-controlled study to evaluate 
the efficacy and safety of bimekizumab in subjects with active ankylosing spondylitis (AS), a 
subtype of axial spondyloarthritis (axSpA) with radiographic evidence of disease (also known as 
radiographic axSpA [r-axSpA]). To be eligible to participate in this study, subjects must be 
adults with a diagnosis of active AS, determined by documented radiologic evidence (x-ray) 
fulfilling the Modified New York (mNY) criteria for AS (1984) (Section 19.2), including at least 
3 months of symptoms and age at symptom onset <45 years, and moderate-to-severe active 
disease at Baseline as defined by both of the following: 
• Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ≥4 AND spinal pain ≥4 on a 
0 to 10 numeric rating scale (NRS) (from BASDAI Item 2). 
As bimekizumab will be evaluated in axSpA, UCB will also perform a randomized, 
double-blind, placebo-controlled Phase 3 study (AS0010) in subjects with nonradiographic axial 
spondyloarthritis (nr-axSpA) in parallel to the present study in AS (AS0011).  
The primary objective of AS0011 is to demonstrate the efficacy of bimekizumab administered 
subcutaneously (sc) every 4 weeks (Q4W) compared with placebo in the treatment of subjects 
with active AS. The secondary objectives of the study are listed in Section 3.2, and other 
objectives are listed in Section 3.3.  
The primary efficacy variable for this study is the Assessment of SpondyloArthritis International 
Society 40% response criteria (ASAS 40) response at Week 16. The secondary and other 
efficacy variables are listed in Section 4.2.1 and Section 4.3.1, respectively. 
Safety variables are listed in Section 4.2.2 (secondary safety variables) and Section 4.3.2 (other 
safety variables). The pharmacokinetic (PK), pharmacogenomic, and immunological variables 
are listed in Section 4.3.3, Section 4.3.4, and Section 4.3.5 respectively. 
AS0011 will evaluate the efficacy, safety, and PK of bimekizumab in adult subjects with 
active AS at a dose level of bimekizumab 160mg Q4W administered by sc injection.  
The overall study design consists of a Screening Period (minimum of approximately 14 days 
[unless a screenfailed subject from AS0010 will be screened in AS0011] to ≤35 days), a 52-week 
Treatment Period consisting of a 16-week Double-Blind Treatment Period, a 36-week 
Maintenance Period, and a Safety Follow-Up (SFU) Visit 20 weeks after the final dose of the 
investigational medicinal product (IMP) (ie, Week 48 for subjects who completed AS0011; for 
subjects not entering the extension study or who discontinue early, including those withdrawn 
from study treatment). The maximum study duration per subject will be 73 weeks.  
Approximately 300 subjects will be randomly assigned in a 2:1 ratio to the following treatment 
groups: bimekizumab 160mg sc Q4W (200 subjects) or placebo (100 subjects). Subjects 
receiving placebo during the Double-Blind Treatment Period will be re-allocated to 
bimekizumab treatment at Week 16 after all study assessments have been completed. These 
subjects will receive bimekizumab 160mg sc at Week 16 and Q4W thereafter (Section 7.2).  
A detailed schedule of study assessments is presented in Table 5-2 and a study schematic 
diagram is presented in Figure 5‒1. 
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Nonbiologic rescue therapy will be at the Investigator’s discretion as add-on therapy to 
bimekizumab at any time from Week 20 or later. Details are provided in Table 7‒2. 
Subjects completing Week 52 who meet the eligibility criteria may be enrolled in an extension 
study to continue to receive bimekizumab treatment.  
2 
INTRODUCTION 
2.1 
Axial spondyloarthritis 
Spondyloarthritis (SpA) is an umbrella term applied to a family of rheumatic diseases (including 
axial spondyloarthritis [axSpA], psoriatic arthritis [PsA], reactive arthritis, the arthritis of 
inflammatory bowel disease [IBD], and undifferentiated SpA) that have features in common with 
each other and distinct from other inflammatory arthritides, particularly rheumatoid arthritis 
(RA).  
The ASAS working group established classification criteria to distinguish 2 broad categories of 
SpA: peripheral SpA and axSpA (Rudwaleit et al, 2011; Rudwaleit, 2010; Rudwaleit et al, 
2009b). This division is based on the body part predominantly involved in the inflammatory 
process. Therefore, peripheral SpA includes diseases affecting mainly peripheral joints, such as 
reactive arthritis and PsA, whereas axSpA comprises those diseases with mainly axial 
involvement (sacroiliac joints and spine), including AS (also known as r-axSpA) diagnosed with 
definite radiographic changes of the sacroiliac joint and nr-axSpA.  
Patients with axSpA have inflammatory back pain. The disease typically originates in the 
sacroiliac joints, then progresses to the spine. In the sacroiliac joints and the spine, active 
inflammation results in erosions, sclerosis, and fatty lesions seen on magnetic resonance imaging 
(MRI). However, the most characteristic feature is new bone formation leading to ankylosis of 
the sacroiliac joints and syndesmophytes attached to the vertebral bodies. As a result of extended 
syndesmophyte formation, over time the spine may become fused (bamboo spine). Objective 
signs of inflammation (such as enthesitis, dactylitis, peripheral arthritis, or uveitis), genetic 
features (such as the presence of human leukocyte antigen [HLA] B27), and laboratory 
parameters (such as elevated C-reactive protein [CRP]) may also be present (Braun, 2012; 
Rudwaleit et al, 2009a; Braun and Sieper, 2007). Disability in axSpA is related to both the 
degree of inflammatory activity, causing pain, stiffness, fatigue, and poor quality of sleep, and to 
the degree of bony ankylosis, causing loss of spinal mobility. Patients with AS show 
radiographic progression of disease with x-ray identified sacroiliitis, while "bamboo spine" may 
develop when the outer fibers of the fibrous ring of the intervertebral discs ossify, which results 
in the formation of marginal syndesmophytes between adjoining vertebrae. 
2.1.1 
axSpA epidemiology  
Axial SpA is a chronic inflammatory disease that impacts a substantial proportion of the 
population. Limited evidence exists regarding the global occurrence of axSpA with a prevalence 
of 0.20 to 0.25% in Europe and North America, and a wider range in Asia (0.06 to 0.20%) 
(Stolwijk et al, 2016); however, recent data suggest that the prevalence is similar to that of RA in 
the US (axSpA: 0.7% to 1.4%; RA: 0.5% to 1.0%) (Reveille et al, 2012; Myasoedova et al, 2010; 
Helmick et al, 2008). Axial SpA comprises those diseases with mainly axial involvement 
(sacroiliac joints and spine), including AS and nr-axSpA. 
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2.1.2 
Current treatments for axSpA 
Nonsteroidal anti-inflammatory drugs are used as first-line treatment and are effective for the 
symptoms (pain and stiffness) of axSpA (van der Heijde et al, 2017; Ward et al, 2015; 
Poddubnyy, 2013; Poddubnyy et al, 2012), but many patients lose or never have clinically 
meaningful response and structural damage often progresses despite their use. Conventional 
disease-modifying antirheumatic drugs (DMARDs, eg, methotrexate [MTX] and sulfasalazine 
[SSZ]) have no proven efficacy in axial disease, but may benefit patients with peripheral joint 
disease (Haibel et al, 2007; Braun et al, 2006; Haibel et al, 2005). Therefore, DMARDs are 
recommended only in patients with predominantly peripheral manifestations (Braun et al, 2011). 
Patients who are intolerant of or have inadequately responded to NSAIDs, or those in whom 
NSAIDs are contraindicated, have approved treatment options such as tumor necrosis factor 
alpha (TNFα) inhibitors (van der Heijde, 2017; Ward et al, 2015).  
Recently, the interleukin (IL)-17 cytokine family has been identified as a therapeutic target in 
axSpA and secukinumab, an IL-17A monoclonal antibody, has recently been approved as a 
treatment option in active AS. 
2.2 
Bimekizumab 
Bimekizumab (UCB4940) is an engineered, humanized full-length monoclonal antibody of IgG1 
subclass of approximately 150,000 Dalton, which is expressed in a genetically engineered 
Chinese Hamster Ovarian (CHO) cell line. Bimekizumab has high affinity for human IL-17A 
and human IL-17F and selectively and potently inhibits the activity of both isoforms in vitro. 
Interleukin-17A and IL-17F are key proinflammatory cytokines believed to play important roles 
in autoimmune and inflammatory diseases. Therefore, bimekizumab permits an evaluation of the 
potential for additional efficacy, which may be conferred by dual inhibition of both cytokines, in 
patients suffering from diseases in which both cytokines are active. Bimekizumab is being 
developed for the treatment of patients with inflammatory diseases such as PsA, psoriasis (PSO), 
axSpA and hidradenitis suppurativa.  
2.2.1 
Nonclinical 
There is increasing evidence of the role of IL-17F in various inflammatory diseases. 
Simultaneous inhibition of IL-17A and IL-17F has been shown to be more efficacious than 
inhibition of IL-17A alone in in vitro models. Intravenously or sc administered bimekizumab 
was well tolerated in repeat-dose toxicology studies in Cynomolgus monkeys with dosing up to 
200mg/kg/week for up to 26 weeks. The findings of note varied from study to study, but were all 
compatible with decreased muco-epidermal immunity induced by the inhibition of IL-17A and F 
signaling. They consisted in diarrhea related to infectious enteritis, asymptomatic proliferation of 
a protozoan commonly found in the cynomolgus monkey, Balantidium coli, superficial 
dermatitis associated with increased bacterial load on the skin (mainly Gram positive cocci, 
including Staphylococcus aureus), and abscesses.  
Infection-related safety findings in a nonhuman primate can be highly variable from study to 
study and have limited ability to accurately predict the incidence and type of infection that can be 
expected in humans, especially because nonhuman primates bear different commensal flora and 
show different sensitivity to different pathogens. Immunomodulators can increase the 
susceptibility of monkeys to potential pathogens that are endemic in nonhuman primate 
populations and usually remain clinically undetectable or are mild and self-limiting in 
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immunocompetent animals. Moreover, infections associated with the gastrointestinal (GI) tract 
that result in chronic enterocolitis are a persistent and widespread colony problem in nonhuman 
primates, often multifactorial in origin.  
The nonclinical studies have highlighted the already known risk of infection linked to decreased 
muco-epidermal immunity that needs to be carefully monitored in the clinic, but are unlikely to 
predict the risk of infection in humans based on dose and exposure for the aforementioned 
reasons. To date, similar findings have not been seen in studies in humans. 
Preliminary results from the embryofetal and postnatal study conducted in the Cynomolgus 
monkey indicate no effects of bimekizumab on the gestation, gestation duration, or the 
parturition of pregnant females. No bimekizumab-related effects were noted in infants at birth, 
during postnatal development, or on infant survival rate. Toxicokinetic data confirmed 
dose-related exposure of maternal animals during the pregnancy and the lactation phase, and of 
infants at birth and during the postnatal phase. 
Additional information on the nonclinical data for bimekizumab is available in the current 
version of the Investigator’s Brochure (IB). 
2.2.2 
Clinical  
2.2.2.1 
Completed studies 
Twenty clinical studies of bimekizumab have been completed: UP0008 in 39 subjects with 
mild-to-moderate plaque PSO, RA0124 in 30 healthy volunteers, PA0007 in 53 subjects with 
PsA, UP0031 in 12 healthy volunteers, UP0033 in 189 healthy volunteers, UP0034 in 56 healthy 
volunteers, UP0042 in 48 Japanese and Caucasian healthy volunteers, UP0074 in 37 healthy 
volunteers, RA0123 in 159 subjects with moderate-to-severe RA, PS0010 in 250 subjects with 
moderate-to-severe chronic plaque PSO and the corresponding extension study (PS0011), 
PS0016 in 49 subjects with moderate-to-severe chronic plaque PSO and the corresponding 
extension study (PS0018), UC0011 in 23 subjects with moderate-to-severe active ulcerative 
colitis, HS0001 in 90 subjects with moderate to severe hidradenitis suppurativa, AS0008 in 
303 subjects with AS, PA0008 in 206 subjects with PsA, PS0008 in 478 subjects with moderate 
to severe chronic plaque PSO, PS0009 in 567 subjects with moderate to severe chronic plaque 
PSO and PS0013 in 435 subjects with moderate to severe chronic plaque PSO. 
Information on the clinical data for bimekizumab from completed studies is available in the 
current version of the IB. 
2.2.2.2 
Ongoing studies 
Several additional studies of bimekizumab in subjects with axSpA are ongoing:  
• AS0009 is an open-label extension study for AS0008. 
• AS0013 is a Phase 2a Investigator- and subject-blind parallel-group study to evaluate the 
efficacy and safety of bimekizumab and certolizumab pegol (CZP) in subjects with active 
AS.  
• AS0010 is a Phase 3, double-blind, randomized, placebo-controlled study to evaluate the 
efficacy and safety of bimekizumab in subjects with active nr-axSpA. 
• AS0014 is a Phase 3, open-label extension study for AS0010 and AS0011. 
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Bimekizumab is also being evaluated in the treatment of other indications (eg, PsA, PSO, 
hidradenitis suppurativa).  
Additional information on the ongoing studies for bimekizumab is available in the current 
version of the IB. 
3 
STUDY OBJECTIVE(S) 
3.1 
Primary objective 
The primary objective is to demonstrate the efficacy of bimekizumab administered sc Q4W 
compared to placebo in the treatment of subjects with active AS. 
3.2 
Secondary objectives 
The secondary objectives of the study are as follows: 
• To assess the efficacy of bimekizumab compared to placebo  
• To assess the safety and tolerability of bimekizumab 
• To assess the impact of bimekizumab on patient-reported quality of life  
• To assess the impact of bimekizumab on spinal mobility  
• To assess the impact of bimekizumab on enthesitis and on peripheral arthritis 
3.3 
Other objectives 
The other objectives are as follows: 
• To assess the immunogenicity of bimekizumab 
• To assess the pharmacokinetics of bimekizumab  
• To assess the maintenance of efficacy of bimekizumab 
• To assess the relationship between exploratory biomarkers, drug treatment, and AS disease 
biology 
• To assess the impact of bimekizumab on work productivity  
• To assess the impact of bimekizumab on inflammatory changes using MRI  
4 
STUDY VARIABLES 
4.1 
Primary variable 
4.1.1 
Primary efficacy variable 
The primary efficacy variable for this study is: 
• ASAS40 response at Week 16.  
4.2 
Secondary variables 
4.2.1 
Secondary efficacy variables 
The secondary efficacy variables for this study are as follows:  
• ASAS40 response at Week 16 in TNFα inhibitor-naïve subjects 
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• ASAS20 response at Week 16 
• Change from Baseline in BASDAI total score at Week 16  
• ASAS partial remission (ASAS-PR) at Week 16 
• Ankylosing Spondylitis Disease Activity Score major improvement (ASDAS-MI) at 
Week 16  
• ASAS5/6 response at Week 16 
• Change from Baseline in Bath Ankylosing Spondylitis Functional Index (BASFI) at Week 16  
• Change from Baseline in nocturnal spinal pain score (NRS) at Week 16 
• Change from Baseline in Ankylosing Spondylitis Quality of Life (ASQoL) total score at 
Week 16  
• Change from Baseline in the Short Form 36-Item Health Survey (SF-36) physical component 
summary (PCS) score at Week 16  
• Change from Baseline in Bath Ankylosing Spondylitis Disease Metrology Index (BASMI) at 
Week 16 
• Change from Baseline in the Maastricht Ankylosing Spondylitis Enthesitis (MASES) Index 
in the subgroup of subjects with enthesitis at Baseline at Week 16 
• Enthesitis-free state based on the MASES Index in the subgroup of subjects with enthesitis at 
Baseline at Week 16 
4.2.2 
Secondary safety variables 
Assessment time points for safety variables are specified in Table 5-2. Variables are as follows: 
• Incidence of treatment-emergent adverse events (TEAEs) 
• Incidence of treatment-emergent serious adverse events (SAEs) 
• TEAEs leading to withdrawal from IMP 
4.3 
Other variables 
4.3.1 
Other efficacy variables 
Other efficacy variables will be assessed as specified in Table 5-2. All time points not specified 
in Section 4.1.1 or Section 4.2.1 are exploratory:  
• ASAS40 response  
• Time to ASAS40 response  
• ASAS20 response  
• Time to ASAS20 response 
• ASAS5/6 response  
• ASAS-PR  
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• Change from Baseline in Ankylosing Spondylitis Disease Activity Score C-reactive protein 
(ASDAS-CRP)  
• ASDAS status (eg, inactive disease [ID], low disease [LD], high disease [HD], and very high 
disease [vHD])  
• ASDAS-MI  
• Change from Baseline in BASDAI total score  
• BASDAI50 response 
• Change from Baseline in BASFI  
• Change from Baseline in the MASES Index in the subgroup of subjects with enthesitis at 
Baseline  
• Enthesitis-free state based on the MASES in the subgroup of subjects with enthesitis at 
Baseline 
• Change from Baseline in BASMI  
• Change from Baseline in Physician’s Global Assessment of Disease Activity (PhGADA)  
• Change from Baseline in Patient’s Global Assessment of Disease Activity (PGADA)  
• Change from Baseline in total and nocturnal spinal pain score (NRS)  
• Change from Baseline in the average score of Questions 5 and 6 of the BASDAI concerning 
morning stiffness  
• Change from Baseline in CRP  
• Responses to the European Qol-5 Dimensions 3-Level (EQ-5D-3L)  
• Change from Baseline in EQ-5D-3L visual analog scale (VAS) scores  
• Change from Baseline in the EQ-5D utility score  
• Change from Baseline in the SF-36 PCS score 
• Change from Baseline in the SF-36 mental component summary (MCS) score 
• Change from Baseline in sleep quality score (Medical Outcomes Study [MOS 12-item] scale)  
• Change from Baseline in Functional Assessment of Chronic Illness Therapy 
(FACIT)-Fatigue subscale score 
• Change from Baseline in ASQoL total score  
• Change from Baseline in the Work Productivity and Activity Impairment 
Questionnaire- specific health problem (WPAI-SHP)  
• Change from Baseline in (44/44) tender joint count (TJC) and swollen joint count (SJC) 
• Change from Baseline in Ankylosing Spondylitis spine MRI-activity (ASspiMRI-a) in the 
Berlin modification score  
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• Change from Baseline in sacroiliac joint Spondyloarthritis Research Consortium of Canada 
(SPARCC) score  
4.3.2 
Other safety variables 
Other safety variables to be assessed as specified in Table 5-2 are as follows: 
• Change from Baseline in vital signs (blood pressure [BP], temperature, and pulse rate)  
• Standard 12-lead electrocardiogram (ECG) results  
• Change from Baseline in clinical laboratory values (hematology, biochemistry, and 
urinalysis) 
• Change from Baseline in Patient Health Questionnaire-9 (PHQ-9) 
Physical examination findings considered clinically significant changes since the physical 
examination at the Screening Visit will be recorded as adverse events (AEs). 
4.3.3 
Pharmacokinetic variable 
The PK variable is the plasma concentration of bimekizumab.  
4.3.4 
Pharmacogenomic variables 
Additional blood and stool samples will be collected from subjects who consent to participate in 
the substudy at specific time points specified in Table 5-2. 
Genomic, genetic, epigenetic, proteins, and metabolite biomarkers may be measured to evaluate 
the relationship with response to treatment with bimekizumab, axSpA disease biology, bone 
metabolism, and inflammatory and immune response processes. The nature and format of these 
tentative substudy analyses will be determined at a later time.  
Additional candidate serum exploratory variables may include, but are not limited to the blood 
concentrations of cytokines and chemokines of relevance to the IL-17A/F signaling pathway and 
axSpA biology, and serum complement concentrations. Stool samples will be collected from 
subjects who consent to participate in the pharmacogenomics substudy at specific time points 
specified in Table 5-2. These samples may be used to assess biomarkers of gut inflammation 
including but not limited to calprotectin and microbiome testing. 
4.3.5 
Immunological variables 
The immunological variables are the anti-bimekizumab antibody status and the 
treatment-emergent antibody positivity derived from anti-drug antibody assays. 
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5 
STUDY DESIGN 
5.1 
Study description 
This is a multicenter, Phase 3, randomized, double-blind, placebo-controlled study to evaluate 
the efficacy and safety of bimekizumab in subjects with active AS. To be eligible to participate 
in this study, subjects must meet the following key inclusion criteria:  
• Adult subjects with active AS, determined by documented radiologic evidence (x-ray) 
fulfilling the Modified New York criteria for AS (1984) (Section 19.2), including at least 
3 months of symptoms.  
• Age at symptom onset <45 years  
• Subject must have moderate-to-severe active disease as defined by BOTH of the following at 
Screening AND Baseline.  
− BASDAI ≥4 AND spinal pain ≥4 on a 0 to 10 NRS (from BASDAI Item 2)  
Detailed eligibility criteria are presented in Section 6.1 and Section 6.2.  
The study will include the following 3 periods: a Screening Period (minimum of approximately 
14 days [unless a screenfailed subject from AS0010 will be screened in AS0011] to ≤35 days), a 
Treatment Period (52 weeks) consisting of a 16-week Double-Blind Treatment Period and a 
36-week Maintenance Period, and a SFU Period (20 weeks after the final dose of IMP). 
Eligible subjects will be randomized 2:1 to receive 1 of 2 treatments (bimekizumab 
160mg sc Q4W or placebo sc Q4W), and will remain on their allowable background medication. 
Details of the Treatment Period are provided in Section 5.1.2. At the end of the 16-week 
Double-Blind Treatment Period subjects receiving placebo will be re-allocated to bimekizumab 
treatment at Week 16 after all assessments have been completed. These subjects will receive 
bimekizumab 160mg sc at Week 16 and 160mg sc Q4W thereafter. Starting at Week 20, 
nonbiologic rescue therapy for axial SpA may be adjusted or added, while continuing 
bimekizumab as outlined in Table 7‒2. 
Subjects completing Week 52 who are not withdrawn from IMP, may be eligible for enrollment 
in an extension study with bimekizumab. Subjects who are ineligible for or elect not to 
participate in the extension study at Week 52 will undergo a SFU Visit. 
Interim analyses of all available data (including efficacy, safety, and PK) will be conducted after 
the planned number of randomized subjects have completed 24 weeks and 52 weeks of treatment 
or have withdrawn from IMP or the study. Details of the interim analyses are given in 
Section 15.8.1. The final analysis of all available data will be performed after all randomized 
subjects have completed the SFU Visit or have withdrawn from the IMP and/or study.  
A detailed schedule of study assessments is presented in Table 5-2 and a study schematic 
diagram is presented in Figure 5‒1.  
5.1.1 
Screening Period/Baseline 
Assessments of eligibility as described in Section 6 will be initiated during the Screening Period 
with a minimum duration of approximately 14 days (unless a screenfailed subject from AS0010 
will be screened in AS0011) and a maximum duration of up to 35 days. The Screening Period 
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will also enable the washout of medications not permitted for use during the study, allow 
initiation of latent TB treatment where necessary, and allow completion of imaging assessments 
required to determine eligibility including time for central reading.  
All subjects will have an anterior posterior (AP) pelvis or sacroiliac joint x-ray (read centrally) to 
determine eligibility as per mNY criteria. Subjects who are mNY-negative may be eligible for 
Screening in AS0010, a double-blind, randomized, placebo-controlled Phase 3 study in subjects 
with active nr-axSpA. It is recommended to perform the sacroiliac joint x-ray prior to any other 
screening assessment to avoid repetition of screening assessments (applicable at sites 
participating in both Phase 3 studies). 
5.1.1.1 
Within-study rescreening/retesting requirements 
Rules for rescreening or repetition of screening tests within the study are listed below: 
• Subjects who fail to meet the eligibility criteria for BASDAI, spinal pain, PHQ-9, eC-SSRS, 
or the TB questionnaire are not allowed to be rescreened. 
The Medical Monitor must be contacted for confirmation of rescreening/retesting in all other 
cases. 
• Subjects who initially fail to meet selected eligibility criteria (eg, documented completion of 
latent tuberculosis infection [LTBI] prophylactic therapy) may be rescreened. 
• Subjects for whom eligibility assessments could not be completed as planned (eg, for 
technical reasons) within the defined Screening Period of 35 days may be rescreened.  
• Subjects with individual laboratory screening tests for which the results are exclusionary, can 
be retested.  
Of note, repetition of laboratory screening tests within the Screening Period is permitted for 
technical reasons (eg, frozen sample, expired laboratory kit) without contacting the Medical 
Monitor. 
5.1.1.2 
Cross-study screening requirements 
Screening assessments for subjects previously screened for AS0010, who were not eligible for 
AS0010 based on mNY criteria and therefore entered AS0011 Screening for eligibility, must be 
repeated during the Screening Period unless defined in Table 5‒1. The Medical Monitor must be 
contacted for confirmation of the rescreening requirements in all cases. 
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Table 5‒1: 
Cross-study screening requirements 
Assessment  
Screening requirements 
Cross-study screening is not permitted in the following cases: 
BASDAI and 
spinal pain 
Screening of a subject not eligible for AS0010 who will be screened for AS0011, 
and who did not meet the related Inclusion Criteria in AS0010. 
PHQ-9, eC-SSRS, 
TB questionnaire 
(Q1) 
Screening of a subject not eligible for AS0010 who will be screened for AS0011, 
and who did meet the related Exclusion Criteria in AS0010. 
Cross-study screening is permitted in the following cases: 
CRP 
If a subject not eligible for AS0010 will be screened for AS0011, the Screening 
CRP testing must be repeated during Screening for AS0011 only if the result is 
older than 35 days at time of randomization at Baseline (Section 12.6). 
All safety 
laboratory 
assessments 
If a subject not eligible for AS0010 will be screened for AS0011, the Screening 
safety laboratory testing (hematology, biochemistry, urinalysis, urine drug 
screen, pregnancy testing as applicable, HIV, Hepatitis B and C, and IGRA TB 
testing), and HLA-B27 testing must be repeated during Screening for AS0011 
only if the results are older than 35 days at time of randomization at Baseline 
(Section 12.6). 
Anterior posterior 
pelvis x-ray 
The following will be accepted to qualify subjects with AS for this study: 
Anterior posterior pelvis x-ray centrally read for AS0010 and determined to be 
modified New York Criteria positive (+mNY); neither the x-ray nor the reading 
will be repeated (Section 9.20). The central imaging reader needs to be informed 
by the site about screening activities in order to transfer and confirm eligibility 
for the switch from AS0010 to AS0011. 
AS=ankylosing spondylitis; BASDAI=Bath Ankylosing Spondylitis Disease Activity Index; CRP=C-reactive 
protein; eC-SSRS=electronic Columbia-Suicide Severity Rating Scale; HIV=human immunodeficiency virus; 
HLA-B27=human leukocyte antigen B27; IGRA=Interferon-Gamma Release Assay; mNY=modified New 
York; PHQ-9=Patient Health Questionnaire 9; Q=question; TB=tuberculosis 
Assessments at the Screening Visit are presented in Table 5-2. 
5.1.2 
Treatment Period 
5.1.2.1 
Double-Blind Treatment Period 
During the Double-Blind Treatment Period, subjects will be randomized in a 2:1 fashion 
(stratified by region and prior TNFα inhibitor experience) to 1 of 2 treatment arms to receive 
blinded IMP regimens of bimekizumab 160mg sc Q4W or placebo sc Q4W. The enrollment of 
TNFα inhibitor-experienced subjects will be limited to 30% of the total study population.  
Investigational medicinal product treatment details are provided in Section 7.2.  
Visit windows of ±3 days are allowed from the first dose at all visits through Week 16. The visit 
window is relative to the Baseline Visit, not the previous study visit. The time between doses 
should be ≥25 days and ≤31 days. When applying the allowed visit windows, it must be ensured 
that the time between these 2 visits does not exceed the allowed time between doses. 
Bimekizumab or placebo will be administered sc by unblinded study personnel at the study site. 
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The Double-Blind Treatment Period ends after Week 16 assessments. At Week 16, subjects will 
transition from the double-blind, placebo-controlled treatment into the 36-week Maintenance 
Period with bimekizumab treatment, as discussed in Section 5.1.2.2. 
Subjects discontinuing IMP during the Double-Blind Treatment Period will be encouraged to 
return for all scheduled visits through Week 52 and the SFU Visit (20 weeks after the final dose 
of IMP), as applicable (Section 5.1.4). Subjects withdrawing from the study will have an 
ET Visit and a SFU Visit 20 weeks after the final dose of IMP, as applicable. 
5.1.2.2 
Maintenance Period 
The 36-week Maintenance Period starts with the Week 16 IMP administration. All subjects will 
receive bimekizumab 160mg sc Q4W during the Maintenance Period. 
• Subjects who received bimekizumab 160mg sc Q4W during the 16-week Double-Blind 
Treatment Period will continue to receive bimekizumab 160mg sc Q4W.  
• Subjects who received placebo during the 16-week Double-Blind Treatment Period will be 
re-allocated to bimekizumab treatment. After the Week 16 assessments are performed, all 
subjects will receive bimekizumab 160mg sc Q4W.  
Bimekizumab will be administered by the blinded or unblinded study personnel at the study site, 
according to the site-specific blinding plan.  
Visit windows of ±4 days are allowed for all visits after Week 16. The time between doses 
during the Maintenance Period should be ≥24 days and ≤32 days. When applying the allowed 
visit windows, it must be ensured that the time between these 2 visits does not exceed the 
allowed time between doses. 
All subjects will be eligible for nonbiologic rescue therapy from Week 20 onwards, as defined in 
Table 7‒2. 
Prior to completion of the Maintenance Period, Investigators should discuss treatment options 
with the subject. Subjects who complete AS0011 and meet the eligibility criteria may enroll in an 
extension study to continue to receive bimekizumab.  
Subjects discontinuing IMP during the Maintenance Period after Week 16 will be encouraged to 
return for all scheduled visits through Week 52 and the SFU Visit (20 weeks after the final dose 
of IMP), as applicable. The SFU Visit is not required if the Week 52 Visit is ≥20 weeks after the 
final dose of IMP (Section 5.1.4). Subjects withdrawing from the study will have an ET Visit and 
a SFU Visit 20 weeks after the final dose of IMP. 
5.1.3 
Early Termination Visit 
Subjects withdrawing consent and withdrawn early from the study will undergo the ET Visit 
assessments (see Section 8.5) and will enter the SFU Period. 
Subjects withdrawing from IMP who are not continuing for all scheduled visits through 
Week 52, will undergo the ET Visit, and will enter the SFU Period. 
5.1.4 
Safety Follow-Up Visit 
All subjects who complete the study and do not enter the extension study will undergo the 
SFU Visit 20 weeks after their final dose of IMP (see Section 8.6). 
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Subjects withdrawing from the IMP during the study, will be encouraged by the Investigator to 
return for all scheduled visits through Week 52 and the SFU Visit (unless the Week 52 Visit 
occurs ≥20 weeks after the final dose of IMP). 
Subjects withdrawing from IMP who are not continuing for all scheduled visits, will undergo the 
ET Visit and the SFU Visit 20 weeks after their final dose of IMP. 
Subjects withdrawing consent and withdrawn early from the study will undergo the ET Visit 
assessments and will enter the SFU Period. 
5.1.5 
Study duration per subject 
For each subject, the study will last up to 73 weeks, as follows: 
• Screening Period: minimum duration of approximately 14 days (unless a screenfailed subject 
from AS0010 will be screened in AS0011) to ≤35 days 
• 16-week Double-Blind Treatment Period 
• 36-week Maintenance Period 
• A SFU Visit for subjects who complete the study and who do not enter the extension study or 
who discontinue from the study early, including those withdrawn from IMP, will be 
conducted 20 weeks after the final dose of the IMP as applicable (ie, Week 48 for subjects 
who completed AS0011). 
The end of the study is defined as the date of the last visit of the last subject in the study. 
5.1.6 
Planned number of subjects and site(s) 
Approximately 300 subjects will be randomly assigned in a 2:1 ratio to the following treatment 
groups: bimekizumab 160mg sc Q4W (200 subjects) or placebo sc Q4W (100 subjects). The 
planned number of study sites is approximately 95.  
Enrollment requirements will be applied and controlled by the IXRS system. 
The minimum proportion of TNFα inhibitor-naïve subjects will be approximately 70% and the 
maximum proportion of subjects with prior use of TNFα inhibitor will be approximately 30%.  
5.1.7 
Anticipated regions and countries 
This will be a multicenter, international study conducted in approximately 14 countries in the 
US, Eastern and Western Europe, and Asia. Enrollment will be competitive among study sites 
and may be capped in regions or at sites.  
5.2 
Schedule of study assessments 
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Table 5-2: 
Schedule of study assessments 
Protocol activity 
SC 
BL (D1) 
Double-Blind Treatment 
Period (16 weeks) 
Maintenance Period (36 weeks) 
ET 
SFUb 
Weeka 
 
 
1 
2 
4 
8 
12 
16 
20 
24 
28 
32 
36 
40 
44 
48 
52 
 
 
Visita 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
 
 
Written informed consent 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Demographic data including 
lifestyle and infection history 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
AS history including EAMs 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Significant past medical history 
and concomitant diseases 
X 
Xc 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Incl./excl. criteria 
X 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Prior medication 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Concomitant medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse events 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
eC-SSRSd 
X 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
PHQ-9 
X 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
ASQoL 
 
X 
 
 
X 
X 
X 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
BASDAI 
X 
X 
X 
X 
X 
X 
X 
X 
 
X 
 
 
X 
 
  
 
X 
X 
 
BASFI 
 
X 
X 
X 
X 
X 
X 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
SF-36 PCS and MCS 
 
X 
 
 
 
X 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
MOS Short Sleep Scale (12 items) 
 
X 
 
 
 
X 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
PGADA 
 
X 
X 
X 
X 
X 
X 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
Total and nocturnal spinal pain 
(NRS) 
 
X 
X 
X 
X 
X 
X 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
Tuberculosis questionnaire 
X 
X 
 
 
 
 
X 
 
 
X 
 
 
X 
 
 
X 
 
X 
X 
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Table 5-2: 
Schedule of study assessments 
Protocol activity 
SC 
BL (D1) 
Double-Blind Treatment 
Period (16 weeks) 
Maintenance Period (36 weeks) 
ET 
SFUb 
Weeka 
 
 
1 
2 
4 
8 
12 
16 
20 
24 
28 
32 
36 
40 
44 
48 
52 
 
 
Visita 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
 
 
FACIT-Fatigue subscale 
 
X 
 
 
X 
 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
EQ-5D-3L 
 
X 
 
 
X 
 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
WPAI-SHP 
 
X 
 
 
 
 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
Vital signs (BP, pulse, 
temperature)e 
X 
X 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Height and body weightf 
X 
X 
 
 
 
X 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
X 
Physical examinationg 
X 
X 
 
 
 
X 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
X 
TJC/SJC (44/44) 
 
X 
 
 
 
X 
 
X 
 
X 
 
 
 
 
 
 
X 
 
 
MASES 
 
X 
 
 
X 
X 
 
X 
 
X 
 
 
 
 
 
 
X 
X 
 
BASMI 
 
X 
 
 
 
X 
 
X 
 
X 
 
 
 
 
 
 
X 
X 
 
PhGADA 
 
X 
 
 
X 
X 
 
X 
 
X 
 
 
X 
 
 
 
X 
X 
 
ECGh 
X 
 
 
 
 
 
 
X 
 
X 
 
 
 
 
 
 
X 
X 
X 
Hematology/ 
biochemistry 
X 
X 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Urinalysis 
X 
 
 
 
 
 
 
X 
 
 
 
 
X 
 
 
 
X 
X 
X 
Urine drug screen 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CRP 
X 
X 
 
X 
X 
X 
X 
X 
 
X 
 
 
X 
 
 
 
X 
X 
X 
Pregnancy testingi 
X 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Hepatitis B and C testingj,k 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HIV testingj 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HLA-B27 analysis 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 5-2: 
Schedule of study assessments 
Protocol activity 
SC 
BL (D1) 
Double-Blind Treatment 
Period (16 weeks) 
Maintenance Period (36 weeks) 
ET 
SFUb 
Weeka 
 
 
1 
2 
4 
8 
12 
16 
20 
24 
28 
32 
36 
40 
44 
48 
52 
 
 
Visita 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
 
 
BKZ plasma concentrationj 
 
X 
 
X 
X 
X 
X 
X 
X 
X 
 
 
X 
 
 
 
X 
X 
X 
Anti-BKZ antibody detectionj 
 
X 
 
 
X 
X 
X 
X 
X 
X 
 
 
X 
 
 
 
X 
X 
X 
Serum and plasma samples for 
exploratory biomarkersj,l 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
X 
 
 
RNA blood samples for 
exploratory biomarkersj,l 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
X 
 
 
Blood sample for genetic/ 
epigenetic analysisj,l 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
X 
 
 
Stool samplesl 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
IGRA TB testj,m 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
 
 
Chest x-rayn 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Sacroiliac joint x-rayo 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Spine x-rayp 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Sacroiliac and spine MRIq 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
X 
 
 
Enter IXRSr 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
IMP administrations 
 
X 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
 
AS=ankylosing spondylitis; ASQoL=Ankylosing Spondylitis Quality of Life; BASDAI=Bath Ankylosing Spondylitis Disease Activity Index; BASFI=Bath 
Ankylosing Spondylitis Functional Index; BASMI=Bath Ankylosing Spondylitis Metrology Index; BL=Baseline; BKZ=bimekizumab; BP=blood pressure; 
CRP=C-reactive protein; D=day; EAM=extra-articular manifestation; eC-SSRS=electronic Columbia-Suicide Severity Scale; ECG=electrocardiogram; EQ-
5D-3L=EuroQol 5 Dimensions 3 Level; ET=Early Termination; excl.=excluding; FACIT=Functional Assessment of Chronic Illness Therapy; HIV=human 
immunodeficiency virus; HLA-B27=human leukocyte antigen B27; IGRA=interferon gamma release assay; IMP=investigational medicinal product; 
incl.=including; IXRS=interactive voice or web response system; MASES=Maastricht Ankylosing Spondylitis Enthesitis; MCS=mental component score; 
MOS=Medical Outcomes Study; MRI=magnetic resonance imaging; NRS=numeric rating scale; mNY=modified New York; PCS=physical component score; 
PGADA=Patient’s Global Assessment of Disease Activity; PhGADA=Physician’s Global Assessment of Disease Activity; PHQ-9=Patient’s Health 
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Table 5-2: 
Schedule of study assessments 
Protocol activity 
SC 
BL (D1) 
Double-Blind Treatment 
Period (16 weeks) 
Maintenance Period (36 weeks) 
ET 
SFUb 
Weeka 
 
 
1 
2 
4 
8 
12 
16 
20 
24 
28 
32 
36 
40 
44 
48 
52 
 
 
Visita 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
 
 
Questionnaire 9; RNA=ribonucleic acid; SC=Screening; SF-36=Short Form-36 Health Survey; SFU=Safety Follow-Up; SJC=swollen joint count; 
TB=tuberculosis; TJC=tender joint count; WPAI-SHP=Work Productivity and Activity Impairment Questionnaire-specific health problem 
a Visit windows of ±3 days are allowed for all visits through Week 16. The visit window is relative to the Baseline Visit, not the previous week’s visit. During 
the Maintenance Period, visit windows of ±4 days are permitted for all visits after Week 16. 
b The SFU Visit occurs 20 weeks after the final dose for all subjects who complete the study and do not enter the extension study or who discontinue early, 
including those withdrawn from study treatment. The visit window for the SFU Visit is -3/+7 days. 
c Ensure there are no significant changes in medical history that would exclude the subject based on the exclusion criteria. 
d If an Unscheduled Visit is conducted due to safety or efficacy reasons, an eC-SSRS assessment will be performed with the subject during the visit. 
e Collect vital signs (pulse, BP, and temperature) prior to IMP administration and then at 30 minutes after administration and 1 hour after administration at 
Baseline and Week 16 only. At all other applicable visits, vital signs will be collected once prior to IMP administration. All other procedures are done prior 
to dosing. 
f The Investigator or designee will measure the height of the subject with shoes removed in meters once at Screening and the weight of the subject in 
kilograms. 
g Includes evaluation of signs and symptoms of active TB and risk for exposure to TB. 
h ECGs will be read centrally. 
i Pregnancy testing will consist of serum testing at Screening for all women of childbearing potential. A urine dipstick will be used for pregnancy testing at all 
other visits (Section 12.7.6). 
j At dosing visits, all blood samples are taken prior to dosing. Blood samples for bimekizumab and anti-bimekizumab antibody detection as well as 
pharmacogenetics/genomics will be processed as per instructions in the lab manual. 
k Subjects who have evidence of or test positive for hepatitis B or hepatitis C are excluded. Positive test criteria are defined in Section 6.2. 
l A separate Informed Consent Form will be required for subjects who decide to participate in the pharmacogenomic substudy. The Informed Consent Form 
must be signed prior to collecting any samples for the substudy. Blood and/or stool samples are collected for exploratory purposes and participation in either 
blood or stool sampling (or both) is optional.  
m An IGRA TB test will be performed at the central laboratory. Details will be specified in the Laboratory Manual.  
n If a subject has had a recent x-ray of the chest within 3 months prior to the Screening Visit, it may be used as the Screening chest x-ray. Any findings 
suggestive of active TB are exclusionary. 
o The following will be accepted to qualify AS subjects for this study: a) sacroiliac joint x-ray centrally read for the Phase 3 study AS0010 determined to be 
modified New York Criteria positive (+mNY); neither the reading nor the x-ray will be repeated; b) prior sacroiliac joint x-ray (performed at any time prior 
to the study) was submitted and centrally read for the purposes of this study and determined to be modified New York Criteria positive (+mNY). If the prior 
x-ray is not meeting central reading criteria for randomization, another x-ray may be performed if prior x-ray is more than 1 year old and if permitted by 
local guidelines, or c) if no prior x-ray is available, one must be performed at Screening. 
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Table 5-2: 
Schedule of study assessments 
Protocol activity 
SC 
BL (D1) 
Double-Blind Treatment 
Period (16 weeks) 
Maintenance Period (36 weeks) 
ET 
SFUb 
Weeka 
 
 
1 
2 
4 
8 
12 
16 
20 
24 
28 
32 
36 
40 
44 
48 
52 
 
 
Visita 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
 
 
p The spine x-ray at Baseline for subjects with confirmed eligibility can be performed prior to or after the Baseline Visit, and must be performed prior to or no 
later than on the day of the second administration of IMP. The spine x-ray will be centrally read and will be used to assess disease progression in the spine in 
the extension study, given the subject is willing to enter this subsequent study. If the subject has a spine x-ray available from the past 6 months prior to 
Screening, this x-ray may be used and submitted for central reading. 
q Sacroiliac joint and spine MRIs will be performed for subjects participating in the MRI substudy. Baseline sacroiliac joint and spine MRIs should be 
performed after confirmation of eligibility based on screening assessments for the study and before the first dose of IMP. The sacroiliac joint and spine MRIs 
can be performed at Baseline or prior to the actual Baseline Visit. Further sacroiliac joint and spine MRIs will be performed at Weeks 16 and 52, within a 
window of ±5 days for all subjects participating in the substudy.  
r The IXRS is used to register subjects at Screening, randomize subjects at Baseline/Day 1, rerandomize subjects at Week 16 and to register all visits. 
s At Week 16, the Maintenance Period dosing will start, as detailed Section 5.1.2.2. At Week 52, IMP administration will only occur for subjects entering the 
extension study. Dosing details at Week 52 will be provided in the protocol of the extension study. 
 
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5.3 
Schematic diagram 
Figure 5‒1: Schematic diagram: study overview 
 
 
ASAS40=Assessment of SpondyloArthritis International Society 40% response criteria; BKZ=bimekizumab; BL=Baseline; IMP=investigational medicinal 
product; Q4W=every 4 weeks; sc=subcutaneous; SFU=Safety Follow-Up; W=week 
a Subjects are eligible for nonbiologic rescue therapy starting at Week 20 with treatment at the discretion of the Investigator while continuing to receive BKZ. 
Treatment with non-BKZ biologics or prohibited treatment (see Section 7.8.2) will lead to BKZ discontinuation (Table 7‒2).  
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5.4 
Rationale for study design and selection of dose 
AS0011 will evaluate the efficacy and safety of bimekizumab at a dose level of bimekizumab 
160mg sc Q4W in adult subjects with AS. 
5.4.1 
Study design 
A randomized, double-blind, placebo-controlled study design has been selected to evaluate the 
efficacy and safety of bimekizumab. The study population will include adult subjects with active 
AS and allow subjects who have received previous biologic treatment (eg, a TNFα inhibitor) as 
well as those who are biologic treatment-naïve. The primary efficacy outcome measures 
(ASAS40 response) and other efficacy assessments included in this study are consistent with 
those used for other axSpA studies and are considered appropriate for establishing efficacy of 
bimekizumab. An initial double-blind treatment period of 16 weeks will be used to demonstrate 
the efficacy of bimekizumab over placebo. The study duration extends beyond the initial 
Double-Blind Treatment Period (ie, Maintenance Period up to 52 weeks) to collect data on the 
maintenance of efficacy of bimekizumab for exploratory analyses and to allow continued 
evaluation of safety data. 
5.4.2 
Dose selection 
A bimekizumab dose of 160mg sc Q4W has been selected for AS0011. 
Bimekizumab doses of 16mg to 320mg Q4W were evaluated in a multicenter, Phase 2b, 
double-blind, placebo-controlled, randomized, parallel-group study in subjects with active AS 
(AS0008). Results from the Week 12 interim analysis indicated bimekizumab doses up to and 
including 320mg have an acceptable safety profile and PK/PD modelling indicated a plateau in 
Week 12 ASAS40 response at doses of 160mg and above. This plateau at bimekizumab160mg 
was further confirmed based on the observed noncontrolled Week 48 data, which demonstrated a 
similar ASAS40 response between 160mg and 320mg Q4W at Week 48. 
There were no dose-related safety concerns or changes in laboratory values in the preliminary 
data review up to 48 weeks that preclude the use of any of the tested doses in AS0008 for the 
Phase 3 program in axSpA. 
The same dosing regimen was selected for a Phase 3 program evaluating bimekizumab in 
subjects with active PsA.  
6 
SELECTION AND WITHDRAWAL OF SUBJECTS 
6.1 
Inclusion criteria 
To be eligible to participate in this study, all of the following criteria must be met:  
1a. An Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved written 
Informed Consent form is signed and dated by the subject. 
2a. Subject is considered reliable and capable of adhering to the protocol (eg, able to understand 
and complete diaries), visit schedule, or medication intake according to the judgment of the 
Investigator. 
3. Subject is male or female at least 18 years of age. 
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4. Subject has AS as per the Modified New York (mNY) criteria (1984) including documented 
radiologic evidence (x-ray) based on central reading and at least 3 months of symptoms 
(Table 19‒2) with age at symptom onset <45 years.  
5. Subject has moderate-to-severe active disease as defined by BOTH of the following at 
Screening AND Baseline: 
− BASDAI ≥4 AND spinal pain ≥4 on a 0 to 10 NRS (from BASDAI Item 2) 
6a. Subjects had to have either failed to respond to 2 different NSAIDs given at the maximum 
tolerated dose for a total of 4 weeks or have a history of intolerance to or a contraindication 
to NSAID therapy.  
7. Subjects who are regularly taking NSAIDs/COX-2 inhibitors or analgesics (including mild 
potency opioids) are required to be on a stable dose for at least 14 days before Baseline.  
8. Subjects taking corticosteroids must be on an average daily dose of ≤10mg/day prednisone or 
equivalent for at least 14 days before Baseline.  
9. Subjects taking MTX (≤25mg/week) or LEF (≤20mg/day or an average of 20mg/day if not 
dosed daily) are allowed to continue their medication if started at least 12 weeks prior to 
Baseline, with a stable dose and route of administration (MTX) for at least 8 weeks before 
randomization. It is strongly recommended that subjects taking MTX are also taking folic 
acid supplementation.  
10. Subjects taking SSZ up to 3g/day (or 4g/day if in accordance with local standard of care), 
HCQ up to 400mg/day (other anti-malarials may be used if in accordance with local standard 
of care), or apremilast (up to 60mg/day and dosed as per local label) are allowed to continue 
their medication if started at least 8 weeks prior to Baseline, with a stable dose for at least 
4 weeks before randomization.  
11. Subjects who have taken a TNFα inhibitor must have experienced an inadequate response to 
previous treatment given at an approved dose for at least 12 weeks or have been intolerant to 
treatment.  
12. Female subjects must be: 
− Postmenopausal. Menopause is defined as 12 consecutive months of amenorrhea, for 
which there is no other obvious pathological or physiological cause. 
− Permanently sterilized (eg, tubal occlusion, hysterectomy, bilateral salpingectomy). 
− Or, if of childbearing potential (and engaged in sexual activity that could result in 
procreation), must be willing to use a highly effective method of contraception 
throughout the duration of the study until 20 weeks after last administration of IMP, and 
have a negative pregnancy test at Visit 1 (Screening) and immediately prior to first dose. 
The following methods are considered highly effective when used consistently and correctly: 
− Combined (estrogen and progestogen) hormonal contraception associated with inhibition 
of ovulation (oral, intravaginal or transdermal) 
− Progestogen-only hormonal contraception associated with inhibition of ovulation (oral, 
injectable, implantable) 
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− Intrauterine device (IUD) 
− Intrauterine hormone-releasing system (IUS) 
− Vasectomized partner 
− Abstinence as a form of birth control is generally not allowed in the study unless 
abstinence is in accordance with a subject’s preferred and common lifestyle. Study 
personnel must confirm the continued use of abstinence is still in accordance with the 
subject’s lifestyle at regular intervals during the study 
6.2 
Exclusion criteria 
Subjects are not permitted to enroll in the study if any of the following criteria are met: 
1. Female subject who is breastfeeding, pregnant, or plans to become pregnant during the study 
or within 20 weeks following the final dose of IMP. 
2. Subject has previously participated in a bimekizumab clinical study who received at least 
1 dose of the IMP (including placebo). 
3a. Subject previously participated in another study of a medication (systemic) under 
investigation within the 12 weeks or at least 5 half-lifes prior to the Baseline Visit, whichever 
is greater, or is currently participating in another study of a medication (systemic) under 
investigation, with the exception of subjects who were screen failures in AS0010. 
4. Subject previously participated in another study of a medical device under investigation 
within the 4 weeks prior to the Screening Visit, or is currently participating in another study 
of a medical device under investigation.  
5. Subject has a known hypersensitivity to any excipients of bimekizumab. 
6. Subjects with a total ankylosis of the spine.  
7. Subjects with fibromyalgia or osteoarthritis symptoms that in the Investigator’s opinion 
would have potential to interfere with efficacy assessments. 
8. Subject had acute anterior uveitis within 6 weeks of the Baseline Visit. 
9. Subjects who have received more than 1 TNFα inhibitor and/or more than 2 additional 
non-TNFα biological response modifiers, or any IL-17 biological response modifier at any 
time are excluded (please refer to Table 7‒2).  
10. Subject is taking or has taken prohibited medications as outlined in Table 7‒2 without 
meeting the mandatory washout period(s) relative to the Baseline visit. 
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11. Subject has an active infection or history of infections as follows: 
− Any active infection (except common cold) within 14 days prior to Baseline. 
− A serious infection, defined as requiring hospitalization or iv anti-infectives within 
2 months prior to Baseline. 
− A history of opportunistic, recurrent or chronic infections that, in the opinion of the 
Investigator, might cause this study to be detrimental to the subject. Opportunistic 
infections are infections caused by uncommon pathogens (eg, Pneumocystis jirovicii, 
Cryptococcosis) or unusually severe infections caused by common pathogens (eg, 
cytomegalovirus [CMV], herpes zoster). 
12. Subject has concurrent acute or chronic viral hepatitis B or C or human immunodeficiency 
virus (HIV) infection. Subjects who have evidence of, or tested positive for hepatitis B or 
hepatitis C are excluded. 
A positive test for the hepatitis B virus (HBV) is defined as:  
− Positive for hepatitis B surface antigen (HBsAg+); or,  
− Positive for anti-hepatitis B core antibody (HBcAb+)  
A positive test for the hepatitis C virus (HCV) is defined as:  
− Positive for hepatitis C antibody (anti-HCV Ab), and  
− Positive via a confirmatory test for HCV (for example, HCV polymerase chain reaction). 
13. Subject has received any live (includes attenuated) vaccination within the 8 weeks prior to 
the Baseline Visit (eg, inactivated influenza and pneumococcal vaccines are allowed, but 
nasal influenza vaccination is not permitted) or has received Bacillus Calmette-Guerin 
vaccinations within 1 year prior to the Baseline Visit. 
14. Subject has known tuberculosis (TB) infection, at high risk of acquiring TB infection, or 
current or history of nontuberculous mycobacterium (NTMB) infection. A subject with latent 
tuberculosis (LTB) (a positive interferon-gammy release assay [IGRA] and diagnosis 
confirmed by TB specialist) may be rescreened once and enrolled after receiving at least 
4 weeks of appropriate LTB infection therapy and if no evidence of therapy-related 
hepatotoxicity has occurred prior to the first injection (alanine aminotransferase 
[ALT]/aspartate aminotransferase [AST] remain ≤3 times upper limit of normal [ULN]). 
Subject has a past history of active TB involving any organ system, unless adequately treated 
according to World Health Organization (WHO)/Center for Disease Control and Prevention 
(CDC) therapeutic guidance and proven to be fully recovered upon consult with a TB 
specialist. 
Refer to Section 12.7.5 for details on determining full TB exclusion criteria. 
15. Subject has a history of a lymphoproliferative disorder including lymphoma or current signs 
and symptoms suggestive of lymphoproliferative disease. 
16. Subject has any active malignancy or history of malignancy within 5 years prior to the 
Screening Visit EXCEPT treated and considered cured cutaneous squamous or basal cell 
carcinoma or in situ cervical cancer. 
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17a. Subject has a diagnosis of inflammatory conditions other than AS, including but not limited 
to psoriatic arthritis, rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, and 
reactive arthritis. Subjects with a diagnosis of Crohn’s disease, ulcerative colitis, or other 
IBD are allowed as long as they have no active symptomatic disease at Screening or 
Baseline. 
18. Subject has had major surgery (including joint surgery) within the 3 months prior to the 
Baseline, or has planned major surgery within 6 months after entering the study. 
19. Subject has any systemic disease (ie, cardiovascular, neurological, renal, hepatic, metabolic, 
gastrointestinal, hematological, immunological, etc) considered by the Investigator to be 
uncontrolled, unstable or likely to progress to a clinically significant degree during the course 
of the study. 
20. Subject has had myocardial infarction or stroke within the 6 months prior to the Screening 
Visit. 
21. Subject has laboratory abnormalities at Screening, including any of the following: 
a. ≥3.0 ULN of any of the following: ALT, AST, alkaline phosphatase (ALP); or >ULN 
total bilirubin (≥1.5xULN total bilirubin if known Gilbert’s syndrome) 
b. White blood cell (WBC) count <3.00 x103/µL 
c. Absolute neutrophil count <1.5 x103/µL 
d. Absolute lymphocyte count <500 cells/µL  
e. Hemoglobin <8.5g/dL 
f. Creatinine >2mg/dL 
g. Any other laboratory abnormality, which, in the opinion of the Investigator, will 
prevent the subject from completing the study or will interfere with the interpretation 
of the study results 
Individual screening tests for which the results are in error, borderline, or indeterminate for 
inclusion in the study, can be repeated once for confirmation during the Screening Period. 
Upon retesting, subjects whose results remain outside this threshold should not be 
randomized. 
22. Subject has any other condition, including medical or psychiatric, which, in the Investigator's 
judgment, would make the subject unsuitable for inclusion in the study.  
23. Presence of active suicidal ideation, or positive suicide behavior using the “Screening” 
version of the electronic Columbia-Suicide Severity Rating Scale (eC-SSRS) with either of 
the following criteria: 
− History of a suicide attempt within the 5 years prior to the Screening Visit. Subjects with 
a history of a suicide attempt more than 5 years ago should be evaluated by a mental 
healthcare practitioner (HCP) before enrolling into the study. 
− Suicidal ideation in the past month prior to the Screening Visit as indicated by a positive 
response (“Yes”) to either Question 4 or Question 5 of the “Screening” version of the 
eC-SSRS  
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24. Subject has moderately severe major depression or severe major depression, indicated by a 
score ≥15 using the Screening PHQ-9. Medication used to treat depression should be stable 
for 8 weeks prior to Baseline. 
25. Subject has a history of chronic alcohol or drug abuse within 6 months prior to Screening as 
evaluated by the Investigator based on medical history, site interview, and/or results of the 
specified urine drug screen.  
26. Subject is a member of Investigator site personnel directly affiliated with this study and/or 
their immediate families. Immediate family is defined as a spouse, parent, child, or sibling, 
whether biological or legally adopted. 
27. Subject is a UCB employee or employee of third-party organizations involved in the study. 
6.3 
Withdrawal criteria 
Subjects are free to withdraw from the study at any time, without prejudice to their continued 
care.  
Subjects should be withdrawn from the study if the subject withdraws his/her consent. 
Subjects should be withdrawn from IMP and encouraged by the Investigator to return for all 
scheduled visits through Week 52, and the SFU Visit (if the Week 52 Visit is ≥20 weeks after the 
final dose of IMP, the SFU Visit is not required) if any of the following events occur: 
1. The Sponsor or a regulatory agency requests withdrawal of the subject.  
2. Subject develops an illness that in the opinion of the Investigator would interfere with his/her 
continued participation if the risk of continuing IMP outweighs the potential benefit. 
3. Subject is noncompliant with the study procedures or medications in the opinion of the 
Investigator.  
4. Subject uses prohibited concomitant medications as defined in this protocol (Section 7.8.2), 
that may present a risk to the safety of the subject or the integrity of the study data, in the 
opinion of the Investigator and/or the Medical Monitor. 
5. Subject has a clinical laboratory value meeting any of the following criteria: 
a. Hepatotoxicity as described in Section 6.3.1. 
b. A laboratory value meeting any of the following criteria:  
− Absolute neutrophil count <1.0 x103/µL  
− Absolute lymphocyte count <200 cells/µL 
Subjects may remain on IMP if the result is transient. A retest is required within 1 to 2 weeks 
at a scheduled or unscheduled visit. If the repeat absolute neutrophil count or absolute 
lymphocyte count is still below the allowable values, the subject must be withdrawn from the 
IMP. If the repeat absolute neutrophil count or absolute lymphocyte count is above the 
allowable values, the subject may continue to receive IMP. 
6. The subject experiences a severe AE, an SAE, or a clinically significant change in a 
laboratory value occurs that, in the opinion of the Investigator, merits the discontinuation of 
the IMP and appropriate measures being taken. 
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7. There is confirmation of a pregnancy during the study, as evidenced by a positive pregnancy 
test (see Section 12.2 for more information regarding pregnancies). 
8. A subject considered as having either a suspected new LTB infection or who develops active 
TB or NTMB infection during the study (including but not limited to, conversion 
demonstrated by IGRA or other diagnostic means) must be immediately discontinued from 
IMP, and an ET Visit must be scheduled as soon as possible, but not later than the next 
regular visit. 
The subject must be permanently withdrawn if further examinations result in a diagnosis of 
active TB, or if the subject is diagnosed with latent TB infection (LTBI) with no initiation of 
prophylactic treatment, prematurely discontinues prophylactic treatment, or, in the opinion of 
the Investigator or Sponsor, is noncompliant with prophylactic TB therapy. 
Confirmed active TB is an SAE and must be captured in the eCRF in the SAE Report Form 
section. As with all SAEs, periodic follow-up reports should be completed as per protocol 
requirements until such time as the TB infection resolves. 
Additional information on TB policies is provided in Section 12.7.5. 
9. Subjects with newly diagnosed IBD or with IBD flares during the study must: 
− Be referred, as appropriate, to a healthcare professional treating IBD, such as a 
gastroenterologist 
− Discontinue IMP and be followed-up until resolution of active IBD symptoms 
If IBD flares increase in severity or frequency during the study, the Investigator should use 
clinical judgement in deciding whether the subject should continue on IMP and contact the 
Medical Monitor and UCB Study Physician to confirm the subject’s suitability for continued 
participation in the study. 
10. Subjects must be referred immediately to a mental healthcare professional and may be 
withdrawn from the study based upon the Investigator’s judgment of benefit/risk for: 
− Active suicidal ideation as indicated by a positive response (“Yes”) to Question 4 of the 
“Since Last Visit” version of the eC-SSRS  
− Moderately severe major depression as indicated by a PHQ-9 score of 15 to 19 if this 
represents an increase of 3 points compared to the last visit  
The mental health consultation must be recorded in the subject’s source documentation. 
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11. Subjects must be referred immediately to a mental healthcare professional and must be 
withdrawn from the study in case of: 
− Active suicidal ideation as indicated by a positive response ("Yes") to Question 5 of the 
"Since Last Visit" version of the eC-SSRS. 
− Any suicidal behavior since last visit. 
− Severe major depression as indicated by a PHQ-9 score ≥20. 
The mental health consultation must be recorded in the subject’s source documentation. 
12. Any subject who develops a clinically important infection or recurrent infections not 
responsive to standard therapy during the study must discontinue IMP until resolution of the 
infection. The Investigator should use clinical judgement in deciding whether the subject 
should restart IMP and contact the Medical Monitor and UCB study physician to confirm the 
subject’s suitability for continued participation in the study. 
Investigators should contact the Medical Monitor, whenever possible, to discuss the withdrawal 
of a subject from IMP or from the study in advance. 
Subjects withdrawing from the study who are not continuing for all scheduled visits, will 
undergo the ET Visit and the SFU Visit 20 weeks after their final dose of IMP, as applicable. 
For subjects considered as lost to follow-up, the Investigator should make an effort (at least 
1 phone call and 1 written message to the subject), and document his/her effort (date and 
summary of the phone call and copy of the written message in the source documents), to 
complete the final evaluation. All results of these evaluations and observations, together with a 
narrative description of the reason(s) for removing the subject, must be recorded in the source 
documents. The electronic Case Report Form (eCRF) must document the primary reason for 
withdrawal or discontinuation. 
Investigators should contact the Medical Monitor, whenever possible, to discuss the withdrawal 
of a subject in advance. 
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6.3.1 
Potential drug-induced liver injury IMP discontinuation criteria 
Subjects with potential drug-induced liver injury (PDILI) must be assessed to determine if IMP 
must be discontinued. In addition, all concomitant medications and herbal supplements that are 
not medically necessary should also be discontinued.  
The PDILI criteria below require immediate discontinuation of IMP for subjects with either of 
the following:  
• ALT or AST ≥8x ULN  
• ALT or AST ≥3xULN and coexisting total bilirubin ≥2xULN  
• Subjects with ALT or AST ≥3xULN who exhibit temporally associated symptoms of 
hepatitis or hypersensitivity. Hepatitis symptoms include fatigue, nausea, vomiting, right 
upper quadrant pain or tenderness. Hypersensitivity symptoms include fever (without clear 
alternative cause), rash, or eosinophilia (ie, >5%).  
If a nondrug-related cause for the symptoms can be confirmed, these subjects may resume 
IMP administration after discussion with the responsible UCB physician, but only when the 
requirements for rechallenge with IMP as provided in (Section 12.6.1.2.1) are followed.  
The PDILI criterion below allows for subjects to continue on IMP at the discretion of the 
Investigator.  
• Subjects with ALT or AST ≥5xULN and <8xULN, total bilirubin <2xULN, and no 
eosinophilia (ie, ≤5%), with no fever, rash, or symptoms of hepatitis (eg, fatigue, nausea, 
vomiting, right upper quadrant pain or tenderness).  
Evaluation of PDILI must be initiated as described in Section 12.6.1 with repeat tests performed 
in 2 weeks. Upon re-test, if ALT or AST values have reduced to <5xULN, the subject can 
continue with the study. However, if ALT or AST remains ≥5xULN and <8xULN after re-test, 
IMP should be temporarily withheld and subject should undergo a repeat test in 2 weeks. If ALT 
or AST values remain ≥5xULN even after the second re-test, then the subject should be 
immediately discontinued from IMP and should be followed for possible PDILI.  
If subjects are unable to comply with the applicable monitoring schedule, IMP must be 
discontinued immediately. 
Investigators should attempt to obtain information on subjects in the case of IMP discontinuation 
to complete the final evaluation. Subjects with PDILI should not be withdrawn from the study 
until investigation and monitoring are complete. All results of these evaluations and 
observations, as well as the reason(s) for IMP discontinuation and subject withdrawal (if 
applicable), must be recorded in the source documents. The eCRF must document the primary 
reason for IMP discontinuation. 
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7 
STUDY TREATMENTS 
7.1 
Description of investigational medicinal products 
The IMPs used in this study are bimekizumab and placebo. 
• 
 
 
 
• Placebo will be supplied as 0.9% sodium chloride aqueous solution (physiological saline, 
preservative free) of pharmacopoeia (US Pharmacopoeia/European Pharmacopoeia) quality 
in a 1mL PFS for sc injection. 
Details of the IMPs and their specification will be provided in the IMP Handling Manual.  
7.2 
Treatment(s) to be administered 
Unblinded study personnel will be responsible for recording the administration information on 
source documents, and administration of the IMP as sc injections. The unblinded personnel will 
not be involved in any other aspect of the study. During the Maintenance Period, bimekizumab 
will be administered by unblinded study personnel, unless the site-specific blinding plan allows 
for the administration by blinded study personnel.  
Suitable areas for sc injections are the lateral abdominal wall, upper arm, and upper outer thigh. 
Injection sites should be rotated and injections should not be given in areas where the skin is 
tender, bruised, red, or hard.  
An IMP Handling Manual will be provided to each site containing instructions regarding drug 
preparation and dosing. 
7.2.1 
Double-Blind Treatment Period 
Subjects will be randomized 2:1 to receive 1 of 2 blinded treatment regimens during the 
Double-Blind Treatment Period. To keep the blinding, all subjects will receive administrations as 
per the dosing scheme shown in Table 7‒1.  
The IMP (bimekizumab and placebo) will be administered at the time points indicated in 
Table 5-2. The Double-Blind Treatment Period ends with Week 16 assessments and the final 
dose in the Double-Blind Period will be administered at Week 12. 
During the Double-Blind Treatment Period, bimekizumab or placebo will be administered by 
unblinded study personnel at the study site. 
Table 7‒1: 
Overview on dosing during the Double-Blind Treatment Period 
Treatment arm 
Dosing 
BKZ 160mg sc Q4W  
Subjects will receive 1 BKZ 160mg injection sc at Week 0 
(Baseline) followed by BKZ 160mg sc Q4W at Weeks 4, 8, and 12.  
PBO sc Q4W 
Subjects will receive 1 PBO injection sc at Week 0 (Baseline) 
followed by PBO sc Q4W at Weeks 4, 8, and 12. 
BKZ=bimekizumab; PBO=placebo; Q4W=every 4 weeks, sc=subcutaneous 
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7.2.2 
Maintenance Period 
The 36-week Maintenance Period starts with the Week 16 IMP administration. All subjects will 
receive bimekizumab 160mg sc Q4W during the Maintenance Period and will receive treatments 
as follows: 
• Subjects who received bimekizumab 160mg sc Q4W during the 16-week Double-Blind 
Treatment Period will continue to receive bimekizumab 160mg sc Q4W.  
• Subjects who received placebo during the 16-week Double-Blind Treatment Period will be 
re-allocated to bimekizumab treatment. After the Week 16 assessments are performed, all 
subjects will receive bimekizumab 160mg sc at the Week 16 Visit.  
During the Maintenance Period, all subjects will receive bimekizumab, and the responsibility for 
recording the administration information and the administration of the IMP can be switched to 
the blinded team only if the site-specific blinding plan defines a process of maintaining the blind 
of the documentation of IMP administration of the Double-Blind Treatment Period.  
7.3 
Packaging 
The IMPs are manufactured, packaged, and labeled according to Good Manufacturing Practice 
(GMP) guidelines and applicable laws or regulations. Investigational medicinal products will be 
suitably packaged in such a way as to protect the IMPs from deterioration during transport and 
storage.  
7.4 
Labeling 
Clinical drug supplies will be labeled in accordance with the current International Council for 
Harmonisation (ICH) guidelines on Good Clinical Practice (GCP) and Good Manufacturing 
Practice and will include any locally required statements. If necessary, labels will be translated 
into the local language. 
7.5 
Handling and storage requirements 
Investigational Medicinal Product must be stored under refrigerated conditions (2ºC to 8ºC) 
protected from light. The IMP must not be frozen. 
The Investigator (or designee) is responsible for the safe and proper storage of IMP at the site. 
Investigational medicinal product stored by the Investigator is to be kept in a secured area with 
limited access according to the storage conditions mentioned on the label. 
Appropriate storage conditions must be ensured either by controlling the temperature (eg, room, 
refrigeration unit) or by completion of a temperature log in accordance with local requirements 
on a regular basis, showing actual and minimum/maximum temperatures reached over the time 
interval. 
In case an out-of-range temperature is noted, it must be immediately reported as per instructions 
contained in the IMP Handling Manual. 
7.6 
Drug accountability 
A Drug Accountability Form will be used to record IMP dispensing and return information on a 
by-subject basis and will serve as source documentation during the course of the study. Details of 
any IMP lost, damaged (due to breakage or wastage), not used, partially used, disposed of at the 
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study site, or returned to the Sponsor or designee must also be recorded on the appropriate forms. 
All supplies and pharmacy documentation must be made available throughout the study for UCB 
(or designee) to review. 
The packaging identifies each kit by a unique number and by the content. Unblinded study staff 
will be responsible for preparation (eg, breaking tamper proof sticker on kit) of the clinical trial 
material, including recording the administration information in the source document during the 
Double-Blind Treatment Period. During the Maintenance Period, bimekizumab will be 
administered by unblinded study personnel unless the site-specific blinding plan allows the 
administration by blinded study personnel (Section 7.2.2). 
All IMP documentation of the Double-Blind Treatment Period (eg, shipping receipts, drug 
accountability logs, IXRS randomization materials) must be maintained and accessed by 
unblinded, trained site personnel only. Designated, unblinded site personnel must be 
appropriately trained and licensed (per country guidelines) to administer injections. Each site 
will be required to have a written site-specific blinding plan in place signed by the Investigator, 
which will detail the site’s steps for ensuring that the double-blind nature of the study is 
maintained from Week 0 to Week 16/ET, and for defining site-specific responsibilities of the 
blinded and unblinded team during the course of the study. 
The Investigator (or designee) is responsible for retaining all used, unused, and partially used 
containers of IMP until returned or destroyed. 
The Investigator may assign some of the Investigator’s duties for drug accountability at the study 
site to an appropriate pharmacist/designee. 
The Investigator must ensure that the IMP is used only in accordance with the protocol. 
Periodically, and/or after completion of the clinical phase of the study, all used (including empty 
containers)/partially used, unused, damaged, and/or expired IMP must be reconciled and either 
destroyed at the site according to local laws, regulations, and UCB SOPs or returned to UCB (or 
designee). Investigational medicinal product intended for the study cannot be used for any other 
purpose than that described in this protocol. 
7.7 
Procedures for monitoring subject compliance 
During the Double-Blind Treatment Period and the Maintenance Period, bimekizumab and 
placebo will be administered in the clinic and compliance will be determined at the visit by study 
personnel. Drug accountability must be recorded on the Drug Accountability Form. 
7.8 
Concomitant medications/treatments 
All concomitant medications, including over-the-counter products, herbal, traditional remedies, 
vitamin or mineral supplements, other dietary supplements, “nutraceuticals,” and hormones must 
be recorded in the subject’s source documentation (eg, clinical chart) and on the eCRF. This 
record should include the name of the drug, the dose, the route and date(s) of administration, and 
the indication for use. 
Medications listed in Table 7‒2 are prohibited, restricted, or used as nonbiologic rescue therapy. 
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Table 7‒2: 
Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
Analgesics 
• 
Acetaminophen/ 
paracetamol 
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Stable dose/regimen permitted  
Ad hoc/PRN/“as needed use” 
permitted, but: 
No ad hoc/PRN/“as needed use” 
in the 24h prior to any study visit 
Ad hoc/PRN/“as needed use” permitted, but: 
No ad hoc/PRN/“as needed use” in the 24h prior to 
any study visit 
 
NSAID/COX-2 inhibitors  
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Stable dose/ regimen permitted 
No change until Week 20 Visit 
Nonbiologic rescue therapy will be at the 
Investigator’s discretion with the following options for 
symptoms: 
• 
For subjects taking an NSAID/COX-2 inhibitor 
dosing can be optimized; a change can be made to 
a different NSAID/COX-2 inhibitor; changes 
from an NSAID to a COX-2 inhibitor or from a 
COX-2 inhibitor to an NSAID are also permitted 
up to the maximum approved or tolerated dose, 
whichever is lower. Only 1 NSAID/COX-2 
inhibitor may be taken at a given time. 
• 
For subjects not taking NSAID/COX-2 inhibitors 
either 1 NSAID, or 1 COX-2 inhibitor can be 
initiated, up to the maximum approved or 
tolerated dose, whichever is lower. Only 
1 NSAID/COX-2 inhibitor may be taken at a 
given time. 
• 
For subjects who cannot take NSAIDs/COX-2 
inhibitors, topical NSAIDs are also a potential 
nonbiologic rescue therapy in regions where they 
are approved, up to the maximum approved or 
tolerated dose, whichever is lower.  
Mild potency opioids permitted 
only eg,: 
• 
Tramadol/any dose up to 
maximum approved dose 
• 
Codeine/only <90mg of 
codeine per dosage unit 
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Dosing/ schedule should remain 
stable for the first 20 weeks of 
the study 
Prohibited for rescue therapy 
 
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Table 7‒2: 
Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
Oral corticosteroids/average daily 
dose of ≤10mg/day prednisone or 
equivalent 
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Permitted, but: 
• 
No steroid bursts/tapers 
• 
No increase in steroid 
dosing 
• 
No initiation of steroids 
until the Week 20 Visit 
Prohibited for rescue therapy 
Topical corticosteroids 
None 
Permitted 
Not applicable 
Corticosteroids: 
• 
Intramuscular 
• 
Intravenous 
• 
Intra-articular  
• 
Bursal 
 
Use within 28 days prior to 
BL 
Prohibited unless used as rescue 
therapy from Week 20 or later 
Nonbiologic rescue therapy will be at the 
Investigator’s discretion with the following options for 
symptoms: 
• 
Sacroiliac joint steroid injection(s), either 
unilateral or bilateral. 
For non-axial symptoms: 
• 
One peripheral joint (or bursa) may be injected 
with a steroid at or after any visit where 
nonbiologic rescue therapy eligibility is assessed; 
however, the same joint may not be injected more 
than once during the study and should not be 
injected within 4 weeks of a sacroiliac joint 
injection(s). 
Intra-articular hyaluronic acid 
Use within 8 weeks prior 
to the BL Visit or during 
the study 
Prohibited 
Not applicable 
Any established antidepressant 
regimen 
Any change in dose/dose 
regimen within 8 weeks 
prior to BL 
Permitted 
Not applicable 
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Table 7‒2: 
Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
csARDs/formerly known as 
DMARDs 
 
 
 
• 
Azathioprine 
• 
Cyclosporine 
• 
Cyclophosphamide 
• 
Mycophenolic acid 
• 
Mycophenylate mofetil 
• 
Any other small molecule 
DMARDs 
Use within 8 weeks prior 
to BL 
Prohibited 
Prohibited for rescue  
• 
Methotrexate (MTX) 
 
Use within 12 weeks prior 
to BL unless Inclusion 
Criterion #9 is met 
Permitted 
MTX (≤25mg/week) 
For non-axial symptoms: 
• 
MTX may be added or increased to a maximum 
dose of 25mg/week, or the maximum tolerated 
dose, whichever is lower, in accordance with local 
standard of care. The route of administration may 
be changed from oral to sc or from sc to oral, at 
any visit at Week 20 or later. It is strongly 
recommended that subjects taking MTX are also 
taking folic acid supplementation. 
• 
Leflunomide (LEF) 
Use in the 6 months prior 
to the BL Visit (unless a 
cholestyramine washout 
has been performed; in 
which case, use up to 
28 days prior to the BL 
Visit is acceptable) unless 
Inclusion Criterion #9 is 
met 
Permitted 
LEF (≤20mg/day or an average 
of 20mg/day if not dosed daily) 
For non-axial symptoms: 
• 
Leflunomide may be given at a maximum dose of 
20mg/day (or an average of 20mg/day if not 
dosed daily), or the maximum tolerated dose, 
whichever is lower.  
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Table 7‒2: 
Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
• 
Hydroxychloroquine (HCQ) 
(and other anti-malarials) 
• 
Sulfasalazine (SSZ) 
• 
Apremilast 
 
Use within 8 weeks prior 
to BL unless Inclusion 
Criterion #10 is met 
Permitted 
For non-axial symptoms: 
• 
HCQ may be added or increased to a maximum 
dose of 400mg/day or the maximum tolerated 
dose, whichever is lower. Other anti-malarials 
may be used in accordance with local standard of 
care. 
• 
SSZ may be added or increased up to a maximum 
dose of 3g/day (up to 4g/day if in accordance with 
local standard of care), or the maximum tolerated 
dose, whichever is lower.  
• 
Apremilast may be given at a maximum dose of 
60mg/day and dosed as per Investigator’s 
discretion or local label. 
Combination DMARDs are allowed except that LEF 
and MTX may not be given together. 
JAK inhibitors 
 
 
 
• 
Eg, tofacitinib 
• 
Upadacitinib 
Use within 8 weeks prior 
to BL 
Prohibited 
Not applicable 
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Table 7‒2: 
Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
Biologic DMARDs 
 
 
 
TNFα inhibitors: 
• 
Infliximab (IFX) 
• 
Golimumab (GOL) 
• 
Certolizumab pegol (CZP) 
• 
Adalimumab (ADA) 
• 
Etanercept (ETN) 
• 
Biosimilar versions of any 
TNFα inhibitor 
For IFX, ADA, GOL, and 
CZP, any use within the 
12 weeks prior to the BL 
Visit 
For ETN, use within the 
28 days prior to the BL 
Visit 
Any use of >1 TNFα in the 
history 
Subjects not meeting 
Inclusion Criterion #11. 
Prohibited 
Not applicable 
Other biologics: 
• 
Abatacept 
Any use within 12 weeks 
prior to BL 
Prohibited 
Not applicable 
• 
Alefacept 
 
 
• 
Efalizumab 
 
 
• 
Guselkumab 
 
 
• 
Sarilumab 
 
 
• 
Sirukumab 
 
 
• 
Tocilizumab 
 
 
• 
Others in development 
targeting IL-6 or IL-6R 
 
 
• 
Ustekinumab 
 
Any use within 24 weeks 
prior to BL 
Prohibited 
Not applicable 
• 
Tildrakizumab 
Any use within 4 months 
prior to BL 
Prohibited 
Not applicable 
• 
Risankizumab 
Any use within 5 months 
prior to BL 
Prohibited 
Not applicable 
• 
Briakinumab 
 
Any use within 6 months 
prior to BL 
Prohibited 
Not applicable 
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Table 7‒2: 
Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
• 
Rituximab (incl. biosimilars), 
ocrelizumab 
Any use within 12 months 
prior to BL 
Prohibited 
Not applicable 
Anti-IL-17 therapy: 
• 
Bimekizumab 
• 
Secukinumab 
• 
Ixekizumab 
• 
Brodalumab 
• 
Others in development 
Any exposure history 
Prohibited 
Not applicable 
BL=Baseline; ADA=adalimumab; COX-2=cyclooxygenase 2; csARD=conventional synthetic antirheumatic drug; CZP=certolizumab pegol; 
DMARD=disease-modifying antirheumatic drug; ETN=etanercept; GOL=golimumab; h=hour; HCQ=hydroxychloroquine; IFX=infliximab; JAK=Janus 
kinase; LEF=leflunomide; IL=interleukin; MTX=methotrexate; NSAID=nonsteroidal anti-inflammatory drug; PRN=as needed; sc=subcutaneous; 
SSZ=sulfasalazine; TNFα=tumor necrosis factor alpha 
a 
Note: any medication not listed here for rescue therapy must be approved by the Medical Monitor prior to starting that medication. 
 
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7.8.1 
Permitted concomitant treatments (medications and therapies) 
No medication increases or additions for AS are permitted until after the Week 20 Visit 
assessments. However, a decrease in dose or dosing frequency of any agent is permitted for 
reasons of intolerance/AEs/side-effects at any time. Permitted nonbiologic rescue therapy is 
described in Table 7‒2. 
Whenever possible, physical therapy/physiotherapy/non-medication/complementary and 
alternative treatment(s) (including traditional Chinese medications) of AS should remain stable 
through the Week 20 Visit.  
Subjects are allowed to use any other medications, including biologics, after at least 28 days of 
their final dose of the IMP. This is applicable for subjects who discontinue from the study early, 
including those permanently withdrawn from IMP, or subjects who have completed the study 
treatment without entering the extension study and are in the SFU Period. 
7.8.2 
Prohibited concomitant treatments (medications and therapies) 
Prohibited concomitant treatments are described in Table 7‒2. 
7.8.3 
Nonbiologic rescue therapy 
Nonbiologic rescue therapy will be at the Investigator’s discretion as add-on therapy to 
bimekizumab at any time from Week 20 or later as described in Table 7‒2. 
7.8.4 
Vaccines 
Administration of live (including attenuated) vaccines is not allowed during the conduct of the 
study and for 20 weeks after the final dose of IMP. Administration of inactivated vaccines is 
allowed during the study at the discretion of the Investigator. 
7.9 
Blinding 
Due to differences in presentation between bimekizumab and placebo treatments in the 
Double-Blind Treatment Period up to Week 16, special precautions will be taken to ensure study 
blinding and study sites will have blinded and unblinded personnel. 
Bimekizumab and placebo injections will be administered at the investigational sites by 
unblinded, dedicated study personnel according to the site-specific blinding plan (Section 7.2). 
The unblinded personnel will not be involved in the study in any way other than assuring the 
medication is taken from the correct kit and prepared according to the pharmacy manual 
instructions, and administering the drug to the subjects.  
A full blinding plan for the Week 24 interim statistical analysis will be written as described in 
Section 15.8.1.  
7.9.1 
Procedures for maintaining and breaking the treatment blind 
7.9.1.1 
Maintenance of study treatment blind 
All subject treatment details will be allocated and maintained by the interactive response 
technology (IXRS) system.  
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7.9.1.2 
Breaking the treatment blind in an emergency situation 
The integrity of this clinical study must be maintained by observing the treatment blind. In the 
event of an emergency for which the appropriate treatment for a subject cannot be made without 
knowing the treatment assignment, it will be possible to determine to which treatment arm and 
dose the subject has been allocated by contacting the IXRS. All sites will be provided with 
details of how to contact the system for code breaking at the start of the study. The Medical 
Monitor or equivalent should be consulted prior to unblinding, whenever possible. 
The Clinical Project Manager (CPM) will be informed immediately via the IXRS when a code is 
broken, but will remain blinded to specific treatment information. Any unblinding of the IMP 
performed by the Investigator must be recorded in the source documents and on the Study 
Termination eCRF page. 
7.10 
Randomization and numbering of subjects 
An IXRS will be used for assigning eligible subjects to a treatment regimen based on a 
predetermined production randomization and/or packaging schedule provided by the UCB (or 
designee). The randomization schedule will be produced by the IXRS vendor. The IXRS will 
generate individual assignments for subject kits of IMP, as appropriate, according to the visit 
schedule. Subjects treatment assignment will be stratified by region and prior TNFα inhibitor 
exposure (yes/no). Enrollment of TNFα inhibitor-experienced subjects will be limited to 30% of 
the total study population.  
At Screening, each subject will be assigned a 5-digit number that serves as the subject identifier 
throughout the study. The subject number will be required in all communication between the 
Investigator or designee and the IXRS regarding a particular subject. Subjects who were screen 
failures in AS0010 and who are rescreened in AS0011, will be assigned a new subject number 
and will be registered in IXRS. 
Eligible subjects will be randomized to treatment groups at the Baseline Visit (Day 1). To 
randomize a subject, unblinded study personnel will contact the IXRS and provide brief details 
about the subject to be randomized. The IXRS will automatically inform the unblinded study 
personnel of the subject’s randomization number and the treatment arm assigned. At the end of 
the 16-week Double-Blind Treatment Period subjects receiving placebo will be re-allocated to 
the bimekizumab treatment group. The IXRS will allocate kit numbers to the subject based on 
the subject number during the course of the study. Subject numbers and kit numbers will be 
tracked via the IXRS. 
8 
STUDY PROCEDURES BY VISIT  
The Schedule of Assessments (Table 5-2) provides a general overview of study assessments. A 
list of procedures to be completed at each visit is described below.  
Visit windows are ±3 days from Baseline (Day 1, first dose of IMP) at all visits through the 
Week 16 Visit and ±4 days from all visits thereafter. For the SFU Visit (20 weeks after the final 
dose), the visit should occur no more than 3 days prior to the scheduled visit date and within 
7 days after the scheduled visit date (-3 days/+7 days). The minimum amount of time between 
bimekizumab doses should be no less than 25 days and no more than 31 days from Baseline to 
Week 16 and 24 to 32 days thereafter. When applying the allowed visit windows, it must be 
ensured that the time between these 2 visits does not exceed the allowed time between doses. 
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Changes to the dosing schedule outside of the allowed windows should be discussed with the 
Medical Monitor and may result in subject withdrawal. 
8.1 
Screening (Visit 1) 
The Screening Period will last for a minimum of approximately 14 days (unless a screenfailed 
subject from AS0010 will be screened in AS0011) and up to a maximum of 35 days. 
Prior to any study specific activities, subjects will be asked to read, sign, and date an Informed 
Consent Form (ICF) that has been approved by the Sponsor and an IEC/IRB, and that complies 
with regulatory requirements. Subjects will be given adequate time to consider any information 
concerning the study given to them by the Investigator (or designee). As part of the informed 
consent procedure, subjects will be given the opportunity to ask the Investigator any questions 
regarding potential risks and benefits of participation in the study. 
Subjects will also be given the option to participate in the pharmacogenomic and/or MRI 
substudies. Subjects who decide to participate in the substudies will need to complete a separate 
ICF following the same procedure and given the same considerations as the main ICF. Their 
willingness to participate in the substudies will be independent from their consent to participate 
in the main study. 
Subjects who initially fail to meet selected eligibility criteria (including but not limited to 
documented completion of LTBI prophylactic therapy) or for whom eligibility assessments could 
not be completed as planned may be rescreened once after discussion with the Medical Monitor. 
An overview on rescreening/retesting requirements is provided in Section 5.1.1.1 and 
Section 5.1.1.2. 
The following procedures or assessments will be performed at the Screening Visit: 
• Obtain written informed consent for the main study and for the MRI and/or the 
pharmacogenomic substudies for participating subjects. 
• Collect demographic data including the lifestyle and infection history. 
• Collect AS history including extra-articular manifestations (EAMs). 
• Collect significant past medical history and concomitant diseases. 
• Assess that all inclusion and no exclusion criteria are met. 
• Record prior medications. 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the BASDAI. 
• Administer the TB questionnaire. 
• Measure BP, pulse, and temperature. 
• Measure height and body weight. 
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• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB.  
• Perform an ECG. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Serum pregnancy test if the subject is a woman of childbearing potential.  
− Hepatitis B and C tests. 
− HIV test. 
− HLA-B27 status. 
− IGRA TB test. 
• Collect urine samples for: 
− Urinalysis. 
− Urine drug screen. 
• Obtain a chest x-ray, unless one has been obtained within 3 months prior to the Screening 
Visit. Any findings suggestive of active TB are exclusionary. 
• Obtain an x-ray of the sacroiliac joint unless one has been obtained up to 6 months prior to 
Screening or as part of screening for AS0010 (see Section 9.20.1 for details). 
• Register the subject using the interactive voice or web response system (IXRS). 
8.2 
Baseline (Visit 2, Day 1, first dose of IMP) 
The following procedures of assessments will be completed prior to administration of IMP: 
• Review significant past medical history and concomitant diseases to ensure there are no 
significant changes in medical history that would exclude the subject based on the exclusion 
criteria. 
• Confirm that the subject meets all inclusion and no exclusion criteria. 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
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• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the TB questionnaire. 
• Administer the FACIT-Fatigue subscale. 
• Administer the EQ-5D-3L. 
• Administer the WPAI-SHP. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB.  
• Perform the TJC and SJC assessment. 
• Determine the MASES. 
• Determine the BASMI. 
• Administer the PhGADA. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• For subjects consenting on a separate ICF for participation in the pharmacogenomic 
substudy: 
− Collect serum and plasma samples for exploratory biomarkers. 
− Collect ribonucleic acid (RNA) blood samples for exploratory biomarkers. 
− Collect blood samples for genetic/epigenetic analysis. 
− Collect stool samples. 
• Obtain an x-ray of the spine unless one has been obtained up to 6 months prior to Screening 
(see Section 9.20.2 for details). The spine x-ray must be performed prior to or no later than 
on the day of the second administration of IMP. 
• Obtain MRIs of the sacroiliac joint and the spine for subjects consenting on a separate ICF 
for participation in the MRI substudy prior to the first IMP administration (see Section 9.20.3 
for details). 
• Randomize the subject using the IXRS. 
• Administer IMP. 
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The following procedures of assessments will be completed following administration of IMP: 
• Measure vital signs approximately 30 minutes and 1 hour after dosing. 
8.3 
Double-Blind Treatment Period 
8.3.1 
Week 1 (±3 days) (Visit 3)  
• Record concomitant medications. 
• Record AEs. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Record the visit in the IXRS. 
8.3.2 
Week 2 (±3 days) (Visit 4) 
• Record concomitant medications. 
• Record AEs. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations. 
• Record the visit in the IXRS. 
8.3.3 
Week 4 (±3 days) (Visit 5) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
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• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the FACIT-Fatigue subscale. 
• Administer the EQ-5D-3L. 
• Measure BP, pulse, and temperature. 
• Determine the MASES. 
• Administer the PhGADA. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.3.4 
Week 8 (±3 days) (Visit 6) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Perform the TJC and SJC assessment. 
• Determine the MASES. 
• Determine the BASMI. 
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• Administer the PhGADA. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.3.5 
Week 12 (±3 days) (Visit 7) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the TB questionnaire. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.3.6 
Week 16 (±3 days) (Visit 8) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
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• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the FACIT-Fatigue subscale. 
• Administer the EQ-5D-3L. 
• Administer the WPAI-SHP. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Perform the TJC and SJC assessment. 
• Determine the MASES. 
• Determine the BASMI. 
• Administer the PhGADA. 
• Perform an ECG. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Collect urine samples for: 
− Urinalysis. 
− Urine pregnancy test if the subject is a woman of childbearing potential.  
• For subjects consenting on a separate ICF for participation in the pharmacogenomic 
substudy: 
− Collect serum and plasma samples for exploratory biomarkers. 
− Collect RNA blood samples for exploratory biomarkers. 
− Collect blood samples for genetic/epigenetic analysis. 
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• Obtain MRIs of the sacroiliac joint and the spine for subjects consenting on a separate ICF 
for participation in the MRI substudy. Magnetic resonance imaging at Week 16 should be 
performed within ±5 days (see Section 9.20.3 for details). 
• Record the visit in the IXRS. 
• Administer IMP. 
The following procedures of assessments will be completed following administration of IMP: 
• Measure vital signs approximately 30 minutes and 1 hour after dosing. 
8.4 
Maintenance Period  
8.4.1 
Week 20 (±4 days) (Visit 9) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.4.2 
Week 24 (±4 days) (Visit 10) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the TB questionnaire. 
• Administer the FACIT-Fatigue subscale. 
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• Administer the EQ-5D-3L. 
• Administer the WPAI-SHP. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Perform the TJC and SJC assessment. 
• Determine the MASES. 
• Determine the BASMI. 
• Administer the PhGADA. 
• Perform an ECG. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.4.3 
Week 28 (±4 days) (Visit 11) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for hematology and biochemistry. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.4.4 
Week 32 (±4 days) (Visit 12) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Measure BP, pulse, and temperature. 
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• Collect blood samples for hematology and biochemistry. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.4.5 
Week 36 (±4 days) (Visit 13) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the TB questionnaire. 
• Administer the FACIT-Fatigue subscale. 
• Administer the EQ-5D-3L. 
• Administer the WPAI-SHP. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Administer the PhGADA. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Collect urine samples for: 
− Urinalysis. 
− Urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
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• Administer IMP. 
8.4.6 
Week 40 (±4 days) (Visit 14)  
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for hematology and biochemistry. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.4.7 
Week 44 (±4 days) (Visit 15) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− IGRA TB test. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
8.4.8 
Week 48 (±4 days) (Visit 16) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the TB questionnaire. 
• Measure BP, pulse, and temperature. 
• Collect blood samples for hematology and biochemistry. 
• Perform a urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
• Administer IMP. 
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8.4.9 
Week 52 (±4 days) (Visit 17) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the FACIT-Fatigue subscale. 
• Administer the EQ-5D-3L. 
• Administer the WPAI-SHP. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Perform the TJC and SJC assessment. 
• Determine the MASES. 
• Determine the BASMI. 
• Administer the PhGADA. 
• Perform an ECG. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Collect urine samples for: 
− Urinalysis. 
− Urine pregnancy test if the subject is a woman of childbearing potential.  
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• For subjects consenting on a separate ICF for participation in the pharmacogenomic 
substudy: 
− Collect serum and plasma samples for exploratory biomarkers. 
− Collect RNA blood samples for exploratory biomarkers. 
− Collect blood samples for genetic/epigenetic analysis. 
− Collect stool samples 
• Obtain MRIs of the sacroiliac joint and the spine for subjects consenting on a separate ICF 
for participation in the MRI substudy. Magnetic resonance imaging should be performed 
within ±5 days of the Week 52 Visit (see Section 9.20.3 for details). 
• Record the visit in the IXRS. 
8.5 
Early Termination Visit (if applicable) 
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the ASQoL. 
• Administer the BASDAI. 
• Administer the BASFI. 
• Administer the SF-36 questionnaire. 
• Administer the MOS Short Sleep Scale (12 items). 
• Perform the PGADA. 
• Administer the total and nocturnal spinal pain NRS. 
• Administer the TB questionnaire. 
• Administer the FACIT-Fatigue subscale. 
• Administer the EQ-5D-3L. 
• Administer the WPAI-SHP. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Determine the MASES. 
• Determine the BASMI. 
• Administer the PhGADA. 
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• Perform an ECG. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Collect urine samples for: 
− Urinalysis. 
− Urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
8.6 
Safety Follow-Up Visit (-3 days/+7 days)  
• Record concomitant medications. 
• Record AEs. 
• Administer the eC-SSRS and the PHQ-9. 
• Administer the TB questionnaire. 
• Measure BP, pulse, and temperature. 
• Measure body weight. 
• Perform a physical examination, including an evaluation for signs and symptoms of active 
TB, and risk for exposure to TB. 
• Perform an ECG. 
• Collect blood samples for: 
− Hematology and biochemistry. 
− CRP. 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
• Collect samples for: 
− Urinalysis. 
− Urine pregnancy test if the subject is a woman of childbearing potential.  
• Record the visit in the IXRS. 
8.7 
Unscheduled Visit 
At the Investigator’s discretion, an Unscheduled Visit may be completed at any time during the 
study but prior to the SFU Visit, if deemed necessary for the subject’s safety and well-being.  
If an Unscheduled Visit is conducted due to safety or efficacy reasons, an eC-SSRS assessment 
will be performed with the subject during the visit. If an Unscheduled Visit is conducted for 
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reasons other than safety or efficacy concerns (eg, repeated collection of a laboratory specimen 
due to collection or analysis issues) an eC-SSRS will not be required at these visits.  
At this visit, assessments including, but not limited to the following may be performed, 
depending on the reason for the visit: 
• Record concomitant medication. 
• Record AEs. 
• Administer the eC-SSRS. 
• Measure BP, pulse, and temperature.  
• Physical examination. 
• Record 12-lead ECG. 
• If indicated, obtain blood sample(s) for: 
− Standard safety laboratory tests (hematology, serum chemistry). 
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection. 
− An IGRA TB test. 
• Obtain urine sample for: 
− Urine pregnancy test. 
− Urinalysis. 
9 
ASSESSMENT OF EFFICACY 
9.1 
ASAS20, 40, ASAS 5/6 response, and ASAS-PR 
The ASAS20 response is defined as an improvement of at least 20% and absolute improvement 
of at least 1 unit on a 0 to 10 NRS in at least 3 of the 4 following domains: 
• PGADA (see Section 9.8) 
• Pain assessment (the total spinal pain NRS score; see Section 9.9) 
• Physical function (measured by BASFI, Section 9.5) 
• Inflammation (the mean of the BASDAI Questions 5 and 6, [see Section 9.3] concerning 
morning stiffness intensity and duration)  
and absence of deterioration in the potential remaining domain (deterioration is defined as a 
relative worsening of at least 20% and an absolute worsening of at least 1 unit). 
The ASAS criteria for 40% improvement are defined as relative improvements of at least 40%, 
and absolute improvement of at least 2 units on a 0 to 10 NRS in at least 3 of the 4 domains and 
no worsening at all in the remaining domain. 
The ASAS 5/6 response is defined as at least 20% improvement in 5 of 6 domains, including 
spinal mobility (lateral spinal flexion) and CRP as more objective measures (Brandt et al, 2004). 
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The ASAS-PR is defined as a score of ≤2 units on a 0 to 10 unit scale in all 4 domains listed 
above for ASAS20. 
The ASAS20, 40, ASAS 5/6 response, and ASAS-PR will be derived from assessments at the 
visits specified in Table 5-2.  
9.2 
ASQoL 
The ASQoL, a validated disease-specific 18-item questionnaire, has been developed specifically 
for measuring health-related quality of life (HRQoL) in subjects with AS (Doward et al, 2003). 
The ASQoL has been used and has shown to be responsive in axSpA (Barkham et al, 2009; 
Haibel et al, 2008). Each statement on the ASQoL is given a score of 1 = Yes or 0 = No. A score 
of "1" is given where the item is affirmed, indicating adverse quality of life. All item scores are 
summed to total score ranging from 0 to 18 with a higher score indicating worse HRQoL.  
The ASQoL will be assessed by the subject at the visits specified in Table 5-2. 
9.3 
Inflammation – BASDAI (mean of Questions 5 and 6) 
Question 5 of the BASDAI (described completely in Section 9.4) measures intensity of morning 
stiffness. The subject considers the previous week and responds to the question, “How would 
you describe the overall level of morning stiffness you have had from the time you wake up?” 
The response is indicated on a 10-point NRS in which 0=None and 10=Very severe. Question 6 
of the BASDAI measures duration of morning stiffness. The subject considers the previous week 
and responds to the question, “How long does your morning stiffness last from the time you 
wake up? The response is indicated on a 10-point NRS in which 0=0 hours, 5=1 hour, and 
10=2 or more hours. The ratings for each question are summed and divided by 2 to provide the 
mean of questions 5 and 6.  
The BASDAI Questions 5 and 6 will be assessed by the subject at the visits specified  
in Table 5-2. 
9.4 
BASDAI 
The most common instrument used to measure the disease activity of AS from the subject’s 
perspective is the BASDAI (Garrett et al, 1994). The BASDAI is a validated self-reported 
instrument which consists of six 10-unit horizontal NRSs to measure severity of fatigue, spinal 
and peripheral joint pain and swelling, enthesitis, and morning stiffness (both severity and 
duration, respectively) over the last week (van Tubergen et al, 2015). The final BASDAI score 
ranges from 0 to 10, with lower scores indicating lower disease activity. 
 
 
and the score is used as the “total back pain” factor in the calculation of ASDAS-CRP. 
 
 and the score is used as the “peripheral 
pain/swelling” factor in the calculation of ASDAS-CRP. Question 6 of the BASDAI asks the 
subject to describe his/her overall stiffness from the time of awakening in the past week, and the 
score is used as the “duration of morning stiffness” factor in the calculation of ASDAS-CRP. 
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The BASDAI total score is calculated as follows:  
𝐵𝐴𝑆𝐷𝐴𝐼=
Q1+Q2+Q3+Q4+(𝑄5+𝑄6
2
)
5
  
 
 
 
 
Fatigue item of the BASDAI 
Fatigue, as a major symptom of AS, can effectively be measured with single-item questions such 
as the BASDAI item (van Tubergen et al, 2002b). This item has shown moderate to good 
reliability and responsiveness (van Tubergen et al, 2002b). The same minimal clinically 
important difference (MCID) will be used for the fatigue item of the BASDAI as for the total 
BASDAI score, ie, a change of 1 unit on the NRS. 
The BASDAI will be assessed at the visits specified in Table 5-2.  
9.5 
Physical function – BASFI 
The BASFI is a validated disease-specific instrument for assessing physical function (van der 
Heijde et al, 2005; Calin et al, 1994). The BASFI comprises 10 items relating to the past week. 
The NRS version will be used for the answering options of each item on a scale of 0 (“Easy”) 
to 10 (“Impossible”) (van Tubergen et al, 2015; van Tubergen et al, 2002a). The BASFI is the 
mean of the 10 scores such that the total score ranges from 0 to 10, with lower scores indicating 
better physical function. The MCID used to interpret scores is 7mm on a 0 to 100mm VAS or 
17.5% of the Baseline score (Pavy et al, 2005); an MCID of 1 unit will be used for the NRS 
version.  
The BASFI will be assessed by the subject at the visits specified in Table 5-2. 
9.6 
SF-36 
The SF-36 (Version 2, standard recall) is a 36-item generic HRQoL instrument that uses a recall 
period of 4 weeks. Items are grouped into 8 domains as follows: Physical Functioning (10 items), 
Role Physical (4 items), Bodily Pain (2 items), General Health (5 items), Vitality (4 items), 
Social Functioning (2 items), Role Emotional (3 items), Mental Health (5 items). One additional 
item asks respondents about health change (Health Transition) over the past year. The concepts 
represented by these domains contribute to physical, mental, and social aspects of HRQoL. 
In addition to domain scores, the Physical Component Summary and Mental Component 
Summary scores are calculated from the 8 domains (excluding the Health Transition item). 
Component scores appreciate the impact of each domain on physical and mental health status 
(Maruish, 2011). The norm-based T-scores for the 2 SF-36 component summary (PCS and MCS) 
and the 8 domain scores are standardized with a mean of 50 and a standard deviation (SD) of 10 
in the general US population (Maruish, 2011). An individual respondent’s score that falls outside 
the T-score range of 45 to 55 should be considered outside the average range for the US general 
population. When considering group-level data, a score below 47 should be considered indicative 
of impaired functioning within that health domain or dimension. Similar to individual respondent 
data, group mean scores of 47 or greater should be considered average or above average as 
compared to the general US population. Higher scores indicate a better health status. 
The SF-36 will be assessed by the subject at the visits specified in Table 5-2. 
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9.7 
MOS-12 
The MOS Sleep Scale is a validated generic self-administered scale measuring specific aspects 
of sleep. The frequency with which each problem has been experienced during the previous 
4 weeks is rated on a 5-point scale ranging from “none of the time” to “all of the time,” except 
sleep quantity, which is reported in hours. All scores are transformed linearly to range from 
0 to 100, again with the exception of the sleep quantity subscale, which is scored in hours. 
Higher scores indicate more of the attribute implied by the scale name (eg, more sleep 
disturbance, more adequate sleep, and greater sleep quantity). The psychometric properties of the 
MOS Sleep Scale have been found to be satisfactory by Hays and colleagues (Hays et al, 2005). 
The domains of interest for this study are the Sleep Disturbance and the Sleep Problems Index II 
domains.  
The MOS-12 Sleep Scale will be assessed by the subject at the visits specified in Table 5-2. 
9.8 
PGADA 
Subjects will score the global assessment of their disease activity in response to the question 
“How active was your spondylitis on average during the last week?” using a NRS where 0 is 
“not active” and 10 is “very active” (van Tubergen et al, 2015).  
The PGADA will be assessed by the subject at the visits specified in Table 5-2.  
9.9 
Total and nocturnal spinal pain 
The pain experienced by AS subjects is adequately measured by 2 separate questions: 1) total 
pain in the spine due to AS (ie, “How much pain of your spine due to spondylitis do you have?”); 
and 2) pain in the spine at night due to AS (ie, “How much pain of your spine due to spondylitis 
do you have at night?”) (Sieper et al, 2009; van der Heijde et al, 2005; Committee for Proprietary 
Medicinal Product [CPMP]/EWP/556/95, 2004). When responding to each question, the subject 
is to consider the average amount of pain in the preceding week.  
Total and nocturnal spinal pain will be assessed by the subject at the visits specified in 
Table 5-2. 
9.10 
FACIT-Fatigue subscale 
The FACIT-F is a 40-item measure that assesses self-reported fatigue and its impact upon daily 
activities and function over the past 7 days (FACIT.org). The scale consists of 5 subscales 
(physical well-being, social/family well-being, emotional well-being, functional well-being, and 
fatigue). The fatigue subscale is the only one used in this study. It is composed of 13 items, all 
scored from 0 (Not at all) to 4 (Very much). The FACIT-Fatigue subscale score ranges from 0 to 
52 with 0 being the worst possible score and 52 being the best possible score. To obtain a score 
from 0 to 52, all negatively worded questions have to be recoded, so that responses range from 
worst (0) to the best (4) outcome.   
The FACIT-Fatigue subscale will be completed by the subject at the visits specified in Table 5-2. 
9.11 
EQ-5D-3L 
The EQ-5D-3L is comprised of a 5-item health status dimension and a VAS. The response to 
each of the 5 health status dimensions is divided into 3 levels (no problem, some or moderate 
problems, or extreme problems) and is scored as 1, 2, and 3, respectively. The EQ-5D-3L VAS 
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records the respondent’s self-rated health status on a vertical 20cm scale, 0 to 100 graduated 
(0=worst imaginable health status, 100=best imaginable health status). 
The EQ-5D-3L will be assessed by the subject at the visits specified in Table 5-2. 
9.12 
TJC and SJC (44/44) 
The following 44 joints are to be examined for tenderness and swelling by the Investigator, 
another delegated physician, or an appropriately qualified medical professional (based on local 
requirements) who has had documented training on how to perform these assessments correctly. 
Preferably the same assessor should evaluate the subject at each arthritis assessment. 
• Upper body (4) – bilateral sternoclavicular, and acromioclavicular joints. 
• Upper extremity (26) – bilateral shoulders, elbows, wrists (includes radiocarpal, carpal and 
carpometacarpal bones considered as a single unit), metacarpophalangeals (MCPs) I, II, III, 
IV, and V, and thumb interphalangeals (IPs), and proximal IPs (PIPs) II, III, IV, and V. 
• Lower extremity (14) – bilateral knees, ankles, and metatarsophalangeals (I, II, III, IV, 
and V). 
The assessment for tenderness and swelling is made on 44 joints from the above list. Artificial 
and ankylosed joints are excluded from swelling and tenderness assessments. The assessments 
per visit are described in the schedule of study assessments Table 5-2. 
Table 9‒1 summarizes the swelling and tenderness grading criteria. 
Table 9‒1: 
Tenderness and swelling grading 
Grade 
Tenderness response (44) 
Swelling response (44) 
0 
Not tender  
None 
1 
Tenderness present  
Detectable synovial thickening 
9.13 
WPAI-SHP v2.0 
The WPAI-SHP v2.0 is a patient-reported questionnaire that assesses subject’s employment 
status, work absenteeism, work impairment while working (presenteeism), overall work, and 
daily activity impairment attributable to a specific health problem (WPAI-SHP) (Reilly et al, 
1993). It has been used in several clinical studies of biologic therapy in subjects with plaque PSO 
(Kimball et al, 2012; Vender et al, 2012). 
Five out of 6 items of the WPAI-SHP are regrouped into the 4 dimensions, with scores expressed 
as percentage, where higher numbers indicate greater impairment and less productivity, ie, worse 
outcomes, as described in the WPAI-SHP scoring rules. 
The WPAI-SHP v2.0 will be assessed by the subject at the visits specified in Table 5-2. 
9.14 
CRP 
Blood will be collected for measurement of CRP (ie, determination of hs-CRP). After Baseline, 
the CRP data will not be sent to the Investigator to protect the blinded nature of the treatment 
assignments and response. 
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9.15 
ASDAS 
The ASDAS is comprised of a number of assessments which are scored by the subject and 
Investigator and multiplied by a validated formula (van der Heijde et al, 2009) as listed: 
• 0.121 x Total back pain (BASDAI Q2 result, Section 9.4) 
• 0.058 x Duration of morning stiffness (BASDAI Q6 result, Section 9.4) 
• 0.110 x PGADA (Section 9.8) 
• 0.073 x Peripheral pain/swelling (BASDAI Q3 result, Section 9.4) 
• 0.579 x (natural logarithm of the CRP [mg/L] + 1)  
Back pain, PGADA, duration of morning stiffness, peripheral pain/swelling, and fatigue are all 
assessed on a numerical scale (0 to 10 units) (Lukas et al, 2009). The results of these calculations 
are summed to calculate the ASDAS.  
The variables related to ASDAS disease activity are defined as follows: 
• ASDAS-Inactive Disease (ASDAS-ID): ASDAS <1.3 
• ASDAS-Low Disease activity (ASDAS-LD): ASDAS ≥1.3, <2.1 
• ASDAS-High Disease activity (ASDAS-HD): ASDAS ≥2.1, ≤3.5 
• ASDAS-very High Disease activity (ASDAS-vHD): ASDAS >3.5 
The variable related to ASDAS improvement is defined as follows: 
• ASDAS-MI: ASDAS reduction (improvement) of ≥2.0 relative to Baseline 
The ASDAS variables will be derived from assessments at the visits specified in Table 5-2. 
9.16 
MASES 
Enthesitis is assessed with the MASES. The MASES is an index that measures the severity (ie, 
intensity and extent) of enthesitis through the assessment of 13 entheses (bilateral 
costochondral 1, costochondral 7, anterior superior iliac spine, posterior iliac spine, iliac crest 
and proximal insertion of the Achilles tendon sites, and the fifth lumbar vertebral body spinous 
process) (Heuft-Dorenbosch et al, 2003) each scored as 0 or 1 and then summed for a possible 
score of 0 to 13. 
The MASES will be assessed at the visits specified Table 5-2. 
9.17 
BASMI 
The BASMI characterizes the spinal mobility of subjects with AS. The BASMI is a 
disease-specific measure consisting of 5 clinical measures to reflect subject axial status: cervical 
rotation; tragus to wall distance; lateral spinal flexion; modified Schober test; intermalleolar 
distance. Each of the 5 movements is scored according to the linear BASMI definition. The mean 
of the 5 scores provides the BASMI score. The higher the BASMI score the more severe the 
subject’s limitation of movement due to their AS. 
The BASMI will be assessed at the visits specified in Table 5-2. 
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9.18 
PhGADA 
The Investigator will assess the overall status of the subject with respect to their AS signs and 
symptoms and functional capacity using an NRS in which 0=very good, asymptomatic and no 
limitations of normal activities and 10=very poor, very severe symptoms which are intolerable 
and inability to carry out normal activities.  
This assessment by the Investigator should be made blind to the PGADA. 
The PhGADA will be assessed at the visits specified in Table 5-2. 
9.19 
Occurrence of extra-articular manifestations 
Information regarding dactylitis, PSO, uveitis, and IBD events during the study will be captured 
as AEs. Enthesitis will be assessed regularly via the MASES performed at site visits as specified 
in Table 5-2.  
9.20 
Imaging evaluation 
Screening imaging evaluations need to be completed during the Screening Period.  
Radiographs and MRIs are read by 2 independent, highly trained expert rheumatology imaging 
specialist physicians. A third person will serve as an adjudicator. 
Details for standardized performance and processing of the x-rays and MRIs will be provided in 
an Imaging Manual.  
The MRIs and x-rays in Section 9.20 will be read centrally by readers who are blinded to 
treatment assignment and chronological order of the imaging according to a charter for 
independent imaging assessment.  
Chest x-rays are discussed in Section 12.7.5.2. 
In addition to the analyses mentioned below, x-rays and MRI images may be evaluated using 
other reading criteria or methods. 
9.20.1 
Sacroiliac joint x-ray (AP Pelvis Joint Film for modified New York 
Criteria) 
The sacroiliac joint is assessed by radiography with an AP pelvis or sacroiliac joint x-ray that 
will be assessed by a central reading review during the Screening Period to evaluate for modified 
New York Criteria status (Table 19‒2) as described in Section 6.1. Sacroiliac joint changes will 
be scored according to the imaging specifications. 
The following will be accepted to qualify subjects with AS for this study: 
• Anterior posterior pelvis x-ray centrally read for one of the Phase 3 studies AS0010 or 
AS0011 and determined to be modified New York Criteria positive (+mNY); neither the 
x-ray nor the reading will be repeated.  
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• Prior sacroiliac joint or AP pelvis x-ray (performed at any time prior to the study) was 
submitted and centrally read for the purposes of this study and determined to be modified 
New York Criteria positive (+mNY). If the prior x-ray does not meet central reading criteria 
for randomization, another x-ray may be performed if the prior x-ray is more than 1 year old 
and if permitted by local guidelines.  
• If no recent x-ray is available, one must be performed at Screening. 
9.20.2 
Spine x-ray 
Subjects with confirmed eligibility based on screening assessments will have a spine x-ray 
performed at Baseline. The x-ray can be performed prior to or after the Baseline Visit, and must 
be performed prior to or no later than on the day of the second administration of IMP. 
If the subject has a spine x-ray available from the past 6 months prior to Screening, this x-ray 
may be used and submitted for central reading. The spine x-ray will be centrally read and will be 
used to assess disease progression in the spine after 1 year in the extension study, given the 
subject is willing to enter this subsequent study. 
9.20.3 
Sacroiliac joint and spine MRI assessment substudy 
While radiography can detect chronic bony changes (eg, sclerosis, erosions, bridging, and 
ankyloses), structural changes generally occur slowly and x-rays are insensitive; therefore, 
changes are difficult to detect in the relatively short duration of a randomized clinical study. 
Unlike radiography, MRI can be used to visualize active inflammation in the sacroiliac joints and 
spine in addition to structural lesions. Inflammation of the sacroiliac joints and spine is a key 
feature of axSpA that is potentially amenable to treatment with bimekizumab. If bimekizumab is 
effective, it is expected that reduction in inflammation in the sacroiliac joints and spine can be 
detected using MRI within the 52-week Treatment Period of this study. Recently, a Danish study 
demonstrated significant changes in ASspiMRI-a (Berlin modification) and 
SPARCC MRI-assessed inflammation scores and in MRI-assessed erosion scores within 
12 weeks after initiation of adalimumab (see below for further description of these MRI scoring 
methods). The researchers concluded that MRI-assessed structural lesions change rapidly and 
may have value for assessing the effects of disease-modifying treatment in clinical trials 
(Pedersen et al, 2016). In this study, MRI changes will be evaluated in the sacroiliac joint and 
spine to evaluate the effect of bimekizumab on objective signs of inflammation through the 
SPARCC and ASspiMRI scores as outlined below. In addition, exploratory evaluation of other 
chronic MRI features, such as erosions and fatty lesions, will be performed as indicators of 
disease modification associated with structural disease progression (Baraliakos et al, 2014). 
Magnetic resonance imaging of the spine and sacroiliac joints will be performed for consenting 
subjects in the MRI substudy after confirmation of eligibility based on screening assessments 
and before the first dose of IMP. If needed, the sacroiliac joint and spine MRIs can be performed 
at Baseline or prior to the actual Baseline Visit after confirmation of eligibility based on 
Screening assessments. 
A central reader will assess the Baseline MRIs to identify MRI-positive subjects as per the 
OMERACT criteria. Further MRIs of the spine and sacroiliac joint for MRI-positive and 
MRI-negative subjects will be performed at Week 16 and Week 52 within a window of ±5 days 
for subjects participating in the MRI substudy. All MRIs will be centrally read. 
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Refusal to participate in the substudy will not affect a subject’s opportunity to participate in the 
main study. 
The following 2 different scoring systems will be utilized to determine changes from Screening 
(Lukas et al, 2007): 
SPARCC Sacroiliac Joint score 
This method is a scoring system for assessing the sacroiliac joint based on short-tau-inversion 
recovery (STIR) sequences. An abnormal increased signal on the STIR sequence represents bone 
marrow edema. The sacroiliac joint is divided into 4 quadrants (upper iliac, lower iliac, upper 
sacral, and lower sacral). The presence of increased signal on STIR in each of these 4 quadrants 
is scored as either 0=normal signal or 1=increased signal. The maximum score for abnormal 
signal in the 2 sacroiliac joints of 1 coronal slice is therefore 8. Joints that include a lesion 
exhibiting intense signal are each given an additional score of 1 per slice (that demonstrate this 
feature). Each sacroiliac joint that includes a lesion demonstrating continuous increase signal of 
depth ≥1cm from the articular surface is also given an additional score of 1. The maximum score 
for a single coronal slice is 12. Scoring is repeated in each of 6 consecutive coronal slices, so that 
the total sacroiliac joint SPARCC MRI score can range from 0 to 72. 
ASspiMRI-a (Berlin modification) score (spine) 
This method is a scoring system with a concentration on STIR sequences which quantifies 
changes in 23 disco-vertebral units (DVU) of the spine. A DVU is defined as the region between 
2 virtual lines through the middle of each vertebra. Active inflammation is scored by grading the 
degree of bone marrow edema from 0 to 3 in 1 dimension on 1 or more consecutive slices that 
represent the highest level of inflammation in a particular DVU. There is no grading for erosion 
in the Berlin modification. The total spine ASspiMRI-a score in the Berlin modification can 
range from 0 to 69.  
Additional scoring systems of inflammation may be used as appropriate methodology becomes 
accepted. 
10 
ASSESSMENT OF PHARMACOKINETIC AND 
PHARMACOGENOMIC VARIABLES 
10.1 
Pharmacokinetic variables 
The PK variable is the plasma concentrations of bimekizumab. The Investigator or designee will 
obtain blood samples for these measurements at the time points specified in Table 5-2. When 
these samples are required at a visit during which the subject is dosed with IMP, the blood 
samples will be drawn prior to dosing. Samples should be drawn at the same time of the 
sampling for clinical laboratory tests. The time and date of collection will be recorded in the 
eCRF. Instructions pertaining to sample collection, processing, storage, labeling, and shipping 
are provided in the laboratory manual for this study. Detailed information on sample analysis 
will be provided in a bioanalytical report. The relationship between PK concentrations and 
efficacy, PD and safety endpoints may also be assessed. The data from this study may be 
combined with data from other studies as part of this assessment. 
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10.2 
Pharmacogenomic variables 
A separate ICF will be required for those subjects who agree to participate in the genomics, 
genetics, and proteomics substudy, and must be signed prior to collection of any samples for the 
substudy. The substudy will only be conducted where ethically accepted and authorized by the 
regulatory agencies. Refusal to participate in the substudy will not affect a subject’s ability to 
participate in the main study. 
These analyses will enable evaluation of biomarkers relative to disease biology and progression, 
drug treatment and bone metabolism, and inflammatory and immune response processes. The 
nature and format of these tentative analyses will be determined at a later date. 
For individuals consenting to the genomics, genetics, and proteomics substudy, blood samples 
will be drawn for exploratory genetic/epigenetic, genomic, proteomic, metabolomics analysis, 
and for candidate biomarker analyses. Candidate biomarker evaluations may include, but are not 
limited to, IL-17A/IL-17F pathway signaling and axSpA biology (eg, IL-17A, IL-17F, IL-23, IL-
6, tumor necrosis factor, dendritic cell-specific transmembrane protein, and circulating osteoclast 
precursors). These plasma samples may be used for additional analyses of other exploratory 
biomarkers. 
Collection of these samples will occur at the time points specified in the schedule of study 
assessments (Table 5-2). At dosing visits, blood samples will be drawn prior to dosing, and will 
be drawn at the same time of the sampling for clinical laboratory tests. The time and date of 
collection will be recorded in the eCRF. The samples will be stored at -80°C at the central 
biorepository for up to 20 years to allow for future exploratory research. 
Stool samples will be collected at time points specified in Table 5-2. These samples may be used 
to assess biomarkers of gut inflammation including but not limited to calprotectin and 
microbiome testing. 
Blood and/or stool samples for pharmacogenomic and biomarker assessments are collected for 
exploratory purposes and participation in either blood or stool sampling (or both) is optional.  
Instructions pertaining to sample collection, processing, storage, labeling, and shipping are 
provided in the laboratory manual for this study. Detailed information on sample analysis will be 
provided in a bioanalytical report. 
11 
ASSESSMENT OF IMMUNOLOGICAL VARIABLES 
Immunological variables are the anti-bimekizumab antibody status, and the treatment-emergent 
antibody positivity derived from anti-drug antibody assays.  
The Investigator or designee will obtain blood samples for these measurements at the time points 
specified in Table 5-2. When these samples are required at a visit during which the subject is 
dosed with IMP, the blood samples will be drawn prior to dosing. Samples should be drawn at 
the same time of the sampling for clinical laboratory tests. The time and date of collection will be 
recorded in the eCRF. Instructions pertaining to sample collection, processing, storage, labeling, 
and shipping are provided in the laboratory manual for this study. The presence of antibodies to 
bimekizumab will be determined using a validated bioanalytical method. Detailed information on 
sample analysis will be provided in a bioanalytical report. 
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The presence of anti-bimekizumab antibodies will be determined using a tiered approach of 
screening, confirmatory, and titer assays. Where applicable, a neutralizing-antibody assay will be 
performed. 
12 
ASSESSMENT OF SAFETY 
12.1 
Adverse events 
12.1.1 
Definitions 
12.1.1.1 
Adverse event 
An AE is any untoward medical occurrence in a patient or clinical investigation subject 
administered a pharmaceutical product that does not necessarily have a causal relationship with 
this treatment. An AE can therefore be any unfavorable and unintended sign (including an 
abnormal laboratory finding), symptom, or disease temporally associated with the use of a 
medicinal (investigational) product, whether or not related to the medicinal (investigational) 
product. 
In order to ensure complete safety data collection, all AEs occurring during the study (ie, after 
the signing of the ICF), including any pretreatment and post-treatment periods required by the 
protocol, must be reported in the eCRF even if no IMP was taken but specific study procedures 
were conducted. This includes all AEs not present prior to the initial visit and all AEs that 
recurred or worsened after the initial visit. 
Signs or symptoms of the condition/disease for which the IMP is being studied should be 
recorded as AEs only if their nature changes considerably or their frequency or intensity 
increases in a clinically significant manner as compared to the clinical profile known to the 
Investigator from the subject’s history or the Baseline Period.  
12.1.1.2 
Serious adverse event 
Once it is determined that a subject experienced an AE, the seriousness of the AE must be 
determined. An SAE must meet 1 or more of the following criteria: 
• Death 
• Life-threatening 
(Life-threatening does not include a reaction that might have caused death had it occurred in 
a more severe form.) 
• Significant or persistent disability/incapacity 
• Congenital anomaly/birth defect (including that occurring in a fetus) 
• Important medical event that, based upon appropriate medical judgment, may jeopardize the 
patient or subject and may require medical or surgical intervention to prevent 1 of the other 
outcomes listed in the definition of serious 
(Important medical events may include, but are not limited to, potential Hy’s Law [see 
Section 12.1.1.3], allergic bronchospasm requiring intensive treatment in an emergency room 
or at home, blood dyscrasias that do not result in inpatient hospitalization, or the 
development of drug dependency or drug abuse.) 
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• Initial inpatient hospitalization or prolongation of hospitalization 
(A patient admitted to a hospital, even if he/she is released on the same day, meets the 
criteria for the initial inpatient hospitalization. An emergency room visit that results in 
admission to the hospital would also qualify for the initial inpatient hospitalization criteria. 
However, emergency room visits that do not result in admission to the hospital would not 
qualify for this criteria and, instead, should be evaluated for 1 of the other criteria in the 
definition of serious [eg, life-threatening adverse experience, important medical event]. 
Hospitalizations for reasons not associated with the occurrence of an AE [eg, preplanned 
surgery or elective surgery for a pre-existing condition that has not worsened or manifested 
in an unusual or uncharacteristic manner] do not qualify for reporting. For example, if a 
subject has a condition recorded on his/her medical history and later has a preplanned surgery 
for this condition, it is not appropriate to record the surgery or hospitalization as an SAE, 
since there is no AE upon which to assess the serious criteria. Please note that, if the 
pre-existing condition has worsened or manifested in an unusual or uncharacteristic manner, 
this would then qualify as an AE and, if necessary, the seriousness of the event would need to 
be determined.) 
12.1.1.2.1 
Anticipated serious adverse events 
The following Anticipated SAEs are anticipated to occur in the population studied in this 
protocol at some frequency that is independent of drug exposure.  
This list does not change the Investigator’s obligation to report all SAEs (including Anticipated 
SAEs) as detailed in Section 12.1.2.3. 
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Table 12‒1: Anticipated serious adverse events for the population of subjects 
with AS 
MedDRA system organ class  
MedDRA preferred term 
Skin and subcutaneous tissue disorders 
Psoriasis 
Eye disorders  
Uveitis 
Musculoskeletal and connective tissue disorders  
Dactylitis 
Tendonitis 
Atlantoaxial instability 
Gastrointestinal disorders  
Colitis ulcerative  
Crohn's disease 
Cardiac disorders  
Aortic valve incompetence 
Atrial tachycardia 
Atrioventricular block 
Bundle branch block 
Cardiomyopathy 
Vascular disorders 
Aortitis 
Respiratory, thoracic and mediastinal disorders  
Pulmonary fibrosis 
Nervous system disorders 
Cauda equina syndrome 
Injury, poisoning and procedural complications  
Spinal cord injury 
Spinal fracture 
Cervical vertebral fracture 
Lumbar vertebral fracture 
Thoracic vertebral fracture 
Immune system disorders  
Amyloidosis 
Psychiatric disorders  
Depression 
AS=ankylosing spondylitis; MedDRA=Medical Dictionary for Regulatory Activities; SAE=serious adverse event 
Note: Exception: Listed events will not be regarded as anticipated SAEs if they are life threatening or if they 
result in the death of the study subject. 
12.1.1.3 
Adverse events of special interest 
An AE of special interest (AESI) is any AE that a regulatory authority has mandated to be 
reported on an expedited basis, regardless of the seriousness, expectedness, or relatedness of the 
AE to the administration of a UCB product/compound. 
Potential Hy’s Law, defined as ≥3xULN ALT or AST with coexisting ≥2xULN total bilirubin in 
the absence of ≥2xULN ALP, with no alternative explanation for the biochemical abnormality, 
must ALWAYS be reported to UCB as an AESI (ie, without waiting for any additional etiologic 
investigations to have been concluded). Follow-up information should then be reported if an 
alternative etiology is identified during investigation and monitoring of the subject. 
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12.1.1.4 
Other safety topics of interest 
Pre-specified safety topics of interest for the study are: infections (serious, opportunistic, fungal, 
and TB), neutropenia, hypersensitivity, suicidal ideation and behavior, major cardiovascular 
events, liver function test changes/enzyme elevations, malignancies, and inflammatory bowel 
diseases (with gastroenterology referral, as appropriate).  
This is based on findings from the IMP clinical program to date, potential risks generally 
associated with biologic immunomodulators, or findings from other medicines with a related 
mechanism of action. There are no specific AE reporting requirements for these topics, however 
special monitoring, additional data collection activities, and/or enhanced signal detection 
activities (within UCB) are in place. 
12.1.2 
Procedures for reporting and recording adverse events 
The subject will be given the opportunity to report AEs spontaneously. A general prompt will 
also be given at each study visit to detect AEs. For example: 
“Did you notice anything unusual about your health (since your last visit)?” 
In addition, the Investigator should review any self-assessment procedures (eg, diary cards) 
employed in the study. 
12.1.2.1 
Description of adverse events 
When recording an AE, the Investigator should use the overall diagnosis or syndrome using 
standard medical terminology, rather than recording individual symptoms or signs. The eCRF 
and source documents should be consistent. Any discrepancies between the subject’s own words 
on his/her own records (eg, diary card) and the corresponding medical terminology should be 
clarified in the source documentation. 
Details for completion of the Adverse Event eCRF (including judgment of relationship to IMP) 
are described in the eCRF Completion Guidelines. 
12.1.2.2 
Rule for repetition of an adverse event 
An increase in the intensity of an AE should lead to the repetition of the AE being reported with: 
• The outcome date of the first AE that is not related to the natural course of the disease being 
the same as the start date of the repeated AE, and the outcome of “worsening” 
• The AE verbatim term being the same for the first and repeated AE, so that the repeated AE 
can be easily identified as the worsening of the first one 
12.1.2.3 
Additional procedures for reporting serious adverse events 
If an SAE is reported, UCB must be informed within 24 hours of receipt of this information by 
the site. The Investigator must enter the information regarding the SAE into the appropriate 
eCRFs and transmit to UCB via the clinical database, even if the data are incomplete, or if it is 
obvious that more data will be needed in order to draw any conclusions. This information will be 
received by UCB and entered into the global safety database. Any ancillary documentation (eg, 
autopsy or other documentation) that is valid for the SAE can be sent to UCB using the contact 
information (fax/email) for SAE reporting listed in the Serious Adverse Event Reporting section 
at the front of the protocol. 
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It is important for the Investigator, when entering the SAE data into the eCRF, to include the 
assessment as to a causal relationship between the SAE and the IMP administration. This insight 
from the Investigator is very important for UCB to consider in assessing the safety of the IMP 
and in determining whether the SAE requires reporting to the regulatory authorities in an 
expedited manner. 
Additional information received by the Investigator must be provided within 24 hours. All 
documents in the local language must be accompanied by a translation in English, or the relevant 
information included in the same document must be summarized in the eCRF and transmitted to 
UCB via the clinical database. 
The Investigator is specifically requested to collect and report to UCB (or its representative) any 
SAEs (even if the Investigator is certain that they are in no way associated with the IMP), up to 
30 days from the end of the study for each subject, and to also inform participating subjects of 
the need to inform the Investigator of any SAE within this period. Serious AEs that the 
Investigator thinks may be associated with the IMP must be reported to UCB regardless of the 
time between the event and the end of the study. 
Upon receipt of the electronic transmission of the SAE, UCB will perform an assessment of 
expectedness of the reported SAE. The assessment of the expectedness of the SAE is based on 
the Investigator’s Brochure. 
12.1.3 
Follow up of adverse events 
An AE should be followed until it has resolved, has stable sequelae, the Investigator determines 
that it is no longer clinically significant, or the subject is lost to follow up. This follow-up 
requirement applies to AEs, SAEs, and AEs of special interest; further details regarding follow 
up of PDILI events is provided in Section 12.6.1.4.  
If an AE is ongoing at the end of the study for a subject, follow-up should be provided until 
resolution/stable level of sequelae is achieved, or until the Investigator no longer deems that it is 
clinically significant, or until the subject is lost to follow up. If no follow up is provided, the 
Investigator must provide a justification. The follow up will usually be continued for 20 weeks 
after the subject has discontinued his/her IMP. 
Information on SAEs obtained after clinical database lock will be captured through the Patient 
Safety (PS) database without limitation of time. 
12.2 
Pregnancy 
If an Investigator is notified that a subject has become pregnant after the first intake of any IMP, 
the Investigator must immediately (within 24 hours) notify UCB’s PS department by entering all 
pregnancy information into the eCRF. An automatic notification will be sent to UCB’s PS 
department. The subject should be permanently withdrawn from IMP as soon as pregnancy is 
known (by positive pregnancy test), and the following should be completed: 
• The subject should immediately stop the intake of the IMP.  
• The subject should return for an early ad-hoc study visit. 
• A Safety Follow-Up Visit should be scheduled 20 weeks after the final dose of IMP. 
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The Investigator should discuss with the subject the possibility to continue the study by attending 
the scheduled visits for assessments without IMP administration. The tests or assessments, which 
are considered contraindicated during the pregnancy should not be performed. The early ad-hoc 
study visit will be considered as the ET Visit if the subject does not wish to pursue the study 
investigations. 
The Investigator must inform the subject of information currently known about potential risks 
and about available treatment alternatives. 
The pregnancy will be documented in the eCRF. The progression of the pregnancy and the 
eventual birth (if applicable) must be followed up using the eCRF. The Investigator must inform 
the subject of information currently known about potential risks and about available treatment 
alternatives. 
The pregnancy will be documented on the Pregnancy Report and Outcome Form provided to the 
Investigator. The progression of the pregnancy and the eventual birth (if applicable) must be 
followed up using the Pregnancy Report and Outcome Form in which the Investigator has to 
report on the health of the mother and of the child. Every reasonable attempt should be made to 
follow the health of the child for 30 days after birth for any significant medical issues. In certain 
circumstances, UCB may request that follow up is continued for a period longer than 30 days. If 
the subject is lost to follow up and/or refuses to give information, written documentation of 
attempts to contact the subject needs to be provided by the Investigator and filed at the site. 
UCB’s PS department is the primary contact for any questions related to the data collection for 
the pregnancy, eventual birth, and follow up. 
In cases where the partner of a male subject enrolled in a clinical study becomes pregnant, the 
Investigator or designee is asked to contact the subject to request consent of the partner via the 
Partner Pregnancy Consent Form that has been approved by the responsible IRB/IEC and should 
be available in the Investigator site file. In case of questions about the consent process, the 
Investigator may contact the UCB/contract research organization (CRO) contract monitor for the 
study. The Investigator will complete the information in the eCRF only after the partner has 
agreed that additional information can be captured and has provided the signed Partner 
Pregnancy Consent Form. UCB’s PS department is also the primary contact for any questions 
related to the data collection for the partner pregnancy, eventual birth, and follow up. 
A pregnancy becomes an SAE in the following circumstances: miscarriage, elective abortion, 
medically indicated abortion (eg, when the pregnancy is endangering life or health of the woman, 
or when the fetus will be born with severe abnormalities), unintended pregnancy after hormonal 
contraceptive failure (if the hormonal contraceptive was correctly used), ectopic pregnancy, fetal 
demise, or any congenital anomaly/birth defect of the baby. Those SAEs must be additionally 
reported using the eCRF.  
12.3 
Suspected transmission of an infectious agent 
For the purposes of reporting, any suspected transmission of an infectious agent via a medicinal 
product should be considered as an SAE; such cases must be reported immediately, recorded in 
the AE module of the eCRF, and followed as any other SAE. Any organism, virus, or infectious 
particle (eg, prion protein transmitting transmissible spongiform encephalopathy), pathogenic or 
nonpathogenic, is considered an infectious agent. 
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12.4 
Overdose of investigational medicinal product 
Excessive dosing (beyond that prescribed in the protocol and including overdose) should be 
recorded in the eCRF. Any SAE or nonserious AE associated with excessive dosing must be 
followed as any other SAE or nonserious AE. 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). 
12.5 
Safety signal detection 
Selected data from this study will be reviewed periodically to detect as early as possible any 
safety concern(s) related to the IMP so that Investigators, clinical study subjects, regulatory 
authorities, and IRBs/IECs will be informed appropriately and as early as possible. 
The Study Physician or medically qualified designee/equivalent will conduct an ongoing review 
of SAEs and perform ongoing SAE reconciliations in collaboration with the PS representative. 
As appropriate for the stage of development and accumulated experience with the IMP, 
medically qualified personnel at UCB may identify additional safety measures (eg, AEs, vital 
signs, laboratory or ECG results) for which data will be periodically reviewed during the course 
of the study. 
In addition, an independent Data Monitoring Committee (DMC) will periodically review and 
monitor safety data from this study and advise UCB. Details are provided in the DMC Charter. 
Cardiovascular and Neuropsychiatric Adjudication Committees will also periodically review and 
monitor safety data from this study and advise UCB. Details are provided in the Adjudication 
Committee Charters. 
12.6 
Laboratory measurements 
Clinical laboratory assessments consist of biochemistry, hematology, urinalysis, and pregnancy 
tests (serum or urine) (Table 12‒2). A centralized laboratory will be used to supply all laboratory 
test supplies and analyze all blood and urine samples (except the urine pregnancy test). Any 
unscheduled laboratory testing should also be collected using the central laboratory (with the 
exception of urgent safety laboratory measurements which should be performed locally and 
centrally simultaneously). Testing to exclude hepatitis B, hepatitis C, and HIV (see Exclusion 
Criterion #12, Section 6.2) will be performed at Screening in addition to those measurements 
listed in Table 12‒2. A urine dipstick will be used for pregnancy testing. 
Rescreening and retesting rules are provided in Section 5.1.1.1 and Section 5.1.1.2. 
Specific details regarding the handling and processing of biochemistry and hematology samples 
are provided in the study laboratory manuals. 
For subjects consenting to the pharmacogenomic substudy, blood and/or stool samples will be 
collected at defined timepoints (Table 5-2) and shipped and stored according to the laboratory 
manual. 
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The following laboratory parameters will be measured: 
Table 12‒2: Laboratory measurements 
Hematology 
Biochemistry 
Urinalysis 
Basophils 
Calcium 
pH 
Eosinophils 
Chloride 
Albumin (protein) 
Lymphocytes 
Magnesium 
Glucose 
Monocytes 
Potassium 
Blood 
Neutrophils 
Sodium 
Leukocyte esterase 
Hematocrit 
Glucose 
Nitrite 
Hemoglobin 
BUN 
Urine dipstick for pregnancy 
testinga 
MCH 
Creatinine 
Urine drug screenc 
MCHC 
AST 
 
MCV 
ALT 
 
Platelet count 
ALP 
 
RBC count  
GGT 
 
WBC count  
Total bilirubin 
 
 
LDH 
 
 
Total cholesterol 
 
 
Serum pregnancy testinga 
 
 
CRPb 
 
ALP=alkaline phosphatase; ALT=alanine aminotransferase; AST=aspartate aminotransferase; BUN=blood urea 
nitrogen; CRP=C-reactive protein; ET=Early Termination; GGT=gamma-glutamyltransferase; 
IMP=investigational medicinal product; LDH=lactate dehydrogenase; MCH=mean corpuscular hemoglobin; 
MCHC=mean corpuscular hemoglobin concentration; MCV=mean corpuscular volume; RBC=red blood cell; 
SFU=Safety Follow-Up; WBC=white blood cell 
a A serum pregnancy test will be performed at Screening for all women of childbearing potential. A urine 
pregnancy test (urine dipstick analyzed locally) is also required at the Baseline Visit, Q4W from Week 4 to 
Week 52, ET, and at SFU visits. Pregnancy test results must be negative prior to administering IMP. 
b CRP will be tested at specified visits (Table 5-2). 
c Urine drug screen will be performed at the Screening Visit. 
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12.6.1 
Evaluation of PDILI 
The PDILI IMP discontinuation criteria for this study are provided in Section 6.3.1, with the 
accompanying required follow-up investigation and monitoring detailed below. All PDILI events 
must be reported as an AE and PDILI events meeting SAE criteria should be reported to the 
Sponsor within 24 hours of learning of their occurrence. Any PDILI event that meets the 
criterion for potential Hy’s Law must be reported within 24 hours of learning of their occurrence 
as an AE of special interest (see Section 12.1.1.3), and, if applicable, also reported as an SAE 
(see Section 12.1.1.2).  
Evaluation of PDILI consists of the diagnostic testing and continued monitoring included in 
Table 12‒3) specific tests dependent on laboratory results and corresponding symptoms) and 
consultation with a local hepatologist (if applicable; discussed in Section 12.6.1.1). The local 
hepatologist is the expert usually consulted by the treating physician for assessment and 
management of potential hepatic disease. This would usually be a hepatologist, but may be a 
gastroenterologist. Additional investigation and monitoring may be required and adapted based 
on the diagnosis after the cause of the liver injury/abnormality is confirmed (details in 
Section 12.6.1.4).  
The results of all monitoring, including laboratory testing and other testing, should be made 
available to the study site and Sponsor. 
All initial tests resulting in abnormal hepatic laboratory values need to be repeated, but 
appropriate medical action must not be delayed waiting for the repeat result. 
If tests are done locally for more rapid results, a concurrent sample should also be sent to the 
central laboratory whenever possible. Medical care decisions are to be made initially using the 
most rapidly available results and a conservative approach must be taken if the results from the 
2 laboratory tests are significantly different. Data from the local and central laboratory are to be 
recorded on the applicable eCRF pages. 
When IMP is discontinued, all concomitant medications and herbal supplements that are not 
medically necessary should also be discontinued. In these cases, the Investigator should also 
consider dose reduction for medically necessary concomitant medication and consider changing 
any medically required concomitant medication known to be hepatotoxic to a suitable 
alternative. 
When IMP is stopped due to PDILI (as described in Section 6.3.1), IMP must be discontinued 
unless a subsequent alternative diagnosis fully explains the hepatic findings. If a subsequent 
alternative diagnosis fully explains the hepatic findings, and the requirements provided in 
Section 12.6.1.2.1 are met, rechallenge with IMP may be appropriate. 
The approach to investigate PDILI is summarized in Table 12‒3. 
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Table 12‒3: Required investigations and follow-up for PDILI 
Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis or 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
≥3xULN 
≥2xULN
b 
NA 
Hepatology consultc 
Medical Monitor must 
be notified within 
24 hours (eg, by 
laboratory alert) and 
subject discussed with 
Medical Monitor ASAP. 
Immediate IMP 
discontinuationd. 
 
Essential: Must have 
repeat liver 
chemistry values and 
additional testing 
completed ASAP 
(see 
Section 12.6.1.3); 
recommended to 
occur at the site with 
HCP. 
Monitoring of liver chemistry 
values at least twice per week 
until values normalize, stabilize, 
or return to within baseline 
values.e 
≥3xULN 
NA 
Yes 
≥8xULN 
NA 
NA 
 
 
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Table 12‒3: Required investigations and follow-up for PDILI 
Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis or 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
≥5xULN 
(and ≥2x 
baseline) 
and 
<8xULN  
<2xULN 
No 
Discussion with Medical 
Monitor required. 
Consider need for 
hepatology consult if 
there is no evidence of 
resolution (see Follow 
up requirements).c 
Further investigation 
– immediate IMP 
discontinuation not 
required (see 
Section 12.6.1.2). 
 
IMP discontinuation 
required if any of the 
following occur: 
• 
Subject cannot 
comply with 
monitoring 
schedule. 
• 
Liver chemistry 
values continue 
to increase 
• 
Liver chemistry 
values remain 
≥5xULN (and 
≥2x baseline) 
after 4 weeks of 
monitoring 
without 
evidence of 
resolution 
Essential: Every 
attempt must be 
made to have repeat 
liver chemistry 
values and 
additional testing 
completed within 
48 hours at the site 
with HCP (see 
Section 12.6.1.3). 
Monitoring of liver chemistry 
values at least twice per week for 
2 weeks.e 
• 
Immediate IMP 
discontinuation required if 
liver chemistry values 
continue to increase. 
After 2 weeks of monitoring 
liver chemistry values: 
• 
ALT or AST remains 
≥5xULN <8xULN, IMP 
should be temporarily 
withheld and subject should 
undergo repeat test in 2 
weeks. 
Continue IMP if ALT or 
AST values <5xULN; 
continue to monitor at least 
twice per week until values 
normalize, stabilize, or 
return to within baseline 
values. 
If ALT or AST remains 
≥5xULN after second re-
test, immediate IMP 
discontinuation required. 
Continue to monitor until values 
normalize, stabilize, or return to 
within baseline values.e 
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Table 12‒3: Required investigations and follow-up for PDILI 
Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis or 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
ALP=alkaline phosphatase; ALT=alanine aminotransferase; ASAP=as soon as possible; AST=aspartate aminotransferase; HCP=healthcare practitioner; 
IMP=investigational medicinal product; NA=not applicable; PDILI=potential drug induced liver injury; ULN=upper limit of normal 
a Hepatitis symptoms include fatigue, nausea, vomiting, and right upper quadrant pain or tenderness; hypersensitivity symptoms include eosinophilia 
(>5%), rash, and fever (without clear alternative cause). 
b If the subject also has ≥2xULN ALP, the possibility of an indication of biliary obstruction should be discussed with the Medical Monitor. 
c Details provided in Section 12.6.1.1. The local hepatologist is the expert usually consulted by the treating physician for assessment and management of 
potential hepatic disease. This would usually be a hepatologist, but may be a gastroenterologist. 
d Details are provided in Section 12.6.1.2. 
e Unless an alternative monitoring schedule is agreed by the Investigator and UCB responsible physician. Determination of stabilization is at the discretion 
of the Investigator in consultation with the hepatologist (as applicable) and UCB responsible physician, as needed. 
 
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12.6.1.1 
Consultation with Medical Monitor and local hepatologist  
Potential drug-induced liver injury events require notification of the Medical Monitor within 
24 hours (eg, by laboratory alert), and the subject must be discussed with the Medical Monitor as 
soon as possible. If required, the subject must also be discussed with the local hepatologist. The 
local hepatologist is the expert usually consulted by the treating physician for assessment and 
management of potential hepatic disease. This would usually be a hepatologist, but may be a 
gastroenterologist. If determined necessary, this discussion should be followed by a full 
hepatology assessment (see Section 12.6.1.3) and SAE report (if applicable). 
12.6.1.2 
Immediate action: determination of IMP discontinuation 
All PDILI events require immediate action, testing, and monitoring.  
The immediate action is dependent on the laboratory values and symptoms of hepatitis or 
hypersensitivity and ranges from continuation of IMP (followed by immediate investigation) to 
immediate discontinuation (see Section 6.3.1 and Table 12‒3 for details). 
When IMP is discontinued, all concomitant medications and herbal supplements that are not 
medically necessary should also be discontinued. The Investigator should also consider dose 
reduction for medically necessary concomitant medication and consider changing any medically 
required concomitant medication known to be hepatotoxic to a suitable alternative. 
12.6.1.2.1 
IMP restart/rechallenge  
Subjects who are immediately discontinued from IMP due to having met certain criteria for 
PDILI (as described in Section 6.3.1 and Table 12‒3), but for whom an alternative diagnosis is 
confirmed, ie, drug-induced liver injury is excluded, can rarely restart IMP. Rechallenge with 
IMP can occur only if ALL of the following requirements are met at the time of the rechallenge: 
• The results of additional testing and monitoring described in Section 12.6.1.3 and 
Section 12.6.1.4 confirm a nondrug-related cause for the abnormal hepatic laboratory 
parameters and any associated symptoms (ie, a subsequent alternative diagnosis fully 
explains the hepatic findings).  
• No alternative treatment options are available to the subject. 
• The subject has shown clear therapeutic benefit from the IMP. 
• Subject’s ALT or AST elevations do not exceed ≥3xULN. 
• Subject’s total bilirubin is <1.5xULN. 
• Subject has no signs or symptoms of hypersensitivity.  
• The rechallenge is approved by the UCB responsible physician and a hepatologist. The 
hepatologist must be external to UCB. It is recommended that the hepatologist be a local 
hepatology expert or the hepatologist treating the subject. 
• Subject agrees to the investigator-recommended monitoring plan and understands their 
individual benefit risk for restarting IMP and this is adequately documented.  
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12.6.1.3 
Testing: identification/exclusion of alternative etiology 
The measurements and additional information required for the assessment of PDILI events when 
there is a reasonable possibility that they may have been caused by the IMP are detailed in 
Table 12‒4 (laboratory measurements) and Table 12‒5 (additional information). Results of the 
laboratory measurements and information collected are to be submitted to the Sponsor on the 
corresponding eCRF. If the medical history of the subject indicates a requirement for other 
assessments not included below, these additional assessments should be completed and 
submitted, as applicable. 
All blood samples should be stored, if possible. If tests are done locally for more rapid results, a 
concurrent sample must also be sent to the central laboratory. 
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The following measurements are to be assessed: 
Table 12‒4: PDILI laboratory measurements 
Virology-
related 
Hepatitis A IgM antibody 
HBsAg 
Hepatitis E IgM antibody 
HBcAb-IgM 
Hepatitis C RNA 
Cytomegalovirus IgM antibody 
Epstein-Barr viral capsid antigen IgM antibody (if unavailable, obtain heterophile 
antibody or monospot testing) 
Immunology 
Anti-nuclear antibody (qualitative and quantitative) 
Anti-smooth muscle antibody (qualitative and quantitative) 
Type 1 anti-liver kidney microsomal antibodies (qualitative and quantitative) 
Hematology 
Eosinophil count 
Urinalysis 
Urine drug screena 
Chemistry 
Amylase 
 
Sodium, potassium, chloride, glucose, BUN, creatinine 
 
Total bilirubin, ALP, AST, ALT, GGT, total cholesterol, albumin 
If total bilirubin ≥1.5xULN, obtain fractionated bilirubin to obtain % direct bilirubin 
Serum CPK and LDH to evaluate possible muscle injury causing transaminase elevation  
Additional 
Prothrombin time/INRb 
Serum pregnancy testc 
PK sample 
ALP=alkaline phosphatase; ALT=alanine aminotransferase; AST=aspartate aminotransferase; BUN=blood urea 
nitrogen; CPK=creatine phosphokinase; GGT=gamma-glutamyltransferase; HBcAb-IgM=hepatitis B core 
antibody-IgM; HBsAg=hepatitis B surface antigen; IgM=immunoglobulin M; INR=international normalized ratio; 
LDH=lactate dehydrogenase; PDILI=potential drug-induced liver injury; PK=pharmacokinetic; RNA=ribonucleic 
acid; ULN=upper limit of normal 
a Tests in addition to the specified analytes may be performed based on the Investigator’s medical judgment and 
subject history. 
b Measured only for subjects with ALT >8xULN, elevations in total bilirubin, and symptoms of hepatitis or 
hypersensitivity. Hepatitis symptoms include fatigue, nausea, vomiting, and right upper quadrant pain or 
tenderness; hypersensitivity symptoms include eosinophilia (>5%), rash, and fever (without clear alternative 
cause). 
c For women of childbearing potential. 
Additional information to be collected is presented in Table 12‒5. 
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Table 12‒5: PDILI information to be collected 
New or updated information 
Concomitant prescription and over-the-counter medications (eg, acetaminophen, herbal remedies, 
vitamins); dosages and dates should be included. 
Pertinent medical history, including the following: 
• 
History of liver disease (eg, autoimmune hepatitis, nonalcoholic steatohepatitis or other “fatty 
liver disease”) 
• 
Adverse reactions to drugs 
• 
Allergies 
• 
Relevant family history or inheritable disorders (eg, Gilbert’s syndrome, alpha-1 antitrypsin 
deficiency) 
• 
Recent travel  
• 
Progression of malignancy involving the liver (Note: Metastatic disease to the liver, by itself, 
should not be used as an explanation for significant AST and/or ALT elevations.) 
The appearance or worsening of clinical symptoms of hepatitis or hypersensitivity (eg, fatigue, nausea, 
vomiting, right upper quadrant pain or tenderness, decreased appetite, abdominal pain, jaundice, fever, or 
rash) 
Recent clinically significant hypotension or hypoxemia with compromised cardiopulmonary function 
Alcohol and illicit drug use 
Results of liver imaging or liver biopsy, if done 
Results of any specialist or hepatology consult, if done 
Any postmortem/pathology reports 
ALT=alanine aminotransferase; AST=aspartate aminotransferase; PDILI=potential drug-induced liver injury 
12.6.1.4 
Follow-up evaluation 
Potential drug-induced liver injury events require follow-up monitoring as described in 
Table 12‒3. Monitoring should continue until liver chemistry values normalize, stabilize, or 
return to Baseline. Determination of stabilization is at the discretion of the Investigator in 
consultation with the hepatologist (as applicable) and UCB responsible physician, as needed. 
12.7 
Other safety measurements 
12.7.1 
Vital signs 
The Investigator or designee should measure all vital signs (systolic and diastolic BP, 
temperature [oral, axillary, or otic], pulse rate) prior to dosing after the subject has been sitting 
for at least 5 minutes, and the subject should remain seated during the measurements. At 
Baseline/Day 1 and Week 16, collect vital signs prior to drug administration and then at 
approximately 30 minutes and 1 hour after dosing.  
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12.7.2 
Body weight and height 
Height is collected at Screening only. The Investigator or designee will measure the height of the 
subject with shoes removed in meters and the weight of the subject in kilograms at the time 
points listed in Table 5-2. The same scale should be utilized throughout the study where possible. 
12.7.3 
Physical examination 
The physical examination should be conducted by the Investigator or designee at the time points 
listed in Table 5-2 and will include general appearance; ear, nose, and throat; eyes, hair, and 
skin; respiratory; cardiovascular; GI; musculoskeletal; hepatic; neurological (including limb 
reflexes); and mental status. Findings considered clinically significant changes since the physical 
examination at the Screening Visit will be recorded as AEs. 
12.7.4 
12-lead electrocardiogram 
The Investigator or designee will perform the ECG which will be read centrally at the time points 
listed in Table 5-2. Full details of ECG recording will be provided in the ECG Manual. 
12.7.5 
Assessment and management of TB and TB risk factors 
All subjects will be assessed for TB at Screening and at the time points specified in the schedule 
of assessments (Table 5-2) through physical examination for signs and symptoms of TB, chest 
x-ray (Section 12.7.5.2), laboratory testing (Section 12.7.5.1), and TB questionnaire 
(Section 12.7.5.3). 
At Screening, all subjects will have an IGRA test (QuantiFERON TB test is recommended), a 
chest x-ray (unless already performed within 3 months of Screening) and examination for signs 
and symptoms of TB. In addition, each subject will complete a TB questionnaire directed at 
potential exposure to TB and symptoms of TB.  
For the purposes of this study, TB definitions are as follows: 
a. Known TB infection: 
− Active TB infection or clinical signs and symptoms suspicious for TB (pulmonary or 
extra-pulmonary). 
− History of active TB infection involving any organ system or findings in other organ 
systems consistent with TB infection, unless adequately treated and proven to be fully 
recovered upon consult with a TB specialist. 
− Any evidence by radiography or other imaging modalities consistent with previously 
active TB infection that is not reported in the subject’s medical history. 
b. High risk of acquiring TB infection: 
− Known close exposure to another person with active TB infection within the 3 months 
prior to Screening. 
− Time spent in a healthcare delivery setting or institution where individuals infected with 
TB are housed and where the risk of transmission of infection is high. 
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c. Latent TB infection (unless appropriate prophylaxis is initiated at least 4 weeks prior to IMP 
dosing and continued to completion of prophylaxis): 
− The absence of signs, symptoms, or physical findings suggestive of TB infection with a 
positive IGRA test (or 2 indeterminate IGRA test results) and a chest x-ray (or other 
imaging) without evidence of TB infection. If the result of the IGRA test is 
indeterminate, the particular IGRA test previously performed may be repeated once; if 
positive or indeterminate on retest, the subject may not be randomized to IMP without 
further evaluation by a TB specialist and discussion with the Study Physician, if LTB 
infection is identified. The retest must be done during the protocol-defined Screening 
window. 
− Note: If available, respiratory or other specimens must also be smear and culture negative 
for TB (CDC diagnosis of LTB infection) http://www.cdc.gov/TB/topic 
/testing/default.htm). 
d. NTMB infection is defined as a clinical infection caused by mycobacterial species other than 
those belonging to the Mycobacterium tuberculosis complex. 
e. Tuberculosis test conversion: 
− A positive IGRA result for the current test when previous IGRA test results were 
negative. All subjects with TB test conversion must immediately stop IMP administration 
and be referred to a TB specialist for further evaluation. Confirmed TB test conversions 
should be classified as due to LTBI, active TB infection, or NTMB, and reported to the 
UCB PS function. 
Subject eligibility, retesting requirements, and treatment requirements are shown in Figure 12‒1. 
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Figure 12‒1: Schematic diagram of TB test results and study eligibility 
 
CDC=Center for Disease Control; IGRA=interferon-gamma release assay; LTBI=latent tuberculosis infection; 
TB=tuberculosis; WHO=World Health Organization 
a IGRA retest must be done during the protocol-defined Screening window. 
b Subject has a past history of active TB involving any organ system unless adequately treated according to 
WHO/CDC therapeutic guidance and proven to be fully recovered upon consult with a TB specialist. Subjects who 
have recently (no more than 12 months prior to Screening) completed the full treatment course of prophylaxis for 
LTBI are allowed. Prophylaxis should be in accordance with WHO or CDC guidelines and TB specialist judgment 
based on the origin of infection.  
c Subjects with LTBI may enter the study only after they have completed at least 4 weeks of appropriate 
prophylactic therapy and thereafter, will continue and complete the entire regimen. 
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Figure 12‒2: Schematic diagram of TB test results during the study 
 
ASAP=as soon as possible; IGRA=interferon-gamma release assay; IMP=investigational medicinal product; 
LTBI=latent tuberculosis infection; TB=tuberculosis 
a IGRA retest must be done ASAP and prior to the next IMP dose 
b Subjects with LTBI may continue the study only after they have completed at least 4 weeks of appropriate 
prophylactic therapy and thereafter, will continue and complete the entire regimen.  
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12.7.5.1 
Tuberculosis assessment by IGRA 
During conduct of the study, the TB assessment by IGRA (QuantiFERON TB test is 
recommended) will be performed as described in Table 5-2 for all subjects. The test results will 
be reported as positive, negative, or indeterminate. Positive and indeterminate TB test results that 
occur during the course of the study must be reported as an AE and appropriately updated once 
the final diagnosis is known (eg, active TB, latent TB, or false positive TB test). UCB also 
recommends that a TB specialist be consulted where TB (latent or active) is suspected or if there 
are doubts regarding test results. If latent or active TB is identified, subject must undergo 
appropriate study-specified withdrawal procedures. For indeterminate test results, the retest 
during Screening must be done during the protocol-defined Screening window. 
12.7.5.2 
Chest x-ray for tuberculosis 
A plain posteroanterior chest x-ray must be performed in the Screening Period unless one has 
been performed within 3 months prior to the Screening Visit. The chest x-ray (or, if done, 
Computed Axial Tomography [CAT] of the chest) must be clear of signs of TB infection 
(previous or current) before first IMP administration. All chest imaging (particularly x-rays) 
should be available for review by the Investigator before randomization of the subject. The chest 
x-ray reading should be repeated if the TB test was confirmed positive. If the second read of the 
pretreatment chest x-ray is confirmed to be clear, the subject may be included in the study 
4 weeks after the start of the TB prophylactic treatment. If the pretreatment chest x-ray is not 
available for a re-read, it should be repeated after notification to the radiologist that this subject 
is IGRA positive, and confirmed to be clear for signs of TB. 
The chest imaging must be negative for any old or recent TB infection as determined by a 
qualified radiologist and/or pulmonary physician. Any new clinically significant findings post 
Baseline on chest x-ray must be documented in the source documents and the eCRF as an AE. 
12.7.5.3 
Tuberculosis questionnaire 
The questionnaire “Evaluation of signs and symptoms of tuberculosis” should be used as a 
source document. The questionnaire will be completed as described in Table 5-2. The 
questionnaire will assist with the identification of subjects who may require therapy for TB. A 
subject who answers “Yes” to the question 
 
 Screening 
is excluded. A “Yes” response to any of the other questions within the questionnaire at Screening 
should trigger further careful assessment to determine if subject has LTB or active TB (see 
Exclusion Criterion #14 in Section 6.2). A “Yes” response to any of the questions during the 
study should trigger further assessments to determine if the subject has either LTB or active TB 
infection.  
12.7.5.4 
Tuberculosis management 
During the study, subjects who develop evidence of LTB infection or active TB must 
immediately stop further administration of IMP and will be referred to an appropriate TB 
specialist (pulmonologist or infectious disease specialist) for further evaluation. Evidence of 
LTB infection is defined as subject’s IGRA test converts to positive or indeterminate (and 
confirmed indeterminate on repeat), or the subject’s questionnaire or history and physical 
indicates that TB infection or exposure may have occurred. Evidence of active TB includes, in 
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addition to the aforementioned tests, signs and symptoms of organ involvement. In either 
situation, the subject should be carefully assessed by a TB specialist for active TB. Subjects 
diagnosed with active TB should be withdrawn from the study and receive appropriate TB or 
prophylaxis therapy.  
If a TB specialist excludes an active TB infection the subject can proceed with the IMP no earlier 
than 4 weeks after the start of an appropriate prophylactic therapy. 
Any presumptive diagnosis or diagnosis of a TB infection is a reportable event. Confirmed active 
TB must be reported as an SAE. The Investigator is to complete and submit the TB follow-up 
Form provided. 
The subject should be transferred to the care of his/her physician and managed according to the 
best available standard of care. Subjects identified as having converted to active TB during the 
study must be withdrawn and scheduled to return for the ET Visit as soon as possible but no later 
than the next scheduled study visit and complete all ET Visit assessments.  
The subject should be encouraged to complete a SFU Visit (20 weeks after the final dose of 
IMP). 
If infection with NTMB is identified during the study, the same procedure as for active TB 
acquired during the study must be followed. 
12.7.6 
Pregnancy testing 
Pregnancy testing will consist of serum testing at Screening for all women of childbearing 
potential. A urine dipstick will be used for pregnancy testing at all other visits. 
The Screening Visit serum pregnancy test results must be negative, and received and reviewed 
prior to randomization. A negative urine pregnancy test result should be obtained immediately 
prior to each administration of IMP and at all visits specified in Table 5-2. Pregnancy tests 
should be administered to all female subjects of childbearing potential, regardless of their use of 
birth control. 
12.7.7 
PHQ-9 
The PHQ-9 is a multipurpose instrument for screening, diagnosing, monitoring, and measuring 
the severity of depression. The PHQ-9 scores for depression range from 0 to 27 with higher 
scores indicating worse state. A score of 5 to 9 is considered to be minimal symptoms of 
depression. A score of 10 to 14 is considered minor depression, dysthymia, or mild major 
depression. A score of 15 to 19 is considered to indicate moderately severe major depression, 
and a score ≥20 is considered to be severe major depression.  
The PHQ-9 will be completed by the subject at the visits specified in Table 5-2.  
Refer to Section 6.3 for PHQ-9-related withdrawal criteria. 
12.7.8 
Assessment of suicidal ideation and behavior 
Suicidal ideation and behavior will be assessed by using the eC-SSRS; the questionnaire will be 
completed by the subject. This scale will be used to assess suicidal ideation and behavior that 
may occur during the study. The visits at which the eC-SSRS assessments will be performed are 
specified in the schedule of study assessments (Table 5-2). 
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The eC-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; Mundt et al, 2010). 
Subjects respond to standardized clinical questions that are presented in a uniform fashion. The 
eC-SSRS defines 5 subtypes of suicidal ideation and behavior in addition to self-injurious 
behavior with no suicidal intent. The eC-SSRS takes approximately 3 to 10 minutes to complete. 
Refer to Section 6.3 for eC-SSRS-related withdrawal criteria.  
13 
OTHER STUDY MEASUREMENTS 
13.1 
Demography 
The Investigator or designee will collect demographic information for all subjects according to 
local rules and regulations. This will include age, gender, race and ethnicity. Demographic 
information will be recorded in the eCRF. 
The Investigator or designee will obtain a complete history of lifestyle (alcohol or drug 
consumption within 6 months prior to Screening, nicotine consumption at the time of screening) 
and infections (fungal skin infections within 12 months prior to Screening) as part of the 
screening assessment. Lifestyle and infection history will be recorded in the eCRF. 
13.2 
Medical and ankylosing spondylitis history 
The Investigator or designee will obtain a complete medical history and a medical history related 
to AS (including EAMs, the date of diagnosis, and past treatments for AS, and ASAS 
classification criteria as referenced in Section 19.1) as part of the Screening assessment and 
include all clinically relevant past or coexisting medical conditions, responses to AS treatment as 
available, Baseline GI-related symptoms, and surgeries. Findings will be recorded in the eCRF. 
13.3 
Prior and concomitant medications 
As part of the medical history, the Investigator or designee will determine prior and concomitant 
medications and record these in the eCRF. 
14 
STUDY MANAGEMENT AND ADMINISTRATION  
14.1 
Adherence to protocol 
The Investigator should not deviate from the protocol. However, the Investigator should take any 
measure necessary in deviation from or not defined by the protocol in order to protect clinical 
study subjects from any immediate hazard to their health and safety. In this case, this action 
should be taken immediately, without prior notification of the regulatory authority, IRB/IEC, or 
Sponsor.  
After implementation of such measure, the Investigator must notify the CPM of the Sponsor 
within 24 hours and follow any local regulatory requirements. 
14.2 
Monitoring 
UCB (or designee) will monitor the study to meet the CRO’s monitoring Standard Operating 
Procedures (SOPs), ICH-GCP guideline, and applicable regulatory requirements, and to ensure 
that study initiation, conduct, and closure are adequate. Monitoring of the study may be 
delegated by UCB to a CRO or a contract monitor. 
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The Investigator and his/her staff are expected to cooperate with UCB (or designee) and to be 
available during the monitoring visits to answer questions sufficiently and to provide any 
missing information. The Investigator(s)/institution(s) will permit direct access to source 
data/documents for study-related monitoring, audits, IRB/IEC review, and regulatory 
inspection(s). 
The Investigator will allow UCB (or designee) to periodically review all CRFs and 
corresponding source documents (eg, hospital and laboratory records for each study participant). 
Monitoring visits will provide UCB (or designee) with the opportunity to evaluate the progress 
of the study, verify the accuracy and completeness of CRFs, ensure that all protocol 
requirements, applicable authorities’ regulations, and Investigator’s obligations are being 
fulfilled, and resolve any inconsistencies in the study records. 
14.2.1 
Definition of source data  
All source documents must be accurate, clear, unambiguous, permanent, and capable of being 
audited. They should be made using some permanent form of recording (ink, typing, printing, 
optical disc). They should not be obscured by correction fluid or have temporary attachments 
(such as removable self-stick notes). Photocopies and/or printouts of eCRFs are not considered 
acceptable source documents. Source documents are original records in which raw data are first 
recorded. These may include hospital/clinic/general practitioner records, charts, diaries, x-rays, 
laboratory results, printouts, pharmacy records, care records, ECG or other printouts, completed 
scales, quality of life questionnaires, or video, for example. Source documents should be kept in 
a secure, limited access area. 
Electronic Patient-Reported Outcome (ePRO) measures (eg, ASQoL; BASDAI, BASFI, SF-36, 
MOS-12, PGADA, total and nocturnal spinal pain, FACIT-Fatigue, EQ-5D-3L, WPAI-SHP) will 
be completed by each subject and will be collected electronically.  
The data collection and database management system will be supplied by a vendor and will be 
compliant with the relevant regulations. The data collected on the ePROs will be uploaded to a 
central server database and will be sent electronically to UCB (or a designated CRO). 
Sponsor or designee will review to ensure that computerized source documents produced by the 
site are compliant with Food and Drug Administration (FDA) Part 11 requirements and 
document appropriately. Source documents that are computer generated and stored electronically 
must be printed for review by the monitor (eg, ECG reports). Once printed, these copies should 
be signed and dated by the Investigator and become a permanent part of the subject’s source 
documents. The Investigator will facilitate the process for enabling the monitor to compare the 
content of the printout and the data stored in the computer to ensure all data are consistent. 
Electronic data records must be saved and stored as instructed by UCB (or designee).  
14.2.2 
Source data verification 
Source data verification ensures accuracy and credibility of the data obtained. During monitoring 
visits, reported data are reviewed with regard to being accurate, complete, and verifiable from 
source documents (eg, subject files, recordings from automated instruments, tracings [ECG], 
x-ray films, laboratory notes). All data reported on the eCRF should be supported by source 
documents, unless otherwise specified in Section 14.2.1. 
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14.3 
Data handling 
14.3.1 
Case Report Form completion 
This study will use electronic data capture (EDC); the Investigator is responsible for prompt 
reporting of accurate, complete, and legible data in the eCRF and in all required reports. 
This study will also use an electronic device (Site Tablet) to capture patient reported outcomes. 
Serious AE reporting will be done using the eCRF in the appropriate SAE Report Form section 
and transmitted to Patient Safety (see Section 12.1.2.3). The safety database and the clinical 
database will be reconciled during the study and discrepancies will be corrected as needed. 
The Investigator should maintain a list of personnel authorized to enter data into the eCRF. 
Access to the EDC will be given after training has been received. A training certificate will be 
provided and filed. 
Detailed instructions on the use of the EDC will be provided in the eCRF Completion 
Guidelines. 
Corrections made after the Investigator’s review and approval (by means of a 
password/electronic signature) will be re-approved by the Investigator. Any change or correction 
to the eCRF after saving must be accompanied by a reason for the change. 
14.3.2 
Database entry and reconciliation 
Case Report forms/external electronic data will be entered/loaded into a validated electronic 
database using a clinical data management system (CDMS). Computerized data cleaning checks 
will be used in addition to manual review to check for discrepancies and to ensure consistency of 
the data. Case Report Form data are entered into the clinical database using independent, 
double-data entry, with the exception of comment fields, which are verified by a second person. 
The data are entered into the eCRFs once and are subsequently verified if the study is performed 
using electronic data capture. 
An electronic audit trail system will be maintained within the CDMS to track all data changes in 
the database once the data have been saved initially into the system or electronically loaded. 
Regular backups of the electronic data will be performed. 
14.3.3 
Subject Screening and Enrollment log/Subject Identification Code list 
The subject’s screening and enrollment will be recorded in the Subject Screening and Enrollment 
Log. 
The Investigator will keep a Subject Identification Code list. This list remains with the 
Investigator and is used for unambiguous identification of each subject. 
The subject’s consent and enrollment in the study must be recorded in the subject’s medical 
record. These data should identify the study and document the dates of the subject’s 
participation. 
14.4 
Termination of the study 
UCB reserves the right to temporarily suspend or prematurely discontinue this study either at a 
single site, multiple sites, or at all sites at any time for reasons including, but not limited to, 
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safety or ethical issues, inaccurate or incomplete data recording, noncompliance, or 
unsatisfactory enrollment with respect to quality or quantity. 
If the study is prematurely terminated or suspended, UCB (or its representative) will inform the 
Investigators/institutions and the regulatory authority(ies) of the termination or suspension and 
the reason(s) for the termination or suspension, in accordance with applicable regulatory 
requirement(s). The IRB/IEC should also be informed and provided with reason(s) for the 
termination or suspension by the Sponsor or by the Investigator/institution, as specified by the 
applicable regulatory requirement(s). In addition, arrangements will be made for the return of all 
unused IMP and other material in accordance with UCB procedures for the study. 
14.5 
Archiving and data retention 
The Investigator will maintain adequate records for the study, including CRFs, medical records, 
laboratory results, Informed Consent documents, drug dispensing and disposition records, safety 
reports, information regarding participants who discontinued, and other pertinent data. 
All essential documents are to 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 IMP. These documents should be retained 
for a longer period, however, if required by the applicable regulatory requirement(s) or by an 
agreement with UCB (CPMP/ICH/135/95, 2002 [Section 4.9.5]). The Investigator will contact 
UCB for authorization prior to the destruction of any study records or in the event of accidental 
loss or destruction of any study records. The Investigator will also notify UCB should he/she 
relocate or move the study-related files to a location other than that specified in the Sponsor’s 
trial master file. 
14.6 
Audit and inspection 
The Investigator will permit study-related audits mandated by UCB, after reasonable notice, and 
inspections by domestic or foreign regulatory authorities. 
The main purposes of an audit or inspection are to confirm that the rights and well-being of the 
subjects enrolled have been protected, that enrolled subjects (ie, signing consent and undergoing 
study procedures) are appropriate for the study, and that all data relevant for the evaluation of the 
IMP have been processed and reported in compliance with the planned arrangements, the 
protocol, investigational site, and IRB/IEC SOPs, ICH GCP, and applicable regulatory 
requirements. 
The Investigator will provide direct access to all study documents, source records, and source 
data. If an inspection by a regulatory authority is announced, the Investigator will immediately 
inform UCB (or designee). 
14.7 
Good Clinical Practice 
Noncompliance with the protocol, ICH-GCP, or local regulatory requirements by the 
Investigator, institution, institution staff, or designees of the Sponsor will lead to prompt action 
by UCB to secure compliance. Continued noncompliance may result in the termination of the 
site’s involvement in the study. 
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15 
STATISTICS 
A description of statistical methods follows and will be described in more detail in the Statistical 
Analysis Plan (SAP). 
15.1 
Definition of analysis sets 
The following analysis sets were defined: 
• The Enrolled Set (ES) will consist of all subjects who have given informed consent. 
• The Randomized Set (RS) will consist of all randomized subjects. 
• The Safety Set (SS) will consist of all randomized subjects who received at least 1 dose of 
the IMP. 
• The Full Analysis Set (FAS) will consist of all randomized subjects who received at least 
1 dose of the IMP and have a valid measurement of all components of the primary efficacy 
variable at Baseline. 
• The Per-Protocol Set (PPS) will consist of all subjects in the RS who had no important 
protocol deviation affecting the primary efficacy variable. Important protocol deviations will 
be predefined and subjects with important protocol deviations will be evaluated during a data 
evaluation meeting prior to unblinding of the data. Exclusions from the FAS will be 
considered important protocol deviations that also result in exclusion from the PPS. 
• The Pharmacokinetics Per-Protocol Set (PK-PPS) consists of all randomized subjects who 
received at least 1 dose of the IMP and provided at least 1 quantifiable plasma concentration 
post-dose without important protocol deviations that would affect the concentration.  
• The coronavirus disease 2019 (COVID-19) free set will consist of all subjects in the RS who 
had no COVID-19 impact up to the primary efficacy endpoint. Further details will be defined 
as part of the SAP. 
15.2 
General statistical considerations 
Summary statistics will consist of frequency tables for categorical variables. For continuous 
variables, summary statistics will consist of number of available observations, arithmetic mean, 
SD, median, minimum, and maximum unless stated otherwise. 
All statistical tests will be performed 2-sided at a 5% level of significance unless stated 
otherwise. 
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15.3 
Planned efficacy analyses 
15.3.1 
Analysis of the primary and secondary efficacy variables 
A fixed sequence testing procedure will be applied for each of the primary and selected 
secondary variables. The testing procedure will control the family-wise type-I-error and will 
account for multiplicity. The family-wise error will be set to α=0.05 (2-sided).  
For the testing procedure, the hypotheses are mapped into a set ranging from H1 to H12.  
For each test based on a binary efficacy variable, the null hypothesis is that the conditional odds 
ratio is equal to 1. 
H0: ORT1/T2 = 1 
The alternative hypothesis is that the conditional odds ratio is not equal to 1. 
HA: ORT1/T2 ≠ 1  
For each test on a continuous efficacy variable, the null hypothesis is that there is no difference 
between treatment groups. 
H0: T1 – T2 = 0 
The alternative hypothesis is that there is a difference between treatment groups. 
HA: T1 – T2 ≠ 0 
The treatment comparison for each of these hypotheses is between bimekizumab 160mg sc Q4W 
and placebo. Point estimates and 95% confidence intervals (CI) will be calculated. 
The testing starts with H1. If H1 can be rejected at α=0.05 (2-sided), the corresponding α will be 
passed on to the next test in the sequence (ie, H2) and testing will continue. The hierarchical 
testing will be stopped if a hypothesis cannot be rejected at α=0.05 (2-sided). 
The sequential testing procedure of primary and secondary efficacy endpoints is shown in 
Figure 15‒1. 
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Figure 15‒1: Sequential testing procedure of primary/secondary efficacy 
endpoints  
 
ASAS40 (20)=Assessment of SpondyloArthritis International Society 40% (20%) response criteria; 
ASAS5/6=Assessment of SpondyloArthritis International Society 5 out of 6 response criteria; 
ASAS-PR=Assessment of SpondyloArthritis International Society partial remission; ASDAS-MI=Ankylosing 
Spondylitis Disease Activity Score major improvement; ASQoL=Ankylosing Spondylitis Quality of Life; 
BASDAI=Bath Ankylosing Spondylitis Disease Activity Index; BASFI=Bath Ankylosing Spondylitis Functional 
Index; BASMI=Bath Ankylosing Spondylitis Metrology Index; BKZ=bimekizumab; CfB=change from Baseline; 
H=hypothesis; PCS=physical component summary; SF-36=Short Form 36-item Health Survey; TNFα=tumor 
necrosis factor alpha; W=Week 
15.3.1.1 
Analysis of the primary efficacy variable 
The primary efficacy analysis will be performed based on the RS.  
The primary endpoint is the ASAS40 response at Week 16. The primary efficacy analysis will 
evaluate the composite estimand in the RS. The composite estimand combines the clinically 
meaningful improvement from Baseline based on the ASAS40 response and not discontinuing 
treatment early. In practice, this composite estimand is similar to non-responder imputation 
(NRI), referred to here as modified NRI. 
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The following 4 attributes describe the estimand that will be used to define the treatment effect 
of interest for the primary efficacy analysis: 
1. Population = Subjects enrolled according to the protocol-specified inclusion/exclusion 
criteria and randomized to IMP. 
2. Subject-level outcome = ASAS40 at Week 16. 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment prior to Week 16. A composite strategy will be implemented in which a positive 
clinical outcome is defined as achieving ASAS40 at Week 16 and not discontinuing study 
treatment through Week 16. 
4. Population-level summary measure = Conditional odds ratio comparing bimekizumab to 
placebo. 
Missing data at Week 16 that are not preceded by an intercurrent event, and any data after an 
intercurrent event will be imputed as non-responders. 
Any use of prohibited or rescue therapy through Week 16 would constitute an important protocol 
deviation which would be accounted for when the supportive analysis based on the PPS is 
performed (see Section 15.3.1.1.1). 
The statistical hypothesis for the ASAS40 response at Week 16 is that the conditional odds ratio 
for the ASAS40 response in the bimekizumab treatment group relative to the placebo group is 
equal to 1.  
A logistic regression model will be used to assess the effect of bimekizumab vs placebo on 
ASAS40 response. The model will include fixed effects for treatment. The suitability of 
including the stratification variables of prior TNFα inhibitor exposure (yes/no) and region will be 
assessed, and will be added to the model if appropriate. Comparisons will be made for 
bimekizumab vs placebo using the 2-sided Wald test at a significance level of α=0.05 (ie, H1 in 
Figure 15‒1). The odds ratio versus placebo, p-value, and the 95% CI will be calculated. 
15.3.1.1.1 
Supportive analyses 
Supportive analyses for the primary efficacy variable will be conducted. The analyses will be 
repeated: 
1. Based on the PPS to evaluate the effect of important protocol deviations on the analysis.  
2. For all subjects in the FAS to evaluate the consistency between the RS and the more 
restrictive FAS. This analysis will only be performed if the number of subjects in RS and 
FAS are different. 
3. For all individual components of the ASAS40 response to explore the effect of the signs and 
symptoms of the individual components on the composite endpoint. Since all ASAS 
components are continuous variables (eg, change from Baseline in total spinal pain), an 
analysis of covariance (ANCOVA) with treatment, region, and prior TNFα inhibitor 
exposure as fixed effects and the Baseline values as covariate will be used for the analysis. 
4. Using a modified composite estimand where intercurrent events are defined only as 
discontinuation due to adverse event or lack of efficacy. 
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5. Using a treatment policy imputation. 
6. Using a tipping point analysis. 
7. Using observed cases only (OC). 
8. Using the COVID-19-free set. 
Further specification of additional supportive analyses to evaluate varying assumptions related to 
the handling of missing data will also be performed and are described in Section 15.7. 
15.3.1.2 
Analyses of the secondary efficacy variables 
The secondary efficacy variables will be analyzed for all subjects in the RS.  
Binary variables will be analyzed to evaluate the composite estimand in the RS, as done for the 
primary efficacy variable. The composite estimand combines (1) achieving the given binary 
response and (2) not discontinuing treatment prior to Week 16. The statistical hypothesis for the 
binary variables at Week 16 is that the conditional odds ratio for binary variables in the 
bimekizumab treatment group compared with the placebo treatment group is equal to 1. 
Continuous variables will be analyzed for treatment effects using a similar estimand approach as 
for the primary efficacy variable, except for the following: 
• Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment prior to Week 16. A hypothetical strategy for addressing intercurrent events will be 
implemented. This estimand targets the treatment difference in a scenario where withdrawal 
from study treatment does not occur, such that outcomes for subjects without an intercurrent 
event are as observed, and outcomes for subjects with an intercurrent event are treated as 
though they had completed the randomized study treatment through Week 16. A multiple 
imputation strategy will be used to impute data following an intercurrent event. 
• Population-level summary measure = The difference in adjusted means between 
bimekizumab and placebo. 
Any missing data at Week 16 that is not preceded by an intercurrent event (ie, discontinuation of 
study medication) will be imputed based on a predefined multiple imputation (MI) model. The 
missing value will be replaced by a set of plausible values, where each value is a Bayesian draw 
from the conditional distribution of the missing data given the observed data. Intermittent 
missing data will be imputed using the Markov-Chain Monte Carlo (MCMC) method, followed 
by monotone regression for monotone missing data. The statistical model for the comparison of 
bimekizumab and placebo will be an ANCOVA with treatment, region, and prior TNFα inhibitor 
exposure as fixed effects and the Baseline value as covariate. The statistical hypothesis for the 
continuous variables at Week 16 is that the treatment difference between the bimekizumab 
treatment group and placebo is equal to 0. 
All secondary efficacy variables will also be summarized based on observed case data. Binary 
outcomes will also be summarized using the modified composite estimand. 
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15.3.2 
Analyses of other efficacy variables 
All other efficacy variables will be analyzed based on the RS.  
Binary variables will be summarized using frequency tables by each visit. Generally, the 
estimand structure for binary other efficacy variables is as described below. Note that further 
details will be provided in the SAP. 
1. Population = Subjects meeting the protocol-specified inclusion/exclusion criteria. 
2. Subject-level outcome = The given variable and time point being summarized (eg, ASAS-PR 
at Week 24). 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment prior to the time point being summarized. A composite strategy will be 
implemented in which a positive clinical outcome is defined as achieving the given variable 
at the specified time point and not discontinuing study treatment through that time point. 
4. Population-level summary measure = Unadjusted proportion of responders. 
Any missing data that are not preceded by an intercurrent event as described above will be 
imputed based on a NRI as described for the primary and secondary efficacy variables. 
Continuous variables will be summarized using descriptive statistics by each visit. Generally, the 
estimand structure for continuous other efficacy variables is as described below. Note that further 
details will be provided in the SAP. 
1. Population = Subjects meeting the protocol-specified inclusion/exclusion criteria. 
2. Subject-level outcome = The given variable and time point being summarized (eg, Change 
from Baseline in BASFI at Week 36). 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment prior to the time point being summarized. A hypothetical strategy will be 
implemented in which outcomes for subjects without an intercurrent event are as observed at 
the given time point, and outcomes for subjects with an intercurrent event are treated as 
though they had completed the randomized study treatment through the time point being 
summarized. A multiple imputation strategy will be used to impute data following an 
intercurrent event.  
4. Population-level summary measure = Unadjusted mean. 
Any missing data that are not preceded by an intercurrent event as described above will be 
imputed based on a predefined multiple imputation model as described for continuous secondary 
efficacy variables. 
In some cases, other efficacy variables may also be summarized based on observed case data (ie, 
subjects with missing data or who have prematurely discontinued study treatment are treated as 
missing). 
Time to ASAS20/40 response will be estimated and presented using the Kaplan-Meier 
product-limit method for each treatment. Time to a given response will be defined as the length 
in days from Baseline until the first date when the response is achieved. Subjects who 
discontinue study treatment prior to achieving a response will be censored at the date of study 
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treatment discontinuation. The median time to response, including the 2-sided 95% CI, will be 
calculated for each treatment. Between-group differences will be analyzed with the log-rank 
statistic. 
15.3.3 
Subgroup analyses 
Subgroup analyses using descriptive statistics will be performed on the primary efficacy 
variable. The following variables for subgroup analyses will be defined:  
• Age at Baseline (<45 years of age; ≥45 years of age) 
• Gender (male; female) 
• Disease duration (<5 years; ≥5 years) 
• Region (eg, Asia, Eastern Europe, North America, Western Europe) 
• Body mass index at Baseline (<18.5kg/m2; 18.5kg/m2 to <25kg/m2; 25kg/m2 to <30kg/m2; 
≥30kg/m2) 
• Prior TNFα inhibitor exposure (yes; no) 
• CRP at Baseline (≤ULN; >ULN) 
• ASDAS status at Baseline (<1.3 [inactive disease]; 1.3 to ≤2.1 [low disease activity]; 
>2.1 to ≤3.5 [high disease activity]; >3.5 [very high disease activity]) 
• HLA-B27 positivity (yes; no) 
• Anti-bimekizumab antibody status (positive, negative) 
15.4 
Planned safety analyses 
15.4.1 
Safety analyses 
Safety variables will be analyzed for all subjects in the SS. 
Adverse events will be coded according to the Medical Dictionary for Regulatory Activities 
(MedDRA® 19.0). Adverse events with an onset date on or after the date of first IMP 
administration and up to 20 weeks after the last (most recent) dose of IMP will be defined as 
TEAEs. Treatment-emergent AEs will be summarized descriptively by treatment group, primary 
system organ class, high level term, and preferred term. Additional tables will summarize TEAEs 
leading to withdrawal from IMP, TEAEs by intensity and relationship to IMP. Treatment 
emergent AEs leading to withdrawal from both IMP or the study, serious TEAEs, TEAEs of 
special interest, TEAE of special monitoring, and deaths will be also be tabulated and listed. 
When analyzing categorical data, the number and percentage of subjects in each category will be 
presented by treatment group. In addition, shift tables may be used to evaluate the number and 
percentage of subjects having a different post-Baseline status when compared to their Baseline 
status. 
Laboratory values (including markedly abnormal values), urinary values, vital signs, ECGs, 
eC-SSRS, and extent of exposure will be presented descriptively by treatment group. Definitions 
for markedly abnormal laboratory values will be provided in the SAP. 
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15.5 
Planned other analyses 
15.5.1 
Pharmacokinetic analyses 
Pharmacokinetic variables will be analyzed for all subjects in the PK-PPS.  
Pharmacokinetic analyses will be detailed in a separate data analysis plan and reported in a 
separate document.  
Bimekizumab plasma concentrations will be summarized by treatment arm for subjects who 
received at least 1 dose of bimekizumab at applicable time points scheduled in Table 5-2. 
15.5.2 
Immunological analyses 
Anti-bimekizumab antibody levels will be determined using a tiered approach applying 
Screening, Confirmatory, and Titration assays. The details of this approach will be described in a 
separate Analytical Plan. Anti-bimekizumab antibody levels will be summarized by treatment 
arm for subjects who received at least 1 dose of bimekizumab at applicable time points 
scheduled in Table 5-2. 
15.6 
Handling of protocol deviations 
Important protocol deviations are deviations from the protocol which potentially could have a 
meaningful impact on study conduct or on the primary efficacy, key safety, or PK outcomes for 
an individual subject. The criteria for identifying important protocol deviations will be defined 
within the appropriate protocol-specific document. Important protocol deviations will be 
reviewed as part of the ongoing data cleaning process and all important deviations will be 
identified and documented prior to unblinding to confirm exclusion from analysis sets. 
15.7 
Handling of dropouts or missing data 
The primary analysis for the primary variable will use a conservative approach to handling 
missing data that is similar to non-responder imputation. The sensitivity of results to the 
approach for handling missing data will be evaluated via supportive analyses using different 
missing data mechanisms. 
In instances where MI is used, the missing value is replaced by a set of plausible values, where 
each value is a Bayesian draw from the conditional distribution of the missing data given the 
observed data. Intermittent missing data will be imputed using the MCMC method, followed by 
regression for monotone missing data. The planned multiple imputation procedures are based on 
an assumption of data missing at random (MAR).  
The following supportive analyses for the primary efficacy variable will be conducted: 
1. Multiple imputation as described above will be performed using the modified composite 
estimand as specified for the use with the secondary variables. The definition of an 
intercurrent event is changed from all treatment discontinuation, to discontinuation of 
treatment due to AE or lack of efficacy.  
2. Tipping point analyses will be performed to evaluate missingness assumptions. These tipping 
point analyses will be performed on the monotone missing data and only if the primary 
analysis is significant at α=0.05. Various delta adjustments will be made to the assumed 
responses on the monotone missing data in each treatment group independently with various 
degrees of plausibility. It will include scenarios where subjects who have missing data and 
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are randomized to bimekizumab have a lower probability of response compared to subjects 
who have missing data and were randomized to placebo. For binary variables, this includes 
the worst case scenario where subjects who have missing data and are randomized to 
bimekizumab are considered nonresponders, while subjects who have missing data and were 
randomized to placebo are considered responders. The goal of the tipping point analysis is to 
systematically vary assumptions until there is no evidence of a treatment effect (if possible). 
The plausibility of such required delta adjustment will then be assessed. Details will be 
provided in the Statistical Analysis Plan (SAP).  
3. The treatment policy strategy for addressing intercurrent events will be considered. This will 
be based on an analysis of all available data at Week 16 regardless of the occurrence of 
intercurrent events. This analysis will use the same models specified for the primary and 
secondary analyses, where subjects are analyzed according to their randomized treatment, 
even if they discontinued study treatment for any reason prior to Week 16. Even though 
efforts will be made to collect the primary outcome data for all subjects at Week 16, there 
may still be some subjects for whom Week 16 efficacy data cannot be obtained. In this case, 
missing data will be imputed using MI under the assumption of MAR. Results will be 
combined into a single inference using Rubin's rule. It should be noted that this measures 
something different from the primary analysis and could be confounded by placebo subjects 
who withdraw and are subsequently on another active medication at the time of the Week 16 
assessment. Therefore, the results of this analysis should be interpreted in the appropriate 
context.  
4. An additional supportive analysis will be based on observed data only for subjects who are 
still on the initially randomized treatment at Week 16. Subjects with missing data or who 
have prematurely discontinued study treatment will be treated as missing. 
For the secondary and other efficacy variables, the binary endpoints will be analyzed using 
modified NRI, MI, and OC, and the continuous endpoints will be analyzed using MI and OC. 
Additional details on these supportive analyses will be provided in the SAP. 
15.8 
Planned interim analysis and data monitoring 
15.8.1 
Interim analyses 
Two interim analyses will be performed: one after the planned number of randomized subjects 
have completed the Double-Blind Treatment Period and the Week 24 assessments, and one after 
the planned number of subjects have completed Week 52.  
The purpose of the Week 24 interim analysis is to perform a comprehensive evaluation of all 
available double-blind data for the 2 treatment arms and to prepare a regulatory submission for a 
Marketing Authorization Application based on this analysis. 
For the Week 24 interim analysis, the database will be locked and the treatment codes will be 
made available to UCB personnel with exception of operational staff working on the study. An 
interim report will be written. The Investigators and subjects will remain blind to the original 
randomized IMP dosing regimen until the subject completes the Maintenance Period at Week 52. 
The Week 24 interim analysis will evaluate the primary and secondary efficacy variables, as well 
as all other efficacy, safety, and PK variables up to Week 24 according to the statistical methods 
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specified in the SAP. No formal alterations to the further study conduct (eg, stopping rules, 
sample size re-estimation, or changes to eligibility criteria) are planned for this interim analysis. 
To ensure blinding of Investigators and subjects, a statistical blinding plan will be written to 
evaluate the potential bias of the Maintenance Period, define blinded and unblinded teams, and 
describe the process of interim results generation and dissemination. The plan will be finalized 
prior to the lock of the database at the Week 24 interim analysis. 
The purpose of the Week 52 interim analysis is to perform a comprehensive evaluation of all 
available data for the study and to supplement the regulatory submission based on the Week 24 
interim analysis. 
The Week 52 interim analysis will evaluate all efficacy, safety, and PK variables up to Week 52 
according to the statistical methods specified in the SAP. Only data from the SFU visits for 
subjects who discontinued and did not enter the extension study will not be included. 
Additional interim analyses and data cuts may be performed for regulatory purposes. 
15.8.2 
Data monitoring and Adjudication Committees 
A DMC will be reviewing safety data on an ongoing basis. The DMC membership includes 
experienced clinicians and a statistician, all of whom have expertise in clinical studies. Further 
details are specified in the DMC Charter. 
Cardiovascular and Neuropsychiatric Adjudication Committees will also periodically review 
data from this study. Details are provided in the Cardiovascular Adjudication Committee and 
Neuropsychiatric Adjudication Committee charters.  
Other adjudication committees may be added as necessary. 
Both Data Monitoring and Adjudication Committee members may not participate in the study as 
principal or co-Investigators, or as study subject care physicians and must not be members of the 
study team at UCB or the conducting CRO. The duration of membership for the committees will 
be inclusive of planned analyses for AS0011.  
15.9 
Determination of sample size 
Approximately 300 subjects will be randomly assigned in a 2:1 ratio to the following treatment 
groups: bimekizumab 160mg sc Q4W (200 subjects) or placebo sc Q4W (100 subjects).  
The primary efficacy analysis is based on the bimekizumab dose versus placebo for 
ASAS40 response at Week 16.  
All sample size and power calculations were done at a significance level of 0.05. 
All sample size and power calculations were performed using the software nQuery Advisor® 7.0. 
15.9.1 
Power calculation for primary endpoint 
The sample size assumptions for bimekizumab versus placebo are based on the ASAS40 
response data from the Phase 2b bimekizumab study in subjects with active AS (AS0008). 
An ASAS40 response at Week 16 of 40% can be assumed for the bimekizumab treatment group. 
This assumed treatment response is based on the bimekizumab 160mg dose results of AS0008 at 
Week 12 (46.7%). It was also assumed that the treatment response at Week 12 and Week 16 
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would be the same (ie, conservative assumption). In addition, the observed ASAS40 response 
rates were adjusted to account for a higher number of subjects with prior TNFα inhibitor 
exposure and for a higher number of subjects with early withdrawal. Placebo ASAS40 response 
at Week 16 was assumed to be 15% and is more conservative than that of AS0008 at Week 12 
(ie, ASAS40 response=13.3%).  
The sample size for showing statistical superiority of bimekizumab versus placebo was 
calculated using a 2-sided 2-sample Chi square test with continuity correction (Fleiss et al, 
1980). With 200 subjects in the bimekizumab treatment group and 100 subjects in the placebo 
group, the test for detecting statistical superiority of bimekizumab versus placebo based on 
ASAS40 response at Week 16 is powered with >99%. 
15.9.2 
Power calculations for secondary endpoints in the hierarchical 
testing 
The assumptions for power calculations of the secondary endpoints are based on the Week 12 
results of AS0008, unless indicated otherwise. It was assumed that the treatment response at 
Week 12 and Week 16 would be the same (ie, conservative assumption). In addition, the 
observed data were adjusted in the same way as the primary endpoint to account for a higher 
number of subjects with prior TNFα inhibitor exposure and for a higher number of subjects with 
early withdrawal.  
All power calculations for binary endpoints were performed using a 2-sided 2-sample Chi-square 
test with continuity correction (Fleiss et al, 1980). All power calculations for continuous 
endpoints were performed using a 2-sided 2-group Satterthwaite t-test (Moser et al, 1989) The 
power calculations provided below represent independent evaluations for each endpoint and do 
not account for multiplicity. 
For ASAS40 response of the TNFα inhibitor-naïve population at Week 16, an ASAS40 response 
of 48% for the bimekizumab group was assumed. Placebo ASAS40 response at Week 16 is 18%. 
It is also assumed that 70% of the subjects in each treatment group are TNFα inhibitor-naïve. 
With those assumptions, the endpoint is powered with >99% at the planned sample size (ie, 
140 and 70 subjects in the bimekizumab and placebo group, respectively). 
For ASAS20 response at Week 16, an ASAS20 response of 70% for the bimekizumab group was 
assumed. Placebo ASAS20 response at Week 16 is 30%. With those assumptions, the endpoint is 
powered with 99% at the planned sample size. 
For change from Baseline in BASDAI total score at Week 16, an adjusted between-treatment 
difference of - 1.38 with an SD=1.8 for bimekizumab and SD=1.4 for placebo was used. With 
those assumptions, the endpoint is powered with >99% at the planned sample size. 
For ASAS-PR at Week 16, an ASAS-PR of 17% for the bimekizumab group was assumed. 
Placebo ASAS-PR at Week 16 was assumed to be 3.3%. With those assumptions, the endpoint is 
powered with 94% at the planned sample size. 
For ASDAS-MI at Week 16, the ASDAS-MI data of AS0008 at Week 12 and Week 16 were 
used and the placebo response was extrapolated to Week 16. The assumed ASDAS-MI are 
36.0% and 13.8% at Week 16 for the bimekizumab and placebo group, respectively. With those 
assumptions, the endpoint is powered with 98% at the planned sample size. 
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For ASAS5/6 response at Week 16, an ASAS5/6 response of 44% for the bimekizumab group 
was assumed. Placebo ASAS-PR at Week 16 was assumed to be 5%. With those assumptions, 
the endpoint is powered with >99% at the planned sample size. 
For change from Baseline in BASFI at Week 16, an adjusted between-treatment difference 
of - 2.35 with an SD=1.9 for bimekizumab and placebo was used. With those assumptions, the 
endpoint is powered with >99% at the planned sample size. 
For change from Baseline in nocturnal spinal pain score at Week 16, the AS data from the 
certolizumab pegol study AS001 were used. An adjusted between-treatment difference of -1.88 
with an SD=2.9 for bimekizumab and SD=2.4 for placebo was used. With those assumptions, the 
endpoint is powered with >99% at the planned sample size. 
For change from Baseline in ASQoL total score at Week 16, an adjusted between-treatment 
difference of - 2.39 with an SD=4.5 for bimekizumab and placebo was used. With those 
assumptions, the endpoint is powered with >99% at the planned sample size. 
For change from Baseline in SF-36 PCS score at Week 16, an adjusted between-treatment 
difference of 4.56 with an SD=8.1 for bimekizumab and SD=5.8 for placebo was used. With 
those assumptions, the endpoint is powered with >99% at the planned sample size. 
For change from Baseline in BASMI at Week 16, an adjusted between treatment difference 
of - 0.55 with an SD=0.8 for bimekizumab and SD=0.7 for placebo was used. With those 
assumptions, the endpoint is powered with >99% at the planned sample size. 
16 
ETHICS AND REGULATORY REQUIREMENTS 
16.1 
Informed consent 
Subject’s informed consent must be obtained and documented in accordance with local 
regulations, ICH-GCP requirements, and the ethical principles that have their origin in the 
principles of the Declaration of Helsinki. 
Prior to obtaining informed consent, information should be given in a language and at a level of 
complexity understandable to the subject in both oral and written form by the Investigator (or 
designee). Each subject will have the opportunity to discuss the study and its alternatives with 
the Investigator. 
Prior to participation in the study, the Informed Consent Form should be signed and personally 
dated by the subject and by the person who conducted the informed consent discussion 
(Investigator or designee). The subject must receive a copy of the signed and dated Informed 
Consent Form. As part of the consent process, each subject must consent to direct access to 
his/her medical records for study-related monitoring, auditing, IRB/IEC review, and regulatory 
inspection. 
If the Informed Consent Form is amended during the study, the Investigator (or the Sponsor, if 
applicable) must follow all applicable regulatory requirements pertaining to the approval of the 
amended Informed Consent Form by the IRB/IEC and use of the amended form. 
All studies conducted at centers in the United States must include the use of a Health Insurance 
Portability and Accountability Act Authorization Form. 
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The subject may withdraw his/her consent to participate in the study at any time. A subject is 
considered as enrolled in the study when he/she has signed the Informed Consent Form. A eCRF 
must not be started, nor may any study specific procedure be performed for a given subject, 
without having obtained his/her written consent to participate in the study. 
16.2 
Subject identification cards 
Upon signing the Informed Consent Form, the subject will be provided with a subject 
identification card in the language of the subject. The Investigator will fill in the subject 
identifying information and medical emergency contact information. The Investigator will 
instruct the subject to keep the card with him/her at all times. 
16.3 
Institutional Review Boards and Independent Ethics 
Committees 
The study will be conducted under the auspices of an IRB/IEC, as defined in local regulations, 
ICH-GCP, and in accordance with the ethical principles that have their origin in the Declaration 
of Helsinki. 
The Investigator/UCB will ensure that an appropriately constituted IRB/IEC that complies with 
the requirements of the current ICH-GCP version or applicable country-specific regulations will 
be responsible for the initial and continuing review and approval of the clinical study. Prior to 
initiation of the study, the Investigator/UCB will forward copies of the protocol, Informed 
Consent Form, Investigator’s Brochure, Investigator’s curriculum vitae (if applicable), 
advertisement (if applicable), and all other subject-related documents to be used for the study to 
the IRB/IEC for its review and approval. 
Before initiating a study, the Investigator will have written and dated full approval from the 
responsible IRB/IEC for the protocol. 
The Investigator will also promptly report to the IRB/IEC all changes in the study, all 
unanticipated problems involving risks to human subjects or others, and any protocol deviations, 
to eliminate immediate hazards to subjects. 
The Investigator will not make any changes in the study or study conduct without IRB/IEC 
approval, except where necessary to eliminate apparent immediate hazards to the subjects. For 
minor changes to a previously approved protocol during the period covered by the original 
approval, it may be possible for the Investigator to obtain an expedited review by the IRB/IEC as 
allowed. 
As part of the IRB/IEC requirements for continuing review of approved studies, the Investigator 
will be responsible for submitting periodic progress reports to the IRB/IEC (based on IRB/IEC 
requirements), at intervals appropriate to the degree of subject risk involved, but no less than 
once per year. The Investigator should provide a final report to the IRB/IEC following study 
completion. 
UCB (or its representative) will communicate safety information to the appropriate regulatory 
authorities and all active Investigators in accordance with applicable regulatory requirements. 
The appropriate IRB/IEC will also be informed by the Investigator or the Sponsor, as specified 
by the applicable regulatory requirements in each concerned country. Where applicable, 
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Investigators are to provide the Sponsor (or its representative) with evidence of such IRB/IEC 
notification. 
16.4 
Subject privacy 
UCB staff (or designee) will affirm and uphold the subject’s confidentiality. Throughout this 
study, all data forwarded to UCB (or designee) will be identified only by the subject number 
assigned at Screening. 
The Investigator agrees that representatives of UCB, its designee, representatives of the relevant 
IRB/IEC, or representatives of regulatory authorities will be allowed to review that portion of the 
subject’s primary medical records that directly concerns this study (including, but not limited to, 
laboratory test result reports, ECG reports, admission/discharge summaries for hospital 
admissions occurring during a subject’s study participation, and autopsy reports for deaths 
occurring during the study). 
16.5 
Protocol amendments 
Protocol changes may affect the legal and ethical status of the study and may also affect the 
statistical evaluations of sample size and the likelihood of the study fulfilling its primary 
objective. 
Significant changes to the protocol will only be made as an amendment to the protocol and must 
be approved by UCB, the IRB/IEC, and the regulatory authorities (if required), prior to being 
implemented. 
17 
FINANCE, INSURANCE, AND PUBLICATION 
Insurance coverage will be handled according to local requirements. 
Finance, insurance, and publication rights are addressed in the Investigator and/or CRO 
agreements, as applicable. 
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18 
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Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), Psoriatic Arthritis 
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Network 2015 Recommendations for the Treatment of Ankylosing Spondylitis and 
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19 
APPENDICES 
19.1 
ASAS classification criteria for axial SpA 
Table 19‒1: ASAS classification criteria for axial SpA (for subjects with 
chronic back pain of at least 3 months and age at onset <45 years) 
Imaging criteria 
ASAS clinical criteria for axial SpA 
Sacroiliitis (MRI or radiographsa) plus ≥1 SpA feature 
HLA-B27 plus ≥2 other SpA features 
SpA featuresb 
 
Inflammatory back painc  
Psoriasis 
Arthritis 
Crohn’s disease/ulcerative colitis 
Enthesitis (heel)  
HLA-B27 
Uveitis  
Elevated CRP 
Dactylitis 
 
ASAS=Assessment of SpondyloArthritis International Society; axSpA=axial spondyloarthritis; CRP=C-reactive 
protein; HLA-B27=human leukocyte antigen B27; MRI=magnetic resonance imaging; NSAID=nonsteroidal 
anti-inflammatory drug; SpA=spondyloarthritis 
a Active inflammatory lesions of sacroiliac joints with definite bone marrow oedema/osteitis suggestive of 
sacroiliitis associated with spondyloarthritis in MRI or radiographic sacroiliitis Grade 2 to 4 bilaterally or 
Grade 3 to 4 unilaterally according to modified NY criteria. For this study, only MRI will be permitted for 
study entry for the imaging criterion. 
b “Family history for SpA” and “Good response to NSAIDs” are excluded as SpA feature criteria. 
c Inflammatory back pain according to ASAS criteria for axSpA defined as the presence of 4 out of 5 of the 
following parameters: 
1. age at onset <45 years 
2. insidious onset 
3. improvement with exercise 
4. no improvement with rest 
5. pain at night (with improvement upon getting up) 
 
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19.2 
Modified New York (mNY) Classification Criteria for AS 
Table 19‒2: Modified New York (mNY) Classification Criteria for AS  
Diagnosis 
Clinical criteria: 
a. Low back pain and stiffness for more than 3 months which improves with exercise, but is 
not relieved by rest  
b. Limitation of motion of the lumbar spine in both the sagittal and frontal planes. 
c. Limitation of chest expansion relative to normal values corrected for age and sex. 
Radiologic criterion: 
Sacroiliitis grade ≥2 bilaterally or grade 3 to 4 unilaterally 
Grading 
Definite ankylosing spondylitis if the radiologic criterion is associated with at least 1 clinical 
criterion 
AS=ankylosing spondylitis; mNY=modified New York Criteria 
Note: A second grading of “probable ankylosing spondylitis” is part of the modified NY criteria, but it is not 
applicable for this study.  
 
 
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19.3 
Protocol Amendment 1 
Rationale for the amendment 
The major purpose of this protocol amendment was to implement changes in response to 
scientific discussions and feedback provided at meetings with Investigators and advisors or for 
clarifications. Mainly, imaging assessments were amended with sacroiliac joint and spine MRIs 
performed at Weeks 16 and 52 for all consenting subjects participating in the MRI substudy 
regardless of MRI positivity at Baseline. These additional MRIs will allow an exploratory 
evaluation of any changes in the sacroiliac joint or spine after 16 or 52 weeks in subjects who 
were MRI-negative at Baseline and on early signals such as the impact on erosions and fatty 
lesions at Week 16. Additionally, including MRI-positive and MRI-negative subjects in the 
substudy was considered a more holistic strategy comparable to the approach used for other 
compounds. At the same time, the number of participating subjects will be expanded to include 
subjects in the substudy without restriction. 
Further key changes are summarized below. The amendment: 
• Clarifies that the minimum duration of the Screening Period of 14 days does not apply to 
screenfailed subjects from AS0010 who are screened for AS0011.  
• Changes the categorization of PHQ-9 from an other efficacy variable to an other safety 
variable for consistency within the program. 
• Clarifies that protected adults will not be enrolled in the study.  
• Clarifies that subjects with a diagnosis of PsA will be excluded from the study as per the 
revised Exclusion Criterion 17.  
• Adds new sections summarizing all within-study rescreening/retesting and cross-study 
screening rules in one place and updates corresponding protocol sections. 
• Updates the IMP description for consistency within the program. 
• Updates for clarification and adds more detail to sections presenting exclusionary, 
concomitant, or rescue medication. 
− To clarify that permitted acetaminophen/paracetamol serve as examples for the larger 
group of analgesics and are permitted as rescue therapy except for 24 hours prior to any 
study visit. 
− To add that topical steroids are permitted. 
− To clarify that any change in dose/dose regimen of oral corticosteroids within 14 days 
prior to Baseline is exclusionary. 
− To clarify that apremilast used as a rescue medication can be dosed as per Investigator’s 
discretion or local label. 
− To clarify that the use of more than 1 TNFα inhibitor and the inclusion of any subject not 
meeting the related Inclusion criterion is exclusionary. 
• Restructures sections related to exclusionary, concomitant medication, or rescue medication 
to allow a side by side presentation in one table. 
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• Clarifies that the 12-item MOS Sleep Scale is rated using the 5-point scale. 
• Removes the option for enrollment in a separate observational pregnancy follow-up study 
sponsored by UCB. 
• Updates statistical terminology and replaces “sensitivity analyses” with “supportive 
analyses”. 
• Increases the threshold for subgroup analyses by disease duration from 2 to 5 years. 
• Updates the section detailing the status of bimekizumab studies. 
• Updates the list of references. 
• Updates instances of “AS” in the summary and introduction to clarify that “AS” is also 
known as “radiographic axSpA”. 
• Updates instances of “ASAS criteria” to “ASAS classification criteria” for consistency where 
applicable. 
In addition, a few minor updates including consistency changes for PDILI-related text, contact 
details, the list of abbreviations, and minor formatting changes for the purpose of clarity have 
been made. 
Modifications and changes 
Global changes 
The following changes were made throughout the protocol: 
• All instances that referred to “legal representatives” were updated to remove this terminology 
from the entire protocol. Protected adults will not be enrolled in the study. 
• All instances that referred to a minimum of 14 days for the Screening Period have been 
updated to clarify that this requirement does not apply to screenfailed subjects from AS0010 
who are screened for AS0011. The minimum requirement is still applicable to all other 
subjects. 
• All instances of “sensitivity analysis” were replaced with “supportive analysis”. The revision 
corresponds to the structure of study estimands described in the ICH E9 (R1) Addendum. 
 
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Specific changes 
Change #1 
Study contact details 
Sponsor study physician 
 
UCB BIOSCIENCES Ltd. 
208 Bath Road 
Slough SL1 3WE 
UNITED KINGDOM 
 
Has been changed to: 
 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Straße 10 
40789 Monheim am Rhein 
GERMANY 
 
Clinical Trial Biostatistician 
 
UCB BIOSCIENCES Inc. 
8010 Arco Corporate Drive 
Raleigh, NC 27617 
UNITED STATES 
 
Has been changed to: 
 
UCB BIOSCIENCES Ltd. 
208 Bath Road 
Slough SL1 3WE 
UNITED KINGDOM 
 
 
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Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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Change #2 
Section 1, Summary, paragraph 1 sentence 1 and paragraph 7  
This is a multicenter, Phase 3, randomized, double-blind, placebo-controlled study to evaluate 
the efficacy and safety of bimekizumab in subjects with active ankylosing spondylitis (AS), a 
subtype of axial spondyloarthritis (axSpA) with radiographic evidence of disease. 
... 
The overall study design consists of a Screening Period (≥14 days to ≤35 days), a 16-week 
Double-Blind Treatment Period, a 36-week Maintenance Period, and a Safety Follow-Up (SFU) 
Visit 20 weeks after the final dose of the investigational medicinal product (IMP) .... 
Has been changed to: 
This is a multicenter, Phase 3, randomized, double-blind, placebo-controlled study to evaluate 
the efficacy and safety of bimekizumab in subjects with active ankylosing spondylitis (AS), a 
subtype of axial spondyloarthritis (axSpA) with radiographic evidence of disease (also known as 
radiographic axSpA [r-axSpA]). 
... 
The overall study design consists of a Screening Period (minimum of approximately 14 days 
[unless a screenfailed subject from AS0010 will be screened in AS0011] to ≤35 days), a 
52-week Treatment Period consisting of a 16-week Double-Blind Treatment Period, a 36-week 
Maintenance Period, and a Safety Follow-Up (SFU) Visit 20 weeks after the final dose of the 
investigational medicinal product (IMP) ... 
 
Change #3 
Section 2.1, Axial spondyloarthritis, paragraph 2, sentence 3 
Therefore, peripheral SpA includes diseases affecting mainly peripheral joints, such as reactive 
arthritis and PsA, whereas axSpA comprises those diseases with mainly axial involvement 
(sacroiliac joints and spine), including AS diagnosed with definite radiographic changes of the 
sacroiliac joint and nr-axSpA.  
Has been changed to: 
Therefore, peripheral SpA includes diseases affecting mainly peripheral joints, such as reactive 
arthritis and PsA, whereas axSpA comprises those diseases with mainly axial involvement 
(sacroiliac joints and spine), including AS (also known as r-axSpA) diagnosed with definite 
radiographic changes of the sacroiliac joint and nr-axSpA.  
 
Change #4 
Section 2.2.2.1, Completed studies, paragraph 1 
Nine clinical studies of bimekizumab have been completed: UP0008 in 39 subjects with 
mild-to-moderate plaque PSO, RA0124 in 30 healthy volunteers, PA0007 in 53 subjects with 
PsA, UP0031 in 12 healthy volunteers, UP0042 in 48 Japanese and Caucasian healthy 
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Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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volunteers, RA0123 in 159 subjects with moderate-to-severe RA, PS0010 in 250 subjects with 
moderate-to-severe chronic plaque PSO, PS0016 in 49 subjects with moderate-to-severe chronic 
plaque PSO, and UC0011 in 23 subjects with moderate-to-severe active ulcerative colitis. 
Has been changed to: 
Nine Thirteen clinical studies of bimekizumab have been completed: UP0008 in 39 subjects 
with mild-to-moderate plaque PSO, RA0124 in 30 healthy volunteers, PA0007 in 53 subjects 
with PsA, UP0031 in 12 healthy volunteers, UP0042 in 48 Japanese and Caucasian healthy 
volunteers, RA0123 in 159 subjects with moderate-to-severe RA, PS0010 in 250 subjects with 
moderate-to-severe chronic plaque PSO and the corresponding extension study (PS0011), 
PS0016 in 49 subjects with moderate-to-severe chronic plaque PSO and the corresponding 
extension study (PS0018), UC0011 in 23 subjects with moderate-to-severe active ulcerative 
colitis, AS0008 in 303 subjects with AS, and PA0008 in 206 subjects with PsA. 
 
Change #5 
Section 2.2.2.2, Ongoing studies 
The following bullet has been deleted: 
• AS0008 is a Phase 2b, double-blind, randomized, placebo-controlled, multiple-dose study to 
evaluate the efficacy and safety of bimekizumab in subjects with active AS.  
 
The following bullet has been added: 
• AS0010 is a Phase 3, double-blind, randomized, placebo-controlled study to evaluate 
the efficacy and safety of bimekizumab in subjects with active nr-axSpA. 
 
Change #6 
Section 4.3.1, Other efficacy variables 
The following variable has been removed: 
• Change from Baseline in Patient Health Questionnaire-9 (PHQ-9) 
 
Change #7 
Section 4.3.2, Other safety variables 
The following variable has been added: 
• Change from Baseline in Patient Health Questionnaire-9 (PHQ-9) 
 
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Bimekizumab 
AS0011 
 
 
 
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Change #8 
Section 5.1, Study description, paragraph 3 
The study will include the following 3 periods: a Screening Period (≥14 days to ≤35 days), a 
Treatment Period (52 weeks) consisting of a 16-week Double-Blind Treatment Period and a 36-
week Maintenance Period, and a SFU Period (20 weeks after the final dose of IMP). 
Has been changed to: 
The study will include the following 3 periods: a Screening Period (minimum of approximately 
14 days [unless a screenfailed subject from AS0010 will be screened in AS0011] to 
≤35 days), a Treatment Period (52 weeks) consisting of a 16-week Double-Blind Treatment 
Period and a 36-week Maintenance Period, and a SFU Period (20 weeks after the final dose of 
IMP). 
 
Change #9 
Section 5.1.1, Screening Period/Baseline, paragraph 1 first sentence 
Assessments of eligibility as described in Section 6 will be initiated during the Screening Period 
with a minimum duration of 14 days and a maximum duration of up to 35 days. 
Has been changed to: 
Assessments of eligibility as described in Section 6 will be initiated during the Screening Period 
with a minimum duration of approximately 14 days (unless a screenfailed subject from 
AS0010 will be screened in AS0011) and a maximum duration of up to 35 days. 
The following paragraph was added: 
All subjects will have an anterior posterior (AP) pelvis or sacroiliac joint x-ray (read 
centrally) to determine eligibility as per mNY criteria. Subjects who are mNY-negative 
may be eligible for Screening in AS0010, a double-blind, randomized, placebo-controlled 
Phase 3 study in subjects with active nr-axSpA. It is recommended to perform the 
sacroiliac joint x-ray prior to any other screening assessment to avoid repetition of 
screening assessments (applicable at sites participating in both Phase 3 studies). 
 
Change #10 
Section 5.1.1, Screening Period/Baseline, last paragraph  
Screening assessments for subjects previously screened for AS0010, who were not eligible for 
AS0010 and therefore entered Screening again for eligibility during the Screening Period of 
AS0011, must be repeated unless defined otherwise. These cross-study rescreening rules 
pertaining to laboratory testing are provided in Section 12.6 and imaging is described in 
Section 9.21. 
Has been deleted. 
 
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Clinical Study Protocol 
Bimekizumab 
AS0011 
 
 
 
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Change #11 
Section 5.1.1, Screening Period/Baseline 
The following sections have been added. 
5.1.1.1 Within-study rescreening/retesting requirements 
Rules for rescreening or repetition of screening tests within the study are listed below: 
• Subjects who fail to meet the eligibility criteria for BASDAI, spinal pain, PHQ-9, eC-SSRS, 
or the TB questionnaire are not allowed to be rescreened. 
The Medical Monitor must be contacted for confirmation of rescreening/retesting in all other 
cases. 
• Subjects who initially fail to meet selected eligibility criteria (eg, documented completion of 
latent tuberculosis infection [LTBI] prophylactic therapy) may be rescreened. 
• Subjects for whom eligibility assessments could not be completed as planned (eg, for 
technical reasons) within the defined Screening Period of 35 days may be rescreened.  
• Subjects with individual laboratory screening tests for which the results are exclusionary, can 
be retested.  
Of note, repetition of laboratory screening tests within the Screening Period is permitted for 
technical reasons (eg, frozen sample, expired laboratory kit) without contacting the Medical 
Monitor. 
5.1.1.2 Cross-study screening requirements 
Screening assessments for subjects previously screened for AS0010, who were not eligible for 
AS0010 based on mNY criteria and therefore entered AS0011 Screening for eligibility, must be 
repeated during the Screening Period unless defined in Table 5‒1. The Medical Monitor must be 
contacted for confirmation of the rescreening requirements in all cases. 
Table 5-1: Cross-study screening requirements 
Assessment  
Screening requirements 
Cross-study screening is not permitted in the following cases: 
BASDAI and 
spinal pain 
Screening of a subject not eligible for AS0010 who will be screened for AS0011, 
and who did not meet the related Inclusion Criteria in AS0010. 
PHQ-9, eC-SSRS, 
TB questionnaire 
(Q1) 
Screening of a subject not eligible for AS0010 who will be screened for AS0011, 
and who did not meet the related Exclusion Criteria in AS0010. 
Cross-study screening is permitted in the following cases: 
CRP 
If a subject not eligible for AS0010 will be screened for AS0011, the Screening 
CRP testing must be repeated during Screening for AS0011 only if the result is 
older than 35 days at time of randomization at Baseline (Section 12.6). 
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Bimekizumab 
AS0011 
 
 
 
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Table 5-1: Cross-study screening requirements 
Assessment  
Screening requirements 
Cross-study screening is not permitted in the following cases: 
All safety 
laboratory 
assessments 
If a subject not eligible for AS0010 will be screened for AS0011, the Screening 
safety laboratory testing (hematology, biochemistry, urinalysis, urine drug 
screen, pregnancy testing as applicable, HIV, Hepatitis B and C, and IGRA TB 
testing) and HLA-B27 testing must be repeated only during Screening for 
AS0011 if the results are older than 35 days at time of randomization at Baseline 
(Section 12.6). 
Anterior posterior 
pelvis x-ray 
The following will be accepted to qualify subjects with AS for this study: 
Anterior posterior pelvis x-ray centrally read for AS0010 and determined to be 
modified New York Criteria positive (+mNY); neither the x-ray nor the reading 
will be repeated (Section 9.20). The central imaging reader needs to be informed 
by the site about screening activities in order to transfer and confirm eligibility 
for the switch from AS0010 to AS0011. 
AS=ankylosing spondylitis; BASDAI=Bath Ankylosing Spondylitis Disease Activity Index; CRP=C-reactive 
protein; eC-SSRS=electronic Columbia-Suicide Severity Rating Scale; HIV=human immunodeficiency virus; 
HLA-B27=human leukocyte antigen B27; IGRA=Interferon-Gamma Release Assay; mNY=modified New 
York; PHQ-9=Patient Health Questionnaire 9; Q=question; TB=tuberculosis 
 
Change #12 
Section 5.1.2.1, Double-Blind Treatment Period, paragraph 3 
Visit windows of ±3 days are allowed from the first dose at all visits through Week 16. The visit 
window is relative to the Baseline Visit, not the previous study visit. The time between doses 
should be ≥25 days and ≤31 days.  
Has been changed to: 
Visit windows of ±3 days are allowed from the first dose at all visits through Week 16. The visit 
window is relative to the Baseline Visit, not the previous study visit. The time between doses 
should be ≥25 days and ≤31 days. When applying the allowed visit windows, it must be 
ensured that the time between these 2 visits does not exceed the allowed time between 
doses. 
 
Change #13 
Section 5.1.2.2, Maintenance Period, paragraph 3 
Visit windows of ±4 days are allowed for all visits after Week 16. The time between doses 
during the Maintenance Period should be ≥24 days and ≤32 days.  
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Clinical Study Protocol 
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AS0011 
 
 
 
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Has been changed to: 
Visit windows of ±4 days are allowed for all visits after Week 16. The time between doses 
during the Maintenance Period should be ≥24 days and ≤32 days. When applying the allowed 
visit windows, it must be ensured that the time between these 2 visits does not exceed the 
allowed time between doses. 
 
Change #14 
Section 5.1.3, Nonbiologic rescue therapy 
The entire section has been deleted from Section 5 and merged with Table 7-2. Subsequent 
sections have been re-numbered and in-text references were updated. 
 
Change #15 
Section 5.1.5, Study duration per subject, bullet #1 
• Screening Period: ≥14 days to ≤35 days 
Has been changed to: 
• Screening Period: minimum duration of approximately 14 days (unless a screenfailed 
subject from AS0010 will be screened in AS0011) to ≤35 days 
 
Change #16 
Section 5.1.6, Planned number of subjects and site(s) 
Approximately 300 subjects will be randomly assigned in a 2:1 ratio to the following treatment 
groups: bimekizumab 160mg sc Q4W (200 subjects) or placebo sc Q4W (100 subjects). The 
planned number of study sites is approximately 85.  
Has been changed to: 
Approximately 300 subjects will be randomly assigned in a 2:1 ratio to the following treatment 
groups: bimekizumab 160mg sc Q4W (200 subjects) or placebo sc Q4W (100 subjects). The 
planned number of study sites is approximately 85 95.  
 
Change #17 
Section 5.2, Table 5-2, Schedule of assessments, footnotes n and q  
n 
If a subject has had a recent x-ray of the chest within 3 months prior to the Screening Visit, it 
may be used as the Screening chest x-ray. The chest x-ray has to be read by a pulmonologist 
and any significant finding is exclusionary. Any findings suggestive of active TB are 
exclusionary. 
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q 
Sacroiliac joint and spine MRIs will be performed for subjects participating in the MRI 
substudy. Baseline sacroiliac joint and spine MRIs should be performed after confirmation of 
eligibility based on screening assessments for the study and before the first dose of IMP. If 
preferred, the sacroiliac joint and spine MRIs can be performed prior to the actual Baseline 
Visit. Further sacroiliac joint and spine MRIs will be performed at Weeks 16 and 52, within a 
window of ±5 days for sacroiliac joint MRI-positive subjects at Baseline participating in the 
substudy. 
Has been changed to: 
n 
If a subject has had a recent x-ray of the chest within 3 months prior to the Screening Visit, it 
may be used as the Screening chest x-ray. The chest x-ray has to be read by a pulmonologist 
and any significant finding is exclusionary. Any findings suggestive of active TB are 
exclusionary. 
q 
Sacroiliac joint and spine MRIs will be performed for subjects participating in the MRI 
substudy. Baseline sacroiliac joint and spine MRIs should be performed after confirmation of 
eligibility based on screening assessments for the study and before the first dose of IMP. If 
preferred, The sacroiliac joint and spine MRIs can be performed at Baseline or prior to the 
actual Baseline Visit. Further sacroiliac joint and spine MRIs will be performed at Weeks 16 
and 52, within a window of ±5 days for all subjects participating in the substudy. 
 
Change #18 
Section 6.1, Inclusion criteria 1 and 2 
1. An Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved written 
Informed Consent form is signed and dated by the subject or legal representative. 
2. Subject/legal representative is considered reliable and capable of adhering to the protocol 
(eg, able to understand and complete diaries), visit schedule, or medication intake according 
to the judgment of the Investigator. 
Have been changed to: 
1a. An Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved written 
Informed Consent form is signed and dated by the subject or legal representative. 
2a. Subject/legal representative is considered reliable and capable of adhering to the protocol 
(eg, able to understand and complete diaries), visit schedule, or medication intake according 
to the judgment of the Investigator. 
 
Change #19 
Section 6.2, Exclusion criteria #3 and #17 
3. Subject previously participated in another study of a medication (systemic) under 
investigation within the 12 weeks or at least 5 half-lifes prior to the Screening Visit, 
whichever is greater, or is currently participating in another study of a medication (systemic) 
under investigation, with the exception of subjects who were screen failures in AS0010. 
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Bimekizumab 
AS0011 
 
 
 
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17. Subject has a diagnosis of inflammatory conditions other than AS, including but not limited 
to rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, and reactive arthritis. 
Subjects with a diagnosis of Crohn’s disease, ulcerative colitis, or other IBD are allowed as 
long as they have no active symptomatic disease at Screening or Baseline. 
Has been changed to: 
3a. Subject previously participated in another study of a medication (systemic) under 
investigation within the 12 weeks or at least 5 half-lifes prior to the Screening Baseline Visit, 
whichever is greater, or is currently participating in another study of a medication (systemic) 
under investigation, with the exception of subjects who were screen failures in AS0010. 
17a. Subject has a diagnosis of inflammatory conditions other than AS, including but not limited 
to psoriatic arthritis, rheumatoid arthritis, sarcoidosis, systemic lupus erythematosus, and 
reactive arthritis. Subjects with a diagnosis of Crohn’s disease, ulcerative colitis, or other 
IBD are allowed as long as they have no active symptomatic disease at Screening or 
Baseline. 
 
Change #20 
Section 6.3.1, Potential drug-induced liver injury IMP discontinuation criteria 
Subjects with potential drug-induced liver injury (PDILI) must be assessed to determine if IMP 
must be discontinued. In addition, all concomitant medications and herbal supplements that are 
not medically necessary should also be discontinued.  
The PDILI criteria below require immediate and permanent discontinuation of IMP for subjects 
with either of the following:  
• ALT or AST ≥8x ULN  
• ALT or AST ≥3xULN and coexisting total bilirubin ≥2xULN  
The PDILI criterion below requires immediate discontinuation of IMP for:  
• Subjects with ALT or AST ≥3xULN who exhibit temporally associated symptoms of 
hepatitis or hypersensitivity. Hepatitis symptoms include fatigue, nausea, vomiting, right 
upper quadrant pain or tenderness. Hypersensitivity symptoms include fever (without clear 
alternative cause), rash, or eosinophilia (ie, >5%).  
… 
Evaluation of PDILI must be initiated as described in Section 12.6.1 with repeat tests performed 
in 2 weeks. Upon re-test, if ALT or AST values have reduced to <5xULN, the subject can 
continue with the study. However, if ALT or AST remains ≥5xULN and <8xULN after re-test, 
IMP should be temporarily withheld and subject should undergo a repeat test in 2 weeks. If ALT 
or AST values remain ≥5xULN even after the second re-test, then the subject should be 
permanently withdrawn from IMP and should be followed for possible PDILI.  
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Has been changed to: 
Subjects with potential drug-induced liver injury (PDILI) must be assessed to determine if IMP 
must be discontinued. In addition, all concomitant medications and herbal supplements that are 
not medically necessary should also be discontinued.  
The PDILI criteria below require immediate and permanent discontinuation of IMP for subjects 
with either of the following:  
• ALT or AST ≥8x ULN  
• ALT or AST ≥3xULN and coexisting total bilirubin ≥2xULN  
The PDILI criterion below requires immediate discontinuation of IMP for:  
• Subjects with ALT or AST ≥3xULN who exhibit temporally associated symptoms of 
hepatitis or hypersensitivity. Hepatitis symptoms include fatigue, nausea, vomiting, right 
upper quadrant pain or tenderness. Hypersensitivity symptoms include fever (without clear 
alternative cause), rash, or eosinophilia (ie, >5%).  
… 
Evaluation of PDILI must be initiated as described in Section 12.6.1 with repeat tests performed 
in 2 weeks. Upon re-test, if ALT or AST values have reduced to <5xULN, the subject can 
continue with the study. However, if ALT or AST remains ≥5xULN and <8xULN after re-test, 
IMP should be temporarily withheld and subject should undergo a repeat test in 2 weeks. If ALT 
or AST values remain ≥5xULN even after the second re-test, then the subject should be 
permanently withdrawn immediately discontinued from IMP and should be followed for 
possible PDILI. 
 
Change #21 
Section 7.1, Description of investigational medicinal products, first bullet 
• 
 
 
 
Has been changed to: 
• 
 
 
 
 
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Change #22 
Section 7.8, Concomitant medications/treatments, paragraph 2 
The following sentence has been added. 
Medications listed in Table 7‒2 are prohibited, restricted, or used as nonbiologic rescue 
therapy. 
 
Change #23 
Section 7.8, Concomitant medications/treatments, paragraph 2 
Table 7‒2 has been amended to include exclusionary and nonbiologic rescue therapy.  
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Bimekizumab 
AS0011 
 
 
 
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Table 7-2: Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
Analgesics 
• 
Acetaminophen/ 
paracetamol 
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Stable dose/regimen permitted  
Ad hoc/PRN/“as needed use” 
permitted, but: 
No ad hoc/PRN/“as needed use” 
in the 24h prior to any study visit 
Ad hoc/PRN/“as needed use” permitted, but: 
No ad hoc/PRN/“as needed use” in the 24h prior to 
any study visit 
 
NSAID/COX-2 inhibitors  
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Stable dose/ regimen permitted 
No change until Week 20 Visit 
Nonbiologic rescue therapy will be at the 
Investigator’s discretion with the following options for 
symptoms: 
• 
For subjects taking an NSAID/COX-2 inhibitor 
dosing can be optimized; a change can be made to 
a different NSAID/COX-2 inhibitor; changes 
from an NSAID to a COX-2 inhibitor or from a 
COX-2 inhibitor to an NSAID are also permitted 
up to the maximum approved or tolerated dose, 
whichever is lower. Only 1 NSAID/COX-2 
inhibitor may be taken at a given time. 
• 
For subjects not taking NSAID/COX-2 inhibitors 
either 1 NSAID, or 1 COX-2 inhibitor can be 
initiated, up to the maximum approved or 
tolerated dose, whichever is lower. Only 
1 NSAID/COX-2 inhibitor may be taken at a 
given time. 
• 
For subjects who cannot take NSAIDs/COX-2 
inhibitors, topical NSAIDs are also a potential 
nonbiologic rescue therapy in regions where they 
are approved, up to the maximum approved or 
tolerated dose, whichever is lower.  
Mild potency opioids permitted 
only: 
• 
Tramadol/any dose up to 
maximum approved dose 
• 
Codeine/only <90mg of 
codeine per dosage unit 
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Dosing/schedule should remain 
stable for the first 20 weeks of 
the study 
Prohibited for rescue therapy 
 
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Table 7-2: Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
Oral corticosteroids/average daily 
dose of ≤10mg/day prednisone or 
equivalent 
Any change in dose/dose 
regimen within 14 days 
prior to BL 
Permitted, but: 
• 
No steroid bursts/tapers 
• 
No increase in steroid 
dosing 
• 
No initiation of steroids 
until the Week 20 Visit 
Prohibited for rescue therapy 
Topical corticosteroids 
None 
Permitted 
Not applicable 
Corticosteroids: 
• 
Intramuscular 
• 
Intravenous 
• 
Intra-articular  
• 
Bursal 
 
Use within 28 days prior to 
BL 
Prohibited unless used as rescue 
therapy from Week 20 or later 
Nonbiologic rescue therapy will be at the 
Investigator’s discretion with the following options for 
symptoms: 
• 
Sacroiliac joint steroid injection(s), either 
unilateral or bilateral. 
For non-axial symptoms: 
• 
One peripheral joint (or bursa) may be injected 
with a steroid at or after any visit where 
nonbiologic rescue therapy eligibility is assessed; 
however, the same joint may not be injected more 
than once during the study and should not be 
injected within 4 weeks of a sacroiliac joint 
injection(s). 
Intra-articular hyaluronic acid 
Use within 8 weeks prior 
to the BL Visit or during 
the study 
Prohibited 
Not applicable 
Any established antidepressant 
regimen 
Any change in dose/dose 
regimen within 8 weeks 
prior to BL 
Permitted 
Not applicable 
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Table 7-2: Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
csARDs/formerly known as 
DMARDs 
 
 
 
• 
Azathioprine 
• 
Cyclosporine 
• 
Cyclophosphamide 
• 
Mycophenolic acid 
• 
Mycophenylate mofetil 
• 
Any other small molecule 
DMARDs 
Use within 8 weeks prior 
to BL 
Prohibited 
Prohibited for rescue  
• 
Methotrexate (MTX) 
 
Use within 12 weeks prior 
to BL unless Inclusion 
Criterion #9 is met 
Permitted 
MTX (≤25mg/week) 
For non-axial symptoms: 
• 
MTX may be added or increased to a maximum 
dose of 25mg/week, or the maximum tolerated 
dose, whichever is lower, in accordance with local 
standard of care. The route of administration may 
be changed from oral to sc or from sc to oral, at 
any visit at Week 20 or later. It is strongly 
recommended that subjects taking MTX are also 
taking folic acid supplementation. 
• 
Leflunomide (LEF) 
Use in the 6 months prior 
to the BL Visit (unless a 
cholestyramine washout 
has been performed; in 
which case, use up to 
28 days prior to the BL 
Visit is acceptable) unless 
Inclusion Criterion 
Criterion #9 is met 
Permitted 
LEF (≤20mg/day or an average 
of 20mg/day if not dosed daily) 
For non-axial symptoms: 
• 
Leflunomide may be given at a maximum dose of 
20mg/day (or an average of 20mg/day if not 
dosed daily), or the maximum tolerated dose, 
whichever is lower.  
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Table 7-2: Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
• 
Hydroxychloroquine (HCQ) 
(and other anti-malarials) 
• 
Sulfasalazine (SSZ) 
• 
Apremilast 
 
Use within 8 weeks prior 
to BL unless Inclusion 
Criterion #10 is met 
Permitted 
For non-axial symptoms: 
• 
HCQ may be added or increased to a maximum 
dose of 400mg/day or the maximum tolerated 
dose, whichever is lower. Other anti-malarials 
may be used in accordance with local standard of 
care. 
• 
SSZ may be added or increased up to a maximum 
dose of 3g/day (up to 4g/day if in accordance with 
local standard of care), or the maximum tolerated 
dose, whichever is lower.  
• 
Apremilast may be given at a maximum dose of 
60mg/day and dosed as per Investigator’s 
discretion or local label. 
Combination DMARDs are allowed except that LEF 
and MTX may not be given together. 
JAK inhibitors 
 
 
 
• 
Eg, tofacitinib 
• 
Upadacitinib 
Use within 8 weeks prior 
to BL 
Prohibited 
Not applicable 
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Table 7-2: Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
Biologic DMARDs 
 
 
 
TNFα inhibitors: 
• 
Infliximab (IFX) 
• 
Golimumab (GOL) 
• 
Certolizumab pegol (CZP) 
• 
Adalimumab (ADA) 
• 
Etanercept (ETN) 
• 
Biosimilar versions of any 
TNFα inhibitor 
For IFX, ADA, GOL, and 
CZP, any use within the 
12 weeks prior to the BL 
Visit 
For ETN, use within the 
28 days prior to the BL 
Visit 
Any use of >1 TNFα in the 
history 
Subjects not meeting 
Inclusion Criterion #11. 
Prohibited 
Not applicable 
Other biologics: 
• 
Abatacept 
Any use within 12 weeks 
prior to BL 
Prohibited 
Not applicable 
• 
Alefacept 
 
 
• 
Efalizumab 
 
 
• 
Guselkumab 
 
 
• 
Sarilumab 
 
 
• 
Sirukumab 
 
 
• 
Tocilizumab 
 
 
• 
Others in development 
targeting IL-6 or IL-6R 
 
 
• 
Ustekinumab 
 
Any use within 24 weeks 
prior to BL 
Prohibited 
Not applicable 
• 
Tildrakizumab 
Any use within 4 months 
prior to BL 
Prohibited 
Not applicable 
• 
Risankizumab 
Any use within 5 months 
prior to BL 
Prohibited 
Not applicable 
• 
Briakinumab 
 
Any use within 6 months 
prior to BL 
Prohibited 
Not applicable 
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Table 7-2: Exclusionary, concomitant, and rescue medication 
Drug class/dose 
Exclusion criteria 
Study visits/during the 
study 
Nonbiologic rescue therapy as add-on therapy 
to bimekizumab from Week 20 or latera 
• 
Rituximab (incl. biosimilars), 
ocrelizumab 
Any use within 12 months 
prior to BL 
Prohibited 
Not applicable 
Anti-IL-17 therapy: 
• 
Bimekizumab 
• 
Secukinumab 
• 
Ixekizumab 
• 
Brodalumab 
• 
Others in development 
Any exposure history 
Prohibited 
Not applicable 
BL=Baseline; ADA=adalimumab; COX-2=cyclooxygenase 2; csARD=conventional synthetic antirheumatic drug; CZP=certolizumab pegol; 
DMARD=disease-modifying antirheumatic drug; ETN=etanercept; GOL=golimumab; h=hour; HCQ=hydroxychloroquine; IFX=infliximab; JAK=Janus 
kinase; LEF=leflunomide; IL=interleukin; MTX=methotrexate; NSAID=nonsteroidal anti-inflammatory drug; PRN=as needed; sc=subcutaneous; 
SSZ=sulfasalazine; TNFα=tumor necrosis factor alpha 
a 
Note: any medication not listed here for rescue therapy must be approved by the Medical Monitor prior to starting that medication. 
 
 
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Change #24 
Section 7.8.1, Permitted concomitant treatments (medications and therapies) 
The following paragraphs have been moved to Table 7‒2. 
Subjects are allowed to use acetaminophen/paracetamol as needed except that PRN/as needed 
doses are not permitted within 24 hours before a study visit where efficacy assessments are 
performed. 
Mild potency opioids are permitted during the study and the dosing/schedule should remain 
stable for the first 16 weeks of the study, but are not permitted as nonbiologic rescue therapy (see 
Section 5.1.3). 
No steroid bursts/tapers, increase in steroid dosing or initiation of steroids are permitted during 
the study. 
Subjects are permitted to decrease NSAID/COX-2 medications, analgesics (including opioids), 
DMARD(s) and/or oral corticosteroids and/or alter their regimen only at/after the Week 20 Visit 
except for reasons of intolerance/AEs/side effects. 
Subjects who are receiving an established antidepressant regimen should be on a stable dose of 
the antidepressant for 8 weeks prior to Baseline. 
The following paragraph has been changed to: 
Whenever possible, physical therapy/physiotherapy/non-medication/complementary and 
alternative treatment(s) (including traditional Chinese medications) of AS should remain stable 
through the Week 16 20 Visit.  
The following paragraph has been deleted: 
Subjects may be withdrawn from IMP at any time and continue treatment using other treatment 
options per the Investigator’s discretion, as described in the Withdrawal criteria Section 6.3. 
 
Change #25 
Section 7.8.2, Prohibited concomitant treatments (medications and therapies) 
Medications listed in Table 7‒2 are prohibited or restricted as follows: 
Has been changed to: 
Prohibited concomitant treatments are described in Table 7‒2. 
 
Change #26 
Section 7.8, Concomitant medications/treatments 
The following changes have been made and are included in Table 7‒2. 
• The dosing/schedule of mild potency opioids should remain stable for the first 16 20 weeks 
of the study 
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• Any change in dose/dose regimen of oral corticosteroids within 14 days prior to BL is 
exclusionary. 
• Intramuscular, intravenous, intra-articular, and bursal corticosteroids use is prohibited unless 
used as rescue therapy. 
• Any use of >1 TNFα in the history is exclusionary. 
• Subjects not meeting Inclusion Criterion #11 are excluded. 
• Apremilast may be given at a maximum dose of 60mg/day and dosed as per Investigator’s 
discretion or local label. 
 
Change #27 
Section 7.8.2, Prohibited concomitant treatments (medications and therapies), Table 7-2 
The outdated Table 7‒2 has been deleted. 
 
Change #28 
Section 7.8.3, Nonbiologic rescue therapy 
The section has been moved from Section 5.1.3 to Section 7.8. The following text has been 
added: 
Nonbiologic rescue therapy will be at the Investigator’s discretion as add-on therapy to 
bimekizumab at any time from Week 20 or later as described in Table 7‒2. 
 
Change #29 
Section 8, Study procedures by visit, paragraph 2 
Visit windows are ±3 days from Baseline (Day 1, first dose of IMP) at all visits through the 
Week 16 Visit and ±4 days from all visits thereafter. For the SFU Visit (20 weeks after the final 
dose), the visit should occur no more than 3 days prior to the scheduled visit date and within 
7 days after the scheduled visit date (-3 days/+7 days). The minimum amount of time between 
bimekizumab doses should be no less than 25 days and no more than 31 days from Baseline to 
Week 16 and 24 to 32 days thereafter.  
Has been changed to: 
Visit windows are ±3 days from Baseline (Day 1, first dose of IMP) at all visits through the 
Week 16 Visit and ±4 days from all visits thereafter. For the SFU Visit (20 weeks after the final 
dose), the visit should occur no more than 3 days prior to the scheduled visit date and within 
7 days after the scheduled visit date (-3 days/+7 days). The minimum amount of time between 
bimekizumab doses should be no less than 25 days and no more than 31 days from Baseline to 
Week 16 and 24 to 32 days thereafter. When applying the allowed visit windows, it must be 
ensured that the time between these 2 visits does not exceed the allowed time between 
doses. 
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Change #30 
Section 8.1, Screening Visit (Visit 1), paragraph 1  
The Screening Period will last for a minimum of 14 days and up to a maximum of 35 days. 
Has been changed to: 
The Screening Period will last for a minimum of approximately 14 days (unless a screenfailed 
subject from AS0010 will be screened in AS0011) and up to a maximum of 35 days. 
The following text has been added. 
An overview on rescreening/retesting requirements is provided in Section 5.1.1.1 and 
Section 5.1.1.2. 
 
Change #31 
Section 8.1, Screening Visit (Visit 1), bullet 18  
Obtain a chest x-ray, unless one has been obtained within 3 months prior to the Screening Visit. 
The chest x-ray must be read by a qualified radiologist and/or pulmonary physician and any 
significant finding is exclusionary. Any findings suggestive of active TB are exclusionary. 
Has been changed to: 
Obtain a chest x-ray, unless one has been obtained within 3 months prior to the Screening Visit. 
The chest x-ray must be read by a qualified radiologist and/or pulmonary physician and any 
significant finding is exclusionary. Any findings suggestive of active TB are exclusionary. 
 
Change #32 
Section 9.7, MOS-12, paragraph 1, second sentence 
The frequency with which each problem has been experienced during the previous 4 weeks is 
rated on a 6-point scale ranging from “none of the time” to “all of the time,” except sleep 
quantity, which is reported in hours. 
Has been changed to: 
The frequency with which each problem has been experienced during the previous 4 weeks is 
rated on a 5-point scale ranging from “none of the time” to “all of the time,” except sleep 
quantity, which is reported in hours. 
 
Change #33 
Section 9.19, PHQ-9 
Has been moved from Section 9.19 to Section 12.7.7 without any content change. 
 
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Change #34 
Section 9.19, Occurrence of extra-articular manifestations 
Information regarding dactylitis, PSO, uveitis, and IBD occurrences during the study will be 
captured as AEs. Enthesitis will be assessed regularly via the MASES performed at site visits as 
specified in Table 5-2.  
Has been changed to: 
Information regarding dactylitis, PSO, uveitis, and IBD occurrences events during the study will 
be captured as AEs. Enthesitis will be assessed regularly via the MASES performed at site visits 
as specified in Table 5-2.  
 
Change #35 
Section 9.20.1, Sacroiliac joint x-ray (AP Pelvis Joint Film for modified New York Criteria, 
paragraph 2, bullet 1 
• Anterior posterior pelvis x-ray centrally read for one of the Phase 3 studies AS0010 or 
AS0011 and determined to be modified New York Criteria positive (+mNY); neither the 
reading nor the x-ray will be repeated. 
Has been changed to: 
• Anterior posterior pelvis x-ray centrally read for one of the Phase 3 studies AS0010 or 
AS0011 and determined to be modified New York Criteria positive (+mNY); neither the 
reading x-ray nor the x-ray reading will be repeated.  
 
Change #36 
Section 9.20.3, Sacroiliac joint and spine MRI assessment substudy, paragraphs 1, 2, and 3 
While radiography can detect chronic bony changes (eg, sclerosis, erosions, bridging, and 
ankyloses), structural changes generally occur slowly and x-rays are insensitive; therefore, 
changes are difficult to detect in the relatively short duration of a randomized clinical study. 
Unlike radiography, MRI can be used to visualize inflammation in the sacroiliac joints and spine 
in addition to structural lesions. Inflammation of the sacroiliac joints and spine is a key feature of 
axSpA that is potentially amenable to treatment with bimekizumab. If bimekizumab is effective, 
it is expected that reduction in inflammation in the sacroiliac joints and spine can be detected 
using MRI within the 52-week Treatment Period of this study. Recently, a Danish study 
demonstrated significant changes in in ASspiMRI-a (Berlin modification) and SPARCC MRI 
assessed inflammation scores and in SPARCC MRI-assessed erosion scores within 12 weeks 
after initiation of adalimumab (see below for further description of these MRI scoring methods). 
The researchers concluded that MRI-assessed structural lesions change rapidly and may have 
value for assessing the effects of disease-modifying treatment in clinical trials (Pedersen et al, 
2016). 
... 
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Magnetic resonance imaging of the spine and sacroiliac joints will be performed in a substudy 
with approximately 15% of subjects at Baseline after confirmation of eligibility based on 
screening assessments and before the first dose of IMP. If needed, the sacroiliac joint and spine 
MRIs can be performed prior to the actual Baseline Visit after confirmation of eligibility based 
on Screening assessments. 
... 
A central reader will assess the Baseline MRIs to identify MRI-positive subjects as per the 
OMERACT criteria. Further MRIs of the spine and sacroiliac joint will be performed at Week 16 
and Week 52 within a window of ±5 days only for those subjects who were MRI positive in the 
sacroiliac joint MRI at Baseline, and will be centrally read. 
Has been changed to: 
While radiography can detect chronic bony changes (eg, sclerosis, erosions, bridging, and 
ankyloses), structural changes generally occur slowly and x-rays are insensitive; therefore, 
changes are difficult to detect in the relatively short duration of a randomized clinical study. 
Unlike radiography, MRI can be used to visualize active inflammation in the sacroiliac joints 
and spine in addition to structural lesions. Inflammation of the sacroiliac joints and spine is a key 
feature of axSpA that is potentially amenable to treatment with bimekizumab. If bimekizumab is 
effective, it is expected that reduction in inflammation in the sacroiliac joints and spine can be 
detected using MRI within the 52-week Treatment Period of this study. Recently, a Danish study 
demonstrated significant changes in in ASspiMRI-a (Berlin modification) and SPARCC MRI 
assessed inflammation scores and in SPARCC MRI-assessed erosion scores within 12 weeks 
after initiation of adalimumab (see below for further description of these MRI scoring methods). 
The researchers concluded that MRI-assessed structural lesions change rapidly and may have 
value for assessing the effects of disease-modifying treatment in clinical trials (Pedersen et al, 
2016). In this study, MRI changes will be evaluated in the sacroiliac joint and spine to 
evaluate the effect of bimekizumab on objective signs of inflammation through the 
SPARCC and ASspiMRI scores as outlined below. In addition, exploratory evaluation of 
other chronic MRI features, such as erosions and fatty lesions, will be performed as 
indicators of disease modification associated with structural disease progression 
(Baraliakos et al, 2014). 
... 
Magnetic resonance imaging of the spine and sacroiliac joints will be performed for consenting 
subjects in the MRI substudy after confirmation of eligibility based on screening assessments 
and before the first dose of IMP. If needed, the sacroiliac joint and spine MRIs can be performed 
at Baseline or prior to the actual Baseline Visit after confirmation of eligibility based on 
Screening assessments. 
A central reader will assess the Baseline MRIs to identify MRI-positive subjects as per the 
OMERACT criteria. Further MRIs of the spine and sacroiliac joint for MRI-positive and 
MRI-negative subjects will be performed at Week 16 and Week 52 within a window of ±5 days 
for subjects participating in the MRI substudy. All MRIs will be centrally read. 
Refusal to participate in the substudy will not affect a subject’s opportunity to participate 
in the main study. 
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Change #37 
Section 10.2, Pharmacogenomic variables, paragraph 3, sentence 2 
...Candidate biomarker evaluations may include, but are not limited to, IL-17A/IL17-F pathway 
signaling and AS biology (eg, IL-17A, IL-17F, IL-23, IL-6, tumor necrosis factor, dendritic cell-
specific transmembrane protein, and circulating osteoclast precursors). ... 
Has been changed to: 
...Candidate biomarker evaluations may include, but are not limited to, IL-17A/IL-17F pathway 
signaling and AS axSpA biology (eg, IL-17A, IL-17F, IL-23, IL-6, tumor necrosis factor, 
dendritic cell-specific transmembrane protein, and circulating osteoclast precursors). ... 
 
Change #38 
Section 12.2, Pregnancy 
Should a subject become pregnant while participating in the study, the subject may be offered the 
option to enroll in a separate observational pregnancy follow-up study sponsored by UCB and 
conducted independently from AS0011. If the study is available locally, the AS0011 Investigator 
will be provided with locally approved information about the observational pregnancy follow-up 
study to inform the subject at the time the pregnancy is reported. Participation in this separate 
study will be voluntary and will not impact the therapeutic management of the subject nor 
interfere with termination and follow-up procedures as described in protocol AS0011. 
This paragraph has been deleted. 
 
Change #39 
Section 12.6, Laboratory measurements, paragraph 1 and bullets 
Clinical laboratory assessments consist of biochemistry, hematology, urinalysis, and pregnancy 
tests (serum or urine) (Table 12‒2). A centralized laboratory will be used to supply all laboratory 
test supplies and analyze all blood and urine samples (except the urine pregnancy test). Any 
unscheduled laboratory testing should also be collected using the central laboratory (with the 
exception of urgent safety laboratory measurements which should be performed locally and 
centrally simultaneously). Testing to exclude hepatitis B, hepatitis C, and HIV (see Exclusion 
Criterion #12, Section 6.2) will be performed at Screening in addition to those measurements 
listed in Table 12‒2. A urine dipstick will be used for pregnancy testing. Rescreening 
requirements pertaining to laboratory assessments are summarized below: 
• For CRP: If a subject will be rescreened for AS0011, the Screening CRP testing does not 
have to be repeated during Screening for AS0011 if the result is not older than 35 days at 
time of randomization at Baseline, otherwise, the CRP must be repeated. 
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• For all safety laboratory assessments: If a subject from AS0010 will be rescreened for 
AS0011, the Screening safety laboratory testing (hematology, biochemistry, urinalysis, urine 
drug screen, pregnancy testing as applicable, and IGRA TB testing) does not have to be 
repeated during Screening for AS0011 if the results are not older than 35 days at time of 
randomization at Baseline. Otherwise, if the results are older than 35 days, these tests must 
be repeated. 
Has been changed to: 
Clinical laboratory assessments consist of biochemistry, hematology, urinalysis, and pregnancy 
tests (serum or urine) (Table 12‒2). A centralized laboratory will be used to supply all laboratory 
test supplies and analyze all blood and urine samples (except the urine pregnancy test). Any 
unscheduled laboratory testing should also be collected using the central laboratory (with the 
exception of urgent safety laboratory measurements which should be performed locally and 
centrally simultaneously). Testing to exclude hepatitis B, hepatitis C, and HIV (see Exclusion 
Criterion #12, Section 6.2) will be performed at Screening in addition to those measurements 
listed in Table 12‒2. A urine dipstick will be used for pregnancy testing. Rescreening 
requirements pertaining to laboratory assessments are summarized below: 
Rescreening and retesting rules are provided in Section 5.1.1.1 and Section 5.1.1.2. 
• For CRP: If a subject will be rescreened for AS0011, the Screening CRP testing does not 
have to be repeated during Screening for AS0011 if the result is not older than 35 days at 
time of randomization at Baseline, otherwise, the CRP must be repeated. 
• For all safety laboratory assessments: If a subject from AS0010 will be rescreened for 
AS0011, the Screening safety laboratory testing (hematology, biochemistry, urinalysis, urine 
drug screen, pregnancy testing as applicable, and IGRA TB testing) does not have to be 
repeated during Screening for AS0011 if the results are not older than 35 days at time of 
randomization at Baseline. Otherwise, if the results are older than 35 days, these tests must 
be repeated. 
 
Change #40 
Section 12.6.1, Evaluation of PDILI, last paragraph 
When IMP is stopped due to PDILI (as described in Section 6.3.1), IMP must be permanently 
discontinued unless a subsequent alternative diagnosis fully explains the hepatic findings. If a 
subsequent alternative diagnosis fully explains the hepatic findings, and the requirements 
provided in Section 12.6.1.2.1 are met, rechallenge with IMP may be appropriate. 
Has been changed to:  
When IMP is stopped due to PDILI (as described in Section 6.3.1), IMP must be permanently 
discontinued unless a subsequent alternative diagnosis fully explains the hepatic findings. If a 
subsequent alternative diagnosis fully explains the hepatic findings, and the requirements 
provided in Section 12.6.1.2.1 are met, rechallenge with IMP may be appropriate. 
 
 
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Change #41 
Section 12.6.1, Evaluation of PDILI, Table 12-3 
Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
hyper-
sensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
≥3xULN 
≥2xULNb 
NA 
Hepatology consultc 
Medical Monitor must 
be notified within 
24 hours (eg, by 
laboratory alert) and 
subject discussed with 
Medical Monitor ASAP. 
Immediate, 
permanent IMP 
discontinuation. 
 
Essential: Must have 
repeat liver 
chemistry values and 
additional testing 
completed ASAP 
(see 
Section 12.6.1.3); 
recommended to 
occur at the site with 
HCP. 
Monitoring of liver chemistry 
values at least twice per week 
until values normalize, stabilize, 
or return to within baseline 
values.d 
≥3xULN 
NA 
Yes 
≥8xULN 
NA 
NA 
Need for hepatology 
consult to be discussed 
(required if ALT or AST 
≥8xULN) 
Medical Monitor must 
be notified within 
24 hours (eg, by 
laboratory alert) and 
subject discussed with 
Medical Monitor ASAP. 
Immediate, 
permanent IMP 
discontinuation 
 
≥5xULN 
(and ≥2x 
Baseline) 
and 
<8xULN  
<2xULN 
No 
Discussion with Medical 
Monitor required. 
Consider need for 
hepatology consult if 
there is no evidence of 
resolution (see Follow 
up requirements).c 
Further investigation 
– immediate IMP 
discontinuation not 
required (see 
Section 12.6.1.2). 
 
IMP discontinuation 
required if any of the 
following occur: 
Essential: Every 
attempt must be 
made to have repeat 
liver chemistry 
values and 
additional testing 
completed within 
48 hours at the site 
with HCP (see 
Section 12.6.1.3). 
Monitoring of liver chemistry 
values at least twice per week for 
2 weeks.d 
• 
Immediate IMP 
discontinuation required if 
liver chemistry values 
continue to increase. 
After 2 weeks of monitoring 
liver chemistry values: 
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Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
hyper-
sensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
• 
Subject cannot 
comply with 
monitoring 
schedule. 
• 
Liver chemistry 
values continue 
to increase 
• 
Liver chemistry 
values remain 
≥5xULN (and 
≥2x baseline) 
after 4 weeks 
of monitoring 
without 
evidence of 
resolution 
• 
ALT or AST remains 
≥5xULN <8xULN, IMP 
should be temporarily 
withheld and subject 
should undergo repeat test 
in 2 weeks. 
Continue IMP if ALT or 
AST values <5xULN; 
continue to monitor at least 
twice per week until values 
normalize, stabilize, or 
return to within baseline 
values. 
If ALT or AST remains 
≥5xULN after second re-
test, immediate, permanent 
IMP discontinuation 
required. 
Continue to monitor until values 
normalize, stabilize, or return to 
within baseline values.d 
 
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Has been changed to: 
Laboratory value 
 
Immediate 
Follow up 
ALT or AST 
Total 
bilirubin 
Symptomsa of 
hepatitis or 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
≥3xULN 
≥2xULNb 
NA 
Hepatology consultc 
Medical Monitor must 
be notified within 
24 hours (eg, by 
laboratory alert) and 
subject discussed with 
Medical Monitor ASAP. 
Need for hepatology 
consult to be discussed 
(required if ALT or AST 
≥8xULN). 
Medical Monitor must 
be notified within 
24 hours (eg, by 
laboratory alert) and 
subject discussed with 
Medical Monitor ASAP. 
Immediate permanent 
IMP discontinuation.d 
Immediate, permanent 
IMP discontinuation. 
 
Essential: Must have 
repeat liver chemistry 
values and additional 
testing completed 
ASAP (see 
Section 12.6.1.3); 
recommended to occur 
at the site with HCP. 
Monitoring of liver 
chemistry values at least 
twice per week until values 
normalize, stabilize, or 
return to within baseline 
values.e 
≥3xULN 
NA 
Yes 
≥8xULN 
NA 
NA 
≥5xULN (and 
≥2x baseline) 
and <8xULN  
<2xULN 
No 
Discussion with Medical 
Monitor required. 
Consider need for 
hepatology consult if 
there is no evidence of 
resolution (see Follow 
up requirements).c 
Further investigation – 
immediate IMP 
discontinuation not 
required (see 
Section 12.6.1.2). 
 
IMP discontinuation 
required if any of the 
following occur: 
 
• Subject cannot 
comply with 
monitoring schedule. 
Essential: Every 
attempt must be made 
to have repeat liver 
chemistry values and 
additional testing 
completed within 
48 hours at the site 
with HCP (see 
Section 12.6.1.3). 
Monitoring of liver 
chemistry values at least 
twice per week for 2 weeks.e 
• 
Immediate IMP 
discontinuation required 
if liver chemistry values 
continue to increase. 
After 2 weeks of monitoring 
liver chemistry values: 
• 
ALT or AST remains 
≥5xULN <8xULN, IMP 
should be temporarily 
withheld and subject 
should undergo repeat 
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Laboratory value 
 
Immediate 
Follow up 
ALT or AST 
Total 
bilirubin 
Symptomsa of 
hepatitis or 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
• Liver chemistry 
values continue to 
increase. 
• Liver chemistry 
values remain 
≥5xULN (and 
≥2x baseline) after 4 
weeks of monitoring 
without evidence of 
resolution. 
test in 2 weeks. 
 
Continue IMP if ALT 
or AST values 
<5xULN; continue to 
monitor at least twice 
per week until values 
normalize, stabilize, or 
return to within baseline 
values. 
 
If ALT or AST remains 
≥5xULN after second 
re-test, immediate, 
permanent IMP 
discontinuation 
required. 
Continue to monitor until 
values normalize, stabilize, 
or return to within baseline 
values.e 
 
 
 
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Change #42 
Section 12.6.1, Evaluation of PDILI, Table 12-3, footnotes 
The following footnote has been added: 
d 
Details are provided in Section 12.6.1.2. 
Subsequent footnotes have been adjusted accordingly. 
 
Change #43 
Section 12.6.1.2, Immediate action: determination of IMP discontinuation, paragraph 2 
All PDILI events require immediate action, testing, and monitoring.  
The immediate action is dependent on the laboratory values and symptoms of hepatitis or 
hypersensitivity and ranges from continuation of IMP (followed by immediate investigation) to 
immediate and permanent discontinuation (see Section 6.3.1 and Table 12‒3 for details). 
Has been changed to:  
All PDILI events require immediate action, testing, and monitoring.  
The immediate action is dependent on the laboratory values and symptoms of hepatitis or 
hypersensitivity and ranges from continuation of IMP (followed by immediate investigation) to 
immediate and permanent discontinuation (see Section 6.3.1 and Table 12‒3 for details). 
 
Change #44 
Section 12.6.1.2.1, IMP restart/rechallenge, paragraph 1 
Subjects who are immediately discontinued from IMP due to having met certain criteria for 
PDILI (as described in Section 6.3.1 and Table 12‒3), but for whom an alternative diagnosis is 
confirmed, ie, drug-induced liver injury is excluded, can rarely restart IMP. Rechallenge with 
IMP can occur only if ALL of the following requirements are met: 
Has been changed to:  
Subjects who are immediately discontinued from IMP due to having met certain criteria for 
PDILI (as described in Section 6.3.1 and Table 12‒3), but for whom an alternative diagnosis is 
confirmed, ie, drug-induced liver injury is excluded, can rarely restart IMP. Rechallenge with 
IMP can occur only if ALL of the following requirements are met at the time of the 
rechallenge: 
 
Change #45 
Section 12.7.7, PHQ-9 
The following text was moved to Section 12.7.7. 
The PHQ-9 is a multipurpose instrument for screening, diagnosing, monitoring, and measuring 
the severity of depression. The PHQ-9 scores for depression range from 0 to 27 with higher 
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scores indicating worse state. A score of 5 to 9 is considered to be minimal symptoms of 
depression. A score of 10 to 14 is considered minor depression, dysthymia, or mild major 
depression. A score of 15 to 19 is considered to indicate moderately severe major depression, 
and a score ≥20 is considered to be severe major depression.  
The PHQ-9 will be completed by the subject at the visits specified in Table 5-2.  
Refer to Section 6.3 for PHQ-9-related withdrawal criteria. 
 
Change #46 
Section 13.2, Medical and ankylosing spondylitis history 
The Investigator or designee will obtain a complete medical history and a medical history related 
to AS (including EAMs, the date of diagnosis, and past treatments for AS as part of the 
Screening assessment and include all clinically relevant past or coexisting medical conditions, 
responses to AS treatment as available, Baseline GI-related symptoms, and surgeries. Findings 
will be recorded in the eCRF. 
Has been changed to:  
The Investigator or designee will obtain a complete medical history and a medical history related 
to AS (including EAMs, the date of diagnosis, and past treatments for AS, and ASAS 
classification criteria as referenced in Section 19.1) as part of the Screening assessment and 
include all clinically relevant past or coexisting medical conditions, responses to AS treatment as 
available, Baseline GI-related symptoms, and surgeries. Findings will be recorded in the eCRF. 
 
Change #47 
Section 15.3.1, Figure 15-1, Sequential testing procedure of primary/secondary efficacy 
endpoints  
The time point (Week 16) was added to hypothesis #9 in the sequential testing procedure. 
 
Change #48 
Section 15.3.3, Subgroup analyses, bullet #3 
Subgroup analyses using descriptive statistics will be performed on the primary efficacy 
variable. The following variables for subgroup analyses will be defined:  
• ... 
• Disease duration (<2 years; ≥2 years) 
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Has been changed to:  
Subgroup analyses using descriptive statistics will be performed on the primary efficacy 
variable. The following variables for subgroup analyses will be defined:  
• ... 
• Disease duration (<5 years; ≥5 years) 
 
Change #49 
Section 16.1, Informed consent, paragraph 3  
Prior to participation in the study, the Informed Consent Form should be signed and personally 
dated by the subject, or his/her legal representative, and by the person who conducted the 
informed consent discussion (Investigator or designee). The subject or his/her legal 
representative must receive a copy of the signed and dated Informed Consent Form. As part of 
the consent process, each subject must consent to direct access to his/her medical records for 
study-related monitoring, auditing, IRB/IEC review, and regulatory inspection. 
Has been changed to:  
Prior to participation in the study, the Informed Consent Form should be signed and personally 
dated by the subject, or his/her legal representative, and by the person who conducted the 
informed consent discussion (Investigator or designee). The subject or his/her legal 
representative must receive a copy of the signed and dated Informed Consent Form. As part of 
the consent process, each subject must consent to direct access to his/her medical records for 
study-related monitoring, auditing, IRB/IEC review, and regulatory inspection. 
 
Change #50 
Section 16.2, Subject identification cards  
Upon signing the Informed Consent Form, the subject or legal representative will be provided 
with a subject identification card in the language of the subject. The Investigator will fill in the 
subject identifying information and medical emergency contact information. The Investigator 
will instruct the subject to keep the card with him/her at all times. 
Has been changed to:  
Upon signing the Informed Consent Form, the subject or legal representative will be provided 
with a subject identification card in the language of the subject. The Investigator will fill in the 
subject identifying information and medical emergency contact information. The Investigator 
will instruct the subject to keep the card with him/her at all times. 
 
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Change #51 
Section 18, References 
The following reference has been added: 
Baraliakos X, Heldmann F, Callhoff J, Listing J, Appelboom T, Brandt J, et al. Which spinal 
lesions are associated with new bone formation in patients with ankylosing spondylitis treated 
with anti-TNF agents? A long-term observational study using MRI and conventional 
radiography. Ann Rheum Dis. 2014;73:1819-25. 
The following reference has been deleted: 
Sieper J, Poddubnyy D. Axial spondyloarthritis.Lancet. 2017;1;390(10089):73-84. 
 
Change #52 
Section 19.1, ASAS Classification Criteria for axial SpA  
The following table has been added: 
Table 19-1: ASAS classification criteria for axial SpA (for subjects with chronic 
back pain of at least 3 months and age at onset <45 years) 
Imaging criteria 
ASAS clinical criteria for axial SpA 
Sacroiliitis (MRI or radiographsa) plus ≥1 SpA feature 
HLA-B27 plus ≥2 other SpA features 
SpA featuresb 
 
Inflammatory back painc  
Psoriasis 
Arthritis 
Crohn’s disease/ulcerative colitis 
Enthesitis (heel)  
HLA-B27 
Uveitis  
Elevated CRP 
Dactylitis 
 
ASAS=Assessment of SpondyloArthritis International Society; axSpA=axial spondyloarthritis; CRP=C-reactive 
protein; HLA-B27=human leukocyte antigen B27; MRI=magnetic resonance imaging; NSAID=nonsteroidal 
anti-inflammatory drug; SpA=spondyloarthritis 
a Active inflammatory lesions of sacroiliac joints with definite bone marrow oedema/osteitis suggestive of 
sacroiliitis associated with spondyloarthritis in MRI or radiographic sacroiliitis Grade 2 to 4 bilaterally or 
Grade 3 to 4 unilaterally according to modified NY criteria. For this study, only MRI will be permitted for 
study entry for the imaging criterion. 
b “Family history for SpA” and “Good response to NSAIDs” are excluded as SpA feature criteria. 
c Inflammatory back pain according to ASAS criteria for axSpA defined as the presence of 4 out of 5 of the 
following parameters: 
1. age at onset <45 years 
2. insidious onset 
3. improvement with exercise 
4. no improvement with rest 
5. pain at night (with improvement upon getting up) 
 
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19.4 
Protocol Amendment 2 
Rationale for the amendment 
The purpose of this protocol amendment is an update of Inclusion criterion #6 to reflect the 
treatment guidelines for axSpA, as presented in the recent EULAR/ASAS and ACR/SPARTAN 
guidelines. The List of Abbreviations has been updated accordingly. In addition, a minor update 
for consistency has been made. 
 
Modifications and changes 
Global changes 
No global changes have been made. 
 
Specific changes 
Change #1 
Section 6.1, Inclusion criterion #6 
6. Subjects must have at least 1 of the following: 
− Inadequate response to NSAID therapy, or  
− Intolerance to administration of at least 1 NSAID, or 
− Contraindication(s) to NSAID therapy 
Inadequate response to an NSAID is defined as lack of response for at least 4 weeks of 
continuous NSAID therapy at the highest tolerated dose of the administered NSAID or the 
lack of response to treatment with at least 2 NSAIDs at the maximum tolerated dose for at 
least 4 weeks total duration.  
Has been changed to: 
6a. Subjects had to have either failed to respond to 2 different NSAIDs given at the 
maximum tolerated dose for a total of 4 weeks or have a history of intolerance to or a 
contraindication to NSAID therapy. 
Change #2 
Section 9.15, ASDAS 
The variables related to ASDAS improvement are defined as follows: 
• ASDAS-CII: ASDAS reduction (improvement) of ≥1.1 relative to Baseline 
• ASDAS-MI: ASDAS reduction (improvement) of ≥2.0 relative to Baseline 
The ASDAS variables will be derived from assessments at the visits specified in Table 5‒2. 
 
 
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Has been changed to: 
The variable related to ASDAS improvement is defined as follows: 
• ASDAS-MI: ASDAS reduction (improvement) of ≥2.0 relative to Baseline 
The ASDAS variables will be derived from assessments at the visits specified in Table 5‒2. 
 
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19.5 
Protocol Amendment 3 
Rationale for the amendment 
The purpose of this amendment is to change the sponsor company name from “UCB Biopharma 
SPRL” to “UCB Biopharma SRL” since the name of the legal form of the entity UCB 
Biopharma has changed into “société à responsabilité limitée” abbreviated “SRL”. 
In addition, a minor correction has been made. 
Modifications and changes 
Global changes 
No global changes have been made. 
Specific changes 
Change #1 
Sponsor name on the title page in the study contact information 
Sponsor 
UCB Biopharma SPRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
Has been changed to: 
Sponsor 
UCB Biopharma SRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
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19.6 
Protocol Amendment 4 
Rationale for the amendment 
The major purpose of this protocol amendment is to update the handling of missing data for the 
statistical analysis of the primary endpoint in response to a recent agency request. The 
COVID-19-free set was added in response to industry recommendations for evaluating the 
impact of the pandemic. In addition, other previously planned supportive analyses defined in the 
SAP were added for completeness. 
Further key changes are summarized below. 
• The introduction in Section 2 presenting a high level summary of bimekizumab indications in 
development and an overview of clinical studies has been updated to reflect the latest status.  
• For some secondary and other endpoints in Section 4.2.1 and Section 4.3.1 (BASDAI, 
nocturnal spinal pain, ASQoL, SF-36, MOS12-item scale, and FACIT-Fatigue), wording 
changes have been implemented for consistency with the user manuals and to reflect precise 
description of the PRO tool and scoring (change in terminology but no change in the 
method). Similarly, corresponding small changes in Section 8 and Section 15.9.2 have been 
made for clarity and consistency with the revised description of the assessments.  
• The definition of the secondary safety variables related to SAEs and AEs leading to 
withdrawal was changed to clarify these variables are related to treatment-emergent events. 
This definition is consistent with the SAP and common practice. 
• Interim analyses as described in Section 5.1 and Section 15.8.1 have been updated to clarify 
that interim analyses will include data from the planned number of randomized study 
participants who completed the corresponding treatment period. In Section 15.8.1, the 
amendment clarifies that additional interim analyses or data cuts for regulatory purposes are 
permitted.  
• A typographical error in Table 5‒1 showing cross-study screening requirements for the 
PHQ-9, eC-SSRS, and the TB questionnaire (Q1) related criterion has been corrected.  
• In line with the Exclusion Criterion 11 regarding infections, a specific infection related 
withdrawal criterion was added to clarify that subjects with serious or recurrent infections not 
responding to standard therapies are not exposed to immunomodulatory therapies until their 
infection is resolved. This is in line with most biologic therapies, including other anti-IL17s. 
• In Table 7‒2, the section providing details for mild potency opioids has been updated to 
clarify that the listed opioids reflect examples. 
• Section 7.8.1 listing permitted concomitant treatments has been amended to enhance clarity 
on allowed medications including biologics for permanently discontinued subjects after at 
least 28 days of the final IMP dose. 
• Throughout the protocol, vital sign assessments reported as pulse and blood pressure 
measurements were replaced with “vital sign” measurements for internal consistency. This 
update does not reflect a procedural change. 
• The description of the ASQoL assessment in Section 9.2 has been amended with details 
regarding scoring.  
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• Language describing the BASFI component of the ASAS response has been updated for 
clarity to specifically mention “physical function” as opposed to “function”. The header for 
Section 9.5 was updated accordingly. 
• The presentation of the SF-36 assessment in Section 9.6 has been corrected to ensure 
consistency with the user manual and the author’s recommendation (Maruish, 2011). 
Subsequently, wording changes for consistency throughout the protocol, mainly in 
Section 4.2.1 and Section 8 have been made. 
• The presentation of the FACIT-Fatigue subscale in Section 9.10 has been corrected to ensure 
consistency with the user manual (FACIT.org). Subsequently, wording changes for 
consistency throughout the protocol, mainly in Section 4.3.1 and Section 8 have been made. 
• The proposed SPARCC and ASspiMRI scoring systems to assess the level of MRI 
inflammation in the SIJ and spine, respectively, are currently well accepted.  Methodology 
for scoring of MRI inflammation in the SIJ or spine is evolving, and the additional methods 
to evaluate the MRI inflammation data (for instance spine SPARCC) may be considered. 
Based on this approach, Section 9.20.3 has been amended accordingly. 
• With progressive development of bimekizumab and based on the ongoing review of 
emerging safety data, depression has been removed as a safety topic of interest. Nevertheless, 
depression will continue to be monitored as a safety parameter by the PHQ9 and will be 
captured via routine AE reporting during the study. This update is considered a procedural 
change. 
• Action to be taken in the event that a subject reports a pregnancy as described in Section 12.2 
has been updated for consistency with protocols in other indications. 
• Action to be taken if a subject presents with a PDILI event as described in Section 12.6.1 has 
been updated for consistency with protocols in other indications. 
• Section 15.8.2 was amended to allow other adjudication committees as necessary. 
• Study contact details have been updated to reflect recent changes.  
At the same time, a few updates including consistency changes within the bimekizumab 
program, minor corrections, the list of abbreviations, a reference has been added for the 
FACIT-Fatigue, and minor formatting changes for the purpose of clarity have been made. 
 
Modifications and changes 
Global changes 
The following change was made throughout the protocol: 
• All instances that referred to “Administer the SF-36 PCS and MCS” have been corrected 
to “Administer the SF-36 questionnaire”. 
• All instances that referred to “FACIT-F” have been corrected to “FACIT-Fatigue”, all 
instances that referred to “Administer the FACIT-F” have been corrected to “Administer 
the FACIT-Fatigue subscale” and the definition of the abbreviation was updated 
accordingly. 
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Specific changes 
Change #1 
Protocol/Amendment number details on the cover page 
Protocol Amendment 4.2 (Germany) 
Has been changed to: 
Protocol Amendment 3.2 (Germany) 
 
Change #2 
STUDY CONTACT INFORMATION 
Sponsor Study Physician 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Straße 10 
40789 Monheim am Rhein 
GERMANY 
Phone: 
 
Has been changed to: 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Straße 10 
40789 Monheim am Rhein 
GERMANY 
Phone: 
 
 
Change #3 
Section 2.2, Bimekizumab, paragraph 1, sentence 5 
Bimekizumab is being developed for the treatment of patients with inflammatory diseases such 
as PsA, psoriasis (PSO), and axSpA. 
Has been changed to: 
Bimekizumab is being developed for the treatment of patients with inflammatory diseases such 
as PsA, psoriasis (PSO), and axSpA and hidradenitis suppurativa. 
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Change #4 
Section 2.2.2.1, Completed studies, paragraph 1 
Thirteen clinical studies of bimekizumab have been completed: UP0008 in 39 subjects with mild 
to moderate plaque PSO, RA0124 in 30 healthy volunteers, PA0007 in 53 subjects with PsA, 
UP0031 in 12 healthy volunteers, UP0042 in 48 Japanese and Caucasian healthy volunteers, 
RA0123 in 159 subjects with moderate-to-severe RA, PS0010 in 250 subjects with moderate-to-
severe chronic plaque PSO and the corresponding extension study (PS0011), PS0016 in 49 
subjects with moderate-to-severe chronic plaque PSO and the corresponding extension study 
(PS0018), UC0011 in 23 subjects with moderate-to severe active ulcerative colitis, AS0008 in 
303 subjects with AS, and PA0008 in 206 subjects with PsA. 
Has been changed to: 
Thirteen Twenty clinical studies of bimekizumab have been completed: UP0008 in 39 subjects 
with mild to moderate plaque PSO, RA0124 in 30 healthy volunteers, PA0007 in 53 subjects 
with PsA, UP0031 in 12 healthy volunteers, UP0033 in 189 healthy volunteers, UP0034 in 
56 healthy volunteers, UP0042 in 48 Japanese and Caucasian healthy volunteers, UP0074 in 
37 healthy volunteers, RA0123 in 159 subjects with moderate-to-severe RA, PS0010 in 250 
subjects with moderate-to-severe chronic plaque PSO and the corresponding extension study 
(PS0011), PS0016 in 49 subjects with moderate-to-severe chronic plaque PSO and the 
corresponding extension study (PS0018), UC0011 in 23 subjects with moderate-to severe active 
ulcerative colitis, HS0001 in 90 subjects with moderate to severe hidradenitis suppurativa, 
AS0008 in 303 subjects with AS, and PA0008 in 206 subjects with PsA, PS0008 in 478 subjects 
with moderate to severe chronic plaque PSO, PS0009 in 567 subjects with moderate to 
severe chronic plaque PSO and PS0013 in 435 subjects with moderate to severe chronic 
plaque PSO. 
 
Change #5 
Section 2.2.2.2, Ongoing studies, paragraph 1 
Several additional studies of bimekizumab in subjects with AS are ongoing:  
Has been changed to: 
Several additional studies of bimekizumab in subjects with AS axSpA are ongoing:  
In addition, the following bullet has been added: 
• AS0014 is a Phase 3, open-label extension study for AS0010 and AS0011.  
 
Change #6 
Section 4.2, Secondary variables 
Section 4.2.1, Secondary efficacy variables 
• … 
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• Change from Baseline in BASDAI at Week 16  
• … 
• Change from Baseline in nocturnal spinal pain (NRS) at Week 16 
• Change from Baseline in Ankylosing Spondylitis Quality of Life (ASQoL) at Week 16  
• Change from Baseline in the Short Form 36-Item Health Survey (SF-36) physical component 
summary (PCS) at Week 16  
• … 
Section 4.2.2, Secondary safety variables 
… 
• Incidence of serious adverse events (SAEs) 
• Adverse events (AEs) leading to withdrawal from IMP 
Has been changed to: 
Section 4.2.1, Secondary efficacy variables 
• … 
• Change from Baseline in BASDAI total score at Week 16  
• … 
• Change from Baseline in nocturnal spinal pain score (NRS) at Week 16 
• Change from Baseline in Ankylosing Spondylitis Quality of Life (ASQoL) total score at 
Week 16  
• Change from Baseline in the Short Form 36-Item Health Survey (SF-36) physical component 
summary (PCS) score at Week 16  
• … 
Section 4.2.2, Secondary safety variables 
… 
• Incidence of treatment-emergent serious adverse events (SAEs) 
• Adverse events (AEs) TEAEs leading to withdrawal from IMP 
 
Change #7 
Section 4.3.1, Other efficacy variables 
• … 
• Change from Baseline in BASDAI 
• … 
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• Change from Baseline in total and nocturnal spinal pain (NRS)  
• Change from Baseline in the average of Questions 5 and 6 of the BASDAI concerning 
morning stiffness  
• … 
• Change from Baseline in the SF-36 PCS  
• Change from Baseline in the SF-36 mental component summary (MCS)  
• Change from Baseline in sleep quality (Medical Outcomes Study [MOS 12-item] scale)  
• Change from Baseline in Functional Assessment of Chronic Illness Therapy-Fatigue 
(FACIT-F)  
• Change from Baseline in ASQoL  
• … 
Has been changed to: 
• … 
• Change from Baseline in BASDAI total score  
• … 
• Change from Baseline in total and nocturnal spinal pain score (NRS)  
• Change from Baseline in the average score of Questions 5 and 6 of the BASDAI concerning 
morning stiffness  
• … 
• Change from Baseline in the SF-36 PCS score 
• Change from Baseline in the SF-36 mental component summary (MCS) score 
• Change from Baseline in sleep quality score (Medical Outcomes Study [MOS 12-item] 
scale)  
• Change from Baseline in Functional Assessment of Chronic Illness Therapy-Fatigue 
(FACIT-F)-Fatigue subscale score 
• Change from Baseline in ASQoL total score  
• … 
 
Change #8 
Section 5.1, Study description, paragraph 6, sentence 1 
Interim analyses of all available data (including efficacy, safety, and PK) will be conducted after 
all randomized subjects have completed 24 weeks and 52 weeks of treatment or have withdrawn 
from IMP or the study.  
Has been changed to: 
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Interim analyses of all available data (including efficacy, safety, and PK) will be conducted after 
all the planned number of randomized subjects have completed 24 weeks and 52 weeks of 
treatment or have withdrawn from IMP or the study.  
 
Change #9 
Section 5.1.1.2 Cross-study screening requirements 
Table 5-1: Cross-study screening requirements, fourth row, second column 
Table 5-1: 
Cross-study screening requirements 
Assessment  
Screening requirements 
… 
PHQ-9, eC-SSRS, 
TB questionnaire 
(Q1) 
Screening of a subject not eligible for AS0010 who will be screened for AS0011, 
and who did not meet the related Exclusion Criteria in AS0010. 
… 
Has been changed to: 
Table 5-1: 
Cross-study screening requirements 
Assessment  
Screening requirements 
… 
PHQ-9, eC-SSRS, 
TB questionnaire 
(Q1) 
Screening of a subject not eligible for AS0010 who will be screened for AS0011, 
and who did not meet the related Exclusion Criteria in AS0010. 
… 
 
Change #10 
Section 5.2, Schedule of study assessments 
Table 5‒2: Schedule of study assessments, 22nd row, first column 
Protocol activity 
… 
• 
FACIT-F 
… 
Has been changed to: 
Protocol activity 
… 
• 
FACIT-F-Fatigue subscale 
… 
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Change #11 
Section 6.3, Withdrawal criteria 
The following bullet has been added: 
12.  Any subject who develops a clinically important infection or recurrent infections not 
responsive to standard therapy during the study must discontinue IMP until resolution of the 
infection. The Investigator should use clinical judgement in deciding whether the subject 
should restart IMP and contact the Medical Monitor and UCB study physician to confirm the 
subject’s suitability for continued participation in the study. 
 
Change #12 
Section 7.8, Concomitant medications/treatments 
Table 7‒2: Exclusionary, concomitant, and rescue medication, fourth row, first column 
Drug class/dose 
… 
Mild potency opioids permitted 
only: 
• 
Tramadol/any dose up to 
maximum approved dose 
• 
Codeine/only <90mg of 
codeine per dosage unit 
… 
Has been changed to: 
Drug class/dose 
… 
Mild potency opioids permitted 
only eg,: 
• 
Tramadol/any dose up to 
maximum approved dose 
• 
Codeine/only <90mg of 
codeine per dosage unit 
… 
 
Change #13 
Section 7.8.1, Permitted concomitant treatments (medications and therapies) 
The following text has been added: 
Subjects are allowed to use any other medications, including biologics, after at least 28 days of 
their final dose of the IMP. This is applicable for subjects who discontinue from the study early, 
including those permanently withdrawn from IMP, or subjects who have completed the study 
treatment without entering the extension study and are in the SFU Period. 
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Change #14 
Section 8.2, Baseline (Visit 2, Day 1, first dose of IMP), last bullet  
and  
 Section 8.3.6, Week 16 (±3 days) (Visit 8), last bullet 
• Measure BP and pulse approximately 30 minutes and 1 hour after dosing. 
Has been changed to: 
• Measure BP and pulse vital signs approximately 30 minutes and 1 hour after dosing. 
 
Change #15 
Section 9.1, ASAS20, 40, ASAS 5/6 response, and ASAS-PR, third bullet point 
• Function section (represented by BASFI, Section 9.5) 
Has been changed to: 
• Physical Function section (represented measured by BASFI, Section 9.5) 
 
Change #16 
Section 9.2, ASQoL, first paragraph 
The ASQoL, a validated disease-specific 18-item questionnaire, has been developed specifically 
for measuring health-related quality of life (HRQoL) in subjects with AS (Doward et al, 2003). 
The ASQoL has been used and has shown to be responsive in axSpA (Barkham et al, 2009; 
Haibel et al, 2008). The ASQoL score ranges from 0 to 18 with a higher score indicating worse 
HRQoL.  
Has been changed to: 
The ASQoL, a validated disease-specific 18-item questionnaire, has been developed specifically 
for measuring health-related quality of life (HRQoL) in subjects with AS (Doward et al, 2003). 
The ASQoL has been used and has shown to be responsive in axSpA (Barkham et al, 2009; 
Haibel et al, 2008). The Each statement on the ASQoL is given a score ranges of 1 = Yes or 0 
= No. A score of "1" is given where the item is affirmed, indicating adverse quality of life. 
All item scores are summed to total score ranging from 0 to 18 with a higher score indicating 
worse HRQoL.  
 
Change #17 
Section 9.4, BASDAI, second paragraph 
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The BASDAI is calculated as follows:  
Has been changed to: 
The BASDAI total score is calculated as follows:  
 
Change #18 
Section 9.5, Function – BASFI, heading 
Has been changed to: 
Section 9.5, Physical Ffunction – BASFI 
 
Change #19 
Section 9.6, SF-36, paragraphs 1 and 2 
The SF-36 (Version 2, standard recall) is a 36-item generic HRQoL instrument that uses a recall 
period of 4 weeks. Items are grouped into 8 domains as follows: Physical Functioning (10 items), 
Role Physical (4 items), Bodily Pain (2 items), General Health (5 items), Vitality (4 items), 
Social Functioning (2 items), Role Emotional (3 items), Mental Health (5 items), and 1 item for 
perceived stability or change in health (Health Transition) during the last year. The concepts 
represented by these domains contribute to physical, mental, and social aspects of HRQoL. 
In addition to domain scores, the Physical Component Summary and Mental Component 
Summary scores are calculated from the 8 domains (excluding the Health Transition item). 
Component scores appreciate the impact of each domain on physical and mental health status 
(Maruish, 2011). Each of the 8 domain scores and the component summary scores range from 
0 to 100, with a higher score indicating a better health status. The 2 component summary scores 
are standardized with a mean of 50 and a standard deviation (SD) of 10 in the general 
US population.  
Has been changed to: 
The SF-36 (Version 2, standard recall) is a 36-item generic HRQoL instrument that uses a recall 
period of 4 weeks. Items are grouped into 8 domains as follows: Physical Functioning (10 items), 
Role Physical (4 items), Bodily Pain (2 items), General Health (5 items), Vitality (4 items), 
Social Functioning (2 items), Role Emotional (3 items), Mental Health (5 items), and 1 One 
additional item for perceived stability or change in asks respondents about health change 
(Health Transition) during over the last past year. The concepts represented by these domains 
contribute to physical, mental, and social aspects of HRQoL. 
In addition to domain scores, the Physical Component Summary and Mental Component 
Summary scores are calculated from the 8 domains (excluding the Health Transition item). 
Component scores appreciate the impact of each domain on physical and mental health status 
(Maruish, 2011). Each of the 8 domain scores and the component summary scores range from 
0 to 100, with a higher score indicating a better health status. The norm-based T-scores for the 
2 SF-36 component summary (PCS and MCS) and the 8 domain scores are standardized with a 
mean of 50 and a standard deviation (SD) of 10 in the general US population (Maruish, 2011). 
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An individual respondent’s score that falls outside the T-score range of 45 to 55 should be 
considered outside the average range for the US general population. When considering 
group-level data, a score below 47 should be considered indicative of impaired functioning 
within that health domain or dimension. Similar to individual respondent data, group 
mean scores of 47 or greater should be considered average or above average as compared 
to the general US population. Higher scores indicate a better health status. 
 
Change #20 
Section 9.10, FACIT-F, heading and all paragraphs 
The FACIT-F is a self-administered quality of life questionnaire targeted to the management of 
chronic illness within the past 7 days. The FACIT-F contains 13 questions with responses scored 
on a 5-point Likert scale from 0 (not at all) to 4 (very much). Scores range from 0 to 52 (Mease 
et al, 2011). 
The FACIT-F will be assessed by the subject at the visits specified in Table 5-2. 
Has been changed to: 
Section 9.10, FACIT-F-Fatigue subscale 
The FACIT-F is a self-administered quality of life questionnaire targeted to 40-item measure 
that assesses self-reported fatigue and its impact upon daily activities and function over the 
management of chronic illness within the past 7 days (FACIT.org). The scale consists of 
5 subscales (physical well-being, social/family well-being, emotional well-being, functional 
well-being, and fatigue). The fatigue subscale is the only one used in this study. The FACIT-
F contains It is composed of 13 questions with responses items, all scored on a 5-point Likert 
scale from 0 (nNot at all) to 4 (vVery much). Scores range The FACIT-Fatigue subscale score 
ranges from 0 to 52 (Mease et al, 2011) with 0 being the worst possible score and 52 being 
the best possible score. To obtain a score from 0 to 52, all negatively worded questions have 
to be recoded, so that responses range from worst (0) to the best (4) outcome.  
The FACIT-F-Fatigue subscale will be assessed completed by the subject at the visits specified 
in Table 5-2. 
 
Change #21 
Section 12.1.1.4 Other safety topics of interest, paragraph 1 
Pre-specified safety topics of interest for the study are: infections (serious, opportunistic, fungal, 
and TB), neutropenia, hypersensitivity, suicidal ideation and behavior, depression, major 
cardiovascular events, liver function test changes/enzyme elevations, malignancies, and 
inflammatory bowel diseases (with gastroenterology referral, as appropriate).  
Has been changed to: 
Pre-specified safety topics of interest for the study are: infections (serious, opportunistic, fungal, 
and TB), neutropenia, hypersensitivity, suicidal ideation and behavior, depression, major 
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cardiovascular events, liver function test changes/enzyme elevations, malignancies, and 
inflammatory bowel diseases (with gastroenterology referral, as appropriate).  
 
Change #22 
Section 9.20.3, Sacroiliac joint and spine MRI assessment substudy 
The following sentence has been added at the end of the last paragraph: 
Additional scoring systems of inflammation may be used as appropriate methodology becomes 
accepted. 
 
Change #23 
Section 12.2 Pregnancy, paragraph 1 and bullet points 
If an Investigator is notified that a subject has become pregnant after the first intake of any IMP, 
the Investigator must immediately notify UCB’s PS department by entering all pregnancy 
information into the eCRF. An automatic notification will be sent to UCB’s PS department. The 
subject should be withdrawn from the study as soon as pregnancy is known (by positive 
pregnancy test), and the following should be completed: 
• The subject should return for the ET Visit. 
• The subject should immediately stop the intake of the IMP.  
• A Safety Follow-Up Visit should be scheduled 20 weeks after the subject has discontinued 
her IMP. 
Has been changed to: 
If an Investigator is notified that a subject has become pregnant after the first intake of any IMP, 
the Investigator must immediately (within 24 hours) notify UCB’s PS department by entering 
all pregnancy information into the eCRF. An automatic notification will be sent to UCB’s PS 
department. The subject should be permanently withdrawn from the study IMP as soon as 
pregnancy is known (by positive pregnancy test), and the following should be completed: 
• The subject should return for the ET Visit. 
• The subject should immediately stop the intake of the IMP.  
• The subject should return for an early ad-hoc study visit. 
• A Safety Follow-Up Visit should be scheduled 20 weeks after the subject has discontinued 
her final dose of IMP. 
The Investigator should discuss with the subject the possibility to continue the study by 
attending the scheduled visits for assessments without IMP administration. The tests or 
assessments, which are considered contraindicated during the pregnancy should not be 
performed. The early ad-hoc study visit will be considered as the ET Visit if the subject 
does not wish to pursue the study investigations. 
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The Investigator must inform the subject of information currently known about potential 
risks and about available treatment alternatives. 
 
Change #24 
Section 12.6.1 Evaluation of PDILI, paragraph 1 
The PDILI IMP discontinuation criteria for this study are provided in Section 6.3.1, with the 
accompanying required follow-up investigation and monitoring detailed below. All PDILI events 
must be reported as an AE and reported to the study site and Sponsor within 24 hours of learning 
of their occurrence. Any PDILI event that meets the criterion for potential Hy’s Law must be 
reported as an AE of special interest (see Section 12.1.1.3), and, if applicable, also reported as an 
SAE (see Section 12.1.1.2). 
Has been changed to: 
The PDILI IMP discontinuation criteria for this study are provided in Section 6.3.1, with the 
accompanying required follow-up investigation and monitoring detailed below. All PDILI events 
must be reported as an AE and PDILI events meeting SAE criteria should be reported to the 
study site and Sponsor within 24 hours of learning of their occurrence. Any PDILI event that 
meets the criterion for potential Hy’s Law must be reported within 24 hours of learning of their 
occurrence as an AE of special interest (see Section 12.1.1.3), and, if applicable, also reported 
as an SAE (see Section 12.1.1.2).  
 
Change #25 
Section 12.7.1 Vital signs 
The Investigator or designee should measure all vital signs (systolic and diastolic BP, 
temperature [oral, axillary, or otic], pulse rate) prior to dosing after the subject has been sitting 
for at least 5 minutes, and the subject should remain seated during the measurements. At 
Baseline/Day 1 and Week 16 collect pulse and BP prior to drug administration and then at 
approximately 30 minutes and 1 hour after dosing.  
Has been changed to: 
The Investigator or designee should measure all vital signs (systolic and diastolic BP, 
temperature [oral, axillary, or otic], pulse rate) prior to dosing after the subject has been sitting 
for at least 5 minutes, and the subject should remain seated during the measurements. At 
Baseline/Day 1 and Week 16, collect pulse and BP vital signs prior to drug administration and 
then at approximately 30 minutes and 1 hour after dosing.  
 
Change #26 
Section 15.1, Definition of analysis sets, fifth bullet 
• The Per-Protocol Set (PPS) will consist of all subjects in the RS who had no important 
protocol deviation affecting the primary efficacy variable. Important protocol deviations will 
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be predefined and subjects with important protocol deviations will be evaluated during a data 
evaluation meeting prior to unblinding of the data.  
Has been changed to: 
• The Per-Protocol Set (PPS) will consist of all subjects in the RS who had no important 
protocol deviation affecting the primary efficacy variable. Important protocol deviations will 
be predefined and subjects with important protocol deviations will be evaluated during a data 
evaluation meeting prior to unblinding of the data. Exclusions from the FAS will be 
considered important protocol deviations that also result in exclusion from the PPS. 
In addition, the following bullet has been added: 
The coronavirus disease 2019 (COVID-19) free set will consist of all subjects in the RS who had 
no COVID-19 impact up to the primary efficacy endpoint. Further details will be defined as part 
of the SAP. 
 
Change #27 
Section 15.3.1.1 Analysis of the primary efficacy variable, paragraph 2, bullet #1, bullet #3 
and paragraph 4 
… 
The primary endpoint is the ASAS40 response at Week 16. The primary efficacy analysis will 
evaluate the composite estimand in the RS. The composite estimand combines the clinically 
meaningful improvement from Baseline based on the ASAS40 response and not discontinuing 
treatment early due to an AE or lack of efficacy. 
… 
1. Population = Subjects meeting the protocol-specified inclusion/exclusion criteria. 
… 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to an AE or lack of efficacy prior to Week 16. A composite strategy will be 
implemented in which a positive clinical outcome is defined as achieving ASAS40 at 
Week 16 and not discontinuing study treatment due to an AE or lack of efficacy through 
Week 16.  
… 
Any missing data at Week 16 that are not preceded by an intercurrent event (ie, discontinuation 
of study medication due to an AE or lack of efficacy) will be imputed based on a predefined 
multiple imputation (MI) model. In MI, the missing value is replaced by a set of plausible values, 
where each value is a Bayesian draw from the conditional distribution of the missing data given 
the observed data. Intermittent missing data will be imputed using the Markov-Chain Monte 
Carlo (MCMC) method, followed by logistic regression for monotone missing data.  
… 
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Has been changed to: 
… 
The primary endpoint is the ASAS40 response at Week 16. The primary efficacy analysis will 
evaluate the composite estimand in the RS. The composite estimand combines the clinically 
meaningful improvement from Baseline based on the ASAS40 response and not discontinuing 
treatment early due to an AE or lack of efficacy. In practice, this composite estimand is 
similar to non-responder imputation (NRI), referred to here as modified NRI.  
… 
1. Population = Subjects meeting enrolled according to the protocol-specified 
inclusion/exclusion criteria and randomized to IMP. 
… 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to an AE or lack of efficacy prior to Week 16. A composite strategy will be 
implemented in which a positive clinical outcome is defined as achieving ASAS40 at 
Week 16 and not discontinuing study treatment due to an AE or lack of efficacy through 
Week 16. 
… 
Any mMissing data at Week 16 that are not preceded by an intercurrent event, and any data 
after an intercurrent event will be imputed as non-responders (ie, discontinuation of study 
medication due to an AE or lack of efficacy) will be imputed based on a predefined multiple 
imputation (MI) model. In MI, the missing value is replaced by a set of plausible values, where 
each value is a Bayesian draw from the conditional distribution of the missing data given the 
observed data. Intermittent missing data will be imputed using the Markov-Chain Monte Carlo 
(MCMC) method, followed by logistic regression for monotone missing data.  
… 
 
Change #28 
Section 15.3.1.1.1 Supportive analyses 
Supportive analyses for the primary efficacy variable will be conducted: 
1. The analysis will be repeated based on the PPS to evaluate the effect of important protocol 
deviations on the analysis.  
2. The analyses will be repeated for all subjects in the FAS to evaluate the consistency between 
the RS and the more restrictive FAS. This analysis will only be performed if the number of 
subjects in RS and FAS are different. 
3. The analyses will also be repeated for all individual components of the ASAS40 response to 
explore the effect of the signs and symptoms of the individual components on the composite 
endpoint. Since all ASAS components are continuous variables (eg, change from Baseline in 
total spinal pain), an analysis of covariance (ANCOVA) with treatment, region, and prior 
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TNFα inhibitor exposure as fixed effects and the Baseline values as covariate will be used for 
the analysis. 
Additional supportive analyses to evaluate varying assumptions related to the handling of 
missing data will also be performed and are described in Section 15.7. 
Has been changed to: 
Supportive analyses for the primary efficacy variable will be conducted. The analyses will be 
repeated: 
1. The analysis will be repeated bBased on the PPS to evaluate the effect of important protocol 
deviations on the analysis.  
2. The analyses will be repeated fFor all subjects in the FAS to evaluate the consistency 
between the RS and the more restrictive FAS. This analysis will only be performed if the 
number of subjects in RS and FAS are different. 
3. The analyses will also be repeated fFor all individual components of the ASAS40 response to 
explore the effect of the signs and symptoms of the individual components on the composite 
endpoint. Since all ASAS components are continuous variables (eg, change from Baseline in 
total spinal pain), an analysis of covariance (ANCOVA) with treatment, region, and prior 
TNFα inhibitor exposure as fixed effects and the Baseline values as covariate will be used for 
the analysis. 
4. Using a modified composite estimand where intercurrent events are defined only as 
discontinuation due to adverse event or lack of efficacy. 
5. Using a treatment policy imputation. 
6. Using a tipping point analysis. 
7. Using observed cases only (OC). 
8. Using the COVID-19-free set. 
Further specification of Aadditional supportive analyses to evaluate varying assumptions 
related to the handling of missing data will also be performed and are described in Section 15.7. 
 
Change #29 
Section 15.3.1.2 Analyses of the secondary efficacy variables, paragraph 2, first bullet point 
and paragraphs 4 and 5 
… 
Binary variables will be analyzed to evaluate the composite estimand in the RS as done for the 
primary efficacy variable. The composite estimand combines (1) achieving the given binary 
response and (2) not discontinuing prior to Week 16 due to an AE or lack of efficacy. The 
statistical hypothesis for the binary variables at Week 16 is that the conditional odds ratio for 
binary variables in the bimekizumab treatment group compared with the placebo treatment group 
is equal to 1. 
… 
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• Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to an AE or lack of efficacy prior to Week 16. A hypothetical strategy for 
addressing intercurrent events will be implemented. This estimand targets the treatment 
difference in a scenario where withdrawal from study treatment due to an AE or lack of 
efficacy does not occur, such that outcomes for subjects without an intercurrent event are as 
observed, and outcomes for subjects with an intercurrent event are treated as though they had 
completed the randomized study treatment through Week 16. A multiple imputation strategy 
will be used to impute data following an intercurrent event. 
… 
Any missing data at Week 16 that is not preceded by an intercurrent event (ie, discontinuation of 
study medication due to an AE or lack of efficacy) will be imputed based on a predefined MI 
model. The missing value will be replaced by a set of plausible values, where each value is a 
Bayesian draw from the conditional distribution of the missing data given the observed data. 
Intermittent missing data will be imputed using the MCMC method, followed by monotone 
regression for monotone missing data. The statistical model for the comparison of bimekizumab 
and placebo will be an ANCOVA with treatment, region, and prior TNFα inhibitor exposure as 
fixed effects and the Baseline value as covariate. The statistical hypothesis for the continuous 
variables at Week 16 is that the treatment difference between the bimekizumab treatment group 
and placebo is equal to 0. 
All secondary efficacy variables will also be summarized based on observed case data. 
 
Has been changed to: 
… 
Binary variables will be analyzed to evaluate the composite estimand in the RS, as done for the 
primary efficacy variable. The composite estimand combines (1) achieving the given binary 
response and (2) not discontinuing treatment prior to Week 16 due to an AE or lack of efficacy. 
The statistical hypothesis for the binary variables at Week 16 is that the conditional odds ratio for 
binary variables in the bimekizumab treatment group compared with the placebo treatment group 
is equal to 1. 
… 
• Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to an AE or lack of efficacy prior to Week 16. A hypothetical strategy for 
addressing intercurrent events will be implemented. This estimand targets the treatment 
difference in a scenario where withdrawal from study treatment due to an AE or lack of 
efficacy does not occur, such that outcomes for subjects without an intercurrent event are as 
observed, and outcomes for subjects with an intercurrent event are treated as though they had 
completed the randomized study treatment through Week 16. A multiple imputation strategy 
will be used to impute data following an intercurrent event. 
… 
Any missing data at Week 16 that is not preceded by an intercurrent event (ie, discontinuation of 
study medication due to an AE or lack of efficacy) will be imputed based on a 
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predefined multiple imputation (MI) model. The missing value will be replaced by a set of 
plausible values, where each value is a Bayesian draw from the conditional distribution of the 
missing data given the observed data. Intermittent missing data will be imputed using the 
Markov-Chain Monte Carlo (MCMC) method, followed by monotone regression for monotone 
missing data. The statistical model for the comparison of bimekizumab and placebo will be an 
ANCOVA with treatment, region, and prior TNFα inhibitor exposure as fixed effects and the 
Baseline value as covariate. The statistical hypothesis for the continuous variables at Week 16 is 
that the treatment difference between the bimekizumab treatment group and placebo is equal to 
0. 
All secondary efficacy variables will also be summarized based on observed case data. Binary 
outcomes will also be summarized using the modified composite estimand. 
 
Change #30 
Section 15.3.2 Analyses of other efficacy variables, bullet #3, paragraph 3 and the second 
bullet #3 
… 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to adverse event or lack of efficacy prior to the time point being summarized. A 
composite strategy will be implemented in which a positive clinical outcome is defined as 
achieving the given variable at the specified time point and not discontinuing study treatment 
due to adverse event or lack of efficacy through that time point. 
… 
Any missing data that are not preceded by an intercurrent event as described above will be 
imputed based on a predefined multiple imputation model as described for the primary efficacy 
variable. 
… 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to an AE or lack of efficacy prior to the time point being summarized. A 
hypothetical strategy will be implemented in which outcomes for subjects without an 
intercurrent event are as observed at the given time point, and outcomes for subjects with an 
intercurrent event are treated as though they had completed the randomized study treatment 
through the time point being summarized. A multiple imputation strategy will be used to 
impute data following an intercurrent event. 
… 
Has been changed to: 
… 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to adverse event or lack of efficacy prior to the time point being summarized. A 
composite strategy will be implemented in which a positive clinical outcome is defined as 
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achieving the given variable at the specified time point and not discontinuing study treatment 
due to adverse event or lack of efficacy through that time point. 
… 
Any missing data that are not preceded by an intercurrent event as described above will be 
imputed based on a predefined multiple imputation model NRI as described for the primary and 
secondary efficacy variables. 
… 
3. Intercurrent event handling = An intercurrent event is defined as discontinuation of study 
treatment due to an AE or lack of efficacy prior to the time point being summarized. A 
hypothetical strategy will be implemented in which outcomes for subjects without an 
intercurrent event are as observed at the given time point, and outcomes for subjects with an 
intercurrent event are treated as though they had completed the randomized study treatment 
through the time point being summarized. A multiple imputation strategy will be used to 
impute data following an intercurrent event. 
… 
 
Change #31 
Section 15.7, Handling of dropouts or missing data, paragraphs 1 and 2, bullet #1 and 
paragraph 4 
The analysis for the primary and secondary efficacy variables will include the use of MI. In MI, 
the missing value is replaced by a set of plausible values, where each value is a Bayesian draw 
from the conditional distribution of the missing data given the observed data. Intermittent 
missing data will be imputed using the MCMC method, followed by regression for monotone 
missing data. The multiple imputation procedures planned for the primary and secondary 
efficacy analyses are based on an assumption of data missing at random (MAR).  
The sensitivity of results to the approach for handling missing data will be evaluated via 
supportive analyses using different missing data mechanisms. The following supportive analyses 
for the primary efficacy variable and for those secondary efficacy variables that are part of the 
hierarchical testing will be conducted: 
1.  Deviations from the MAR pattern will be evaluated using a reference-based MI approach. 
Intermittent missing data will be imputed using the MCMC method. The remaining monotone 
missing data will be assumed to follow a missing not at random (MNAR) pattern. These data 
will be imputed using a reference-based approach in which the MI model is based on data 
from the placebo group, thereby assuming that monotone missing data follow a trajectory 
similar to the placebo group (Mallinckrodt, 2013). The estimand in this procedure is the 
difference in outcome improvement in all randomized subjects at the planned endpoint of the 
study attributable to the initially randomized medication (Mallinckrodt et al, 2012).  
… 
The same procedure described as in the primary efficacy analyses will be used. 
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… 
Has been changed to: 
The primary analysis for the primary and secondary efficacy variables will use a conservative 
approach to handling missing data that is similar to non-responder imputation. The 
sensitivity of results to the approach for handling missing data will be evaluated via 
supportive analyses using different missing data mechanisms. 
In instances where include the use of MI. In MI is used, the missing value is replaced by a set 
of plausible values, where each value is a Bayesian draw from the conditional distribution of the 
missing data given the observed data. Intermittent missing data will be imputed using the 
MCMC method, followed by regression for monotone missing data. The planned multiple 
imputation procedures planned for the primary and secondary efficacy analyses are based on an 
assumption of data missing at random (MAR).  
The sensitivity of results to the approach for handling missing data will be evaluated via 
supportive analyses using different missing data mechanisms. The following supportive analyses 
for the primary efficacy variable and for those secondary efficacy variables that are part of the 
hierarchical testing will be conducted: 
1.  Deviations from the MAR pattern will be evaluated using a reference-based MI approach. 
Intermittent missing data will be imputed using the MCMC method. The remaining monotone 
missing data will be assumed to follow a missing not at random (MNAR) pattern. These data 
will be imputed using a reference-based approach in which the MI model is based on data 
from the placebo group, thereby assuming that monotone missing data follow a trajectory 
similar to the placebo group (Mallinckrodt, 2013). The estimand in this procedure is the 
difference in outcome improvement in all randomized subjects at the planned endpoint of the 
study attributable to the initially randomized medication (Mallinckrodt et al, 2012). Multiple 
imputation as described above will be performed using the modified composite estimand 
as specified for the use with the secondary variables. The definition of an intercurrent 
event is changed from all treatment discontinuation, to discontinuation of treatment due 
to AE or lack of efficacy. 
… 
The same procedure described as in the primary efficacy analyses will be used. For the 
secondary and other efficacy variables, the binary endpoints will be analyzed using 
modified NRI, MI and OC, and the continuous endpoints will be analyzed using MI and 
OC. 
… 
 
Change #32 
Section 15.8.1, Interim analyses, paragraph 1 
Two interim analyses will be performed: one after all randomized subjects have completed the 
Double-Blind Treatment Period and the Week 24 assessments, and one after all subjects have 
completed Week 52. 
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Has been changed to: 
Two interim analyses will be performed: one after all the planned number of randomized 
subjects have completed the Double-Blind Treatment Period and the Week 24 assessments, and 
one after all the planned number of subjects have completed Week 52.  
In addition, the following text has been added: 
Additional interim analyses and data cuts may be performed for regulatory purposes. 
 
Change #33 
Section 15.8.2 Data monitoring and Adjudication Committees  
The following text has been added: 
Other adjudication committees may be added as necessary. 
 
Change #34 
Section 15.9.2, Power calculations for secondary endpoints in the hierarchical testing 
… 
For change from Baseline in BASDAI at Week 16, an adjusted between-treatment difference 
of - 1.38 with an SD=1.8 for bimekizumab and SD=1.4 for placebo was used. With those 
assumptions, the endpoint is powered with >99% at the planned sample size. 
… 
For change from Baseline in nocturnal spinal pain at Week 16, the AS data from the 
certolizumab pegol study AS001 were used. An adjusted between-treatment difference of -1.88 
with an SD=2.9 for bimekizumab and SD=2.4 for placebo was used. With those assumptions, the 
endpoint is powered with >99% at the planned sample size. 
For change from Baseline in ASQoL at Week 16, an adjusted between-treatment difference 
of - 2.39 with an SD=4.5 for bimekizumab and placebo was used. With those assumptions, the 
endpoint is powered with >99% at the planned sample size. 
For change from Baseline in SF-36 at Week 16, an adjusted between-treatment difference of 4.56 
with an SD=8.1 for bimekizumab and SD=5.8 for placebo was used. With those assumptions, the 
endpoint is powered with >99% at the planned sample size. 
… 
Has been changed to: 
… 
For change from Baseline in BASDAI total score at Week 16, an adjusted between-treatment 
difference of - 1.38 with an SD=1.8 for bimekizumab and SD=1.4 for placebo was used. With 
those assumptions, the endpoint is powered with >99% at the planned sample size. 
… 
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For change from Baseline in nocturnal spinal pain score at Week 16, the AS data from the 
certolizumab pegol study AS001 were used. An adjusted between-treatment difference of -1.88 
with an SD=2.9 for bimekizumab and SD=2.4 for placebo was used. With those assumptions, the 
endpoint is powered with >99% at the planned sample size. 
For change from Baseline in ASQoL total score at Week 16, an adjusted between-treatment 
difference of - 2.39 with an SD=4.5 for bimekizumab and placebo was used. With those 
assumptions, the endpoint is powered with >99% at the planned sample size. 
For change from Baseline in SF-36 PCS score at Week 16, an adjusted between-treatment 
difference of 4.56 with an SD=8.1 for bimekizumab and SD=5.8 for placebo was used. With 
those assumptions, the endpoint is powered with >99% at the planned sample size. 
… 
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20 
DECLARATION AND SIGNATURE OF INVESTIGATOR 
I confirm that I have carefully read and understood this protocol and agree to conduct this 
clinical study as outlined in this protocol, according to current Good Clinical Practice and local 
laws and requirements. 
I will ensure that all subinvestigators and other staff members read and understand all aspects of 
this protocol. 
I have received and read all study-related information provided to me. 
The objectives and content of this protocol as well as the results deriving from it will be treated 
confidentially, and will not be made available to third parties without prior authorization by 
UCB. 
All rights of publication of the results reside with UCB, unless other agreements were made in a 
separate contract. 
Investigator: 
 
 
 
 
Printed name  
 
Date/Signature 
 
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21 
SPONSOR DECLARATION 
I confirm that I have carefully read and understand this protocol and agree to conduct this 
clinical study as outlined in this protocol and according to current Good Clinical Practice. 
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Approval Signatures
Name:
as0011-protocol-amend-4
Version:
1. 0
Document Number:
CLIN-000166877
Title:
AS0011 Protocol Amendment 4 - Phase 3 - Placebo-controlled - Double-blind
Approved Date:
17 Feb 2021
Document Approvals
Approval
Verdict: Approved
Name: 
Capacity: Medical
Date of Signature: 16-Feb-2021 11:37:45 GMT+0000
Approval
Verdict: Approved
Name: 
Capacity: Qualified Person
Date of Signature: 16-Feb-2021 14:12:45 GMT+0000
Approval
Verdict: Approved
Name: 
Capacity: Clinical
Date of Signature: 17-Feb-2021 12:16:53 GMT+0000
PUBLIC COPY 
 
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