A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Active Reference (Adalimumab) Study Evaluating the Efficacy and Safety of Bimekizumab in the Treatment of Subjects With Active Psoriatic Arthritis
Phase: PHASE3
Conditions: Psoriatic Arthritis
Sponsor: UCB Biopharma SRL

UCB 
 
22 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
PA0010 
 
 
 
Confidential 
Page 1 of 189 
PROTOCOL PA0010 AMENDMENT 2 
 
A PHASE 3, MULTICENTER, RANDOMIZED, DOUBLE-BLIND, 
PLACEBO-CONTROLLED, ACTIVE REFERENCE 
(ADALIMUMAB) STUDY EVALUATING THE EFFICACY AND 
SAFETY OF BIMEKIZUMAB IN THE TREATMENT OF 
SUBJECTS WITH ACTIVE PSORIATIC ARTHRITIS 
PHASE 3 
EudraCT Number: 2017-002322-20 
IND Number: 128708 
Sponsor: 
UCB Biopharma SRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
 
Protocol/Amendment number 
Date 
Type of amendment 
 Final Protocol 
28 Nov 2018 
Not applicable 
Protocol Amendment 0.1 (Japan) 
05 Feb 2019 
Not applicable 
Protocol Amendment 1 
10 Jan 2020 
Substantial 
Protocol Amendment 1.1 (Japan) 
04 Feb 2020 
Substantial 
Protocol Amendment 2 
22 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. 

UCB 
 
22 Feb 2021 
Clinical Study Protocol 
Bimekizumab 
PA0010 
 
 
 
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 Celltech Ltd 
208 Bath Road 
Slough SL1 3WE 
UNITED KINGDOM 
Phone: 
 
Clinical Project Manager 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Str. 10 
40789 Monheim 
GERMANY 
Phone: 
 
Clinical Trial Biostatistician 
Name: 
 
Address: 
UCB 
208 Bath Road 
Slough SL1 3WE 
UNITED KINGDOM 
Phone: 
 
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 

UCB 
 
22 Feb 2021 
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PA0010 
 
 
 
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SERIOUS ADVERSE EVENT REPORTING 
Serious adverse event reporting (24h) 
All serious adverse events 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 
USA and Canada: +1-800-880-6949 or +1-866-890-3175 
Email 
Global: DS_ICT@ucb.com  
 

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22 Feb 2021 
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PA0010 
 
 
 
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TABLE OF CONTENTS 
TABLE OF CONTENTS ........................................................................................................... 4 
LIST OF TABLES ................................................................................................................... 10 
LIST OF FIGURES ................................................................................................................. 10 
LIST OF ABBREVIATIONS .................................................................................................. 11 
1 
SUMMARY ..................................................................................................................... 16 
2 
INTRODUCTION ........................................................................................................... 17 
2.1 
Psoriatic arthritis .......................................................................................................... 17 
2.1.1 
Psoriatic arthritis epidemiology ........................................................................... 17 
2.1.2 
Current treatments for psoriatic arthritis .............................................................. 17 
2.2 
Bimekizumab ............................................................................................................... 18 
2.2.1 
Nonclinical ........................................................................................................... 18 
2.2.2 
Clinical ................................................................................................................. 19 
2.2.2.1 
Completed studies ..................................................................................... 19 
2.2.2.2 
Ongoing studies ......................................................................................... 22 
2.3 
Adalimumab ................................................................................................................. 23 
3 
STUDY OBJECTIVES .................................................................................................... 23 
3.1 
Primary objective ......................................................................................................... 23 
3.2 
Secondary objectives ................................................................................................... 23 
3.3 
Other objectives ........................................................................................................... 24 
4 
STUDY VARIABLES ..................................................................................................... 24 
4.1 
Efficacy variables......................................................................................................... 24 
4.1.1 
Primary efficacy variable ..................................................................................... 24 
4.2 
Secondary variables ..................................................................................................... 24 
4.2.1 
Secondary efficacy variables ............................................................................... 24 
4.2.2 
Secondary safety variables .................................................................................. 25 
4.3 
Other variables ............................................................................................................. 25 
4.3.1 
Other efficacy variables ....................................................................................... 25 
4.3.2 
Other safety variables .......................................................................................... 27 
4.3.3 
Pharmacokinetic variable ..................................................................................... 27 
4.3.4 
Pharmacogenomic variables ................................................................................ 28 
4.3.5 
Immunological variables ..................................................................................... 28 
5 
STUDY DESIGN ............................................................................................................. 28 
5.1 
Study description ......................................................................................................... 28 
5.2 
Screening Period/Baseline ........................................................................................... 29 
5.2.1 
Within-study rescreening/retesting requirements ................................................ 29 
5.3 
Treatment Period .......................................................................................................... 30 
5.3.1 
Double-Blind Treatment Period .......................................................................... 30 

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5.3.2 
Active Treatment-Blind Period ............................................................................ 30 
5.4 
Permitted rescue therapy after Week 16 ...................................................................... 31 
5.5 
Safety Follow-Up Visit ................................................................................................ 32 
5.6 
Study duration per subject ........................................................................................... 32 
5.7 
Planned number of subjects and sites .......................................................................... 32 
5.7.1 
Enrollment of hs-CRP/bone erosion positive subjects ........................................ 32 
5.8 
Anticipated regions and countries ................................................................................ 33 
5.9 
Schedule of study assessments..................................................................................... 33 
5.10 
Schematic diagram ....................................................................................................... 40 
5.11 
Rationale for study design and selection of dose ......................................................... 40 
6 
SELECTION AND WITHDRAWAL OF SUBJECTS ................................................... 41 
6.1 
Inclusion criteria .......................................................................................................... 41 
6.2 
Exclusion criteria ......................................................................................................... 42 
6.3 
Withdrawal criteria ...................................................................................................... 46 
6.3.1 
Potential drug-induced liver injury IMP discontinuation criteria ........................ 48 
7 
STUDY TREATMENTS ................................................................................................. 49 
7.1 
Description of investigational medicinal products ...................................................... 49 
7.2 
Treatments to be administered ..................................................................................... 49 
7.3 
Packaging ..................................................................................................................... 51 
7.4 
Labeling ....................................................................................................................... 51 
7.5 
Handling and storage requirements ............................................................................. 51 
7.6 
Drug accountability ...................................................................................................... 51 
7.7 
Procedures for monitoring subject compliance ............................................................ 52 
7.8 
Concomitant medications/treatments ........................................................................... 52 
7.8.1 
Permitted concomitant treatments (medications and therapies) .......................... 52 
7.8.1.1 
Psoriasis treatments ................................................................................... 52 
7.8.2 
Prohibited concomitant treatments (medications and therapies) ......................... 53 
7.8.3 
Vaccines ............................................................................................................... 54 
7.9 
Blinding........................................................................................................................ 54 
7.9.1 
Procedures for maintaining and breaking the treatment blind ............................. 55 
7.9.1.1 
Maintenance of study treatment blind ....................................................... 55 
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 ............................................................................... 56 
8.1 
Screening Period/Baseline ........................................................................................... 56 
8.1.1 
Screening ............................................................................................................. 56 
8.1.2 
Baseline (Day 1) .................................................................................................. 57 
8.2 
Treatment Period .......................................................................................................... 59 

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8.2.1 
Double-Blind Treatment Period .......................................................................... 59 
8.2.1.1 
Week 2 ....................................................................................................... 59 
8.2.1.2 
Week 4 ....................................................................................................... 59 
8.2.1.3 
Weeks 6, 10, and 14 .................................................................................. 61 
8.2.1.4 
Week 8 ....................................................................................................... 61 
8.2.1.5 
Week 12 ..................................................................................................... 62 
8.2.1.6 
Week 16 ..................................................................................................... 63 
8.2.2 
Active Treatment-Blind Period ............................................................................ 64 
8.2.2.1 
Weeks 18 and 22 ....................................................................................... 64 
8.2.2.2 
Week 20 ..................................................................................................... 64 
8.2.2.3 
Week 24 ..................................................................................................... 65 
8.2.2.4 
Weeks 26, 30, 34, 38, 42, 46, and 50 ........................................................ 66 
8.2.2.5 
Week 28 ..................................................................................................... 67 
8.2.2.6 
Week 32 ..................................................................................................... 67 
8.2.2.7 
Week 36 ..................................................................................................... 68 
8.2.2.8 
Week 40 ..................................................................................................... 69 
8.2.2.9 
Week 44 ..................................................................................................... 69 
8.2.2.10 
Week 48 ..................................................................................................... 70 
8.2.2.11 
Week 52 ..................................................................................................... 70 
8.3 
Early Termination Visit ............................................................................................... 72 
8.4 
Safety Follow-Up Visit (20 weeks [-3 days/+7 days] after the final dose) ................. 73 
8.5 
Unscheduled Visits ...................................................................................................... 74 
9 
ASSESSMENT OF EFFICACY ...................................................................................... 75 
9.1 
Joint assessments ......................................................................................................... 75 
9.1.1 
68/66 joint evaluation for ACR response and verification of Inclusion 
Criterion 5 ............................................................................................................ 75 
9.1.2 
28 joint evaluation for determination of DAS28(CRP) ....................................... 76 
9.2 
ACR20, ACR50, and ACR70 response ....................................................................... 76 
9.3 
Patient’s Global Assessments ...................................................................................... 76 
9.3.1 
Patient’s Global Assessment of Psoriatic Arthritis (PGA-PsA) .......................... 76 
9.3.2 
Patient’s Global Assessment of Arthritis (PGA-arthritis) ................................... 77 
9.4 
Physician’s Global Assessments .................................................................................. 77 
9.4.1 
Physician’s Global Assessment of Psoriatic Arthritis (PhGA-PsA) .................... 77 
9.4.2 
Physician’s Global Assessment of Arthritis (PhGA-Arthritis) ............................ 77 
9.5 
Patient’s Assessment of Arthritis Pain (PtAAP) .......................................................... 77 
9.6 
Health Assessment Questionnaire-Disability Index score (HAQ-DI) ......................... 78 
9.7 
High sensitivity C-reactive protein levels (hs-CRP) .................................................... 78 
9.8 
Evaluation of psoriasis ................................................................................................. 78 

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9.8.1 
Body surface area-psoriasis (BSA-PSO) ............................................................. 78 
9.8.2 
Psoriasis Area and Severity Index (PASI) ........................................................... 78 
9.8.3 
Investigator’s Global Assessment (IGA) ............................................................. 79 
9.8.4 
Modified Nail Psoriasis Severity Index (mNAPSI) ............................................. 80 
9.9 
Minimal Disease Activity (MDA) and Very Low Disease Activity (VLDA) ............. 80 
9.10 
Disease Activity Index for Psoriatic Arthritis (DAPSA) ............................................. 80 
9.11 
Van der Heijde modified Total Sharp Score (vdHmTSS) ........................................... 81 
9.12 
Disease Activity Score-28 based on C-reactive protein (DAS28[CRP]) ..................... 81 
9.13 
Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ............................... 81 
9.14 
Leeds Enthesitis Index (LEI) ....................................................................................... 81 
9.15 
Spondyloarthritis Research Consortium of Canada (SPARCC) .................................. 82 
9.16 
Leeds Dactylitis Index (LDI) ....................................................................................... 82 
9.17 
Psoriatic Arthritis Quality of Life (PsAQoL) .............................................................. 82 
9.18 
Psoriatic Arthritis Impact of Disease-12 (PsAID-12) .................................................. 82 
9.19 
Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue subscale ......... 82 
9.20 
Short-Form 36-item Health Survey (SF-36) ................................................................ 83 
9.21 
Euro Quality of life 5-Dimensions-3 Level (EQ-5D-3L) ............................................ 83 
9.22 
Work Productivity and Activity Impairment Questionnaire–Specific Health Problem 
(WPAI-SHP) ................................................................................................................ 83 
9.23 
Psoriatic Arthritis Response Criteria (PsARC) ............................................................ 83 
9.24 
Psoriatic Arthritis Disease Activity Score (PASDAS) ................................................ 84 
10 ASSESSMENT OF PHARMACOKINETIC AND PHARMACOGENOMIC 
VARIABLES ................................................................................................................... 84 
10.1 
Pharmacokinetic variable ............................................................................................. 84 
10.2 
Pharmacogenomic variables ........................................................................................ 84 
11 ASSESSMENT OF IMMUNOLOGICAL VARIABLES ............................................... 85 
12 ASSESSMENT OF SAFETY .......................................................................................... 86 
12.1 
Adverse events ............................................................................................................. 86 
12.1.1 
Definitions ........................................................................................................... 86 
12.1.1.1 
Adverse event ............................................................................................ 86 
12.1.1.2 
Serious adverse event ................................................................................ 86 
12.1.1.3 
Adverse events of special interest ............................................................. 88 
12.1.1.4 
Other safety topics of interest .................................................................... 88 
12.1.2 
Procedures for reporting and recording adverse events ....................................... 89 
12.1.2.1 
Description of adverse events .................................................................... 89 
12.1.2.2 
Rule for repetition of an adverse event...................................................... 89 
12.1.2.3 
Additional procedures for reporting serious adverse events ..................... 89 
12.1.3 
Follow-up of adverse events ................................................................................ 90 
12.1.4 
Pregnancy ............................................................................................................ 91 

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12.1.5 
Suspected transmission of an infectious agent via a medicinal product .............. 92 
12.1.6 
Overdose of investigational medicinal product ................................................... 92 
12.1.7 
Safety signal detection ......................................................................................... 92 
12.2 
Laboratory measurements ............................................................................................ 92 
12.2.1 
Evaluation of potential drug-induced liver injury................................................ 94 
12.2.1.1 
Consultation with Medical Monitor and local hepatologist ...................... 99 
12.2.1.2 
Immediate action: determination of IMP discontinuation ......................... 99 
12.2.1.3 
Testing: identification/exclusion of alternative etiology ......................... 100 
12.2.1.4 
Follow-up evaluation ............................................................................... 102 
12.3 
Other safety measurements ........................................................................................ 102 
12.3.1 
Vital signs .......................................................................................................... 102 
12.3.2 
Body weight and height ..................................................................................... 103 
12.3.3 
Physical examination ......................................................................................... 103 
12.3.4 
12-lead electrocardiogram ................................................................................. 103 
12.3.5 
Assessment and management of TB and TB risk factors .................................. 103 
12.3.5.1 
Tuberculosis assessment by IGRA .......................................................... 107 
12.3.5.2 
Chest x-ray for tuberculosis .................................................................... 107 
12.3.5.3 
Tuberculosis questionnaire ...................................................................... 107 
12.3.5.4 
Tuberculosis management ....................................................................... 107 
12.3.6 
Pregnancy testing ............................................................................................... 108 
12.3.7 
Assessment of suicidal ideation and behavior ................................................... 108 
12.3.8 
Patient Health Questionnaire-9 (PHQ-9) ........................................................... 108 
13 STUDY MANAGEMENT AND ADMINISTRATION ............................................... 109 
13.1 
Adherence to protocol ................................................................................................ 109 
13.2 
Monitoring ................................................................................................................. 109 
13.2.1 
Definition of source data ................................................................................... 109 
13.2.2 
Source data verification ..................................................................................... 110 
13.3 
Data handling ............................................................................................................. 110 
13.3.1 
Case Report form completion ............................................................................ 110 
13.3.2 
Database entry and reconciliation ...................................................................... 111 
13.3.3 
Subject Screening and Enrollment log/Subject Identification Code list............ 111 
13.4 
Termination of the study ............................................................................................ 111 
13.5 
Archiving and data retention ...................................................................................... 111 
13.6 
Audit and inspection .................................................................................................. 112 
13.7 
Good Clinical Practice ............................................................................................... 112 
14 STATISTICS ................................................................................................................. 112 
14.1 
Definition of analysis sets .......................................................................................... 112 
14.2 
General statistical considerations ............................................................................... 113 

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14.3 
Planned efficacy analyses .......................................................................................... 113 
14.3.1 
Analysis of the primary and secondary efficacy variables ................................ 113 
14.3.1.1 
Analysis of the primary efficacy variable ............................................... 114 
14.3.1.2 
Analysis of the secondary efficacy variables .......................................... 116 
14.3.2 
Analysis of the other efficacy variables ............................................................. 118 
14.3.3 
Subgroup analyses ............................................................................................. 119 
14.4 
Planned safety analyses.............................................................................................. 120 
14.4.1 
Safety analyses ................................................................................................... 120 
14.5 
Other planned analyses .............................................................................................. 120 
14.5.1 
Pharmacokinetics analyses ................................................................................ 120 
14.5.2 
Immunological analyses .................................................................................... 120 
14.6 
Handling of protocol deviations................................................................................. 120 
14.7 
Handling of dropouts or missing data ........................................................................ 121 
14.8 
Planned interim analyses and data monitoring .......................................................... 122 
14.8.1 
Interim analyses ................................................................................................. 122 
14.8.2 
Data monitoring ................................................................................................. 122 
14.9 
Determination of sample size ..................................................................................... 123 
14.9.1 
Power calculation for primary endpoint ............................................................ 123 
14.9.2 
Power calculations for secondary endpoints ...................................................... 123 
15 ETHICS AND REGULATORY REQUIREMENTS .................................................... 126 
15.1 
Informed consent ....................................................................................................... 126 
15.2 
Subject identification cards ........................................................................................ 126 
15.3 
Institutional Review Boards and Independent Ethics Committees ............................ 126 
15.4 
Subject privacy........................................................................................................... 127 
15.5 
Protocol amendments ................................................................................................. 127 
16 FINANCE, INSURANCE, AND PUBLICATION ....................................................... 128 
17 REFERENCES .............................................................................................................. 128 
18 APPENDICES ............................................................................................................... 133 
18.1 
Classification Criteria for Psoriatic Arthritis ............................................................. 133 
18.2 
Protocol Amendment 1 .............................................................................................. 134 
18.3 
Protocol Amendment 2 .............................................................................................. 171 
19 DECLARATION AND SIGNATURE OF INVESTIGATOR ..................................... 188 
20 SPONSOR DECLARATION ........................................................................................ 189 
 

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LIST OF TABLES 
Table 5-1: 
Schedule of study assessments......................................................................... 34 
Table 7-1: 
Dosing scheme ................................................................................................. 50 
Table 7-2: 
Prohibited or restricted medications and required wash-out periods ............... 53 
Table 7-3 
Additional prohibited psoriasis treatments ...................................................... 54 
Table 9-1: 
Swelling and tenderness grading ..................................................................... 76 
Table 9-2: 
Body areas for calculation of percent BSA for PASI ...................................... 79 
Table 9-3: 
Five-point IGA ................................................................................................. 79 
Table 12-1: 
Anticipated SAEs for the population of subjects with PsA ............................. 88 
Table 12-2: 
Laboratory measurements ................................................................................ 93 
Table 12‒3: 
Required investigations and follow-up for PDILI ........................................... 96 
Table 12-4: 
PDILI laboratory measurements .................................................................... 101 
Table 12-5: 
PDILI information to be collected ................................................................. 102 
Table 14‒1: 
Treatment effect by elevated hs-CRP and/or bone erosion at Baseline for 
secondary efficacy analyses ........................................................................... 125 
Table 18-1: 
CASPAR Criteria ........................................................................................... 133 
 
LIST OF FIGURES 
Figure 5-1: 
Study schematic diagram ................................................................................. 40 
Figure 12-1: 
Schematic diagram of TB test results and study eligibility ........................... 105 
Figure 12‒2: Schematic diagram of TB test results during the study ................................. 106 
Figure 14-1: 
Sequential testing procedure of primary/secondary efficacy endpoints 
(fixed sequence testing procedure) ................................................................ 114 
 

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LIST OF ABBREVIATIONS 
ACR 
American College of Rheumatology 
AE 
adverse event 
ALP 
alkaline phosphatase 
ALT 
alanine aminotransferase 
AMS 
Active Medication Set 
ANCOVA 
analysis of covariance 
AS 
ankylosing spondylitis 
AST 
aspartate aminotransferase 
ATS 
Active Treatment-Blind Set 
BA 
bioavailability 
BASDAI 
Bath Ankylosing Spondylitis Disease Activity Index 
bDMARD 
biologic disease modifying antirheumatic drug  
BP 
blood pressure 
BSA 
body surface area 
CASPAR 
Classification Criteria for Psoriatic Arthritis 
CCP 
cyclic citrullinated peptide 
CD 
cluster of differentiation 
cDMARD 
conventional disease-modifying antirheumatic drug 
CDMS 
clinical data management system 
CI 
confidence interval 
COX-2 
cyclooxygenase-2 
CPM 
Clinical Project Manager 
CRO 
contract research organization 
CRP 
C-reactive protein 
CSR 
Clinical Study Report 
CZP 
certolizumab pegol 
DAPSA 
Disease Activity Index for Psoriatic Arthritis 
DAS28(CRP) 
Disease Activity Score-28 based on C-reactive protein 
DIP 
distal interphalangeal 
DMARD 
disease modifying antirheumatic drug 
DMC 
Data Monitoring Committee 

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ECG 
electrocardiogram 
eCRF 
electronic Case Report form 
eC-SSRS 
electronic Columbia-Suicide Severity Rating Scale 
EDC 
electronic data capture 
ePRO 
Electronic Patient-Reported Outcome 
EQ-5D-3L 
EuroQol-5 Dimensions-3 Level 
ES 
Enrolled Set 
ET 
Early Termination 
EudraCT 
European Union Drug Regulating Authorities Clinical Trials 
FACIT 
Functional Assessment of Chronic Illness Therapy 
FAS 
Full Analysis Set 
GCP 
Good Clinical Practice 
GI 
gastrointestinal 
HAQ-DI 
Health Assessment Questionnaire – Disability Index 
HCQ 
hydroxychloroquine 
HCV 
hepatitis C virus 
HDL 
high density lipoprotein 
HIV 
human immunodeficiency virus 
HLA-B27 
human leukocyte antigen B27 
HRQoL 
Health-Related Quality of Life 
HS 
hidradenitis suppurativa 
hs-CRP 
high sensitivity C-reactive protein 
IB 
Investigator’s Brochure 
IBD 
inflammatory bowel disease 
ICF 
Informed Consent form 
ICH 
International Council for Harmonisation 
IEC 
Independent Ethics Committee 
IGA 
Investigator’s Global Assessment 
IGRA 
interferon gamma release assay 
IL 
interleukin 
IMP 
investigational medicinal product 
IRB 
Institutional Review Board 

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iv 
intravenous 
IXRS 
interactive voice or web response system  
LDI 
Leeds Dactylitis Index 
LDL 
low density lipoprotein 
LEF 
leflunomide 
LEI 
Leeds Enthesitis Index 
LN 
natural logarithm 
LS 
least squares 
LTB 
latent tuberculosis 
MAR 
missing at random 
MCMC 
Markov-Chain Monte Carlo 
MCS 
Mental Component Summary 
MDA 
Minimal Disease Activity 
MedDRA 
Medical Dictionary for Regulatory Activities 
MI 
multiple imputation 
mNAPSI 
modified Nail Psoriasis Severity Index 
MTX 
methotrexate 
NHP 
nonhuman primate 
NRI 
nonresponder imputation 
NSAID 
nonsteroidal anti-inflammatory drug 
NTMB 
nontuberculous mycobacteria 
OC 
observed case 
PASI 
Psoriasis Area and Severity Index 
PASDAS 
Psoriatic Arthritis Disease Activity Score 
PCS 
Physical Component Summary 
PD 
pharmacodynamic 
PDILI 
potential drug-induced liver injury 
PFS 
prefilled syringe 
PGADA 
Patient’s Global Assessment of Disease Activity 
PGA-Arthritis 
Patient’s Global Assessment of Arthritis 
PGA-PsA 
Patient’s Global Assessment of Psoriatic Arthritis 
PhGADA 
Physician’s Global Assessment of Disease Activity 

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PhGA-Arthritis 
Physician’s Global Assessment of Arthritis 
PhGA-PsA 
Physician’s Global Assessment of Psoriatic Arthritis 
PHQ-9 
Patient Health Questionnaire-9 
PK 
pharmacokinetic 
PK-PPS 
Pharmacokinetics Per-Protocol Set 
PPS 
Per-Protocol Set 
PS 
Patient Safety 
PsA 
psoriatic arthritis 
PsAID-12 
Psoriatic Arthritis Impact of Disease-12 
PsARC 
Psoriatic Arthritis Response Criteria  
PsAQoL 
Psoriatic Arthritis Quality of Life 
PSO 
psoriasis 
PtAAP 
Patient’s Assessment of Arthritis Pain 
Q2W 
every 2 weeks 
Q4W 
every 4 weeks 
R/L 
right/left 
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 
SOP 
standard operating procedure 
SPARCC 
Spondyloarthritis Research Consortium of Canada 
SS 
Safety Set 
SSZ 
sulfasalazine 
TB 
tuberculosis 
TEAE 
treatment-emergent adverse event 

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TNF 
tumor necrosis factor  
TNFα 
tumor necrosis factor alpha 
UC 
ulcerative colitis 
ULN 
upper normal limit 
VAS 
Visual Analog Scale 
vdHmTSS 
van der Heijde modified Total Sharp Score 
VLDA 
Very Low Disease Activity 
WPAI-SHP 
Work Productivity and Activity Impairment Questionnaire–Specific 
Health Problem 

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1 
SUMMARY 
This is a Phase 3, multicenter, randomized, double-blind, placebo-controlled, noninferential 
active reference study to evaluate the efficacy and safety of bimekizumab in subjects with active 
psoriatic arthritis (PsA) who are biologic disease-modifying antirheumatic drug (bDMARD) 
naïve. To be eligible to participate in this study, subjects must be adults with a diagnosis of 
active PsA based on the Classification Criteria for Psoriatic Arthritis (CASPAR) and have 
disease with tender joint count (TJC) ≥3 and swollen joint count (SJC) ≥3. In addition, subjects 
should not have been previously exposed to any bDMARD for PsA or psoriasis (PSO) to be 
eligible for the study.  
The primary objective is to demonstrate the efficacy of bimekizumab administered 
subcutaneously (sc) every 4 weeks (Q4W) for 16 weeks compared with placebo in the treatment 
of subjects with active PsA as assessed by the American College of Rheumatology (ACR) 
50% response. The secondary efficacy and safety objectives of the study are listed in Section 3.2, 
and other objectives are listed in Section 3.3. In this study, the efficacy of bimekizumab will be 
assessed with reference to the active-reference drug, adalimumab (HUMIRA®; AbbVie 
Pharmaceuticals, North Chicago, IL); however, no formal statistical comparisons of adalimumab 
to bimekizumab or placebo are planned. 
The primary efficacy variable for this study is the ACR50 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) and Section 4.3.2 (other). The 
pharmacokinetic (PK), and pharmacogenomic variables are listed in Section 4.3.3, and 
Section 4.3.4 , respectively. The immunological variable is listed in Section 4.3.5.  
PA0010 will evaluate the efficacy and safety of bimekizumab 160mg sc Q4W in adult subjects 
with active PsA. The dose regimens were selected based on currently available safety and 
efficacy data from a Phase 2b study, and PK/pharmacodynamics (PD) modeling.  
The overall study design consists of a Screening Period (≥14 days to ≤35 days), a 16-week 
placebo-controlled Double-Blind Treatment Period, a 36-week Active Treatment-Blind Period, 
and a Safety Follow-Up (SFU) Visit 20 weeks after the final dose of investigational medicinal 
product (IMP) (for subjects not entering the extension study or who discontinue early, including 
those withdrawn from IMP). The maximum study duration per subject will be up to 73 weeks.  
It is planned to enroll a minimum of 45% of subjects who are positive for elevated high 
sensitivity C-reactive protein (hs-CRP ≥6mg/L) and/or who have at least 1 bone erosion at 
Screening. 
During the Double-Blind Treatment and Active Treatment-Blind Periods, permitted rescue 
therapy after Week 16 is described in Section 5.4. Subjects’ permitted background medications 
may be changed if the subject is not responding as per Investigator assessment. 
Subjects completing Week 52 are eligible for enrollment in an extension study where all subjects 
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Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio (stratified by region and 
bone erosion [0, ≥1]) to the following treatment groups: bimekizumab 160mg sc Q4W 
(420 subjects), placebo (280 subjects), and adalimumab sc 40mg every 2 weeks (Q2W) 
(140 subjects). The planned number of study sites is approximately 150. 
2 
INTRODUCTION 
2.1 
Psoriatic arthritis 
Psoriatic arthritis is a chronic inflammatory musculoskeletal disorder, which occurs in 
approximately 6% to 41% of people affected by PSO (Ogdie and Weiss, 2015). A substantial 
proportion of subjects have polyarthritis (McHugh et al, 2003). These disorders are distinct from 
rheumatoid arthritis (RA), the prototypical inflammatory arthritis, and generally have an earlier 
onset, distal interphalangeal (DIP) joint involvement, asymmetric distribution, dactylitis 
(inflammation of the whole digit), enthesitis (inflammation at the site of tendon insertion into 
bone), spinal involvement, and an association with the human leukocyte antigen (HLA)-B27 
allele.  
Previous work has implicated various isoforms of the interleukin (IL)-17 cytokine family in the 
pathophysiology of PSO and of PsA (Raychaudhuri et al, 2012; Fujishima et al, 2010; 
Watanabe et al, 2009; Harper et al, 2009; Johansen et al, 2009). Numbers of IL-17A-positive 
cells are increased and localized in psoriatic skin lesions (Fujishima et al, 2010; 
Watanabe et al, 2009; Harper et al, 2009; Johansen et al, 2009), and IL-17A and IL-17F are 
overexpressed in the serum and skin lesions of subjects with PSO (Johansen et al, 2009), while 
IL-17F in particular is a key inflammatory cytokine contributing to PSO pathology 
(Fujishima et al, 2010; Watanabe et al, 2009). Cluster of differentiation (CD) 4 + T helper 17 
(Th17) cells, IL-17A, and IL-17 receptor A (IL-17-RA) have recently been shown to play a role 
in PsA (Raychaudhuri et al, 2012). Anti-IL-17 antibodies have been shown to be effective 
treatments for PSO (Papp et al, 2012; Leonardi et al, 2012; Hueber et al, 2010) and have also 
shown activity in subjects with RA, PsA, and ankylosing spondylitis (AS) (McInnes et al, 2014; 
Mease et al, 2015; Hueber et al, 2010; Genovese et al, 2010). Taken together, these data suggest 
that inhibition of both IL-17A and IL-17F could be therapeutically effective in subjects with 
PSO, PsA, and axial spondyloarthritis. 
2.1.1 
Psoriatic arthritis epidemiology 
Psoriatic arthritis is usually diagnosed years after PSO appears. A substantial proportion of 
subjects have polyarthritis (Gladman 2015; McHugh et al, 2003). More than 50% of patients 
with PsA experience progressive, erosive arthritis that is often accompanied by pain, fatigue, and 
functional impairment. The combination of joint and skin manifestations of PsA can have a 
profound impact on patient function, well-being, and Health-Related Quality of Life (HRQoL). 
The functional impairments are also associated with significant direct health care costs and 
substantial work-related disability, including a lower rate of employment (Lee et al, 2010; 
Salaffi et al, 2009). 
2.1.2 
Current treatments for psoriatic arthritis 
Disease-modifying antirheumatic drugs (DMARDs) and biological agents targeting tumor 
necrosis factor alpha (TNFα), IL-17, and IL-12/23 are effective for the treatment of PsA 
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Genovese et al, 2007; Kavanaugh et al, 2006; Antoni et al, 2005a; Antoni et al, 2005b; 
Mease et al, 2005; Mease et al, 2004; McInnes et al, 2015; Mease et al, 2015). Current treatments 
include DMARDs (hydroxychloroquine, azathioprine, cyclosporine, cyclophosphamide, 
mycophenolic acid, mycophenolate mofetil, sulfasalazine [SSZ], tofacitinib, apremilast, 
abatacept, methotrexate [MTX], and leflunomide [LEF]), IL-17A inhibitor (secukinumab, and 
ixekizumab) and TNFα inhibitors (infliximab, adalimumab, etanercept, golimumab, and 
certolizumab pegol [CZP]). However, some subjects are not responsive to these treatments 
(defined as achieving ACR20 response criteria), do not maintain a clinical response, or have 
contraindications or intolerance to these agents. The long-term goals of therapy include 
improvement in symptoms of the disease, psoriatic plaque clearance, inhibition of disease 
progression, and prevention of bone destruction. 
2.2 
Bimekizumab 
Bimekizumab (UCB4940) is an engineered, humanized full-length monoclonal antibody of 
immunoglobin G1 (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. Interleukin-17A has been shown 
to have a role in pathogenesis of several autoimmune disorders and IL-17F has been increasingly 
recognized to contribute to the pathogenesis of a number of inflammatory diseases, including 
PSO, ulcerative colitis, asthma, AS, PsA, and RA (Raychaudhuri et al, 2012; 
Fujishima et al, 2010; Watanabe et al, 2009).  
While anti-IL-17A antibodies have demonstrated efficacy in subjects with PSO, PsA, and AS, 
there is currently no therapeutic approach available that fully inhibits the activity of IL-17F. 
Bimekizumab selectively and potently inhibits the activity of both IL-17A and IL-17F isoforms 
in vitro. Therefore, it permits an evaluation of the potential for additional efficacy, which may be 
conferred by dual inhibition of both cytokines in patients with diseases in which both cytokines 
are active. Furthermore, a proof-of-concept study (PA0007) with bimekizumab in subjects with 
moderate to severe PsA demonstrated a strong efficacy signal that warrants further exploration of 
bimekizumab in this indication. A Phase 2b, dose-ranging study (PA0008) was designed to 
investigate the efficacy and safety of various bimekizumab dose regimens in subjects with active 
PsA. The current Phase 3, randomized, double-blind, placebo-controlled, and active-controlled 
confirmatory study (PA0010) is designed to investigate the efficacy and safety of bimekizumab 
in subjects with active PsA. 
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 of diarrhea-related to infectious enteritis, asymptomatic proliferation of 
a protozoan commonly found in the Cynomolgus monkey, Balantidium coli, superficial 

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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 
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. 
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 
In the overall bimekizumab development program, the following clinical studies in healthy 
volunteers and subjects with PSO, RA, PsA, AS, ulcerative colitis (UC), and hidradenitis 
suppurativa (HS) have been completed: 
• UP0008 was a Phase 1, first-in-human study in subjects with mild to moderate PSO.  
• RA0124 and UP0031 were 2 Phase 1, bioavailability studies in healthy subjects. 
• UP0033 was a Phase 1, open-label, multicenter, randomized, parallel-group, 3-arm, single-
dose bioequivalence study of bimekizumab injected sc either by a prefilled syringe (PFS) or 
by an auto-injector in adult healthy subjects. 
• UP0034 is a Phase 1, open-label, randomized, parallel-group, single-dose study to evaluate 
the antibody response of influenza vaccination following concomitant exposure to 
bimekizumab in adult healthy subjects. 
• UP0074 was a Phase 1, open-label, randomized, parallel-group, single-dose study to evaluate 
the PK, safety, and tolerability of bimekizumab given as 2x1mL or 1x2mL sc administration 
in healthy subjects. 
• PA0007 was a Phase 1b study in subjects with moderate to severe PsA. 

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• UP0042 was a Phase 1, PK study in healthy Japanese and Caucasian subjects. 
• RA0123 was a Phase 2a study evaluating safety, PK, PD, and efficacy in subjects with 
moderate to severe RA who received bimekizumab as an add-on therapy to CZP. 
• UC0011 was a Phase 2a, multinational, multicenter, subject- and Investigator-blind, 
randomized, placebo-controlled study to evaluate the efficacy, safety, tolerability, and PK of 
bimekizumab in adult subjects with moderate to severe active UC (discontinued study). 
• PS0016 was a Phase 2a study evaluating the time course of Psoriasis Area and Severity Index 
(PASI) response, safety, and PK in subjects with moderate to severe chronic plaque PSO. 
PS0018 was the corresponding Phase 2 extension study. 
• PS0018 was a Phase 2 OLE study evaluating the long-term safety, tolerability, and efficacy 
of bimekizumab in subjects who completed PS0016. 
• PS0010 was a Phase 2b placebo-controlled dose-ranging study evaluating safety, efficacy, 
PK, and PD in subjects with moderate to severe PSO. 
• PS0011 was a Phase 2b, multicenter, 48-week, double-blind, parallel-group, extension study 
to assess the long-term safety, tolerability, and efficacy of bimekizumab in adult subjects 
with moderate to severe chronic plaque PSO who completed PS0010. 
• PS0008 is a Phase 3, multicenter, randomized, double-blind, parallel-group, active-
comparator-controlled study to evaluate the efficacy and safety of bimekizumab in adult 
subjects with moderate to severe chronic plaque PSO. 
• PS0009 is a Phase 3 randomized, double-blind, placebo- and active comparator-controlled 
study to evaluate the efficacy and safety of bimekizumab administered sc to adult subjects 
with moderate to severe plaque PSO. 
• PS0013 is a Phase 3, multicenter, randomized withdrawal, double-blind, placebo-controlled 
study to evaluate the efficacy and safety of bimekizumab in adult subjects with moderate to 
severe chronic plaque PSO. 
• PA0008 was a Phase 2b study evaluating the efficacy and safety in subjects with active PsA. 
• AS0008 was a Phase 2b, placebo-controlled study evaluating the efficacy and safety of 
bimekizumab in subjects with active AS. 
• HS0001 was a Phase 2 study to evaluate the safety, efficacy, and PK of bimekizumab in 
subjects with moderate to severe HS. 
To evaluate treatment in subjects with PsA, bimekizumab has been investigated in a Phase 1b, 
proof-of-concept, randomized, placebo-controlled, multiple-dose study (PA0007). The primary 
objective of PA0007 was to assess the safety and PK of multiple dose administration of iv 
bimekizumab in subjects with PsA. Four active doses and a placebo were tested. Drug was 
administered as a loading dose at Week 1, and 2 additional doses were administered at Week 4 
and Week 7. In each treatment group, subjects received a total of 3 doses of bimekizumab, 
administered every 3 weeks as shown below: 
• 80mg loading dose followed by 40mg at Weeks 4 and 7 
• 160mg loading dose followed by 80mg at Weeks 4 and 7 

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• 240mg loading dose followed by 160mg at Weeks 4 and 7 
• 560mg loading dose followed by 320mg at Weeks 4 and 7 
The results of this study demonstrated that all doses of bimekizumab were well tolerated and 
there were no unexpected clinically relevant safety findings. 
Infections (mostly nasopharyngitis) were the most commonly reported events in both the active 
treatment and the placebo group. None of the infections were considered serious or required 
treatment with antibiotics. Two subjects in the active treatment group experienced one local 
candida infection each (oropharyngitis and vulvovaginitis, respectively) that were nonserious and 
resolved with topical therapy. There was a potential reduction in mean neutrophil count in the 
active treatment group, although this drop was not clinically relevant and a clear relationship 
with dose or time was not evident. Some increases in liver function tests were reported, but none 
had a clear relationship to exposure to IMP. The exploratory analysis showed clinically relevant 
improvement in activity of PsA and in skin involvement in those subjects with concomitant 
active psoriatic lesions. 
PA0008 was a Phase 2b, placebo-controlled study to evaluate the efficacy, safety, tolerability, 
PK, PD, and immunogenicity of bimekizumab in subjects with active PsA. The primary 
objective of PA0008 was to assess the dose response based on the efficacy of bimekizumab 
administered sc Q4W (monthly) for 12 weeks in the treatment of subjects with active PsA. 
During the 12-week Double-Blind Period, subjects were randomized 1:1:1:1:1 (stratified by 
region and prior tumor necrosis factor [TNF] inhibitor exposure) to receive the following blinded 
IMP regimens. The enrollment of TNF inhibitor-experienced subjects was planned to be limited 
to approximately 30% of the total study population (actual enrollment was 18.9% of all subjects). 
• Placebo 
• Bimekizumab 16mg administered sc Q4W 
• Bimekizumab 160mg administered sc Q4W 
• Bimekizumab 320mg administered sc Q4W 
• Bimekizumab 320mg loading dose followed by 160mg administered sc starting at Week 4 
and Q4W thereafter  
After the 12-week Double-Blind Period, subjects entered the 36-week Dose-Blind Period. At the 
Week 12 Visit, subjects were allocated to bimekizumab treatment regimens: 160mg Q4W or 
320mg Q4W. 
The results of this study demonstrated a statistically significant dose response in the primary 
efficacy variable (ACR50 response at Week 12), and the dose response was linear for 
bimekizumab doses up to 160mg. The results of all secondary efficacy endpoints (ACR20, 
ACR70, PASI75, and PASI90 response at Week 12) were consistent with and supported the 
findings of the primary endpoint. All bimekizumab doses were associated with a greater response 
compared with placebo. 
In PA0008, all doses of bimekizumab were well tolerated, and there were no unexpected 
clinically relevant safety findings. During the overall study, the most commonly reported adverse 
events (AEs) in subjects treated with bimekizumab were nasopharyngitis (12.3%), upper 

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respiratory tract infection (10.3%), respiratory tract infection (5.9%), and pharyngitis (5.4%); all 
other AEs were reported by <5.0% of subjects. There was no apparent relationship to 
bimekizumab dose with regard to the incidence of treatment-emergent adverse events (TEAEs). 
Eight participants (3.9%) had serious adverse events (SAEs) in bimekizumab arms, and no SAE 
(by preferred term) was reported by more than 1 subject. Eight participants (3.9%) discontinued 
due to a TEAE. 
Additional information on the clinical data for bimekizumab is available in the current version of 
the Investigator’s Brochure (IB). 
2.2.2.2 
Ongoing studies 
The following studies of bimekizumab are ongoing:  
• PS0014 is a Phase 3, long-term extension study for eligible subjects from the Phase 3 PSO 
feeder studies to assess the safety, tolerability, and efficacy of bimekizumab. 
− DV0002 and DV0006 are multicenter, randomized, open-label studies to evaluate the 
safe and effective use of the prefilled safety syringe or the auto-injector for the sc 
self-injection of bimekizumab solution by subjects with moderate to severe PSO. 
DV0002 and DV0006 are substudies of PS0014; DV0002 is being conducted in North 
America, and DV0006 is being conducted in the EU and Japan.  
• PS0015 is a Phase 3b, randomized, double-blind, secukinumab-controlled, parallel-group 
study to evaluate the efficacy and safety of bimekizumab administered sc to subjects with 
moderate to severe chronic plaque PSO. 
• PA0009 is a Phase 2b, long-term extension study for eligible subjects from PA0008 to assess 
the safety, tolerability, and efficacy of bimekizumab. 
• PA0011 is a Phase 3, multicenter, randomized, double-blind, placebo-controlled study 
evaluating the efficacy and safety of bimekizumab in the treatment of subjects with active 
PsA. 
• PA0012 is a Phase 3, multicenter, OLE study to assess the long-term safety, tolerability, and 
efficacy of bimekizumab in the treatment of subjects with active PsA who complete PA0010 
or PA0011. 
− DV0004 is a multicenter, randomized, open-label study to evaluate the safe and effective 
use of the prefilled safety syringe or auto-injector for the sc self-injection of 
bimekizumab solution by subjects with active PsA. DV0004 is a substudy of PA0012. 
• AS0009 is a Phase 2b, long-term extension study for eligible subjects from AS0008 to assess 
the safety, tolerability, and efficacy of bimekizumab.  
• AS0010 is a Phase 3, multicenter, randomized, double-blind, placebo-controlled study 
evaluating the efficacy and safety of bimekizumab in subjects with active nonradiographic 
axial spondyloarthritis. 
• AS0011 is a Phase 3, multicenter, randomized, double-blind, placebo-controlled study 
evaluating the efficacy and safety of bimekizumab in subjects with active AS. 

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• AS0014 is a Phase 3, multicenter, OLE study to assess the long-term safety, tolerability, and 
efficacy of bimekizumab in the treatment of subjects who complete AS0010 or AS0011. 
• AS0013 is a Phase 2a, active-controlled study evaluating the efficacy and safety of 
bimekizumab compared with CZP in subjects with active AS. 
• HS0003 and HS0004 are Phase 3, multicenter, randomized, double-blind, placebo-controlled 
studies evaluating the efficacy and safety of bimekizumab in subjects with moderate to 
severe HS. 
• HS0005 is a Phase 3, multicenter, OLE study to assess the long-term safety, tolerability, and 
efficacy of bimekizumab in the treatment of subjects who complete HS0003 or HS0004. 
Additional information on the clinical data for bimekizumab is available in the current version of 
the IB. 
2.3 
Adalimumab 
In this study, the efficacy of bimekizumab will be assessed with reference to the active-reference 
drug, adalimumab. Adalimumab’s mechanism of action occurs through TNFα inhibition 
compared with bimekizumab’s inhibition of IL-17A and IL-17F (HUMIRA®, 2016). 
Adalimumab has been approved for the treatment of several auto-immune diseases such as PsA, 
RA, AS, Crohn’s disease, HS, and plaque PSO in the US and EU, as well as in many other 
countries globally, and is among the first line standard of care biologic therapy for patients not 
responding to conventional disease-modifying antirheumatic drugs (cDMARDs).  
3 
STUDY OBJECTIVES 
3.1 
Primary objective 
The primary objective is to demonstrate the clinical efficacy of bimekizumab administered sc 
Q4W for 16 weeks compared with placebo in the treatment of subjects with active PsA, as 
assessed by the ACR50 response. 
3.2 
Secondary objectives 
The secondary objectives of the study are as follows: 
• To assess the efficacy of bimekizumab compared with 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 skin PSO in the subgroup of affected subjects at 
Baseline 
• To assess the impact of bimekizumab on functional improvement  
• To assess the impact of bimekizumab on radiographic changes in the hands and feet 
• To assess the impact of bimekizumab on extra-articular disease manifestations (dactylitis, 
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3.3 
Other objectives 
Other objectives are as follows: 
• To descriptively assess the efficacy of bimekizumab with reference to adalimumab  
• To assess the immunogenicity of bimekizumab  
• To assess the impact of bimekizumab treatment on axial disease 
• To assess the maintenance of treatment effect 
• To assess nail PSO in the subgroup of affected subjects at Baseline 
• To explore the exposure response relationship of bimekizumab 
• To assess the effect of bimekizumab on gene and protein expression, and explore the 
relationship between genomic, genetic, and proteomic biomarkers and disease biology, drug 
treatment and inflammatory and immune responses (from consenting subjects who agree to 
participate in the biomarker substudy) 
• To assess the impact of bimekizumab on social life and work productivity 
4 
STUDY VARIABLES 
4.1 
Efficacy variables 
4.1.1 
Primary efficacy variable 
The primary efficacy variable for this study is the ACR50 response at Week 16. 
4.2 
Secondary variables 
4.2.1 
Secondary efficacy variables 
The secondary efficacy variables for this study are as follows: 
• Change from Baseline in Health Assessment Questionnaire—Disability Index (HAQ-DI) at 
Week 16 
• PASI90 response at Week 4 and Week 16 in the subgroup of subjects with PSO involving at 
least 3% BSA at Baseline 
• Change from Baseline in the Short Form 36-item Health Survey (SF-36) Physical 
Component Summary (PCS) at Week 16 
• Minimal Disease Activity (MDA) response at Week 16 
• Change from Baseline in Van der Heijde modified Total Sharp Score (vdHmTSS) in subjects 
with elevated hs-CRP and/or at least 1 bone erosion at Baseline at Week 16  
• Enthesitis-free state in the Leeds Enthesitis Index (LEI) at Week 16 in the subgroup of 
subjects with enthesitis at Baseline in the pooled population of PA0010 and PA0011 
• Dactylitis-free state based on the Leeds Dactylitis Index (LDI) at Week 16 in the subgroup of 
subjects with dactylitis at Baseline in the pooled population of PA0010 and PA0011 
• Change from Baseline in vdHmTSS in the overall population at Week 16 

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• ACR20 response at Week 16 
• ACR70 response at Week 16 
• Proportion of subjects with an Investigator Global Assessment (IGA) score of 0 (clear) or 
1 (almost clear) AND at least a 2-grade reduction from Baseline at Week 4 and Week 16 in 
the subset of subjects with psoriatic skin lesions at Baseline  
• Change from Baseline in the Patient’s Assessment of Arthritis Pain (PtAAP) at Week 16 
• Enthesitis-free state based on the Spondyloarthritis Research Consortium of Canada 
(SPARCC) index at Week 16 in the subgroup of subjects with enthesitis at Baseline 
• Change from Baseline in Psoriatic Arthritis Impact of Disease-12 (PsAID-12) total score at 
Week 16 
4.2.2 
Secondary safety variables 
Secondary safety variables to be assessed are as follows: 
• Incidence of TEAEs 
• Incidence of treatment-emergent 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 5-1 (all time points not specified 
in Section 4.1.1 or Section 4.2.1 are exploratory): 
• Time to ACR20, ACR50, and ACR70 response from Baseline (Day 1)  
• ACR20, ACR50, and ACR70 response 
• PASI75, PASI90, and PASI100 response in the subgroup of subjects with PSO involving at 
least 3% BSA at Baseline 
• Composite endpoint composed of ACR50 and PASI90 response in subjects with PSO 
involving at least 3% BSA at Baseline 
• Composite endpoint composed of ACR50 and PASI100 response in subjects with PSO 
involving at least 3% BSA at Baseline 
• Proportion of Psoriatic Arthritis Response Criteria (PsARC) responders 
• Psoriatic Arthritis Disease Activity Score (PASDAS) categories 
• Change from Baseline in the PASDAS  
• The proportion of ACR50 responders at Week 16 and maintaining response at Week 52 
• MDA response 
• Very Low Disease Activity (VLDA) response 

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• Proportion of subjects with an IGA score of 0 (clear) or 1 (almost clear) AND at least a 
2-grade reduction from Baseline in the subset of subjects with psoriatic skin lesions at 
Baseline 
• Disease Activity Index for Psoriatic Arthritis (DAPSA) score categories 
• Change from Baseline in DAPSA score 
• Change from Baseline in the Disease Activity Score-28 based on C-reactive protein 
(DAS28[CRP]) 
• Change from Baseline in all individual ACR core components: 
− SJC 
− TJC 
− HAQ-DI  
− PtAAP  
− Physician’s Global Assessment of Psoriatic Arthritis (PhGA-PsA)  
− Patient’s Global Assessment of Psoriatic Arthritis (PGA-PsA) 
− hs-CRP  
• Change from Baseline in vdHmTSS total score and in erosion and joint space narrowing 
(subscores) in subjects with elevated hs-CRP and/or with at least 1 bone erosion at Baseline 
• Change from Baseline in vdHmTSS total score and in erosion and joint space narrowing 
(subscores) in the overall population 
• Proportion of subjects with no radiographic joint damage progression (change from Baseline 
vdHmTSS of ≤0.5)  
• Dactylitis-free state based on the LDI in the subgroup of subjects with dactylitis at Baseline 
in the pooled population of PA0010 and PA0011, as well as for PA0010 alone 
• Enthesitis-free state based on the LEI in the subgroup of subjects with enthesitis at Baseline 
in the pooled population of PA0010 and PA0011, as well as for PA0010 alone 
• Enthesitis-free state based on the SPARCC index in the subgroup of subjects with enthesitis 
at Baseline in the pooled population of PA0010 and PA0011, as well as for PA0010 alone 
• Proportion of subjects with a decrease of HAQ-DI from Baseline of at least 0.35 in those 
subjects with HAQ-DI>0.35 at Baseline 
• Change from Baseline in the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 
in the subgroup of subjects with axial involvement defined by a score of ≥4 at Baseline 
• Change from Baseline in the modified Nail Psoriasis Severity Index (mNAPSI) score in the 
subgroup of subjects with psoriatic nail disease at Baseline 
• Change from Baseline in the LEI in the subgroup of subjects with enthesitis at Baseline in the 
pooled population of PA0010 and PA0011, as well as for PA0010 alone 

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• Change from Baseline in the SPARCC index in the subgroup of subjects with enthesitis at 
Baseline in the pooled population of PA0010 and PA0011, as well as for PA0010 alone 
• Change from Baseline in the LDI in the subgroup of subjects with dactylitis at Baseline in the 
pooled population of PA0010 and PA0011, as well as for PA0010 alone 
• Change from Baseline in PsAID-12 total score, as well as the individual domain scores 
• Proportion of subjects achieving PsAID-12 total score ≤4 
• Proportion of PsAID-12 responders (decrease from Baseline in PsAID-12 total score ≥3 in 
subjects with PsAID-12 total score >3 at Baseline) 
• Change from Baseline in the Psoriatic Arthritis Quality of Life (PsAQoL) total score 
• Change from Baseline in the SF-36 PCS and Mental Component Summary (MCS), as well as 
the 8 domain scores (Physical Functioning, Role Physical, Bodily Pain, General Health, 
Vitality, Social Functioning, Role Emotional, and Mental Health) 
• Change from Baseline in Functional Assessment of Chronic Illness Therapy 
(FACIT)-Fatigue subscale score 
• Proportion of FACIT-Fatigue subscale responders (subjects with a minimum clinically-
important difference for FACIT-Fatigue subscale score, defined as an increase of ≥4) 
• Change from Baseline in Work Productivity and Activity Impairment Questionnaire-Specific 
Health Problem (WPAI-SHP) v2.0 adapted to PsA scores  
• Responses to the EuroQol-5 Dimensions-3 Level (EQ-5D-3L)  
• Change from Baseline in EQ-5D-3L Visual Analog Scale (VAS) scores 
• Change from Baseline in Physician’s Global Assessment of Arthritis (PhGA-Arthritis) 
• Change from Baseline in Patient’s Global Assessment of Arthritis (PGA-Arthritis)  
4.3.2 
Other safety variables 
Other safety variables to be assessed are: 
• 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 the 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 AEs. 
4.3.3 
Pharmacokinetic variable 
The PK variable is the plasma concentration of bimekizumab. 

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4.3.4 
Pharmacogenomic variables 
Additional blood samples will be collected from subjects who consent to participate in the 
substudy at specific time points. If the collected samples are not used immediately, they will be 
stored at -80°C for up to 20 years until the completion of bimekizumab development program. 
Genomic, genetic, epigenetic, proteins, and metabolite biomarkers may be measured to evaluate 
the relationship with response to treatment with bimekizumab, psoriatic arthritis disease biology, 
and inflammatory and immune response processes. The nature and format of these tentative 
substudy analyses will be determined when the results of the main study are made available. 
The candidate exploratory variables are the blood or blood derivative (eg, serum) concentrations 
of cytokines and chemokines of relevance to IL-17A/F signaling pathway and psoriatic arthritis 
biology. Additional variables may include but will not be limited to serum complement 
concentrations. Where local regulations permit, additional blood samples will be collected at 
time points specified in Table 5-1. They may be used to allow for potential exploratory analyses 
of ribonucleic acid (RNA), proteins, lipids, and metabolite biomarkers relevant to disease 
biology and progression, response to therapy, the inflammatory and immune response processes, 
and cardiovascular risk in PsA. 
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. 
5 
STUDY DESIGN 
5.1 
Study description 
This is a Phase 3, multicenter, randomized, double-blind, placebo-controlled, active-reference 
study to evaluate the efficacy and safety of bimekizumab in subjects with active PsA. To be 
eligible to participate in this study, subjects must be adults with a diagnosis of active PsA based 
on the CASPAR criteria and have active disease with TJC ≥3 and SJC ≥3. It is planned to enroll 
a minimum of 45% of subjects who are positive for elevated hs-CRP (hs-CRP ≥6mg/L) and/or 
who have at least 1 bone erosion at Screening. 
Subjects should not have previously been treated with any biologic drugs for PsA or PSO. 
Detailed inclusion and exclusion criteria are presented in Section 6.1 and Section 6.2, 
respectively. 
The study will include 3 periods: a Screening Period (≥14 days to ≤35 days), a Treatment Period 
(52 weeks), and a Safety Follow-up Period (20 weeks after the final dose of IMP). The 
Treatment Period will consist of a 16-week Double-Blind Treatment Period followed by a 
36-week Active Treatment-Blind Period. Permitted rescue therapy changes after Week 16 are 
described in Section 5.4. The maximum study duration per subject will be up to 73 weeks. 
Eligible subjects will be randomized 3:2:1 (stratified by region and bone erosion [0, ≥1]) to 
receive 1 of 3 blinded treatments (bimekizumab 160mg sc Q4W, placebo, or active-reference 
[adalimumab 40mg sc Q2W]) and will remain on their allowable background medication. Details 
of the Treatment Period are provided in Section 5.3. 

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Subjects completing Week 52 and meeting eligibility criteria are eligible for enrollment in an 
extension study to continue to receive bimekizumab.  
An interim analysis of all available data (including efficacy, safety, and PK) will be undertaken 
after all randomized subjects have completed 24 weeks of treatment or have withdrawn from 
IMP or the study. The purpose of this analysis is to perform a comprehensive evaluation of all 
available data for the 3 treatment arms to prepare a regulatory submission for a marketing 
authorization application based on this analysis.  
A second interim analysis of all available data will be undertaken after all randomized subjects 
have completed 52 weeks of treatment or have withdrawn from IMP or the study. The purpose of 
this analysis is to demonstrate the long-term efficacy and safety of bimekizumab. For subjects 
who are ineligible for the open-label extension study at Week 52, a final analysis will be 
undertaken after the SFU Visit. 
Additional details for the interim analyses and data monitoring in this study are provided in 
Section 14.8.1. A detailed schedule of study assessments is presented in Table 5-1 and a study 
schematic diagram is presented in Figure 5-1.  
5.2 
Screening Period/Baseline 
The Screening Period will last for a minimum duration of 14 days and a maximum duration of 
35 days and will involve obtaining laboratory data and verifying that the doses of nonsteroidal 
anti-inflammatory drugs (NSAIDs), or permitted DMARDs, if used to treat PsA, are stable. The 
Screening Period will also enable washout of any medications not permitted for use during the 
study.  
During the Screening Period, X-rays of hands and feet will be assessed for bone erosion and used 
for the stratification of subjects at Baseline (Day 1). 
5.2.1 
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 PHQ-9, electronic Columbia-Suicide 
Severity Rating Scale (eC-SSRS), or the tuberculosis (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. 

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5.3 
Treatment Period 
5.3.1 
Double-Blind Treatment Period 
During the Double-Blind Treatment Period, subjects will be randomized 3:2:1 (stratified by 
region and bone erosion [0, ≥1]) to 1 of 3 blinded treatments. 
Investigational medicinal product treatment details are provided in Section 7.2. Visit windows of 
±2 days are allowed for all visits through Week 16. The visit window is relative to the Day 1 
(Baseline) Visit. 
Bimekizumab, adalimumab, and placebo will be administered sc by unblinded study personnel at 
the clinical site. 
The time between IMP doses should be ≥12 days and ≤16 days during the Double-Blind 
Treatment Period. The Double-Blind Period is 16 weeks in duration. At Week 16, subjects will 
transition from the double-blind, placebo-controlled treatment into the 36-week Active 
Treatment-Blind Period, as discussed in Section 5.3.2. 
Subjects withdrawing early from the study will undergo the Early Termination (ET) 
Visit assessments and will enter the SFU Period. Subjects who withdraw from IMP during the 
Double-Blind Period will be encouraged to return for all scheduled visits up to Week 52 and for 
the SFU Visit (20 weeks after their final dose of IMP), as applicable. 
5.3.2 
Active Treatment-Blind Period 
After the 16-week Double-Blind Treatment Period, subjects will enter the 36-week 
Active Treatment-Blind Period. At the Week 16 Visit, subjects will be allocated to treatment 
regimens as follows:  
• Subjects in the bimekizumab 160mg sc Q4W group will continue to receive 
bimekizumab 160mg Q4W 
• Subjects in the adalimumab 40mg sc Q2W group will continue to receive 
adalimumab 40mg sc Q2W  
• Subjects in the placebo group will be reallocated to bimekizumab 160mg sc Q4W 
Bimekizumab and adalimumab will be administered sc by unblinded study personnel at the 
clinical site. The first dose in the Active Treatment-Blind Period will be administered at Week 16 
after all assessments have been completed. After Week 16, if the subjects are not responding 
adequately as per Investigators’ judgement, rescue therapy will be allowed as described in 
Section 5.4. 
Visit windows of ±3 days are allowed for all visits after Week 16. 
The time between doses during the Active Treatment-Blind Period should be ≥11 days and 
≤17 days. 
Subjects who withdraw early from the study will undergo the ET Visit assessments and will 
enter the SFU Period. Subjects who withdraw from IMP during the Active-Treatment-Blind 
Period will be encouraged to return for all remaining scheduled visits up to Week 52 and the 
SFU Visit (20 weeks after their final dose of IMP), as applicable. 

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At the completion of the Active Treatment-Blind Period, Investigators should discuss treatment 
options with the subject. Subjects who complete PA0010 will be given the opportunity to enter 
an extension study at Week 52. 
5.4 
Permitted rescue therapy after Week 16 
After Week 16, subjects may be rescued by changes to their permitted background medications, 
if the subject is not responding as per Investigator assessment. Permitted rescue therapy changes 
are listed below. Any other changes should be discussed with the Medical Monitor prior to the 
change. 
Subjects who are rescued will remain on IMP. Permitted rescue therapy for eligible subjects will 
be at the Investigator’s discretion, with the following options:  
• Nonsteroidal anti-inflammatory drugs, DMARDs (MTX, SSZ, LEF, hydroxychloroquine 
[HCQ], apremilast), and/or joint injections may be given as permitted rescue therapy if 
deemed appropriate by the Investigator as outlined below. Subjects may receive these add-on 
therapies while continuing to receive their randomized dose of IMP. 
− For subjects taking NSAID/cyclooxygenase 2 (COX-2) inhibitors at Baseline, 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 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 at Baseline, either an NSAID or 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.  
− Methotrexate may be added or increased to a maximum dose of 25mg/week, or the 
maximum tolerated dose, whichever is lower. The route of administration may be 
changed from oral to sc.  
− Sulfasalazine may be given up to a maximum dose of 3g/day or 4g/day if in accordance 
with local standard of care, or the maximum tolerated dose, whichever is lower.  
− 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.  
− Hydroxychloroquine may be added or increased to a maximum dose of 400mg/day or the 
maximum tolerated dose, whichever is lower. 
− Apremilast may be given at a maximum dose of 30mg twice daily, or the maximum 
tolerated dose, whichever is lower. 
− Combination DMARDs are allowed except that LEF and MTX may not be given 
together. 
− Up to 2 joints (up to a total dose of 80mg methylprednisolone or equivalent) may be 
injected at or after Week 16; however, the same joint should not be injected more than 
once during the study. 

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• A decrease in dose or dosing frequency of any agent for the treatment of PsA is permitted for 
reasons of intolerance/AEs/side-effects at any time. 
• Any medication not listed in the protocol for rescue must be approved by the Medical 
Monitor prior to starting that medication. 
• If, in the judgment of the Investigator, the options outlined above are not considered 
appropriate for the subject, or the subject does not achieve sufficient response to these 
options, biologics may be considered. Subjects must discontinue IMP prior to use of another 
biologic therapy and follow the withdrawal criteria and follow-up as outlined in Section 6.3.  
• Permitted rescue therapy will be determined by the Investigator taking into account the 
half-life of bimekizumab (27.8 days). 
No other medication changes or additions are permitted for rescue therapy. 
Subjects may be withdrawn from IMP at any time if they are judged to be not responding and 
continue treatment per the Investigator’s discretion, as described in the Withdrawal Section 
(Section 6.3). 
5.5 
Safety Follow-Up Visit 
All subjects who complete the study and do not enter the extension study will have an 
SFU Visit, 20 weeks after their final dose of IMP. 
Any subjects who discontinue early, including those withdrawn from IMP, will be asked to 
attend all scheduled visits and will have an SFU Visit, 20 weeks after their final dose of IMP. 
5.6 
Study duration per subject 
For each subject, the study will last up to 73 weeks, as follows: 
• ≥14 days to ≤35 days in the Screening Period 
• 16 weeks in the placebo-controlled, Double-Blind Treatment Period 
• 36 weeks in the Active Treatment-Blind Period 
• An SFU Visit 20 weeks after the final dose of IMP (for subjects not entering the extension 
study or who discontinue early, including those withdrawn from IMP) 
The end of the study is defined as the date of the last visit of the last subject in the study. 
5.7 
Planned number of subjects and sites 
Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio (stratified by region and 
bone erosion [0, ≥1]) to the following treatment groups: bimekizumab 160mg sc Q4W (420 
subjects), placebo (280 subjects), and adalimumab 40mg sc Q2W (140 subjects). The planned 
number of study sites is approximately 150. 
5.7.1 
Enrollment of hs-CRP/bone erosion positive subjects 
It is planned to enroll a minimum of 45% of subjects who are positive for elevated hs-CRP 
(hs-CRP ≥6mg/L) and/or who have at least 1 bone erosion at Screening. 

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5.8 
Anticipated regions and countries 
This will be a multicenter, international study. Enrollment will be competitive among study sites 
and may be capped at sites.  
5.9 
Schedule of study assessments 
The schedule of study assessments is presented in Table 5-1. 
 

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Table 5-1: 
Schedule of study assessments 
     Visit a/ 
Week 
 
Protocol activity 
Screening (V1) 
Baseline (Day 1) 
(first dose) (V2) 
Double-Blind Treatment Period 
(weeks after first dose) 
Active Treatment-Blind Period 
(weeks after first dose) 
 
 
3/ 
2 
4/ 
4 
5/ 
6 
6/ 
8 
7/ 
10 
8/ 
12 
9/ 
14 
10/ 
16 
11/
18 
12/
20 
13/
22 
14/
24 
15/
26 
16/
28 
17/
30 
18/
32 
19/
34 
20/
36 
21/
38 
22/
40 
23/
42 
24/
44 
25/
46 
26/
48 
27/
50 
28/
52 
ET 
SFU b 
Written Informed 
consent 
X  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Inclusion/ 
exclusion 
X 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Demographic data 
c 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Psoriatic arthritis 
history 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Significant past 
medical history 
and concomitant 
diseases 
X 
X d 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Prior medication 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Concomitant 
medication 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
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 
eC-SSRS 
X 
X 
  
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
X 
X 
Height e 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Weight e 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
Vital signs f 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
X 
X 
ECG by central 
reader 
X 
 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
X 
X 
Hematology/ 
biochemistryg 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
X 
X 

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Table 5-1: 
Schedule of study assessments 
     Visit a/ 
Week 
 
Protocol activity 
Screening (V1) 
Baseline (Day 1) 
(first dose) (V2) 
Double-Blind Treatment Period 
(weeks after first dose) 
Active Treatment-Blind Period 
(weeks after first dose) 
 
 
3/ 
2 
4/ 
4 
5/ 
6 
6/ 
8 
7/ 
10 
8/ 
12 
9/ 
14 
10/ 
16 
11/
18 
12/
20 
13/
22 
14/
24 
15/
26 
16/
28 
17/
30 
18/
32 
19/
34 
20/
36 
21/
38 
22/
40 
23/
42 
24/
44 
25/
46 
26/
48 
27/
50 
28/
52 
ET 
SFU b 
hs-CRP h 
X 
X 
X 
X 
 
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 
Urinalysis 
X 
X 
 
 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
X 
 
 
 
X 
 
 
 
X 
 
X 
X 
X 
Urine drug screen 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hepatitis B and C 
testing 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HIV testing 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HLA-B27 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
RF and anti-CCP 
antibodies 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Blood sample for 
bimekizumab 
plasma 
concentrationsj 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
Anti-
bimekizumab 
antibody 
detectionj 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
Serum and plasma 
blood samples for 
exploratory 
biomarkersj 
 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
RNA blood 
samples for 
exploratory 
biomarkersj 
 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Table 5-1: 
Schedule of study assessments 
     Visit a/ 
Week 
 
Protocol activity 
Screening (V1) 
Baseline (Day 1) 
(first dose) (V2) 
Double-Blind Treatment Period 
(weeks after first dose) 
Active Treatment-Blind Period 
(weeks after first dose) 
 
 
3/ 
2 
4/ 
4 
5/ 
6 
6/ 
8 
7/ 
10 
8/ 
12 
9/ 
14 
10/ 
16 
11/
18 
12/
20 
13/
22 
14/
24 
15/
26 
16/
28 
17/
30 
18/
32 
19/
34 
20/
36 
21/
38 
22/
40 
23/
42 
24/
44 
25/
46 
26/
48 
27/
50 
28/
52 
ET 
SFU b 
Blood samples for 
genetic/ 
epigenetic 
analysis j 
 
X 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
IGRA 
tuberculosis test 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
 
 
 
 
Tuberculosis 
questionnaire 
X 
X 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
Physical 
examinationk 
X 
X 
 
 
 
 
 
X 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
BSA affected by 
PSO l 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
PASIm 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
IGAm 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
TJC and SJC 
X 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
X 
X 
HAQ-DI 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
PtAAP 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
PhGA-PsA 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
PhGA-Arthritis 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
PGA-PsA 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
PGA-Arthritis 
 
X 
X 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
X 
X 
X 
BASDAI 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
mNAPSIn  
 
X 
 
X 
 
X 
 
X  
 
X 
 
 
 
X 
 
 
 
 
 
X  
 
 
 
 
 
 
 
X  
X  
 

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Table 5-1: 
Schedule of study assessments 
     Visit a/ 
Week 
 
Protocol activity 
Screening (V1) 
Baseline (Day 1) 
(first dose) (V2) 
Double-Blind Treatment Period 
(weeks after first dose) 
Active Treatment-Blind Period 
(weeks after first dose) 
 
 
3/ 
2 
4/ 
4 
5/ 
6 
6/ 
8 
7/ 
10 
8/ 
12 
9/ 
14 
10/ 
16 
11/
18 
12/
20 
13/
22 
14/
24 
15/
26 
16/
28 
17/
30 
18/
32 
19/
34 
20/
36 
21/
38 
22/
40 
23/
42 
24/
44 
25/
46 
26/
48 
27/
50 
28/
52 
ET 
SFU b 
LEI 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
SPARCC 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
LDIo 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
PsAQoL 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
PsAID-12 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
 
FACIT-Fatigue 
subscale 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
 
SF-36 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
X 
EQ-5D-3L 
 
X 
 
X 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
X 
 
 
 
 
 
 
 
X 
X 
 
WPAI-SHP 
 
X 
 
 
 
 
 
 
 
X 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
X 
 
Chest x-rayp 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X-ray of hands 
and feetq 
X 
 
 
 
 
 
 
 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
X 
 
Adverse eventsr 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
IXRSs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
IMP 
administrationt,u 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
 

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Table 5-1: 
Schedule of study assessments 
     Visit a/ 
Week 
 
Protocol activity 
Screening (V1) 
Baseline (Day 1) 
(first dose) (V2) 
Double-Blind Treatment Period 
(weeks after first dose) 
Active Treatment-Blind Period 
(weeks after first dose) 
 
 
3/ 
2 
4/ 
4 
5/ 
6 
6/ 
8 
7/ 
10 
8/ 
12 
9/ 
14 
10/ 
16 
11/
18 
12/
20 
13/
22 
14/
24 
15/
26 
16/
28 
17/
30 
18/
32 
19/
34 
20/
36 
21/
38 
22/
40 
23/
42 
24/
44 
25/
46 
26/
48 
27/
50 
28/
52 
ET 
SFU b 
BASDAI=Bath Ankylosing Spondylitis Disease Activity Index; BP=blood pressure; BSA=body surface area; CASPAR=Classification Criteria for Psoriatic 
Arthritis; CCP=cyclic citrullinated peptide; eC-SSRS=electronic Columbia-Suicide Severity Rating Scale; ECG=electrocardiogram; EQ-5D-3L=EuroQol-5-
Dimensions-3 Level; ET=Early Termination; FACIT=Functional Assessment of Chronic Illness Therapy; HAQ-DI=Health Assessment Questionnaire—
Disability Index; HDL=high density lipoprotein; HIV=human immunodeficiency virus; HLA-27=human leukocyte antigen B27; hs-CRP=high sensitivity C-
reactive protein; IGA=Investigator’s Global Assessment; IGRA=interferon gamma release assay; IMP=investigational medicinal product; IXRS=interactive 
voice or web response system; LDI=Leeds Dactylitis Index; LDL=low density lipoprotein; LEI=Leeds Enthesitis Index; mNAPSI=modified Nail Psoriasis 
Severity Index; PASI=Psoriasis Area and Severity Index; PGA-Arthritis=Patient’s Global Assessment of Arthritis; PGA-PsA=Patient’s Global Assessment of 
Psoriatic Arthritis; PhGA-Arthritis=Physician’s Global Assessment of Arthritis; PhGA-PsA=Physician’s Global Assessment of Psoriatic Arthritis; PHQ-
9=Patient Health Questionnaire-9; PsA=psoriatic arthritis; PsAID-12=Psoriatic Arthritis Impact of Disease-12; PsAQoL=Psoriatic Arthritis Quality of Life; 
PSO=psoriasis; PtAAP=Patient’s Assessment of Arthritis Pain; Q2W=every 2 weeks; Q4W=every 4 weeks; RF=rheumatoid factor; RNA=ribonucleic acid; 
SF-36= Short-Form 36-item Health Survey; SFU=Safety Follow-Up; SJC=swollen joint count; SPARCC= Spondyloarthritis Research Consortium of Canada; 
TB=tuberculosis; TJC=tender joint count; vdHmTSS=Van der Heijde modified Total Sharp Score; V=Visit; WPAI-SHP=Work Productivity and Activity 
Impairment Questionnaire–Specific Health Problem 
a Visit windows of ±2 days are allowed for all visits up to Week 16 and ±3 days are allowed for all visits after Week 16. The time between study treatment doses 
should be ≥12 days and ≤16 days or ≥11 days and ≤17 days, respectively. For the SFU Visit, 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). 
b Safety Follow-Up Visit occurs 20 weeks after the final dose of IMP for all subjects who complete the study and do not enter the extension study or who 
discontinue early, including those withdrawn from IMP. 
c A complete history of lifestyle (alcohol, drug, and nicotine consumption at the time of Screening) and infections (fungal skin infections within 12 months prior 
to Screening). 
d Confirm there are no significant changes in medical history that would exclude the subject based on the exclusion criteria. 
e The Investigator or designee will measure the height of the subject with shoes removed in meters and the weight of the subject in kilograms. 
f Collect vital signs (pulse, BP, and temperature) prior to IMP administration and then at approximately 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. 
g Biochemistry testing will include triglycerides, cholesterol, HDL cholesterol, and LDL cholesterol at Baseline, Weeks 12 and 24, and at the ET Visit. 
h After Baseline, the hs-CRP data will not be sent to the Investigator to protect the blinded nature of the treatment assignments. 
i Pregnancy testing will consist of serum testing at Screening for all women of childbearing potential. The pregnancy test will be urine at all other visits.  
j At dosing visits, all blood samples are taken prior to dosing. Blood samples for bimekizumab and anti-bimekizumab antibody detection will be processed as per 
instructions in the laboratory manual. 

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Table 5-1: 
Schedule of study assessments 
     Visit a/ 
Week 
 
Protocol activity 
Screening (V1) 
Baseline (Day 1) 
(first dose) (V2) 
Double-Blind Treatment Period 
(weeks after first dose) 
Active Treatment-Blind Period 
(weeks after first dose) 
 
 
3/ 
2 
4/ 
4 
5/ 
6 
6/ 
8 
7/ 
10 
8/ 
12 
9/ 
14 
10/ 
16 
11/
18 
12/
20 
13/
22 
14/
24 
15/
26 
16/
28 
17/
30 
18/
32 
19/
34 
20/
36 
21/
38 
22/
40 
23/
42 
24/
44 
25/
46 
26/
48 
27/
50 
28/
52 
ET 
SFU b 
k Includes evaluation of signs and symptoms of active TB and risk for exposure to TB.  
l Any subject with PSO lesions at Baseline will have a BSA-PSO assessment (Section 9.8.1) at each scheduled visit.  
m Only subjects with a BSA of ≥3% at Baseline will be required to have the PASI and IGA assessed at selected visits post Baseline (Day 1). 
n Only for subjects who have nail PSO at Baseline. 
o Circumference measured in millimeters. 
p If a subject has had a radiograph of the chest within 3 months prior to the Screening Visit, it may be used as the Screening chest x-ray. 
q The x-ray at Screening will be used for CASPAR classification (for inclusion) and will serve as the Baseline x-ray for assessment of the degree of joint damage, 
which will be assessed using the vdHmTSS (Van der Heijde et al, 2005). 
r  Adverse events are to be collected beginning at the signing of the Informed Consent form. 
s The IXRS will be used to register subjects at Screening, to randomize eligible subjects to treatment groups at Baseline (Day 1), to reallocate subjects (at 
Week 16) in the placebo group, and to register visits. 
t Bimekizumab subjects will be administered bimekizumab at Baseline, Week 4, and Q4W thereafter. The subjects will also receive dummy treatments at 
Week 2, and Q4W thereafter, in order to preserve the blind. Adalimumab subjects will be administered with adalimumab at Baseline, Week 2, and Q2W 
thereafter. Placebo will be administered at Baseline, Week 2, and Q2W thereafter to preserve blinding and correspond to the dosing schedule for adalimumab. 
For details of bimekizumab and adalimumab doses, see Section 7.2. 
u At Week 16 after all assessments are complete, the Active Treatment-Blind Period dosing will start as detailed in Section 5.3.2, at which point no subjects will 
be in the placebo group, but will still be administered placebo to maintain blind. 
.

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5.10 
Schematic diagram 
The study schematic PA0010 is presented in Figure 5-1.  
Figure 5-1: Study schematic diagram 
 
ACR50=American College of Rheumatology 50% response criteria; BKZ=bimekizumab; PsA=psoriatic arthritis; 
Q2W=every 2 weeks; Q4W=every 4 weeks; sc=subcutaneous; SFU=Safety Follow-Up; W=week 
a Adalimumab dosing is presented in Section 7.2.  
b After 16 weeks of double-blind treatment, subjects will enter the Active Treatment-Blind Period. All subjects 
randomized to placebo will be reallocated to receive bimekizumab 160mg Q4W. Subjects randomized to 
bimekizumab 160mg Q4W will continue to receive their originally randomized dose. Subjects randomized to 
active-reference (adalimumab) will continue with their active treatment.  
c Permitted rescue therapy is defined in Section 5.4. 
5.11 
Rationale for study design and selection of dose 
Bimekizumab 
Bimekizumab doses of 16mg, 160mg, 160mg with an initial 320mg dose, and 320mg were 
evaluated in PA0008, a Phase 2b multicenter, randomized, double-blind, placebo-controlled, 
parallel group, dose-ranging study. In this study, doses up to 320mg were well tolerated by 
subjects and found to have acceptable safety profile.  
PA0010 will evaluate the efficacy and safety of bimekizumab 160mg sc Q4W in adult subjects 
with active PsA. The dose was selected based on the data from Phase 2b study. In PA0008, both 
ACR50 and PASI90 responder rates saturate at bimekizumab 160mg Q4W, further increase in 
dose does not provide a significant benefit on either ACR50 or PASI90 responder rates. This 

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plateau at bimekizumab 160mg was further confirmed based on the observed noncontrolled 
Week 48 data, which demonstrated a similar ACR50 and PASI90 response between 160mg and 
320mg Q4W at Week 48. An exposure-response analysis was performed on both endpoints 
which also indicated that bimekizumab 160mg Q4W is the optimal dose for these patients.  
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 PA0008 for the 
Phase 3 program in PsA. 
Adalimumab 
Adalimumab is approved and indicated for the treatment of active and progressive PsA in adults 
when the response to previous DMARD therapy has been inadequate. The recommended dose of 
adalimumab for patients with PsA is 40mg adalimumab administered Q2W as a single dose via 
sc injection. Available data suggest that the clinical response is usually achieved within 12 weeks 
of treatment. Adalimumab dosing schedules are provided in Section 7.2.  
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 at Screening 
and be reconfirmed at the Baseline Visit: 
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. 
4. 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 Screening and immediately prior to the 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, or implantable) 
− intrauterine device  

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− intrauterine hormone-releasing system  
− 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.  
5. Subject has a documented diagnosis of adult-onset PsA classified and meets the CASPAR 
classification criteria (Table 18-1) for at least 6 months prior to Screening with active PsA 
and must have at Baseline TJC ≥3 out of 68 and SJC ≥3 out of 66 (dactylitis of a digit counts 
as 1 joint each).  
6. Subject must be negative for rheumatoid factor and anti-cyclic citrullinated peptide (CCP) 
antibodies.  
7. Subject must have at least 1 active psoriatic lesion(s) and/or a documented history of PSO. 
8. Subject must be considered, in the opinion of the Investigator, to be a suitable candidate for 
treatment with adalimumab per regional labeling and has no contraindications to receive 
adalimumab as per the local label. 
9. Subjects who are regularly taking NSAIDs/COX-2 inhibitors or analgesics (including mild 
opioids) as part of their PsA therapy are required to be on a stable dose/dose regimen for at 
least 14 days before Baseline and should remain on a stable dose until Week 16. 
10. Subjects taking oral corticosteroids must be on an average daily dose of ≤10mg/day 
prednisone or equivalent for at least 14 days before Baseline and should remain on a stable 
dose until Week 16. 
11. Subjects taking MTX (≤25mg/week) are allowed to continue their medication if started at 
least 12 weeks prior to Baseline, with a stable dose for at least 8 weeks before randomization. 
Dose, dosing schedule and route of administration (oral or sc) should remain stable until 
Week 16. It is strongly recommended that subjects taking MTX are also taking folic acid 
supplementation. 
12. Subjects taking 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 
for at least 8 weeks before randomization. Dose and dosing schedule should remain stable 
until Week 16. 
13. Subjects taking SSZ (up to 3g/day, for arthritis or 4g/day if in accordance with local standard 
of care, HCQ (up to 400mg/day), or apremilast (up to 60mg/day and dosed as per local label) 
are allowed to continue their medication if started 8 weeks prior Baseline, with a stable dose 
for at least 4 weeks before randomization. Dose and dosing schedule should remain stable 
until Week 16. 
6.2 
Exclusion criteria 
Subjects are not permitted to enroll in the study if any of the following criteria are met: 
1. Female subjects who are breastfeeding, pregnant, or plan to become pregnant during the 
study or within 20 weeks following last dose of IMP.  

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2. Subjects with current or prior exposure to any biologics for the treatment of PsA or PSO, 
including participation in a bimekizumab clinical study who received at least 1 dose of IMP 
(including placebo). 
3. Subject previously participated in another study of a medication (systemic) under 
investigation. Subject must be washed out of the medication for 12 weeks or at least 
5 half-lives 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 PA0011. 
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 or adalimumab.  
6. Subject is taking or has taken prohibited PsA or PSO medications without meeting the 
mandatory wash-out period relative to the Baseline Visit (Table 7-2 and Table 7-3).  
7. 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, herpes zoster). 
8. 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 is defined as:  
• positive for hepatitis B surface antigen; or,  
• positive for anti-hepatitis B core antibody  
A positive test for the hepatitis C virus (HCV) is defined as:  
• positive for hepatitis C antibody (anti-HCV antibody), and  
• positive via a confirmatory test for HCV (for example, HCV polymerase chain reaction) 
9. Subject has received any live (includes attenuated) vaccination within the 8 weeks prior to 
the Baseline (eg, inactivated influenza and pneumococcal vaccines are allowed, but nasal 
influenza vaccination is not permitted). 
10. Subject has received Bacillus Calmette-Guerin (BCG) vaccinations within 1 year prior to the 
Baseline Visit. 

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11. Subject has known tuberculosis (TB) infection, is at high risk of acquiring TB infection, or 
has current or history of nontuberculous mycobacterium (NTMB) infection. A subject with 
latent tuberculosis (LTB) (a positive interferon gamma 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 (LTBI) 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/Center for Disease Control and Prevention 
therapeutic guidance and proven to be fully recovered upon consult with a TB specialist. 
Refer to Section 12.3.5 for details on determining full TB exclusion criteria. 
12. Subject has a history of a lymphoproliferative disorder including lymphoma and/or current 
signs and symptoms suggestive of lymphoproliferative disease. 
13. Subject has a diagnosis of inflammatory conditions other than PSO or PsA including, but not 
limited to RA, sarcoidosis, systemic lupus erythematosus, and reactive arthritis. Subjects 
with a diagnosis of Crohn’s disease, ulcerative colitis, or other inflammatory bowel disease 
(IBD) are allowed as long as they have no active symptomatic disease at Screening or 
Baseline. 
14. Subject had acute anterior uveitis within 6 weeks of Baseline. 
15. Subjects with fibromyalgia or osteoarthritis symptoms that in the Investigator’s opinion 
would have potential to interfere with efficacy assessments. 
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. 
17. Subject has a form of PSO other than chronic plaque-type (eg, pustular, erythrodermic and 
guttate PSO, or drug-induced PSO). 
18. Subject has had major surgery (including joint surgery) within the 3 months prior to 
Baseline, or planned surgery within 6 months after entering the study. 
19. Subject has any systemic disease (ie, cardiovascular, neurological, renal, liver, metabolic, GI, 
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. ≥3x 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 count <3.0x103/μL 
c. Absolute neutrophil count <1.5x103/μL 
d. Lymphocyte count <500 cells/μL 

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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: 
− Subject has a 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 professional (eg, locally licensed psychiatrist, psychologist, or 
master’s level therapist) before enrolling into the study. 
− Subject has 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  
24. Subject has presence of 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. Subjects taking PsA medications other than MTX, SSZ, apremilast, HCQ, LEF, 
NSAIDs/COX-2 inhibitors, and oral corticosteroids as outlined in the Inclusion criteria 
(Section 6.1). Stable doses/regimens of analgesics are also permitted. 
26. Subject has a history of chronic alcohol or drug abuse within 6 months prior to Screening 
evaluated by the Investigator based on medical history, site interview, and results of the 
specified urine drug screen. 
27. 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. 
28. Subject is a UCB employee or is an employee of third-party organizations involved in the 
study. 

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6.3 
Withdrawal criteria 
Subjects are free to withdraw from the study at any time, without prejudice to their continued 
care. Subjects who withdraw from the study should complete the Early Termination Visit (see 
Section 8.3).  
Subjects should be withdrawn from the study and will be asked to come back for the SFU Visit 
20 weeks after the final dose of IMP if the subject withdraws his/her consent. 
Subjects should be withdrawn from IMP and will be asked to come back for all scheduled visits 
(up to Week 52) and the SFU Visit 20 weeks after the final dose of IMP 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 with IMP outweighs the potential 
benefit. 
3. Subject is noncompliant with the study procedures or medications, which may present a risk 
to the safety of the subject, in the opinion of the Investigator. 
4. Subject uses prohibited concomitant medications, as defined in Section 7.8.2, that may 
present a risk to the safety of the subject in the opinion of the Investigator and 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 <1.0x103/μL 
− Absolute lymphocyte count <0.2x103/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, 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. 
7. There is confirmation of a pregnancy during the study, as evidenced by a positive pregnancy 
test (see Section 12.1.4 for more information regarding pregnancies). 
8. Subject develops erythrodermic, guttate or generalized pustular form of PSO. 
9. A subject considered as having either a suspected new LTBI 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. 

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The subject must be permanently withdrawn if further examinations result in a diagnosis of 
active TB, or if the subject is diagnosed with 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 electronic Case Report form 
(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 12.3.5. 
10. Subjects with newly diagnosed IBD or with IBD flares during the study must: 
− Be referred, as appropriate, to a health care 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 judgment 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. 
11. 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: 
a. Active suicidal ideation as indicated by a positive response (“Yes”) to Question 4 of the 
“Since Last Visit” version of the eC-SSRS.  
b. 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 last visit. 
The mental health consultation must be recorded in the subject’s source documentation. 
12. Subjects must be referred immediately to a mental health care professional and must be 
withdrawn from the study: 
a. Active suicidal ideation as indicated by a positive response (“Yes”) to Question 5 of the 
“Since Last Visit” version of the eC-SSRS. 
b. Any suicidal behavior since the last visit.  
c. Severe major depression as indicated by a PHQ-9 score ≥20. 
The mental health consultation must be recorded in the subject’s source documentation. 
13. 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. 

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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. 
Investigators should attempt to obtain information on subjects in the case of withdrawal or 
discontinuation. 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. 
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:  
• Subjects with either of the following: 
− ALT or AST ≥8xULN 
− 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 12.2.1.2.1 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 12.2.1 with repeat tests performed 
in 2 weeks. Upon retest, if ALT or AST values have reduced to <5xULN, the subject can 
continue with the study. However, if ALT or AST remains ≥5xULN <8xULN after retest, IMP 
should be temporarily withheld and subject should undergo a repeat test in 2 weeks. The subject 
will continue to be monitored at least twice per week until values normalize, stabilize, or return 
to within baseline values. If ALT or AST values remain ≥5xULN even after the second retest, 
then the subject should be permanently withdrawn from the study and should be followed for 
possible PDILI.  
If subjects are unable to comply with the applicable monitoring schedule, IMP must be 
discontinued immediately. 

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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. 
7 
STUDY TREATMENTS 
7.1 
Description of investigational medicinal products 
The IMPs used in this study are bimekizumab, adalimumab, and placebo. 
• Bimekizumab will be supplied in a 1mL PFS. Each single-use syringe contains bimekizumab 
drug substance at a nominal formulation of 160mg/mL in 
mM sodium acetate, 
mM 
glycine, and 
% polysorbate 80 at pH 
 for sc injection. 
• 
 
 
• 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. 
Further details of the IMPs and their specifications will be provided in the IMP Handling 
Manual.  
7.2 
Treatments to be administered 
The IMPs are to be administered in the clinic by unblinded study site staff. At all visits, only a 
single sc injection would be administered. Suitable areas for sc injections are the lateral 
abdominal wall 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. 
The IMP dosing scheme is presented in Table 7-1. 

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Table 7-1: 
Dosing scheme 
 
 
Week 
 
Protocol 
activity 
Baseline  
(first dose) 
Double-Blind Treatment Period 
Active Treatment-Blind Period 
2 
4 
6 
8 
10 
12 
14 
16 
18 
20 
22 
24 
26 
28 
30 
32 
34 
36 
38 
40 
42 
44 
46 
48 
50 
Bimekizumab 
160mg sc Q4W 
● 
 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
 
○a 
Adalimumab 
40mg 
▲ 
 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
▲ 
 
▲
a 
Placebo 
○ 
 
○ 
○ 
○ 
○ 
○ 
○ 
○ 
● b 
○ 
● 
○ 
●  
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
○ 
● 
 
○a 
Note: A bimekizumab 160mg Q4W dose injection is depicted by a black circle (●). A placebo injection is depicted by a white circle (○). An adalimumab 40mg 
injection is depicted by a black triangle (▲).  
a Subjects that continue to the extension study will receive their final dose of IMP. 
b Placebo subjects reallocated to bimekizumab 160mg sc Q4W (follow applicable schedules noted above). 
  
 

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7.3 
Packaging 
The IMPs are manufactured, packaged, and labeled according to Good Manufacturing Practice 
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 Products must be stored under refrigerated conditions (2ºC to 8ºC) 
protected from light. The IMPs 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 
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 that does not correlate to the contents and, 
therefore, does not unblind study site staff. 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. 
The Investigator (or designee) is responsible for retaining all used, unused, and partially used 
containers of IMP until returned or destroyed. 
The Investigator must 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 

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destroyed at the site according to local laws, regulations, and UCB standard operating procedures 
(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 
Bimekizumab, adalimumab, and placebo will be administered in the clinic and compliance will 
be determined at the visit by unblinded study personnel. Drug accountability must be recorded 
by unblinded study personnel on the Drug Accountability form. 
7.8 
Concomitant medications/treatments 
All concomitant medications, including over-the-counter products, herbal, traditional remedies, 
vitamin/mineral supplements, other dietary supplements, “nutraceuticals,” and hormones must be 
recorded in the subject’s source documentation (eg, clinical chart) and in 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. 
7.8.1 
Permitted concomitant treatments (medications and therapies) 
No medication increases or additions are permitted for medications taken for PsA until Week 16. 
However, a decrease in dose or dosing frequency of any agent is permitted for reasons of 
intolerance/AEs/side-effects at any time. 
After Week 16, background medication changes are permitted at the Investigator’s discretion if 
the subject is considered to be not responding adequately. Permitted rescue therapy is described 
in Section 5.4. 
Subjects are allowed to use acetaminophen/paracetamol and mild opioids as needed, except 
within 24 hours of a visit with disease activity assessment. 
Subjects who are already receiving an established antidepressant regimen should be on a stable 
dose of the antidepressant for 8 weeks prior to Baseline. 
Subjects are allowed to use any other medications, including biologics, after at least 28 days of 
last dose of the IMP. This is applicable for subjects who discontinue from IMP or 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. 
7.8.1.1 
Psoriasis treatments 
For treatment of PSO, subjects may continue to use topical moisturizers, emollients, salicylic 
acid preparations, bath oils, and oatmeal bath preparations for skin conditions during the study, 
as needed. Over-the-counter shampoos for the treatment of PSO of the scalp are also permitted. 
Additionally, mild topical steroids are permitted for use limited to the face, axillae, and/or 
genitalia, as needed. Subjects who use prohibited topical medications will be allowed to stay in 
the study but will counseled to not use them further. No other topical preparations are allowed in 
the 2 weeks prior to randomization or during the study unless medically required to treat an AE. 
See Table 7-3 for prohibited PSO medications. 
After the Week 16 Visit, the addition of topical retinoids, vitamin D analogues, coal tar 
preparations, and more potent topical steroids may be used as medically required to treat a flare 
but are not permitted to be used within 24 hours prior to a study visit. Use of psoralen and 

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ultraviolet A light (PUVA/UVA) therapy for the treatment of PSO is not permitted for the first 
16 weeks of the study and is discouraged through the duration of the study. 
7.8.2 
Prohibited concomitant treatments (medications and therapies) 
Prohibited and/or restricted medications are summarized in Table 7-2 and Table 7-3. 
Table 7-2: 
Prohibited or restricted medications and required wash-out 
periods 
Drug class 
Dose 
Exclusion/Washout 
Analgesics, including mild 
opioid analgesics, 
acetaminophen/paracetamol, 
etc. 
Any dose  
Any ad hoc use in the 24 hours prior to any study 
visit.  
 
Stable doses of analgesics are permitted. 
NSAIDs/COX-2 inhibitors 
Any dose 
regimen 
Any change in dose/dose regimen in the 14 days 
prior to the Baseline Visit 
Oral corticosteroids 
Any dose 
regimen 
Any change in dose/dose regimen in the 14 days 
prior to the Baseline Visit. 
Intramuscular/intravenous 
/intra-articular 
corticosteroids  
Any dose  
Use in the 28 days prior to the Baseline Visit and 
during the study. 
Intra-articular hyaluronic 
acid  
Any dose  
Use in the 6 months prior to the Baseline Visit. 
DMARDs: 
-azathioprine,  
-cyclosporine,  
-cyclophosphamide,  
-mycophenolic acid 
-mycophenolate mofetil 
-any other nonpermitted 
small molecule DMARDs 
(eg, tofacitinib) 
Any dose 
Use within 8 weeks prior to the Baseline Visit and 
during the study. 
-apremilast a 
Any dose 
Use within 8 weeks prior to the Baseline Visit 
unless Inclusion Criterion #13 is met.  
-hydroxychloroquine a 
Any dose 
Use within 8 weeks prior to the Baseline Visit 
unless Inclusion Criterion #13 is met.  
-sulfasalazine a 
Any dose 
Use within 8 weeks prior to the Baseline Visit 
unless Inclusion Criterion #13 is met.  

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Table 7-2: 
Prohibited or restricted medications and required wash-out 
periods 
Drug class 
Dose 
Exclusion/Washout 
-methotrexate a 
Any dose 
regimen 
Initiation less than 12 weeks prior to the Baseline 
Visit unless Inclusion Criterion #11 is met.  
Administration of LEF and MTX together is not 
permitted at any time during the study. 
-leflunomide a 
Any dose 
Use in the 6 months prior to the Baseline Visit, 
unless (1) a cholestyramine washout has been 
performed, in which case, use up to 28 days prior 
to the Baseline Visit is acceptable or (2) Inclusion 
Criterion #12 is met. 
Any bDMARDs 
Any dose 
Any exposure history. 
COX-2=cyclooxygenase-2; CZP=certolizumab pegol; bDMARD=biological disease modifying antirheumatic 
drug; DMARD=disease modifying antirheumatic drug; ETN=etanercept; GOL=golimumab; 
HCQ=hydroxychloroquine; IFX=infliximab; LEF=leflunomide; MTX=methotrexate; NSAID=nonsteroidal 
anti-inflammatory drug; SSZ=sulfasalazine 
a Permitted as per Section 5.4. 
 
Table 7-3 
Additional prohibited psoriasis treatments 
Drug class 
Dose 
Exclusion criteria 
Phototherapy 
Any dose 
Use within the 28 days prior to the 
Baseline Visit. 
Topical corticosteroids for dermatological 
use except as detailed in Section 7.8.1, 
vitamin D analogues, topical retinoids, 
keratolytics, coal tar, and fumaric acid 
esters 
Any dose 
Use within 14 days prior to the 
Baseline Visit. 
Systemic retinoids 
Any dose 
Use within 3 months prior to the 
Baseline Visit. 
7.8.3 
Vaccines 
Administration of live (including attenuated) vaccines is not allowed during the conduct of the 
study and for 20 weeks after the final dose IMP (see exclusion criteria, Section 6.2). 
Administration of inactivated vaccines is allowed during the study at the discretion of the 
Investigator.  
7.9 
Blinding 
Due to differences in presentation between the bimekizumab, adalimumab, and placebo 
treatments, special precautions will be taken to ensure study blinding and study sites will have 
blinded and unblinded personnel. 

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As per dosing schedule for adalimumab (see Section 7.2), all subjects must come to the study 
center for IMP administration at Baseline, Week 2, Week 4, and then Q2W thereafter. 
For subjects receiving bimekizumab, bimekizumab will be administered at Baseline and Q4W 
thereafter; dummy/placebo treatments at Week 2 and Q4W thereafter to preserve blinding and 
correspond to the dosing schedule for adalimumab. Adalimumab subjects will receive 
adalimumab at Baseline and Q2W thereafter. Details of the interim sensitivity analysis to 
examine any treatment biases are provided in Section 14.3.2. 
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 voice or web 
response system (IXRS) system. 
Additional information on procedures to maintain the treatment blind after the 24-week and 
52-week interim analyses is provided in Section 14.8.1. 
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 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 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. 
To enroll a subject, the Investigator or designee will contact the IXRS and provide brief details 
about the subject to be enrolled. Each subject will receive a 5-digit number assigned at Screening 
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. Subject numbers and kit numbers will be tracked via the IXRS. 
Eligible subjects will be randomized to treatment groups at Baseline (Day 1). To randomize a 
subject, the Investigator or designee will contact the IXRS and provide brief details about the 
subject to be randomized. The IXRS will automatically inform the Investigator or designee of the 
subject’s randomization number. The IXRS will allocate kit numbers to the subject based on the 
subject number during the course of the study. The randomization number must be documented 
into the eCRF. 

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After 16 weeks of double-blind treatment, subjects who were randomized to placebo will be 
reallocated to bimekizumab 160mg sc Q4W. Subjects randomized to bimekizumab160mg sc 
Q4W will continue to receive their originally randomized dose. Subjects randomized to 
adalimumab 40mg Q2W will continue with their reference treatment. 
8 
STUDY PROCEDURES BY VISIT  
The schedule of study assessments (Table 5-1) provides an overview of study assessments. A list 
of procedures to be completed at each visit is described below. Visit windows of ±2 days are 
allowed from the first dose at all visits through to Week 16. During the 16-week Double-Blind 
Period, the time between doses should be ≥12 days and ≤16 days. Visit windows of ±3 days are 
allowed for all visits after Week 16. The time between doses during the Active Treatment-Blind 
Period should be ≥11 days and ≤17 days. For the SFU Visit (20 weeks after the final dose of 
IMP), 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).  
Where local regulations permit, subjects will also be given the option to participate in the 
genomics, genetics, and proteomics substudy. Subjects agreeing to participate in the substudy 
will be required to complete a separate Informed Consent form (ICF). The ICF must be signed 
prior to collecting 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 PA0010 study. 
8.1 
Screening Period/Baseline 
8.1.1 
Screening 
The Screening Period will last for a minimum of 14 days 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 that has been approved by the Sponsor and an IRB/IEC, 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. 
The following procedures or assessments will be performed at the Screening Visit: 
• Obtain written informed consent 
• Assessment of inclusion and exclusion criteria 
• Collect demographic data 
• Collect PsA history 
• Collect significant past medical history and concomitant diseases 
• Record prior medications 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 

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• Vital signs 
• ECG by central reader 
• Collect samples for hematology and biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (serum) 
• Urinalysis  
• Urine drug screen 
• Collect samples for Hepatitis B and Hepatitis C testing  
• Collect samples for HIV testing 
• Collect samples for rheumatoid factor, anti-CCP antibodies 
• IGRA TB test 
• TB questionnaire 
• Physical examination 
• BSA affected by PSO 
• PASI (if the BSA affected by PSO is ≥3%) 
• Investigator’s Global Assessment (IGA)   
• Perform TJC and SJC 
• Chest x-ray 
• X-ray of hands and feet 
• AEs 
• IXRS 
8.1.2 
Baseline (Day 1) 
• Assessment of inclusion and exclusion criteria 
• Collect significant past medical history and concomitant diseases 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Height 
• Vital signs 
• Collect samples for hematology and biochemistry (including triglycerides, cholesterol, high 
density lipoprotein [HDL] cholesterol, and low-density lipoprotein [LDL] cholesterol) 

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• Collect samples for hs-CRP 
• Collect sample for HLA-B27 
• Pregnancy testing (urine) 
• Urinalysis  
• Blood sample for bimekizumab plasma concentrations  
• Blood sample for anti-bimekizumab antibody detection  
• Serum and plasma blood samples for exploratory biomarkers (participating subjects only) 
• RNA blood samples for exploratory biomarkers (participating subjects only) 
• Blood samples for genetic/epigenetic analysis (participating subjects only) 
• TB questionnaire 
• Physical examination 
• BSA affected by PSO using the BSA palm method 
• PASI (if the BSA affected by PSO is ≥3%) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 
• SPARCC 
• LDI 
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 

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• WPAI-SHP  
• AEs 
• IXRS (randomization) 
• IMP administration 
8.2 
Treatment Period 
8.2.1 
Double-Blind Treatment Period 
8.2.1.1 
Week 2 
• Record concomitant medications 
• Vital signs 
• Collect samples for hematology and biochemistry 
• Collect samples for hs-CRP 
• Blood sample for bimekizumab plasma concentrations 
• BSA affected by PSO  
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• AEs 
• IXRS 
• IMP administration 
8.2.1.2 
Week 4  
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology and biochemistry 

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• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Blood sample for bimekizumab plasma concentrations  
• Blood sample for anti-bimekizumab antibody detection  
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 
• SPARCC 
• LDI 
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 
• AEs 
• IXRS 
• IMP administration 

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8.2.1.3 
Weeks 6, 10, and 14 
• Record concomitant medications 
• IXRS 
• AEs  
• IMP administration 
8.2.1.4 
Week 8 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology and biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Blood sample for bimekizumab plasma concentrations 
• Blood sample for anti-bimekizumab antibody detection 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 
• SPARCC 
• LDI 
• AEs 

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• IXRS 
• IMP administration 
8.2.1.5 
Week 12 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Vital signs 
• Collect samples for hematology and biochemistry (including triglycerides, cholesterol, 
HDL cholesterol, and LDL cholesterol) 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Blood sample for bimekizumab plasma concentrations  
• Blood sample for anti-bimekizumab antibody detection  
• TB questionnaire 
• Physical examination 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 
• SPARCC 
• LDI  
• AEs 

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• IXRS 
• IMP administration 
8.2.1.6 
Week 16 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• ECG by central reader 
• Collect samples for hematology and biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Urinalysis  
• Blood sample for bimekizumab plasma concentrations 
• Blood sample for anti-bimekizumab antibody detection 
• Serum and plasma blood samples for exploratory biomarkers (participating subjects only) 
• RNA blood samples for exploratory biomarkers (participating subjects only) 
• Blood samples for genetic/epigenetic analysis (participating subjects only) 
• Physical examination 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 

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• SPARCC 
• LDI  
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 
• WPAI-SHP  
• X-ray of hands and feet 
• AEs 
• IXRS 
• IMP administration 
8.2.2 
Active Treatment-Blind Period 
After 16 weeks of double-blind treatment, subjects will enter the Active Treatment-Blind Period. 
Subjects in the placebo group will be reallocated to bimekizumab 160mg sc Q4W. Subjects 
randomized to receive bimekizumab or adalimumab during the Double-Blind Treatment Period 
will continue their Double-Blind Treatment Period regimen in the Active Treatment-Blind 
Period. After Week 16, rescue therapy will be permitted for all subjects at the Investigator’s 
discretion if the subject is judged to be not responding adequately. 
8.2.2.1 
Weeks 18 and 22 
• Record concomitant medications 
• IXRS 
• AEs  
• IMP administration 
8.2.2.2 
Week 20 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology and biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Blood sample for bimekizumab plasma concentrations 

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• Blood sample for anti-bimekizumab antibody detection 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• LEI 
• SPARCC 
• LDI  
• AEs 
• IXRS 
• IMP administration 
8.2.2.3 
Week 24 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Vital signs 
• Collect samples for hematology and biochemistry (including triglycerides, cholesterol, 
HDL cholesterol, and LDL cholesterol) 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Urinalysis 
• Blood sample for bimekizumab plasma concentrations  
• Blood sample for anti-bimekizumab antibody detection  
• TB questionnaire 
• Physical examination 

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• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC/SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 
• SPARCC 
• LDI  
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 
• WPAI-SHP  
• AEs 
• IXRS 
• IMP administration 
8.2.2.4 
Weeks 26, 30, 34, 38, 42, 46, and 50 
• Record concomitant medications 
• IXRS 
• AEs 
• IMP administration 

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8.2.2.5 
Week 28 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology/biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• AEs 
• IXRS 
• IMP administration 
8.2.2.6 
Week 32 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology/biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Urinalysis 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 

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• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• AEs 
• IXRS 
• IMP administration 
8.2.2.7 
Week 36 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Vital signs 
• Collect samples for hematology/biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Blood sample for bimekizumab plasma concentrations 
• Blood sample for anti-bimekizumab antibody detection 
• TB questionnaire 
• Physical examination 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 

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• LEI 
• SPARCC 
• LDI  
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 
• AEs 
• IXRS 
• IMP administration 
8.2.2.8 
Week 40 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology/biochemistry 
• Pregnancy testing (urine) 
• Urinalysis 
• Perform TJC and SJC 
• AEs 
• IXRS 
• IMP administration 
8.2.2.9 
Week 44 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology/biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 

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• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• AEs 
• IXRS 
• IMP administration 
8.2.2.10 
Week 48 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Vital signs 
• Collect samples for hematology/biochemistry 
• Pregnancy testing (urine) 
• Urinalysis 
• IGRA TB test 
• AEs 
• IXRS 
• IMP administration 
8.2.2.11 
Week 52 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Vital signs 
• ECG by central reader 
• Collect samples for hematology/biochemistry 
• Collect samples for hs-CRP 

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• Pregnancy testing (urine) 
• Urinalysis 
• Blood sample for bimekizumab plasma concentrations  
• Blood sample for anti-bimekizumab antibody detection  
• TB questionnaire 
• Physical examination 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• mNAPSI 
• LEI 
• SPARCC 
• LDI  
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 
• WPAI-SHP  
• X-ray of hands and feet 
• AEs 
• IXRS 

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At the completion of the Active Treatment-Blind Period, Investigators should discuss treatment 
options with the subject. Subjects will be given the opportunity to enter an extension study at 
Week 52. 
8.3 
Early Termination Visit 
Subjects withdrawing early from the study will undergo the following ET Visit assessments and 
will enter the SFU Period: 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Vital signs 
• ECG by central reader 
• Collect samples for hematology/biochemistry (including triglycerides, cholesterol, 
HDL cholesterol, and LDL cholesterol) 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Urinalysis 
• Blood sample for bimekizumab plasma concentrations 
• Blood sample for anti-bimekizumab antibody detection 
• TB questionnaire 
• Physical examination 
• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 

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• mNAPSI 
• LEI 
• SPARCC 
• LDI  
• PsAQoL 
• PsAID-12 
• FACIT-Fatigue subscale 
• SF-36 
• EQ-5D-3L 
• WPAI-SHP  
• X-ray of hands and feet 
• AEs 
• IXRS 
8.4 
Safety Follow-Up Visit (20 weeks [-3 days/+7 days] after the final 
dose) 
All subjects who complete the study and do not enter the extension study or who discontinue 
early, including those withdrawn from IMP, will have an SFU Visit 20 weeks after their final 
dose of IMP with the following assessments: 
• Record concomitant medications 
• PHQ-9 
• eC-SSRS 
• Weight 
• Vital signs 
• ECG by central reader 
• Collect samples for hematology/biochemistry 
• Collect samples for hs-CRP 
• Pregnancy testing (urine) 
• Urinalysis 
• Blood sample for bimekizumab plasma concentrations 
• Blood sample for anti-bimekizumab antibody detection 
• TB questionnaire 
• Physical examination 

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• BSA affected by PSO 
• PASI (if BSA affected by PSO is ≥3% at the Baseline [Day 1] visit) 
• IGA 
• Perform TJC and SJC 
• HAQ-DI 
• PtAAP 
• PhGA-PsA 
• PhGA-Arthritis 
• PGA-PsA 
• PGA-Arthritis  
• BASDAI 
• LEI 
• SPARCC 
• LDI  
• PsAQoL 
• SF-36 
• AEs 
• IXRS 
8.5 
Unscheduled Visits 
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 wellbeing.  
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 
reasons other than safety or efficacy concerns (eg, replacement of lost medication, 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, any of the following assessments may be performed, depending on the reason for 
the visit: 
• Record concomitant medication 
• eC-SSRS 
• Vital signs 
• ECG  
• Obtain urine sample for urine pregnancy test 

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• If indicated, obtain blood sample(s) for: 
− Standard safety laboratory tests (hematology/biochemistry)  
− Bimekizumab plasma concentrations and anti-bimekizumab antibody detection 
• An IGRA TB test 
• Physical examination 
• AEs 
9 
ASSESSMENT OF EFFICACY 
The ACR50 response at Week 16 is the primary efficacy variable. In addition, the ACR20 and 
ACR70 responses are secondary or other efficacy variables. Several assessments must be 
completed in order to determine the ACR response. These include the TJC and SJC based on 
68 and 66 joints, respectively, PGA-PsA, PhGA-PsA, PtAAP, HAQ-DI and hs-CRP. The 
methods for the component measures will be described first, followed by ACR response and 
assessments used in secondary and other efficacy variables.  
The timing for all assessments is specified in the schedule of study assessments (Table 5-1).  
9.1 
Joint assessments 
9.1.1 
68/66 joint evaluation for ACR response and verification of Inclusion 
Criterion 5 
The TJC/SJC, as recommended by ACR in RA, is the 68/66 count and it has since also been used 
in PsA studies; therefore, it will be utilized in this study. 
All joint assessments will be performed by an experienced independent evaluator who has had 
documented training on how to perform these assessments correctly. Preferably, the same 
evaluator should perform these assessment at all visits, as indicated in Table 5-1. The 
independent evaluator will not be involved in any other assessments. The following joints will be 
assessed for tenderness:  
• Upper body (6) - bilateral temporomandibular, sternoclavicular, and acromioclavicular joints 
• Upper extremity (34) - bilateral shoulders, elbows, wrists (includes radiocarpal, and carpal 
and carpometacarpal bones considered as a single unit), metacarpophalangeal (I, II, III, IV, 
and V), thumb interphalangeals, proximal interphalangeal (II, III, IV, and V), and distal 
interphalangeals (II, III, IV, and V). 
• Lower extremity (28) - bilateral hips, knees, ankles, tarsi (includes subtalar, transverse tarsal, 
and tarsometatarsal considered as a single unit), metatarsophalangeals (I, II, III, IV, and V), 
great toe interphalangeals, and proximal interphalangeals (II, III, IV, and V). 
All of these except for the hips are assessed for swelling.  
Artificial and ankylosed joints, as well as missing joints (ie, amputated joints), are excluded from 
both tenderness and swelling assessments.  
One dactylitic digit is to be counted as 1 swollen joint (instead of counting as 3 in the finger or 
2 in the toe). 

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Table 9-1 summarizes the swelling and tenderness grading criteria. 
Table 9-1: 
Swelling and tenderness grading 
Grade 
Tenderness response (68) 
Swelling response (66) 
0 
Not tender 
None 
1 
Tenderness present 
Detectable synovial thickening 
Data mapping from collected data to the grades listed in Table 9-1 will be described in the 
Statistical Analysis Plan (SAP). 
9.1.2 
28 joint evaluation for determination of DAS28(CRP) 
The following 28 joints will be used for calculation of the DAS28(CRP). 
• Upper extremity (26)-bilateral shoulders, elbows, wrists (includes radiocarpal, and carpal and 
carpometacarpal bones considered as a single unit), metacarpophalangeal joints I, II, III, IV, 
and V, thumb interphalangeals, proximal interphalangeal II, III, IV, and V  
• Lower extremity (2)-knees 
9.2 
ACR20, ACR50, and ACR70 response 
The ACR20, ACR50, and ACR70 response rates are based on a 20%, 50%, and 70% or greater 
improvement relative to Baseline in the following measures: 
• TJC based on 68 joints 
• SJC based on 66 joints 
• 3 of the 5 remaining core set measures: 
− PGA-PsA 
− PhGA-PsA 
− PtAAP 
− HAQ-DI 
− hs-CRP 
9.3 
Patient’s Global Assessments  
9.3.1 
Patient’s Global Assessment of Psoriatic Arthritis (PGA-PsA) 
The subject’s global assessment of PsA will be performed using a 100mm VAS scale where 0 is 
“very good, no symptoms” and 100 is “very poor, severe symptoms.” The subject will be asked 
the following question:  
“Considering all the ways your psoriatic arthritis affects you, please mark a vertical line on 
the scale below to show how well you are doing today.” 
The subject should be asked to consider all aspects of their disease (including joint and skin 
components) in their response to this question. 

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9.3.2 
Patient’s Global Assessment of Arthritis (PGA-arthritis) 
The subject’s global assessment of arthritis will be performed using a 100mm VAS scale where 
0 is “very good, no symptoms” and 100 is “very poor, severe symptoms.” The subject will be 
asked the following question: 
“Considering all the ways your arthritis affects you, please mark a vertical line on the scale 
below to show how you are feeling today.” 
The subject should be asked to consider their arthritis symptoms and functional capacity in their 
response to this question. 
9.4 
Physician’s Global Assessments 
These assessments will be performed by the Principal Investigator, another delegated physician 
or an appropriately trained medical professional (based on local requirements) who has 
documented training on how to perform these assessments correctly. The assessments should be 
made blind to the PGA-PsA and PGA-Arthritis assessments. 
9.4.1 
Physician’s Global Assessment of Psoriatic Arthritis (PhGA-PsA) 
The Investigator or delegate will assess the overall status of the subject with respect to their PsA, 
which may include any element of the disease and may include arthritis, PSO, enthesitis, 
dactylitis, or spondylitis. This will be assessed using a 100mm VAS scale where 0 is “very good, 
asymptomatic and no limitation of normal activities” and 100 is “very poor, very severe 
symptoms which are intolerable and inability to carry out all normal activities”. The Investigator 
or delegate will be asked the following question: 
“Considering all the ways the disease affects your patient, mark a vertical line on the scale 
for how well his or her condition is today.”  
9.4.2 
Physician’s Global Assessment of Arthritis (PhGA-Arthritis) 
The Physician or delegate will assess how the subject’s overall arthritis appears at the time of the 
visit. This is an evaluation based on the subject’s disease signs, functional capacity, and physical 
examination using a 100mm VAS scale where 0 is “very good” and 100 is “very poor”. The 
physician will be asked to mark the Patient’s arthritis:  
The Patient’s arthritis at this time is:  
“Please mark a vertical line on the scale below to assess the overall status of the subject’s 
arthritis signs and symptoms and the functional capacity of the subject.”  
Very Good--------------------------------------------------------Very Poor 
9.5 
Patient’s Assessment of Arthritis Pain (PtAAP) 
The PtAAP VAS or ‘Pain VAS’ is part of the ACR core set of measures in arthritis 
(Felson et al, 1993). Subjects will assess their arthritis pain using a VAS where 0 is “no pain” 
and 100 is “most severe pain.”  

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9.6 
Health Assessment Questionnaire-Disability Index score 
(HAQ-DI)  
The HAQ-DI contains 20 items divided into 8 domains that measure: dressing and grooming, 
arising, eating, walking, hygiene, reach, grip, and common daily activities. Subjects are required 
to indicate the degree of difficulty they have experienced in each domain in the past week on a 
4-point scale that ranges from 0 (without difficulty) to 3 (unable to do). Any individual score of 
less than 2 is adjusted to 2 if the activity requires assistance from another individual or the use of 
an assistive device. The highest score in each category is then summed (0 to 24) and divided by 
the number of categories scored to give a score that ranges from 0 to 3.  
9.7 
High sensitivity C-reactive protein levels (hs-CRP) 
High sensitivity CRP levels will be analyzed by the central laboratory according to Table 5-1. 
After Baseline, the hs-CRP data will not be sent to the Investigator in order to protect the blinded 
nature of the treatment assignments and response. 
9.8 
Evaluation of psoriasis 
9.8.1 
Body surface area-psoriasis (BSA-PSO) 
In the BSA-PSO assessment, the subject’s hand (including the palm, fingers, and thumb) is used 
as the reference point for measuring how much of their skin is affected by PSO, representing 
roughly 1% of the body’s surface.  
The BSA palm method will be used for the evaluation of BSA affected by PSO as follows: 
• Head and neck=10% (10 palms) 
• Upper extremities=20% (20 palms) 
• Trunk=30% (30 palms) 
• Lower extremities=40% (40 palms)  
• Total BSA=100% 
9.8.2 
Psoriasis Area and Severity Index (PASI) 
The PASI will be assessed in all subjects with Baseline/Day 1 BSA affected by PSO ≥3% 
determined by the method described in Section 9.8.1 (ie, the BSA palm method).  
The PASI is the most commonly used and validated assessment for grading the severity of PSO 
in clinical studies (Feldman, 2004). The PASI quantifies the severity and extent of the disease 
and weighs these with the percentage of BSA involvement.  
The percent area of involvement (BSA%) is estimated across 4 body areas (head, upper limbs, 
trunk, and lower limbs) and then transferred into a grade (Table 9-2).  
The Investigator assesses the average redness, thickness, and scaliness of lesions in each body 
area (each on a 5-point scale); 0=none, 1=slight, 2=moderate, 3=marked, and 4=very marked.  
The PASI score ranges from 0 to 72 with a higher score indicating increased disease severity. 

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Table 9-2: 
Body areas for calculation of percent BSA for PASI 
Body area 
Details of area 
BSA 
Degree of 
involvement of 
body area a 
Head 
Face, back of head 
10% 
0 to 6 
Upper limbs  
Left, right, upper lower, flexor 
surface, extensor surface 
20% 
0 to 6 
Trunk 
Front, back, groin 
30% 
0 to 6 
Lower limbs  
Left, right, upper lower, flexor 
surface, extensor surface, including 
buttocks 
40% 
0 to 6 
Total 
 
100% 
 
BSA=body surface area; PASI=Psoriasis Area and Severity Index 
 a Where 0=none; 1=1% to <10% affected, 2=10% to <30% affected, 3=30% to <50% affected, 4=50% to <70% 
affected, 5=70% to <90% affected, 6=90% to 100% affected 
The PASI75, PASI90, and PASI100 responses are based on at least 75%, 90%, and 100% 
improvement in the PASI score. The PASI will be assessed at Screening and at Baseline/Day 1. 
Thereafter, the PASI will be assessed for the purposes of determining response only in subjects 
with PSO involving at ≥3% of BSA at Baseline/Day 1. 
9.8.3 
Investigator’s Global Assessment (IGA) 
A static IGA for PSO will be used to assess disease severity in all subjects during the study. The 
IGA will completed at the visits specified in Table 5-1.  
The Investigator will assess the overall severity of PSO using the following 5-point scale 
presented in Table 9-3. 
Table 9-3: 
Five-point IGA 
Score 
Short Descriptor 
Detailed Descriptor 
0 
Clear 
No signs of PSO; post-inflammatory hyperpigmentation may 
be present  
1 
Almost Clear 
No thickening; normal to pink coloration; no to minimal focal 
scaling 
2 
Mild 
Just detectable to mild thickening; pink to light red coloration; 
predominantly fine scaling 
3 
Moderate 
Clearly distinguishable to moderate thickening; dull to bright 
red, moderate scaling  
4 
Severe 
Severe thickening with hard edges; bright to deep dark red 
coloration severe/coarse scaling covering almost all or all 
lesions 
IGA=Investigator’s Global Assessment; PSO=psoriasis 
 

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The IGA response is defined as a clear [0] or almost clear [1] assessment with at least a 
2-category improvement from Baseline, meaning that this parameter will be evaluable only for 
subjects with psoriatic skin lesions (IGA score ≥2) at Baseline.    
In this study, only subjects with BSA ≥ 3% at Baseline will have IGA assessed at post-Baseline 
Visits. 
9.8.4 
Modified Nail Psoriasis Severity Index (mNAPSI) 
Subjects with psoriatic nail disease will have a target nail selected at the Baseline Visit for 
evaluation using the mNAPSI. The nail selected should be the most affected nail observed at 
Baseline and should be the only one assessed throughout the study. The target nail will be scored 
(0 to 3) for onycholysis/oil drop dyschromia, nail plate crumbling, and pitting and will be scored 
(0 for “no” or 1 for “yes”) for leukonychia, nail bed hyperkeratosis, splinter hemorrhages, and 
red spots in the lunula. 
9.9 
Minimal Disease Activity (MDA) and Very Low Disease Activity 
(VLDA) 
Minimal Disease Activity and VLDA are states of disease activity deemed useful targets of 
treatment by both the subject and physician, given current treatment possibilities and limitations. 
Criteria covering all domains of the disease have been developed to determine whether or not a 
subject has reached MDA or VLDA based on key outcome measures in PsA (Mease, 2011; 
Coates et al, 2010).  
A subject is considered as having MDA if 5 or more of the following 7 criteria are fulfilled: 
• Tender joint count ≤1 
• Swollen joint count ≤1 
• PASI ≤1 or BSA ≤3 
• Patients’ pain VAS ≤15 
• PGA-PsA VAS ≤20 
• HAQ-DI ≤0.5 
• Tender enthesial points ≤1 
A subject is considered as having VLDA if all 7 of the above criteria are fulfilled. 
9.10 
Disease Activity Index for Psoriatic Arthritis (DAPSA) 
Disease Activity Index for Psoriatic Arthritis (DAPSA) is a composite score of patient global and 
pain VAS, TJC/SJC, and hs-CRP that incorporates a pattern of peripheral arthritis that often is 
encountered in PsA, and is calculated as follows: 
DAPSA=SJC (range 0-66) + TJC (range 0-68) + PGA-Arthritis (VAS range 0-10cm; 0=best, 
10=worst) + PtAAP (VAS range 0-10cm) + hs-CRP. 

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9.11 
Van der Heijde modified Total Sharp Score (vdHmTSS) 
The degree of joint damage is to be assessed using the vdHmTSS as used in the evaluation of 
PsA (Van der Heijde et al, 2005). This methodology quantifies the extent of bone erosions and 
joint space narrowing for 64 and 52 joints, respectively, with higher scores representing greater 
damage. 
Radiographs of the hands and feet are to be taken using standardized imaging methodology, 
which is defined in the Hand and Foot Radiography Manual that will be provided as part of the 
Study Manual. 
All enrolled subjects are required to have radiographs taken of both hands and both feet (a single 
posteroanterior view of each hand and a single dorsoplantar of each foot). Radiographs are to be 
read centrally and independently by 2 experienced readers. Readers will be blind to treatment 
assignment and time course of the films.  
9.12 
Disease Activity Score-28 based on C-reactive protein 
(DAS28[CRP]) 
The components for DAS28(CRP) include the TJC and SJC based on 28 joints (Section 9.1.2), 
hs-CRP (Section 9.7) and the PGA-Arthritis (Section 9.5). The DAS28(CRP) is calculated as 
follows: 
𝐷𝐴𝑆28(𝐶𝑅𝑃) = 0.56  √𝑇𝐽𝐶+ 0.28  √𝑆𝐽𝐶+ 0.014   𝑃𝐺𝐴−𝐴𝑟𝑡ℎ𝑟𝑖𝑡𝑖𝑠+ 0.36  𝑙𝑛(𝐶𝑅𝑃+ 1) + 0.96 
 
9.13 
Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 
The BASDAI is the most common instrument used to measure the disease activity of ankylosing 
spondylitis from the subject’s perspective (Garrett et al, 1994) and is considered useful for 
evaluating axial involvement in subjects with PsA (Fernandez-Sueiro et al, 2009). The BASDAI 
is a validated self-reported instrument which consists of six 10-unit horizontal numeric rating 
scales 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.  
The BASDAI is calculated as follows:  
𝐵𝐴𝑆𝐷𝐴𝐼=
Q1 + Q2 + Q3 + Q4 + (𝑄5 + 𝑄6
2
)
5
 
 
9.14 
Leeds Enthesitis Index (LEI) 
Enthesitis, the inflammation at the bone insertion of tendon, ligament, or joint capsule, is 
common in PsA. The LEI is a new enthesitis index designed for use in PsA (Healy and Helliwell, 
2007) adopted for use in randomized controlled studies involving subjects with PsA. Enthesitis 
will be assessed by palpation on the lateral epicondyles of the humerus (elbows), medial femoral 
epicondyles (knees), and Achilles tendons (heels) bilaterally and scored as 0=no pain and 
1=painful. 

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9.15 
Spondyloarthritis Research Consortium of Canada (SPARCC) 
The SPARCC is an index that measures the severity of enthesitis through the assessment of 
16 sites (the greater trochanter (right/left [R/L]), quadriceps tendon insertion into the patella 
(R/L), patellar ligament insertion into the patella and tibial tuberosity (R/L), Achilles tendon 
insertion (R/L), plantar fascia insertion (R/L), medial and lateral epicondyles (R/L) and the 
supraspinatus insertion [R/L]) (Maksymowych et al, 2009). Tenderness on examination is 
recorded as either present (1) or absent (0) for each of the 16 sites, for an overall score range of 
0 to 16. 
9.16 
Leeds Dactylitis Index (LDI) 
Dactylitis, the swelling of an entire digit related to articular and periarticular inflammation is a 
characteristic of inflammatory spondyloarthropathies, including PsA. Presence of dactylitis will 
be assessed using the LDI basic. It measures the ratio of the circumference of the affected digit to 
the circumference of the digit on the contralateral hand or foot (millimeters): a minimum 
difference of 10% is used to define a dactylitic digit (Healy and Helliwell, 2007; 
Helliwell et al, 2005). If the contralateral digit is also dactylitic, a table of normative values 
based on population averages is used to provide the comparison. The ratio is then multiplied by 
the tenderness score, using a simple grading system (0=absent, 1=present). The results from each 
digit with dactylitis are then summed to produce a final score. The digits involved and the 
matching contralateral digit will also be recorded at the same visits. 
9.17 
Psoriatic Arthritis Quality of Life (PsAQoL) 
The use of the PsAQoL is recommended by the health regulatory authorities as 1 of the 
disease-specific HRQoL measures in PsA (CHMP/EWP/438/04). The PsAQoL comprises 
20 items so that the score ranges from 0 to 20 with higher scores indicating worse HRQoL. 
9.18 
Psoriatic Arthritis Impact of Disease-12 (PsAID-12) 
The PsAID-12 is a patient-reported outcome measure for assessing the impact of PsA in 
12 physical and psychological domains, including pain, fatigue, skin problems, work and/or 
leisure activities, functional capacity, discomfort, sleep disturbance, coping, 
anxiety/fear/uncertainty, embarrassment and/or shame, social participation, and depression. Each 
domain is assessed with a single question using a 0 to 10 numerical rating scale. Each domain 
score is multiplied by a weighting factor and the results are then summed to provide the total 
score. The total score ranges from 0 to 10, with higher scores indicating a worse status. The 
PsAID-12 demonstrated satisfactory psychometric properties in an international validation study; 
however, further validation is needed (Gossec et al, 2014). A score below 4 out of 10 is 
considered a patient-acceptable status. A change of 3 or more points is considered relevant 
absolute change.  
9.19 
Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue 
subscale 
The FACIT-Fatigue 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 

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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 has been validated in patients with PsA. The minimum clinically 
important difference for FACIT-Fatigue subscale in patients with PsA was determined to be a 4-
point change (Cella et al, 2019). 
9.20 
Short-Form 36-item Health Survey (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), and 1 item 
 
. The concepts 
represented by these domains contribute to physical, mental, and social aspects of HRQoL. 
In addition to domain scores, the PCS and MCS scores are calculated from the 8 domains 
(excluding the Health Transition item). Component scores reflect the impact of each domain on 
physical and mental health status. The norm-based T-scores for the 2 SF-36 component summary 
(PCS and MCS) and the 8 domains 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.  
9.21 
Euro Quality of life 5-Dimensions-3 Level (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 
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). 
9.22 
Work Productivity and Activity Impairment Questionnaire–
Specific Health Problem (WPAI-SHP) 
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 (Reilly et al, 1993).  
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. 
9.23 
Psoriatic Arthritis Response Criteria (PsARC) 
The PsARC is based on the TJC (68 joints) and SJC (66 joints), the PGA-PsA and PhGA-PsA 
VAS.  

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The PsARC response is defined as improvement from Baseline in at least 2 of the 4 measures 
(TJC, SJC, PGA-PsA, PhGA-PsA) 1 of which must be TJC or SJC and no worsening from 
Baseline in any of the 4 measures. Improvement for TJC and SJC is defined as a reduction of 
≥30% and worsening is defined as an increase of ≥30%. Improvement of PGA-PsA and 
PhGA-PsA is defined as a reduction of the 100-point VAS of ≥20 points and worsening is 
defined as an increase of the 100-point VAS of ≥20. 
9.24 
Psoriatic Arthritis Disease Activity Score (PASDAS) 
The PASDAS (Coates et al, 2014) is a composite score that includes patient and physician global 
scores of skin and joint disease, SJC, TJC, LEI, tender dactylitis count, the physical component 
of the SF-36 Health Survey, and level of CRP. It was developed by the Group for Research and 
Assessment of Psoriasis and Psoriatic Arthritis and the European League Against Rheumatism. 
PASDAS is calculated using the following equation: 
PASDAS = (((0.18 × √Physician global VAS) + (0.159 × √Patient global VAS) − 
(0.253 × √SF36 − PCS) + (0.101 × LN (SJC + 1)) + (0.048 × LN (TJC + 1)) + (0.23 × 
LN (LEI + 1)) + (0.377 LN (tender Dactylitis count + 1)) + (0.102 × LN (CRPmg/dL 
+ 1)) +2)*1.5. 
Note: LN=natural logarithm 
The following categories are used to define the level of disease activity (Coates et al, 2018): 
• Remission: PASDAS ≤1.9 
• Low disease activity: PASDAS 1.9 to <3.2 
• Moderate disease activity: PASDAS 3.2 to <5.4 
• High disease activity: PASDAS ≥5.4 
10 
ASSESSMENT OF PHARMACOKINETIC AND 
PHARMACOGENOMIC VARIABLES 
10.1 
Pharmacokinetic variable 
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 5-1. 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. 
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. 

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These analyses will enable evaluation of biomarkers relative to disease biology and progression, 
drug treatment, 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, and metabolomics 
analysis and for candidate exploratory biomarker analyses. Candidate exploratory biomarker 
evaluations may include, but are not limited to, IL 17A/IL-17F pathway signaling and PsA 
biology (eg, IL-17A, IL-17F, IL-23, IL-6, tumor necrosis factor, dendritic cell-specific 
transmembrane protein, and circulating osteoclast precursors). 
Collection of these samples will occur at the time points specified in the schedule of study 
assessments (Table 5-1). 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. 
Detailed information on the collection, storage, preparation, and shipping of samples for 
potential RNA, proteins, lipids, and metabolites analysis will be presented in a Laboratory 
Manual. 
The nature and format of these tentative analyses will be determined at a later date. 
Results for the exploratory parameters obtained from potential RNA, lipids, proteins and 
metabolites analysis will be described in a separate 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 5-1. 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. 
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. 

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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 Informed Consent form), 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.) 
• 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 

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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.) 
Note: Confirmed active TB is an SAE and must be captured on an SAE Report Form and 
provided to the Sponsor in accordance with SAE reporting requirements. 
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. Note that 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. 
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 SAEs for the population of subjects with PsA 
MedDRA system organ class 
MedDRA preferred terms 
Eye disorders 
Uveitis 
Cardiac disorders 
Myocardial infarction 
Atrial fibrillation 
Gastrointestinal disorders 
Crohn's disease 
Hepatobiliary disorders 
Non-alcoholic steatohepatitis 
Metabolism and Nutrition disorders 
Metabolic syndrome 
Diabetes mellitus 
Musculoskeletal and connective tissue disorders 
Psoriatic arthropathy 
Neoplasms benign, malignant and unspecified 
(including cysts and polyps) 
Basal cell carcinoma 
Squamous cell carcinoma 
Nervous system disorders 
Embolic Stroke 
Ischaemic Stroke 
Psychiatric disorders 
Anxiety 
Depression 
Skin and subcutaneous tissue disorders 
Psoriasis 
MedDRA=Medical Dictionary for Regulatory Activities; PsA=psoriatic arthritis; 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 is any AE that a regulatory authority has mandated 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 AE of special interest (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. 
12.1.1.4 
Other safety topics of interest 
Prespecified 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 

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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 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 and the corresponding medical terminology should be clarified in the 
source documentation. 
When recording the intensity of an AE in the CRF (ie, mild, moderate, or severe), the 
Investigator should use the following criteria: 
• Mild: the subject is aware of the sign or symptom (syndrome), but it does not interfere with 
his/her usual activities and/or is of no clinical consequence 
• Moderate: the AE interferes with the usual activities of the subject or it is of some clinical 
consequence 
• Severe: the subject is unable to work normally or to carry out his/her usual activities, or the 
AE is of definite clinical consequence 
Details for completion of the AE 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 

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information (fax/email) for SAE reporting listed in the Serious Adverse Event Reporting section 
at the front of the protocol. 
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 as assessment of 
expectedness of the reported SAE. The assessment of expectedness of the SAE is based on the 
IB. 
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; AESMs, further details regarding 
follow-up of PDILI events is provided in Section 12.2.1.4. 
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. 

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12.1.4 
Pregnancy 
If the 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 PS. 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. 
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 provided to the Investigator. The progression of 
the pregnancy and the eventual birth (if applicable) must be followed up using the eCRF in 
which the Investigator must 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 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 woman, or 
when 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. 

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12.1.5 
Suspected transmission of an infectious agent via a medicinal 
product 
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. 
12.1.6 
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). 
12.1.7 
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 the safety data from this study and advise UCB. The DMC membership includes 
clinicians knowledgeable about the disease or the treatment. All members have experience and 
expertise in clinical studies. Board members may not participate in the study as principal or 
co-Investigators, or as study subject care physicians. The duration of membership for the DMC 
will be inclusive of planned analyses for PA0010. The DMC may also be asked to provide a 
review of final study results, as deemed appropriate. The DMC procedures will ensure that data 
remain blind to the study team and Investigators at all times throughout the conduct of the study. 
The detailed role, scope, responsibilities, and complete procedures, as well as the identity of the 
DMC members, will be described in a separate charter document. A Cardiovascular Adjudication 
Committee and a Neuropsychiatric Adjudication Committee will be in place for this study. 
Specific procedures will be outlined in the charters, which will be developed by the committee 
members. 
12.2 
Laboratory measurements 
Clinical laboratory assessments consist of serum biochemistry, hematology, urinalysis, and 
pregnancy tests (serum or urine) (Table 5-1). A centralized laboratory will be used to supply all 
laboratory test supplies and analyze all blood and urine samples for hematology and 
biochemistry. Any unscheduled laboratory testing should also be collected using the central 

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laboratory (with the exception of urgent safety laboratory measurements which should be 
performed locally and centrally simultaneously). Testing to rule out hepatitis B, hepatitis C, and 
HIV will be performed at Screening. Rheumatoid factor and anti-CCP testing will also be 
performed at Screening. Testing of HLA-B27 will be performed at Baseline. 
Specific details regarding the handling and processing of serum biochemistry, hematology and 
urinalysis samples are provided in the study laboratory manuals. 
Laboratory parameters to be measured are presented in Table 12-2. 
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 testing b 
MCH 
Creatinine 
Urine drug screenc 
MCHC 
hs-CRP 
 
MCV 
AST 
 
Platelet count 
ALT 
 
RBC count 
GGT 
 
WBC count 
ALP 
 
 
Total bilirubin 
 
 
Triglyceridesa 
 
 
Cholesterola 
 
 
HDL cholesterola 
 
 
LDL cholesterola 
 
 
LDH 
 
 
Serum pregnancy testingb 
 

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Table 12-2: Laboratory measurements 
 
Hematology 
Biochemistry 
Urinalysis  
ALP=alkaline phosphatase; ALT=alanine aminotransferase; AST=aspartate aminotransferase; BUN=blood 
urea nitrogen; ET=early termination; GGT=gamma-glutamyltransferase; HDL=high density lipoprotein; 
hs-CRP=high sensitivity C-reactive protein; IMP=investigational medicinal product; IMS=International 
Menopause Society; LDH=lactate dehydrogenase; LDL=low density lipoprotein; 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 Biochemistry will include triglycerides, cholesterol, HDL cholesterol, and LDL cholesterol at Baseline, 
Weeks 12 and 24, and at the ET Visit. 
b Pregnancy testing will consist of serum testing at the Screening Visit for all women of childbearing potential. 
The pregnancy test will be urine at all other visits.  
c Urine drug screen will be performed at Screening Visit. 
 
12.2.1 
Evaluation of potential drug-induced liver injury 
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 AEs 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 12.2.1.1). 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 12.2.1.4).  
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 

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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 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 12.2.1.2.1 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 of 
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. 
Immediate IMP 
discontinuation.d 
 
 
 
Essential: Must have 
repeat liver 
chemistry values 
and additional 
testing completed 
ASAP (see 
Section 12.2.1.3); 
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 of 
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 12.2.1.2). 
 
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 12.2.1.3). 
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. 

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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 of 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
• 
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 
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 12.2.1.1. 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 12.2.1.2.1.  
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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12.2.1.1 
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 12.2.1.3) and SAE report (if applicable). 
12.2.1.2 
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 and permanent 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. 
12.2.1.2.1 
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 12.2.1.3 and 
Section 12.2.1.4 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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12.2.1.3 
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 
Toxicology screen a 
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 test 
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 For detecting substances (ie, amphetamines, benzodiazepines, opioids, marijuana, cocaine, phencyclidine, and 
tricyclic antidepressants), additional tests may be performed based on the Investigator’s medical judgment and 
subject’s 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). 

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Additional information to be collected is presented in Table 12-5.  
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 
12.2.1.4 
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. 
12.3 
Other safety measurements 
12.3.1 
Vital signs 
The Investigator or designee should measure all vital signs (BP, temperature [oral, axillary, or 
otic], and pulse rate) after the subject has been sitting for at least 5 minutes, and the subject 
should remain seated during the measurements. At Baseline and at Week 16, vital signs will be 
measured prior to IMP administration and then at approximately 30 minutes and 1 hour after 
dosing. At all other visits, vital signs will be measured only once prior to dosing. 

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12.3.2 
Body weight and height 
The Investigator or designee will measure the height of the subject with shoes removed in meters 
and the weight of the subject in kilograms. The same scale should be utilized throughout the 
study where possible. 
12.3.3 
Physical examination 
The physical examination should be conducted by the Investigator or designee at the time points 
listed in Table 5-1 and will include general appearance; ear, nose, and throat; eyes, hair, and 
skin; respiratory; cardiovascular; gastrointestinal; 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. 
12.3.4 
12-lead electrocardiogram 
The Investigator or designee will perform the ECGs which will be read centrally. Full details of 
ECG recording will be provided in the ECG Manual. 
12.3.5 
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 study assessments (Table 5-1) through physical examination for signs and symptoms of TB, 
chest x-ray (Section 12.3.5.2), laboratory testing (Section 12.3.5.1), and subject questionnaire 
(Section 12.3.5.3). 
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 LTBI 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 (Center for Disease Control 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 presented in 
Figure 12-1. A schematic diagram of TB test results during the study is presented in Figure 12‒2. 

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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 full treatment course of prophylaxis for 
LTBI are allowed. Prophylaxis should be in accordance with WHO/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; LTBI=latent tuberculosis infection; 
TB=tuberculosis 
a IGRA retest must be done ASAP and prior to the next 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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12.3.5.1 
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 5-1 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. The retest during Screening must be done 
during the protocol-defined Screening window. 
12.3.5.2 
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. 
12.3.5.3 
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 5-1. The 
questionnaire will assist with the identification of subjects who may require therapy for TB. A 
subject who answers “Yes” to the question 
 
 at 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 #10 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.  
12.3.5.4 
Tuberculosis management 
LTB infection and active TB identified during study 
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 

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indicates that TB infection or exposure may have occurred. Evidence of active TB includes, in 
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. 
12.3.6 
Pregnancy testing 
Pregnancy testing will consist of serum testing at Screening for all women of childbearing 
potential. The pregnancy test will be urine 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 at the visits specified in Table 5-1. Pregnancy tests should be 
administered to all female subjects of childbearing potential, regardless of their use of birth 
control. 
12.3.7 
Assessment of suicidal ideation and behavior 
Suicidal ideation and behavior will be assessed by trained study personnel using the eC-SSRS. 
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 5-1). 
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. 
12.3.8 
Patient Health Questionnaire-9 (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 

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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 assessed at the visits specified in Table 5-1.  
Refer to Section 6.3 for PHQ-9-related withdrawal criteria. 
13 
STUDY MANAGEMENT AND ADMINISTRATION  
13.1 
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. 
13.2 
Monitoring 
UCB (or designee) will monitor the study to meet the Sponsor’s monitoring 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. 
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 eCRFs and 
corresponding source documents (eg, hospital and laboratory records for each subject). 
Monitoring visits will provide UCB (or designee) with the opportunity to evaluate the progress 
of the study, verify the accuracy and completeness of eCRFs, ensure that all protocol 
requirements, applicable authorities’ regulations, and Investigator’s obligations are being 
fulfilled, and resolve any inconsistencies in the study records. 
13.2.1 
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, 

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pharmacy records, care records, ECG or other printouts, completed scales, or Quality of Life 
questionnaires, for example. Source documents should be kept in a secure, limited access area. 
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, such as Holter monitor records or electroencephalogram records, must 
be saved and stored as instructed by UCB (or designee). 
Electronic Patient-Reported Outcome (ePRO) measures (eg, EQ-5D-3L, FACT-F, HAQ-DI, 
PGA-PsA and, PGA-arthritis) 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). 
13.2.2 
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 13.2.1. 
13.3 
Data handling 
13.3.1 
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 eCRFs and in all required reports. 
Any change or correction to the eCRF should be dated, initialed, and explained (if necessary) 
and should not obscure the original entry.  
Corrections made after the Investigator’s review and signature of the completed eCRF will be 
resigned and dated by the Investigator. 
The Investigator should maintain a list of personnel authorized to enter data into the eCRF. The 
Investigator is responsible for prompt reporting of accurate, complete, and legible data in the 
electronic eCRFs and in all required reports.  
Detailed instructions on the use of the EDC will be provided in the eCRF Completion 
Guidelines. 
Any change or correction to the eCRF after saving must be accompanied by a reason for the 
change. Corrections made after the Investigator’s review and approval (by means of a 
password/electronic signature) will be reapproved by the Investigator. 

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13.3.2 
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. 
13.3.3 
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. 
13.4 
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, 
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. 
13.5 
Archiving and data retention 
The Investigator will maintain adequate records for the study, including eCRFs, 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 

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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. 
13.6 
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). 
13.7 
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. 
14 
STATISTICS 
A description of statistical methods follows and will be described in more detail in the SAP. 
14.1 
Definition of analysis sets 
The following analysis sets were defined: 
• The Enrolled Set (ES) consists of all subjects who have given informed consent. 
• The Randomized Set (RS) consists of all randomized subjects.  
• The Safety Set (SS) consists of all randomized subjects who received at least 1 dose of the 
IMP. 
• The Full Analysis Set (FAS) consists of all randomized subjects who received at least 1 dose 
of IMP and have valid measurement of all the 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 deviations affecting the primary efficacy variable. Important protocol deviations 
will be predefined and subjects with important protocol deviations will be evaluated during 
ongoing data cleaning meetings prior to unblinding of the data. Exclusions from the FAS will 
be considered important protocol deviations that also result in exclusion from the PPS. 

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• The Pharmacokinetic Per-Protocol Set (PK-PPS) consists of all randomized subjects who 
received at least one dose of the IMP and provided at least one quantifiable plasma 
concentration post-dose without important protocol deviations that would affect the 
concentration. Exclusions from the FAS will be considered important protocol deviations that 
also result in exclusion from the PK-PPS. 
• The Radiographic Set will consist of all subjects in the RS who received at least 1 dose of the 
IMP and have a valid radiographic image of the hands and feet at Baseline. 
• The COVID-19-free Set will consist of all subjects in the RS who had no COVID-19 impact 
up to the primary efficacy endpoint. This will be defined as subjects not having a COVID-19 
related important protocol deviation, nor having an impact based on the COVID-19 eCRF 
nor having an AE related to COVID-19 nor discontinuing due to COVID-19 up to the time of 
the primary endpoint. 
14.2 
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. 
14.3 
Planned efficacy analyses 
14.3.1 
Analysis of the primary and secondary efficacy variables 
A fixed sequence testing procedure will be applied for 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 each test, on each binary efficacy endpoint, the null hypothesis is that the conditional odds 
ratio is equal to one.   
H0: ORT1T2 = 1 
The alternative hypothesis is that the conditional odds ratio is not equal to one. 
HA: ORT1T2 ≠ 1 
For each test on each continuous efficacy endpoint, 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 
For the primary and secondary variables, the primary comparison is the bimekizumab 160mg sc 
Q4W vs placebo. Point estimates and 95% confidence intervals (CI) will be calculated.   
No formal statistical comparisons will be made with the adalimumab 40mg sc Q2W treatment 
group. 

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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 and testing will continue. The testing will be stopped if 
a hypothesis cannot be rejected at α=0.05 (2-sided). 
The fixed sequence testing procedure of primary and secondary efficacy endpoints is shown in 
Figure 14-1. 
Figure 14-1: Sequential testing procedure of primary/secondary efficacy 
endpoints (fixed sequence testing procedure)  
 
ACR=American College of Rheumatology; BKZ=bimekizumab; CfB=change from Baseline; H=hypothesis; 
HAQ-DI=Health Assessment Questionnaire—Disability Index; hs-CRP=high sensitivity C-reactive protein; 
MDA=Minimal Disease Activity; PASI=Psoriasis Area and Severity Index; PCS=Physical Component Summary; 
Q4W=every 4 weeks; SF-36=Short-Form 36-item Health Survey; vdHmTSS=Van der Heijde modified Total 
Sharp Score; W=Week 
* It is planned to enroll a minimum of 45% of subjects who are positive for elevated hs-CRP (hs-CRP ≥6mg/L) 
and/or who have at least 1 bone erosion at Screening. 
** Based on the overall population 
14.3.1.1 
Analysis of the primary efficacy variable 
The primary efficacy variable will be analyzed for all subjects in the RS. 

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The primary endpoint is the ACR50 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 in ACR50 response and not discontinuing treatment 
early. This composite estimand is similar to nonresponder imputation (NRI). 
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 = ACR50 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 ACR50 at Week 16 and not discontinuing study 
treatment through Week 16.  
4. Population-level summary measure = Conditional odds ratio comparing bimekizumab to 
placebo. 
As the ACR response is based on 7 different component scores, it is necessary to consider 
various data scenarios that could impact the calculation of response. The rules described here are 
applicable in the context of the calculation of ACR response and may differ from the rules 
applied for calculating and summarizing the components individually (some values may need to 
be imputed for component analysis but are not required here to evaluate ACR response).  
The following rules will be applied prior to invoking any imputation analysis at the variable 
level: 
• If a subject has a component value that is equal to 0 at Baseline and the post-Baseline 
value is greater than or equal to 0, then the percent improvement for that component will 
be treated as 0 for purposes of ACR response calculations. 
• If a subject has component values that are missing at Baseline, then the percent 
improvement for that component will be treated as missing for purposes of ACR response 
calculations. 
Observed data will be used to calculate ACR response where possible. In case of partial missing 
data where an observed response may be calculated, imputed data will not change the result. 
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. 
The statistical hypothesis for the ACR50 response at Week 16 is that the conditional odds ratio 
for ACR50 response in the bimekizumab treatment compared with placebo treatment is equal 
to 1.  
A logistic regression model will be used to assess the treatment effect on ACR50 response at 
Week 16. The model will include a fixed effect for treatment. The suitability of including the 
randomization stratification variables, region and bone erosion at Baseline will be assessed and 
will be added to the model if appropriate. Comparisons will be made using the 2-sided Wald test 
at a significance level of α=0.05 (ie, H1 in Figure 14-1). The odds ratio versus placebo, p-value, 
and the 95% CI will be calculated. 

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Any use of prohibited or rescue medications through Week 16 would constitute an important 
protocol deviation which would be accounted for when the sensitivity analysis based on the PPS 
is performed (see Section 14.3.1.1.1). 
14.3.1.1.1 
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 primary comparison will also be repeated for all individual components of the ACR50 
response to explore the effect of the signs and symptoms of the individual components on the 
composite endpoint. Since all ACR components are continuous variables (eg, change from 
Baseline in TJC), an analysis of covariance (ANCOVA) with treatment, region, and bone 
erosion at Baseline as fixed effects and the Baseline value as a covariate will be used for the 
analysis. Note as outlined above, some additional values may need to be imputed for 
component analysis which are not required to evaluate the overall ACR response. 
4. The analysis will be repeated using a modified composite estimand where intercurrent events 
are defined only as discontinuation due to AE or lack of efficacy. 
5. The analysis will be repeated using a treatment policy approach. 
6. The analysis will be repeated using observed cases only. 
7. The analysis will be repeated using the COVID-19-free Set. 
Additional sensitivity and supportive analyses to evaluate varying assumptions related to the 
handling of missing data will also be performed and are described in Section 14.7. 
14.3.1.2 
Analysis of the secondary efficacy variables 
The secondary efficacy variables will be analyzed for all subjects in the RS.  
All binary variables that are part of the testing hierarchy are given below: 
• PASI90 responders at Week 16 will be analyzed to evaluate the composite estimand. The 
composite estimand combines the clinically meaningful improvement from Baseline in 
PASI90 response and not discontinuing treatment early. 
• The proportion of subjects achieving MDA status at Week 16 will be analyzed to evaluate 
the composite estimand. The composite estimand combines (1) achieving the MDA status 
with (2) not discontinuing treatment early. 
• The proportion of subjects with enthesitis at Baseline achieving enthesitis-free status at 
Week 16 will be analyzed to evaluate the composite estimand. The composite estimand 
combines (1) achieving the enthesitis-free status with (2) not discontinuing treatment early. 
For this analysis, the PA0010 and PA0011 data will be pooled. 

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• The proportion of subjects with dactylitis at Baseline achieving dactylitis-free status at 
Week 16 will be analyzed to evaluate the composite estimand. The composite estimand 
combines (1) achieving the dactylitis-free status with (2) not discontinuing treatment early. 
For this analysis, the PA0010 and PA0011 data will be pooled. 
The statistical hypothesis for the binary variables at Week 16 is that the conditional odds ratio for 
binary variables in the bimekizumab treatment compared with placebo treatment groups is equal 
to 1. 
The binary variables will be analyzed using the same analysis methods and estimand approach as 
used for the primary variable (Section 14.3.1.1). 
If appropriate ie, where the outcome variable (eg, PASI90 response) is an assessment of 
skin/dermatological manifestations of PsA the fitted model will exclude the fixed term bone 
erosion at Baseline. 
All continuous variables that are part of the testing hierarchy are given below: 
• Change from Baseline in HAQ-DI at Week 16 
• Change from Baseline in the SF-36 PCS score at Week 16  
• Change from Baseline in vdHmTSS at Week 16  
Continuous variables will be analyzed to evaluate the hypothetical estimand as defined below: 
1. Population = Subjects enrolled according to the protocol-specified inclusion/exclusion 
criteria and randomized to IMP. 
2. Subject level outcome = variable as stated in Section 4.2.1  
3. 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. 
4. Population-level summary measure = the difference in the adjusted means between 
bimekizumab 160mg Q4W and placebo. 
Any missing data at Week 16 that are not preceded by an intercurrent event (ie, discontinuation 
of study medication) will also be imputed based on a predefined 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 MCMC method, followed by monotone regression for monotone 
missing data.  
In the case of vdHmTSS missing data, as vdHmTSS is only collected at Baseline prior to 
Week 16; missing data at Week 16 will be imputed using monotone regression. 
The statistical model for continuous endpoints for the comparison of bimekizumab and placebo 
will be an ANCOVA model with treatment, bone erosion, and region as fixed effects and the 

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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 as well as 
multiple imputation using the modified composite estimand for binary variables. 
Variables that are included in the hierarchy will additionally be rerun  using the COVID-19-free 
Set. 
14.3.2 
Analysis of the other efficacy variables 
All other efficacy variables will be analyzed for all subjects in 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 enrolled according to the protocol-specified inclusion/exclusion 
criteria and randomized to IMP. 
2. Subject-level outcome = The given variable and time point being summarized (eg, ACR50 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 is not preceded by an intercurrent event as described above will be 
imputed based on 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 enrolled according to the protocol-specified inclusion/exclusion 
criteria and randomized to IMP. 
2. Subject-level outcome = The given variable and time point being summarized (eg, change 
from Baseline in HAQ-DI 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 

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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. 
Other binary and continuous efficacy variables will also be summarized based on observed case 
data (ie, subjects with missing data or who have prematurely discontinued study treatment are 
treated as missing). Further, binary outcomes will be summarized using the modified composite 
estimand. 
Time to ACR20/50/70 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 
treatment discontinuation. Subjects in the placebo group who are rerandomized at Week 16 
without achieving response will be censored at the date of the Week 16 Visit. The median time to 
response, including the 2-sided 95% CI, will be calculated for each treatment. Between group 
differences will be analyzed with a log-rank statistic. 
The time to ACR20/50/70 endpoints with 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. 
The time to ACR20/50/70 endpoints will also be analyzed using observed case (OC) data. 
14.3.3 
Subgroup analyses 
Subgroup analyses will be performed on the ACR50 response and the PASI90 response at 
Week 16. The following variables for subgroup analyses will be defined:   
• Age (<45 years of age, ≥45 years of age) 
• Gender (male, female) 
• Disease duration (<1 year, ≥1 year) 
• Region (eg, Asia, Eastern Europe, North America, Western Europe) 
• Race  
• Weight at Baseline (≤100kg, >100kg) 
• Bone erosion (≥1) at Baseline (Yes, No) 
• hs-CRP at Baseline (<6mg/L, ≥6mg/L) 
• Bone erosion (≥1) and/or hs-CRP ≥6mg/L at Baseline (Yes, No) 
• Prior cDMARDs (0, 1, ≥2) 
• Concomitantly receiving cDMARDs versus no concomitant cDMARDs 
• Concomitantly receiving MTX versus no concomitant MTX 
• PSO affected BSA at Baseline (<3%, ≥3% to 10%, >10%) 
• BASDAI at Baseline (≤4, >4) 

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• Anti-bimekizumab antibody status (positive, negative) 
• HLA-B27 (positive, negative) 
14.4 
Planned safety analyses 
14.4.1 
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, TEAEs of special monitoring and deaths will be also be tabulated and 
listed. TEAEs adjusted for exposure will also be presented. 
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 value (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. 
14.5 
Other planned analyses 
14.5.1 
Pharmacokinetics analyses 
Pharmacokinetic variables will be analyzed for all subjects in the PK-PPS.  
Bimekizumab plasma concentrations will be summarized for each treatment at each scheduled 
visit. 
The relationship between bimekizumab plasma concentrations and efficacy response (for 
example ACR20/50/70) and/or safety endpoints may be explored via a graphical and/or a model 
based (PK-PD) approach. The data may also be combined with that from other bimekizumab 
trials. The details of such analysis will be described separately in a data analysis plan, and the 
analysis itself will be reported separately from the CSR.  
14.5.2 
Immunological analyses 
Anti-bimekizumab antibodies will be assessed using a tiered approach: screening, confirmatory, 
and titer assays will be used. Anti-bimekizumab antibodies (including positivity) will be 
summarized by treatment at each scheduled visit at which samples are collected.  
14.6 
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 

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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. 
14.7 
Handling of dropouts or missing data 
The primary method for assessing the efficacy variables will be the composite estimand 
approach to handling missing data that is similar to NRI. 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 multiple imputation procedures planned for efficacy 
analyses are based on an assumption of data missing at random (MAR).  
Missing data will be evaluated as sensitivity analyses using different missing data mechanisms. 
The following sensitivity analyses for the primary efficacy variable will be conducted: 
1. Multiple imputation as described above will be performed using the modified composite 
estimand. The definition of an intercurrent event is changed from all treatment 
discontinuation, to discontinuation of treatment due to AE or lack of efficacy.  
2. A tipping point analysis will be performed to evaluate missingness assumptions. The tipping 
point analysis 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 
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 SAP.  
3. The treatment policy strategy for addressing intercurrent events will be considered. This will 
be based on an analysis in which all available data at Week 16 regardless of the occurrence 
of intercurrent events will be considered. 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 and were no longer on the randomized study treatment when the assessment was 
performed at 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 

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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 sensitivity 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. The same 
procedure described as in the main efficacy analysis will be used. 
Additional details on these sensitivity analyses will be provided in the SAP. 
14.8 
Planned interim analyses and data monitoring 
14.8.1 
Interim analyses 
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.  
The purpose of the Week 24 interim analysis is to perform a comprehensive evaluation of all 
available double-blind data for the 3 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 assigned 
bimekizumab dosing regimen until the final analysis is completed. 
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 
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 blinding plan will be written to evaluate the 
potential bias of the Active Treatment-Blind 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 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 data cuts may be prepared following regulatory requests or for publication purposes. 
14.8.2 
Data monitoring 
A Data Monitoring Committee (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.  

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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 PA0010. 
14.9 
Determination of sample size 
Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio to the following treatment 
groups: bimekizumab 160mg sc Q4W (420 subjects), placebo (280 subjects), 
adalimumab 40mg sc Q2W (140 subjects).  
The primary efficacy analysis is based on the bimekizumab dose versus placebo for 
ACR50 response at Week 16. It is planned that only descriptive summaries will be provided for 
the adalimumab reference arm. No statistical comparisons will be made between adalimumab 
and the other treatment groups.  
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. 
14.9.1 
Power calculation for primary endpoint 
The sample size assumptions for bimekizumab versus placebo are based on the ACR50 response 
data from the Phase 2b bimekizumab study in subjects with moderate to severe PsA (PA0008). 
The median ACR50 responses of the top three dose groups (bimekizumab 160mg, 320mg, and 
320mg [initial dose] plus 160mg) at Week 12 in the TNF-naïve population are conservatively 
assumed for the Week 16 endpoint. The observed median ACR50 response rate of the top three 
bimekizumab doses in the TNF-naïve population in study PA0008 was 43.8%.  
The placebo ACR50 response at Week 16 is based on the TNFα-naïve population in PA0008 
(6.1% at Week 12, n=33); Mease et al, 2015), FUTURE 2 study in the subgroup of TNFα-naïve 
subjects (15.9%, n=63; McInnes et al, 2015), FUTURE 3 study (11.8%, n=93; Nash and Mease, 
2018), and FUTURE 5 study in a mixed TNFα exposure population (8.1% at Week 16, n=332; 
Mease et al, 2018). Therefore, the estimated ACR50 response at Week 16 in the placebo group is 
assumed to be 16%. 
The sample size for showing statistical superiority of bimekizumab vs placebo was calculated 
using a 2-sided 2-sample Chi-square test with continuity correction (Fleiss et al, 1980). 
Assuming 420 subjects in the bimekizumab group and 280 subjects in the placebo group, the test 
for detecting statistical superiority of bimekizumab 160mg Q4W vs placebo based on 
ACR50 response at Week 16 has >99% power to detect a true treatment difference of 27.8% 
(odds ratio 4.09).  
14.9.2 
Power calculations for secondary endpoints 
The assumptions for power calculations of the secondary endpoints included in the hierarchy, 
and for which supporting data exists, are based on the interim results of the Phase 2b 

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bimekizumab study PA0008 and the FUTURE 1, FUTURE 2, FUTURE 5, and SPIRIT P1 
studies. 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). 
For the PASI90 response at Week 16, the bimekizumab 160mg Q4W treatment response at 
Week 12 is 45% (n=20) in the TNFα-naïve population of PA0008 at Week 12 and 46% (n=28) at 
Week 12 in the mixed TNFα exposure population. The placebo PASI90 response at Week 16 is 
based on the subgroup analyses of TNFα therapy-naïve subjects in PA0008 (9.1% at Week 12; 
n=22), FUTURE 2 study (9.7% at Week 24; n=63), and SPIRIT P1 study (1.5% at Week 12; 
n=67). Therefore, a placebo PASI90 response rate of 10% is assumed. With those assumptions, 
the study has >99% power to detect a true treatment difference at an assumed 60% of subjects 
with BSA ≥3% of the planned sample size. 
For change from Baseline in HAQ-DI at Week 16, the between treatment differences of the 
change from Baseline in HAQ-DI of in the mixed TNFα exposure population of the PA0008 at 
Week 12 were used. The bimekizumab 160mg Q4W treatment group mean change from 
Baseline in HAQ-DI at Week 12 of -0.37, SD=0.47 (n=41) versus placebo mean change from 
Baseline in HAQ-DI at Week 12 of -0.13, SD=0.50 (n=42). With those assumptions, the study 
has >99% power to detect a true treatment difference of -0.24 at the planned sample size. 
For change from Baseline in PCS of SF-36 at Week 16, the between treatment differences of the 
change from Baseline in PCS of SF-36 of the TNFα-naïve population of FUTURE 2 study 
(Kavanaugh et al, 2016) at Week 24 were used. The bimekizumab 160mg Q4W treatment group 
assumes the secukinumab 150mg treatment group mean change from Baseline in SF-36 PCS at 
Week 24 of 7.91, SD 7.38 (N=63) versus placebo mean change from Baseline in SF-36 PCS at 
Week 24 of 2.08, SD 9.51 (N=63). With those assumptions, the study has >99% power to detect 
a true treatment difference of 5.83 at the planned sample size. 
For MDA at Week 16, the bimekizumab 160mg Q4W treatment response at Week 12 in PA0008 
is 46.3% (N=41) in the mixed TNFα exposure population of PA0008. In the placebo group, 
14.3% of subjects achieved MDA at Week 12 (n=42). With those assumptions, the study has 
>99% power to detect a true treatment difference of 32% (odds ratio 5.17) at the planned sample 
size. 
For change from Baseline in vdHmTSS at Week 16, the between treatment differences of the 
change from Baseline in vdHmTSS at Week 16 of the SPIRIT P1 study in a TNFα-naive 
population (Mease et al, 2017) were used. The SPIRIT P1 study ixekizumab 80mg sc Q2W 
treatment group least square (LS) mean change from Baseline at Week 16 0.06 and SD 0.720; 
and LS mean change from Baseline 0.36 and SD 0.710 for placebo are assumed. With those 
assumptions, the study has a 95% power to detect a true treatment difference of -0.30, assuming 
45% of subjects with elevated hs-CRP and/or bone erosion, in the planned sample size. 
There is uncertainty in the final percentage of subjects with elevated hs-CRP and/or bone erosion 
at Baseline that will be recruited to the study and the variability in the subgroup. To demonstrate 
the sensitivity of the sample size calculation for this study, Table 14‒1 shows the power function 
for a fixed total sample size of 840 subjects in the RS population for this secondary efficacy 
analysis, varying the percentage of subjects with elevated hs-CRP and/or bone erosion at 

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Baseline and the treatment difference and estimated standard deviation on the change from 
Baseline in vdHmTSS at Week 16. 
Table 14‒1: Treatment effect by elevated hs-CRP and/or bone erosion at 
Baseline for secondary efficacy analyses 
Subjects with elevated hs-CRP and/or 
bone erosion at Baseline 
Treatment difference/standard deviation 
 
Treatment effect = -0.3 
SD=0.72 vs 0.71 
Treatment effect = -0.35 
SD=0.81 vs 0.93 
20% 
67 
62 
25% 
76 
72 
30% 
84 
79 
35% 
89 
85 
40% 
92 
89 
45% 
95 
92 
50% 
96 
95 
hs-CRP=high sensitivity C-reactive protein; SD=standard deviation 
 
For enthesis free-state at Week 16, enthesis resolution data from the FUTURE 5 study at 
Week 16 were used to estimate the bimekizumab 160mg Q4W treatment and placebo groups. In 
FUTURE 5 The treatment effect estimate from the secukinumab 150mg treatment group at 
Week 16 was 55% (n=141) and the placebo group estimate was 36% (n=192). Assuming a BKZ 
response of 55% and a placebo rate of 39% and having 25% of subjects with Baseline enthesis 
the pooled PA0010/PA0011 the studies have a 69% power to detect a true treatment difference 
of 16% (odds ratio 1.91). 
For dactylitis-free state at Week 16, dactylitis resolution data of the FUTURE 5 study (Mease et 
al, 2018) at Week 16 were used to estimate the bimekizumab 160mg Q4W treatment and placebo 
groups. The treatment effect estimate from the secukinumab 150mg treatment group at Week 16 
of 56% (n=103) is assumed versus a placebo group estimate of 32% (n=124). With those 
assumptions and having 11% of subjects with Baseline dactylitis, the pooled PA0010/PA0011 
studies have a 66% power to detect a true treatment difference of 24% (odds ratio 2.71). 
Treatment difference in change from Baseline in vdHmTSS at Week 16 in the overall population 
is estimated using the data from the FUTURE 5 study in a mixed TNFα exposure population. 
The bimekizumab 160mg Q4W group treatment difference compared to placebo is estimated to 
be the same as the difference in change from Baseline in vdHmTSS at Week 16 between the 
secukinumab 150mg group and placebo which is 0.42, assuming a SD of 1.13 for bimekizumab 
and SD=2.44 for placebo. With these assumptions the study has 76% power to detect a treatment 
difference of 0.42 in the planned sample size. 

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15 
ETHICS AND REGULATORY REQUIREMENTS 
15.1 
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 US must include the use of a Health Insurance Portability 
and Accountability Act Authorization form. 
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. An 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. 
15.2 
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. 
15.3 
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, IB, Investigator’s curriculum vitae (if applicable), advertisement (if applicable), 

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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, 
Investigators are to provide the Sponsor (or its representative) with evidence of such IRB/IEC 
notification. 
15.4 
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). 
15.5 
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. 

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16 
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. 
17 
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F Test Article. Communication in Statistics-Theory and Methods 1989(11):3963-3975. 
Mundt JC, Greist JH, Gelenberg AJ, Katzelnick DJ, Jefferson JW, Modell JG. Feasibility and 
Validation of a Computer-Automated Columbia-Suicide severity Rating Scale Using Interactive 
Voice Response Technology. J Psychiatr Res. 2010;44(16):1224-8. 
Nash P, Mease PJ, McInnes IB, Rahman P, Ritchlin CT, Blanco R, et al and FUTURE 3 study 
group. Efficacy and safety of secukinumab administration by autoinjector in patients with 
psoriatic arthritis: results from a randomized, placebo-controlled trial (FUTURE 3). Arthritis Res 
Ther. 2018;15;20(1):47. 
Ogdie A, Weiss P. The epidemiology of psoriatic arthritis. Rheum Dis Clin North Am. 
2015;41(4):545-68. 
Papp KA, Leonardi C, Menter A, Ortonne JP, Krueger JG, Kricorian G, et al. Brodalumab, an 
anti–interleukin-17–receptor antibody for psoriasis. N Engl J Med. 2012;366:1181-9. 
Posner K, Brown GK, Stanley B, Brent DA, Yershova KV, Oquendo MA, et al. The 
Columbia-Suicide Severity Rating Scale: Initial validity and internal consistency findings from 
three multisite studies with adolescents and adults. Am J Psychiatry. 2011;168(12):1266-77. 
Raychaudhuri SP, Raychaudhuri SK, Genovese MC. IL-17 receptor and its functional 
significance in psoriatic arthritis. Mol Cell Biochem. 2012;359:419–29. 
Reilly MC, Zbronzek AS, Dukes EM. The Validity and Reproducibility of a Work Productivity 
and Activitiy Impairment Instrument. PharmacoEconomics. 1993:4(5):353-365. 
Salaffi F, Carotti M, Gasparini S, INtorcia M, Grassi W. The health-related quality of life in 
rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis: a comparison with a selected 
sample of healthy people. Health Qual Life Outcomes. 2009;7:25. 
Van der Heijde D, Sharp J, Wassenberg S, Gladman DD. Psoriatic arthritis imaging: a review of 
scoring methods. Ann Rheum Dis. 2005;64;ii61-ii64. 

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Van der Heijde D, Landewé RB, Mease PJ, McInnes IB, Conaghan PG, Pricop L, et al. Brief 
Report: Secukinumab Provides Significant and Sustained Inhibition of Joint Structural Damage 
in a Phase III Study of Active Psoriatic Arthritis. Arthritis Rheumatol. 2016;68(8);1914-21. 
van Tubergen A, Black PM, Coteur G. Are patient-reported outcome instruments for ankylosing 
spondylitis fit-for-purpose for the axial spondyloarthritis patient? A Qualitative and 
Psychometric Analysis. Rheum. 2015;54:1842-51. 
Watanabe H, Kawaguchi M, Fujishima S, Ogura M, Matsukura S, Takeuchi H, et al. Functional 
characterization of IL-17F as a selective neutrophil attractant in psoriasis. J Invest Dermatol. 
2009;129:650-6. 

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18 
APPENDICES 
18.1 
Classification Criteria for Psoriatic Arthritis  
Inflammatory articular disease (joint, spine, or entheseal) AND at least 3 points of the following 
5 categories: 
Table 18-1: CASPAR Criteria 
Category 
Definition 
Points 
1) Evidence of psoriasis:  
(Score for 1 of the following a) 
 
 
Current psoriasis 
Psoriatic skin or scalp disease present today as 
judged by a dermatologist or rheumatologist 
2 points 
Personal history of psoriasis 
A history of psoriasis that may be obtained from the 
subject, family physician, dermatologist, 
rheumatologist, or other qualified health care 
provider 
1 point 
Family history of psoriasis 
A history of psoriasis in a first- or second-degree 
relative according to subject report 
1 point 
2) Psoriatic nail dystrophy 
Typical psoriatic nail dystrophy, including 
onycholysis, pitting, and hyperkeratosis, observed on 
current physical examination 
1 point 
3) A negative test for rheumatoid 
factor 
By any method except latex, but preferably by 
enzyme-linked immunosorbent assay (ELISA) or 
nephelometry, according to the local laboratory 
reference range 
1 point 
4) Dactylitis:  
(Score for 1 of the following) 
 
 
Current dactylitis 
Swelling of an entire digit 
1 point 
History of dactylitis 
A history of dactylitis recorded by a rheumatologist 
1 point 
5) Radiologic evidence of 
juxta-articular new bone 
formation 
Ill-defined ossification near joint margins (but 
excluding osteophyte formation) on plain radiographs 
of the hand or foot 
1 point 
CASPAR=Classification Criteria for Psoriatic Arthritis  
 a “Score for 1 of the following” means that only 1 of the 3 criteria is applicable (either current psoriasis 
[scores 2 points], personal history [scores 1 point], or family history [scores 1 point]). 
 

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18.2 
Protocol Amendment 1 
Rationale for the amendment 
This protocol has been amended to update the completed and ongoing studies information, 
clarify study procedures, update the description of the IMP, and to apply a minimum percentage 
for enrollment of subjects who are positive for elevated hs-CRP and/or have at least 1 bone 
erosion at Screening. 
Modifications and changes 
Global changes: 
The following changes were made throughout the protocol and are not included in specific 
changes section:  
• The company name was changed from UCB Biopharma SPRL to UCB Biopharma SRL 
• The term “legal representative” was deleted from protocol, as it is not applicable to PA0010 
• “joint erosion” was changed to “bone erosion” 
• Minor spelling, editorial, and formatting changes were made throughout the document  
Specific changes: 
Change #1  
Study Contact Information 
Sponsor 
UCB Biopharma SPRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
Sponsor Study Physician 
Name: 
 
Address: 
208 Bath Road 
Slough SL1 3WE 
Phone: 
 

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Clinical Project Manager 
Name: 
 
Address: 
UCB BIOSCIENCES Inc. 
8010 Arco Corporate Drive 
Raleigh, NC 27617 
UNITED STATES 
Phone: 
 
Clinical Trial Biostatistician 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Strasse 10 
40789 Monheim am Rhein 
GERMANY 
Phone: 
 
 
Has been changed to: 
Sponsor 
UCB Biopharma SPRL SRL 
Allée de la Recherche 60 
1070 Brussels 
BELGIUM 
Sponsor Study Physician 
Name: 
 
Address: 
UCB Celltech Ltd 
208 Bath Road 
Slough SL1 3WE 
UNITED KINGDOM 
Phone: 
 

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Clinical Project Manager 
Name: 
 
Address: 
UCB BIOSCIENCES Inc. 
8010 Arco Corporate Drive 
Raleigh, NC 27617 
UNITED STATES 
Phone: 
 
Clinical Trial Biostatistician 
Name: 
 
Address: 
UCB BIOSCIENCES GmbH 
Alfred Nobel Strasse 10 208 Bath Road 
40789 Monheim am Rhein Slough SL1 3WE 
GERMANY UNITED KINGDOM 
Phone: 
 
 
Change #2 
List of Abbreviations 
The following abbreviations were added:  
HS 
hidradenitis suppurativa 
OS 
observed case 
TNF 
tumor necrosis factor  
TNFα 
tumor necrosis factor alpha 
UC 
ulcerative colitis 
 
Change #3 
Section 1 Summary, paragraphs 7 through 10 (last paragraph) 
It is planned to enroll a minimum of 35% of subjects with elevated high sensitivity C-reactive 
protein (hs-CRP) and/or with at least one bone erosion (hs-CRP ≥6mg/L and/or 
erosion-positive). 
During the Double-Blind Treatment and Active Treatment-Blind Periods, permitted rescue 
therapy after Week 16 is described in Section 5.4. Subjects’ permitted background medications 
may be changed if the subject is not responding as per Investigator assessment. 
Subjects completing Week 52 are eligible for enrollment in an extension study where all subjects 
will receive bimekizumab. 

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Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio (stratified by region and 
joint erosion [≥1]) to the following treatment groups: bimekizumab 160mg sc Q4W 
(420 subjects), placebo (280 subjects), and adalimumab sc 40mg every 2 weeks (Q2W) 
(140 subjects). The planned number of study sites is approximately 150. 
Has been changed to: 
It is planned to enroll a minimum of 3545% of subjects who are positive for with elevated high 
sensitivity C-reactive protein (hs-CRP ≥6mg/L) and/or withwho have at least one1 bone erosion 
at Screening(hs CRP ≥6mg/L and/or erosion positive). 
During the Double-Blind Treatment and Active Treatment-Blind Periods, permitted rescue 
therapy after Week 16 is described in Section 5.4. Subjects’ permitted background medications 
may be changed if the subject is not responding as per Investigator assessment. 
Subjects completing Week 52 are eligible for enrollment in an extension study where all subjects 
will receive bimekizumab. 
Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio (stratified by region and 
joint bone erosion [0, ≥1]) to the following treatment groups: bimekizumab 160mg sc Q4W 
(420 subjects), placebo (280 subjects), and adalimumab sc 40mg every 2 weeks (Q2W) 
(140 subjects). The planned number of study sites is approximately 150. 
 
Change #4 
Section 2.2 Bimekizumab, paragraph 2 
While anti-IL-17A antibodies have demonstrated efficacy in subjects with PSO, PsA, and AS, 
there is currently no therapeutic approach available that fully inhibits the activity of IL-17F. 
Bimekizumab selectively and potently inhibits the activity of both IL-17A and IL-17F isoforms 
in vitro. Therefore, it permits an evaluation of the potential for additional efficacy, which may be 
conferred by dual inhibition of both cytokines in patients with diseases in which both cytokines 
are active. Furthermore, a proof-of-concept study with bimekizumab in subjects with moderate to 
severe PsA demonstrated a strong efficacy signal that warrants further exploration of 
bimekizumab in this indication. A Phase 2b, dose-ranging study (PA0008) is an ongoing study 
that was designed to investigate the efficacy and safety of various bimekizumab dose regimens in 
subjects with active PsA. The current Phase 3, randomized, double-blind, placebo-controlled, 
and active controlled confirmatory study (PA0010) is designed to investigate the efficacy and 
safety of bimekizumab in subjects with active PsA. 
Has been changed to: 
While anti-IL-17A antibodies have demonstrated efficacy in subjects with PSO, PsA, and AS, 
there is currently no therapeutic approach available that fully inhibits the activity of IL-17F. 
Bimekizumab selectively and potently inhibits the activity of both IL-17A and IL-17F isoforms 
in vitro. Therefore, it permits an evaluation of the potential for additional efficacy, which may be 
conferred by dual inhibition of both cytokines in patients with diseases in which both cytokines 
are active. Furthermore, a proof-of-concept study (PA0007) with bimekizumab in subjects with 
moderate to severe PsA demonstrated a strong efficacy signal that warrants further exploration of 
bimekizumab in this indication. A Phase 2b, dose-ranging study (PA0008) is an ongoing study 

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that was designed to investigate the efficacy and safety of various bimekizumab dose regimens in 
subjects with active PsA. The current Phase 3, randomized, double-blind, placebo-controlled, 
and active controlled confirmatory study (PA0010) is designed to investigate the efficacy and 
safety of bimekizumab in subjects with active PsA. 
 
Change #5 
Section 2.2.1 Nonclinical, paragraph 4 
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. 
Has been changed to: 
Preliminary rResults 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. 
 
Change #6 
Section 2.2.2.1 Completed studies 
This section was updated to reflect the studies that have completed since the original protocol 
was written. Study descriptions for non-PsA studies were deleted and cross-reference to the 
bimekizumab IB was added for detail of these studies. PA0007 summary remains, and a 
summary of the recently completed PA0008 study was added. 
 
Change #7 
Section 2.2.2.2 Ongoing studies 
This section was updated to reflect studies that are ongoing as of 02 Dec 2019. 
 
Change #8 
Section 4.2.1 Secondary efficacy variables 
The secondary efficacy variables for this study are as follows: 
• PASI90 response at Week 4 and Week 16 in the subgroup of subjects with PSO involving at 
least 3% BSA at Baseline 

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• Change from Baseline in Health Assessment Questionnaire—Disability Index (HAQ-DI) at 
Week 16 
• Change from Baseline in the Short Form 36-item Health Survey (SF-36) Physical 
Component Summary (PCS) at Week 16 
• Minimal Disease Activity (MDA) response at Week 16 
• Change from Baseline in Van der Heijde modified Total Sharp Score (vdHmTSS) at 
Week 16  
• Dactylitis-free state based on the Leeds Dactylitis Index (LDI) at Week 16 in the subgroup of 
subjects with dactylitis at Baseline 
• Enthesitis-free state based on the Leeds Enthesitis Index (LEI) at Week 16 in the subgroup of 
subjects with enthesitis at Baseline 
• ACR20 response at Week 16 
• ACR70 response at Week 16 
• Proportion of subjects with an Investigator Global Assessment (IGA) score of 0 (clear) or 
1 (almost clear) AND at least a 2-grade reduction from Baseline at Week 4 and Week 16 in 
the subset of subjects with psoriatic skin lesions at Baseline  
• Change from Baseline in the Patient’s Assessment of Arthritis Pain (PtAAP) at Week 16 
• Enthesitis-free state based on the Spondyloarthritis Research Consortium of Canada 
(SPARCC) index at Week 16 in the subgroup of subjects with enthesitis at Baseline 
• Change from Baseline in Psoriatic Arthritis Impact of Disease-12 (PsAID-12) at Week 16 
Has been changed to: 
The secondary efficacy variables for this study are as follows: 
• Change from Baseline in Health Assessment Questionnaire—Disability Index (HAQ-DI) at 
Week 16 
• PASI90 response at Week 4 and Week 16 in the subgroup of subjects with PSO involving at 
least 3% BSA at Baseline 
• Change from Baseline in the Short Form 36-item Health Survey (SF-36) Physical 
Component Summary (PCS) at Week 16 
• Minimal Disease Activity (MDA) response at Week 16 
• Change from Baseline in Van der Heijde modified Total Sharp Score (vdHmTSS) in 
subjects with elevated hs-CRP and/or at least 1 bone erosion at Baseline at Week 16  
• Dactylitis-free state based on the Leeds Dactylitis Index (LDI) at Week 16 in the subgroup of 
subjects with dactylitis at Baseline 
• Change from Baseline in Enthesitis free state based on the Leeds Enthesitis Index (LEI) at 
Week 16 in the subgroup of subjects with enthesitis at Baseline 
• Change from Baseline in vdHmTSS in the overall population at Week 16 

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• ACR20 response at Week 16 
• ACR70 response at Week 16 
• Proportion of subjects with an Investigator Global Assessment (IGA) score of 0 (clear) or 
1 (almost clear) AND at least a 2-grade reduction from Baseline at Week 4 and Week 16 in 
the subset of subjects with psoriatic skin lesions at Baseline  
• Change from Baseline in the Patient’s Assessment of Arthritis Pain (PtAAP) at Week 16 
• Enthesitis-free state based on the Spondyloarthritis Research Consortium of Canada 
(SPARCC) index at Week 16 in the subgroup of subjects with enthesitis at Baseline 
• Change from Baseline in Psoriatic Arthritis Impact of Disease-12 (PsAID-12) at Week 16 
 
Change #9 
Section 4.2.2 Secondary safety variables 
Secondary safety variables to be assessed are as follows: 
• Incidence of treatment-emergent adverse events (TEAEs) 
• Incidence of SAEs 
• Adverse events (AEs) leading to withdrawal from IMP  
Has been changed to:  
Secondary safety variables to be assessed are as follows: 
• Incidence of treatment emergent adverse events (TEAEs) 
• Incidence of treatment-emergent SAEs 
• Adverse events (AEs) TEAEs leading to withdrawal from IMP  
 
Change #10 
Section 4.3.1 Other efficacy variables, the following variables had changes and/or clarifications 
• The percentage of ACR50 responders at Week 16 and maintaining response at Week 52 
• Change from Baseline in vdHmTSS total score and in erosion and joint space narrowing 
(subscores)  
• Percentage of subjects with no radiographic joint damage progression (Change from Baseline 
vdHmTSS of ≤0.5)  
• Change from Baseline in PsAID-12 
• Change from Baseline in the Patient Health Questionnaire-9 (PHQ-9) 
• Change from Baseline in the EQ-5D-3L utility score 

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Has been changed to: 
• The percentageproportion of ACR50 responders at Week 16 and maintaining response at 
Week 52 
• Change from Baseline in vdHmTSS total score and in erosion and joint space narrowing 
(subscores) in subjects with elevated hs-CRP and/or with at least 1 bone erosion at 
Baseline 
• PercentageProportion of subjects with no radiographic joint damage progression (change 
from Baseline vdHmTSS of ≤0.5)  
• Change from Baseline in PsAID-12, in the individual domains of PsAID-12 
• Change from Baseline in the Patient Health Questionnaire 9 (PHQ 9) 
• Change from Baseline in the EQ 5D 3L utility score 
 
Change #11 
Section 4.3.1 Other efficacy variables, the following new variables were added:  
• Change from Baseline in vdHmTSS total score and in erosion and joint space 
narrowing (subscores) in the overall population 
• Subjects achieving PsAID-Score ≤4 
• Change from Baseline in Physician’s Global Assessment of Arthritis (PhGA-Arthritis) 
• Change from Baseline in Patient’s Global Assessment of Arthritis (PGA-Arthritis) 
 
Change #12 
Section 4.3.2 Other safety variables, PHQ-9 variable added (was removed from Section 4.3.1 
Other efficacy variables)  
• Change from Baseline in the Patient Health Questionnaire-9 (PHQ-9) 
 
Change #13 
Section 5.1 Study description, paragraphs 1 through 5 
This is a Phase 3, multicenter, randomized, double-blind, placebo-controlled, active-reference 
study to evaluate the efficacy and safety of bimekizumab in subjects with active PsA. To be 
eligible to participate in this study, subjects must be adults with a diagnosis of active PsA based 
on the CASPAR criteria and have active disease with TJC ≥3 and SJC ≥3. It is planned to enroll 
a minimum of 35% of subjects with elevated hs-CRP and/or with at least one bone erosion 
(hs-CRP ≥6mg/L and/or erosion-positive). 
Subjects should not have previously been treated with any biologic drugs for PsA or PSO. 
Detailed inclusion and exclusion criteria are presented in Section 6.1 and Section 6.2, 
respectively. 

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The study will include 3 periods: a Screening Period (≥14 days to ≤35 days), a Treatment Period 
(52 weeks), and a Safety Follow-up Period (20 weeks after the final dose of IMP). The 
Treatment Period will consist of a 16-week Double-Blind Treatment Period followed by a 
36-week Active Treatment-Blind Period. Permitted rescue therapy changes after Week 16 are 
described in Section 5.4. The maximum study duration per subject will be up to 73 weeks. 
Eligible subjects will be randomized 3:2:1 (stratified by region and joint erosion [≥1]) to receive 
1 of 3 blinded treatments (bimekizumab 160mg sc Q4W, placebo, or active-reference 
[adalimumab 40mg sc Q2W]), and will remain on their allowable background medication. 
Details of the Treatment Period are provided in Section 5.3. 
Subjects completing Week 52 are eligible for enrollment in an extension study to continue to 
receive bimekizumab.  
Has been changed to: 
This is a Phase 3, multicenter, randomized, double-blind, placebo-controlled, active-reference 
study to evaluate the efficacy and safety of bimekizumab in subjects with active PsA. To be 
eligible to participate in this study, subjects must be adults with a diagnosis of active PsA based 
on the CASPAR criteria and have active disease with TJC ≥3 and SJC ≥3. It is planned to enroll 
a minimum of 3545% of subjects withwho are positive for elevated hs-CRP (hs-CRP ≥6mg/L) 
and/or withwho have at least one1 bone erosion at Screening (hs CRP ≥6mg/L and/or erosion
positive). 
Subjects should not have previously been treated with any biologic drugs for PsA or PSO. 
Detailed inclusion and exclusion criteria are presented in Section 6.1 and Section 6.2, 
respectively. 
The study will include 3 periods: a Screening Period (≥14 days to ≤35 days), a Treatment Period 
(52 weeks), and a Safety Follow-up Period (20 weeks after the final dose of IMP). The 
Treatment Period will consist of a 16-week Double-Blind Treatment Period followed by a 
36-week Active Treatment-Blind Period. Permitted rescue therapy changes after Week 16 are 
described in Section 5.4. The maximum study duration per subject will be up to 73 weeks. 
Eligible subjects will be randomized 3:2:1 (stratified by region and jointbone erosion [0, ≥1]) to 
receive 1 of 3 blinded treatments (bimekizumab 160mg sc Q4W, placebo, or active-reference 
[adalimumab 40mg sc Q2W]), and will remain on their allowable background medication. 
Details of the Treatment Period are provided in Section 5.3. 
Subjects completing Week 52 and meeting eligibility criteria are eligible for enrollment in an 
extension study to continue to receive bimekizumab.  
 
Change #14 
New Section 5.2.1 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 PHQ-9, electronic Columbia-Suicide 
Severity Rating Scale (eC-SSRS), or the tuberculosis (TB) questionnaire are not allowed 
to be rescreened. 

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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. 
 
Change #15 
Section 5.3.1 Double-Blind Treatment Period, paragraph 1 
During the Double-Blind Treatment Period, subjects will be randomized 3:2:1 (stratified by 
region and joint erosion [≥1]) to 1 of 3 blinded treatments. 
Has been changed to: 
During the Double-Blind Treatment Period, subjects will be randomized 3:2:1 (stratified by 
region and jointbone erosion [0, ≥1]) to 1 of 3 blinded treatments. 
 
Change #16 
Section 5.7 Planned number of subjects and sites 
Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio (stratified by region and 
joint erosion) to the following treatment groups: bimekizumab 160mg sc Q4W (420 subjects), 
placebo (280 subjects), and adalimumab 40mg sc Q2W (140 subjects). The planned number of 
study sites is approximately 150. 
Has been changed to:  
Approximately 840 subjects will be randomly assigned in a 3:2:1 ratio (stratified by region and 
jointbone erosion [0, ≥1]) to the following treatment groups: bimekizumab 160mg sc Q4W (420 
subjects), placebo (280 subjects), and adalimumab 40mg sc Q2W (140 subjects). The planned 
number of study sites is approximately 150. 
 
Change #17 
Section 5.7.1 Enrollment of hs-CRP/bone erosion positive subjects 
It is planned to enroll a minimum of 35% of subjects with elevated hs-CRP and/or with at least 
one bone erosion (hs-CRP ≥6mg/L and/or erosion-positive). 

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Has been changed to: 
It is planned to enroll a minimum of 3545% of subjects withwho are positive for elevated hs-
CRP (hs-CRP ≥6mg/L) and/or withwho have at least one1 bone erosion at Screening (hs CRP 
≥6mg/L and/or erosion positive). 
 
Change #18 
Table 5-1: Schedule of study assessments footnote a 
a Visit windows of ±2 days are allowed for all visits up to Week 16 and ±3 days are allowed for all visits after Week 
16. The time between study treatment doses should be ≥12 days and ≤16 days or ≥11 days and ≤17 days, 
respectively. The Safety Follow-Up Visit window is scheduled -3 and +7 days from the final dose. 
Has been changed to: 
a Visit windows of ±2 days are allowed for all visits up to Week 16 and ±3 days are allowed for all visits after Week 
16. The time between study treatment doses should be ≥12 days and ≤16 days or ≥11 days and ≤17 days, 
respectively. The Safety Follow UpFor the SFU Visit window is, the visit should occur no more than 3 days 
prior to the scheduled 3visit date and +within 7 days from the final dose.after the scheduled visit date (-3 
days/+7 days). 
 
Change #19 
Table 5-1: Schedule of study assessments footnote o 
o Circumference measured in millimeters. 
Has been changed to: 
o Circumference measured in millimeters. The LDI assessment of dactylitis will be obtained for all subjects at 
the Baseline visit. Subsequent to the Baseline visit, the LDI assessment will be obtained only for those 
subjects who had dactylitis at Baseline (as per the LDI assessment performed at Baseline). 
 
Change #20 
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. 

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Has 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 #21 
Section 6.3.1 Potential drug-induced liver injury IMP discontinuation criteria, paragraph 2 
The PDILI criteria below require immediate and permanent discontinuation of IMP:   
• Subjects with either of the following: 
− ALT or AST ≥8xULN 
− 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%). 
Has been changed to: 
The PDILI criteria below require immediate and permanent discontinuation of IMP:   
• Subjects with either of the following: 
− ALT or AST ≥8xULN 
− 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%). 
 
Change #22 
Section 7.1 Description of investigational medicinal products, first bullet 
• 
 
 
 

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Has been changed to: 
• 
 
 
 
. 
 
Change #23 
Table 7-2: Prohibited or restricted medications and required wash-out periods, third row 
Oral corticosteroids 
Any dose 
regimen 
Any change in dose/dose regimen in the 28 days 
prior to the Baseline Visit. 
Has been changed to: 
Oral corticosteroids 
Any dose 
regimen 
Any change in dose/dose regimen in the 2814 days 
prior to the Baseline Visit. 
 
Change #24 
Table 7-2: Prohibited or restricted medications and required wash-out periods, 10th row 
-methotrexate a 
Any dose 
regimen 
Initiation within 12 weeks prior to the Baseline 
Visit unless Inclusion Criterion #11 is met.  
Administration of LEF and MTX together is not 
permitted at any time during the study. 
Has been changed to: 
-methotrexate a 
Any dose 
regimen 
Initiation withinless than 12 weeks prior to the 
Baseline Visit unless Inclusion Criterion #11 is 
met.  
Administration of LEF and MTX together is not 
permitted at any time during the study. 
 
Change #25 
Section 8 Study Procedures By Visit, paragraph 1 
The schedule of study assessments (Table 5-1) provides an overview of study assessments. A list 
of procedures to be completed at each visit is described below. Visit windows of ±2 days are 
allowed from the first dose at all visits through to Week 16. During the 16-week Double-Blind 
Period, the time between doses should be ≥12 days and ≤16 days. Visit windows of ±3 days are 
allowed for all visits after Week 16. The time between doses during the Active Treatment-Blind 
Period should be ≥11 days and ≤17 days. 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). 

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Has been changed to: 
The schedule of study assessments (Table 5-1) provides an overview of study assessments. A list 
of procedures to be completed at each visit is described below. Visit windows of ±2 days are 
allowed from the first dose at all visits through to Week 16. During the 16-week Double-Blind 
Period, the time between doses should be ≥12 days and ≤16 days. Visit windows of ±3 days are 
allowed for all visits after Week 16. The time between doses during the Active Treatment-Blind 
Period should be ≥11 days and ≤17 days. For the SFU Visit (20 weeks after the final dose of 
IMP), 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). 
 
Change #26 
Section 9.8.1 Body surface area-psoriasis (BSA-PSO), paragraph 2 
The BSA palm method will be used for the evaluation of BSA affected by PSO as follows: 
• Subject’s palm=1% 
• Head and neck=10% (10 palms) 
• Upper extremities=20% (20 palms) 
• Trunk=30% (30 palms) 
• Lower extremities=40% (40 palms)  
• Total BSA=100% 
Has been changed to: 
The BSA palm method will be used for the evaluation of BSA affected by PSO as follows: 
• Subject’s palm=1% 
• Head and neck=10% (10 palms) 
• Upper extremities=20% (20 palms) 
• Trunk=30% (30 palms) 
• Lower extremities=40% (40 palms)  
• Total BSA=100% 
 
Change #27 
Section 9.8.3 Investigator’s Global Assessment (IGA) – new paragraphs added after Table 9-3 
The IGA response is defined as a clear [0] or almost clear [1] assessment with at least a 
2-category improvement from Baseline, meaning that this parameter will be evaluable only 
for subjects with psoriatic skin lesions (IGA score ≥2) at Baseline.    
In this study, only subjects with BSA ≥ 3% at Baseline will have IGA assessed at 
post-Baseline Visits. 

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Change #28 
Section 9.10 Disease Activity Index for Psoriatic Arthritis (DAPSA), formula 
SJC (range 0-66) + TJC (range 0-68) + PGA-Arthritis and patient’s pain assessment (VAS 
range 0-10; 0=best, 10=worst) + hs-CRP. 
Has been changed to: 
DAPSA=SJC (range 0-66) + TJC (range 0-68) + PGA-Arthritis and patient’s pain assessment 
(VAS range 0-10cm; 0=best, 10=worst) + PtAAP (VAS range 0-10cm) + hs-CRP. 
 
Change #29 
Section 12.1.4 Pregnancy, paragraph 1 
If the 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 PS. 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 final dose of IMP. 
Has been changed to: 
If the 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 PS. The 
subject should be permanently withdrawn from the studyIMP 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 the ET Visitan early ad-hoc study visit. 
• A Safety Follow-Up Visit should be scheduled 20 weeks after the 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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Change #30 
Section 12.1.4 Pregnancy, last paragraph of section was deleted 
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 study PA0010. If the study is available locally, the PA0010 
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 PA0010. 
 
Change #31 
Table 12-2: Laboratory measurements, footnote c 
c Urine drug screen will be performed at Screening Visit and ET Visit 
Has been changed to: 
c Urine drug screen will be performed at Screening Visit and ET Visit. 
 

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Change #32 
Table 12-3: Required investigations and follow-up for PDILI 
Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
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. 
Immediate, 
permanent IMP 
discontinuation. 
 
 
 
Essential: Must have 
repeat liver 
chemistry values 
and additional 
testing completed 
ASAP (see 
Section 12.2.1.3); 
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. 
 
 
 

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Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
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 12.2.1.2). 
 
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 12.2.1.3). 
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: 
• 
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, 

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Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
permanent IMP 
discontinuation 
required. 
Continue to monitor until 
values normalize, 
stabilize, or return to 
within baseline values.d 
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 12.2.1.1. 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 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. 
Has been changed to: 
Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
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. 
Immediate, 
permanent IMP 
discontinuation.d 
 
 
 
Essential: Must have 
repeat liver 
chemistry values 
and additional 
testing completed 
ASAP (see 
Section 12.2.1.3); 
recommended to 
Monitoring of liver 
chemistry values at least 
twice per week until 
values normalize, 
stabilize, or return to 
within baseline values.de 
≥3xULN 
NA 
Yes 

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Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
≥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. 
 
 
 
occur at the site with 
HCP. 

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Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
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 12.2.1.2). 
 
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 12.2.1.3). 
Monitoring of liver 
chemistry values at least 
twice per week for 2 
weeks.de 
• 
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, 

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Laboratory value 
 
Immediate 
Follow up 
ALT or 
AST 
Total 
bilirubin 
Symptomsa of 
hepatitis of 
hypersensitivity 
Consultation 
requirements 
Actions 
Testing 
Evaluation 
permanent IMP 
discontinuation 
required. 
Continue to monitor until 
values normalize, 
stabilize, or return to 
within baseline values.de 
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 12.2.1.1. 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 12.2.1.2.1. 
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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Change #33 
Section 12.2.1.2 Immediate action: determination of IMP discontinuation, paragraph 2 
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: 
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 #34 
Section 12.2.1.2.1 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: 
 

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Change #35 
Figure 14-1: Sequential testing procedure of primary/secondary efficacy endpoints (fixed 
sequence testing procedure)  
 
ACR=American College of Rheumatology; BKZ=bimekizumab; CfB=change from Baseline; H=hypothesis; 
HAQ-DI=Health Assessment Questionnaire—Disability Index; hs-CRP=high sensitivity C-reactive protein; 
LEI=Leeds Enthesitis Index; MDA=Minimal Disease Activity; PASI=Psoriasis Area and Severity Index; 
PCS=Physical Component Summary; Q4W=every 4 weeks; SF-36=Short-Form 36-item Health Survey; 
vdHmTSS=Van der Heijde modified Total Sharp Score; W=Week 
* It is planned to enroll a minimum of 35% of subjects with elevated hs-CRP and/or with at least one bone erosion 
(hs-CRP ≥6mg/L and/or erosion-positive).  
** Based on the overall population 

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Has been changed to: 
(in the revised figure [below], the “CfB HAQ-DI at W16 superior to placebo” has moved to the 
H2 position from the H3 position and the “PASI90 response at W16 superior to placebo” has 
moved to the H3 position from the H2 position.) 
 
ACR=American College of Rheumatology; BKZ=bimekizumab; CfB=change from Baseline; H=hypothesis; 
HAQ-DI=Health Assessment Questionnaire—Disability Index; hs-CRP=high sensitivity C-reactive protein; 
LEI=Leeds Enthesitis Index; MDA=Minimal Disease Activity; PASI=Psoriasis Area and Severity Index; 
PCS=Physical Component Summary; Q4W=every 4 weeks; SF-36=Short-Form 36-item Health Survey; 
vdHmTSS=Van der Heijde modified Total Sharp Score; W=Week 
* It is planned to enroll a minimum of 3545% of subjects withwho are positive for elevated hs-CRP (hs-CRP 
≥6mg/L) and/or withwho have at least one1 bone erosion at Screening(hs CRP ≥6mg/L and/or erosion positive).  
** Based on the overall population 
 
Change #36 
Section 14.3.1.1 Analysis of the primary efficacy variable   
The primary efficacy variable will be analyzed for all subjects in the RS. 
The primary endpoint is the ACR50 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 in ACR50 response and not discontinuing treatment 
early due to an AE or lack of efficacy.  
The following 4 attributes describe the estimand that will be used to define the treatment effect 
of interest for the primary efficacy analysis: 

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1. Population = Subjects meeting the protocol-specified inclusion/exclusion criteria. 
2. Subject-level outcome = ACR50 at Week 16. 
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 ACR50 at Week 16 
and not discontinuing study treatment due to an AE or lack of efficacy through Week 16.  
4. Population-level summary measure = Conditional odds ratio comparing bimekizumab to 
placebo. 
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 
multiple imputation model (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 Markov-Chain Monte 
Carlo (MCMC) method followed by logistic regression for monotone missing data. 
Any use of prohibited or rescue medications through Week 16 would constitute an important 
protocol deviation which would be accounted for when the sensitivity analysis based on the PPS 
is performed (see Section 14.3.1.1.1). 
The statistical hypothesis for the ACR50 response at Week 16 is that the conditional odds ratio 
for ACR50 response in the bimekizumab treatment compared with placebo treatment is equal 
to 1.  
A logistic regression model will be used to assess the treatment effect on ACR50 response at 
Week 16. The model will include a fixed effect for treatment. The suitability of including the 
randomization stratification variables, region and joint erosion at Baseline will be assessed, and 
will be added to the model if appropriate. Comparisons will be made using the 2-sided Wald test 
at a significance level of α=0.05 (ie, H1 in Figure 14-1). The odds ratio versus placebo, p-value, 
and the 95% CI will be calculated. 
Has been changed to: 
The primary efficacy variable will be analyzed for all subjects in the RS. 
The primary endpoint is the ACR50 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 in ACR50 response and not discontinuing treatment 
early due to an AE or lack of efficacy.  
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 meeting the protocol-specified inclusion/exclusion criteria. 
2. Subject-level outcome = ACR50 at Week 16. 

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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 ACR50 at Week 16 
and not discontinuing study treatment due to an AE or lack of efficacy through Week 16.  
4. Population-level summary measure = Conditional odds ratio comparing bimekizumab to 
placebo. 
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 
multiple imputation model (MI).  
As the ACR response is based on 7 different component scores, it is necessary to consider 
various data scenarios that could impact the calculation of response. The rules described 
here are applicable in the context of the calculation of ACR response and may differ from 
the rules applied for calculating and summarizing the components individually (some 
values may need to be imputed for component analysis but are not required here to 
evaluate ACR response).  
The following rules will be applied prior to invoking any imputation analysis at the 
variable level: 
• If a subject has a component value that is equal to 0 at Baseline and the post-
Baseline value is greater than or equal to 0, then the absolute and percent 
improvement for that component will be treated as 0 for purposes of ACR response 
calculations. 
• If a subject has a single component value that is missing at Baseline, then the 
absolute and percent improvement for that component will be treated as 0 across all 
visits for purposes of ACR response calculations. 
After these rules have been implemented, the following rules will be applied to complete the 
derivation of ACR response based on the composite estimand definition: 
• If a given visit has been preceded by an intercurrent event: 
o The endpoint at all subsequent visits (whether the data were observed or not) 
will be set to “non-response” as the subject has not met the criteria for response. 
• If a given visit has not been preceded by an intercurrent event: 
o If both the TJC and SJC are available and at least 3 of the other 5 components 
have observed data collected, the ACR response will be calculated based on 
observed data.  
o If either the TJC and SJC are missing or there are fewer than 3 of the other 
5 components with observed data at Week 16, then imputation methods will be 
applied, consistent with the predefined approach for handling intercurrent 
events. Multiple imputation will be applied, where each of the components will 
be imputed separately before deriving the response based on imputed 
components. Note: In the case where there is partial missing data at a visit 
(missing data for some components), the available observed values and the 
imputed values will be used to derive the response. 

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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. 
Any use of prohibited or rescue medications through Week 16 would constitute an important 
protocol deviation which would be accounted for when the sensitivity analysis based on the PPS 
is performed (see Section 14.3.1.1.1). 
The statistical hypothesis for the ACR50 response at Week 16 is that the conditional odds ratio 
for ACR50 response in the bimekizumab treatment compared with placebo treatment is equal 
to 1.  
A logistic regression model will be used to assess the treatment effect on ACR50 response at 
Week 16. The model will include a fixed effect for treatment. The suitability of including the 
randomization stratification variables, region and jointbone erosion at Baseline will be assessed, 
and will be added to the model if appropriate. Comparisons will be made using the 2-sided Wald 
test at a significance level of α=0.05 (ie, H1 in Figure 14-1). The odds ratio versus placebo, 
p-value, and the 95% CI will be calculated. 
Any use of prohibited or rescue medications through Week 16 would constitute an 
important protocol deviation which would be accounted for when the sensitivity analysis 
based on the PPS is performed (see Section 14.3.1.1.1). 
 
Change #37 
Section 14.3.1.1.1 Sensitivity analyses, #3   
3. The primary comparison will also be repeated for all individual components of the ACR50 
response to explore the effect of the signs and symptoms of the individual components on the 
composite endpoint. Since all ACR components are continuous variables (eg, change from 
Baseline in TJC), an analysis of covariance (ANCOVA) with treatment, region, and joint 
erosion at Baseline as fixed effects and the Baseline values as covariate will be used for the 
analysis.  
Has been changed to:  
3. The primary comparison will also be repeated for all individual components of the ACR50 
response to explore the effect of the signs and symptoms of the individual components on the 
composite endpoint. Since all ACR components are continuous variables (eg, change from 
Baseline in TJC), an analysis of covariance (ANCOVA) with treatment, region, and 
jointbone erosion at Baseline as fixed effects and the Baseline valuesvalue as a covariate 
will be used for the analysis. Note as outlined above, some additional values may need to 
be imputed for component analysis which are not required to evaluate the overall ACR 
response. 
 

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Change #38 
Section 14.3.1.2 Analysis of the secondary efficacy variables 
The secondary efficacy variables will be analyzed for all subjects in the RS.  
All binary variables that are part of the testing hierarchy are given below: 
PASI90 responders at Week 16 will be analyzed to evaluate the composite estimand. The 
composite estimand combines the clinically meaningful improvement from Baseline in 
PASI90 response and not discontinuing treatment early due to an AE or lack of efficacy. 
The proportion of subjects achieving MDA status at Week 16 will be analyzed to evaluate the 
composite estimand. The composite estimand combines (1) achieving the MDA status with 
(2) not discontinuing treatment early due to an AE or lack of efficacy. 
The proportion of subjects with dactylitis at Baseline achieving dactylitis-free status at Week 16 
will be analyzed to evaluate the composite estimand. The composite estimand combines 
(1) achieving the dactylitis-free status with (2) not discontinuing treatment early 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 compared with placebo treatment groups is equal 
to 1. 
The binary variables will be analyzed using the same analysis methods and estimand approach as 
used for the primary variable (Section 14.3.1.1). 
If appropriate ie, where the outcome variable (eg, PASI90 response) is an assessment of 
skin/dermatological manifestations of PsA the fitted model will exclude the fixed term joint 
erosion at Baseline. 
All continuous variables that are part of the testing hierarchy are given below: 
• Change from Baseline in HAQ-DI at Week 16 
• Change from Baseline in the SF-36 PCS score at Week 16  
• Change from Baseline in vdHmTSS at Week 16  
• Change from Baseline in LEI at Week 16 in the subgroup of subjects with enthesitis at 
Baseline 
Continuous variables will be analyzed to evaluate the hypothetical estimand as defined below: 
1. Population = Subjects meeting the protocol-specified inclusion/exclusion criteria 
2. Subject level outcome = variable as stated in Section 4.2.1  
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 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 

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completed the randomized study treatment through Week 16. A multiple imputation strategy 
will be used to impute data following an intercurrent event. 
4. Population-level summary measure = the difference in the adjusted means between 
bimekizumab 160mg Q4W and placebo. 
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 
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 MCMC method, followed by monotone 
regression for monotone missing data. In the case of vdHmTSS missing data, where there are 
only 2 timepoints; missing data at Week 16 will be imputed using the MCMC method. 
The statistical model for the comparison of bimekizumab and placebo will be an ANCOVA 
model with treatment, joint erosion, and region 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: 
The secondary efficacy variables will be analyzed for all subjects in the RS.  
All binary variables that are part of the testing hierarchy are given below: 
• PASI90 responders at Week 16 will be analyzed to evaluate the composite estimand. The 
composite estimand combines the clinically meaningful improvement from Baseline in 
PASI90 response and not discontinuing treatment early due to an AE or lack of efficacy. 
• The proportion of subjects achieving MDA status at Week 16 will be analyzed to evaluate 
the composite estimand. The composite estimand combines (1) achieving the MDA status 
with (2) not discontinuing treatment early due to an AE or lack of efficacy. 
• The proportion of subjects with dactylitis at Baseline achieving dactylitis-free status at 
Week 16 will be analyzed to evaluate the composite estimand. The composite estimand 
combines (1) achieving the dactylitis-free status with (2) not discontinuing treatment early 
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 compared with placebo treatment groups is equal 
to 1. 
Any missing data at Week 16 which 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 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 MCMC 
method followed by logistic regression for monotone missing data.  
In the case of MDA as the response is based on 7 different component scores, it is necessary 
to consider various data scenarios that could impact the calculation of response. The rules 

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described here are applicable in the context of the calculation of MDA response and may 
differ from the rules applied for calculating and summarizing the components individually 
(some values may need to be imputed for component analysis but are not required here to 
evaluate MDA response).  
The following rules will be applied to complete the derivation of MDA response based on 
the composite estimand definition: 
• If a given visit has been preceded by an intercurrent event: 
o The endpoint at all subsequent visits (whether the data were observed or not) 
will be set to “non-response” as the subject has not met the criteria for 
response. 
• If a given visit has not been preceded by an intercurrent event: 
o If at least 5 of the 7 components have observed data collected, the MDA 
response will be calculated based on observed data.  
o If there are fewer than 5 of the 7 components with observed data at Week 16, 
then imputation methods will be applied, consistent with the predefined 
approach for handling intercurrent events. Multiple imputation will be applied, 
where each of the components will be imputed separately before deriving the 
response based on imputed components. Note: In the case where there is partial 
missing data at a visit (missing data for some components), the available 
observed values and the imputed values will be used to derive the response. 
The binary variables will be analyzed using the same analysis methods and estimand approach as 
used for the primary variable (Section 14.3.1.1). 
If appropriate ie, where the outcome variable (eg, PASI90 response) is an assessment of 
skin/dermatological manifestations of PsA the fitted model will exclude the fixed term jointbone 
erosion at Baseline. 
All continuous variables that are part of the testing hierarchy are given below: 
• Change from Baseline in HAQ-DI at Week 16 
• Change from Baseline in the SF-36 PCS score at Week 16  
• Change from Baseline in vdHmTSS at Week 16  
• Change from Baseline in LEI at Week 16 in the subgroup of subjects with enthesitis at 
Baseline 
Continuous variables will be analyzed to evaluate the hypothetical estimand as defined below: 
1. Population = Subjects meeting the protocol-specified inclusion/exclusion criteria 
2. Subject level outcome = variable as stated in Section 4.2.1  
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 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 

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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. 
4. Population-level summary measure = the difference in the adjusted means between 
bimekizumab 160mg Q4W and placebo. 
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 
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 MCMC method, followed by monotone 
regression for monotone missing data. In the case of vdHmTSS missing data, where there are 
only 2 timepoints; missing data at Week 16 will be imputed using the MCMC method. 
In the case of vdHmTSS missing data, where there are only 2 timepoints; missing data at 
Week 16 will be imputed using the MCMC method. 
The statistical model for continuous endpoints for the comparison of bimekizumab and placebo 
will be an ANCOVA model with treatment, jointbone erosion, and region 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 as well as 
nonresponder imputation (NRI) for binary variables. 
 
Change #39 
Section 14.3.2 Analysis of the other efficacy variables, paragraph 3 through end 
Any missing data that is 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. 
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 HAQ-DI at Week 36) 
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 

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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 ACR20/50/70 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 
treatment discontinuation. Subjects in the placebo group who are rerandomized at Week 16 
without achieving response will be censored at the date of the Week 16 Visit. The median time to 
response, including the 2-sided 95% CI, will be calculated for each treatment. Between group 
differences will be analyzed with a log-rank statistic. 
Has been changed to: 
Any missing data that is not preceded by an intercurrent event as described above will be 
imputed based on a predefined multiple imputation model 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 HAQ-DI at Week 36) 
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.  
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. 

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In some cases, other Other binary and continuous efficacy variables willmay 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 ACR20/50/70 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 
treatment discontinuation. Subjects in the placebo group who are rerandomized at Week 16 
without achieving response will be censored at the date of the Week 16 Visit. The median time to 
response, including the 2-sided 95% CI, will be calculated for each treatment. Between group 
differences will be analyzed with a log-rank statistic. 
The time to ACR20/50/70 endpoints with 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. 
The time to ACR20/50/70 endpoints will also be analyzed using observed case (OC) data. 
 
Change #40 
Section 14.3.3 Subgroup analyses—the following subgroup analysis added: 
• Concomitantly receiving MTX versus no concomitant MTX 
 
Change #41 
Section 14.7 Handling of dropouts or missing data, paragraph 2  
Missing data will be evaluated as sensitivity analyses using different missing data mechanisms. 
The following sensitivity analyses for the primary efficacy variable and for those secondary 
efficacy variables that are part of the hierarchical testing will be conducted: 
Has been changed to: 
Missing data will be evaluated as sensitivity analyses using different missing data mechanisms. 
The following sensitivity analyses for the primary efficacy variable and for those secondary 
efficacy variables that are part of the hierarchical testing will be conducted: 
 
Change #42 
Section 14.7 Handling of dropouts or missing data, last paragraph (new text added before 
paragraph)  
Additional details on these sensitivity analyses will be provided in the SAP. 
Has been changed to: 
5. Nonresponder imputation analysis will also be performed where subjects will be 
considered “nonresponders” at the timepoint of interest if: 

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− Subjects are missing data at the time point of interest. 
− Subjects remained in the study but have discontinued study treatment due to an AE 
or lack of efficacy before the time point of interest. 
For the secondary efficacy variables, the binary endpoints will be analyzed using both NRI 
and OC and for continuous endpoints OC will be performed. 
For the other efficacy endpoints, OC analysis will be conducted for both binary and 
continuous variables. 
Additional details on these sensitivity analyses will be provided in the SAP. 
 
Change #43 
Section 14.8.1 Interim analyses—new sentence added to end of section 
Additional data cuts may be prepared following regulatory requests or for publication 
purposes. 
 
Change #44 
Section 14.8.2 Data monitoring—new sentence added after paragraph 2  
Other adjudication committees may be added as necessary. 
 
Change #45 
Section 14.9.2 Power calculations for secondary endpoints, paragraph 6, paragraph 7, and 
Table 14-1 
For change from Baseline in vdHmTSS at Week 16, the between treatment differences of the 
change from Baseline in vdHmTSS at Week 16 of the SPIRIT P1 study in a TNFα-naive 
population (Mease et al, 2017) were used. The SPIRIT P1 study ixekizumab 80mg sc Q2W 
treatment group least square (LS) mean change from Baseline at Week 16 0.06 and SD 0.720; 
and LS mean change from Baseline 0.36 and SD 0.710 for placebo are assumed. With those 
assumptions, the study has a 84% power to detect a true treatment difference of -0.30, assuming 
30% of subjects with joint erosion, in the planned sample size. 
There is uncertainty in the final percentage of subjects with joint erosion at Baseline that will be 
recruited to the study and the variability in the subgroup. To demonstrate the sensitivity of the 
sample size calculation for this study, Table 14-1 shows the power function for a fixed total 
sample size of 840 subjects in the RS population for this secondary efficacy analysis, varying the 
percentage of subjects with joint erosion at Baseline and the treatment difference and estimated 
standard deviation on the change from Baseline in vdHmTSS at Week 16. 

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Table 14-1: Treatment effect by joint erosion at Baseline for secondary efficacy 
analyses 
Subjects with joint erosion at Baseline 
Treatment difference/standard deviation 
 
Treatment effect = -0.3 
SD=0.72 vs 0.71 
Treatment effect = -0.35 
SD=0.81 vs 0.93 
20% 
67 
62 
25% 
76 
72 
30% 
84 
79 
35% 
89 
85 
40% 
92 
89 
45% 
95 
92 
50% 
96 
95 
SD=standard deviation 
Has been changed to: 
For change from Baseline in vdHmTSS at Week 16, the between treatment differences of the 
change from Baseline in vdHmTSS at Week 16 of the SPIRIT P1 study in a TNFα-naive 
population (Mease et al, 2017) were used. The SPIRIT P1 study ixekizumab 80mg sc Q2W 
treatment group least square (LS) mean change from Baseline at Week 16 0.06 and SD 0.720; 
and LS mean change from Baseline 0.36 and SD 0.710 for placebo are assumed. With those 
assumptions, the study has a 8495% power to detect a true treatment difference of -0.30, 
assuming 3045% of subjects with jointelevated hs-CRP and/or bone erosion, in the planned 
sample size. 
There is uncertainty in the final percentage of subjects with jointelevated hs-CRP and/or bone 
erosion at Baseline that will be recruited to the study and the variability in the subgroup. To 
demonstrate the sensitivity of the sample size calculation for this study, Table 14-1 shows the 
power function for a fixed total sample size of 840 subjects in the RS population for this 
secondary efficacy analysis, varying the percentage of subjects with jointelevated hs-CRP 
and/or bone erosion at Baseline and the treatment difference and estimated standard deviation 
on the change from Baseline in vdHmTSS at Week 16. 

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Table 14-1: Treatment effect by jointelevated hs-CRP and/or bone erosion at 
Baseline for secondary efficacy analyses 
Subjects with jointelevated hs-CRP 
and/or bone erosion at Baseline 
Treatment difference/standard deviation 
 
Treatment effect = -0.3 
SD=0.72 vs 0.71 
Treatment effect = -0.35 
SD=0.81 vs 0.93 
20% 
67 
62 
25% 
76 
72 
30% 
84 
79 
35% 
89 
85 
40% 
92 
89 
45% 
95 
92 
50% 
96 
95 
hs-CRP=high sensitivity C-reactive protein; SD=standard deviation 
 
 

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18.3 
Protocol Amendment 2 
The main purpose of this protocol amendment was to modify the secondary variables and fixed 
sequence testing procedure, update the statistical section, and make other procedural 
clarifications. 
Modifications and changes 
Global changes: 
Throughout the protocol, FACIT-F has been corrected to FACIT-Fatigue subscale, as it is the 
fatigue subscale that is being assessed in this study. In addition, minor spelling, editorial, and 
formatting changes were made throughout the protocol. These global changes are not included in 
specific changes table that follows.  
 

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Specific changes: 
Protocol section 
impacted 
Key components of previous 
protocol text 
Key components of revised protocol 
text 
Rationale 
Change 1: Administrative section 
Study contact details 
 
UCB Celltech Ltd 
208 Bath Road 
Slough SL1 3WE 
 
 
 
UCB Celltech Ltd 
208 Bath Road 
Slough SL1 3WE 
 
The Sponsor Study Physician has 
changed. 
 
UCB BIOSCIENCES Inc. 
8010 Arco Corporate Drive 
Raleigh, NC 27617 
UNITED STATES 
 
 
UCB BIOSCIENCES GmbH 
Alfred-Nobel-Str. 10 
40789 Monheim 
GERMANY 
 
The Clinical Project Manager has 
changed.  
Change 2: Abbreviation added 
List of abbreviations 
Abbreviations and definitions added for the following: LN, PsARC, PASDAS 
Abbreviations used in text. 
Change 3: Updated text in clinical studies section 
Section 2.2.2.1 
The list of completed studies was updated consistent with the current 
bimekizumab IB.  
More studies have completed, and 
additional studies have started, 
since the last protocol amendment. 
Section 2.2.2.2 
The list of ongoing studies was updated consistent with the current bimekizumab 
IB. 

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Protocol section 
impacted 
Key components of previous 
protocol text 
Key components of revised protocol 
text 
Rationale 
Change 4: Updated 2 secondary efficacy variables 
Section 4.2.1 
• 
Dactylitis-free state based on the 
Leeds Dactylitis Index (LDI) at 
Week 16 in the subgroup of 
subjects with dactylitis at Baseline  
• 
Change from Baseline in the Leeds 
Enthesitis Index (LEI) at Week 16 
in the subgroup of subjects with 
enthesitis at Baseline 
• 
Change from Baseline Enthesitis-
free state in the Leeds Enthesitis 
Index (LEI) at Week 16 in the 
subgroup of subjects with 
enthesitis at Baseline in the 
pooled population of PA0010 
and PA0011 
• 
Dactylitis-free state based on the 
Leeds Dactylitis Index (LDI) at 
Week 16 in the subgroup of 
subjects with dactylitis at Baseline 
in the pooled population of 
PA0010 and PA0011 
In order to provide more clinically 
interpretable results for dactylitis 
and enthesitis endpoints across a 
more robust mixed population 
(TNF-inadequate responders and 
bDMARD-naïve), the endpoints of 
dactylitis free-state and enthesitis 
free-state will be analyzed using a 
pooled PA0010 and PA0011 
population. 
Given similar power between 
dactylitis and enthesitis, the 
enthesitis endpoint was moved up 
in the statistical testing hierarchy as 
it is considered a more relevant 
clinical endpoint.  
Section 14.3.1 
Figure 14-1 
In Figure 14-1 Sequential testing procedure of primary/secondary efficacy 
endpoints (fixed sequence testing procedure), the enthesitis and dactylitis 
variables were updated to be based on the pooled population of PA0010 and 
PA0011, and the enthesitis-free state variable was moved above the dactylitis-
free state variable in the figure. 

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Protocol section 
impacted 
Key components of previous 
protocol text 
Key components of revised protocol 
text 
Rationale 
Change 5: Added 7 new Other efficacy variables 
Section 4.3.1 
Added the following variables:  
• 
Composite endpoint composed of ACR50 and PASI100 response in 
subjects with PSO involving at least 3% BSA at Baseline 
• 
Proportion of Psoriatic Arthritis Response Criteria (PsARC) responders 
• 
Psoriatic Arthritis Disease Activity Score (PASDAS) categories 
• 
Change from Baseline in the PASDAS  
• 
Proportion of subjects with a decrease of HAQ-DI from Baseline of at 
least 0.35 in those subjects with HAQ-DI >0.35 at Baseline 
• 
Proportion of PSAID-12 responders (decrease from Baseline in 
PsAID-12 total score ≥3 in subjects with PsAID-12 total score >3 at 
Baseline 
• 
Proportion of FACIT-Fatigue subscale responders (minimum 
clinically important difference for FACIT-Fatigue subscale score, 
defined as an increase of ≥4 
Updated to be consistent with 
variables added to the SAP 
Change 6: Updated wording in other efficacy variables 
Section 4.3.1 
• 
Dactylitis-free state based on the 
LDI in the subgroup of subjects 
with dactylitis at Baseline 
• 
Dactylitis-free state based on the 
LDI in the subgroup of subjects 
with dactylitis at Baseline in the 
pooled population of PA0010 
and PA0011, as well as PA0010 
alone 
Updated to be consistent with 
changes made to the dactylitis and 
enthesitis secondary efficacy 
variables and to specify that the 
PA0010-only population will also 
be analyzed. 
• 
Enthesitis-free state based on the 
LEI in the subgroup of subjects 
with enthesitis at Baseline 
• 
Enthesitis-free state based on the 
LEI in the subgroup of subjects 
with enthesitis at Baseline in the 
pooled population of PA0010 
and PA0011, as well as PA0010 
alone 

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Protocol section 
impacted 
Key components of previous 
protocol text 
Key components of revised protocol 
text 
Rationale 
Section 4.3.1 
• 
Enthesitis-free state based on the 
SPARCC index in the subgroup of 
subjects with enthesitis at Baseline 
• 
Enthesitis-free state based on the 
SPARCC index in the subgroup of 
subjects with enthesitis at Baseline 
in the pooled population of 
PA0010 and PA0011, as well as 
PA0010 alone 
Updated to be consistent with 
changes made to the dactylitis and 
enthesitis secondary efficacy 
variables and to specify that the 
PA0010-only population will also 
be analyzed. 
• 
Change from Baseline in the LEI 
in the subgroup of subjects with 
enthesitis at Baseline 
• 
Change from Baseline in the LEI 
in the subgroup of subjects with 
enthesitis at Baseline in the 
pooled population of PA0010 
and PA0011, as well as for 
PA0010 alone 
• 
Change from Baseline in the 
SPARCC index in the subgroup of 
subjects with enthesitis at Baseline 
• 
Change from Baseline in the 
SPARCC index in the subgroup of 
subjects with enthesitis at Baseline 
in the pooled population of 
PA0010 and PA0011, as well as 
for PA0010 alone  
• 
Change from Baseline in the LDI 
in the subgroup of subjects with 
dactylitis at Baseline 
• 
Change from Baseline in the LDI 
in the subgroup of subjects with 
dactylitis at Baseline in the pooled 
population of PA0010 and 
PA0011, as well as for PA0010 
alone 

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Protocol section 
impacted 
Key components of previous 
protocol text 
Key components of revised protocol 
text 
Rationale 
Section 4.3.1 
• 
Disease Activity Index for 
Psoriatic Arthritis (DAPSA) 
• 
Disease Activity Index for 
Psoriatic Arthritis (DAPSA) score 
categories 
Corrected wording  
• 
Change from Baseline in 
PsAID-12, in the individual 
domains of PsAID-12 
• 
Change from Baseline in 
PsAID-12 total score, as well as 
in the individual domain scores 
• 
Change from Baseline in the 
Psoriatic Arthritis Quality of Life 
(PsAQoL) 
• 
Change from Baseline in the 
Psoriatic Arthritis Quality of Life 
(PsAQoL) total score 
• 
Change from Baseline in 
Functional Assessment of Chronic 
Illness Therapy—Fatigue 
(FACIT-F) 
• 
Change from Baseline in 
Functional Assessment of Chronic 
Illness Therapy—Fatigue 
(FACIT F) subscale score 
Change 7: Made minor updates to Double-Blind Treatment Period section and Active Treatment Period section text 
Section 5.3.1 
2nd paragraph: Investigational 
medicinal product treatment details are 
provided in Section 7.2. Visit windows 
of ±2 days are allowed for all visits up 
to Week 16. The visit window is 
relative to the Day 1 (Baseline) Visit. 
5th paragraph: Subjects withdrawing 
early from the study will undergo the 
Early Termination (ET) Visit 
assessments and will enter the SFU 
Period. Subjects who withdraw from 
IMP during the Double-Blind Period 
will return for all scheduled visits up to 
Week 52 and for the SFU Visit (20 
weeks after their final dose of IMP). 
2nd paragraph: Investigational 
medicinal product treatment details are 
provided in Section 7.2. Visit windows 
of ±2 days are allowed for all visits up 
tothrough Week 16. The visit window 
is relative to the Day 1 (Baseline) 
Visit. 
5th paragraph: Subjects withdrawing 
early from the study will undergo the 
Early Termination (ET) Visit 
assessments and will enter the SFU 
Period. Subjects who withdraw from 
IMP during the Double-Blind Period 
will be encouraged to return for all 
scheduled visits up to Week 52 and for 
Clarification of text. 

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Protocol section 
impacted 
Key components of previous 
protocol text 
Key components of revised protocol 
text 
Rationale 
the SFU Visit (20 weeks after their 
final dose of IMP), as applicable. 
Section 5.3.2 
5th paragraph: Subjects who withdraw 
early from the study will undergo the 
ET Visit assessments and will enter the 
SFU Period. Subjects who withdraw 
from IMP during the Active-
Treatment-Blind Period will return for 
all remaining scheduled visits up to 
Week 52 and the SFU Visit (20 weeks 
after their final dose of IMP). 
5th paragraph: Subjects who withdraw 
early from the study will undergo the 
ET Visit assessments and will enter the 
SFU Period. Subjects who withdraw 
from IMP during the Active-
Treatment-Blind Period will be 
encouraged to return for all remaining 
scheduled visits up to Week 52 and the 
SFU Visit (20 weeks after their final 
dose of IMP), as applicable. 
Clarification of text. 
Change 8: Made minor updates to Schedule of study assessments footnote o 
Table 5-1 
o 
Circumference measured in 
millimeters. The LDI assessment of 
dactylitis will be obtained for all 
subjects at the Baseline visit. 
Subsequent to the Baseline visit, 
the LDI assessment will be 
obtained only for those subjects 
who had dactylitis at Baseline (as 
per the LDI assessment performed 
at Baseline). 
o Circumference measured in 
millimeters. The LDI assessment of 
dactylitis will be obtained for all 
subjects at the Baseline visit. 
Subsequent to the Baseline visit, the 
LDI assessment will be obtained 
only for those subjects who had 
dactylitis at Baseline (as per the LDI 
assessment performed at Baseline). 
Correction of footnote ‘o,’ as the 
LDI assessment is being done at 
every visit. 
Change 9: Added a withdrawal criterion 
Section 6.3 
Added the following to the list of withdrawal criteria: 
13. 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 
In line with the exclusion 
criterion 11 regarding infections, a 
specific infection-related 
withdrawal criterion was added to 
clarify that patients with serious or 
recurrent infections not responding 

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and contact the Medical Monitor and UCB study physician to confirm the 
subject’s suitability for continued participation in the study. 
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. 
Change 10: Updated the permitted concomitant treatments section 
Section 7.8.1 
Added the following paragraph to the section:  
Subjects are allowed to use any other medications, including biologics, after at 
least 28 days of last dose of the IMP. This is applicable for subjects who 
discontinue from IMP or 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.  
Clarification of permitted 
concomitant medications. 
Change 11: Updated FACIT-F assessment section 
Section 9.19 
The FACIT–F scale (Cella et al, 2005) 
will be used to assess fatigue in PsA 
patients. The FACIT-F has been 
validated in the general population, in 
patients with RA, and in patients with 
PsA. The minimum clinically 
important difference for FACIT-F in 
patients with RA was determined to be 
a 3 to 4-point change; this minimum 
clinically important difference will be 
used in evaluating clinically 
meaningful changes in fatigue for 
patients with PsA. 
The FACIT F scale (Cella et al, 2005) 
will be used to assess fatigue in PsA 
patients. The FACIT-Fatigue 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 
Added a reference for FACIT-
Fatigue subscale use in PsA. 
Wording changes implemented for 
consistency with the user manuals 
and to reflect precise description of 
the PRO tools and scoring (change 
in terminology but no change in the 
method). 

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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 has been 
validated in the general population, in 
patients with RA, and in patients with 
PsA. The minimum clinically 
important difference for 
FACIT-Fatigue subscale in patients 
with RAPsA was determined to be a 3   
to 4-point change (Cella et al, 2019); 
this minimum clinically important 
difference will be used in evaluating 
clinically meaningful changes in 
fatigue for patients with PsA. 
Change 12: Updated SF-36 assessment section 
Section 9.20 
In addition to domain scores, the PCS 
and MCS 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 
In addition to domain scores, the PCS 
and MCS scores are calculated from 
the 8 domains (excluding the Health 
Transition item). Component scores 
appreciate reflect 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 scores (PCS and MCS) and 
Wording changes implemented for 
consistency with the user manuals 
and to reflect precise description of 
the PRO tools and scoring (change 
in terminology but no change in the 
method). 

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50 and a standard deviation (SD) of 10 
in the general US population. 
the 8 domains 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. 
Change 13: Added 2 new sections to describe the PsARC and PASDAS efficacy assessments added in new Other efficacy variables 
New Section 9.23 
Section 9.23 Psoriatic Arthritis Response Criteria (PsARC) added to describe the 
PsARC efficacy assessment 
The PsARC was added in a new 
Other efficacy variable 
New Section 9.24 
Section 9.24 Psoriatic Arthritis Disease Activity Score (PASDAS) added to 
describe the PASDAS efficacy assessment 
The PASDAS was added in 2 new 
Other efficacy variables. 

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Change 14: Moved PHQ-9 assessment section from efficacy assessments to safety assessments  
Old Section 9.23 
moved to  
New Section 12.3.8 
12.3.5 Assessment and management of 
TB and TB risk factors 
12.3.6 Pregnancy testing 
12.3.7 Assessment of suicidal ideation 
and behavior  
12.3.5 Assessment and management of 
TB and TB risk factors 
12.3.6 Pregnancy testing 
12.3.7 Assessment of suicidal ideation 
and behavior  
12.3.8 Patient Health 
Questionnaire-9 (PHQ-9) 
In PA0010 Protocol Amendment 1, 
the PHQ-9 was moved to Other 
safety variables from Other efficacy 
variables, but the assessment 
description section was not moved. 
In the current amendment (#2), the 
PHQ-9 assessment description 
section was moved to align with the 
variables. 
Change 15: Updated Other safety topics of interest section 
Section 12.1.1.4 
Prespecified 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). 
Prespecified 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). 
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 PHQ-9 and will 
be captured via routine AE 
reporting during the study. This 
update is considered a procedural 
change. 

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Change 16: Updated Evaluation of PDILI section 
Section 12.2.1 
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 AEs 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). 
All PDILI events must be reported as 
an AE and reported to the study site 
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). 
Clarified PDILI event reporting 
procedure. 
Section 12.2.1.2 
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). 
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). 
Clarify the range of potential 
actions. 
Change 17: Updated the analysis set definition section 
Section 14.1 
• 
The Per-Protocol Set (PPS) will 
consist of all subjects in the RS 
who had no important protocol 
deviations affecting the primary 
efficacy variable. Important 
protocol deviations will be 
predefined and subjects with 
important protocol deviations will 
• 
The Per-Protocol Set (PPS) will 
consist of all subjects in the RS 
who had no important protocol 
deviations affecting the primary 
efficacy variable. Important 
protocol deviations will be 
predefined and subjects with 
important protocol deviations will 
Clarified PPS and PK-PPS 
definitions. 
Added COVID-19-free analysis set 
to determine if COVID-19 has an 
impact on analyses. 

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be evaluated during ongoing data 
cleaning meetings prior to 
unblinding of the data. 
• 
The Pharmacokinetic Per-Protocol 
Set (PK-PPS) consists of all 
randomized subjects who received 
at least one dose of the IMP and 
provided at least one quantifiable 
plasma concentration post-dose 
without important protocol 
deviations that would affect the 
concentration.  
 
be evaluated during ongoing data 
cleaning meetings 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 Pharmacokinetic Per-Protocol 
Set (PK-PPS) consists of all 
randomized subjects who received 
at least one dose of the IMP and 
provided at least one quantifiable 
plasma concentration post-dose 
without important protocol 
deviations that would affect the 
concentration. Exclusions from 
the FAS will be considered 
important protocol deviations 
that also result in exclusion from 
the PK-PPS. 
• 
The COVID-19-free Set will 
consist of all subjects in the RS 
who had no COVID-19 impact 
up to the primary efficacy 
endpoint. This will be defined as 
subjects not having a COVID-19 
related important protocol 
deviation, nor having an impact 
based on the COVID-19 eCRF, 
nor having an AE related to 
COVID-19, nor discontinuing 
due to COVID-19 up to the time 
of the primary endpoint. 

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Change 18: Updated text in analysis of the primary efficacy variables section 
Section 14.3.1.1 
Updated text regarding the statistical approach to be used for analyzing primary 
efficacy variable. 
Updated statistical methods based 
on feedback from the FDA. 
Change 19: Updated title and text in former Sensitivity analyses section 
Section 14.3.1.1.1 
Updated title of this section from Sensitivity analyses to SensitivitySupportive 
Analyses. Also, updated text regarding the statistical approach to be used for the 
supportive analyses. 
Updated statistical methods based 
on feedback from the FDA. 
Change 20: Updated text in analysis of the secondary efficacy variables section 
Section 14.3.1.2 
Updated text regarding the statistical approach to be used for analyzing 
secondary efficacy variables. 
Updated statistical methods based 
on feedback from the FDA. 
Change 21: Updated text in analysis of the other efficacy variables section 
Section 14.3.2 
Updated text regarding the statistical approach to be used for analyzing the other 
efficacy variables. 
Updated statistical methods based 
on feedback from the FDA. 
Change 22: Updated text in handling of dropouts or missing data section 
Section 14.7 
Updated the statistical approach to be used for missing data. 
Updated statistical methods based 
on feedback from the FDA. 
Change 23: Updated the power calculation text for enthesitis-free state and dactylitis-free state 
Section 14.9.2 
For dactylitis-free state at Week 16, it 
has been assumed that 25% of all 
subjects have dactylitis symptoms at 
Baseline. Dactylitis resolution data of 
the FUTURE 5 study (Mease et al, 
2018) at Week 16 were used to 
estimate the bimekizumab 160mg 
Q4W treatment and placebo groups. 
The treatment effect estimate from the 
secukinumab 150mg treatment group 
at Week 16 of 56% (n=103) is assumed 
For dactylitis-free state at Week 16, it 
has been assumed that 25% of all 
subjects have dactylitis symptoms at 
Baseline. Dactylitis resolution data of 
the FUTURE 5 study (Mease et al, 
2018) at Week 16 were used to 
estimate the bimekizumab 160mg 
Q4W treatment and placebo groups. 
The treatment effect estimate from the 
secukinumab 150mg treatment group 
at Week 16 of 56% (n=103) is 
Updated the power calculation 
based on pooled population of 
PA0010 and PA0011. 

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versus a placebo group estimate of 
32% (n=124). With those assumptions, 
the study has an 85% power to detect a 
true treatment difference of 24% (odds 
ratio 2.71), assuming 25% of subjects 
at Baseline with dactylitis of the 
planned sample size. 
assumed versus a placebo group 
estimate of 32% (n=124). With those 
assumptions and having 11% of 
subjects with Baseline dactylitis, the 
study has an 85 pooled 
PA0010/PA0011 studies have a 66% 
power to detect a true treatment 
difference of 24% (odds ratio 2.71), 
assuming 25% of subjects at Baseline 
with dactylitis of the planned sample 
size. 
For change from Baseline in LEI 
Week 16, it has been assumed that 
50% of all subjects have enthesitis 
symptoms at Baseline. Enthesitis 
change from Baseline in LEI data at 
Week 16 of the FUTURE 2 study in 
the mixed TNFα exposure population 
(McInnes et al, 2015) were used to 
estimate the bimekizumab 160mg 
Q4W treatment and placebo groups. 
The FUTURE 2 treatment effect 
estimate from the secukinumab 150mg 
treatment group at Week 16 of -1.5 
(SD=2.0) is assumed versus a placebo 
group estimate of -0.9 (SD=2.1). With 
those assumptions, the study has 76% 
power of detecting a true treatment 
difference of 0.6 assuming 50% of 
subjects with enthesitis at Baseline of 
the planned sample size. 
For change from Baseline in LEI 
Week 16, it has been assumed that 
50% of all subjects have enthesitis 
symptoms at Baseline. Enthesitis 
change from Baseline in LEI data at 
Week 16 of the FUTURE 2 study in 
the mixed TNFα exposure population 
(McInnes et al, 2015) were used to 
estimate the bimekizumab 160mg 
Q4W treatment and placebo groups. 
The FUTURE 2 treatment effect 
estimate from the secukinumab 150mg 
treatment group at Week 16 of 1.5 
(SD=2.0) is assumed versus a placebo 
group estimate of 0.9 (SD=2.1). With 
those assumptions, the study has 76% 
power of detecting a true treatment 
difference of 0.6 assuming 50% of 
subjects with enthesitis at Baseline of 
the planned sample size. 
For enthesis free-state at Week 16, 
enthesis resolution data from the 
The secondary endpoint for 
enthesitis was updated to enthesitis-
free state from change from 
Baseline in LEI, and the power 
calculation was updated based on 
pooled population of PA0010 and 
PA0011 

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FUTURE 5 study at Week 16 were 
used to estimate the bimekizumab 
160mg Q4W treatment and placebo 
groups. In FUTURE 5 The 
treatment effect estimate from the 
secukinumab 150mg treatment 
group at Week 16 was 55% (n=141) 
and the placebo group estimate was 
36% (n=192). Assuming a BKZ 
response of 55% and a placebo rate 
of 39% and having 25% of subjects 
with Baseline enthesis the pooled 
PA0010/PA0011 the studies have a 
69% power to detect a true 
treatment difference of 16% (odds 
ratio 1.91). 
Change 24: Updated reference list 
References 
Deleted the following 2 references due to updates made in Section 14.7 Handling 
of dropouts or missing data: 
Mallinckrodt CH, Lin Q, Lipkovich I, Molenberghs G. A structured approach 
to choosing estimands and estimators in longitudinal clinical trials. Pharm 
Stat. 2012;11:456 61. 
Mallinckrodt CH. Preventing and Treating Missing Data in Longitudinal 
Clinical Trials: A Practical Guide. New York, NY: Cambridge University 
Press; 2013. 
Added the following 3 references, 1 for FACIT-Fatigue subscale and 2 for 
PASDAS: 
Cella D, Wilson H, Shalhoub H, Revicki DA, Cappelleri JC, Bushmakin AG, 
et al. Content validity and psychometric evaluation of Functional Assessment 
of Chronic Illness Therapy-Fatigue in patients with psoriatic arthritis. J 
Patient Rep Outcomes. 2019;3(1):5. 
Deleted Mallinckrodt references, as 
they are no longer applicable due to 
statistical updates. 
Additional references were 
deleted/added to support the 
assessments of FACIT-Fatigue 
subscale and PASDAS. 

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Coates LC, FitzGerald O, Mease PJ, Gladman DD, Strand V, Goel N, 
Campbell I, et al. Development of a disease activity and responder index for 
psoriatic arthritis – Report of the Psoriatic Arthrits Module at OMERACT 11. 
J Rheumatol 2014;41:782-91. 
Coates LC, Gladman DD, Nash P, FitzGerald O, Kavanaugh A, Kvien TK, et 
al. Secukinumab provides sustained PASDAS-defined remission in psoriatic 
arthritis and improves health-related quality of life in patients achieving 
remission: 2-year results from the Phase III FUTURE 2 study. Arthritis Res 
Ther. 2018;20(1):272. doi: 10.1186/s13075-018-1773-y. 
Deleted the following FACIT reference because it was superseded by the Cella 
et al, 2019 reference: 
Cella D, Yount S, Sorensen M, Chartash E, Sengupta N, Grober J. Validation 
of the Functional Assessment of Chronic Illness Therapy Fatigue Scale 
relative to other instrumentation in patients with rheumatoid arthritis. J 
Rheumatol. 2005;32:811 19. 
 

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19 
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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20 
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 GCP.