A Randomized, Double-Blind, Adaptive, Phase II/III Study of GSK3359609 in Combination With Pembrolizumab and 5FU-Platinum Chemotherapy Versus Placebo in Combination With Pembrolizumab Plus 5FU-Platinum Chemotherapy for First-Line Treatment of Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma
Phase: PHASE3
Conditions: Neoplasms, Head and Neck
Sponsor: GlaxoSmithKline

0 
 
 
 
Protocol Amendment 02 
Study ID:  209227 
Official Title of Study:  A Randomized, Double-Blind, Adaptive, Phase II/III Study of 
GSK3359609 in Combination with Pembrolizum ab and 5FU-Platinum Chemotherapy 
versus Placebo in Combination with Pembrolizumab plus 5FU-Platinum Chemotherapy 
for First-Line Treatment of Recurrent/Metastatic Head and Neck Squamous Cell 
Carcinoma 
NCT ID: NCT04428333 
Date of Document: 30-JUN-2021 

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GlaxoSmithKline group of companies 
 
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TITLE PAGE 
Protocol Title: A Randomized, Double-Blind, Adaptive, Phase II/III Study of 
GSK3359609 in Combination with Pembrolizum ab and 5FU-Platinum Chemotherapy 
versus Placebo in Combination with Pembrolizumab plus 5FU-Platinum Chemotherapy 
for First-Line Treatment of Recurrent/Metastatic Head and Neck Squamous Cell 
Carcinoma 
Protocol Number: 209227 
Compound Number 
or Name: 
GSK3359609  
Study Phase: Phase II/III 
Short Title: A Phase II/ III study of GSK3359609 in combination with pembrolizumab 
and 5FU-platinum chemotherapy compared with placebo in combination with 
pembrolizumab plus 5FU-platinum chemotherapy in participants with recurrent or 
metastatic HNSCC 
Acronym: INDUCE-4 
Sponsor Name and Legal Registered Address:  
GlaxoSmithKline Research & Development Limited 
980 Great West Road 
Brentford 
Middlesex, TW8 9GS 
UK 
Medical Monitor Name and Contact Information: refer to the Study Reference 
Manual 
Regulatory Agency Identifying Number(s): 
IND: 143221 
EudraCT:  2019-003981-42 
Approval Date: 30-JUN-2021 
 
 
Copyright 2021 the GlaxoSmithKline group of companies.  All rights reserved.  
Unauthorized copying or use of this information is prohibited. 

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SPONSOR SIGNATORY: 
Protocol Title: A Randomized, Double-Blind, Adaptive, Phase II/III Study of 
GSK3359609 in Combination with Pembrolizumab and 5FU-Platinum Chemotherapy 
versus Placebo in Combination with Pembrolizumab plus 5FU-Platinum Chemotherapy 
for First-Line Treatment of Recurrent/Metastatic Head and Neck Squamous Cell 
Carcinoma 
Protocol Number: 209227 
Compound Number 
or Name: 
GSK3359609  
 
 
 
 
 
 
 
 
Sumita Roy-Ghanta, MD, 
Clinical Development Lead, 
Oncology Research & Development 
GlaxoSmithKline 
 
Date 
 
 
 
The signed page is a separate document 
 
 
 
Medical Monitor Name and Contact Information  
May be found in the Study Reference Manual 

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PROTOCOL AMENDMENT SUMMARY OF CHANGES TABLE 
DOCUMENT HISTORY 
List dates of original protocol and all amendments in reverse chronological order. 
Document 
Date 
DNG Number 
Amendment 2 
30-JUN-2021 
TMF-13842020 
Amendment 1 
13-Apr-2020 
2019N416505_01 
Original Protocol 
7-Jan-2020 
2019N416505_00 
 
Amendment 2: 30-JUN-2021 
Overall Rationale for the Amendment: A Dear Investigator Letter (DIL) dated 13-
April-2021 was issued requiring the stopping of further screening and the discontinuation 
of the administration of GSK3359609 (feladilimab) or placebo for all participants on 
INDUCE-4, effective immediately. Further to the DIL, since all participants have the 
option to remain on pembrolizumab alone plus 5FU-platinum as study therapy, GSK 
issued a Protocol Clarification Letter (PCL) dated 28-April-2021 to reduce any 
unnecessary burden of on treatment and follow up assessments (the PCL did not alter any 
screening assessments). This protocol amendment is a follow up to the PCL, with a 
primary intent to only update the SoA; other impacted, relevant sections were also 
updated accordingly. Additionally, updates were made to management guidelines to align 
with pembrolizumab IB update.  
Section # and 
Name 
Description of Change 
Brief Rationale 
1.3 Schedule of 
Activities 
(SoA) 
Assessments related to 
GSK3359609 (feladilimab) 
were removed. These include 
feladilimab/placebo 
infusions; feladilimab PK 
collections, immunogenicity, 
IRR lab panel, plasma 
collections, PBMC 
collections, optional biopsy, 
Patient Reported Outcomes 
(PROs), Healthcare Resource 
Utilization (HCRU), prior 
protocol required disease 
assessments, follow-up 
subsequent anticancer therapy 
and disease assessments, and 
pembrolizumab second 
course. Minor clarifications 
to pembrolizumab dosing and 
window extension to PE, PS, 
and vital signs were also 
added. 
Since there will be no further 
screening into the study and no 
further dosing of GSK3359609 or 
placebo, there is no need to collect 
samples, PROs or efficacy 
assessments to determine the effect 
of GSK3359609 

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Section # and 
Name 
Description of Change 
Brief Rationale 
6 Study 
Intervention 
Added reference to Schedule 
of Assessments. 
To align with updated SoA.  
6.1.1 Duration 
of Second 
Course 
Removed section. 
Second Course will not be 
administered as subsequent 
anticancer therapy will not be 
followed and PFS2 will not be 
analysed as the study is terminated 
with no further screening. 
6.6.1 General 
Guidelines for 
Immune-
Related 
Adverse Events 
Added neurological toxicities 
and exfoliative 
dermatological conditions as 
immune-related AEs and 
updated myocarditis 
information. 
To align with pembrolizumab IB 
update (Edition 20 March 2021). 
7.1 
Discontinuation 
of Study 
Intervention 
Removed wording referring 
to second course. Added 
timeframe for completion of 
survival follow up. 
Second Course will not be 
administered as subsequent 
anticancer therapy will not be 
followed and PFS2 will not be 
analysed as the study is terminated 
with no further screening. A 
timeframe for completion of 
survival follow up is added as study 
is terminated. 
8.1 Efficacy 
Assessments 
Removed requirement for 
confirmatory scan per 
iRECIST. 
iRECIST may be followed at 
investigator discretion once 
progression is determined by 
RECIST 1.1 up to a maximum of 35 
cycles. 
8.1.1 Disease 
Assessments 
Removed wording referring 
to second course. 
Second Course will not be 
administered as subsequent 
anticancer therapy will not be 
followed and PFS2 will not be 
analysed as the study is terminated 
with no further screening. 
9.4 Statistical 
Analyses 
Added that primary and 
secondary endpoints would 
be included in main CSR. A 
separate final CSR will report 
updated key safety analyses 
at end of study. 
Clarifies reporting as the study is 
terminated with no further 
screening,  
10.3.5 
Reporting of 
SAE to GSK 
Removed requirement for 
investigator to show evidence 
of SAE causality in the eCRF 
within 72 hours.  
Change to GSK standard procedure. 
 

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TABLE OF CONTENTS 
PAGE 
PROTOCOL AMENDMENT SUMMARY OF CHANGES TABLE ..................................... 3 
1. 
PROTOCOL SUMMARY .......................................................................................... 9 
1.1. 
Synopsis ....................................................................................................... 9 
1.2. 
Schema ...................................................................................................... 14 
1.3. 
Schedule of Activities (SoA) ........................................................................ 15 
2. 
INTRODUCTION .................................................................................................... 23 
2.1. 
Study Rationale .......................................................................................... 23 
2.2. 
Background ................................................................................................ 25 
2.2.1. 
Inducible T Cell Costimulatory Receptor and GSK3359609 ......... 25 
2.2.1.1. 
GSK3359609 Clinical Experience ............................... 26 
2.2.2. 
Pembrolizumab ............................................................................ 27 
2.2.2.1. 
Pharmaceutical and Therapeutic Background ............ 27 
2.2.2.2. 
Non-clinical and Clinical Studies ................................. 28 
2.2.3. 
GSK3359609 Monotherapy and in Combination with 
Pembrolizumab in HNSCC .......................................................... 28 
2.3. 
Benefit/Risk Assessment ............................................................................ 29 
2.3.1. 
Risk Assessment ......................................................................... 29 
2.3.2. 
Benefit Assessment ..................................................................... 33 
2.3.3. 
Overall Benefit: Risk Conclusion .................................................. 33 
3. 
OBJECTIVES AND ENDPOINTS1 .......................................................................... 34 
4. 
STUDY DESIGN .................................................................................................... 36 
4.1. 
Overall Design ............................................................................................ 36 
4.2. 
Scientific Rationale for Study Design .......................................................... 37 
4.3. 
Justification for Dose .................................................................................. 38 
4.3.1. 
GSK3359609 Dose Justification .................................................. 38 
4.3.2. 
Pembrolizumab Dose Justification ............................................... 39 
4.3.3. 
Chemotherapy Dose Justification ................................................ 40 
4.4. 
End of Study Definition ............................................................................... 40 
5. 
STUDY POPULATION ........................................................................................... 41 
5.1. 
Inclusion Criteria ......................................................................................... 41 
5.2. 
Exclusion Criteria ........................................................................................ 43 
5.3. 
Lifestyle Considerations .............................................................................. 46 
5.4. 
Screen Failures........................................................................................... 46 
6. 
STUDY INTERVENTION ........................................................................................ 47 
6.1. 
Study Intervention(s) Administered ............................................................. 47 
6.2. 
Preparation/Handling/Storage/Accountability .............................................. 49 
6.3. 
Measures to Minimize Bias: Randomization and Blinding ........................... 50 
6.4. 
Study Intervention Compliance ................................................................... 51 
6.5. 
Concomitant Therapy.................................................................................. 51 
6.5.1. 
Permitted Medications and Non-drug Therapies .......................... 51 
6.5.2. 
Prohibited Medications and Non-drug Therapies ......................... 52 
6.5.2.1. 
Anti-cancer Therapy After Study Intervention 
Discontinuation ........................................................... 52 
6.6. 
Dose Modification ....................................................................................... 52 

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6.6.1. 
General Guidelines for Immune-Related Adverse Events ............ 53 
6.6.2. 
Dose Modification and Toxicity Management of Infusion-
Reactions Related to Immunotherapy Treatment ......................... 57 
6.6.3. 
Management of Chemotherapy-related Toxicities ........................ 59 
6.7. 
Intervention after the End of the Study ........................................................ 59 
7. 
DISCONTINUATION OF STUDY INTERVENTION AND PARTICIPANT 
DISCONTINUATION/WITHDRAWAL ..................................................................... 60 
7.1. 
Discontinuation of Study Intervention .......................................................... 60 
7.1.1. 
Liver Chemistry Stopping Criteria ................................................ 61 
7.1.2. 
Rechallenge ................................................................................. 62 
7.1.2.1. 
Study Intervention Restart or Rechallenge after 
liver stopping criteria met ............................................ 62 
7.2. 
Participant Discontinuation/Withdrawal from the Study ............................... 62 
7.3. 
Lost to Follow Up ........................................................................................ 62 
8. 
STUDY ASSESSMENTS AND PROCEDURES ..................................................... 63 
8.1. 
Efficacy Assessments ................................................................................. 65 
8.1.1. 
Disease Assessments.................................................................. 66 
8.2. 
Safety Assessments ................................................................................... 67 
8.2.1. 
Physical Examinations ................................................................. 67 
8.2.2. 
Performance Status ..................................................................... 68 
8.2.3. 
Vital Signs .................................................................................... 68 
8.2.4. 
Electrocardiograms ...................................................................... 68 
8.2.5. 
Echocardiograms ......................................................................... 68 
8.2.6. 
Clinical Safety Laboratory Assessments ...................................... 68 
8.3. 
Adverse Events and Serious Adverse Events ............................................. 69 
8.3.1. 
Time Period and Frequency for Collecting AE and SAE 
Information ................................................................................... 69 
8.3.2. 
Method of Detecting AEs and SAEs ............................................. 70 
8.3.3. 
Follow-up of AEs and SAEs ......................................................... 70 
8.3.4. 
Regulatory Reporting Requirements for SAEs ............................. 70 
8.3.5. 
Pregnancy ................................................................................... 71 
8.3.6. 
Cardiovascular and Death Events ................................................ 71 
8.3.7. 
Events of Clinical Interest ............................................................ 71 
8.4. 
Treatment of Overdose ............................................................................... 72 
8.4.1. 
GSK3359609 ............................................................................... 72 
8.4.2. 
Pembrolizumab ............................................................................ 72 
8.4.3. 
Chemotherapy ............................................................................. 72 
8.5. 
Pharmacokinetics ....................................................................................... 73 
8.6. 
Pharmacodynamics .................................................................................... 73 
8.7. 
Genetics ..................................................................................................... 73 
8.8. 
Biomarkers ................................................................................................. 73 
8.8.1. 
RNA Research ............................................................................. 74 
8.8.2. 
DNA Research ............................................................................. 75 
8.8.3. 
Tumor Tissue ............................................................................... 75 
8.8.4. 
Blood Samples ............................................................................ 75 
8.9. 
Immunogenicity Assessments ..................................................................... 76 
8.10. 
Medical Resource Utilization and Health Economics .................................. 76 
8.11. 
Patient Reported Outcomes ........................................................................ 76 
8.11.1. 
EORTC Item Library 50 and 51: Select Domains from the 
EORTC QLQ-C30 and EORTC QLQ-HN35 ................................. 77 
8.11.2. 
Brief Pain Inventory Short-Form- Item 3 (BPI-SF I3) .................... 77 

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8.11.3. 
The Patient-Reported Outcomes Measurement 
Information System- Short Form Physical Function- 8 item 
(PROMIS SF PF 8c) .................................................................... 77 
8.11.4. 
Patient Global Impression Items (PGIS and PGIC) ...................... 77 
8.11.5. 
Euroqol Questionnaire (EQ-5D-3L) .............................................. 77 
8.11.6. 
Functional Assessment of Cancer Therapy – General 
Population (FACT-GP5) ............................................................... 78 
9. 
STATISTICAL CONSIDERATIONS ........................................................................ 78 
9.1. 
Statistical Hypotheses................................................................................. 78 
9.1.1. 
Primary Hypotheses .................................................................... 78 
9.1.2. 
Key Secondary Hypotheses ......................................................... 79 
9.2. 
Sample Size Determination ........................................................................ 80 
9.2.1. 
Phase III Study with No Pause of Enrollment ............................... 81 
9.2.2. 
Phase II/III Study with Pause in Enrollment .................................. 83 
9.3. 
Populations for Analyses ............................................................................ 85 
9.4. 
Statistical Analyses ..................................................................................... 85 
9.4.1. 
Primary and secondary endpoints will be included in the 
main CSR.  A separate final CSR will report updated key 
safety analyses at the end of study. Further details will be 
outlined in the statistical analysis plan.Efficacy Analyses ............. 85 
9.4.1.1. 
Primary Analyses ....................................................... 86 
9.4.1.2. 
Secondary Analyses ................................................... 88 
9.4.1.3. 
Exploratory Analyses .................................................. 89 
9.4.1.3.1. 
Progression-Free Survival per 
iRECIST (iPFS) ...................................... 89 
9.4.1.3.2. 
Other Exploratory Analyses .................... 90 
9.4.2. 
Safety Analyses ........................................................................... 90 
9.4.3. 
Patient Reported Outcomes ......................................................... 91 
9.5. 
Interim Analyses ......................................................................................... 92 
9.6. 
Independent Data Monitoring Committee (IDMC) ....................................... 95 
9.7. 
Blinded Independent Central Review Auditing ............................................ 95 
9.8. 
Multiplicity ................................................................................................... 96 
10. SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS ............................................................................................... 99 
10.1. 
Appendix 1: Regulatory, Ethical, and Study Oversight 
Considerations ............................................................................................ 99 
10.1.1. 
Regulatory and Ethical Considerations ........................................ 99 
10.1.2. 
Informed Consent Process .......................................................... 99 
10.1.3. 
Data Protection .......................................................................... 100 
10.1.4. 
Dissemination of Clinical Study Data ......................................... 100 
10.1.5. 
Data Quality Assurance ............................................................. 101 
10.1.6. 
Source Documents .................................................................... 102 
10.1.7. 
Study and Site Closure .............................................................. 102 
10.2. 
Appendix 2: Clinical Laboratory Tests ....................................................... 103 
10.3. 
Appendix 3: Adverse Events: Definitions and Procedures for 
Recording, Evaluating, Follow-up, and Reporting ..................................... 105 
10.3.1. 
Definition of AE .......................................................................... 105 
10.3.2. 
Definition of SAE ........................................................................ 106 
10.3.3. 
Definition of Cardiovascular Events ........................................... 107 
10.3.4. 
Recording and Follow-Up of AE and SAE .................................. 108 
10.3.5. 
Reporting of SAE to GSK ........................................................... 109 

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10.4. 
Appendix 4: Contraceptive Guidance and Collection of Pregnancy 
Information ................................................................................................ 111 
10.4.1. 
Definitions: ................................................................................. 111 
10.4.2. 
Contraception Guidance: ........................................................... 112 
10.4.3. 
Collection of Pregnancy Information: ......................................... 113 
10.5. 
Appendix 5: ECOG Performance Status ................................................... 115 
10.6. 
Appendix 6: Renal Function Measures ..................................................... 116 
10.7. 
Appendix 7: Genetics ................................................................................ 118 
10.8. 
Appendix 8: Liver Safety: Required Actions, Follow-up Assessments 
and Study Intervention Rechallenge Guidelines ........................................ 119 
10.8.1. 
Study Intervention Rechallenge Guidelines ................................ 122 
10.8.1.1. Rechallenge Following Liver Stopping Events 
that are Possibly Related to Study Treatment ........... 122 
10.8.1.2. Restart Following Transient Resolving Liver 
Stopping Events NOT Related to Study 
Treatment ................................................................. 123 
10.9. 
Appendix 9: Country Specific Amendments .............................................. 125 
10.10. Appendix 10: Abbreviations and Trademarks ............................................ 126 
10.11. Appendix 11: Immune-related Diseases ................................................... 129 
10.12. Appendix 12: Protocol Amendment History ............................................... 131 
11. REFERENCES ..................................................................................................... 134 
 

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1. 
PROTOCOL SUMMARY 
1.1. 
Synopsis 
Protocol Title: A Randomized, Double-Blind, Adaptive, Phase II/III Study of 
GSK3359609 in Combination with Pembrolizumab and 5FU-Platinum Chemotherapy 
versus Placebo in combination with Pembrolizumab plus 5FU-Platinum Chemotherapy 
for First-Line Treatment of Recurrent/Metastatic Head and Neck Squamous Cell 
Carcinoma 
Short Title: A Phase II/III study of GSK3359609 in combination with pembrolizumab 
and 5FU-platinum chemotherapy compared with placebo in combination with 
pembrolizumab plus 5FU-platinum chemotherapy in participants with recurrent or 
metastatic HNSCC 
Rationale: 
KEYNOTE-048 (KN-048; NCT02358031) is a randomized, three arm study in patients 
with recurrent or metastatic (R/M) HNSCC who had not received prior systemic therapy 
in the R/M setting. In the standard first-line treatment arm patients received 
chemotherapy (platinum and fluorouracil) in combination with cetuximab based on the 
EXTREME protocol [Vermorken, 2008]. In the two experimental arms patients either 
receive pembrolizumab in combination with platinum plus fluorouracil (5FU) or alone. 
Pembrolizumab was given at a dose of 200 mg every 3 weeks (Q3W), for up to 35 cycles. 
Pembrolizumab alone and in combination with chemotherapy compared with the 
EXTREME regimen as first-line treatment significantly improved the overall survival 
(OS) of patients with R/M HNSCC. The degree of  survival improvement for 
pembrolizumab alone or in combination with 5FU/platinum chemotherapy depended on 
the programmed cell death receptor 1-ligand 1 (PD-L1) combined positive score (CPS) 
status [Burtness, 2018; Rischin, 2019]. OS improvement in the total PD-L1 population 
required pembrolizumab in combination with 5FU-platinum regimen to reach statistical 
significance [Hazard Ratio (HR): 0.77; 95% Confidence Interval (CI): 0.63, 0.93; 
p-value: 0.0034]; in the PD-L1 CPS 1 population, pembrolizumab in combination with 
chemotherapy resulted in a 35% improvement in the risk of death [HR: 0.65; 95% CI: 
0.53, 0.80; p-value: <0.0001]. The results from KN-048 supported the Food and Drug 
Administration (FDA) approval of pembrolizumab alone and in combination with 
5FU- platinum chemotherapy as first-line treatment of patients with R/M HNSCC in the 
PD-L1 CPS 1 and total populations, respectively [KEYTRUDA, 2019]. In the European 
Union (EU), the European Commission approved pembrolizumab alone and in 
combination with 5FU-platinum chemotherapy in the PD-L1 positive (CPS 1) 
population [KEYTRUDA, 2019]. 
Despite the treatment advancements pembrolizumab has afforded patients with R/M 
HNSCC, there remains an unmet need due to the limited population benefit with the aim 
to further improve disease control, a feature that if not addressed adversely impacts 
patient quality of life in the disease setting, and to further improve survival across all 
HNSCC populations. 

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The non-clinical data demonstrate that the activity of targeting ICOS with an agonist 
antibody is further enhanced with PD-1 blockade and that the mechanisms of action for 
each antibody are complementary with one another as evidenced by the non-clinical 
findings that treatment with a mouse anti-PD-1 antibody resulted in upregulation of 
ICOS+ cluster of differentiation (CD)4+ and CD8+ T cells in tumors and lymph nodes; 
conversely, treatment with anti-mouse ICOS antibodies increased PD-L1 levels in the 
tumor. Furthermore, when combined, the two agents resulted in a greater survival effect 
than either agent alone in syngeneic mouse tumor models (refer to Section 2.2.1). The 
preliminary clinical data from INDUCE-1 demonstrate that the combination of 
GSK3359609 with pembrolizumab exhibits promising antitumor activity in participants 
with HNSCC (refer to Section 2.2.3). 
Combining immunomodulatory agents targeting different components of the cancer 
immunity cycle [Chen, 2013] may be able to overcome the multiple mechanisms of 
immune suppression which prohibit an effective antitumor immune response. Thus, 
targeting both the ICOS and PD-1 axes may translate into enhanced clinical activity and 
expand the population that benefits with the combination of GSK3359609 (ICOS agonist 
antibody) and pembrolizumab (PD-1 blocking antibody) which is supported by the 
available non-clinical and clinical evidence. The clinical data from INDUCE-1 has 
validated the non-clinical findings whereby the 24% overall response rate (ORR) 
observed with the combination of GSK3359609 and pembrolizumab was higher than that 
observed with GSK3359609 monotherapy as described in Section 2.2.1.1 and higher than 
that reported for pembrolizumab alone as first-line therapy [Burtness, 2018] or 
subsequent-line therapy [Cohen, 2019] in R/M HNSCC. The purpose of Study 209227 is 
to evaluate if the addition of GSK3359609 to pembrolizumab in combination with 
platinum-based chemotherapy improves the efficacy of the pembrolizumab combination 
with platinum-based chemotherapy in patients with R/M HNSCC. 
Objectives and Endpoints: 
Primary 
Objectives 
Endpoints 
• 
Compare the efficacy of GSK3359609 in 
combination with pembrolizumab + 
5FU-platinum chemotherapy versus placebo 
in combination with pembrolizumab + 
5FU-platinum chemotherapy in the total 
population (PD-L1 CPS all) and in the PD-L1 
positive (CPS1) population 
• 
OS in the total and the PD-L1 CPS1 
populations, defined as the time from the date 
of randomization until the date of death due to 
any cause 
• 
PFS per RECIST v1.1 by Investigator 
assessment in the total population; defined as 
the time from the date of randomization to the 
date of first documented disease progression 
or death due to any cause, whichever comes 
first 

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Secondary 
Objectives 
Endpoints 
• 
Further compare the efficacy of GSK3359609 
in combination with pembrolizumab + 
5FU-platinum chemotherapy versus placebo 
in combination with pembrolizumab + 
5FU-platinum chemotherapy 
• 
PFS per RECIST v1.1 by Investigator 
assessment in the PD-L1 CPS1 population 
• 
Milestone OS rate at 12, 24 and 36 months in 
the total and the PD-L1 CPS 1 populations 
• 
ORR per RECIST v1.1 by Investigator 
assessment in the total and the PD-L1 CPS 1 
populations 
• 
DCR per RECIST v1.1 by Investigator 
assessment in the total and the PD-L1 CPS 1 
populations 
• 
DoR per RECIST v1.1 by Investigator 
assessment in the total and PD-L1 CPS 1 
populations 
• 
Evaluate the safety and tolerability of 
GSK3359609 in combination with 
pembrolizumab + 5FU-platinum 
chemotherapy compared with placebo in 
combination with pembrolizumab + 
5FU-platinum chemotherapy 
• 
Frequency and severity of AEs, AESI, SAEs 
in the total and the PD-L1 CPS 1 populations 
• 
Dose modifications (i.e., interruptions, 
discontinuations) in the total and the PD-L1 
CPS 1 populations 
• 
Compare disease and treatment related 
symptoms and impact on function and 
HRQoL of GSK3359609 in combination with 
pembrolizumab + 5FU-platinum 
chemotherapy versus placebo in combination 
with pembrolizumab + 5FU-platinum 
chemotherapy 
• 
The time to deterioration in Pain measured by 
the EORTC QLQ-H&N35 pain domain in the 
total and the PD-L1 CPS 1 populations 
• 
The time to deterioration in Physical Function 
as measured by the PROMIS PF 8c in the total 
and the PD-L1 CPS 1 populations 
Abbreviations:  AE=adverse events; AESI=adverse events of special interest; CPS = combine positive 
score; DCR=disease control rate; DoR=duration of response; EORTC QLQ-H&N35= European 
Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Head and Neck 35 
Item Module; HRQoL=health-related quality of life; ORR=overall response rate; Overall 
survival=overall survival; PD-L1= Programmed Death Receptor Ligand-1; PFS=progression-free 
survival; PROMIS PF 8c=Patient-Reported Outcomes Measurement Information System-Physical 
Function-Short Form; RECIST v1.1= Response Evaluation Criteria in Solid Tumors version 1.1; 
SAE=serious adverse event 
Overall Design: 
This is a randomized, double-blinded, Phase II/III study comparing the combination of 
GSK3359609 with pembrolizumab and 5FU-platinum chemotherapy to placebo in 
combination with pembrolizumab and 5FU-platinum chemotherapy in participants with 
recurrent or metastatic HNSCC of the oral cavity, oropharynx, hypopharynx or larynx. 
The study will evaluate the efficacy, safety, and patient reported outcomes of 
GSK3359609 in combination with pembrolizumab and 5FU-platinum chemotherapy 
(Arm 1) compared with placebo in combination with pembrolizumab and 5FU-platinum 
chemotherapy (Arm 2) as a standard first-line regimen in HNSCC. Study participants will 
be stratified by PD-L1 CPS status (CPS20 versus 1≤ CPS<20 versus CPS <1) and HPV 
status for oropharyngeal cancers (positive vs. negative/unknown) vs non-oropharyngeal 
cancers then randomly assigned to one of the two study treatment arms in a 1:1 ratio. 

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The Phase II/III study design is deemed an efficient approach to consider the potential of 
expanding Study 209227 to a Phase III design based on pre-specified, external adaptive 
decision rules from Study 209229 (INDUCE-3) [GlaxoSmithKline Document Number 
2019N403389_03] that are based on ORR/DCR per RECIST v1.1 guidelines in 
approximately 100 participants (PD-L1 CPS ≥1 population) with a minimum follow-up 
of 6 months. If the adaptive analysis results from Study 209229 meets the defined 
adaptive decision criterion to expand Study 209229 to a Phase III study (ORR 8%), 
then Study 209227 will expand to a Phase III design with 640 participants randomized. If 
the outcome does not meet the aforementioned defined criteria but meets the criteria for 
Study 209229 to remain as a Phase II study (0% ∆ORR<8% ), then Study 209227 will 
be conducted as a Phase II/III seamless design with the second adaptive decision for 
Study 209227 to be based on the outcome of the first OS analysis within Study 209227. 
This analysis for OS will occur after 9 months of OS follow-up in the first 300 
participants. 
All participants randomized are included for inference at the end of Phase III 
(approximately 640 participants). In addition, all primary endpoints and key secondary 
endpoints are formally tested for statistical significance at the end of Phase II/III or Phase 
III. 
Disclosure Statement: This is a parallel group treatment study with 2 arms that is 
sponsor, participant and investigator blinded. Crossover between study treatment arms is 
not permitted. 
Number of Participants: 
Overall, if the study expands to a Phase III design, approximately 640 participants with 
R/M HNSCC will be randomly assigned in a 1:1 ratio either to GSK3359609 in 
combination with pembrolizumab and 5FU-platinum chemotherapy (Arm 1) or placebo 
in combination with pembrolizumab and 5FU-platinum chemotherapy (Arm 2). Based on 
the prevalence of PD-L1 CPS status reported in KN-048 [Burtness, 2018], in a target 
sample size of 640 R/M HNSCC participants, the study will enroll approximately 544 
participants with PD-L1 CPS 1 (PD-L1 positive expression) of which 275 participants 
have PD-L1 CPS 20 (PD-L1 high expression), and 96 participants with PD-L1 CPS <1 
(PD-L1 negative). Strata may be collapsed in the case where a very small stratum size is 
observed; details will be documented in Statistical Analysis Plan. 
The overall proportion of participants by PD-L1 CPS status will be capped such that the 
maximum proportion of participants in PD-L1 CPS 20, 1 CPS <20 or CPS <1 will not 
exceed the expected proportion by 5% for any subgroup. Refer to Section 9.2 for the 
expected sample size of each subgroup. 
Intervention Groups and Duration: 
The study is comprised of three periods: screening, treatment, and follow-up. The total 
duration of study participation begins with the signing of the informed consent form 
(ICF). After a screening period of up to 45 days, eligible participants will be randomly 
assigned to 1 of the 2 treatment arms. 
For participants who meet all eligibility criteria and are randomized within the study, the 
maximum duration of treatment with pembrolizumab, GSK3359609 and placebo is 

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expected to be approximately 2 years, up to 35 cycles. The duration of chemotherapy 
treatment will be 6 cycles (cycle=21 days). If the course of chemotherapy treatment is 
completed after six cycles or discontinued prior to completion of 6 cycles, GSK3359609, 
placebo and pembrolizumab treatment may continue for the aforementioned duration 
indicated. 
The follow-up period begins when study treatment is permanently discontinued; 
participants will undergo follow-up assessments for safety, patient reported outcomes, 
PFS on first subsequent anti-cancer therapy (PFS2), subsequent anticancer therapy and 
survival as indicated in the Schedule of Activities (SoA); refer to Section 1.3. The total 
duration of study participation begins with the signing of the ICF through the final 
protocol-defined follow-up assessment for survival. 
Participants will be randomly assigned to one of the following combinations: 
• GSK3359609 24 mg + pembrolizumab 200 mg + 5FU 1000 mg/m2/24 hours for 
4 days + platinum chemotherapy (cisplatin 100 mg/m2 OR carboplatin area under 
the curve [AUC] 5) Q3W for 6 cycles (Arm 1) 
• Placebo + pembrolizumab 200 mg+ 5FU 1000 mg/m2/24 hours for 4 days + 
platinum chemotherapy (cisplatin 100 mg/m2 OR carboplatin AUC 5) Q3W for 
6 cycles (Arm 2) 
GSK3359609 and pembrolizumab are administered as 30-minute intravenous (IV) 
infusions. GSK3359609 will be administered first followed by pembrolizumab; 
5FU-platinum chemotherapy will be administered after pembrolizumab infusion is 
complete. The sequence in which chemotherapy doublets are administered is per standard 
practice. 
Independent Data Monitoring or Other Committee: 
The study will use an Independent Data Monitoring Committee (IDMC). The IDMC 
membership and governance will be outlined in a separate charter. 
The IDMC will make recommendations for discontinuation or modification of the study 
based on ongoing reviews of safety data according to the Charter. In addition, the IDMC 
will also evaluate adaptive decision analyses, the interim analyses of OS and make 
recommendations based on observed results of the study. 
In this double-blind study, all GSK and site personnel will be restricted from access to 
interim analysis results provided to the IDMC until the conclusion of the study, unless the 
IDMC recommends significant changes to study conduct that require a protocol 
amendment. In this scenario, after receiving the IDMC recommendation and a decision 
by Chief Medical Officer (CMO), a review of the data may be required. A select group 
from GSK, as determined by the CMO will be unblinded to review the data to agree on 
future study conduct. Depending on the recommendation of the IDMC, the Sponsor may 
prepare a regulatory submission. More details will be provided in the IDMC charter. 

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1.2. 
Schema 
 
Abbreviations: 5FU=fluorouracil; AUC=area under the curve; CPS=combined positive score; 
HPV=human papilloma virus; m2= meters squared; mg=milligram; PD-L1=programmed death ligand-1; 
Q3W=every three weeks; vs=versus 
1. Stratification Factors: 
• 
PD-L1 Status (CPS ≥20 vs. 1≤ CPS <20 vs CPS <1) 
• 
HPV status in oropharynx sites only (positive vs. negative/unknown) vs non-oropharynx 
2. Refer to Section 9.2 for details on adaptive decision analyses based on external (Study 209229) and 
internal (Study 209227) analyses 
 

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1.3. 
Schedule of Activities (SoA) 
Table 1 
Schedule of Activities 
Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Screening Only, Safety and Disease Assessments 
Informed Consent 
X 
 
 
 
 
 
 
 
 
 
 
 
ICF can be signed up to 45 
days before randomization. 
Inclusion and Exclusion 
Criteria 
X 
 
 
 
 
 
 
 
 
 
 
 
Review eligibility prior to 
randomization. 
Demography 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Disease History, Medical 
History (Past and Current 
Conditions; Includes Tobacco, 
Alcohol and Drug Substance 
Usage), Prior Anticancer 
Therapies; HPV status by p16 
IHC in oropharyngeal 
cancers* 
X 
 
 
 
 
 
 
 
 
 
 
 
*HPV status assessed by p16 
IHC testing using CINtec p16 
Histology assay. If local p16 
testing results are not 
available, or cannot be 
assessed by the specified 
method, a tumor tissue 
sample are to be submitted 
for p16 testing at the 
designated central laboratory. 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Physical Examination  
X 
X 
X 
X 
X 
X 
X 
X 
X 
Q3W 
X 
 
Full physical exam at 
Screening; brief physical 
exam thereafter Must be 
assessed within 3 days prior 
to dosing. 
Not required to be performed 
on Day 1 if Screening exam 
was performed within 72 
hours from time of the 
scheduled first dose. 
ECOG PS 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Q3W 
X 
 
Must be assessed within 3 
days prior to dosing. 
Serum Pregnancy Test 
(WOCBP only) 
X 
 
 
 
 
 
 
 
 
 
 
 
Required within 72 hours 
prior to randomization. 
Monthly urine/serum 
(preference) pregnancy 
testing may also be 
performed as consistent with 
local standards however if a 
urine test is positive or 
borderline, or in the event of 
a missed menstrual period or 
suspicion of pregnancy, a 
serum β-hCG test will be 
required. 
Hepatitis B and C  
X 
 
 
 
 
 
 
 
 
 
 
 
If test otherwise performed 
within 3 months prior to 
randomization, testing at 
screening is not required 
(refer to Table 15) 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Hematology, Coagulation, 
Clinical Chemistry, Urinalysis 
Laboratory Assessments 
(Refer to Table 15 ) 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Q3W 
X 
 
Required within 7 days of 
randomization day 
Not required to be tested on 
Day 1 if Screening labs are 
within 72 hours from time of 
scheduled first dose. 
Must be drawn within 3 days 
prior to dosing 
Thyroid Function Testing 
X 
 
 
X 
 
X 
 
X 
 
Q6W 
X 
 
Must be drawn within 3 days 
prior to dosing 
ECHO or MUGA/12-lead 
ECG/ Cardiac Troponin I or T 
X 
 
 
 
 
 
 
 
 
 
 
 
After Screening, perform as 
clinically indicated. QT 
interval/duration will be 
corrected using Fridericia’s 
formula  
Vital Signs 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Q3W 
X 
 
Must be assessed within 3 days 
prior to dosing. 
Height will be recorded at 
Screening only 
Refer to Protocol Section 
8.2.3. 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Tumor Tissue Collection for 
22C3 PharmDx PD-L1 Assay 
Testing by Central Laboratory 
X* 
 
 
 
 
 
 
 
 
 
 
 
*Assessment(s) can 
commence after signed ICF 
within 45 days prior to 
randomization. Refer to 
Section 8 for details on 
central lab testing. 
Refer to Section 5.1, 
inclusion 12. for tumor tissue 
requirements (i.e., whether 
archival tumor tissue is 
acceptable or fresh biopsy is 
required). Refer to Section 
8.8.3 for details on PD-L1 
testing.  
PD-L1 IHC by central lab 
testing; evaluable result 
required prior to 
randomization. Refer to 
Section 8 for details 
p16 IHC testing by central 
lab if local results not 
available (refer to Section 8; 
[oropharyngeal only]) 
*This tissue will be used for 
exploratory biomarkers 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
AE/AESI/SAE Review 
X 
=============================→ 
X 
X 
All AEs are to be graded 
according to NCI-CTCAE 
(Version 5.0) 
Refer to Section 8.3.1 for 
time period of collection 
Concomitant Medication 
Review 
X 
=============================→ 
X 
X* 
*Concomitant medications 
used to treat AEs/AESI/SAEs 
during the follow-up period 
are to be reported. 
Disease Assessments 
X 
 
 
 
X* 
 
X* 
 
 
 
 
 
*For participants who 
received at least 1 dose of 
GSK3359609 (feladilimab) or 
placebo scans should be 
completed at W9, W15 and 
then move to standard 
practice. For participants who 
received only pembrolizumab 
or who received 
GSK3359609 (feladilimab) 
and are past W15, scans 
should be completed 
according to standard 
practice. 
Study Treatment 
Randomization 
 
X 
 
 
 
 
 
 
 
 
 
 
Randomization may occur up 
to 3 days before Day 1; the 
preference is to randomize 
within 24 hours before Day 1. 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Pembrolizumab 
 
X 
X 
X 
X 
X 
X 
X 
X 
Q3W 
 
 
Day 1: study administration 
window is within 3 days of 
randomization 
 
Participants will receive 
study treatment up to the 
maximum duration of 35 
cycles unless one of the 
following events occurs 
earlier: 
•Disease progression 
•Death 
•Unacceptable toxicity (refer 
to Protocol Section 6.6 and 
subsections) 
•Pregnancy (refer to Protocol 
Section 8.3.5 for details) 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Administer 5 FU/Cisplatin or 
Carboplatin 
 
X 
X 
X 
X 
X 
X 
 
 
 
 
 
Fluorouracil (5FU) will be 
administered continuous on 
Day 1 through Day 4 of every 
3-week/21-day cycle 
Chemotherapy premedication 
indicated on day of dosing 
should be administered after 
GSK3359609/pembrolizumab 
infusion. Chemotherapy will 
be administered for a 
maximum of 6 cycles; if a 
cycle is delayed, 
chemotherapy may be given 
beyond Week 18 
Genetics Research  
Genetics Research Blood 
Sample 
 
X 
 
 
 
 
 
 
 
 
 
 
Optional, collected if genetics 
research optional consent 
signed; consent must be 
signed before sample is 
drawn  
Sample collected on Day 1 
predose.  
NOTE: sample may be 
collected beyond 
predose/Day 1 with signed 
consent 

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Procedure 
Screening  
(up to 28 Days 
Before 
Randomization) 
Treatment Period1, 4 
 
Follow-
up3 
(14 
Days) 
 
 
Notes 
 
TDV = Treatment 
Discontinuation Visit 
Day 1 
Weeks (3 Days) 
3 
6 
9 
12 
15 
18 
21 
>21 
TDV2. 
Fresh Tumor Biopsy* 
X* 
 
 
 
 
*Optional biopsy at: 
• 
 Screening in those 
participants who provide 
archival tumor tissue 
(refer to Section 5.1 for 
archival tissue 
requirements) 
Follow-up Assessments 
Survival 
 
 
 
 
 
 
 
 
 
 
 
Q12W 
Participants will be contacted 
via telephone contact every 
12 weeks until death or 
participant’s withdrawal from 
further contact or until the 
last patient discontinues 
treatment and has had their 
last follow up for safety.  
Abbreviations: AE = Adverse Events; AESI = Adverse Events of Special Interest;; ECG = electrocardiogram; ECHO = echocardiogram; ECOG PS= Eastern 
Cooperative Oncology Group Performance Status; EOI= end of infusion; HPV = human papilloma virus; ICF = Informed Consent Form; MUGA = Multigated 
Acquisition Scan; Q3W = every 3 weeks; Q6W = every 6 weeks; Q12W = every 12 weeks; Q24W = every 24 weeks; SAE = Serious Adverse Events; TDV = 
Treatment Discontinuation visit; WOCBP = woman of childbearing potential 
1. If administration of study treatment is delayed 7 days due to adverse events, assessments indicated to occur at the dosing visit can be scheduled to occur when 
dosing occurs. If administration of study treatment is delayed > 7 days due to adverse events, assessments indicated at the dosing visit are to be performed at the 
expected scheduled visit (window) with the exception of the following: PK sample collection; immunogenicity sample collection, and the PRO assessments. If the 
dosing Week visit that is delayed > 7 days occurs at a visit when disease assessments are required, then PRO assessments are required to be administered to the 
participant. 
2. Do not repeat tests that have already been performed within 3 days or scans within 6 weeks of the TDV. The assessments required at the study treatment 
discontinuation visit (permanent discontinuation) must be completed within 30 days from the date study treatment was discontinued and must occur prior to the start 
of subsequent anti-cancer therapy; the window for this visit is +10 days. 
3. The follow-up visits will commence after decision to permanently discontinue study treatment for any reason is made including completion of 35 cycles  
 

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2. 
INTRODUCTION 
Head and neck squamous cell carcinoma (HNSCC) is one of the most common 
malignancies worldwide, accounting for more than 550,000 new cases and 380,000 
deaths per year [Vos, 2017; Naghavi, 2017]. HNSCC is a heterogeneous disease, 
encompassing a variety of tumors that originate from different anatomic subsites in the 
head and neck region, and include carcinomas of the oral cavity, oropharynx, 
hypopharynx, nasopharynx, larynx, and nasal cavity/sinuses. 
The etiology of HNSCC is well-established as being multifactorial with risk factors that 
include tobacco smoking and alcohol consumption; human papilloma virus (HPV) 
infection is also an important factor in the pathophysiology and prognosis of HNSCC 
which includes playing an immunosuppressive role, mainly in the oropharyngeal region 
[Gillison, 2015; Ang, 2010; Fung, 2017]. Most patients are diagnosed with locally 
advanced disease and are usually treated with multimodal therapy including surgery, 
radiotherapy/chemotherapy and systemic therapy. 
Despite advances in surgical and radiation techniques, as well as the addition of 
chemotherapy and epidermal growth factor receptor-targeting monoclonal antibodies 
(mAbs) in the treatment of locally advanced HNSCC, more than half of patients 
eventually experience relapse or distant metastases. Most of these patients are no longer 
suitable for curative treatment approaches. For locally recurrent disease, local treatment 
options such as surgery and radiotherapy play an important role in this setting. For 
recurrent disease no longer amenable to local therapy or metastatic HNSCC, platinum-
based chemotherapy  cetuximab was the standard treatment option in the United States 
(US) before the US FDA approval of pembrolizumab in this setting. Even with current 
multi-agent chemotherapy that now includes pembrolizumab, the expected median 
survival for a patient in the incurable or metastatic relapse setting remains under 15 
months [KEYTRUDA, 2019]. 
2.1. 
Study Rationale 
KEYNOTE-048 (KN-048; NCT02358031) was a randomized, three arm study in patients 
with recurrent or metastatic (R/M) HNSCC who had not received prior systemic therapy 
in the R/M setting. In the standard first-line treatment arm patients received 
chemotherapy (platinum and fluorouracil) in combination with cetuximab based on the 
EXTREME protocol [Vermorken, 2008]. In the 2 experimental arms patients either 
receive pembrolizumab in combination with platinum plus fluorouracil (5FU) or 
pembrolizumab alone. Pembrolizumab was given at a dose of 200 mg every 3 weeks 
(Q3W), for up to 35 cycles. 
Pembrolizumab alone and in combination with chemotherapy compared with the 
EXTREME regimen as first-line treatment improved the overall survival (OS) of patients 
with R/M HNSCC. However, the degree of survival improvement for pembrolizumab 
alone or in combination with 5FU/platinum chemotherapy depended on the programmed 
cell death receptor 1-ligand 1 (PD-L1) combined positive score (CPS) status. OS 
improvement in the total PD-L1 CPS population required pembrolizumab in combination 
with the 5FU-platinum regimen [HR: 0.77; 95% CI: 0.63-0.93; p-value: 0.0034]; in the 

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PD-L1 CPS ≥1 population, pembrolizumab in combination with chemotherapy resulted 
in a 35% improvement in the risk of death [HR: 0.65; 95% CI: 0.53, 0.80; p-value: 
<0.0001]. Overall, the frequencies of all treatment-related toxicities categories were 
consistent between pembrolizumab in combination with 5FU-platinum and the 
EXTREME regimen [Burtness, 2018; Rischin, 2019]. 
The KN-048 results supported the Food and Drug Administration (FDA) approval of 
pembrolizumab alone and in combination with 5FU-platinum chemotherapy as first-line 
treatment of patients with R/M HNSCC in the PD-L1 CPS 1 and total populations, 
respectively [KEYTRUDA, 2019]. In the EU, the European Commission approved 
pembrolizumab alone and in combination with 5FU-platinum chemotherapy in the PD-L1 
positive (CPS 1) population [KEYTRUDA, 2019]. In addition, pembrolizumab alone 
and in combination with 5FU-platinum chemotherapy were incorporated into the 
National Comprehensive Cancer Network (NCCN) and the Society for Immunotherapy 
of Cancer guidelines as an option for the first-line treatment in patients with non-
nasopharyngeal HNSCC; the choice of which pembrolizumab-based regimen may 
consider PD-L1  expression status as well as other patient and disease characteristics 
[National Comprehensive Cancer Network (NCCN), 2020; Cohen, 2019]. 
However, there was a lack of significant improvement in PFS with pembrolizumab in 
combination with chemotherapy compared with the EXTREME regimen in the overall 
population and in the PD-L1 CPS populations analysed; although there was a 37% 
improvement in PFS in the PD-L1 CPS 20, statistical significance was not reached [HR: 
0.73; 95% CI: 0.55-0.97; p-value: >0.0017, as the superiority threshold][Rischin, 2019]. 
Despite the treatment advancements pembrolizumab has afforded patients with R/M 
HNSCC, there remains an unmet need due to the limited population of benefit that 
includes to further improve disease control, a feature that if not addressed, adversely 
impacts patient quality of life in this disease setting, and to further improve survival 
across all HNSCC populations. 
The non-clinical data demonstrate that the activity of targeting ICOS with an agonist 
antibody is further enhanced with PD-1 blockade. Further rationale for targeting the 
ICOS and PD-1 axes is supported by the non-clinical finding that treatment with a mouse 
anti-PD-1 antibody resulted in upregulation of ICOS+ cluster of differentiation (CD)4+ 
and CD8+ T cells in tumors and lymph nodes; conversely, treatment with anti-mouse 
ICOS antibodies increased PD-L1 levels in the tumor. Furthermore, when combined, the 
2 agents resulted in a greater survival effect than either agent alone in syngeneic mouse 
tumor models (refer to Section 2.2.1). The preliminary clinical data from INDUCE-1 
demonstrate that the combination of GSK3359609 with pembrolizumab exhibits 
promising antitumor activity in participants with HNSCC (refer to Section 2.2.3). 
Combining immunomodulatory agents targeting different components of the cancer 
immunity cycle [Chen, 2013] may be able to overcome the multiple mechanisms of 
immune suppression which prohibit an effective antitumor immune response and 
contribute to the progression of HNSCC [Ferris, 2015]. Rationale combination 
approaches with immune-targeted agents may include chemotherapies which offer rapid 
disease control and have been shown to possess advantageous immunological effects 
[Bracci, 2014; Galluzzi, 2015] that translated to improvement in overall survival, and in 

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certain disease settings progression-free survival with the combination of PD-1/L1 
therapies and standard of care chemotherapy regimens [Gandhi, 2018; Socinski, 2018; 
Burtness, 2018]. Additionally, targeting both the ICOS and PD-1 axes with chemotherapy 
may translate into enhanced clinical activity and expand the population that benefits with 
the combination of GSK3359609 (ICOS agonist antibody) and pembrolizumab (PD-1 
blocking antibody) which is supported by the available non-clinical and clinical evidence.  
The clinical data from INDUCE-1 has validated the non-clinical findings whereby the 
24% ORR observed with the combination of GSK3359609 and pembrolizumab was 
higher than GSK3359609 monotherapy as described in Section 2.2.3, and higher than that 
reported for pembrolizumab alone as first-line therapy [Burtness, 2018; Rischin, 2019] or 
subsequent-line therapy [Cohen 2019] in R/M HNSCC. In addition, the majority of 
patients who received GSK3359609 in combination with pembrolizumab and achieved a 
response or stable disease had PD-L1 CPS status <20. The purpose of Study 209227 is to 
evaluate if the addition of GSK3359609 to pembrolizumab in combination with 
5FU-platinum chemotherapy as first-line treatment improves the efficacy of 
pembrolizumab in combination with chemotherapy in participants with R/M HNSCC. 
2.2. 
Background 
2.2.1. 
Inducible T Cell Costimulatory Receptor and GSK3359609 
Inducible T cell co-stimulatory receptor (ICOS) is a co-stimulatory receptor belonging to 
the CD28/B7immunoglobulin (Ig) super family with expression restricted to T cells 
[Hutloff, 1999]. ICOS differentiates from first generation immunomodulatory antibodies 
directed against Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA-4) and PD-1/PD-
L1 by targeting a different axis in the antitumor T cell response cascade and promoting 
activation. ICOS is weakly expressed on resting T cells yet is highly induced on CD4+ 
and CD8+ T cells upon T cell receptor (TCR) engagement with cognate antigen and 
activation. The effect of ICOS agonist activity is to promote activation of cytotoxic CD8+ 
and conventional CD4+ cells, augmenting the expansion, function and survival of these 
populations thereby resulting in an increased antitumor immune response that is durable 
[Fan, 2014; Paulos, 2010; Wakamatsu, 2013, Sharpe, 2002]. 
GSK3359609 is a humanized anti-ICOS mAb selected for its nanomolar (nM) binding to 
and agonist activity in ICOS-expressing CD4+ and CD8+ effector T cells. GSK3359609 
is specifically engineered as an IgG4 hinge-stabilized isotype, IgG4PE, to markedly 
decrease binding affinity of the Fc (Fragment crystallizable) region of the mAb to 
activating Fcγ receptors and C1q, and thereby diminish the cytotoxic potential of 
GSK3359609 that would result in depletion of ICOS-positive T cells through antibody-
dependent or complement-dependent cell mediated mechanisms, respectively. Moreover, 
the IgG4PE isotype retains functional binding to the Fc inhibitor receptor, FcRIIb, a 
feature described as critical for modulating antibody agonist activity [Li, 2011], which 
also may be essential for optimal ICOS agonist activity and its associated antitumor 
effects in humans. 
The T cell activating potential of GSK3359609 was evaluated in multiple in vitro assay 
formats as a single agent and in combination with other immune checkpoint inhibitors. 

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GSK3359609 in combination with pembrolizumab demonstrated a more robust pro-
inflammatory cytokine response, including increases in interferon gamma (IFN) 
secretion, than either single agent alone. In vivo experiments in different mouse models 
either using GSK3359609/pembrolizumab or anti-mouse ICOS in combination with PD-1 
surrogate antibodies demonstrated enhanced growth inhibition and increased survivability 
of mice compared to either agent alone. The upregulation of ICOS with the mouse anti-
PD-1 antibodies and the converse whereby ICOS mouse surrogate antibodies increased 
tumor PD-L1 expression in these in-vivo experiments further support evaluating this 
combination. Furthermore, analysis of The Cancer Genome Atlas gene expression data 
demonstrates that tumors with higher ICOS expression also tend to have higher PD-L1 
expression, with head and neck squamous cell carcinomas observed as having the highest 
ICOS expression suggesting that targeting both axes may result in greater anti-tumor 
immune response. 
Refer to the GSK3359609 IB for details on the non-clinical experiments and findings 
[GlaxoSmithKline Document Number 2017N319717_02]. 
2.2.1.1. 
GSK3359609 Clinical Experience 
INDUCE-1 (Study 204691; NCT02723955) is an ongoing, first in-human, dose 
escalation and expansion study of GSK3359609, alone and in combination with other 
agents including pembrolizumab, in participants with advanced solid tumors. Analysis 
from the dose escalation phases of GSK3359609 monotherapy (Part 1A, n=22) and 
GSK3359609 combination with pembrolizumab (Part 2A, n=36), and GSK3359609 
monotherapy pharmacokinetic (PK)/pharmacodynamic cohort (n=47) demonstrated 
GSK3359609 alone and in combination with pembrolizumab was well tolerated across 
the 0.001–3 mg/kg dose range. Maximum tolerated dose (MTD) was not reached in 
Part 1A and Part 2A; maximum administered dose of GSK3359609 as a monotherapy 
and in combination with pembrolizumab was 3 mg/kg. A range of GSK3359609 doses 
(≥0.1-1 mg/kg) demonstrated biological and clinical activity supporting the mechanism 
of action of a non-depleting ICOS agonist as a clinical target [Hansen, 2018; Maio, 
2019]. 
A summary safety analyses from a later clinical data cut-off date of 15 March 2019 that 
included all participants dosed with GSK3359609 monotherapy (n=194), which included 
participants dosed at GSK3359609 10 mg/kg (MAD), or GSK3359609 in combination 
with pembrolizumab (n= 260) showed that 39% (n=75) and 50% (n=130) of participants, 
respectively, experienced at least 1 treatment-related adverse events (TR-AE). In the 
overall Part 1 population, TR-AEs occurring in ≥5% of participants were fatigue (10%, 
n=20), asthenia (8%, n=16) and diarrhea (5%, n=9). Eight participants (4%) experienced 
at least 1 TR-Grade 3 AE; none of which were Grade 5 in severity. In the overall Part 2 
population, TR-AEs occurring in ≥5% of participants were diarrhea (7%, n=18), asthenia 
(7%, n=17), fatigue (7%, n=17), aspartate aminotransferase elevations (5%, n=14), 
pruritus (5%, n=14) and nausea (5%, n=12). Thirteen participants (5%) experienced at 
least 1 TR-Grade 3 AE, three of whom experienced at least 1 treatment-related Grade 5 
event. Refer to GSK3359609 IB for further details [GlaxoSmithKline Document Number 
2017N319717_02]. 

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The INDUCE-1 study has an ongoing investigation of GSK3359609 in combination with 
pembrolizumab plus 5FU/platinum chemotherapy in participants with R/M HNSCC as a 
safety run-in cohort. As of 11 October 2019, in this ongoing safety cohort, six 
participants have received at least 1 cycle of GSK3359609 80 mg in combination with 
pembrolizumab200 mg and 5FU 1000 mg/m2 per 24 hours plus platinum (cisplatin 
[100 mg/m2] OR carboplatin [AUC 5]) chemotherapy. Four of the six participants (67%) 
experienced at least 1 AE regardless of causality; mucositis (n=2, 33%) was the only AE 
that occurred in >1 participant. The majority of AEs were Grade 1 or Grade 2 in severity; 
Grade 3 events of diarrhea, neutrophil count decrease and tumor haemorrhage were each 
experienced in 1 participant (50%). Three of six participants (50%) experienced at least 1 
treatment-related AE which included mucositis (n=2, 33%), abdominal pain (n=1, 17%), 
colitis (n=1, 17%), diarrhea (n=1, 17%), hypomagnesemia (n=1, 17%), nausea (n=1, 
17%), neutrophil count decrease (n=1, 17%) and oral candidiasis (n=1, 17%). No AEs 
were considered dose limiting toxicities. Two participants experienced at least 1 AE that 
was considered serious (33%); 1 participant experienced 2 serious AEs of Grade 3 
diarrhea and Grade 2 colitis, both events were treatment related and resolved 8 days and 
6 days, respectively, after the onset date. A second patient experienced Grade 3 
oropharyngeal tumor bleed that was not treatment related and later resolved 12 days after 
the onset date. 
2.2.2. 
Pembrolizumab 
Pembrolizumab is a potent humanized IgG4 mAb with high specificity of binding to the 
PD-1 receptor, thus inhibiting its interaction with PD-L1 and PD-ligand 2 (PD-L2). Based 
on preclinical in vitro data, pembrolizumab has high affinity and potent receptor blocking 
activity for PD-1. Pembrolizumab has an acceptable preclinical safety profile and is in 
clinical development as an intravenous (IV) immunotherapy for advanced malignancies. 
Keytruda (pembrolizumab) is indicated for the treatment of patients across a number of 
indications, which includes first-line treatment of metastatic or unresectable recurrent 
HNSCC. Pembrolizumab and nivolumab, another PD-1 inhibitor, is also considered a 
second-line/subsequent-line standard of care for patients with R/M HNSCC. 
Refer to the pembrolizumab IB [Merck; 2021] and approved labeling for detailed 
background information on MK-3475. 
The most common reported AEs (20% of patients) with pembrolizumab single agent 
include fatigue, musculoskeletal pain, decreased appetite, pruritus, diarrhea, nausea, rash, 
pyrexia, cough, dyspnea, constipation, pain and abdominal pain [KEYTRUDA, 2019]. 
Serious and fatal AEs associated with treatment include immune-mediated adverse 
reactions, which consisted of pneumonitis, colitis, endocrinopathies (i.e., hypophysitis, 
thyroid disorders, and Type1 diabetes mellitus), hepatitis, nephritis, infusion reactions, 
and skin reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis. 
2.2.2.1. 
Pharmaceutical and Therapeutic Background 
The PD-1 receptor-ligand interaction is a major pathway hijacked by tumors to suppress 
immune control. The normal function of PD-1, expressed on the cell surface of activated 
T cells under healthy conditions, is to down-modulate unwanted or excessive immune 
responses, including autoimmune reactions. PD-1 (encoded by the gene Pdcd1) is an Ig 

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superfamily member related to CD28 and CTLA-4 that has been shown to negatively 
regulate antigen receptor signalling upon engagement of its ligands (PD L1 and/or PD-
L2) [Greenwald, 2005; Okazaki, 2001]. 
The structure of murine PD-1 has been resolved [Zhang, 2004]. PD-1 and its family 
members are type I transmembrane glycoproteins containing an Ig-variable–type (IgV 
type) domain responsible for ligand binding and a cytoplasmic tail responsible for the 
binding of signalling molecules. The cytoplasmic tail of PD-1 contains 2 tyrosine-based 
signalling motifs, an immunoreceptor tyrosine-based inhibition motif, and an 
immunoreceptor tyrosine-based switch motif. Following T-cell stimulation, PD-1 recruits 
the tyrosine phosphatases, SHP-1 and SHP-2, to the immunoreceptor tyrosine-based 
switch motif within its cytoplasmic tail, leading to the dephosphorylation of effector 
molecules such as CD3 zeta (CD3ζ), protein kinase C-theta (PKCθ), and zeta-chain-
associated protein kinase (ZAP70), which are involved in the CD3 T-cell signalling 
cascade [Okazaki, 2001; Chemnitz, 2004; Shepard, 2004; Riley, 2009]. The mechanism 
by which PD-1 down-modulates T cell responses is similar to, but distinct from, that of 
CTLA-4, because both molecules regulate an overlapping set of signalling proteins 
[Parry, 2005; Francisco, 2010]. As a consequence, the PD 1/PD-L1 pathway is an 
attractive target for therapeutic intervention. 
2.2.2.2. 
Non-clinical and Clinical Studies 
Therapeutic studies in mouse models have shown that administration of antibodies 
blocking PD-1/PD-L1 interaction enhances infiltration of tumor-specific CD8+ T cells 
and ultimately leads to tumor rejection, either as a monotherapy or in combination with 
other treatment modalities [Hirano, 2005; Blank, 2004; Weber, 2010; Strome, 2003; 
Spranger, 2014; Curran, 2010; Pilon-Thomas, 2010]. Anti-mouse PD-1 or anti-mouse 
PD-L1 antibodies have demonstrated antitumor responses in models of squamous cell 
carcinoma, pancreatic carcinoma, melanoma, acute myeloid leukemia and colorectal 
carcinoma [Strome, 2003; Curran, 2010; Pilon-Thomas, 2010; Nomi, 2007; Zhang, 
2004]. In such studies, tumor infiltration by CD8+ T cells and increased IFNγ, granzyme 
B and perforin expression were observed, indicating that the mechanism underlying the 
antitumor activity of PD-1 checkpoint inhibition involved local infiltration and activation 
of effector T cell function in vivo [Curran, 2010]. Experiments have confirmed the in vivo 
efficacy of anti-mouse PD-1 antibody as a monotherapy, as well as in combination with 
chemotherapy, in syngeneic mouse tumor models (for detail refer to pembrolizumab IB; 
Merck, 2021). 
2.2.3. 
GSK3359609 Monotherapy and in Combination with 
Pembrolizumab in HNSCC 
The ongoing INDUCE-1 expansion phase is investigating GSK3359609 as a 
monotherapy (Part 1B) and GSK3359609 in combination with pembrolizumab (Part 2B) 
in participants with HNSCC. At a clinical data cut-off date of 26 July 2019, 
17 participants with anti-PD-1/L1 treatment-experienced HNSCC received at least 1 dose 
of 1 mg/kg GSK3359609 in Part 1B cohort. In the treated population (n=17), the median 
age was 56 years (range: 41-73 years); 82% were male and 82% received ≥1 prior lines 
of systemic therapy in the advanced/metastatic setting. Sixteen of the 17 dosed 
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(ORR) in the evaluable population was 6% with 1 of the 16 participants achieving a 
partial response (PR). 
In the Part 2B cohort, 34 participants with anti-PD-1/L1 naïve HNSCC received at least 
one cycle of 0.3 mg/kg GSK3359609 in combination with 200 mg pembrolizumab. In the 
treated population (n=34), the median age was 62 years (range 37-77 years); 85% were 
male and 53% received ≥1 prior line of systemic therapy in the advanced/metastatic 
setting. All 34 dosed participants were considered evaluable for efficacy analyses. The 
ORR in the evaluable population (n=34) was 24% (95% CI: 10.7%, 41.2%) with 8 of the 
34 participants achieving a complete response (n=3) or PR (n=5); disease control rate 
(DCR) was 65% (n=22; 95% CI: 46.5, 80.3). In addition, the majority of patients that 
achieved a response or stable disease had PD-L1 CPS status <20 (10/14 patients with 
CPS1 and <20, and 1 patient with CPS <1).The median progression-free survival (PFS) 
was 5.6 months (95% CI: 2.4, 7.4) [Rischin, 2019]. 
2.3. 
Benefit/Risk Assessment 
Summaries of findings from both clinical and non-clinical studies conducted with 
GSK3359609 [GlaxoSmithKline Document Number 2017N319717_02] and 
pembrolizumab [Merck, pembrolizumab IB, 2021] can be found in the respective IBs. 
Section 2.3.1 outlines the risk assessment and mitigation strategy for GSK3359609 in 
combination with pembrolizumab FU-platinum chemotherapy. The nonclinical and 
clinical toxicity profiles of the cytotoxic chemotherapies are well characterized with 
extensive clinical experience for a range of oncological indications including 
combinations with immune checkpoint inhibitors, such as pembrolizumab, which have 
not identified overlapping toxicities across the two drug classes. 
2.3.1. 
Risk Assessment 
Of 260 participants treated with the combination of GSK3359609 (at various doses) and 
pembrolizumab in various tumor types across the dose escalation and expansion phases 
of the INDUCE-1 study, 94% experienced at least 1 adverse event regardless of causality; 
with 41% experiencing at least 1 Grade 3 event and 41% experiencing at least 1 serious 
event. The events reported with the highest frequency (10%) regardless of causality 
were anemia, fatigue, nausea, diarrhea, asthenia, pyrexia, deceased appetite, dyspnea, 
constipation, cough and vomiting; these most common all-cause AEs are consistent with 
the those reported for pembrolizumab alone [KEYTRUDA, 2019]. Regarding immune 
related events (irAEs) most have been low grade and were treated successfully; few high 
grade irAEs were considered significant or required hospitalization (i.e., hyperglycemia 
and pneumonitis). Refer to the GSK3359609 IB for further details [GlaxoSmithKline 
Document Number 2017N319717_02]. In the ongoing INDUCE-1 safety cohort of 
GSK3359609 in combination with pembrolizumab plus 5FU/platinum chemotherapy, 4 
of the six participants (67%) experienced at least 1 AE regardless of causality; mucositis 
(n=2, 33%) was the only AE that occurred in >1 participant (refer to Section 2.2.1.1.). 
Table 2 outlines the risk assessment and mitigation strategy for this protocol. 

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Table 2 
Risk Assessment and Mitigation Strategy 
Potential Risk of Clinical 
Significance 
Summary of Data/ 
Rationale for Risk 
Mitigation Strategy 
Immune-related AEs 
• Inflammatory AEs such 
as diarrhea/colitis, 
pneumonitis, nephritis, 
and hepatotoxicity are 
well established as 
treatment emergent 
AEs with immune-
modulating agents and 
are consistent with the 
immune stimulatory 
mechanism of action of 
these agents. 
Participants with the 
following medical history 
are ineligible for this study 
• Toxicity (≥Grade 3) 
related to prior 
immunotherapy leading 
to study treatment 
discontinuation 
• Active autoimmune 
disease (refer to 
Section 5.2 exclusion 
criterion 8) 
• Severe hypersensitivity 
to another mAb 
• Established 
management guidelines 
for irAEs/treatment 
related AEs (refer to 
Section 6.6) 
• Further details on the 
identification, 
evaluation, and 
management of 
toxicities with a 
potential immune 
etiology (refer to 
Section 6.6); refer to 
pembrolizumab 
prescribing information 
for further details 
Hypersensitivity reaction 
• Risk for infusion 
reactions and 
hypersensitivity is 
inherent to many mAbs 
[Brennan, 2010] 
• Participants with 
history of severe 
hypersensitivity to 
another mAb or to the 
chemotherapies under 
investigation including 
any ingredient used in 
the formulation are 
ineligible for this study  
• Details on management 
of infusion reactions 

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Potential Risk of Clinical 
Significance 
Summary of Data/ 
Rationale for Risk 
Mitigation Strategy 
are included in Section 
6.6.2. 
Severe cytokine release 
syndrome (sCRS) 
• ICOS is a 
costimulatory receptor 
that can stimulate 
proliferation and 
activation of T cells 
• GSK3359609 is an 
ICOS agonist that can 
co-stimulate T cell 
activation in the 
context of TCR signal 
• No CRS events have 
been reported in 
clinical programs 
investigating 
GSK3359609 (refer to 
GSK3359609 IB; 
GlaxoSmithKline 
Document Number 
2017N319717_02) 
• Management of CRS 
events is provided in 
the Section 6.6.2. 
Immune complex disease 
• Immune complex 
formation and 
deposition findings in 
non-clinical safety 
studies (refer to 
GSK3359609 IB; 
GlaxoSmithKline 
Document Number 
2017N319717_02) 
• Clinical laboratory 
safety assessments and 
immunogenicity testing 
is included in the study 
(refer to Table 1) 
5FU Risks 
Refer to local prescribing 
information for description 
of 5FU risks:  
Warning and Precautions 
include: do not use in low 
or absent DPD activity; 
Withhold 5FU in 
cardiotoxicity, 
hyperammonemic 
encephalopathy, neurologic 
toxicity, diarrhea, Palmar 
Plantar Erythrodysesthesia 
• These risks are 
described in detail in 
the Warning and 
Precautions section of 
5FU prescribing 
information.  Please 
refer to local 
prescribing information 
• Participants with the 
following screening 
labs are ineligible 
o ANC <1.5x109/L; 
hemoglobin <9 g/dL; 
Platelets <100x109/L 
• Participants with the 
following medical 
history are ineligible 
o Toxicity related to 
prior chemotherapy 
that has not resolved 
to Grade 1 (refer 
Section 5.2 to 

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Potential Risk of Clinical 
Significance 
Summary of Data/ 
Rationale for Risk 
Mitigation Strategy 
(hand foot syndrome), 
myelosuppression, 
mucositis, increased INR 
with warfarin, embryofetal 
toxicity 
exclusion criterion 
4) 
• Clinical laboratory 
safety assessments and 
SoA in Section 1.3. 
• And/or follow local 
labels, whichever is 
more conservative 
(refer to Section 6.6.3) 
Cisplatin Risks 
Warnings include: 
cumulative renal toxicity 
can be severe, ototoxicity, 
and anaphylactic-like 
reactions 
• These risks are 
described in detail in 
the Warning and 
Precautions section of 
cisplatin prescribing 
information.  Please 
refer to local 
prescribing information 
• Participants with the 
following screening 
labs are ineligible 
o ANC <1.5x109/L; 
hemoglobin <9 g/dL; 
Platelets <100x109/L 
• Participants with the 
following medical 
history are ineligible 
o Toxicity related to 
prior chemotherapy 
that has not resolved 
to Grade 1 (refer to 
Section 5.2 
exclusion criterion 
4) 
• Clinical laboratory 
safety assessments and 
SoA in Section 10.2 
and Section 1.3. 
• And/or follow local 
labels, whichever is 
more conservative 
(refer to Section 6.6.3) 
Carboplatin Risks 
Warnings include: 
myelosuppression, 
nephrotoxicity and 
ototoxicity in combination 
with aminoglycosides, 
vomiting, loss of vision, 
peripheral neuropathy, 
anaphylactic-like reaction 
• These risks are 
described in detail in 
the Warning and 
Precautions section of 
carboplatin prescribing 
information. 
• Participants with the 
following screening 
labs are ineligible 
o ANC <1.5x109/L; 
hemoglobin <9 g/dL; 
Platelets <100x109/L 
• Participants with the 
following medical 
history are ineligible 
o Toxicity related to 
prior chemotherapy 
that has not resolved 

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Potential Risk of Clinical 
Significance 
Summary of Data/ 
Rationale for Risk 
Mitigation Strategy 
to Grade 1 (refer to 
exclusion criterion 
4) 
• Clinical laboratory 
safety assessments and 
SoA in Section 10.2 
and Section 1.3. 
• And/or follow local 
labels, whichever is 
more conservative 
(refer to Section 6.6.3) 
Abbreviations: 5FU=fluorouracil; AE= adverse event; CRS=cytokine release syndrome; DDI=drug-drug 
interaction; DPD= dihydropyrimidine dehydrogenase; ICOS=inducible T-cell co-stimulatory receptor; 
IB=Investigator’s brochure; irAE=immune-related AE; mAb=monoclonal antibody; SoA=schedule of 
activities; TCR=T-cell receptor 
2.3.2. 
Benefit Assessment 
This is a randomized, double-blind, Phase II/III study of pembrolizumab in combination 
with placebo and 5FU/platinum chemotherapy versus pembrolizumab in combination 
with GSK3359609 and 5FU/platinum chemotherapy for first line treatment of R/M 
HNSCC. Regarding benefit, the focus should be on the following key points: first, the 
KEYNOTE-048 results support pembrolizumab as a backbone agent in the standard of 
care for the first-line treatment of R/M HNSCC (refer to Section 2.1); second, 
GSK3359609 in combination with pembrolizumab was shown to have a positive ORR 
and disease control rate in a small cohort (n=34) of participants with PD-1/L1 treatment 
naïve HNSCC (refer to Section 2.2.3 for further details and Rischin, 2019). 
2.3.3. 
Overall Benefit: Risk Conclusion 
This is a randomized, double-blind, Phase II/III study of GSK3359609/pembrolizumab in 
combination with 5FU-platinum chemotherapy versus placebo/pembrolizumab in 
combination with5FU-platinum chemotherapy for first line treatment of R/M HNSCC. 
Regarding benefit, the focus should be on the following key points: first, the KEYNOTE-
048 results support pembrolizumab as a backbone agent in the standard of care for the 
first-line treatment of R/M HNSCC (refer to Section 2.1); second, GSK3359609 in 
combination with pembrolizumab was shown to have a positive ORR and disease control 
rate in a small cohort (n=34) of participants with PD-1/L1 treatment naïve HNSCC (refer 
to Section 2.2.3). The risks seen in participants exposed to GSK3359609 (at various 
doses) in combination with pembrolizumab are summarized in Table 2. Of 260 
participants treated with the combination of GSK3359609 and pembrolizumab in the 
INDUCE-1 study, most had at least 1 adverse event, the majority of which were low 
grade events. The evidence to date for the combination of GSK3359609 with 
pembrolizumab favor an acceptable safety profile and an expected clinical benefit in 
participants with HNSCC within the context of the anti-tumor effect observed in the 
small cohort of participants with HNSCC enrolled in INDUCE-1. The addition of 

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fluorouracil with platinum-based chemotherapy to GSK3359609 in combination 
pembrolizumab is not expected to have overlapping toxicities over that observed with 
pembrolizumab in combination with 5FU-platinum chemotherapy. Careful monitoring 
and management are required throughout the study, refer to Section 6.6 and in the 
Schedule of Activities (SoA) in Section 1.3. Thus, initiating this Phase II/III study using 
the combination of pembrolizumab plus chemotherapy with GSK3359609 provides 
participants with the potential to realize an improved benefit to that seen previously in 
KN-048 [Burtness, 2018; Rischin, 2019]. 
 
3. 
OBJECTIVES AND ENDPOINTS1 
Primary 
• 
Compare the efficacy of GSK3359609 in 
combination with pembrolizumab and 
5FU-platinum chemotherapy compared with 
placebo in combination with pembrolizumab 
and platinum-based chemotherapy in the total 
(PD-L1 CPS all) population and in the PD-L1 
positive (PD-L1 CPS 1) population. 
• 
OS in the total and the PD-L1 CPS1 
populations, defined as the time from the date 
of randomization until the date of death due to 
any cause 
• 
PFS per RECIST v1.1 by Investigator 
assessment in the total population, defined as 
the time from the date of randomization until 
the date of disease progression or death due to 
any cause, whichever comes first 
Secondary 
• 
Further compare the efficacy of GSK3359609 
in combination with pembrolizumab and 
5FU-platinum chemotherapy compared with 
placebo in combination with pembrolizumab 
and 5FU-platinum chemotherapy 
• 
PFS per RECIST v1.1 by Investigator 
assessment in the PD-L1 CPS1 population 
• 
Milestone OS rate at 12, 24 and 36 months in 
the total and the PD-L1 CPS1 populations 
• 
ORR per RECIST v1.1 by Investigator 
assessment in the total and the PD-L1 CPS1 
populations 
• 
DCR per RECIST v1.1 by Investigator 
assessment in the total and the PD-L1 CPS1 
populations 
• 
DoR per RECIST v1.1 by Investigator 
assessment in the total and the PD-L1 CPS1 
populations  
• 
Evaluate the safety and tolerability of 
GSK3359609 in combination with 
pembrolizumab and5FU-platinum 
chemotherapy compared with placebo in 
combination with pembrolizumab and 
5FU-platinum chemotherapy 
• 
Frequency and severity of AEs, AESI, SAEs 
in the total and the PD-L1 CPS1 populations 
• 
Dose modifications (i.e., interruptions, 
discontinuations) in the total and the PD-L1 
CPS1 populations 
• 
Evaluate and compare disease and treatment 
related symptoms and impact on function and 
HRQoL of GSK3359609 in combination with 
pembrolizumab and 5FU-platinum 
chemotherapy versus placebo in combination 
• 
The time to deterioration in Pain measured by 
the EORTC QLQ-H&N35 pain domain in the 
total and the PD-L1 CPS1 populations 

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with pembrolizumab and 5FU-platinum 
chemotherapy 
• 
The time to deterioration in Physical Function 
as measured by the PROMIS PF 8c in the total 
and the PD-L1 CPS1 populations 
Exploratory 
• 
Evaluate the efficacy of GSK3359609 in 
combination with pembrolizumab and 
5FU-platinum chemotherapy compared with 
placebo in combination with pembrolizumab 
5FU-platinum chemotherapy 
• 
PFS, ORR, DCR, DoR per iRECIST 
• 
PFS2, defined as the time from randomization 
to second objective disease progression per 
RECIST v1.1 by Investigator assessment, or 
death due to any cause, whichever comes first 
• 
Evaluate and compare disease and treatment 
related symptoms and impact on function and 
HRQoL of GSK3359609 in combination with 
pembrolizumab and 5FU-platinum 
chemotherapy versus placebo in combination 
with pembrolizumab and 5FU-platinum 
chemotherapy 
• 
Symptomatic AEs as measured by the FACT 
GP5 
• 
Changes in other domains of quality of life as 
measured by the selected EORTC IL50/51 
(subset of domains of the EORTC QLQ-C30 
and EORTC QLQ-H&N35), BPI-SF I3 and 
EQ-5D 
• 
Evaluate healthcare resource utilization of 
participants in the GSK3359609 in 
combination with pembrolizumab and 
5FU-platinum chemotherapy arm versus 
participants in the placebo in combination 
with pembrolizumab and 5FU platinum 
chemotherapy arm 
• 
Non-protocol healthcare encounters, such as 
provider visits, emergency room visits, 
hospitalizations, medications, tests, or 
procedures 
• 
Evaluate GSK3359609 PK properties 
• 
Summary of GSK3359609 concentrations and 
Cmax, Ctrough,  
• 
Determine immunogenicity of GSK3359609 
• 
Anti-drug antibody incidence 
• 
Explore relationship between biomarkers in 
tumor and blood, such as immune response 
biomarkers, target expression and efficacy 
endpoints 
• 
Tumor and blood-based analysis of DNA, 
RNA, and protein analytes/profiles2; OS, PFS, 
ORR, other efficacy parameters 
• 
Genetics Research: Investigate the 
relationship between host genetic variations 
and response to therapy 
• 
Germline genetic evaluations may be 
conducted for: 
• 
Clinical response, including 
GSK3359609/pembrolizumab or any 
concomitant medicines 
• 
Disease susceptibility, severity, and 
progression and related conditions 
Abbreviations: AE=adverse events; AESI=adverse events of special interest; Brief Pain Inventory 
Short Form- Item 3= BPI-SF I3; CPS = combined positive score; DCR=disease control rate; 
DNA=deoxyribonucleic acid; DoR=duration of response; EORTC IL50= European Organisation for 
Research and Treatment of Cancer Quality of Life Questionnaire Item Library 50; EORTC IL51= 
European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Item 
library 51; FACT-GP5 = Functional Assessment of Cancer Therapy – General (Item GP5); 
HRQoL=health-related quality of life; iRECIST=immune-based Response Evaluation Criteria in Solid 
Tumors; ORR=overall response rate; OS=overall survival; PD-L1 = Programmed Death Receptor 
Ligand-1; PFS=progression-free survival; PROMIS PF 8c= Patient-Reported Outcomes Measurement 
Information System-Physical Function-Short Form; RECIST= Response Evaluation Criteria in Solid 
Tumors; RNA=ribonucleic acid 

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1. Refer to Section 9.4 for definitions/attributes of efficacy endpoints, Section 9.1.1 for key 
endpoints/hypotheses and Section 9.8 for multiplicity control 
2. Refer to Section 8.8 for details on biomarkers 
 
4. 
STUDY DESIGN 
4.1. 
Overall Design 
This is a randomized, double-blinded, adaptive Phase II/III study comparing the 
combination of GSK3359609 with pembrolizumab and 5FU-platinum chemotherapy to 
placebo in combination with pembrolizumab and 5FU-platinum chemotherapy in 
participants with recurrent or metastatic HNSCC of the oral cavity, oropharynx, 
hypopharynx or larynx. 
The first decision that will inform on the Study 209227 design is guided by the analysis 
of external data from Study 209229 of ORR/DCR per RECIST v1.1 in the approximate 
first 100 participants across the 2 study treatment arms (PD-L1 CPS ≥1 population) with 
a minimum follow-up of 6 months [GlaxoSmithKline Document Number 
2019N403389_03]. If the outcome of the decision from Study 209229 expands Study 
209229 to a Phase III study, then there will be no pause in enrollment for Study 209227, 
and the sample size for the Study 209227 Phase III design becomes 640 participants 
(refer to Section 9.2.1). 
If the analysis for the adaptive decision in Study 209229 is to remain as a Phase II then 
Study 209227 will be conducted as a Phase II/III seamless design with the second 
adaptive decision for Study 209227 based on the outcome of the first OS analysis within 
Study 209227. This first OS analysis will occur after 9 months of OS follow-up in the 
first 300 participants; there will be a pause in enrollment. If the outcome of the decision 
is for Study 209227 to expand to a Phase III study, an additional 340 participants will be 
randomized. Otherwise, Study 209227 will stop for futility, then no further enrollment 
will occur and no further analysis for OS will be performed. Refer to Section 9.2 and 
Section 9.5 for details on sample size estimations and operating characteristics of the 
efficacy analyses. If the analysis for the adaptive decision in Study 209229 is to stop for 
futility (∆ORR<0% and ∆DCR<0%) then Study 209227 may stop and no further accrual 
will occur. 
In addition, all available data from other clinical studies may inform on the decision of a 
Phase III design.  
If Study 209227 expands to a Phase III, all participants randomized are included for 
inference at the end of Phase III (approximately 640 participants). In addition, all primary 
endpoints and key secondary endpoints are formally tested for statistical significance at 
the end of Phase II/III or Phase III. 
The study will evaluate the efficacy, safety, and patient reported outcomes of 
GSK3359609 in combination with pembrolizumab and 5FU-platinum chemotherapy 
(Arm 1) compared with placebo in combination with pembrolizumab and 5FU-platinum 
chemotherapy (Arm 2) as a standard first-line regimen in HNSCC. Study participants will 

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be stratified by PD-L1 CPS status, and HPV status for oropharyngeal cancers then 
randomly assigned to the two treatment arms in a 1:1 ratio. 
Stratification factor subgroups are PD-L1 CPS by central laboratory assessment (CPS20 
versus 1≤ CPS<20 versus CPS <1), and HPV status in oropharynx sites only (p16 
positive versus negative/unknown) versus non-oropharyngeal sites. The overall 
proportion of participants by PD-L1 CPS status in the study population will be capped 
such that PD-L1 CPS 20, 1 CPS <20 or CPS <1 will not exceed the expected 
proportion by 5% for any subgroup. 
The study schematic is provided in Section 1.2. 
4.2. 
Scientific Rationale for Study Design 
The rationale for progressing the combination of GSK3359609 with pembrolizumab and 
chemotherapy in Study 209227 is supported by the efficacy and safety data of the 
GSK3359609 plus pembrolizumab combination in participants with HNSCC from Study 
204691 (refer to Section 2.2.3), the response rate observed is from a single arm cohort. 
Thus, the basis for using the Study 209229 adaptive decision analysis as external data to 
inform on the Study 209227 study design is Study 209229 will evaluate in a randomized 
fashion the response rate of the combination compared with pembrolizumab alone. This 
approach supports a Phase III design by properly balancing the risk and benefit of the 
Phase III expansion decision. 
A Phase II/III design is deemed an efficient approach to consider potentially expanding 
into a Phase III study based on pre-specified adaptive decision rules by randomizing 
additional participants without changing the inclusion and exclusion criteria for 
enrollment, endpoints and randomization scheme. 
The co-primary endpoints are appropriate for this population as overall survival is the 
gold standard measure of clinical benefit and PFS by RECISTv1.1 as a direct measure of 
disease control in a randomized Phase III study setting 
The selection of pembrolizumab  in combination with 5FU/platinum chemotherapy in the 
control arm is supported by the data from KN-048 in which this combination 
demonstrated a significant clinical improvement in OS in all participants compared with 
the EXTREME regimen [Burtness, 2018; Rischin, 2019]; this evidence supported the 
FDA approval of pembrolizumab in combination with 5FU/platinum chemotherapy in the 
first-line disease setting for patients with R/M HNSCC. 
Randomization will be stratified by the following factors associated as prognostic, and 
selective of clinical benefit from pembrolizumab: 
1. PD-L1 CPS (degree of benefit from pembrolizumab depended on PD-L1 status 
[Burtness, 2018; Rischin, 2019]) 
2. HPV status (established as a prognostic factor in the oropharynx region and 
oropharyngeal cancers are staged according by HPV status [Fung, 2017; AJCC, 
2017]) 

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The placebo-controlled, double-blinded design will mitigate the intentional or inadvertent 
bias inherent to an open-label study. 
4.3. 
Justification for Dose 
4.3.1. 
GSK3359609 Dose Justification 
The dose of GSK3359609 planned for registration studies in HNSCC is 24-mg 
administered Q3W. The 24 mg dose of GSK3359609 was selected based upon the 
cumulative clinical evidence to date from the first-time in human (FTIH) Study 
204691/INDUCE-1 that included preliminary efficacy data from the 
GSK3359609/pembrolizumab combination HNSCC expansion cohort, pooled 
preliminary population PK and exposure-response assessments, as well as peripheral 
target engagement and preliminary tumor biomarker assessments. Overall, GSK3359609 
clinical data demonstrate a lack of dose-dependent differences in efficacy or safety 
outcomes. A flat GSK3359609 exposure-response relationship for efficacy and safety 
was found in participants across the range of dose levels evaluated (0.001mg/kg to 
3 mg/kg). Exposures for 24-mg Q3W are expected to lie within this dose level range and 
will be close to those obtained with 0.3 mg/kg Q3W, the dose level where in the HNSCC 
cohort durable objective responses were observed in combination with 200-mg 
pembrolizumab. 
The PK disposition of GSK3359609 was evaluated after 30 minutes of IV infusion at the 
aforementioned dose level range in Study 204691. A preliminary population PK model 
(n = 251; October 2018), which characterized the influence of body weight, age, and 
other participant covariates on exposure, has been developed. Results indicate the PK 
disposition of GSK3359609 is consistent with that of other humanized mAbs, which 
typically have a low clearance (CL) and a limited central volume of distribution (Vc). 
Plasma concentration-time profiles of GSK3359609 exhibit a bi-exponential decline with 
dose-proportional increases in exposure, e.g. Cmax and Cmin. The preliminary 
comparisons of the FTIH data from Part 1 (monotherapy) versus Part 2 (pembrolizumab 
combination) demonstrate no differences in GSK3359609 exposure with concomitant 
administration of pembrolizumab; no drug-drug interaction affecting PK for the 
combination of GSK3359609 and pembrolizumab would be anticipated given that both 
are mAb catabolized via high capacity, non-specific pathways. 
The preliminary FTIH population PK analysis dataset encompassed a wide distribution of 
bodyweight, with a median of 73 kg and a range of 40.8–133 kg. Estimates (90% 
confidence intervals [CI]) of the relationship between clearance and body weight based 
on the population PK model revealed an allometric exponent (α) of 0.056 (95% CI, -
0.364– 0.475) for the CL and 0.314 (95% CI, -0.009 – 0.637) for Vc. In theory, body-
weight–based dosing would be considered most appropriate where CL scales linearly 
with patient bodyweight (α equals to 1), whereas fixed dosing would be more appropriate 
when CL is unaffected by body weight (α = 0). Given that α estimates were closer to 0 
for both CL and Vc, no advantage of weight-based dosing over fixed dosing is expected 
for GSK3359609. Distributions of GSK3359609 exposures from potential fixed doses 
administered Q3W were simulated with the preliminary FTIH population PK model and 
compared with the distributions expected from weight-based dosing regimens, using 

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bodyweight distributions resampled from the Centers for Disease Control National Health 
and Nutrition Examination Survey database. These simulations reveal that a 
GSK3359609 bodyweight-based dose results in slightly higher exposure in heavier 
weight participants, with a GSK3359609 fixed dose expected to provide more consistent 
control of PK variability across the entire bodyweight spectrum. 
As previously indicated, no MTD was established and no dose limiting toxicities were 
observed in the dose escalation cohorts over the range of GSK3359609 dose levels 
(0.001 mg/kg [~0.08 mg] to 3 mg/kg [~240 mg]) evaluated in Study 204691. An 
exposure-response, time-to-event analysis of all reported Grade 2 AEs supports the 
conclusion of similar safety outcomes across the exposure/dose range evaluated, both in 
pooled monotherapy cohorts and pembrolizumab combination cohorts. Evidence of target 
engagement and objective evidence of tumor size reduction were observed in the HNSCC 
expansion cohort at the 0.3 mg/kg dose level. Doses of 0.3 mg/kg (~24-mg) showed high 
ICOS receptor occupancy (RO) levels on CD4 and CD8 T cells over the 21-day dosing 
cycle. Concentration-ICOS RO analyses suggest bodyweight-based doses of 
approximately >0.1 mg/kg maintained approximately >~70% CD4/CD8 RO over the 
entire dosing interval. Preliminary exposure-response assessments of tumor size 
reduction at Week 9 (stratified by tumor type) demonstrate little difference in efficacy 
outcomes across the exposure/ dose range evaluated. 
Hence, the integrated body of evidence supports a 24-mg Q3W dose for evaluation in the 
pivotal studies of HNSCC in combination with pembrolizumab. The distribution of 
exposures from the 24-mg fixed dose are predicted to considerably overlap those 
obtained with the 0.3 mg/kg dose, and importantly, will maintain individual patient 
exposures within the exposure range established in the FTIH study. 
4.3.2. 
Pembrolizumab Dose Justification 
The planned dose of pembrolizumab for this study is 200 mg Q3W. This pembrolizumab 
dose and schedule is consistent with that administered in the KN-048 study and which is 
administered in combination with GSK3359609 in the ongoing INDUCE-1 study. 
Based on the totality of data generated in the Keytruda development program, 200 mg 
Q3W is the appropriate dose of pembrolizumab for adults across all indications, 
regardless of tumor type. As outlined below, this dose is justified by: 
• Clinical data from 8 randomized studies demonstrating flat dose- and exposure-
efficacy relationships from 2 mg/kg Q3W to 10 mg/kg every 2 weeks (Q2W), 
• Clinical data showing meaningful improvement in benefit-risk including overall 
survival at 200 mg Q3W across multiple indications, and 
• Pharmacology data showing full target saturation in both systemic circulation (inferred 
from PK data) and tumor (inferred from physiologically-based PK [PBPK] analysis) at 
200 mg Q3W. 
Among the 8 randomized dose-comparison studies, a total of 2262 participants were 
enrolled with melanoma and non-small cell lung cancer, covering different disease 
settings (treatment naïve, previously treated, PD-L1 enriched, and all-comers) and 

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different treatment settings (monotherapy and in combination with chemotherapy). Five 
studies compared 2 mg/kg Q3W versus 10 mg/kg Q2W (KN001 Cohort B2, KN001 
Cohort D, KN002, KN010, and KN021), and 3 studies compared 10 mg/kg Q3W versus 
10 mg/kg Q2W (KN001 Cohort B3, KN001 Cohort F2 and KN006). All of these studies 
demonstrated flat dose- and exposure-response relationships across the doses studied 
representing an approximate 5- to 7.5-fold difference in exposure. The 2 mg/kg (or 200 
mg fixed-dose) Q3W provided similar responses to the highest doses studied. 
Subsequently, flat dose-exposure-response relationships were also observed in other 
tumor types including head and neck cancer, bladder cancer, gastric cancer and classical 
Hodgkin’s Lymphoma, confirming 200 mg Q3W as the appropriate dose independent of 
the tumor type. These findings are consistent with the mechanism of action of 
pembrolizumab, which acts by interaction with immune cells, and not via direct binding 
to cancer cells. 
Additionally, pharmacology data clearly show target saturation at 200 mg Q3W. First, 
PK data in KN001 evaluating target-mediated drug disposition conclusively 
demonstrated saturation of PD-1 in systemic circulation at doses much lower than 200 
mg Q3W. Second, a PBPK analysis was conducted to predict tumor PD-1 saturation over 
a wide range of tumor penetration and PD-1 expression. This evaluation concluded that 
pembrolizumab at 200 mg Q3W achieves full PD-1 saturation in both blood and tumor. 
Finally, population PK analysis of pembrolizumab, which characterized the influence of 
body weight and other participant covariates on exposure, has shown that the fixed-
dosing provides similar control of PK variability as weight-based dosing, with 
considerable overlap in the distribution of exposures from the 200 mg Q3W fixed dose 
and 2 mg/kg Q3W dose. Supported by these PK characteristics and given that fixed-dose 
has advantages of reduced dosing complexity and reduced potential of dosing errors, the 
200 mg Q3W fixed-dose was selected for evaluation across all pembrolizumab protocols. 
4.3.3. 
Chemotherapy Dose Justification 
In Arm 1 and Arm 2, carboplatin (AUC 5) or cisplatin at 100 mg/m2 may be combined 
with 5FU at 1000 mg/m2 (Refer to Table 5). The doses selected were in accordance with 
standard doses given for first-line treatment of R/M HNSCC [Vermorken, 2008]. 
4.4. 
End of Study Definition 
A participant is considered to have completed the study if he/she has completed all 
phases of the study including follow-up for survival or until follow-up for survival is no 
longer required (refer to Section 7.1). 
The end of the study is defined as the date of the last visit of the last participant in the 
study. 
 

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5. 
STUDY POPULATION 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also 
known as protocol waivers or exemptions, is not permitted. 
5.1. 
Inclusion Criteria 
Participants are eligible for inclusion in this study if all the following criteria apply: 
1. Capable of giving signed informed consent/assent which includes compliance 
with the requirements and restrictions listed in the ICF and in this protocol  
2. Male or female, age 18 years; at the time consent is obtained (minimum age 
requirement per local regulatory requirements) 
3. Histological or cytological documentation of HNSCC that was diagnosed as 
recurrent or metastatic and considered incurable by local therapies 
4. Primary tumor location of the oral cavity, oropharynx, hypopharynx or larynx 
5. No prior systemic therapy administered in the recurrent or metastatic setting (with 
the exception of systemic therapy completed > 6 months prior if given as part of 
multimodal treatment for locally advanced disease and no disease 
progression/recurrence within 6 months of the completion of curatively intended 
systemic treatment) 
6. Measurable disease per response evaluation criteria in solid tumors (RECIST) 
version 1.1 guidelines 
7. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score of 
0 or 1 
8. Adequate organ function as defined in Table 3. 
Table 3 
Definitions of Adequate Organ Function 
System 
Laboratory Values 
Hematologica,b 
ANC 
1.5x109/L 
Hemoglobin 
9 g/dL 
Platelets 
100x109/L 
Hepaticb 
Albumin 
2.5 g/dL 
ALT 
2.5xULN or ≤5xULN for participants with documented liver 
metastases 
Total bilirubin 
Bilirubin ≤1.5xULN (isolated bilirubin >1.5xULN is 
acceptable if bilirubin is fractionated and direct bilirubin 
<35%) 
Renalb 
Calculated CrClc 
60 mL/min 

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System 
Laboratory Values 
Coagulationb 
INR OR PT 
aPTT  
1.5 × ULN unless participant is receiving anticoagulant 
therapy as long as PT or aPTT is within therapeutic range of 
intended use of anticoagulants 
Cardiacb 
Ejection fractiond 
50% 
Abbreviations: ANC = Absolute neutrophil count; ALT = alanine aminotransferase; CrCl = creatinine 
clearance; ECHO= echocardiogram; eGFR=estimated glomerular filtration rate; MUGA= multigated 
acquisition scan TSH = thyroid-stimulating hormone; ULN = upper limit of normal; WNL = within normal 
limits 
a. 
Participants may be transfused or receive growth factor treatment to meet minimum hematologic 
values up to 7 days prior to determining eligibility 
b. Participant eligibility for the GSK3359609/placebo + pembrolizumab chemotherapy combinations 
requires laboratory values fulfilling the warnings/precautions requirements indicated in the approved 
product label (i.e., CrCl requirements for cisplatin) 
c. 
Estimated CrCl/eGFR is required to be calculated using the Chronic Kidney Disease Epidemiology 
Collaboration (CKD EPI) or Cockcroft-Gault formula; either formula is acceptable and must be 
consistently used for each participant throughout the study. (refer to Section 10.6) 
d. MUGA is acceptable if ECHO is not available; for each participant the same modality must be used for 
all subsequent evaluations 
9. Life expectancy of at least 12 weeks 
10. Female participants: must not be pregnant (as confirmed by a negative serum 
beta-human chorionic gonadotrophin [-hCG] test in females of reproductive 
potential; for further details refer to Section 10.4), not breastfeeding, and at least 
one of the following conditions apply: 
a) Not a woman of childbearing potential (WOCBP) as defined in Section 
10.4.1. 
b) A WOCBP who agrees to use a highly effective method of birth control 
from 30 days prior to randomization and for at least 120 days after the last 
dose of study treatment (Note: duration of contraceptive use after last dose 
of chemotherapy must be consistent with local requirements; however, the 
minimum duration is 180 days after last dose of chemotherapy). Refer to 
Section 10.4.2 for permitted contraceptive methods; contraceptive use 
should be consistent with local regulations regarding the methods of 
contraception for those participating in clinical studies. 
c) The investigator is responsible for review of medical history, menstrual 
history, and recent sexual activity to decrease the risk for inclusion of a 
woman with an early undetected pregnancy 
11. Male participants with female partners of child-bearing potential: must agree to 
use a highly effective contraception while receiving study treatment and for at 
least 120 days after the last dose of study treatment and refrain from donating 
sperm during this period (Note: duration of contraceptive use after last dose of 
chemotherapy must be consistent with local requirements; however, the minimum 
duration is 180 days after last dose of chemotherapy). Refer to Section 10.4.2 for 

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permitted contraceptive methods; contraceptive use should be consistent with 
local regulations regarding the methods of contraception for those participating in 
clinical studies. 
12. Provide tumor tissue from excisional or core biopsy (fine needle aspirates and 
bone biopsies are not acceptable) acquired within 2 years prior to randomization 
for PD-L1 immunohistochemistry (IHC) testing by central laboratory. A fresh 
tumor biopsy, using a procedure that is safe for the participant on a lesion not 
previously irradiated (unless lesion progressed) will be required if previously 
acquired tumor tissue (i.e., archival tumor tissue) was acquired > 2 years or is 
unavailable//unsuitable for PD-L1 testing. 
13. Have PD-L1 IHC CPS status by central laboratory testing (refer to Section 5.4 for 
definition of screen failure based on PD-L1 CPS restrictions); refer to Section 
8.8.3 for details on PD-L1 IHC assay. Participants in countries governed under 
the European Commission are required to have PD-L1 CPS 1 status. 
a) A specific PD-L1 CPS status may be required to fulfill eligibility (refer to 
Section  9.2 for details on estimated number of participants by PD-L1 CPS 
status) if a PD-L1 CPS status cap is implemented (study population 
proportion by PD-L1 CPS status will not exceed 5% of the planned 
proportions of the PD-L1 CPS subgroups (CPS 20,  1 CPS <20 and 
CPS <1) 
14. Have results from testing of HPV status for oropharyngeal cancer (refer to Section 
8 and Table 1 for details on testing requirements) 
5.2. 
Exclusion Criteria 
Participants are excluded from the study if any of the following criteria apply: 
1. Prior therapy with an anti-PD-1/L1/L2, anti-ICOS directed agent 
2. Systemic approved or investigational anticancer therapy within 30 days or 5 half-
lives of the drug, whichever is shorter. At least 14 days must have elapsed 
between the last dose of prior anticancer agent and the date of randomization 
3. Has high risk of bleeding (examples include but are not limited to tumors 
encasing or infiltrating a major vessel [i.e., carotid, jugular, bronchial artery] 
and/or exhibits other high-risk features such as a fistula, significant cavitary 
lesions, prior history of hemorrhage [ 60 days]) 
NOTE: following principal investigator consultation with the GSK Medical Monitor, 
certain cases may be approved by the GSK Medical Monitor upon review of the case 
(this review may include a requirement to provide images) 
4. Active tumor bleeding 
5. Grade 3 or Grade 4 hypercalcemia 

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6. Major surgery 28 days prior to randomization.  Participants must have also fully 
recovered from any surgery (major or minor) and/or its complications before 
randomization 
7. Toxicity from previous anticancer treatment that includes: 
a. Grade 3/Grade 4 toxicity considered related to prior immunotherapy and 
that led to treatment discontinuation 
b. Toxicity related to prior treatment that has not resolved to Grade 1 
(except alopecia, hearing loss, endocrinopathy managed with replacement 
therapy, and peripheral neuropathy which must be Grade 2) 
8. Received transfusion of blood products (including platelets or red blood cells) or 
administration of colony stimulating factors (including granulocyte colony-
stimulating factor [G-CSF], granulocyte-macrophage colony-stimulating factor, 
recombinant erythropoietin) within 14 days prior to randomization 
9. Central nervous system (CNS) metastases, with the following exception: 
Participants with asymptomatic CNS metastases who are clinically stable and 
have no requirement for steroids for at least 14 days prior to randomization 
Note: Participants with carcinomatous meningitis or leptomeningeal spread are 
excluded regardless of clinical stability 
10. Invasive malignancy or history of invasive malignancy other than disease under 
study within the last 3 years, except as noted below: 
a. Any other invasive malignancy for which the participant was definitively 
treated, has been disease-free for 3 years and in the opinion of the 
principal investigator and GSK Medical Monitor will not affect the 
evaluation of the effects of the study treatment on the currently targeted 
malignancy, may be included in this clinical study 
b. Curatively treated non-melanoma skin cancer or successfully treated in 
situ carcinoma 
c. Low-risk early stage prostate cancer defined as follows: Stage T1c or T2a 
with a Gleason score ≤ 6 and prostatic-specific antigen (PSA) <10 ng/mL 
either treated with definitive intent or untreated in active surveillance that 
has been stable for the past year prior to randomization 
11. Autoimmune disease (current or history; refer to Table 19) or syndrome that 
required systemic treatment within the past 2 years 
Note: Replacement therapies which include physiological doses of corticosteroids 
for treatment of endocrinopathies (for example, adrenal insufficiency) are not 
considered systemic treatments. 

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12. Has a diagnosis of immunodeficiency or is receiving systemic steroids (>10 mg 
oral prednisone or equivalent) or other immunosuppressive agents within 7 days 
prior to randomization 
Note:  
a) Physiologic doses of corticosteroids for treatment of endocrinopathies or 
steroids with minimal systemic absorption, including topical, inhaled, or 
intranasal corticosteroids may be continued if the participant is on a stable 
dose 
b) Steroids as premedication for hypersensitivity reactions (e.g., computed 
tomography [CT] scan premedication) are permitted 
13. Receipt of any live vaccine within 30 days prior randomization 
14. Prior allogeneic/autologous bone marrow or solid organ transplantation 
15. Has current pneumonitis or history of non-infectious pneumonitis that required 
steroids or other immunosuppressive agents 
Note: post-radiation changes in the lung related to prior radiotherapy and/or 
asymptomatic radiation-induced pneumonitis not requiring treatment (Grade 1) 
may be permitted if agreed upon by the investigator and Medical Monitor 
16. Recent history (within the past 6 months) of uncontrolled symptomatic ascites, 
pleural or pericardial effusions 
17. Recent history (within the past 6 months) of gastrointestinal obstruction that 
required surgery, acute diverticulitis, inflammatory bowel disease, or intra-
abdominal abscess 
18. Recent history of allergen desensitization therapy within 4 weeks of 
randomization 
19. History or evidence of cardiac abnormalities within the 6 months prior to 
randomization which include: 
a. Serious, uncontrolled cardiac arrhythmia or clinically significant 
electrocardiogram abnormalities including second degree (Type II) or 
third-degree atrioventricular block 
b. Cardiomyopathy, myocardial infarction, acute coronary syndromes 
(including unstable angina pectoris), coronary angioplasty, stenting or 
bypass grafting 
c. Congestive heart failure (Class II, III, or IV) as defined by the New York 
Heart Association functional classification system 
d. Symptomatic pericarditis 

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20. Current unstable liver or biliary disease per investigator assessment defined by the 
presence of ascites, encephalopathy, coagulopathy, hypoalbuminemia, esophageal 
or gastric varices, persistent jaundice, or cirrhosis 
Note: Stable chronic liver disease (including Gilbert's syndrome or asymptomatic 
gallstones) is acceptable if participant otherwise meets entry criteria 
21. Active infection requiring systemic therapy 
22. Known HIV infection, or positive test for hepatitis B active infection (presence of 
hepatitis B surface antigen), or hepatitis C active infection 
23. History of severe hypersensitivity to monoclonal antibodies or to the 
chemotherapies under investigation including any ingredient used in the 
formulation (Refer to Table 4/Table 5) 
24. Known history of active tuberculosis 
25. Any serious (Grade 3) and/or unstable pre-existing medical condition (aside 
from malignancy) 
NOTE: following principal investigator consultation with the GSK Medical Monitor, 
certain cases may be approved by the GSK Medical Monitor upon review of the case 
26. Any psychiatric disorder, or other condition that could interfere with participant's 
safety, obtaining informed consent, or compliance to the study procedures in the 
opinion of the investigator 
27. Is currently participating in or has participated in a study of an investigational 
agent or has used an investigational device within 4 weeks prior to the date of 
randomization 
Note:  Participants who have entered the follow-up phase of an investigational study 
may participate provided it has been 4 weeks after the last dose of the previous 
investigational agent. 
5.3. 
Lifestyle Considerations 
There are no dietary restrictions nor lifestyle restrictions other than the contraceptive 
requirements defined in Section 10.4. 
5.4. 
Screen Failures 
Screen failures are defined as participants who consent to participate in the clinical study 
but do not meet 1 or more eligibility criteria and therefore are not subsequently 
randomized. If participants are required to have a specific positive PD-L1 CPS status 
based on Competent Authority and/or IRB/Ethics Committee restrictions, or an 
Investigator’s decision, then a participant who is not otherwise randomized due to a 
PD-L1 CPS result will be considered a screen failure. 

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A minimal set of screen failure information is required to ensure transparent reporting of 
screen failure participants to meet the Consolidated Standards of Reporting Trials 
(CONSORT) publishing requirements and to respond to queries from regulatory 
authorities. Minimal information includes demography, screen failure details, eligibility 
criteria, and any serious adverse events (SAEs). 
Individuals who do not meet the criteria for participation in this study (screen failure) 
may be rescreened; rescreened participants will be assigned a new participant number. 
 
6. 
STUDY INTERVENTION 
Study intervention is defined as any investigational intervention(s), marketed product(s), 
placebo, or medical device(s) intended to be administered to a study participant according 
to the study protocol. The term study intervention or study treatment may be used in the 
protocol and study supportive documents (e.g., study reference manual) interchangeable 
and apply to an individual study drug or the combination of study drugs. 
Refer to the SoA for administration of study interventions.  
6.1. 
Study Intervention(s) Administered 
For participants who meet all eligibility criteria and are randomized within the study, the 
maximum duration of treatment with pembrolizumab, GSK3359609 and placebo is 
expected to be approximately 2 years, up to 35 cycles. The duration of chemotherapy 
treatment will be 6 cycles (cycle=21 days). As the maximum duration of GSK3359609 
and pembrolizumab treatment is expected to be two years (up to 35 cycles), once the 
course of chemotherapy treatment is completed after six cycles, GSK3359609/placebo 
and pembrolizumab treatment will continue. If chemotherapy is discontinued prior to 
completion of 6 cycles, GSK3359609/placebo and pembrolizumab treatment may 
continue provided the reason for treatment discontinuation is not required due AE (refer 
to Section 6.6). 
Participants will be randomly assigned to the following combinations: 
GSK3359609/pembrolizumab/5FU-platinum chemotherapy or 
placebo/pembrolizumab/5FU platinum chemotherapy. 
Participants will receive: 
• GSK3359609 24 mg + pembrolizumab 200 mg + 5FU 1000 mg/m2/24 hours for 
4 days + platinum chemotherapy (cisplatin 100 mg/m2 OR carboplatin area under 
the curve [AUC] 5) for 6 cycles followed by GSK3359609 24 mg + 
pembrolizumab 200 mg up to 35 cycles (includes cycles administered in 
combination with chemotherapy) (Arm 1) OR 
• Placebo +pembrolizumab 200 mg + 5FU 1000 mg/m2/24 hours for 4 days + 
platinum chemotherapy (cisplatin 100 mg/m2 OR carboplatin AUC 5) Q3W for 6 
cycles followed by placebo + pembrolizumab 200 mg up to 35 cycles (includes 
cycles administered in combination with chemotherapy) (Arm 2) 

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GSK3359609 or placebo will be administered first followed by pembrolizumab; the 
5FU-platinum chemotherapy will be administered after pembrolizumab infusion is 
complete. The sequence in which chemotherapy doublets are administered is per standard 
practice; participants should receive the chemotherapy indicated premedication regimens 
and supplementation requirements according to the approved product label or standard 
practice (i.e., corticosteroids, diphenhydramine, hydration). 
The GSK3359609/placebo combinations with pembrolizumab and 5FU-platinum 
chemotherapy regimens will be administered intravenously to participants at each study 
site under medical supervision of an investigator or designee. The date and time of 
administration for each agent will be documented in the source documents and reported 
in the electronic case report form (eCRF). Participants should remain under observation 
at the study site post-study treatment infusion per the judgement of the investigator or as 
per institutional guidelines. 
Participants should remain under observation at the study site post-study treatment 
infusion per the judgement of the investigator or as per institutional guidelines. 
The study reference manual (SRM) contains details on product administration and 
specific instructions for the preparation of both GSK3359609 and pembrolizumab 
infusions, and administration of these infusions. The description, preparation and 
administration of placebo is provided in the SRM. 
The details on the chemotherapy product characteristics and instructions for preparation 
and administration are according to the individual package inserts. 
Table 4 
Study Intervention Description and Administration 
 
Study Agent1 
Product Name: 
GSK3359609 
Pembrolizumab 
Placebo 
Product Description 
Humanized anti-
ICOS IgG4 mAb 
Humanized anti-PD-1 
IgG4 mAb 
Sterile normal saline 
Dosage form 
/strength: 
10 mg/mL solution 
100 mg/4 mL 
solution/25 mg/mL 
0.9% Sodium 
Chloride for Injection  
Planned dosage 
level(s): 
24 mg 
200 mg 
N/A 
Route of 
Administration  
IV infusion 
IV infusion 
IV infusion 
Dosing instructions/ 
Frequency: 
Administer diluted 
product /once Q3W 
(refer to SRM for 
infusion time) 
Administer diluted 
product /once Q3W 
(refer to SRM for 
infusion time) 
Administer product 
/once Q3W (refer to 
SRM for infusion 
time) 
Packaging and 
Labelling  
Provided in vials 
labelled as required 
per country 
requirement. 
Provided in vials 
labelled as required 
per country 
requirement. 
Provided by the site 
unless required by the 
Sponsor as per 
country requirement 
Study Arm 
1  
1 and 2 
2 
Manufacturer 
GSK 
Merck 
N/A 

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Abbreviations: GSK=GlaxoSmithKline; IgG4=immunoglobulin G4; IV-intravenous; mAb=monoclonal 
antibody; mg=milligram; ml=millilitre; N/A=not applicable; PD-1=programmed cell death receptor1; 
Q3W=every three weeks; SRM=study reference manual 
1. Refer to GSK3359609 and Pembrolizumab IB for formulation description 
Table 5 
Chemotherapy Description and Administration 
Chemotherapy1 
Product Name: 
Fluorouracil 
Cisplatin 
Carboplatin 
Product Description 
Nucleoside analog/ 
small molecule 
DNA cross-
linker/small molecule 
DNA cross-
linker/small molecule 
Dosage form 
/strength: 
Refer to package 
insert 
Refer to package 
insert 
Refer to package 
insert 
Planned dosage 
level(s): 
1000 mg/m2/ 
24 hours 
100 mg/m2 
AUC 52 
Route of 
Administration  
IV infusion 
IV infusion 
IV Infusion 
Dosing instructions/ 
Frequency: 
 
Administer diluted 
product continuous 
on Day 1 through 
Day 4 of every 21-
day cycle (Q3W) 
Administer diluted 
product /once Q3W 
Administer diluted 
product /once Q3W 
Packaging and 
Labelling 
Provided by the site 
unless required by the 
Sponsor as per 
country requirement 
Provided by the site 
unless required by the 
Sponsor as per 
country requirement 
Provided by the site 
unless required by the 
Sponsor as per 
country requirement 
Study Arms 
1 and 2 
1 and 2 
1 and 2 
Abbreviations: AUC=area under the curve; FU= Fluorouracil; GFR=glomerular filtration rate; 
IV=intravenous; m= meters; mg=milligrams; min=minute; ml=millilitres; Q3W= every three weeks 
1. Chemotherapies will be sourced locally from commercial stock, except in countries where Regulatory 
Authorities mandate the sponsor supply all study treatment(s) required for the conduct of a clinical 
study. 
2. Carboplatin dosage calculation is according to the Calvert equation; consider capping carboplatin dose 
based on a GFR estimate that is capped at 125 mL/min for participants with normal renal function 
[NCCN, 2018]. 
6.2. 
Preparation/Handling/Storage/Accountability 
1. The investigator or designee must confirm appropriate temperature conditions have 
been maintained during transit for all study intervention received and any 
discrepancies are reported and resolved before use of the study intervention. 
2. The investigator or designee must confirm appropriate temperature conditions have 
been maintained during transit for all study intervention received and any 
discrepancies are reported and resolved before use of the study intervention. 
3. Only participants enrolled in the study may receive study intervention and only 
authorized site staff may supply or administer study intervention. All study 
interventions must be stored in a secure, environmentally controlled, and monitored 
(manual or automated) area in accordance with the labeled storage conditions with 
access limited to the investigator and authorized site staff. 

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4. The investigator, institution, or the head of the medical institution (where applicable) 
is responsible for study intervention accountability, reconciliation, and record 
maintenance (i.e., receipt, reconciliation, and final disposition records). 
5. Further guidance and information for the final disposition of unused study 
intervention are provided in the SRM. 
6. Under normal conditions of handling and administration, GSK3359609, placebo and 
pembrolizumab is not expected to pose significant safety risks to site staff. Take 
adequate precautions to avoid direct eye or skin contact and the generation of 
aerosols or mists. In the case of unintentional occupational exposure notify the 
monitor, Medical Monitor and/or GSK study contact. Refer to the respective 
chemotherapy labeling for details on handling and administration. 
NOTE: A Material Safety Data Sheet (MSDS)/equivalent document describing 
occupational hazards and recommended handling precautions either will be provided 
to the investigator, where this is required by local laws, or is available upon request 
from GSK. 
7. Precaution will be taken to avoid direct contact with the chemotherapy agents. A 
Material Safety Data Sheet (MSDS) describing occupational hazards and 
recommended handling precautions will be provided to the investigator. In the case 
of unintentional occupational exposure notify the monitor, Medical Monitor and/or 
GSK study contact. 
NOTE: Precaution will be taken to avoid direct contact with the study intervention.  
A MSDS describing occupational hazards and recommended handling precautions 
will be provided to the investigator. In the case of unintentional occupational 
exposure notify the monitor, Medical Monitor and/or GSK study contact. 
6.3. 
Measures to Minimize Bias: Randomization and Blinding 
Randomization will occur centrally using an Interactive Response Technology (IRT); 
refer to the SRM for detail on randomization process. Participants will be randomly 
assigned to a study treatment arm in a 1:1 ratio to either receive GSK3359609 24 mg in 
combination with pembrolizumab 200 mg and 5FU-platinum chemotherapy or placebo in 
combination with pembrolizumab 200 mg and 5FU-platinum chemotherapy. 
Randomization will be stratified according to the following factors: 
1. PD-L1 CPS status (CPS ≥20 vs. 1≤ CPS <20 vs. CPS <1) 
2. HPV status (oropharyngeal cancers [positive vs. negative/unknown] vs. non-
oropharyngeal cancers). 
The overall proportion of participants by PD-L1 CPS status will be capped by the IRT 
such that the maximum proportion of participants in PD-L1 CPS 20, 1CPS <20 or CPS 
<1 will not exceed the expected proportion by 5% for either subgroup. 
This is a double-blind study. The participant, the investigator and site staff involved in 
the treatment administration or clinical management of the participants will remain 
blinded to each participant’s assigned study treatment throughout the course of the study. 
Site unblinded staff will provide the investigative blinded staff with prepared blinded 
GSK3359609 or placebo infusion solutions, packaged identically in order to maintain the 

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blinding, for administration at scheduled infusion visits. Refer to the SRM for 
information on labelling and dispensing procedures to mitigate unblinding. In the event a 
participant’s study treatment assignment is unblinded to the blinded site staff and/or the 
participant, the participant is permitted to continue/remain in the study; the site must 
notify the GSK’s clinical research associate (CRA) within 24 hours. 
GSK personnel or delegates, except GSK staff involved in the review/monitoring of site 
pharmacy records and GSK clinical supplies group, will remain blinded to each 
participant’s assigned study treatment throughout the course of the study. 
GSK’s Global Clinical Safety and Pharmacovigilance staff may unblind the intervention 
assignment for any participant with an SAE. If the SAE requires that an expedited 
regulatory report be sent to one or more regulatory agencies, a copy of the report, 
identifying the participant’s intervention assignment, may be sent to investigators in 
accordance with local regulations and/or GSK policy. 
In the event of a medical emergency, Investigators may unblind a participant’s treatment 
assignment immediately through the IRT system by accessing a participant’s home 
screen using the Subjects tab and clicking the Unblind button. Further details may be 
found in the SRM and the IRT manual. 
6.4. 
Study Intervention Compliance 
• 
All study agents will be intravenously administered to participants at the site. 
Administration will be documented in the source documents and reported in the 
eCRF. Refer to the SRM for further details. 
6.5. 
Concomitant Therapy 
Any medication or vaccine (including over-the-counter or prescription medicines, 
vitamins, and/or herbal supplements) that the participant is receiving at the time of 
enrollment or receives during the study must be recorded along with: 
• 
reason for use 
• 
dates of administration including start and end dates 
• 
dosage information including dose and frequency 
The GSK clinical team should be contacted if there are any questions regarding 
concomitant or prior therapy. 
6.5.1. 
Permitted Medications and Non-drug Therapies 
All participants should receive full supportive care during the treatment course of the 
study, including transfusion of blood and blood products, growth factors and treatment 
with antibiotics, antiemetics, antidiarrheals, and analgesics, bisphosphonates or other 
medications as appropriate. Seasonal flu vaccine is permitted as an injection only, that is, 
intra-nasal flu vaccine is not permitted. Elective palliative surgery or radiation may be 
permitted on a case-by-case basis in consultation with GSK Medical Monitor. 

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The following medications are permitted as indicated: 
a. Bisphosphonates and receptor activator of nuclear factor-kappaB ligand 
(RANKL) inhibitors (e.g., denosumab): permitted for treatment of bone 
metastasis or other indicated conditions such as hypercalcemia provided 
participants have been on a stable dose for at least 4 weeks prior to 
randomization date. Note: prophylactic use in participants without evidence or 
history of bone metastasis is not permitted, except for the treatment of 
osteoporosis. 
b. Steroids: refer to Section 6.6 and the associated sub-sections for acceptable 
use while participant is receiving study treatment. Participants with pre-
existing conditions requiring steroids are permitted to continue taking up to a 
maximum of 10 mg of prednisone per day or equivalent provided the 
participant has been on a stable dose for at least 28 days before date of 
randomization; refer to exclusion criterion 9 in Section 5.2 for further 
requirements. Steroids used for chemotherapy premedication are permitted. 
6.5.2. 
Prohibited Medications and Non-drug Therapies 
The following medications are prohibited before the date of randomization (refer to 
Section 5.2 for specific time requirements) and while on treatment in this study: 
a. Anticancer therapies other than those referred to as Study Intervention/Treatment 
that include but are not limited to chemotherapy, immunotherapy, biologic 
therapy, hormonal therapy (other than physiologic replacement), surgery, and 
radiation therapy (other than palliative intervention as described in Section 6.5.1 ) 
b. Any investigational drug (s) other than those referred to as Study 
Intervention/Treatment 
c. Live vaccines such as intra-nasal flu vaccine 
d. Steroids at >10 mg of prednisone per day or equivalent; refer to Section 6.5.1 for 
permitted use of steroids 
6.5.2.1. 
Anti-cancer Therapy After Study Intervention Discontinuation 
Treatment with ICOS or ICOS ligand directed/targeted agents as post study anti-cancer 
therapy are prohibited for participants who permanently discontinue study treatment. 
6.6. 
Dose Modification 
Distinct safety management guidelines, including dose modification algorithms, are 
provided in this section for: 
• 
GSK3359609 
• 
Pembrolizumab 
Refer to chemotherapy prescribing information or standard practice guidelines for the 
management of chemotherapy-related AEs or potential safety-related issues; including 
resuming chemotherapy treatment and dose reductions following recovery of AE. 

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Please note: In instances where the investigator is directed to permanently discontinue 
study treatment, the instructions are mandatory as described in Section 7.1. 
All AEs are to be graded according to NCI-CTCAE (version 5.0) [NCI, 2017]. All dose 
modifications and the reason(s) for the dose modification must be documented in the 
eCRF. 
Refer to pembrolizumab prescribing information [KEYTRUDA, 2019] or IB [Merck, 
2021] for additional information regarding the background and the management of other 
AEs or potential safety-related issues. The investigator may consult the GSK Medical 
Monitor on study treatment modifications (i.e., holds or discontinuation) or on the 
management of AEs. 
6.6.1. 
General Guidelines for Immune-Related Adverse Events 
AEs associated with immunotherapy treatment may be immune-mediated. These 
immune-related AEs (irAEs) may occur shortly after the first dose or several months after 
the last dose of treatment, or during the treatment course, and may affect more than one 
body system simultaneously. Therefore, early recognition of and initiation of treatment 
for these events is critical to reduce potential complications. Based on existing data from 
the study 204691, most treatment-related AEs were Grade 1 or 2, managed with 
supportive care and if appropriate the administration of corticosteroids. 
For suspected irAEs, ensure adequate evaluation to confirm the etiology or exclude other 
causes. Additional procedures or tests such as, but not limited to, bronchoscopy, 
endoscopy, or skin biopsy may be included as part of the evaluation. Based on the 
severity of irAEs, withhold or permanently discontinue treatment and administer 
corticosteroids. Dose modification and toxicity management guidelines for irAEs 
associated with immunotherapies are provided in Table 6. 
Before administration of study treatment, investigators are to review a participant’s AEs, 
concomitant medications, and clinical evaluation results, e.g., vital signs, laboratory 
results, ECOG PS, physical examination findings, responses, etc. as outlined in the 
Schedule of Activities (Table 1) to monitor for new or worsening irAEs and ensure 
continues dosing is appropriate. 
Adverse Events of Special Interest (AESI) 
AESI are defined as events of potential immunologic etiology, including irAEs. Such 
events recently reported after treatment with other immune modulatory therapy include 
colitis, uveitis, hepatitis, pneumonitis, diarrhea, endocrine disorders, and specific 
cutaneous toxicities, as well as other events that may be immune mediated. 
Table 6 
Dose Modification and Toxicity Management Guidelines for Immune-
Related AEs 
General instructions: 
• Corticosteroid taper should be initiated upon irAE improving to Grade 1 and 
continue to taper over at least 4 weeks. 

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• For situations where immunotherapy treatment has been withheld, treatment can 
be resumed after irAE has been reduced to Grade 1 and corticosteroid has been 
tapered. Immunotherapy treatment should be permanently discontinued if irAE 
does not resolve or corticosteroids cannot be reduced to ≤10 mg prednisone or 
equivalent per day within 12 weeks of last dose of study treatment.  
• For severe and life-threatening irAEs, IV corticosteroid should be initiated first 
followed by oral steroid. Other immunosuppressive treatment should be initiated 
if irAEs cannot be controlled by corticosteroids. 
Immune-related 
AEs 
Severity 
Grade or 
Condition 
(CTCAEv5.0) 
Action Taken 
toa: 
GSK3359609/ 
Pembrolizumab 
Management: 
Corticosteroid 
and/or Other 
Therapies 
Monitoring and 
Follow-up 
Respiratory 
Pneumonitis  
Grade 2 
Withhold  
• 
Administer 
corticosteroids 
(initial dose of 
1-2 mg/kg 
prednisone or 
equivalent) 
followed by 
taper 
• 
Add 
prophylactic 
antibiotics for 
opportunistic 
infections 
• 
Monitor 
participants for 
signs and 
symptoms of 
pneumonitis. 
• 
Evaluate 
participants with 
suspected 
pneumonitis with 
radiographic 
imaging and initiate 
corticosteroid 
treatment. 
Grade 3 or 
Grade 4, or 
recurrent 
Grade 2 
Permanently 
discontinue 
Gastrointestinal 
Diarrhea / Colitis 
Grade 2 or 
Grade 3 
Withhold 
• 
Administer 
corticosteroids 
(initial dose of 
1-2 mg/kg 
prednisone or 
equivalent) 
followed by 
taper 
• 
Monitor 
participants for 
signs and 
symptoms of 
enterocolitis (i.e., 
diarrhea, abdominal 
pain, blood or 
mucus in stool with 
or without fever) 
and of bowel 
perforation (i.e., 
peritoneal signs and 
ileus). 
• 
Participants with ≥ 
Grade 2 diarrhea 
suspecting colitis 
should consider GI 
consultation and 
performing 
endoscopy to rule 
out colitis.  
• 
Participants with 
diarrhea/colitis 
should be advised 
to drink liberal 
quantities of clear 
Grade 4 or 
recurrent 
Grade 3 
Permanently 
discontinue 

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Immune-related 
AEs 
Severity 
Grade or 
Condition 
(CTCAEv5.0) 
Action Taken 
toa: 
GSK3359609/ 
Pembrolizumab 
Management: 
Corticosteroid 
and/or Other 
Therapies 
Monitoring and 
Follow-up 
fluids. If sufficient 
oral fluid intake is 
not feasible, fluid 
and electrolytes 
should be 
substituted via IV 
infusion. 
Hepatobiliary 
AST / ALT 
elevation or 
increased 
bilirubin 
Grade 2 
Withhold 
• 
Administer 
corticosteroids 
(initial dose of 
0.5-1 mg/kg 
prednisone or 
equivalent) 
followed by 
taper 
• 
Monitor with liver 
function tests 
(consider weekly or 
more frequently 
until liver enzyme 
value returned to 
baseline or is 
stable. 
• 
Refer to Section 
10.8 for liver safety 
required actions 
and follow-up 
assessments and 
study treatment 
guidelines. 
Grade 3 or 
Grade 4  
Permanently 
discontinue 
• 
Administer 
corticosteroids 
(initial dose of 
1-2 mg/kg 
prednisone or 
equivalent) 
followed by 
taper 
Endocrine 
Type 1 diabetes 
mellitus (T1DM) 
or 
Hyperglycemia 
 
New onset 
T1DM or  
Grade 3 or 
Grade 4 
hyperglycemia 
associated 
with evidence 
of -cell 
failure 
Withholdb 
• 
Initiate insulin 
replacement 
therapy for 
participants 
with T1DM  
• 
Administer 
anti-
hyperglycemic 
in participants 
with 
hyperglycemia  
• 
Monitor 
participants for 
hyperglycemia or 
other signs and 
symptoms of 
diabetes. 
Hypophysitis 
Grade 2 
Withhold 
• 
Administer 
corticosteroids 
and initiate 
hormonal 
replacements as 
clinically 
indicated. 
• 
Monitor for signs 
and symptoms of 
hypophysitis 
(including 
hypopituitarism and 
adrenal 
insufficiency). 
Grade 3 or 
Grade 4  
Withhold or 
permanently 
discontinueb  
Hyperthyroidism  Grade 2 
Continue 
• 
Treat with non-
selective beta-
blockers (e.g., 
propranolol) or 
thionamides as 
appropriate  
• 
Monitor for signs 
and symptoms of 
thyroid disorders. 
Grade 3 or 
Grade 4  
Withhold or  
Permanently 
discontinueb 
Hypothyroidism 
Grade 2, 
Grade 3, or 
Grade 4 
Continue 
• 
Initiate thyroid 
replacement 
hormones (e.g., 
• 
Monitor for signs 
and symptoms of 
thyroid disorders 

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Immune-related 
AEs 
Severity 
Grade or 
Condition 
(CTCAEv5.0) 
Action Taken 
toa: 
GSK3359609/ 
Pembrolizumab 
Management: 
Corticosteroid 
and/or Other 
Therapies 
Monitoring and 
Follow-up 
levothyroxine 
or liothyronine) 
per standard of 
care 
Renal 
Nephritis: Grade 
according to 
increased 
creatinine or 
acute kidney 
injury 
Grade 2 
Withhold 
• 
Administer 
corticosteroids 
(prednisone 1-2 
mg/kg or 
equivalent) 
followed by 
taper 
• 
Monitor changes of 
renal function 
Grade 3 or 
Grade 4  
Permanently 
discontinue 
Cardiovascular 
Myocarditis 
Grade 2 
Grade 3 or 
Grade 4 
 
• 
Based on 
severity of AE 
administer 
corticosteroids 
• 
Ensure adequate 
evaluation to 
confirm etiology 
and/or exclude 
other causes. 
Permanently 
discontinue 
Neurological 
Neurological 
Toxicities 
Grade 2 
Withhold 
• Based on severity 
of AE administer 
corticosteroids 
• Ensure adequate 
evaluation to 
confirm etiology 
and/or exclude other 
causes 
Grade 3 or 
Grade 4 
Permanently 
discontinue 
Skin 
Exfoliative 
Dermatologic 
Conditions 
Suspected SJS, 
TEN, or DRESS 
Withhold 
• Based on severity 
of AE administer 
corticosteroids 
• Ensure adequate 
evaluation to 
confirm etiology 
and/or exclude other 
causes 
Confirmed SJS, 
TEN, or DRESS 
Permanently 
discontinue 
Other 
All other 
immune-related 
AEs 
Grade 3, or 
intolerable/ 
persistent 
Grade 2 
Withhold or 
discontinue 
based on the 
type of eventc 
• 
Based on 
severity of AE 
administer 
corticosteroids 
• 
Ensure adequate 
evaluation to 
confirm etiology or 
exclude other 
causes 
Grade 4 or 
recurrent 
Grade 3  
Permanently 
discontinue 
Abbreviations: AE=adverse events; ALT=alanine aminotransferase; AST= aspartate aminotransferase; 
CTCAE=common terminology criteria for adverse events; DRESS=Drug Rash with Eosinophilia and 
Systemic Symptom; GI=gastrointestinal irAE=immune-related AE; IV=intravenous; kg=kilogram; 
mg=milligram; SJS=Stevens-Johnson Syndrome; T1DM=Type 1 diabetes mellitus; TEN=toxic epidermal 
necrolysis 
a. 
The actions taken for GSK3359609 infer an action required for placebo due to the blinded design. The 
actions taken for GSK3359609/pembrolizumab includes chemotherapy. 
b. The decision to withhold or permanently discontinue study treatment is at the discretion of the 
investigator or treating physician. If control is achieved or Grade 2, study treatment may be resumed. 
c. 
The events that require discontinuation include but are not limited to: encephalitis, and other clinically 
important irAEs (e.g., vasculitis and sclerosing cholangitis). 

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6.6.2. 
Dose Modification and Toxicity Management of Infusion-
Reactions Related to Immunotherapy Treatment 
Infusion reactions are a well-documented AE associated with the administration of mAb. 
Infusion reactions typically develop within 30 minutes to 2 hours after initiation of drug 
infusion, although symptoms may be delayed for up to 48 hours. The incidence of 
infusion reactions varies by mAb agent, and there are multiple mechanisms known to 
lead to infusion-related reactions including both IgE-dependent anaphylactic and non-IgE 
dependent anaphylactoid hypersensitivities. Cytokine release syndrome, and when 
severe, cytokine “storm”, has been identified as a sequela of the immune system 
activation associated with infusion reactions. 
Infusion reactions may affect any organ system in the body; most are mild in severity, 
although severe and even fatal reactions occur. As a group, infusion reactions (including 
both cytokine-mediated and allergic) usually occur during or within a few hours of drug 
infusion. Occasionally, a reaction may occur 1 to 2 days after administration. The 
NCI-CTCAE (version 5.0) for grading adverse reactions during chemotherapy 
administration has a scale for grading the severity of infusion reactions and separate 
grading scales for allergic reactions and anaphylaxis. While use of these separate grading 
scales may be useful for classifying the nature of an infusion reaction for research 
purposes, they are less useful for clinical care, since it may not be obvious if the 
participant is having an allergic infusion reaction or a non-allergic infusion reaction.  
Clinically, an infusion reaction may present with flushing, itching, urticaria, and/or 
angioedema, repetitive cough, sudden nasal congestion, shortness of breath, chest 
tightness, wheeze, sensation of throat closure or choking, and/or change in voice quality, 
faintness, tachycardia (or less often bradycardia), hypotension, hypertension and/or loss 
of consciousness, nausea, vomiting, abdominal cramping, and/or diarrhea, sense of 
impending doom, tunnel vision, dizziness, and/or seizure, severe back, chest, and pelvic 
pain. Refer to Table 8 for dose modification and treatment guidance for immunotherapy 
infusion reactions. 
To better understand the underlying etiology of these events, serum tryptase, C-reactive 
protein (CRP), ferritin, and a cytokine panel should be drawn during the occurrence of an 
infusion reaction/CRS of any grade as outlined in Table 7. The serum tryptase, CRP and 
ferritin panels should be performed at the investigator’s designated local laboratory. The 
serum cytokine panel will be performed at a GSK designated laboratory. These data will 
aid in the classifying (albeit retrospectively) the etiology of the AE. 

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Table 7 
Infusion-Related Reaction Laboratory Panel 
Analyte 
Relationship to Adverse Event 
Serum tryptasea 
IgE-related infusion reaction 
(Allergic/anaphylaxis) [Schwartz, 2006] 
Serum CRPa 
Elevated in CRS [Lee, 2014] 
Serum ferritina 
Elevated in CRS [Lee, 2014] 
Serum cytokine panelb 
(IFNγ*^, TNFα*^, IL1, IL2*, IL4, I-6*^, 
IL8*, IL10*, IL12p70, and IL13) 
* Reported to be elevated in CRS [Lee, 
2014] 
^ Consistently reported as elevated in CRS 
[Lee, 2014] 
Abbreviations: CRP = C-reactive protein; CRS = Cytokine release syndrome; IFNγ = Interferon gamma; 
TNFα =Tumor necrosis factor alpha; IL = Interleukin.  
a. 
Performed by investigator designated local laboratory if available; otherwise performed by GSK 
designated laboratory. 
b. Performed by a GSK designated laboratory; note: in participants enrolled from China sites, only the 
analytes bolded and italicized will be tested. 
The guidelines provided in Table 8 are suggestions. Investigators and site staff may also 
follow their site standard operating procedures for the treatment of these events. 
Table 8 
Infusion Reaction Dose Modification and Treatment Guidelines 
NCI CTCAE Grade 
Treatment 
Premedication at Subsequent Dosing 
Grade 1 
Mild reaction; infusion 
interruption not 
indicated; intervention 
not indicated 
• 
Increase monitoring of vital 
signs as medically indicated 
until the participant is deemed 
medically stable in the opinion 
of the investigator. 
• 
None 
Grade 2 
Requires therapy or 
infusion interruption 
but responds promptly 
to symptomatic 
treatment (e.g., 
antihistamines, 
NSAIDs, narcotics, IV 
fluids); prophylactic 
medications indicated 
for ≤24 hrs. 
• 
Stop Infusion 
• 
Additional appropriate medical 
therapy may include but is not 
limited to: 
o 
IV fluids 
o 
Antihistamines 
o 
NSAIDs 
o 
Acetaminophen 
o 
Narcotics 
• 
Increase monitoring of vital 
signs as medically indicated 
until the participant is deemed 
medically stable in the opinion 
of the investigator 
• 
If symptoms resolve within 1 
hour of stopping drug infusion, 
the infusion may be restarted at 
50% of the original infusion 
rate (e.g. from 100 mL/hr to 50 
mL/hr). Otherwise dosing will 
be held until symptoms resolve 
and the participant should be 
premedicated for the next 
scheduled dose 
Participants who develop Grade 2 
toxicity despite adequate 
• 
Participant may be premedicated 
1.5hr (± 30 minutes) prior to 
infusion of study drugs with: 
o 
Diphenhydramine 50 mg po 
(or equivalent dose of 
antihistamine). 
o 
Acetaminophen 500-1000 mg 
po (or equivalent dose of 
analgesic). 

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NCI CTCAE Grade 
Treatment 
Premedication at Subsequent Dosing 
premedication should be 
permanently discontinued from 
further study treatment 
Grades 3 or Grade 4 
Grade 3: Prolonged 
(i.e., not rapidly 
responsive to 
symptomatic 
medication and/or 
brief interruption of 
infusion); recurrence 
of symptoms 
following initial 
improvement; 
hospitalization 
indicated for other 
clinical sequelae (e.g., 
renal impairment, 
pulmonary infiltrates) 
Grade 4: Life-
threatening; pressor or 
ventilatory support 
indicated 
• 
Stop Infusion 
• 
Additional appropriate medical 
therapy may include but is not 
limited to: 
o 
Epinephrine** 
o 
IV fluids 
o 
Antihistamines 
o 
NSAIDs 
o 
Acetaminophen 
o 
Narcotics 
o 
Oxygen 
o 
Pressors 
o 
Corticosteroids 
• 
Increase monitoring of vital 
signs as medically indicated 
until the participant is deemed 
medically stable in the opinion 
of the investigator 
• 
Hospitalization may be 
indicated. 
**In cases of anaphylaxis, 
epinephrine should be used 
immediately. 
Participant is permanently 
discontinued from further study 
treatment. 
• 
No subsequent dosing 
Note: Appropriate resuscitation equipment should be available at the bedside and a physician readily 
available during the period of drug administration. For further information, please refer to the Common 
Terminology Criteria for Adverse Events v5.0 (CTCAE) at http://ctep.cancer.gov 
Abbreviations: CTCAE=common terminology criteria for adverse events; hr=hour; IV=intravenous; 
mg=milligram; ml=millilitres; NSAID=nonsteroidal anti-inflammatory drug; po=per os [by mouth] 
6.6.3. 
Management of Chemotherapy-related Toxicities 
Refer to chemotherapy prescribing information/local label or standard practice guidelines 
for the management of chemotherapy-related AEs or potential safety-related issues; 
including resuming chemotherapy treatment and dose reductions following recovery of 
AE. If chemotherapy is being held due to a chemotherapy-related toxicity, treatment with 
GSK3359609/placebo and pembrolizumab may continue unless otherwise instructed 
(refer to Section 6.6.1). 
6.7. 
Intervention after the End of the Study 
Participants receiving study treatment at the time of the final analysis may continue to 
receive study treatment until treatment is discontinued as indicated in Section 7.1. At the 
time of the interim analysis or at final analyses (refer to Section 9.5), the IDMC may 
make a recommendation regarding the continuation of study treatment based on the 
outcome; this decision will be communicated to Investigators whereby subsequent 
communication to participants may be required. 

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Participants who permanently discontinue study treatment will not receive any additional 
treatment from GSK. The investigator is responsible for ensuring that consideration has 
been given to the post-study care based on the participant’s medical condition. Refer to 
SoA (Table 1) and Section 7.1 for details on the follow-up assessments required for 
participants who permanently discontinued study treatment. Refer to Section 6.5.2.1 on 
prohibited post-study therapies. 
 
7. 
DISCONTINUATION OF STUDY INTERVENTION AND 
PARTICIPANT DISCONTINUATION/WITHDRAWAL 
7.1. 
Discontinuation of Study Intervention 
Participants will receive study treatment for the duration indicated in Section 6.1 as 
applicable, unless one of the following events occurs earlier:  
• Disease progression 
• Death 
• Unacceptable toxicity (refer to Section 6.6 and subsections) 
• Pregnancy (refer to Section 8.3.5 for details) 
In addition, study treatment may be permanently discontinued for any of the following 
reasons: 
• Deviation(s) from the protocol or non-compliance with study requirements 
• Request of the participant or proxy (withdrawal of consent by participant or 
proxy) 
• Discretion of the investigator  
• Participant is lost to follow-up 
• Closure or termination of the study 
Participants who have disease progression by RECIST v1.1 may continue study treatment 
up to the protocol specified 35 cycles at the discretion of the Investigator to confirm 
progression as per iRECIST guidelines. Nevertheless, the consideration to continue study 
treatment should be balanced by clinical judgment as to whether the participant is 
clinically stable. Continuation on study treatment is contingent upon the following 
conditions: 
• 
Absence of clinical signs or symptoms indicating clinically significant disease 
progression 
• 
ECOG PS has not worsened, or worsening by no more than 1 point from 
baseline 
• 
Absence of rapid disease progression or threat to vital organs or critical 
anatomical sites (e.g., CNS metastasis, respiratory failure due to tumor 

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compression, or spinal cord compression) requiring urgent alternative medical 
intervention. 
• 
No significant, unacceptable, or irreversible toxicities related to study treatment. 
All participants who permanently discontinue study treatment for any reason (except 
consent withdrawn) will have safety assessments at the time of discontinuation and 
during follow-up as specified in the SoA. 
The primary reason study treatment was permanently discontinued must be documented 
in the participant’s medical records and eCRF. If the participant voluntarily discontinues 
from treatment due to toxicity, ‘adverse event (AE)’ will be recorded as the primary 
reason for permanent discontinuation on the eCRF. 
Once a participant has permanently discontinued from study treatment, the participant 
will not be allowed to be retreated. Refer to the SoA for assessments to be performed at 
the time study treatment is permanently discontinued and for evaluations that need to be 
completed. 
All participants who permanently discontinue study treatment without disease 
progression will be followed for progression according to the protocol-defined on-
treatment disease assessment schedule in the SoA until one or more of the following 
occur: 
• 
a new anticancer therapy is initiated  
• 
disease progression  
• 
death 
All participants who permanently discontinue study treatment for any reason, except 
withdrawal of consent (refer to Section 7.2) will be followed for survival every 12 weeks 
until death or until the last participant discontinues treatment and has had their last follow 
up for safety.  
The every 12-week schedule (refer to Table 1 SoA for details of frequency of all 
assessments during follow-up period) should begin once study treatment has been 
permanently discontinued. If participants are unable or unwilling to attend clinic visits 
during follow-up, contact to assess survival, may be made via another form of 
communication (e.g., telephone, email, etc.).  
7.1.1. 
Liver Chemistry Stopping Criteria 
Liver chemistry stopping, and increased monitoring criteria have been designed to 
assure participant safety and evaluate liver event etiology. 
Discontinuation of study intervention for abnormal liver tests is required when: 
• a participant meets one of the conditions outlined in Section 10.8 and Section 
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• when in the presence of abnormal liver chemistries not meeting protocol-specified 
stopping rules, the investigator believes study intervention discontinuation is in 
the best interest of the participant. 
7.1.2. 
Rechallenge 
7.1.2.1. 
Study Intervention Restart or Rechallenge after liver stopping criteria 
met 
If participant meets liver chemistry stopping criteria do not restart/rechallenge participant 
with study intervention unless: 
• 
GSK Medical Governance approval is granted 
• 
Ethics and/or IRB approval is obtained, if required, and 
• 
Separate consent for intervention restart/rechallenge is signed by the participant 
Refer to Section 10.8 and Section 10.8.1 for details. 
If GSK Medical Governance approval to restart/rechallenge participant with study 
intervention is not granted, then participant must permanently discontinue study 
intervention and may continue in the study for protocol-specified follow up assessments. 
7.2. 
Participant Discontinuation/Withdrawal from the Study 
• 
A participant may withdraw from the study at any time at his/her own request or 
may be withdrawn at any time at the discretion of the investigator for safety, 
behavioral, compliance or administrative reasons. This is expected to be 
uncommon. 
• 
At the time of discontinuing from the study, an early discontinuation visit should 
be conducted, as shown in the SoA. Refer to SoA (Table 1) for the assessments 
at the time of study discontinuation 
• 
The participant will be permanently discontinued both from the study 
intervention and from the study at that time. 
• 
If the participant withdraws consent for disclosure of future information, the 
sponsor may retain and continue to use any data collected before such a 
withdrawal of consent. 
• 
If a participant withdraws from the study, he/she may request destruction of any 
samples taken and not tested, and the investigator must document this in the site 
study records. 
7.3. 
Lost to Follow Up 
A participant will be considered lost to follow-up if he or she repeatedly fails to return for 
scheduled visits and is unable to be contacted by the study site.  
The following actions must be taken if a participant fails to return to the clinic for a 
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• 
The site must attempt to contact the participant and reschedule the missed visit 
as soon as possible and counsel the participant on the importance of maintaining 
the assigned visit schedule and ascertain whether or not the participant wishes to 
and/or should continue in the study. 
• 
Before a participant is deemed lost to follow up, the investigator or designee 
must make every effort to regain contact with the participant (where possible, 3 
telephone calls and, if necessary, a certified letter to the participant’s last known 
mailing address or local equivalent methods). These contact attempts should be 
documented in the participant’s medical record. 
• 
Should the participant continue to be unreachable, he/she will be considered to 
have withdrawn from the study. 
 
8. 
STUDY ASSESSMENTS AND PROCEDURES 
• 
Study procedures and their timing are summarized in the SoA.  
• 
Protocol waivers or exemptions are not allowed  
• 
Immediate safety concerns should be discussed with the sponsor immediately upon 
occurrence or awareness to determine if the participant should continue or 
discontinue study intervention. 
• 
Adherence to the study design requirements, including those specified in the SoA, is 
essential and required for study conduct. 
• 
All screening evaluations must be completed and reviewed to confirm that potential 
participants meet all eligibility criteria. The investigator will maintain a screening 
log or equivalent to record details of all participants screened and to confirm 
eligibility or record reasons for screening failure, as applicable.  
• 
Procedures conducted as part of the participant’s routine clinical management (e.g., 
blood count) and obtained before signing of ICF may be utilized for screening or 
baseline purposes provided the procedure met the protocol-specified criteria and was 
performed within the time frame defined in the SoA. 
• 
The maximum volume of blood collected from each participant from Screening 
through Week 21 of the study treatment phase is estimated not to exceed 180 mL 
• 
Note: Repeat or unscheduled blood samples may be taken for safety reasons 
or for technical issues with the samples; these estimates are not included in 
the calculated maximum 
Screening 
All screening assessments must be performed within 28 days prior to randomization 
unless otherwise specified. The ICF may be signed within 45 days prior to 

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randomization; archival tumor tissue collection or tumor tissue biopsy procedure can be 
performed as of 45 days prior to randomization after participant ICF obtained. 
The term ‘baseline’ refers to the assessment performed during the screening period prior 
to first dose of study treatment that serves as a comparison or control. For example, the 
baseline laboratory assessment is the laboratory assessment performed prior to first dose. 
Refer to SoA (Table 1) for additional details on assessments required at Screening and 
prior to start of study treatment. 
The following assessments are required during screening: 
• Demographic parameters such as year of birth and sex will be captured 
• Medical history including cardiovascular medical history, tobacco use, and other 
risk factors will be assessed as related to the inclusion/exclusion criteria 
• Disease characteristics including medical, surgical, and treatment history (best 
response to prior therapy [radiotherapy and systemic] will be recorded), date of 
initial diagnosis, primary tumor location, stage at initial diagnosis, histology, HPV 
status (if available, by the CINtec p16 histology assay; required in oropharyngeal 
cancers, refer to Table 1), tumor genetic/genomic features and current sites of 
disease will be taken as part of the disease history/status. 
• Tumor tissue sent to central laboratory (refer to Section 5.1, inclusion criterion 12 
for tissue requirements) for the following required screening assessments: 
o PD-L1 protein expression using the PD-L1 IHC 22C3 pharmDx assay by 
central laboratory testing; an evaluable CPS score is required for eligibility 
▪ If PD-L1 IHC testing by 22C3 pharmDx assay was performed for 
eligibility to Study 209229, retesting is not required provided result 
was evaluable for CPS 
NOTE: the PD-L1 IHC 22C3 pharmDx is US FDA approved and CE marked in 
the European Union (EU) 
o p16 IHC using the CINtec p16 histology assay for the assessment of HPV 
status (only required in oropharyngeal cancers and if results not available by 
local laboratory testing/prior testing) 
Baseline lesion assessments per RECIST v1.1 guideline [Eisenhauer, 2009] are required 
within 28 days randomization and include: 
• Computed tomography (CT) scan with contrast of the chest and abdomen (must 
include complete imaging of the liver 
o Note: Although a CT scan is preferred, magnetic resonance imaging (MRI) may 
be used as an alternative method of baseline disease assessment, especially for 
those participants where a CT scan is contraindicated due to allergy to contrast. 
The method used to document baseline status must be used consistently 
throughout disease assessment visits to facilitate direct comparison. Refer to 
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tomography (FDG-PET)/CT; this modality is permitted provided the CT portion 
is with contrast and is of diagnostic quality [Eisenhauer, 2009; Seymour, 2017]. 
• MRI/CT scan of head and neck region with IV gadolinium/contrast, respectively 
• MRI of brain with and without IV gadolinium (if clinically indicated) 
• Bone scan (if clinically indicated) 
• Clinical disease assessment for palpable/visible lesions 
• Other areas as indicated by the participant’s underlying disease present prior to 
screening 
Refer to Section 8.1 for baseline documentation of target and non-target lesions. 
Safety and laboratory assessments (refer to Section 8.2 and Section 8.2.6) required at 
baseline include: 
• 
Physical examination (refer to Section 8.2.1) 
• 
ECOG Performance Status (refer to Section 8.2.2) 
• 
Vital Signs (refer to Section 8.2.3) 
• 
Concomitant medication 
o Recorded starting from screening through post-study treatment follow-up.  
o Record all medications the participant is taking including prescription 
medications, over-the-counter drugs or preparations, and herbal 
preparations including any cannabinoids and/or recreational drugs used. 
o At a minimum, the drug name, route of administration, dose, and frequency 
of dosing, along with start and stop dates must be recorded. 
• 
Electrocardiogram (ECG; refer to Section 8.2.4) 
• 
Echocardiogram (ECHO; refer to Section 8.2.5) 
• 
Laboratory assessments (refer to Section 8.2.6). 
Follow-up assessments 
Participants who permanently discontinue study treatment for any reason, except 
withdrawal of consent (refer to Section 7.2) will be followed for survival every 12 weeks 
(14 days) until death. 
8.1. 
Efficacy Assessments 
RECIST version 1.1 guidelines will be used to determine the overall tumor burden at 
screening, select target and non-target lesions, and in the disease assessments through the 
duration of the study [Eisenhauer, 2009]. The primary measure of response-based 
efficacy endpoints is according to RECIST v1.1 definitions as assessed by the 
Investigator. Scans will be collected centrally; refer to Section 9.7 for details on response 
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Additionally, iRECIST guidelines may be used in the assessment of response/progression 
to account for the unique tumor kinetics observed with immunotherapeutic agents which 
may manifest as an increase in tumor burden then later is followed by regression 
suggesting the apparent observed neoplastic growth representing transient lymphocyte 
infiltration. Thus, participants with disease progression by RECIST version 1.1 
guidelines may have a confirmatory disease assessment no sooner than 4 weeks after the 
date disease progression was declared in order to confirm disease progression by 
iRECIST guidelines. Confirmatory scans may be done as per clinical standard of care and 
at the discretion of the investigator up to the protocol specified 35 cycles. The visit level 
responses and treatment-based decisions will incorporate iRECIST guidelines [Seymour, 
2017]. 
Refer to the SoA (Table 1) for the frequency of disease assessments post Screening. 
Imaging of the head/neck, chest and abdomen is required at each disease assessment visit 
and at confirmation of disease progression; the same modality used at Screening must 
remain consistent throughout the study duration. Other imaging modalities and regions 
assessed at Screening and required to measure/evaluate the target and nontarget lesions 
are required at each visit and for confirmation of disease progression. 
A random BICR audit will be performed at the time of the primary PFS analysis. 
Participant BICR randomization designation will not be known to the investigators; refer 
to Section 9.7 for details. 
All imaging scans and clinical assessments (i.e., photographs) performed at Screening 
and at each disease assessment visit, including unscheduled assessment visits, are 
required to be uploaded at each visit occurrence for BICR. Refer to the imaging manual 
for details on imaging/clinical assessment requirements and submission guidelines. 
8.1.1. 
Disease Assessments 
• 
RECIST version 1.1 guidelines will be used to determine the overall tumor burden at 
screening, select target and non-target lesions, and in the disease assessments 
through the duration of the study [Eisenhauer, 2009]. 
• 
As indicated in RECIST version 1.1 guidelines: 
• 
Lymph nodes that have a short axis of <10 mm are considered non-pathological 
and must not be recorded or followed. 
• 
Pathological lymph nodes with <15 mm but 10 mm short axis are considered 
non-measurable. 
• 
Pathological lymph nodes with 15 mm short axis are considered measurable and 
can be selected as target lesions; however, lymph nodes should not be selected as 
target lesions when other suitable target lesions are available. 
• 
Measurable lesions up to a maximum of two lesions per organ and 5 lesions in 
total, representative of all involved organs, should be identified as target lesions, 
and recorded and measured at baseline. These lesions should be selected based on 
their size (lesions with the longest diameter) and their suitability for accurate 
repeated measurements (either by imaging techniques or clinically). 

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Note: Cystic lesions thought to represent cystic metastases must not be selected as target 
lesions when other suitable target lesions are available. 
Note: Measurable lesions that have been previously irradiated and have not been shown 
to be progressing following irradiation must not be considered as target lesions. 
• 
Lytic bone lesions or mixed lytic-blastic lesions, with identifiable soft tissue 
components, that can be evaluated by CT or MRI can be considered measurable. 
Bone scans, FDG-PET scans or X-rays are not considered adequate imaging 
techniques to measure bone lesions. 
• 
All other lesions (or sites of disease) must be identified as non-target and must 
also be recorded at baseline. Non-target lesions will be grouped by organ. 
Measurements of these lesions are not required, but the presence or absence of 
each must be noted throughout follow-up. 
• 
Disease assessment modalities may include imaging (e.g., CT scan, MRI, bone scan) 
and physical examination (as indicated for palpable/superficial lesions). 
• 
At each post-baseline assessment, evaluation of the sites of disease (all target and 
non-target lesions) identified by the baseline scans is required. CT scans with 
contrast of the chest, and abdomen, or if contra-indicated, MRI, is required at each 
post-baseline assessment. To ensure comparability between the baseline and 
subsequent assessments, the same method of assessment and the same technique will 
be used when assessing response. 
• 
Refer to the SoA for the frequency of disease assessment. Assessments must be 
performed on a calendar schedule and should not be affected by dose 
interruptions/delays. 
• 
Participants whose disease responds (either CR or PR) may have a confirmatory 
disease assessment performed at least 4 weeks after the date of assessment during 
which the response was demonstrated. More frequent disease assessments may be 
performed at the discretion of the investigator. . 
8.2. 
Safety Assessments 
Planned time points for all safety assessments are provided in the SoA. 
8.2.1. 
Physical Examinations 
• A complete physical examination performed at Screening will include, at a 
minimum, assessment of the cardiovascular, respiratory, gastrointestinal, and 
neurological systems.  
• A brief physical examination performed at each subsequent visit will include, at a 
minimum, assessments of the skin, lungs, cardiovascular system, and abdomen 
(liver and spleen).  
• Investigators should pay special attention to clinical signs related to previous 
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8.2.2. 
Performance Status 
Performance status will be assessed using the ECOG scale at each visit; refer to Section 
10.5. 
8.2.3. 
Vital Signs 
• Vital signs will be measured after 5 minutes of rest and will include temperature, 
systolic and diastolic blood pressure, pulse rate, respiratory rate, and oxygen 
saturation (measured by pulse oximetry). Blood pressure should be taken in the 
same position throughout the study and captured in the eCRF. 
• Vital signs will be measured more frequently if warranted by clinical condition 
of the participant. 
• If a participant develops fever and infusion related reaction or cytokine release 
syndrome is suspected, refer to management guidelines (Section 6.6.2). 
• Height will be recorded at Screening only. 
• Weight will be measured and recorded (in kilograms) at baseline and at every 
treatment visit. 
8.2.4. 
Electrocardiograms 
A 12-lead ECG will be performed at Screening as indicated in the SoA using an ECG 
machine that calculates the heart rate and measures PR, QRS, and QT intervals. The QT 
interval corrected for heart rate or RR interval using Fridericia’s formula may be by 
machine or manual calculation. ECG after Screening will be performed as clinically 
indicated. 
8.2.5. 
Echocardiograms 
Echocardiogram will be performed at Screening to assess cardiac ejection fraction for the 
purpose of study eligibility, as specified in the SoA and Section 5.1. Additional ECHO 
assessments may be performed if clinically warranted. MUGA can be used in lieu of 
ECHO (if not available) in the assessment of LVEF; the same modality should be used in 
any subsequent assessments. 
8.2.6. 
Clinical Safety Laboratory Assessments 
• 
Refer to Appendix 2 for the list of clinical laboratory tests to be performed and 
to the SoA for the timing and frequency. The clinical laboratory tests will be 
performed by local laboratory unless otherwise indicated. 
• 
The investigator must review the laboratory report, document this review, and 
record any clinically relevant changes occurring during the study in the AE 
section of the CRF. The laboratory reports must be filed with the source 
documents. Clinically significant abnormal laboratory findings are those which 
are not associated with the underlying disease, unless judged by the investigator 
to be more severe than expected for the participant's condition. 

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• 
All laboratory tests with values considered clinically significantly abnormal 
during participation in the study or within 30 days after the last dose of study 
intervention should be repeated until the values return to normal or baseline or 
are no longer considered significantly abnormal by the investigator or medical 
monitor.  
• 
If such values do not return to normal/baseline within a period of time judged 
reasonable by the investigator, the etiology should be identified and the sponsor 
notified. 
• 
All protocol-required laboratory assessments, as defined in Appendix 2, must be 
conducted in accordance with the laboratory manual and the SoA. 
8.3. 
Adverse Events and Serious Adverse Events 
The definitions of an AE or SAE can be found in Appendix 3. 
The investigator and any qualified designees are responsible for detecting, documenting, 
and reporting events that meet the definition of an AE or SAE and remain responsible for 
following up AEs that are serious, considered related to the study intervention or the 
study, or that caused the participant to discontinue the study intervention (Refer to 
Section 7).  
All AEs are to be graded according to NCI-CTCAE (version 5.0) [NCI, 2017]. 
8.3.1. 
Time Period and Frequency for Collecting AE and SAE 
Information 
• All AESIs and SAEs will be collected from the start of treatment until 90 days 
after the last dose of study treatment at the time points specified in the SoA (refer 
to Appendix 3 for details on SAEs). However, any SAEs assessed as related to 
study participation (e.g., study treatment, protocol-mandated procedures, invasive 
tests, or change in existing therapy) OR in countries where collection of SAEs 
regardless of causality is required to be recorded once the participant signs the 
informed consent form, SAEs will be recorded from the time a participant 
consents to participate in the study (i.e., signs the informed consent). 
o If subsequent anti-cancer treatment is initiated during the 90-day 
follow-up period yet <30 days after the date study treatment was 
discontinued, AESI ad SAEs must continue to be collected until 30 
days after last dose of study treatment. 
• All AEs will be collected from the start of study treatment until 30 days after the 
last dose of study treatment at the time points specified in the SoA (Table 1). 
• Medical occurrences that begin before the start of study treatment but after 
obtaining informed consent will be recorded in the Medical History/Current 
Medical Conditions section of the CRF and not in the AE section. 
• All SAEs will be recorded and reported to the Sponsor or designee immediately 
and under no circumstance should this exceed 24 hours. The investigator will 

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submit any updated SAE data to the Sponsor within 24 hours of learning of the 
event. 
• Investigators are not obligated to actively seek AEs or SAEs in former study 
participants. However, if the investigator learns of any SAE, including a death, at 
any time after a participant has been discharged from the study, and he/she 
considers the event to be reasonably related to the study treatment or study 
participation, the investigator must promptly notify the Sponsor. 
8.3.2. 
Method of Detecting AEs and SAEs 
• 
The method of recording, evaluating, and assessing causality of AEs and SAEs 
and the procedures for completing and transmitting SAE reports are provided in 
Appendix 3. 
• 
Care will be taken not to introduce bias when detecting AE and/or SAE. Open-
ended and non-leading verbal questioning of the participant is the preferred 
method to inquire about AE occurrence.  
8.3.3. 
Follow-up of AEs and SAEs 
After the initial AE/SAE report, the investigator is required to proactively follow each 
participant at subsequent visits/contacts. All SAEs and non-serious AESIs will be 
followed until events are resolved, stabilized, otherwise explained, or the participant is 
lost to follow-up as defined in Section 7.3. Further information on follow-up procedures 
is given in Appendix 3. 
8.3.4. 
Regulatory Reporting Requirements for SAEs 
• 
Prompt notification by the investigator to the sponsor of a SAE is essential so 
that legal obligations and ethical responsibilities towards the safety of 
participants and the safety of a study intervention under clinical investigation are 
met.  
• 
The sponsor has a legal responsibility to notify both the local regulatory 
authority and other regulatory agencies about the safety of a study intervention 
under clinical investigation. The sponsor will comply with country-specific 
regulatory requirements relating to safety reporting to the regulatory authority, 
Institutional Review Boards (IRB)/Independent Ethics Committees (IEC), and 
investigators. 
• 
For all studies except those utilizing medical devices investigator safety reports 
must be prepared for suspected unexpected serious adverse reactions (SUSAR) 
according to local regulatory requirements and sponsor policy and forwarded to 
investigators as necessary. 
• 
An investigator who receives an investigator safety report describing a SAE or 
other specific safety information (e.g., summary or listing of SAEs) from the 
sponsor will review and then file it along with the Investigator’s Brochure and 
will notify the IRB/IEC, if appropriate according to local requirements. 

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8.3.5. 
Pregnancy 
• 
Details of all pregnancies in female participants and female partners of male 
participants will be collected after the start of study treatment and until 120 days 
after the last dose of study treatment. 
• 
If a pregnancy is reported, the investigator should inform GSK within 24 hours of 
learning of the pregnancy. 
• 
Abnormal pregnancy outcomes (e.g., spontaneous abortion, fetal death, stillbirth, 
congenital anomalies, ectopic pregnancy) are considered SAE. 
8.3.6. 
Cardiovascular and Death Events 
For any cardiovascular events detailed in Section 10.3.3 and all deaths, whether or not 
they are considered SAEs, specific Cardiovascular (CV) and Death sections of the CRF 
will be required to be completed. These sections include questions regarding 
cardiovascular (including sudden cardiac death) and non-cardiovascular death. 
The CV CRFs are presented as queries in response to reporting of certain CV MedDRA 
terms. The CV information should be recorded in the specific cardiovascular section of 
the CRF within one week of receipt of a CV Event data query prompting its completion.  
The Death CRF is provided immediately after the occurrence or outcome of death is 
reported. Initial and follow-up reports regarding death must be completed within one 
week of when the death is reported. 
8.3.7. 
Events of Clinical Interest 
Selected events that may be non-serious or serious adverse events and are considered as 
Events of Clinical Interest (ECI) in this study protocol and must be reported to the 
Sponsor. 
Events of clinical interest include: 
1. An overdose of Study Treatment (GSK3359609/Pembrolizumab), as defined in 
Section 8.4 that is not associated with clinical symptoms or abnormal laboratory 
results. 
2. An elevated AST (aspartate aminotransferase) or ALT (alanine aminotransferase) 
lab value that is greater than or equal to 3X the upper limit of normal and an 
elevated total bilirubin lab value that is greater than or equal to 2X the upper limit 
of normal and, at the same time, an alkaline phosphatase lab value that is less than 
2X the upper limit of normal, as determined by way of protocol-specified 
laboratory testing or unscheduled laboratory testing.* 
*Note: These criteria are based upon available regulatory guidance documents. The 
purpose of the criteria is to specify a threshold of abnormal hepatic tests that may require 
an additional evaluation for an underlying etiology. The study site guidance for 
assessment and follow up of these criteria can be made available. It may also be 
appropriate to conduct additional evaluation for an underlying etiology in the setting of 
abnormalities of liver blood tests including AST, ALT, bilirubin, and alkaline 

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phosphatase that do not meet the criteria noted above. In these cases, the decision to 
proceed with additional evaluation will be made through consultation between the study 
investigators and the GSK Medical Monitor. However, abnormalities of liver blood tests 
that do not meet the criteria noted above are not ECIs for this study. 
8.4. 
Treatment of Overdose 
In the event there is an overdose of GSK3359609, pembrolizumab and/or chemotherapy 
the investigator must: 
1. Contact the Medical Monitor immediately. 
2. Closely monitor the participant for AEs/SAEs and laboratory abnormalities for at 
least 130 days. 
3.  Obtain a PK analysis within 28 days from the date of the last dose of study treatment 
if requested by the Medical Monitor (determined on a case-by-case basis) 
4. Document the quantity of the excess dose as well as the duration of the overdosing in 
the eCRF. 
An overdose event that is not associated with clinical symptoms or abnormal laboratory 
results is defined as an ECI; refer to Section 8.3.7 for details on the expedited reporting 
requirements for ECI. 
Decisions regarding dose interruptions or modifications will be made by the investigator 
in consultation with the Medical Monitor based on the clinical evaluation of the 
participant. 
8.4.1. 
GSK3359609 
An overdose of GSK3359609 is defined as administration of a dose that is >240 mg (>10 
times the 24 mg intended dose). There is no specific antidote for overdose with 
GSK3359609. In the event of a suspected overdose, it is recommended that the 
appropriate supportive clinical care be instituted as dictated by the participant’s clinical 
status. 
8.4.2. 
Pembrolizumab 
An overdose of pembrolizumab is defined as ≥1000 mg (5 times the dose) of 
pembrolizumab. In the event of a suspected overdose, it is recommended that the 
appropriate supportive clinical care be instituted as dictated by the participant’s clinical 
status. 
8.4.3. 
Chemotherapy 
Refer to the respective chemotherapy prescribing information/summary of primary 
characteristics information for management of participants in the event of chemotherapy 
overdosage. 

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8.5. 
Pharmacokinetics 
• Plasma samples will be collected for measurement of GSK3359609 concentrations at 
the timepoints specified in the SoA. Refer to the Q2 laboratory manual for 
instructions on the collection and handling of the plasma samples. The actual date and 
time (24-hour clock time) of each sample will be recorded. 
• Samples will be used to evaluate the PK of GSK3359609. Samples collected for 
analyses of GSK3359609 plasma concentration may also be used to evaluate safety or 
efficacy aspects related to concerns arising during or after the study. 
Drug concentration information that would unblind the study will not be reported to 
investigative sites or blinded personnel until the study has been unblinded. If appropriate, 
de-identified drug concentration information may be analysed prior to study unblinding. 
In that case, GSK Clinical Pharmacology Modelling Simulation analysts will have access 
to a blinded population PK dataset (including, but not limited to, concentration, actual 
dosing information, demographics, and some vital sign and laboratory information, but 
excluding adverse event and efficacy information) at several time points (e.g., prior to 
each interim analysis) throughout the trial for population PK model 
development/refinement. 
8.6. 
Pharmacodynamics 
Pharmacodynamic parameters are not evaluated in this study. 
8.7. 
Genetics 
Refer to Section 10.7 for information regarding genetics research. 
A blood sample for deoxyribonucleic acid (DNA) isolation will be collected from 
participants who have consented to participate in the genetics analysis component of the 
study. Participation is optional. Participants who do not wish to participate in the genetic 
research may still participate in the study. 
In the event of DNA extraction failure, a replacement genetic blood sample may be 
requested from the participant. Signed informed consent will be required to obtain a 
replacement sample unless it was included in the original consent. 
Details on blood volume collected, the processes for collection, shipment and destruction 
of these samples can be found in Q2 laboratory manual. 
8.8. 
Biomarkers 
• 
Collection of samples for biomarker research is also part of this study. The following 
samples for biomarker research are required and will be collected from all 
participants in this study as specified in the SoA: 
• Whole blood for peripheral blood mononuclear cell (PBMC) isolation. The 
PBMC may be used for biomarker assays including but not limited to TCR 
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• Plasma at baseline and on-treatment timepoints specified in the SoA. The 
sample may be used to extract and analyze cell-free DNA (cfDNA) and/or cell-
free ribonucleic acid (cfRNA) as well as other soluble factors and proteins. 
• Archival tumor tissue (refer to Section 8.8.3): tumor tissue acquired within 2 
years prior to randomization is required otherwise fresh tumor biopsy 
performed at Screening will be required. 
• 
Optional samples for biomarker research to be obtained from participants at the 
following timepoints: 
• Tumor biopsy at Screening in those participants providing archival tissue 
(i.e., archival tumor tissue meets the protocol defined time requirements) 
• Tumor tissue biopsy during the treatment period in participants with a 
mixed tumor response and/or disease progression.  
• Tumor tissue biopsy at the completion of 35 cycles  of study treatment 
• 
Samples may be tested for ICOS expression, germline and/or somatic mutations 
including and tumor mutation burden, gene expression, TCR sequences and/ or 
any other DNA, RNA or protein-based biomarker that may emerge from other 
studies using the test drugs, to evaluate their association with the efficacy 
endpoints to the study treatments. 
• 
In addition, with the participant’s consent, samples will be stored, and analysis 
may be performed on biomarker variants thought to play a role in the 
mechanism of action, sensitivity or resistance or could support future 
combinations. Analyses may include associations of biomarker variants with 
efficacy endpoints.  
Furthermore, the samples and any biomarker data generated may be used to support the 
development and filing of a diagnostic. 
Samples may be stored for a maximum of 15 years (or according to local regulations) 
following the last participant’s last visit for the study at a facility selected by the sponsor 
to enable further analysis of biomarker responses to study intervention. 
8.8.1. 
RNA Research 
Transcriptome studies will be conducted using either next generation sequencing (NGS) 
based technologies, targeted probe set and/or alternative equivalent technologies, which 
facilitates the simultaneous measurement of the relative abundances of thousands of 
ribonucleic acid (RNA) species resulting in a transcriptome profile for each blood and/ or 
tumor sample. This will enable the evaluation of baseline transcriptome profiles or any 
changes upon treatment with the study drugs that may correlate with response to the 
chemotherapy combinations of Pembrolizumab  GSK3359609. This may include tumor 
and/or immune cells from blood as well as from tumor tissues. 
RNA expression studies may be conducted using quantitative reverse transcriptase 
polymerase chain reaction (RT-qPCR), and/or alternative equivalent technologies, which 
can facilitate the simultaneous measurement of the relative abundances of RNA species 

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resulting in an RNA expression profile for each blood and/or tumor tissue samples. The 
RNAs assayed may be those involved with the pathogenesis of HNSCC; the biology of 
ICOS-ICOSL or PD-1-PD-L1 signalling pathways and may help identify responder 
populations to the combination of GSK3359609, pembrolizumab and chemotherapy or 
pembrolizumab and chemotherapy. The RNAs that code for these proteins and/or 
regulatory RNAs may also be studied. 
The same samples may also be used to confirm findings using the application of 
alternative technologies. 
8.8.2. 
DNA Research 
DNA analysis using either whole exome and/or targeted sequencing of circulating tumor 
DNA from plasma and/or tumor will be performed. T-cell repertoire analysis for clonality 
and diversity of TCRs at baseline and on treatment may also be evaluated. 
8.8.3. 
Tumor Tissue 
All participants will provide archival tumor tissue or if not available or evaluable for 
screening assessments (refer to Section 5.1 inclusion 12 and SoA [Table 1]) then a fresh 
pre-treatment biopsy. Fresh biopsy will be optional at Screening for those participants 
providing archival tissue. The tumor tissue collected (archival or fresh biopsy material) 
will be evaluated by methods that include PD-L1 IHC testing using the US FDA 
approved and CE marked EU PD-L1 IHC 22C3 pharmDx assay; other IHC tests and may 
include multiplex immunofluorescence technologies or other methods for evaluating the 
expression of phenotypic and functional immune cell markers on tumor infiltrating 
lymphocytes (TIL) and other immune cells as well as markers on tumor cells. 
Additionally, tumor tissue may undergo DNA/RNA-based genetic/genomic profiling 
(i.e., tumor mutation burden, T-cell receptor diversity) which may include sequencing 
technologies that provide DNA/RNA sequence information. In addition, when possible, 
similar analyses will be performed on tumor tissue obtained during treatment and upon 
progression. These samples may also be evaluated for predictive measures of efficacy; if 
a predictive biomarker is identified, these tissues may be used for the development of a 
diagnostic test. 
8.8.4. 
Blood Samples 
Plasma and/or serum samples are collected at baseline, during treatment and at disease 
progression to evaluate soluble factors such as cytokines, chemokines and other secreted 
proteins as well as cfDNA/cfRNA. 
PBMC samples will be collected at baseline, during treatment and at disease progression 
and may be used for evaluating the expression of phenotypic and functional immune cell 
markers as well as for evaluating the polyfunctionality of immune cells and to test any 
novel biology emerging from other ICOS studies. 
Other biomarkers may be evaluated as determined by additional data. Details for the 
samples collection, processing, storage and shipment will be provided in the SRM and 
Q2 laboratory manual. 

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8.9. 
Immunogenicity Assessments 
Antibodies to GSK3359609 will be evaluated in serum samples collected from all 
participants according to the SoA. Additionally, serum samples should also be collected 
at the final visit from participants who discontinued study intervention or were withdrawn 
from the study. These samples will be tested by the sponsor or sponsor's designee. 
Serum samples will be screened for antibodies binding to GSK3359609 and the titer of 
confirmed positive samples will be reported. Other analyses may be performed to verify 
the stability of antibodies to GSK3359609 and/or further characterize the 
immunogenicity of GSK3359609. 
The detection and characterization of antibodies to GSK3359609 will be performed using 
a validated assay method by or under the supervision of the sponsor. All samples 
collected for detection of antibodies to study intervention will also be evaluated for 
GSK3359609 concentration to enable interpretation of the antibody data. Antibodies may 
be further characterized and/or evaluated for their ability to neutralize the activity of 
GSK3359609. 
8.10. 
Medical Resource Utilization and Health Economics 
Healthcare resource utilization (HCRU) will be collected for all participants randomized 
to study treatment and may be used to conduct exploratory economic analyses. HCRU 
includes non-protocol healthcare encounters, such as provider visits, emergency room 
visits, hospitalizations (including ward, admission and discharge dates, and primary 
discharge diagnosis), medications, tests, or procedures. 
8.11. 
Patient Reported Outcomes 
The below questionnaires to assess patient-reported symptoms, functioning, and 
treatment tolerability during the study will be administered at the time-points indicated in 
SoA (Table 1). The questionnaires will be administered to participants in different 
regions based on the availability of translated versions; further details on the participant 
questionnaires can be found in the SRM. 
PRO 
Concepts 
EORTC IL50 
Select domains of the EORTC-QLQ-C30 general cancer 
module  
EORTC IL51 
Select domains of the EORTC QLQ-H&N35 cancer 
specific symptom module 
BPI-SF I3 
Pain severity 
PROMIS-SF PF 8c 
Physical function 
PGIS/PGIC 
Patient global impression of severity/change 
EQ-5D-3L 
HRQoL, for utility assessments 
FACT-GP5 
Overall toxicity burden 

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8.11.1. 
EORTC Item Library 50 and 51: Select Domains from the EORTC 
QLQ-C30 and EORTC QLQ-HN35 
The European Organization for Research and Treatment of Cancer Quality of Life 
Questionnaire 30-item Core module (EORTC QLQ-C30) is the core module designed to 
cover a broad range of cancer patients and is intended to be supplemented with disease-
specific sub-scales as necessary to assess QoL aspects particular to a given type of cancer 
and to improve the specificity and sensitivity of measurement [Sprangers, 1993; 
Aaronson, 1993]. Select domains from the EORTC QLQ-C30 will be administered and 
will be referred to as the EORTC IL50. 
The 35-Item Head and Neck Module (EORTC QLQ-H&N35) is a head and neck specific 
module with multi-item scales [Bjordal, 1994]. The mouth pain, swallowing, speech 
problems, opening mouth, coughing, feeding tube, and trouble with social eating domains 
will be administered and referred to as the EORTC IL51. 
8.11.2. 
Brief Pain Inventory Short-Form- Item 3 (BPI-SF I3) 
The Brief Pain Inventory Short Form was designed to assess pain and its impact in 
cancer. Item 3 measures ‘pain at its worst’ in the last 24 hours using a numerical rating 
scale of 0 
) to 10 (
 scale [Cleeland, 1994]. 
8.11.3. 
The Patient-Reported Outcomes Measurement Information 
System- Short Form Physical Function- 8 item (PROMIS SF PF 
8c) 
The Patient-Reported Outcomes Measurement Information System (PROMIS) is a 
universally applicable set of instruments measuring patient-reported health across 
different patient populations developed by the US National Institutes for Health (NIH) 
[Cella, 2007]. The PROMIS-SF PF assesses physical function and measures self-reported 
capability rather than actual performance of physical activities. This includes the 
functioning of one’s upper extremities (dexterity), lower extremities (walking or 
mobility), and central regions (neck, back), as well as instrumental activities of daily 
living, such as running errands. 
8.11.4. 
Patient Global Impression Items (PGIS and PGIC) 
The Patient Global Impression of Severity (PGIS) assesses global impression of 
symptoms severity at baseline and subsequent timepoints. The second question, the 
Patient Global Impression of Change (PGIC) serves to rate the global change in 
symptoms at subsequent time points. In addition to evaluating symptom severity and 
change, these questions serve as anchors to establish thresholds of clinically meaningful 
change for the questionnaires in the study [Guy, 1976]. 
8.11.5. 
Euroqol Questionnaire (EQ-5D-3L) 
The EQ-5D-3L is a standardized instrument for use as a measure of health utility. It is 
designed for self-completion or interview administration and is cognitively simple, taking 
only a few minutes to complete. 
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The EQ-5D-3L self-assessment questionnaire has 2 parts. The first part consists of 5 
items covering 5 dimensions (mobility, self-care, usual activities, pain/discomfort, and 
anxiety/depression). Each dimension is measured by a 3-point Likert scale (no problems, 
some or moderate problems, and unable or extreme problems). Respondents are asked to 
choose one level that reflects their "own health state today" for each of the 5 dimensions. 
Respondents can be then classified into one of 243 distinct health states. The second part 
is a 20-cm visual analogue scale (EQ-VAS) that has endpoints labelled "best imaginable 
health state" and "worst imaginable health state" anchored at 100 and 0, respectively. 
Respondents are asked to indicate how they rate their own health by drawing a line from 
an anchor box to that point on the EQ-VAS which best represents their own health on that 
day. EQ-5D-3L health states are converted to a single summary index by applying a 
formula that essentially attaches weights to each of the levels in each dimension. The 
formula is based on the valuation of EQ-5D health states from general population 
samples. 
8.11.6. 
Functional Assessment of Cancer Therapy – General Population 
(FACT-GP5) 
The FACT-G (now in Version 4) is a 27-item compilation of general questions divided 
into 4 primary QoL domains: Physical Well-Being, Social/Family Well-Being, Emotional 
Well-Being, and Functional Well-Being [Cella, 1993]. It is considered appropriate for use 
with participants with any form of cancer and has also been used and validated in other 
chronic illness condition (e.g., HIV/AIDS and multiple sclerosis) and in the general 
population (using a slightly modified version). 
The FACT-G scale has been developed and validated [Cella, 1993] and is widely used to 
measure HRQoL in patients with a broad range of cancer diagnoses [Lee, 2004]. The 
FACT GP5 item is a single item from the FACT-G, which assesses how bothersome the 
side effects of treatment are for cancer patients. The recall period is the past 7 days, and 
the item has a 5-category response scale ranging from “0=
 to “4=
. 
This item is being included to assess the overall tolerability of treatment from the 
participant’s perspective. 
 
9. 
STATISTICAL CONSIDERATIONS 
The study is considered to have met the study primary objective if GSK3359609 in 
combination with pembrolizumab and platinum-based chemotherapy is superior to the 
placebo in combination with pembrolizumab and platinum-based chemotherapy for either 
OS or PFS in the total population. 
9.1. 
Statistical Hypotheses 
9.1.1. 
Primary Hypotheses 
The following primary hypotheses will be tested: 
 
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Overall Survival 
• Hypotheses (H1): GSK3359609 in combination with pembrolizumab + 
5FU/platinum-based chemotherapy prolongs OS compared with placebo in 
combination with pembrolizumab + 5FU/platinum-based chemotherapy in all 
participants with R/M HNSCC (total population). 
• Hypotheses (H2): GSK3359609 in combination with pembrolizumab + 
5FU/platinum-based chemotherapy prolongs OS compared with placebo in 
combination with pembrolizumab + 5FU/platinum-based chemotherapy in 
participants with PD-L1 CPS1 R/M HNSCC. 
Progression-free Survival 
• Hypotheses (H3): GSK3359609 in combination with pembrolizumab + 
5FU/platinum-based chemotherapy prolongs PFS per RECIST v1.1 by 
investigator assessment compared with placebo in combination with 
pembrolizumab + 5FU/platinum-based chemotherapy in all participants with R/M 
HNSCC (total population). 
9.1.2. 
Key Secondary Hypotheses 
Progression-free Survival 
• Hypotheses (H4): GSK3359609 in combination with pembrolizumab + 
5FU/platinum-based chemotherapy prolongs PFS per RECIST v1.1 by 
investigator assessment compared with placebo in combination with 
pembrolizumab + 5FU/platinum-based chemotherapy in participants with PD-L1 
CPS1 R/M HNSCC. 
Time to Deterioration (TTD) in Pain 
• Hypothesis (H5): GSK3359609 in combination with pembrolizumab 
+ 5FU/platinum-based chemotherapy prolongs TTD in Pain (measured by 
EORTC QLQ H&N 35 pain domain) compared with placebo in combination with 
pembrolizumab + 5FU/platinum-based chemotherapy in all participants with R/M 
HNSCC (total population). 
• Hypothesis (H6): GSK3359609 in combination with pembrolizumab 
+ 5FU/platinum-based chemotherapy prolongs TTD in Pain (measured by 
EORTC QLQ H&N 35 pain domain) compared with placebo in combination with 
pembrolizumab + 5FU/platinum-based chemotherapy in participants with PD-L1 
CPS1 R/M HNSCC. 
TTD in Physical Function 
• 
Hypothesis (H7): GSK3359609 in combination with pembrolizumab + 
5FU/platinum-based chemotherapy prolongs TTD in Physical Function (measured 
by PROMIS PF 8c) compared with placebo in combination with pembrolizumab 

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+ 5FU/platinum-based chemotherapy in all participants with R/M HNSCC (total 
population). 
• 
Hypothesis (H8): GSK3359609 in combination with pembrolizumab + 
5FU/platinum-based chemotherapy prolongs TTD in Physical Function (measured 
by PROMIS PF 8c) compared with placebo in combination with pembrolizumab 
+ 5FU/platinum-based chemotherapy in participants with PD-L1 CPS1 R/M 
HNSCC. 
All other secondary endpoints will be summarized descriptively. 
9.2. 
Sample Size Determination 
The adaptive Phase II/III study design allows the study to be a Phase II/III or  Phase III 
study, subject to the outcome of the efficacy analysis at the adaptive decision points 
The first adaptive decision point that informs on Study 209227 design results from Study 
209229, which are data external from Study 209227. The timing of the analysis for 
adaptive decision in Study 209229 will occur when approximately 100 PD-L1 CPS 1 
participants have a minimum follow-up of 6 months and will be conducted using 
ORR/DCR per RECIST v1.1 based on investigator assessment. The adaptive decision 
criteria are defined positive if there is at least an 8% improvement of ORR in the 
GSK3359609 in combination with pembrolizumab arm compared with the 
pembrolizumab/placebo arm in the PD-L1 CPS 1 population of Study 209229 
[GlaxoSmithKline Document Number 2019N403389_03]. 
• If the analysis for the adaptive decision in Study 209229 (INDUCE-3; 
NCT04128696) is positive (∆ORR 8%), then Study 209227 will become a Phase 
III study that includes no pause in enrollment. 
• If the analysis for the adaptive decision in Study 209229 is to remain as a Phase II 
study (0% ∆ORR<8% , or ∆ORR<0% and ∆DCR>0%), then Study 209227 will 
be a Phase II/III adaptive study and the sample size will depend upon the outcome 
of the interim OS analysis within Study 209227; refer to Section 9.2.2 and Section 
9.5 for details. 
• If the analysis for the adaptive decision in Study 209229 is to stop for futility 
(∆ORR<0% and ∆DCR<0%) then Study 209227 may stop. 
Should a Phase II/III study be decided, then the Study 209227 will randomize 
approximately 300 participants with a 1:1 ratio between the GSK3359609 in combination 
with pembrolizumab plus platinum-based chemotherapy arm and the placebo in 
combination with pembrolizumab plus platinum-based chemotherapy arm. Assuming the 
aforementioned prevalence rate of PD-L1 CPS status, a sample size of 300 participants 
will approximately provide 129 PD-L1 CPS 20 participants, 126 PD-L1 1≤CPS<20 
participants and 45 PD-L1 CPS <1 participants. 
Should a Phase III study be decided, the study will randomize approximately 640 
participants with a 1:1 ratio between the GSK3359609 in combination with 
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with pembrolizumab and platinum-based chemotherapy arm.  A sample size of 640 
participants will approximately provide 275 PD-L1 CPS 20 participants, 269 PD-L1 
1≤CPS<20 participants and 96 PD-L1 CPS <1 participants.  
The sample size calculation is driven by survival events. There will be two interim 
analyses of OS and no interim analyses of PFS. The family-wise type I error rate for the 
primary hypotheses on PFS and OS is strongly controlled at 2.5% (one-sided). The 
strategy to address multiplicity issues with regards to multiple efficacy endpoints and 
interim analyses are described in Section 9.8 and Section 9.5.  
The sample size, power calculations, and simulations were performed in the software 
EAST 6.4 and R version 3.6.2 (package “gsDesign”). 
The study is considered to have met the study primary objective if GSK3359609 in 
combination with pembrolizumab and platinum-based chemotherapy is superior to the 
placebo in combination with pembrolizumab and platinum-based chemotherapy for either 
OS or PFS in the total population. 
9.2.1. 
Phase III Study with No Pause of Enrollment 
Overall Survival 
A total of 640 participants will be randomized in a 1:1 ratio. The final OS analysis will be 
carried out after approximately 410 events have occurred across two arms in the total 
population.  
The sample size and power calculation of OS are based on the following assumptions: 
1. The target hazard ratio is 0.72 at the end of study for OS between 
theGSK3359609 in combination with pembrolizumab and 5FU/platinum 
chemotherapy arm and the placebo in combination with pembrolizumab and 
5FU/platinum chemotherapy arm 
2. OS of the placebo in combination with pembrolizumab and 5FU/platinum 
chemotherapy arm follows the same distribution as the pembrolizumab + 
chemotherapy arm in the total population of KN-048 trial. That is, the survival 
rates at 6, 12, 24 and 36 months are approximately 77%, 53.0%, 29.4% and 
22.6%, respectively, with a median survival time of 13 months 
3. Enrollment period of 21 months  
4. Yearly drop-out rate of 5% 
The following alpha- and beta-spending functions are used in the OS hypothesis. 
• For the OS hypothesis, the alpha-spending function based on Lan-DeMets 
O’Brien-Fleming approximation spending function and the beta-spending 
function based on the Hwang-Shih-DeCani boundary method with a gamma 
parameter of -20 are constructed to implement group sequential boundaries that 
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It is anticipated that pembrolizumab would provide a long-term survival benefit (heavy 
tail in survival curve) which was observed in the KN-048 clinical trial. Therefore, 2 OS 
scenarios were considered as it is expected that 1 of these scenarios will most likely be 
observed in 209227 trial. 
Scenario 1 – proportional hazards with heavy tail 
Scenario 1 assumes the hazard ratio of OS is consistent between the GSK3359609 in 
combination with pembrolizumab and 5FU/platinum chemotherapy arm and the placebo 
in combination with pembrolizumab and 5FU/platinum chemotherapy arm throughout the 
entire course of the study, with heavy tails for both arms. 
Under the proportional hazard assumption with 410 events at the final analysis, the study 
provides 90.6% power to demonstrate superiority of OS at the one-sided alpha level of 
2.49% with a true HR of 0.72. Success for OS at the final analysis approximately 
corresponds to an observed hazard ratio of 0.81. 
Scenario 2 – non-proportional hazards with delayed separation of OS curve and heavy 
tail 
Scenario 2 assumes the hazard ratio of OS is non-proportional between the GSK3359609 
in combination with pembrolizumab and 5FU/platinum chemotherapy arm and the 
placebo in combination with pembrolizumab and 5FU/platinum chemotherapy arm, with 
heavy tails for both arms. Specifically, it is assumed that the hazard ratio between the two 
arms is ~1 for the first 6 months due to potential delayed treatment effect. 
A simulation study was performed with piecewise time varying hazard ratio of OS at time 
intervals shown below: 
 
0-6 Month 
6-12 Month 
12-24 Month 
After 24 Month 
Hazard Ratio 
1 
0.69 
0.52 
0.50 
The simulation showed the final analysis will be delayed by approximately 2 months 
compared with the proportional hazard scenario. Under the non-proportional hazard 
assumption with 410 events at the final analysis, the study provides 90.2% power to 
demonstrate superiority of OS at the one-sided alpha level of 2.49% at the final analysis. 
Success for OS at the final analysis approximately corresponds to an observed hazard 
ratio of 0.81. 
Progression-free Survival 
The final PFS analysis will be carried out after approximately 470 events have occurred 
across two arms. The final PFS analysis is expected to occur at approximately 9 months 
after the last participant is enrolled in the study. With 470 PFS events, the study has 
93.1% power to demonstrate superiority in PFS when the true hazard ratio for PFS is 0.62 
at type I error rate of 0.01% (one-sided). 
The sample size and power calculation of PFS is based on the following assumptions:  

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1. PFS follows an exponential distribution with a median of 5 months in the placebo 
in combination with pembrolizumab and platinum-based chemotherapy arm  
2. Hazard ratio for PFS between the GSK3359609 in combination with 
pembrolizumab and platinum-based chemotherapy arm and the placebo in 
combination with pembrolizumab and platinum-based chemotherapy arm is 0.62 
3. Enrollment period of 21 months and a minimum of 8 months follow-up after 
enrollment completion 
4. Yearly dropout rate of 10% 
9.2.2. 
Phase II/III Study with Pause in Enrollment 
If a decision of expanding to Phase III study is made at the first interim analysis (IA1) 
which will occur after 9 months of OS follow-up in the first 300 participants, then this 
study will be a Phase III study with a total of 640 participants. Thus, 300 and 340 
participants will be enrolled before and after IA1, respectively, with an approximate 12 
months pause in enrollment between the 2 enrollment phases. 
Overall Survival 
The final OS analysis is event driven and will be carried out after approximately 425 
events have occurred across 2 arms.  
The sample size and power calculation of OS are based on the following assumptions: 
1. The target hazard ratio is 0.72 at the end of study for OS between the 
GSK3359609 in combination with pembrolizumab and 5FU/platinum 
chemotherapy arm and the placebo in combination with pembrolizumab and 
5FU/platinum chemotherapy arm 
2. OS of the placebo in combination with pembrolizumab and 5FU/platinum 
chemotherapy arm follows the same distribution as the pembrolizumab + 
chemotherapy arm in the total population of KN-048 trial. That is, the survival 
rates at 6, 12, 24 and 36 months are approximately 77%, 53.0%, 29.4% and 
22.6%, respectively, with a median survival time of 13 months 
3. Enrollment consists of 2 phases. The first phase is an enrollment period of ~15 
months for 300 participants, followed by an approximate 12 month pause of 
enrollment. The second phase is an enrollment period of ~18 months for 340 
participants 
4. Yearly drop-out rate of 5% 
The following alpha- and beta-spending functions are used in the OS hypothesis. 
• For the OS hypothesis, the alpha-spending function based on Lan-DeMets 
O’Brien-Fleming approximation spending function and the futility boundary of p-
value > 0.1 at IA1 are constructed to implement group sequential boundaries that 
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The following two OS scenarios were considered as it is expected that one of these 
scenarios will most likely be observed in 209227 trial. 
Scenario 1 – proportional hazards with heavy tail 
Scenario 1 assumes the hazard ratio of OS is consistent between the GSK3359609 in 
combination with pembrolizumab and 5FU/platinum chemotherapy arm and the placebo 
in combination with pembrolizumab and 5FU/platinum chemotherapy arm with heavy 
tails for both arms. 
Under the proportional hazard assumption with 425 events at the final analysis, this study 
has 71.2% power to demonstrate superiority of OS at the one-sided alpha level of 2.49% 
with a true HR of 0.72. If the futility boundary of p-value > 0.1 is not crossed at IA1, 
there is 98.8% probability to demonstrate superiority of OS with a true HR of 0.72. 
Success for OS at the final analysis approximately corresponds to an observed hazard 
ratio of 0.82. 
Scenario 2 – non-proportional hazards with delayed separation of OS curve and heavy 
tail 
A simulation study was performed with same piecewise time varying hazard ratios 
described in Section 9.2.1. The simulation showed the final analysis will be delayed by 
approximately 3 months compared with the proportional hazard scenario. Under the non-
proportional hazard assumption with 425 events at the final analysis, the study has 47.9% 
power to demonstrate superiority of OS at the one-sided alpha level of 2.49% with a true 
HR of 0.72 at the final analysis. If the futility boundary of p-value > 0.1 is not crossed at 
IA1, there is 98.8% probability to demonstrate superiority of OS with a true HR of 0.72. 
Success for OS at the final analysis approximately corresponds to an observed hazard 
ratio of 0.82. 
Progression-free Survival 
The final PFS analysis will be carried out at the time of the second interim analysis (IA2) 
for OS; with approximately 456 PFS events across the 2 arms. With 456 PFS events, the 
study has 92% power to demonstrate superiority in PFS when the true hazard ratio for 
PFS is 0.62 at type I error rate of 0.01% (one-sided). 
The sample size and power calculation of PFS is based on the following assumptions:  
1. PFS follows an exponential distribution with a median of 5 months in the placebo 
in combination with pembrolizumab and platinum-based chemotherapy arm 
2. Hazard ratio is 0.62 for PFS between the GSK3359609 in combination with 
pembrolizumab and 5FU/platinum chemotherapy arm and the placebo in 
combination with pembrolizumab and 5FU/platinum chemotherapy arm  
3. Enrollment consists of 2 phases. The first phase is an enrollment period of ~15 
months for 300 participants, followed by a 12 month pause in enrollment. The 
second phase is an enrollment period of ~18 months for 340 participants 
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9.3. 
Populations for Analyses 
The following populations are defined: 
Population 
Description 
All Screened 
All participants who sign the ICF 
Intent-to-treat 
All randomized participants whether or not randomized 
intervention was administered 
This population will be based on the study intervention to 
which a participant was randomized and will be the primary 
population for the analysis of efficacy data. 
Safety 
All randomized participants who take at least 1 dose of 
study intervention. This population will be the primary 
population for the analyses of safety data. 
Pharmacokinetic 
The Pharmacokinetic Population will consist of those 
participants in the Safety Population from whom at least 1 
PK sample has been obtained and analysed. This population 
will be the primary population for PK analyses. 
9.4. 
Statistical Analyses 
The statistical analysis plan will be finalized prior to first patient first visit and it will 
include a more technical and detailed description of the statistical analyses described in 
this section. This section provides summary of the planned statistical analyses of the most 
important endpoints including primary and key secondary endpoints. 
9.4.1. 
Primary and secondary endpoints will be included in the main 
CSR.  A separate final CSR will report updated key safety 
analyses at the end of study. Further details will be outlined in 
the statistical analysis plan.Efficacy Analyses 
The intent-to-treat (ITT) population that includes all randomized participants will serve 
as the primary population for the efficacy analyses. The hypotheses on OS and PFS will 
be tested at significance levels as specified in Section 9.8. All confidence intervals will be 
estimated at 95% significance level. 
Stratified statistical analyses will be based on the following stratification factors, PD-L1 
expression (CPS 20 vs. 1 CPS <20 vs. CPS <1), and HPV status (positive vs. 
negative). Participants with oropharynx HPV negative/unknown and non-oropharyngeal 
tumors will be combined as the HPV negative group in the stratified analyses. Details 
will be documented in the statistical analysis plan. 

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An outline of the analysis strategy for key efficacy endpoints is presented in Table 9. 
Details are outlined in Section 9.4.1.1 and Section 9.4.1.2 and will be further delineated 
in the statistical analysis plan. 
Table 9 
Analysis Strategy for Key Efficacy Endpoints 
Endpoint 
Statistical Method1 
Analysis 
Population 
Missing Data Approach 
OS 
Test: Stratified log-rank test to 
assess the treatment difference 
Estimation: Stratified Cox model 
with Efron’s tie handling method to 
assess the magnitude of treatment 
difference 
ITT 
Model based 
• 
Censoring rule(s) 
PFS per RECIST 
v1.1 
Test: Stratified log-rank test to 
assess the treatment difference 
Estimation: Stratified Cox model 
with Efron’s tie handling method to 
assess the magnitude of treatment 
difference 
ITT 
Model based 
• 
Censoring rule(s) 
ORR/DCR per 
RECIST v1.1 
Stratified Miettinen and 
Nurminen’s method with sample 
size weights 
ITT 
Participants with missing 
data are considered non-
responders and 
conservatively included in 
denominator 
Duration of 
Response per 
RECIST v1.1 
Summary statistics using Kaplan-
Meier method 
All 
Responders 
in ITT 
Non-responders are 
excluded from analysis 
Abbreviations: DCR=disease control rate; ITT=intent-to-treat; ORR=overall response rate; OS=overall 
survival; PFS=progression-free survival; RECIST= Response Evaluation Criteria in Solid Tumors 
Statistical models are described in further detail in the statistical analysis plan. 
Statistical analyses of PFS, ORR, DCR, and duration of response per iRECIST follow 
similarly. 
9.4.1.1. 
Primary Analyses 
Overall Survival 
OS is defined as the interval of time from the date of randomization to the date of death 
due to any cause. Participants without documented death will be censored at last known 
alive date. 
The non-parametric Kaplan-Meier method will be used to estimate the survival curves. 
The treatment difference in survival will be assessed by the stratified log-rank test. A 
stratified Cox proportional hazard model with Efron’s method of tie handling will be 
used to assess the magnitude of the treatment difference (i.e., the hazard ratio). The 
hazard ratio and its 95% confidence interval from the stratified Cox model with a single 
treatment covariate will be reported. OS rate at 12 months, 24 months, 36 month and the 
corresponding 95% CI will also be estimated from the Kaplan-Meier analysis. 
The Restricted Mean Survival Time (RMST) method or piecewise HR method may be 
conducted as appropriate to account for the possible non-proportional hazards effect. 

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Additional analyses of OS adjusting for the effect of subsequent treatment may be 
performed based on recognized methods, e.g., the Rank Preserving Structural Failure 
Time (RPSFT) model [Robins, 1991], if a sufficient proportion of participants switch. 
The choice of the method will be based on an examination of the appropriateness of the 
data to the assumptions required by the method. To further account for the possible 
confounding effect, a supplementary analysis of OS censoring participants at the time of 
initiation of new therapy will be performed. 
The proportional hazards assumption will be assessed using graphical method and testing 
the interaction term of treatment and time in the Cox model. More details will be 
provided in the statistical analysis plan. 
Progression-Free-Survival per RECIST v1.1 
Progression-free-survival (PFS) per RECIST v1.1 is defined as the time from the date of 
randomization to the date of the first documented disease progression per RECIST v1.1 
based on investigator assessment, or death due to any cause, whichever occurs first. 
A summary of the assignments for progression and censoring dates for the primary 
analysis of PFS per RECIST v1.1 is specified in Table 10. Supplementary analyses of 
PFS per RECIST v1.1 with different censoring rules will be delineated in the statistical 
analysis plan. 
Table 10 
Censoring Rules for Primary Analysis of PFS per RECIST v1.1 
Situation 
Primary Analysis 
No baseline disease assessments and the 
participant has not died 
Censored at the date of randomization 
No post-baseline disease assessments and the 
participant has not died 
Censored at the date of randomization 
With post-baseline disease assessments,  
new anticancer treatment is not initiated and no 
documented PD or death 
Censored at the date of last adequate radiological 
disease assessment1 
With post-baseline disease assessments and new 
anticancer treatment is initiated (prior to 
documented PD or death)2 
Censored at the date of last adequate radiological 
disease assessment on or prior to the initiation of 
new anticancer treatment 
PD or death documented after 1 missed disease 
assessment 
Progressed at the date of documented PD3 or death 
PD or death documented after 2 missed disease 
assessments 
Censored at the date of last adequate radiological 
disease assessment prior to the 2 missed disease 
assessment  
Abbreviations: CR=complete response; PD=progressive disease; PFS=progression-free survival; 
PR=partial response; RECIST=response evaluation criteria in solid tumors; SD=stable disease 
1. An adequate assessment is defined as an assessment where the investigator assessed response is CR, 
PR, or SD. 
2. If PD and new anti-cancer therapy occur on the same day, it is assumed that the progression was 
documented first (i.e. outcome is progression; the date is the date of the assessment for progression). 
3. The earliest of (i) Date of radiological assessment showing new lesion (if progression is based on new 
lesion); or (ii) Date of radiological assessment showing unequivocal progression in non-target lesions, 
or (iii) Date of last radiological assessment of measured lesions (if progression is based on increase in 
sum of measured lesions). 

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The non-parametric Kaplan-Meier method will be used to estimate the PFS curves. The 
treatment difference in PFS will be assessed by the stratified log-rank test. A stratified 
Cox proportional hazard model with Efron’s method of tie handling will be used to assess 
the magnitude of the treatment difference (i.e., hazard ratio) between the treatment arms. 
The hazard ratio and its 95% confidence interval from the stratified Cox model with 
Efron’s method of tie handling and with a single treatment covariate will be reported. 
The proportional hazards assumption will be assessed using graphical method and testing 
the interaction term of treatment and time in the Cox model. In case the proportional 
hazards assumption is not valid for PFS, the RMST method or piecewise HR as 
appropriate may be performed for PFS to account for the possible non-proportional 
hazards effect. Details will be provided in the statistical analysis plan. 
9.4.1.2. 
Secondary Analyses 
OS Rate at 12, 24 and 36 months 
The non-parametric Kaplan-Meier method will be used to estimate the survival curves. 
OS rate at 12 months, 24 months and 36 months and the corresponding 95% CI will be 
estimated from the Kaplan-Meier analysis. 
Overall Response Rate/Disease Control Rate 
ORR per RECIST v1.1 is defined as the proportion of the participants who have a 
complete response (CR) or partial response (PR) as the best overall response per 
RECIST v1.1 based upon investigator assessment. 
DCR per RECIST v1.1 is defined as the percentage of participants with a best overall 
response of CR or PR at any time plus SD meeting the minimum time of 18 weeks per 
RECIST v1.1 based upon investigator assessment. 
Stratified Miettinen and Nurminen’s method will be used for comparison of the 
ORR/DCR between two treatment groups. The difference in ORR/DCR and its 95% 
confidence interval from the stratified Miettinen and Nurminen’s method with strata 
weighting by sample size with a single treatment covariate will be reported. Participants 
with unknown or missing response will be treated as non-responders and these 
participants will be included in the denominator when calculating the percentage of ORR 
and DCR. 
Duration of Response 
Duration of response (DoR) per RECIST v1.1 is defined as the time from first 
documented evidence of CR or PR until first documented disease progression per 
RECIST v1.1 based upon investigator assessment or death due to any cause, whichever 
occurs first, among participants who demonstrated CR or PR as the best overall response 
per RECIST v1.1. If sample size permits, DoR per RECIST v1.1 will be summarized 
descriptively using Kaplan-Meier medians and quartiles. 

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9.4.1.3. 
Exploratory Analyses 
9.4.1.3.1. Progression-Free Survival per iRECIST (iPFS) 
Progression-free survival per iRECIST (iPFS) is defined as the interval of time from the 
date of randomization to the date of the first documented disease progression confirmed 
consecutively per iRECIST based on investigator assessment, or death due to any cause, 
whichever occurs first. 
Unlike RECIST 1.1, iRECIST requires the confirmation of progression and uses the 
terms unconfirmed progressive disease (iUPD) and confirmed progressive disease 
(iCPD). 
The progression event date (iPD date) to be used in the calculation of PFS per iRECIST 
should be the first date of documented iUPD provided that iCPD is confirmed at the next 
assessment. If iUPD occurs, but is disregarded because of later iSD, iPR, or iCR, that 
iUPD date should not be used as the progression event date. 
If progression is not confirmed and there is no subsequent iSD, iPR, or iCR, then the 
iUPD date will be used as iPD date in the following scenarios: 
• Participant discontinues study treatment because the participant was judged not to 
be clinically stable  
• Participant does not undergo further response assessments due to any reason (i.e., 
participant refusal, protocol non-compliance, or participant death) 
•  Next timepoint response of iUPD, and iCPD never occurs 
Determination of dates of iPFS events and dates for censoring in the secondary analysis 
of iPFS are summarized in Table 11.  
Table 11 
Censoring Rules for Analysis of iPFS 
Situation 
Primary Analysis 
No baseline disease assessments and the 
participant has not died 
Censored at the date of randomization 
No post-baseline disease assessments and the 
participant has not died 
Censored at the date of randomization 
With post-baseline disease assessments,  
new anticancer treatment is not initiated, and no 
iPD date or death 
Censored at the date of last radiological disease 
assessment 
With post-baseline disease assessments,  
new anticancer treatment is initiated (prior to iPD 
date or death)1  
Censored at the date of last radiological disease 
assessment on or prior to the initiation of new 
anticancer treatment 
iPD date or death after 1 missed disease 
assessment 
Progressed at the iPD date2 or death 
iPD date or death documented after 2 missed 
disease assessments 
Censored at the date of last radiological disease 
assessment prior to the 2 missed disease 
assessment  

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Abbreviations: iPD=immune-based progressive disease; iPFS=progression-free survival per iRECIST 
1. If the iPD date and new anti-cancer therapy occur on the same day, it is assumed that the progression 
was documented first (i.e. outcome is progression; the date is the date of the assessment for 
progression). 
2. The earliest date of radiological assessments of lesion in which progression criteria are met for the iPD 
date. 
The non-parametric Kaplan-Meier method will be used to estimate the iPFS curves. The 
treatment difference in iPFS will be assessed by the stratified log-rank test. A stratified 
Cox proportional hazard model with Efron’s method of tie handling will be used to assess 
the magnitude of the treatment difference (i.e., hazard ratio) between the treatment arms. 
The hazard ratio and its 95% confidence interval from the stratified Cox model with 
Efron’s method of tie handling and with a single treatment covariate will be reported. 
In case the proportional hazards assumption is not valid for iPFS, the RMST method or 
piecewise HR as appropriate may be conducted for iPFS to account for the possible non-
proportional hazards effect. 
9.4.1.3.2. Other Exploratory Analyses 
An exploratory analysis of ORR per iRECIST will be performed using the stratified 
Miettinen and Nurminen’s method. The corresponding 95% CI for ORR will also be 
provided. Participants with unknown or missing responses will be treated as non-
responders, i.e., these participants will be included in the denominator when calculating 
percentages of response. 
If sample size permits, DoR per iRECIST will be summarized descriptively using 
Kaplan-Meier medians and quartiles.  
An exploratory analysis of PFS2, defined as the time from randomization to subsequent 
disease progression per RECIST 1.1 based on investigator assessment after initiation of 
first new anti-cancer therapy, or death from any cause, whichever first, will be carried 
out. Participants alive and for whom a second objective disease progression has not been 
observed will be censored at the last time known to be alive and without second objective 
disease progression. 
Further details of efficacy analyses will be described in the statistical analysis plan. 
PK, immunogenicity and biomarker exploratory analyses will be described in the 
statistical analysis plan. Theses exploratory analyses may be presented separately from 
the main CSR. 
9.4.2. 
Safety Analyses 
The safety population will serve as the primary population for the analyses of safety data 
in this study. Safety analyses will follow a tiered approach [Crowe, 2009] as shown in 
Table 12. The tiers differ with respect to the analyses that will be performed. Tier 1 safety 
endpoints that will be critical to inferential testing for statistical significance with 
p-values and 95% confidence intervals may be provided for between-group comparisons. 

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For this protocol, there are no Tier 1 events. All safety parameters will be considered 
Tier 2 or Tier 3. Tier 2 parameters will be assessed via point estimates with 95% CI 
provided for between-group comparisons; only point estimates by treatment group are 
provided for Tier 3 safety parameters. The between-treatment difference will be analyzed 
using the Miettinen and Nurminen method. 
Based on emerging external data, the analysis strategy for safety endpoints may be 
modified to improve the integrity and efficiency of the design. Should this happen, the 
change will be documented elsewhere, if not in a protocol amendment, at the earliest time 
before any unblinding of the data. Refer to the statistical analysis plan for further details. 
Table 12 
Analysis Strategy for Safety Parameters 
Safety Tier 
Safety Endpoint 
95% CI for 
Treatment 
Comparison 
Descriptive 
Statistics 
Tier 2 
Any AE 
X 
X 
Any Serious AE 
X 
X 
Any Grade 3-5 AE 
X 
X 
Any Treatment-Related AE 
X 
X 
Any Treatment-Related Serious AE 
X 
X 
Any Grade 3-5 and Treatment-Related AE 
X 
X 
Dose Modification due to AE 
X 
X 
Discontinuation due to AE 
X 
X 
Death 
X 
X 
Specific AEs, SOCs (incidence ≥ 5% of 
participants in 1 of the treatment groups) 
X 
X 
Tier 3 
Specific AEs, SOCs (incidence < 5% of 
participants in both treatment groups) 
 
X 
Change from Baseline Results (Labs, ECGs, 
Vital Signs) 
 
X 
Abbreviations: AE=adverse event; CI=confidence intervals; ECG=electrocardiogram; SOC=system organ 
class 
9.4.3. 
Patient Reported Outcomes 
EORTC IL50 and IL51(subset of domains from the EORTC QLQ C30 and H&N35 
respectively) are not pure efficacy or safety endpoints because they are affected by both 
disease symptoms and treatment tolerability in addition to HRQoL domains. 
The time to deterioration (TTD) in Pain measured by the EORTC QLQ-H&N35 pain 
domain (included in the EORTC IL51) and the TTD in Physical Function (PF) measured 
by the PROMIS PF 8c will be analysed in the ITT population using the non-parametric 
Kaplan-Meier method. 
The treatment effect in TTD will be assessed separately by the stratified log-rank test. A 
stratified Cox proportional hazard model with Efron’s method of tie handling will be 
used to assess the magnitude of the treatment difference (i.e., hazard ratio) between the 
treatment arms. The hazard ratio and its 95% confidence interval from the stratified Cox 
model with Efron’s method of tie handling and with a single treatment covariate will be 
reported. 

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For both Pain and PF, TTD will be defined as the time from the date of randomization to 
the date of first definitive meaningful deterioration in score compared to baseline. The 
deterioration has to be: 
• Meaningful, i.e. greater than a clinically meaningful within-individual change in 
score, as defined below; 
• Definitive, i.e. two sequential assessments of the score are showing a clinically 
meaningful deterioration compared to baseline and no subsequent scores return to 
baseline, or no further score is available for the patients for any reason (including 
disease progression or death) 
Patients who don’t show meaningful deterioration will be censored at the time of the last 
available PRO assessment. 
As no threshold for meaningful within-individual change is established for the EORTC 
QLQ-H&N35 pain domain score or PROMIS PF 8c score, the value for use in the TTD 
analyses will be determined using blinded interim data from the phase II. These analyses 
will be performed before study unblinding and the value will be set-up before database 
lock. The full procedure for determination of meaningful within-person change in 
EORTC QLQ-H&N35pain domain score and PROMIS PF 8c score will be fully 
described in the clinical statistical analysis plan or in a standalone analysis plan, as 
appropriate. It will include anchor-based approach using the patient global impression of 
severity and change as an anchors, and possibly other clinical anchors (e.g. ECOG 
status). Supportive distribution-based methods may be applied as sensitivity analyses. 
The EORTC IL50, EORTC IL51, BPI-SF I3 and EQ-5D changes will be summarized as 
part of the exploratory analysis. Longitudinal and descriptive data analysis may be used 
to evaluate patient reported outcomes. The detailed PRO analysis plan will be included in 
a reporting and analysis plan document. 
9.5. 
Interim Analyses 
If the study continues as a Phase III study, there will be two interim analyses on OS, 
allowing for early stopping of the study due to efficacy or allow for non-binding futility 
analysis.  
For the Phase III study with no enrollment pause, the timing of the two interim analyses 
will be triggered by the pre-specified number of OS events in the total population. The 
final analysis of PFS will be aligned with the first OS interim analysis.  
For the Phase II/III study with an enrollment pause, the first interim analyses of OS (IA1, 
adaptive decision making) will occur when the first 300 participants have a minimum 
follow-up of 9 months. A futility criterion of p-value > 0.1 for log-rank test of OS is pre-
specified for adaptive decision making. If the futility criterion is not met at the first 
interim analysis (IA1), the study will continue as a Phase III study and enrollment of an 
additional 340 participants to a total of 640 participants will occur. If the futility criterion 
is met in the OS analysis, the study will stop for futility. The timing of the second interim 

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analyses will be triggered by the pre-specified number of OS events in the total 
population. The final analysis of PFS will be aligned with the second OS interim analysis. 
The nominal significance levels for the interim and final analyses of OS will be 
determined by the Lan-DeMets spending function based upon the O’Brien-Fleming 
boundary. The futility bounds of this study are non-binding and the bounds are 
considered guidance rather than strict bounds. 
Table 13 and Table 14 summarizes the required number of events, sample size and 
decision guidance for the planned PFS and OS analyses for the 2 Phase III study 
scenarios, respectively. Efficacy boundaries and non-binding futility boundaries are 
based on initially assigned type I error rate before any alpha re-allocation and projected 
number of events at study mile stones. The actual boundaries will be determined from the 
actual number of interim analyses conducted and from the actual number of events, at the 
time of the specified interim analysis using the alpha- and beta- spending functions. 
Actual futility bounds will be updated if overall beta is changed with respect to alpha 
reallocation. 
Results of the interim analyses will be reviewed by an independent data monitoring 
committee (IDMC). Further details of interim analyses are provided in the IDMC 
Charter. Any change to the planned event size will be described in the statistical analysis 
plan before any unblinding of the data. 
Table 13 
Summary of Number of Events, Sample Size and Decision Guidance 
at the Planned Interim and Final Analyses for Phase III Study with No 
Pause in Enrollment 
Analysis 
Key 
Endpts 
Expected 
Number of 
Events at the 
Planned 
Analysis 
(Information 
Fraction) 
Efficacy Boundary1 
Non-binding Futility 
Boundary1 
p-value 
Cumulative 
Alpha  
p-value 
Cumulative 
Beta  
IA1: Final 
PFS 
Analysis 
(H3, H4); 
Interim OS 
Analysis1 
(H1, H2) 
PFS 
~470 (100%) 
0.0001 
0.0001 
NA 
NA 
OS 
~310 (76%) 
0.01 
0.01 
0.619 
0.0007 
IA2: 
Interim OS 
Analysis2 
(H1, H2) 
OS 
~375 (92%) 
0.016 
0.019 
0.143 
0.017 
FA:  
Final OS 
Analysis 
(H1, H2) 
OS 
~410 (100%) 
0.019 
0.0249 
0.019 
0.094 

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Abbreviations: Endpts=endpoints; FA: final analysis; H=hypothesis; IA: interim analysis; NA: not 
applicable; PFS=progression-free survival; OS=overall survival 
1. Efficacy boundaries and non-binding futility boundaries are based on initially assigned type I error rate 
before any alpha roll-over and projected number of events at study mile stones. Actual efficacy 
boundaries will be based on the actual number of interim analyses conducted and actual numbers of 
events available at study milestones. Actual futility bounds will be updated if overall beta is changed 
with respect to alpha roll-over. 
2. The timing of interim analyses and final analysis for OS may be delayed in the presence of non-
proportional hazards. 
Table 14 
Summary of Number of Events, Sample Size and Decision Guidance 
at the Planned Interim and Final Analyses for Phase II/III Study with 
Pause in Enrollment 
Abbreviations: Endpts=endpoints; FA: final analysis; H=hypothesis; IA: interim analysis; NA: not 
applicable; PFS=progression-free survival; OS=overall survival 
1. Efficacy boundaries and non-binding futility boundaries are based on initially assigned type I error rate 
before any alpha roll-over and projected number of events at study mile stones. Actual efficacy 
boundaries will be based on the actual number of interim analyses conducted and actual numbers of 
events available at study milestones. Actual futility bounds will be updated if overall beta is changed 
with respect to alpha roll-over. 
2. The timing of interim analyses and final analysis for OS may be delayed in the presence of non-
proportional hazards. 
3. Represents the OS adaptive decision analysis timepoint. If OS reaches the futility boundary then no 
further OS analyses will be performed and IA1 becomes the end of Phase II for OS. 
Analysis 
Key 
Endpts 
Expected 
Number of 
Events at the 
Planned 
Analysis 
(Information 
Fraction) 
Efficacy Boundary1 
Non-binding Futility 
Boundary1 
p-value 
Cumulative 
Alpha 
p-value 
Cumulative 
Beta 
IA1: Interim 
OS 
Analysis1, 3 
(H1, H2) 
OS 
~136 (32%) 
0.00007 
0.00007 
0.1 
0.263 
IA2:  
Final PFS 
Analysis 
(H3, H4); 
Interim OS 
Analysis2 
(H1, H2) 
PFS 
~456 (100%) 
0.0001 
0.0001 
NA 
NA 
OS 
~315 (74%) 
0.009 
0.009 
NA 
0.263 
FA:  
Final OS 
Analysis 
(H1, H2) 
OS 
~425 (100%) 
0.022 
0.0249 
0.022 
0.288 

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9.6. 
Independent Data Monitoring Committee (IDMC) 
The study will use an IDMC. The IDMC membership and governance will be outlined in 
a separate charter. 
The IDMC will make recommendations for discontinuation or modification of the study 
based on ongoing reviews of safety data according to the Charter. In addition, the IDMC 
will also evaluate all adaptive decision analyses, PFS analysis and OS interim analysis, 
and make recommendations based on observed results of the study and the totality of data 
available. 
In this double-blind study, all GSK and site personnel will be restricted from access to 
interim analysis results provided to the IDMC until the conclusion of the study, unless the 
IDMC recommends significant changes to study conduct that require a protocol 
amendment. In this scenario, after receiving the IDMC recommendation and a decision 
by Chief Medical Officer (CMO), a review of the data may be required. A select group 
from GSK, as determined by the CMO will be unblinded to review the data to agree on 
future study conduct. Depending on the recommendation of the IDMC, the Sponsor may 
prepare a regulatory submission. More details will be provided in the IDMC Charter. 
9.7. 
Blinded Independent Central Review Auditing 
A random sample-based BICR auditing approach will be used to assess whether bias 
exists in estimation of PFS hazard ratio between investigator assessments and BICR 
assessments [Stone, 2015]. The study is currently designed as a randomized, double-blind 
study. The risk of investigator bias can be mitigated in a properly double-blinded 
randomized study [Dodd, 2008]. 
The objective of the sample-based BICR approach is to corroborate the analysis results of 
the investigator-assessed PFS and to assist in the evaluation of potential bias. The BICR 
audit approach is not intended to provide an alternative means of definitive analysis. 
Evaluation bias will be assessed through the use of measure proposed by Stone et al 
[Stone, 2015]. The hazard ratio ratio (HRR), where HRR is defined as the ratio of the 
hazard ratio (HR) for the treatment effect estimated from the BICR to the corresponding 
HR for the investigator assessments, i.e.  HRR=HRBICR/HRInv. Larger values of HRR are 
suggestive of a less acceptable bias. The maximum acceptable HRR will be derived based 
on the graded approach [Stone, 2015]. For example, in order to preserve two-thirds of the 
observed HR based on investigator assessment, the maximum acceptable HRR is 1.204 if 
the full study HR based on investigator assessment is 0.62. 
If the sample HRR is within the range specified by the maximum acceptable HRR, it is 
concluded that the sample is sufﬁcient to rule out meaningful levels of bias, and no 
further scans will be assessed by the BICR; otherwise the BICR will be performed in all 
participants. 
The audit size of the sample-based BICR will be 35% of all participants. Assuming the 
correlation in the logarithm of HRs between investigator assessment and BICR is 0.85, 
with the maximum acceptable HRR of 1.204 and the testing of evaluation of bias is 

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conducted at the 10% alpha level, and 70% of participants have an event according to 
investigator assessment and 65% according to BICR, the audit size of 35% will ensure 
that the specificity is ~90% in all participants. 
9.8. 
Multiplicity 
The family-wise type I error for this study is strongly controlled at 2.5% (one-sided) with 
0.01% allocated to the PFS hypotheses and 2.49% allocated to the OS hypotheses. 
Figure 1 shows the initial one-sided alpha-allocation for OS, PFS, and key PRO 
endpoints. The weights for reallocation from each hypothesis to the others are 
represented on the lines connecting hypotheses. 
Figure 1 
Multiplicity Testing Strategy for Comparison Between GSK3359609 
in Combination with Pembrolizumab + 5FU/Platinum-based 
Chemotherapy versus Placebo in Combination with Pembrolizumab 
+ 5FU/Platinum-based Chemotherapy  
 
Abbreviations: C=Chemotherapy; CPS=combined positive score; H = hypothesis; 
I=GSK3359609; OS=overall survival; P=pembrolizumab; PD-L1= programmed cell death receptor 
1-ligand 1; PF=physical function; PFS=progression-free survival; PRO=patient reported outcome; 
TTD=time to deterioration vs=versus 
1. The alpha inside a box reflects the initial allocated alpha. 
2. The alpha level assigned to a family will be rolled over only if the hypotheses within the family are 
significant based on the splitting weights for re-allocation presented on the dashed lines connecting 
families. Within each family, the weights for reallocation from each hypothesis to the others are 
represented on the solid lines connecting hypotheses. 
3. ε = 49/249 if H1 and H2 are rejected at the scheduled timing of PFS analysis; ε = 0 if H1 and H2 are 
rejected after the scheduled timing of PFS analysis.  
The alpha re-allocation for PFS, OS and key PRO endpoints is detailed below: 

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Overall Survival 
• An initial alpha level of 2.49% is allocated to the OS 
• If PFS is significant in both total population and PD-L1 CPS1 population, 0.01% 
alpha level will be re-allocated to OS hypothesis so that OS hypotheses in all 
participants total population may be tested at 2.5%. 
• OS in the PD-L1 CPS1 population is tested sequentially at the same overall 
alpha level as that of OS in the total population if GSK3359609 in combination 
with pembrolizumab and 5FU/platinum chemotherapy demonstrates superiority to 
pembrolizumab in combination with 5FU/platinum chemotherapy in OS in the 
total population. If OS is not significant in total population, the formal conclusion 
of statistical significance on OS in PD-L1 CPS1 population will not be drawn. 
Refer to Section 9.2 for alpha- and beta-spending functions used in the OS hypothesis for 
each possible design. 
Section 9.5 demonstrates the planned analyses as well as bounds and boundary properties 
for OS hypothesis testing. Efficacy boundaries and non-binding futility boundaries are 
based on initially assigned type I error rate before any alpha re-allocation and projected 
number of events at study milestones. The actual boundaries will be determined from the 
actual number of events at the time of the specified interim analysis using the alpha- and 
beta- spending functions. Actual futility bounds will be updated if overall beta is changed 
with respect to alpha roll-over. 
Progression-free Survival 
• An initial alpha level of 0.01% is allocated to the PFS 
• If OS is significant in both the total population and PD-L1 CPS1 population at 
the time of the first OS interim analysis, 0.49% alpha level will be re-allocated to 
PFS hypothesis so that the PFS hypothesis in total population may be tested at 
0.5%. 
• If the PFS hypothesis in the total population is significant, the hypothesis of PFS 
in PD-L1 CPS1 population will be tested sequentially at the same alpha level. 
Key Patient Reported Outcomes (TTD in Pain, TTD in PF) 
• If GSK3359609 in combination with pembrolizumab and 5FU/platinum 
chemotherapy demonstrates OS superiority to placebo in combination with 
pembrolizumab and 5FU/platinum chemotherapy in both the total population and 
PD-L1 CPS1 population, will key secondary PRO endpoints be tested. The alpha 
level from OS hypothesis will be propagated to key PRO hypotheses. 
• If OS meets superiority in both the total population and PD-L1 CPS1 population 
at the time of the first OS interim analysis, a total of 2.0% alpha level will be 
propagated to key PRO hypotheses. 

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• If OS demonstrates superiority in both populations at the time of the second OS 
analysis or the final OS analysis but PFS fails to demonstrate superiority in either 
the total or the PD-L1 CPS1 population, a total of 2.49% alpha level will be 
propagated to key PRO hypotheses. 
• If both OS and PFS demonstrates superiority in both the total population and the 
PD-L1 CPS1 population, a total of 2.5% alpha level will be propagated to key 
PRO hypotheses. 
• The alpha level propagated from OS will be equally split between TTD in Pain 
and TTD in PF, with the possibility to further propagate the alpha level between 
each other. 
• If 1 of 2 key PRO hypotheses in the total population is rejected based on the 
re-allocated alpha level, the key PRO hypotheses in PD-L1 CPS1 population can 
be tested based on the (updated) weight, with the possibility to further propagate 
the levels between each other. 
• Based on the re-allocated cumulative alpha level, the nominal significance level 
for each key PRO endpoint will be calculated based on the Lan-DeMets O’Brien-
Fleming approximation alpha-spending function. 

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10. 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
10.1. 
Appendix 1: Regulatory, Ethical, and Study Oversight 
Considerations 
10.1.1. 
Regulatory and Ethical Considerations 
• 
This study will be conducted in accordance with the protocol and with: 
• Consensus ethical principles derived from international guidelines 
including the Declaration of Helsinki and Council for International 
Organizations of Medical Sciences (CIOMS) International Ethical 
Guidelines 
• Applicable ICH Good Clinical Practice (GCP) Guidelines 
• Applicable laws and regulations 
• 
The protocol, protocol amendments, ICF, Investigator Brochure, and other 
relevant documents (e.g., advertisements) must be submitted to an IRB/IEC by 
the investigator and reviewed and approved by the IRB/IEC before the study is 
initiated. 
• 
Any amendments to the protocol will require IEC/IRB approval before 
implementation of changes made to the study design, except for changes 
necessary to eliminate an immediate hazard to study participants. 
• 
The investigator will be responsible for the following: 
• Providing written summaries of the status of the study to the IRB/IEC 
annually or more frequently in accordance with the requirements, policies, 
and procedures established by the IRB/EC 
• Notifying the IRB/IEC of SAE or other significant safety findings as 
required by IRB/IEC procedures 
• Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR, ICH guidelines, the IRB/IEC, European 
regulation 536/2014 for clinical studies (if applicable), and all other 
applicable local regulations 
10.1.2. 
Informed Consent Process 
• 
The investigator or his/her representative will explain the nature of the study to 
the participant or his/her legally authorized representative and answer all 
questions regarding the study. 
• 
Participants must be informed that their participation is voluntary. Participants 
or their legally authorized representative will be required to sign a statement of 
informed consent that meets the requirements of 21 CFR 50, local regulations, 
ICH guidelines, Health Insurance Portability and Accountability Act (HIPAA) 
requirements, where applicable, and the IRB/IEC or study center. 

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• 
The medical record must include a statement that written informed consent was 
obtained before the participant was enrolled in the study and the date the written 
consent was obtained. The authorized person obtaining the informed consent 
must also sign the ICF. 
• 
Participants must be re-consented to the most current version of the ICF(s) 
during their participation in the study. 
• 
A copy of the ICF(s) must be provided to the participant or the participant’s 
legally authorized representative. 
A participant who is rescreened may not be required to sign another ICF if the 
rescreening occurs within the assessment windows as defined in the SoA. 
GSK (alone or working with others) may use participant’s coded study data and samples 
and other information to carry out this study; understand the results of this study; learn 
more about the study intervention or about the study disease; publish the results of these 
research efforts; work with government agencies or insurers to have the the study 
intervention approved for medical use or approved for payment coverage. 
The ICF contains a separate section that addresses the use of participant data and 
remaining samples for optional further research. The investigator or authorised designee 
will inform each participant of the possibility of further research not related to the 
study/disease. Participants will be told that they are free to refuse to participate and may 
withdraw their consent at any time and for any reason during the storage period. A 
separate tick box will be required to document a participant's agreement to allow any 
participant data and/or remaining leftover samples to be used for further research not 
related to the study/disease. Participants who decline further research will tick the 
corresponding “No” box. 
10.1.3. 
Data Protection 
• 
Participants will be assigned a unique identifier by the sponsor. Any participant 
records or datasets that are transferred to the sponsor will contain the identifier 
only; participant names or any information which would make the participant 
identifiable will not be transferred. 
• 
The participant must be informed that his/her personal study-related data will be 
used by the sponsor in accordance with local data protection law. The level of 
disclosure must also be explained to the participant who will be required to give 
consent for their data to be used as described in the informed consent.  
• 
The participant must be informed that his/her medical records may be examined 
by Clinical Quality Assurance auditors or other authorized personnel appointed 
by the sponsor, by appropriate IRB/IEC members, and by inspectors from 
regulatory authorities. 
10.1.4. 
Dissemination of Clinical Study Data 
• 
Where required by applicable regulatory requirements, an investigator signatory 
will be identified for the approval of the clinical study report. The investigator 

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will be provided reasonable access to statistical tables, figures, and relevant 
reports and will have the opportunity to review the complete study results at a 
GSK site or other mutually-agreeable location. 
• 
GSK will also provide the investigator with the full summary of the study 
results.  The investigator is encouraged to share the summary results with the 
study subjects, as appropriate. 
• 
GSK will provide the investigator with the randomization codes for their site 
only after completion of the full statistical analysis. 
• 
The procedures and timing for public disclosure of the protocol and results 
summary and for development of a manuscript for publication for this study will 
be in accordance with GSK Policy. 
• 
GSK intends to make anonymized patient-level data from this trial available to 
external researchers for scientific analyses or to conduct further research that 
can help advance medical science or improve patient care. This helps ensure the 
data provided by trial participants are used to maximum effect in the creation of 
knowledge and understanding. 
10.1.5. 
Data Quality Assurance 
• 
All participant data relating to the study will be recorded on printed or electronic 
CRF unless transmitted to the sponsor or designee electronically (e.g., 
laboratory data). The investigator is responsible for verifying that data entries 
are accurate and correct by physically or electronically signing the CRF. 
• 
The investigator must maintain accurate documentation (source data) that 
supports the information entered in the CRF. 
• 
The investigator must permit study-related monitoring, audits, IRB/IEC review, 
and regulatory agency inspections and provide direct access to source data 
documents. 
• 
Monitoring details describing strategy (e.g., risk-based initiatives in operations 
and quality such as Risk Management and Mitigation Strategies and Analytical 
Risk-Based Monitoring), methods, responsibilities and requirements, including 
handling of noncompliance issues and monitoring techniques (central, remote, 
or on-site monitoring) are provided in the Monitoring Plan. 
• 
The sponsor or designee is responsible for the data management of this study 
including quality checking of the data. 
• 
The sponsor assumes accountability for actions delegated to other individuals 
(e.g., Contract Research Organizations). 
• 
Study monitors will perform ongoing source data verification to confirm that 
data entered into the CRF by authorized site personnel are accurate, complete, 
and verifiable from source documents; that the safety and rights of participants 
are being protected; and that the study is being conducted in accordance with the 
currently approved protocol and any other study agreements, ICH GCP, and all 
applicable regulatory requirements. 

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• 
Records and documents, including signed ICF, pertaining to the conduct of this 
study must be retained by the investigator for 25 years from the issue of the final 
Clinical Study Report (CSR)/ equivalent summary unless local regulations or 
institutional policies require a longer retention period. No records may be 
destroyed during the retention period without the written approval of the 
sponsor. No records may be transferred to another location or party without 
written notification to the sponsor. 
10.1.6. 
Source Documents 
• 
Source documents provide evidence for the existence of the participant and 
substantiate the integrity of the data collected. Source documents are filed at the 
investigator’s site. 
• 
Data reported on the CRF or entered in the eCRF that are transcribed from 
source documents must be consistent with the source documents or the 
discrepancies must be explained. The investigator may need to request previous 
medical records or transfer records, depending on the study. Also, current 
medical records must be available. 
• 
Definition of what constitutes source data can be found in SRM and The 
Monitoring Plan. 
10.1.7. 
Study and Site Closure 
GSK or its designee reserves the right to close the study site or terminate the study at any 
time for any reason at the sole discretion of GSK. Study sites will be closed upon study 
completion. A study site is considered closed when all required documents and study 
supplies have been collected and a study-site closure visit has been performed. 
The investigator may initiate study-site closure at any time, provided there is reasonable 
cause and sufficient notice is given in advance of the intended termination. 
Reasons for the early closure of a study site by the sponsor or investigator may include 
but are not limited to: 
• 
Failure of the investigator to comply with the protocol, the requirements of the 
IRB/IEC or local health authorities, the sponsor's procedures, or GCP guidelines 
• 
Inadequate recruitment of participants by the investigator 
• 
Discontinuation of further study intervention development 
If the study is prematurely terminated or suspended, the sponsor shall promptly inform 
the Investigators, the IECs/IRBs, the regulatory authorities, and any contract research 
organization(s) used in the study of the reason for termination or suspension, as specified 
by the applicable regulatory requirements. The Investigator shall promptly inform the 
subject and should assure appropriate subject therapy and/or follow-up. 

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10.2. 
Appendix 2: Clinical Laboratory Tests 
• 
The tests detailed in Table 15 will be performed by local laboratory. 
• 
Protocol-specific requirements for inclusion or exclusion of participants are 
detailed in Section 5 of the protocol. 
• 
Additional tests may be performed at any time during the study as determined 
necessary by the investigator or required by local regulations. 
• 
Pregnancy Testing  
• 
Refer to Section 5.1 Inclusion Criteria for screening pregnancy criteria. 
• 
Additional serum or urine pregnancy tests may be performed, as determined 
necessary by the investigator or required by local regulation, to establish the 
absence of pregnancy at any time during the participant’s participation in the 
study. 
Table 15 
Protocol-Required Safety Laboratory Assessments 
Laboratory Assessments 
Parameters 
Hematology 
RBC 
Indices 
WBC count with 
Differential 
Platelets 
Hemoglobin Neutrophils 
 
Hematocrit 
Lymphocytes 
 
RBC count 
Monocytes 
 
 
Eosinophils 
 
 
Basophils 
 
Clinical Chemistry 
BUNa 
Potassium 
Bilirubin 
AST (SGOT) 
Creatinineb 
Sodium 
Total 
protein 
ALT (SGPT) 
Glucose 
Calcium 
Albumin 
Alkaline 
phosphatase 
Coagulation 
INR or PT 
aPTT 
Cardiac Function 
Troponin I or Troponin T 
Thyroid Function 
Thyroid stimulating hormone 
Free T4 
Free T3a 
Routine Urinalysis 
Specific gravity 
pH, glucose, protein, blood and ketones  
Other Screening Testsc 
Hepatitis B (HBsAg)d, HBsAbe, HBcAbe 
Hepatitis C (Hep C antibody)d 
Serum -hCG Pregnancy test (as needed for women of child 
bearing potential) 

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Abbreviations: ALT = alanine aminotransferase; AST = aspartate aminotransferase; -hCG = beta-human 
chorionic gonadotropin; BUN = blood urea nitrogen; eGFR=estimated glomerular filtration rate; HBcAb = 
Hepatitis B core antibody; HBsAb = Hepatitis B surface antibody; HBsAg = Hepatitis B surface antigen; 
HBV = Hepatitis B virus; RBC = red blood cells; SGOT = serum glutamic oxaloacetic transaminase; SGPT 
= serum glutamic pyruvic transaminase; T3 = triiodothyronine; T4 = thyroxine; WBC = white blood cells; 
INR = International Normalized Ratio; PT = Prothrombin Time; aPTT = Activated Partial Thromboplastin 
Time 
a. 
Required if local laboratory testing is available 
b. Creatinine clearance/eGFR is also required to be calculated using one of the formulas provided in 
Section 10.6. 
c. 
HIV testing for eligibility is not required unless mandated by local health authority 
d. Central laboratory testing will be performed if local laboratory testing not available. Participants with 
positive Hepatitis C antibody due to prior resolved disease can be enrolled, only if a confirmatory 
negative Hepatitis C RNA test is obtained. Hepatitis C RNA Test is optional with negative Hepatitis C 
antibody test. 
e. 
HBsAb and HBcAb tests are required for participants enrolled from sites in Japan. In HBcAb positive 
and/or HBsAb positive participants, it is required to monitor liver function tests and HBV DNA levels 
to monitor for hepatitis B reactivation . 

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10.3. 
Appendix 3: Adverse Events: Definitions and Procedures for 
Recording, Evaluating, Follow-up, and Reporting 
10.3.1. 
Definition of AE 
AE Definition 
• 
An AE is any untoward medical occurrence in a clinical study participant, 
temporally associated with the use of a study intervention, whether or not 
considered related to the study intervention. 
• 
NOTE: An AE can therefore be any unfavorable and unintended sign (including 
an abnormal laboratory finding), symptom, or disease (new or exacerbated) 
temporally associated with the use of a study intervention. 
 
Events Meeting the AE Definition 
• 
Any abnormal laboratory test results (hematology, clinical chemistry, or 
urinalysis) or other safety assessments (e.g., ECG, radiological scans, vital signs 
measurements), including those that worsen from baseline, considered clinically 
significant in the medical and scientific judgment of the investigator (i.e., not 
related to progression of underlying disease). 
• 
Exacerbation of a chronic or intermittent pre-existing condition including either an 
increase in frequency and/or intensity of the condition. 
• 
New conditions detected or diagnosed after study intervention administration even 
though it may have been present before the start of the study. 
• 
Signs, symptoms, or the clinical sequelae of a suspected drug-drug interaction. 
• 
Signs, symptoms, or the clinical sequelae of a suspected overdose of either study 
intervention or a concomitant medication. Overdose per se will not be reported as 
an AE/SAE unless it is an intentional overdose taken with possible suicidal/self-
harming intent. Such overdoses should be reported regardless of sequelae. 
• 
"Lack of efficacy" or "failure of expected pharmacological action" per se will not 
be reported as an AE or SAE. Such instances will be captured in the efficacy 
assessments. However, the signs, symptoms, and/or clinical sequelae resulting 
from lack of efficacy will be reported as AE or SAE if they fulfill the definition of 
an AE or SAE. 
 

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Events NOT Meeting the AE Definition  
• 
Any clinically significant abnormal laboratory findings or other abnormal safety 
assessments which are associated with the underlying disease, unless judged by 
the investigator to be more severe than expected for the participant’s condition. 
• 
The disease/disorder being studied or expected progression, signs, or symptoms of 
the disease/disorder being studied, unless more severe than expected for the 
participant’s condition. 
• 
Medical or surgical procedure (e.g., endoscopy, appendectomy): the condition that 
leads to the procedure is the AE. 
• 
Situations in which an untoward medical occurrence did not occur (social and/or 
convenience admission to a hospital). 
• 
Anticipated day-to-day fluctuations of pre-existing disease(s) or condition(s) 
present or detected at the start of the study that do not worsen. 
10.3.2. 
Definition of SAE 
If an event is not an AE per definition above, then it cannot be an SAE even if serious 
conditions are met (e.g., hospitalization for signs/symptoms of the disease under study, 
death due to progression of disease). 
A SAE is defined as any untoward medical occurrence that, at any dose: 
o Results in death 
o Is life-threatening 
The term 'life-threatening' in the definition of 'serious' refers to an event in which the 
participant was at risk of death at the time of the event. It does not refer to an event, 
which hypothetically might have caused death, if it were more severe. 
Requires inpatient hospitalization or prolongation of existing hospitalization 
• In general, hospitalization signifies that the participant has been detained 
(usually involving at least an overnight stay) at the hospital or emergency ward 
for observation and/or treatment that would not have been appropriate in the 
physician’s office or outpatient setting. Complications that occur during 
hospitalization are AE. If a complication prolongs hospitalization or fulfills any 
other serious criteria, the event is serious. When in doubt as to whether 
“hospitalization” occurred or was necessary, the AE should be considered 
serious. 
• Hospitalization for elective treatment of a pre-existing condition that did not 
worsen from baseline is not considered an AE. 

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Results in persistent or significant disability/incapacity 
• 
The term disability means a substantial disruption of a person’s ability to conduct 
normal life functions. 
• 
This definition is not intended to include experiences of relatively minor medical 
significance such as uncomplicated headache, nausea, vomiting, diarrhea, 
influenza, and accidental trauma (e.g. sprained ankle) which may interfere with or 
prevent everyday life functions but do not constitute a substantial disruption. 
Is a congenital anomaly/birth defect 
Other situations: 
• 
Medical or scientific judgment should be exercised in deciding whether SAE 
reporting is appropriate in other situations such as important medical events that 
may not be immediately life-threatening or result in death or hospitalization but 
may jeopardize the participant or may require medical or surgical intervention to 
prevent one of the other outcomes listed in the above definition. These events 
should usually be considered serious. 
• 
Examples of such events include invasive or malignant cancers, intensive 
treatment in an emergency room or at home for allergic bronchospasm, blood 
dyscrasias or convulsions that do not result in hospitalization, or development of 
drug dependency or drug abuse. 
10.3.3. 
Definition of Cardiovascular Events 
Cardiovascular Events (CV) Definition: 
Investigators will be required to fill out the specific CV event page of the CRF for the 
following AEs and SAEs: 
• 
Myocardial infarction/unstable angina 
• 
Congestive heart failure 
• 
Arrhythmias 
• 
Valvulopathy 
• 
Pulmonary hypertension 
• 
Cerebrovascular events/stroke and transient ischemic attack 
• 
Peripheral arterial thromboembolism 
• 
Deep venous thrombosis/pulmonary embolism 
• 
Revascularization 

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10.3.4. 
Recording and Follow-Up of AE and SAE 
AE and SAE Recording 
• 
When an AE/SAE occurs, it is the responsibility of the investigator to review all 
documentation (e.g. hospital progress notes, laboratory, and diagnostics reports) 
related to the event. 
• 
The investigator will then record all relevant AE/SAE information in the CRF. 
• 
It is not acceptable for the investigator to send photocopies of the participant’s 
medical records to GSK in lieu of completion of the GSK /AE/SAE CRF page. 
• 
There may be instances when copies of medical records for certain cases are 
requested by GSK. In this case, all participant identifiers, with the exception of the 
participant number, will be redacted on the copies of the medical records before 
submission to GSK. 
• 
The investigator will attempt to establish a diagnosis of the event based on signs, 
symptoms, and/or other clinical information. Whenever possible, the diagnosis 
(not the individual signs/symptoms) will be documented as the AE/SAE. 
Assessment of Severity 
• 
The investigator will make an assessment of severity for each AE and SAE 
reported during the study and will assign a grade according to the NCI-CTCAE 
v5.0 [NCI, 2017].  
 
Assessment of Causality 
• 
The investigator is obligated to assess the relationship between study intervention 
and each occurrence of each AE/SAE. 
• 
A "reasonable possibility" of a relationship conveys that there are facts, evidence, 
and/or arguments to suggest a causal relationship, rather than a relationship cannot 
be ruled out. 
• 
The investigator will use clinical judgment to determine the relationship. 
• 
Alternative causes, such as underlying disease(s), concomitant therapy, and other 
risk factors, as well as the temporal relationship of the event to study intervention 
administration will be considered and investigated. 
• 
The investigator will also consult the Investigator’s Brochure (IB) and/or Product 
Information, for marketed products, in his/her assessment. 
• 
For each AE/SAE, the investigator must document in the medical notes that 
he/she has reviewed the AE/SAE and has provided an assessment of causality. 
• 
There may be situations in which an SAE has occurred, and the investigator has 
minimal information to include in the initial report to GSK. However, it is very 

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Assessment of Causality 
important that the investigator always make an assessment of causality for 
every event before the initial transmission of the SAE data to GSK. 
• 
The investigator may change his/her opinion of causality in light of follow-up 
information and send an SAE follow-up report with the updated causality 
assessment. 
• 
The causality assessment is one of the criteria used when determining regulatory 
reporting requirements. 
Follow-up of AE and SAE 
• 
The investigator is obligated to perform or arrange for the conduct of supplemental 
measurements and/or evaluations as medically indicated or as requested by GSK 
to elucidate the nature and/or causality of the AE or SAE as fully as possible. This 
may include additional laboratory tests or investigations, histopathological 
examinations, or consultation with other health care professionals. 
• 
New or updated information will be recorded in the originally completed CRF. 
• 
The investigator will submit any updated SAE data to GSK within 24 hours of 
receipt of the information. 
10.3.5. 
Reporting of SAE to GSK 
SAE Reporting to GSK via Electronic Data Collection Tool 
• 
The primary mechanism for reporting SAE to GSK will be the electronic data 
collection tool. 
• 
If the electronic system is unavailable, then the site will use the paper SAE data 
collection tool (see next section) in order to report the event within 24 hours. 
• 
The site will enter the SAE data into the electronic system as soon as it becomes 
available. 
• 
After the study is completed at a given site, the electronic data collection tool will 
be taken off-line to prevent the entry of new data or changes to existing data. 
• 
If a site receives a report of a new SAE from a study participant or receives 
updated data on a previously reported SAE after the electronic data collection tool 
has been taken off-line, then the site can report this information on a paper SAE 
form (see next section) or to the medical monitor/SAE coordinator by telephone. 
• 
Contacts for SAE reporting can be found in the SRM. 

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SAE Reporting to GSK via Paper CRF 
• 
Refer to the SRM for the method to transmit the SAE paper CRF and to whom the 
information should be sent. 
• 
In rare circumstances notification by telephone is acceptable with a copy of the 
SAE data collection tool sent by overnight mail or courier service. 
• 
Initial notification via telephone does not replace the need for the investigator to 
complete and sign the SAE CRF pages within the designated reporting time 
frames. 
• 
Contacts for SAE reporting can be found in SRM. 

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10.4. 
Appendix 4: Contraceptive Guidance and Collection of 
Pregnancy Information 
Chemotherapies can cause fetal harm when administered to a pregnant woman, based on 
their mechanism of action. 
GSK3359609 and pembrolizumab may have adverse effects on a fetus in utero. 
Furthermore, it is not known if pembrolizumab has transient adverse effects on the 
composition of sperm. In order to participate in the study, participants of childbearing 
potential must adhere to the contraception requirement as indicated in Section 5.1 and 
Section 10.4.2. If there is any question that a participant of childbearing potential will not 
reliably comply with the requirements for contraception, that participant should not be 
entered into the study. 
10.4.1. 
Definitions: 
Woman of Childbearing Potential (WOCBP) 
A woman is considered fertile following menarche and until becoming post-menopausal 
unless permanently sterile (see below). 
If fertility is unclear (e.g., amenorrhea in adolescents or athletes) and a menstrual cycle 
cannot be confirmed before first dose of study intervention, additional evaluation should 
be considered. 
Women in the following categories are not considered WOCBP 
1. Premenarchal 
2. Premenopausal female with 1 of the following: 
• 
Documented hysterectomy 
• 
Documented bilateral salpingectomy 
• 
Documented bilateral oophorectomy 
For individuals with permanent infertility due to an alternate medical cause other 
than the above, (e.g., mullerian agenesis, androgen insensitivity), investigator 
discretion should be applied to determining study entry. 
Note: Documentation can come from the site personnel’s: review of the 
participant’s medical records, medical examination, or medical history interview. 
3. Postmenopausal female 
• 
A postmenopausal state is defined as no menses for 12 months without an 
alternative medical cause. 
• 
A high follicle stimulating hormone (FSH) level in the postmenopausal 
range may be used to confirm a postmenopausal state in women not 
using hormonal contraception or hormonal replacement therapy (HRT). 

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However, in the absence of 12 months of amenorrhea, confirmation with 
more than one FSH measurement is required. 
• 
Females on HRT and whose menopausal status is in doubt will be required to 
use one of the non-estrogen hormonal highly effective contraception methods 
if they wish to continue their HRT during the study. Otherwise, they must 
discontinue HRT to allow confirmation of postmenopausal status before 
study enrollment. 
10.4.2. 
Contraception Guidance: 
Male participants 
• 
Male participants with female partners of child-bearing potential are eligible to 
participate if they agree to ONE of the following during the protocol-defined 
time frame in Section 5.1. 
• Are abstinent from penile-vaginal intercourse as their usual and preferred 
lifestyle (abstinent on a long term and persistent basis) and agree to remain 
abstinent 
• Agree to use a male condom plus an additional method of contraception 
with a failure rate of <1% per year as described in Table 16 when having 
penile-vaginal intercourse with a woman of childbearing potential 
• 
Men with a pregnant or breastfeeding partner must agree to remain abstinent 
from penile-vaginal intercourse or use a male condom during each episode of 
penile penetration for the duration of the study and for at least 120 days after the 
last dose of study treatment. 
Female participants 
Table 16 
Highly Effective Contraceptive Methods 
CONTRACEPTIVESa ALLOWED DURING THE STUDY INCLUDE: 
• 
Highly Effective Methodsb That Have Low User Dependency Failure rate of <1% per 
year when used consistently and correctly. 
• 
Implantable progestogen-only hormone contraception associated with inhibition of 
ovulationc 
• 
Intrauterine device (IUD)  
• 
Intrauterine hormone-releasing system (IUS)c 
• 
Bilateral tubal occlusion 
• 
Vasectomized partner 
• 
Note: Vasectomized partner is a highly effective contraceptive method provided that 
the partner is the sole sexual partner of the woman of childbearing potential and the 
absence of sperm has been confirmed. If not, an additional highly effective method of 
contraception should be used. Spermatogenesis cycle is approximately 90 days. 

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CONTRACEPTIVESa ALLOWED DURING THE STUDY INCLUDE: 
• 
Highly Effective Methodsb That Are User Dependent Failure rate of <1% per year 
when used consistently and correctly. 
• 
Combined (estrogen- and progestogen-containing) hormonal contraception associated 
with inhibition of ovulationc 
• 
oral 
• 
intravaginal 
• 
transdermal 
• 
injectable 
• 
Progestogen-only hormone contraception associated with inhibition of ovulationc 
• 
oral 
• 
injectable 
• 
Sexual abstinence 
• 
Note: Sexual abstinence is considered a highly effective method only if defined as 
refraining from heterosexual intercourse during the entire period of risk associated 
with the study intervention. The reliability of sexual abstinence needs to be evaluated 
in relation to the duration of the study and the preferred and usual lifestyle of the 
participant. 
a. Contraceptive use by men or women should be consistent with local regulations regarding 
the use of contraceptive methods for those participating in clinical studies. 
b. Failure rate of <1% per year when used consistently and correctly. Typical use failure rates 
differ from those when used consistently and correctly. 
c. If locally required, in accordance with Clinical Trial Facilitation Group (CTFG) guidelines, 
acceptable contraceptive methods are limited to those which inhibit ovulation as the 
primary mode of action. 
Note: Periodic abstinence (calendar, sympto-thermal, post-ovulation methods), withdrawal 
(coitus interruptus), spermicides only, and lactational amenorrhoea method (LAM) are not 
acceptable methods of contraception. Male condom and female condom should not be used 
together (due to risk of failure with friction) 
10.4.3. 
Collection of Pregnancy Information: 
Male participants with partners who become pregnant 
• 
Investigator will attempt to collect pregnancy information on any male participant’s 
female partner of a male study participant who becomes pregnant while participating 
in this study. 
• 
After obtaining the necessary signed informed consent from the pregnant female 
partner directly, the investigator will record pregnancy information on the 
appropriate form and submit it to GSK within 24 hours of learning of the partner’s 
pregnancy. 
• 
The female partner will also be followed to determine the outcome of the pregnancy. 
Information on the status of the mother and child will be forwarded to GSK. 
• 
Generally, follow-up will be no longer than 6 to 8 weeks following the estimated 
delivery date. Any termination of the pregnancy will be reported regardless of fetal 
status (presence or absence of anomalies) or indication for procedure. 

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Female Participants who become pregnant 
• 
Investigator will collect pregnancy information on any female participant, who 
becomes pregnant while participating in this study. 
• 
The initial information will be recorded on the appropriate form and submitted to 
GSK within 24 hours of learning of a participant's pregnancy. 
• 
Participant will be followed to determine the outcome of the pregnancy. The 
investigator will collect follow up information on participant and neonate, which will 
be forwarded to GSK Generally, follow-up will not be required for longer than 6 to 8 
weeks beyond the estimated delivery date. 
• 
Any termination of pregnancy will be reported, regardless of fetal status (presence or 
absence of anomalies) or indication for procedure. 
• 
While pregnancy itself is not considered to be an AE or SAE, any pregnancy 
complication or elective termination of a pregnancy for medical reasons will be 
reported as an AE or SAE. 
• 
A spontaneous abortion (occurring at < 22 weeks gestational age) or still birth 
(occurring at > 22 weeks gestational age) is always considered to be an SAE and will 
be reported as such. 
• 
Any SAE occurring as a result of a post-study pregnancy which is considered 
reasonably related to the study intervention by the investigator, will be reported to 
GSK as described in Appendix 3. While the investigator is not obligated to actively 
seek this information in former study participants, he or she may learn of an SAE 
through spontaneous reporting. 
• 
Any female participant who becomes pregnant while participating will discontinue 
study intervention or be withdrawn from the study. 

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10.5. 
Appendix 5: ECOG Performance Status 
Grade 
Descriptions 
[Oken, 1982] 
CCI - This section contained Clinical Outcome Assessment data collection questionnaires or indices, which are protected 
by third party copyright laws and therefore have been excluded.

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10.6. 
Appendix 6: Renal Function Measures 
CKD-EPI Formula 
Chronic Kidney Disease (CKD) stage: Kidney Disease Outcomes Quality Initiative 
(KDOQI) CKD stages 3/4/5 defined by estimated glomerular filtration rate (eGFR) using 
the CKD Epidemiology Collaboration (CKD-EPI) formula [Levey, 2009]. 
GFR = 141 × min (Scr /κ, 1)α × max(Scr /κ, 1)-1.209 × 0.993Age × 1.018 [if female] × 
1.159 [if black] 
where: 
Scr is serum creatinine in mg/dL, 
κ is 0.7 for females and 0.9 for males, 
α is -0.329 for females and -0.411 for males, 
min indicates the minimum of Scr /κ or 1, and 
max indicates the maximum of Scr /κ or 1. 
Cockcroft-Gault Formula 
The Cockcroft-Gault formula is a commonly-used surrogate marker for actual creatinine 
clearance (CrCl) and employs creatinine measurements and a participant's weight (kg) to 
predict the clearance.  
If the participant is obese (>30% over ideal body weight), use ideal body weight in 
calculation of estimated CrCl. 
If the participant is below ideal body weight, use actual body weight in calculation of 
estimated CrCl. 
Cockcroft-Gault Formula for serum creatinine in mmol/L 
 
 
 
CrCl (mL/min) = 
Q X (140-age [years]) X actual body weight (kg)a 
 
814 X serum creatinine (mmol/L) 
Q=0.85 for females 
Q=1.0 for males 
OR 
a. Calculation of Ideal Body Weight Using the Devine Formula [Devine, 1974] 
Male participants: 
 
 
 
50.0 kg + (2.3 kg X each inch over 5 feet) 
or 
50.0 kg + (0.906 kg X each cm over 152.4 cm) 
Female 
participants: 
 
 
 
45.5 kg + (2.3 kg X each inch over 5 feet) 
or 
45.5 kg + (0.906 kg X each cm over 152.4 cm) 

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Cockcroft-Gault Formula for serum creatinine in mg/dL 
 
For example: 
For a male participant with actual body weight = 90.0 kg and height = 68 inches, the 
calculation would be as follows: 
Ideal body weight= 50.0 + (2.3) (68-60) = 68.4 kg 
This participant’s actual body weight is >30% over ideal body weight. In this case, the 
participant’s ideal body weight of 68.4 kg should be used in calculating estimated 
creatinine clearance 

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10.7. 
Appendix 7: Genetics 
USE/ANALYSIS OF DNA 
• 
Genetic variation may impact a participant’s response to study intervention, 
susceptibility, severity and progression of disease. Variable response to study 
intervention may be due to genetic determinants that impact drug absorption, 
distribution, metabolism, and excretion; mechanism of action of the drug; disease 
etiology; and/or molecular subtype of the disease being treated. Therefore, where 
local regulations and IRB/IEC allow, a blood sample will be collected for DNA 
analysis 
• 
DNA samples will be used for research related to study intervention or HNSCC and 
related diseases. They may also be used to develop tests/assays including diagnostic 
tests related to study intervention or study interventions of this drug class, and 
HNSCC. Genetic research may consist of the analysis of one or more candidate 
genes or the analysis of genetic markers throughout the genome or analysis of the 
entire genome (as appropriate) 
• 
DNA samples will be analyzed as described in exploratory study 
objectives/endpoints (refer to Section 3). A detailed description of analyses will be 
documented in a statistical analysis plan prior to initiation of analyses. Planned 
analyses and results of genetic investigations will be reported either as part of the 
clinical statistical analysis plan and clinical study report (CSR), or in a separate 
genetics statistical analysis plan and report, as appropriate. Additional analyses may 
be conducted if it is hypothesized that this may help further understand the clinical 
data.  
• 
The samples may be analyzed as part of a multi-study assessment of genetic factors 
involved in the response to study intervention or study treatments of this class. The 
results of genetic analyses may be reported in the clinical study report or in a 
separate study summary. 
• 
The sponsor will store the DNA samples in a secure storage space with adequate 
measures to protect confidentiality.  
• 
The samples will be retained while research on study intervention (or study 
interventions of this class) or HNSCC continues but no longer than 15 years after the 
last participant last visit or other period as per local requirements. 

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10.8. 
Appendix 8: Liver Safety: Required Actions, Follow-up 
Assessments and Study Intervention Rechallenge 
Guidelines 
Figure 2 
Liver Stopping Algorithm and Monitoring Event Algorithm1 
 
1.Study intervention refers to study drugs that comprise a study treatment arm. The 
algorithm/guideline applies to all study drugs. 
Table 17 
Liver Chemistry Stopping Criteria –Liver Stopping Event 
Event 
Criteria 
ALT-absolute 
Both ALT  8xULN and 2X baseline value 
ALT Increase 
Both ALT  3xULN and 1.5 X baseline value that persists for 
4 weeks 
Bilirubin1, 2 
ALT  3xULN and bilirubin  2xULN (>35% direct bilirubin)  
INR2  
ALT  3xULN and INR>1.5 
Cannot Monitor 
Both ALT  3xULN and ≥ 1.5x baseline value and cannot be 
monitored weekly for 4 weeks 

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Event 
Criteria 
Symptomatic3 
Both ALT  3xULN and ≥ 1.5x baseline value associated with 
symptoms (new or worsening) believed to be related to liver 
injury or hypersensitivity 
Required Actions and Follow up Assessments following ANY Liver Stopping 
Event4 
Actions 
Follow Up Assessments 
• Immediately discontinue study drug(s) 
• Report the event to GSK within 24 
hours 
• Complete the liver event CRF and 
complete SAE data collection tool if the 
event also meets the criteria for an SAE2 
• Perform liver event follow up 
assessments  
• Monitor the participant until liver 
chemistries resolve, stabilize, or return to 
within baseline (see MONITORING 
below) 
• Do not restart/rechallenge participant 
with study drug(s) unless allowed per 
protocol and GSK Medical Governance 
approval is granted (refer to Section 
7.1.2.1)  
• If restart/rechallenge not allowed or not 
granted, permanently discontinue study 
drug(s) and may continue participant in 
the study for any protocol specified 
follow up assessments  
 
 
MONITORING: 
For bilirubin or INR criteria:  
• Repeat liver chemistries (include ALT, 
AST, alkaline phosphatase, bilirubin and 
• Viral hepatitis serology5 
• Obtain INR and recheck with each 
liver chemistry assessment until the 
transaminase values show downward 
trend 
• Blood samples for pharmacokinetic 
(PK) analysis of each study drug, 
obtained within 48 hours after last 
dose6 
• Serum creatine phosphokinase (CPK) 
and lactate dehydrogenase (LDH) 
• Fractionate bilirubin, if total 
bilirubin2xULN 
• Obtain complete blood count with 
differential to assess eosinophilia 
• Record the appearance or worsening 
of clinical symptoms of liver injury, or 
hypersensitivity, on the AE report 
form 
• Record use of concomitant 
medications on the concomitant 
medications report form including 
acetaminophen, herbal remedies, other 
over the counter medications 
• Record alcohol use on the liver event 
alcohol intake case report form 
For bilirubin or INR criteria: 
• Anti-nuclear antibody, anti-smooth 
muscle antibody, Type 1 anti-liver 
kidney microsomal antibodies, and 

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INR) and perform liver event follow up 
assessments within 24 hours 
• Monitor participant twice weekly until 
liver chemistries resolve, stabilize or 
return to within baseline 
• A specialist or hepatology consultation is 
recommended 
For All other criteria:  
• Repeat liver chemistries (include ALT, 
AST, alkaline phosphatase, bilirubin and 
INR) and perform liver event follow up 
assessments within 24-72 hours 
• Monitor participant weekly until liver 
chemistries resolve, stabilize or return to 
within baseline 
quantitative total immunoglobulin G 
(IgG or gamma globulins) 
• Serum acetaminophen adduct HPLC 
assay (quantifies potential 
acetaminophen contribution to liver 
injury in participants with definite or 
likely acetaminophen use in the 
preceding week [James, 2009]). 
NOTE: not required in China 
• Liver imaging (ultrasound, magnetic 
resonance, or computerized 
tomography) and /or liver biopsy to 
evaluate liver disease; complete Liver 
Imaging and/or Liver Biopsy CRF 
forms 
1. Serum bilirubin fractionation should be performed if testing is available. If serum bilirubin 
fractionation is not immediately available, discontinue study drug(s) for that participant if ALT  
3xULN and bilirubin  2xULN. Additionally, if serum bilirubin fractionation testing is unavailable, 
record presence of detectable urinary bilirubin on dipstick, indicating direct bilirubin elevations 
and suggesting liver injury 
2. All events of ALT  3xULN and bilirubin  2xULN (>35% direct bilirubin) or ALT  3xULN and 
INR>1.5, which may indicate severe liver injury (possible ‘Hy’s Law’), must be reported as an SAE 
(excluding studies of hepatic impairment or cirrhosis); the INR threshold value stated will not apply 
to participants receiving anticoagulants 
3. New or worsening symptoms believed to be related to liver injury (such as fatigue, nausea, vomiting, 
right upper quadrant pain or tenderness, or jaundice) or believed to be related to hypersensitivity (such 
as fever, rash or eosinophilia)  
4. Study drugs refer to all drugs that comprise a study treatment arm. Refer to the central laboratory 
manual for instructions on sample requirements for follow-up tests performed at central laboratory. 
5. Includes: Hepatitis A IgM antibody; Hepatitis B surface antigen and Hepatitis B Core Antibody (IgM); 
Hepatitis C RNA; Cytomegalovirus IgM antibody; Epstein-Barr viral capsid antigen IgM antibody (or 
if unavailable, obtain heterophile antibody or monospot testing); Hepatitis E IgM antibody.  
6. Record the date/time of the PK blood sample draw and the date/time of the last dose of study drug 
prior to blood sample draw on the CRF. If the date or time of the last dose is unclear, provide the 
participant’s best approximation. If the date/time of the last dose cannot be approximated OR a PK 
sample cannot be collected in the time period indicated above, do not obtain a PK sample. Instructions 
for sample handling and shipping are in the SRM. 

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Table 18 
Liver Chemistry Increased Monitoring Criteria – Liver Monitoring 
Event 
Criteria 
Actions 
 
ALT 3xULN and ≥ 1.5x baseline value 
and not meeting any stopping criteria 
without symptoms believed to be 
related to liver injury or 
hypersensitivity, and who can be 
monitored weekly for 4 weeks. 
 
• Notify the GSK medical monitor within 
24 hours of learning of the abnormality 
to discuss participant safety.  
• Participant can continue study drug(s) 
• Participant must return weekly for repeat 
liver chemistries (ALT, AST, alkaline 
phosphatase, bilirubin) until they resolve, 
stabilize or return to within baseline  
• If at any time participant meets the liver 
chemistry stopping criteria, proceed as 
described above 
• If, after 4 weeks of monitoring, ALT 
<3xULN and <1.5 X baseline value, and 
bilirubin <2xULN, monitor participants 
twice monthly until liver chemistries 
normalize or return to within baseline 
10.8.1. 
Study Intervention Rechallenge Guidelines 
10.8.1.1. 
Rechallenge Following Liver Stopping Events that are Possibly Related 
to Study Treatment 
Following drug-induced liver injury, drug rechallenge is associated with a 13% 
mortality across all drugs in prospective studies [Andrade, 2009]. Clinical outcomes 
vary by drug, with nearly 50% fatality with halothane readministered within one month 
of initial injury. However, some drugs seldom result in recurrent liver injury or fatality. 
Risk factors for a fatal drug rechallenge outcome include: 
• 
Hypersensitivity [Andrade, 2009] with initial liver injury (e.g. fever, rash, 
eosinophilia) 
• 
Jaundice or bilirubin >2xULN with initial liver injury (direct bilirubin >35% of 
total) 
• 
Participant currently exhibits severe liver injury defined by: ALT >3xULN, 
bilirubin >2xULN (direct bilirubin >35% of total), or INR>1.5 
• 
Serious adverse event or fatality has earlier been observed with drug 
rechallenges [Hunt, 2010; Papay, 2009] 
• 
Evidence of drug-related preclinical liability (e.g. reactive metabolites; 
mitochondrial impairment [Hunt, 2010]) 

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Rechallenge refers to resuming study treatment following drug induced liver injury 
(DILI). Because of the risks associated with rechallenge after DILI this should only be 
considered for a participant for whom there is compelling evidence of benefit from a 
critical or life-saving medicine, there is no alternative approved medicine available, and a 
benefit:risk assessment of rechallenge is considered to be favorable. 
Approval by GSK for rechallenge with study treatment can be considered where: 
• 
Investigator requests consideration of rechallenge with study treatment for a 
participant who is receiving compelling benefit with study treatment that exceeds 
risk, and no effective alternative therapy is available. 
• 
Ethics Committee or Institutional Review Board approval for rechallenge with study 
treatment must be obtained, as required. 
• 
If the rechallenge is approved by GSK Medical Governance in writing, the 
participant must be provided with a clear description of the possible benefits and 
risks of study treatment administration, including the possibility of recurrent, more 
severe liver injury or death. 
• 
The participant must also provide signed informed consent specifically for the 
rechallenge with study treatment.  Documentation of informed consent must be 
recorded in the study chart. 
• 
Study treatment must be administered at the dose specified by GSK. 
• 
Participants approved by GSK Medical Governance for rechallenge with study 
treatment must return to the clinic twice a week for liver chemistry tests until stable 
liver chemistries have been demonstrated and then standard laboratory monitoring 
may resume as per protocol. 
• 
If after study treatment rechallenge, participant meets protocol-defined liver 
chemistry stopping criteria, study treatment should be permanently discontinued. 
• 
GSK Medical Monitor, and the Ethics Committee or Institutional Review Board as 
required, must be informed of the participant’s outcome following study treatment 
rechallenge.  
• 
GSK to be notified of any adverse events, as per Section 10.3. 
10.8.1.2. 
Restart Following Transient Resolving Liver Stopping Events NOT 
Related to Study Treatment 
Restart refers to resuming study intervention following liver stopping events in which 
there is a clear underlying cause (other than DILI) of the liver event (e.g. biliary 
obstruction, pancreatic events, hypotension, acute viral hepatitis). Furthermore, restart is 
not permitted following liver stopping event when the underlying cause was alcohol-
related hepatitis. 
Approval by GSK for study treatment restart can be considered where: 

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• 
Investigator requests consideration for study treatment restart if liver chemistries 
have a clear underlying cause (e.g., biliary obstruction, hypotension and liver 
chemistries have improved to normal or are within 1.5 x baseline and ALT 
<3xULN). 
• 
Possible study intervention-induced liver injury has been excluded by the 
investigator and the study team. This includes the absence of markers of 
hypersensitivity (otherwise unexplained fever, rash, eosinophilia). If study 
intervention-related liver injury cannot be excluded, the guidance on rechallenge in 
Section 10.8.1.1 will apply. 
• 
There is no evidence of alcohol-related hepatitis 
• 
Ethics Committee or Institutional Review Board approval of study treatment restart 
must be obtained, as required. 
• 
If restart of study treatment is approved by GSK Medical Governance in writing, the 
participant must be provided with a clear description of the possible benefits and 
risks of study treatment administration, including the possibility of recurrent, more 
severe liver injury or death. 
• 
The participant must also provide signed informed consent specifically for the study 
treatment restart. Documentation of informed consent must be recorded in the study 
chart. 
• 
Study treatment must be administered at the dose specified by GSK. 
• 
Participants approved by GSK Medical Governance for restarting study treatment 
must return to the clinic once a week for liver chemistry tests until stable liver 
chemistries have been demonstrated and then laboratory monitoring may resume as 
per protocol. 
• 
If after study treatment re-start, participant meets protocol-defined liver chemistry 
stopping criteria, follow usual stopping criteria instructions. 
• 
GSK Medical Monitor, and the Ethics Committee or Institutional Review Board as 
required, must be informed of the participant’s outcome following study treatment 
restart. 
• 
GSK to be notified of any adverse events, as per Section 10.3. 

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10.9. 
Appendix 9: Country Specific Amendments 
Not Applicable. 

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10.10. 
Appendix 10: Abbreviations and Trademarks 
Abbreviations 
5FU 
Fluorouracil 
ADA 
Anti-drug antibodies 
AE 
Adverse Event 
AESI 
Adverse Events of Special Interest 
ALT 
Alanine Aminotransferase 
ANC 
Absolute Neutrophil Count 
AST 
Aspartate Aminotransferase 
AUC 
Area under the curve 
-hCG 
Beta-human chorionic gonadotropin 
BPI-SF I3 
Brief Pain Inventory-Short Form Item 3 
cfDNA 
Cell-free DNA 
cfRNA 
Cell-free RNA 
CI 
Confidence Interval 
CKD-EPI 
Chronic Kidney Disease Epidemiology Collaboration 
Cmax 
Maximum observed concentration 
Ctrough 
Lowest Observed Concentration; 
CNS 
Central Nervous System 
CPD 
Confirmed Progressive Disease 
CR 
Complete Response 
CrCl 
Creatinine Clearance 
CRP 
C Reactive Protein 
CRS 
Cytokine Release Syndrome 
CSR 
Clinical Study Report 
CT 
Computed Tomography 
CTLA-4 
Cytotoxic T-Lymphocyte-Associated Protein 4  
CV 
Cardiovascular 
DCR 
Disease Control Rate 
DILI 
Drug-induced Liver Injury 
DNA 
Deoxyribonucleic Acid 
DoR 
Duration of Response 
ECHO 
Echocardiogram 
ECI 
Events of Clinical Interest 
ECOG 
Eastern Cooperative Oncology Group 
eCRF 
electronic Case Report Form 
EORTC IL50 
European Organization for Research and Treatment of 
Cancer Item Library 50 (a subset of domains from the 
EORTC QLQ-C30) 
EORTC IL51 
European Organization for Research and Treatment of 
Cancer Item Library 51 (a subset of domains from the 
EORTC QLQ-HN35) 
EORTC QLQ C30 
European Organization for Research and Treatment of 
Cancer Quality of Life Questionnaire – 30 item Core 
Module 

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EU 
European Union 
FACT-G 
Functional Assessment of Cancer Therapy - General 
Fc 
Fragment Crystallizable 
FcR 
FC-gamma Receptor 
FDA 
Food and Drug Administration 
FDG-PET 
Fluorodeoxyglucose Positron Emission Tomography 
FTIH 
First-time-in-human 
GSK 
GlaxoSmithKline 
H 
Hypothesis 
HNSCC 
Head and Neck Squamous Cell Carcinoma/Cancer 
HPV 
Human Papilloma Virus 
HRQoL 
Health-related Quality of Life 
HRT 
Hormone Replacement Therapy 
IB 
Investigator’s Brochure 
ICF 
Informed Consent Form 
ICH 
International Council on Harmonization of Technical 
Requirements for Registration of Pharmaceuticals for 
Human Use 
ICOS 
Inducible T Cell Co-Stimulatory Receptor 
IDMC 
Independent Data Monitoring Committee 
IEC 
Independent Ethics Committees 
IFN 
Interferon, gamma 
Ig 
Immunoglobulin 
IHC 
Immunohistochemistry 
IL 
Interleukin 
INR 
International Normalized Ratio 
irAE 
Immune-related Adverse Event 
IRB 
Institutional Review Board 
iRECIST 
Immune-based RECIST 
IRR 
Infusion-related Reactions 
IRT 
Interactive Response Technology 
IV 
Intravenous 
kg 
Kilogram(s) 
KN 
KEYNOTE 
LVEF 
Left Ventricular Ejection Fraction 
mAb 
Monoclonal Antibody 
MedDRA 
Medical Dictionary for Regulatory Activities 
g 
Microgram(s) 
mg 
Milligram(s) 
mmHg 
Millimeters of Mercury 
mL 
Milliliter(s) 
MRI 
Magnetic Resonance Imaging 
MSDS 
Material Safety Data Sheet 
MSEC 
Millisecond(s) 
MTD 
Maximum Tolerated Dose 
MUGA 
Multigated Acquisition Scan 

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NCI-CTCAE 
National Cancer Institute - Common Toxicity Criteria for 
Adverse Events  
NGS 
Next Generation Sequencing 
NK 
Natural Killer 
nM 
Nanomolar(s) 
ORR 
Overall Response Rate 
OS 
Overall Survival 
PBMC 
Peripheral Blood Mononuclear Cell 
PD 
Progressive Disease 
PD-1 
Programmed Death Receptor Protein 1 
PD-L 
PD Ligand 
PFS 
Progression-free Survival 
PK 
Pharmacokinetics 
PR 
Partial Response 
PS 
Performance Status 
Q2W 
Every 2 Weeks 
Q3W 
Every 3 Weeks 
Q6W 
Every 6 Weeks 
Q12W 
Every 12 Weeks 
QTc 
QT interval duration corrected 
R/M 
Recurrent/Metastatic 
RANKL 
Receptor Activator of Nuclear Factor-kappa B Ligand 
RECIST 
Response Evaluation Criteria in Solid Tumors 
RNA 
Ribonucleic Acid 
RO 
Receptor Occupancy 
SAE 
Serious Adverse Event 
SD 
Stable Disease 
SRM 
Study Reference Manual 
TCR 
T Cell Receptor 
TDV 
Treatment Discontinuation Visit 
TIL 
Tumor Infiltrating Lymphocytes 
TNF 
Tumor Necrosis Factor, alpha 
Treg 
T Regulatory Cells 
TSH 
Thyroid Stimulating Hormone 
TTD 
Time to Deterioration 
ULN 
Upper Limit of Normal 
UPD 
Unconfirmed Progressive Disease 
UPM 
Unit Probability Mass 
US 
United States 
WOCBP 
Woman of Childbearing Potential 
 
Trademark Information 
Trademarks of the GlaxoSmithKline 
group of companies 
 
Trademarks not owned by the 
GlaxoSmithKline group of companies 
None 
 
Keytruda 

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10.11. 
Appendix 11: Immune-related Diseases 
Table 19 
Potential Immune-mediated Diseases 
Neuroinflammatory Disorders 
Musculoskeletal Disorders 
Skin Disorders 
• 
Cranial nerve disorders, 
including 
paralyses/paresis (e.g. 
Bell’s palsy) 
• 
Optic neuritis 
• 
Multiple sclerosis  
• 
Transverse myelitis 
• 
Guillain-Barré 
syndrome, including 
Miller Fisher syndrome 
and other variants 
• 
Acute disseminated 
encephalomyelitis, 
including site specific 
variants: e.g. non-
infectious encephalitis, 
encephalomyelitis, 
myelitis, 
myeloradiculoneuritis 
• 
Myasthenia gravis, 
including Lambert-
Eaton myasthenic 
syndrome  
• 
Immune-mediated 
peripheral neuropathies 
and plexopathies, 
(including chronic 
inflammatory 
demyelinating 
polyneuropathy, 
multifocal motor 
neuropathy and 
polyneuropathies 
associated with 
monoclonal 
gammopathy). 
• 
Narcolepsy 
• 
Systemic lupus 
erythematosus and 
associated conditions 
• 
Systemic Scleroderma 
(Systemic sclerosis), 
including diffuse 
systemic form and 
CREST syndrome 
• 
Idiopathic 
inflammatory 
myopathies, including 
Dermatomyositis, 
Polymyositis, 
• 
Antisynthetase 
syndrome 
• 
Rheumatoid arthritis 
and associated 
conditions including 
Juvenile chronic 
arthritis and Still’s 
disease) 
• 
Polymyalgia 
rheumatica  
• 
Spondyloarthritis, 
including ankylosing 
spondylitis, reactive 
arthritis (Reiter's 
Syndrome) and 
undifferentiated 
spondyloarthritis 
• 
Psoriatic arthropathy 
• 
Relapsing 
polychondritis 
• 
Mixed connective 
tissue disorder 
• 
Psoriasis 
• 
Vitiligo 
• 
Erythema nodosum 
• 
Autoimmune bullous 
skin diseases (including 
pemphigus, pemphigoid 
and dermatitis 
herpetiformis) 
• 
Alopecia areata 
• 
Lichen planus 
• 
Sweet’s syndrome 
• 
Localized Scleroderma 
(Morphoea) 
Liver disorders 
Gastrointestinal disorders 
Endocrine disorders 
• 
Autoimmune hepatitis 
• 
Primary biliary 
cirrhosis 
• 
Primary sclerosing 
cholangitis 
• 
Autoimmune 
cholangitis. 
• 
Inflammatory Bowel 
disease, including 
Crohn’s disease, 
ulcerative colitis, 
microscopic colitis, 
ulcerative proctitis 
• 
Celiac disease 
• 
Autoimmune 
pancreatitis 
• 
Autoimmune thyroiditis 
(including Hashimoto 
thyroiditis) 
• 
Grave's or Basedow’s 
disease 
• 
Diabetes mellitus type I 
• 
Addison’s disease 
• 
Polyglandular 
autoimmune syndrome 
• 
Autoimmune 
hypophysitis 

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Vasculitides 
Blood disorders 
Others 
• 
Large vessels vasculitis 
including: giant cell 
arteritis such as 
Takayasu's arteritis and 
temporal arteritis.  
• 
Medium sized and/or 
small vessels vasculitis 
including: polyarteritis 
nodosa, Kawasaki's 
disease, microscopic 
polyangiitis, Wegener's 
granulomatosis, Churg–
Strauss syndrome 
(allergic granulomatous 
angiitis), Buerger’s 
disease 
(thromboangiitis 
obliterans), necrotizing 
vasculitis and anti-
neutrophil cytoplasmic 
antibody (ANCA) 
positive vasculitis (type 
unspecified), Henoch-
Schonlein purpura, 
Behcet's syndrome, 
leukocytoclastic 
vasculitis. 
• 
Autoimmune hemolytic 
anemia 
• 
Autoimmune 
thrombocytopenia 
• 
Antiphospholipid 
syndrome 
• 
Pernicious anemia 
• 
Autoimmune aplastic 
anemia 
• 
Autoimmune 
neutropenia  
• 
Autoimmune 
pancytopenia 
• 
Autoimmune 
glomerulonephritis 
(including IgA 
nephropathy, 
glomerulonephritis 
rapidly progressive, 
membranous 
glomerulonephritis, 
membranoproliferative 
glomerulonephritis, and 
mesangioproliferative 
glomerulonephritis) 
• 
Ocular autoimmune 
diseases (including 
autoimmune uveitis and 
autoimmune 
retinopathy) 
• 
Autoimmune 
myocarditis/cardiomyo
pathy 
• 
Sarcoidosis 
• 
Stevens-Johnson 
syndrome 
• 
Sjögren’s syndrome 
• 
Idiopathic pulmonary 
fibrosis 
• 
Goodpasture syndrome 
• 
Raynaud’s phenomenon 

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10.12. 
Appendix 12: Protocol Amendment History 
The Protocol Amendment Summary of Changes Table for the current amendment is 
located directly before the Table of Contents (TOC). 
Amendment 1: 13-APR-2020 
Overall Rationale for the Amendment: The primary rationale for the amendment was 
to account for a study design update from a Phase III study to an adaptive Phase II/III 
study which allows for a proper balance of the risk and benefit of a Phase III expansion 
decision. Additional updates included were: eligibility criteria to address high risk of 
bleeds that are a feature inherent to the underlying disease of a population with HNSCC 
and define unstable medical condition; definition of second course of study treatment that 
was expanded to include participants who complete 35 cycles of study treatment. 
Section # and Name 
Description of Change 
Brief Rationale 
1.1 Synopsis – Overall 
Design 
Added detail for adaptive 
Phase II/III study design. 
To describe the updated study 
design  
1.1 Synopsis – Number 
of Participants 
Modified participant 
numbers 
To adjust for the adaptive 
Phase II/III design 
Synopsis – Intervention 
Groups and Duration, 
1.3 Schedule of 
Activities, 6.1 Study 
Intervention 
Administered 
Added “approximately” to 
2 years of treatment 
To allow for possible delays in 
dosing to cover 35 cycles 
1.2 Schema 
Added schema for the 
adaptive Phase II/III 
design 
To provide clarity for the 
adaptive Phase II/III study 
design 
1.3 Schedule of 
Activities 
Added a window for 
Physical Examinations, 
added Coagulation 
assessments, removed 
chemotherapy treatment at 
Week 18, added notes for 
Immunogenicity, fresh 
tumor and patient reported 
outcomes (PRO) 
collections 
To provide clarity for 
assessments 
3 Objectives and 
Endpoints 
Added DCR per iRECIST 
as exploratory endpoint 
DCR an intended exploratory 
endpoint 
4.1 Overall Design, 4.2 
Scientific Rationale for 
Added detail for adaptive 
To provide description for the 
adaptive Phase II/III study 

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Section # and Name 
Description of Change 
Brief Rationale 
Study Design 
Phase II/III study design 
design 
5.2 Exclusion Criteria 
Added criteria for 
exclusion of patients with 
high risk of bleeding and 
clarification for the 
definition of 
severe/unstable medical 
conditions 
In response to high risk of 
bleeds that are an  inherent 
feature in HNSCC; provided 
clarification to eligibility 
requiring definition which 
included Grade 3/Grade 4 
hypercalcemia 
6.1 Study 
Intervention(s) 
Administered 
Added that participants 
should remain under 
observation at the study 
site post-study treatment 
infusion per the judgement 
of the investigator 
In response to request from an 
EC to provide guidance on 
observation period post 
infusions 
6.1.1 Duration of 
Second Course 
New section added to 
address retreatment after 
CR that results in early 
study treatment 
discontinuation or 
completion of maximum 
allows 35 cycles number 
of study treatment 
To provide participants the 
option to restart study 
treatment upon progression 
after achieving a response 
6.3 Measures to 
Minimize Bias: 
Randomization and 
Blinding 
Included summary details 
on the unblinding process 
for investigators 
To provide general information 
on the unblinding process 
6.5.1 Permitted 
Medications and Non-
drug Therapies 
Expanded language to 
include bisphosphonates 
and other supportive care 
medications 
To provide clarification of 
permitted supportive care 
medications 
6.5.2 Prohibited 
Medications and Non-
drug Therapies 
Prohibit use of steroids 
>10 mg per day 
To align with permitted steroid 
use of up to 10mg 
7.1 Discontinuation of 
Study Intervention 
Added language to address 
retreatment defined as 
Second Course 
To allow participants to have 
the option for  retreatment 
upon progression after 
achieving a response/stable 
disease 
8.8 Biomarkers and 
Added additional 
To clarify timepoints of tissue 

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Section # and Name 
Description of Change 
Brief Rationale 
8.8.3 Tumor Tissue 
information on timepoints 
for optional tumor tissue 
biopsy collections 
collections 
9. Statistical 
Considerations 
Added the study statistical 
primary objective to the 
beginning of the section 
To clarify the primary 
objective of the study upfront 
9.2 Sample Size 
Determination 
Added language to 
confirm the number of 
study participants required 
for the adaptive Phase 
II/III study design 
To clarify number of study 
participants for the adaptive 
Phase II/III study design 
9.2.1 Phase III Study 
with No Pause of 
Enrollment 
Added language to 
describe the analysis and 
timings for the adaptive 
Phase II/III study design if 
the INDUCE-3 study 
(209229) is positive 
To clarify the analysis 
definition for the adaptive 
Phase II/III study design 
9.2.1 Phase II/III Study 
with Pause of 
Enrollment 
Added language to 
describe the analysis and 
timings for the expansion 
to Phase III 
To clarify the analysis 
definition for the adaptive 
Phase II/III study design 
9.5 Interim Analyses 
Updated Sample Size 
Table 13 and Table 14 for 
adaptive design options 
To clarify the expected number 
of events at the planned 
analysis for the adaptive study 
design 
9.7 Blinded 
Independent Central 
Review 
Updated BICR auditing 
size strategy and the 
maximum acceptable 
HRR, 
To align with revised 
alternative hypothesis for PFS 
9.8 Multiplicity 
Updated multiplicity 
testing strategy 
To clarify for the adaptive 
study design 
2.1 Study Rationale, 2.3 
Benefit/Risk 
Assessment, 6.2 
Preparation/Handling 
/Storage/Accountability, 
8. Study Assessments 
and Procedures 
 
Administrative corrections 
 

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