A Phase 2, Adaptive, Open-Label, Multiple-Dose, Dose-Escalation Study to Evaluate the Efficacy, Safety, Tolerability, and Pharmacokinetics of Intravenous AMB-05X in Subjects With Tenosynovial Giant Cell Tumor
Phase: PHASE2
Conditions: Tenosynovial Giant Cell Tumor, Pigmented Villonodular Synovitis, TGCT, PVNS - Pigmented Villonodular Synovitis
Sponsor: AmMax Bio, Inc.



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INVESTIGATOR’S SIGNATURE 
Title: 
A Phase 2, Adaptive, Open-Label, Multiple-Dose, Dose-Escalation Study 
to Evaluate the Efficacy, Safety, Tolerability, and Pharmacokinetics of 
Intravenous AMB-05X in Subjects with Tenosynovial Giant Cell Tumor 
Protocol Number: 
AMB-051-02 
I confirm that I have read this protocol. I will comply with the protocol, with statutory 
requirements as described in the United States Code of Federal Regulations (CFR) Title 21 
Parts 11, 50, 54, 56, and 312 or local requirements in the countries where the study is 
performed, with the principles of Good Clinical Practice (GCP) in relevant guidance 
documents from the International Council for Harmonisation of Technical Requirements for 
Pharmaceuticals for Human Use (ICH), and with the ethical principles of the Declaration of 
Helsinki. 
I will provide copies of the protocol and all pertinent information to all study center personnel 
who participate in the conduct of this clinical study. I will discuss this material with them to 
ensure that they are fully informed regarding the study drug, the conduct of the study, and the 
obligations of confidentiality. 
 
 
 
Principal Investigator Name (printed) 
 
Signature 
 
 
 
Date 
 
Study Center Number 
 
 
 
Institution Name 
 
City, State or Province, Country 
 

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TABLE OF CONTENTS 
SPONSOR APPROVAL .................................................................................................................2 
INVESTIGATOR’S SIGNATURE .................................................................................................3 
CONTACTS IN THE EVENT OF AN EMERGENCY..................................................................4 
TABLE OF CONTENTS .................................................................................................................5 
LIST OF TABLES ...........................................................................................................................9 
LIST OF FIGURES .........................................................................................................................9 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS ................................................10 
1 
PROTOCOL SUMMARY ..........................................................................................12 
1.1 
Protocol Synopsis .......................................................................................................12 
1.2 
Schema ........................................................................................................................22 
1.3 
Schedule of Events .....................................................................................................23 
2 
INTRODUCTION ......................................................................................................25 
2.1 
Tenosynovial Giant Cell Tumor .................................................................................25 
2.2 
AMB-05X ...................................................................................................................26 
2.3 
Summary of Nonclinical Data ....................................................................................26 
2.3.1 
Pharmacology .............................................................................................................26 
2.3.2 
Pharmacokinetics ........................................................................................................27 
2.3.3 
Toxicology ..................................................................................................................27 
2.4 
Summary of Clinical Data ..........................................................................................28 
2.4.1 
Monotherapy Study ....................................................................................................28 
2.4.2 
Combination Study with Pembrolizumab ...................................................................29 
3 
OBJECTIVES AND ENDPOINTS ............................................................................32 
3.1 
Primary Endpoint ........................................................................................................32 
3.2 
Secondary Endpoints ..................................................................................................32 
3.2.1 
Efficacy Secondary Endpoints ....................................................................................32 
3.2.2 
Pharmacokinetic and Pharmacodynamic Secondary Endpoints .................................32 
4 
STUDY DESIGN .......................................................................................................33 
4.1 
Overall Design ............................................................................................................33 
4.1.1 
Study Visit Schedule ...................................................................................................33 

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4.1.2 
Adaptive Dose Cohorts and Data Monitoring Committee .........................................33 
4.1.3 
Subject Dose Reduction ..............................................................................................35 
4.2 
Justification for Dose ..................................................................................................35 
4.3 
End of Study Definition ..............................................................................................36 
4.4 
Subject Early Termination ..........................................................................................36 
5 
STUDY POPULATION .............................................................................................38 
5.1 
Inclusion Criteria ........................................................................................................38 
5.2 
Exclusion Criteria .......................................................................................................38 
5.3 
Contraception Guidelines ...........................................................................................39 
5.3.1 
Contraception Guidelines for Female Subjects ..........................................................39 
5.3.2 
Contraception Guidelines for Male Subjects ..............................................................40 
6 
STUDY INTERVENTION ........................................................................................42 
6.1 
Study Intervention Administration .............................................................................42 
6.1.1 
Study Intervention Description ...................................................................................42 
6.1.2 
Dosing and Administration .........................................................................................42 
6.2 
Preparation/Handling/Storage/Accountability ............................................................43 
6.2.1 
Acquisition and Accountability ..................................................................................43 
6.2.2 
Formulation, Appearance, Packaging, and Labeling ..................................................43 
6.2.3 
Product Storage and Stability .....................................................................................43 
6.2.4 
Disposal ......................................................................................................................44 
6.3 
Measures to Minimize Bias: Randomization and Blinding ........................................44 
6.4 
Study Intervention Compliance ..................................................................................44 
6.5 
Concomitant Therapy .................................................................................................44 
7 
STUDY ASSESSMENTS AND PROCEDURES ......................................................45 
7.1 
Screening Procedures ..................................................................................................45 
7.1.1 
Subject ID ...................................................................................................................45 
7.1.2 
Demographics and Medical History ...........................................................................45 
7.1.3 
Height .........................................................................................................................45 
7.1.4 
Tumor Biopsy .............................................................................................................45 
7.2 
Safety Assessments .....................................................................................................45 
7.2.1 
Vital Signs ..................................................................................................................45 

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7.2.2 
Physical Examination .................................................................................................46 
7.2.3 
Electrocardiogram .......................................................................................................46 
7.2.4 
Pregnancy Tests ..........................................................................................................46 
7.2.5 
Clinical Laboratory Tests ...........................................................................................46 
7.3 
Adverse Events and Serious Adverse Events .............................................................47 
7.3.1 
Definition of Adverse Event .......................................................................................47 
7.3.2 
Definition of Serious Adverse Event ..........................................................................48 
7.3.3 
Classification of an Adverse Event .............................................................................48 
7.3.3.1 
Severity .......................................................................................................................48 
7.3.3.2 
Relationship to Study Drug ........................................................................................48 
7.3.3.3 
Expectedness ...............................................................................................................49 
7.3.4 
Time Period and Frequency for Event Assessment and Follow-up ...........................50 
7.3.5 
Adverse Event Reporting ............................................................................................50 
7.3.6 
Serious Adverse Event Reporting and Follow-up ......................................................50 
7.3.7 
Reporting of Pregnancy ..............................................................................................51 
7.3.8 
Clinically Significant Adverse Events ........................................................................51 
7.3.8.1 
Dose-Limiting Toxicity ..............................................................................................51 
7.3.8.2 
Adverse Events of Special Interest .............................................................................52 
7.4 
Efficacy Assessments .................................................................................................52 
7.4.1 
Tumor Assessments ....................................................................................................52 
7.4.1.1 
MRI .............................................................................................................................52 
7.4.1.2 
Response Based on RECIST v1.1 ..............................................................................52 
7.4.1.3 
Response Based on Tumor Volume Score .................................................................52 
7.4.2 
Joint Range of Motion ................................................................................................53 
7.4.3 
PROMIS Physical Function Scale ..............................................................................53 
7.4.4 
Worst Stiffness Numeric Rating Scale .......................................................................53 
7.4.5 
Brief Pain Inventory Short Form and Worst Pain Numeric Rating Scale ..................53 
7.4.6 
EQ-5D-5L ...................................................................................................................54 
7.5 
Pharmacokinetic and Pharmacodynamic Assessments ..............................................54 
7.6 
Blood Sampling ..........................................................................................................55 
8 
ASSESSMENTS BY STUDY VISIT ........................................................................56 

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8.1 
Visit 1 / Screening ......................................................................................................56 
8.2 
Visit 2 / Baseline (Day 1) ...........................................................................................57 
8.2.1 
Pre-dose Procedures ....................................................................................................57 
8.2.2 
First Dose and Post-dose Procedures ..........................................................................57 
8.3 
Visit 3 (Week 2 r 2 Days) ..........................................................................................58 
8.4 
Visit 4 (Week 4 r 2 Days) ..........................................................................................58 
8.5 
Visit 5 (Week 6 r 3 Days) ..........................................................................................59 
8.6 
Visit 6 (Week 8 r 3 Days) ..........................................................................................60 
8.7 
Visit 7 (Week 10 r 3 Days) ........................................................................................60 
8.8 
Visit 8 (Week 12 r 3 Days) or Early Termination .....................................................61 
8.9 
Follow-up Visit 9 (Week 14 r 3 Days) ......................................................................62 
8.10 
Follow-up Visit 10 (Week 24 r 7 Days) ....................................................................62 
8.11 
Early Termination Procedures ....................................................................................63 
9 
STATISTICAL CONSIDERATIONS .......................................................................64 
9.1 
Sample Size Determination ........................................................................................64 
9.2 
Populations for Analyses ............................................................................................64 
9.3 
Statistical Analyses .....................................................................................................64 
9.3.1 
General Approach .......................................................................................................64 
9.3.2 
Handling Missing Data ...............................................................................................64 
9.3.3 
Demographics and Baseline Characteristics ...............................................................64 
9.3.4 
Safety Analyses ..........................................................................................................64 
9.3.5 
Efficacy Analyses .......................................................................................................65 
9.3.6 
Pharmacokinetic Analyses ..........................................................................................65 
10 
REGULATORY, ETHICAL, AND STUDY OVERSIGHT 
CONSIDERATIONS ..................................................................................................66 
10.1 
Administrative Procedures ..........................................................................................66 
10.1.1 
Ethics Review .............................................................................................................66 
10.1.2 
Good Clinical Practice ................................................................................................66 
10.1.3 
Informed Consent .......................................................................................................66 
10.1.4 
Subject Confidentiality ...............................................................................................67 
10.1.5 
Protocol Deviation ......................................................................................................67 

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10.1.6 
Protocol Amendment ..................................................................................................68 
10.1.7 
Study Termination ......................................................................................................68 
10.2 
Data Handling and Recordkeeping .............................................................................69 
10.2.1 
Source Documents and Electronic Case Report Forms ..............................................69 
10.2.2 
Retention of Records ..................................................................................................69 
10.3 
Study Oversight ..........................................................................................................70 
10.3.1 
Study Monitoring ........................................................................................................70 
10.3.2 
Audits and Inspections ................................................................................................70 
10.4 
Publication Policy .......................................................................................................71 
10.4.1 
Clinical Trial Database ...............................................................................................71 
10.4.2 
Publishing Study Results ............................................................................................71 
LIST OF REFERENCES ...............................................................................................................72 
APPENDIX 1. PROMIS PHYSICAL FUNCTION SCALE .....................................................74 
APPENDIX 2. WORST STIFFNESS NUMERIC RATING SCALE .......................................75 
APPENDIX 3. BRIEF PAIN INVENTORY SHORT FORM ...................................................76 
APPENDIX 4. EQ-5D-5L ..........................................................................................................77 
APPENDIX 5. COVID-19 CONTINGENCY PLAN ................................................................79 
COVID-19 Risk Mitigation ...........................................................................................................79 
Subject Disposition in the Event of COVID-19 Infection .............................................................79 
Regulatory and Study Oversight Considerations ...........................................................................79 
 
LIST OF TABLES 
Table 1. Clinical Laboratory Parameters .......................................................................................46 
 
LIST OF FIGURES 
Figure 1. Simulated Serum and Synovial Fluid AMB-05X Concentrations for the Cohort 
A Starting Dose Level ................................................................................................36 
 

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LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS 
Abbreviation 
Definition 
ADA 
anti-drug antibody 
AE 
adverse event 
ALT 
alanine aminotransferase 
AST 
aspartate aminotransferase 
ATC 
Anatomical Therapeutic Chemical (drug classification system) 
AUC 
area under the curve 
BPI 
Brief Pain Inventory 
CFR 
Code of Federal Regulations 
CIC 
circulating immune complex 
COVID-19 
coronavirus disease 2019 
CR 
complete response (in the context of tumor response) 
CSF1 
colony-stimulating factor 1 
CSF1R 
colony-stimulating factor 1 receptor 
CTCAE 
Common Terminology Criteria for Adverse Events 
DLT 
dose-limiting toxicity 
DMC 
data monitoring committee 
ECG 
electrocardiogram 
eCRF 
electronic case report form 
ET 
early termination 
FDA 
Food and Drug Administration 
FSH 
follicle-stimulating hormone 
GCP 
Good Clinical Practice 
HBV 
hepatitis B virus 
HCV 
hepatitis C virus 
HEENT 
head, eyes, ears, nose, throat 
HIPAA 
Health Insurance Portability & Accountability Act 
HIV 
human immunodeficiency virus 
IB 
Investigator’s Brochure 
ICF 
informed consent form 
ICH 
International Council for Harmonisation of Technical Requirements for 
Pharmaceuticals for Human Use 
IEC 
Independent Ethics Committee 
IL-34 
interleukin-34 
IRB 
Institutional Review Board 
IUD 
intrauterine device 
IUS 
intrauterine hormone-releasing system 
IV 
intravenous 
IWRS 
interactive web response system 
MedDRA 
Medical Dictionary for Regulatory Activities 
mITT 
Modified Intent to Treat (Population) 
MRI 
magnetic resonance imaging 

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Abbreviation 
Definition 
NRS 
numeric rating scale 
OR 
objective response (in the context of tumor response) 
ORR 
objective response rate (in the context of tumor response) 
PD 
pharmacodynamic(s) 
PD 
progressive disease (in the context of tumor response) 
PI 
Principal Investigator: the investigator who leads study conduct at an 
individual study center. Every study center has a Principal Investigator. 
PK 
pharmacokinetic(s) 
PP 
Per Protocol (Population) 
PR 
partial response (in the context of tumor response) 
PRO 
patient-reported outcome 
PROMIS 
Patient-Reported Outcomes Measurement Information System 
PT 
Preferred Term 
QTcF 
QT interval corrected with Fridericia’s formula 
RECIST 
Response Evaluation Criteria in Solid Tumors 
ROM 
range of motion 
SAE 
serious adverse event 
SAS 
Statistical Analysis System 
SD 
standard deviation 
SD 
stable disease (in the context of tumor response) 
SOC 
System Organ Class 
SUSAR 
suspected, unexpected serious adverse reaction 
TB 
tuberculosis 
TEAE 
treatment-emergent adverse event 
TGCT 
tenosynovial giant cell tumor 
TVS 
tumor volume score 
ULN 
upper limit of normal 
VAS 
visual analogue scale 

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x Mean change from Baseline in Worst Stiffness Numeric Rating Scale 
(NRS) score 
x Percentage of subjects who respond with a decrease of at least 30% in 
mean Brief Pain Inventory (BPI) score from Baseline 
x Mean change from Baseline in BPI score 
x Mean change from Baseline in Worst Pain NRS score 
x Mean change from Baseline in EQ-5D-5L health assessment 
Pharmacokinetics and Pharmacodynamics 
x Serum (and optional synovial) AMB-05X levels 
x Serum (and optional synovial) AMB-05X–binding anti-drug antibody 
(ADA) levels 
x Serum (and optional synovial) colony-stimulating factor 1 (CSF1) levels 
Study Design 
This is a Phase 2, open-label, multiple-dose, dose-escalation study with an 
adaptive design that will enroll up to approximately 48 subjects with TGCT 
for 12 weeks of open-label treatment with IV AMB-05X. There will be a 
screening period of up to 4 weeks, a treatment period of 12 weeks, and a post-
treatment follow-up period of 12 weeks. Each subject will receive a dose of 
AMB-05X every 2 or 4 weeks, for a total of 6 or 3 doses over the 12-week 
treatment period. All subjects, regardless of their dose regimen, will have a 
study visit every 2 weeks during the treatment period. 
A study schema is provided in Section 1.2, and the Schedule of Events is 
provided in Section 1.3. 
Study Visit Schedule 
Study visits will occur at the following times: 
x At Screening (Visit 1) 
x During the Treatment Period: 
o At Baseline/Day 1 (Visit 2), within 4 weeks after Screening (subjects 
receive their first dose of AMB-05X) 
o At Week 2 (Visit 3), Week 4 (Visit 4), Week 6 (Visit 5), Week 8 
(Visit 6), and Week 10 (Visit 7) 
o At Week 12 (Visit 8) (end of the Treatment Period and timepoint for 
assessment of primary and secondary endpoints; no AMB-05X is 
administered) 
x During the Follow-up Period: 
o At Week 14 (Visit 9) and Week 24 (Visit 10) 

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Adaptive Dose Cohorts and Data Monitoring Committee 
The study will enroll up to approximately 48 subjects total into up to 6 serial 
dose cohorts, designated Cohorts A through F. Each cohort will be composed 
of at least 3 and at most 12 subjects. 
Dosing will begin with Cohort A at the following starting dose level and 
regimen: 
x An initial priming dose of 4 mg/kg on Day 1 
x Followed by 5 maintenance doses of 2 mg/kg administered every 
2 weeks (at Weeks 2, 4, 6, 8, and 10) 
The dose levels and regimens for subsequent cohorts will be determined by 
the Sponsor based on an ongoing analysis of available data from the previous 
cohort(s). The following range of dose levels and regimens may be 
implemented in subsequent cohorts without a protocol amendment: 
Range of Dose Levels 
 
 
Initial Dose on Day 1 Maintenance Doses 
Minimum 2 mg/kg 
1 mg/kg 
Maximum 12 mg/kg 
8 mg/kg 
Although the minimum and maximum specified for the initial dose are both 
higher than those specified for maintenance doses, the initial dose does not 
have to be higher than subsequent maintenance doses. While remaining 
within the range specified, the initial dose may be the same as the subsequent 
maintenance doses, or the initial dose may be a higher, priming dose. 
Allowable Regimens 
 
 
 
Frequency 
# Doses Schedule 
Minimum Every 4 weeks 3 doses 
Initial dose on Day 1 
2 maintenance doses, at Weeks 4, 8 
Maximum Every 2 weeks 6 doses 
Initial dose on Day 1 
5 maintenance doses, at Weeks 2, 4, 
6, 8, 10 
Thus, the lowest dose that a cohort could receive would be an initial dose of 
2 mg/kg on Day 1, followed by 2 maintenance doses of 1 mg/kg every 
4 weeks (at Weeks 4 and 8). The highest dose that a cohort could receive 
would be an initial dose of 12 mg/kg on Day 1, followed by 5 maintenance 
doses of 8 mg/kg every 2 weeks (at Weeks 2, 4, 6, 8, and 10).  
A Sponsor data monitoring committee (DMC) composed of qualified 
medical/clinical representatives from the Sponsor will review the available 

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safety, tolerability, PK, pharmacodynamics (PD), and efficacy data on an 
ongoing basis and provide recommendations regarding appropriate next steps 
in study conduct. Study enrollment will begin with an initial 3 subjects in 
Cohort A. The DMC will begin to review study data after the first 3 subjects 
complete Week 6 and will continue to review data throughout the study (each 
time 3 additional subjects [from any cohort] complete Week 12). Whenever a 
new dose is instituted during the study, the DMC will again review the 
available data once 3 subjects have completed Week 6 at the new dose. 
The DMC will pay special attention to any clinically significant adverse 
events (AEs). Clinically significant AEs include dose-limiting toxicities 
(DLTs), AEs leading to discontinuation, and adverse events of special interest 
(AESIs), all considered at least possibly related to study drug. A DLT is 
defined as any Grade 3 or higher AE or serious adverse event (SAE) 
considered at least possibly related to study drug. AESIs are defined in 
Section 7.3.8.2. 
Based on the recommendations of the DMC, the Sponsor may implement any 
of the following decisions without a protocol amendment, in the manner of a 
3+3 dose-escalation study design: 
x If none of the first 3 subjects of a cohort experiences a clinically 
significant AE after 12 weeks on study drug, the Sponsor may elect to 
begin enrollment of the next cohort. 
x If exactly 1 subject among the first 3 subjects of a cohort experiences a 
clinically significant AE, an additional 3 subjects will be enrolled into 
that cohort. If only 1 of the 6 subjects experiences a clinically 
significant AE, the Sponsor may then elect to proceed with enrollment 
of the next cohort. 
x If exactly 2 subjects among the first 3 subjects of a cohort experience a 
clinically significant AE, the Sponsor will suspend enrollment in that 
cohort, and the DMC will make recommendations on next steps, such 
as suspending further enrollment in that cohort, enrolling another 
3 subjects into the cohort, or initiating another cohort at a lower dose. 
x If exactly 2 subjects in a 6-subject cohort experience a clinically 
significant AE, the Sponsor may elect to enroll an additional 3 subjects 
into that cohort at the same dose. If no additional clinically significant 
AEs occur, the Sponsor may then elect to proceed with enrollment of 
the next cohort. 
x ,I  VXEMHFWV LQ D 3- or 6-subject cohort experience a clinically 
significant AE, the Sponsor will suspend dosing and enrollment in that 
cohort and/or any further dose escalation in the study. Additional 
subjects may be enrolled at a lower dose. 

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x If data from the first 3 subjects in a cohort to complete treatment 
indicate suboptimal drug exposure or efficacy, and there are no 
significant safety issues such as clinically significant AEs, the Sponsor 
may elect to discontinue further enrollment in that cohort and proceed 
directly to the next cohort. 
x If safety permits according to the rules above (ie, if d1/3 of the previous 
subjects in the cohort experiences a clinically significant AE), the 
Sponsor may elect to enroll up to 12 subjects per cohort for more 
conclusive data. 
x Following the rules above, the Sponsor may elect to enroll the 
subsequent cohort in a staggered / overlapping manner (initiating 
enrollment in the next cohort while the current cohort is still completing 
the study or still enrolling) or sequentially (waiting until more complete 
data are available from the current cohort before initiating the next 
cohort). 
x The Sponsor may discontinue further enrollment and/or 
suspend/terminate the study (see Section 10.1.7). 
Subject Dose Reduction 
Enrolled subjects will begin treatment at the planned dose levels for their 
assigned cohorts. The Investigator may exercise his/her clinical judgment and 
consider a reduction in an individual subject’s maintenance dose (eg, from 
2 mg/kg to 1 mg/kg, 4 mg/kg to 2 mg/kg, or 8 mg/kg to 4 mg/kg) for subjects 
who experience a DLT. Before implementing a dose reduction for a subject, 
the Investigator should contact the Medical Monitor to discuss the case. 
Subjects who are unable to tolerate the lowest dose level specified above will 
have study drug discontinued. 
Dosage and 
Administration 
Dosing will begin with Cohort A with an initial priming dose of 4 mg/kg on 
Day 1 followed by 5 maintenance doses of 2 mg/kg administered every 
2 weeks (at Weeks 2, 4, 6, 8, and 10), for a total of 6 doses over the 12-week 
treatment period.  
The allowable range of dose levels and regimens for subsequent cohorts is 
provided under Study Design. Subjects in subsequent cohorts will receive 
study drug either every 2 weeks or every 4 weeks. The Sponsor will 
determine the dose levels and regimens for subsequent cohorts within the 
allowable range based on an ongoing analysis of available data from the 
previous cohort(s), as described under Study Design. 
Study drug will be administered via IV infusion at the study center by 
qualified study staff. Subjects will remain at the study center for at least 
60 minutes after dosing to allow monitoring for any adverse reactions, 
including any infusion-site reactions. 

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Assessments 
Safety and Tolerability 
Safety and tolerability will be assessed on an ongoing basis by monitoring 
AEs (including any SAEs, AEs leading to discontinuation, infusion-site 
reactions, any other DLTs, and AESIs), physical examinations / vital signs, 
changes in clinical laboratory values, and ECG results. 
A DMC composed of qualified medical/clinical representatives from the 
Sponsor will review available clinical data regularly and provide ongoing 
recommendations to the Sponsor concerning continuation, modification, or 
termination of the study. 
Efficacy 
1. Tumor response based on RECIST v1.1 (Eisenhauer, 2009) will be 
centrally assessed from magnetic resonance imaging (MRI) scans. An 
OR comprises both CR (defined as disappearance of all tumors) and PR 
(defined as a t30% decrease in the sum of diameters of target tumors 
from the baseline sum of diameters). 
2. Tumor response based on TVS will also be centrally assessed from MRI 
scans. TVS is a semi-quantitative scoring method developed specifically 
for assessing TGCT (Tap, 2015) that calculates tumor volume as a 
percentage of the estimated volume of the maximally distended synovial 
cavity or tendon sheath and provides a score in 10% increments. A score 
of 0 indicates no evidence of tumor; a score of 10 indicates a tumor that 
is equal in volume to that of a maximally distended synovial cavity or 
tendon sheath. The overall number of responses and the number of 
subjects with and without disease progression will be assessed (see 
Section 7.4.1.3). 
3. ROM of the affected joint will be assessed by qualified assessors at the 
study center and recorded in degrees. At Baseline, the plane of 
movement with the smallest (worst) relative ROM will be identified; 
only this plane will be used for evaluating change in ROM subsequently. 
4. The PROMIS Physical Function Scale is a 10-question patient-reported 
outcome (PRO) instrument that assess physical functioning. Questions 
address either the degree to which the subject’s health limits certain 
physical activities or the degree to which the subject is able to perform 
certain physical activities. Subjects select a response to each item that is 
scored on a 5-point scale. 
5. The Worst Stiffness NRS is a single-item PRO instrument designed to 
assess "worst" stiffness at the site of the tumor in the last 24 hours. The 
instrument uses an 11-point NRS that ranges from 0 (“no stiffness”) to 10 
(“stiffness as bad as you can imagine”). 
6. The BPI Short Form is a PRO instrument used to evaluate the severity of 
a subject's pain and the impact of this pain on the subject's daily 

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functioning. Subjects list current pain treatments and rate on a scale from 
0 to 10 their worst, least, average, and current pain intensity; how much 
relief current pain treatments provide; and the degree to which pain 
interferes with general activity, mood, walking ability, normal work, 
relations with other people, sleep, and enjoyment of life. 
The Worst Pain NRS is an item in the BPI that assesses a subject’s 
"worst" pain in the last 24 hours. The 11-point NRS for this item ranges 
from 0 (“no pain”) to 10 (“pain as bad as you can imagine”). 
7. The EQ-5D-5L is a widely used PRO quality-of-life instrument that asks 
subjects to select one of 5 levels of severity in each of 5 dimensions 
(mobility, self-care, usual activities, pain/discomfort, and 
anxiety/depression) and to provide an overall assessment of general 
health using a visual analogue scale (VAS). 
Pharmacokinetics and Pharmacodynamics 
Serum AMB-05X and CSF1 concentrations will be measured at the following 
visits: 
x Day 1, Week 4, and Week 8: before dosing and within 15 minutes after 
the end of infusion 
x Weeks 2 and 6: 
o If the subject will receive study drug at the visit, collect the serum 
sample before dosing. 
o If the subject will not receive study drug at the visit, collect the 
serum sample at any time during the visit. 
x Week 10: 
o If the subject will receive study drug at this visit, collect serum 
samples before dosing and within 15 minutes after the end of 
infusion. 
o If the subject will not receive study drug at this visit, collect a serum 
sample at any time during the visit. 
x Weeks 12, 14, and 24: at any time during the visit 
Synovial AMB-05X and CSF1 concentrations may be measured pre-dose at 
Day 1 and pre-dose at the visit associated with the last dose of study drug for 
each subject (Week 8 or Week 10) as an optional assessment. 
ADA levels against AMB-05X will be measured from pre-dose serum 
samples and any synovial samples collected at Day 1, at Week 4, at the visit 
associated with the last dose of study drug for each subject (Week 8 or 
Week 10), and at Week 14. 
Actual dosing and sampling times will be accurately recorded on the 
electronic case report form (eCRF). 

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Study 
Population 
This study will enroll up to approximately 48 adult subjects with local or 
diffuse TGCT in the United States and Europe. 
Inclusion 
Criteria 
A subject may be included in this study if ALL of the following criteria 
are met: 
1. Male or female t18 years of age. 
2. Able to communicate well with study staff and understand and comply 
with the requirements of the study. Reads and voluntarily signs the 
informed consent form (ICF) and the Health Insurance Portability and 
Accountability Act (HIPAA) authorization (if applicable) before the 
conduct of any study-specific procedures. 
3. TGCT that has been histologically confirmed by a pathologist. If the 
diagnosis has not been previously histologically confirmed, biopsy with 
histological confirmation is required before enrollment. 
4. Measurable disease as defined by RECIST v1.1 (except with a minimum 
size of 2 cm), assessed from MRI scans by a central radiologist. 
5. If subject uses prescription analgesic, subject must be on a stable 
prescription analgesic regimen during the 2 weeks before Baseline. 
6. Agrees to follow contraception guidelines (see Section 5.3). 
7. Adequate hematologic, hepatic, and renal function at Screening, defined 
by: 
x $EVROXWH QHXWURSKLO FRXQW   î 9/L 
x Aspartate aminotransferase (AST) and alanine aminotransferase 
$/7   î XSSHU OLPLW RI QRUPDO 8/1 
x Hemoglobin > 10 g/dL 
x 7RWDO ELOLUXELQ   î 8/1 (elevated bilirubin secondary to a 
known, relatively benign condition [eg, Gilbert’s syndrome] is not 
exclusionary) 
x 3ODWHOHW FRXQW   î 9/L 
x 6HUXP FUHDWLQLQH   î 8/1 
8. Willing and able to complete the PROMIS Physical Function Scale, 
Worst Stiffness NRS, BPI, and EQ-5D-5L throughout the study. 
Exclusion 
Criteria 
A subject will be excluded if ANY of the following criteria is met: 
1. Use of any investigational drug within 4 weeks or 5 half-lives (whichever 
is longer) before Baseline. 
2. Use of pexidartinib, any other oral tyrosine kinase inhibitor (eg, imatinib 
or nilotinib), or any biologic treatment targeting CSF1 or CSF1R within 
3 months before Baseline. 

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3. Current or prior radiotherapy within 3 months before Baseline. 
4. Current or prior active cancer within 3 years before Baseline that 
requires/required therapy (eg, surgery, chemotherapy, or radiation 
therapy), except adequately treated basal or squamous cell carcinoma of 
the skin, melanoma in situ, carcinoma in situ of the cervix or breast, or 
prostate carcinoma not requiring treatment apart from active surveillance. 
5. Known metastatic TGCT or malignant transformation of diffuse-type 
TGCT. 
6. Any history of complex or reconstructive surgery on the affected joint 
(eg, involving plates, screws, or metal implants). 
7. Hepatitis C virus (HCV) or hepatitis B virus (HBV) or known active or 
chronic infection with human immunodeficiency virus (HIV). 
8. Known active tuberculosis (TB). 
9. Significant concomitant arthropathy in the affected joint, serious illness, 
uncontrolled infection, or a medical or psychiatric history that, in the 
Investigator's opinion, would likely interfere with the subject’s study 
participation or the interpretation of the subject’s results. 
10. A woman who is pregnant or breastfeeding. For women of childbearing 
potential, a positive pregnancy test at either Screening or Baseline will be 
exclusionary. 
11. A screening Fridericia-corrected QT interval (QTcF)  ms (men) or 
 ms (women) 
12. MRI contraindications (eg, pacemaker, loose metallic implants) 
13. History of hypersensitivity to any ingredient in the study drug. 
14. History of drug or alcohol abuse within 3 months before Baseline. 
15. Has any other severe acute or chronic medical or psychiatric condition or 
clinically significant laboratory abnormality that may increase the risk 
associated with study participation/treatment, interfere with interpretation 
of study results, or, in the Investigator’s opinion, make the subject 
inappropriate for this study. 
16. A person who is held in detention as the result of a judicial or official 
decision or who is in a subordinate relationship to the Sponsor or 
Investigator. 
17. A subject who, in the opinion of the Investigator, should not participate 
in this study for any reason, including instances where the subject’s 
stability or ability to comply with study requirements is in question. 
Statistical 
Methods 
Sample Size Determination 
Based on prior Phase 1 experience and an anticipated treatment effect with 
AMB-05X in this population, the sample size of 3 to 12 subjects per cohort is 

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anticipated to provide sufficient data for PK/PD analysis and an estimate of 
safety, tolerability, and efficacy.  
Analysis Methods 
All study data will be summarized by dose cohort and overall using 
descriptive statistics.  
Safety Analyses 
Safety analyses will include all subjects who receive at least 1 dose of study 
drug. 
All AEs reported will be listed, documenting severity, start and stop date and 
time, possible relationship to study drug, action taken, and outcome. TEAEs 
are defined as AEs that occur after the first dose of study drug. Verbatim 
terms will be mapped to Preferred Terms (PTs) and related System Organ 
Classes (SOCs) using the Medical Dictionary for Regulatory Activities 
(MedDRA). PTs and SOCs will be tabulated by dose cohort and overall. All 
reported AEs will be summarized by the number of subjects reporting each 
AE, SOC, PT, severity, and relationship to study drug. Multiple occurrences 
of an AE will be counted only once per subject per SOC and PT in summary 
tables. 
Safety labs (including hematology, chemistry, and urinalysis), vital signs, 
tolerability data, and ECGs will be tabulated using descriptive statistics. 
Abnormal/out-of-range findings and changes from pre-dose to post-dose will 
be listed by subject. Shift tables will be provided for all laboratory variables. 
Efficacy Analyses 
Efficacy endpoints will be summarized using descriptive statistics and 95% 
confidence intervals. Exploratory hypotheses testing may be conducted using 
a significance level of 0.05 without adjustment for multiplicity. 
Pharmacokinetic Analyses  
AMB-05X concentrations will be summarized by dose, regimen, and nominal 
collection time. If warranted, a population PK analysis may be conducted 
using data from the current study and relevant data from other clinical studies. 
In addition, an exposure-response analysis may be attempted using the 
population approach. 

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1.2 Schema

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2 INTRODUCTION 
2.1 Tenosynovial Giant Cell Tumor 
TGCT, also known as giant cell tumor of the tendon sheath (GCT-TS) or pigmented villonodular 
synovitis (PVNS), is a rare, locally aggressive and destructive mesenchymal neoplasm that arises 
in the synovium of joints, bursae, or tendon sheaths (de Saint Aubain Somerhausen, 2013; 
Staals, 2016).  
TGCTs are caused by the excessive production of CSF1 resulting from genomic mutations 
(balanced translocations) at the CSF1 gene locus of chromosome 1p13 (West, 2006; 
Cupp, 2007). CSF1 acts at the CSF1R, leading to the proliferation of synovial-like mononuclear 
cells and recruitment of multinucleate giant cells, foam cells, siderophages, and inflammatory 
cells, which compose the bulk of the neoplasm (West, 2006; Cupp, 2007; de Saint Aubain 
Somerhausen, 2013). Although TGCTs are nonmetastatic in nature, they can develop into locally 
destructive lesions that cause significant local tissue injury, loss of joint function, and impaired 
quality of life (West, 2006). 
The annual incidence of TGCT is estimated to be approximately 43 cases per 1 million 
individuals (Ehrenstein, 2017; Mastboom, 2017), with approximately 40,000 new cases per year 
in the US and Europe combined. TGCT most commonly affects individuals between 20 to 50 
years of age (Ostuni, 2015). Two TGCT subtypes have generally been recognized: localized (l-
TGCT) and diffuse (d-TGCT). Approximately 10% of TGCT are classified as diffuse 
(Mastboom, 2017). Regardless of subtype, TGCT nearly always involves a single joint, with the 
knee being the most commonly affected (up to 66% to 80%), followed by the ankle, elbow, 
shoulder, wrist/hand, and hip (Murphey, 2008). 
TGCT presents clinically as a joint swelling or a firm, slowly enlarging mass (Ostuni, 2015). As 
the disease advances, patients experience attacks of pain, swelling, loss of range of motion, 
hemorrhagic joint effusions, cartilage destruction, and bone erosion, leading to eventual loss of 
joint function, impaired quality of life, and severe morbidity (Giustini, 2018; Tap, 2019). Joint 
replacement or even amputation might be necessary in cases of persistent disease (Staals, 2016). 
While TGCT is not lethal, it is a serious, chronic, debilitating illness with long-term 
consequences for joint function and quality of life (Mastboom, 2017). 
The standard of care in TGCT is surgical resection via synovectomy (Granowitz, 1976). 
However, recurrence after surgery is common and occurs in up to 55% of patients with the 
diffuse subtype (Palmerini, 2015; Brahmi, 2016; Staals, 2016; Mastboom, 2017). Repeated 
surgeries may be necessary but often lead to further morbidity, complications, and reduced 
function of affected joints (Staals, 2016). Radiotherapy is occasionally used, typically for larger 
joints with diffuse lesions, but its use is limited because of late sequelae (Benner, 2020).  
In late 2019, pexidartinib, an oral small-molecule tyrosine kinase inhibitor with activity against 
CSF1R, was approved by the US Food and Drug Administration (FDA) for the treatment of 
adults with symptomatic TGCT with severe morbidity/functional limitations, not amenable to 
surgery (Turalio package insert, 2020). Results from the Phase 3 ENLIVEN study showed that 
pexidartinib was superior to placebo in achieving overall responses per RECIST criteria (39% vs 

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0%; p<0.0001). However, systemic side effects including serious / life-threatening cases of 
mixed or cholestatic hepatotoxicity were observed and remain a concern among patients treated 
with pexidartinib (Tap, 2019; Gelderblom, 2020).  
The viability of CSF1R inhibition as a treatment modality for TGCT was further established in 
an early-stage clinical trial of emactuzumab, a monoclonal antibody that targets CSF1R 
(Cassier, 2015). Following systemic (IV) administration, 86% of subjects achieved an objective 
response associated with early onset of symptomatic and functional improvement.  
In summary, TGCT is a rare but serious, debilitating chronic illness with limited treatment 
options. Given the limitations of current treatment options and prior clinical validation of CSF1R 
as an effective treatment target, AmMax Bio, Inc. is developing AMB-05X, a human monoclonal 
antibody that inhibits CSF1R, as an IV therapeutic for the treatment of TGCT. 
2.2 AMB-05X 
AMB-05X is an antagonistic, fully human antibody (immunoglobulin G, type 2 [IgG2]) specific 
to the extracellular domain of human CSF1R (also known as c-FMS). AMB-05X potently blocks 
both CSF1- and interleukin-34 (IL-34)–mediated proliferation of growth factor–dependent 
human myelomonocytic cells in vitro. It effectively interacts with CSF1R in monkeys but not in 
other species such as rodents. 
2.3 Summary of Nonclinical Data 
Refer to the Investigator’s Brochure (IB) for additional information on nonclinical studies of 
AMB-05X. 
2.3.1 Pharmacology 
AMB-05X binds with high affinity to CSF1R expressed on the surface of human 
myelomonocytic cells (AML-5 cells) and to cynomolgus monkey CSF1R expressed on the 
surface of human embryonic kidney cells transformed by adenovirus (2936E cells). 
AMB-05X inhibits CSF1-induced phosphorylation of human CSF1R. In addition, this antibody 
immunoprecipitated human CSF1R and its known single-nucleotide polymorphism variants. 
AMB-05X potently inhibits CSF1-driven proliferation of both human and cynomolgus monkey 
primary bone marrow–derived monocyte/macrophage cells in vitro as well as CSF1- and IL-34–
driven proliferation of human myelomonocytic AML-5 cells. 
AMB-05X does not cross-react with mouse CSF1R. Therefore, a surrogate anti-mouse CSF1R 
antibody (M279) was developed for use in mouse tumor model studies. Like AMB-05X, M279 
potently and specifically inhibited CSF1R-mediated activity in vitro. In vivo, M279 significantly 
inhibited the growth of a variety of xenograft and syngeneic tumor models, including MDA-MB-
231 (human breast adenocarcinoma), Renca (mouse renal cell carcinoma, syngeneic), and 
NCI-H1650 and NCI-H1975 (human non-small-cell lung carcinomas) tumor models, by 50% to 
70% based on tumor volume. In addition, tumor-associated macrophage content in all tumors 
treated with M279 was significantly lower than in control-treated tumors, as shown by a variety 
of methods, including immunohistochemistry, flow cytometry, and immunofluorescence. 

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2.3.2 Pharmacokinetics 
Single IV doses of AMB-05X administered to cynomolgus monkeys produced a nonlinear 
increase in exposure at doses of 0.1 to 5 mg/kg but an approximately dose-proportional increase 
at doses of 5 to 100 mg/kg. When receptor-mediated clearance had been saturated at higher 
serum concentrations of AMB-; 
ȝJP/ WKH NLQHWLFV RI AMB-05X became linear. The 
volume of distribution at steady state for AMB-05X in monkeys was approximately equal to 
plasma volume, indicating limited extravascular distribution. 
The toxicokinetics of repeated IV doses of AMB-05X was assessed in both 4-week and 14-week 
repeat-dose toxicity studies and did not differ markedly between male and female monkeys. In 
general, exposure to IV AMB-05X increased approximately dose proportionally in monkeys over 
the dose range of 10 to 300 mg/kg. No marked (>2-fold) accumulation of AMB-05X was 
observed after 4 or 13 once-weekly doses in monkeys. During the dosing phase of these studies, 
AMB-05X–binding ADAs were detected in 1 of 30 animals in the 4-week study and 13 of 35 
animals in the 14-week study; during the recovery phase of the 14-week study, ADAs were 
detected in 8 of 10 animals. In general, ADAs decreased exposure to AMB-05X in these animals. 
For both studies, high concentrations of AMB-05X in the serum samples may have interfered 
with detection of ADAs in animals that tested ADA-negative. 
2.3.3 Toxicology 
In toxicology studies in the cynomolgus monkey, animals received IV AMB-05X at up to 
300 mg/kg once-weekly for 4 or 14 weeks. All directly AMB-05X–related findings were 
attributed to its expected pharmacology of inhibition of macrophages. Additionally, changes 
related to the acute post-dosing formation of ADA/drug complex (also called circulating immune 
complexes [CICs]) occurred in some animals in the 14-week study. 
Clinical observations attributed to AMB-05X pharmacology consisted of reversible periorbital 
swelling due to increased extracellular matrix, as observed by light microscopy. Clinical 
pathology changes included reversible increases in serum ALT, AST, and glutamate 
dehydrogenase (GLDH) without a light microscopic correlate in the liver and without elevations 
in sorbitol dehydrogenase (SDH), a liver-specific marker of injury. The increased extracellular 
matrix and elevated activities of serum enzymes were thought to result from decreased clearance 
due to inhibition of macrophages (Radi, 2011). Additional AMB-05X–related changes included 
decreased bone turnover, characterized by elongation of bone growth plates, decreased numbers 
of osteoclasts, and decreases in serum markers of bone turnover, all of which were reversible. 
The presence of yeast organisms in the lung and protozoal organisms in the gastrointestinal tract 
in a few animals (contributing to death in 1 animal) may be incidental or a pharmacologic effect 
of AMB-05X. Increased neutrophil counts occurred in association with myeloid hyperplasia. 
During the last 2 months of the dosing phase in the 14-week study, acute post-dosing sequelae 
(platelet effects and clinical signs including death) were observed in ADA-positive animals at 10 
and 50 mg/kg. The role of ADA/drug complexes in the acute post-dosing findings was confirmed 
by demonstration of ADA/drug complexes serologically and immunohistochemically. No post-
dosing CICs or related effects occurred at 300 mg/kg. Retrospective analyses correlating 
immunogenicity rates in animals and humans demonstrate low predictive value of nonclinical 

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immunogenicity rates for human clinical responses (Ponce, 2009). Moreover, for nonclinical 
species dosed with human or humanized proteins, immunogenicity in animals is generally 
greater than in humans. For these reasons, the observed adverse effects in ADA-positive 
monkeys at 10 and 50 mg/kg attributed to the formation of ADA/drug complexes are not 
considered to be predictive of human clinical risk. 
Synovial concentrations of AMB-05X can be extrapolated from the 14-week cynomolgus 
monkey studies. In these studies, peak serum concentrations over the dosing period were 
 mg/mL, which translates to synovial concentrations of 
 Pg/mL at steady-state 
(Stepensky, 2012; AmMax modeling; AMB051-20-NHP1 study results). 
2.4 Summary of Clinical Data 
Refer to the IB for additional information on clinical studies of AMB-05X. 
Two clinical studies of IV AMB-05X have been conducted in subjects with advanced solid 
tumors: a first-in-human monotherapy study and a combination study with pembrolizumab. 
2.4.1 Monotherapy Study 
The first-in-human study of IV AMB-05X evaluated safety, tolerability, PK, and PD in subjects 
with advanced solid tumors (Papadopoulos, 2017). The study initially dosed subjects once 
weekly at 0.5 mg/kg. In subsequent cohorts, the dosing regimen was revised to IV infusion over 
a 60-minute period every 2 weeks. Escalation of AMB-05X dose was advanced through 1.5, 3, 6, 
10, and 20 mg/kg levels.  
All 25 subjects (100%) had measurable disease at baseline by local assessment, which supported 
their enrollment into the study. By central assessment, 21 subjects (84%) had measurable disease 
at baseline. Per central assessment, 8 subjects (32%) had a best response of stable disease; per 
local assessment, 1 subject (4.0%) had partial response and 6 subjects (24%) had stable disease 
(central and local assessments of subject response did not fully overlap). Per central assessment, 
1 subject (with stable disease) had a >20% reduction in tumor burden based on RECIST; per 
local assessment, 1 subject (with partial response) had a 40% reduction in tumor burden. The 
median for maximum percentage change from baseline in tumor volume was 19.3% 
(range: -24.0% to 104.8%). 
All 25 subjects (100%) had at least 1 TEAE; the most common were nausea and vomiting 
(12 subjects [48%] each); fatigue and periorbital edema (11 subjects [44%] each); constipation 
(9 subjects [36%]); and anemia, AST increased, and decreased appetite (8 subjects [32%] each). 
A total of 18 subjects (72%) had AEs that were at least Grade 3 in severity and 5 (20%) had AEs 
that were at least Grade 4. 
One subject in the 20-mg/kg cohort experienced a nonreversible DLT of Grade 3 bilateral 
deafness; lack of a baseline audiology exam and the recent receipt of multiple cycles of cisplatin 
therapy (1 month before first dose of AMB-05X) precluded any meaningful assessment of the 
progressive aspect of hearing loss. 
SAEs were reported for 11 subjects (44%), AEs leading to withdrawal from the study were 
reported for 4 subjects (16%), and AEs leading to discontinuation of investigational product were 

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reported for 5 subjects (20%). Fatal AEs were reported for 3 subjects (12%); the events occurred 
in the setting of progressive disease and were considered not related to treatment with AMB-05X 
by the investigators. 
AEs considered treatment-related by the investigator were reported by 19 subjects (76%). 
Periorbital edema (without clinical sequelae) was the most common treatment-related AE 
(11 subjects [44%]); the majority of events resolved and were managed without intervention. 
AST increased was also a common treatment-related AE (7 subjects [28%]). Seven subjects 
(28%) had treatment-related AEs that were Grade 3 or higher in severity, and 1 subject (4%) 
discontinued AMB-05X due to a treatment-related AE (the previously mentioned bilateral 
deafness DLT). There were no treatment-related serious or fatal AEs. 
Macrophages were quantified in skin biopsies as an indicator of pharmacologic effect. In all 
subjects in the 10-mg/kg and 20-mg/kg dose groups who had available skin biopsy data, 
macrophage levels were reduced from baseline at Week 5, as indicated by positive staining for 
CD68 and/or CD163. 
2.4.2 Combination Study with Pembrolizumab 
The combination study of IV AMB-05X administered with pembrolizumab (Study 20150195) 
evaluated safety, tolerability, and objective response rate (ORR) in subjects with select advanced 
solid tumors. 
The study was conducted in 2 parts: 
x Part 1 (Phase 1b) evaluated the safety of AMB-05X in combination with pembrolizumab 
using a 6+3 design. The starting dose was AMB-05X 1,400 mg  pembrolizumab 200 mg 
every 3 weeks. Fifteen subjects were enrolled and received at least 1 dose of AMB-05X  
pembrolizumab. The mean (standard deviation [SD]) treatment duration was 0.8 (0.7) 
months. The ORR was 0%. 
x Part 2 (Phase 2) further evaluated safety and tested whether AMB-05X could enhance the 
antitumor activity observed historically with pembrolizumab alone and/or overcome lack 
of response to pembrolizumab monotherapy in subjects with select solid tumors. One 
hundred and one subjects were enrolled and received at least 1 dose of AMB-05X  
pembrolizumab. Of these, 90 subjects received AMB-05X 1,100 mg  pembrolizumab 
200 mg every 3 weeks, and 11 subjects received AMB-05X 1,400 mg  pembrolizumab 
200 mg every 3 weeks. The mean (SD) treatment duration was 1.6 (2.5) months. The ORR 
was 3.0%. 
PK results from a total of 116 subjects were available from the study. Following administration 
in cycles 1 and 2, AMB-05X exposures increased in an approximately dose-proportional manner 
over the dose range of 1,100 to 1,400 mg. Over this 1.3-fold increase in dose, mean Cmax 
increased 1.4-fold in both cycle 1 and cycle 2, and mean AUC over the dosing interval W (AUCW) 
increased 1.5-fold in both cycle 1 and cycle 2. Median tmax values ranged from 2.0 to 3.0 hours 
post-dose in cycles 1 and 2. No significant serum accumulation of AMB-05X was observed 
between cycles 1 and 2; mean accumulation ratio for AUCW ranged from 1.25 to 1.27. 

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Safety in Part 1 is summarized as follows: 
x All subjects had at least 1 TEAE. The most common AEs were fatigue (66.7%), AST 
increased (60.0%), periorbital edema (53.3%), decreased appetite and diarrhea (each in 
33.3% of subjects), and dyspnea, hypophosphatemia, nausea, and pyrexia (each in 26.7% 
of subjects).  
x A total of 14 subjects (93.3%) had events that were Grade 3 or higher, including 6 subjects 
(40.0%) who had Grade 4 events and 5 subjects (33.3%) who had fatal (Grade 5) AEs. All 
of the fatal AEs were considered not related to study treatment.  
x Seven subjects (46.7%) had at least 1 SAE, none of which occurred in more than 1 subject. 
x TEAEs considered related to AMB-05X were reported in 12 subjects (80.0%). The most 
common AMB-05X–related AEs were periorbital edema and AST increased (each in 
46.7% of subjects) and fatigue (26.7%). 
x One subject (14.3%) who received AMB-05X 1,400 mg  pembrolizumab 200 mg had 
DLTs of autoimmune pancreatitis, autoimmune hepatitis, cholecystitis, and electrolyte 
imbalance, after which the AMB-05X dose was decreased to 1,100 mg. No subject who 
received AMB-05X 1,100 mg  pembrolizumab 200 mg had a DLT. No subject had a 
TEAE leading to discontinuation of investigational product. 
x No clinically relevant trends in hematology, serum chemistry, or urinalysis laboratory 
values were reported. 
Safety in Part 2 is summarized as follows: 
x All subjects had at least 1 TEAE. The most common AEs were fatigue (53.5%), periorbital 
edema (39.6%), anemia (37.6%), nausea (29.7%), constipation (28.7%), pyrexia (26.7%), 
and decreased appetite and rash (each in 25.7% of subjects).  
x A total of 99 subjects (98.0%) had events that were Grade 3 or higher, including 
68 subjects (67.3%) who had Grade 4 events and 57 subjects (56.4%) who had fatal 
(Grade 5) events. Of the fatal AEs, only tumor flare and pneumonitis (1 subject each) were 
considered related to study treatment.  
x Seventy-three subjects (72.3%) had at least 1 SAE. The most common SAEs were pyrexia 
(6.9%) and pneumonia and urinary tract infection (each in 5.0% of subjects).  
x TEAEs considered related to AMB-05X were reported in 90 subjects (89.1%). The most 
common AMB-05X–related AEs were AST increased (53.5%), periorbital edema (38.6%), 
and fatigue (30.7%). 
x Seventeen subjects (16.8%) had a TEAE leading to discontinuation of investigational 
product. TEAEs leading to discontinuation in >1 subject were periorbital edema and 
pneumonitis (2 subjects each).  
x Six subjects (5.9%) who received AMB-05X 1,100 mg  pembrolizumab 200 mg had 
DLTs of AST increased (2 subjects) and fatigue, lipase increased, epilepsy, rash 
generalized, and rash maculo-papular (1 subject each). 
x During the study, 4 subjects (4.0%) treated with AMB-05X  pembrolizumab had liver 
function test results that potentially met the criteria for Hy’s Law (ALT or AST > 3 î ULN 

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and total bilirubin > 2 î ULN and alkaline phosphatase < 2 î ULN). After further 
evaluation, none of the subjects met the definitive criteria for Hy’s Law.  
x No clinically relevant trends in hematology, serum chemistry, or urinalysis laboratory 
values were reported.  

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3 OBJECTIVES AND ENDPOINTS 
The objectives of this study are to evaluate the safety, efficacy, and PK of IV AMB-05X in the 
treatment of TGCT. 
3.1 Primary Endpoint 
The primary endpoint is the frequency and severity of reported TEAEs. 
3.2 Secondary Endpoints 
3.2.1 Efficacy Secondary Endpoints 
The following efficacy endpoints will be assessed at Week 12: 
x Proportion of subjects who achieve an overall tumor response (OR, which includes both 
CR and PR) per RECIST v1.1 (Eisenhauer, 2009) 
x Proportion of subjects with overall response based on TVS, a TGCT-specific method that 
calculates tumor volume as a percentage of the estimated maximally distended synovial 
cavity 
x Mean change from Baseline in ROM score 
x Mean change from Baseline in the PROMIS Physical Function score  
x Mean change from Baseline in Worst Stiffness NRS score 
x Percentage of subjects who respond with a decrease of at least 30% in mean BPI score 
from Baseline 
x Mean change from Baseline in BPI score 
x Mean change from Baseline in Worst Pain NRS score 
x Mean change from Baseline in EQ-5D-5L health assessment 
3.2.2 Pharmacokinetic and Pharmacodynamic Secondary Endpoints 
x Serum (and optional synovial) AMB-05X levels 
x Serum (and optional synovial) AMB-05X–binding ADA levels 
x Serum (and optional synovial) CSF1 levels 

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4 STUDY DESIGN 
4.1 Overall Design 
This is a Phase 2, open-label, multiple-dose, dose-escalation study with an adaptive design that 
will enroll up to approximately 48 subjects with TGCT for 12 weeks of open-label treatment 
with IV AMB-05X. There will be a screening period of up to 4 weeks, a treatment period of 
12 weeks, and a post-treatment follow-up period of 12 weeks. Each subject will receive a dose of 
AMB-05X every 2 or 4 weeks, for a total of 6 or 3 doses over the 12-week treatment period.  
A study schema is provided in Section 1.2, and the Schedule of Events is provided in 
Section 1.3.  
4.1.1 Study Visit Schedule 
Study visits will occur at the following times: 
x At Screening (Visit 1) 
x During the Treatment Period: 
o At Baseline/Day 1 (Visit 2), within 4 weeks after Screening (subjects receive their first 
dose of AMB-05X) 
o At Week 2 (Visit 3), Week 4 (Visit 4), Week 6 (Visit 5), Week 8 (Visit 6), and Week 10 
(Visit 7) 
o At Week 12 (Visit 8) (the end of the Treatment Period and timepoint for assessment of 
primary and secondary endpoints; no AMB-05X is administered) 
x During the Follow-up Period: 
o At Week 14 (Visit 9) and Week 24 (Visit 10) 
Refer to Appendix 5 for potential changes to study conduct in the context of COVID-19 
(coronavirus disease 2019). 
4.1.2 Adaptive Dose Cohorts and Data Monitoring Committee 
The study will enroll up to approximately 48 subjects total into up to 6 serial dose cohorts, 
designated Cohorts A through F. Each cohort will be composed of at least 3 and at most 
12 subjects. All subjects, regardless of their dose regimen, will have a study visit every 2 weeks 
during the treatment period. 
Dosing will begin with Cohort A at the following starting dose level and regimen: 
x An initial priming dose of 4 mg/kg on Day 1 
x Followed by 5 maintenance doses of 2 mg/kg administered every 2 weeks (at Weeks 2, 4, 
6, 8, and 10) 
The dose levels and regimens for subsequent cohorts will be determined by the Sponsor based on 
an ongoing analysis of available data from the previous cohort(s). The following range of dose 
levels and regimens may be implemented in subsequent cohorts without a protocol amendment: 

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Range of Dose Levels 
 
 
Initial Dose on Day 1 Maintenance Doses 
Minimum 2 mg/kg 
1 mg/kg 
Maximum 12 mg/kg 
8 mg/kg 
Although the minimum and maximum specified for the initial dose are both higher than those 
specified for maintenance doses, the initial dose does not have to be higher than subsequent 
maintenance doses. While remaining within the range specified, the initial dose may be the same 
as the subsequent maintenance doses, or the initial dose may be a higher, priming dose. 
Allowable Regimens 
 
 
 
Frequency 
# Doses Schedule 
Minimum Every 4 weeks 3 doses 
Initial dose on Day 1 
2 maintenance doses, at Weeks 4, 8 
Maximum Every 2 weeks 6 doses 
Initial dose on Day 1 
5 maintenance doses, at Weeks 2, 4, 
6, 8, 10 
Thus, the lowest dose that a cohort could receive would be an initial dose of 2 mg/kg on Day 1, 
followed by 2 maintenance doses of 1 mg/kg every 4 weeks (at Weeks 4 and 8). The highest 
dose that a cohort could receive would be an initial dose of 12 mg/kg on Day 1, followed by 
5 maintenance doses of 8 mg/kg every 2 weeks (at Weeks 2, 4, 6, 8, and 10).  
A Sponsor DMC composed of qualified medical/clinical representatives from the Sponsor will 
review the available safety, tolerability, PK, PD, and efficacy data on an ongoing basis and 
provide recommendations regarding appropriate next steps in study conduct. Study enrollment 
will begin with an initial 3 subjects in Cohort A. The DMC will begin to review study data after 
the first 3 subjects complete Week 6 and will continue to review data throughout the study (each 
time 3 additional subjects [from any cohort] complete Week 12). Whenever a new dose is 
instituted during the study, the DMC will again review the available data once 3 subjects have 
completed Week 6 at the new dose. 
The DMC will pay special attention to any clinically significant AEs. Clinically significant AEs 
include DLTs, AEs leading to discontinuation, and AESIs, all considered at least possibly related 
to study drug. A DLT is defined as any Grade 3 or higher AE or SAE considered at least possibly 
related to study drug. AESIs are defined in Section 7.3.8.2.  
Based on the recommendations of the DMC, the Sponsor may implement any of the following 
decisions without a protocol amendment, in the manner of a 3+3 dose escalation study design: 
x If none of the first 3 subjects of a cohort experiences a clinically significant AE after 
12 weeks on study drug, the Sponsor may elect to begin enrollment of the next cohort. 

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x If exactly 1 subject among the first 3 subjects of a cohort experiences a clinically 
significant AE, an additional 3 subjects will be enrolled into that cohort. If only 1 of the 
6 subjects experiences a clinically significant AE, the Sponsor may then elect to proceed 
with enrollment of the next cohort. 
x If exactly 2 subjects among the first 3 subjects of a cohort experience a clinically 
significant AE, the Sponsor will suspend enrollment in that cohort, and the DMC will 
make recommendations on next steps, such as suspending further enrollment in that cohort, 
enrolling another 3 subjects into the cohort, or initiating another cohort at a lower dose. 
x If exactly 2 subjects in a 6-subject cohort experience a clinically significant AE, the 
Sponsor may elect to enroll an additional 3 subjects into that cohort at the same dose. If no 
additional clinically significant AEs occur, the Sponsor may then elect to proceed with 
enrollment of the next cohort. 
x ,I  VXEMHFWV LQ D - or 6-subject cohort experience a clinically significant AE, the Sponsor 
will suspend dosing and enrollment in that cohort and/or any further dose escalation in the 
study. Additional subjects may be enrolled at a lower dose. 
x If data from the first 3 subjects in a cohort to complete treatment indicate suboptimal drug 
exposure and efficacy, and there are no significant safety issues such as clinically 
significant AEs, the Sponsor may elect to discontinue further enrollment in that cohort and 
proceed directly to the next cohort. 
x If safety permits according to the rules above (ie, if d1/3 of the previous subjects in the 
cohort experience a clinically significant AE), the Sponsor may elect to enroll up to 
12 subjects per cohort for more conclusive data. 
x Following the rules above, the Sponsor may elect to enroll the subsequent cohort in a 
staggered / overlapping manner (initiating enrollment in the next cohort while the current 
cohort is still completing the study or still enrolling) or sequentially (waiting until more 
complete data are available from the current cohort before initiating the next cohort). 
x The Sponsor may discontinue further enrollment and/or suspend/terminate the study (see 
Section 10.1.7). 
4.1.3 Subject Dose Reduction 
Enrolled subjects will begin treatment at the planned dose levels for their assigned cohorts. The 
Investigator may exercise his/her clinical judgment and consider a reduction in an individual 
subject’s maintenance dose (eg, from 2 mg/kg to 1 mg/kg, 4 mg/kg to 2 mg/kg, or 8 mg/kg to 
4 mg/kg) for subjects who experience a DLT. Before implementing a dose reduction for a 
subject, the Investigator should contact the Medical Monitor to discuss the case. Subjects who 
are unable to tolerate the lowest dose level specified in Section 4.1.2 will have study drug 
discontinued. 
4.2 Justification for Dose 
The proposed starting dose level for Cohort A is an initial priming dose of 4 mg/kg IV, followed 
by 5 maintenance doses of 2 mg/kg IV every 2 weeks thereafter, for a total of 6 doses over 
12 weeks. This dose level is well supported by a 14-week Good Laboratory Practice (GLP) 

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Investigator will discontinue a subject’s study drug if the Investigator concludes that 
continuation would be detrimental to the subject’s safety or well-being. 
Reasons for premature discontinuation of study drug / withdrawal from the study may include: 
x Pregnancy 
x Lack of efficacy 
x Adverse event 
x Protocol violation  
x Death 
x Study termination by the Sponsor  
x Physician decision  
x Lost to follow-up 
x Subject decision 
x Other, to be specified 
If ET occurs for any reason, the Investigator must make every effort to determine the primary 
reason for the ET and record this information on the eCRF. The Investigator will also schedule 
ET procedures for a subject who terminates early but does not withdraw consent for study 
participation (see Section 8.11). ET procedures consist of Visit 8 (Week 12), Visit 9 (Week 14), 
and Visit 10 (Week 24) (whichever visits the subject has yet to complete at the time of ET). 
Subjects who discontinue study drug as the result of an AE will also be followed according to 
Section 7.3.4. Subjects who withdraw consent will be considered withdrawn from further study 
participation.  
If a subject fails to appear for study visits without stating an intention to withdraw, the site must 
make every effort to regain contact with the subject, including making 3 telephone calls to the 
subject and, if necessary, sending a registered letter to the subject’s last known mailing address. 
Attempts to contact the subject will be documented in the subject’s site file. If the subject 
continues to be unreachable, the subject will be considered lost to follow-up and thus withdrawn 
from the study. 

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5 STUDY POPULATION 
This study will enroll up to approximately 48 adult subjects with local or diffuse TGCT in the 
United States and Europe. 
5.1 Inclusion Criteria 
A subject may be included in this study if ALL of the following criteria are met. 
1. Male or female t18 years of age. 
2. Able to communicate well with study staff and understand and comply with the 
requirements of the study. Reads and voluntarily signs the ICF and the HIPAA authorization 
(if applicable) before the conduct of any study-specific procedures. 
3. TGCT that has been histologically confirmed by a pathologist. If the diagnosis has not been 
previously histologically confirmed, biopsy with histological confirmation is required before 
enrollment. 
4. Measurable disease as defined by RECIST v1.1 (except with a minimum size of 2 cm), 
assessed from MRI scans by a central radiologist. 
5. If subject uses prescription analgesic, subject must be on a stable prescription analgesic 
regimen during the 2 weeks before Baseline. 
6. Agrees to follow contraception guidelines (see Section 5.3). 
7. Adequate hematologic, hepatic, and renal function at Screening, defined by: 
x $EVROXWH QHXWURSKLO FRXQW   î 9/L 
x $67 DQG $/7   î 8/1 
x Hemoglobin > 10 g/dL 
x 7RWDO ELOLUXELQ   î 8/1 (elevated bilirubin secondary to a known, relatively benign 
condition [eg, Gilbert’s syndrome] is not exclusionary) 
x 3ODWHOHW FRXQW   î 9/L 
x 6HUXP FUHDWLQLQH   î 8/1 
8. Willing and able to complete the PROMIS Physical Function Scale, Worst Stiffness NRS, 
BPI, and EQ-5D-5L throughout the study. 
5.2 Exclusion Criteria 
A subject will be excluded if ANY of the following criteria is met. 
1. Use of any investigational drug within 4 weeks or 5 half-lives (whichever is longer) before 
Baseline. 
2. Use of pexidartinib, any other oral tyrosine kinase inhibitor (eg, imatinib or nilotinib), or any 
biologic treatment targeting CSF1 or CSF1R within 3 months before Baseline. 

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3. Current or prior radiotherapy within 3 months before Baseline 
4. Current or prior active cancer within 3 years before Baseline that requires/required therapy 
(eg, surgery, chemotherapy, or radiation therapy), except adequately treated basal or 
squamous cell carcinoma of the skin, melanoma in situ, carcinoma in situ of the cervix or 
breast, or prostate carcinoma not requiring treatment apart from active surveillance. 
5. Known metastatic TGCT or malignant transformation of diffuse-type TGCT. 
6. Any history of complex or reconstructive surgery on the affected joint (eg, involving plates, 
screws, or metal implants). 
7. HCV or HBV or known active or chronic infection with HIV. 
8. Known active TB. 
9. Significant concomitant arthropathy in the affected joint, serious illness, uncontrolled 
infection, or a medical or psychiatric history that, in the Investigator's opinion, would likely 
interfere with the subject’s study participation or the interpretation of the subject’s results. 
10. A woman who is pregnant or breastfeeding. For women of childbearing potential, a positive 
pregnancy test at either Screening or Baseline will be exclusionary. 
11. $ VFUHHQLQJ 47F)  PV PHQ RU  PV ZRPHQ 
12. MRI contraindications (eg, pacemaker, loose metallic implants) 
13. History of hypersensitivity to any ingredient in the study drug. 
14. History of drug or alcohol abuse within 3 months before Baseline. 
15. Has any other severe acute or chronic medical or psychiatric condition or clinically 
significant laboratory abnormality that may increase the risk associated with study 
participation/treatment, interfere with interpretation of study results, or, in the Investigator’s 
opinion, make the subject inappropriate for this study. 
16. A person who is held in detention as the result of a judicial or official decision or who is in a 
subordinate relationship to the Sponsor or Investigator. 
17. A subject who, in the opinion of the Investigator, should not participate in this study for any 
reason, including instances where the subject’s stability or ability to comply with study 
requirements is in question. 
5.3 Contraception Guidelines 
Subjects must agree to adhere to the following contraception guidelines (Heads of Medicines 
Agencies, 2014) throughout the study and for 90 days after the last dose of study drug. 
5.3.1 Contraception Guidelines for Female Subjects 
A female enrolling in this study must meet ONE of the following contraceptive criteria: 
1. She is not a female of childbearing potential because of one of the following: 
a. She is postmenopausal. 

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A postmenopausal state is defined as having no menses for at least 1 year 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. However, a single 
FSH measurement is insufficient to establish a postmenopausal state without at least 
1 year of amenorrhea. 
b. She is permanently sterile by hysterectomy, bilateral salpingectomy, or bilateral 
oophorectomy. 
2. She is totally abstinent from heterosexual intercourse as her preferred and usual lifestyle 
(abstinent on a long-term and persistent basis). Periodic abstinence (eg, calendar, 
symptothermal, or post-ovulation methods) and withdrawal are not acceptable. Subjects who 
practice total abstinence must use another method of contraception if they become sexually 
active. 
3. Any male sexual partner is vasectomized and has received medical confirmation of the 
surgical success. 
4. She agrees to use one of the following highly effective contraceptive methods: 
a. Combined hormonal contraception (containing estrogen and progestogen) associated 
with inhibition of ovulation: oral, intravaginal, or transdermal 
b. Progestogen-only hormonal contraception associated with inhibition of ovulation: 
oral, injectable, or implantable  
c. Intrauterine device (IUD) 
d. Intrauterine hormone-releasing system (IUS) 
e. Bilateral tubal occlusion 
5. Where allowed by local laws and regulations, a double-barrier contraceptive method—
specifically, female subject use of cap, diaphragm, or sponge with spermicide AND male 
partner use of condom—is acceptable. 
5.3.2 Contraception Guidelines for Male Subjects 
A male enrolling in this study must meet ONE of the following contraceptive criteria: 
1. He is not a fertile male because he is permanently sterile by bilateral orchiectomy. 
2. He is totally abstinent from heterosexual intercourse as his preferred and usual lifestyle 
(abstinent on a long-term and persistent basis). Periodic abstinence (eg, calendar, 
symptothermal, or post-ovulation methods) and withdrawal are not acceptable. Subjects who 
practice total abstinence must use another method of contraception if they become sexually 
active. 
3. He is vasectomized and has received medical confirmation of the surgical success. 
4. He agrees to use a male condom AND his female partner, if she is a female of childbearing 
potential, uses one of the following highly effective contraceptive methods: 

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a. Combined hormonal contraception (containing estrogen and progestogen) associated 
with inhibition of ovulation: oral, intravaginal, or transdermal 
b. Progestogen-only hormonal contraception associated with inhibition of ovulation: 
oral, injectable, or implantable 
c. IUD 
d. IUS 
e. Bilateral tubal occlusion 
5. Where allowed by local laws and regulations, a double-barrier contraceptive method—
specifically, male subject use of condom AND female partner of childbearing potential use 
of cap, diaphragm, or sponge with spermicide—is acceptable. 

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Storage conditions must be adequately monitored, and appropriate temperature logs maintained 
as source data. Any excursion in storage temperature should be recorded and reported to the 
Sponsor to ensure study drug is suitable for administration. Refer to the pharmacy manual for 
detailed information regarding storage and temperature constraints. 
6.2.4 Disposal 
Any leftover study drug in opened vials will be disposed of onsite according to the study center’s 
standard operating procedures; glass vials will be retained for accountability. 
After receiving written authorization from the Sponsor or its designee, the site will either send 
unused and empty vials of study drug to the address provided at the time of authorization for 
destruction or, with specific approval from the Sponsor, destroy the unused and empty vials of 
study drug onsite according to the study center’s standard operating procedures. The study staff 
must provide a drug destruction certificate to the Sponsor or its designee. 
6.3 Measures to Minimize Bias: Randomization and Blinding 
If there is concurrent enrollment of multiple cohorts, subjects will be randomized to a cohort via 
the interactive web response system (IWRS). There is no blinding except for the blinding of the 
central radiologist to a subject’s dose. 
6.4 Study Intervention Compliance 
Study drug will be administered by qualified study staff at the study center. 
6.5 Concomitant Therapy 
A subject’s concomitant medications will be reviewed during the screening period. Subjects 
should be instructed to notify the study center about any new medications they start taking or any 
medications they stop taking. All medications administered from the time the ICF is signed 
through a subject’s last study visit must be recorded on the Concomitant Medications eCRF. Any 
significant non-drug therapies (including physical therapy and blood transfusions) will be 
recorded on the Concomitant Procedures eCRF. 
Subjects who use a prescription analgesic must be on a stable regimen of prescription analgesic 
during the 2 weeks before Baseline and should make every effort to maintain a stable regimen of 
prescription analgesic during the study, so as not to confound the measurement of pain in this 
study. 
Use of any other investigational drug is prohibited within 4 weeks or 5 half-lives (whichever is 
longer) before Baseline and during the study. 
Use of pexidartinib, any other oral tyrosine kinase inhibitor (eg, imatinib or nilotinib), or any 
biologic treatment targeting CSF1 or CSF1R is prohibited within 3 months before Baseline and 
during the study. 
MRI contraindications (eg, pacemaker, loose metallic implants) are prohibited during the study. 

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7 STUDY ASSESSMENTS AND PROCEDURES 
7.1 Screening Procedures 
7.1.1 Subject ID 
Each subject screened will be assigned a unique 6-digit Subject ID via the interactive web 
response system (IWRS). The Subject ID will consist of a 3-digit center number (101, 201, etc) 
and a 3-digit subject number that starts with 001 for each site. Thus, if the center number is 101, 
the Subject IDs assigned to subjects at that center will be 101-001, 101-002, 101-003, etc. 
7.1.2 Demographics and Medical History 
Demographic data and a complete medical history with review of body systems will be 
documented for all subjects during the screening period. Any change in the subject’s condition or 
health status between consent and the first dose of study drug will be captured as medical 
history. Any AE that occurs between consent and the first dose of study drug will be recorded 
but will not be considered treatment emergent. 
7.1.3 Height 
Height will be measured at Screening only. 
7.1.4 Tumor Biopsy 
For subjects whose TGCT diagnosis has not been previously histologically confirmed, a tumor 
biopsy will be performed during the screening period after a central radiologist has reviewed the 
subject’s screening MRI scan. 
7.2 Safety Assessments 
Safety will be evaluated using the following assessments: 
x Reported AEs (see Section 7.3) and concomitant medications (see Section 6.5) 
x Body weight 
x Vital signs 
x Physical examination 
x ECG 
x Pregnancy tests 
x Clinical laboratory tests 
x Tolerability assessment 
7.2.1 Vital Signs 
Vital signs, including blood pressure (systolic and diastolic, in mmHg), body temperature (in 
°C), heart rate (in beats per minute), and respiratory rate (in breaths per minute) will be recorded 
with the subject in a sitting position after having rested for 5 minutes. 

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7.2.2 Physical Examination 
A full physical exam will include, but not be limited to, an examination of general appearance, 
skin, HEENT (head, eyes, ears, nose, throat), lungs, heart, abdomen, back, lymph nodes, 
extremities, and basic nervous system evaluation. 
Information about the physical examination must be present in the source documentation at the 
study center. Significant findings that are present before the first dose of study drug must be 
included on the medical history / current medical conditions page of the eCRF. Significant 
findings made after the first dose of study drug that meet the definition of an AE must be 
recorded on the AE page of the eCRF. 
7.2.3 Electrocardiogram 
Standard 12-lead ECGs will be performed, and the following ECG parameters will be measured: 
heart rate, RR, PR, QRS, and QTcF. The Subject ID, the subject’s age, the date and actual time 
of the tracing, and the study code must appear on each page of the tracing. Tracings will be 
dated, signed, and interpreted by a qualified physician. The overall interpretation will be 
collected with a Yes / No statement about whether any clinically significant abnormalities are 
present that need to be specified further in the source document and eCRF. Original ECG 
tracings, appropriately signed, will be archived at study centers. 
7.2.4 Pregnancy Tests 
For women of childbearing potential, a serum pregnancy test will be performed at Screening and 
a urine pregnancy test will be performed at all other visits specified in the Schedule of Events 
and at the discretion of the Investigator (eg, for a subject with irregular menses). The results of 
the serum pregnancy test at Screening and the urine pregnancy test at Visit 2 (Baseline) must be 
received before a subject may be enrolled. 
7.2.5 Clinical Laboratory Tests 
Table 1 shows the clinical laboratory parameters to be evaluated during the study. Blood samples 
will be drawn for chemistry and hematology. Urine samples will be collected for urinalysis. 
Details on sample collection and processing will be described in the laboratory manual. 
Table 1. Clinical Laboratory Parameters 
Hematology 
Platelet count 
Mean platelet volume (MPV) 
Red blood cell (RBC) count 
Red cell distribution width (RDW) 
Hematocrit 
Hemoglobin  
Mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin 
concentration (MCHC), mean corpuscular volume (MCV) 

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Reticulocytes 
White blood cell (WBC) count (total and differential) 
Chemistry 
(including 
lipids) 
Alanine transaminase (ALT) 
Albumin 
Alkaline phosphatase (ALP) 
Aspartate transaminase (AST) 
Bilirubin (total, direct, indirect) 
Blood urea nitrogen (BUN) 
Carbon dioxide (CO2) 
Calcium 
Chloride 
Cholesterol 
Creatinine 
Gamma-glutamyl transferase (GGT) 
Globulin 
Glucose (non-fasting) 
High-density lipoprotein (HDL) 
Lactate dehydrogenase (LDH) 
Low-density lipoprotein (LDL) 
Magnesium 
Phosphorus 
Potassium 
Sodium 
Total protein 
Triglycerides 
Uric acid 
Routine 
Urinalysis 
Color, visual color, turbidity, glucose, bilirubin, ketones, specific gravity, 
blood, pH, protein, acidified protein, urobilinogen, nitrite, leukocyte esterase 
Microscopic examination if indicated:  urine WBC, urine RBC, bacteria, oval 
fat bodies, squamous epithelial cells, renal tubular epithelial cells, 
transitional epithelial cells, yeast, mucus, sperm, dysmorphic RBC 
 
7.3 Adverse Events and Serious Adverse Events 
7.3.1 Definition of Adverse Event 
An AE is any untoward medical occurrence associated with the use of a drug in humans, whether 
or not considered drug related. An AE (also referred to as an adverse experience) can be any 
unfavorable and unintended sign (eg, an abnormal laboratory finding), symptom, or disease 
temporally associated with the use of a drug and does not imply any judgment about causality.  
An AE can arise with any use of the drug (eg, off-label use, use in combination with another 
drug) and with any route of administration, formulation, or dose, including an overdose. An 
overdose with symptoms should be recorded as an AE. 
A worsening of previous illness or condition from baseline while participating in the study is 
also considered an AE. 

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7.3.2 Definition of Serious Adverse Event 
An SAE is any event that meets any of the following criteria: 
x Results in death 
x Is life-threatening 
x Requires inpatient hospitalization or prolongation of existing hospitalization 
x Results in persistent or significant disability/incapacity 
x Is a congenital anomaly/birth defect 
x Is an important medical event. An important medical event that may not result in death, be 
life-threatening, or require hospitalization may be considered serious when, based upon 
appropriate medical judgment, the event may jeopardize the subject and may require 
medical or surgical intervention to prevent one of the other outcomes listed in the 
definition above. Examples of such medical events include allergic bronchospasm 
requiring intensive treatment in an emergency room or at home, blood dyscrasias or 
convulsions that do not result in inpatient hospitalization, or the development of drug 
dependency or drug abuse. 
If, during follow-up, any non-serious AE worsens and eventually meets the criteria for an SAE, 
that AE should be recorded as a new SAE. 
7.3.3 Classification of an Adverse Event 
7.3.3.1 Severity 
The Investigator will provide an assessment of the severity of each AE by recording a severity 
rating on the AE page of the subject’s eCRF. Severity, which is a description of the intensity of 
manifestation of the AE, is distinct from seriousness. Severity will be graded according to the 
National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) version 
5.0 (CTCAE 2017), summarized here: 
x Grade 1: Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; 
intervention not indicated. 
x Grade 2: Moderate; minimal, local, or noninvasive intervention indicated; limiting 
age-appropriate instrumental activities of daily living (preparing meals, shopping for 
groceries or clothes, using the telephone, managing money, etc).  
x Grade 3: Severe or medically significant but not immediately life-threatening; 
hospitalization or prolongation of hospitalization indicated; disabling; limiting self-care 
activities of daily living (bathing, dressing and undressing, feeding self, using the toilet, 
taking medications, and not bedridden). 
x Grade 4: Life-threatening consequences; urgent intervention indicated. 
x Grade 5: Death related to AE. 
7.3.3.2 Relationship to Study Drug 
The Investigator must assess the relationship of each AE to the study drug according to the 
categories defined below and record it on the AE page of the subject’s eCRF. 

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x Definitely related: There is clear evidence to suggest a causal relationship, and other 
possible contributing factors can be ruled out. The clinical event, including an abnormal 
laboratory test result, occurs in a plausible time relationship to study drug administration 
and cannot be explained by concurrent disease or other drugs or chemicals. The response 
to withdrawal of the study drug (dechallenge) should be clinically plausible. The event 
must be pharmacologically or phenomenologically definitive, with use of a satisfactory 
rechallenge procedure if necessary. 
x Probably related: There is evidence to suggest a causal relationship, and the influence of 
other factors is unlikely. The clinical event, including an abnormal laboratory test result, 
occurs within a reasonable time after administration of the study drug, is unlikely to be 
attributed to concurrent disease or other drugs or chemicals, and follows a clinically 
reasonable response on withdrawal (dechallenge). Rechallenge information is not required 
to fulfill this definition. 
x Possibly related: There is some evidence to suggest a causal relationship (eg, the event 
occurred within a reasonable time after administration of the study drug). However, other 
factors may have contributed to the event (eg, the participant’s clinical condition, other 
concomitant events). Although an AE may rate only as “possibly related” soon after 
discovery, it can be flagged as requiring more information and later be upgraded to 
“probably related” or “definitely related”, as appropriate. 
x Unlikely to be related: A clinical event, including an abnormal laboratory test result, 
whose temporal relationship to study drug administration makes a causal relationship 
improbable (eg, the event did not occur within a reasonable time after administration of the 
study drug) and in which other drugs or chemicals or underlying disease provides plausible 
explanations (eg, the participant’s clinical condition, other concomitant treatments). 
x Not related: The AE is completely independent of study drug administration, and/or 
evidence exists that the event is definitely related to another etiology. There must be an 
alternative, definitive etiology documented by the clinician.  
This assessment will help the Sponsor to determine whether an AE might be a suspected adverse 
reaction. A suspected adverse reaction is any AE for which there is a reasonable possibility that 
the drug caused the AE. ‘Reasonable possibility’ means there is evidence to suggest a causal 
relationship between the drug and the AE. A suspected adverse reaction implies a lesser degree 
of certainty about causality than an adverse reaction. 
The Investigator may change the causality assessment at any time based on new accumulated 
information. An AE with causal relationship not initially determined will require follow-up to 
assign causality. 
7.3.3.3 Expectedness 
An unexpected AE or unexpected, suspected adverse reaction refers to an event or reaction that 
is not listed in the Reference Safety Information section of the most recent version of the IB at 
the time of the event or is not listed at the specificity or severity that has been observed. The 
Sponsor will be responsible for determining whether an AE is expected or unexpected. 

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7.3.4 Time Period and Frequency for Event Assessment and Follow-up 
AEs will be recorded from the time the ICF is signed until the subject completes the last study 
visit or withdraws from the study. 
AEs will be assessed at each study visit, and subjects should be encouraged to contact the study 
center to report any AEs at their onset. Study staff will elicit information about AEs using 
nonspecific questions such as “Have you experienced any change in your health status since your 
last visit?” Subjects will also be monitored closely for the development of an AE. 
Any AE or clinically significant abnormality of ECG, physical examination finding, or clinical 
laboratory measurement that occurs during the study should be followed until no further medical 
intervention is warranted (eg, it resolves, becomes medically stable, or is assessed as chronic) or 
until the subject is lost to follow-up. AE follow-up must comply with International Council for 
Harmonisation (ICH) Good Clinical Practice (GCP) guidelines. 
7.3.5 Adverse Event Reporting 
Information about AEs will be recorded on the AE page of the subject’s eCRF. When known, the 
diagnosis (rather than individual symptoms) should be entered as the event term in the eCRF. For 
example, an upper respiratory infection with symptoms of cough, rhinitis, and sneezing should 
be recorded as upper respiratory infection. When the diagnosis is unclear, key symptoms may be 
entered separately, and the Investigator should obtain appropriate tests to establish a diagnosis, if 
possible. After a diagnosis is determined, the eCRF event term should be updated. 
For each AE, the onset date, seriousness, severity (Section 7.3.3.1), relationship to study drug 
(causality) (Section 7.3.3.2), action taken, outcome, and date of resolution (or continuing) will be 
recorded. The Investigator must make a causality assessment for each AE. 
7.3.6 Serious Adverse Event Reporting and Follow-up 
The Sponsor is required to inform worldwide regulatory authorities of SAEs that meet specific 
criteria and to do so in an expedited manner. Specifically, suspected, unexpected serious adverse 
reactions (SUSARs) are subject to expedited safety reporting requirements. The Sponsor will 
report SUSARs to the appropriate authorities within the timelines and format required by local 
regulations. The Sponsor will also inform all participating investigators of SUSARs and any new 
safety risks.  
Therefore, study centers must report all SAEs, including death, due to any cause, that occur from 
the time the ICF is signed until the subject completes the last study visit or withdraws from the 
study, to the Sponsor or its designee within 24 hours of the study center staff learning of its 
occurrence. When reporting an SAE, all relevant seriousness criteria should be recorded, and 
relationship to study drug should be assigned at the time of initial report, as this is required to 
determine regulatory reporting. 
The Investigator must also report applicable SAEs to the Institutional Review Board (IRB) / 
Independent Ethics Committees (IEC) according to the requirements of the IRB/IEC. The 
Sponsor will provide the Investigator with information on SUSARs from other study centers or 
other studies conducted with the study drug to provide to IRBs/IECs. 

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The Investigator is expected to institute appropriate diagnostic and therapeutic measures 
necessary to treat and promote resolution of the SAE. Any medications or procedures used to 
treat the SAE must be recorded on the appropriate pages of the subject’s eCRF. The Investigator 
must determine whether the seriousness of the event warrants discontinuation of study drug. 
The Investigator is expected to proactively follow up on the SAE with the subject at subsequent 
visits/contacts and to report follow-up information on the SAE to the Sponsor or its designee. All 
SAEs will be followed until no further medical intervention is warranted (eg, the event resolves, 
becomes medically stable, or is assessed as chronic) or until the subject is lost to follow-up. 
The Sponsor or designee may contact the study center to solicit additional information or to 
follow up on the event. If requested, medical records (such as laboratory results, radiology 
reports, progress notes, hospital admission and emergency room notes, holding and observation 
notes, discharge summaries, autopsy reports, and death certificates) should be sent to the Sponsor 
or its designee after redacting all information that personally identifies the subject or hospital 
staff (per the European General Data Protection Regulation). 
After a subject’s last study visit, the Investigator is not obligated to actively seek AEs or SAEs. 
However, if the Investigator learns of any SAE, including a death, at any time after a subject has 
been discharged from the study, and he/she considers the event reasonably related to the study 
drug or to study participation, the Investigator must notify the Sponsor or designee within 
24 hours of learning of the event. 
7.3.7 Reporting of Pregnancy 
Any pregnancy in a female subject or in the female partner of a male subject that occurs from the 
time the subject signs an ICF until a subject’s last study visit must be reported to the Sponsor or 
its designee within 24 hours of study center staff learning of its occurrence. A pregnant female 
subject will be immediately discontinued from study drug. 
The subject or pregnant partner should provide consent and then will be followed throughout the 
course of the pregnancy. Pregnancy follow-up information, including the status and health of the 
mother and the child and the outcome of the pregnancy, will be reported to the Sponsor or its 
designee. Any premature termination of the pregnancy will be reported. Any complication of the 
pregnancy affecting either the mother or the fetus that meets seriousness criteria will be reported 
as an SAE. A planned elective termination of the pregnancy will not be considered an SAE. 
7.3.8 Clinically Significant Adverse Events 
Clinically significant AEs include DLTs, AEs leading to discontinuation, and AESIs, all 
considered at least possibly related to study drug. The DMC will pay special attention to the 
occurrence of clinically significant AEs in their recommendations regarding continuation or 
suspension of dosing or enrollment, cohort expansion, initiation of a new dose cohort, and dose 
selection. 
7.3.8.1 Dose-Limiting Toxicity 
A DLT is defined as any Grade 3 or higher AE or SAE considered at least possibly related to 
study drug. For subjects who experience a DLT, the Investigator may exercise his/her clinical 
judgment and consider a reduction in an individual subject’s maintenance dose (eg, from 

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2 mg/kg to 1 mg/kg, 4 mg/kg to 2 mg/kg, or 8 mg/kg to 4 mg/kg). Before implementing a dose 
reduction for a subject, the Investigator should contact the Medical Monitor to discuss the case. 
Subjects who are unable to tolerate the lowest dose level specified in Section 4.1.2 will have 
study drug discontinued. 
7.3.8.2 Adverse Events of Special Interest 
AESIs for this study will include the following: 
x Any events of liver toxicity, including elevations in liver enzymes (ALP, ALT, AST, 
bilirubin) 
x Any periorbital edema or facial edema 
x Grade 2 or higher: infections, nausea, vomiting, diarrhea 
x Any infusion reactions 
x Any neutropenia, anemia, or thrombocytopenia 
All AESIs will be captured on an AESI report form. The DMC will pay special attention to 
AESIs considered at least possibly related to study drug. 
7.4 Efficacy Assessments 
Efficacy will be evaluated using the following assessments: 
x MRI and central radiologist assessment of tumors based on RECIST v1.1 and TVS 
x Clinician evaluation of ROM in the affected joint 
x PRO instruments of PROMIS Physical Function Scale, Worst Stiffness NRS, BPI Short 
Form (including the Worst Pain NRS item), and EQ-5D-5L 
7.4.1 Tumor Assessments 
7.4.1.1 MRI 
MRI procedures will be detailed in a separate MRI manual. MRI scans will be evaluated 
centrally by an independent radiologist blinded to a subject’s dose. MRI scans will be assessed 
for tumor response based on RECIST v1.1 (Section 7.4.1.2) and based on TVS (Section 7.4.1.3). 
7.4.1.2 Response Based on RECIST v1.1 
OR will be centrally assessed from MRI scans using RECIST v1.1 and will include CR and PR 
(Eisenhauer, 2009). A CR is defined as disappearance of all tumors. A PR is defined as at least a 
30% decrease in the sum of diameters of target tumors from the baseline sum of diameters. 
7.4.1.3 Response Based on Tumor Volume Score 
Quantification of tumor volume in TGCT is complicated by the irregular shape of the tumor and 
heterogeneous contrast between the tumor and its surrounding structures, which make it 
challenging to delineate tumor boundaries. TVS is a semi-quantitative scoring method for MRIs 
developed specifically for assessing TGCT (Tap, 2015). TVS draws from existing MRI scoring 
methods commonly used in arthritis (the Rheumatoid Arthritis MRI Score and the Whole Organ 
MRI Score) and from existing radiological experience in assessing changes in tumor volume and 

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patterns of distension of synovial cavities. TVS calculates tumor volume as a percentage of the 
estimated volume of the maximally distended synovial cavity or tendon sheath and provides a 
score in 10% increments. A score of 0 indicates no evidence of tumor; a score of 10 indicates a 
tumor that is equal in volume to that of a maximally distended synovial cavity or tendon sheath.  
Tumor outcomes based on TVS will be classified according to the following: 
x Complete response (CR):  lesion is completely gone 
x Partial response (PR):  t50% decrease in TVS relative to Baseline 
x Progressive disease (PD):  t30% increase in TVS relative to the lowest score during the 
study 
x Stable disease (SD):  does not meet any of the other classifications 
Tumor response based on TVS is defined as CR or PR. The overall number of responses and the 
number of subjects with and without disease progression will be assessed. 
7.4.2 Joint Range of Motion 
ROM of the affected joint will be assessed by qualified assessors at the study center and recorded 
in degrees. At Baseline, the plane of movement with the smallest (worst) relative ROM will be 
identified; only this plane will be used for evaluating change in ROM subsequently. 
7.4.3 PROMIS Physical Function Scale 
The PROMIS Physical Function Scale provided in Appendix 1 is a 10-question PRO instrument 
that will be used to assess physical functioning based on use of the upper extremities (dexterity), 
lower extremities (walking or mobility), and central regions (neck, back) and on instrumental 
activities of daily living. Five questions address the degree to which the subject’s health limits 
certain physical activities, and subjects select a response to each question that ranges from 1 
(“cannot do”) to 5 (“not at all”). Five questions address the degree to which the subject is able to 
perform certain physical activities, and subjects select a response to each question that ranges 
from 1 (“cannot do”) to 5 (“without any difficulty”). 
7.4.4 Worst Stiffness Numeric Rating Scale 
The Worst Stiffness NRS provided in Appendix 2 is a single-item PRO instrument designed to 
assess “worst” stiffness at the site of the tumor. The instrument uses an 11-point NRS that ranges 
from 0 (“no stiffness”) to 10 (“stiffness as bad as you can imagine”). Subjects are asked to recall 
their “worst” stiffness at the site of the tumor in the last 24 hours. 
7.4.5 Brief Pain Inventory Short Form and Worst Pain Numeric Rating Scale 
The BPI Short Form provided in Appendix 3 is a PRO instrument used to evaluate the severity of 
a subject's pain and the impact of this pain on the subject's daily functioning (Cleeland, 1994). 
Subjects list current pain treatments and rate on a scale from 0 to 10 their worst, least, average, 
and current pain intensity; how much relief current pain treatments provide; and the degree to 
which pain interferes with general activity, mood, walking ability, normal work, relations with 
other people, sleep, and enjoyment of life.  

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The Worst Pain NRS is an item in the BPI that assesses a subject’s "worst" pain in the last 
24 hours. The 11-point NRS for this item ranges from 0 (“no pain”) to 10 (“pain as bad as you 
can imagine”). 
7.4.6 EQ-5D-5L 
The EQ-5D-5L assessment provided in Appendix 4 is a widely used PRO quality-of-life 
instrument developed by the EuroQol Group that consists of 2 pages: the EQ-5D descriptive 
system and the EQ VAS. The descriptive system comprises 5 dimensions (mobility, self-care, 
usual activities, pain/discomfort, and anxiety/depression), and subjects select one of 5 levels 
(statements describing severity) that most accurately describes their health state for each 
dimension. The VAS records the subject’s self-rated general health on a vertical VAS. 
7.5 Pharmacokinetic and Pharmacodynamic Assessments 
Serum will be collected and optional synovial fluid may be collected to assess AMB-05X, CSF1, 
and anti–AMB-05X antibody at the visits indicated in the Schedule of Events. 
Serum AMB-05X and CSF1 concentrations will be measured at the following visits: 
x Day 1, Week 4, and Week 8: before dosing and within 15 minutes after the end of infusion 
x Weeks 2 and 6: 
o If the subject will receive study drug at the visit, collect the serum sample before 
dosing. 
o If the subject will not receive study drug at the visit, collect the serum sample at any 
time during the visit. 
x Week 10: 
o If the subject will receive study drug at this visit, collect serum samples before dosing 
and within 15 minutes after the end of infusion. 
o If the subject will not receive study drug at this visit, collect a serum sample at any time 
during the visit. 
x Weeks 12, 14, and 24: at any time during the visit 
Synovial AMB-05X and CSF1 concentrations may be measured pre-dose at Day 1 and pre-dose 
at the visit associated with the last dose of study drug for each subject (Week 8 or Week 10) as 
an optional assessment. 
ADA levels against AMB-05X will be measured from pre-dose serum samples and any synovial 
samples collected at Day 1, at Week 4, at the visit associated with the last dose of study drug for 
each subject (Week 8 or Week 10), and at Week 14. 
Actual dosing and sampling times will be accurately recorded on the eCRF. 

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7.6 Blood Sampling 
Blood samples will be taken by direct venipuncture. Blood sampling volumes will be limited by 
the most stringent regulations applicable to a particular site or region. Details on sample 
collection and processing will be described in a separate laboratory manual. 

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8 ASSESSMENTS BY STUDY VISIT 
The Schedule of Events for this study is provided in Section 1.3. 
Refer to Appendix 5 for potential changes to study conduct in the context of COVID-19, 
including the possibility of remote visits. 
8.1 Visit 1 / Screening 
After the subject provides signed consent and HIPAA authorization (if applicable), complete the 
following procedures. If necessary, screening assessments may be performed at more than 1 visit 
during the 4-week screening period. 
x Obtain a 6-digit Subject ID from IWRS. 
x Collect demographic information and take medical history. 
x Record all concomitant medications, including dose amount and dosing frequency, taken 
within 4 weeks before Screening. 
x Obtain height and weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Conduct a full physical examination. 
x Perform a 12-lead ECG. 
x Evaluate ROM of the affected joint. 
x Administer the following PRO instruments: 
o PROMIS Physical Function Scale 
o Worst Stiffness NRS 
o BPI Short Form 
o EQ-5D-5L 
x Collect a urine sample for urinalysis. 
x Collect blood samples for HBV, HCV, HIV, TB (QuantiFERON), serum pregnancy test 
for females of childbearing potential, and clinical laboratory tests (chemistry and 
hematology). 
x Perform MRI. A central radiologist will evaluate MRI scans to assess tumors. 
x For subjects whose TGCT diagnosis has not been previously histologically confirmed, a 
tumor biopsy will be performed during the screening period after the central radiologist has 
reviewed the subject’s screening MRI scan. 
x Once test results are obtained, check inclusion/exclusion criteria. 
Individuals who successfully complete screening procedures and meet all eligibility criteria will 
be notified and scheduled for Visit 2 (Baseline). The interval between Visit 1 (Screening) and 
Visit 2 (Baseline) should not exceed 4 weeks.  

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For any individual who does not meet eligibility criteria, capture screen failure information, 
contact IWRS to report screen failure status, and record any changes in concomitant medications 
and AEs since Screening. 
8.2 Visit 2 / Baseline (Day 1) 
Approximately 16 to 24 hours before scheduled study drug administration, set up the appropriate 
number of study drug vials to thaw in the refrigerator according to Section 6.1.2. 
8.2.1 Pre-dose Procedures 
x Collect a urine sample for a urine pregnancy test for females of childbearing potential and 
for urinalysis. 
x Update any changes in concomitant medications since Visit 1 (Screening). 
x Record any AEs that may have occurred since the ICF was signed. AEs that occur before 
the first dose of study drug will be recorded as such to distinguish them from TEAEs. 
x Once test results are obtained, check inclusion/exclusion criteria. 
o Individuals who do not meet eligibility criteria (eg, females of childbearing potential 
with a positive pregnancy test) will be recorded as screen failures. 
If the subject met all inclusion and no exclusion criteria, complete the following procedures: 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with the 
subject in a sitting position after having rested for 5 minutes. 
x Conduct a full physical examination and document any changes since the previous visit. 
x Perform a 12-lead ECG. 
x Evaluate ROM of the affected joint. 
x Administer the following PRO instruments: 
o PROMIS Physical Function Scale 
o Worst Stiffness NRS 
o BPI Short Form 
o EQ-5D-5L 
x Collect blood samples for clinical laboratory tests (chemistry and hematology) and serum 
PK, CSF1, and anti–AMB-05X antibody (pre-dose sample). 
x Optional assessment: collect synovial fluid for PK, CSF1, and anti–AMB-05X antibody. 
8.2.2 First Dose and Post-dose Procedures 
x Administer study drug via IV infusion. 
x Collect blood samples for serum PK and CSF1 within 15 minutes after the end of infusion. 
x Monitor the subject for at least 60 minutes post-dose for any adverse reactions, including 
any infusion-site reactions. 

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x Schedule the subject for Visit 3 (Week 2). 
x Contact IWRS to record the visit. 
8.3 Visit 3 (Week 2 r 2 Days) 
If the subject is on an every-2-weeks study drug regimen, set up the appropriate number of study 
drug vials to thaw in the refrigerator approximately 16 to 24 hours before scheduled study drug 
administration and according to Section 6.1.2. 
For all subjects, complete the following procedures during the visit: 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Collect a urine sample for urinalysis. 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect blood samples for serum PK and CSF1 (before study drug administration, if 
applicable for the subject). 
x Schedule the next visit with the subject.  
x Contact IWRS to record the visit. 
If the subject is on an every-2-weeks study drug regimen, administer study drug via IV infusion. 
Monitor the subject for at least 60 minutes post-dose for any adverse reactions, including any 
infusion-site reactions. 
8.4 Visit 4 (Week 4 r 2 Days) 
Set up the appropriate number of study drug vials to thaw in the refrigerator approximately 16 to 
24 hours before scheduled study drug administration and according to Section 6.1.2. 
Complete the following procedures during the visit: 
x Collect a urine sample for a urine pregnancy test for female subjects of childbearing 
potential and for urinalysis. 
o Any subject with a positive pregnancy test result must complete ET procedures and will 
be recorded as ET. 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 

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x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect pre-dose blood samples for serum PK, CSF1, and anti–AMB-05X antibody. 
x Administer study drug via IV infusion. 
x Collect post-dose blood samples for serum PK and CSF1 within 15 minutes after the end 
of infusion. 
x Monitor the subject for at least 60 minutes post-dose for any adverse reactions, including 
any infusion-site reactions. 
x Schedule the next visit with the subject.  
x Contact IWRS to record the visit. 
8.5 Visit 5 (Week 6 r 3 Days) 
If the subject is on an every-2-weeks study drug regimen, set up the appropriate number of study 
drug vials to thaw in the refrigerator approximately 16 to 24 hours before scheduled study drug 
administration and according to Section 6.1.2. 
For all subjects, complete the following procedures during the visit: 
x Collect a urine sample for urinalysis. 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Conduct a full physical examination and document any changes since the previous 
physical exam. 
x Perform a 12-lead ECG. 
x Evaluate ROM of the affected joint. 
x Administer the following PRO instruments: 
o PROMIS Physical Function Scale 
o Worst Stiffness NRS 
o BPI Short Form 
o EQ-5D-5L 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect blood samples for serum PK and CSF1 (before study drug administration, if 
applicable for the subject). 
x Perform MRI. A central radiologist will evaluate MRI scans to assess tumors. 

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x Schedule the next visit with the subject.  
x Contact IWRS to record the visit. 
If the subject is on an every-2-weeks study drug regimen, administer study drug via IV infusion. 
Monitor the subject for at least 60 minutes post-dose for any adverse reactions, including any 
infusion-site reactions. 
8.6 Visit 6 (Week 8 r 3 Days) 
Set up the appropriate number of study drug vials to thaw in the refrigerator approximately 16 to 
24 hours before scheduled study drug administration and according to Section 6.1.2. 
Complete the following procedures during the visit: 
x Collect a urine sample for a urine pregnancy test for female subjects of childbearing 
potential and for urinalysis. 
o Any subject with a positive pregnancy test result must complete ET procedures and will 
be recorded as ET. 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect pre-dose blood samples for serum PK and CSF1 (and anti–AMB-05X antibody, if 
the subject will be receiving the last dose of study drug at this visit). 
x Optional assessment: If the subject will be receiving the last dose of study drug at this 
visit, collect pre-dose synovial fluid for PK, CSF1, and anti–AMB-05X antibody. 
x Administer study drug via IV infusion to the affected joint. 
x Collect post-dose blood samples for serum PK and CSF1 within 15 minutes after the end 
of infusion. 
x Monitor the subject for at least 60 minutes post-dose for any adverse reactions, including 
any infusion-site reactions. 
x Schedule the next visit with the subject.  
x Contact IWRS to record the visit. 
8.7 Visit 7 (Week 10 r 3 Days) 
If the subject is on an every-2-weeks study drug regimen, set up the appropriate number of study 
drug vials to thaw in the refrigerator approximately 16 to 24 hours before scheduled study drug 
administration and according to Section 6.1.2. 

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For all subjects, complete the following procedures during the visit: 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Collect a urine sample for urinalysis. 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect blood samples for serum PK and CSF1 (before study drug administration, if 
applicable for the subject). 
x Schedule the next visit with the subject.  
x Contact IWRS to record the visit. 
If the subject is on an every-2-weeks study drug regimen (and thus will be receiving the last dose 
of study drug at this visit): 
x Collect a pre-dose blood sample for serum anti–AMB-05X antibody. 
x Optional assessment: collect synovial fluid for PK, CSF1, and anti–AMB-05X antibody. 
x Administer study drug via IV infusion. 
x Collect post-dose blood samples for serum PK and CSF1 within 15 minutes after the end 
of infusion. 
x Monitor the subject for at least 60 minutes post-dose for any adverse reactions, including 
any infusion-site reactions. 
8.8 Visit 8 (Week 12 r 3 Days) or Early Termination 
Complete the following procedures during the visit: 
x Collect a urine sample for a urine pregnancy test for female subjects of childbearing 
potential and for urinalysis. 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Conduct a full physical examination and document any changes since the previous 
physical exam. 
x Perform a 12-lead ECG. 
x Evaluate ROM of the affected joint. 

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x Administer the following PRO instruments: 
o PROMIS Physical Function Scale 
o Worst Stiffness NRS 
o BPI Short Form 
o EQ-5D-5L 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect blood samples for serum PK and CSF1. 
x Perform MRI. A central radiologist will evaluate MRI scans to assess tumors. 
x Schedule the next visit with the subject.  
x Contact IWRS to record the visit. 
8.9 Follow-up Visit 9 (Week 14 r 3 Days) 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with 
subject in a sitting position after having rested for 5 minutes. 
x Conduct a full physical examination and document any changes since the previous visit. 
x Evaluate ROM of the affected joint. 
x Administer the Worst Stiffness NRS. 
x Collect a urine sample for a urine pregnancy test for female subjects of childbearing 
potential and for urinalysis. 
x Collect blood samples for clinical laboratory (chemistry and hematology). 
x Collect blood samples for serum PK, CSF1, and anti–AMB-05X antibody. 
x Schedule the next visit with the subject. 
x Contact IWRS to record the visit. 
8.10 Follow-up Visit 10 (Week 24 r 7 Days) 
x Record any changes in concomitant medications since the previous visit. 
x Record any new AEs that may have occurred since the previous visit and follow up on the 
status of any existing AEs. 
x Obtain weight. 
x Measure vital signs (blood pressure, heart rate, temperature, and respiratory rate) with the 
subject in a sitting position after having rested for 5 minutes. 
x Conduct a full physical examination and document any changes since the previous visit. 

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x Evaluate ROM of the affected joint. 
x Administer the following PRO instruments: 
o PROMIS Physical Function Scale 
o Worst Stiffness NRS 
o BPI Short Form 
o EQ-5D-5L 
x Collect a urine sample for a urine pregnancy test for female subjects of childbearing 
potential and for urinalysis. 
x Collect blood samples for clinical laboratory tests (chemistry and hematology). 
x Collect blood samples for serum PK and CSF1. 
x Perform MRI. A central radiologist will evaluate MRI scans to assess tumors. 
x Contact IWRS to record the visit. 
8.11 Early Termination Procedures 
A subject who terminates early from the study and does not withdraw consent for study 
participation will be asked to complete Visit 8 (Week 12) (Section 8.8), Visit 9 (Week 14) 
(Section 8.9), and Visit 10 (Week 24) (Section 8.10) (whichever visits the subject has yet to 
complete at the time of ET). Study personnel will make every effort to conduct all 
protocol-specified procedures to complete the study, including a final MRI. 

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9 STATISTICAL CONSIDERATIONS 
9.1 Sample Size Determination 
Based on prior Phase 1 experience and an anticipated treatment effect with AMB-05X in this 
population, the sample size of 3 to 12 subjects per cohort is anticipated to provide sufficient data 
for PK/PD analysis and an estimate of safety, tolerability, and efficacy. 
9.2 Populations for Analyses 
Safety Population: This population will include all subjects who receive at least 1 dose of study 
drug. The Safety Population will be used for analysis of safety data. 
Modified Intent-To-Treat (mITT) Population: This population will include all subjects who 
receive at least 1 dose of study drug and have both baseline and post-baseline data for at least 
1 efficacy endpoint. The mITT Population will be the primary analysis population for efficacy 
analysis. 
Per-Protocol Population (PP): This population will include subjects in the mITT Population 
who complete the study and do not have protocol deviations that could significantly affect the 
interpretation of the endpoints. The PP Population will be identified before database lock. The 
PP Population may be used for sensitivity analyses of efficacy endpoints. 
9.3 Statistical Analyses 
9.3.1 General Approach 
All study data will be summarized by dose cohort and overall using descriptive statistics. Data 
from all investigational centers will be pooled for analyses. Unless otherwise specified, 
descriptive statistics for numeric data (eg, age, weight) will include the number of subjects with 
data to be summarized (n), mean, SD, median, minimum, and maximum. Categorical/qualitative 
data (eg, sex, race) will be presented using absolute and relative frequency counts and 
percentages. All summaries, statistical analyses, and individual subject data listings will be 
completed using SAS software (SAS Institute, Inc; Cary, North Carolina) Version 9.3 or later. 
A detailed statistical analysis plan will be finalized before the first DMC meeting and will be 
provided separately. 
9.3.2 Handling Missing Data 
All available data will be presented as descriptive summaries or listings. Missing data will not be 
imputed. 
9.3.3 Demographics and Baseline Characteristics 
Demographics and baseline characteristics will be summarized descriptively for the Safety 
Population. 
9.3.4 Safety Analyses 
Safety analyses will include all subjects who receive at least 1 dose of study drug. 

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The number of subjects exposed to study drug and the duration of exposure will be summarized. 
All AEs reported will be listed, documenting severity, start and stop date and time, possible 
relationship to study drug, action taken, and outcome. TEAEs are defined as AEs that occur after 
the first dose of study drug. Verbatim terms will be mapped to PTs and related SOCs using 
MedDRA. PTs and SOCs will be tabulated by dose cohort and overall. All reported AEs will be 
summarized by the number of subjects reporting each AE, SOC, PT, severity, and relationship to 
study drug. Multiple occurrences of an AE will be counted only once per subject per SOC and 
PT in summary tables. 
The following will be summarized by SOC, PT, and dose cohort: 
x Incidence of all TEAEs 
x Incidence of all TEAEs by maximum severity (severe, moderate, and mild) specified by 
investigators 
x Incidence of TEAEs related to study drug as determined by investigators 
x Incidence of serious TEAEs 
x Incidence of TEAEs leading to early discontinuation/withdrawal from the study 
Safety labs (including hematology, chemistry, and urinalysis), vital signs, and ECGs will be 
tabulated using descriptive statistics. Abnormal/out-of-range findings and changes from pre-dose 
to post-dose will be listed by subject. Safety labs will be displayed graphically. Shift tables will 
be provided for all laboratory variables. For ECG parameters, heart rate, RR, PR, QRS, and 
QTcF will be summarized. 
Concomitant medication usage will be summarized. The World Health Organization Drug 
Dictionary will be used to classify concomitant medications by therapeutic class and generic 
name based on ATC (Anatomical Therapeutic Chemical) code level 3. A subject will only be 
counted once in each unique ATC class and generic name if the subject uses multiple drugs. 
9.3.5 Efficacy Analyses 
Efficacy endpoints will be summarized using descriptive statistics and 95% confidence intervals. 
Exploratory hypotheses testing may be conducted using a significance level of 0.05 without 
adjustment for multiplicity. 
9.3.6 Pharmacokinetic Analyses 
AMB-05X concentrations will be summarized by dose, regimen, and nominal collection time. If 
warranted, a population PK analysis may be conducted using data from the current study and 
relevant data from other clinical studies. In addition, an exposure-response analysis may be 
attempted using the population approach. 

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10 REGULATORY, ETHICAL, AND STUDY OVERSIGHT 
CONSIDERATIONS 
10.1 Administrative Procedures 
10.1.1 Ethics Review 
The protocol and the ICF must be reviewed and approved by a properly constituted IRB/IEC 
and/or national competent authority before study start. A signed and dated statement that the 
protocol and ICF have been approved by the IRB/IEC and/or national competent authority must 
be given to the Sponsor or its designee before study start.  
Before study start, the Investigator is required to sign a protocol signature page confirming 
agreement to conduct the study in accordance with the specified documents and with all of the 
instructions and procedures found in this protocol. The Investigator agrees to provide access to 
all relevant data and records to the Sponsor’s monitors, auditors, and quality assurance 
representatives; IRBs/IECs; and regulatory authorities, as required.  
The Principal Investigator is responsible for informing the IRB/IEC of any amendment to the 
protocol in accordance with local requirements. In addition, the IRB/IEC must approve all 
advertising used to recruit subjects for the study. The protocol must be re-approved by the 
IRB/IEC upon receipt of amendments and annually, as local regulations require. 
The Principal Investigator is also responsible for providing the IRB/IEC with reports of any 
reportable serious adverse drug reactions from any other study conducted with the investigational 
product. The Sponsor will provide this information to the Principal Investigator. 
At the completion of the study, the Investigator must provide the Sponsor a copy of the final 
conduct report that was submitted to their IRB/IEC, including a review of AEs, as described by 
Code of Federal Regulations (CFR) Title 21 Part 312.64. 
10.1.2 Good Clinical Practice 
This study will be conducted in accordance with principles of GCP as promulgated by the ICH, 
the US FDA, and applicable local regulations. GCP is an international ethical and scientific 
quality standard for designing, conducting, recording, and reporting trials that involve the 
participation of human subjects. Compliance with this standard provides public assurance that 
the rights, safety, and well-being of human subjects are protected under current ethical principles 
and that the clinical study data are credible.  
Current GCP standards may be found in ICH Guidance E6 (R2) (Good Clinical Practice: 
Consolidated Guidance). This guidance describes the principles of GCP and the obligations of 
the IRB/IEC, the Investigator, and the Sponsor in conducting this study in accordance with those 
principles. 
10.1.3 Informed Consent 
A complete description of the study is to be presented to each potential study subject, and a 
signed and dated (and, where required, witnessed) ICF that has been approved by the IRB/IEC 
will be obtained before any study-specific procedures are performed. 

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The subject must be able to communicate well with study staff, understand and comply with the 
requirements of the study, and read and voluntarily sign the ICF and the HIPAA authorization, if 
applicable, before the conduct of any study-specific procedures. All reasonable efforts should be 
taken by the study staff to ensure that the subject is able to comprehend what participation 
means. All consent documents will be provided in the subject’s native language and in a form the 
subject is able to comprehend. 
Females of childbearing potential must be informed that being on the study drug may involve 
unknown risks to a fetus if pregnancy were to occur during the study and agree to adhere to the 
contraception requirement. Male participants must be informed of potential risks to the fetus of a 
partner if conception were to occur during the study and agree to adhere to the contraception 
requirement. If there is any concern that the participant will not reliably comply, the participant 
will not be entered into the study.  
The process of obtaining informed consent must be documented in the subject source documents. 
The Principal Investigator must maintain the original signed ICF. A copy of the signed ICF will 
be given to the subject. 
All consent documents and procedures must comply with national laws, respective regulations, 
and IRBs/IECs relevant to the country where the subject participates. The Sponsor will provide 
Investigators with a proposed ICF that complies with ICH GCP guidelines and regulatory 
requirements and that the Sponsor considers appropriate for this study. The Sponsor must agree 
to any Investigator-suggested changes to the proposed ICF before the ICF is submitted to the 
IRB/IEC, and a copy of the approved ICF must be provided to the Sponsor’s monitor after 
IRB/IEC approval. 
10.1.4 Subject Confidentiality 
In order to maintain subject privacy, all eCRFs, study drug accountability records, and study 
reports and communications will use the 6-digit assigned Subject ID. The Investigator will grant 
the monitor and auditor from the Sponsor or its designee and any regulatory authority access to 
the subject’s original medical records to verify data gathered on the eCRFs and to audit the data 
collection process. The subject’s confidentiality will be maintained and will not be made publicly 
available to the extent permitted by applicable laws and regulations. The Sponsor will comply 
with the requirements of US HIPAA regulations and the European General Data Protection 
Regulation. 
10.1.5 Protocol Deviation 
Investigators will apply due diligence to avoid a protocol deviation. Unless there is a safety 
concern, there should be no deviation from the study protocol. In the event of a safety concern, 
the Investigator/designee must document and explain the reason for any deviation from the 
approved protocol. The Investigator may implement a deviation from or a change to the protocol 
to eliminate an immediate hazard to subjects without prior IRB/IEC or regulatory authority 
approval. Immediately after the implemented deviation or change, the Investigator must submit a 
report explaining the reason for protocol deviation to the Sponsor or its designee and to the 
IRB/IEC (if required). 

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10.1.6 Protocol Amendment 
All amendments to the protocol must be documented in writing; reviewed and approved by the 
Sponsor, the controlling regulatory authority, and each Investigator; and submitted to the 
IRB/IEC for approval before implementation.  
If the protocol amendment substantially alters the study design or potential risk to the subject, 
new written informed consent for continued participation in the study must be obtained from 
each subject who is affected by the change. 
10.1.7 Study Termination 
This multicenter study as a whole or conduct of the study at any particular study site(s), 
whichever is applicable, may be terminated prematurely for the following reasons: 
x The controlling regulatory authority terminates the study in the applicable region. 
x The competent IRB/IEC for a particular study site does not approve the study or 
irrevocably withdraws its approval of the study. 
x It is reasonable to conclude that terminating the study would be in the interests of the 
health of the study subjects. 
For example, the study may be terminated if new information arises that suggests 
continuing the study may pose an undue risk to subject safety or well-being. The Sponsor 
will review emerging safety data to identify safety and tolerability signals. These data 
include AEs and their associated frequency and severity, TEAEs, SAEs, SUSARs, and 
clinically significant changes in laboratory results, ECGs, vital signs, and physical 
examinations. New nonclinical safety data will also be assessed and considered in 
decisions on termination. 
x In the event of a negative development in the benefit/risk profile, it is not possible to 
increase the amount of insurance coverage accordingly. 
x It becomes clear that continuation of the study cannot serve any scientific purpose, and this 
is confirmed by the IRB/IEC that approved the study. 
x The Sponsor or the particular study site is declared insolvent, has had a petition for 
bankruptcy filed against it, or is dissolved as a legal entity. 
x The principal investigator of a study site is no longer capable of performing the tasks of the 
principal investigator, and no replacement acceptable to both the Sponsor and the site can 
be found within a reasonable period. 
x The Sponsor or the particular study site fails to comply with the obligations arising from 
their clinical trial agreement and, provided this failure can be remedied, does not remedy 
the noncompliance within 30 days of receiving a written request from the other party to 
comply, unless failure to comply is not in reasonable proportion to the premature 
termination of the study. 
x Circumstances beyond the control of the Sponsor or the particular study site render study 
continuation unreasonable. 

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If the study is terminated, the Sponsor will endeavor to provide adequate notice and clear 
guidance on study termination procedures to support the safe withdrawal of subjects from the 
study. 
10.2 Data Handling and Recordkeeping 
10.2.1 Source Documents and Electronic Case Report Forms 
Source data is defined as all information in original records and certified copies of original 
records of clinical findings, observations, or other activities in a clinical study necessary for the 
evaluation and reconstruction of the clinical study. Source data are contained in source 
documents (ie, original records or certified copies).  
Study center staff will collect and record source data for the study in source documents and 
transcribe them into eCRFs, which use fully validated software that conforms to 21 CFR Part 11 
requirements. Site staff will not be given access to the electronic data capture system until they 
have been trained. 
It is the Investigator’s responsibility to ensure the accuracy, completeness, and timeliness of the 
data reported in the subject’s source documents / eCRFs. The source documents / eCRFs should 
indicate the subject’s participation in the study and should document the dates and details of 
study procedures, AEs, and subject status. The Investigator must electronically sign the 
completed eCRFs to endorse the recorded data. 
The Investigator will retain all completed source documents. The Sponsor will retain the eCRF 
archive and audit trail for all investigative sites. A site-specific eCRF archive and audit trail will 
be provided to each Investigator at the close of the study. 
10.2.2 Retention of Records 
Subject records, source documents, monitoring visit logs, eCRFs, inventories of investigational 
product, regulatory documents, and other correspondence pertaining to the study must be kept in 
the appropriate study files at the site.  
The Investigator will maintain all study records according to ICH GCP and applicable local 
regulatory requirements. Records will be retained for as long as mandated by applicable local 
regulatory requirements and for at least 2 years after the last marketing application approval or at 
least 2 years after formal discontinuation of clinical development of the investigational product. 
The essential documents should be retained for longer than 2 years if required by applicable 
regulatory requirements or by an agreement with the Sponsor. 
If the Investigator withdraws from the responsibility of keeping the study records, custody must 
be transferred to a person willing to accept the responsibility. The Sponsor must be notified in 
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10.3 Study Oversight 
10.3.1 Study Monitoring 
Before an investigational site can enter a subject into the study, a representative of the Sponsor 
will visit the investigational site to: 
x Determine the adequacy of the facilities 
x Discuss with the Investigator(s) and other personnel their responsibilities regarding 
protocol adherence and the responsibilities of the Sponsor or its representatives. This will 
be documented in a Clinical Study Agreement between the Sponsor and the Investigator. 
During the study, a monitor from the Sponsor or its representative will have regular contact with 
the investigational site to: 
x Provide information and support to the Investigator(s) 
x Confirm that facilities remain acceptable 
x Confirm that the investigational team is adhering to the protocol, that data are being 
accurately recorded on the eCRFs, and that investigational product accountability checks 
are being performed 
x Perform source data verification. This includes a comparison of the data in the eCRFs with 
the subject’s medical records at the hospital or practice and other records relevant to the 
study. This will require direct access to all original records for each subject (eg, clinic 
charts). 
x Record and report any protocol deviations not previously sent to the Sponsor 
x Confirm that AEs and SAEs have been properly documented on eCRFs, that any SAEs 
have been forwarded to the Sponsor or its designee, and that those SAEs that met criteria 
for reporting have been forwarded to the IRB/IEC 
The Investigator agrees to allow the monitor to inspect the drug storage area, study drug stocks, 
drug accountability records, subject charts and study source documents, and other records related 
to study conduct. 
The monitor will be available between visits if the Investigator(s) or other staff need information 
or advice. 
10.3.2 Audits and Inspections 
Authorized representatives of the Sponsor, a regulatory authority, or an IRB/IEC may visit the 
site to perform audits or inspections, including source data verification. The Investigator agrees 
to allow the auditor direct access to all relevant documents and to allocate his or her time, and 
that of site personnel, to the auditor to discuss findings and any relevant issues. Sufficient prior 
notice will be provided to allow the Investigator to prepare properly for the audit. 
The purpose of an audit or inspection by the Sponsor is to systematically and independently 
examine all study-related activities and documents to determine whether these activities were 
conducted and data were recorded, analyzed, and accurately reported according to the protocol, 
ICH GCP guidelines, and any applicable regulatory requirements.  

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Other regulatory agencies may also conduct similar auditing procedures. The Investigator should 
immediately notify the Sponsor’s study monitor of any upcoming regulatory inspection. 
10.4 Publication Policy 
The Sponsor acknowledges the importance of public disclosure of study results. 
10.4.1 Clinical Trial Database 
The Sponsor will post key design elements of this protocol in a publicly accessible database such 
as clinicaltrials.gov. In addition, within 12 months after study completion and after finalization 
of the study report, the Sponsor will post the results of this study in a publicly accessible 
database of clinical trial results. 
10.4.2 Publishing Study Results 
The Sponsor anticipates that the results of this study will be presented at scientific meetings 
and/or published in a peer-reviewed scientific or medical journal. After study completion, the 
Sponsor shall form a Publications Committee comprising the Investigators participating in the 
study and representatives from the Sponsor to oversee the initial publication of overall study 
results, which will reflect the experience of all participating study centers. Authorship shall be 
determined in accordance with generally accepted academic standards. 
Individual Investigators who wish to publish or publicly disclose study results must wait until 
after the Sponsor’s initial publication of overall study results to do so, provided the Sponsor does 
so within 12 months after study completion/termination. Subsequently, individual Investigators 
may publish results from the study, either in part or in full, in compliance with their agreement 
with the Sponsor. Investigators will provide proposed manuscripts to the Sponsor at least 90 days 
before submission of the manuscript to a publisher so that the Sponsor may review and respond 
or so that the Sponsor has the opportunity to file patent applications. Similarly, the Sponsor will 
provide any Sponsor-prepared manuscript to Investigators for review at least 30 days before 
submission to a publisher. 
Before the Sponsor publicly discloses information from the study, provided the Sponsor does so 
before 12 months after study completion/termination, the Investigator agrees not to publicly 
disclose such information in any way without prior written permission from the Sponsor, as such 
disclosure would constitute violation of the Sponsor’s confidentiality restrictions and a detriment 
to the Sponsor’s intellectual property rights. 

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LIST OF REFERENCES 
Benner B, Good L, Quiroga D, et al. Pexidartinib, a novel small molecule CSF-1R inhibitor in 
use for tenosynovial giant cell tumor: a systematic review of pre-clinical and clinical 
development. Drug Des Devel Ther. 2020;14:1693-1704. 
Brahmi M, Vinceneux A, Cassier PA. Current systemic treatment options for tenosynovial giant 
cell tumor/pigmented villonodular synovitis: targeting the CSF1/CSF1R axis. Curr Treat 
Options Oncol. 2016;17(2):10. 
Cassier PA, Italiano A, Gomez-Roca CA, et al. CSF1R inhibition with emactuzumab in locally 
advanced diffuse-type tenosynovial giant cell tumours of the soft tissue: a dose-escalation and 
dose-expansion phase 1 study. Lancet Oncol. 2015;16(8):949-956. 
Cleeland CS, Ryan KM. Pain assessment : global use of the Brief Pain Inventory. Ann Acad Med 
Singap. 1994;23(2):129-138. 
Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0. US Dept of Health 
and Human Services, National Institutes of Health, National Cancer Institute; 2017. 
Cupp JS, Miller MA, Montgomery KD, et al. Translocation and expression of CSF1 in 
pigmented villonodular synovitis, tenosynovial giant cell tumor, rheumatoid arthritis and other 
reactive synovitides. Am J Surg Pathol. 2007;31(6):970-976. 
de Saint Aubain Somerhausen N, van de Rijn M. Tenosynovial giant cell tumor, localized type / 
diffuse type. In: Fletcher CDM, Bridge JA, Hogendoorn PCW, Mertens F, eds. World Health 
Organization Classification of Tumours of Soft Tissue and Bone. 4th ed. IARC Press; 2013:100-
103. 
Ehrenstein V, Andersen SL, Qazi I, et al. Tenosynovial giant cell tumor: incidence, prevalence, 
patient characteristics, and recurrence. A registry-based cohort study in Denmark. J Rheumatol. 
2017;44(10):1476-1483. 
Eisenhauer EA, Therasse P, Bogaerts J, et al. New response evaluation criteria in solid tumours: 
revised RECIST guideline (version 1.1). Eur J Cancer. 2009;45(2):228-247. 
Gelderblom H, van de Sande M. Pexidartinib: first approved systemic therapy for patients with 
tenosynovial giant cell tumor. Future Oncol. 2020;16(29):2345-2356. 
Giustini N, Bernthal NM, Bukata SV, Singh AS. Tenosynovial giant cell tumor: case report of a 
patient effectively treated with pexidartinib (PLX3397) and review of the literature. Clin 
Sarcoma Res. 2018;8:14. 
Granowitz S, D’Antonio J, Mankin HL. The pathogenesis and long-term end results of 
pigmented villonodular synovitis. Clin Orthop Relat Res. 1976;(114):335-351. 
Heads of Medicines Agencies. Clinical Trials Facilitation and Coordination Group. 
Recommendations related to contraception and pregnancy testing in clinical trials. 2014. 
https://www.hma.eu/fileadmin/dateien/Human Medicines/01-
About HMA/Working Groups/CTFG/2014 09 HMA CTFG Contraception.pdf 

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Mastboom MJL, Verspoor FGM, Verschoor AJ, et al. Higher incidence rates than previously 
known in tenosynovial giant cell tumors. Acta Orthop. 2017;88(6):688-694. 
Murphey MD, Rhee JH, Lewis RB, Fanburg-Smith JC, Flemming DJ, Walker EA. Pigmented 
villonodular synovitis: radiologic-pathologic correlation. Radiographics. 2008;28(5):1493-1518. 
Ostuni R, Kratochvill F, Murray PJ, Natoli G. Macrophages and cancer: from mechanisms to 
therapeutic implications. Trends Immunol. 2015;36(4):229-239. 
Palmerini E, Staals EL, Maki RG, et al. Tenosynovial giant cell tumour/pigmented villonodular 
synovitis: outcome of 294 patients before the era of kinase inhibitors. Eur J Cancer. 
2015;51(2):210-217. 
Papadopoulos KP, Gluck L, Martin LP, et al. First-in-human study of AMG 820, a monoclonal 
anti-colony-stimulating factor 1 receptor antibody, in patients with advanced solid tumors. Clin 
Cancer Res. 2017;23(19):5703-5710. 
Ponce R, Abad L, Amaravadi L, et al. Immunogenicity of biologically-derived therapeutics: 
assessment and interpretation of nonclinical safety studies. Regul Toxicol Pharmacol. 
2009;54(2):164-182. 
Radi ZA, Koza-Taylor PH, Bell RR, et al. Increased serum enzyme levels associated with 
Kupffer cell reduction with no signs of hepatic or skeletal muscle injury. Am J Pathol. 
2011;179(1):240-247. 
Staals EL, Ferrari S, Donati DM, Palmerini E. Diffuse-type tenosynovial giant cell tumour: 
current treatment concepts and future perspectives. Eur J Cancer. 2016;63:34-40. 
Stepensky D. Local versus systemic anti-tumor necrosis factor-Į HIIHFWV RI DGDOLPXPDE LQ
rheumatoid arthritis: pharmacokinetic modelling analysis of interaction between a soluble target 
and a drug. Clin Pharmacokinet. 2012;51(7):443-455. 
Tap WD, Wainberg ZA, Anthony SP, et al. Structure-guided blockade of CSF1R kinase in 
tenosynovial giant-cell tumor. N Engl J Med. 2015;373(5):428-437. 
Tap WD, Gelderblom H, Palmerini E, et al. Pexidartinib versus placebo for advanced 
tenosynovial giant cell tumour (ENLIVEN): a randomised phase 3 trial. Lancet. 
2019;394(10197):478-487. 
Turalio [package insert]. Daiichi Sankyo, Inc; 2020. 
West RB, Rubin BP, Miller MA, et al. A landscape effect in tenosynovial giant-cell tumor from 
activation of CSF1 expression by a translocation in a minority of tumor cells. Proc Natl Acad Sci 
USA. 2006;103(3):690-695. 

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APPENDIX 1.
PROMIS PHYSICAL FUNCTION SCALE

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APPENDIX 2. WORST STIFFNESS NUMERIC RATING SCALE 
The following question asks about stiffness at the site of your tumor. Please rate your stiffness by 
checking the one number that best describes your stiffness at its WORST in the last 24 hours. 
0 is no stiffness and 10 is stiffness as bad as you can imagine. 
  
0
1
2
3
4
5
6
7
8
9
10 
 
 

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APPENDIX 3.
BRIEF PAIN INVENTORY SHORT FORM

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APPENDIX 4.
EQ-5D-5L

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APPENDIX 5. COVID-19 CONTINGENCY PLAN 
COVID-19 Risk Mitigation 
To mitigate any risk of COVID-19 infection that might be associated with study participation, 
study conduct will be modified in the following ways in regions with COVID-19–related 
shelter-in-place orders, shutdown of clinical trial sites, or other restrictions that would prevent 
subjects from going to study centers. 
x The study will not screen or enroll new subjects in such regions.  
x If enrollment has already begun in a region and such restrictions are issued, remote study 
visits consisting of a combination of home health visits and telemedicine may be 
conducted in place of certain in-clinic visits. 
x The Investigator must consult with the Medical Monitor to determine the best course of 
action, particularly for situations not delineated here or for further clarification. 
If clinic visits are no longer possible, activities that can only be performed in the clinic will not 
be conducted. Once COVID-19–related restrictions are lifted, sites should attempt to conduct any 
missed study activities via an unscheduled visit. 
If a subject or a member of the subject’s household is suspected or confirmed to have 
COVID-19, only telemedicine activities can proceed. Once the subject or member of his/her 
household no longer has suspected or confirmed COVID-19, missed study activities should be 
conducted as an unscheduled visit via home health nurse visit or clinic visit, as the situation 
allows. 
Subject Disposition in the Event of COVID-19 Infection 
If a subject is suspected or confirmed to have COVID-19, the Investigator will consider AE and 
SAE guidelines (Section 7.3) and work with the subject and Medical Monitor to assess safety 
and determine whether it is in the best interest of the subject to discontinue study drug / 
withdraw from the study or to continue study drug. If a subject discontinues study drug / 
withdraws from the study because of COVID-19, the reason for early termination will be 
captured as such. 
Regulatory and Study Oversight Considerations 
If onsite monitoring visits are not possible because of COVID-19, remote monitoring may occur, 
if allowed by local and federal laws and regulations. Home healthcare staff will transfer any 
source documents collected at a home health visit to the trial site as soon as the situation allows. 
If a protocol deviation is the result of COVID-19–related circumstances, this information should 
be captured.