A Multicenter, Open-label, Single-arm, Phase 2 Study to Evaluate Safety and Organ Uptake Quantitation Repeatability of 124I AT-01 Using Positron Emission Tomography/X-ray Computed Tomography (PET/CT) in Subjects With Systemic Amyloidosis
Phase: PHASE2
Conditions: Amyloidosis
Sponsor: Attralus, Inc.

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 1 - 
 
CLINICAL STUDY PROTOCOL 
Protocol Title: 
A Multicenter, Open-label, Single-arm, Phase 2 Study to 
Evaluate Safety and Organ Uptake Quantitation Repeatability of 
124I-AT-01 using Positron Emission Tomography/X-ray 
Computed Tomography (PET/CT) in Subjects with Systemic 
Amyloidosis 
Protocol Number: 
AT01-001 
Amendment Number: 
2.0 
Version Date: 
08 March 2022 
Supersedes: 
1.1 (Dated: 07 October 2021) 
Investigational Product: 
124I-AT-01 
Study Phase: 
2 
Study Acronym/Name: 
N/A 
Brief Protocol Title: 
An Open-label, Phase 2 Study to Evaluate Organ Level Uptake 
Quantitation Repeatability of 124I-AT-01 in Subjects with 
Systemic Amyloidosis 
Sponsor Name and 
Address: 
Attralus, Inc. 
50 Francisco Street, Suite 450 
San Francisco, CA 94133 
Sponsor Contact/Medical 
Monitor: 
Gregory Bell, MD 
Chief Medical Officer 
Tel.: +1 415-435-6210 
Email: gbell@attralus.com 
IND Number: 
132282 
EudraCT Number: 
N/A 
CONFIDENTIAL 
This protocol contains confidential information about a product provided by Attralus, Inc. This information is 
provided for the exclusive use of the Investigators participating in this study. Any and all confidential 
information contained herein may not be disclosed to any other person or party without the prior written 
consent of Attralus, Inc. Attralus, Inc. ™/® are trademarks of Attralus, Inc. All other brand names/product 
names are trademarks of their respective owners. 
CONTACT FOR MEDICAL EMERGENCIES: 
Gregory Bell, M.D.1-415-845-4304 
gbell@attralus.com 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 2 - 
SPONSOR SIGNATORY 
 
Study Title: 
A Multicenter, Open-label, Single-arm, Phase 2 Study to Evaluate 
Safety and Organ Uptake Quantitation Repeatability of 124I-AT-01 
using Positron Emission Tomography/X-ray Computed 
Tomography (PET/CT) in Subjects with Systemic Amyloidosis 
Protocol Number: 
AT01-001 
Amendment Number: 
2.0 
Version Date: 
08 March 2022 
Protocol Accepted and Approved by: 
Gregory Bell, MD 
Chief Medical Officer 
Attralus, Inc. 
329 Oyster Point Blvd, Third Floor 
South San Francisco, CA 94080 
 
 
 
________________________________________________ 
Signature 
 
 
 
__________________________ 
Date 
 
 
 
DocuSign Envelope ID: BC4932CC-2F4A-4330-8536-3DB9F188D3A4
3/8/2022

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 3 - 
PRINCIPAL INVESTIGATOR SIGNATORY 
 
Study Title: 
A Multicenter, Open-label, Single-arm, Phase 2 Study to Evaluate 
Safety and Organ Uptake Quantitation Repeatability of 124I-AT-01 
using Positron Emission Tomography/X-ray Computed 
Tomography (PET/CT) in Subjects with Systemic Amyloidosis 
Protocol Number: 
AT01-001 
Amendment Number: 
2.0 
Version Date: 
08 March 2022 
 
I have read the protocol described above, concur that it contains all information necessary to 
conduct the study, and agree to abide by all provisions set forth therein. I agree to conduct this 
study in accordance with the International Council on Harmonisation Tripartite Guideline on 
Good Clinical Practice (ICH E6 GCPs) and applicable local regulations. I will not initiate the 
study until I have obtained written approval by the appropriate Institutional Review Board 
(IRB) and have complied with all financial and administrative requirements of the governing 
body of the clinical institution and the Sponsor. I will obtain written informed consent from 
each study subject prior to performing any study specific procedures that are NOT my routine 
standard of care. I understand that my signature on a case report form indicates that the data 
therein has been reviewed and accepted by me. I understand that this document and related 
information is subject to confidentiality terms found in my signed Confidentiality or Clinical 
Services Agreement. I agree to protect the confidentiality of my patients when allowing the 
Sponsor of this clinical investigation, and/or relevant regulatory authorities and IRBs, direct 
access to my medical records for study subjects. 
 
 
________________________________________________ 
Signature 
 
 
__________________________ 
Date 
 
 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 4 - 
TABLE OF CONTENTS 
1.0 
PROTOCOL SUMMARY ..............................................................................................10 
1.1 
Synopsis .................................................................................................................10 
1.2 
Study Schema.........................................................................................................13 
1.3 
Schedule of Activities ............................................................................................14 
2.0 
INTRODUCTION............................................................................................................16 
2.1 
Study Rationale ......................................................................................................16 
2.2 
Background ............................................................................................................16 
2.2.1 
Systemic Amyloidosis ...........................................................................16 
2.2.2 
Description of 124I-AT-01 .....................................................................17 
2.3 
Benefit/Risk Assessment .......................................................................................18 
2.3.1 
Potential Benefits ..................................................................................18 
2.3.2 
Potential Risks .......................................................................................18 
2.3.3 
Benefit/Risk Conclusion .......................................................................20 
3.0 
OBJECTIVES AND ENDPOINTS ................................................................................21 
4.0 
STUDY DESIGN ..............................................................................................................22 
4.1 
Overall Design .......................................................................................................22 
4.1.1 
Screening Period ...................................................................................22 
4.1.2 
Pre-Administration Period ....................................................................22 
4.1.3 
Administration Period ...........................................................................22 
4.1.4 
Follow-up Period ...................................................................................23 
4.1.5 
Early Termination Visit ........................................................................24 
4.2 
Scientific Rationale for Study Design ....................................................................24 
4.2.1 
Choice of Population .............................................................................24 
4.2.2 
Choice of Primary Endpoint and Analysis ............................................24 
4.2.3 
Choice of Duration of Treatment and Follow-up ..................................25 
4.3 
Justification for Dose(s) and Posology ..................................................................25 
4.4 
End of Treatment Definition ..................................................................................25 
4.5 
End of Study Definitions .......................................................................................25 
4.6 
Subject Completion Definition ..............................................................................26 
5.0 
STUDY POPULATION ..................................................................................................27 
5.1 
Inclusion Criteria ...................................................................................................27 
5.2 
Exclusion Criteria ..................................................................................................28 
5.3 
Lifestyle Considerations ........................................................................................29 
5.4 
Screen Failures .......................................................................................................29 
5.5 
Subject Replacement ..............................................................................................29 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 5 - 
6.0 
STUDY INTERVENTION(S) AND CONCOMITANT THERAPY ..........................30 
6.1 
Study Intervention(s) .............................................................................................30 
6.2 
Preparation/Handling/Storage/Accountability .......................................................30 
6.3 
Measures to Minimize Bias ...................................................................................31 
6.4 
Study Intervention Compliance .............................................................................31 
6.5 
Dose Modifications/Interruptions and Retreatment Criteria ..................................31 
6.6 
Access to Study Intervention After End of Study ..................................................31 
6.7 
Treatment of Overdose ..........................................................................................31 
6.8 
Concomitant Medications and Procedures .............................................................32 
6.8.1 
Allowed Concomitant Medications and Procedures .............................32 
6.8.2 
Prohibited Concomitant Medications and Procedures ..........................32 
6.8.3 
Rescue Medication or Supportive Therapy for Adverse Events ...........32 
7.0 
DISCONTINUATION OF STUDY INTERVENTION AND/OR SUBJECT 
DISCONTINUATION OR WITHDRAWAL ...............................................................33 
7.1 
Discontinuation of Study Intervention ...................................................................33 
7.1.1 
Specific Stopping Criteria .....................................................................34 
7.2 
Missed Visits ..........................................................................................................35 
7.3 
Lost to Follow-up ...................................................................................................35 
8.0 
STUDY ASSESSMENTS AND PROCEDURES ..........................................................36 
8.1 
124I-AT-01 Organ Uptake Assessments .................................................................36 
8.1.1 
Medical History and Demographics......................................................36 
8.1.2 
Biomarkers ............................................................................................36 
8.1.3 
Administration of 124I-AT-01 ................................................................36 
8.1.4 
124I-AT-01 PET/CT Imaging .................................................................36 
8.2 
Safety Assessments ................................................................................................36 
8.2.1 
Vital Signs, Body Weight, and Height ..................................................36 
8.2.2 
Clinical Laboratory Testing ..................................................................37 
8.2.3 
Pregnancy Testing .................................................................................37 
8.2.4 
Unscheduled Safety Visits ....................................................................37 
8.3 
Adverse Events, Serious Adverse Events, and Other Safety Reporting ................37 
8.3.1 
Time Period and Frequency for Collecting AE and SAE 
Information ............................................................................................38 
8.3.2 
Method of Detecting AEs and SAEs .....................................................38 
8.3.3 
Follow-up of AEs and SAEs .................................................................38 
8.3.4 
Regulatory Reporting Requirements for SAEs .....................................39 
8.3.5 
Pregnancy ..............................................................................................40 
8.3.6 
Death Events .........................................................................................40 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 6 - 
9.0 
STATISTICAL CONSIDERATIONS ...........................................................................41 
9.1 
Study Hypothesis ...................................................................................................41 
9.2 
Definition of Enrollment ........................................................................................41 
9.3 
Sample Size Determination ....................................................................................41 
9.4 
Analysis Sets ..........................................................................................................41 
9.5 
Statistical Analyses ................................................................................................41 
9.5.1 
General Considerations .........................................................................41 
9.5.2 
Primary Endpoint(s) ..............................................................................42 
9.5.3 
Secondary Endpoint(s) ..........................................................................42 
9.5.4 
Safety Analysis .....................................................................................43 
9.6 
Interim Analyses ....................................................................................................44 
10.0 
APPENDICES WITH SUPPORTING DOCUMENTATION AND 
OPERATIONAL CONSIDERATIONS ........................................................................45 
10.1 
Appendix 1: Regulatory, Ethical, and Study Oversight Considerations ................46 
10.1.1 
Regulatory and Ethical Considerations .................................................46 
10.1.2 
Financial Disclosure ..............................................................................46 
10.1.3 
Informed Consent ..................................................................................47 
10.1.4 
Data Protection ......................................................................................47 
10.1.5 
Data Quality Assurance.........................................................................48 
10.1.6 
Source Documents ................................................................................48 
10.1.7 
Study and Site Start and Closure ...........................................................49 
10.1.8 
Publication Policy .................................................................................50 
10.2 
Appendix 2: Clinical Laboratory Tests ..................................................................51 
10.3 
Appendix 3: AEs and SAEs: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting ...................................................................52 
10.3.1 
Definition of AE ....................................................................................52 
10.3.2 
Definition of SAE .................................................................................53 
10.3.3 
Recording and Follow-Up of AE and/or SAE ......................................54 
10.3.4 
Reporting of SAEs ................................................................................55 
10.4 
Appendix 4: Contraceptive and Barrier Guidance .................................................56 
10.4.1 
Definitions .............................................................................................56 
10.4.2 
Contraception Guidance ........................................................................57 
10.4.3 
Collection of Pregnancy Information ....................................................58 
10.5 
Appendix 5: Protocol Amendment History ...........................................................59 
11.0 
REFERENCES .................................................................................................................60 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 7 - 
LIST OF TABLES 
Table 1: 
Protocol AT01-001: Risk Assessment .......................................................19 
Table 2: 
Protocol AT01-001: Study Intervention ....................................................30 
Table 3: 
Protocol AT01-001: Amendment History .................................................59 
 
 
LIST OF FIGURES 
Figure 1: 
Protocol AT01-001: Schema ......................................................................13 
 
 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 8 - 
LIST OF ABBREVIATIONS AND ACRONYMS 
Term 
Definition 
ADA 
Anti-drug antibodies 
AE 
Adverse event 
AL 
Amyloid light chain 
ATTR 
Amyloid transthyretin 
ALECT2 
Amyloid leukocyte cell-derived chemotaxin-2 
AUC0-t 
Area under the whole blood radioactivity-time curve from time 0 to the last quantifiable 
drug concentration 
BMI 
Body mass index 
BNP 
Brain natriuretic peptide 
BP 
Blood pressure 
CBC 
Complete blood count 
CFR 
Code of Federal Regulations 
CIOMS 
Council for International Organizations of Medical Sciences 
CL 
Apparent systemic clearance 
Cmax 
Maximum observed whole blood radioactivity 
CMR 
Cardiac magnetic resonance 
CNR 
Contrast to noise ratio 
COVID-19 
Coronavirus-19 
CR 
Complete response 
CRF 
Case report form 
CRO 
Contract or Clinical Research Organization 
CT 
Computerized tomography 
CTCAE 
National Cancer Institute Common Terminology Criteria for Adverse Events 
DBP 
Diastolic blood pressure 
ECG 
Electrocardiogram 
ECOG 
Eastern Cooperative Oncology Group 
EDC 
Electronic data collection 
EOS 
End of study 
ET 
Early termination 
FSH 
Follicle stimulating hormone 
GCPs 
Good clinical practices 
HIPPA 
Health Insurance Portability and Accountability Act 
HR 
Heart rate 
HRT 
Hormone replacement therapy 
IB 
Investigator’s Brochure 
ICF 
Informed consent form  
ICH 
International Conference on Harmonisation 
IEC 
Independent Ethics Committee 
IND 
Investigational new drug 
iOSAT 
Potassium iodide (KI) 130 mg  
IRB 
Institutional review board 
IRR 
Infusion-related reaction 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 9 - 
IV 
Intravenous  
λz 
Terminal elimination rate constant 
LAR 
Legally authorized representative 
LDH 
Lactate dehydrogenase 
MedDRA 
Medical Dictionary for Regulatory Activities  
MRI 
Magnetic resonance imaging 
NOAEL 
No-observed-adverse-effect level 
NSAIDs 
Nonsteroidal anti-inflammatory drugs 
NT-proBNP 
N-terminal prohormone of brain natriuretic peptide 
NYHA 
New York Heart Association 
OTC 
Over the counter 
PBS 
Phosphate-buffered saline 
PET 
Positron emission tomography 
PK 
Pharmacokinetics 
PT 
Preferred term 
RBC 
Red blood cell 
ROI 
Region(s) of interest 
SAE 
Serious adverse event 
SAP 
Serum amyloid P-component; statistical analysis plan 
SBP 
Systolic blood pressure 
scFc 
Single chain Fc 
SD 
Standard deviation 
SNR 
Signal to noise ratio 
SoA 
Schedule of Activities 
SOC 
System organ class 
SOP 
Standard operating procedure 
SPECT 
Single-photon emission computerized tomography 
SpO2 
Peripheral blood oxygen saturation level 
SUSAR 
Suspected unexpected serious adverse reaction 
SUV 
Standardized uptake value 
t1/2 
Apparent terminal elimination half-life 
TEAE 
Treatment-emergent adverse event 
Tmax 
Time of maximum observed whole blood radioactivity 
TnI 
Troponin I 
UACR 
Urine albumin creatinine ratio 
UPT 
Urine pregnancy test 
UTARP 
UT Amyloidosis Research Program 
VGPR 
Very good partial response 
Vss 
Apparent volume of distribution at steady state 
WBC 
White blood cell 
WOCBP 
Women of childbearing potential 
 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 10 - 
1.0 
PROTOCOL SUMMARY 
1.1 
Synopsis 
Protocol Number: AT01-001 
Version: 1.0 
For National Authority 
Use Only 
 
IND Number: 132282 
EudraCT Number: N/A 
Sponsor: Attralus, Inc 
Investigational Product: 124I-AT-01 
Title of Study: A Multicenter, Open-label, Single-arm, Phase 2 Study to Evaluate Safety and Organ Uptake 
Quantitation Repeatability of 124I-AT-01 using Positron Emission Tomography/X-ray Computed Tomography 
(PET/CT) in Subjects with Systemic Amyloidosis 
Brief Title: An Open-label, Phase 2 Study to Evaluate Organ Level Uptake Quantitation Repeatability of 
124I-AT-01 in Subjects with Systemic Amyloidosis 
Brief Study Rationale: 
There currently are no approved imaging agents that specifically detect and quantify amyloid deposits in patients. 
As a positron emission tomography (PET)/X-ray computed tomography (CT) imaging agent that binds many forms 
of human and murine amyloid, 124I-AT-01 may fulfill this unmet clinical need by enabling detection of amyloid in 
abdominothoracic organs or tissues of patients with systemic amyloidosis. Thus, this study has been designed to 
assess the repeatability of organ-specific quantitation of radiotracer uptake following PET/CT imaging of AT-01 in 
subjects with amyloid light chain (AL) or amyloid transthyretin (ATTR) systemic amyloidosis. This will help to 
determine whether 124I-AT-01 can be used to monitor disease progression and treatment response in patients with 
systemic amyloidosis. 
Type of Study and Development Phase:  
Human pharmacology, Phase 2 
Countries/Regions:  
United States 
Study Period: Approximately nine (9) months. 
Objectives and Key Endpoints: 
Objectives 
Key Endpoints 
Primary 
To evaluate the repeatability of organ-specific 
quantitation of radiotracer uptake following PET/CT 
imaging of 124I-AT-01 in subjects with AL or ATTR 
systemic amyloidosis. 
• 
Repeatability coefficient (Bland-Altman plots) and 
intraclass correlation coefficient (ICC) associated 
with the quantification of radioactivity associated 
with organ level 124IAT01 uptake measurements. 
Secondary 
• 
To characterize the safety and tolerability of repeat 
doses of 124I-AT-01 administered by IV infusion or 
slow IV bolus.  
 
• 
Incidence of treatment-emergent AEs1 from Day 1 
to EOS. 
• 
Change from Baseline in clinical laboratory values 
at Visits 2 and Safety Follow-up 1 (1-3 days after 
the second administration of 124I-AT-01). 
• 
Change from Baseline in vital signs. 
• 
Change from Baseline in ADA. 
Design/Methodology:  
This is a multicenter, open-label, single arm study in subjects with AL or ATTR systemic amyloidosis. 124I-AT-01 
is the only study intervention; neither reference therapy nor placebo will be administered. 
Number of Subjects Planned: 
Approximately 20 
Gender: 
Male or female 
Age: 
≥18 years of age 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 11 - 
Protocol Number: AT01-001 
Version: 1.0 
For National Authority 
Use Only 
 
IND Number: 132282 
EudraCT Number: N/A 
Sponsor: Attralus, Inc 
Investigational Product: 124I-AT-01 
Title of Study: A Multicenter, Open-label, Single-arm, Phase 2 Study to Evaluate Safety and Organ Uptake 
Quantitation Repeatability of 124I-AT-01 using Positron Emission Tomography/X-ray Computed Tomography 
(PET/CT) in Subjects with Systemic Amyloidosis 
Diagnosis and Key Criteria for Eligibility: 
Eligible subjects will have: 
• 
Has a history of AL or ATTR systemic amyloidosis with at least one organ with clinically demonstrable 
amyloid involvement. 
• 
Able to undergo 2 PET/CT scans as part of the study, including ability to lie supine for up to 1 hour. 
Total Subject Duration: 
Approximately 14 weeks. 
Treatment Duration:  
Approximately 6 weeks 
Investigational Product, Dose, and Route of 
Administration:  
124I-AT-01, 1 mCi ±10% (≤2 mg AT-01) via IV infusion 
or slow IV bolus at 1 mL/5 seconds 
Control, Dose, and Route of Administration: 
N/A 
Organ Uptake Quantitation Evaluation: 
The repeatability of organ-specific quantitation of radiotracer uptake will be assessed using PET/CT imaging of 
124I-AT-01 in subjects with AL or ATTR systemic amyloidosis. 
The signal to noise ratio (SNR) and contrast to noise ratio (CNR) will be plotted against standardized uptake value 
(SUV) based metrics. Repeatability will be assessed using Bland-Altman plots. Intraclass correlation coefficient 
(ICC) and its associated 95% confidence interval will be presented. 
Safety Evaluation: 
All AEs and SAEs will be recorded from the time of informed consent until the final EOS telephone follow-up 
(~Week 10). AEs will be graded using Common Terminology Criteria for Adverse Events (CTCAE) version 5. All 
adverse events occurring during the study will be recorded and classified based on Medical Dictionary for 
Regulatory Activities (MedDRA) terminology. The number and percentage of subjects experiencing TEAEs and 
SAEs will be tabulated for the safety population by system organ class (SOC) and preferred term (PT). TEAEs and 
SAEs will be tabulated by severity and relationship to study medication. Each subject will be counted only once 
within a SOC or a PT by using the AE with the highest severity or greatest relationship, respectively, within each 
category.  
TEAEs or SAEs leading to early discontinuation will be summarized as described above. 
Listings for all reported adverse events, including SAEs, will be provided. In addition, separate listing for SAEs, 
AEs leading to premature withdrawal from the study, and all deaths will be generated. 
Vital signs will include blood pressure (mmHg) and heart rate (beats per minute). Vital signs will be summarized at 
Baseline and for each study visit when vital signs were obtained. Changes from Baseline in vital sign 
measurements will also be summarized. Baseline is defined as the last vital signs obtained prior to the initiation of 
study drug. 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 12 - 
Protocol Number: AT01-001 
Version: 1.0 
For National Authority 
Use Only 
 
IND Number: 132282 
EudraCT Number: N/A 
Sponsor: Attralus, Inc 
Investigational Product: 124I-AT-01 
Title of Study: A Multicenter, Open-label, Single-arm, Phase 2 Study to Evaluate Safety and Organ Uptake 
Quantitation Repeatability of 124I-AT-01 using Positron Emission Tomography/X-ray Computed Tomography 
(PET/CT) in Subjects with Systemic Amyloidosis 
Statistical Considerations: 
This is an open-label, single arm study. In general, for continuous variables, the mean, standard deviation (SD), 
median, and range will be presented. Categorical variables will be summarized by frequency counts and 
percentages. 
Subject disposition will be summarized for all subjects who signed the ICF and will include the number of subjects 
who received study treatment and the number and percentage of subjects who completed or prematurely 
discontinued the study, classified by reasons for premature discontinuation. 
Description of Data Monitoring: 
Study conduct and subject safety will be monitored on an ongoing basis by the study Sponsor. 
Version Date: 08 March 2022 

CONFIDENTIAL 
 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
 
124I-AT-01 
 
- 13 - 
1.2 
Study Schema 
Figure 1: 
Protocol AT01-001: Schema 
 
 
Abbreviations: CT = computerized tomography; IV = intravenous; PET = positron emission tomography; SoA = schedule of activities. 
a. 
Begin oral KI for 3 days, beginning >30 minutes and <24 hr prior to dosing. 
b. 
124I-AT-01 will be administered by IV infusion over 2-5 minutes (subjects enrolled under protocol Version 1.1) or slow IV bolus at 1 mL/5 seconds 
(subjects enrolled under protocol Version 2.0). For all subjects, 124I-AT-01 will be administered by the same route (IV infusion over 2-5 minutes or 
slow IV bolus at 1 mL/5 seconds) at the Week 6 visit as on the Day 1 visit. 
c. 
Subjects will be discontinued if amyloid deposits are not identified in the Day 1 PET/CT scan in at least one of the following organs: heart, liver, spleen 
or kidney. 
d.  Record concomitant medications and conduct biomarker/safety assessments per SoA. 
e. 
Safety follow-ups will be done via telephone call for all subjects.  

CONFIDENTIAL 
 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
 
124I-AT-01 
 
- 14 - 
1.3 
Schedule of Activities 
Visit 
Screening 
Visit 1/ 
Day 1 
Visit 2/ 
Week 6 
Safety  
Follow-up 1 j 
Safety  
Follow-up 2 
(EOS) j 
Early 
Termination 
(ET) k,l 
Window 
Day –30 
to 
Day 1 
± 0 days 
Week 6 to Week 8 
1-3 Days  
After Visit 2 
28 (± 3) Days  
After Visit 2 
<7 days 
from ET 
Decision 
Timing of Activity(ies) 
 
Prior to 
124I-AT-01 
124I-AT-01 
and Scan  
Prior to 
124I-AT-01 
124I-AT-01 
and Scan  
 
 
 
Assessment/Procedures 
 
 
 
 
 
 
 
 
Informed Consent a 
X 
 
 
 
 
 
 
 
Medical history and Demographics 
X 
 
 
 
 
 
 
 
Inclusion and Exclusion criteria 
X 
 
 
 
 
 
 
 
Concomitant Medications 
X 
X 
X 
X 
X 
X 
X 
X 
Oral Potassium Iodide (KI ) b 
 
X 
 
X 
 
 
 
 
124I-AT-01 Administration c 
 
 
X 
 
X 
 
 
 
Biomarker and Safety Assessments 
 
 
 
 
 
 
 
 
Vital Signs (HR and BP) d  
 
X 
X 
X 
X 
 
 
 
Body Weight 
 
X 
 
X 
 
 
 
 
Height 
 
X 
 
 
 
 
 
 
Pregnancy Test (WOCBP) e,f 
X 
 
 
X 
 
 
 
 
PET/CT Scan 
 
 
X 
 
X 
 
 
 
Adverse events g 
X 
X 
X 
X 
X 
X 
X 
X 
Laboratory h,i 
X 
 
 
X 
 
X 
 
 
Biomarkers h,i 
X 
 
 
X 
 
 
 
 
Urine UACR (AL subjects only) i 
X 
 
 
X 
 
 
 
 
Serum ADA i 
X 
 
 
X 
 
 
X 
X 

CONFIDENTIAL 
 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
 
124I-AT-01 
 
- 15 - 
Abbreviations: ADA = anti-drug antibodies; AL = amyloid light chain amyloidosis; BP = blood pressure; CBC = complete blood count; EOS = end of 
study; ET = early termination; HR = heart rate; NT-proBNP = N-terminal prohormone of brain natriuretic peptide; UACR = urine albumin-to-
creatinine ratio; WOCBP = women of childbearing potential. 
a. 
Informed consent, as described in Section 10.1.3. 
b. KI is self-administered by the subject daily for 3 days, beginning >30 minutes and <24 hr prior to dosing, as described in Section 4.1.2. 
c. 
124I-AT-01 will be administered by IV infusion over 2-5 minutes (protocol Version 1.1) or slow IV bolus at 1 mL/5 seconds (protocol 
Version 2.0), as described in Section 4.1.3. For all subjects, 124I-AT-01 will be administered by the same route (IV infusion over 2-5 minutes 
or slow IV bolus at 1 mL/5 seconds) at the Week 6 visit as on the Day 1 visit.  
d. Subjects must remain semi-recumbent for at least 5 minutes prior to blood pressure measurements. Blood pressure and heart rate will be 
measured within an hour prior to dosing and 5-10 minutes after administration of 124I-AT-01. 
e. 
Serum pregnancy test, as indicated in Section 10.2, will be obtained in all women of childbearing potential.  
f. 
Serum pregnancy and all other laboratory samples must be drawn within 7 days prior to administration of 124I-AT-01 in all WOCBP. The 
results of the pregnancy test must be available and be negative prior to 124I-AT-01 administration in all WOCBP.  
g. Adverse events will be monitored from Screening through the EOS Visit. For Safety Follow-up 1 and 2, adverse events and concomitant 
medications can be obtained by phone call. 
h. Clinical laboratory tests and biomarker analysis, as described in Section 10.2. Baseline sample will be collected within 30 days prior to the 
first administration of 124I-AT-01; second sample within 7 days prior to the second administration of 124I-AT-01; third sample at Safety 
Follow-up 1 after the second administration of 124I-AT-01. 
i. 
Urine and blood may be collected locally by visiting nurse/phlebotomist. An additional serum ADA sample will be obtained at Screening for 
subjects who provided consent for the extra ADA sample. 
j. 
Safety follow-ups for concomitant medications and adverse events will be done via telephone call for all subjects. Both Safety Follow-up 1 
and Safety Follow-up 2 activities will be conducted for subjects who discontinue for IRRs at either the first or second administration of 
124I-AT-01.  
k. Blood draw for ADA should be obtained if ET is ≥4 weeks after first administration of 124I-AT-01.  
l. 
Early Termination activities do not apply to subjects discontinued for IRRs. Please follow Safety Follow-up 1 and Safety Follow-up 2 
activities for subjects experiencing IRR with either the first or second administration of 124I-AT-01. 
 

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2.0 
INTRODUCTION 
124I-AT-01 is an amyloid-reactive synthetic peptide (p5+14 or APi1832) radiolabeled with 
iodine-124. There currently are no approved imaging agents that specifically detect and quantify 
amyloid deposits in patients with systemic amyloidosis. As a positron emission tomography 
(PET)/X-ray computed tomography (CT) imaging agent that binds many forms of human and 
murine amyloid, it may fulfill this unmet clinical need by enabling detection of amyloid in 
abdominothoracic organs or tissues of patients with systemic amyloidosis. 
2.1 
Study Rationale 
Systemic amyloidosis is an incurable disease, and about 20% of patients with cardiac or 
advanced kidney involvement experience early deaths (<1 year). Recent progress in the 
treatment of AL amyloidosis with proteasome inhibitors, chemotherapies, and immunotherapies 
that target plasma cells has greatly improved patient prognosis; however, median survival 
remains low at approximately five years (Milani 2018; Palladini 2020). Earlier quantitative 
detection of amyloid in abdominothoracic organs or tissues and assessment of response to 
treatment may improve the prognosis of these patients. However, there currently are no approved 
imaging agents that specifically detect and quantify amyloid deposits in patients. 
As a PET/X-ray CT imaging agent that binds many forms of human and murine amyloid, 
124I-AT-01 may fulfill this unmet clinical need by enabling detection of amyloid in 
abdominothoracic organs or tissues of patients with systemic amyloidosis. Thus, this study has 
been designed to assess the repeatability of organ-specific quantitation of radiotracer uptake 
following PET/CT imaging of AT-01 in subjects with amyloid light chain (AL) or amyloid 
transthyretin (ATTR) systemic amyloidosis. This will help to determine whether AT-01 can be 
used to monitor disease progression and treatment response in patients with systemic 
amyloidosis. 
2.2 
Background 
2.2.1 
Systemic Amyloidosis 
Systemic amyloidosis is a rare protein misfolding and deposition disorder that results in tissue 
amyloid deposits and progressive organ failure. The amyloid deposits are composed of highly 
organized proteinaceous (amyloid) fibrils in association with proteoglycans (hypersulfated 
proteoglycans) and serum derived proteins, serum amyloid P, apolipoprotein E, and 
apolipoprotein A-IV (Muchtar 2021). Amyloid is insoluble and resistant to degradation. The 
resistance to catabolism results in progressive tissue amyloid accumulation and organ 
dysfunction.  
Amyloidosis can be acquired or hereditary and can affect various organs, including the liver, 
spleen, heart, kidneys, peripheral and autonomic nervous systems, gastrointestinal tract, lungs 
and pleura, skin, and soft tissues. Symptoms are usually nonspecific and slowly progressive, 
resulting in delays in diagnosis. Approximately 37 different proteins have been identified as 

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amyloidogenic; at least 17 of them can cause systemic disease, in which the amyloidogenic 
protein is produced in one site (e.g., bone marrow, liver) and is deposited at distant site(s) (e.g., 
heart, kidneys) (Wechalekar 2016).  
The most common forms in the United States (US) are derived from immunoglobulin light 
chains (AL-associated amyloidosis), wild type or mutant transthyretin (wtATTR- and ATTR-
associated amyloid, respectively), leukocyte chemotactic factor 2 (ALECT2), or serum amyloid 
protein A (AA). The incidence of visceral amyloidosis is estimated to be ~8 patients per 
1 million persons per year, with ~4,500 new cases diagnosed every year in the US (Wechalekar 
2016).  
Current Imaging Diagnostics 
Currently, there are no approved methods to document the extent of whole-body amyloid 
deposition or its response to treatment. Thus, there is a critical need to develop a method for 
objective, quantitative visualization of a patient’s amyloid burden.  
Routine anatomic imaging techniques (i.e., CT, magnetic resonance imaging (MRI), ultrasound) 
are not “amyloid-specific”. Furthermore, organ-specific amyloid deposits are rarely visualized 
with current approved nuclear medicine agents. Although European investigators have imaged 
cardiac amyloid distribution in patients with ATTR amyloidosis using planar gamma 
scintigraphy or single-photon emission computerized tomography (SPECT) imaging with 123I-
labeled serum amyloid P-component (SAP) (Hazenberg 2007), 99mTc-aprotinin or 99mTc- 3,3-
diphosphono-1,2 propanodicarboxylic acid (DPD) (Rapezzi 2011), these agents are not approved 
in the US, nor do they detect amyloid in all affected organ sites. The FDA-approved Aβ amyloid 
imaging agents, 18F-Florbetapir (Amyvid), 18F-Flutemetamol (Vizamyl), and 18F-Florbetaben 
(Neuraceq), are only approved for use in very specific populations of suspected Alzheimer’s 
disease patients and have not been shown to be effective at imaging systemic amyloid in organs 
other than the heart in some patients; therefore, they are not suitable for providing non-invasive 
detection of whole-body amyloid load (Dorbala 2014).  
2.2.2 
Description of 124I-AT-01 
124I-AT-01 is an amyloid-reactive synthetic peptide (p5+14 or APi1832) radiolabeled with 124I 
under development for use as a PET/CT imaging agent for the detection of amyloid in 
abdominothoracic organs or tissues of patients with systemic amyloid disease. AT-01 (p5+14 or 
APi1832) is a synthetic, all natural, 45 amino acid peptide (MW = 4763.46 Da) with a net +12 
positive charge that has been shown to specifically bind to amyloid in vitro and in vivo (Wall 
2015).  
Clinical experience with 124I-AT-01 is derived from Study AMY1001 (NCT: NCT03678259), a 
single-center, open-label, exploratory, Phase 1/2 PET/CT imaging study to detect amyloidosis in 
57 subjects, 50 of which had systemic amyloidosis, two (2) of which were asymptomatic ATTR 
carriers, and five (5) of which were healthy volunteers. The primary outcome measure was 

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localization of AT-01 using PET/CT imaging following a single dose via intravenous (IV) 
infusion. Overall, 124I-AT-01 was well tolerated, with no deaths or drug-related serious adverse 
events. The gender-averaged, whole-body, effective dose for 124I-AT-01 in the first three subjects 
was estimated to be 0.24 ± 0.02 mSv/MBq (8.7 mSv/mCi). The whole blood radioactivity half-
life was 21.9 hours. 124I-AT-01 was detected in one or more organs in >90% of patients with 
systemic amyloidosis, including detection in the heart, kidney, liver, and spleen. 124I-AT-01 was 
detected in the liver and kidney in one (1) of five (5) healthy volunteers (both organs were 
identified in the same subject).  
A detailed description of the chemistry, mechanism of action, and nonclinical pharmacology of 
124I-AT-01 is provided in the Investigator’s Brochure (IB).  
2.3 
Benefit/Risk Assessment 
2.3.1 
Potential Benefits 
Based on the initial study of 124I-AT-01 in patients with known systemic amyloidosis, 124I-AT-01 
has been shown to detect amyloid in the heart, kidney, liver, spleen, and pancreas but does not 
bind to these organs in healthy volunteers, indicating that 124I-AT-01 may enable a 
comprehensive assessment of the extent and severity of amyloid deposition in patients with 
systemic amyloidosis. This information may benefit patients by supporting a diagnosis, 
providing information on amyloid organ deposition and severity/extent of disease, and enabling 
monitoring of disease progression and response to therapies.  
2.3.2 
Potential Risks 
Clinically significant potential risks and their mitigation strategies are summarized in Table 1. As 
with all imaging studies involving radiopharmaceuticals, the greatest risks to subjects in this 
study are associated with reactions to the radiotracer and the radiation dose associated with the 
injected radionuclide and external x-rays associated with the CT component of the PET/CT scan. 
These risks are described in Sections 2.3.2.1 and 2.3.2.2. 
 
 

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Table 1: 
Protocol AT01-001: Risk Assessment 
Potential Risk  
Rationale for Risk 
Risk Mitigation Strategy 
Study Intervention(s) 
Infusion-related 
reactions 
As with all protein/peptide 
infusions, there is a potential for an 
infusion-related reaction (IRR) in 
subjects administered 124I-AT-01 
(Doessegger 2015).  
Subjects will be monitored during and following the 
administration of 124I-AT-01 and instructed to 
report any symptoms indicative of an IRR without 
delay (Section 7.1.1.1). 
Immunogenicity 
As with all therapeutic proteins, 
there is a potential for an immune 
response in subjects administered 
124I-AT-01. 
Subjects will be monitored during and following the 
administration of 124I-AT-01and instructed to report 
any symptoms indicative of an immune response 
without delay. 
Radiation exposure 
124I-AT-01 contains radioactive 
iodine.  
Subjects exposed to 124I-AT-01 will be pretreated 
with nonradioactive elemental iodine (127I), 
administered as potassium iodide (KI) at 
recommended doses prior to and for 3 days after 
dosing (Section 2.3.2.1). 
Subjects must agree to prevent pregnancy during 
the study and for at least 90 days afterwards 
(Section 5.1). 
Study Procedures 
Exposure to 
SARS-CoV-2 virus 
International guidelines (e.g., FDA 
Guidance on Conduct of Clinical 
Trials of Medical Products During 
the COVID-19 Public Health 
Emergency) on the conduct of 
clinical trials during the 
COVID-19 pandemic. 
Section 2.3.2.2. 
Abbreviations: CT = computed tomography; ECG = electrocardiogram; FDA = United States Food and Drug 
Administration; PET = positron emission tomography; SpO2 = peripheral blood oxygen saturation. 
 
2.3.2.1 
Risks Associated with Radiation Exposure 
124I is one of several radioactive isotopes of iodine commonly used in human research and 
medical care with a radioactive half-life of 4.2 days. The clinically important risk of exposure to 
124I derives from the potential sequestration of iodine in the thyroid gland and the concentration 
of radiation exposure in that gland. Subjects exposed to 124I as 124I-AT-01 will be treated with 
three daily doses of nonradioactive elemental iodine (127I), administered as potassium iodide 
(KI), at recommended doses beginning >30 minutes and within 24 hours prior to dosing. No 
other clinically important untoward effects of this well-characterized iodine isotope are expected 
at the doses planned in this study.  
From Study AMY1001, the gender-averaged mean whole-body effective radiation dose 
associated with 124I-AT-01 was 0.24 ± 0.02 mSv/MBq. Therefore, the 1 mCi dose used for each 
dose in this study will result in an estimated whole-body effective dose of ~8.7 mSv associated 
with the radiotracer. The whole blood radioactivity half-life was 21.9 hours. Whole blood 

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radioactivity levels were <100 Bq/mL at 48 hrs following a single 1 mCi dose of 124I-AT-01 
(Wall 2021).  
Subjects will also be exposed to radiation from the PET/CT imaging. To reduce radiation dose 
from the PET/CT protocol, image acquisition will use a low-dose CT for attenuation correction. 
Women of childbearing potential must also agree to remain as abstinent (refrain from 
heterosexual intercourse) or use contraceptive methods that result in a failure rate of <1% per 
year during the treatment period and for at least 90 days after the last dose of study intervention. 
Men with female partners of childbearing potential must also agree to remain abstinent or use a 
condom plus an additional contraceptive method that together result in a failure rate of <1% per 
year during the treatment period and for at least 30 days plus 90 days (a spermatogenesis cycle) 
after the last dose of study intervention. Men must also agree to refrain from donating sperm 
during this same time period. Additional details are provided in Section 5.1. 
2.3.2.2 
Risks Associated with Exposure to the Virus SARS-CoV-2 
In consideration of the Coronavirus disease (COVID-19) pandemic caused by the virus 
SARSCoV-2 and the impact it may have on clinical trials, COVID-19 related risks to subjects 
are carefully considered and will be documented on an ongoing basis. Measures that prioritize 
trial subject safety and data integrity have been developed in consideration of local guidelines. 
To minimize risk of exposure associated with trial participation, the Schedule of Activities (SoA) 
(Section 1.3) has been optimized to allow for an adequate follow-up and assessment of the safety 
of 124I-AT-01, without unnecessarily increasing subject exposure.  
As the pandemic situation evolves, the Sponsor will reassess risks, which will be documented as 
part of the Sponsor's trial master file. If escalation of the pandemic during this trial and local 
circumstances lead to a local change in risk assessment, additional measures may be 
implemented. In this case, an Investigator-driven risk assessment will be conducted and 
documented in the Investigator’s site master file and communicated to the Sponsor. 
2.3.3 
Benefit/Risk Conclusion 
The potential benefits of having a comprehensive assessment of the extent of amyloid deposits in 
subjects with systemic amyloidosis have been considered against the risks associated with (i) 
124I-AT-01, (ii) the study procedures, (iii) the method of administration, and (iv) the COVID-19 
pandemic. Subjects in this study will be closely monitored for potential risks. Eligibility criteria 
excludes subjects with higher risk, including those with significant co-morbidity such as Eastern 
Cooperative Oncology Group (ECOG) score of 3 or greater, New York Heart Association 
(NYHA) Class IV heart failure, or other ongoing serious illness. 
For patients with systemic amyloidosis, there is a substantial medical need for amyloid-specific 
imaging diagnostics. Therefore, the Sponsor considers that the value of the information to be 
gained outweighs the risks associated with participating in this study.  
 

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3.0 
OBJECTIVES AND ENDPOINTS 
Objective 
Endpoint 
Primary 
• 
To evaluate the repeatability of organ-specific 
quantitation of radiotracer uptake following 
PET/CT imaging of 124I-AT-01 in subjects with 
AL or ATTR systemic amyloidosis. 
• 
Repeatability coefficient (Bland-Altman plots) and 
ICC associated with the quantification of 
radioactivity associated with organ level 
124I-AT-01 uptake measurements. 
Secondary  
• 
To characterize the safety and tolerability of repeat 
doses of 124I-AT-01 administered by IV infusion or 
slow IV bolus.  
 
• 
Incidence of treatment-emergent AEs1 from Day 1 
to EOS. 
• 
Change from Baseline in clinical laboratory 
values2 at Visits 2 and Safety Follow-up 1 (1-3 
days after the second administration of 
124I-AT-01). 
• 
Change from Baseline in vital signs. 
• 
Change from Baseline in ADA. 
Abbreviations: ADA = anti-drug antibodies; AEs = adverse events; AL = amyloid light chain; ATTR = amyloid 
transthyretin; CT = computerized tomography; EOS = end of study; ICC = intraclass correlation coefficient; 
IV = intravenous; PET = positron emission tomography. 
1. Adverse events will be graded using National Cancer Institute Common Terminology Criteria for Adverse 
Events (CTCAE) version 5. 
2. Clinical laboratory tests are described in Section 10.2 and include hematology and serum chemistry. 
 
 
 

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4.0 
STUDY DESIGN 
4.1 
Overall Design 
This is a multicenter, open-label, single arm study in subjects with AL or ATTR systemic 
amyloidosis. 124I-AT-01 is the only study intervention; neither reference therapy nor placebo will 
be administered.  
This study consists of a screening period of up to 30 days; two, one-day treatment periods (Day 1 
and Week 6); a safety follow-up 1-3 days after the second administration of 124I-AT-01, and a 
final safety follow-up 28 ± 3 days after the second administration of 124I-AT-01. Thus, the total 
subject duration is approximately 14 weeks. 
Adverse events will be monitored and recorded from Screening through the final safety follow-
up/EOS. The schedule for all screening, treatment, and follow-up period activities is provided in 
the SoA (Section 1.3). 
4.1.1 
Screening Period 
The screening period is up to 30 days. Eligibility criteria (Section 5.0) will be confirmed and 
informed consent, as specified in Section 10.1.3, will be obtained. Blood and urine tests as 
outlined in the SoA (Section 1.3) will be obtained during the screening period.  
In WOCBP, serum pregnancy and all other laboratory samples must be drawn within 7 days 
prior to 124I-AT-01 administration. The results of the pregnancy test must be available and be 
negative prior to 124I-AT-01 administration in all WOCBP. 
4.1.2 
Pre-Administration Period 
Subjects will begin therapy with KI 130 mg (e.g., iOSAT, Potassium Iodide Oral Solution USP, 
65 mg/mL) orally once every day for 3 days beginning at least 30 minutes and within 24 hours 
prior to dosing with 124I-AT-01 on the Day 1 and Week 6 visits to block radioactive iodine 
uptake in the thyroid gland.  
4.1.3 
Administration Period 
Administration of 124I-AT-01 and the associated study procedures occur at the Day 1 and Week 6 
(+ 2 week) visits. Administration of 124I-AT-01 and the associated study procedures are described 
in Section 4.1.3.1.  

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4.1.3.1 
Administration of Study Intervention(s) and Associated Procedures 
Day 1 and Week 6 (+ 2 week) Visits 
The schedule for administration of 124I-AT-01 is provided in the SoA (Section 1.3). 
Administration of 124I-AT-01 occurs at the Day 1 and Week 6 to Week 8 visits, as follows: 
Prior to Administration of 124I-AT-01  
1) Clinical laboratory tests and biomarker analysis (including serum pregnancy test in WOCBP) 
will be obtained within 7 days prior to the second administration of 124I-AT-01, as described 
in the SoA (Section 1.3). The results of the pregnancy test must be available and be negative 
prior to 124I-AT-01 administration in all WOCBP. 
2) Instruct subject to take oral KI daily for 3 days, as described in Section 4.1.2. 
3) Record concomitant medications and monitor and record AEs throughout the study visit. 
Administration of 124I-AT-01 
4) Subjects enrolled under protocol Version 2.0 will receive a single dose of 1 mCi (± 10%) 
124I-AT-01 by slow IV bolus at a rate of 1 mL/ 5 seconds. During 124I-AT-01 administration, 
monitor subjects for infusion-related reactions (IRRs), as described in Section 7.1.1. For all 
subjects, 124I-AT-01 will be administered by the same route (IV infusion over 2-5 minutes or 
slow IV bolus at 1 mL/5 seconds) at the Week 6 visit as on the Day 1 visit. 
After Completion of Administration of 124I-AT-01 
5) Blood pressure and heart rate will be measured 5-10 minutes after administration of 
124I-AT-01. 
6) Subjects will undergo a PET/CT scan 5 hours (± 30 minutes) after the start of administration 
of 124I-AT-01 to quantify 124I-AT-01 uptake in organs. 124I-AT-01 whole-body scans will be 
acquired by study-designated PET/CT scanners, as described in Section 8.1.4. 
Subjects will be discontinued if amyloid deposits are not identified in the Day 1 PET/CT 
scan in at least one of the following organs: heart, liver, spleen or kidney (i.e., they will not 
receive a second administration of 124I-AT-01 or undergo a second scan) and will undergo 
early termination (ET) activities, as provided in the SoA (Section 1.3) and as described in 
Section 4.1.5. 
7) Any adverse events will be recorded; patient can be discharged after completing the scan and 
deemed stable by study staff. 
4.1.4 
Follow-up Period  
As shown in the SoA (Section 1.3), the follow-up period is 28 +/- 3 days after the second 
administration of 124I-AT-01. It consists of the following: 

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• Safety Follow-up 1: a safety follow-up phone call 1-3 days after the second 
administration of 124I-AT-01 and a safety laboratory draw 1-3 days after the second 
administration of 124I-AT-01; and  
• Safety Follow-up 2: a final safety follow-up phone call 28 ± 3 days after the second 
administration of 124IAT-01 for collection of AEs and concomitant medication, and a 
blood draw 28 ± 3 days after the second administration of 124I-AT-01 for anti-drug 
antibodies (ADA).  
Blood draws for laboratory and ADA will be collected locally by visiting nurse/phlebotomist. 
Both Safety Follow-up 1 and Safety Follow-up 2 activities will be conducted for subjects who 
discontinue for IRRs, as described in Section 7.1.1.1, at either the first or second administration 
of 124I-AT-01. 
4.1.5 
Early Termination Visit 
Subjects that are withdrawn or discontinued per the criteria provided in Section 7.1 will undergo 
the ET activities provided in the SoA (Section 1.3) within 7 days from the early termination 
decision. Blood draw for ADA should be obtained if ET is ≥4 weeks after the first administration 
of 124I-AT-01 of 124I-AT-01 and will be collected locally by visiting nurse/phlebotomist.  
ET activities do not apply to subjects discontinued for IRRs. Safety Follow-up 1 and Safety 
Follow-up 2 activities (Section 4.1.4) will be conducted for subjects who discontinue for IRRs at 
either the first or second administration of 124I-AT-01.  
4.2 
Scientific Rationale for Study Design 
This is a multicenter, open-label, single arm study in subjects with systemic amyloidosis to 
evaluate the repeatability of organ-specific quantitation of radiotracer uptake following PET/CT 
imaging of 124I-AT-01 in subjects with AL or ATTR systemic amyloidosis.  
4.2.1 
Choice of Population 
124I-AT-01 is designed to selectively bind to amyloid; therefore, the objectives of this study can 
only be met by including subjects with documented systemic amyloidosis and known visceral 
organ amyloid deposits. Subjects with AL or ATTR systemic amyloidosis were selected for this 
study because these are the most common forms of systemic amyloidosis at the study sites. 
4.2.2 
Choice of Primary Endpoint and Analysis 
The primary endpoint is to evaluate the repeatability of organ-specific quantitation of radiotracer 
uptake using PET/CT imaging of 124I-AT-01 in subjects with AL or ATTR systemic amyloidosis. 
To evaluate organ uptake of 124I-AT-01 using PET/CT as a quantitative imaging biomarker, 
quantitative readings must be repeatable and reproducible (Meikle 2021).  

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4.2.3 
Choice of Duration of Treatment and Follow-up 
124I-AT-01 is eliminated by radioactive decay (half-life ~ 4.2 days), cell-mediated protein 
clearance, and catabolism. Ten radioactive half-lives will assure complete clearance of 
radioactivity after the first PET/CT imaging visit and before the second PET/CT imaging visit. 
Ten half-lives is ~ 6 weeks. Thus, the two doses of 124I-AT-01 will be separated by at least 6 
weeks. A final safety follow-up 28 days after the second dose of 124I-AT-01 represents more than 
five half-lives, a routinely recommended post-treatment safety assessment period (CIOMS 
2005). 
4.3 
Justification for Dose(s) and Posology 
In the AMY1001 trial, doses of 0.3, 1, and 2 mCi of 124I-AT-01 were evaluated. All but the first 
five subjects in the AMY1001 study received a 2 mCi dose of 124I-AT-01. However, review of 
the experience in the AMY1001 study indicated that the 1mCi dose of 124I-AT-01provides 
sufficient exposure to characterize amyloid deposits. The 1mCi dose is being used in a study 
conducted under a separate IND at Brigham and Women’s Hospital and will be used in this 
study. This dose is associated with ≤2 mg of p5+14 peptide (AT-01). The nonclinical safety of 
AT-01 was evaluated in a single IV dose toxicity study in Sprague Dawley rats. A maximum 
tolerated dose was not determined, and the no-observed-adverse-effect-level (NOAEL) was 
considered to be at least 17.6 mg/kg (105.8 mg/m2) for a single IV dose administration in rats. 
This dose is approximately 100-fold greater than the maximum 2 mg dose (~0.03 mg/kg) 
intended for administration to patients. Additional details are provided in the IB. 
4.4 
End of Treatment Definition 
Subjects may withdraw from this study at any time and for any reason and shall not be subject to 
prejudice to further medical care by the Investigator or study site. Reasons for end of treatment 
and/or ET are provided in Section 7.0. 
4.5 
End of Study Definitions 
If, during the study, it becomes evident to the Sponsor that the study should be stopped 
prematurely, the study will be terminated and appropriate notification will be given to the 
Investigator(s) and IRB(s), as applicable. The Sponsor, or designee, will instruct the 
Investigators to stop dispensing study materials/treatment and to arrange for study closeout at 
each site. 
The end of the study is defined as whichever of the following comes first: 
• The last safety follow-up of the last enrolled subject; or  
• The Sponsor’s decision to terminate the study. 
The Sponsor, or designee, will notify the Investigator when to contact the IRB to inform them 
that the study is complete. 

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4.6 
Subject Completion Definition 
Subjects have completed the study when they have received both administrations of 124I-AT-01 
and both PET/CT scans and have completed the EOS activities, including the final safety follow-
up telephone call and blood draw. Subjects who require further follow-up for an adverse event 
(AE) will be followed according to Section 8.3. 

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5.0 
STUDY POPULATION 
Subjects will be enrolled and will receive study treatment only if they meet all inclusion criteria 
(Section 5.1) and none of the exclusion criteria (Section 5.2). 
5.1 
Inclusion Criteria 
Subjects are eligible to be included in the study only if all the following criteria apply: 
1) Understands the study procedures and is capable of giving signed informed consent, as 
described in Appendix 1, which includes compliance with the requirements and restrictions 
listed in the informed consent form (ICF) and in this protocol. 
2) Male or female ≥18 years of age. 
3) Has a history of AL or ATTR systemic amyloidosis with at least one organ with clinically 
demonstrable amyloid involvement defined by: 
a) For AL systemic amyloidosis: 
i) Positive tissue (e.g., fat-pad, gastrointestinal tract, etc.) biopsy for AL amyloid, and 
ii) Achieved a hematologic very good partial response (VGPR) or complete response 
(CR) based on their most recent assessment and within 12 months of screening, and 
iii) At least one of the following: 
(1) Cardiac, renal, or liver biopsy positive for amyloid, or 
(2) NT-proBNP >650 pg/mL, or 
(3) Left ventricle septal wall thickness >12 mm by echocardiogram or cardiac 
magnetic resonance (CMR), or 
(4) 24-hour urine protein >500 mg, or  
(5) Urine albumin-to-creatinine ratio (UACR) >300 mg/g. 
b) For ATTR (wild type or variant) systemic amyloidosis: 
i) Positive cardiac biopsy for ATTR amyloid, or 
ii) At least two of the following:  
(1) Positive extracardiac tissue (e.g., fat-pad, GI tract, etc.) biopsy for ATTR amyloid 
or positive transthyretin gene mutation associated with amyloid (obtained at any 
time), or  
(2) Left ventricle septal wall thickness >12 mm by echocardiogram or CMR (in the 
absence of alternative causes), or 
(3) Pyrophosphate (PYP) scintigraphy with myocardial uptake ≥grade 2 (or 
heart/contralateral chest ratio >1.5) using SPECT/CT scan if AL amyloidosis is 
excluded.  

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4) Able to undergo two PET/CT scans as part of the study, including ability to lie supine for up 
to 1 hour. 
5) For women of childbearing potential: agreement to remain abstinent (refrain from 
heterosexual intercourse) or use contraceptive methods that result in a failure rate of <1% per 
year during the treatment period and for at least 90 days after the last dose of 124I-AT-01.  
a) A woman is considered of childbearing potential if she is postmenarchal, has not reached 
a postmenopausal state (≥12 months of amenorrhea with no identified cause other than 
menopause), and has not undergone surgical sterilization (removal of ovaries and/or 
uterus). The definition of childbearing potential may be adapted for alignment with local 
guidelines or requirements. 
b) Examples of contraceptive methods with a failure rate of <1% per year include bilateral 
tubal ligation, male sterilization, established, proper use of hormonal contraceptives that 
inhibit ovulation, hormone-releasing intrauterine devices, and copper intrauterine 
devices. 
c) Contraception methods that do not result in a failure rate of <1% per year such as cap, 
diaphragm, or sponge with spermicide, or male or female condom with or without 
spermicide, are not acceptable. 
d) The reliability of sexual abstinence should be evaluated in relation to the duration of the 
clinical trial and the preferred and usual lifestyle of the subject. Periodic abstinence (e.g., 
calendar, ovulation, symptothermal, or post-ovulation methods) and withdrawal are not 
acceptable methods of contraception. 
6) For men: agreement to remain abstinent or use contraceptive measures and agreement to 
refrain from donating sperm, as defined below: 
a) With female partners of childbearing potential, men must remain abstinent or use a 
condom plus an additional contraceptive method that together result in a failure rate of 
<1% per year during the treatment period and for at least 120 days (a spermatogenesis 
cycle) after the last dose of study intervention. Men must refrain from donating sperm 
during this same time period. 
5.2 
Exclusion Criteria 
Subjects are excluded from the study if any of the following criteria apply: 
1) Is pregnant or breast-feeding. 
2) Is mentally or legally incapacitated, has significant emotional problems at the time of the 
study, or has a history of psychosis. 
3) Has received in the last 6 months or are currently receiving treatment with anti-amyloid 
monoclonal antibody therapy (i.e., CAEL101, NEOD001, PRX-004, or NI006) or are 
expected to begin treatment prior to completing this study. 

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4) Has received heparin or heparin analogs (e.g., enoxaparin, dalteparin, fondaparinux) within 7 
days of Day 1 (first administration of 124I-AT-01). 
5) Has a significant co-morbidity (e.g., ECOG score of 3 or greater), NYHA Class IV heart 
failure, uncontrolled infection, or other ongoing serious illness. 
6) Has a known allergy to potassium iodine treatment. 
7) Has end-stage renal disease and is receiving hemodialysis or peritoneal dialysis. 
8) Has severe claustrophobia that would prevent completion of the PET/CT imaging protocol. 
9) Has received an investigational agent within five half-lives of the agent or 30 days, 
whichever is longer, prior to Screening.  
10) Has any illness that, in the opinion of the Investigator, might confound the results of the 
study or pose additional risk to the subject. 
5.3 
Lifestyle Considerations 
Specific lifestyle considerations are not required.  
5.4 
Screen Failures 
Subjects that fail screening will be recorded as screen failures in the source documentation.  
Subjects that terminate the study early may be replaced, as described in Section 5.5. 
5.5 
Subject Replacement 
Subjects that are withdrawn (except for an AE) or are lost to follow-up during the study may be 
replaced to ensure an appropriate number of subjects complete the study. The decision to replace 
a subject will be made in agreement between the Sponsor and Investigator. Subjects who do not 
receive a second dose of 124I-AT-01 or have a PET/CT scan following the second dose of 
124I-AT-01 will be replaced. 

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6.0 
STUDY INTERVENTION(S) AND CONCOMITANT THERAPY 
6.1 
Study Intervention(s) 
The study intervention is described in Table 2. For complete information regarding the 
administration of study intervention, refer to the Study Manual.  
Table 2: 
Protocol AT01-001: Study Intervention 
Arm Name 
124I-AT-01 
Intervention Name 
124I-AT-01 
Type  
Radiopharmaceutical 
Dosage Form 
Solution for Injection 
Unit Dose Strength(s) 
0.004-0.037 GBq (0.1-1 mCi)/mL; NMT 2 mg AT-01 
Dosage Level(s) 
1 mCi (± 10%) 124I-AT-01 
Half-life is 4.2 days. Calculate the correct dosage from date and time 
of calibration. 
Route of Administration 
IV infusion (2-5 minutes) or slow IV bolus at 1 mL/5 seconds. 
Additional details are provided in the Pharmacy Manual. 
Use 
Experimental 
IMP or NIMP 
IMP 
Sourcing 
124I-AT-01 will be manufactured for each subject and will be supplied 
to the investigative site by the Sponsor. 
Storage 
Store upright in a shielded container at room temperature. The 
expiration time of 124I-AT-01 is 96 hours after its end of synthesis. 
Packaging and Labeling 
Multidose 10 mL vial. 
Contains: [124I]p5+14, 1.3-1.8 mg in phosphate-buffered saline (PBS) 
for injection.  
>90% radiochemical purity (remainder iodide), >99% radionuclidic 
purity.  
The product is sterile and non-pyrogenic. May be diluted with sodium 
chloride for injection (USP). 
DO NOT USE if cloudy or contains particulate matter. 
Handling 
Aseptically withdraw and handle doses. The empty syringe and IV 
administration sets shall be disposed of in accordance with 
appropriate local radioactive waste management guidance.  
Abbreviations: IMP = investigational medicinal product; IV = intravenous; NIMP = non-investigational medicinal 
product; NMT = no more than. 
 
6.2 
Preparation/Handling/Storage/Accountability 
124I-AT-01 will be manufactured by 3D Bioimaging, LLC (Little Rock, AR) and will be supplied 
to the investigative site in a multidose 10 mL vial. It will be delivered in a container with 
appropriate radioactive shielding. Any damage to the vial should be reported immediately to both 

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the Sponsor and 3D Imaging using the contact information provided in the Pharmacy Manual. 
Store upright in a shielded container.  
Aseptically withdraw and handle doses. The half-life of 124I is 4.2 days. Calculate the correct 
dosage from date and time of calibration. The expiration time of 124I-AT-01 is 96 hours after its 
preparation. 
The empty syringe and IV administration sets will be disposed of in accordance with appropriate 
local radioactive waste management guidance. 
The Investigator (or designee) will be responsible for keeping current and accurate records of the 
dose of 124I-AT-01 dispensed and its disposition. 
6.3 
Measures to Minimize Bias 
Because this study is an exploratory, single arm, open-label human pharmacology study, 
measures to minimize bias are not applicable. 
6.4 
Study Intervention Compliance 
Only subjects enrolled in this study may receive treatment with 124I-AT-01. All study drug 
during the study will be administered by qualified clinical site staff. The date and time for each 
dose will be recorded in the CRFs. The date of and reason for any deviations in protocol-
specified dosing will be documented in the case report forms. 
6.5 
Dose Modifications/Interruptions and Retreatment Criteria 
Subjects may only receive the specified dose of 124I-AT-01. Modifications of the dosage and 
retreatment are not allowed, except as provided in Section 7.1.1.  
6.6 
Access to Study Intervention After End of Study 
Administration of 124I-AT-01 under this protocol will be completed at Visit 2 (Week 6 to 
Week 8). No further treatment with 124I-AT-01 will occur under this protocol, and 124I-AT-01 will 
not be made available to subjects by the Sponsor after completion of the study. 
6.7 
Treatment of Overdose 
For this study, any dose of 124I-AT-01 greater than 1.1 mCi or >2 mg AT-01 is considered 
overdose. There are no specific treatments for overdose. In the event of an accidental overdose, 
the Investigator should do the following: 
• Contact the Sponsor/Medical Monitor immediately; 
• In consultation with the Sponsor/Medical Monitor, determine, whether additional steps 
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• Closely monitor the subject for any AEs or serious AEs (SAEs); and 
• Document the quantity of the excess dose. 
 
6.8 
Concomitant Medications and Procedures 
A concomitant medication is any drug or substance administered between signing the ICF and 
the EOS Visit. A concomitant procedure is any therapeutic intervention (e.g., surgery/biopsy) 
performed between obtaining informed consent and the EOS Visit that is not otherwise specified 
in the protocol. 
6.8.1 
Allowed Concomitant Medications and Procedures 
There are no restrictions on concomitant medications, unless specified as prohibited 
(Section 6.8.2). 
6.8.2 
Prohibited Concomitant Medications and Procedures 
Concurrent enrollment in any other drug, biologic, or device clinical study; or treatment with an 
unapproved investigational drug under development is prohibited. 
If a participant is scheduled for an elective procedure during the study, they should postpone the 
procedure until their participation in the study is complete. 
Heparin or heparin analogs are prohibited within 7 days of a planned administration of 124I-AT-
01. Additional details are provided in Section 7.1.1.2. 
6.8.3 
Rescue Medication or Supportive Therapy for Adverse Events 
Not applicable. 

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7.0 
DISCONTINUATION OF STUDY INTERVENTION AND/OR SUBJECT 
DISCONTINUATION OR WITHDRAWAL 
7.1 
Discontinuation of Study Intervention 
All subjects are free to withdraw from participating in this study at any time for any reason, 
specified or unspecified, and without prejudice. No constraints will be placed on ordinary subject 
management.  
Subjects will be withdrawn for any of the following reasons: 
• The subject withdraws consent. 
• The subject does not have amyloid deposits in the heart, liver, spleen or kidney on the 
Day 1 PET/CT scan, as described in Section 8.1.4. 
• The subject begins treatment with heparin or a heparin analog within 7 days of a planned 
administration of 124I-AT-01, as described in Section 7.1.1.2. 
• The subject experiences an intolerable AE or serious AE (SAE). 
• The subject enrolls into another clinical study in which an investigational treatment or 
approved therapy for investigational use is administered. 
• The subject becomes pregnant. Study treatment must be discontinued immediately. 
Report the pregnancy according to the instructions in Section 8.3.5. 
• The subject is unwilling or unable to comply with the protocol. 
• At the discretion of the Investigator or Sponsor.  
• Investigator decision that it is not in the best medical interest of the subject to continue 
participation in the investigation. 
• The Sponsor prematurely terminates the study. 
Prior to discontinuing a subject, every effort should be made to obtain as much follow-up data as 
possible. Withdrawn or discontinued subjects will undergo ET activities per the SoA 
(Section 1.3). Subject withdrawals will be documented clearly on the source documents and 
applicable case report forms (CRFs). Subject withdrawals will be documented clearly on the 
source documents and applicable CRFs.  
Discontinued subjects will be assessed for adverse events via a telephone call 24-48 hours after 
decision to discontinue. 
Notification of subject withdrawals will be made to the Sponsor, or designee. 

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7.1.1 
Specific Stopping Criteria  
7.1.1.1 
Infusion-related Reactions  
Infusion-related reactions (IRRs) can be any signs or symptoms experienced by subjects during 
the infusion of pharmacologic or biologic agents or any event occurring on the first day of the 
infusion (Doessegger 2015). IRRs have been reported, among other terms, as anaphylaxis, 
anaphylactoid reactions, cytokine release syndrome, hypersensitivity reaction, etc. Symptoms 
suggestive of an IRR include but not limited to the following: tachypnea with respiratory 
distress, new onset rash or pruritus, chills, stridor, wheezing, swollen or itchy lips or tongue, 
onset of abdominal cramping, or hypotension. 
Treatment-emergent adverse events starting on the day of 124I-AT-01 administration will be 
summarized to evaluate potential infusion-related reactions.  
Subjects will be monitored for IRRs and managed as follows:  
• During administration of 124I-AT-01: if an IRR occurs during administration, the 
administration will be immediately discontinued and the subject will be treated for their 
symptoms and discontinued from the study. Activities for Safety Follow-up 1 (1-3 days 
after the second administration) and Safety Follow-up 2/EOS (28 (± 3) days after the 
second administration) will be conducted, per the SoA (Section 1.3).  
• After administration of 124I-AT-01: if an IRR occurs in a subject after completion of the 
administration, the subject will be treated for their symptoms, managed in accordance 
with standard of care, and the IRR will be recorded as an AE. If the symptoms respond 
promptly to minimal intervention (e.g., responds promptly to symptomatic treatment with 
antihistamines, acetaminophen, or nonsteroidal anti-inflammatory drugs (NSAIDs)) then, 
at the discretion of the Investigator, the subject may continue in the study. If the 
symptoms are prolonged (e.g., not rapidly responsive to symptomatic medication), 
require IV fluids or treatments, or require hospitalization, the subject will be discontinued 
from the study. Activities for Safety Follow-up 1 (1-3 days after the second 
administration) and Safety Follow-up 2/EOS (28 (± 3) days after the second 
administration) will be conducted, per the SoA (Section 1.3).  
7.1.1.2 
Heparin or Heparin Analogs 
Concomitant use of heparin or heparin analogs within 7 days of a planned administration of 124I-
AT-01 is prohibited (Section 6.8.2), as follows:  
• Subjects who have received heparin or a heparin analog within 7 days of Day 1 (first 
administration of 124I-AT-01) are excluded from the study (Section 5.2). 

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• If a subject receives heparin or a heparin analog within 7 days of the planned Week 6 
administration of 124I-AT-01 and PET/CT scan, they will be discontinued from the study 
(i.e., they will not receive a second administration of 124I-AT-01 or undergo a second 
scan) and will undergo ET activities, as provided in the SoA (Section 1.3) and as 
described in Section 4.1.5. 
If a subject begins treatment with heparin or a heparin analog after the Week 6 administration of 
124I-AT-01 and PET/CT scan, they may continue the study, as described in the SoA 
(Section 1.3).  
7.2 
Missed Visits  
If a subject misses any of the scheduled visits, the visit is considered missed and recorded as 
such in the source documents and CRFs.  
7.3 
Lost to Follow-up 
Subjects who do not return for a scheduled visit (missed visit) and cannot be contacted, may be 
considered lost to follow-up. The site will attempt to contact the subject through a minimum of 
two telephone calls. If the subject still cannot be contacted, the site will send a certified letter to 
the last known address of the subject. If no contact is made by the subject, the site will consider 
the subject lost to follow-up. All follow-up attempts will be documented and kept with the 
subject’s source documentation, and the applicable CRFs will be completed. 

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8.0 
STUDY ASSESSMENTS AND PROCEDURES 
8.1 
124I-AT-01 Organ Uptake Assessments 
8.1.1 
Medical History and Demographics 
Medical history includes clinically significant diseases, organ or stem cell transplants, and 
reproductive status. All prescription medications used by the subject regularly or within 30 days 
preceding Day -1 must be recorded. Prior or concurrent treatment regimens for systemic 
amyloidosis should be recorded. Demographic data will include age, sex, body mass index 
(BMI), amyloid subtype, time since diagnosis of systemic amyloidosis, and ethnic origin (also 
referred to as self-reported race and ethnicity in some regions of the world). 
8.1.2 
Biomarkers 
Biomarkers including NT-proBNP, brain natriuretic peptide (BNP), serum free light chains (only 
subjects with AL amyloidosis), and UACR (only subjects with AL amyloidosis) will be obtained 
at Screening and Week 6 (Visit 2), as specified in the SoA (Section 1.3). 
8.1.3 
Administration of 124I-AT-01 
124I-AT-01 will be administered while the subject is at the clinical site. 124I-AT-01 will be 
administered as described in Section 4.1.3. 
During 124I-AT-01 administration, monitor subjects for IRRs, as described in Section 7.1.1.  
8.1.4 
124I-AT-01 PET/CT Imaging  
Planned time points for all PET/CT imaging are provided in the SoA (Section 1.3). Subjects will 
undergo a PET/CT scan 5 hours (± 30 minutes) after the start of administration of 124I-AT-01 to 
quantify 124I-AT-01 uptake in organs. 124I-AT-01 whole-body scans will be acquired using study-
designated PET/CT scanners (see Imaging Manual for further information).  
Subjects without evidence of amyloid in at least one of the following organs on the Day 1 scan: 
heart, liver, kidneys, or spleen, will be discontinued from the study (i.e., not receive a second 
administration of 124I-AT-01 or undergo a second scan) and will undergo ET activities provided 
in the SoA (Section 1.3) and as described in Section 4.1.5. 
8.2 
Safety Assessments 
Planned time points for all safety assessments are provided in the SoA (Section 1.3). 
8.2.1 
Vital Signs, Body Weight, and Height 
Planned time points for vital signs, body weight, and height are provided in the SoA 
(Section 1.3). Additional vital signs may be taken at any other times, if deemed necessary. 

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Heart rate and blood pressure measurements will be performed with subjects in a supine position 
for at least 5 minutes, except when they are seated or semi-reclined because of study procedures 
and/or AEs (e.g., nausea, dizziness), or if deemed necessary by the Investigator or designee. 
Blood pressure measurements should be measured on the same arm throughout the study. 
8.2.2 
Clinical Laboratory Testing 
A list of clinical laboratory tests to be performed is provided in Appendix 2.  
The clinical safety laboratory tests will be performed at a central laboratory. Samples for 
complete blood count (CBC) and chemistry should be obtained and analyzed based on central lab 
requirements. Laboratory safety tests may be performed at various unscheduled time points, if 
deemed necessary by the Investigator or designee. 
8.2.3 
Pregnancy Testing 
Subject samples for pregnancy testing will be acquired pre-administration at the Screening and 
Week 6 visits in women of childbearing potential, as specified in the SoA (Section 1.3). All 
women of childbearing potential (defined in Appendix 4) must have a negative pregnancy test 
prior to administration of 124I-AT-01 at the Day 1 and Week 6 visits to participate in the study. 
Samples for serum pregnancy tests must be drawn within 7 days prior to 124I-AT-01 
administration for all women of childbearing potential. 
Prior to enrollment in the study, female subjects of childbearing potential and male subjects must 
be advised of the importance of avoiding pregnancy or partner pregnancy, respectively, during 
the trial, and the potential risks associated with an unintentional pregnancy. Contraceptive and 
barrier guidance and collection of pregnancy information is described in Appendix 4. 
8.2.4 
Unscheduled Safety Visits 
Additional visits may be scheduled, as necessary, to ensure the safety and well-being of subjects. 
All additional exams should be fully documented in the source documents and on Unscheduled 
Visit CRFs, as appropriate. 
8.3 
Adverse Events, Serious Adverse Events, and Other Safety Reporting 
The definitions of AEs and SAEs; the methods of recording, evaluating, and assessing causality 
of AEs and SAEs; and the procedures for completing and transmitting SAE reports are provided 
in Appendix 3.  
Adverse events will be graded for seriousness, severity, and relationship to study drug treatment. 
After obtaining informed consent, each subject must be given the names and telephone numbers 
of study site staff for reporting AEs and medical emergencies. 

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8.3.1 
Time Period and Frequency for Collecting AE and SAE Information 
All AEs and SAEs will be recorded from the time of informed consent until the final EOS 
telephone follow-up (~Week 10).  
Throughout the study, every effort must be made to remain alert to possible AEs. If an AE 
occurs, the first concern should be for the safety of the subject. If necessary, appropriate medical 
intervention should be provided. 
8.3.2 
Method of Detecting AEs and SAEs 
Adverse events may be spontaneously reported by the subject, obtained through non-leading 
questioning, or noted during examination of a subject. 
When recording an AE, a diagnosis is always preferable; however, in the absence of a diagnosis, 
the Investigator should record each sign and symptom as an individual AE.  
Medical or surgical procedures (e.g., cardiac ablation) should not be recorded as AEs. Rather, the 
condition for which the procedure was performed should be recorded. 
Adverse events will be recorded from the time informed consent (Section 10.1.3) is obtained 
through the end of the study. The data will be recorded on the appropriate CRF, regardless of 
whether they are thought to be associated with the study or treatment with study drug. 
Investigators are not obligated to actively seek SAE information from subjects that complete the 
study but are encouraged to notify the Sponsor or designee of any SAE occurring at any time 
after a subject has discontinued or completed the study that they judge may be reasonably related 
to treatment with study drug or study participation. 
8.3.3 
Follow-up of AEs and SAEs 
All related SAEs must be followed until resolution, until the condition stabilizes, until the event 
is otherwise explained, or the subject is lost to follow-up. The Investigator is responsible for 
ensuring that follow-up includes any supplemental investigations as may be indicated to 
elucidate as completely as practical the nature and/or causality of the AE or SAE. This may 
include additional laboratory tests or investigations, histopathological examinations, relevant 
hospital records (i.e., discharge summary), or consultation with other health care professionals. 
The Investigator must ensure that all subject identifiers are redacted from supportive 
documentation prior to submission. 
The Sponsor or designee may request that the Investigator perform or arrange for the conduct of 
supplemental measurements and/or evaluations. If a subject dies during participation in the study 
or during a recognized follow-up period, the Sponsor or designee should be provided with a copy 
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New or updated information obtained during SAE follow-up should be recorded in the 
original/existing form(s); updates should be made to the relevant data in the EDC. If EDC is not 
available, then new or updated information should be recorded on a new paper SAE form; the 
original or prior paper SAE forms must not be re-used or altered. By signing the SAE form, the 
Investigator or designee attests to the accuracy and completeness of the data and that he/she has 
reviewed the report being submitted and approves it. If a paper form is used, the same 
information is to be captured in the EDC when EDC becomes available. 
8.3.4 
Regulatory Reporting Requirements for SAEs 
Any SAE experienced by the subject between the time of the signing of the ICF and up to the 
EOS telephone call (approximately Week 10) must be recorded on an SAE form, regardless of 
the severity of the event or its relationship to treatment with study drug. Once the Investigator 
determines that the event meets the protocol definition of an SAE, the SAE must be reported to 
the Sponsor, or designee, within 24 hours.  
Prompt notification of an SAE by the Investigator to the Sponsor is essential to meet the legal 
obligations and ethical responsibilities regarding the safety of subjects and the safety of a study 
intervention under clinical investigation. 
Reporting of a SAE requires the following: 
• Completion of the SAE Report Form details in the EDC, or if the EDC is not available, 
transmission of the paper SAE Report Form to the Sponsor or designee, via email as 
noted in the Study Manual. The SAE event is to be reported within 24 hours of the 
Investigator’s knowledge of the event. If paper submission is used, the same information 
is to be entered into the EDC when EDC becomes available.  
• Reporting of additional, follow-up information for previously reported SAEs should 
follow the same reporting timeframe and procedures as initial reports. New or updated 
information should be made to the relevant data in the EDC. If EDC is not available, new 
or updated information should be recorded on a new paper SAE form; the original or 
prior paper SAE forms must not be re-used or altered.  
• Accompanying documentation, such as laboratory data, concomitant medication records, 
hospital records etc., should be redacted and transmitted to the Sponsor or designee as 
outlined in the Study Manual. In addition, the corresponding AE in the AE CRF (as 
applicable) should be updated to ensure all data points documented in the AE CRF are 
aligned with the matching data points on the SAE Report Form. 
The Sponsor has a legal responsibility to notify health authorities about the safety of a study 
intervention under clinical investigation. The Sponsor will comply with country-specific 
regulatory requirements relating to safety reporting to the local regulatory authority, Institutional 
Review Boards (IRB)/Independent Ethics Committees (IEC), and Investigators. 

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An Investigator who receives an Investigator Safety Report describing an SAE or other specific 
safety information (e.g., summary or listing of SAEs) from the Sponsor will review and then file 
it along with the IB and will notify the IRB/IEC, as appropriate according to local requirements. 
Investigator Safety Reports must be prepared for suspected unexpected serious adverse reactions 
(SUSAR) according to local regulatory requirements and Sponsor policy and forwarded to 
Investigators as necessary. 
8.3.5 
Pregnancy 
The Investigator must report a pregnancy occurring in a female subject to the Sponsor or 
designee within 24 hours of the study site staff becoming aware of the pregnancy. In addition, if 
a female subject becomes pregnant within 12 weeks after last dose of study drug, the pregnancy 
must also be reported within 24 hours of the study site becoming aware of the pregnancy. The 
Investigator or study site staff must also follow the pregnancy until the outcome is known and 
submit the outcome as follow-up within 24 hours of notification of outcome. Follow-up 
Pregnancy Forms may be submitted as required as additional information is obtained. Although 
pregnancy occurring in a clinical study is not considered to be an AE or SAE, any pregnancy 
complication or elective termination of a pregnancy, for medical reasons, will be recorded as an 
AE or SAE and followed as such. Pregnancies in partners of male study subjects will similarly 
be monitored for the full duration of the pregnancy and/or followed through a definitive outcome 
(i.e., birth, or spontaneous or elective abortion). Pregnancy reporting must be submitted via email 
as noted in the Study Manual. 
8.3.6 
Death Events 
Death is an outcome of an event. The event that resulted in death should be recorded on the 
appropriate CRF. All causes of death must be reported as SAEs within 24 hours of the site 
becoming aware of the event. The Investigator should make every effort to obtain and send death 
certificates and autopsy reports to the Sponsor or designee. If cause of death is not available 
within the 24-hour reporting period, “death” must be reported as the SAE term to meet timelines, 
and the cause of death must be actively queried and submitted as a follow-up report. 

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9.0 
STATISTICAL CONSIDERATIONS 
9.1 
Study Hypothesis 
Not applicable. 
9.2 
Definition of Enrollment 
“Enrolled” means a subject, or their legally authorized representative, has provided agreement to 
participate in this clinical study following completion of the screening and informed consent 
processes. Potential subjects who are screened for the purpose of determining eligibility for the 
study, but who do not participate in the study, are considered screening failures and are not 
considered enrolled. 
9.3 
Sample Size Determination 
A formal sample size calculation is not provided for this study. The sample size of up to 
20 subjects was estimated based on systematic literature review analysis sets. 
9.4 
Analysis Sets 
Safety analyses will be performed on the All-enrolled Population, consisting of all subjects who 
undergo at least one PET/CT scan or receive any amount of 124I-AT-01.  
Analyses of repeatability will be performed on the Image Evaluable Population, consisting of all 
subjects who undergo PET/CT scans on both Day 1 and 6 to 8 weeks after Day 1 and who have 
evaluable images at both time points. 
9.5 
Statistical Analyses 
The study statistical analysis plan (SAP) will specify the statistical methodology and reporting 
for all aspects of the planned analyses. Additional unplanned analyses may be required. All 
unplanned analyses will be clearly identified in the clinical study report. 
9.5.1 
General Considerations 
This is an open-label, single arm study. In general, for continuous variables, the mean, standard 
deviation (SD), median, and range will be presented. Categorical variables will be summarized 
by frequency counts and percentages. 
Subject disposition will be summarized for all subjects who signed the ICF and will include the 
number of subjects who received study treatment and the number and percentage of subjects who 
completed or prematurely discontinued the study, classified by reasons for premature 
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Discontinuations  
The reason for study discontinuation and the number of days post-study drug treatment on which 
the subject discontinued will be summarized. 
Protocol Deviations 
Protocol deviations will be provided in a listing with reasons for the deviation and the date of 
occurrence. Any exclusion of subjects from exploratory analysis populations, and how these 
exclusions impact data analysis, will be addressed in the clinical study report.  
Missing Data 
There will be no imputation for missing safety or whole blood radioactivity data. 
9.5.2 
Primary Endpoint(s) 
The primary objective of this study is to evaluate the repeatability of organ-specific quantitation 
of radiotracer uptake following PET/CT imaging of AT-01 in subjects with AL or ATTR 
systemic amyloidosis. The corresponding primary endpoint is:  
• Repeatability coefficient (Bland-Altman plots) and intraclass correlation coefficient 
(ICC) associated with the quantification of radioactivity associated with organ level 
124I-AT-01 uptake measurements. 
The signal to noise ratio (SNR) and contrast to noise ratio (CNR) will be plotted against 
standardized uptake value (SUV) based metrics. Repeatability will be assessed using Bland-
Altman plots. ICC and its associated 95% confidence interval will be presented. Quantitative 
organ uptake analyzed by an automated method will be summarized. Between-reader agreement 
in visual determination of AT-01 uptake will be evaluated by Cohen’s kappa. 
9.5.3 
Secondary Endpoint(s) 
The secondary objective of this study is to characterize the safety and tolerability of repeat doses 
of 124I-AT-01 administered by IV infusion or slow IV bolus. The corresponding secondary 
endpoints are as follows: 
• Incidence of treatment-emergent AEs from Day 1 to EOS. AEs will be graded using 
Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5. 
• Change from Baseline in clinical laboratory values at Visits 2 and Safety Follow-up 1 (1-3 
days after the second administration of 124I-AT-01). Clinical laboratory tests are described in 
Section 10.2 and include hematology and serum chemistry. 
• Change from Baseline in vital signs. 
• Change from Baseline in ADA. 

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Exploratory analyses may be performed to examine the relationship between images and 
biomarkers including, but not limited to, NT-proBNP, free light chains (AL subjects only), and 
UACR (AL subjects only). 
9.5.4 
Safety Analysis 
Safety will be assessed through reported adverse events (graded using NCI CTCAE version 5) 
and changes in laboratory parameters. 
Adverse Events 
All adverse events occurring during the study will be recorded and classified based on Medical 
Dictionary for Regulatory Activities (MedDRA) terminology. Only treatment-emergent adverse 
events (TEAEs), which are adverse events that occur after the start of study drug, will be 
summarized.  
The number and percentage of subjects experiencing TEAEs and SAEs will be tabulated for the 
safety population by system organ class (SOC) and preferred term (PT). TEAEs and SAEs will 
be tabulated by severity and relationship to study medication. Each subject will be counted only 
once within a SOC or a PT by using the AE with the highest severity or greatest relationship, 
respectively, within each category.  
TEAEs or SAEs leading to early discontinuation will be summarized as described above. 
Treatment-emergent adverse events starting on the day of dosing at each dosing visit will be 
summarized by SOC and PT to evaluate potential infusion-related reactions.   
Listings for all reported adverse events, including SAEs, will be provided. In addition, separate 
listing for SAEs, AEs leading to premature withdrawal from the study, and all deaths will be 
generated. 
Vital signs will include blood pressure (mmHg) and heart rate (beats per minute). Vital signs will 
be summarized at Baseline and for each study visit when vital signs were obtained. Changes 
from Baseline in vital sign measurements will also be summarized. Baseline is defined as the last 
vital signs obtained prior to the initiation of study drug. 
Clinical Laboratory Analyses 
Baseline for clinical chemistry parameters is defined as the most recent laboratory measurement 
obtained prior to the initiation of study drug. Clinical laboratory parameters from the tests 
itemized in Section 10.2, will be summarized as both absolute value and change from Baseline 
for each visit per the SoA (Section 1.3).  
Laboratory parameters with quantitative abnormalities will be listed as ‘flagged’ based on the 
Sponsor’s internal guidelines. Flagged laboratory parameters will be presented by incidence and 
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Clinical safety laboratory tests performed during the study will be analyzed by a central clinical 
laboratory. 
9.6 
Interim Analyses 
Not applicable. 
 

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10.0 
APPENDICES WITH SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
Appendix 1: Regulatory, Ethical, and Study Oversight Considerations 
Appendix 2:  Clinical Laboratory Tests 
Appendix 3:  AEs and SAEs: Definitions and Procedures for Recording, Evaluating, Follow-up, 
and Reporting 
Appendix 4: Contraceptive and Barrier Guidance 
Appendix 5:  Protocol Amendment History 
 
 

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10.1 
Appendix 1: Regulatory, Ethical, and Study Oversight Considerations 
10.1.1 
Regulatory and Ethical Considerations 
This study will be conducted in accordance with the protocol and with the following: 
• 21CFR Parts 50, 54, 56 and 312; 
• Applicable ICH Good Clinical Practice (GCP) Guidelines;  
• Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical Sciences 
(CIOMS); and 
• Applicable local laws and regulations. 
The protocol, protocol amendments, ICF, Investigator Brochure, and other relevant documents 
(e.g., advertisements) must be submitted to an IRB/IEC by the Investigator and reviewed and 
approved by the IRB/IEC before the study is initiated. 
Any amendments to the protocol will require IRB/IEC approval before implementation of 
changes made to the study design, except for changes necessary to eliminate an immediate 
hazard to study subjects.  
The Investigator is responsible for the following: 
• Providing written summaries of the status of the study to the IRB/IEC at least annually, in 
accordance with the requirements, policies, and procedures established by the IRB/IEC; 
• Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures; and 
• Providing oversight of the conduct of the study at the site and adherence to requirements 
of 21 CFR, ICH guidelines, the IRB/IEC, and all other applicable local regulations. 
10.1.2 
Financial Disclosure 
Investigators must provide financial disclosure information to allow the Sponsor to submit 
complete and accurate certification or disclosure statements to the appropriate regulatory 
authorities. In addition, Investigators must provide to the Sponsor a commitment to promptly 
update this information if any relevant changes occur during the investigation and for 1 year 
following the completion of the study. 
Neither the Sponsor nor their Contract or Clinical Research Organization (CRO) partner is 
financially responsible for additional testing or treatment of any medical condition that may be 
detected during the screening process. In addition, in the absence of specific arrangements, 
neither the Sponsor nor their CRO are financially responsible for further treatment of the 
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10.1.3 
Informed Consent 
A signed and dated IRB approved ICF will be obtained prior to any protocol-specified screening 
procedures being performed. Each subject will be provided with oral and written information 
describing the nature, purpose, and duration of the study; participation/termination conditions; 
and risks and benefits. The subject will also sign and date an authorization form required under 
the Health Insurance Portability and Accountability Act (HIPPA), if applicable, that authorizes 
the use and disclosure of the subject’s protected health information. The original signed ICF will 
be retained in the subject records, and a copy will be provided to the subject.  
Subjects unable to sign the ICF may participate in the study if a legal representative or witness 
provides the consent (in accordance with ICH-GCP and local regulations) and the subject 
confirms his/her interest in study participation. The subject will be informed that they can freely 
withdraw consent and stop participation in the study at any time with no prejudice post-study 
care.  
Subjects who are re-screened are required to sign a new ICF if it has been more than 30 days 
from the initial consent date. 
10.1.4 
Data Protection 
Subjects will be sequentially assigned a study number at Screening that will be used throughout 
the study. All subject records or datasets that are transferred to the Sponsor will contain the 
identifier only; subject names or other identifiable information will not be transferred. 
The subject must be informed that his/her personal study-related data will be used by the 
Sponsor in accordance with local data protection law. The level of disclosure must also be 
explained to the subject during the informed consent process (Section 10.1.3).  
Subject medical information obtained by this study is confidential, and disclosure to third parties 
other than those noted below is prohibited. All laboratory specimens, evaluation forms, reports, 
and other records will be identified in a manner designed to maintain subject confidentiality. All 
records will be kept in a secure storage area with limited access. Upon the subject’s permission, 
medical information may be given to his or her personal physician or other appropriate medical 
personnel responsible for his or her welfare. 
The subject must be informed that his/her medical records may be examined by Clinical Quality 
Assurance auditors or other authorized personnel appointed by the Sponsor, by appropriate 
IRB/IEC members, and by health authority inspectors. 
All information provided by the Sponsor, verbally and in writing, is confidential. The 
Investigator agrees not to disclose any such information without prior written permission of the 
Sponsor. This document may be disclosed to study personnel under the Investigator’s 
supervision and to the IRB under the condition that they also agree to maintain its 
confidentiality. Any supplemental information (e.g., protocol amendment) that may be added to 

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this document is confidential and must also be handled accordingly. The information obtained 
from the Sponsor may be disclosed to obtain informed consent from subjects who wish to 
participate in the study. 
Study documents provided by the Sponsor (protocols, IB, etc.) will be stored appropriately to 
ensure their confidentiality.  
The Investigator and all employees and co-workers involved with this study may not disclose or 
use for any purpose other than performance of the study any data, record, or other unpublished, 
confidential information disclosed to those individuals for the purpose of the study. Prior written 
agreement from the Sponsor or its designee must be obtained for the disclosure of any said 
confidential information to other parties. 
10.1.5 
Data Quality Assurance 
All subject data relating to the study will be recorded on printed or eCRF unless transmitted to 
the Sponsor or designee electronically (e.g., laboratory data). The Investigator is responsible for 
verifying that data entries are accurate and correct by physically or electronically signing the 
eCRF. 
The Investigator must permit study-related monitoring, audits, IRB/IEC review, and regulatory 
agency inspections and provide direct access to source data documents. 
Monitoring details describing strategy (e.g., risk-based initiatives in operations and quality such 
as Risk Management and Mitigation Strategies and Analytical Risk-Based Monitoring), methods, 
responsibilities and requirements, including handling of noncompliance issues and monitoring 
techniques (central, remote, or on-site monitoring) are provided in the Monitoring Plan. 
The Sponsor or designee is responsible for the data management of this study including quality 
checking of the data. 
The Sponsor assumes accountability for actions delegated to other individuals (e.g., CROs). 
Records and documents, including signed ICFs, pertaining to the conduct of this study must be 
retained by the Investigator for 10 years after study completion unless local regulations or 
institutional policies require a longer retention period. No records may be destroyed during the 
retention period without the written approval of the Sponsor. No records may be transferred to 
another location or party without written notification to the Sponsor. 
10.1.6 
Source Documents 
All medical information obtained at each study visit must be recorded in the subject’s record 
(source documentation) in real time as it is collected. Source documentation consists of original 
subject documents, as well as data and records with information relevant to the subject and 
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Source documents consist of, but are not limited to, subject hospital charts, clinic notes, subject 
medical records, original test results, laboratory data, worksheets, drug accountability records, 
consent forms, telephone records, etc. Source documents must be available for review and 
inspection during on-site monitoring of the study by the Sponsor, their designees, the IRB, 
and/or appropriate regulatory authorities. 
Subject-completed forms are also considered source data. Only subjects are to record 
information in subject diaries and questionnaires, if used. In no instance should an Investigator or 
study site personnel record any data or make changes to subject-completed forms. The 
Investigator or designee should review subject-completed forms during study visits. If an entry is 
found to be illegible or a mistake is found (e.g., incorrect year was recorded), the subject may be 
instructed to edit the entry 
10.1.7 
Study and Site Start and Closure 
First Act of Recruitment 
The study start date is the date on which the clinical study will be open for recruitment of 
subjects. 
Study/Site Termination Due to Adverse Events 
Study stopping criteria due to adverse events are provided in Section 7.1.1. 
Study/Site Termination Due to Other Reasons 
The Sponsor or designee reserves the right to close the study site or terminate the study at any 
time for any reason at the sole discretion of the Sponsor. Study sites will be closed upon study 
completion. A study site is considered closed when all required documents and study supplies 
have been collected and a study site closure visit has been performed. 
The Investigator may initiate study site closure at any time, provided there is reasonable cause 
and sufficient notice is given in advance of the intended termination. 
Reasons for the early closure of a study site by the Sponsor or Investigator may include but are 
not limited to: 
For study termination: 
• Discontinuation of further study intervention development. 
For site termination: 
• Failure of the Investigator to comply with the protocol, the requirements of the IRB/IEC 
or local health authorities, the Sponsor's procedures, or GCP guidelines; and/or 

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Inadequate or no recruitment (evaluated after a reasonable amount of time) of subjects by the 
Investigator. If the study is prematurely terminated or suspended, the Sponsor shall promptly 
inform the Investigators, the IECs/IRBs, the regulatory authorities, and any contract research 
organization(s) used in the study of the reason for termination or suspension, as specified by the 
applicable regulatory requirements. The Investigator shall promptly inform the subject and 
should assure appropriate subject therapy and/or follow-up 
10.1.8 
Publication Policy 
• All study data generated from this study will be regarded as confidential, until 
appropriate analysis and review by the Sponsor or its designee and the Investigator(s) are 
completed. The results of the study may be published or presented at scientific meetings 
by the Investigator(s) after the review by, and in consultation and agreement with the 
Sponsor, such that confidential or proprietary information is not disclosed. 
• Prior to publication or presentation, a copy of the final text should be forwarded by the 
Investigator(s) to the Sponsor or its designee, for comment. Such comments shall aim to 
ensure the scientific integrity of the proposed publications and/or presentations and 
ensure that the data and material referring to Attralus, Inc products and activities receive 
fair, accurate, and reasonable presentation. 
• The Sponsor will comply with the requirements for publication of study results. 
• Authorship will be determined by mutual agreement and in line with International 
Committee of Medical Journal Editors authorship requirements. 
 
 

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10.2 
Appendix 2: Clinical Laboratory Tests 
Laboratory 
Tests  
Parameters 
Hematology 
Complete blood count (CBC) with differential  
WBC differential: 
• 
Bands/stabs 
• 
Neutrophils 
• 
Eosinophils 
• 
Basophils 
• 
Lymphocytes 
• 
Monocytes 
White blood cell (WBC) count 
Red blood cell (RBC) count 
Hemoglobin (Hgb) 
Hematocrit (Hct) 
Platelet count (Plt) 
Serum 
Chemistry 
Sodium (Na) 
Creatinine (Cr) 
Alanine aminotransferase 
(ALT, SGPT) 
Potassium (K) 
Uric acid 
Aspartate aminotransferase 
(AST, SGOT) 
Chloride (Cl) 
Albumin 
Calcium (Ca) 
Bicarbonate (HCO3)/CO2 
Total protein 
Phosphate (PO4) 
Glucose 
Total bilirubin  
Lactate dehydrogenase (LDH) 
Blood urea nitrogen (BUN) 
Alkaline phosphatase  
 
Biomarker 
Assays 
N-terminal prohormone of brain natriuretic 
peptide (NT-proBNP) 
Serum free light chain1 
Brain natriuretic peptide (BNP) 
Urine albumin creatinine ratio (UACR)1 
Pregnancy 
Testing 
Highly sensitive serum human chorionic gonadotropin (hCG) pregnancy test (as needed for 
women of childbearing potential)2 
1. Subjects with AL systemic amyloidosis only.  
2. Serum pregnancy and laboratory tests must be drawn within 7 days prior to 124I-AT-01 administration in all 
WOCBP. The results of the pregnancy test must be available and be negative prior to 124I-AT-01 
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T 
10.3 
Appendix 3: AEs and SAEs: Definitions and Procedures for Recording, Evaluating, 
Follow-up, and Reporting 
10.3.1 
Definition of AE 
AE Definition 
• 
An AE is any untoward medical occurrence in a clinical study subject, temporally associated with the use of 
study intervention, whether or not considered related to the study intervention. 
• 
NOTE: An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory 
finding), symptom, or disease (new or exacerbated) temporally associated with the use of study intervention. 
 
Definition of Unsolicited and Solicited AE 
• 
An unsolicited AE is an AE that was not solicited using a Subject Diary and that is communicated by a 
subject or subject’s parent(s)/ legally authorized representative (LAR) who has signed the informed consent. 
Unsolicited AEs include serious and non-serious AEs. 
• 
Potential unsolicited AEs may be medically attended (i.e., symptoms or illnesses requiring a hospitalization, 
or emergency room visit, or visit to/by a health care provider). The subjects or subject’s parent(s)/LAR will 
be instructed to contact the site as soon as possible to report medically attended event(s), as well as any 
events that, though not medically attended, are of subject or parental/LAR’s concern. Detailed information 
about reported unsolicited AEs will be collected by qualified site personnel and documented in the subject’s 
records. 
• 
Unsolicited AEs that are not medically attended nor perceived as a concern by the subject or subject’s 
parent(s)/LAR(s) will be collected during interview with the subject or subject’s parent(s)/LAR(s) and by 
review of available medical records at the next visit. 
• 
Solicited AEs are predefined local (at the infusion site) and systemic events for which the subject is 
specifically questioned, and which are noted by the subject in their diary.  
 
Events Meeting the AE Definition 
• 
Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or other safety 
assessments (e.g., ECG, radiological scans, vital signs measurements), including those that worsen from 
Baseline, considered clinically significant in the medical and scientific judgment of the Investigator (i.e., not 
related to progression of underlying disease). 
• 
Exacerbation of a chronic or intermittent pre-existing condition including either an increase in frequency 
and/or intensity of the condition. 
• 
New conditions detected or diagnosed after study intervention administration even though it may have been 
present before the start of the study. 
• 
Signs, symptoms, or the clinical sequelae of a suspected intervention- intervention interaction. 
• 
Signs, symptoms, or the clinical sequelae of a suspected overdose of either study intervention or a 
concomitant medication. Overdose per se will not be reported as an AE/SAE unless it is an intentional 
overdose taken with possible suicidal/self-harming intent. Such overdoses should be reported regardless of 
sequelae. 
 
 

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Events NOT Meeting the AE Definition 
• 
Any clinically significant abnormal laboratory findings or other abnormal safety assessments which are 
associated with the underlying disease, unless judged by the Investigator to be more severe than expected for 
the subject’s condition. 
• 
The disease/disorder being studied or expected progression, signs, or symptoms of the disease/disorder being 
studied, unless more severe than expected for the subject’s condition. 
• 
Medical or surgical procedure (e.g., endoscopy, appendectomy): the condition that leads to the procedure is 
the AE. 
• 
Situations in which an untoward medical occurrence did not occur (social and/or convenience admission to a 
hospital). 
• 
Anticipated day-to-day fluctuations of pre-existing disease(s) or condition(s) present or detected at the start 
of the study that do not worsen. 
 
10.3.2 
Definition of SAE 
An SAE is defined as any serious AE that, at any dose: 
• 
Results in death 
• 
Is life-threatening 
The term 'life-threatening' in the definition of 'serious' refers to an event in which the subject was at risk of death 
at the time of the event. It does not refer to an event, which hypothetically might have caused death, if it were 
more severe. 
• 
Requires inpatient hospitalization or prolongation of existing hospitalization 
- 
In general, hospitalization signifies that the subject has been admitted (usually involving at least an 
overnight stay) at the hospital or emergency ward for observation and/or treatment that would not have 
been appropriate in the physician’s office or outpatient setting. Complications that occur during 
hospitalization are AEs. If a complication prolongs hospitalization or fulfills any other serious criteria, 
the event is serious. When in doubt as to whether “hospitalization” occurred or was necessary, the AE 
should be considered serious. 
- 
Hospitalization for elective treatment of a pre-existing condition that did not worsen from Baseline is 
not considered an AE. 
• 
Results in persistent or significant disability/incapacity 
- 
The term disability means a substantial disruption of a person’s ability to conduct normal life functions. 
- 
This definition is not intended to include experiences of relatively minor medical significance such as 
uncomplicated headache, nausea, vomiting, diarrhea, influenza, and accidental trauma (e.g., sprained 
ankle) which may interfere with or prevent everyday life functions but do not constitute a substantial 
disruption. 
• 
Is a congenital anomaly/birth defect 
• 
Other situations: 
- 
Medical or scientific judgment should be exercised by the Investigator in deciding whether SAE 
reporting is appropriate in other situations such as significant medical events that may jeopardize the 
subject or may require medical or surgical intervention to prevent one of the other outcomes listed in the 
above definition. These events should usually be considered serious. 
- 
Examples of such events include invasive or malignant cancers, intensive treatment for allergic 
bronchospasm, blood dyscrasias, convulsions, or development of intervention dependency or 
intervention abuse. 
 
 
 

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10.3.3 
Recording and Follow-Up of AE and/or SAE 
AE and SAE Recording 
• 
When an AE/SAE occurs, it is the responsibility of the Investigator to review all documentation (e.g., 
hospital progress notes, laboratory reports, and diagnostics reports) related to the event. 
• 
The Investigator will then record all relevant AE/SAE information. 
• 
It is not acceptable for the Investigator to send photocopies of the subject’s medical records to the Sponsor or 
designee in lieu of completion of SAE/AE required form. 
• 
There may be instances when copies of medical records for certain cases are requested by the Sponsor or 
designee. In this case, all subject identifiers, with the exception of the subject number, will be redacted on the 
copies of the medical records before submission to the Sponsor or designee. 
• 
The Investigator will attempt to establish a diagnosis of the event based on signs, symptoms, and/or other 
clinical information. Whenever possible, the diagnosis (not the individual signs/symptoms) will be 
documented as the AE/SAE. 
Assessment of Intensity 
The Investigator will make an assessment of intensity for each AE and SAE reported during the study and assign 
it to one of the following categories:  
• 
Mild: An event that is easily tolerated by the subject, causing minimal discomfort and not interfering with 
everyday activities. 
• 
Moderate: An event that causes sufficient discomfort to interfere with normal everyday activities. 
• 
Severe: An event that prevents normal everyday activities. An AE that is assessed as severe should not be 
confused with an SAE. Severe is a category utilized for rating the intensity of an event; and both AEs and 
SAEs can be assessed as severe. 
• 
An event is defined as ‘serious’ when it meets at least one of the predefined outcomes as described in the 
definition of an SAE, NOT when it is rated as severe. 
 
Assessment of Causality 
• 
The Investigator is obligated to assess the relationship between study intervention and each occurrence of 
each AE/SAE. 
• 
A “reasonable possibility” of a relationship conveys that there are facts, evidence, and/or arguments to 
suggest a causal relationship, rather than a relationship cannot be ruled out. 
• 
The Investigator will use clinical judgment to determine the relationship. 
• 
Alternative causes, such as underlying disease(s), concomitant therapy, and other risk factors, as well as the 
temporal relationship of the event to study intervention administration will be considered and investigated. 
• 
The Investigator will also consult the IB and/or Product Information, for marketed products, in his/her 
assessment. 
• 
For each AE/SAE, the Investigator must document in the medical notes that he/she has reviewed the 
AE/SAE and has provided an assessment of causality. 
• 
There may be situations in which an SAE has occurred, and the Investigator has minimal information to 
include in the initial report to Attralus, Inc. However, it is very important that the Investigator always make 
an assessment of causality for every event before the initial transmission of the SAE data to Attralus, Inc. 
• 
The Investigator may change his/her opinion of causality in light of follow-up information and send an SAE 
follow-up report with the updated causality assessment. 
• 
The causality assessment is one of the criteria used when determining regulatory reporting requirements. 
 
 

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Follow-up of AEs and SAEs 
• 
The Investigator is obligated to perform or arrange for the conduct of supplemental measurements and/or 
evaluations as medically indicated or as requested by Attralus, Inc to elucidate the nature and/or causality of 
the AE or SAE as fully as possible. This may include additional laboratory tests or investigations, 
histopathological examinations, or consultation with other health care professionals. 
• 
If a subject dies during participation in the study or during a recognized follow-up period, the Investigator 
will provide Attralus, Inc with a copy of any postmortem findings including histopathology. 
• 
New or updated information will be recorded in the originally submitted documents. 
• 
The Investigator will submit any updated SAE data to Attralus, Inc within 24 hours of receipt of the 
information. 
 
10.3.4 
Reporting of SAEs 
SAE Reporting to Attralus, Inc. via the Electronic Data Collection (EDC) System 
• 
The primary mechanism for reporting an SAE to Attralus, Inc. will be the EDC system. 
• 
If the EDC system is unavailable, then the site will use the paper SAE data collection tool (see next section) 
to report the event within 24 hours. 
• 
The site will enter the SAE data into the EDC system as soon as it becomes available. 
• 
After the study is completed at a given site, the EDC system will be taken off-line to prevent the entry of new 
data or changes to existing data. 
• 
If a site receives a report of a new SAE from a study subject or receives updated data on a previously 
reported SAE after the EDC system has been taken off-line, then the site can report this information as noted 
in the Study Manual. 
• 
Contacts for SAE reporting can be found in the Study Manual. 
 
SAE Reporting to Attralus, Inc. via Paper Data Collection Tool 
• 
It is the responsibility of the Investigator to report SAEs to the Sponsor within 24 hours of awareness of the 
event or safety information, whether initial or follow-up. Do not delay in the reporting of suspected SAE in 
order to obtain additional information. Any additional information, if collected, can be reported to the 
Sponsor as a follow-up to the initial report. 
• 
In rare circumstances and in the absence of facsimile equipment, notification by telephone is acceptable 
with a copy of the SAE data collection tool sent by overnight mail or courier service. 
• 
Initial notification via telephone does not replace the need for the Investigator to complete and sign the 
SAE data collection tool within the designated reporting time frames. 
• 
Contacts for SAE reporting can be found in the Study Manual. 
 
 

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10.4 
Appendix 4: Contraceptive and Barrier Guidance 
10.4.1 
Definitions 
Women of Childbearing Potential (WOCBP) 
A woman is considered fertile following menarche and until becoming postmenopausal unless 
permanently sterile (see below). 
If fertility is unclear (e.g., amenorrhea in adolescents or athletes) and a menstrual cycle cannot be 
confirmed before first dose of study intervention, additional evaluation should be considered. 
Women in the following categories are not considered WOCBP: 
• Premenarchal; or 
• Premenopausal female with one of the following: 
- 
Documented hysterectomy 
- 
Documented bilateral salpingectomy 
- 
Documented bilateral oophorectomy 
For individuals with permanent infertility due to an alternate medical cause other than the above, 
(e.g., Müllerian agenesis, androgen insensitivity), Investigator discretion should be applied to 
determining study entry. 
Note: Documentation can come from the site personnel’s: review of the subject’s medical 
records, medical examination, or medical history interview. 
Postmenopausal Female 
A postmenopausal state is defined as no menses for 12 months without an alternative medical 
cause. 
A high follicle stimulating hormone (FSH) level in the postmenopausal range may be used to 
confirm a postmenopausal state in women not using hormonal contraception or hormone 
replacement therapy (HRT). However, in the absence of 12 months of amenorrhea, confirmation 
with more than one FSH measurement is required. The Screening Visit FSH will be processed 
using the chemistry tube and the Day 1 FSH will need to be collected separately and sent to the 
central lab for analysis. A pregnancy test is required until both FSH measurements have been 
collected and results have been received that verify the postmenopausal state of the female 
subject. 
Females on HRT and whose menopausal status is in doubt will be required to use one of the non-
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during the study. Otherwise, they must discontinue HRT to allow confirmation of 
postmenopausal status before study enrollment. 
10.4.2 
Contraception Guidance 
For Women of Childbearing Potential 
Agreement to remain as abstinent (refrain from heterosexual intercourse) or use contraceptive 
methods that result in a failure rate of <1% per year during the treatment period and for at least 
90 days after the last dose of study intervention.  
a. A woman is considered of childbearing potential if she is postmenarchal, has not reached 
a postmenopausal state (≥12 months of amenorrhea with no identified cause other than 
menopause), and has not undergone surgical sterilization (removal of ovaries and/or 
uterus). The definition of childbearing potential may be adapted for alignment with local 
guidelines or requirements. 
b. Examples of contraceptive methods with a failure rate of <1% per year include bilateral 
tubal ligation, male sterilization, established, proper use of hormonal contraceptives that 
inhibit ovulation, hormone-releasing intrauterine devices, and copper intrauterine 
devices. 
c. Contraception methods that do not result in a failure rate of <1% per year such as cap, 
diaphragm, or sponge with spermicide, or male or female condom with or without 
spermicide, are not acceptable. 
The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical 
trial and the preferred and usual lifestyle of the subject. Periodic abstinence (e.g., calendar, 
ovulation, symptothermal, or post-ovulation methods) and withdrawal are not acceptable 
methods of contraception. 
For Men:  
Agreement to remain abstinent or use contraceptive measures and agreement to refrain from 
donating sperm, as defined below: 
a. With female partners of childbearing potential, men must remain abstinent or use a 
condom plus an additional contraceptive method that together result in a failure rate of 
<1% per year during the treatment period and for at least 30 days plus 90 days (a 
spermatogenesis cycle) after the last dose of study intervention. Men must refrain from 
donating sperm during this same time period 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
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10.4.3 
Collection of Pregnancy Information  
Female Subjects Who Become Pregnant 
• The Investigator will collect pregnancy information on any female subject who becomes 
pregnant while participating in this study. The initial information will be recorded on the 
appropriate form and submitted to the Sponsor within 24 hours of learning of a subject's 
pregnancy.  
• The subject will be followed to determine the outcome of the pregnancy. The Investigator 
will collect follow-up information on the subject and the neonate and the information will be 
forwarded to the Sponsor. Generally, follow-up will not be required for longer than 6 to 8 
weeks beyond the estimated delivery date. Any termination of pregnancy will be reported, 
regardless of fetal status (presence or absence of anomalies) or indication for the procedure. 
• While pregnancy itself is not considered to be an AE or SAE, any pregnancy complication or 
elective termination of a pregnancy for medical reasons will be reported as an AE or SAE.  
• A spontaneous abortion (occurring at <22 weeks gestational age) or stillbirth (occurring at 
>22 weeks gestational age) is always considered to be an SAE and will be reported as such.  
• Any post-study pregnancy related SAE considered reasonably related to the study 
intervention by the Investigator will be reported to the Sponsor, as described in Section 8.3.5. 
While the Investigator is not obligated to actively seek this information in former study 
subjects, he or she may learn of an SAE through spontaneous reporting. 
• Any female subject who becomes pregnant while participating in the study will discontinue 
study intervention or be withdrawn from the study. 
Male Subjects with Partners Who Become Pregnant 
• The Investigator will attempt to collect pregnancy information on any male subject’s female 
partner who becomes pregnant while the male subject is in this study. This applies only to 
male subjects who receive any study intervention. 
After obtaining the necessary signed informed consent from the pregnant female partner directly, 
the Investigator will record pregnancy information on the appropriate form and submit it to the 
Sponsor within 24 hours of learning of the partner’s pregnancy. The female partner will also be 
followed to determine the outcome of the pregnancy. Information on the status of the mother and 
child will be forwarded to the Sponsor. Generally, the follow-up will be no longer than 6 to 8 
weeks following the estimated delivery date. Any termination of the pregnancy will be reported 
regardless of fetal status (presence or absence of anomalies) or indication for the procedure. 
 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
- 59 - 
10.5 
Appendix 5: Protocol Amendment History 
The amendment history for Protocol AT01-001 is provided in Table 3. 
Table 3: 
Protocol AT01-001: Amendment History 
Version 
Version Date 
Brief Description  
2.0 
08 March 2022 
Revisions from Version 1.1 include the following: 
• 
Addition of slow IV bolus at 1 mL/5 seconds as a method of 
administration. 
• 
Updated clinical experience to reflect final results from Study 
AMY1001. 
• 
Minor administrative and editorial revisions. 
1.1 
07 October 2021 
Revisions from Version 1.0 include the following: 
• 
Addition of heparin/heparin analogs as a prohibited concomitant 
medication within 7 days of infusion of 124I-AT-01. 
• 
Minor administrative and editorial revisions. 
1.0 
27 September 2021 
• 
Original protocol; used for pre-submission activities. This version 
was not submitted to any health authorities or IRBs/ECs, nor was it 
implemented. 
 

CONFIDENTIAL 
Protocol AT01-001, Version 2.0 
Attralus, Inc. 
124I-AT-01 
 
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11.0 
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