A Phase 1, Open-label, Positron Emission Tomography Study in Healthy Subjects to Determine the Relationship Between Plasma Concentration and Target Occupancy of ASN51 Following Repeated Oral Doses
Phase: PHASE1
Conditions: Healthy
Sponsor: Asceneuron S.A.



HMR Ltd - Confidential 
 
Asceneuron S.A. 
Trial Protocol 
Confidential 
Trial title 
A phase 1, open-label, positron emission tomography 
study in healthy subjects to determine the relationship 
between plasma concentration and target occupancy 
of ASN51 following repeated oral doses. 
Short title 
PET study of repeated ASN51 in healthy volunteers 
Version and date of protocol 
Version 2, dated 23 January 2023 
HMR code 
22-012 
Sponsor code 
ASN51-103 
Invicro code 
COM221594 
IRAS number 
1006677 
Trial medication 
ASN51 (O-linked-β-N-acetylglucosaminidase 
inhibitor) 
Phase of trial 
Phase 1 
Place of trial 
Hammersmith Medicines Research (HMR) 
Cumberland Avenue 
London NW10 7EW 
Tel: +44(0)20 8961 4130 Fax: +44(0)20 8961 8665 
Invicro 
Burlington Danes Building, Imperial College London 
Hammersmith Hospital, Du Cane Road 
London W12 0NN 
Chief investigator 
 MBBS JCPTGP MPhil 
HMR 
Principal investigator 
BSc MBBCh FCPsych SA 
Invicro 
Sponsor 
Asceneuron S.A. 
EPFL Innovation Park, Bâtiment B 
1015 Lausanne, Switzerland, CH-1015 
Tel: +41 (0)21 353 8242 Fax: +41 (0)21 693 8247 
Planned dates of trial 
January 2023 to April 2023 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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Version control history 
Version 
Reason for change 
2, dated 23 January 2023 
Response to GNA 
1, dated 07 November 2022 
N/A 

PET study of repeated ASN51 in healthy volunteers
Trial Codes: 22-012 and ASN51-103
Protocol Version 2, dated 23 January 2023
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1 
Signatures
The investigator and the sponsor have discussed this protocol. The investigator 
agrees to perform the investigation and to abide by this protocol and any future 
agreed amendments, except in case of medical emergency.
Chief investigator
24-Jan-2023
HMR
Signature
Date
Principal investigator
24-Jan-2023
Invicro
Signature
Date
Statistician
24-Jan-2023
HMR
Signature
Date
Sponsor
Asceneuron S.A.
Signature
Date
23-Jan-2023

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
Page 4 of 80 
HMR Ltd - Confidential 
 
 
2 
Summary 
2.1 
Trial medication 
ASN51 is a reversible, substrate-competitive inhibitor of 
O-linked-N-acetylglucosaminidase (O-GlcNAcase). It is being developed as an 
orally-administered treatment for neurodegenerative diseases such as Alzheimer’s 
Disease (AD), Progressive Supranuclear Palsy (PSP), and other tauopathies. 
 
2.2 
Objectives 
 
2.2.1 
Primary objectives 
• To assess the pharmacodynamic (PD) response in peripheral blood mononuclear 
cells (PBMCs) following single and repeated oral doses of ASN51 in healthy 
subjects. 
• To assess brain O-GlcNAcase occupancy using [18F]-IMA601 positron emission 
tomography (PET), following repeated oral doses of ASN51 in healthy subjects. 
 
2.2.2 
Secondary objectives 
• To assess the safety and tolerability of repeated oral doses of ASN51 in healthy 
subjects 
• To assess the relationship between the plasma concentration of ASN51 and the 
time-course of brain O-GlcNAcase occupancy using [18F]-IMA601 PET, 
following repeated oral doses of ASN51 in healthy subjects 
• To assess the pharmacokinetics (PK) of repeated doses of ASN51 in healthy 
subjects 
• To assess the trough O-GlcNAcase occupancy of ASN51 after repeated doses in 
healthy subjects 
• To determine the effect of food on the PD response in PBMCs following repeated 
ASN51 dosing in healthy subjects 
 
2.3 
Endpoints 
 
2.3.1 
Primary endpoints 
PD: 
 
• 
O-GlcNAcylation of PBMCs 
• 
[18F]-IMA601 regional total volume of distribution (VT) at each brain scan 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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2.3.2 
Secondary endpoints 
Safety and tolerability: 
• vital signs (blood pressure, pulse rate, tympanic temperature, and respiratory 
rate), 12-lead safety electrocardiogram (ECG), physical and neurological 
examination, laboratory safety tests (haematology, clinical chemistry, 
coagulation, and urinalysis), Columbia-Suicide Severity Rating Scale (C-SSRS), 
and adverse events (AEs) 
PK: 
• plasma concentration of ASN51 at the time of each postdose PET scan 
• PK parameters including Cmax, Cmax/Dose, tmax, t½, λZ, AUCtau, AUClast, AUCinf, 
AUCinf /Dose, %AUCextrap, CLSS/F, VZ/F, Ctrough, Rac(Cmax), Rac(AUC). 
PD: 
• 
O-GlcNAcylation of PBMCs with or without prior feeding 
• 
Trough [18F]-IMA601 VT 
PK/PD: 
• relationship between ASN51 plasma concentration, PBMC target engagement, 
and brain receptor occupancy (RO) over time 
 
2.4 
Type of trial 
This is a phase 1, open-label, dose escalation, PET study to investigate the brain 
occupancy of O-GlcNAcase, and the PD response in PBMCs, after repeated doses of 
ASN51 in healthy subjects. 
 
2.5 
Trial population 
a 
Total Up to 12 healthy volunteers, excluding replacements 
b 
Age 
25–55 years 
c 
Main inclusion criteria 
Normotensive male volunteer (PET subjects), or male or female volunteer of non- 
childbearing potential (PBMC-only subjects), deemed healthy on the basis of a 
clinical history, physical and neurological examination, ECG, vital signs, and 
laboratory tests of blood and urine; agree to follow the contraception requirements of 
the trial; able to give fully informed written consent. 
d 
Main exclusion criteria 
Significant (> 10%) recent weight change; positive tests for hepatitis B & C, HIV; 
severe adverse reaction to any drug; sensitivity to trial medication; drug or alcohol 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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abuse; regular consumption of xanthine-containing products; frequent use of 
nicotine-containing products; severe adverse reaction to any drug; sensitivity to trial 
medication (all subjects) or PET imaging radioligand (PET subjects); use of over- 
the-counter medication (with the exception of paracetamol [acetaminophen]) during 
the 7 days before the first dose of radioligand (PET subjects) or trial medication 
(PBMC subjects) (or longer if the medicine is a potential enzyme inducer), or 
prescribed medication during the 28 days before first dose of radioligand (PET 
subjects) or trial medication (PBMC subjects); received vaccine against severe acute 
respiratory syndrome coronavirus 2 (SARS-CoV-2) within 2 weeks of screening; 
participation in other clinical trials of unlicensed medicines, or loss of more than 
400 mL blood, within the 3 months before the first dose of tracer (PET subjects) or 
trial medication (PBMC subjects); clinically relevant abnormal findings at the 
screening assessment, including ECG abnormalities (all subjects) or those identified 
by MRI scan (PET subjects only); acute or chronic illness; clinically relevant 
abnormal history of or concurrent medical (including neurological or psychiatric) 
condition; positive C-SSRS result; vegan; possibility that volunteer will not 
cooperate; unsatisfactory venous access; objection by General Practitioner (GP); 
PET subjects only: significant exposure to research related radiation (more than 
10 mSv) within the previous 12 months; contraindications to arterial cannulation 
(eg Allen’s test indicates risk) or MRI scanning (eg presence of a cardiac pacemaker 
or other implanted electronic device or a history of claustrophobia). 
 
2.6 
Trial design and methods 
Enrolment of up to 12 healthy subjects is planned, in up to 2 groups (Groups 1 and 
2). Each group will consist of up to 6 subjects. 
All subjects will receive once-daily (QD) doses of ASN51, by mouth, for 
14 days: Group 1 will receive 
 ASN51 QD and Group 2 will receive 
 
ASN51 QD. Group 2 will proceed only if the safety and tolerability of the previous 
dose level are acceptable, and the plasma concentrations of ASN51 are predicted to 
remain below the toxicokinetic limit, as determined by the Safety Review Group 
(SRG). 
On Day 11, to evaluate the effect of food on PBMC response, subjects will receive 
ASN51 in the fed state following a United States Food and Drug Administration 
(FDA) high-fat breakfast. Subject fasting requirements are further detailed in 
section 11. 
In each group, 2 subjects will have a PBMC-only study design (section 8.1.2) and 
4 will have a PBMC and PET scanning study design (section 8.1.3). 
Schematic diagrams of each study design are in section 8.2. 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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HMR Ltd - Confidential 
 
 
PBMC-only subjects 
2 subjects in each of Groups 1 and 2 will not have PET scans during the study. They 
will: 
• be screened within 28 days before their first dose of trial medication. 
• be resident on ward from 1 day before their first dose (Day –1) until 6 days after 
their final dose (Day 20). 
• return for a follow-up visit 9–11 days after their final dose of trial medication 
(Days 23–25). 
PET subjects 
4 subjects in each of Groups 1 and 2 will have PET scans during the study. PET 
subjects will: 
• be screened within 21 days before imaging session 1 (see below). 
• be resident on ward from 1 day before their first dose (Day –1) until 6 days after 
their final dose (Day 20); and have imaging sessions as described below. 
• return for a follow-up visit 9–11 days after their final dose of trial medication 
(Day 23 ± 2 days), or 2–4 days after imaging session 3 (see below), whichever is 
later. 
PET subjects will have up to 3 imaging sessions, as follows. 
• Imaging session 1. Subjects will have a baseline PET scan between Day –7 and 
Day –3. Subjects will be admitted to the ward the day before their baseline PET 
scan, and will be discharged after their scan. 
• Imaging session 2. Subjects will have an on-treatment PET scan at about 5 h 
postdose on Day 1. 
• Imaging session 3. Subjects will have an on-treatment PET scan at 3–9 days 
after their final dose of ASN51: 
• 3 subjects per group on Day 17 
• 1 subject on Day 22 (± 1 day) (Group 1 only) 
• 1 subject on Day 23 (± 1 day) (Group 2 only) 
The timing of on-treatment PET scans (imaging sessions 2 and 3) may be altered 
based on emerging data or study logistical requirements. 
Subjects will receive an intravenous dose of the radiolabelled tracer, [18F]-IMA601, 
at the start of each PET scan. 
Arterial blood sampling will be done during each PET scan to quantify the parent 
tracer-related radioactivity over the course of the PET scan, and to establish a tracer 
metabolite-corrected plasma input function. The total arterial blood volume required 
for each tracer injection will not exceed 120 mL. Arterial cannulation and arterial 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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blood sampling may be reduced or removed if analysis of PET data from previous 
subjects indicates that non-invasive analysis of the PET scan data can be done. If a 
non-invasive analysis is not possible, the use of an arterial cannula with each PET 
scan will continue through the study. 
In the case of a technical failure (such as unsuccessful tracer synthesis), subjects may 
be asked to attend an additional on-treatment imaging session as described in 
section 12.2. However, no subject will have more than 3 PET scans and 3 doses of 
[18F]-IMA601 during the study. 
 
2.7 
Assessments 
The following assessments will be made. 
 
2.7.1 
Pharmacodynamics 
Blood samples for PBMC assays will be taken before and frequently during dosing 
(up to 144 h [6 days] after the last dose). Trough samples will be taken before study 
drug administration. 
Occupancy of O-GlcNAcase by ASN51 will be assessed by PET imaging using the 
radioligand [18F]-IMA601 (PET subjects only). 
Blood samples will be taken during each PET scan for arterial input function and 
radio metabolite analysis (PET subjects only). 
 
2.7.2 
Safety and tolerability 
Laboratory assessments (routine haematology, clinical chemistry, coagulation, and 
urinalysis), physical and neurological examinations, 12-lead ECGs, and vital signs 
(blood pressure, pulse rate, respiratory rate, and tympanic temperature) and C-SSRS 
will be done frequently until the subject’s last visit. AEs will be recorded from 
screening until the subject’s last visit. 
Laboratory safety variables to be assessed during the study are in Table 4. 
From screening until the follow-up visit, AEs and concomitant medication will be 
documented as they are reported by the subjects. Subjects will be questioned about 
AEs on admission to the ward, when procedures are done, and when they return to 
the ward for outpatient visits/at follow-up. 
 
2.7.3 
Pharmacokinetics 
Blood samples for assay of ASN51 will be taken before and frequently during dosing 
(up to 144 h [6 days] after the last dose), and at follow-up. Trough samples will be 
taken before study drug administration. 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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PET subjects only: for subjects having imaging session 3 on Day 22 or 23, 
additional PK samples will be taken approximately 2 h before and after the PET 
scan. 
 
2.7.4 
Other 
Structural MRI scans will be done during the screening period (PET subjects only). 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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3 
Contents 
Version control history 
2 
1 
Signatures 
3 
2 
Summary 
4 
2.1 
Trial medication 
4 
2.2 
Objectives 
4 
2.2.1 
Primary objectives 
4 
2.2.2 
Secondary objectives 
4 
2.3 
Endpoints 
4 
2.3.1 
Primary endpoints 
4 
2.3.2 
Secondary endpoints 
5 
2.4 
Type of trial 
5 
2.5 
Trial population 
5 
2.6 
Trial design and methods 
6 
2.7 
Assessments 
8 
2.7.1 
Pharmacodynamics 
8 
2.7.2 
Safety and tolerability 
8 
2.7.3 
Pharmacokinetics 
8 
2.7.4 
Other 
9 
3 
Contents 
10 
3.1 
Table of Figures 
13 
3.2 
Table of Tables 
13 
4 
List of abbreviations 
14 
5 
Trial personnel 
17 
6 
Introduction 
19 
6.1 
Background 
19 
6.2 
Review of investigational medicinal product 
20 
6.2.1 
Non-clinical studies 
20 
6.2.2 
Clinical studies 
21 
6.2.2.1 
Study ASN51-101 
22 
6.2.2.2 
Study ASN51-102 
23 
6.3 
Review of non-investigational medicinal product 
24 
6.4 
Rationale for the trial 
24 
6.5 
Participant input into trial design 
25 
6.6 
Rationale for choice of doses 
25 
6.7 
Assessment and management of risk 
27 
6.8 
Conducting the trial during the COVID-19 pandemic 
30 
7 
Objectives and endpoints 
31 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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7.1 
Objectives 
31 
7.1.1 
Primary objectives: 
31 
7.1.2 
Secondary objectives: 
31 
7.2 
Endpoints 
31 
7.2.1 
Primary endpoints: 
31 
7.2.2 
Secondary endpoints: 
32 
8 
Overall trial design 
32 
8.1 
Trial design 
32 
8.1.1 
Trial design 
32 
8.1.2 
PBMC-only subjects 
33 
8.1.3 
PET subjects 
33 
8.2 
Study flow chart 
35 
8.3 
Definition of the end of the trial 
36 
8.4 
Stopping criteria 
36 
8.4.1 
Trial stopping criteria 
36 
8.5 
Criteria for proceeding to Group 2 
36 
8.5.1 
Review of data by the Safety Review Group 
36 
9 
Trial population 
37 
9.1 
Planned number of subjects 
37 
9.2 
Inclusion criteria 
37 
9.3 
Exclusion criteria 
38 
9.4 
Withdrawal of subjects from the trial 
41 
9.4.1 
Subject withdrawal 
41 
9.4.2 
Individual subject stopping criteria 
42 
9.4.3 
Replacement of withdrawn subjects 
42 
10 
Treatments 
42 
10.1 
Treatments administered 
42 
10.2 
Overdose 
43 
10.3 
Blinding 
43 
10.4 
Method of assigning subjects to treatment groups 
43 
10.5 
Selection and timing of dose for each subject 
43 
10.6 
Previous and concomitant treatment 
43 
10.7 
Assessment of compliance 
44 
11 
Dietary and lifestyle restrictions 
44 
11.1 
Contraception requirements 
45 
12 
Procedures and observations 
46 
12.1 
Schedule of procedures 
48 
12.2 
Sampling timepoints and additional tests 
52 
12.3 
Follow-up 
53 
12.4 
Methods 
54 
12.5 
Total volume of blood removed 
59 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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13 
Trial materials 
59 
13.1 
Identity of test product(s) 
59 
13.2 
Packaging and labelling 
60 
13.3 
Storage and accountability of IMP 
60 
13.4 
Non-investigational medicinal product 
60 
13.5 
Other trial supplies 
60 
14 
Adverse events 
61 
14.1 
Definitions of adverse events 
61 
14.2 
Procedures for recording adverse events 
62 
14.3 
Procedures for dealing with serious adverse events 
63 
14.4 
Procedures for handling withdrawals due to adverse events 
64 
14.5 
Procedures for reporting pregnancies 
64 
15 
Data management and quality assurance 
65 
16 
Statistical methods 
65 
16.1 
Pharmacokinetic methods 
65 
16.1.1  Plasma Parameters 
66 
16.2 
Statistical methods 
67 
16.2.1  Planned analyses 
67 
16.2.2  Statistical hypotheses 
67 
16.2.3  Analysis populations 
68 
16.2.4  General considerations for data analyses 
68 
16.2.5  Study population analyses 
69 
16.2.5.1 Disposition of subjects 
69 
16.2.5.2 Demographic and baseline characteristics 
69 
16.2.5.3 Treatment compliance 
69 
16.2.6  Safety data analyses 
69 
16.2.6.1 Adverse events 
69 
16.2.6.2 Clinical laboratory evaluations 
70 
16.2.6.3 Other safety measures 
70 
16.2.7  PET data analyses 
70 
16.2.8  Pharmacokinetic data analyses 
71 
16.2.9  Pharmacodynamic data analyses 
71 
16.3 
Determination of sample size 
72 
17 
Ethical and regulatory requirements 
72 
18 
Trial documentation 
73 
18.1 
Protocol amendments 
73 
18.2 
Case report forms 
74 
18.3 
Reporting of results 
74 
19 
Obligations of the sponsor and investigator 
74 
19.1 
Monitoring, auditing, and inspection 
74 
19.2 
Compensation of volunteers 
75 

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19.3 
Confidentiality 
75 
19.4 
Publication 
75 
19.5 
Archiving 
75 
20 
Premature termination of the trial 
76 
21 
References 
77 
3.1 
Table of Figures 
Figure 1 
Schematic of the study design (PBMC-only subjects) ...................................... 35 
Figure 2 
Schematic of the study design (PET subjects) .................................................. 35 
3.2 
Table of Tables 
Table 1: 
Selected PK parameters after single and repeated ASN51 doses in the first-in- 
human study ASN51-101 .................................................................................. 22 
Table 2: 
Expected maximal radioactive exposure of each subject .................................. 29 
Table 3: 
Acceptable deviation times ............................................................................... 52 
Table 4: 
Laboratory safety tests ...................................................................................... 55 
Table 5: 
Vital signs ranges .............................................................................................. 57 
Table 6: 
ECG ranges ....................................................................................................... 58 
Table 7: 
Planned blood volume (PBMC-only subjects) .................................................. 59 
Table 8: 
Planned blood volume (PET subjects) .............................................................. 59 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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4 
List of abbreviations 
AChE 
acetylcholinesterase 
AD 
Alzheimer’s disease 
AE 
adverse event 
ALT 
alanine aminotransferase 
ANOVA 
analysis of variance 
ARSAC 
Administration of Radioactive Substances Advisory Committee 
AST 
aspartate aminotransferase 
%AUCextrap 
percentage of AUC that was extrapolated 
AUC 
area under the concentration–time curve 
AUC24 
AUC during the first 24 h after dosing 
AUCinf 
AUC extrapolated to infinite time 
AUClast 
AUC to last measurable concentration 
AUCtau 
AUC during the dosing interval 
BLQ 
below the limit of quantification 
BMI 
Body Mass Index 
BSA-CF 
body surface area conversion factor 
CI 
confidence interval 
Clast 
last measurable plasma concentration 
CLss/F 
clearance/fraction of dose absorbed at steady state 
Cmax 
maximum plasma concentration 
Cmin 
minimum measured concentration 
CNS 
central nervous system 
COVID-19 
Coronavirus disease 2019 
CRF 
case report form 
C -SSRS 
Columbia-Suicide Severity Rating Scale 
CT 
computed tomography 
CTA 
clinical trial authorisation 
CYP 
cytochrome P450 
CV 
coefficient of variation 
D 
decreased by more than predetermined amount 
DRF 
dose-range finding (studies) 
DDS 
Drug Development Solutions 
ECG 
electrocardiogram 
EDTA 
ethylenediaminetetraacetic acid 
FDA 
United States Food and Drug Administration 
FIH 
first-in-human 
FSH 
follicle-stimulating hormone 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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g 
gram(s) 
g 
G force 
GCP 
Good Clinical Practice 
GLP 
Good Laboratory Practice 
GMP 
Good Manufacturing Practice 
GP 
General Practitioner 
h 
hour(s) 
Hb 
haemoglobin 
hERG 
human Ether-à-go-go-Related Gene 
HIV 
human immunodeficiency virus 
HMR 
Hammersmith Medicines Research 
IB 
investigator’s brochure 
ICF 
information and consent form 
ICH 
International Council for Harmonisation of Technical 
Requirements for Registration of Pharmaceuticals for Human Use 
ICRP 
International Committee for Radiation Protection 
IMP 
investigational medicinal product 
INR 
international normalised ratio 
IUD 
intrauterine device 
IV 
intravenous 
kg 
kilogram(s) 
λz 
terminal rate constant 
LIMS 
laboratory information management system 
LSM 
least square means 
MBq 
megabecquerel 
MCH 
mean corpuscular haemoglobin 
MCHC 
mean corpuscular haemoglobin concentration 
MCV 
mean corpuscular volume 
MedDRA 
Medical Dictionary for Regulatory Activities 
mg 
milligram 
MHRA 
Medicines and Healthcare Products Regulatory Agency 
MIA(IMP) 
manufacturing authorisation for investigational medicinal 
products 
min 
minute(s) 
mm Hg 
millimetres of mercury 
MRI 
magnetic resonance imaging 
mSv 
millisievert 
MTD 
maximum tolerated dose 
NFT 
neurofibrillary tangle 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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NMDA 
N-methyl-D-aspartate 
NOAEL 
no observed adverse effect level 
O-GlcNAc 
O-linked-N-acetylglucosamine 
O-GlcNAcase 
O-linked-N-acetylglucosaminidase or OGA 
PBMC 
peripheral blood mononuclear cell 
PD 
pharmacodynamic(s) 
PET 
positron emission tomography 
PK 
pharmacokinetic(s) 
PSP 
Progressive Supranuclear Palsy 
QA 
quality assurance 
QD 
once-daily 
QTc 
QT interval corrected for pulse rate 
QTcF 
QT interval corrected according to Fridericia’s formula 
RBC 
red blood cells 
REC 
research ethics committee 
RES 
Research Ethics Service 
RO 
receptor occupancy 
SAE 
serious adverse event 
SARS-CoV-2 
severe acute respiratory syndrome-related coronavirus 2 
SD 
standard deviation 
SOP(s) 
standard operating procedure(s) 
SRG 
Safety Review Group 
SUSAR 
Suspected Unexpected Serious Adverse Reaction 
t½ 
terminal elimination half-life 
TEAE 
treatment-emergent adverse event 
tlast 
time of last measurable concentration 
tmax 
time of maximum plasma concentration 
TOPS 
The Overvolunteering Prevention System 
UK 
United Kingdom 
ULN 
upper limit of normal 
US 
United States of America 
WBC 
white blood cells 
WHO 
World Health Organization 
VT 
volume of distribution 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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5 
Trial personnel 
 
Chief investigator 
 MBBS JCPTGP MPhil 
HMR 
Tel: 
 
Email:
 
Principal investigator 
(Invicro) 
 BSc MBBCh FCPsych SA 
Invicro 
Tel: 
Email: 
HMR emergency contact 
On-call physician 
Tel: +44(0)793 0323244 
Statistician 
BSc MSc 
 BSc MSc 
HMR 
Sponsor’s representative 
 MD 
Asceneuron S.A 
Tel: 
Email: 
 
Sponsor’s primary medical 
officer (European Union) 
 
 
Sponsor’s secondary medical 
officer (United States) 
MD MSc PhD 
Asceneuron S.A. 
Tel: 
Email: 
MD 
Asceneuron S.A. 
Tel: 
Email:
Monitor 
Niche Science & Technology Ltd 
Unit 26, Falstaff House 
Bardolph Road 
Richmond-upon-Thames 
London, TW9 2LH 
Tel: 
Email: 
Laboratory safety tests 
The HMR Analytical Laboratory 
HMR 
Assays of IMP concentration 
DDS 
Newmarket Road, Fordham 
Cambridgeshire 
CB7 5WW 
Tel: 
Email: 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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Derivation of 
pharmacokinetic (PK) 
parameters 
 BSc 
HMR 
Pharmacovigilance 
 MD MSc PhD 
Asceneuron S.A. 
EPFL Innovation Park, Bâtiment B 
1015 Lausanne 
Switzerland, CH-1015 
Tel: 
Email:
 
SAE reporting: 
Email: 
 
Mobile: 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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6 
Introduction 
6.1 
Background 

PET study of repeated ASN51 in healthy volunteers 
Trial Codes: 22-012 and ASN51-103 
Protocol Version 2, dated 23 January 2023 
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6.2 
Review of investigational medicinal product 
Asceneuron SA is developing ASN51, a new chemical entity
 
 
 
6.2.1 
Non-clinical studies 
Several non-clinical studies of ASN51 have been conducted to date, as described 
below. 
Non-clinical pharmacology 
Further information about non-clinical pharmacology studies of ASN51 is available 
in the IB9. 
Pharmacokinetics 
PK studies of ASN51 were done in rats, dogs, and monkeys. Additional information 
is available from in vitro studies on plasma protein binding and metabolism in liver 
microsomes and hepatocytes of various species, cytochrome P450 (CYP)-profiling 
(inhibition and induction) and from toxicokinetic studies in rats and dogs. 
Further information about the non-clinical PK of ASN51 is available in the IB9. 
Toxicology 

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Further information about non-clinical studies of ASN51 is available in the IB9. 
 
6.2.2 
Clinical studies 
To date, ASN51 has been assessed 2 clinical studies in healthy subjects: a 
first-in-human (FIH) single- and multiple-ascending dose study (ASN51-101), and 
an adaptive-design positron emission tomography (PET) study (ASN51-102). 
There were no deaths or serious adverse events (SAEs) in either study. Overall, 
ASN51 was safe and well tolerated. All treatment-emergent adverse events (TEAEs) 
were mild or moderate in severity. All AEs were reversible. There were no 

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clinically significant laboratory, vital sign, electrocardiogram (ECG), cardiac 
telemetry, or physical or neurological examination findings in either study, and no 
positive Columbia-Suicide Severity Rating Scale (C-SSRS) results. 
Further information about clinical studies of ASN51 is available in the IB9. 
6.2.2.1 Study ASN51-101 
 
 

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Further information is available in the IB9. 
6.2.2.2 Study ASN51-102 
 

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Further information is available in the IB9. 
 
6.3 
Review of non-investigational medicinal product 
Further details are included in the [18F]-IMA601 non-IMP dossier (non-IMPD)28. 
 
6.4 
Rationale for the trial 

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The results of this study will be used to select doses for subsequent studies in 
patients. 
 
6.5 
Participant input into trial design 
This is a phase 1, exploratory study in healthy volunteers, with no anticipated 
therapeutic benefit to the participants; involvement of patients, service users or 
members of the public in the design of the trial is not appropriate. 
 
6.6 
Rationale for choice of doses 

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6.7 
Assessment and management of risk 
Risk associated with ASN51 (all subjects) 
Other safety considerations (all subjects) 
Any other safety risk to study participants is mitigated by the following 
considerations. 
• Subjects will be monitored frequently throughout the study for safety and 
tolerability, including vital signs, 12-lead safety ECG, physical and neurological 
examination, laboratory safety tests, and C-SSRS. The safety monitoring 
practices employed by this protocol are adequate to protect the subjects’ safety 
and should detect all expected TEAEs. 
• HMR maintains its own resuscitation team (SS329) to deal with medical 
emergencies, including anaphylaxis and cardiac arrest. The team will be on duty 
continuously, until at least 24 h after each dose. 
• Any risks are adequately mitigated by safety assessments, and by the medical 
cover provided by the investigator site, and by appropriate investigational 
medicinal product (IMP) manufacture, according to Good Manufacturing Practice 
(GMP). 
• Subjects will stay on the ward from the day before first study drug administration 
until 6 days (ie 3 half-lives) after the last study drug administration. 
There will be no direct health benefit for study participants from receipt of study 
medication. An indirect health benefit to the healthy subjects enrolled in this trial is 
the free medical examination received at screening and during the study. 
Overall, the risk benefit balance of the present study is considered to be acceptable. 
Risk of testicular toxicity (all subjects) 

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Risk associated with the imaging techniques (PET subjects only) 
In this study, each subject will be exposed to radiation from PET and computed 
tomography (CT) scans (for attenuation correction). To mitigate this risk, the study 
will exclude subjects who have had previous exposure to ionising radiation such that, 
their exposure would be > 10mSv for the previous year (see exclusion criterion 35). 
The maximal radiation exposure for each subject over the whole study is presented in 
Table 2. 

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Table 2: 
Expected maximal radioactive exposure of each subject 
 
Assessment 
Number 
of scans 
Activity from 
PET tracer 
(MBq) 
Effective 
dose per 
scan 
Total 
exposure 
(mSv) 
 
(mSv) 
 
 
PET emission scan 
3 
100 
2.05 
6.15 
Low-dose CT scan 
3 
– 
0.28 
0.84 
Total 
6.99 
 
A total exposure of 6.99 mSv falls into category IIb (upper limit 10 mSv) of the 
guidance published by the International Committee for Radiation Protection (ICRP). 
There is no dose limit for research purposes in the UK. However, as in many 
member states in the EU, the UK follows the ICRP 62 guidance that provides a 
guideline of 10 mSv (or less) per study where research subjects are not expected to 
benefit personally12. 
Magnetic resonance imaging (MRI) to delineate brain anatomy will be done in this 
study to aid PET image analysis. There are no known risks to subjects associated 
with MRI scanning, provided that they have no contraindications to MRI as listed in 
the exclusion criteria (section 9.3, exclusion criterion 36). Potential risks associated 
with metallic implants will be mitigated by administration of a questionnaire and 
careful screening. 
Risk associated with arterial cannulation (PET subjects only) 
Before the PET-CT scan, subjects will have a cannula inserted into the radial artery 
by qualified staff using aseptic technique under local anaesthesia. That insertion may 
be uncomfortable, cause minor local bleeding and bruising, and can rarely lead to 
complications (eg, a blood clot could form around the cannula). Most people have 
no after-effects of cannulation. However, very occasionally, it may cause a small 
scar. Very rarely, more serious complications can occur, although these usually 
occur when the radial artery is cannulated in sick people for therapeutic purposes, 
rather than in healthy subjects for research purposes. 
Assessment of the patency of collateral arterial circulation will be assessed at 
screening and at each imaging session using Allen’s test, to minimise the risk of 
complications. 
Use of healthy young male volunteers (PET subjects only) 
Despite the potential risk of testicular toxicity, radiation exposure, and repeated 
arterial blood sampling described above, healthy young volunteers are the most 
suitable population for the present study, because they: 

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• 
have no confounding pathology (eg vascular disease), or concomitant medicine 
use (eg aspirin), that would contraindicate arterial cannulation, and are better 
able to tolerate the procedure. 
• 
are better suited to tolerate repeated blood draws for PK and PBMC analyses (to 
a maximum total of 537 mL; see section 12.5). 
• 
are better able to tolerate repeated PET scans. 
The intended blood volume to be taken from PET subjects in this study (537 mL, 
plus a maximum intended overage of 30 mL unless medically indicated that further 
samples are needed for safety reasons) is slightly higher than that of a standard blood 
donation visit. However, the total volume of blood will be taken over approximately 
4 weeks. To ensure the safety of the subjects, volunteers will be screened to confirm 
that they have no haematological abnormalities, and will be excluded if they lose or 
donate more than 400 mL blood during the 3 months before the trial. Male 
volunteers are at lower risk of anaemia, and must agree not to donate blood or blood 
products for up to 3 months after their final visit. Volunteers will be closely 
monitored and if the investigator (or delegate) has concerns about the results of 
regular safety blood tests, no further samples will be taken until it is considered 
clinically safe to do so. 
 
6.8 
Conducting the trial during the COVID-19 pandemic 
The investigator and sponsor have reviewed the risks of conducting the trial during 
the current Coronavirus disease 2019 (COVID-19) pandemic. Our priority is the 
safety of trial subjects and staff, but we also have an ethical duty to preserve the 
scientific integrity of the trial as far as possible. 
ASN51 is unlikely to increase the risk of contracting COVID-19 infection, or to 
worsen the severity of an infection. ASN51 has no immunosuppressive effect, and is 
not associated with cough, pyrexia, or anosmia, which would require isolation of 
subjects. 
ASN51 is unlikely to affect the efficacy of a vaccine against severe acute respiratory 
syndrome-related coronavirus 2 (SARS-CoV-2). However, to delineate AEs caused 
by ASN51 or a vaccine, vaccines will be prohibited from 7 days before screening 
until the follow-up visit. That’s ethically acceptable owing to the short duration of 
participation for each subject. 
This clinical trial will be done in accordance with HMR’s COVID-19 risk mitigation 
policy (RMP), which documents HMR’s COVID-19 virus testing strategy for 
volunteers and staff, social distancing measures, and management of COVID-19-like 
symptoms. HMR’s RMP was first notified to the MHRA and HRA on 22 May 2020 
and applies across all HMR’s trials. The mitigation measures specified in the HMR 
COVID-19 RMP are deemed adequate for this trial. Any deviations from the RMP 
will be documented in a separate COVID-19 trial-specific risk assessment, prepared 

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by the investigator. Any deviations from the protocol that result from the COVID-19 
pandemic, and COVID-19 related AEs or SAEs, will be documented. 
Taking the above factors into account, and the proposed mitigation, we believe that it 
is medically and ethically acceptable to proceed with the trial during the current 
COVID-19 pandemic. 
 
7 
Objectives and endpoints 
 
7.1 
Objectives 
 
7.1.1 
Primary objectives: 
• To assess the pharmacodynamic (PD) response in peripheral blood mononuclear 
cells (PBMCs) following single and repeated oral doses of ASN51 in healthy 
subjects 
• To assess brain O-GlcNAcase occupancy using [18F]-IMA601 positron emission 
tomography (PET), following repeated oral doses of ASN51 in healthy subjects 
 
7.1.2 
Secondary objectives: 
• To assess the safety and tolerability of repeated oral doses of ASN51 in healthy 
subjects 
• To assess the relationship between the plasma concentration of ASN51 and the 
time-course of brain O-GlcNAcase occupancy using [18F]-IMA601 PET, 
following repeated oral doses of ASN51 in healthy subjects 
• To assess the PK of repeated doses of ASN51 in healthy subjects 
• To assess the trough O-GlcNAcase occupancy of ASN51 after repeated doses in 
healthy subjects 
• To determine the effect of food on the PD response in PBMCs following repeated 
ASN51 dosing in healthy subjects 
 
7.2 
Endpoints 
 
7.2.1 
Primary endpoints: 
PD: 
 
• 
O-GlcNAcylation of PBMCs 
• 
[18F]-IMA601 regional total volume of distribution (VT) at each brain scan 

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7.2.2 
Secondary endpoints: 
Safety and tolerability: 
• vital signs (blood pressure, pulse rate, tympanic temperature, and respiratory 
rate), 12-lead safety ECG, physical and neurological examination, laboratory 
safety tests (haematology, clinical chemistry, coagulation, and urinalysis), 
C-SSRS, and adverse events (AEs) 
PK: 
• plasma concentration of ASN51 at the time of each postdose PET scan 
• PK parameters including Cmax, Cmax/Dose, tmax, t½, λZ, AUCtau, AUClast, AUCinf, 
AUCinf /Dose, %AUCextrap, CLSS/F, VZ/F, Ctrough, Rac(Cmax), Rac(AUC) 
PD: 
• 
O-GlcNAcylation of PBMCs with or without prior feeding 
• 
Trough [18F]-IMA601 VT 
PK/PD: 
• relationship between ASN51 plasma concentration, PBMC target engagement, 
and brain RO over time 
 
8 
Overall trial design 
 
8.1 
Trial design 
 
8.1.1 
Trial design 
This is a phase 1, open-label, dose escalation, PET study to investigate the brain 
occupancy of O-GlcNAcase, and the PD response in PBMCs, after repeated doses of 
ASN51 in healthy subjects. 
Enrolment of up to 12 healthy subjects is planned, in up to 2 groups (Groups 1 
and 2). Each group will consist of up to 6 subjects. 
All subjects will receive once-daily (QD) doses of ASN51, by mouth, for 
14 days: Group 1 will receive 
 ASN51 QD and Group 2 will receive 
 
ASN51 QD. Group 2 will proceed only if the safety and tolerability of the previous 
dose level are acceptable, and the plasma concentrations of ASN51 are predicted to 
remain below the toxicokinetic limit, as determined by the Safety Review Group 
(SRG; see section 8.5). 
On Day 11, to evaluate the effect of food on PBMC response, subjects will receive 
ASN51 in the fed state following a United States Food and Drug Administration 
(FDA) high-fat breakfast29. Subject fasting requirements are further detailed in 
section 11. 

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In each group, 2 subjects will have a PBMC-only study design (section 8.1.2) and 
4 will have a PBMC and PET scanning study design (section 8.1.3). 
Schematic diagrams of each study design are in section 8.2. 
 
8.1.2 
PBMC-only subjects 
2 subjects in each of Groups 1 and 2 will not have PET scans during the study. They 
will: 
• be screened within 28 days before their first dose of trial medication. 
• be resident on ward from 1 day before their first dose (Day –1) until 6 days after 
their final dose (Day 20). 
• return for a follow-up visit 9–11 days after their final dose of trial medication 
(Days 23–25). 
 
8.1.3 
PET subjects 
4 subjects in each of Groups 1 and 2 will have PET scans during the study. PET 
subjects will: 
• be screened within 21 days before imaging session 1 (see below). 
• be resident on ward from 1 day before their first dose (Day –1) until 6 days after 
their final dose (Day 20); and have imaging sessions as described below. 
• return for a follow-up visit 9–11 days after their final dose of trial medication 
(Day 23 ± 2 days), or 2–4 days after imaging session 3 (see below), whichever is 
later. 
PET subjects will have up to 3 imaging sessions, as follows. 
• Imaging session 1. Subjects will have a baseline PET scan between Day –7 and 
Day –3. Subjects will be admitted to the ward the day before their baseline PET 
scan, and be discharged the following day after their scan. 
• Imaging session 2. Subjects will have an on-treatment PET scan at about 5 h 
postdose on Day 1. 
• Imaging session 3. Subjects will have an on-treatment PET scan at 3–9 days 
after their final dose of ASN51: 
• 3 subjects per group on Day 17 
• 1 subject on Day 22 (± 1 day) (Group 1 only) 
• 1 subject on Day 23 (± 1 day) (Group 2 only) 
The timing of on-treatment PET scans (imaging sessions 2 and 3) may be altered 
based on emerging data or study logistical requirements. 

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Subjects will receive an intravenous (IV) dose of the radiolabelled tracer, 
[18F]-IMA601, at the start of each PET scan. 
Arterial blood sampling will be done during each PET scan to quantify the parent 
tracer-related radioactivity over the course of the PET scan, and to establish a tracer 
metabolite-corrected plasma input function. The total arterial blood volume required 
for each tracer injection will not exceed 120 mL. Arterial cannulation and arterial 
blood sampling may be reduced or removed if analysis of PET data from previous 
subjects indicates that non-invasive analysis of the PET scan data can be done. If a 
non-invasive analysis is not possible, the use of an arterial cannula with each PET 
scan will continue through the study. 
In the case of a technical failure (such as unsuccessful tracer synthesis), subjects may 
be asked to attend an additional on-treatment imaging session as described in 
section 12.2. However, no subject will have more than 3 PET scans and 3 doses of 
[18F]-IMA601 during the study. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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8.2 
Study flow chart 
Figure 1 
Schematic of the study design (PBMC-only subjects) 
 
* The follow-up visit will be 9–11 days after a subject’s last dose (Days 23–25). 
Subject fasting requirements are detailed in section 11 
 
 
Figure 2 
Schematic of the study design (PET subjects) 
 
* 1 subject in Group 1 will have imaging session 3 on Day 22, and 1 subject in Group 2 will have imaging session 3 on Day 23. 
† The follow-up visit will be 9–11 days after a subject’s last dose (Days 23–25) or 2–4 days after imaging session 3, whichever is later. 
Subject fasting requirements are detailed in section 11 
 
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8.3 
Definition of the end of the trial 
The end of the trial is defined as the final follow-up visit by the last subject. If the 
trial is terminated prematurely, the trial ends when the sponsor notifies the 
investigator in writing that the trial has finished, or when the last subject attends the 
final follow-up visit, whichever is later. 
 
8.4 
Stopping criteria 
 
8.4.1 
Trial stopping criteria 
The trial will be stopped if either of the following occurs: 
• 1 or more SAEs considered to be at least possibly related to study treatment; or 
• 2 or more severe or clinically significant AEs considered to be at least possibly 
related to study treatment at any dose level. 
If, after an internal safety review, it is appropriate to restart the trial, a substantial 
amendment will be submitted to the MHRA and research ethics committee (REC). 
The trial will not restart until the amendment has been approved by the MHRA and 
REC. 
 
8.5 
Criteria for proceeding to Group 2 
 
8.5.1 
Review of data by the Safety Review Group 
Before proceeding to Group 2, the SRG will review the safety, tolerability and PK 
data from Group 1. The SRG will include (as a minimum) the principal investigator 
(or medically qualified delegate) and the sponsor’s medically qualified 
representatives (Primary Medical Officer and the Head of Translational Medicine [or 
delegate]). Each dose decision will be made and documented in line with HMR 
SOPs. All data used to support dose selection will be quality checked. 
The SRG will review safety, tolerability, and PK data up to 6 days after the final 
dose (Day 20) from all subjects dosed in Group 1. In the event of a subject 
withdrawal prior to Day 20, all available safety, tolerability, and PK data from that 
subject will be included in the SRG review. The review will include (as a minimum) 
data from at least 4 evaluable subjects. An evaluable subject is one who completes 
dosing and has undergone procedures until 6 days after final dosing (Day 20), and 
had no major protocol deviations. 
The data reviewed will include, as a minimum: 
• AEs and SAEs, including description, frequency, intensity, onset, duration, and 
relationship to treatment 
• vital signs 

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and to participate in, and comply with the requirements of, the entire trial (ie be 
fluent in the local language). 
7. Willingness to give written consent to participate after reading the ICF, and after 
having the opportunity to discuss the trial with the investigator or their delegate. 
8. Agree to follow the contraception requirements of the trial as described in 
section 11. 
9. Agree not to donate blood or blood products during the study and for up to 
3 months after the final visit. 
10. Willingness to give written consent to have data entered into The 
Overvolunteering Prevention System (TOPS). 
11. Agree not to post any personal medical data or information related to the study 
on any website or social media site (eg Facebook, Twitter, etc) until the trial has 
ended. 
 
9.3 
Exclusion criteria 
The exclusion criteria detailed below should be used to determine eligibility at 
screening only (unless otherwise specified). 
1. Clinically relevant abnormal medical history, physical or neurological findings, 
ECG, or laboratory values at screening, or before the baseline PET scan (PET 
subjects only), or before the first dose of trial medication, that could interfere 
with the objectives of the trial or the safety of the volunteer. 
2. History or presence of acute or chronic illness, or clinically-significant medical 
abnormality, sufficient to invalidate the volunteer’s participation in the trial or 
make it unnecessarily hazardous. 
3. History or presence of any disease, medical condition, or surgery (eg stomach 
bypass), likely to affect the absorption, distribution, metabolism, or excretion of 
medicines. Subjects with a history of cholecystectomy should be excluded. 
4. Impaired endocrine, thyroid, hepatic, respiratory or renal function, diabetes 
mellitus, coronary heart disease, or history of any psychotic mental illness. 
5. Presence or history of severe or clinically significant adverse reaction to any 
drug; or a history of sensitivity to ASN51 (all subjects) or the PET radioligand, 
[18F]-IMA601 (PET subjects only), or any components of those medications. 
6. History of psychiatric disorders, including substance use disorders, according to 
the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) 
criteria. 
7. Any diagnosis of intellectual disability (intellectual developmental disorder) or 
mental retardation. 

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8. History of epilepsy or seizures, other than a single instance of benign febrile 
convulsion in childhood. 
9. History of clinically significant head trauma, including closed head injury with 
loss of consciousness. 
10. History of symptomatic orthostatic hypotension (ie postural syncope). 
11. History of neuroleptic malignant syndrome. 
12. History of chronic urinary tract infections. 
13. Significant suicide risk as assessed by C-SSRS. 
14. Frequent use (≥ 3 days a week) of any nicotine-containing product (eg cigar, 
cigarette, or snuff; or any product used for smoking cessation [eg nicotine gum 
or plasters]) within 3 months before the baseline PET scan (PET subjects) or first 
dose of trial medication (PBMC subjects). 
Use of any nicotine-containing product is prohibited from within 1 week of the 
baseline PET scan (PET subjects) or the first dose of trial medication (PBMC 
subjects). 
15. Presence or history of drug or alcohol abuse, or intake of more than 14 units of 
alcohol weekly, within the 12 months before the baseline PET scan (PET 
subjects) or the first dose of trial medication (PBMC subjects). 
16. Evidence of drug abuse on urine testing. 
17. Regular consumption (eg ≥ 4 days/week) of excessive quantities of 
xanthine-containing beverages (eg ≥ 5 cups of coffee or the equivalent per day) 
within 30 days before screening, or between screening and the baseline PET scan 
(PET subjects) or the first dose of trial medication (PBMC-only subjects). 
18. Receipt of an investigational product (including prescription medicines) or device 
within 3 months* before the baseline PET scan (PET subjects) or the first dose of 
trial medication (PBMC subjects); in the follow-up period of another clinical trial 
at the time of screening for this study. 
*(or 5 half-lives, or twice the duration of the biological effect, of the 
investigational product – whichever is longer). 
19. Use of the following: 
• a prescription medicine during the 28 days* before the baseline PET scan 
(PET subjects) or the first dose of trial medication (PBMC subjects); 
• an over-the-counter medicine, including vitamins, herbal, or dietary 
supplements (including St John’s Wort), with the exception of acetaminophen 
(paracetamol), during the 7 days* (or 28 days if the medicine is a potential 
hepatic enzyme inducer) before the baseline PET scan (PET subjects) or the 
first dose of trial medication (PBMC subjects). 

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*(or 5 half-lives of the medicine – whichever is longer). 
20. Loss of more than 400 mL blood during the 3 months before the trial, eg as a 
blood donor. 
21. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels 
≥ 1.5 × upper limit of normal (ULN) at screening, or before the baseline PET 
scan (PET subjects), or before the first dose of trial medication. A repeat is 
allowed on one occasion for determination of eligibility. 
22. QT value, measured at screening, or before the baseline PET scan (PET subjects) 
or first dose of trial medication (PBMC subjects), greater than 450 msec (men) or 
470 msec (women), using Fridericia’s formula (QTcF) for correction. 
Triplicate measurements will be made, and a mean QTcF value higher than those 
stated will lead to exclusion. A repeat (in triplicate) is allowed on one occasion 
for determination of eligibility. 
23. Family history of long QT syndrome or sudden death. 
24. Clinically significant ECG abnormalities, as determined by the investigator or 
medical monitor, including (but not limited to): 
• abnormal ST-T-wave morphology or left ventricular hypertrophy. 
• PR (PQ) interval shortening < 120 msec (PR < 120 msec but > 110 msec is 
acceptable if there is no evidence of ventricular pre-excitation). 
• PR (PQ) interval prolongation (> 220 msec), intermittent second- 
(Wenckebach block while asleep or in deep rest is not exclusionary) or 
third-degree atrioventricular (AV) block. 
• Persistent or intermittent complete bundle branch block, incomplete bundle 
branch block, or intraventricular conduction delay with QRS > 120 msec. 
25. Blood pressure and pulse rate in seated position at the screening examination 
outside the ranges: blood pressure 90–140 mm Hg systolic, 40–90 mm Hg 
diastolic; pulse rate 40_100 beats/min. The average of triplicate measurements 
(each 5 min apart) will be used to assess eligibility. 
Repeat measurements are permitted if values are borderline (ie values that are 
within 5 mm Hg for blood pressure or 5 beats/min for pulse rate) or if requested 
by the investigator. Subjects can be included if the repeat value is within range 
or still borderline, but deemed not clinically significant by the investigator. 
26. Significant (> 10%) weight loss or gain within 30 days before the (first) screening 
visit or before the baseline PET scan (PET subjects) or first dose of trial 
medication (PBMC subjects). 
27. Unsatisfactory venous access 
28. Subjects with a COVID-19 vaccination within 2 weeks of screening, or who are 
due to receive a dose of a COVID-19 vaccine while participating in the study. 

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29. Positive test for hepatitis B, hepatitis C or human immunodeficiency virus 
(HIV). 
30. Vegan, or unwilling to eat a high-fat breakfast including eggs and dairy (eg for 
personal or religious reasons). 
31. Employed by, or a first-degree relative of an employee of, Asceneuron S.A. or a 
clinical trial site participating in this study. 
32. Possibility that the volunteer will not cooperate with the requirements of the 
protocol. 
33. Objection by general practitioner (GP) to volunteer entering trial. 
The following exclusion criteria also apply to subjects who will be given PET scans 
during the study. 
34. Significant structural brain abnormality, as determined by MRI. 
35. Significant exposure to ionising radiation as part of research (defined as 
International Commission on Radiological Protection [ICRP]11 category IIb or 
above: no more than 10 mSv in addition to natural background radiation 
including this trial), within the 12 months before the first dose of tracer. 
36. Unsuitable or unwilling to undergo the imaging procedures, as determined by an 
MRI safety questionnaire. Reasons for exclusion include but are not limited 
to: presence of a cardiac pacemaker or other implanted electronic device; 
ferromagnetic metal foreign bodies, intracranial aneurysm clips or other metallic 
objects; non-MRI compatible heart valves; inner ear implants; or a history of 
claustrophobia. 
37. Contraindication for arterial cannulation: Allen’s test indicating potential risk in 
placement of the arterial cannula. 
 
9.4 
Withdrawal of subjects from the trial 
 
9.4.1 
Subject withdrawal 
Subjects are free to withdraw from the trial at any time without giving reasons. 
Furthermore, the investigator may withdraw a subject for reasons such as intolerance 
to trial medication, intercurrent illness, need for medication which is contraindicated, 
significant non-compliance with the requirements of the trial, or withdrawal of 
consent. The investigator will assess the reasons for withdrawal as far as possible 
and will fully record the circumstances and medical details. 
Subjects will be informed before they agree to take part in the trial that, if they 
withdraw or are withdrawn: 
• the investigator will stop collecting information about them; and 
• they can ask the investigator to destroy any identifiable samples taken from them. 

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The investigator will ask withdrawn subjects to consent to a follow-up examination, 
to check that they have come to no harm as a result of taking part in the trial. 
Provided that the subject agrees, they will undergo, at withdrawal from the trial (or 
as soon as possible afterwards), the standard medical examination and laboratory 
tests which they would have undergone had they completed it. The investigator will 
record in the case report form (CRF) the results of the follow-up examination of 
withdrawn subjects, if they give their consent for that. 
 
9.4.2 
Individual subject stopping criteria 
A subject who meets any of the following criteria will receive no further doses. 
• SAE considered related to study treatment. 
• ALT ≥ 3 × ULN. 
• Any condition that, in the judgment of the investigator or sponsor, might place 
the subject at risk or invalidate the trial. 
Subjects who meet the above criteria will be considered discontinued from dosing. 
However, the investigator may ask the subject to continue their participation in the 
study, so they can be monitored for safety, PK and PD, or the investigator may 
withdraw the subject from the trial. 
 
9.4.3 
Replacement of withdrawn subjects 
Withdrawn subjects will be replaced at the discretion of the sponsor and investigator. 
Replacements for withdrawn subjects will receive the treatment intended for the 
withdrawn subject, from the start of the trial. 
For subjects withdrawn because of AEs considered possibly related to study 
treatment (see section 14.2), possible replacement will be discussed by mutual 
agreement between sponsor and investigator. 
 
10 
Treatments 
10.1 
Treatments administered 
All subjects 
All subjects will receive once-daily doses of ASN51 for 14 days (see section 8.1). 
All doses will be given orally, in the fasted or fed state, with about 240 mL of water. 
Extra water can be given if a subject has trouble swallowing the tablets; that will be 
recorded in source documents. 
Fasting requirements are described in section 11. 
PET subjects 

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PET subjects will also receive IV doses of the radiolabelled tracer [18F]-IMA601 
(non-IMP) on up to 3 occasions (1 at each imaging session). 
If one or both on-treatment PET scans need to be rescheduled, eg owing to a 
technical failure, subjects may have additional imaging sessions. However, subjects 
will receive no more than 3 doses of [18F]-IMA601 during the study. 
 
10.2 
Overdose 
Symptoms of overdose of ASN51 are not yet known. In the case of accidental 
overdose, subjects should be treated symptomatically as no specific antidote is 
available. 
 
10.3 
Blinding 
This is an open-label study. 
 
10.4 
Method of assigning subjects to treatment groups 
Subjects will be assigned a screening number at the screening visit. 
After passing all of the screening assessments, subjects will be allocated to a group 
according to their availability and the scheduled trial dates. 
Subjects will be numbered consecutively, from 1001–1006 (Group 1) or 2001–2006 
(Group 2), in the order in which they arrive on the ward and are entered into the trial 
(ie subjects who will have PET scans during the study will be allocated subject 
numbers on the day of imaging session 1; all other subjects will be numbered on 
Day –1). 
Replacements for withdrawn subjects will be given a number equal to that of the 
subject that they replaced plus 100. So, Subject 1001 would be replaced by 
Subject 1101, and Subject 2004 would be replaced by Subject 2104, and so on. 
 
10.5 
Selection and timing of dose for each subject 
The treatments to be administered are described in sections 8.1 and 10.1. Subjects 
will be assigned to treatments as described in section 10.4. 
Doses will be given at the same time each day (± 15 mins from the dosing time on 
Day 1). 
 
10.6 
Previous and concomitant treatment 
Previous treatment restrictions are described in section 9.3. 
During the trial, concomitant medication may be given if the subject’s GP believes it 
to be necessary. In addition, up to 2 g paracetamol (acetaminophen) will be allowed 

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per day for mild analgesia (up to 1 g per dose). Any other concomitant treatment 
will be given only if deemed strictly necessary by the investigator or co-investigator. 
In any case, all concomitant treatments will be reported in the CRF along with their 
daily dosage, duration and reasons for administration. Subjects who have received 
any concomitant treatment may be withdrawn from the trial at the discretion of an 
investigator. 
 
10.7 
Assessment of compliance 
All subjects will be dosed with ASN51 on the research ward under the supervision of 
2 suitably trained members of HMR staff. Mouth checks will be done. 
Subjects who will have PET scans will be dosed with radiolabelled tracer, 
[18F]-IMA601 at Invicro, under the supervision of suitably trained members of staff, 
at least one of whom will be a registered physician or nurse. 
 
11 
Dietary and lifestyle restrictions 
Subjects will abide by HMR house rules while on the ward or at Invicro. 
Subjects will receive their doses of ASN51 in the fed and fasted states, as follows. 
• On Days 1 and 14, subjects will fast (no food or drink other than water) from 
midnight on the evening before dosing, until 4 h after dosing. 
• On Days 2–10, 12, and 13, the study medicine will be given before a standard 
breakfast. 
• On Day 11, subjects will take the study medicine after a high-fat breakfast 
consisting of 2 fried eggs, 2 strips of bacon, 2 slices of toast and butter, 4 ounces 
of hash brown potatoes, and a glass of whole milk. Subjects will start the meal 
approximately 30 min before dosing, and must eat all of it by at least 10 min 
before dosing. 
Other standard meals and drinks will be provided at appropriate times. Because the 
timings of on-treatment PET scans may change, meals for PET subjects may be 
provided at unusual times. 
Other than the water required to take the study medicine, water will not be allowed 
for 2 h before and after dosing (Days 1 and 14 only). 
No food or drink containing Seville oranges or grapefruit, and no smoking or use of 
nicotine-containing products, will be allowed from 7 days before the baseline PET 
scan (PET subjects) or the first dose of trial medication (PBMC subjects) until the 
end of the study. No alcoholic drinks will be allowed 48 h before the baseline PET 
scan (PET subjects) or first dose of trial medication (PBMC subjects), until the end 
of the study. No caffeine- or xanthine-containing products (eg coffee, tea, cola 
drinks and chocolate) will be allowed from 24 h before: the baseline PET scan (PET 
subjects) or the first dose of trial medication (PBMC subjects) until discharge from 

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the ward; imaging session 3 (if applicable, PET subjects); and the follow-up visit (all 
subjects). Subjects should be advised to avoid eating food containing poppy seeds 
from screening until the end of the study, because that can cause a positive drugs of 
abuse test result. 
No strenuous exercise will be allowed for 7 days before the baseline PET scan (PET 
subjects) or the first dose of trial medication (PBMC subjects) until the end of the 
study. 
Subjects must not sunbathe or use a sunbed during the study. 
Subjects must use a reliable method of contraception, as follows. 
11.1 
Contraception requirements 
Men 
Male subjects must not plan to father a child, or donate sperm, during the trial (from 
1 day before the baseline PET scan [PET subjects] or first dose of trial medication 
[PBMC subjects] until 3 months after their follow-up visit). 
Male subjects must not have sex without using a condom, if their partner is a woman 
of childbearing potential, from 1 day before the baseline PET scan (PET subjects) or 
first dose of trial medication (PBMC subjects) until 90 days after their last dose of 
trial medication. Also, their female partners of childbearing potential must use an 
additional method of contraception (such as an oral contraceptive, cap, or diaphragm 
[used with spermicide], intrauterine device [IUD], or tubal ligation). Subjects do not 
need to use any contraception if: they’ve had a vasectomy, and surgical success has 
been confirmed by medical assessment, or if their partner is not of childbearing 
potential. Partners who are not of childbearing potential are defined as: men; post- 
menopausal women (no menstrual periods for at least 12 months, and FSH at 
screening confirms post-menopausal status); or women who have no uterus, ovaries, 
or fallopian tubes. 
Subjects who practise true abstinence or who only have same-sex relationships need 
not use contraception, provided it is in line with their preferred and usual lifestyle 
(note: periodic abstinence (eg calendar, ovulation, symptothermal, and 
post-ovulation methods) and withdrawal are not acceptable methods of 
contraception). Should any such subject stop practising true abstinence, they must 
use contraception as described above. 
Women 
Women of non-childbearing potential may take part in the trial as PBMC-only 
subjects. A woman is considered to be of non-childbearing potential if she meets one 
of the criteria in inclusion criterion 1. 

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12 
Procedures and observations 
Only subjects who meet all the inclusion and no exclusion criteria will be eligible for 
enrolment into the trial (see section 9). Each subject will be allocated a unique trial 
number (see section 10.4). 
The schedule of procedures is in section 12.1. 
Additional timepoints may be introduced, and changes to timepoints may be made, in 
accordance with section 12.2. 
The following assessments will be made. 
Pharmacodynamics 
Blood samples for PBMC assays will be taken before and frequently during dosing 
(up to 144 h [6 days] after the last dose). Trough samples will be taken before study 
drug administration. 
Occupancy of O-GlcNAcase by ASN51 will be assessed by PET imaging using the 
radioligand [18F]-IMA601 (PET subjects only). 
Blood samples will be taken during each PET scan for arterial input function and 
radio metabolite analysis (PET subjects only). 
Safety and tolerability: 
Laboratory assessments (routine haematology, clinical chemistry, coagulation, and 
urinalysis), physical and neurological examinations, 12-lead ECGs, and vital signs 
(blood pressure, pulse rate, respiratory rate, and tympanic temperature) and C-SSRS 
will be done frequently until the subject’s last visit. AEs will be recorded from 
screening until the subject’s last visit. 
Laboratory safety variables to be assessed during the study are in Table 4. 
From screening until the follow-up visit, AEs and concomitant medication will be 
documented as they are reported by the subjects. Subjects will be questioned about 
AEs on admission to the ward, when procedures are done, and when they return to 
the ward for outpatient visits/at follow-up. 
Pharmacokinetics 
Blood samples for assay of ASN51 will be taken before and frequently during dosing 
(up to 144 h [5 days] after the last dose), and at follow-up. Trough samples will be 
taken before study drug administration. 
PET subjects only: for subjects having imaging session 3 on Day 22 or 23, 
additional PK samples will be taken approximately 2 h before and after the PET 
scan. 
Other 
Structural MRI scans will be done during the screening period (PET subjects only). 

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7. 
PET subjects only – subjects will complete an MRI questionnaire before the MRI scan, to exclude unsuitable subjects. Questionnaires will be done at Screening Visit 1 
with the screening physician, and at Screening Visit 2 at Invicro with the radiographer. Screening MRI will be done once all other screening results are available. If a 
subject is being re-screened (ie missed cohort) and there is already a recent MRI scan available within 3 months from their first screening period (ie if subjects were a 
reserve subject for a previous group but were not dosed and are no longer within the screening window) they do not need a repeat MRI scan. 
8. 
Subjects will have several cannulas, as below. 
• All subjects – on Days 1 and 14, subjects will have a cannula inserted for PK sampling. 
• PET subjects only – at each imaging session, subjects will have an additional cannula inserted for administration of the radioligand [18F]-IMA601. 
9. 
PET subjects only – once per imaging session 
10. PET subjects only – [18F]-IMA601 administration at the start of each PET scan. 
11. Subjects will receive once-daily oral doses of ASN51 on Days 1–14 in the fasted and fed state (fasting requirements and water restrictions are in section 11). Doses will 
be given at approximately the same time each day (± 15 min from dosing time on Day 1). 
12. All subjects will be given an FDA high-fat breakfast before dosing on Day 11; see section 11. 
13. Full physical and neurological examinations will be done at screening and at the follow-up visit. Brief (symptom-directed) physical examinations will be done at all 
other timepoints. 
14. FSH tests in post-menopausal women (screening only). 
15. Weight only at screening visit 2 (MRI; PET subjects only). 
16. Vital signs consist of seated systolic and diastolic blood pressure, pulse rate, tympanic temperature, and respiratory rate. Vital signs will be done at the following 
timepoints. 
• PBMC-only subjects: screening; Day –1; predose and at 2, 4, 8, and 12 h postdose on Day 1; before dosing on Days 2–13; before, and at 2, 4, 8, and 12 h after 
dosing on Day 14; at 24 h (Day 15), 48 h (Day 16), 72 h (Day 17), 96 h (Day 18), 120 h (Day 19), and 144 h (Day 20) after the last dose of ASN51; and at follow-up 
• PET subjects will have the same timepoints as PBMC-only subjects, plus additional assessments at: imaging session 1 (baseline) and imaging session 3 (if held on 
Day 22 or Day 23) 
Triplicate measurements (obtained ≥ 5 min apart) will be made at screening. Single measurements will be made at all other timepoints. Measurements should begin 
with subjects in a seated position, after resting for at least 5 min. Additional unscheduled assessments may be done at the discretion of the investigator. Morning vital 
signs should always be taken before study drug administration. 
17. During the period of residence, ECGs will be recorded at the following timepoints. 
• PBMC-only subjects: screening; Day –1; predose and at 2, 4, 8, and 12 h postdose on Day 1; before dosing on Days 2–13; before, and at 2, 4, 8, and 12 h after 
dosing on Day 14; at 24 h (Day 15), 48 h (Day 16), 72 h (Day 17), 96 h (Day 18), 120 h (Day 19), and 144 h (Day 20) after the last dose of ASN51; and at follow-up 
• PET subjects will have the same timepoints as PBMC-only subjects, plus additional assessments at: imaging session 1 (baseline) and imaging session 3 (if held on 
Day 22 or Day 23) 
Triplicate recordings (obtained ≥ 5 min apart) will be made at screening. Single recordings will be done at all other time points. Recordings should be made with 
subjects in a supine position, after resting for 5 min. 

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18. Laboratory safety tests consist of haematology, clinical chemistry, coagulation, and urinalysis. Samples are to be taken at screening, Day –1, before dosing on Days 8 
and 14, on Day 20, and at follow-up. Samples for clinical chemistry only are to be taken at Imaging session 1. 
19. Plasma samples for the PBMC assay will be collected as follows. 
PBMC-only subjects 
• before and at 4, 8, and 12 h after dosing on Day 1 
• before dosing on Day 2 
• before and at 4 h after dosing on Day 11 
• before and at 4 h, 8 h, and 12 h after dosing on Day 14 
• at 24 h (Day 15), 72 h (Day 17), and 144 h (Day 20) after the last dose of ASN51 
PET subjects 
• before and at 4, and 8 h after dosing on Day 1 
• before dosing on Day 2 
• 4 h after dosing on Day 11 
• before and at 4 h, and 8 h after dosing on Day 14 
• at 24 h (Day 15), 72 h (Day 17), and 144 h (Day 20) after the last dose of ASN51 
20. Plasma samples for PK assay of ASN51 will be collected at as follows. 
PBMC-only subjects 
• before and at 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 16 h after dosing on Day 1 
• before dosing on Days 2, 4, and 7 
• before and at 8 h after dosing on Day 11 
• before and at 0.25, 0.5, 1, 2, 4, 6, and 12 h after dosing on Day 14 
• at 24 h (Day 15), 48 h (Day 16), 96 h (Day 18), and 144 h (Day 20) after the last dose of ASN51; and at follow-up 
PET subjects will have the same timepoints as PBMC-only subjects, plus 2 additional samples at imaging session 3 at about 2 h before and 2 h after the PET scan. 
Samples scheduled immediately before the PET scan should be taken as close as possible to the planned start of the PET scan. Samples scheduled for the end of the PET 
scan should be taken as soon as possible after the PET scan is finished. Samples scheduled during the PET scan should be taken either before or after the PET scan, as 
close to the scheduled timepoint as possible. 
When more than one assessment is scheduled at a specific timepoint, PET procedures should be prioritised (if applicable), followed by PK, PBMC, and scheduled safety 
assessments. Unscheduled safety assessments due to an emergency should always be prioritised. Blood sampling should be done on time. Other procedures should be done 
as close as possible to the scheduled timepoint. 
 
 
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12.2 
Sampling timepoints and additional tests 
With the sponsor’s approval, additional timepoints may be introduced, and changes 
to timepoints may be made, if we have reason to believe that the change might 
improve the quality of the data (for example, if we believe that an important effect of 
the IMP is occurring at a time when no measurements are scheduled), or if extra 
procedures are needed in the interest of subject safety. However, the total volume of 
blood taken in the trial will not exceed the value given in section 12.5. 
An additional 48 hours’ residence in the ward, and additional outpatient or imaging 
visits, will be permitted, in the event of a technical failure, to accommodate a later 
PET scan (detailed further below), and/or if extra observations or samples of blood 
or urine are needed. 
Extra procedures and changes to timepoints which have a significant impact on the 
scientific value and/or safety of the trial participants will be implemented only after 
approval of a substantial amendment from the Regulatory Authority (MHRA), unless 
the changes constitute an urgent safety measure. 
With the sponsor’s approval, the interval between inpatient and outpatient visits may 
be changed, if data collected during the trial support the change. The following will 
not be regarded as protocol deviations. 
Table 3:   Acceptable deviation times 
 
Procedure 
Study day 
Timepoint 
Acceptable deviation 
PK and 
PBMC blood 
sampling* 
Days 1 
and 14 
Predose 
Up to 30 min before dosing 
Up to and including 
1 h post dose 
± 5 min of the scheduled time 
After 1 h to 4 h post 
dose 
± 10 min of the scheduled time 
After 4 h to 24 h 
post dose 
± 15 min of the scheduled time 
Days 2–13 
Predose 
Up to 30 min before dosing 
Day 15–20 
> 24 h post dose 
± 1 h of the scheduled time 
Day 21 
onward 
Outpatient visits 
± 1 day 
All other 
procedures 
Days 1 
and 14 
Predose 
Up to 90 min before dosing** 
Up to and including 
4 h post dose 
± 10 min of the scheduled time 
After 4 h to 24 h 
post dose 
± 15 min of the scheduled time 
Days 2–13 
Predose 
Before dosing 
Day 15–20 
> 24 h post dose 
± 1 h of the scheduled time 
Day 21 
onward 
Outpatient visits 
± 1 day 
* For subjects having PET scans, samples scheduled immediately before the scan should 
be taken as close as possible to the planned start of the scan. Samples scheduled for the 
end of the scan should be taken as soon as possible after the scan is finished. Samples 

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Procedure 
Study day 
Timepoint 
Acceptable deviation 
scheduled during the scan should be taken either before or after the scan, as close to the 
scheduled timepoint as possible. 
** Samples for urinalysis may be collected anytime from when the subject awakes until 
the scheduled time. 
PET scans 
Timings of on-treatment PET scans may change based on emerging data. 
Occasionally, a technical failure, such as unsuccessful radiolabelled tracer synthesis 
or a PET scanner malfunction, may require a PET scan to be repeated or rescheduled. 
However, subjects will have no more than 3 PET scans and 3 doses of [18F]-IMA601 
during the study. Therefore, if the failure affects an imaging session before the 
administration of radioactivity, a scan may be repeated (ideally within about 24 h for 
on-treatment scans). If the scan is scheduled after a subject has been discharged 
from the ward, the subjects may be asked to stay at the research unit for up to 24 h 
longer. Otherwise, the subject may be discharged and later readmitted to the 
research unit. If a subject can receive no further doses of [18F]-IMA601, then they 
may be replaced, on a case-by-case basis, at the discretion of the sponsor. 
 
12.3 
Follow-up 
Subjects will return to the ward 9–11 days after their final dose of trial medication, or 
2–4 days after imaging session 3 (whichever is later; PET subjects only) for a follow- 
up visit. Withdrawn subjects who consent to a follow-up visit will undergo the same 
procedures (see section 9.4). 
The follow-up period may be extended if: 
1. a subject has an unresolved AE at the follow-up visit, which, in the opinion of the 
investigator, merits further follow-up; 
2. plasma concentrations of IMP were higher than predicted, and/or the half-life of 
the IMP was very long, and the investigator considers that additional follow-up is 
necessary; or 
3. new information becomes available that supports an extended follow-up period. 
The investigator will decide on the nature of the follow-up. For example, subjects 
may have a telephone follow-up at which they are asked about AEs, or subjects may 
be asked to attend extra outpatient visits for additional monitoring of blood levels or 
effects of IMP, and for extra safety tests. The extra safety tests might include tests 
that are not described in this protocol. The investigator reserves the right, during or 
after the study, to repeat safety tests or to do any extra safety tests that are in the best 
interest of the subjects. 
If a subject has an SAE during the study, they will also have an additional follow-up 
by telephone at 28 days (± 3) days after their final dose of trial medication. 

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12.4 
Methods 
Blood collection 
Blood will be taken by venepuncture or via a cannula. At HMR, cannulae will be 
inserted under local anaesthesia with lidocaine 0.5%, for withdrawal of venous 
blood. 
After each blood sample, the cannula will be flushed with 3–5 mL normal saline, to 
keep it patent. In order to minimise dilution of each subsequent blood sample with 
normal saline, the following procedure will be used: about 2 mL will be drawn via 
the cannula into the sampling syringe, and immediately re-injected gently via the 
cannula. The definitive blood sample will be taken after a 10-second delay. 
Additional cannulation (PET subjects only) 
On the day of each imaging session, before each PET scan, an additional cannula 
will be inserted into a forearm vein, as per site standard operating procedures (SOPs), 
for administration of the radiolabelled tracer [18F]-IMA601. 
An arterial cannula will be inserted to take blood for analysis of the radioligand and 
metabolites. The details of sampling times and analysis of the arterial samples (done 
at the imaging centre) will be provided in a PET blood sampling protocol. 
Blood volumes of specific types of samples may vary from those described below, 
but any change to the sample volumes will not cause the total volume of blood taken 
during the study to exceed that given in section 12.5. 
Samples for laboratory safety tests 
Blood will be taken for: 
• haematology (2 mL in EDTA) 
• clinical chemistry (3.5 mL in tubes with a gelatin plug) 
• serology and serum FSH (3.5 mL in tubes with a gelatin plug) 
• coagulation (3 mL in sodium citrate) 
Blood samples will be collected into 13 × 75 mm tubes. Urine will be collected in 
Universal containers. Samples will then be transferred to the laboratory. For 
logistical reasons, blood and/or urine samples may be collected in tubes other than 
those stated above. 
Processing and analysis of samples for laboratory safety tests 
Processing of samples will be done by the HMR Analytical Laboratory in accordance 
with the laboratory’s SOPs. 
The HMR Analytical Laboratory will do safety tests on blood and urine samples 
using instruments interfaced to a validated laboratory information management 
system (LIMS). Data from analysers that are not interfaced will be entered manually 
into the LIMS. 

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Drugs of abuse, alcohol, and cotinine tests 
Urine will be tested for drugs of abuse, alcohol, and cotinine according to the 
laboratory’s SOP. Tests will include: amphetamines, cocaine, opiates, cannabis, 
barbiturates, benzodiazepines, alcohol, and cotinine. 
Processing of blood samples for pharmacodynamic analysis 
Blood samples (5 mL) will be taken. 
Details will be provided in a PBMC sampling manual. 
Processing of blood samples for pharmacokinetic analysis 
Blood samples (2 mL) will be taken into K2EDTA tubes, and immediately placed on 
ice. Samples will be centrifuged at 1500 G for 10 min at 4°C and the plasma divided 
into 2 aliquots of approximately equal volume (minimum of 250 µL in each aliquot) 
in screw-capped polypropylene cryotubes. Plasma samples will be frozen at about 
_80°C or below within 1.5 h after collection, and stored until dispatch to DDS 
(Cambridgeshire, UK) for analysis. 
Physical and neurological examination 
Physical and neurological examination will be done by a physician. Complete 
physical examinations will examine: general appearance; head, ears, eyes, nose and 
throat; thyroid; lymph nodes; back and neck; heart; chest; lungs; abdomen; skin; and 
extremities. The following systems will be assessed: cardiovascular, dermatologic, 
respiratory, gastrointestinal, musculoskeletal and neurological. 
Brief physical examinations will be symptom-directed, and include neurological 
assessment of cranial nerves, motor, sensation, coordination, reflexes, and gait. 
Complete neurological examinations will include the following. 
Motor system: upper and lower limbs will be inspected for tremor and fasciculation. 
Tone will be recorded for all limbs as ‘normal’, ‘increased’ or ‘decreased’. Tendon 
reflexes will be elicited bilaterally (biceps, triceps, brachioradialis, knee, ankle) and 
graded 0 (absent even with reinforcement), + or ++ (normal) or +++ (increased). 
Plantar responses will be recorded as downgoing or equivocal (normal), or upgoing 
(abnormal). 
Romberg test: this test is designed to identify loss of proprioceptive sensation, 
resulting in a sensory ataxia. The sensory ataxia is accentuated when the subject 
stands still with both feet together, arms at each side and eyes closed (Romberg 
Test). If the subject falls or staggers after 1 min, they are considered to have a 
sensory ataxia (a positive Romberg sign). If the sign is absent, the test will be 
repeated with the subject standing on the balls of the feet. 
Coordination: will be examined using the ‘finger–nose’ test bilaterally, whereby the 
subject touches the examiner’s finger at a distance of about 50 cm, with his index 
finger and then touches his nose, as fast as they can. 

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Direct pupillary reflexes: elicited by shining a torch into the pupil of the eye being 
tested and noting pupillary constriction (normal). Consensual pupillary reflexes will 
be elicited by shining the torch in the pupil of one eye and noting pupillary 
constriction in the contralateral eye (normal). 
Height and weight 
Height and weight will be measured by trained staff at HMR. 
Vital signs 
Blood pressure and pulse rate will be measured using SpaceLabs oscillometric 
equipment. Measurements will be made with subjects in a seated position; subjects 
will remain seated for at least 5 min before vital signs are measured. 
Tympanic temperature will be measured using digital thermometers. 
Respiratory rate will be measured by observation of the chest. 
Repeat vital signs measurements 
During the trial, if vital signs fall outside the ranges in Table 5, a physician will 
review and decide on an appropriate course of action. The procedure will be 
repeated only if instructed by a physician. 
Table 5: 
Vital signs ranges 
 
Vital sign 
Range 
Seated systolic blood pressure 
90–140 mm Hg 
Seated diastolic blood pressure 
40–90 mm Hg 
Seated pulse rate 
40–100 beats/min 
Temperature 
35.5–37.8°C 
Respiration rate 
10–16 breaths/min 
If the result of the repeat measurement is still out of range, the investigator will 
decide on an appropriate course of action. 
Standard 12-lead ECGs 
12-lead ECGs will be recorded using Mortara ELI250c and ELI280 cardiographs. 
Each recording will be printed on a single A4 page at paper speed 25 mm/sec and 
calibrated to 10 mm/mV. Recordings will be made with subjects in a supine 
position; subjects will remain supine for at least 5 min before the ECG is recorded. 
PR, RR, QRS and QT intervals will be captured on source documents. QT interval 
will be corrected using Fridericia’s formula (QTcF). 

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During the trial, if ECG values fall outside the ranges in Table 6, a physician will 
review and decide on an appropriate course of action. The procedure will be repeated 
only if instructed by a physician. 
Table 6: 
ECG ranges 
 
ECG parameter 
Range 
Ventricular rate 
35–100 beats/min 
QRS 
≤ 120 msec 
PR interval 
110–220 msec 
QTcF (men) 
≤ 450 msec 
QTcF (women) 
≤ 470 msec 
If the result of the repeat measurement is still out of range, the investigator will 
decide on an appropriate course of action. 
Columbia-Suicide Severity Rating Scale (C-SSRS) 
The C-SSRS is a suicidal ideation rating scale used to evaluate suicidality30. The 
questionnaire will be administered by the investigator or his delegate. The ‘baseline’ 
questionnaire will be used at screening, and the ‘since last visit’ questionnaire will be 
used at follow-up. 
Structural MRI 
Structural MRI acquisition will be performed at Invicro using either a 3 Tesla 
Siemens (Siemens Healthcare, Erlangen, Germany) or 3 Tesla GE (GE Healthcare, 
UK) clinical MRI system, and will consist of a structural scanning protocol. MRI 
scans will be evaluated by a radiologist to exclude any subjects with major pathology 
or abnormalities. A radiologist will provide a report of each MRI scan to the 
investigator at HMR. 
PET scan 
Dynamic PET scans will be performed at Invicro using a Siemens Horizon PET/CT 
scanner (Siemens Healthcare, Erlangen, Germany). The subjects will be placed in 
the PET scanner with head padding to minimise movement during the scan. A low 
dose CT scan will be performed to correct for the attenuation of emitted radiation. 
Subjects will then receive an IV bolus injection of up to 100 MBq of the [18F]- 
IMA601 radioligand. Dynamic emission data will be recorded for up to about 
90 min after injection of the radioligand. 
Allen’s test 
If arterial cannulation will be used, the patency of subjects’ ulnar and radial arteries 
in both wrists will be checked, at screening and before insertion of the arterial 
cannula on scanning days. 

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12.5 
Total volume of blood removed 
The total volume of blood taken from each volunteer in the trial will be about 
184.5 mL (Table 7; PBMC-only subjects) or 537 mL (Table 8; PET subjects). 
Additional blood samples for assay of ASN51, PBMCs, or for laboratory safety tests 
may be taken as described in section 12.2. No more than an extra 80 mL of blood 
will be taken from any PBMC-only subject, and no more than an extra 30 mL of 
blood from any PET subject, unless medically indicated for safety reasons. 
Table 7: 
Planned blood volume (PBMC-only subjects) 
 
Test 
Planned number 
of tests 
Volume 
(mL) 
Total planned 
blood volume 
(mL) 
Haematology 
6 
2 
12 
Clinical chemistry 
6 
3.5 
21 
Coagulation 
6 
3 
18 
Serology (and FSH) 
1 
3.5 
3.5 
Pharmacokinetics 
30 
2 
60 
PBMC sampling 
14 
5 
70 
Total 
184.5 mL 
Table 8: 
Planned blood volume (PET subjects) 
 
Test 
Planned 
number of 
tests 
Volume 
(mL) 
Total planned blood 
volume (mL) 
Haematology 
6 
2 
12 
Clinical chemistry 
7 
3.5 
24.5 
Coagulation 
6 
3 
18 
Serology 
1 
3.5 
3.5 
Arterial 
3 
120 
360 
Pharmacokinetics 
32 
2 
64 
PBMC sampling 
11 
5 
55 
Total 
537 mL 
 
13 
Trial materials 
13.1 
Identity of test product(s) 
Immediate-release 
 containing 
 ASN51 will be provided to the HMR 
pharmacy by Asceneuron S.A, and will be packed and dispatched in containers. 

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Full details of ASN51 are included in the IB1 and IMPD27. 
The sponsor will provide to HMR a certificate of analysis, and a Certificate of GMP 
Compliance for the test product for HMR’s Qualified Person to release batches of 
IMP. 
 
13.2 
Packaging and labelling 
The trial medication will be packaged and labelled by the HMR Pharmacy, in 
accordance with The Rules Governing Medicinal Products in the European Union, 
Volume 4: Good Manufacturing Practice (GMP), and with HMR’s Manufacturing 
Authorisation for IMPs (MIA(IMP)). The IMP labels will include all the information 
required by Annex 13 to GMP13. 
 
13.3 
Storage and accountability of IMP 
The IMP will be stored and accounted for according to GMP and HMR SOPs. 
At the end of the trial, all unused IMP supplies will be returned to the sponsor or 
destroyed in accordance with the sponsor’s instructions. 
 
13.4 
Non-investigational medicinal product 
The radioligand [18F]-IMA601 (non-IMP) will be prepared by Invicro. 
Product name: [18F]-IMA601 (also known as [18F]OGA1) 
Dosage form: sterile solution for injection 
Effective dose: maximum 2.33 mSv for each PET scan (including components from 
both the PET [2.05 mSv] and CT scans [0.28 mSv]) 
Specific activity: will not exceed 100 MBq for each PET scan 
Route of administration: IV bolus 
Manufacturer/source of procurement: Invicro* 
* cGMP grade precursor will be procured from an external commercial source 
Full details are included in the [18F]-IMA601 non-IMPD28. 
 
13.5 
Other trial supplies 
Supplies of containers to be used to package IMP (eg bottles, vials, syringes), 
components to be used in the assembly of a dose (eg labels), and excipients to be 
used in the preparation of the IMP (eg sterile saline solution) will be placed in 
quarantine on receipt by HMR, pending assessment and release by Pharmacy Quality 
Control. 

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14 
Adverse events 
14.1 
Definitions of adverse events 
Adverse event (AE) 
Any untoward medical occurrence in a patient or clinical trial subject administered a 
medicinal product and which does not necessarily have a causal relationship with 
that treatment. 
Adverse drug reaction (AR) 
All untoward and unintended responses to an IMP related to any dose administered. 
Note that, according to the ICH Guideline for Good Clinical Practice (ICH GCP), the 
phrase ‘response to an IMP’ means that a causal relationship between the medicinal 
product and an AE is at least a reasonable possibility, ie a relationship cannot be 
ruled out. 
Unexpected AR 
An AR, the nature or severity of which is not consistent with the applicable product 
information (eg IB for an unauthorised investigational product, or summary of 
product characteristics for an authorised product). 
Serious adverse event (SAE) or serious adverse drug reaction (SAR) 
An AE or AR that: 
• is fatal; 
• is life-threatening; 
• requires or prolongs inpatient treatment; 
• results in persistent or significant disability or incapacity; or 
• is a congenital anomaly or birth defect. 
Note that: 
• the term ‘life-threatening’ in the definition of ‘serious’ refers to an event or 
reaction in which the patient was at risk of death at the time of the event; it does 
not refer to an event or reaction which hypothetically might have caused death 
had it been more severe; and 
• in accordance with the ICH Guideline on Clinical Safety Data Management: 
Definitions and Standards of Expedited Reporting, events or reactions that are 
not immediately life-threatening or may not result in death or hospitalisation, but 
might jeopardise the subject or require intervention to prevent one of the other 
outcomes listed above, should usually be considered serious. 
Significant AE or AR 
Any SAE or SAR, or an AE or AR which is not serious but is otherwise significant. 
The following should normally be considered significant: 

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• a marked haematological or other laboratory abnormality; 
• an AE or AR that leads to an intervention, including withdrawal of drug 
treatment, dose reduction or significant additional concomitant therapy; or 
• any AE or AR that the investigator considers to be significant. 
 
14.2 
Procedures for recording adverse events 
Subjects will be carefully monitored for AEs. The investigator or delegate will 
question the subjects about AEs using a non-leading question, such as ‘How are you 
feeling?’. The investigator will also record AEs reported spontaneously by the 
subjects. Clinically significant changes in the findings of physical examination, and 
clinically significant abnormalities in the results of objective tests (eg laboratory 
variables, x-ray, ECG) may also be recorded as AEs. The investigator will use the 
following criteria when deciding whether to report an abnormal result as an AE. 
1. 
The test result is associated with accompanying symptoms. 
2. 
Results of additional diagnostic tests cause concern or necessitate medical 
intervention. 
3. 
As a consequence of the test result, the dose administered to the subject is 
changed, the subject is withdrawn, or the subject is given concomitant treatment. 
4. 
The investigator considers the result to constitute an AE. 
If any of the above criteria are met, the investigator will report the result as an AE. 
A record will be kept in the source documents of all AEs as reported, whether 
believed to be related or unrelated to the treatment. The record will include the 
following. 
• Clinical symptoms: a simple, brief description. 
• Date and time of onset and end of clinical symptoms. 
• Frequency: constant or intermittent. 
• Severity. The following categories will be used: 
Mild: the AE does not interfere with the volunteer’s daily routine, and does not 
require intervention; it causes slight discomfort. 
Moderate: the AE interferes with some aspects of the volunteer’s routine, or 
requires intervention, but is not damaging to health; it causes moderate 
discomfort. 
Severe: the AE results in alteration, discomfort or disability which is clearly 
damaging to health. 
• Relationship to treatment: The assessment of relationship of AEs to the 
administration of IMP is a clinical decision based on all available information at 

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the time of the completion of the case report form. The following categories will 
be used. 
Unrelated 
• The AE is clearly not related to the study drug/procedure, beyond a reasonable 
doubt. 
Unlikely related 
• The AE is doubtfully related to the study drug/procedure. 
Possibly related 
• The AE may be related to the study drug/procedure. 
Probably related 
• The AE is likely related to the study drug/procedure. 
Definitely related 
• The AE is clearly related to the study drug/procedure. 
For the purposes of reporting to regulatory agencies, AEs deemed ‘definitely 
related’, ‘probably related’ or ‘possibly related’ will be considered related to 
study treatment; and those deemed ‘unrelated’ or ‘unlikely related’ are 
considered unrelated to study treatment. 
AEs listed as related are considered to have a suspected ‘reasonable causal 
relationship’ to the study drug/intervention (ICH E2A). The expression 
‘reasonable causal relationship’ is meant to convey in general that there are facts 
(evidence) or arguments to suggest a causal relationship. 
• Action taken: none, drug treatment, subject withdrawn, other (specified). 
• Outcome: recovered/resolved, recovering/resolving, not recovered/not resolved, 
or unknown. 
 
14.3 
Procedures for dealing with serious adverse events 
In the event of any SAE which, in the investigator’s opinion, justifies termination or 
modification of the trial (see section 8.4), dosing will be stopped and the sponsor’s 
medical monitor will be informed immediately (within 24 h of the investigator 
becoming aware of the event) by telephone or email, as follows. 
Medical monitor: 
 MD 
Tel: 
 
Mobile: 
 
Email: 
 
 
All SAEs occurring after the signing of the ICF until the follow up visit, regardless 
of study drug relationship, must be reported to the sponsor’s pharmacovigilance 

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department, with as much information as possible, within 24 h of the investigator 
becoming aware of the event. The investigator will complete an SAE form and 
provide it to the sponsor’s pharmacovigilance department, via the following contact 
details. 
Monitor: 
 MD 
Tel: 
 
Mobile: 
 
Email: 
 
 
The sponsor will also be notified by email 
 
 
The investigator will notify the REC of SAEs that occur during this trial, if 
applicable, in accordance with the SOPs issued by the Research Ethics Service 
(RES)23. 
The sponsor is responsible for determining the expectedness of the event, using the 
reference safety information in the IB1. The sponsor will notify the MHRA of all 
suspected unexpected serious adverse reactions (SUSARs), and will be responsible 
for ensuring that the REC is notified of SUSARs, if applicable. SUSARs that are 
fatal or life-threatening must be notified to the MHRA and REC within 7 days after 
the sponsor has learned of them. Other SUSARs must be reported to the REC and 
MHRA within 15 days after the sponsor has learned of them. 
If a subject has an SAE during the study, they will have an additional telephone 
follow-up as described in section 12.3. 
 
14.4 
Procedures for handling withdrawals due to adverse events 
The investigator will assess the reason for withdrawal as far as possible and will fully 
record the circumstances and medical details. Provided that subjects give written 
informed consent, they will undergo the standard medical examination and 
laboratory tests at withdrawal from the trial which they would have undergone had 
they completed it (see also section 9.4). 
 
14.5 
Procedures for reporting pregnancies 
Subjects will be asked to follow the contraception guidance in section 11. 
If, during the study, the investigator becomes aware of a pregnancy in a subject or 
their partner, they will inform the sponsor’s pharmacovigilance department 
immediately (within 24 h of the investigator becoming aware of the event), as 
follows. 

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Monitor: 
 MD 
Tel: 
 
Mobile: 
 
Email: 
 
The investigator will follow-up the pregnancy according to HMR SOPs, provided the 
subject (or their partner) consents to that. A pregnancy will not constitute an SAE 
unless it meets one of the criteria in section 14.1. 
 
15 
Data management and quality assurance 
Data will be securely stored within HMR and Invicro. Data collected in paper source 
documents at HMR (see section 18.2) will be transcribed into an electronic CRF 
(eCRF). 
The investigator is responsible for ensuring the accuracy and completeness of the 
data entered into the eCRF, and the timeliness of data entry. Clinical data (including 
AEs, concomitant medication, etc) will be entered into a 21 CFR Part 11-compliant 
Medrio M-1 database. The Medrio M-1 system includes password protection and 
internal quality checks, such as automatic range checks, to identify data that appear 
inconsistent, incomplete, or inaccurate. Data reported in the eCRF, derived from 
source documents, should be consistent with the source documents or the 
discrepancies should be explained. Where the data violate data validation checks, 
queries will be generated for resolution by clinical staff. All edits made to the 
database upon resolution of queries will be recorded in an electronic audit trail. 
The database will be locked after the following have been completed: all expected 
eCRF data have been entered and accounted for; all discrepancies have been 
resolved; data have been coded as appropriate; SAEs have been reconciled; all site 
audit findings impacting the database have been closed; and QC inspection has been 
completed. 
Data in source documents will be checked by the HMR Quality Assurance (QA) 
Department. In addition, the HMR QA Department will audit the trial report; that 
audit will include checks to ensure that statistical output is correctly reproduced in 
the report. If requested, the investigator will provide the sponsor, MHRA, and REC 
with direct access to the original source documents. 
 
16 
Statistical methods 
16.1 
Pharmacokinetic methods 
The PK analysis will be done by the Statistics and Data Management Department at 
HMR, using WinNonlin 8.3 or higher. 

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Actual times will be used to derive PK parameters. Missing data will not be 
imputed. 
For calculation of all PK parameters, and for individual concentration–time plots, 
plasma concentrations below the limit of quantification of the assay (BLQ) will be 
treated as follows: values that occur before tmax will be taken as zero; all other values 
will be taken as missing. 
For calculation of plasma concentration summary statistics, BLQ values will be 
taken as zero, unless they fall between two quantifiable concentrations, in which case 
they will be treated as missing. 
The pharmacokinetic parameters listed in section 16.1.1 will be derived. 
 
16.1.1 Plasma Parameters 
Text symbol 
Definition 
Calculation 
Concentrations during and after multiple dosing 
Ctrough 
Trough plasma concentration 
Trough plasma concentration (measured 
concentration at the end of a dosing 
interval at steady state [taken 
directly before next administration]) 
obtained directly from the 
concentration–time data. 
Concentrations and times (Day 1 and after final dose) 
Cmax 
Maximum (peak) plasma 
concentration 
Obtained directly from the 
concentration–time data. 
Cmax/Dose 
Dose-normalised Cmax 
Calculated as Cmax /Dose administered 
tmax 
Time to reach maximum (peak) 
plasma concentration 
Obtained directly from the 
concentration–time data. 
Half-life (after final dose) 
λz 
Terminal rate constant 
Estimated by linear regression of 
logarithmically transformed 
concentration versus time data. 
t½ 
Terminal half-life 
Calculated from the terminal slope of 
the log concentration–time curve, as 
follows: 
 
 
Areas under the curve 
𝑡𝑡½ = log𝑒𝑒 2 
λ𝑧𝑧 
AUCtau 
Area under the plasma 
concentration–time curve during 
a dosing interval (tau) 
Calculated using the trapezoidal method. 
 
AUClast 
(after final 
dose) 
Area under the plasma 
concentration–time curve from 
time zero to time of last 
measurable concentration 
Calculated using the trapezoidal method. 

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Text symbol 
Definition 
Calculation 
AUCinf 
(after final 
dose) 
Area under the plasma 
concentration–time curve from 
time zero to infinity 
Calculated using the trapezoidal method 
for the interval 0 to tlast (time tlast is the 
time at which the last non-zero level was 
recorded), plus the area under the 
exponential curve from tlast to infinity, 
calculated as follows: 
AUC 
 
 
t −inf = Cˆ
t
 
λz 
where Cˆ
t is the 
 
 
AUCinf/Dose 
(after final 
dose) 
 
 
Dose-normalised AUC to 
infinity 
predicted value of the concentration at 
tlast. 
Calculated as AUCinf /Dose 
administered 
%AUCextrap 
(after final 
dose) 
Percentage of AUC∞ 
extrapolated from tlast to infinity 
%AUC 
 
 
extrap = 100× AUCt−inf 
AUCinf 
Clearance, volume of distribution and mean residence time (after final dose) 
CLSS/F 
Apparent total clearance from 
Calculated using the following formula: 
plasma after non-intravenous 
CL / F = Dose 
administration calculated at 
steady state 
SS 
AUC  
tau 
Vz/F 
apparent volume of distribution 
Calculated using the following formula: 
after non-intravenous 
administration calculated at 
steady state 
Vz / F = 
Dose 
λz • AUC 
 
 
 
tau 
Accumulation and time invariance ratios 
Rac(AUC) 
Accumulation ratio for AUC 
Calculated from AUCtau at steady state 
and AUCtau after a single dose 
Rac(Cmax) 
Accumulation ratio for Cmax 
Calculated from Cmax at steady state and 
Cmax after a single dose 
 
16.2 
Statistical methods 
 
16.2.1 Planned analyses 
Final statistical analysis, including analysis of PK parameters, will be done by HMR. 
A statistical analysis plan will be prepared by the HMR Statistics and Data 
Management Department after completion of the final protocol and before database 
lock. 
All statistical analysis and reporting will be done using SAS 9.4 or higher. 
 
16.2.2 Statistical hypotheses 
The trial is an exploratory one, and there are no null hypotheses to be tested. 

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16.2.3 Analysis populations 
The following populations will be identified: 
Safety population: 
All subjects who received at least one dose of study 
drug. 
PET population: 
All subjects in the safety population who had a 
baseline PET scan, at least 1 post-baseline PET scan, 
and a PK result immediately preceding a PET scan. 
PD analysis population: 
All subjects in the safety population for who a PBMC 
measure is available. 
PK analysis population: 
The PK analysis population will consist of the 
subjects who provide evaluable data for the 
comparisons of interest. These subjects should have 
at least one quantifiable plasma concentration, should 
not have violated any major entry criterion likely to 
confound the PK analysis, and should not have 
deviated significantly from the protocol between 
enrolment and successful study completion. 
The primary endpoint will be analysed using the PET and PD populations. 
 
16.2.4 General considerations for data analyses 
The minimum set of summary statistics for numeric variables will be: n, mean, 
standard deviation (or standard error), median, minimum, and maximum. 95% 
confidence intervals (CI) will be presented where appropriate for data interpretation. 
Categorical data will be summarised in frequency tables with n and percentage. 
Summaries of a categorical variable will include all recorded values. 
The minimum and maximum values will be presented to the same number of decimal 
places as the raw data collected on the CRF (or to 3 significant figures for derived 
parameters). The mean, median and percentiles (eg Q1, and Q3) will be presented to 
one additional decimal place. The standard deviation (SD) and standard error will be 
presented to 2 additional decimal places. 
‘Baseline’ will be the latest value obtained before IMP administration (predose on 
Day 1, or Day –1 if not recorded at predose, or screening if not recorded at predose 
or on Day –1). Out-of-range laboratory tests may be repeated. If a test is out of- 
range at baseline and repeated before dosing, the latest repeat value before dosing 
will be used as baseline. However, if a test is out-of-range and repeated at any other 
time during the study, the out-of-range value (not the repeat value) will be included 
in statistical summaries. 

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16.2.5 Study population analyses 
 
16.2.5.1 Disposition of subjects 
 
The disposition of all subjects in all analysis populations will be summarised 
including: number completing the study, by treatment; and number discontinued 
from the study. 
All subjects who withdraw or are withdrawn from the study will be listed, by 
treatment, with the reason for withdrawal. 
16.2.5.2 Demographic and baseline characteristics 
 
Demographic and baseline characteristics (eg physical examination, vital signs and 
ECGs) will be summarised. 
Subjects who take concomitant medication will be listed. All non-trial medication 
will be coded using the World Health Organisation (WHO) ATC index (version 2021 
or higher). 
Medical and surgical history data will also be listed. Medical and surgical history 
will be coded using the version of the Medical Dictionary for Regulatory Activities 
(MedDRA) current at the time of database lock. 
16.2.5.3 Treatment compliance 
 
Dates and times of dosing will be listed. 
 
16.2.6 Safety data analyses 
Summaries and listings of safety data will use the safety population. 
16.2.6.1 Adverse events 
 
AEs will be coded using the version of the Medical Dictionary for Regulatory 
Activities (MedDRA) current at the time of database lock. 
All AEs will be listed. 
A treatment-emergent adverse event (TEAE) is an AE that emerges during treatment 
(having been absent before treatment) or that worsens after treatment14. 
The number of subjects with at least one TEAE will be tabulated by actual treatment 
and MedDRA system organ class and preferred term. 
For each of the following, the number of TEAEs and the number of subjects with 
TEAEs will be summarised by actual treatment as follows: 
• TEAEs, by system organ class and preferred term 
• drug-related TEAEs, by system organ class and preferred term 

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Subjects with more than one TEAE will be counted only once, at the maximum 
causality, for each system organ class and preferred term. AEs with missing severity 
and/or causality will be treated as severe and possibly related, respectively. 
AEs leading to withdrawal, deaths and other SAEs will be listed separately (fatal 
events will be listed separately from non-fatal events). 
16.2.6.2 Clinical laboratory evaluations 
 
Data from haematology, coagulation, clinical chemistry, and urinalysis will be 
summarised by treatment. 
Data from haematology, coagulation and clinical chemistry outside the normal range 
will be listed separately and summarised. 
16.2.6.3 Other safety measures 
 
Vital signs at each planned assessment, and change in vital signs from baseline at 
each planned post-baseline assessment, will be summarised by actual treatment. 
Vital signs data outside of the normal range will be listed and summarised. 
A separate listing of vital sign findings, classified as clinically significant by the 
investigator will also be provided. 
QT interval will be corrected using Fridericia's (QTcF) formulae. 
ECG variables will be summarised by treatment and timepoint. Differences from 
baseline will be summarised by treatment and timepoint. 
QTcF values > 450 msec, PR interval shortening < 110 msec, and PR interval 
prolongation >220 msec, and increases of QTcF from baseline of > 30 msec and 
> 60 msec, will be listed by treatment and timepoint and summarised. A separate 
listing of ECG findings classified as abnormal by the investigator will also be 
provided. 
Abnormal physical and neurological examination findings will be listed. 
Positive C-SSRS data will be listed. 
16.2.7 PET data analyses 
Start and end date of each PET scan will be listed together with the scan start/stop 
time and the Dose drawn up, Dose administered, Residual 1, and Residual 2. 
[18F]-IMA601 regional total volume of distribution (VT) at each brain scan will be 
listed for each session and for change from baseline. 
The RO values will be listed for imaging sessions 2 and 3, respectively, together with 
the plasma concentration of ASN51 at the time of the start of each postdose PET 
scan, which will be calculated by log-linear interpolation from the two closest PK 
data points by subject and treatment (to be provided by the sponsor). 

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These concentration data will be transferred to Invicro for the PK-RO analysis. The 
PK-RO analysis will be provided by Invicro and sent to HMR for the inclusion in the 
CSR. 
 
16.2.8 Pharmacokinetic data analyses 
PK data will be summarised using the PK analysis population. 
For log-transformed parameters, the primary measure of central tendency will be the 
geometric mean15; for untransformed parameters, it will be the arithmetic mean or 
median. 
For all variables, N (number of subjects in receiving the treatment in the population), 
n (number of observations), arithmetic mean, median, minimum, maximum, SD, 
%CV, and the 95% CI of the arithmetic mean will be derived. For log-transformed 
variables, all of the above plus the geometric mean, its 95% CI, and the SD of the 
log-transformed variables, will be provided. 
Plasma concentrations and PK parameters will be listed and summarised, by 
treatment, using descriptive statistics. Individual and mean plasma 
concentration–time profiles will be presented graphically. All available data will be 
used to derive PK parameters in individual subjects. 
 
16.2.9 Pharmacodynamic data analyses 
O-GlcNAcylation of PBMCs will be summarised using the PD population. 
Time invariance of target engagement will be investigated by comparing the PD and 
PK/PD relationship over time. 
Food effect on the PBMC assay will be investigated by comparing Day 11 and 14 
PBMC data. 
In addition to the descriptive statistics of the PBMC data (ie N, mean, median, SD, 
min, max, CV%), time-matched PBMC parameters (Day 1 vs Day 14, and Day 11 vs 
Day 14) will be assessed using an Analyses of variance (ANOVA) approach. 
ANOVA will be performed on the natural log(ln)-transformed PBMC parameters. 
Each ANOVA will include calculation of least square means (LSM), the difference 
between LSM of the two conditions, and the standard error and 90% confidence 
interval (CI) associated with this difference. The LSM, difference in LSMs, and 
associated 90% CI will be back transformed to present geometric LSM, the ratio of 
geometric means, and associated 90% CI. The 90% CI of geometric mean ratio will 
be calculated to check whether it lies within the interval 0.70 to 1.43. 
Furthermore, PBMC PK/PD of Day 1 and Day 14 will be investigated by a 
regression analysis, where slope and intercept will be compared with appropriate 
statistical methods descriptively. 

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16.3 
Determination of sample size 
Since this trial is hypothesis generating, no formal calculation of sample size is 
appropriate. 
The sample size chosen is considered adequate to allow modelling of the relationship 
between ASN51 plasma concentrations and pharmacodynamic target engagement 
using a PBMC O-GlcNAcylation assay. 
PET analyses of 8 subjects is sufficient to define the occupancy of O-GlcNAcase and 
is within the range generally accepted for PET studies. 
 
17 
Ethical and regulatory requirements 
The trial proposal will be reviewed by a recognised REC, and by the MHRA. The 
trial will not proceed unless the sponsor obtains from the MHRA a clinical trial 
authorisation (CTA), and the REC approves the trial. The trial will not proceed at 
any site until that site has obtained site-specific approval. No subject will have a 
PET scan without approval from the Administration of Radioactive Substances 
Advisory Committee (ARSAC). 
The trial will be done at HMR, in compliance with The Medicines for Human Use 
(Clinical Trials) Regulations 2004 and current amendments19, The Medicines for 
Human Use (Clinical Trials) (Amendment) (EU Exit) Regulations 201920, The 
Human Medicines (Amendment etc) (EU Exit) Regulations of 2019 and 202021,22, 
GMP13, the SOPs issued by RES for RECs in the UK23, and Good Clinical Practice, 
which has its origins in the Declaration of Helsinki. 
All subjects must give written consent to participate in this trial. Consent for 
screening evaluations may be obtained using the information and consent form for 
the HMR healthy volunteer panel, which has been approved by the Health Research 
Authority’s Generic Review Committee. The trial-specific information and consent 
form will be signed by the subject either before any screening evaluation or after the 
investigator confirms the eligibility of the subject for the trial and before the subject 
is randomised to receive the first administration of IMP. Before giving consent, 
subjects must read the information sheet about the trial. They must also read the 
consent form. They will then discuss the trial with the investigator or his deputy and 
be given the opportunity to ask questions. The trial-specific information sheet and 
the consent form must be approved by the REC. 
Each subject is free to withdraw from the trial at any time, without giving a reason. 
If a subject withdraws, the investigator will ask the subject to consent to a follow-up 
examination. For withdrawn subjects, the investigator will use a special information 
and consent form which has been ethically approved. If the subject consents to the 
follow-up examination but asks the investigator to destroy all identifiable samples 
taken from the subject and/or not enter into the eCRF results of the follow-up 
examination, the investigator will comply with the subject’s requests. 

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The sponsor will ensure that the MHRA and the REC, are informed promptly of 
SUSARs (see section 14.3), and that any new reports of SUSARs from other ongoing 
trials of the IMPs under investigation in this trial are notified to the MHRA, and to 
the REC, if applicable. The sponsor will provide the investigator, the REC and the 
MHRA with annual safety reports of each IMP under investigation, and listings of all 
suspected serious adverse reaction (SSAR) reports. The sponsor will also inform the 
investigator promptly of any new safety or toxicology data that might affect the 
safety of the subjects in this study. 
The investigator will promptly inform the sponsor and, if applicable, the REC of any 
SAE that occurs during this trial (see section 14.3). The investigator will provide the 
REC with annual progress reports of the trial, if the trial lasts longer than a year. 
The investigator will report to the REC any protocol deviation that is, in his opinion, 
of clinical significance. The investigator will also inform the REC in the event of 
several deviations which, although of no clinical significance, cause inconvenience 
and/or discomfort to the volunteers. The sponsor will notify the MHRA and REC of 
any serious breach of GCP (for example, the investigator puts subjects’ safety at risk, 
falsifies data, or persistently fails to comply with this protocol or good clinical 
practice). 
Within 90 days after the end of the trial, the sponsor will ensure that the REC and the 
MHRA are notified that the trial has finished. If the trial is terminated prematurely, 
those reports will be made within 15 days after the end of the trial. 
The sponsor will supply a summary of the clinical trial report to the MHRA and REC 
within 1 year after the end of the trial. 
Trial procedures at HMR will be subject to audits by the HMR QA Department, to 
ensure compliance with the protocol and applicable regulatory requirements. 
 
18 
Trial documentation 
18.1 
Protocol amendments 
After the protocol has been approved by the REC and the MHRA, no changes may 
be made without the agreement of both the investigator and the sponsor. 
The MHRA and REC do not need to approve any substantial change to the protocol 
that needs to be implemented urgently to avoid an immediate hazard to trial subjects. 
The sponsor will ensure that the MHRA and REC are informed of urgent 
amendments or a temporary halt to the trial in accordance with The Medicines for 
Human Use (Clinical Trials) Regulations 2004 (and current amendments)19 and the 
SOPs issued by RES for NHS RECs23. 
All agreed protocol amendments will be recorded on a written agreement which will 
be signed and dated by the investigator and sponsor, and attached to the original 

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protocol. The REC and/or MHRA must approve substantial amendments before they 
are implemented. 
 
18.2 
Case report forms 
The eCRF will be designed and produced by HMR. 
To preserve confidentiality, the CRF will not bear the subject’s name. The subject 
number and/or HMR volunteer number will be used for identification. 
The investigator is responsible for ensuring the accuracy and completeness of the 
data entered into the eCRF, and the timeliness of data entry. Clinical data (including 
AEs, concomitant medication, etc) will be entered into a 21 CFR Part 11-compliant 
Medrio database. The Medrio system includes password protection and internal 
quality checks, such as automatic range checks, to identify data that appear 
inconsistent, incomplete, or inaccurate. Data reported in the eCRF, derived from 
source documents, should be consistent with the source documents or the 
discrepancies should be explained. Where the data violate validation checks, queries 
will be generated for resolution by clinical staff. All edits made to the database upon 
resolution of queries will be recorded in an electronic audit trail. 
Source documents 
Before the start of the study, the sponsor and investigator will sign an agreement 
listing the source documents to be used in this trial. 
 
18.3 
Reporting of results 
HMR will prepare a draft report for discussion with the sponsor. The report will 
contain results and discussion of the trial, to which will be attached tables, figures 
and listings in compliance with ICH E324. 
Completed eCRFs will be supplied separately to the sponsor by HMR. 
 
19 
Obligations of the sponsor and investigator 
19.1 
Monitoring, auditing, and inspection 
The trial will be monitored by the sponsor. 
A sample of documents generated by HMR which form part of this trial, and the 
ensuing data, will be audited by the HMR Quality Assurance Department to assess 
compliance with the quality management system of HMR. That system incorporates 
the requirements of The Medicines for Human Use (Clinical Trials) Regulations 
2004 (and current amendments)19, ICH GCP, GMP13, and the SOPs issued by RES 
for RECs in the UK23, and is based on ISO 9001. 
The sponsor may do a quality assurance audit, and regulatory authorities may inspect 
this study, at any time during or after the study. The sponsor and investigator agree 

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to allow auditors and inspectors direct access to all relevant documents, and to 
allocate time to discuss findings with the auditors or inspectors. 
 
19.2 
Compensation of volunteers 
The sponsor agrees to abide by the Association of the British Pharmaceutical 
Industry Guidelines for medical experiments in non-patient human volunteers (2018 
edition)25, and undertakes to compensate the subjects for injuries which are 
considered, on the balance of probabilities, to have arisen as a result of their 
participation in the trial. 
 
19.3 
Confidentiality 
All personal details of the participating subjects and the results of the trial will be 
kept strictly confidential. Each subject’s GP (or equivalent physician) will be 
informed of the nature and timing of the trial. 
All unpublished documents including the protocol, the CRF, and the IB are 
confidential. Those documents cannot be disclosed to a third party without the 
written consent of the sponsor. However, submission of those documents to a REC 
is expressly permitted. 
The investigator agrees that the sponsor maintains the right to use the results of this 
trial, in their original form and/or in a global report, for submission to governmental 
and regulatory authorities of any country. 
 
19.4 
Publication 
If the data merit, the investigator and the sponsor will discuss the preparation of a 
manuscript for publication in a peer-reviewed professional journal or an abstract for 
presentation, oral or written, to a learned society or symposium. Either party may 
undertake the task but both must agree to the strategy before the work is started. 
Each party will allow the other 30 days to comment before any results are submitted 
for publication or presentation. Authorship should reflect work done by the 
investigators and personnel of the sponsor, in accordance with generally recognised 
principles of scientific collaboration. 
 
19.5 
Archiving 
The sponsor and HMR will keep in a trial master file all the essential documents 
required by GCP. HMR will ensure that the investigator’s master file, and all data 
generated during the trial, will be archived in a secure place for at least 25 years. 
Documents will be stored such that they are readily available for inspection at the 
request of the sponsor or a regulatory authority. Any transfer of ownership of the 
investigator’s data or documents will be documented, and the sponsor will be 
informed. 

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20 
Premature termination of the trial 
The sponsor and investigator reserve the right to terminate this trial should severe 
AEs, SAEs or any other safety issue occur during the trial. If the trial is terminated 
prematurely, and the sponsor or investigator, as appropriate, will provide a written 
statement of the reasons for termination. The sponsor will ensure that the MHRA 
and REC are notified, as described in section 17. 

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21 
References 
1. World Health Organisation. https://www.who.int/news-room/fact- 
sheets/detail/dementia 

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Protocol Version 2, dated 23 January 2023 
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