A Multicenter, Long-term Extension Study to Evaluate the Safety, Tolerability, and Efficacy of AL002 in Participants With Alzheimer's Disease
Phase: PHASE2
Conditions: Alzheimer's Disease
Sponsor: Alector Inc.

A MULTICENTER, LONG-TERM EXTENSION STUDY TO EVALUATE 
THE SAFETY, TOLERABILITY, AND EFFICACY OF AL002 IN 
PARTICIPANTS WITH ALZHEIMER’S DISEASE 
Protocol Number: 
AL002-LTE 
Current Version Number: 
2.0 
Replaces Version Number, Date: 
1.0, 30 August 2022 (Global) 
1.1, 25 August 2023 (European Union [EU]/ 
European Economic Area [EEA] Only) 
Name of Investigational Product: 
AL002 
Developmental Phase of Study: 
Phase 2 
Indication: 
Alzheimer’s Disease (AD) 
Sponsor: 
Alector, Inc. 
131 Oyster Point Blvd, Suite 600 
South San Francisco, CA 94080 
US 
IND Number: 
136758 
EudraCT Number:  
2022-002987-57 
EU CT Number: 
2023-506872-29-00 
Approval Date: 
12 January 2024 
This study is to be performed in compliance with the protocol, Good Clinical Practices, and 
applicable regulatory requirements. 
Confidentiality Statement 
This document contains confidential information. This document must not be disclosed to 
anyone other than the site study staff and members of the institutional review board/independent 
ethics committee/institutional scientific review board or equivalent. The information in this 
document cannot be used for any purpose other than the evaluation or conduct of the clinical 
investigation without the prior written consent of Alector, Inc. 

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PROTOCOL SIGNATURE PAGE 
A Multicenter, Long-Term Extension Study to Evaluate the Safety, 
Tolerability, and Efficacy of AL002 in Participants with Alzheimer’s Disease 
Study Number: AL002-LTE 
Version: 2.0 
Date of Issue: 12 January 2024 
Signature of Approval for Protocol (AL002-LTE Version 2.0) 
Name  
Signature 
Date 
Gary Romano, MD, PhD 
 
Alector, Inc. 
Jingjing Gao, PhD 
s 
Alector, Inc. 
Refer to signature manifest at the end 
of the document. 
 
This study is to be performed in accordance with International Council for Harmonisation of 
Technical Requirements for Pharmaceuticals for Human Use E6(R2) (Guideline for Good 
Clinical Practice), the ethical principles that have their origin in the Declaration of Helsinki, 
Title 21 of the Code of Federal Regulations, Parts 50 (Protection of Human Subjects), 
56 (Institutional Review Boards), and 312 (Investigational New Drug Application). 

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DECLARATION OF INVESTIGATOR 
I have read and understood all sections of the protocol entitled “A Multicenter, Long-Term 
Extension Study to Evaluate the Safety, Tolerability, and Efficacy of AL002 in Participants with 
Alzheimer’s Disease”. 
I agree to supervise all aspects of the protocol and to conduct the clinical investigation in 
accordance with Protocol AL002-LTE Version 2.0, dated 12 January 2024, the International 
Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use 
Harmonised Tripartite Guideline E6(R2): Good Clinical Practice, and all applicable government 
regulations. I agree to administer study drug only to participants under my personal supervision 
or the supervision of a Subinvestigator. 
I will not supply the study drug to any person not authorized to receive it. Confidentiality will be 
protected. Participant personal identification will not be disclosed to third parties or appear in 
any study reports or publications. 
I will not disclose information regarding this clinical investigation or publish results of the 
investigation without authorization from Alector, Inc. 
 
 
 
 
 
Signature of Principal Investigator 
 
Date 
 
 
 
Printed Name of Principal Investigator 
 
 
 

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SUMMARY OF CHANGES FROM PREVIOUS VERSION 
Herein is a summary of the changes made to Version 1.0 of the protocol, dated 30 August 2022, 
and reflected in the amended Version 2.0 of the protocol, dated 12 January 2024. 
Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Throughout 
• Revised date and version. 
• Other typographical, formatting 
corrections, minor administrative changes, 
and minor text clarifications. 
• Updates to the Table of Contents, List of 
Tables, List of Abbreviations, and 
References. 
Minor changes made to correct 
errors, conform to revised style 
standards, and/or reflect updates to 
the content for version control. 
Throughout 
• Removed all content related to participant 
randomization. 
Content was inaccurate - participants 
will not be randomized in this study. 
Throughout 
• Removed all content related to the 
Winterlight Labs Speech Assessment and 
whole genome sequencing. 
Assessments will no longer be 
utilized in this study. 
Throughout 
• Revised Medical Dictionary for 
Regulatory Activities (MedDRA) from 
Version 
. 
• Revised the World Health Organization 
Drug Dictionary (WHO DD) from March 
2019 to September 2022 version. 
Revised to most recent versions of 
regulatory guidance documents. 
Throughout 
• Revised term “investigational medicinal 
product (IMP)” to either AL002 or study 
drug depending on context. 
Revised for standardization with 
parent study protocol, AL002-2. 
Throughout 
• Previously, triplicate 12-lead 
electrocardiograms (ECGs) were required; 
this has now been modified to a single 
12-lead ECG. 
Revised to reduce patient testing 
burden. 
Title Page 
Added EudraCT number and European 
Clinical Trial Register (EU CTR) number. 
Revised for standardization with 
regulatory requirements. 
Synopsis 
Reorganization and revision of synopsis.  
Revised for clarity and alignment 
with updated protocol body text. 
Section 1.1 
• Added content related to approval of 
Leqembi® (lecanemab) and lack of 
marketing authorization for AL002. 
• Content reorganization. 
Revised to include availability of 
new AD therapy with additional 
reorganization for clarity and for 
compliance with European Clinical 
Trials Regulation (EU CTR) for 
trials conducted in the European 
Union (EU) and European Economic 
Area (EEA). 

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Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Section 1.5 
Refinements to content to remove clinical 
activity information. 
Revised for clarity. 
Section 2,  
Section 3.1 
• Primary endpoint revised to co-primary 
endpoints including assessment of dose 
titration on amyloid-related imaging 
abnormalities (ARIA) to objectives. 
• Secondary objectives and endpoints added 
and now include evaluation of 
pharmacokinetic (PK) parameters and 
clinical outcome assessments (COAs). 
• Exploratory objectives and endpoints 
were refined, and the COAs are now 
secondary objectives and endpoints (as 
noted above). 
• Added content related to approval of 
Leqembi® (lecanemab). 
• Content added to indicate participants 
were not directly involved in the study 
design. 
Revisions to objectives and 
endpoints for robustness and 
accuracy of study outcomes and 
assessments and compliance with EU 
CTR for trials conducted in 
EU/EEA. 
Section 3.2 
• Expanded content related to 
Screening/Baseline Visit, with an 
emphasis on transition from AL002-2 
parent study. 
• Expanded and reorganized content related 
to treatment period. 
• Expanded content related to the Early 
Termination (ET) Visit. 
• Content added to indicate that no 
additional care is expected to be required 
after the study has ended. 
Revised for clarity and to provide 
additional details related to transition 
of participants from parent study 
AL002-2 and for compliance with 
EU CTR for trials conducted in 
EU/EEA. 
Section 4 (Initial 
Paragraphs) 
Removal of redundant content that is now 
included in Section 3.2. 
Revised for clarity and to eliminate 
redundancy. 

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Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Section 4.1, 
Section 4.2 
• Revised to include detailed criteria for 
inclusion of female participants in relation 
to childbearing and contraception and 
male participants in relation to 
contraception. 
• Revised to include criteria related to 
weight and body mass index (BMI). 
• Participation in optional assessments 
removed as inclusion criteria. 
• Participants taking anticoagulation 
medications are now excluded from the 
study. 
• Participant agrees not to receive any 
investigational treatment, other than 
AL002, during the study. 
• Participants taking any passive 
immunotherapy (eg, immunoglobulin) or 
other long-acting biologic agent that is 
under evaluation or approved to prevent 
or postpone cognitive decline are 
excluded from the study. 
Revised for safety and clarity. 
Section 4.3.1, 
Section 4.3.2 
Section 4.3.1 is now “Withdrawal from 
Study Drug” and a new section has been 
added, “Section 4.3.2 Withdrawal from 
Study.” Criteria for withdrawal were further 
clarified and placed in the appropriate 
sections. In addition, content was added to 
indicate that participants who discontinue 
will not be replaced and duplicate content re: 
electronic case report from (eCRF) reporting 
was eliminated. 
Revised for clarification and 
accuracy of criteria for study drug as 
well as study withdrawal and 
participant replacement. 
Section 5.1 
Content related to the Titration Cohort was 
revised to indicate that evaluation of dosing 
and its relationship to safety and ARIA 
within the Titration Cohort will occur only 
by unblinded study personnel and the 
unblinded safety management team at 
Alector. ARIA monitoring and management 
will be consistent with the procedures 
outlined in the parent study. 
Revised for clarification and 
accuracy of evaluation of the 
Titration Cohort. 
Section 5.2.3 
Content related to the radiotracer 
[18F]flutametamol (Vizamyl) was removed. 
Will no longer be utilized in the 
study. 

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Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Section 5.2.4 
Content was added to summarize 
investigational and auxiliary medicinal 
products used in this study and their 
authorization status. 
Content added for compliance with 
EU CTR for trials conducted in the 
EU/EEA. 
Section 5.3.5 
Content related to storage and disposal was 
added for the Tau PET radiotracer 
[18F]MK-6240. 
Content added for compliance with 
EU CTR for trials conducted in the 
EU/EEA. 
Section 5.4.1,  
Section 5.4.2 
Content was revised to indicate that blinding 
to treatment assignments will be maintained 
throughout the LTE study by those who are 
conducting the efficacy assessments, the 
Investigator, the study staff at the site, study 
participants, participant study partners, 
clinical site monitors, CRO, and the Sponsor 
except in specific circumstances. Minor 
corrections were also made to Section 5.4.2. 
Revised for clarity and accuracy, and 
to enhance robustness of research 
outcomes. 
Section 6, 
Section 10.3 
Content was added to indicate that some 
participants may become incompetent during 
the study due to progression of disease. 
Content added for clarity. 
Section 6.1 
Section now entitled, “Timing of Study Drug 
Administration and Procedures.” 
Revised for clarity and accuracy and 
to align with Schedule of 
Assessments. 
Section 6.3.3 
Years of education will not be collected. 
Data not required for study analysis. 
Section 6.3.9, 
Section 14.1 
Content related to core ECG laboratory 
readings have been eliminated. 
Revised to align with updated study 
procedures. 
Section 6.5 
Section now entitled, “Pharmacokinetic and 
Anti-Drug Antibody Assessments” and 
content was reorganized. 
Title and content revised for clarity. 
Section 6.6 
Section now entitled, “Biomarker 
Assessments” and includes new subsections 
and reorganized content for “Fluid 
Biomarker Assessments” and “Imaging 
Assessments.” 
Revised to maintain all content 
related to biomarkers in a specific 
location in the protocol for clarity 
and accuracy. 
Section 7 (Initial 
Paragraph) 
Content revised to eliminate statement that 
any adverse event of special interest (AESI) 
detected after informed consent but prior to 
administration of study drug will be 
considered medical history. 
Revised to ensure all safety data is 
accurately assessed and recorded. 
Section 7.1 
Content revised to eliminate statement that 
events of ARIA detected during magnetic 
resonance imaging (MRI) performed at 
screening are not adverse events (AEs). 
Revised to ensure all safety data is 
accurately assessed and recorded. 

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Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Section 7.6.5, 
Section 7.12 
Content added for AESI of u
. 
Information added for monitoring 
and accurate recording of u
. 
Section 7.11.2 
Table 8 revised to provide additional detail 
related to specific actions required for 
monitoring of ARIA. 
Revised for accuracy and to ensure 
participant safety. 
Section 8.1 
Content added related to slower dose titration 
has its potential to substantially decrease the 
incidence of ARIA. 
Revised to provide additional detail 
and clarity related to ARIA and 
sample size calculations. 
Section 8.3.1 
Content added to indicate protocol deviations 
will be summarized. 
Revised for clarity and accuracy of 
evaluations. 
Section 8.3.3 
Content added to indicate that the effect of 
dose titration on ARIA will be evaluated. 
Revised for clarity and accuracy of 
evaluations. 
Section 8.3.4 
Revisions to pharmacokinetic (PK) analyses. 
Revised for clarity and accuracy of 
evaluations. 
Section 8.3.6 
Section was added detailing methods for 
immunogenicity analyses. 
Revised to provide additional detail 
and clarity. 
Section 8.3.7 
Revisions to details regarding the interim 
analysis. 
Revised to provide additional detail 
and clarity. 
Section 9, 
Section 9.2 
Section 9 is now entitled, “Data Quality 
Assurance and Protection” due to new 
section added entitled, “Data Protection.” 
Revised to add information 
specifically related to participant 
data protection for compliance with 
EU CTR for trials conducted in the 
EU/EEA. 

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Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Section 14.1 
• Serum pharmacokinetic (PK) and plasma 
samples for biomarkers eliminated at 
Week 13. 
• Serum sample for anti-drug antibodies 
(ADAs) added at Week 5. 
• Lumbar puncture (LP) will now be 
performed at 
 vs. 
 
) Visit. Per revised footnotes z 
and aa following the Screening/Baseline 
Visit, if a participant has an Early 
Termination (ET) Visit an LP should be 
performed at that visit. If not, LP should 
be performed at 
9. 
• Ophthalmological examinations will no 
longer be required Weeks 9, 25, and 41. 
• Footnote c revised to provided additional 
detail for collection of clinical outcome 
assessments (COAs), LP, and 
ophthalmological examinations. 
• Footnote d revised to include information 
related to examinations required for 
u
. 
• Footnote i updated to remove ECG 
information for relocation to footnote p. 
• Footnote i and w revised to include 
updated details re: PK blood sample 
collection. 
• Footnote l revised to include more 
detailed information related to 
neurological examination. 
• Footnote bb revised to include details 
related to performance prior to dosing on 
Day 1/Week 1 unless obtained within 
24 weeks before Day 1/Week 1 in study 
AL002-2. 
• Footnote cc and dd revised to include 
clarifying information related to 
requirements for new Amyloid and Tau 
PET scans and use of historical/existing 
scans. 
Revised to reduce patient burden and 
provide clarification. 

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Amended Protocol 
Sections 
Summary of Change(s) 
Rationale 
Section 14.5 
Appendix with “Country-Specific 
Requirements” was added and includes 
Germany-specific protocol differences. 
Revised to add information 
specifically related to study conduct 
in other countries and for compliance 
with EU CTR for trials conducted in 
the EU/EEA. 
 

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PROTOCOL SYNOPSIS 
Protocol Title: A Multicenter, Long-Term Extension Study to Evaluate the Safety, Tolerability, and 
Efficacy of AL002 in Participants with Alzheimer’s Disease 
Protocol Number: AL002-LTE 
Phase: 2 
Indication: Alzheimer’s disease (AD) 
Objectives and Endpoints: 
Primary Objectives 
Primary Endpoints 
To evaluate the long-term safety and 
tolerability of AL002 in participants 
with AD 
• Incidence of AEs, including AESIs and SAEs 
• Vital signs, clinical laboratory results, and incidence of 
findings from physical, neurological, ophthalmological 
examinations, and ECG 
• C-SSRS 
• MRI abnormalities 
To evaluate the effect of dose 
titration on ARIA 
• Incidence and severity of ARIA in participants undergoing 
titration 
Secondary Objective 
Secondary Endpoints 
To evaluate the PK of AL002 in 
participants with AD 
• Serum PK concentrations of AL002 and relevant PK 
parameters 
To evaluate the effects of AL002 on 
COAs in participants with AD 
• CDR-SB 
• MMSE 
• RBANS-Update 
• ADAS-Cog13 
• ADCS-ADL-MCI 
• ADCOMS 
Exploratory Objectives 
Exploratory Endpoints 
To evaluate the effects of AL002 on 
biomarkers in participants with AD 
• Levels of sTREM2 in CSF and/or plasma 
• Levels of biomarkers related to microglia function in CSF 
and/or plasma (eg, CSF1R, IL1RN, osteopontin, YKL40) 
• Levels of biomarkers related to AD pathology in CSF 
and/or plasma (eg, Aβ40, Aβ42, pTau, tTau) 
• Levels of neurodegeneration biomarkers in plasma and/or 
CSF (eg, NfL) 
• Brain volume, assessed by volumetric MRI 
• Brain pathological Tau burden as assessed by longitudinal 
Tau PET for participants who agree to participate in the 
optional assessment only 

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• Brain amyloid burden as assessed by longitudinal Amyloid 
PET scanning for participants who agree to participate in 
the optional assessment only 
To evaluate immunogenicity of 
AL002 in participants with AD 
• 
Incidence of ADAs 
Aβ40=amyloid beta (1-40); Aβ42=amyloid beta (1-42); AD=Alzheimer’s disease; ADA=anti-drug antibodies; 
ADAS-Cog13=Alzheimer’s Disease Assessment Scale-Cognitive Subscale; ADCOMS=Alzheimer’s Disease 
Composite Score; ADCS-ADL-MCI=Alzheimer’s Disease Cooperative Study – Activities of Daily Living – Mild 
Cognitive Impairment Scale; AE=adverse event; AESI=adverse event of special interest; ARIA=amyloid-related 
imaging abnormality; CDR-SB=Clinical Dementia Rating – Sum of Boxes; COA=clinical outcome assessment; 
CSF=cerebrospinal fluid; CSF1R=colony stimulating factor 1 receptor; C-SSRS=Columbia-Suicide Severity 
Rating Scale; ECG=electrocardiogram; IL1RN=interleukin 1 receptor antagonist; LP=lumbar puncture; 
MMSE=Mini-Mental Status Examination; MRI=magnetic resonance imaging; NfL=neurofilament light; 
PD=pharmacodynamic(s); PET=positron emission tomography; PK=pharmacokinetic(s); pTau=phosphorylated 
tau; RBANS-Update=Repeatable Battery for the Assessment of Neuropsychological Status-Update; SAE=serious 
adverse event; sTREM2=soluble triggering receptor expressed on myeloid cells 2; tTau=total tau; 
YKL-40=chitinase 3-like 1. 
 
Note: All participants who consent to the optional lumbar puncture (LP) will have optional CSF collection. In 
addition, CSF will be collected as needed in participants with ARIA. 
Longitudinal amyloid and Tau PET imaging applies to those participants who consent and participate in the 
optional exploratory biomarker assessment. 
Summary of Study Design: 
This is a Phase 2, parallel-group, long-term extension (LTE), dose-blind, global, multicenter study to 
evaluate the long-term safety and efficacy of AL002 in participants with Alzheimer’s disease (AD). 
The study will enroll participants who completed the planned treatment period in AL002-2 (parent 
study). 
Objectives and Endpoints 
The primary objectives of this Phase 2-LTE study (see Table 1) are to evaluate the long-term safety and 
tolerability of AL002 at 3 possible doses (ie, 15 mg/kg, 40 mg/kg, and 60 mg/kg) and to assess the 
effect of a slower dose titration on the incidence and severity of amyloid-related imaging abnormality 
(ARIA). The secondary objectives include the evaluation of pharmacokinetics (PK) of AL002 as well 
as clinical outcome assessments (COAs) in participants with AD. The exploratory objectives of this 
AL002-LTE study are to evaluate biomarkers and further assess the immunogenicity of AL002 in 
participants with AD. 
Safety will be assessed through monitoring of adverse events (AEs) (including adverse events of 
special interest [AESIs] and serious adverse events [SAEs]), changes in laboratory and vital sign 
values, incidence of findings from physical, neurological, electrocardiogram (ECG), magnetic 
resonance imaging (MRI), ophthalmological examinations, and reports of suicidal ideation or behavior. 
Incidence and severity of ARIA will be assessed in participants undergoing titration. Participants’ 
serum PK will be assessed for investigation of exposure-response and exposure-safety relationships. 
Blood samples for assessment of anti-drug antibodies (ADA) will be taken throughout the study. 
Biomarkers will be assessed from fluid (blood/plasma, cerebrospinal fluid (CSF)), and imaging (MRI, 
optional tau positron emission tomography (PET) with tau radiotracer fluorine-18 MK-6240 ([18F]MK-
6240), and Amyloid PET). Longitudinal CSF, Tau PET and Amyloid PET will be assessed for all 
participants who consent to these optional assessments. Those who did not previously opt-in to these 
procedures in AL002-2 may choose to either opt-in or opt-out in this AL002-LTE study. 

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Investigational Plan 
The first dose of the AL002-LTE study should be within the 4-week ±5-day window of the last dose of 
the parent study, to maintain continuity of study treatment. Delays of the first AL002-LTE dose beyond 
that window will constitute protocol deviations. 
Surveillance for treatment-emergent ARIA will be accomplished with post-baseline MRI scans as 
described in the Schedule of Assessments (see Table 9). Additional Baseline MRIs are required if the 
last MRI occurred more than 90 days prior to the first dose on Day 1/Week 1 of AL002-LTE. 
Participants who were randomized to active treatment in the parent study will remain at their 
previously assigned dose. AL002 will be administered every 4 weeks for up to 48 weeks. Dosing 
duration may be extended beyond this time through a protocol amendment, within the context of 
emerging favorable safety data. 
Those who are conducting the efficacy assessments, including study staff, the Investigator, and 
Sponsor will remain blinded to dose assignments throughout the duration of the AL002-LTE study. 
The Titration Cohort refers to the participants who were randomized to placebo in the parent study 
AL002-2. They will receive an initial starting dose of  mg/kg that will be increased to reach the target 
dose of 0 mg/kg per Titration Algorithm 1: 
Titration Algorithm 1: Starting Dose: 6 mg/kg (See Table 2) 
Week 
 
 
 
5 
AL002 
Dose 
 mg/kg 
 mg/kg 
 mg/kg 
 mg/kg 
The evaluation of dosing and its relationship to safety and ARIA within the Titration Cohort will occur 
only with the unblinded pharmacist, the unblinded pharmacy monitor, the unblinded clinical research 
organization (CRO) staff, and unblinded safety management team at Alector. ARIA monitoring and 
management will be consistent with the procedures outlined in the parent study. Additional information 
about ARIA safety monitoring is described in Section 7.6.4 and Section 7.11. 
If emerging data suggests that Titration Algorithm 1 is not effectively reducing the incidence or 
severity of ARIA, a lower starting dose of  mg/kg may be considered upon determination of the safety 
management team. In the event that a decision is made to lower the starting dose, all subsequent 
participants previously randomized to placebo in the parent study AL002-2 entering this AL002-LTE 
study will be treated with an initial starting dose of 2 mg/kg and will be administered AL002 every 4 
weeks by intravenous (IV) infusion using an up-titration algorithm to reach the target dose of 0 mg/kg 
per Titration Algorithm 2: 
Titration Algorithm 2: Starting Dose:  mg/kg (See Table 3) 
Week 
 
 
 
 
 
AL002 
Dose 
 mg/kg 
 mg/kg 
 mg/kg 
 mg/kg 
 mg/kg 
Independent Data Monitoring Committee 
The iDMC will perform the safety review of all available safety and tolerability data (including from 
the MRI, neurological, and ophthalmological examinations) from all participants in an unblinded 

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manner approximately every 6 months. The iDMC may convene on an ad-hoc basis, as required, to 
review cumulative safety data. 
Description of Study Periods and Visits: 
Screening/Baseline Period: Prior to AL002-LTE Study Entry (from Day -28 to Day -1) 
As described in the sections above, the participant and/or their study partner may sign the informed 
consent/assent for AL002-LTE during the final dosing visit of the parent study. This will mark the 
beginning of the screening/baseline period for AL002-LTE. Required safety and/or eligibility 
assessments may be obtained at any time prior to dosing on Day 1/Week 1. The screening/baseline 
period may also be utilized to obtain any efficacy assessments (eg, COAs) that were not collected from 
the parent study in the last 12 weeks prior to Day1/Week 1. For those participating in the amyloid or 
Tau PET sub-studies in the AL002-2 trial, a new longitudinal amyloid and Tau PET imaging will be 
required if the last timepoint from the parent study was taken more than 24 weeks prior to Day 1/Week 
1. Baseline MRIs are required if the last MRI occurred more than 90 days prior to the first dose on Day 
1/Week 1 of AL002-LTE. For those participating in optional CSF sampling, an optional LP will need 
to be collected prior to Day 1/Week 1 if it has been more than 12 weeks since the last evaluation. The 
C-SSRS must be completed during the screening/baseline period. 
Once eligibility is confirmed and the appropriate safety assessments have been collected, enrollment 
can occur any time after signing the informed consent and prior to the AL002-LTE first dose on Day 
1/Week 1. 
Participants will be offered the opportunity to consent for the optional exploratory biomarker 
assessments (CSF sampling, longitudinal Amyloid PET and Tau PET) even if they did not previously 
agree in the parent study. Details for the optional PET imaging assessments including objectives, 
eligibility criteria, sample collection, and imaging specifications are provided in the PET Imaging 
Procedures Manual. Consent for the optional assessments will be documented. Participation in the 
optional PET imaging procedures will be allowed according to local country regulations. The 
screening/baseline period can be utilized to capture the initial timepoint, which will serve as the 
participant’s baseline and will not be used to determine eligibility. 
Treatment Period (Day 1/Week 1 to Week 49) 
All participants will be treated for 48 weeks. Dosing duration may be extended via a protocol 
amendment based on emerging data and upon consultation with both the Principal Investigator and 
Sponsor. AL002 will be administered via IV infusion at the site on Day 1/Week 1 and every 4 weeks 
thereafter. To further mitigate ARIA risks, all participants who were previously receiving placebo in 
the AL002-2 study will be dosed according to Titration Algorithm 1 (Table 2) with a starting dose of 
 mg/kg. Based on review of the safety data, Titration Algorithm 2 (Table 3) may be implemented with 
a starting dose of  mg/kg to attempt to further reduce ARIA risk. Assessments will be performed at 
Day 1/Week 1 and throughout the treatment period until the end of study (EOS) participation. The full 
Schedule of Assessments is provided in Table 9. 
ARIA Monitoring and Management 
Surveillance for treatment-emergent ARIA will be accomplished with post-baseline MRI scans as 
described in the Schedule of Assessments (see Table 9). To maintain the blind to participants’ original 
treatment assignment in the AL002-2 study, all post-baseline MRIs are required for all participants, 
regardless of whether they received AL002 or placebo in the AL002-2 study. The Sponsor may request 
that additional unscheduled MRIs be performed for the detection and follow-up of ARIA. 
If new or worsening ARIA is observed on any of these post-baseline MRIs, dosing should be managed 
as prescribed in the Dosing Guidelines for ARIA (see Table 8). 

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Participants with new or worsening radiographic evidence of ARIA on post-baseline MRI scans should 
be evaluated for neurological signs or symptoms during an unscheduled visit. 
All new cases of ARIA-E and/or new cases of ARIA-H will require unscheduled MRI scans every 
4-6 weeks until ARIA-E has resolved and/or ARIA-H has stabilized without new findings. An 
Amyloid PET scan may also be requested after the first occurrence of ARIA-E. An unscheduled LP for 
CSF analysis may be requested after any occurrence of ARIA-E and/or ARIA-H. 
End of Study (EOS) Visit 
When a participant completes all study visits and procedures up to and including the last visit of their 
planned treatment period, an EOS Visit will follow 8 weeks after this final treatment period visit. All 
outstanding assessments will be completed within the specified timepoints as indicated in Table 9. 
Early Termination (ET) Visit 
An ET Visit is performed only in cases where the participant is prematurely discontinued from 
the study for any reason. If the participant withdraws or is discontinued from the study for any 
reason, the ET must be completed no longer than 4 to 8 weeks after the last administered dose. 
All safety evaluations, efficacy, biomarker, PK and ADA assessments must be completed at 
this visit. See Table 9 footnotes for additional information. 
Study Sites: 
Multicenter study with sites in North America, Australia, Europe, and Argentina. 
Planned Number of Participants: 
All participants who have completed the planned treatment period in the parent study, AL002-2, are 
invited to participate in this LTE study. Enrollment is optional and participation may be offered at the 
discretion of the Investigator. 
Participant Selection: 
Eligibility for study inclusion will be limited to participants who completed the planned treatment 
period in the parent study AL002-2. Participants must consent to this AL002-LTE study and complete 
all outstanding assessments from AL002-2 prior to Day 1/Week 1 of the AL002-LTE study. 
Criteria for Inclusion and Exclusion: 
Inclusion Criteria 
Each participant must meet all of the following criteria to be enrolled in this study: 
1. The participant has completed the planned treatment period in the AL002-2 study. Completion 
of the planned treatment period is defined as any participant who did not prematurely and 
permanently discontinue the study drug in the AL002-2 study. 
2. The participant is willing and able to give informed consent. Where local regulations permit 
inclusion of participants deemed not able to provide informed consent, a legally authorized 
representative must provide informed consent on his or her behalf, and the participant must 
provide assent, in accordance with the local regulations, guidelines, and institutional review 
board or independent ethics committee. 
3. Female participants must be nonpregnant and nonlactating, and 1 of the following conditions 
must apply: 
a. Participant is not a woman of childbearing potential (WOCBP) (either surgically 
sterilized, or physiologically incapable of becoming pregnant, or at least 1-year 
postmenopausal [amenorrhea duration of 12 consecutive months with no identified 
cause other than menopause]). 

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b. Participant is a WOCBP and agrees to use an acceptable contraceptive method from 
screening until 12 weeks after the last dose of study drug. Acceptable contraception is 
defined as using hormonal contraceptives or an intrauterine device combined with at 
least 1 of the following forms of contraception: a diaphragm or cervical cap, or a 
condom, or the sole sexual partner to a vasectomized male. Vasectomized males must 
have received medical assessment of surgical success. In addition, total abstinence, in 
accordance with the lifestyle of the participant, is acceptable. 
c. A WOCBP must have a serum pregnancy test conducted at screening. Additional 
requirements for pregnancy testing during and after study intervention are described in 
the Schedules of Assessments. 
4. Male participants must agree to use acceptable contraception and not donate sperm from 
screening until 12 weeks after the last dose of study drug. Acceptable contraception for the 
male participant when having sexual intercourse with a WOCBP who is not currently pregnant 
is defined as using a condom. In addition, WOCBP partners must use hormonal contraceptives 
or an intrauterine device. Vasectomized male participants should have received medical 
assessment of surgical success. 
5. Participant weighs ≤120 kg; body mass index (BMI) is between 18.5 and 34.9 kg/m2 inclusive. 
6. The participant has availability of a person (“study partner”) who, in the Investigator’s opinion, 
has frequent and sufficient contact with the participant (eg, at least 10 hours per week of in 
person contact), is able to provide accurate information regarding the participant’s cognitive 
and functional abilities, agrees to provide information at clinic visits (which require partner 
input for scale completion), and signs the necessary consent form. 
a. The study partner must have sufficient cognitive capacity, in the Investigator’s opinion, 
to accurately report upon the participant’s behavior, cognitive, and functional abilities. 
The study partner should be in sufficiently good general health, in the Investigator’s 
opinion, to have a high likelihood of maintaining the same level of interaction with the 
participant and participation in study procedures throughout the study duration. 
b. Every effort should be made to have the same study partner participate throughout the 
duration of the study, and to have the same study partner as in the parent study. 
7. The participant and study partner are fluent in the language of the tests used at the study site as 
assessed by site personnel. 
8. The participant is willing and able to complete all aspects of the study (including MRI). The 
participant should be capable of completing assessments either alone or with the help of the 
study partner. Participants whose disease has progressed such that they cannot complete the 
efficacy assessments may participate in the study for assessment of safety. 
9. The participant has adequate visual and auditory acuity, in the Investigator’s opinion, sufficient 
to perform the neuropsychological testing (corrective lenses and hearing aids are permitted). 
10. Participant agrees not to donate blood or blood products for transfusion for the duration of the 
study and for 1 year after the final dose of study drug. 
Inclusion criteria for participants in the optional Tau PET imaging assessment with [18F]MK-6240 
only: 
11. Participant has not had excessive radiation exposure prior to enrollment in the trial, as defined 
by local standards. 
12. [18F]MK-6240 is available to the PET imaging center based on manufacturing distribution 
network and local regulations. 
Inclusion criteria for participants in the optional longitudinal Amyloid PET imaging assessment only: 

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13. Participant has not had excessive radiation exposure prior to enrollment in the trial, as defined 
by local standards. 
14. An approved amyloid radiotracer is available to the PET imaging center based on 
manufacturing distribution network and local regulations. 
Exclusion Criteria 
Participants are excluded who meet any of the following exclusion criteria: 
1. 
Participants deemed not able to provide consent or assent by the Investigator or by local 
regulations. 
2. 
Participants who were prematurely and permanently discontinued from treatment in the parent 
study for safety reasons. 
3. 
The participant has MRI evidence of: 
a. >2 lacunar infarcts. 
b. Any territorial infarct >1 cm3. 
c. White matter hyperintense lesions on the FLAIR sequence that correspond to an 
overall Fazekas score of 3. 
d. Participants who have an increase in their number of microbleeds, since the previous 
screening/ baseline MRI in the AL002-2 study and >5, should be discussed with the 
Medical Monitor. 
e. Participants who have developed ARIA-E and ARIA-H in the parent study and who 
were permitted to continue dosing according to the ARIA management guidelines, will 
not be excluded from participation in the AL002-LTE, on the basis of microbleeds or 
hemosiderosis. 
4. 
Anticoagulant medications other than antiplatelet agents are prohibited within 90 days of 
screening and throughout the study. Short-term use of anticoagulants to treat an emergent 
medical need is permitted. Treatment with platelet anti-aggregation agents such as aspirin, 
clopidogrel, or dipyridamole is permitted. 
5. 
Participants taking any passive immunotherapy (eg, immunoglobulin) or other long-acting 
biologic agent that is under evaluation or approved to prevent or postpone cognitive decline. 
6. 
Participation in the AL002-LTE is deemed inappropriate for any reason per Investigator 
discretion. 
7. 
Participant agrees not to receive any investigational treatment, other than AL002, during the 
study. 
Clinical Outcome Assessments – Neurocognitive and Functional Tests: 
The following neurocognitive and functional tests (described in Section 14.2) will be performed 
according to the guidelines set forth in the Site Rater Manual. Neurocognitive and functional tests will 
be performed prior to study drug administration (if applicable) and prior to any stressful procedures 
(eg, blood collections, LPs, imaging). Blood collection can be considered a stressful procedure for a 
participant, according to the Investigator’s clinical judgment. 
• Clinical Dementia Rating (CDR) 
• Mini-Mental Status Examination (MMSE) 
• Repeatable Battery for the Assessment of Neuropsychological Status – Update 
(RBANS-Update) 
• Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog13) 

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• Alzheimer’s Disease Cooperative Study-Activities of Daily Living – Mild Cognitive 
Impairment Scale (ADCS-ADL-MCI) 
If a participant is taking intermittent or short-term regimens of medications known to impair 
consciousness or cognition, such medication must be stopped 2 days or 5 half-lives (whichever is 
longer) prior to any cognitive or behavioral assessment. Use of cannabinoids (other than cannabidiol) is 
prohibited within 72 hours prior to any cognitive or behavioral assessment. 
Safety Assessments: 
Safety assessments will consist of monitoring incidence of AEs, changes in vital signs and clinical 
laboratory results, incidence findings of physical, neurological, and ophthalmological exams, ECGs, 
suicidality via the Columbia-Suicide Severity Rating Scale (C-SSRS), and MRI abnormalities (see 
Schedule of Assessments in Table 9). 
This study will also evaluate the effect of a slower titration regimen starting at a lower dose than in the 
parent study on the incidence and severity of ARIA in those participants who were assigned to placebo 
in the AL002-2 study. 
Biomarker Assessments: 
The exploratory biomarker endpoints for this study are presented in Section 2 and Section 6.6. 
The biomarker assessments will consist of, but are not limited to, blood-based biomarkers, CSF-based 
biomarkers, and imaging biomarkers, as follows: 
Blood-based biomarkers: 
• Soluble triggering receptor expressed in myeloid cells 2 (sTREM2) in plasma 
• Plasma biomarkers relevant to AD (eg, amyloid beta 1-42 [Aβ42], amyloid beta 1-40 [Aβ40], 
total tau [tTau], phosphorylated tau [pTau], neurofilament light [NfL]) 
CSF-based biomarkers (those participants who consent to the optional LPs only): 
• sTREM2 in CSF 
• CSF biomarkers relevant to AD (eg, Aβ42, Aβ40, tTau, pTau, NfL) and to microglia function 
(eg, chitinase 3-like 1 [YKL-40], osteopontin) 
• Other exploratory biomarkers 
Imaging biomarkers: 
• MRI measures 
• Optional longitudinal amyloid and Tau PET imaging measures 
Timing and frequency of all biomarker assessments are presented in the Schedule of Assessments 
(Table 9). 
Pharmacokinetic and Anti-drug Antibody Assessments: 
PK blood collection will be performed, and AL002 concentrations will be measured. Blood samples for 
assessment of ADA will be taken throughout the study. 

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Statistical Methods: 
All data for participants will be listed as collected. Analyses may combine the data of the parent study 
with the data of this AL002-LTE study. Missing data will not be imputed, unless otherwise specified in 
the statistical analysis plan (SAP). The SAP will provide further details regarding the analysis sets and 
planned analysis methodologies to address all study objectives. Continuous data will be summarized 
using an 8
 
[
, unless otherwise specified in the SAP. 
Categorical data will be summarized using c
s), unless otherwise specified in the 
SAP. For additional information, see Section 8. 
 

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TABLE OF CONTENTS 
PROTOCOL SIGNATURE PAGE ............................................................................................. 2 
DECLARATION OF INVESTIGATOR ..................................................................................... 3 
SUMMARY OF CHANGES FROM PREVIOUS VERSION ..................................................... 4 
PROTOCOL SYNOPSIS .......................................................................................................... 11 
LIST OF ABBREVIATIONS.................................................................................................... 26 
1. 
INTRODUCTION .................................................................................................. 29 
1.1. 
Background ............................................................................................................ 29 
1.2. 
Summary of Nonclinical and Clinical Studies ......................................................... 30 
1.2.1. 
Nonclinical Studies ................................................................................................. 30 
1.2.2. 
Clinical Studies....................................................................................................... 32 
1.3. 
Summary of Risks and Benefits .............................................................................. 33 
1.4. 
AL002 Dosage Determination ................................................................................ 34 
1.5. 
Participant Population ............................................................................................. 35 
2. 
OBJECTIVES AND ENDPOINTS ......................................................................... 36 
3. 
INVESTIGATIONAL PLAN ................................................................................. 38 
3.1. 
Study Design .......................................................................................................... 38 
3.2. 
Description of Study Periods and Visits .................................................................. 39 
3.2.1. 
Screening/Baseline Period ...................................................................................... 39 
3.2.2. 
Treatment Period .................................................................................................... 39 
3.2.3. 
Unscheduled Visits ................................................................................................. 40 
3.2.4. 
End of Study/Week 57 Visit ................................................................................... 40 
3.2.5. 
Early Termination Visit .......................................................................................... 40 
4. 
PARTICIPANT SELECTION AND WITHDRAWAL CRITERIA ........................ 42 
4.1. 
Inclusion Criteria .................................................................................................... 42 
4.2. 
Exclusion Criteria ................................................................................................... 44 
4.3. 
Withdrawal of Participants from Study ................................................................... 44 
4.3.1. 
Withdrawal from Study Drug .................................................................................. 44 
4.3.2. 
Withdrawal from Study .......................................................................................... 45 
5. 
STUDY DRUG ...................................................................................................... 47 
5.1. 
Method of Assigning Participants to Treatment Groups .......................................... 47 
5.1.1. 
Administration Instructions ..................................................................................... 48 

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5.2. 
Identity of Study Drug and PET Radiotracers ......................................................... 49 
5.2.1. 
Study Drug ............................................................................................................. 49 
5.2.1.1. 
Study Drug Packaging and Labeling ....................................................................... 49 
5.2.2. 
[18F]MK-6240 Tau PET Radiotracer ....................................................................... 49 
5.2.3. 
Amyloid PET Radiotracer ....................................................................................... 49 
5.2.4. 
Investigational and Auxiliary Medicinal Products Used in AL002-LTE .................. 50 
5.3. 
Management of Clinical Supplies ........................................................................... 51 
5.3.1. 
Study Drug Supply ................................................................................................. 51 
5.3.2. 
Study Drug Storage ................................................................................................ 51 
5.3.3. 
Study Drug Accountability ..................................................................................... 51 
5.3.4. 
Study Drug Return or Disposal ............................................................................... 51 
5.3.5. 
Unauthorized AMP Accountability, Return, and/or Disposal .................................. 52 
5.4. 
Blinding.................................................................................................................. 52 
5.4.1. 
Blinding of the Parent Study AL002-2 and AL002-LTE ......................................... 52 
5.4.2. 
Personnel Who Are Unblinded Throughout the Study ............................................. 52 
5.4.3. 
Breaking the Blind by the Investigator .................................................................... 53 
5.5. 
Prior and Concomitant Therapy .............................................................................. 53 
5.6. 
Rescue Medication ................................................................................................. 54 
6. 
STUDY ASSESSMENTS AND PROCEDURES ................................................... 55 
6.1. 
Timing of Study Drug Administration and Procedures ............................................ 55 
6.2. 
Sample Collections ................................................................................................. 56 
6.3. 
Safety Assessments................................................................................................. 56 
6.3.1. 
Adverse Events, Adverse Events of Special Interest, and Serious Adverse 
Events..................................................................................................................... 57 
6.3.2. 
Concomitant Medications ....................................................................................... 57 
6.3.3. 
Demographics......................................................................................................... 57 
6.3.4. 
Medical History and Social History ........................................................................ 57 
6.3.5. 
Physical Examinations ............................................................................................ 58 
6.3.6. 
Neurological Examinations ..................................................................................... 58 
6.3.7. 
Ophthalmological Examinations ............................................................................. 58 
6.3.8. 
Vital Signs .............................................................................................................. 59 
6.3.9. 
Electrocardiograms ................................................................................................. 59 
6.3.10. 
Clinical Laboratory Assessments ............................................................................ 59 

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6.3.11. 
Columbia-Suicide Severity Rating Scale ................................................................. 60 
6.3.12. 
Magnetic Resonance Imaging ................................................................................. 60 
6.4. 
Efficacy Assessments ............................................................................................. 61 
6.5. 
Pharmacokinetic and Anti-Drug Antibody Assessments .......................................... 62 
6.6. 
Biomarker Assessments .......................................................................................... 62 
6.6.1. 
Fluid Biomarker Assessments ................................................................................. 62 
6.6.1.1. 
Blood Biomarker Sampling .................................................................................... 62 
6.6.1.2. 
Optional Cerebrospinal Fluid Sampling .................................................................. 63 
6.6.2. 
Imaging Assessments.............................................................................................. 63 
6.6.2.1. 
Optional PET Imaging Procedures .......................................................................... 63 
7. 
ASSESSMENT OF SAFETY ................................................................................. 65 
7.1. 
Definition of Adverse Event ................................................................................... 65 
7.2. 
Adverse Events of Special Interest .......................................................................... 66 
7.3. 
Definition of Serious Adverse Events ..................................................................... 66 
7.3.1. 
Protocol-Specific Disease Progression Adverse Event and Serious Adverse 
Event Reporting Requirements ............................................................................... 67 
7.4. 
Definition of Clinical Laboratory Abnormalities and Other Abnormal 
Assessments as Adverse Events/Serious Adverse Events ........................................ 67 
7.5. 
Assessment of Adverse Events ............................................................................... 67 
7.5.1. 
Assessment of Adverse Event/Serious Adverse Event Severity ............................... 67 
7.5.2. 
Assessment of Causality ......................................................................................... 68 
7.6. 
Recording of Adverse Events .................................................................................. 69 
7.6.1. 
Eliciting and Documenting the Adverse Events ...................................................... 69 
7.6.2. 
Recording the Action Taken with Study Drug in Response to AE/SAE ................... 69 
7.6.3. 
Recording the Outcome and Follow-up of Participants Reporting an 
AE/SAE.................................................................................................................. 69 
7.6.4. 
Recording of ARIA-H and ARIA-E as Adverse Events of Special Interest.............. 70 
7.6.5. 
Recording of 
s as Adverse Events of Special Interest .................................... 70 
7.7. 
Reporting Adverse Events ...................................................................................... 70 
7.7.1. 
Adverse Events and Serious Adverse Events Reporting .......................................... 70 
7.8. 
Safety Monitoring ................................................................................................... 71 
7.9. 
Follow-Up of Adverse Events and Serious Adverse Events..................................... 72 
7.10. 
Infusion Reactions .................................................................................................. 72 

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7.11. 
Amyloid-Related Imaging Abnormalities................................................................ 73 
7.11.1. 
Schedule of MRI Surveillance for ARIA................................................................. 74 
7.11.2. 
Participant Follow-up for ARIA Events .................................................................. 74 
7.12. 
.................................................................................................................. 77 
7.13. 
General Safety Monitoring...................................................................................... 77 
7.13.1. 
Special Situations ................................................................................................... 77 
7.13.2. 
Pregnancy ............................................................................................................... 78 
7.13.3. 
Breastfeeding .......................................................................................................... 79 
8. 
STATISTICAL METHODS AND ANALYSIS PLAN ........................................... 80 
8.1. 
Sample Size Calculations ........................................................................................ 80 
8.2. 
Analysis Sets .......................................................................................................... 80 
8.3. 
Statistical Analysis Methodology ............................................................................ 80 
8.3.1. 
General Analyses .................................................................................................... 80 
8.3.1.1. 
Disposition of Participants ...................................................................................... 80 
8.3.1.2. 
Protocol Deviations ................................................................................................ 81 
8.3.1.3. 
Demographics and Other Baseline Characteristics .................................................. 81 
8.3.1.4. 
Prior and Concomitant Medications ........................................................................ 81 
8.3.2. 
Efficacy Analyses ................................................................................................... 81 
8.3.3. 
Safety Analyses ...................................................................................................... 81 
8.3.4. 
Pharmacokinetic Analyses ...................................................................................... 81 
8.3.5. 
Exploratory Biomarker Analyses ............................................................................ 82 
8.3.6. 
Immunogenicity Analyses....................................................................................... 82 
8.3.7. 
Interim Analyses ..................................................................................................... 82 
9. 
DATA QUALITY ASSURANCE AND PROTECTION ........................................ 83 
9.1. 
Data Management ................................................................................................... 83 
9.2. 
Data Protection ....................................................................................................... 83 
10. 
ETHICS.................................................................................................................. 86 
10.1. 
Independent Ethics Committee or Institutional Review Board ................................. 86 
10.2. 
Ethical Conduct of the Study .................................................................................. 86 
10.3. 
Participant Information and Consent ....................................................................... 86 
11. 
INVESTIGATOR’S OBLIGATIONS..................................................................... 88 
11.1. 
Confidentiality ........................................................................................................ 88 
11.2. 
Financial Disclosure and Obligations ...................................................................... 88 

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11.3. 
Investigator Documentation .................................................................................... 88 
11.4. 
Study Conduct ........................................................................................................ 89 
11.5. 
Adherence to Protocol ............................................................................................ 89 
11.6. 
Adverse Events and Study Report Requirements..................................................... 89 
11.7. 
Investigator’s Final Report...................................................................................... 89 
11.8. 
Records Retention .................................................................................................. 89 
11.9. 
Publications ............................................................................................................ 90 
12. 
STUDY MANAGEMENT ..................................................................................... 91 
12.1. 
Monitoring ............................................................................................................. 91 
12.1.1. 
Independent Data Monitoring Committee ............................................................... 91 
12.1.2. 
Monitoring of the Study .......................................................................................... 91 
12.1.3. 
Inspection of Records ............................................................................................. 92 
12.2. 
Study Termination .................................................................................................. 92 
12.3. 
Final Report ............................................................................................................ 92 
13. 
REFERENCE LIST ................................................................................................ 93 
14. 
APPENDICES ........................................................................................................ 96 
14.1. 
Appendix 1: Schedule of Assessments .................................................................... 96 
14.2. 
Appendix 2: Clinical Outcome Assessments – Neurocognitive and 
Functional Tests ................................................................................................... 101 
14.2.1. 
Clinical Dementia Rating ...................................................................................... 101 
14.2.2. 
Mini-Mental Status Examination .......................................................................... 101 
14.2.3. 
Repeatable Battery for the Assessment of Neuropsychological Status ................... 101 
14.2.4. 
Alzheimer's Disease Assessment Scale-Cognitive Subscale .................................. 101 
14.2.5. 
Alzheimer's Disease Cooperative Study-Activities of Daily Living – Mild 
Cognitive Impairment Scale .................................................................................. 101 
14.2.6. 
Alzheimer’s Disease Composite Score (ADCOMS) .............................................. 102 
14.3. 
Appendix 3: Management of Infusion-Related Reactions ...................................... 102 
14.4. 
Appendix 4: Adaptation of Trial Protocol During COVID-19 Pandemic ............... 103 
14.4.1. 
Background .......................................................................................................... 103 
14.4.2. 
Implementation of COVID-19 .............................................................................. 104 
14.4.3. 
Study Screening/Baseline Period .......................................................................... 104 
14.4.4. 
Essential On-Site Assessments and Remote Visits (Via Phone or Video) .............. 104 
14.4.4.1. 
On-site Essential Assessments .............................................................................. 104 

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14.4.4.2. 
Remote Essential Assessments (Telemedicine or Televisits) ................................. 105 
14.4.5. 
On-Site Assessments Unable to be Completed at Scheduled Visits ....................... 107 
14.4.6. 
COVID-19 Reporting ........................................................................................... 107 
14.4.7. 
Remote Consent ................................................................................................... 107 
14.4.8. 
Remote Source Document Verification ................................................................. 107 
14.4.9. 
Home Visits .......................................................................................................... 108 
14.5. 
Appendix 5: Country-Specific Requirements ........................................................ 109 
14.5.1. 
Germany-Specific Protocol Differences ................................................................ 109 
LIST OF TABLES 
Table 1: 
Study Objectives and Endpoints.............................................................................. 36 
Table 2: 
Titration Algorithm 1 (Starting Dose:  mg/kg) ...................................................... 47 
Table 3: 
Titration Algorithm 2 (Starting Dose:  mg/kg) ...................................................... 48 
Table 4: 
Comprehensive List of Investigational and Auxiliary Medicinal Products 
(IMP and AMP) Used in AL002-LTE Study ........................................................... 50 
Table 5: 
Clinical Laboratory Safety Assessments ................................................................. 60 
Table 6: 
Adverse Event Grading Criteria .............................................................................. 68 
Table 7: 
ARIA-E and ARIA-H Radiographic Severity Scales ............................................... 74 
Table 8: 
Dosing Guidelines for ARIA .................................................................................. 76 
Table 9: 
Schedule of Assessments ........................................................................................ 96 
Table 10: Guidelines for Management of Acute Infusion-related Reactions .......................... 102 
 

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LIST OF ABBREVIATIONS 
Abbreviation  
Term or Definition 
[18F]MK-6240 
fluorine-18 MK-6240 
Aβ 
amyloid beta 
Aβ40 
amyloid beta (1-40) 
Aβ42 
amyloid beta (1-42) 
AD 
Alzheimer’s disease 
ADAs 
anti-drug antibodies 
ADAS-Cog13 
Alzheimer’s Disease Assessment Scale-Cognitive Subscale 
ADCOMS 
Alzheimer’s Disease Composite Score 
ADCS-ADL-MCI 
Alzheimer’s Disease Cooperative Study-Activities of Daily Living – Mild 
Cognitive Impairment Scale 
AE 
adverse event 
AESI 
adverse event of special interest 
AMP 
auxiliary medicinal product 
APOE 
apolipoprotein E 
APOE e4 
apolipoprotein E epsilon4 
ARIA 
amyloid-related imaging abnormality 
ARIA-E 
amyloid-related imaging abnormality – edema 
ARIA-H 
amyloid-related imaging abnormality – hemosiderin deposits 
AUC 
area under the concentration-time curve 
BMW 
Brain MRI Worksheet  
BP 
blood pressure 
CDR 
Clinical Dementia Rating 
CDR-SB 
Clinical Dementia Rating – Sum of Boxes 
CFR 
Code of Federal Regulations 
Cmax 
maximum concentration 
CNS 
central nervous system 
COA 
clinical outcome assessment 
COVID-19 
coronavirus disease 2019 
CRA 
clinical research associate 
CRO 
clinical research organization 
CSF 
cerebrospinal fluid 
CSF1R 
colony stimulating factor 1 receptor 

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Abbreviation  
Term or Definition 
CSR 
clinical study report 
C-SSRS 
Columbia-Suicide Severity Rating Scale 
CT 
computerized tomography  
CTCAE 
Common Terminology Criteria for Adverse Events 
DLAE 
dose-limiting AE 
ECG 
electrocardiogram 
eCRF 
electronic case report form 
EDC 
electronic data capture 
EEA 
European Economic Area 
EOS 
End of Study 
ET 
early termination 
EU 
European Union 
EU CTD 
European Clinical Trial Directive 
EU CTR 
European Clinical Trials Regulation 
FDA 
(US) Food and Drug Administration 
FLAIR 
fluid-attenuated inversion recovery 
GCP 
Good Clinical Practice 
GLP 
Good Laboratory Practice 
GRE 
gradient-recalled echo 
IB 
Investigator’s Brochure 
ICF 
Informed Consent Form 
ICH 
International Council for Harmonisation of Technical Requirements for 
Pharmaceuticals for Human Use 
iDMC 
independent Data Monitoring Committee 
IEC 
independent ethics committee 
Ig 
immunoglobulin 
IMP 
Investigational medicinal product 
IND 
Investigational New Drug  
IRB 
institutional review board 
IV 
intravenous(ly) 
LP 
lumbar puncture 
LTE 
long-term extension 
MedDRA 
Medical Dictionary for Regulatory Activities 

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Abbreviation  
Term or Definition 
MMSE 
Mini-Mental Status Examination 
MRI 
magnetic resonance imaging 
mCi 
millicurie 
mSv 
millisievert 
NfL 
neurofilament light 
NIA-AA 
National Institute on Aging/Alzheimer’s Association 
NOAEL 
no-observed-adverse-effect level 
 
o
 
PD 
pharmacodynamic(s) 
PE 
physical examination 
PET 
positron emission tomography 
PK 
pharmacokinetic(s) 
pTau 
phosphorylated tau 
QTcF 
QT interval by Fredericia 
RBANS-Update 
Repeatable Battery for the Assessment of Neuropsychological Status – 
Update 
SAE 
serious adverse event 
SAS 
Statistical Analysis System 
SAP 
statistical analysis plan 
SOP 
standard operating procedures 
sTREM2 
soluble triggering receptor expressed on myeloid cells 2 
TREM2 
triggering receptor expressed on myeloid cells 2 
tTau 
total tau 
US 
United States 
WHO DD 
World Health Organization Drug Dictionary 
WOCBP 
woman of childbearing potential 
YKL-40 
chitinase 3-like 1 protein 

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1. 
INTRODUCTION 
1.1. 
Background 
Worldwide, more than 46.8 million people had dementia in 2015, with the largest incidence rates 
in Asia and Europe (Prince 2015). The worldwide prevalence of dementia is expected to exceed 
130 million by 2050. Alzheimer’s disease (AD) is a degenerative brain disease and is the most 
common cause of dementia in the US, affecting approximately 5.8 million Americans as of 2019 
(Alzheimer’s Association Report 2019). Of the top 10 causes of death in the US, AD is the only 
major cause of morbidity and mortality without suitable treatments for preventing, slowing, or 
curing (Alzheimer’s Association Report 2019). 
Current therapies for AD such as acetylcholinesterase inhibitors (eg, donepezil) and 
N-methyl-D-aspartate receptor antagonists (eg, memantine) show only modest and transient 
benefits to cognition and behavior parameters in AD patients but do not slow or halt the 
progression of the disease (Cummings 2004). Recently (June 2021), Aduhelm® (aducanumab) 
and (January 2023) Leqembi® (lecanemab) received US FDA Accelerated Approval for the 
treatment of AD based on the reduction of amyloid and the reasonable possibility for cognitive 
benefit associated with a lower amyloid burden. Leqembi® was converted to full approval by the 
FDA in July 2023. Usage of these therapies is not yet widespread outside of confirmatory 
clinical trials. 
Tau protein has also been identified as one of the key pathological features of AD 
(Grundke-Iqbal 1986; Kosik1986; Wood 1986). Tau is the primary protein composing 
neurofibrillary tangles, and postmortem studies have shown that neurofibrillary tangle density 
correlates with neurodegeneration and cognitive impairment (Duyckaerts 1987; Delaére 1989; 
Duyckaerts 1990; Arriagada 1992; McLean 1999). However, anti-tau disease-modifying 
therapies have not demonstrated success in slowing cognitive decline in Phase 3 clinical trials 
thus far. 
Given the large number of patients with AD and the expected increases in this patient population 
due to an extended life expectancy and a major worldwide growth in the population of older 
adults, an effective treatment for AD remains an urgent unmet medical need. 
Human genetic studies have identified inherited mutations that underlie familial forms of AD, 
but these mutations are rare, occurring in less than 5% of all cases. More recently, large human 
genetic association studies have revealed genetic loci that modify the risk of common sporadic 
forms of AD (Tanzi 2012). Many of these loci encode for proteins expressed primarily on innate 
immune cells, including microglia, macrophages, and dendritic cells. Microglia are the resident 
macrophages of the central nervous system (CNS) and serve protective housekeeping functions 
such as facilitating clearance of cellular debris through phagocytosis, maintaining synapses, and 
secreting growth factors. Thus, in the course of neurodegenerative diseases such as AD, these 
cells may serve an important protective role when activated appropriately. 
The most prominent microglial gene that modifies the risk of common sporadic forms of AD 
encodes for a type I transmembrane protein that is a member of the immunoglobulin (Ig) 
receptor superfamily, known as a triggering receptor expressed on myeloid cells 2 (TREM2). 
TREM2 is an Ig-like receptor that is expressed primarily on myeloid lineage cells, such as 
macrophages, dendritic cells, and microglia (Colonna 2016). TREM2 is thought to play a key 

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role in modulating the innate immune response, such as in response to bacteria in the context of 
infection or to dying neurons and other debris in neurodegenerative disorders including AD 
(Colonna 2016). 
Heterozygous mutations in the TREM2 gene increase the risk of AD by up to 3-fold 
(Guerreiro 2013; Jonsson 2013) and increase the rate at which brain volume shrinks 
(Rajagopalan 2013). 
Recent mouse genetic model studies strongly support a key role for TREM2 in AD, with the 
AD-associated R47H mutation in TREM2 associated with increased pathology 
(Cheng-Hathaway 2018). Similarly, Wang et al (Wang 2015) showed that in the 5xFAD 
transgenic model of AD, deficiency in TREM2 function exacerbated AD pathology. Subsequent 
studies detailed the pathological changes seen in 5xFAD mice lacking one or both copies of 
TREM2, showing a consistent defect in the ability of TREM2 mutant microglia to effectively 
surround and engulf amyloid plaques (Wang 2016; Yuan 2016; Jay 2017a). In these 
TREM2-defective microglia, a reduction in microglia per plaque was associated with more 
diffuse plaques, more axonal damage, and more tau aggregation in the vicinity of plaques 
(Yuan 2016; Leyns 2019). 
Furthermore, TREM2 activation enhances microglial cell survival, proliferation, and 
differentiation, and also regulates microglial chemotaxis and phagocytosis. In the context of AD 
pathology, TREM2 expression positively impacts tau hyperphosphorylation and aggregation and 
reduces synaptic and neuronal loss (Jay 2017b). Conversely, AD pathology is reduced in mice 
overexpressing TREM2 (Lee 2018). 
In summary, the loss of TREM2 function is detrimental as demonstrated in human and mouse 
genetic studies, while conversely, activating TREM2 on microglial cells is protective against 
damage in the process of neurodegeneration. This suggests that application of TREM2 agonistic 
antibodies may potentially slow cognitive decline under pathological conditions. 
Alector’s approach is to utilize a TREM2 agonistic antibody to activate the innate immune 
system, thereby improving the clearance and sequestration of the molecular factors causing AD 
pathology. Alector has developed a humanized therapeutic TREM2 antibody, AL002, with 
optimized agonistic activity. As demonstrated in the data from Alector preclinical studies, 
activating TREM2 with a variant of the study drug can effectively suppress AD pathology in 
animal models. 
AL002 is currently in development and does not have marketing authorization in any country. 
Per the European Medicines Agency (EMA), a Pediatric Investigational Plan Class Waiver is in 
effect for all classes of medicinal products for treatment of AD. 
1.2. 
Summary of Nonclinical and Clinical Studies 
1.2.1. 
Nonclinical Studies 
The pharmacology, pharmacokinetic (PK), and toxicology of AL002 has been comprehensively 
assessed in nonclinical studies. 
Pharmacology studies conducted to date include: (i) in vitro cell-based assays to describe the 
proposed mechanism of action of AL002, (ii) in vivo pharmacology studies evaluating brain 

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target engagement of AL002 in different species, and (iii) correlation of these changes to reversal 
of behavior deficits in mouse models of AD. 
In vitro, AL002 activates human TREM2 expressed in cell lines or primary myeloid cells and 
causes membrane TREM2 down regulation and activation of downstream signal transduction to 
enhance survival of multiple myeloid cell populations. AL002 can also synergize with 
endogenous ligands such as phosphatidylserine and apolipoprotein E (APOE). In vivo, in a 
bacterial artificial chromosome transgenic mouse model with over expressed human TREM2, a 
single-dose of AL002 increased microglia numbers and microglial genes, such as colony 
stimulating factor 1 receptor (CSF1R), in the brain, indicating that peripherally administered 
AL002 is able to activate brain TREM2 signalling. In the Cynomolgus monkey, dose-dependent 
reductions in soluble triggering receptor on myeloid cells 2 (sTREM2) and brain TREM2 were 
observed after either a single intravenous (IV) dose or repeat weekly doses of AL002 indicating 
effective brain target engagement. Moreover, there was a significant increase in CSF1R levels in 
the monkey brain. A second downstream microglial activation marker, osteopontin, was also 
found to be elevated in Cynomolgus monkey cerebrospinal fluid (CSF). In vivo, a variant of 
AL002 reduced disease pathology in a mouse model of AD. 
The Cynomolgus monkey was selected as the nonclinical species for toxicokinetic and 
toxicology evaluations because AL002 binds with similar and high affinities to both human and 
Cynomolgus monkey TREM2, does not bind to rodent TREM2, and lacks pharmacologic 
activity in rodents. 
Nonclinical PK of AL002 was evaluated in single IV dose and preliminary non-GLP repeat-dose 
toxicology studies, as well as part of the 4-week and 26-week repeat-dose GLP toxicology 
studies to guide human clinical dose and regimen selection, and to estimate clinical safety factors 
for the initial Phase 1 first-in-human and Phase 2 multidose clinical studies. After once weekly 
IV administration of AL002 to Cynomolgus monkeys in the 4-week and 26-week GLP studies, 
systemic exposure (as assessed by Cmax and AUC from time 0 to 168 hours) increased slightly 
less than dose proportionally with increasing dose. Some accumulation of AL002 after multiple 
doses in monkeys was observed after weekly dosing. Animals were confirmed to have been 
exposed throughout the duration of the intended exposure period, although anti-drug antibodies 
(ADAs) were identified in some animals in all AL002 dosing groups in both the 4-week and 
26-week GLP studies. 
A preliminary dose range finding study, a GLP repeat-dose (4-week) IV toxicology study, a GLP 
repeat-dose (26-week) IV toxicology study, a GLP tissue cross reactivity study, and a GLP local 
tolerance study have been conducted to characterize the toxicology of AL002. In addition, the 
potential for AL002 to induce cytokine release was studied in vitro. The toxicology program was 
designed to support the proposed clinical trial and to comply with existing regulatory guidance, 
including ICH Tripartite EMA Guideline S6(R1). AL002 was administered by IV slow bolus in 
the toxicology studies to mimic the route of clinical administration in Study AL002-1 
(IV infusion). 
There were no AL002-related adverse findings in the toxicology assessments in the 4-week GLP 
study. IV administration of AL002 at doses up to 250 mg/kg weekly for 4 weeks was well 
tolerated in this study, and the no-observed-adverse-effect level (NOAEL) was 250 mg/kg. 

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In the 26-week GLP study, AL002 administered at doses up to 250 mg/kg weekly was well 
tolerated. AL002-related findings were limited to microscopic observations in the eye and 
consisted of unilateral or bilateral minimal to marked granulomatous inflammation in the ciliary 
body and/or choroid of animals administered 80 or 250 mg/kg, with no corresponding 
ophthalmic findings or associated clinical observations. The NOAEL was 20 mg/kg. 
Local tolerability of AL002 by IV dosing was evaluated in the 4-week and 26-week GLP 
toxicology studies with no findings at the injection site. In addition, a local tolerance study in 
rabbits following a single-dose subcutaneous injection was conducted with no AL002-related 
adverse findings. When incubated with human peripheral blood mononuclear cells in vitro, 
AL002 did not induce cytokine release when compared to isotype control human IgG antibody. 
An in vitro tissue cross reactivity study indicated the distribution of the staining observed was 
very similar between human and monkey. 
Overall, the nonclinical package for AL002 supports the design of this AL002-LTE and the 
overall safety of study participants. 
Nonclinical studies conducted for AL002 are described in further detail in the AL002 
Investigator’s Brochure (IB). 
1.2.2. 
Clinical Studies 
Study AL002-1 assessed the safety, tolerability, PK, and pharmacodynamics (PD) of IV 
administration of AL002 administered as a single-dose to healthy volunteers as well as multiple 
doses to participants with mild to moderate AD. Study AL002-1 was closed to enrollment by 
Alector on 14 May 2020 given the available data already obtained and limitations on enrollment 
due to the coronavirus disease 2019 (COVID-19) pandemic. 
AL002 was studied in 64 healthy volunteers enrolled in the first portion of the AL002-1 study, 
which evaluated single-dose IV infusion administration of AL002 with doses ranging from 0.003 
to 60 mg/kg. All participants in these single-ascending dose cohorts reached the end of their 
dose-limiting adverse event (DLAE) assessment windows. Fifty-three participants were exposed 
to AL002, and 11 participants were on placebo. All participants have completed the study, with 
the exception of 1 participant (60 mg/kg), who withdrew consent after receiving one dose of 
AL002.The second portion of AL002-1 evaluated AL002 administered in multiple doses in 
participants with AD. Due to the closing of enrollment, only 5 of the planned 32 participants 
with AD were enrolled in the multiple dosing part. Three participants (2 on AL002 and 1 on 
placebo) were enrolled on a schedule that evaluated AL002 15 mg/kg weekly for 4 doses. 
Following a protocol amendment, an additional 2 participants (1 on AL002 and 1 on placebo) 
were enrolled on a schedule that evaluated AL002 60 mg/kg every 4 weeks for 2 doses. In this 
study, there were no deaths, no DLAEs, no treatment-related serious adverse events (SAEs), and 
no adverse events of special interest (AESIs). One participant in the pooled placebo group had a 
Grade 3 injury (attributed to trauma) that was serious and was considered unrelated to study 
drug. Two participants in the single-ascending dose part experienced adverse events (AEs) 
considered probably related to AL002 that led to withdrawal of study drug. Overall, AL002 was 
considered generally safe and well tolerated in this trial. 
In the ongoing, randomized, double-blind, placebo-controlled, dose-ranging Phase 2 study, 
AL002-2, the AL002 is administered for up to 96 weeks via IV infusion every 4 weeks. To 

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further mitigate potential risks associated with dosing, enrolled participants are titrated to their 
assigned dose (15 mg/kg over 1 dose, 40 mg/kg over 2 doses, or 60 mg/kg over 3 doses). 
Amyloid-related imaging abnormality – edema (ARIA-E) and amyloid-related imaging 
abnormality – hemosiderin deposits (ARIA-H) have been observed in Study AL002-2, with 
3 cases associated with serious and severe symptoms. Because the serious and severe 
symptomatic cases were in participants with an apolipoprotein E epsilon4/epsilon4 
(APOE e4/e4) genotype (APOE e4/e4) genotype, participants with this genotype are no longer 
participating in this trial. For additional information regarding these cohorts, please refer to 
Section 5 of the IB. 
AL002-LTE is an extension of the ongoing AL002-2 study for all participants who have 
completed the planned treatment period, who are medically stable, and who consent to dosing for 
an additional 49 weeks. Participants who received active treatment in the parent study will 
remain on their current dose in the AL002-LTE study, and participants who received placebo in 
the parent study will be titrated to 
 mg/kg as described in Section 5.1. AL002 will be 
administered to study participants and all procedures related to the study will be performed by 
qualified persons at investigational sites from the parent study (ie, AL002-2). The Investigator, 
the study staff at the site, study participants, participant study partners, and the clinical site 
monitors will remain blinded to the dose of AL002 participants are receiving throughout the 
AL002-LTE study as well as which study drug (AL002 vs. placebo) and dose they received in 
the AL002-2 study. 
1.3. 
Summary of Risks and Benefits 
Based on preclinical observations and evidence reported in the literature, the proposed 
mechanism of action of AL002 (ie, agonism of TREM2) has the potential to alter the course of 
AD progression. Due to a paucity of therapeutic options for preventing, slowing, or curing AD, a 
safe and effective therapy that targets TREM2 without blocking the ability of natural ligands to 
induce an additive or synergistic effect may provide a favorable risk/benefit profile to 
participants with this condition. 
Preclinical toxicology studies evaluating AL002 with long-term, dose-intensive regimens has 
identified ocular toxicity as a potential risk for AL002. Cynomolgus monkeys treated with 
80 mg/kg or 250 mg/kg weekly for 27 doses had postmortem microscopic findings of 
c 
f
 (for additional information, please see Section 4.3 of 
the IB). Because of these findings, 
s has been added as a potential risk to treatment with 
AL002, and all treated participants will be monitored by an eye specialist (see Section 6.4 of the 
IB and Section 6.3.7 in this protocol). In the Phase 1 study (Study AL002-1), eye-related AEs 
have been limited to mild and transient events. 
ARIA-E and ARIA-H have been observed in Study AL002-2, with 3 cases associated with 
serious and severe symptoms as of 15 April 2022. These data are described in the IB, including 
any issued addenda. Additional magnetic resonance imaging (MRI) monitoring has been added 
to this protocol and the Dosing Guidelines for amyloid-related imaging abnormality (ARIA) 
have been updated (Table 8) in addition to the Schedule of Assessments (Table 9). Because the 
serious and severe symptomatic cases occurred in participants with an APOE e4/e4 genotype, 
participants with this genotype are no longer eligible to participate in the parent study AL002-2 

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and are not eligible to participate in this AL002-LTE. MRI surveillance monitoring will be 
conducted for all participants at the beginning of this study to maintain the blind during the dose 
titration. 
For this Phase 2 LTE study, AL002 will be administered for up to 48 weeks via IV infusion and 
is expected to be generally safe and well tolerated. To further mitigate ARIA risks, those who 
were previously on placebo will receive a lower starting dose (  mg/kg) than in the parent trial 
and will slowly titrate up to 
 mg/kg as described in Table 2: 
Titration Algorithm 1 
(Starting Dose: 6 mg/kg) (Titration Algorithm 1). MRI surveillance of ARIA will occur, and 
determination of the absence of incident ARIA will be made before escalating to the next higher 
dose level. If ARIA is observed, a lower  mg/kg starting dose may be implemented at the 
Sponsor’s discretion and communicated to all clinical sites (see Section 5.1). 
Potential risks associated with AL002 administration include u
, infusion-related reactions, 
and immunogenicity (see Section 6.4 of the IB). Identified risks associated with AL002 include 
MRI findings of ARIA-E and ARIA-H (Section 7.2; also see Section 6.4.1 of the IB, 
Version 7.0, Addendum 2). To minimize risks to study participants, careful monitoring of each 
participant will be conducted at time points throughout the study to detect any AEs or safety 
signals through physical, neurological, and ophthalmological examination, and assessment of 
electrocardiogram (ECG) findings, MRI findings, suicidality findings, vital signs, hematology 
and coagulation, chemistry, and urinalysis parameters. AE reporting and review of concomitant 
medication use, and other specific safety assessments, will occur as delineated in the Schedule of 
Assessments (Table 9). Based on the monitoring of AEs, the Sponsor may request an additional 
unscheduled MRI be performed to determine whether symptoms may be due to ARIA or ensure 
early identification of ARIA. Samples to assess the development of ADAs will be collected prior 
to and throughout the treatment period of the study. For more detail on potential and identified 
risks, and overall benefit risk evaluation associated with AL002, see the IB. 
AL002 will be administered to study participants and all procedures related to the study will be 
performed by scientifically and medically qualified persons at investigational sites suitable for 
conducting human studies of this nature. 
Suicidality will be assessed with regular participant interviews using the Columbia-Suicide 
Severity Rating Scale (C-SSRS). Brain MRI (including, but not limited to, fluid-attenuated 
inversion recovery [FLAIR] and T2*-weighted gradient-recalled echo [GRE] sequences) will be 
undertaken to detect the occurrence of brain abnormalities. Please see Section 7 and the Schedule 
of Assessments (Table 9) for a description of ARIA risk mitigation steps and management 
guidelines. 
1.4. 
AL002 Dosage Determination 
In this AL002-LTE study, participants who were previously assigned to active treatment in the 
15 mg/kg, 40 mg/kg, and 60 mg/kg arms of the AL002-2 parent study will remain on the same 
dose. Those who were previously on placebo will receive a lower starting dose (ie,  mg/kg) than 
in the parent trial and will slowly titrate up to 
 mg/kg. A reduced starting AL002 dose of 
 mg/kg may be considered based on emerging safety data and upon consultation with the 
unblinded teams, the Investigator, and the Medical Monitor. For justification of the target 
treatment doses of 15 mg/kg, 40 mg/kg, and 60 mg/kg, please refer to the AL002-2 study 
protocol. 

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The emergence of ARIA with AL002 in the parent study is consistent with findings from anti-
amyloid trials, with most moderate to severe cases occurring in those who are APOE e4/e4 
homozygotes. There also appears to be a dose-dependent association in anti-amyloid trials, and a 
higher incidence of ARIA occurring early in the treatment course and a subsequent reduction 
with continued dosing. While the mechanism behind AL002 and the development of ARIA has 
yet to be fully elucidated, there is some evidence to suggest that it maybe a result of the 
downstream effects of TREM2 on microglial activation along with the rapid and abundant 
clearance of amyloid within the perivascular spaces (Ostrowitzki 2012). To mitigate the risk of 
ARIA and to further inform the development plan of AL002, a titration regimen will be 
employed in this AL002-LTE study such that participants who were randomized to the placebo 
arm of the AL002-2 trial will receive a target dose of 
 mg/kg employing a slow up-titration 
(See Section 5.1). 
1.5. 
Participant Population 
Eligibility for study inclusion will be limited to participants who completed the planned 
treatment period in the parent study AL002-2. Participants must consent to this AL002-LTE 
study and complete all outstanding assessments from AL002-2 prior to Day 1/Week 1. 
Participants from the parent study AL002-2 met all inclusion criteria at the time of enrollment 
for that study, including a diagnosis of Stages 2 and 3, or early Stage 4 AD as defined in the 
2018 National Institute on Aging/Alzheimer’s Association (NIA-AA) Research Framework 
(Jack 2018). 

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2. 
OBJECTIVES AND ENDPOINTS 
Table 1: 
Study Objectives and Endpoints 
Primary Objectives 
Primary Endpoints 
To evaluate the long-term safety and tolerability of 
AL002 in participants with AD 
• Incidence of AEs, including AESIs and SAEs 
• Vital signs, clinical laboratory results, and 
incidence of findings from physical, neurological, 
ophthalmological examinations, and ECG 
• C-SSRS 
• MRI abnormalities 
To evaluate the effect of dose titration on ARIA 
• 
Incidence and severity of ARIA in participants 
undergoing titration 
Secondary Objective 
Secondary Endpoints 
To evaluate the PK of AL002 in participants with AD 
• 
Serum PK concentrations of AL002 and relevant 
PK parameters 
To evaluate the effects of AL002 on COAs in 
participants with AD 
• 
CDR-SB 
• 
MMSE 
• 
RBANS-Update 
• 
ADAS-Cog13 
• 
ADCS-ADL-MCI 
• 
ADCOMS 
Exploratory Objectives 
Exploratory Endpoints 
To evaluate the effects of AL002 on biomarkers in 
participants with AD 
• 
Levels of sTREM2 in CSF and/or plasma 
• 
Levels of biomarkers related to microglia 
function in CSF and/or plasma (eg, CSF1R, 
IL1RN, osteopontin, YKL 40) 
• 
Levels of biomarkers related to AD pathology in 
CSF and/or plasma (eg, Aβ40, Aβ42, pTau, 
tTau) 
• 
Levels of neurodegeneration biomarkers in 
plasma and/or CSF eg, NfL 
• 
Brain volume, assessed by volumetric MRI 
• 
Brain pathological tau burden as assessed by 
longitudinal Tau PET for participants who agree 
to participate in the optional assessment only 
• 
Brain amyloid burden as assessed by 
longitudinal Amyloid PET scanning for 
participants who agree to participate in the 
optional assessment only 
To evaluate immunogenicity of AL002 in participants 
with AD 
• 
Incidence of ADAs 

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Aβ40=amyloid beta (1-40); Aβ42=amyloid beta (1-42); AD=Alzheimer’s disease; ADA=anti-drug antibodies; 
ADAS-Cog13=Alzheimer’s Disease Assessment Scale-Cognitive Subscale; ADCOMS=Alzheimer’s Disease 
Composite Score; ADCS-ADL-MCI=Alzheimer’s Disease Cooperative Study – Activities of Daily Living – Mild 
Cognitive Impairment Scale; AE=adverse event; AESI=adverse event of special interest; CDR-SB=Clinical 
Dementia Rating – Sum of Boxes; COA=clinical outcome assessment; CSF=cerebrospinal fluid; CSF1R=colony 
stimulating factor 1 receptor; C-SSRS=Columbia-Suicide Severity Rating Scale; ECG=electrocardiogram; 
IL1RN=interleukin 1 receptor antagonist; LP=lumbar puncture; MMSE=Mini-Mental Status Examination; 
MRI=magnetic resonance imaging; NfL=neurofilament light; PD=pharmacodynamic(s); PET=positron emission 
tomography; PK=pharmacokinetic(s); pTau=phosphorylated tau; RBANS-Update=Repeatable Battery for the 
Assessment of Neuropsychological Status-Update; SAE=serious adverse event; sTREM2=soluble triggering 
receptor expressed on myeloid cells 2; tTau=total tau; YKL-40=chitinase 3-like 1. 
Note: All participants who consent to the optional lumbar puncture (LP) will have optional CSF collection. In 
addition, CSF will be collected as needed in participants with ARIA. 
Longitudinal amyloid and Tau PET imaging applies to those participants who consent and participate in the optional 
exploratory biomarker assessment. 

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3. 
INVESTIGATIONAL PLAN 
3.1. 
Study Design 
This is a Phase 2, parallel-group, long-term extension (LTE), dose-blind, global multicenter 
study to evaluate the long-term safety and efficacy of AL002 in participants with AD. The study 
will enroll participants who completed the planned treatment period in AL002-2 (parent study). 
Study sites are located in North America, Australia, Europe, and Argentina. 
Participants who were randomized to active treatment in the parent study will remain on their 
previously assigned dose. Participants who were previously on placebo in the parent study will 
be assigned to the Titration Cohort, which will initiate with a starting dose of  mg/kg with the 
potential of escalating to 
 mg/kg per the Titration Algorithm described in Section 5.1. 
The primary objectives of this Phase 2-LTE study are to evaluate the long-term safety and 
tolerability of AL002 at 3 possible doses (ie, 15 mg/kg, 40 mg/kg, and 60 mg/kg) and to assess 
the effect of a slower dose titration on the incidence and severity of ARIA (see Study 
Objectives/Endpoints Table 1). 
The secondary objectives include the evaluation of the PK of AL002 as well as clinical outcome 
assessments (COAs) in participants with AD. A battery of COAs (Section 14.2) will be 
administered as secondary assessments over the course of the study. Efficacy assessments will be 
made during the pre-specified time points throughout the 49-week treatment period and at an end 
of study (EOS)/Week 57 or early termination (ET) Visit if needed (Table 9). 
The exploratory objectives of this AL002-LTE study are to evaluate biomarkers, and the 
immunogenicity of AL002 in participants with AD. Exploratory fluid (blood/plasma and CSF), 
imaging (MRI, Tau positron emission tomography (PET) with the tau radiotracer fluorine-18 
MK-6240 ([18F]MK-6240) and Amyloid PET) biomarker measures will be assessed. Optional 
biomarker assessments include: CSF collection, Tau PET and Amyloid PET imaging. 
Participants who did not previously opt-in to these exploratory PET and CSF assessments in 
AL002-2 may choose to either opt-in or opt-out in this LTE study. Those who did not previously 
consent to these optional assessments in AL002-2 may be required to complete these procedures 
during the screening/baseline period in order to establish a baseline before their AL002-LTE 
Day 1/Week 1 AL002 dose, if they choose to participate in these assessments in this study. 
Please see sections related to study visits in this protocol and the footnotes in the Schedule of 
Assessments (Table 9) for details. 
Safety assessments will be performed upon signing of informed consent and throughout the 
treatment period until the EOS participation. Safety will be assessed through monitoring of AEs 
(including AESIs and SAEs), changes in laboratory and vital sign values, incidence of findings 
from physical, neurological, ECG, MRI, ophthalmological examinations, and reports of suicidal 
ideation or behavior. In addition, CSF (optional) AL002 concentrations will be measured. Blood 
samples for assessment of ADA will be taken throughout the study. PK and PD (CSF, imaging, 
and blood) assessments will be performed during the pre-specified time points throughout the 
treatment period, and at the EOS or ET Visit. The full Schedule of Assessments is provided in 
Table 9. 
Participants were not directly involved in the design of the AL002-LTE clinical trial. 

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3.2. 
Description of Study Periods and Visits 
3.2.1. 
Screening/Baseline Period 
After signing the Informed Consent Form (ICF) at the final dosing visit of the parent study, 
participants enter a screening/baseline period of up to 4 weeks to confirm eligibility and to obtain 
outstanding assessments. A Screening/Baseline Visit could occur any time in the 
screening/baseline period. It is preferred to obtain informed consent and initiate the 
screening/baseline activities for this AL002-LTE study at the conclusion of the final dosing visit 
of the parent study AL002-2. If the assessments (see Schedule of Assessments in Table 9) were 
collected at that visit, they will not have to be repeated prior to Day 1/Week 1 of this AL002-
LTE study. The C-SSRS must be collected during the screening/baseline period. 
This period can also be utilized to schedule and perform optional biomarker assessments prior to 
dosing on Day 1/Week 1 for those participants who consented to these procedures as follows: 
• For participants who did not have amyloid and/or Tau PET imaging assessments 
completed in study AL002-2 in the 24 weeks preceding Day 1/Week 1, a visit will be 
performed to schedule PET imaging prior to Day 1/Week 1. Participation in the 
optional amyloid and/or Tau PET procedures may not be permitted in some countries. 
• For participants who did not complete the optional CSF collection in study AL002-2 
in the 12 weeks preceding Day 1/Week 1, an lumbar puncture (LP) must be 
performed 5 days prior to the first dose on Day 1/Week 1. 
If the COAs or LP were collected in the 12 weeks preceding Day 1/Week 1, or if the amyloid 
and/or Tau PET scan(s) was done in the 24 weeks preceding Day 1/Week 1, these assessments 
will not have to be collected during the screening/baseline period for the AL002-LTE study. 
For the participants who do not need to have additional assessments collected after the final 
dosing visit in the parent study AL002-2 and who provide consent on the same day of the final 
dosing visit in the parent study AL002-2, the Screening/Baseline Visit of this LTE study could 
coincide with the final dosing visit in the parent study AL002-2, ie, on the same day. If the 
assessments (as outlined in Table 9) were collected at the final dosing visit in the parent study 
AL002-2, they will not have to be repeated at the Screening/Baseline Visit of this LTE study. 
3.2.2. 
Treatment Period 
The planned duration of study treatment extends from Day1/Week 1 to Week 49 (Table 9). 
Dosing duration may be extended beyond this time through a protocol amendment, within the 
context of emerging favorable safety data. AL002 will be administered via IV infusion at the 
study site on Day 1/Week 1 (after all necessary baseline assessments have been completed) and 
will be repeated subsequently once every 4 weeks throughout the treatment period. 
The first dose of the AL002-LTE should be within the 4-week window (±5 days) of the last dose 
of the parent study, to maintain continuity of study treatment. Delays of the first AL002-LTE 
dose beyond that window will constitute protocol deviations. 
Dosing for any individual participant may be stopped, paused, or reduced based on emerging 
safety data and/or the development of ARIA-E or ARIA-H. If a participant discontinues the 

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study prior to the end of their planned treatment period, they will need to return for an ET Visit 
and that will mark the end of their participation in the study. 
At study entry and throughout the treatment period, safety will be assessed through monitoring 
of AEs (including AESIs and SAEs), changes in laboratory and vital sign values, incidence of 
findings from physical, neurological, ECG, MRI, ophthalmological exams, and reports of 
suicidal ideation or behavior. Serum PK will be assessed for investigation of exposure-response 
and exposure-safety relationships. Blood samples for assessment of ADA will be taken 
throughout the study. 
The COAs, PK assessments, and biomarker assessments (fluid collection and imaging) will be 
performed prior to dosing and at specific time points during the treatment period and at EOS/ET 
if needed. Please see the Schedule of Assessments (Table 9) as well as details regarding the 
required and optional assessments needed throughout the treatment period. 
3.2.3. 
Unscheduled Visits 
Unscheduled visits may occur at any time while the participant is enrolled in the study. 
3.2.4. 
End of Study/Week 57 Visit 
Participants are considered to have completed the study if they engage in all procedures and 
visits as outlined in Table 9. The EOS Visit is defined as the final study visit at Week 57 which 
is 8 weeks after the last AL002 administration. 
All outstanding assessments will be completed within the specified timepoints as indicated in 
Table 9. For a detailed list of procedures, please refer to Table 9. 
No additional care is expected to be required for participants after participation in the 
AL002-LTE study has ended because of their participation in this clinical trial. 
3.2.5. 
Early Termination Visit 
If it is not possible to keep the participant in the study, or if continued participation is not 
acceptable to the participant or Investigator, the participant may be withdrawn. It is 
recommended that the Investigator consults with the Medical Monitor prior to removing a 
participant from the study for any reason except participant withdrawal of consent or other 
protocol-mandated discontinuation. Participants are considered to be withdrawn, or ET, when the 
study drug is discontinued, and they refrain from completing further visits as outlined in Table 9. 
Please also see Section 4.3. (Withdrawal of Participants from Study) and Table 9 for additional 
information regarding discontinuation of participants from study drug and/or withdrawal from 
the study. 
An ET Visit is performed only in cases where the participant is prematurely discontinued from 
the study for any reason. If the participant withdraws or is discontinued from the study for any 
reason, the ET must be completed no longer than 4 to 8 weeks after the last administered dose. 
All safety evaluations, efficacy, biomarker, PK and ADA assessments must be completed at this 
visit. COAs that were collected in the 12 weeks preceding the ET Visit will not have to be 
collected at the ET Visit. C-SSRS is to be collected at the ET Visit regardless of the last 
collection date. Please see Table 9 schedule and footnotes for additional information. 

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If a participant is not able to return to the site for the ET Visit, then certain assessments may be 
performed remotely, similar to situations involving COVID-19 (Appendix 14.4.2). 
If the participant is discontinued or withdrawn from treatment related to an AE (see Section 7), 
they must be followed until resolution or stabilization of the event, or as deemed no longer 
necessary by the Investigator or Medical Monitor, and the ET Visit should not occur until 
resolution of the event. A participant is considered lost to follow-up if the Investigator has not 
had contact with them or their study partner after 3 attempts. Efforts to contact the participant 
must be made in more than one modality, including, but not limited to, a telephone call, mailing, 
or other means of communication, and this should be documented accordingly. 

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4. 
PARTICIPANT SELECTION AND WITHDRAWAL CRITERIA 
All participants who have completed the planned treatment period in the parent study, AL002-2, 
are invited to participate in this study. Enrollment is optional and participation may be offered at 
the discretion of the Investigator. 
Eligibility for study inclusion will be limited to participants who completed the planned 
treatment period in the prior AL002-2 study. Participants must consent to this dose-extension 
study and complete all outstanding assessments from AL002-2 prior to Day1/Week 1 of 
AL002-LTE. Participants with the APOE e4/e4 genotype who were previously enrolled and 
permanently discontinued from study drug are excluded from participation. 
4.1. 
Inclusion Criteria 
Each participant must meet all of the following criteria to be enrolled in this study: 
1. The participant has completed the planned treatment period in the AL002-2 study. 
Completion of the planned treatment period is defined as any participant who did not 
prematurely and permanently discontinue the study drug in the AL002-2 study. 
2. The participant is willing and able to give informed consent. Where local regulations 
permit inclusion of participants deemed not able to provide informed consent, a legally 
authorized representative must provide informed consent on his or her behalf, and the 
participant must provide assent, in accordance with the local regulations, guidelines, and 
institutional review board or independent ethics committee. 
3. Female participants must be nonpregnant and nonlactating, and 1 of the following 
conditions must apply: 
a. Participant is not a woman of childbearing potential (WOCBP) (either surgically 
sterilized, or physiologically incapable of becoming pregnant, or at least 1-year 
postmenopausal [amenorrhea duration of 12 consecutive months with no identified 
cause other than menopause]). 
b. Participant is a WOCBP and agrees to use an acceptable contraceptive method from 
screening until 12 weeks after the last dose of study drug. Acceptable contraception is 
defined as using hormonal contraceptives or an intrauterine device combined with at 
least 1 of the following forms of contraception: a diaphragm or cervical cap, or a 
condom, or the sole sexual partner to a vasectomized male. Vasectomized males must 
have received medical assessment of surgical success. In addition, total abstinence, in 
accordance with the lifestyle of the participant, is acceptable. 
c. A WOCBP must have a serum pregnancy test conducted at screening. Additional 
requirements for pregnancy testing during and after study intervention are described in 
the Schedules of Assessments. 
4. Male participants must agree to use acceptable contraception and not donate sperm from 
screening until 12 weeks after the last dose of study drug. Acceptable contraception for the 
male participant when having sexual intercourse with a WOCBP who is not currently 
pregnant is defined as using a condom. In addition, WOCBP partners must use hormonal 
contraceptives or an intrauterine device. Vasectomized male participants should have 
received medical assessment of surgical success. 

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5. Participant weighs ≤120 kg; body mass index (BMI) is between 18.5 and 34.9 kg/m2 
inclusive. 
6. The participant has availability of a person (“study partner”) who, in the Investigator’s 
opinion, has frequent and sufficient contact with the participant (eg, at least 10 hours per 
week of in person contact), is able to provide accurate information regarding the 
participant’s cognitive and functional abilities, agrees to provide information at clinic 
visits (which require partner input for scale completion), and signs the necessary consent 
form. 
a. The study partner must have sufficient cognitive capacity, in the Investigator’s opinion, 
to accurately report upon the participant’s behavior, cognitive, and functional abilities. 
The study partner should be in sufficiently good general health, in the Investigator’s 
opinion, to have a high likelihood of maintaining the same level of interaction with the 
participant and participation in study procedures throughout the study duration. 
b. Every effort should be made to have the same study partner participate throughout the 
duration of the study, and to have the same study partner as in the parent study. 
7. The participant and study partner are fluent in the language of the tests used at the study 
site as assessed by site personnel. 
8. The participant is willing and able to complete all aspects of the study (including MRI). 
The participant should be capable of completing assessments either alone or with the help 
of the study partner. Participants whose disease has progressed such that they cannot 
complete the efficacy assessments may participate in the study for assessment of safety. 
9. The participant has adequate visual and auditory acuity, in the Investigator’s opinion, 
sufficient to perform the neuropsychological testing (corrective lenses and hearing aids are 
permitted). 
10. Participant agrees not to donate blood or blood products for transfusion for the duration of 
the study and for 1 year after the final dose of study drug. 
Inclusion criteria for participants in the optional Tau PET imaging assessment with [18F]MK-
6240 only: 
11. Participant has not had excessive radiation exposure prior to enrollment in the trial, as 
defined by local standards. 
12. [18F]MK-6240 is available to the PET imaging center based on manufacturing distribution 
network and local regulations. 
Inclusion criteria for participants in the optional longitudinal Amyloid PET imaging assessment 
only: 
13. Participant has not had excessive radiation exposure prior to enrollment in the trial, as 
defined by local standards. 
14. An approved amyloid radiotracer is available to the PET imaging center based on 
manufacturing distribution network and local regulations. 

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4.2. 
Exclusion Criteria 
Participants are excluded who meet the following any of the following exclusion criteria: 
1. Participants deemed not able to provide consent or assent by the Investigator or by local 
regulations. 
2. Participants who were prematurely and permanently discontinued from treatment in the 
parent study for safety reasons. 
3. The participant has MRI evidence of: 
a. >2 lacunar infarcts. 
b. Any territorial infarct >1 cm3. 
c. White matter hyperintense lesions on the FLAIR sequence that correspond to an overall 
Fazekas score of 3. 
d. Participants who have an increase in their number of microbleeds, since the previous 
screening/ baseline MRI in the AL002-2 study and greater than 5, should be discussed 
with the Medical Monitor. 
e. Participants who have developed ARIA-E and ARIA-H in the parent study and who 
were permitted to continue dosing according to the ARIA management guidelines, will 
not be excluded from participation in the AL002-LTE, on the basis of microbleeds or 
hemosiderosis. 
4. Anticoagulant medications other than antiplatelet agents are prohibited within 90 days of 
screening and throughout the study. Short-term use of anticoagulants to treat an emergent 
medical need is permitted. Treatment with platelet anti-aggregation agents such as aspirin, 
clopidogrel, or dipyridamole is permitted. 
5. Participants taking any passive immunotherapy (eg, immunoglobulin) or other long-acting 
biologic agent that is under evaluation or approved to prevent or postpone cognitive 
decline. 
6. Participation in the AL002-LTE is deemed inappropriate for any reason per Investigator 
discretion. 
7. Participant agrees not to receive any investigational treatment, other than AL002, during 
the study. 
4.3. 
Withdrawal of Participants from Study 
All participants are free to withdraw from participation at any time, for any reason, specified or 
unspecified, and without prejudice. 
4.3.1. 
Withdrawal from Study Drug 
A participant may be discontinued from study drug at any time if the participant, the 
Investigator, or Alector feels that it is not in the participant’s best interest to continue. 
Participants who discontinue the study drug will be withdrawn from this study. The following is 
a list of possible reasons for study drug discontinuation: 
1. Participant is noncompliant with the protocol 
2. Participant is lost to follow-up 

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3. Participant withdraws consent 
4. Participant has a serious or intolerable AE that, in the Investigator’s opinion, requires 
withdrawal from the study drug 
5. Pregnancy 
6. Discretion of the Investigator 
7. Death 
8. Early termination of the study by Sponsor for any reason 
If a participant is withdrawn from study drug due to an AE, the participant will be followed and 
treated by the Investigator until the AE has resolved or stabilized (if applicable). Upon 
occurrence of a serious or intolerable AE, the Investigator may confer with Alector prior to 
discontinuing the participant from treatment. Any participant may withdraw his or her consent at 
any time. 
Reasonable attempts will be made by the Investigator to contact the participant prior to deeming 
the study participant as lost to follow-up (refer to Section 3.2.5 for details). 
The reason for the participant’s withdrawal from the study drug will be specified in the 
participant’s source documents and on the electronic case report form (eCRF). 
4.3.2. 
Withdrawal from Study 
A participant may be withdrawn from the study at any time if the participant, the Investigator, or 
Alector feels that it is not in the participant’s best interest to continue. Participants who 
discontinue the study drug will be withdrawn from this study. The following is a list of possible 
reasons for study discontinuation: 
1. Participant is noncompliant with the protocol 
2. Participant is lost to follow-up 
3. Participant withdraws consent 
4. Participant has a serious or intolerable AE that, in the Investigator’s opinion, requires 
withdrawal from the study 
5. Pregnancy 
6. Discretion of the Investigator 
7. Death 
8. Early termination of the study by Sponsor for any reason 
All participants who discontinue the study should come in for the ET Visit according to the 
Schedule of Assessments (Table 9), unless they were lost to follow-up, withdrew consent or 
died. Participants who discontinue from the study will not be replaced. 
Reasonable attempts will be made by the Investigator to contact the participant prior to deeming 
the study participant as lost to follow-up (refer to Section 3.2.5 for details). 

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The reason for the participant’s withdrawal from the study will be specified in the participant’s 
source documents and on the eCRF. 

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5. 
STUDY DRUG 
5.1. 
Method of Assigning Participants to Treatment Groups 
Participants in the active treatment group in the parent study will remain at their assigned dose. 
The Titration Cohort refers to participants who were randomized to placebo in the parent study 
AL002-2. They will receive an initial starting dose of  mg/kg that will be increased to reach the 
target dose of 60 mg/kg per Titration Algorithm 1 (Table 2). The dose escalation consists of: 
• 
 doses of  mg/kg: 
 on 
1 and o
e on 
, 
• 
 doses of 
 mg/kg: 
e on 
 and 
e on 
, 
• 
 doses of 0 mg/kg: o
e on 
7 and o
e on 
1, 
• T
 doses of 6  mg/kg begin on 
, and this dose continues until the final 
dosing visit. 
Table 2: 
Titration Algorithm 1 (Starting Dose:  mg/kg) 
Week 
 
 
 
 
AL002 Dose 
 mg/kg 
5 mg/kg 
 mg/kg 
 mg/kg 
The evaluation of dosing and its relationship to safety and ARIA within the Titration Cohort will 
occur only with the unblinded pharmacist, the unblinded pharmacy monitor, the unblinded 
clinical research organization (CRO) staff, and unblinded safety management team at Alector. 
ARIA monitoring and management will be consistent with the procedures outlined in the parent 
study. Additional information about ARIA safety monitoring is described in Section 7.6.4 and 
Section 7.11. 
If emerging data suggests that Titration Algorithm 1 is not effectively reducing the incidence or 
severity of ARIA, a lower starting dose of  mg/kg may be considered. In the event that a 
decision is made to lower the starting dose, all subsequent participants previously randomized to 
placebo in the parent study AL002-2 entering this AL002-LTE study will be treated with an 
initial starting dose of  mg/kg and will be administered AL002 every 4 weeks by IV infusion 
using an up-titration algorithm to reach the target dose of 
 mg/kg per Titration Algorithm 2 
(Table 3). The dose escalation includes: 
• 
 doses of  mg/kg: o
e on 
 and o
 on 
, 
• 
 doses of  mg/kg: 
e on 
 and 
e on W
3, 
• 
 doses of 15 mg/kg: o
e on W
7 and o
e on 
1, 
• 
o doses of 40 mg/kg: 
e on 
5 and o
e on 
, 
• 
 doses of 6  mg/kg begin on 
, and this dose continues through the final 
dosing visit. 

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Table 3: 
Titration Algorithm 2 (Starting Dose:  mg/kg) 
Week 
 
 
 
AL002 
Dose 
 mg/kg 
 mg/kg 
 mg/kg 
 mg/kg 
 mg/kg 
The evaluation of dosing and its relationship to safety and ARIA within the Titration Cohort are 
specified in Section 5.4. 
MRIs are performed per the Schedule of Assessments (see Table 9). The Sponsor may request 
that additional unscheduled MRIs be performed for the detection and follow-up of ARIA. 
Dosing for the Titration Cohort or any individual participant may be stopped, paused, or reduced 
based on emerging safety data and/or the development of ARIA-E or ARIA-H. 
ARIA monitoring and management will be consistent with the procedures outlined in the parent 
study. Additional information about ARIA safety monitoring is described in Section 7.6.4 and 
Section 7.11. 
5.1.1. 
Administration Instructions 
Dosing solution preparation instructions will be provided separately in the Pharmacy Manual. 
The IV dose must be prepared by an unblinded pharmacist following Titration Algorithm 1 for 
participants who received placebo in the parent study in Table 2. All participants will be 
administered a total volume of 150 mL containing saline and the calculated volume of AL002. 
The IV dose will be calculated by the participant’s weight on the date of AL002-LTE participant 
screening/baseline (reference weight), unless the participant’s current weight changes (increases 
or decreases) ≥10% from the screening/baseline weight. If this occurs, the current weight will 
become the reference weight for subsequent dosing. If the participant’s weight again changes 
≥10% from the reference weight, the IV dose will again be recalculated. Please refer to the 
Pharmacy Manual for further information. 
A volume of 150 mL of study drug will be administered via IV over approximately 60 minutes at 
the study site by study-trained clinic staff who are blinded to the identity of the study drug, under 
the supervision of the Investigator or their designee. 
The calendar date and 24-hour (local) clock times when the infusion is initiated and concluded, 
including any interruptions, will be recorded in the source documentation and documented in the 
eCRF. The end of infusion is the end of the line flush (please see the Pharmacy Manual). 
The Investigator is responsible for the education of study staff in the correct administration of the 
study drug. 
Participants will arrive at the treatment unit on the day of study drug administration and will be 
followed up for at least 60 minutes after the end of infusion and completion of all activities 
scheduled for that visit day. 

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5.2. 
Identity of Study Drug and PET Radiotracers 
5.2.1. 
Study Drug 
AL002 is a recombinant humanized monoclonal antibody, which is an agonistic TREM2 
monoclonal antibody. 
AL002 for infusion will be provided as a 
n in a 
s 
l, with 
 and 
 with a r
. Each s
 
 will contain at least 
 of a 5
2 in 2
e 
H
, and 
0 at a 
 
 of 
. Each vial will contain at least 0 mL of AL002 for IV use only. 
5.2.1.1. 
Study Drug Packaging and Labeling 
The Sponsor will be responsible for the preparation and labeling of bulk study drug and placebo 
and for providing details of batch numbers, safety, and stability data. This process is described in 
detail in the Pharmacy Manual. 
The study drug will be manufactured for Alector under contractual and quality agreements at a 
qualified current GMP contract manufacturing organization. The Sponsor will ensure that the 
products are labeled in accordance with all local regulatory requirements. 
5.2.2. 
[18F]MK-6240 Tau PET Radiotracer 
This section is only applicable for those who participate in the optional Tau PET assessments. 
[18F]MK-6240 will be provided under contract with a PET imaging vendor in accordance with 
approved national and/or local standards; Tau PET will not be conducted in those countries 
where the Tau PET radiotracer is unavailable and/or where it is not part of the approved Clinical 
Trial Application. [18F]MK-6240 will be supplied as a sterile nonpyrogenic solution in sterile 
borosilicate glass vials with butyl septa and aluminum ring seals. The vial is contained within an 
outer lead or tungsten shield (“pig”) to protect from gamma radiation. The final product bears a 
label with the following items: total activity in millicurie (mCi) units, volume (mL), strength 
(mCi/mL), calibration date and time, batch number, study identification, and shelf life. The 
investigational agent will be stored at ambient temperature in its original container. For 
information on the formulation and handling of [18F]MK-6240, see the [18F]MK-6240 IB and the 
PET Imaging Procedures Manual. 
The anticipated effective dose of each scan will be 6.4 millisievert (mSv), including radiation 
from the associated attenuation computerized tomography (CT) scan. 
5.2.3. 
Amyloid PET Radiotracer 
This section is only applicable for those who participate in the optional Amyloid PET 
assessments. Appropriate Amyloid PET radiotracers will be provided under contract with a PET 
imaging vendor in accordance with approved national and/or local standards. [18F]florbetaben 
(Neuraceq) is the primary radiotracer; where Neuraceq is not approved or not available, 
[18F]florbetapir (Amyvid)will be the radiotracer. Refer to the local labeling information and PET 
Imaging Procedures Manual for details on effective dose, packaging, formulation, and handling 
of the Amyloid PET radiotracers. Depending on locality, additional information may also be 

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found in the local labeling information or the IB for the particular Amyloid PET radiotracer 
being used. 
The anticipated effective dose of each scan, including radiation from the associated attenuation 
CT scan, will be 6.8 mSv with Neuraceq and 8.0 mSv with Amyvid. 
5.2.4. 
Investigational and Auxiliary Medicinal Products Used in AL002-LTE 
The investigational medicinal products (IMPs) and auxiliary medicinal products (AMPs) used in 
AL002-LTE are listed in Table 4. 
Table 4: 
Comprehensive List of Investigational and Auxiliary Medicinal Products 
(IMP and AMP) Used in AL002-LTE Study 
 
Category 
Authorization Status  
Study Drug (AL002) 
IMP 
Not authorized for use in any country. 
[18F]MK-6240 
Tau PET radiotracer 
AMP 
Not authorized for use in any country. 
 
Will only be used in accordance with approved 
national and/or local standards; Tau PET will not be 
conducted in those countries where the Tau PET 
radiotracer is unavailable and/or where it is not part 
of the approved Clinical Trial Application. 
 
Use of the [18F]MK-6240 tracer is justified because 
this Tau PET tracer has improved tracer 
characteristics (lower non-specific binding and 
lower prevalence of off-target binding) as well as 
the ability to detect lower levels of tau compared to 
other available tracers, which is important to be 
able to measure small longitudinal changes in tau 
levels (Rowe 2022). 
[18F]florbetaben (Neuraceq) 
Amyloid PET radiotracer 
AMP 
Authorized for use in US, European Union 
(including Spain, Poland, Italy, France, Germany, 
and Netherlands), UK, Canada, and Australia. 
 
Neuraceq will be used in accordance with the terms 
of its marketing authorization in all countries in 
which it is approved and will not be used in any 
countries where it is not authorized. 

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Category 
Authorization Status  
[18F]florbetapir (Amyvid) 
Amyloid PET radiotracer 
AMP 
Authorized for use in US, UK, Spain, Italy, France 
and Germany; however this radiotracer is only 
being used in the AL002-LTE study in the US. 
 
Amyvid will be used in accordance with the terms 
of its marketing authorization in all countries in 
which it is approved and will not be used in any 
countries where it is not authorized. 
5.3. 
Management of Clinical Supplies 
Specific instructions about the storage, preparation, and administration of study drug are 
provided in the Pharmacy Manual. Additional information about the study drug is provided in 
the IB and on the Certificate of Analysis. 
5.3.1. 
Study Drug Supply 
The Sponsor will supply all study drug to the investigational site, as detailed in the Pharmacy 
Manual. Study drug supplies provided for this study will be manufactured under current Good 
Manufacturing Process and will be suitable for human use. 
5.3.2. 
Study Drug Storage 
Study drug will be shipped at a temperature of 2°C to 8°C. 
Upon receipt at the study site, the study drug shall be stored in a secure and temperature-
monitored (2°C to 8°C) location. The Investigator will be fully responsible for the security, 
accessibility, and storage of the study drug while it is at the investigational facility. 
Study drug dosing solution must be administered within 24 hours after preparation. Additional 
details on study drug storage and preparation are provided in the Pharmacy Manual. 
5.3.3. 
Study Drug Accountability 
The study site will maintain accurate records of receipt of all study drug, including dates and 
conditions of receipt. In addition, accurate records will be kept regarding when and how much 
study drug is dispensed and used by each participant in the study. At the completion of the study, 
to satisfy regulatory requirements regarding drug accountability, all study drugs will be 
reconciled and retained or destroyed according to applicable local regulations. Please see the 
Pharmacy Manual for additional instructions. 
5.3.4. 
Study Drug Return or Disposal 
Study product supplies, including partially used or empty vials, should be disposed of at the site 
per local standard operating procedures (SOPs). If study product supplies cannot be destroyed 
on-site, they may be shipped back to the return depot. Please see the Pharmacy Manual for 
additional instructions. 

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5.3.5. 
Unauthorized AMP Accountability, Return, and/or Disposal 
[18F]MK-6240 is the only unauthorized AMP used in this study. If all or a portion of [18F]MK-
6240 is unused at the subject’s visit, the tracer will not be returned to the production facility. The 
imaging facility is recommended to wait for the product to decay and then dispose of the vial or 
syringe according to their internal SOPs. Depending on the method or transportation (car/air), the 
lead shielded containers used to ship the tracer will need to be returned. For handling the Tau 
PET radiotracer, only personnel properly trained in the handling and administration of 
radioactive materials should handle [18F]MK-6240. Usual radiation protection procedures should 
be used for handling radiotracers, including shielding (lead or tungsten containers/shields), and 
personal protective equipment including gloves. There are no specific procedures required for 
the handling of [18F]MK-6240. The expiry of [18F]MK-6240 is 8 hours from the time at end of 
synthesis. 
5.4. 
Blinding 
5.4.1. 
Blinding of the Parent Study AL002-2 and AL002-LTE 
To maintain the blind to the treatment assignments in the parent study AL002-2 and the blind in 
this LTE study, those who are conducting the efficacy assessments, the Investigator, the study 
staff at the site, study participants, participant study partners, and the clinical site monitors will 
remain blinded to treatment assignments throughout the LTE study, except in circumstances 
described in Sections 5.4.2 and 5.4.3. In addition, the clinical research organization (CRO) and 
the Sponsor will also remain blinded to the treatment assignments, except in circumstances 
described in Sections 5.4.2 and 5.4.3 and below. 
Upon unblinding of the parent study AL002-2, the personnel at CRO or Sponsor who are 
unblinded to the treatment assignments (except those described in Sections 5.4.2 and 5.4.3) will 
no longer have any involvement with the LTE study conduct including but not limited to the 
management, treatment, or assessment of participants; new personnel who are blinded to the 
treatment assignments will replace these individuals to support the LTE study conduct. 
The evaluation of dosing and its relationship to safety within the Titration Cohort will occur only 
with the unblinded pharmacist, the unblinded pharmacy monitor, the unblinded CRO staff, and 
members of the unblinded safety management team at Alector. 
The Sponsor may be unblinded to a participant’s treatment assignment, if necessary, for safety, 
even before the time when participants’ treatment assignments in the parent study AL002-2 are 
unblinded to the Sponsor. 
5.4.2. 
Personnel Who Are Unblinded Throughout the Study 
The independent Data Monitoring Committee (iDMC) and the independent statistical group 
supporting the iDMC will be unblinded to treatment assignments for the duration of the study to 
perform the safety review in an unblinded manner (see Section 12.1.1). 
In addition to iDMC and the independent statistical group supporting the iDMC, the following 
personnel will be unblinded for the duration of the study: 
• Unblinded monitor and clinical trial manager (CRO) 

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• The study pharmacist, pharmacy monitor, and personnel involved in preparation of 
the study drug dosing solutions for IV infusion 
• Interactive web response system setup personnel (CRO) 
• Unblinded data manager (CRO) 
• Unblinded Pharmacovigilance team for safety reporting 
• Contract Manufacturing Organization 
• Personnel at the bioanalytical laboratory involved in the determination of serum 
concentrations of AL002 
5.4.3. 
Breaking the Blind by the Investigator 
A participant’s treatment assignment, including dosage, will not be unblinded by the site until the 
end of the study unless medical treatment of the participant depends on knowing the study drug 
the participant received. In the rare event that the blind needs to be broken because of a medical 
emergency, the Investigator may unblind an individual participant’s treatment allocation through 
the interactive web response system. Reasons for treatment unblinding must be clearly explained 
in the participant’s study file. The date on which the code was unblinded, together with the 
identity of the person responsible, must also be documented. 
5.5. 
Prior and Concomitant Therapy 
All concomitant medications used by a participant in AL002-2 must be collected and recorded 
into each participant’s eCRF for this study and coded using the World Health Organization Drug 
Dictionary (WHO DD), September 2022 or later. The minimum requirement is that the drug 
name, total daily dose, route, frequency of dosing, indicated use, and the dates of administration 
are to be recorded. This will include all prescription drugs, herbal or homeopathic products, 
vitamins, minerals, vaccines, topical medications, and over-the-counter medications. Any 
changes in concomitant medications also will be recorded in the participant’s eCRF. 
During the course of the study, participants are anticipated to continue the use of accepted 
prescribed medications identified during the screening/baseline procedures, in accordance with 
study inclusion and exclusion criteria. Participants should be advised against taking any new 
medication, both prescribed and over-the-counter, without consulting the Investigator, unless the 
new medication is required for emergency use. Use of any passive immunotherapy 
(eg, immunoglobulin) or other long-acting biologic agent that is under evaluation or approved to 
prevent or postpone cognitive decline is prohibited within 1 year of screening/baseline and 
during study participation. 
Any concomitant medication deemed necessary for the welfare of the participant during the 
study may be given at the discretion of the Investigator. However, it is the responsibility of the 
Investigator to ensure that details regarding the medication are recorded in full in the eCRF. 
Any restricted medication must have been stopped as required by the study inclusion and 
exclusion criterion (Section 4.1 and Section 4.2, respectively); participants who start these 
medications during the study may be withdrawn from study drug at the discretion of the Sponsor 
or Medical Monitor. 

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Use of nonsedating antihistamine medications is permitted as required. Participants who meet all 
the study inclusion and exclusion criteria defined for hypertension may be taking 
antihypertensive medication if on a stable dose at screening/baseline and for the duration of the 
study. Participants may be taking antidepressant medication (eg, selective serotonin reuptake 
inhibitors, serotonin and norepinephrine reuptake inhibitors) if on a stable dose at 
screening/baseline and for the duration of the study. Paracetamol/acetaminophen up to 
2000 mg/day may be used for minor ailments during the course of the study without prior 
consultation with Sponsor’s Medical Monitor. 
5.6. 
Rescue Medication 
Participants who experience significant rapid and consistent objective cognitive decline may be 
able to initiate treatment with approved symptomatic AD drugs, after review and approval by the 
Medical Monitor. 
The assessment of significant rapid and consistent objective cognitive decline will be at the 
discretion of the Investigator. 
Participants for which approval is granted would remain on study drug. Initiation would be based 
on the prescribing information for the approved medication and would be administered 
concomitantly with study drug. Participants must obtain the approved medication via 
prescription at their own cost; Alector will not provide the approved medication. 

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6. 
STUDY ASSESSMENTS AND PROCEDURES 
All potential participants will sign an ICF (preference is for signing the ICF at the final dosing 
visit of the planned treatment period of the AL002-2 study) before performing any study 
procedures for the LTE study. As AD is a progressive neurodegenerative disease, some 
participants may become incompetent during the course of the study, and it is important to 
understand if AL002 is safe and effective in these participants. If the study participant is not 
competent or becomes incompetent during the study, a legally authorized representative must 
provide informed consent on their behalf, and the participant must provide assent, in accordance 
with the local regulations, guidelines, and institutional review board/independent ethics 
committee (IRB/IEC). Where not permitted by local regulations, participants deemed not 
competent to provide consent by the Investigator will not be enrolled. 
Participants will have the opportunity to have any questions answered before signing the ICF. 
The Investigator or designee must address all questions raised by the participants. The 
Investigator or designee will also sign the ICF. Further details of informed consent are provided 
in Section 10.3. 
Safety assessments will consist of monitoring incidence of AEs, changes in vital signs and 
clinical laboratory results, incidence findings of physical, neurological, and ophthalmological 
exams, ECGs, suicidality via the Columbia-Suicide Severity Rating Scale (C-SSRS), and MRI 
abnormalities. 
Study visits and timing of assessments and procedures are provided in the Schedule of 
Assessments (Table 9). Study visits may be conducted on 2 consecutive days. Other adaptations 
to visits and procedures under the exceptional circumstance of the COVID-19 pandemic are 
detailed in Section 14.4. 
6.1. 
Timing of Study Drug Administration and Procedures 
Timing of study drug administration are provided in the Schedule of Assessments (Table 9). 
Pre-dose study procedures and assessments: 
• Height, weight, and vital signs, including body temperature, respiratory rate, pulse 
rate, and systolic and diastolic blood pressure (BP) 
• Physical examination (PE) or limited, symptom-driven examination 
• Neurological examination 
• Review of concomitant medication(s) (completed before performing COAs to rule out 
use of medications prohibited within specific time windows) 
• Record any AEs, AESIs, and SAEs 
• Single 12-lead ECG 
• Obtain blood and urine samples for chemistry, hematology, coagulation, viral 
serology, pregnancy testing, and urinalysis 
• Perform C-SSRS 

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• Perform COAs prior to any potentially stressful procedure (eg, LPs, imaging). Blood 
draws may be counted as a stressful procedure per the Investigator’s clinical 
judgment. 
• Obtain blood samples for ADAs, PK, and biomarkers 
• Perform MRI 
• Perform optional Tau PET imaging 
• Perform optional longitudinal Amyloid PET imaging 
Dosing procedures: 
• Study drug will be administered to participants per institutional practice and the 
Pharmacy Manual 
Post-dose procedures (Day 1/Week 1 to end of treatment period): 
• Obtain blood samples for biomarkers 
• Single 12-lead ECG 
• Vital signs, including body temperature, respiratory rate, pulse, and systolic and 
diastolic BP 
• Record any AEs and SAEs 
• Optional LP 
6.2. 
Sample Collections 
Specific information on clinical safety and bioanalytical laboratory sample collection, 
processing, storage, and shipment will be provided in a Laboratory Manual. 
Unused portions of PK, PD, and/or ADA samples remaining after all applicable protocol-defined 
tests have been performed may be retained and maintained for up to 10 years where permitted by 
local regulations, if the participant agrees and provides consent separately for this as described in 
Section 10.3. These optional blood or CSF samples may be used for future testing not described 
in this protocol. 
For participants who have provided consent, the samples may be used for testing including the 
following: further evaluation of biomarkers (eg, associated with efficacy, AEs, or disease 
progression), further clarification or characterization of the disease, further evaluation of the 
study drug’s effects, and/or development of assays (eg, biomarker or diagnostic assays). 
Timing and frequency of all sample collections are presented in the Schedule of Assessments 
(Table 9). 
6.3. 
Safety Assessments 
Safety endpoints for this study are presented in Section 2. Safety assessments will consist of 
monitoring incidence of AEs, changes in vital signs and clinical laboratory results, incidence of 
findings of physical, neurological, and ophthalmological exams, ECGs, suicidality via the 
C-SSRS, and MRI abnormalities. 

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Participants with new or worsening radiographic evidence of ARIA on post-baseline MRI scans 
should be evaluated for neurological signs or symptoms after the initial Day 1/Week 1 dose. 
ARIA will be managed according to the guidelines in Section 7. Timing and frequency of all 
safety assessments are presented in the Schedule of Assessments (Table 9). 
6.3.1. 
Adverse Events, Adverse Events of Special Interest, and Serious Adverse Events 
All AEs, AESIs, and SAEs must be collected and recorded, regardless of cause or relationship to 
AL002, after the participant signs the ICF until the end of study participation. 
The following AEs and special situations must also be reported to Alector Drug Safety within 
24 hours of awareness: 
• AEs assessed as related to the radiopharmaceutical Neuraceq® (florbetaben F18 
injection). Please note: if the site’s imaging facility is located outside of the institutional 
facility, please ensure the imaging lab is aware of this requirement. 
• Special situations (overdose, off-label use, abuse, misuse, occupational exposure, 
medication error) associated with Neuraceq® or the Alector study drug regardless of 
whether the special situation is associated with an AE and regardless of the Investigator’s 
causality assessment of the event with respect to the radiopharmaceutical or the Alector 
product. 
Any unresolved or ongoing AEs, AESIs, and SAEs will be collected and recorded up through 
resolution, stabilization, or return to baseline. Additionally, SAEs considered related to study 
drug or radiotracer, which occur at any time during the study, will be followed until resolution, 
participant withdrawal of consent, loss to follow-up, or death. Additional details of AE collection 
are provided in Section 7. 
6.3.2. 
Concomitant Medications 
All concomitant medications used by a participant 14 days prior to screening/baseline through 
study completion/ET Visit will be collected and recorded in the participant’s eCRF. Timing and 
frequency of concomitant medication assessments are presented in the Schedule of Assessments 
(Table 9). 
6.3.3. 
Demographics 
Year of birth, age (calculated), sex, ethnicity, handedness, and race will be collected unless 
disallowed by local regulatory agencies. 
6.3.4. 
Medical History and Social History 
Medical history will not be collected for this study. 
Any new event or change in the participant’s social history prior to the initial dosing on 
Day 1/Week 1 will be reported in the relevant social history section of the participant’s eCRF. 
Social history includes the following information, past and current, regarding the participant: 
marital status, employment status, highest level of education, tobacco use (eg, smoking, vaping, 
chewing, etc.), alcohol consumption, cannabinoid use, and recreational drug use history. 

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6.3.5. 
Physical Examinations 
Complete and limited, symptom-directed PEs will be performed by a physician, a physician’s 
assistant, or a nurse practitioner qualified to perform the assessments. Complete PEs include 
evaluation of the head, eye, ears, nose, and throat and the cardiovascular, dermatological, 
musculoskeletal, respiratory, and gastrointestinal systems. Breast, rectal, and genitourinary 
exams should be performed as clinically indicated. Complete PEs are performed on all 
participants at screening/baseline and at EOS/ET. 
Limited PEs should include cardiovascular, respiratory, and gastrointestinal systems; further 
symptom-directed examination may also include any other pertinent system as required. A 
limited PE will be performed at all other specified time points, prior to study drug administration 
(as specified in the Schedule of Assessments [Table 9]) or as clinically indicated. 
Abnormalities observed prior to dosing with study drug, as well as new or worsened clinically 
significant abnormalities at all other visits, will be recorded on the eCRF. New abnormal PE 
findings will be followed up at the next scheduled visit. New or worsened abnormalities should 
be recorded as AEs on the AE eCRF if considered clinically significant in the Investigator’s 
opinion. 
Body height (cm) and body weight (kg) will be measured at the time points delineated in the 
Schedule of Assessments (Table 9). 
6.3.6. 
Neurological Examinations 
Neurological examinations will be performed at the time points delineated in the Schedule of 
Assessments (see Table 9). 
A complete neurologic examination should include the evaluation of consciousness, orientation, 
cranial nerves, motor and sensory system, coordination and gait, and reflexes. Changes from 
baseline and/or abnormalities should be recorded at each subsequent neurologic examination. 
New or worsened abnormalities should be recorded as AEs on the AE eCRF if considered 
clinically significant in the Investigator’s opinion. 
6.3.7. 
Ophthalmological Examinations 
Ophthalmological examination will be conducted at the time points delineated in the Schedule of 
Assessments (see Table 9). 
Ophthalmologic exams include the following: 
1. 
 exam (eg, using a 
 chart) 
2. 
 examination before and after dilation 
3. Dilated exam of the f
s by 
 
4. 
) exam, including 
 
for examination of the c
d 
Changes from baseline abnormalities should be recorded at each subsequent ophthalmological 
examination. New or worsened abnormalities should be recorded as AEs on the AE eCRF, if 
considered clinically significant in the Investigator’s judgment. Refer to the Ophthalmological 
Assessment Manual for further details. 

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6.3.8. 
Vital Signs 
Vital sign measurements include temperature, respiratory rate, pulse rate, and systolic and 
diastolic BP while the participant is at rest in a supine position for at least 3 minutes. Heart rate 
and BP measurements should be obtained with a validated digital monitoring device where 
available and an appropriately sized cuff. The same arm should be used for all BP measurements 
if possible. Heart rate and BP should not be measured unless 15 minutes have passed since the 
last blood draw. Vital signs will be measured at the time points delineated in the Schedule of 
Assessments (Table 9). 
After the participant signs the ICF, new or worsened clinically significant abnormalities will be 
recorded on the eCRF. New or worsened abnormalities should be recorded as AEs, AESIs, or 
SAEs on the AE eCRF if considered clinically significant in the Investigator’s opinion. 
6.3.9. 
Electrocardiograms 
A single 12-lead ECG will be obtained at screening/baseline (Table 9). A single 12-lead ECG 
will also be obtained before blood draws (pre-dose) and 60 to 90 minutes after the end of 
infusion on Day 1/Week 1, and Weeks 5, 13, 25, 49, and EOS/ET (Table 9). The ECG must be 
performed after the participant has been resting (supine) for at least 10 minutes. 
All ECG tracings will be reviewed locally for safety by the Investigator or a qualified designee. 
Heart rate, QRS, corrected QT interval by Fredericia (QTcF), RR interval, and result 
interpretation will be captured in the eCRF. 
6.3.10. 
Clinical Laboratory Assessments 
Clinical laboratory assessments will be performed as delineated in Table 9. Blood and urine 
samples will be collected for clinical safety laboratory analytes (hematology, chemistry, 
coagulation, urinalysis, and viral serology) and a pregnancy test. Parameters for assessment are 
listed in Table 5 for hematology, chemistry, coagulation, and urinalysis. 
For any laboratory test value outside the reference range that the Investigator considers clinically 
significant, the Investigator will follow the instructions in Section 7. 
Medically indicated laboratory tests (emergency or unscheduled tests) should be conducted at the 
local laboratory. All other laboratory tests will be conducted at the central laboratory. Local 
laboratory data may be used in place of central lab data, in such instances where the central 
laboratory is unable to analyze the data (ie, central lab sample coagulated, sufficient volume of 
sample not collected or available for analysis, etc.). 
Fasting is not required prior to clinical laboratory assessments. 

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Table 5: 
Clinical Laboratory Safety Assessments 
Test 
Analytes 
Hematology 
Absolute neutrophil count, hemoglobin, hematocrit, MCH, MCV, MCHC, 
white blood cells, red blood cells, platelet count, and differential count 
(neutrophils, lymphocytes, monocytes, basophils, eosinophils). 
Chemistry (serum or 
plasma) 
Sodium, potassium, chloride, calcium, glucose, bicarbonate, albumin, total 
protein, creatinine, HbA1C, blood urea nitrogen or urea, aspartate 
aminotransferase, alanine aminotransferase, gamma glutamyl transpeptidase, 
alkaline phosphatase, phosphorous, total bilirubin (direct and indirect), 
amylase, cholesterol (total, LDL, HDL), triglycerides, uric acid, creatine 
phosphokinase, lactate dehydrogenase, magnesium, C-reactive protein. 
Thyroid-stimulating hormone, folic acid, vitamin B12, and viral serology 
(HIV-1 or HIV-2 antibody and antigen, hepatitis B surface antigen, hepatitis B 
surface antibody, total hepatitis B core antibody, HCV antibody/RNA) will 
also be assessed at screening/baseline only. 
Coagulation 
Prothrombin time with INR, activated partial thromboplastin time. 
Urinalysis 
Dipstick (pH, specific gravity, glucose, protein, ketones, blood). Microscopic 
analysis in the event of abnormal dipstick results (urinary sediment, red blood 
cells, white blood cells, casts, crystals, epithelial cells, bacteria). 
Pregnancy  
(WOCBP only) 
Serum pregnancy test, urine pregnancy test. 
HbA1C=hemoglobin A1C; HCV=hepatitis C virus; HDL=high density lipoprotein; HIV=human immunodeficiency 
virus; INR=international normalized ratio; LDL=low-density lipoprotein; MCH=Mean Corpuscular Hemoglobin; 
MCHC=Mean Corpuscular Hemoglobin Concentration; MCV=Mean Corpuscular Volume; RNA=ribonucleic acid; 
WOCBP=woman of childbearing potential. 
6.3.11. 
Columbia-Suicide Severity Rating Scale 
Suicidality will be assessed regularly throughout the study through participant completion of the 
C-SSRS (Table 9). The C-SSRS is an interview-based instrument used to assess incidence of 
suicidal ideation and behavior. Assessments will assess suicidal ideation and behavior since the 
previous visit. The C-SSRS is administered to the participant and measures 5 subtypes of 
suicidal ideation and behavior considered by health authorities to be important to capture in a 
prospective assessment of suicidality (FDA 2012). 
Any change in the C-SSRS score indicating the presence of suicidality should be immediately 
evaluated by the Investigator and reported to the Medical Monitor. Participants who are suicidal 
based on the C-SSRS will be referred for appropriate psychiatric evaluation and management per 
local clinical practice. When the psychiatric evaluation verifies suicidal ideation or behavior, this 
must be recorded as an AE. 
6.3.12. 
Magnetic Resonance Imaging 
Safety will be assessed with structural brain MRI at screening/baseline and according to the 
visits outlined in the Schedule of Assessments (Table 9) to evaluate the presence of ARIA. An 
MRI must be done at least 5 days and not more than 10 days prior to dose escalation. 

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All new cases of ARIA-E and/or new cases of ARIA-H will require unscheduled MRI scans 
every 4 to 6 weeks until ARIA-E has resolved and/or ARIA-H has stabilized without new 
findings. An Amyloid PET scan may also be requested after the first occurrence of ARIA-E for 
those participants who have opted in to have longitudinal Amyloid PET performed. 
Surveillance for treatment-emergent ARIA will be accomplished with post-baseline MRI scans 
as delineated in the Schedule of Assessments (Table 9). 
If new or worsening ARIA is observed on any of these post-baseline MRIs, dosing should be 
managed as prescribed in the Dosing Guidelines for ARIA (see Table 8). 
Participants with new or worsening radiographic evidence of ARIA on post-baseline MRI scans 
should be evaluated for neurological signs or symptoms during an unscheduled visit. 
All MRIs will be read for brain abnormalities within 5 days by blinded independent radiologists 
at a central MRI reader with Brain MRI Worksheets (BMWs) provided to the clinical sites and 
Sponsor. 
See Section 7.11 for a description of radiographic severity, resolution, and stabilization of ARIA 
findings, MRI surveillance for ARIA, and expectations for Investigator review of BMW reports. 
In addition to the MRI assessments prescribed in the Schedule of Assessments (Table 9) and in 
Section 7.11, the Sponsor may request that additional unscheduled MRIs be performed for the 
detection and follow-up of ARIA. 
Specific information regarding the collection and processing of MRI images will be provided in 
a separate Imaging Procedures Manual. 
6.4. 
Efficacy Assessments 
Efficacy will be assessed with COAs. Please see sections related to study visits in this protocol 
and the footnotes in the Schedule of Assessments (Table 9) for details. 
The following neurocognitive and functional tests (described in Section 14.2) will be performed 
according to the guidelines set forth in the Site Rater Manual. Neurocognitive and functional 
tests will be performed prior to study drug administration (if applicable) and prior to any 
stressful procedures (eg, blood collection, LPs, imaging). Blood collection can be considered a 
stressful procedure for a participant, according to the Investigator’s clinical judgment. 
• Clinical Dementia Rating (CDR) 
• Mini-Mental State Examination (MMSE) 
• Repeatable Battery for the Assessment of Neuropsychological Status-Update 
(RBANS-Update) 
• Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog13) 
• Alzheimer’s Disease Cooperative Study-Activities of Daily Living – Mild Cognitive 
Impairment Scale (ADCS-ADL-MCI) 
If a participant cannot be evaluated due to disease progression, administration of the informant 
portion of the CDR should still be attempted. If a participant is taking intermittent or short-term 
regimens of medications known to impair consciousness or cognition, such medication must be 

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stopped 2 days or 5 half-lives (whichever is longer) prior to any cognitive or behavioral 
assessment. Use of cannabinoids (other than cannabidiol) is prohibited within 72 hours prior to 
any cognitive or behavioral assessment. 
6.5. 
Pharmacokinetic and Anti-Drug Antibody Assessments 
The PK blood collections will be performed, and AL002 concentrations will be measured (see 
Table 9). Blood samples for assessment of ADA will be taken throughout the study. 
6.6. 
Biomarker Assessments 
Blood-based biomarker and MRI biomarker measures will be assessed for all participants. In this 
study, several optional biomarker assessments will be performed. These include CSF collection, 
PET imaging with the tau radiotracer [18F]MK-6240, and longitudinal Amyloid PET imaging. 
Those who did not previously opt-in to these procedures in the AL002-2 study but opt-in for the 
LTE study may be required to complete these procedures during the screening/baseline period in 
order to establish a baseline before their Day 1/Week 1 dose. Please see sections related to study 
visits in this protocol and the footnotes in the Schedule of Assessments (Table 9) for details. 
Exploratory Pharmacodynamic Biomarker Assessments 
• The exploratory biomarker endpoints for this study are presented in Section 2. 
• The biomarker assessments will consist of, but are not limited to, blood-based 
biomarkers, CSF-based biomarkers, and imaging biomarkers, as follows: 
Blood-based biomarkers: 
− soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in plasma 
− Plasma biomarkers relevant to AD (eg, Aβ42, Aβ40, phosphorylated tau [pTau], 
neurofilament light [NfL]) 
Optional CSF-based biomarkers: 
− sTREM2 in CSF 
− CSF biomarkers relevant to AD (eg, Aβ42, Aβ40, tTau, pTau, NfL) and to 
microglia function (eg, chitinase 3-like 1 (YKL-40), osteopontin) 
− Other exploratory biomarkers 
Imaging biomarkers: 
− MRI measures 
− Optional longitudinal Amyloid PET and Tau PET imaging measures 
6.6.1. 
Fluid Biomarker Assessments 
6.6.1.1. 
Blood Biomarker Sampling 
Blood-based biomarker measures will be assessed for all participants. Assessments include 
evaluation of sTREM2 in plasma and other plasma biomarkers relevant to AD (eg, Aβ42, Aβ40, 
pTau, NfL). 

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6.6.1.2. 
Optional Cerebrospinal Fluid Sampling 
For participants who will participate in the optional CSF assessments, LPs should be completed 
only after the COAs have been administered (eg, Clinical Dementia Rating [CDR]). As outlined 
in Table 9, COAs should be performed prior to LPs performed on the same day. 
For all visits, if an LP and an MRI are performed in the same visit, either (a) the MRI should be 
performed first or (b) the MRI should be performed at least 3 days after the LP. This minimizes 
the effect of CSF removal on brain volume measurements. Also, for all visits, if an LP and a PET 
scan (Amyloid PET or Tau PET) are performed in the same visit, either (a) the LP should be 
performed first or (b) the LP should be performed at least 12 hours after the PET scan. 
Post-baseline CSF samples will be collected as specified in the Schedule of Assessments 
(Table 9) to evaluate PK, and exploratory biomarker measures. 
Participants will be required to stay in the clinic or hospital for a minimum of 30 minutes after 
the LP for safety monitoring. Any treated participant who discontinues prematurely should have 
CSF drawn, unless CSF has been drawn within 12 weeks of discontinuation. Please refer to 
Section 6.2 for information regarding sample collection. 
6.6.2. 
Imaging Assessments 
Imaging biomarkers will be assessed with MRI (all participants) and with optional PET scans 
using an amyloid tracer and/or the tau tracer [18F]MK 6240 (both optional). 
6.6.2.1. 
Optional PET Imaging Procedures 
The Sponsor, in conjunction with the imaging vendor, will prepare and distribute a detailed PET 
Imaging Procedures Manual for image acquisition, reconstruction procedures, and parameters for 
each center prior to the start of the study. All imaging data will be transferred to the imaging 
vendor for quality control and image analysis as documented in the PET Imaging Procedures 
Manual. 
Detailed methodology, including scanning procedures, is included in the PET Imaging 
Procedures Manual. 
6.6.2.1.1. Optional Amyloid PET Imaging 
In countries where local regulations allow, participants may either opt-in or opt-out of 
exploratory assessments to evaluate changes in the brain as measured by longitudinal Amyloid 
PET imaging. 
During screening/baseline, participants will consent to the optional longitudinal Amyloid PET 
imaging assessment. If the participant is eligible, the participant must agree and provide consent 
separately for the optional assessment as defined in Section 10.3. Refer to the PET Imaging 
Procedures Manual for further details. 
6.6.2.1.2. Optional Tau PET Imaging with [18F]MK-6240 
Participants in countries where local regulations allow may participate in an optional exploratory 
assessment to evaluate changes in the brain as measured by [18F]MK6240 Tau PET imaging. 

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Participants may travel to select imaging sites to undergo Tau PET imaging at the visits outlined 
in the Schedule of Assessments in Table 9. 
A PET imaging agent that binds to aggregated tau has the potential to serve as a biomarker for 
disease severity or neurodegeneration and may be useful for monitoring disease progression in 
therapeutic trials. Use of Tau PET imaging in this trial will allow the monitoring of the spatial 
progression of tau pathology in the brain, and the assessment of correlation of tau pathology with 
cognitive and functional outcome measures after extended AL002 dosing. Fluorine-18 MK-6240 
([18F]MK-6240) has been developed as a positron emitting radioligand for in vivo imaging of tau 
protein aggregates. Available safety data from the completed and ongoing clinical studies with 
[18F]MK-6240 show that exposure to [18F]MK-6240 and imaging procedures are generally well 
tolerated. There have been no deaths and no commonly recurring AEs following administration 
of [18F]MK-6240. Each [18F]MK-6240 scan involves a 5 mCi (185 megabecquerel) dose. The 
anticipated effective dose of each scan will be 6.4 mSv, including radiation from the associated 
attenuation CT scan. Refer to the [18F]MK-6240 IB for more details on these studies, including a 
full nonclinical evaluation of the tracer as well as the clinical experience to date and radiation 
precautions. 
Participants who consent at screening/baseline are eligible for the optional Tau PET imaging 
assessment. If the participant is eligible, agrees, and provides consent separately for this optional 
assessment as described in Section 10.3, additional safety assessments and Tau PET imaging 
procedures will be performed at the imaging site, as detailed in the PET Imaging Procedures 
Manual. 
Participants who undergo the optional Tau PET imaging assessment will receive [18F]MK-6240 
and undergo a PET scan on multiple occasions as described in the Schedule of Assessments in 
Table 9. Refer to the Study Design (Section 3.1) for details regarding the circumstances when 
Tau PET scans will be performed. The Schedule of Assessments (Table 9) specifies when a final 
Tau PET scan should be performed if a participant discontinues from the study, provided that 
local radiation limits have not been exceeded. 
If occurring at the same visit, Amyloid PET and/or Tau PET scans must be performed after 
administration of COAs. If occurring at the same visit, Amyloid PET and Tau PET scans must 
occur on different calendar days. If occurring at the same visit, Amyloid PET and/or Tau PET 
scans must be performed after MRI. PET scans should be performed only if the Investigator has 
determined that the total past and planned annual radiation exposure does not exceed local 
guidelines. 

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7. 
ASSESSMENT OF SAFETY 
The Investigator’s assessment of the relationship of an AE, SAE, or radiotracer AE to study drug 
is part of the documentation process, but it is not a factor in determining what is or is not 
reported in the study. If there is any doubt as to whether a clinical observation is an AE/SAE, the 
event should be reported. 
The Investigator is responsible for reporting all AEs/SAEs/AESI that are observed or reported 
during the study, from the time a participant signs the ICF until the EOS, regardless of clinical 
significance or of the AEs suspected relationship to study drug and/or radiotracer. 
7.1. 
Definition of Adverse Event 
AEs are any untoward medical occurrence in a participant enrolled into this study, including side 
effects, injury, toxicity, sensitivity reaction, intercurrent illnesses, clinically significant physical 
exam signs, or sudden death, whether or not it is considered related to the study drug. 
Participants will be instructed to contact the Investigator at any time after informed consent if 
any symptoms develop. Participants will be instructed to report all AEs to the Investigator. All 
AEs must be appropriately documented in the participant’s original source documents and on the 
eCRFs. Investigators should report the diagnosis rather than list symptoms, whenever possible. 
A treatment-emergent AE is defined as any event not present before exposure to study drug 
and/or radiotracer, and any event that worsens from baseline after exposure. 
Adverse events resulting from concurrent illnesses, reactions to concurrent illnesses, reactions to 
concurrent medications, or progression of disease states must also be reported within the 
established time frames. 
An AE does not include the following: 
• Elective medical or surgical procedures planned prior to the start of study drug 
(eg, hip replacement surgery) that did not result from a worsening of a pre-existing 
condition (ie, prior to signing informed consent). Note: Any serious procedural 
complication or hospital-emergent conditions (eg, nosocomial infection) that, for 
instance, prolongs the hospitalization would be reported as an SAE. 
• Any medical condition or clinically significant laboratory abnormality that has an 
onset date before the consent form is signed, and that is not related to a protocol-
associated procedure, is not an AE. A pre-existing condition should be reported as an 
AE only if its frequency, intensity, or symptoms worsen during the course of the 
study. 
• Situations where an untoward medical occurrence has not occurred 
(eg, hospitalization for study drug administration per institutional guidelines, elective 
surgery, social and/or convenience admissions). 
Disease progression within expected parameters for the study population is not considered an 
AE. See Section 7.3.1 for Protocol-Specific Disease Progression Adverse Event and Serious 
Adverse Event Reporting Requirements. 

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7.2. 
Adverse Events of Special Interest 
An AESI is a serious or nonserious AE which is of scientific and medical concern specific to a 
product for which ongoing monitoring and rapid reporting by the Investigator to the Sponsor 
should occur. AESIs are defined as the following occurrences: 
• ARIA-H 
− There are 3 categories of ARIA-H which are considered separate AESI. 
See Section 7.11 for additional details. 
• ARIA-E 
• 
 
For AESI, the most appropriate diagnosis should be recorded on the AE eCRF and reported to 
the Sponsor immediately (ie, no more than 24 hours after learning of the event) as an AESI, 
regardless of whether the AESI is deemed to have a possible relationship to the study drug or 
not. 
Management of ARIA are described in Section 7.11. 
 should be managed by an 
ophthalmologist and the Medical Monitor. 
The reporting of an AESI will trigger an auto notification email alert from electronic data capture 
(EDC) to the Medical Monitor. 
In the event that EDC is not functioning, the Investigator should utilize the back-up paper 
process described below for SAE reporting and clearly indicate if the event is nonserious or 
serious, and related or not related to study drug in the opinion of the Investigator, and that the 
event is assessed as an AESI. 
7.3. 
Definition of Serious Adverse Events 
An SAE is defined as any AE that fulfills one or more of the following criteria: 
• Results in death 
• Is immediately life-threatening 
• Requires inpatient hospitalization or prolongation of existing hospitalization 
• Results in persistent or significant disability/incapacity 
• Results in congenital anomaly/birth defect 
• Is an important medical event that may jeopardize the participant or may require 
medical intervention to prevent one of the outcomes listed above. 
Important medical events that may not meet one of the above criteria could be considered a SAE 
by the Investigator when, based upon appropriate medical judgment, they are considered 
clinically significant and may jeopardize the participant, or may require medical or surgical 
intervention to prevent one of the outcomes listed above. 

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An AE is considered “life-threatening” if, in the opinion of either the Investigator or the Sponsor, 
its occurrence places the participant at immediate risk of death. It does not include an AE that, 
had it occurred in a more severe form, might have caused death. 
7.3.1. 
Protocol-Specific Disease Progression Adverse Event and Serious Adverse Event 
Reporting Requirements 
Disease progression in this study is measured via the CDR-SB. Changes in these scores that are 
consistent with the expected rate of progression of the underlying disease should not be recorded 
as AEs. 
However, symptomatic deterioration or events that are judged by the Investigator to be 
inconsistent with normal disease progression or are considered related to study drug should be 
reported as AEs, and if any of the “serious” criteria are met, it must be reported as an SAE. 
Please note that the term “disease progression” should not be reported, but rather the clinical 
manifestation(s) with applicable descriptors should be captured on the AE eCRF page. 
7.4. 
Definition of Clinical Laboratory Abnormalities and Other 
Abnormal Assessments as Adverse Events/Serious Adverse Events 
Abnormal laboratory findings (eg, hematology, coagulation, chemistry, and urinalysis) or other 
abnormal assessments (eg, ECG, vital signs) per se are not reported as AEs. However, those 
abnormal findings that are deemed clinically significant or are associated with signs and/or 
symptoms must be recorded as AEs if they meet the definition of an AE (or recorded as an SAE 
if they meet the criteria of being serious) as previously described. Clinically significant abnormal 
laboratory or other abnormal findings that are detected after consent or that are present at 
baseline and worsen after consent are included as AEs (and SAEs if applicable). 
The Investigator should exercise medical and scientific judgment in deciding whether an 
abnormal laboratory finding, or other abnormal assessment is clinically significant. Usually, the 
abnormality should be associated with a clinically evident sign or symptom or be likely to result 
in an evident sign or symptom in the near term, to be considered clinically significant. 
A clinically significant laboratory abnormality in the absence of clinical symptoms may 
jeopardize the participant and may require intervention to prevent immediate consequences. For 
example, a markedly low serum glucose concentration may not be accompanied by coma or 
convulsions yet be of a magnitude to require glucose administration to prevent such sequelae. 
7.5. 
Assessment of Adverse Events 
7.5.1. 
Assessment of Adverse Event/Serious Adverse Event Severity 
The severity of an AE refers to the extent to which an AE affects the participant’s daily 
activities. Severity will be graded according to the Common Terminology Criteria for Adverse 
Events (CTCAE), Version 5.0 or later. If an AE is not specified within the CTCAE guidelines, 
then the AE will be graded according to the definitions in Table 6. 

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Table 6: 
Adverse Event Grading Criteria 
Grade Severity 
Description 
1 
Mild 
Asymptomatic or mild symptoms; clinical or 
diagnostic observations only; intervention not 
indicated 
2 
Moderate 
Minimal, local, or noninvasive intervention indicated; 
limiting age-appropriate instrumental ADLa 
3 
Severe or medically significant but 
not immediately life-threatening  
Hospitalization, or prolongation of hospitalization 
indicated; disabling, limiting self-care ADLb 
4 
Life-threatening consequences 
Urgent intervention indicated 
5 
Death 
Death related to AE 
ADL=activities of daily living, AE=adverse event. 
a Instrumental ADL refer to preparing meals, shopping for groceries or clothes, using the telephone, managing 
money, etc. 
b Self-care ADL refer to bathing, dressing and undressing, feeding self, using the toilet, taking medications, and not 
bedridden. 
Note that “severity” is a measure of intensity and that a severe AE is not necessarily an SAE. 
Changes in the severity of an AE should be documented to allow assessments of the duration of 
the events at each level of intensity. AEs characterized as intermittent do not require 
documentation of onset and end date of each episode. When the intensity of an AE changes more 
than once a day, the maximum severity for the event should be recorded for that day. If the 
intensity changes over a number of days, these changes should be recorded separately (eg, as 
having distinct onset dates on one or more eCRF lines). 
7.5.2. 
Assessment of Causality 
The relationship or association of the study drug or radiotracer, in causing or contributing to the 
AE, will be characterized using the following classification and criteria: 
Relationship to Study 
Drug or Radiotracer 
Comment 
Related 
There is reasonable possibility that the event may have been caused by 
study drug/radiotracer (eg, there is a plausible temporal relationship 
between the onset of the AE and administration of the study drug, and 
the AE cannot be readily explained by the participant’s clinical state, 
intercurrent illness, or concomitant therapies). 
Not Related 
The event can be readily explained by the participant’s underlying 
medical condition, concomitant therapy, or other causes, and therefore, 
the Investigator believes that it is unlikely that a causal relationship 
exists between the event and study drug or radiotracer. 
AE=adverse event. 
The Investigator should assess causality by answering either “related” or “not related” to the 
question “Is there a reasonable possibility that the event may have been caused by the study 
drug?” The following factors may be used in consideration of causality assessment: 

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• Challenge/rechallenge: Did the event abate after study drug was reduced or 
interrupted? Did the event reappear after study drug was reintroduced? 
• Temporal relationship and time to onset plausibility 
• Confounding risk factors 
• Amount and duration of study drug exposure 
• Concomitant medications 
7.6. 
Recording of Adverse Events 
7.6.1. 
Eliciting and Documenting the Adverse Events 
At every study visit after screening, participants will be asked a standard nonleading question to 
elicit any medically related changes in their well-being. They will also be asked if they have 
been hospitalized, had any accidents, used any new medications, or changed concomitant 
medication regimens (prescription drugs, herbal products, vitamins, minerals, vaccines, topical 
medications, and over-the-counter medications). Please refer to Section 7.2 and Section 7.6.4 for 
additional AEs and special situations that require immediate reporting to the Sponsor. 
Laboratory test values or investigational findings (eg, findings on ECGs, imaging, or 
examination) outside the normal reference range are not necessarily AEs. Only those that meet 
the following criteria should be reported as an AE: (1) is confirmed and the Investigator 
considers clinically significant, or (2) that requires a participant to be discontinued from the 
study, or (3) that requires a participant to receive treatment. Abnormal laboratory test values or 
investigational findings reported as AEs should be followed until satisfactory clinical resolution, 
participant withdrawal of consent, lost to follow-up, or death, whichever comes first. Specific 
instructions for recording of ARIA-E and ARIA-H as AESI are specified in Section 7.6.4. 
7.6.2. 
Recording the Action Taken with Study Drug in Response to AE/SAE 
Should the Investigator need to alter the administration of the study drug from the procedure 
described in the protocol in response to an AE/SAE, then the action taken will be recorded on the 
AE eCRF page as one of the following options: 
• Dose not changed 
• Drug interrupted 
• Drug withdrawn 
• Not applicable 
• Unknown 
7.6.3. 
Recording the Outcome and Follow-up of Participants Reporting an AE/SAE 
Outcome of an AE/SAE will be recorded on the AE eCRF as follows: 
• Recovered/resolved 

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• Recovered/resolved with sequelae (with sequelae being a condition that is the 
consequence of the reported event, and not the event in a lower grade/ severity) 
• Not recovered/not resolving 
• Fatal 
• Unknown 
7.6.4. 
Recording of ARIA-H and ARIA-E as Adverse Events of Special Interest 
Findings of ARIA-E or ARIA-H on MRI are determined by the MRI Central Reader (see 
Section 6.3.12 for more detail). Once confirmed by the BMW report, ARIA-H and ARIA-E will 
be captured as such on the AE eCRF and marked as AESI. For definitional details of ARIA-H 
and ARIA-E see Section 7.11. For details on how to enter AESI of ARIA in the AE eCRF, 
please see the CRF Completion Guidelines. 
7.6.5. 
Recording of 
 as Adverse Events of Special Interest 
Findings of u
s (eg, 
r) are determined by local ophthalmologists 
and will be captured as such on the AE eCRF and marked as AESI. 
7.7. 
Reporting Adverse Events 
7.7.1. 
Adverse Events and Serious Adverse Events Reporting 
Regardless of cause or relationship to study drug, all AEs/SAEs that occur after a participant 
signs the ICF until the EOS participation, regardless of clinical significance or of the suspected 
relationship of the AE to study drug and/or radiotracer, should be reported by the Investigator. 
All unresolved AEs and/or SAEs will be followed through their resolution, or until the 
participant returns to his or her baseline condition, or is lost to follow-up or dies of another 
cause. Additionally, SAEs considered related to the study drug or radiotracer, which occur at any 
time during the study, should be reported by the Investigator, regardless of the AE/SAE 
collection window. Definitions pertaining to AEs are provided in Section 7.1 and descriptions of 
AE grading criteria are provided in Table 6. 
Information to be collected includes but is not limited to the following: 
• Event term 
• Time and date of onset of event 
• Investigator-specified assessment of severity and relationship to study drug or 
radiotracer 
• Time and date of the end of the event or the date on which the event changes severity 
• All serious criteria (if applicable) 
• Any required treatment or evaluations 
• Event outcome 

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In the event of any SAE reported or observed during the study, the site is required to complete 
the AE eCRF within the EDC system, including the event seriousness criteria, within 24 hours of 
becoming aware of the event or aware of substantive new information relating to the event. 
Please note 2 additional scenarios requiring 24-hour reporting to the Sponsor: 
1. 
AEs assessed as related to the radiopharmaceutical, Neuraceq® (florbetaben F18 
injection). Please note: if the site’s imaging facility is located outside of the 
institutional facility, please ensure the imaging lab is aware of this requirement. 
2. 
Special situations (eg, overdose, occupational exposure, medication error) 
associated with Neuraceq® or the Alector study drug regardless of whether the 
special situation is associated with an AE and regardless of the Investigator’s 
causality assessment of the event to the radiotracer or Alector study drug. 
If the EDC system is not available, a paper Serious Adverse Event Report Form should be used 
and emailed to drugsafety@alector.com according to the instructions provided in the Study 
Specific Regulatory Binder. Once the EDC system becomes available, SAEs reported using a 
paper Serious Adverse Event Report Form should be entered in the EDC system. The interval for 
which AEs are reported as described above also applies to SAE reporting. 
The participant’s condition will be followed by the Investigator or designated Subinvestigator, as 
described in Section 7.9. If unscheduled visits are required, the participant will be asked to return 
to the study site for further follow-up. As additional information becomes available, such as 
hospital discharge notes and participant medical records, the Investigator or designee will update 
the SAE eCRF and other relevant documentation pertaining to the SAE, and these updates will 
be submitted to the Sponsor within 24 hours of knowledge. 
Alector is responsible for notifying applicable regulatory agencies of any unexpected fatal or 
life-threatening suspected adverse reaction as soon as possible, but in no case later than 
7 calendar days after the Sponsor's initial receipt of the information. In addition, Alector must 
notify the applicable regulatory agencies and all participating Investigators in an Investigational 
New Drug (IND) safety report of potential serious risks, from clinical trials or any other source, 
as soon as possible, but in no case later than 15 calendar days after Alector determines that the 
information qualifies for reporting. 
It is the Investigator’s responsibility to report all SAEs to Alector (covered in Section 7.7.1) in 
compliance with current regulations and it is Alector’s responsibility to ensure all safety 
reporting obligations are carried out in compliance with current legislation for expedited 
reporting of SAEs (including suspected unexpected serious adverse reactions). 
The Medical Dictionary for Regulatory Activities (MedDRA) Version 
1 or later will be used 
by Alector to code all AEs. 
7.8. 
Safety Monitoring 
For medical emergencies, contact Sponsor’s Medical Monitor or designee: 
 
 
 

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The Medical Monitor will review AE reports, compiled by Data Management, as described in the 
Medical Monitoring Plan. The Medical Monitor will review blinded study data on enrollment, 
abnormal laboratory results, and protocol deviations. These reports will collectively be known as 
the Medical Monitoring Report. 
7.9. 
Follow-Up of Adverse Events and Serious Adverse Events 
All AEs, SAEs, and AESIs that are deemed related, possibly related, or probably related to study 
drug must be followed until resolution, the condition stabilizes, the event is otherwise explained, 
the participant dies of another cause, or is lost to follow-up. The Investigator is responsible for 
ensuring that follow-up includes any supplemental investigations that may be indicated to 
elucidate as completely as practical the nature and/or causality of the AE/SAE/AESI. This may 
include additional laboratory tests or investigations, histopathological examinations, or 
consultation with other health care professionals. 
The Sponsor may request that the Investigator perform or arrange for the conduct of 
supplemental measurements and/or evaluations. If a participant dies during participation in the 
study or during the protocol-defined follow-up period, the cause of death should be reported as a 
SAE and the Sponsor should be provided with a copy of any postmortem findings, including 
histopathology. 
All AEs, AESIs, and SAEs that have not resolved by the end of the study, or that have not 
resolved upon discontinuation of the participant’s participation in the study, must be followed up 
until any of the following occurs: 
• The event resolves. 
• The event stabilizes. 
• The event returns to baseline, if a baseline value is available. 
• The participant withdraws consent. 
• The participant dies. 
• The event can be attributed to agents other than the study drug, [18F]MK-6240 
radiotracer, or to factors unrelated to study conduct. 
• It becomes unlikely that any additional information can be obtained (participant lost 
to follow-up or medical records are not received after demonstration of due diligence 
with follow-up efforts). 
After the protocol-defined follow-up period, if the Investigator becomes aware of any SAE that 
is assessed as related to an Alector study drug or radiotracer, the SAE must be reported to 
Alector within 24 hours of site awareness. 
7.10. 
Infusion Reactions 
Signs or symptoms of AEs during the infusion will be carefully monitored and treated according 
to standard of care. In addition, in the event of an infusion reaction, serum samples of PK and 
ADAs should be obtained, as well as a plasma sample for cytokine, etc. See Section 14.3 for 
information on the management of infusion-related reactions. 

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7.11. 
Amyloid-Related Imaging Abnormalities 
Among the brain abnormalities detected on MRI are ARIA, which are believed to reflect leakage 
of proteinaceous fluid or other blood products into the leptomeninges or brain parenchyma. The 
term ARIA was originally coined to describe specific brain abnormalities seen on MRI in anti-
amyloid clinical trials. Although MRI findings potentially caused by AL002 may or may not be 
related to disruption/mobilization of, or a reaction to, amyloid species in the brain parenchyma or 
vasculature, the term ARIA will be used in this protocol to describe such findings until the 
biological mechanism is better understood. Specifically, according to the convention developed 
to describe ARIA occurring in clinical trials of anti-amyloid immunotherapies, ARIA-E will 
refer to MRI findings of vasogenic edema and leptomeningeal/sulcal effusion, and ARIA-H will 
refer to MRI findings of cerebral microhemorrhages, leptomeningeal hemosiderosis (also known 
as superficial siderosis of the CNS), and cerebral macrohemorrhages. 
For the purpose of this protocol, 4 categories of ARIA will be tracked (see Section 7.6.4 for 
recording of AESIs of ARIA). These categories are ARIA-E, ARIA-H cerebral 
microhemorrhages, ARIA-H leptomeningeal hemosiderosis, and ARIA-H cerebral 
macrohemorrhages. Symptoms associated with ARIA-H and ARIA-E will be captured as 
separate AEs on the AE eCRF and linked to the applicable ARIA AE line number. All clinical 
signs and symptoms that are identified as associated with an ARIA finding will be entered as 
separate AEs on the AE eCRF. Based on evaluation of the participant for signs and symptoms, 
and review of safety findings by the Sponsor that possibly indicates the presence of ARIA, the 
Sponsor may request an unscheduled MRI be obtained. 
To maintain consistency of reporting across clinical sites, findings of ARIA-E or ARIA-H on 
MRI are determined by the MRI Central Reader by radiologists with expertise in assessing for 
ARIA and other abnormalities on brain MRI. ARIA-E, ARIA-H, and other findings are 
documented on and reported to the sites with the BMW report (see Section 6.3.12). The BMW 
provided by the central reader after each MRI examination scores ARIA-E (parenchymal 
vasogenic edema, leptomeningeal/sulcal effusion) according to: extent, location, number of sites 
involved, radiographic severity (mild, mild+, moderate, moderate+, severe), and changes since 
prior MRI exams. ARIA-E findings typically resolve radiographically and will be noted as such 
on the BMW of follow-up MRI scans. The BMW also documents occurrence and characteristics 
(location, size, number) of ARIA-H (parenchymal microhemorrhages and leptomeningeal 
hemosiderosis and macrohemorrhages). Radiographic severity of ARIA-H findings (“mild”, 
“moderate”, “severe”) is defined as follows for the 3 categories of ARIA-H (Table 7): 

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Table 7: 
ARIA-E and ARIA-H Radiographic Severity Scales 
ARIA-E Characterization: 
Severity/Grade 
<5 cm monofocal 
Mild (Grade 1) 
<5 cm multifocal 
Mild+ (Grade 2) 
5-10 cm monofocal 
Moderate (Grade 3) 
5-10 cm multifocal 
Moderate+ (Grade 4) 
>10 cm monofocal/multifocal 
Severe (Grade 5) 
Incident ARIA-H: 
Mild 
Moderate 
Severe 
Microhemorrhages 
1-4 
5-9 
10 or more 
Areas of leptomeningeal hemosiderosis 
NA 
1 
2 or more 
Macrohemorrhages 
NA 
NA 
1 or more 
ARIA-E=amyloid-related imaging abnormalities-edema; ARIA-H=amyloid-related imaging abnormalities-
hemosiderin deposits; NA=not applicable. 
Overall, ARIA-H radiographic severity is defined as the worst individual radiographic severity 
for microhemorrhages, leptomeningeal hemosiderosis or macrohemorrhages (eg, if there are 
4 incident microhemorrhages, 1 incident areas of leptomeningeal hemosiderosis, and no 
macrohemorrhages, then ARIA-H is rated as “Moderate”). 
ARIA-H findings very rarely resolve radiographically; it is more typical for ARIA-H findings to 
stabilize radiographically. Radiographic stabilization of an ARIA-H finding is defined as when a 
follow-up MRI scan shows no increase in number/size/extent of previously seen cerebral 
microhemorrhages, leptomeningeal hemosiderosis, and cerebral macrohemorrhages. 
7.11.1. 
Schedule of MRI Surveillance for ARIA 
Surveillance for treatment-emergent ARIA will be accomplished with MRI scans as described in 
the Schedule of Assessments (Table 9). 
If new or worsening ARIA is observed on any of the MRIs conducted, dosing should be 
managed as prescribed in the Dosing Guidelines for ARIA (see Table 8). 
7.11.2. 
Participant Follow-up for ARIA Events 
Participants with new or worsening radiographic evidence of ARIA on post-baseline MRI scans 
should be evaluated for neurological signs or symptoms during an unscheduled visit. 
Investigators should comprehensively review the BMW for the presence of ARIA or other 
abnormalities. When ARIA has been detected, follow-up BMWs should be reviewed for 
radiographic evolution/resolution/stabilization of findings. Investigators suspecting ARIA that 
has not been detected by the MRI Central Reader should contact the Medical Monitor. For 
instance, if a local radiologist detects a faint area of vasogenic edema or microhemorrhage, 
which was not documented in the BMW, the Investigator should contact the Medical Monitor. 

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If participants are determined to have ARIA related symptoms or signs, the Medical Monitor 
should be contacted within 48 hours. An evaluation of neurologic signs or symptoms may be 
assessed during an unscheduled visit. 
Participants with asymptomatic ARIA-E should be observed; for participants with mild or 
moderate symptomatic ARIA-E, the use of oral or IV steroids may be considered (see Table 8 
below). In the case of severe symptomatic ARIA-E, it is recommended to hospitalize the 
participant for close observation and consider the use of IV steroids such as high-dose 
dexamethasone or a similar agent. 
All new cases of ARIA-E and/or new cases of ARIA-H will require unscheduled MRI scans 
every 4-6 weeks until ARIA-E has resolved and/or until ARIA-H has stabilized without new 
findings. In addition, the Sponsor may request that additional unscheduled MRIs be performed 
for the detection and follow-up of ARIA. 
An Amyloid PET scan should be requested after the first occurrence of ARIA-E for those 
participants who have opted in to have longitudinal Amyloid PET performed. An unscheduled 
LP for CSF analysis and plasma may be requested, if not contraindicated, after any occurrence of 
ARIA-E and/or ARIA-H. 
Participants with MRI evidence of ARIA at any visit will be managed according to the 
guidelines in Table 8. 

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Table 8: 
Dosing Guidelines for ARIA 
Finding 
Asymptomatic/Symptomatic 
Action 
Milda ARIA-E 
Asymptomatic or Symptomatic 
Suspend dosing until resolution 
of ARIA-E or stabilization of 
ARIA-H. After resolution 
(ARIA-E) and/or stabilization 
(ARIA-H), if participant dosing 
is restarted, they must receive 
the same dose they received 
immediately prior to the 
ARIA-E/ARIA-H findings. 
After resuming dosing, 
5-10 days before their second 
post-resumption dose, 
participants must undergo an 
unscheduled MRI that must be 
assessed by the central reader 
for ARIA-E/H before the next 
dose is administered. 
Participants who are undergoing 
dose titration when the ARIA 
occurs may continue up-titrating 
at the second post-resumption 
dose. 
For mild or moderate 
symptomatic ARIA-E the use of 
oral or IV steroids can be 
considered. 
For severe symptomatic 
ARIA-E it is recommended to 
hospitalize the participant for 
close observation and consider 
the use of IV steroids such as 
high-dose dexamethasone or a 
similar agent. 
Moderateb ARIA-E 
Asymptomatic or Symptomatic 
Severe ARIA-E 
Asymptomatic or Symptomatic 
Mild or Moderate ARIA-H  
Asymptomatic 
Mild or Moderate ARIA-H 
Symptomatic 
Permanently discontinue 
treatment 
Severe ARIA-H 
Asymptomatic or Symptomatic 
Permanently discontinue 
treatment 
Seriousc ARIA-E or Serious ARIA-H 
Symptomatic 
Permanently discontinue 
treatment 

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Table 8: 
Dosing Guidelines for ARIA (Continued) 
Finding 
Asymptomatic/Symptomatic 
Action 
Seriousc ARIA-E or Serious ARIA-H 
Asymptomatic 
Suspend dosing until resolution 
of ARIA-E or stabilization of 
ARIA-H. After resolution 
(ARIA-E) and/or stabilization 
(ARIA-H), if participant dosing 
is restarted, they must receive 
the same dose they received 
immediately prior to the 
ARIA-E/ARIA-H findings. 
After resuming dosing, 
5-10 days before their second 
post-resumption dose, 
participants must undergo an 
unscheduled MRI that must be 
assessed by the central reader 
for ARIA-E/H before the next 
dose is administered. 
Participants who are undergoing 
dose titration when the ARIA 
occurs may continue up-titrating 
at the second post-resumption 
dose. 
A second occurrence of ARIA-E after 
full resolution of a prior occurrence of 
ARIA-E 
Asymptomatic or Symptomatic 
Permanently discontinue 
treatment 
ARIA=amyloid-related imaging abnormality; ARIA-E=amyloid-related imaging abnormality-edema; 
ARIA-H=amyloid-related imaging abnormality-hemosiderin deposits; MRI=magnetic resonance imaging. 
a Mild includes ‘mild’ and ‘mild+’, as scored on the BMW from the Central Reader. 
b Moderate includes ‘moderate-’ and ‘moderate+’, as scored on the BMW from the Central Reader. 
c Meets criteria for a SAE. 
7.12. 
 
Ophthalmological examinations will be conducted at baseline and approximately every 4 months 
to monitor for u
itis. These will include 
 examination, 
, 
y 
, and o
y. If evidence suggestive of u
e 
p
) is reported, the frequency of ophthalmologic 
examination should be increased to at least every 2 months until u
s is either ruled out or 
resolved. 
7.13. 
General Safety Monitoring 
7.13.1. 
Special Situations 
Special situations are nonstandard medical conditions that provide valuable information about an 
investigational product. All special situations associated with an AE or SAE should be recorded 
in the EDC system in the AE eCRF. Special situations associated with SAEs must be reported 
within 24 hours of becoming aware. Special situations associated with AEs should be reported 
promptly. 

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Special situations are defined as below: 
• Overdose: An overdose is any dose of study drug given to a participant or taken by a 
participant that exceeds the dose described in the protocol. There is no known 
treatment for AL002 overdose, and all participants should be monitored for AEs. 
• Off-label use: Situations where a medicinal product is intentionally used for a medical 
purpose not in accordance with the authorized product information. It's the use of a 
pharmaceutical drug for an unapproved indication or in an unapproved age group, 
dosage or route of administration. 
• Misuse: This refers to situations where the AL002 is intentionally and inappropriately 
used not in accordance with the prescribed or authorized dose, route of 
administration, and/or the indication(s) or within legal status of its supply. 
• Abuse: This corresponds to the persistent or sporadic, intentional excessive use of 
AL002, which is accompanied by harmful physical or psychological effects. 
• Medication error: A medication error is any dose of study drug given to a participant 
or taken by a participant that differs from the dose described in the protocol. 
Medication errors are not likely in the study, as the study drug is administered by IV 
infusion by trained personnel under the supervision of the Investigator or their 
designee. 
• Occupational exposure: This corresponds to an AL002 for human use as a result of 
one’s occupation. 
• Lack of efficacy/ effect: Efficacy is the ability of a drug, biologic or device to 
produce desired therapeutic effect independent of potency (amount of the product 
needed for desired effect). Lack of efficacy/ effect, therefore, is the evidence of less 
than the expected effect of a product. There might be subpopulations that have a 
higher risk for lack of efficacy/ effect; in order to identify such cases, one needs to 
consider types of events that may be reported in such situations for the specific 
product and indications. 
7.13.2. 
Pregnancy 
If applicable, pregnancy tests are to be performed at screening/baseline and/or at Week 49 and/or 
at EOS/ET (see Schedule of Assessments Table 9). Female participants must be instructed to 
discontinue all study drugs and inform the Investigator immediately if they become pregnant 
during the study. 
The Investigator must report any pregnancy within 24 hours of becoming aware of it using the 
paper Pregnancy Report Form. Follow-up information documenting the pregnancy outcome 
should be reported on the paper Pregnancy Report Form. The site should email the Pregnancy 
Report Form to drugsafety@alector.com, according to the instructions provided in the Study 
Specific Regulatory Binder. 
The participant must be immediately discontinued from study drug and/or PET imaging 
procedure. An uncomplicated pregnancy will not be considered an AE or SAE, but all 
pregnancies will be followed until a final outcome is known. 

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Pregnancies are captured if they occur in female participants or in the sexual partners of male 
participants from the time the participant is first exposed to the study drug or radiotracer until the 
final study visit. 
Any congenital abnormalities associated with a pregnancy that occurred during study 
participation are considered SAEs. The outcome of any pregnancy and complete health 
information regarding the fetus will be recorded in the source documentation and reported to 
Pharmacovigilance. 
Any SAE occurring in association with a pregnancy must be reported to Pharmacovigilance 
regardless of whether the events are considered related to study drug. 
7.13.3. 
Breastfeeding 
All AEs that occur in infants following exposure to a study drug from breastmilk should be 
reported. 

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8. 
STATISTICAL METHODS AND ANALYSIS PLAN 
All data for participants will be 
. Analyses may 
 
a of this AL002-LTE study. Missing data will not be imputed, unless otherwise 
specified in the statistical analysis plan (SAP). The SAP will provide further details regarding the 
analysis sets and planned analysis methodologies to address all study objectives. Statistical 
analyses will be performed using S
r 
). 
Continuous data will be summarized using an 8
 
), 
unless otherwise specified in the SAP. Categorical data will be summarized using 
 
p
, unless otherwise specified in the SAP. 
Any changes to the data summaries and analyses outlined in this section will be documented in 
the SAP. Additional statistical analyses other than those described in this section may be 
performed if deemed appropriate. Any deviations from the analysis planned in the SAP will be 
justified and recorded in the final clinical study report (CSR). 
Study endpoints are provided in Section 2. 
8.1. 
Sample Size Calculations 
It is expected that 8
 of the participants who completed the planned treatment period in 
the parent study AL002-2 (
, approximately) will roll over into this AL002-LTE study, 
corresponding to a sample size between approximately 1
 and 
 participants. 
Slower dose titration has the potential to substantially decrease the incidence of ARIA 
(Retout 2022). Assuming that 1 % of 50 participants in the Titration Cohort would experience 
ARIA-E using a slower titration in this LTE study and 0% of 8  participants in the AL002 
60 mg/kg treatment group would experience ARIA-E using a faster titration in the parent study 
AL002-2, the study has approximately 0% power to detect the difference in the 2 proportions 
aforementioned based on the P
 
. 
8.2. 
Analysis Sets 
The LTE Safety Analysis Set will include a
e 
A
y. 
Details of other analysis sets will be documented in the SAP. 
8.3. 
Statistical Analysis Methodology 
8.3.1. 
General Analyses 
8.3.1.1. 
Disposition of Participants 
Disposition will be summarized, presenting the n
y 
d
on. 

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8.3.1.2. 
Protocol Deviations 
A protocol deviation occurs when t
 
a
. 
8.3.1.3. 
Demographics and Other Baseline Characteristics 
Summary statistics will be provided for demographics a
 as 
r
d 
. 
8.3.1.4. 
Prior and Concomitant Medications 
Prior and concomitant medications will be coded using the WHO DD, September 2022 or later. 
A medication will be considered as “prior” if the stop date and time of administration are before 
the start of the first study drug administration on Day 1/Week 1, either in the parent study or the 
LTE study. A medication will be considered “concomitant” if the stop date and time of 
administration is after the start of study drug administration. If the date and time of 
administration contains partial information such that the attribution of concomitant 
administration cannot be ruled out, then it will be considered as concomitant. 
Prior medications, concomitant medications, exposure to study treatment, and compliance with 
treatment will be summarized. 
8.3.2. 
Efficacy Analyses 
All efficacy data will be summarized using a
. 
Details of efficacy analyses will be specified in the SAP. 
8.3.3. 
Safety Analyses 
Safety analyses will be based on the LTE Safety Analysis Set. 
AEs will be coded using the MedDRA Version 2 1 or later. They will be summarized by 
 
o
d 
l will be summarized similarly. 
Safety endpoints will be s
y. 
To evaluate the effect of dose titration on ARIA, the proportion of participants in the Titration 
Cohort who experienced ARIA-E using a slower titration in this LTE study will be tested against 
the proportion of participants in the AL002 0 mg/kg treatment group who experienced ARIA-E 
using a faster titration in the parent study AL002-2. Details of the statistical test for 2 proportions 
will be specified in the SAP. 
8.3.4. 
Pharmacokinetic Analyses 
Individual and mean serum AL002 concentration-time data will be 
. When available, the individual and mean CSF AL002 
concentration-time data will be ta
. 
Potential c
T 
 may be explored, as data allow. Additional m
, 

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, may 
be performed. The results of such additional analyses may be reported separately from the CSR. 
8.3.5. 
Exploratory Biomarker Analyses 
The exploratory biomarkers (including, but not limited to, 
, 
) will be summarized over time using descriptive statistics. 
Details of biomarker analyses will be specified in the SAP. 
8.3.6. 
Immunogenicity Analyses 
Immunogenicity as assessed by incidence of ADAs will be summarized descriptively. 
8.3.7. 
 
) may 
be performed. Details of the i
s will be provided in a separate SAP. 

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9. 
DATA QUALITY ASSURANCE AND PROTECTION 
This study will be conducted according to the ICH E6(R2) quality and risk processes described 
in the applicable procedural documents. The quality and risk management approach to be 
implemented in this study will be documented and will comply with the current ICH guidance on 
quality and risk management. 
All aspects of the study will be monitored for compliance with applicable government regulatory 
requirements, current GCP, the protocol, and applicable SOPs. The monitor will maintain current 
personal knowledge of the study through observation, review of study records and source 
documentation, and discussion of the conduct of the study with the Investigator and study site 
personnel. eCRFs and EDC will be utilized. The EDC system is validated and compliant with US 
Title 21 Code of Federal Regulations (CFR) Part 11 and applicable local regulations for GxP 
systems. Each person involved with the study will have an individual identification code and 
password that allows for record traceability. There may be an internal quality review audit of the 
data and additional reviews by the clinical monitor. 
9.1. 
Data Management 
As part of the responsibilities assumed by participating in the study, the Investigator agrees to 
maintain adequate case histories for the participants treated as part of the research under this 
protocol. The Investigator agrees to maintain accurate eCRFs and source documentation as part 
of the case histories. These source documents may include laboratory reports, recorded data from 
automated instruments, medical progress notes, email correspondence, and ECG strips. 
The Investigator will adhere to Good Documentation Practice, and investigative site personnel 
will enter participant data into the eCRF. The analysis datasets will be a combination of these 
data and data from other sources (eg, laboratory data). 
Clinical data management will be performed in accordance with applicable standards, and data 
cleaning procedures to ensure the integrity of the data, eg, identifying errors and inconsistencies 
in the data. AE terms will be coded using the MedDRA Version 
 or later, an internal 
validated medical dictionary, and concomitant medications will be coded using the WHO DD, 
September 2022 or later. 
After database lock, each study site will receive a digital file containing all of their site-specific 
eCRF data as entered into the EDC system for the study, including full discrepancy and audit 
history. Additionally, a digital copy of all of the study site’s data from the study will be created 
and sent to Alector for storage. The CRO will maintain a duplicate digital file copy for their 
records. In all cases, participant initials will not be collected or transmitted to Alector. 
9.2. 
Data Protection 
Alector will ensure that any collection and processing of personal data within the scope of and 
for purposes of this study will be carried out in compliance with applicable data protection laws, 
including the European General Data Protection Regulation 679/2016. 
Alector implements and maintains organizational and technical measures designed to protect 
personal data and avoid unauthorized access, disclosure, dissemination, alteration, or loss of 
information and processed personal data. Such organizational and technical measures include, 

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but are not limited to, physical access controls including monitoring of physical access, security 
locks, security guards, automated access controls, such as badges, visitor approval; encryption 
and pseudonymization of data (where appropriate); restricted user access relevant to the function 
and type of activity performed in relation to the clinical trial; audit controls and procedures to 
maintain integrity and protection of personal data; ability to ensure the ongoing confidentiality, 
integrity, availability, and resilience of processing systems and services; network, system, and 
application security by means of access rights management, logging of access, antivirus/anti-
malware protection and firewalls, and other security measures; ensuring detection of malware 
purposed for unauthorized deletion, blocking, copying of information, disabling security 
measures, and response to such attacks; transfer and disclosure controls and protections; means 
to restore the availability and access to personal information in a timely manner in the event of a 
physical or technical incident; logging of security events/incidents in information systems; 
procedures to detect within timely manner if a personal data breach has occurred and incident 
response plan and procedures for investigation, containment, reporting and resolution of 
incidents; backup procedures and business continuity plans and procedures; a process for 
regularly testing, assessing, and evaluating the effectiveness of technical and organizational 
measures for ensuring the security of the processing; and security and training awareness for 
employees and personnel managing clinical studies. 
All locations, personnel, and information systems that are used to perform services for the study 
will be covered. In addition, Alector will ensure the technical and organizational security 
measures described above, are regularly reviewed and updated to consider technological 
developments. 
Alector and its selected vendors working on behalf of Alector or institutions working with 
Alector for purposes of the study are contractually bound to protect confidentiality of records and 
coded personal data of the clinical participants, and Alector has implemented appropriate internal 
safeguards and controls to protect the confidentiality of records and personal data of study 
participants, including by appropriate access rights management on a need-to-know basis and 
confidentiality undertakings for personnel involved in the handling of study participant data. 
Alector will only receive coded (pseudonymized) personal data of clinical participants with the 
code being allocated and held by the sites for each study participant. The relevant codes and 
attribution tables will be kept confidential, and coded (pseudonymized) data will be used instead 
of direct identifiers in all materials associated with the study participant. Alector will neither 
receive nor request any information to attribute any coded data to any individual study 
participants, except as necessary in the context of activities required to comply with applicable 
laws and/or the regulatory clinical trial framework, including for purposes of (on-site) 
monitoring, inspections and/or regulatory audits. Alector will only share participant coded data 
as described in the ICF. 
Alector has implemented operational data breach response processes for responding to any data 
breach occurring at facilities and premises of Alector, its vendors, or institutions working with 
Alector, as required under applicable data protection laws. In case of the occurrence of any data 
breach, Alector will apply relevant measures to mitigate the risks to participant data as 
appropriate in relation to the specific context of the data breach, considering its source, 
underlying intentions, possibilities of recovery, etc. Any data breach presenting risks to the rights 
and freedoms of data participants will be reported to data protection authorities and/or data 

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participants in accordance with the requirements and timelines set forth under applicable data 
protection laws. 

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10. 
ETHICS 
10.1. 
Independent Ethics Committee or Institutional Review Board 
Federal regulations and the ICH guidelines require that approval be obtained from an IRB/IEC 
before participation of human participants in research studies. Before study onset, the protocol, 
informed consent, advertisements to be used for the recruitment of study participants, and any 
other written information regarding this study to be provided to the participant or the 
participant’s legal guardian must be approved by the IRB/IEC. Documentation of all IRB/IEC 
approvals and of the IRB/IEC compliance with ICH E6(R2): GCP will be maintained by the site 
and will be available for review by Alector or its designee. 
All IRB/IEC approvals should be signed by the IRB/IEC chairman or designee and must identify 
the IRB/IEC name and address, the clinical protocol by title or protocol number or both, and the 
date approval or a favorable opinion was granted. 
The Investigator is responsible for providing written summaries of the progress and status of the 
study at intervals not exceeding 1 year or otherwise specified by the IRB/IEC. The Investigator 
must promptly supply Alector or its designee, the IRB/IEC, and, where applicable, the 
institution, with written reports on any changes significantly affecting the conduct of the study or 
increasing the risk to participants. 
10.2. 
Ethical Conduct of the Study 
The study will be performed in accordance with the ethical principles that have their origin in the 
Declaration of Helsinki, ICH GCP, the protocol, and all applicable regulations. 
10.3. 
Participant Information and Consent 
A written informed consent in compliance with US Title 21 CFR Part 50 and any other 
applicable local health authority regulations shall be obtained from each participant before 
entering the study or performing any unusual or nonroutine procedure that involves risk to the 
participant. An informed consent template may be provided by Alector to investigative sites. If 
any institution-specific modifications to study-related procedures are proposed or made by the 
site, the consent will be reviewed by Alector or its designee or both before IRB/IEC submission. 
Once reviewed, the consent will be submitted by the Investigator to his or her IRB/IEC for 
review and approval before the start of the study. If the ICF is revised during the course of the 
study, all active participating participants (or legally authorized representative) must sign the 
revised form. 
Before recruitment and enrollment, each prospective participant or his/her legal guardian will be 
given a full explanation of the study and be allowed to read the approved ICF. Once the 
Investigator is assured that the participant/legal guardian understands the implications of 
participating in the study, the participant/legal guardian will be asked to give consent to 
participate in the study by signing the ICF. The participant’s study partner will also be asked to 
give consent to participate in the study by signing an ICF. 
If the study participant is not competent, a legally authorized representative must provide 
informed consent on their behalf, and the participant must provide assent, in accordance with the 
local regulations, guidelines, and IRB/IEC. Where not permitted by local regulations, 

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participants deemed not competent to provide consent by the Investigator will not be enrolled. 
As AD is a progressive neurodegenerative disease, some participants may become incompetent 
during the course of the study, and it is important to understand if AL002 is safe and effective in 
these participants. If the study participant becomes incompetent over the course of the study, a 
legally authorized representative will need to be identified and the participant will need to 
provide assent. 
Prior to agreeing to samples being retained for future testing outside of the main study, 
participants will provide informed consent in accordance with the SOPs of the investigational 
sites. 
The Investigator shall retain the signed original ICF(s) and give a copy of the signed original 
form to the participant or legal guardian. 
Optional LP for CSF collection 
If the participant is eligible, agrees, and provides additional consent for these optional 
assessments, in accordance with SOPs of sites, additional LP for CSF collection will be 
performed. 
Optional Tau PET imaging assessments 
If the participant is eligible, agrees, and provides additional consent for these optional 
assessments, in accordance with SOPs of sites, additional safety assessments and PET imaging 
procedures will be performed at the imaging site, as detailed in the PET Imaging Procedures 
Manual. 
Optional Amyloid PET imaging assessments 
If the participant is eligible, agrees, and provides additional consent for these optional 
assessments, in accordance with SOPs of sites, additional safety assessments and PET imaging 
procedures will be performed at the imaging site, as detailed in the PET Imaging Procedures 
Manual. 

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11. 
INVESTIGATOR’S OBLIGATIONS 
The following administrative items are meant to guide the Investigator in the conduct of the 
study but may be subject to change based on industry and government SOPs, working practice 
documents, or guidelines. Changes will be reported to the IRB/IEC but will not result in protocol 
amendments. 
11.1. 
Confidentiality 
All laboratory specimens, evaluation forms, reports, and other records will be identified in a 
manner designed to maintain participant confidentiality. All records will be kept in a secure 
storage area with limited access. Clinical information will not be released without the written 
permission of the participant (or the participant’s legal guardian), except as necessary for 
monitoring and auditing by Alector, its designee, the US FDA, other health authorities, or the 
IRB/IEC. 
The Investigator and all employees and coworkers involved with this study may not disclose or 
use for any purpose other than performance of the study any data, record, or other unpublished, 
confidential information disclosed to those individuals for the purpose of the study. Prior written 
agreement from Alector or its designee must be obtained for the disclosure of any said 
confidential information to other parties. 
11.2. 
Financial Disclosure and Obligations 
Investigators are required to provide financial disclosure information to allow Alector to submit 
the complete and accurate certification or disclosure statements required under US Title 21 
CFR 54. In addition, the Investigator must provide to Alector a commitment to promptly update 
this information if any relevant changes occur during the course of the investigation and for 
1 year following the completion of the study. 
Alector (or delegate) is not financially responsible for further testing or treatment of any medical 
condition that may be detected during the screening/baseline process. In addition, in the absence 
of specific arrangements, Alector (or delegate) is not financially responsible for further treatment 
of the participant’s disease. 
11.3. 
Investigator Documentation 
Prior to beginning the study, the Principal Investigator will be asked to comply with ICH 
E6(R2) 8.2 and US Title 21 of the CFR by providing the following essential documents, 
including, but not limited to: 
• IRB/IEC approval 
• Original Investigator-signed Investigator agreement page of the protocol 
• Form FDA 1572, fully executed, and all updates on a new fully executed Form FDA 
1572, or an equivalent form capturing this information. 
• Curriculum vitae for the Investigator and each Subinvestigator listed on Form FDA 
1572 (or equivalent to Form FDA 1572). 

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• Financial disclosure information to allow Alector to submit complete and accurate 
certification or disclosure statements required under US Title 21 CFR 54. In addition, 
the Investigators must provide to Alector a commitment to promptly update this 
information if any relevant changes occur during the course of the investigation and 
for 1 year after the completion of the study. 
• IRB/IEC-approved informed consent, samples of site advertisements for recruitment 
for this study, and any other written information regarding this study that is to be 
provided to the participant or legal guardian. 
• Laboratory certifications and normal ranges for any local laboratories used by the 
site, in accordance with US Title 42 CFR 493. 
11.4. 
Study Conduct 
The Investigator agrees that the study will be conducted according to the principles of ICH 
E6(R2). The Investigator will conduct all aspects of this study in accordance with all national, 
state, and local laws or regulations. Study information from this protocol will be posted on 
publicly available clinical trial registers before enrollment of participants begins. 
11.5. 
Adherence to Protocol 
The Investigator agrees to conduct the study as outlined in this protocol in accordance with ICH 
E6(R2) and all applicable guidelines and regulations. 
11.6. 
Adverse Events and Study Report Requirements 
By participating in this study, the Investigator agrees to submit reports of SAEs to Alector and/or 
IRB/IEC according to the timeline and method outlined in the protocol. In addition, the 
Investigator agrees to submit annual reports to the study site IRB/IEC as appropriate. 
11.7. 
Investigator’s Final Report 
Upon completion of the study, the Investigator, where applicable, should inform the institution; 
the Investigator/institution should provide the IRB/IEC with a summary of the study’s outcome 
and Alector and regulatory authority(ies) with any reports required. 
11.8. 
Records Retention 
Essential documents should be retained until at least 2 years after the last approval of a 
marketing application in an ICH region and until there are no pending or contemplated marketing 
applications in an ICH region or at least 2 years have elapsed since the formal discontinuation of 
clinical development of the study drug. These documents should be retained for a longer period, 
however, if required by the applicable regulatory requirements or by an agreement with Alector. 
It is the responsibility of Alector to inform the Investigator/institution as to when these 
documents no longer need to be retained. The trial master file will be created during the 
implementation phase of a study, maintained on an ongoing basis throughout the duration of the 
project and collated at the end of the study. 

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11.9. 
Publications 
After completion of the study, the data may be considered for reporting at a scientific meeting or 
for publication in a scientific journal. In these cases, Alector will be responsible for these 
activities and will work with the Investigators to determine how the manuscript is written and 
edited, the number and order of authors, the publication to which it will be submitted, and other 
related issues. Alector has final approval authority over all such issues. 
Data are the property of Alector and cannot be published without prior authorization from 
Alector, but data and publication thereof will not be unduly withheld. 

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12. 
STUDY MANAGEMENT 
12.1. 
Monitoring 
12.1.1. 
Independent Data Monitoring Committee 
The administrative structure will include an unblinded external iDMC, which will oversee 
participant safety in the study. All further details with regard to the composition, purpose, and 
duties of the iDMC are provided in a separate iDMC charter. 
The iDMC will perform the safety review of all available safety and tolerability data (including 
from the MRI, neurological, and ophthalmological examinations) from all participants in an 
unblinded manner approximately every 6 months. The iDMC may convene on an ad-hoc basis, 
as required, to review cumulative safety data. The iDMC will act in an advisory capacity to the 
Sponsor. The iDMC responsibilities will be detailed in a charter and will include, but not be 
limited to, the following: 
• Review the following documents before commencing activities as an iDMC: draft 
iDMC charter, IB, study protocols, template ICF, blank case report forms, and data 
monitoring plans 
• Evaluate the progress of the study; timeliness and quality of the data; participant 
recruitment, accrual, and retention; risk versus benefit to participants; and other 
factors that might affect the outcome of the study 
• Consider relevant information that may have an impact on participant safety or the 
ethics of the study 
• Make recommendations to the Sponsor concerning continuation, termination, or other 
modifications to the study based on their observations of the study and its data 
• Conduct routine review of data according to a preplanned schedule 
Further details will be included in the iDMC charter. 
12.1.2. 
Monitoring of the Study 
The clinical monitor, as a representative of Alector, has the obligation to follow the study 
closely. In doing so, the monitor will visit the Investigator and study site at periodic intervals, in 
addition to maintaining necessary telephone and letter contact. The monitor will maintain current 
personal knowledge of the study through observation, review of study records and source 
documentation, and discussion of the conduct of the study with the Investigator and personnel. In 
addition, under the exceptional circumstances of the COVID-19 pandemic, the monitor may 
follow the study closely through remote monitoring and/or remote conduct of Investigator and 
study site visits, as allowed per local regulations. Refer to Section 14.4 for additional details on 
remote source document verification as a result of the COVID-19 pandemic. 
All aspects of the study will be carefully monitored by Alector or its designee for compliance 
with applicable government regulation with respect to current GCP and current SOPs. 

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12.1.3. 
Inspection of Records 
Investigators and institutions involved in the study will permit study-related monitoring, audits, 
IRB/IEC review, and regulatory inspections by providing direct access to all study records. In the 
event of an audit, the Investigator agrees to allow Alector, representatives of Alector, and/or a 
regulatory agency access to all study records. 
The Investigator should promptly notify Alector and the CRO of any audits scheduled by any 
regulatory authorities. Dependent upon the scope of the regulatory authority audit, Alector may 
elect to assist the site in preparation or support. The Investigator should promptly forward copies 
of any audit reports received to Alector. 
12.2. 
Study Termination 
Although Alector has every intention of completing the study, Alector reserves the right to 
discontinue the study at any time for clinical or administrative reasons. 
The end of the study is defined as the date on which the last participant completes the last visit 
(including the EOS/ET Visit). 
12.3. 
Final Report 
Whether the study is completed or prematurely terminated, Alector will ensure that the CSR is 
prepared and provided to the regulatory agency(ies) as required by the applicable regulatory 
requirement(s). The Sponsor will also ensure that the CSR in marketing applications meets the 
standards of the ICH Harmonised Tripartite Guideline E3: Structure and Content of Clinical 
Study Reports. 
Where required by applicable regulatory requirements, an Investigator signatory will be 
identified for the approval of the CSR. The Investigator will be provided reasonable access to 
statistical tables, figures, and relevant reports and will have the opportunity to review the 
complete study results. 
Upon completion of the CSR, Alector will provide the Investigator with the full summary of the 
study results. The Investigator is encouraged to share the summary results with the study 
participants, as appropriate. The study results will be posted on publicly available clinical trial 
registers. 

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13. 
REFERENCE LIST 
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Arriagada PV, Growdon JH, Hedley-Whyte ET, et al. Neurofibrillary tangles but not senile 
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Colonna M and Wang Y. TREM2 variants: new keys to decipher Alzheimer disease 
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Cummings JL. Drug therapy: Alzheimer’s disease. N Engl J Med. 2004;351(1):56-67. 
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immunocytochemistry with a specific antibody and Bodian’s protargol method. Acta 
Neuropathol. 1987;73(2):167-70. 
Duyckaerts C, Delaére P, Hauw JJ, et al. Rating of the lesions in senile dementia of the 
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European Medicines Agency (EMA): CPMP/EWP/553/95 Rev.2. Guideline on the clinical 
investigation of medicines for the treatment of Alzheimer’s disease 2018. 
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medicines-treatment-alzheimers-disease-revision-2_en.pdf. Accessed 9 Aug 2022. 
European Medicines Agency: ICH S6 (R1) Preclinical safety evaluation of biotechnology-
derived pharmaceuticals. https://www.ema.europa.eu/en/ich-s6-r1-preclinical-safety-evaluation-
biotechnology-derived-pharmaceuticals. Accessed 9 Aug 2022. 
Folstein MF, Folstein SE, McHugh PR. “Mini-mental state”. A practical method for grading the 
cognitive state of patients for the clinician. J Psychiatr Res. 1975;12(3):189-98. 
Food and Drug Administration Center for Drug Evaluation and Research. Guidance for industry: 
suicidal ideation and behavior: prospective assessment of occurrence in clinical trials (FDA 
Maryland). 2012. 
Grundke-Iqbal I, Iqbal K, Tung YC, et al. Abnormal phosphorylation of the microtubule-
associated protein tau (tau) in Alzheimer cytoskeletal pathology. Proc Natl Acad Sci USA. 
1986;83(13):4913-7. 

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Guerreiro R, Wojtas A, Bras J, et al. TREM2 variants in Alzheimer’s disease. N Engl J Med. 
2013;368(2):117-27. 
Jack CR, Bennett DA, Blennow K, et al. NIA-AA Research Framework: Toward a biological 
definition of Alzheimer’s disease. Alzheimers Dement. 2018;14(4):535-562. 
Jay TR, Hirsch AM, Broihier ML, et al. Disease progression-dependent effects of TREM2 
deficiency in a mouse model of Alzheimer’s disease. J Neurosci. 2017a;37(3):637-47. 
Jay TR, von Saucken VE, Landreth GE. TREM2 in neurodegenerative diseases. Mol 
Neurodegener. 2017b;12(1):56. 
Jonsson T, Stefansson H, Steinberg S, et al. Variant of TREM2 associated with the risk of 
Alzheimer’s disease. N Engl J Med. 2013;368(2):107-16. 
Knight Alzheimer Disease Research Center, Clinical Dementia Rating (CDR®) Dementia 
Staging Instrument, Washington University in St. Louis. 
https://knightadrc.wustl.edu/professionals-clinicians/cdr-dementia-staging-instrument/ Accessed 
8 Aug 2022. 
Kosik KS, Joachim CT, Selkoe DJ. Microtubule-associated protein tau (tau) is a major antigenic 
component of paired helical filaments in Alzheimer’s disease. Proc Natl Acad Sci USA. 
1986;83(11):4044-8. 
Lee CYD, Daggett A, Gu X, et al. Elevated TREM2 gene dosage reprograms microglia 
responsivity and ameliorates pathological phenotypes in Alzheimer’s disease models. Neuron. 
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Leyns CEG, Gratuze M, Narasimhan S, et al. TREM2 function impedes tau seeding in neuritic 
plaques. Nat Neurosci. 2019;22(8):1217-22. 
McLean CA, Cherny RA, Fraser FW, et al. Soluble pool of Abeta amyloid determinant of 
severity of neurodegeneration in Alzheimer’s disease. Ann Neurol. 1999;46(6):860-6. 
O’Bryant SE, Lacritz LH, Hall J, et al. Validation of the new interpretive guidelines for the 
clinical dementia rating scale sum of boxes score in the national Alzheimer’s coordinating center 
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Ostrowitzki S, Deptula D, Thurfjell L, et al. Mechanism of amyloid removal in patients with 
Alzheimer disease treated with gantenerumab. Arch Neurol. 2012;69(2):198-207. 
Prince M, Wimo A, Guerchet M, et al. World Alzheimer Report 2015. The Global Impact of 
Dementia: An Analysis of Prevalence, Incidence, Cost and Trends. Alzheimer’s Disease 
International. 2015. https://www.alz.co.uk/research/world-report-2015. Accessed 25 May 2020. 
Rajagopalan P, Hibar DP, Thompson PM. TREM2 and neurodegenerative disease. N Engl 
J Med. 2013;369(16):1565-7. 
Randolf C, Williams JB, Hannesdottir K, et al. Telephone administration of the CDR: excellent 
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Randolph C. Pearson Repeatable Battery for the Assessment of Neuropsychological Status 
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Retout S, Gieschke R, Serafin D, et al. Disease modeling and model-based meta-analyses to 
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Tanzi RE. The genetics of Alzheimer disease. Cold Spring Harb Perspect Med. 
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Wang Y, Cella M, Mallinson K, et al. TREM2 lipid sensing sustains the microglial response in 
an Alzheimer’s disease model. Cell. 2015;160(6):1061-71. 
Wang Y, Ulland TK, Ulrich JD, et al. TREM2-mediated early microglial response limits 
diffusion and toxicity of amyloid plaques. J Exp Med. 2016;213(5):667-75. 
Wood JC, Mirra SS, Polock MJ, et al. Neurofibrillary tangles of Alzheimer’s disease share 
antigenic determinants with the axonal microtubules-associated protein tau (tau). Proc Natl Acad 
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14. 
APPENDICES 
14.1. 
Appendix 1: Schedule of Assessments 
Table 9: 
Schedule of Assessments 
Study Weeka 
 
 
 
 
 
 
1 
 
 
 
 
4  
 
4  
  
 
Visit Window 
 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
Informed consent 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Social historyb 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Demographic data 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Viral serologyc, e 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Height and weightf 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
Vital signsc, h, i 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
Complete PEk 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
x 
x 
Limited PEc, m 
 
 
 
 
x 
 
 
 
x 
 
 
 
 
 
 
 
Neurological examinationl 
x 
 
 
x 
 
x 
 
x 
 
x 
 
x 
 
x 
x 
x 
Ophthalmological 
examinationc, d 
x 
 
 
 
 
x 
 
 
 
x 
 
 
 
x 
x 
x 
Concomitant medicationsn 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
Study drug administration 
 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
 
 
Adverse eventsc, i, o 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
x 
ECG (single)c, p 
x 
x 
x 
 
x 
 
 
x 
 
 
 
 
 
x 
x 
x 
Pregnancy test  
(if applicable)j  
x 
 
 
 
 
 
 
 
 
 
 
 
 
x 
x 
x 
Thyroid functionc 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Table 9: 
Schedule of Assessments (Continued) 
Study Weeka 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Visit Window 
 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
±5d 
Folic acid and vitamin B12 
levelsc 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hematology and chemistryc, q, r 
x 
x 
 
 
x 
 
 
 
x 
 
 
x 
 
 
x 
x 
Coagulationc, s 
x 
 
 
 
 
 
 
 
 
 
 
 
 
 
x 
x 
Urinalysisc, t 
x 
x 
 
 
 
 
 
 
x 
 
 
 
 
 
x 
x 
C-SSRSc 
MRI (safety, PD)c, g, u 
CDRc, v, z 
MMSEc, v, z 
ADAS-Cog13c, v, z 
RBANS-Updatec, v, z 
ADCS-ADL-MCIc, v, z 
Serum PK sample(s)i 
Serum sample for ADAc, w 
Plasma sample for biomarkersc 
LP for CSF (optional)c, y, z, aa, cc 
Tau PET (optional)c, x, bb, cc, dd 
Longitudinal Amyloid PET 
(optional)c, x, cc, dd  
[18F]MK-6240=fluorine-18 MK-6240; ADA=anti-drug antibody (-ies); ADAS-Cog13=Alzheimer’s Disease Assessment Scale-Cognitive Subscale; ADCS-ADL-
MCI=Alzheimer’s Disease Cooperative Study-Activities of Daily Living – Mild Cognitive Impairment Scale; AE=adverse event; AESI=adverse event of special 
interest; ARIA=amyloid-related imaging abnormality; BMW=Brain MRI Worksheet; BP=blood pressure; C-SSRS=Columbia-Suicide Severity Rating Scale; 
CDR=Clinical Dementia Rating; COA=clinical outcome assessments; CSF=cerebrospinal fluid; d or D=day; ECG=electrocardiogram; eCRF=electronic case 
report form; EOS=End of Study; ET=early termination; ICF=informed consent form; LP=lumbar puncture; MMSE=Mini-Mental State Examination; 
MRI=magnetic resonance imaging; PD=pharmacodynamic(s); PE=physical examination; PET=positron emission tomography; PK=pharmacokinetic(s); 
RBANS-Update=Repeatable Battery for the Assessment of Neuropsychological Status-Update; RNA=ribonucleic acid; SCR=screening (ie, initial study visit); 
SAE=serious adverse event; WOCBP=woman of childbearing potential. 

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a. Study Day number and Study Week number begin with 1 on the day of the first administration of study drug. 
b. Only new events or changes in the participant’s social history prior to the initial dosing on Day 1/Week 1 are to be reported in the relevant social history 
section of the participant’s eCRF. 
c. The screening/baseline period will begin on or at the final dosing visit of the parent study AL002-2 and upon signing of the ICF. This period will be used to 
schedule and perform required safety and/or efficacy assessments not captured during the final dosing visit in the parent study AL002-2. It can also be utilized 
to schedule and perform optional biomarker assessments prior to dosing on Day 1/Week 1. If the COAs or LP were collected in the last 12 weeks prior to 
Day 1/Week 1 or if the PET scans were done in the last 24 weeks prior to Day 1/Week 1, these will not have to be collected during the screening/baseline 
period. If the COAs or LP were collected in the 12 weeks preceding the ET Visit, these will not have to be collected at the ET Visit. If the PET scans were 
done in the 24 weeks preceding the ET Visit, these will not have to be collected at the ET Visit. The C-SSRS must always be collected during the 
screening/baseline period and at the ET Visit regardless of the last collection date. If an ophthalmological examination was performed within the last 8 weeks, 
it will not be required at EOS/ET. 
d. Ophthalmologic examinations have a window of ±14 days (longer than the standard visit window). See Section 7.12 for additional examinations required for 
findings suggestive of 
s. 
e. Viral serology panel includes: human immunodeficiency virus (-1 or -2 antibody and antigen), hepatitis B surface antigen, hepatitis B surface antibody, total 
hepatitis B core antibody, and hepatitis C antibody/RNA. Participants with a positive hepatitis C virus antibody will be allowed if hepatitis C RNA is negative. 
f. Height and weight will be measured at screening/baseline; weight will also be measured at all other indicated timepoints. 
g. Perform/collect prior to dosing. For all post-screening MRIs, the MRI should occur at least 5 days prior to the next dose administration and no more than 10 
days prior to the next dose administration, with results received from the central imaging vendor prior to dosing. Note that the central imaging vendor typically 
requires 5 business days after receipt of the MRI before sending a BMW to the site. MRIs may be scheduled outside of the prescribed window, with approval 
from the Medical Monitor. The Sponsor may request that additional unscheduled MRIs be performed for the detection and follow-up of ARIA. Participants 
with MRI evidence of ARIA should be managed according to instructions provided in Table 8. 
h. Vital signs include temperature, respiratory rate, pulse rate, and systolic and diastolic BP while the participant is at rest in a supine position for at least 
3 minutes. Heart rate and BP measurements should be obtained with a validated digital monitoring device where available and an appropriately sized cuff. The 
same arm should be used for all BP measurements if possible. Heart rate and BP should not be measured unless 15 minutes have passed since the last blood 
draw. 
i. Perform/collect prior to dosing, and at the end of the infusion. Vital signs will be collected and concomitant medications and AEs documented prior to and at 
the end of infusion. On dosing visits, serum PK samples will be collected pre-dose. On non-dosing visits, serum PK samples may be collected at any time 
during the visit. Blood samples for assessment of ADA will be taken throughout the study. 
j. Urine pregnancy test (WOCBP only) and vital signs will be performed, and concomitant medications and AEs will start being collected at the 
screening/baseline visit and subsequent visits for those participants participating in a Tau PET scan. 
k. Complete PE includes evaluation of the head, eyes, ears, nose, and throat, and the cardiovascular, dermatological, musculoskeletal, respiratory, and 
gastrointestinal systems. Breast, rectal, and genitourinary exams should be performed as clinically indicated. Limited exams should include cardiovascular, 
respiratory, and gastrointestinal systems. Symptom-directed PEs may also include any other pertinent system as required. 
l. Neurological examination includes an evaluation of consciousness, orientation, cranial nerves, motor and sensory system, coordination and gait, and reflexes. 
m. Perform a limited, symptom-directed PE at specified timepoints or as clinically indicated. 
n. Includes any medication (eg, prescription drugs, herbal or homeopathic products, vitamins, minerals, vaccines, topical medications, and over-the-counter 
medications) used by a participant from 14 days prior to initiation of study drug to the final study visit. 

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o. AEs, AESIs, and SAEs will be assessed after the participant signs the informed consent until the EOS participation. Any unresolved AEs, AESIs, and SAEs 
will be followed up through resolution or return to baseline. Additionally, SAEs considered related to study drug or [18F]MK-6240 radiotracer, which occur at 
any time during the study, will be reported until resolution, participant withdrawal of consent, loss to follow-up, or death, whichever is applicable. Definitions 
describing what is and is not considered an AE are provided in Section 7. 
p. A single 12-lead ECG will be obtained before blood draws (pre-dose) on appropriate days. A single 12-lead ECG will be performed pre-dose and 60 to 90 
minutes after the end of infusion on Day 1/Week 1, Weeks 5, 13, 25, and 49. The ECG must be performed after the participant has been resting (supine) for 10 
minutes. 
q. Hematology includes hemoglobin, hematocrit, mean corpuscular hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin concentration, white 
blood cells, red blood cells, platelet count, and differential count (neutrophils, lymphocytes, monocytes, basophils, eosinophils, and other cells). 
r. Chemistry panel (serum or plasma) includes sodium, potassium, chloride, calcium, glucose, bicarbonate, albumin, total protein, creatinine, hemoglobin A1c, 
blood urea nitrogen or urea, aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transpeptidase, alkaline phosphatase, phosphorus, total 
bilirubin (direct and indirect), amylase, cholesterol (total, low-density lipoprotein, high density lipoprotein), triglycerides, uric acid, creatine phosphokinase, 
lactate dehydrogenase, magnesium, and C-reactive protein. 
s. Coagulation panel includes prothrombin time with international normalized ratio, activated partial thromboplastin time. If the LP is required for the EOS, the 
coagulation panel will be performed at the visit immediately preceding the EOS Visit within 4 weeks ±5 days. 
t. Urinalysis: Dipstick (pH, specific gravity, glucose, protein, ketones, blood). Microscopic analysis in the event of abnormal dipstick results (urinary sediment, 
red blood cells, white blood cells, casts, crystals, epithelial cells, bacteria). 
u. Screening/baseline MRI is to occur as close to the beginning (Day -28) of the window as possible and at least 10 days prior to enrollment, for those who have 
not had a brain MRI in the 90 days preceding the first dose on Day 1/Week 1. 
v. Perform COAs prior to any potentially stressful procedure (eg, LPs, imaging). 
w. Additional ADA samples should be collected in participants with signs and symptoms of infusion-related reactions. A corresponding additional PK sample 
should be obtained at the same timepoint. 
x. Informed consent and confirmation of eligibility must be received prior to performing PET scans. 
y. Participants who discontinue due to ARIA may be requested to have an LP per Investigator discretion. 
z. Per footnote v, COAs should be performed prior to LP, If possible, LP should not be performed on the same day when COAs are performed. Participants will 
be required to stay in the clinic or hospital for a minimum of 30 minutes after the procedure. LPs performed during the screening/baseline period will be 
performed at least 5 days prior to the expected Day 1/Week 1 dosing visit. LP should not be performed unless results from coagulation laboratory assessments 
were within clinically acceptable limits within 4 weeks ±5 days. 
aa. If an ET Visit is initiated, the final optional CSF sampling should be performed at that visit. If an ET is not initiated, optional CSF sampling should be 
performed at 
 
bb. For participants in countries where local regulations allow, baseline (optional) Tau PET imaging should be performed prior to dosing on Day1/Week1 unless 
obtained within 24 weeks before Day 1/Week 1 in study AL002-2. In some cases, the initial (baseline) Tau PET scan may be performed after dosing with study 
drug has commenced. Sponsor agreement will be needed for baseline Tau PET scans occurring after dosing has commenced. Participants who receive an 
optional Tau PET scan at baseline will receive 1 or more repeated scans after beginning study drug. PET imaging has a window of ±28 days (longer than the 
standard visit window). 
cc. If an LP and an MRI are performed in the same visit, either (a) the MRI should be performed first or (b) the MRI should be performed at least 3 days after the 
LP. This minimizes the effect of CSF removal on brain volume measurements. If an LP and a PET scan are performed in the same visit, either (a) the LP 

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should be performed first or (b) the LP should be performed at least 12 hours after the PET scan. Participants who undergo both Tau PET and Amyloid PET 
exams at a given study visit must receive these exams on different calendar days. 
dd. New longitudinal Amyloid and Tau PET imaging are required as the baseline scan for longitudinal Amyloid and Tau PET imaging if the participant opts in to 
the optional procedures unless already obtained within 24 weeks before Day 1/Week 1 in study AL002-2. PET imaging has a window of ±28 days (longer than 
the standard visit window). Tau PET scans or Amyloid PET scans should not be performed if local restrictions for radiation exposure would be exceeded; if 
applicable, the site should contact the Sponsor to discuss alternative timing of Tau PET or Amyloid PET scans. 

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14.2. 
Appendix 2: Clinical Outcome Assessments – Neurocognitive and 
Functional Tests 
14.2.1. 
Clinical Dementia Rating 
Washington University’s CDR is a global assessment instrument that yields a global score, 
which is weighted toward memory (eg, Global CDR Score). The sum of boxes (ie, CDR-SB) 
score is a quantitative general index that provides more precision than the Global CDR Score in 
participants with mild dementia (O'Bryant 2010). The CDR characterizes 6 domains of 
cognitive and functional performance applicable to AD and related dementias: Memory, 
Orientation, Judgment and Problem Solving, Community Affairs, Home and Hobbies, and 
Personal Care. The necessary information to make each rating is obtained through a 
semi-structured interview of the participant and a reliable informant or collateral source (the 
study partner). Details of the CDR, including the algorithm used to compute the Global CDR 
Score, can be found at the Knight Alzheimer Disease Research Center’s website. 
14.2.2. 
Mini-Mental Status Examination 
The MMSE (Folstein 1975) is a brief test used to screen for cognitive impairment. It is routinely 
used for estimating the severity of cognitive impairment and tracking cognitive changes in an 
individual over time. The MMSE assesses orientation (time and place), registration, attention and 
calculation, recent memory, language (naming, comprehension, and repetition), and 
constructional praxis (copying a figure). The maximum total score is 30, with a higher score 
indicating better cognitive performance. 
14.2.3. 
Repeatable Battery for the Assessment of Neuropsychological Status 
The RBANS for this study uses the updated version and is referred to as the RBANS-Update 
(Randolph 2013); it is a collection of 12 subtests representing 5 neurocognitive domains: 
Immediate Memory, Visuospatial/Constructional, Language, Attention, and Delayed Memory. 
The raw scores from each subtest within a domain are converted to a summary score, or Index 
Score, for the domain by consulting normative data tables. The RBANS-Update also provides an 
overall Index Score that summarizes the participant’s overall level of performance on this 
measure. 
14.2.4. 
Alzheimer's Disease Assessment Scale-Cognitive Subscale 
The ADAS-Cog is one of the most frequently used tests to measure cognition in clinical trials for 
AD. The ADAS-Cog13 is a 13-item version of the test that assesses immediate and delayed 
memory, confrontational naming, ability to follow commands, ideational and constructional 
praxis, orientation, language, and attention. 
14.2.5. 
Alzheimer's Disease Cooperative Study-Activities of Daily Living – Mild 
Cognitive Impairment Scale 
The ADCS-ADL-MCI assesses the competence of participants with AD in basic, instrumental, 
and complex activities of daily living; this scale is administered to the study partner. 

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14.2.6. 
Alzheimer’s Disease Composite Score (ADCOMS) 
The ADCOMS (Wang 2016) is a composite measure comprising 4 items from the ADAS-Cog13, 
2 items from the MMSE, and the 6 individual domain scores from CDR (Wang 2016). The 
ADCOMS has shown improved sensitivity to clinical decline in the early AD dementia 
populations. The ADCOMS score will be derived from the scores on other COAs described in 
this section; there is no separate scale to administer to participants or study partners. Details of 
the ADCOMS have been published (Wang 2016). 
14.3. 
Appendix 3: Management of Infusion-Related Reactions 
Monoclonal antibodies such as AL002 may be associated with the potential risk for 
infusion-related reactions. Acute infusion-related reactions typically occur within 24 hours of 
infusion and may manifest as erythema, pruritis, fever, or chills and progress to an 
anaphylactic-type reaction. Clinical sites should be prepared to manage any acute 
hypersensitivity or hypersensitivity-like events. All participants will be monitored for infusion 
reactions or injection reactions during the infusion/injection and immediately afterwards. 
Table 10 provides guidelines on management of acute infusion reactions as well as management 
of subsequent dosing instructions. 
Table 10: 
Guidelines for Management of Acute Infusion-related Reactions 
CTCAE Toxicity 
Grade 
Treatment 
Premedication at 
Subsequent Dosing 
Grade 1 
Mild transient reaction; 
infusion interruption not 
indicated; intervention 
not indicated 
Stop infusion and monitor symptoms. If symptoms resolve 
without intervention, the infusion may be restarted at 50% 
of the original infusion rate. 
None 
Grade 2 
Therapy or infusion 
interruption indicated 
but responds promptly to 
symptomatic treatment 
(eg, antihistamines, 
NSAIDs, narcotics, IV 
fluids); prophylactic 
medications indicated 
for ≤24 hours  
Stop infusion and monitor symptoms. Additional 
appropriate medical therapy may include, but is not limited 
to, IV fluids, antihistamines, and antipyretics. Increase 
monitoring of vital signs as medically indicated until the 
participant is deemed medically stable in the opinion of the 
Investigator. 
 
If symptoms resolve following supportive treatment, the 
infusion may be restarted at 50% of the original infusion 
rate. Otherwise, dosing will be held until symptoms resolve 
and the participant should be premedicated for the next 
scheduled dose. If IRR occurs during titration (ie, at first or 
second dose), next dose should be administered at 50% of 
the original infusion rate. 
Participants who develop Grade 2 toxicity despite adequate 
premedication and infusion rate reduction should be 
permanently discontinued from further trial treatment 
administration. 
Participant should be 
premedicated prior to 
next dose of study 
drug with 
antihistamine 
(eg, diphenhydramine 
50 mg po) and 
antipyretic 
(eg, acetaminophen / 
paracetamol 
500-1000 mg po). 

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Table 10: 
Guidelines for Management of Acute Infusion-Related Reactions 
(Continued) 
CTCAE Toxicity 
Grade 
Treatment 
Premedication at 
Subsequent Dosing 
Grades 3 or 4 
 
Grade 3: 
Prolonged (eg, not 
rapidly responsive to 
symptomatic medication 
and/or interruption of 
infusion); recurrence of 
symptoms following 
initial improvement; 
hospitalization indicated 
for clinical sequalae 
 
Grade 4: 
Life-threatening 
consequences; urgent 
intervention indicated 
Stop infusion and increase monitoring of vital signs as 
medically indicated. Additional appropriate medical therapy 
may include, but is not limited to, IV fluids, IV steroids 
(eg, hydrocortisone 100-200 mg or corticosteroid 
equivalent), IV antihistamines, vasopressors, and 
antipyretics. Hospitalization may be indicated. 
Participants with signs or symptoms that may be consistent 
with cardiac etiology should be assessed by ECGs, cardiac 
enzymes (eg, creatinine-MB isoenzyme, troponins, brain 
natriuretic peptide) to rule out myocardial infarction, and 
echocardiogram should be performed unless cardiac failure 
is ruled out by preceding investigations. 
Participant is permanently discontinued from further trial 
treatment administration. 
Any participant with a 
serious Grade 3 or any 
Grade 4 event will not 
be permitted to 
re-dose. Any 
subsequent redosing 
of nonserious Grade 3 
events must be 
discussed and 
approved by the 
Medical Monitor. 
CTCAE=Common Terminology Criteria for Adverse Events; ECG=electrocardiogram; IRR=infusion-related 
reaction; IRR=infusion-related reaction; IV=intravenous; MB=myocardial band; NSAIDs=non-steroidal anti-
inflammatory drugs; po=orally. 
14.4. 
Appendix 4: Adaptation of Trial Protocol During COVID-19 
Pandemic 
Due to the COVID-19 pandemic, the parent study included certain adaptations outlined below 
that may continue to be applied as appropriate during the extension study. 
14.4.1. 
Background 
The COVID-19 pandemic has caused significant disruption globally. The public health 
emergency will have an impact on the conduct of global clinical research activities. The safety 
and well-being of study participants, personnel involved in clinical studies, and colleagues across 
the globe is of primary importance. Alector is closely monitoring the situation and will continue 
to align clinical study execution with guidance from the World Health Organization and the US 
Centers for Disease Control as appropriate, conducting ourselves in accordance with all 
applicable national, regional, and local government and public health authority requirements. 
Alector made a decision to initiate and conduct the AL002-LTE study at the discretion of the 
Principal Investigator, and in accordance with current health authority guidelines and 
recommendations for each site’s region/country regarding the COVID-19 pandemic. The safety 
of all participants and site staff continues to be of paramount importance with regard to their 
continuation within the study. 
An ongoing collaborative risk review, which includes analysis of COVID-19 restrictions as they 
impact participant safety, study and data integrity, and impact on program timelines, continues to 
be assessed. The review has been and will continue to be conducted regularly and will take into 

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consideration any new information regarding the pandemic and ongoing, continuous assessment 
of AEs reported. 
14.4.2. 
Implementation of COVID-19 
The implementation of adaptations to visits and procedures detailed within this appendix only 
applies under the exceptional circumstance of the COVID-19 pandemic. Procedures apply to 
those sites which have been impacted by the pandemic through restrictions to movement, study 
site restrictions, and where the safety of the participant may be impacted through attendance at 
hospital for on-site visits. 
The implementation will be determined on a site-by-site basis dependent on local requirements 
and will be reviewed on a regular basis with the Sponsor to confirm the continued need for 
implementation. Every effort should be made to follow the Clinical Study Protocol; however, for 
clarity additional instructions are provided below. Where applicable, study-specific instructions 
will be communicated separately. 
14.4.3. 
Study Screening/Baseline Period 
Every effort should be made to complete the screening/baseline assessment per the Schedule of 
Assessments detailed in Table 9. At the discretion of the Sponsor, the screening/baseline period 
may be extended up to an additional 4 weeks to accommodate COVID-related delays in 
reporting screening/baseline results. Extension of the screening/baseline period will be on a 
case-by-case basis, and Sponsor approval must be obtained prior to extending the 
screening/baseline window beyond 8 weeks. Extension of the screening/baseline window may 
necessitate repetition of some screening/baseline tests. 
14.4.4. 
Essential On-Site Assessments and Remote Visits (Via Phone or Video) 
Continuation of the study during the pandemic does, and may continue to, impact the ability of 
some sites to conduct all protocol assessments per the Schedule of Assessments detailed in 
Table 9. This is due to reduced time for on-site visits, limited or no availability of some services 
at site, or the need to conduct visits remotely via telephone or via televisit (if approved locally). 
The primary objective with any change to the study schedule is to ensure ongoing monitoring of 
participant safety. 
14.4.4.1. On-site Essential Assessments 
Where possible, all protocol assessments and treatments should be completed. 
To accommodate reduced time on site during study visits, the following reduced assessments 
schedule should be completed as a minimum: 
• Vital signs, weight, physical, ophthalmological, and neurological examinations 
• Phlebotomy and urinalysis, including pregnancy test 
• ECGs 
• Collection of AEs and concomitant medications 
• C-SSRS 

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• Study drug administration 
• MRI 
• PET imaging 
• Biofluid collection for biomarkers (CSF or blood). In the case of LPs for CSF 
collection, a normal coagulation result must be available prior to taking the lumbar 
puncture 
14.4.4.2. Remote Essential Assessments (Telemedicine or Televisits) 
If participants or raters are not able to come to the study site for a visit, the following 
assessments should be completed by telephone or video (if locally approved/allowed): 
• Review of AEs and concomitant medications 
• The following COAs listed below can be completed remotely via telephone by 
qualified raters: 
1. Clinical Dementia Rating – Sum of Boxes (CDR®) 
While it is strongly preferred that participants and caregivers receive administration 
of the CDR® in person, it is understood that remote administration might be required 
due to extenuating circumstances. The CDR can be administered telephonically or 
by locally approved video conference capabilities. 
− Recommendation: Remote administration by phone has been validated for the 
6 domains of the CDR (Randolf 2014). 
− In the circumstance that the primary rater is remote, and the participant and 
back-up rater are on site, scales can still be administered by the primary rater. The 
primary rater should call in to the visit to administer the CDR® questions over the 
phone. The back-up rater should observe the participant while they are answering 
the questions and then provide observations of the participant behavior to the 
primary rater. Missing data from direct observation, which cannot be provided by 
the primary rater, can be completed by the back-up rater, as long as they are 
appropriately trained on the scale. Final observational assessments should be 
made by the primary rater. 
2. Alzheimer’s Disease Cooperative Study-Activities of Daily Living-Mild 
Cognitive Impairment Scale (ADCS-ADL-MCI) 
− Recommendation: As a clinician-administered interview with the caregiver, the 
ADCS-MCI-ADLI can be administered in person in the clinic, in home, or 
telephonically. 
− In the circumstance that the primary rater is remote, and the participant and 
back-up rater are on site, scales can still be administered by the primary rater. The 
primary rater should call in to the visit to administer the ADCS-ADL-MCI 
questions over the phone. The back-up rater should observe the caregiver (study 
partner) while they are answering the questions and then provide observations of 
caregiver behavior to the primary rater. Missing data from direct observation, 

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which cannot be provided by the primary rater, can be completed by the back-up 
rater, as long as they are appropriately trained on the scale. Final observational 
assessments should be made by the primary rater. 
3. Columbia-Suicide Severity Rating Scale (C-SSRS) 
− Recommendation: This assessment can be administered to the participant by a 
clinician via phone. 
The remote assessments would be administered by the qualified site staff authorized to perform 
the procedures above. The following general guidelines for administering scales telephonically 
or by video conference should be followed: 
• Always record on the notes page of the scale or in your source documents when a 
certain assessment was administered remotely and describe any accommodations 
made. 
• Ensure that scale administration guidelines indicated in the scale manual and tutorial 
are carefully followed when adapted for use via telephone. 
• Raters are encouraged to consider and address possible distractions which could 
affect performance during an assessment. This includes forms of distraction that may 
not be obvious or visible (eg, sight, sound, and smell). Consider the quality of the 
telecommunication technologies being used and the hardware requirements needed in 
order to conduct the specific assessment (eg, a telephone with speakerphone). 
• Always use the speaker phone for the scales that should be recorded for independent 
review. 
• Scales should be administered as if informant (rater) and/or participant/caregiver were 
face-to-face with the rater and should be administered in a quiet, distraction-free 
interview environment. 
• Generally, patient-reported outcomes and observer-reported outcomes cannot be 
administered over the telephone unless they are used in your study as “Clinician 
Read”. 
• There may be situations in which study partners or raters are remote. In these cases, 
the following guidance should be followed: 
− If the study partner/caregiver is remote and the participant is on site, scales can be 
administered per procedure, with study partner/caregiver providing answers to the 
site rater. 
− If the primary rater is remote, and the participant and back-up rater are on site, 
scales can still be administered by the primary rater. The back-up rater can be 
used to provide observational information to the primary rater, provided that they 
are trained on the scale. Refer to additional guidance under CDR®, ADCS-ADL-
MCI, and C-SSRS sections. 
Please note that some scales requiring participant performance, like drawing or writing, are not 
validated for remote administration and may not be administered via telephone 
(ie, ADAS-Cog13, MMSE, and RBANS-Update). 

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14.4.5. 
On-Site Assessments Unable to be Completed at Scheduled Visits 
In the event that a scheduled assessment is unable to be completed at site, eg, limited 
availability/restriction of equipment (eg, MRI), participant limited time on site, or because a 
remote visit was completed, the following assessments may be completed at the next scheduled 
on-site visit: 
• Clinical laboratory assessments, including urinalysis 
• ECGs 
• COAs not approved for remote administration 
• MRI 
• PET imaging 
• Biofluid collection for biomarker (CSF or blood). In the case of LPs for CSF 
collection, a normal coagulation result must be available prior to taking the lumbar 
puncture 
The approval of the Medical Monitor must be obtained prior to completion of these moved 
assessments. 
14.4.6. 
COVID-19 Reporting 
In the event where a study participant is diagnosed with COVID-19 infection, the local health 
authority recommendations regarding treatment should be followed and the event should be 
reported as an AE/SAE depending on the severity of infection and diagnosis. Refer to Section 7 
of the protocol. 
14.4.7. 
Remote Consent 
Sponsor will provide a simple downloadable consent that will enable qualified site staff to 
consent a participant to complete televisits. Where it is allowed by country/site regulations, a 
remote eConsent will be provided that allows a participant to be remote from the site and 
participate in the consent process. 
14.4.8. 
Remote Source Document Verification 
Remote source document verification will be employed only in the following circumstance: 
• National law, Regulatory Authorities, and IRB/IEC permit this process and approval 
is obtained. 
• On-site clinical research associate (CRA) visits are not permitted due to continued 
COVID-19 restrictions. 
• There is a need to complete source document verification for the following reasons: 
− Study data assessment review of critical study milestones (eg, database lock). 
− Participant safety. 

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− A significant backlog of data monitoring that could impact data integrity or 
participant safety. 
Prior to commencing remote source document verification, the following documentation must be 
completed: 
• The site CRA will complete a confidentiality agreement committing to securely 
destroy any copies of documents received from sites (paper or electronic), nor take 
any recording during video access. 
• Remote source data verification will only be completed for participants who have 
consented to allow access to their health records remotely. 
14.4.9. 
Home Visits 
Study drug must be administered at an investigational site. Study drug administration at a 
participant’s home is not permitted. 
To allow for collection of safety and protocol assessment data, a home health service may be 
employed. A home visit for the purposes of this appendix is a visit to a participant’s home or an 
alternative convenient location such as an alternate site. These home visits are separate from the 
remote assessments defined above and may be conducted by trained staff of the employed home 
health service. 
In event of home visits being employed, appropriate regulatory and ethics approval will be 
obtained prior to implementation as applicable per local regulations. 

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14.5. 
Appendix 5: Country-Specific Requirements 
14.5.1. 
Germany-Specific Protocol Differences 
This Germany-specific protocol difference was approved by the Paul Ehrlich Institute as 
Protocol Addendum #1 (Germany) to AL002-LTE Version 1.0 on 25 April 2023: 
Section 4.1 Inclusion Criteria 
Inclusion criterion #2 is updated as follows (strikethrough text is removed): 
“2. 
The participant is willing and able to give informed consent. Where local regulations 
permit inclusion of participants deemed not able to provide informed consent, a legally 
authorized representative must provide informed consent on his or her behalf, and the participant 
must provide assent, in accordance with the local regulations, guidelines, and institutional review 
board or independent ethics committee.” 

Document Approvals
Approval Task
Verdict:  Approve
Jingjing Gao
(jingjing.gao@alector.com)
SME Approval
12-Jan-2024 16:27:52 GMT+0000
Approval Task
Verdict:  Approve
Gary Romano,
(gary.romano@alector.com)
Management Approval
16-Jan-2024 16:57:29 GMT+0000
Number: GCP-01527            Status: Approved
AL002-LTE Protocol 2.0               1  of  110