Crossing the Blood-Brain Barrier: Developing Alector’s Next Generation of Investigational Therapies for Neurodegeneration

Crossing the Blood-Brain Barrier:

Developing Alector's Next Generation of Investigational Therapies for Neurodegeneration

Disclaimer and Forward-Looking Statements

This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements other than statements of historical facts contained in this presentation are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potentially," "predict," "should," "will" or the negative of these terms or other similar expressions. Forward-looking statements contained in this presentation also include, but are not limited to, statements regarding the beneficial characteristics, safety, efficacy, and therapeutic effects of our product candidates, including our blood-brain barrier technology platform, Alector Brain Carrier ("ABC"); our plans, timelines and expectations related to our product candidates, including our ABC technology platform, and our other clinical and pre-clinical programs, including with respect to the availability of data, the initiation of future clinical trials and plans and expectations regarding planned regulatory filings with respect to such programs; and objectives of management for future operations, as well as statements regarding industry trends.

We, Alector, Inc. ("Alector"), have based these forward-looking statements largely on our current expectations and projections about future events and trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including, among other things: Alector's plans relating to its research programs and the development and manufacturing of its product candidates; the ability of Alector's clinical trials to demonstrate safety and efficacy of its product candidates, and other positive results; the timing and focus of Alector's clinical trials, and the reporting of data from those trials; Alector's plans relating to commercializing its product candidates, if approved, including the geographic areas of focus and sales strategy; the expected potential benefits of strategic collaborations with third parties and Alector's ability to attract collaborators with development, regulatory and commercialization expertise; Alector's estimates of the number of patients in the United States, the European Union and world-wide who suffer from the diseases it is targeting and the number of patients that will enroll in its clinical trials; the size of the market opportunity for Alector's product candidates in each of the diseases it is targeting; Alector's ability to expand its product candidates into additional indications and patient populations; the success of competing therapies that are or may become available; the beneficial characteristics, safety, efficacy, and therapeutic effects of Alector's product candidates; the timing or likelihood of regulatory filings and approvals, including Alector's expectation to seek special designations, such as orphan drug designation, for its product candidates for various diseases; Alector's ability to obtain and maintain regulatory approval of its product candidates; Alector's plans relating to the further development and manufacturing of its product candidates, including additional indications that it may pursue; existing and future regulations and regulatory developments in the United States and other jurisdictions; Alector's reliance on third parties to conduct clinical trials of its product candidates, and for the manufacture of its product candidates for preclinical studies and clinical trials; the impact of worldwide economic conditions, including macroeconomic downturns stemming from increased inflation, supply chain and other economic impacts of pandemics or other public health outbreaks and geopolitical events on our business; and the other risks, uncertainties and assumptions discussed in the public filings we have made and will make with the Securities and Exchange Commission ("SEC"). These risks are not exhaustive. New risk factors emerge from time to time, and it is not possible for our management to predict all risk factors, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in, or implied by, any forward-looking statements. You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee future results, levels of activity, performance or achievements.

This presentation also contains results based on data from our clinical trials. These clinical trials are ongoing and this presentation does not speak to, and you should make no assumptions about, any additional data. In addition, the information we have chosen to publicly disclose regarding our product candidates has been selected from a more extensive amount of available information. You or others may not agree with what we determine is the material or otherwise appropriate information to include in our disclosure, and any information we determine not to disclose may ultimately be deemed significant with respect to future decisions, conclusions, views, activities or otherwise. If the initial data that we report differ from updated, late, final or actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize our product candidates may be harmed, which could harm our business, financial condition, results of operations and prospects.

This presentation discusses certain investigational therapeutic agents which have not yet been approved for marketing by the U.S. Food and Drug Administration. No representation is made as to the safety or effectiveness of our product candidate for the therapeutic use for which it is being studied.

This presentation contains statistical data based on independent industry publications or other publicly available information, as well as other information based on our internal sources. We have not independently verified the accuracy or completeness of the data contained in these industry publications and other publicly available information. Accordingly, we make no representations as to the accuracy or completeness of that data.

Except as required by law, we undertake no obligation to update any statements in this presentation for any reason after the date of this presentation. We have filed Current Reports on Form 8-K, Quarterly Reports on Form 10-Q,

Annual Reports on Form 10-K, and other documents with the SEC. You should read these documents for more complete information about us. You may obtain these documents for free by visiting EDGAR on the SEC website at www.sec.gov.

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Today's Agenda

01	Alector's Leadership in Neurodegeneration
Arnon Rosenthal, Ph.D., Chief Executive Officer, and
	Peter Heutink, Ph.D., Chief Scientific Officer, Alector
	The State of Drug Delivery Across the BBB
02	Zhiqiang An, Ph.D., Professor & Robert A. Welch
Distinguished University Chair in Chemistry and Director of
	the Texas Therapeutics Institute at UTHealth Houston
	Alector Brain Carrier: Our Proprietary BBB Approach
03
Eric Brown, Ph.D., Lead Scientist, ABC Platform, Alector
	Alector Brain Carrier: Potential Applications
04
Maxime Ah Young-Chapon, Ph.D., Lead Scientist,
GCase Program, Alector
	Closing Remarks and Q&A
05
Peter Heutink, Ph.D., Chief Scientific Officer, Alector

12:00-12:15 pm

12:15-12:35 pm

12:35-12:55 pm

12:55-1:15 pm

1:15-1:30 pm

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Alector's Leadership in

Neurodegeneration

Ar	non Ro	senthal	, Ph.D.	Peter Heutink, Ph.D.
	Chief Executive Officer	Chief Scientific Officer
	Alector	Alector

Enhanced Long-Term Future with Alector Brain Carrier (ABC) Platform

2024

2025

2026

2027

Anticipated

Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

Clinical

AL002 AD Phase 2

Latozinemab FTD-GRN

AL101 AD Phase 2

Readouts

Phase 3

Expanding our ability to deliver first and best-in-class therapies for degenerative brain disorders

	Novel Targets
	Brain Penetrant Proteins, Enzymes
	& Antibodies
ABC:	Validated targets	- Years in the making
- Enables targeting diseases that require protein replacement
An Integral
Best-in-ClassBrain-Penetrant
- Enables lower dosing, better brain distribution & subQ delivery
Part of	Proteins, Enzymes & Antibodies
- Enables development of 2nd gen. drugs for clinical programs
Alector Drug	2nd Gen Targets
- Enables development of best-in-class drugs for validated targets
Discovery
Brain-Penetrant Proteins, Enzymes	- Enables brain delivery of non-protein drug modalities
Platform
& Antibodies

Non-Protein drugs

Best-in-Class Brain Penetrant

Expanded Partnering Opportunities

Partnerships

Proteins

Enzymes

Antibodies

Nucleic Acids

Partnering Opportunities with Drug Modalities Experts

Alector: Pioneering the Potential of Immuno-neurology to Address Neurodegeneration

Pioneering science grounded in human genetics, immunology and neurobiology

Ongoing Phase 2 studies in AD (TREM2 & PGRN) and pivotal Phase 3 study in FTD (PGRN)

Diverse and differentiated research portfolio integrating the company's proprietary Alector Brain Carrier (ABC) technology platform

Image Credit: decade3d - anatomy /Shutterstock.com

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Alector Brain Carrier (ABC): Enhanced Delivery of Biologics Across the BBB

Another tool that supports next-generation and novel immuno-neurology programs

BBB

Maintains homeostasis

and protects by restricting access

Challenge

• BBB poses a challenge for how much drug gets into the brain

Potential Solution

• ABC is our proprietary technology designed to enhance brain penetration of therapeutic molecules

https://www.netterimages.com/the-blood-brain-barrier-labeled-hansen-physiology-1e-physiology-james-a-perkins-4921.html

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Alector Brain Carrier (ABC) Technology Platform Complements Late-Stage Portfolio

		Exploring the potential to develop next-
		GCase + ABC: PD
	generation, brain-penetrant product candidates
		PGRN: FTD-GRN		GCase + ABC: LBD
PROGRAMS
	TREM2: AD		GPNMB + ABC: PD
		PGRN: AD			UD TARGETS + ABC: AD, PD, ALS
		CLINICAL			PRECLINICAL
MODALITIES	NAKED ANTIBODIES	ANTIBODIES+ABC	PROTEINS+ABC	ENZYMES+ABC
THERAPEUTIC AREA			NEURODEGENERATION
STRATEGY	IMMUNO-NEUROLOGY: HUMAN GENETICS + IMMUNOLOGY + NEUROSCIENCE

UD = undisclosed

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Portfolio: Advancing Novel First-in-Class Programs with Major Rights Retained

							ALECTOR'S
TARGET	CANDIDATE	RESEARCH	PRECLINICAL	PHASE 1	PHASE 2	PHASE 3	COMMERCIAL	RIGHTS
							OWNERSHIP
	Latozinemab	FTD-GRN					U.S. 50-50 profit
					share with
PGRN							co-promote and
	AL101	AD					tiered double-digit
					royalties ex-U.S.
TREM2	AL002	AD					Global 50-50 profit
				share with opt-in

GPNMB ADP027-ABC	PD
GCase	ADP050-ABC	PD, LBD
UD	ADP052-ABC	AD, PD
UD	ADP054-ABC	ALS, AD, PD
UD	ADP056-ABC	AD

IP portfolio across all programs contains 60+ patent families, which include 100 issued patents and >500 pending patent applications directed to more than 20 targets and/or technologies

100%

100%

100%

100%

100%

ABC = Alector Brain Carrier

UD = undisclosed

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The State of

Drug Delivery

Across the BBB

Zhiqiang An, Ph.D.

Professor & Robert A. Welch Distinguished University Chair in Chemistry and

Director of the Texas Therapeutics Institute at UTHealth Houston

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