Avidity Biosciences : June 2024 Corporate Presentation

Delivering on the RNA Revolution

June 2024

NASDAQ: RNA | aviditybio.com

Forward-Looking Statements

We caution the reader that this presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements other than statements of historical fact contained in this presentation are forward-looking statements. Forward-looking statements include, but are not limited to, statements regarding: our future results of operations and financial position; our business strategy; the anticipated timing, costs, design, goals and conduct of our ongoing and planned preclinical studies and clinical trials; the timing of release of data from our ongoing clinical programs and the announcement of new programs; the timing of additional cohorts to existing clinical trials; the characterization of data and results from preclinical studies and clinical trials, and conclusions drawn therefrom; research and development plans; plans and projected timelines for delpacibart etedesiran (del-desiran, formerly AOC 1001), delpacibart braxlosiran (del-brax, formerly AOC 1020) and AOC 1044; safety and tolerability profiles of our product candidates; functional and efficacy data demonstrated by our product candidates; the potential of the AOC platform and specific product candidates; the ability of our product candidates to treat rare diseases; timing and likelihood of success; product approvals; plans and objectives of management for future operations; collaborations with third parties and expected benefits therefrom; the partial clinical hold related to del-desiran; and cash position and our ability to fund our planned operations. In some cases, the reader can identify forward- looking statements by terms such as "may," "will," "should," "expect," "plan," "anticipate," "could," "intend," "target," "project," "contemplates," "believes," "estimates," "predicts," "potential" or "continue" or the negative of these terms or other similar expressions. The inclusion of forward-looking statements should not be regarded as a representation by Avidity that any of our plans will be achieved. Actual results may differ from those set forth in this presentation due to the risks and uncertainties inherent in our business based on factors beyond our control, including, without limitation: we may not be able to fully resolve the partial clinical hold related to del-desiran; additional requests for data by the FDA or other regulatory authorities may result in significant additional expense and timing delays; data delivered to the FDA may not be satisfactory to the FDA; additional participant data related to our product candidates that continues to become available may be inconsistent with the data produced as of the most recent respective date cutoffs, and further analysis of existing data and analysis of new data may lead to conclusions different from those established as of such date cutoffs; unexpected adverse side effects or inadequate efficacy of our product candidates may delay or limit their development, regulatory approval and/or commercialization, or may result in additional clinical holds, recalls or product liability claims; we are early in our development efforts; our planned additional cohorts in the FORTITUDE trial may not support the registration of del-brax; our approach to the discovery and development of product candidates based on our AOC platform is unproven, and we do not know whether we will be able to develop any products of commercial value; the results of preclinical studies and early clinical trials are not necessarily predictive of future results; potential delays in the commencement, enrollment and completion of clinical trials, or of designations conferred by regulatory authorities; our dependence on third parties in connection with preclinical and clinical testing and product manufacturing; we may not realize the expected benefits of our collaborations with third parties, our existing collaborations may terminate earlier than expected or we may not be able to form new collaborations; regulatory developments in the United States and foreign countries, including acceptance of INDs and similar foreign regulatory submissions and our proposed design of future clinical trials; Fast Track or Breakthrough Designation by the FDA may not lead to a faster development or regulatory review or approval process; our ability to obtain and maintain intellectual property protection for our product candidates and proprietary technologies; we may exhaust our capital resources sooner than we expect and fail to raise additional needed funds; and other risks described under the heading "Risk Factors" in our Form 10-K for the year ended December 31, 2023, filed with the SEC on February 28, 2024, and in subsequent filings with the SEC. The reader is cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and the reader is cautioned not to give undue weight to such estimates. In addition, projections, assumptions, and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty and risk. These and other factors could cause results to differ materially from those expressed in the estimates made by the independent parties and by us. This presentation shall not constitute an offer to sell or the solicitation of an offer to buy securities, nor shall there be any sale of securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

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OUR VISION

To profoundly improve

people's lives by revolutionizing the delivery of RNA therapeutics

Luke	3
Living with DM1

Building a New Class of RNA Therapeutics

Well positioned for next phase of growth

BROAD & DISRUPTIVE

P L A T F O R M

WORLD CLASS TEAM OF RNA & RARE DISEASE

E X P E R T S

S T R O N G F I N A N C I A L S

& INVESTOR CONFIDENCE

• AOC platform led to historical first-ever successful delivery of RNA to muscle with del-desiran; repeated with del-brax and AOC 1044 in healthy volunteers
• Expanding our therapeutic expertise, particularly in precision cardiology, through research collaborations and internal discovery efforts
• Committed to innovative science matched by passion to improve people's lives
• Building an integrated and diverse company in service of our patients
• Solid cash position of ~$1.3 billion provides funding into mid 2027*
• Advancing our three clinical development programs for del-desiran,del-brax and AOC 1044 into pivotal studies and further expanding our AOC platform, including precision cardiology programs

* Includes receipt of $433M net proceeds raised in upsized public offering which closed on June 17, 2024	4

Delivering in 2024: 3 Data Readouts in 3 Clinical Programs in 3 Rare Diseases

Del-desiranin DM1	Del-braxin FSHD	AOC 1044 in DMD44
>40,000 patients in U.S.	~16,000-38,000 patients in U.S.	~900 patients in U.S.

MARINA-OLE data (Q1 2024)

Initiation of global Phase 3 HARBOR trial (Q2 2024)

Phase 1/2 FORTITUDE initial data (Q2 2024)

Initiate Phase 3 cohorts

• Biomarker cohort (2H 2024)

• Functional cohort (1H 2025)

Phase 1/2 EXPLORE44 5mg/kg patient data (Anticipated in Q3 2024)

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Revolutionizing New Class of Targeted RNA Therapeutics

AOC platform delivers reproducible, consistent data across muscle disease programs

Rare Muscle Disease Therapies	Clinical Program	Safety &	Delivery to	Target	Functional
		Tolerability	Muscle	Engagement	Improvement
Del-desiran
Myotonic Dystrophy Type 1 (DM1)
Del-brax
Facioscapulohumeral Muscular
Dystrophy (FSHD)
AOC 1044
Duchenne Muscular Dystrophy (DMD44)
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Delivering on the RNA Revolution

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Key to Our Success: Proprietary AOC

Combining the specificity
of mAbs with the precision
of oligonucleotide therapies	mAb

Platform

mAb

OLIGO

OLIGO

MONOCLONAL	OLIGONUCLEOTIDE	ANTIBODY OLIGONUCLEOTIDE
ANTIBODIES	THERAPIES	CONJUGATE (AOC)

AOC platform advantages:

• Ability to target new tissue and cell types beyond the liver
• Flexibility to select and deploy the most potent oligonucleotides (e.g., siRNAs, PMOs)
• Maximizes therapeutic durability, enabling infrequent dosing
• Readily reproducible and scalable

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The Optimal AOC for Each Target

AOC COMPONENTS		DATA-DRIVEN COMPONENT		OUR ENGINEERING IMPACT
	CHARACTERISTICS
mAb	•	Well-established safety profile	•	Designed to be effector function null
•	High specificity and affinity	•	Epitope selection designed for optimal
	•	Long half-life		activity
		Known linker	•	Enhanced for durability
Linker	•	•	Engineered sites of conjugation
•	Applicable to multiple oligo modalities	•	Optimized ratio of oligonucleotides
				to mAbs
siRNA	•	Attractive safety profiles	•	Engineered to withstand lysosomal
•	Potency in the nanomolar range		enzymes
	•	Sustained activity in the cytoplasm and	•	Selected and modified to diminish off-
Oligonucleotide		nucleus		target effects
PMO	•	Attractive safety profile	•	Engineered for efficient delivery to
•	Potency in the nanomolar range		muscle - increased drug to antibody
	•	Sustained activity		ratio

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Avidity Is Opening the Possibilities of RNA Delivery

First-ever company to demonstrate successful targeted delivery of RNA to muscle

Past 30 Years	2021	Today	2024 and Beyond
First AOC Dosed in Humans

RNA Therapeutics		Skeletal	Immunology
		Muscle
	mAb	OLIGO
Focused		Precision	Other
	Cardiology	Indications
on delivery to the		AOC
liver or local delivery

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