Avidity Biosciences : October 2022 Corporate Presentation

Delivering on the RNA Revolution

October 2022

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 facts contained in this presentation, including, but not limited to, statements regarding our future results of operations and financial position, business strategy, the anticipated timing, costs, design and conduct of our ongoing and planned preclinical studies and clinical trials, research and development plans, plans and projected timelines for AOC 1001, AOC 1020 and AOC 1044; timing and likelihood of success, prospective products, product approvals, plans and objectives of management for future operations, and future results of anticipated product development efforts, are forward-looking statements. 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, including, without limitation: we are early in our development efforts and many of our development programs are in the preclinical or discovery stage; 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 success of our preclinical studies and clinical trials for our product candidates; 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; our dependence on third parties in connection with preclinical and clinical testing and product manufacturing; disruption to our operations from the COVID-19 pandemic; the war in Ukraine; unexpected adverse side effects or inadequate efficacy of our product candidates that may limit their development, regulatory approval and/or commercialization, or may result in recalls or product liability claims; 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; our ability to obtain and maintain intellectual property protection for our product candidates and proprietary technologies; we may use our capital resources sooner than we expect; and other risks described in our filings with the SEC, including under the heading "Risk Factors" in our Form 10-K for the year ending on December 31, 2021, filed with the SEC on March 1, 2022, and any 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, and 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.

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Our Vision

Luke

Living with DM1

To profoundly improve people's lives by revolutionizing the

delivery of RNA therapeutics

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Delivering on Our Vision

DISRUPTIVE & BROAD

PLATFORM

• Committed to delivering a new class of RNA therapies
• Advancing three AOCs into clinical development; two siRNAs and first PMO
• Broadening to other tissues & cell types through partnerships & internal discovery

ADVANCING & EXPANDING

PIPELINE

• Progressing robust pipeline in muscle; 3 programs in clinical development in approx. a year
• AOC 1001* Phase 1/2 MARINATM trial and MARINA- OLETM ongoing
• AOC 1020 for FSHD advancing into Phase 1/2 FORTITUDETM clinical trials
• AOC 1044 for DMD advancing into clinical trials

AGILE & DIVERSE

COMPANY

• Leveraging expertise in clinical and commercial execution
• Assembling an experienced team in rare & RNA therapies
• Building an integrated and diverse company in service of our patients

*Sept. 2022, FDA placed a partial clinical hold on new participant enrollment. All current participants may continue in their current
dosing cohort. All participants in MARINA may roll over into the MARINA-OLE where they will receive AOC 1001 as planned. Avidity is	4
working closely with the FDA and the trial investigator to resolve the partial clinical hold as quickly as possible.

Delivering on 2022 Goals

Three programs in three distinct rare diseases in clinical development

DM1:

AOC 1001*

MARINATM

On track for preliminary assessment in Q4 2022

Initiated MARINA-OLE in August 2022

FSHD:	DMD:
AOC 1020	AOC 1044
FORTITUDETM	Phase 1/2
IND cleared; trial	IND cleared; trial
initiation underway	initiation underway
Preliminary assessment	First AOC with a
in approximately half of	PMO
participants in 1H 2024

*Sept. 2022, FDA placed a partial clinical hold on new participant enrollment. All current participants may continue in their current
dosing cohort. All participants in MARINA may roll over into the MARINA-OLE where they will receive AOC 1001 as planned. Avidity is	5
working closely with the FDA and the trial investigator to resolve the partial clinical hold as quickly as possible.