Korro Reports Full Year 2023 Financial Results and Highlights Recent Progress On track for regulatory filing for First-in-Human study of KRRO-110 in Alpha-1 Antitrypsin Deficiency (AATD) patients anticipated in the secon

Korro Reports Full Year 2023 Financial Results and Highlights Recent Progress

CAMBRIDGE, Mass., March 26, 2024 Korro Bio, Inc. (Korro) (Nasdaq: KRRO),

a biopharmaceutical company focused on developing a new class of genetic medicines for both rare and highly prevalent diseases, today reported financial results for the full year ended December 31, 2023, and reiterated its recent progress and

anticipated milestones.

Last year was a remarkable year for us as we achieved multiple major milestones, including selecting KRRO-110 as a development candidate, a potentially best-in-class therapeutic for AATD, becoming a public company, and closing

$117 million in financing, said Dr. Ram Aiyar, CEO and President of Korro. 2024 is off to a strong start and is poised to be a transformative year for us. We expect multiple milestones throughout the year, including a

regulatory submission for KRRO-110 in the second half of 2024, further progression of our pipeline programs, and expansion of platform innovation. Our dedication to providing potential disease-modifying

therapies for patients in need, coupled with our conviction in the pivotal role of RNA editing in the development of these therapeutic options, uniquely positions us to make a meaningful impact on patients lives.

Pipeline and Business Updates:

Upcoming Milestones:

Full Year 2023 Financial Results:

Cash Position: Cash, cash equivalents and short-term investments were $166.1 million as of December 31, 2023, compared to $55.2 million

as of December 31, 2022. Korro expects that its cash, cash equivalents and short-term investments to fund operations into 2026.

Development (R&D) Expenses: R&D expenses were $57.2 million for the year ended December 31, 2023, as compared to $42.2 million for the year ended December 31, 2022. The increase in R&D expenses was driven

primarily by preclinical activities for the KRRO-110 AATD program and expenses related to the advancement of its pipeline and platform.

General and Administration (G&A) Expenses: G&A expenses were $27.3 million for the year ended December 31, 2023, as compared to

$16.8 million for the year ended December 31, 2022. The increase is driven primarily by merger-related personnel costs, as well as additional personnel and facility costs to support growing R&D function.

Net Loss: Korro s net loss was $81.2 million for the year ended December 31, 2023, as compared to $58.0 million for the year ended

Korro is a biopharmaceutical company focused on developing a new class of genetic medicines for both rare and highly prevalent diseases using its proprietary

RNA editing platform. Korro is generating a portfolio of differentiated programs that are designed to harness the body s natural RNA editing process to effect a precise yet transient single base edit. By editing RNA instead of DNA, Korro is

expanding the reach of genetic medicines by delivering additional precision and tunability, which has the potential for increased specificity and improved long-term tolerability. Using an oligonucleotide-based approach, Korro expects to bring its

medicines to patients by leveraging its proprietary platform with precedented delivery modalities, manufacturing know-how, and established regulatory pathways of approved oligonucleotide drugs. Korro is based

in Cambridge, Mass. For more information, visit korrobio.com.

Forward-Looking Statements

Certain statements in this press release may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform

Act of 1995, as amended. Forward-looking statements include, but are not limited to, express or implied statements regarding expectations, hopes, beliefs, intentions or strategies of Korro regarding the future including, without limitation, express

or implied statements regarding: Korro s planned regulatory filing for KRRO-110 in AATD and any interim data readout; Korro s cash runway; Korro s ability to advance its pipeline and the role of

RNA editing technology in developing therapeutic options; KRRO-110 s potential as a best-in-class drug candidate for AATD;

and the benefits of OPERA; among others. In addition, any statements that refer to projections, forecasts, or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words

anticipate, believe, continue, could, estimate, expect, intend, may, might, plan, possible, potential,

predict, project, should, strive, would, aim, target, commit, and similar expressions may identify forward-looking statements, but the absence of these

words does not mean that statement is not forward looking. Forward-looking statements are based on current expectations and assumptions that, while considered reasonable are inherently uncertain. New risks and uncertainties may emerge from time to

time, and it is not possible to predict all risks and uncertainties. Factors that may cause actual results to differ materially from current expectations include, but are not limited to, various factors beyond management s control including

risks inherent in biopharmaceutical development; risks associated with pre-clinical studies and clinical trials; and other risks associated with obtaining regulatory approvals and protecting intellectual

property; as well as risks associated with general economic conditions; the inability to recognize the anticipated benefits of the recently completed merger, which may be affected by, among other things, competition, Korro s ability to grow and

manage growth profitably, maintain relationships with customers and suppliers and retain key employees; costs related to merger; the possibility that Korro may be adversely affected by other economic, business, and/or competitive factors; other

risks and uncertainties indicated from time to time in Korro s filings with the SEC, including Item 1A. Risk Factors in Korro s Annual Report on Form 10-K filed with the SEC on the date

hereof, as such may be amended or supplemented by its other filings with the SEC. Nothing in this press release should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of

the contemplated results of such forward-looking statements will be achieved. You should not place undue reliance on forward-looking statements in this press release, which speak only as of the date they are made and are qualified in their entirety

by reference to the cautionary statements herein. Except as required by

law, Korro does not undertake or accept any duty to release publicly any updates or revisions to any forward-looking statements to reflect any change in their expectations or in the events,

conditions or circumstances on which any such statement is based. This press release does not purport to summarize all of the conditions, risks and other attributes of an investment in Korro.

Korro Contact Information

Condensed Consolidated Statements of Operations

(in thousands, except share and per share amounts)

Condensed Consolidated Balance Sheet Data