Company: KROS
Filing Date: 2025-05-19
Form Type: DEFA14A
Source: 0001104659-25-050243
Chunk: 1

Company: Keros Therapeutics, Inc.
Filing Date: 2025-05-19
Form: DEFA14A
Chunk 1
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 LLC and Daniel Schneeberger (collectively, “ADAR1”) publicly announced their intention to withhold votes with respect to the re-election of two of the Board’s nominees, Mary Ann Gray, Ph.D., and Alpna Seth, Ph.D., to the Board at the Annual Meeting.

The purpose of this Supplement is to provide updated
information relating to the election of directors at the Annual Meeting in light of ADAR1’s recent actions. Except as supplemented
by the information contained in this Supplement, this Supplement does not revise or update any of the information set forth in the Proxy
Statement. This Supplement should be read in conjunction with the Proxy Statement. From and after the date of this Supplement, any references
to the “Proxy Statement” are to the Proxy Statement as supplemented hereby.

OUR BOARD UNANIMOUSLY RECOMMENDS A VOTE “FOR” EACH OF THE BOARD’S THREE CLASS II DIRECTOR NOMINEES.

The Proxy Statement includes detailed information
about the matters that will be discussed and voted on at the Annual Meeting that you should consider to make an informed decision when
voting your shares.

We strongly urge you to vote for all three of the Board’s highly qualified and experienced Class II director nominees, Mary Ann Gray, Ph.D., Ran Nussbaum and Alpna Seth, Ph.D. Please vote “FOR” for each of the Board’s three director nominees (Proposal 1); “FOR” for the ratification of Deloitte & Touche LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025 (Proposal 2) and (3) “FOR” for the advisory approval of our named executive officer compensation (Proposal 3). Your vote is extremely important, no matter how many shares you own.

Even if you plan to attend the Annual Meeting,
we urge you to vote your shares as promptly as possible to ensure your representation and the presence of a quorum at the Annual Meeting.

If you have any questions or require any assistance
with voting your shares, please contact Alliance Advisors, our proxy solicitor assisting us in connection with the Annual Meeting:

<div align='center'>Alliance Advisors, LLC

150 Clove Road; Suite 400

Little Falls, NJ 07424

1-844-202-6582</div>

In addition,subsequent to the filing of the Proxy Statement, we have engaged MacKenzie Partners to assist us with our stockholder
engagement process for this Annual Meeting. We may