ADAR1 Capital Management, LLC → Keros Therapeutics, Inc. KROS

Item 4 of the Initial Schedule 13D is hereby amended and supplemented by the addition of the following: On April 24, 2025, counsel to ADAR1 Capital Management, LLC sent a letter (the "Letter") to the Board outlining concerns that the Board has taken actions in breach of its fiduciary duties and demanding that that the Board take immediate action to waive or amend the deadline for the Issuer's stockholders to nominate candidates for election to the Board at the annual meeting of the Issuer's stockholders (the "Annual Meeting") scheduled to take place on June 4, 2025. The foregoing description of the Letter does not purport to be complete and is qualified in its entirety by reference to the full text of the Letter, which is attached hereto as Exhibit C and is incorporated herein by reference. The Reporting Persons intend to have discussions with the Board and management of the Issuer regarding corporate governance, including the composition of the Board, and may seek representation on the Board. The Reporting Persons may communicate with other shareholders and/or third parties regarding the Issuer and any or all of the foregoing, and may conduct a solicitation of proxies in connection with any matters to be considered at the Annual Meeting.