Keros Therapeutics, Inc.

To the shareholders and the Board of Directors of Keros Therapeutics, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Keros Therapeutics, Inc. and subsidiaries (the "Company") as of December 31, 2025 and 2024, the related consolidated statements of operations, stockholders' equity, and cash flows, for each of the years then ended, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for the years then ended, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Revenue Recognition — Takeda License Agreement – Refer to Notes 2 and 15 to the financial statements

Critical Audit Matter Description

The Company recognizes revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). As described in Note 15 to the financial statements, the Company entered into a license agreement with Takeda (the “Takeda Agreement”), which became effective January 16, 2025, and concurrently entered into a separate transition services agreement with Takeda (the “TSA”), pursuant to which the Company will provide certain transitional services to Takeda, including, but not limited to, clinical trial and manufacturing services, during the term of the TSA (the "Transition Services"). Pursuant to the terms of the Takeda Agreement, the Company received a $200.0 million upfront payment in February 2025, which was included in the transaction price at inception. The transaction price also included estimated variable consideration of $51.4 million relating to Transition Services.

The Company evaluated the Takeda Agreement and the TSA as a single contract under ASC 606 and identified two performance obligations, which included the license to the Company’s intellectual property (“License and Know-How”) and the Transition Services. The Company determined that the License and Know-How were distinct from the Transition Services. The Company allocated $195.4 million of the upfront payment to the License and Know-How, which was recognized as revenue at a point in time when control of the License and Know-How was transferred to Takeda. The remaining transaction price was allocated to the Transition Services, which was recognized over time as services were provided. As of December 31, 2025, the Company recognized $38.5 million of service revenue for the Transition Services and such services are substantially complete.

We identified the revenue recognition for the Takeda Agreement and the TSA as a critical audit matter. Auditing the Company’s application of the relevant accounting guidance required significant auditor judgment, including the need to involve an internal subject matter expert.

Our audit procedures related to the Company’s revenue recognition for the Takeda Agreement and the TSA included the following, among others:

•Agreed the $200 million upfront payment to cash received and verified cash receipt for all payments received by the Company from Takeda for Transition Services performed during the year.

•Obtained and read the Company’s accounting position paper assessing the accounting treatment for the Takeda Agreement and the TSA pursuant to ASC 606.

•Utilized the assistance of our professionals with specialized knowledge and skills in the relevant technical accounting guidance, to evaluate (1) the Company’s determination of performance obligations, (2) the timing of revenue recognition for the License and Know-How and (3) the determination of the transaction price.

/s/Deloitte & Touche LLP

Boston, MA

March 4, 2026

We have served as the Company's auditor since 2019.