SecProbe.io

February 13, 2020
Jasbir Seehra, Ph.D.
Chief Executive Officer
Keros Therapeutics, Inc.
99 Hayden Avenue, Suite 120, Building E
Lexington, MA 02421
Re:Keros Therapeutics, Inc.
Draft Registration Statement on Form S-1
Submitted January 21, 2020
CIK No. 0001664710
Dear Dr. Seehra:
            We have reviewed your draft registration statement and have the following comments.  In
some of our comments, we may ask you to provide us with information so we may better
understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Draft Registration Statement Submitted on January 21, 2020
Our Biological Focus, page 2
1.Please provide context for the strategic goals in the bulleted discussion on page 2 to
explain how each of the goals relates to the current offer.  If the goals will not be
addressed with the proceeds of the offer, please disclose that these goals will not be
achievable without additional funding.
Our Pipeline, page 3
2.We note the inclusion of ActRII and "Multiple ActRII variants" in the table on page 3.
Please expand the table and your disclosure to provide more information about the
company's progress with respect to pre-clinical trials for these applications.  If you have

 FirstName LastNameJasbir Seehra, Ph.D.
 Comapany NameKeros Therapeutics, Inc.
 February 13, 2020 Page 2
 FirstName LastNameJasbir Seehra, Ph.D.
Keros Therapeutics, Inc.
February 13, 2020
Page 2
undertaken IND enabling studies for any of the treatments listed in the table, please
describe these studies in the disclosure.  Alternatively, please state in the disclosure
surrounding the table where you are in the IND process.
3.Please balance the pipeline table disclosure by stating the approximate number of patients
worldwide who could benefit from each of the therapies in the table or otherwise clarify
your estimate of the potential market size for each therapy. In this regard, we note your
statements (e.g., page 1) that you are focusing on "novel treatments for patients suffering
from hematological and musculoskeletal disorders with high unmet medical need," as well
as your statements that the total worldwide number of FOP patients may be approximately
3,500.
4.Please add to the table a column for Phase 3.
Implications of Being an Emerging Growth Company, page 5
5.Please supplementally provide us with copies of all written communications, as defined in
Rule 405 under the Securities Act, that you, or anyone authorized to do so on your behalf,
present to potential investors in reliance on Section 5(d) of the Securities Act, whether or
not they retain copies of the communications.
Risk Factors, page 11
6.We note that there are references to foreign regulators and foreign markets throughout the
Risk Factors and other sections of your prospectus.  Please revise to explain what non-US
markets, if any, you plan to enter, and what steps you have taken to attain the necessary
regulatory and patent approvals.
7.We note references throughout the prospectus to risks and benefits associated with orphan
drug status.  Given the small number of patients who may benefit from certain of the
treatments you are developing, please provide more information concerning whether the
company currently intends to seek orphan drug status for any of its product candidates.
8.We note your disclosure in the Risk Factors and throughout the prospectus regarding the
company's having conducted its phase 1 clinical trials in Australia, through its Australian
subsidiary, together with the information that foreign trials may not be acceptable to the
FDA.  Please revise throughout the prospectus to include information about how you will
replicate the trials in the US, if necessary to gain FDA approval, and how you will pay for
the additional trials.
9.We note your disclosure on page 60 and on page 150 that your exclusive forum provision
does not apply to actions arising under the Securities Act or the Exchange Act. Please
ensure that the exclusive forum provision in the bylaws (as effective on the closing of the
offering) states this clearly, or tell us how you will inform investors in future filings that
the provision does not apply to any actions arising under the Securities Act or Exchange
Act.

 FirstName LastNameJasbir Seehra, Ph.D.
 Comapany NameKeros Therapeutics, Inc.
 February 13, 2020 Page 3
 FirstName LastName
Jasbir Seehra, Ph.D.
Keros Therapeutics, Inc.
February 13, 2020
Page 3
Management's Discussion and Analysis of Financial Condition and Results of Operations
Determination of the Fair Value of Common Stock , page 83
10.Once you have an estimated offering price or range, please explain to us the reasons for
any significant differences between the recent valuations of your common stock leading
up to your initial public offering and the estimated offering price.  Please also explain
reasons for significant differences between prices at which you sold preferred stock and
valuations of common shares. This information will help facilitate our review of your
accounting for equity issuances.
Consolidated Financial Statements
Note 2. Research and Development Costs , page F-10
11.For all periods presented, please disclose the amount of income earned and costs incurred
related to research and development activities of the Novo Nordisk license agreement.
Refer to ASC 730-20-50-1.
General
12.Please provide us mockups of any pages that include any additional pictures or graphics to
be presented, including any accompanying captions. Please keep in mind, in scheduling
your printing and distribution of the preliminary prospectus, that we may have comments
after our review of these materials.
            You may contact Christie Wong at 202-551-3684 or Brian Cascio at 202-551-3676 if you
have questions regarding comments on the financial statements and related matters.  Please
contact Julia Griffith at 202-551-3267 or Dietrich King at 202-551-8071 with any other
questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences