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United States securities and exchange commission logo
January 9, 2024
Amit Etkin
Chief Executive Officer
Alto Neuroscience, Inc.
369 South San Antonio Road
Los Altos, CA 94022
Re:Alto Neuroscience, Inc.
Amendment No. 1 to Draft Registration Statement on Form S-1
Submitted December 28, 2023
CIK No. 0001999480
Dear Amit Etkin:
            We have reviewed your amended draft registration statement and have the following
comments.
            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 a comment applies 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 this letter and your amended
draft registration statement or filed registration statement, we may have additional comments.
Amendment No. 1 to Draft Registration Statement on Form S-1
Prospectus Summary
Overview, page 1
1.We note your response to prior comment 3, which we reissue in part.
•Please describe, where appropriate, each of the discussions you have had with the
FDA regarding your novel approach to the discovery and development of your
product candidates using your Platform, as well as any material outcomes of such
discussions.
•Explain whether you are basing your current expectation that you may be required to
develop and obtain FDA approval of a companion diagnostic for any of your product
candidates upon your prior discussions with the FDA.  Also, please describe when
you expect to know more definitively the FDA's views on this subject and how such
views may affect your plans.

 FirstName LastNameAmit  Etkin
 Comapany NameAlto Neuroscience, Inc.
 January 9, 2024 Page 2
 FirstName LastNameAmit  Etkin
Alto Neuroscience, Inc.
January 9, 2024
Page 2
2.We note your revisions in response to prior comment 5, which we reissue. Please further
revise the disclosure on pages 1, 103, and 123 to include the information contained in your
response to prior comment 5 in your letter dated December 28, 2023 concerning your goal
to ultimately provide treatments, if approved, that are tailored to specific patient
populations and explain how this might allow you to avoid the current lengthy paradigm
of treating psychiatric patients.
Our Pipeline, page 3
3.We note your revisions in response to prior comment 7, which we reissue in part.  Please
revise your disclosure on pages 4, 104, and 125 to clarify whether or not the Company's
representatives have had any interaction to date with the FDA regarding its willingness to
accept foreign clinical trial data underpinning the recently submitted IND covering
ALTO-203 in MDD. Also, please revise the Prospectus Summary to disclose the risk that
the FDA or comparable regulators may not accept earlier clinical data generated abroad,
in which case you may need to conduct additional clinical trials, as referenced in your risk
factor on page 31.
4.We note your revisions in response to prior comment 13, which we reissue in part. Please
further revise your discussion of the clinical development of your ALTO-202 program
here and in the Business section where appropriate to disclose the following information
with respect to any material clinical trials that third parties conducted:
•the trial design;
•the number of participants in the trial;
•the primary and secondary endpoints as well as the results as they relate to those
endpoints; and
•the occurrence of any serious adverse events.

Additionally, please include a description of any material development activities you have
conducted to date since licensing ALTO-202, relevant clinical work conducted or in
process, and the remaining steps to develop and commercialize the product and disclose
when you plan to initiate a Phase 2 trial for ALTO-202 and expect to report data from that
trial.
Risk Factor Summary, page 8
5.Consistent with your disclosure on page 162 and elsewhere, please revise your summary
risk and risk factor disclosure where appropriate to highlight that issued patents covering
the composition of ALTO-202 are due to retire in 2024 (compound) and 2035
(polymorph) and patents covering the composition of ALTO-203 in 2027.
Business
ALTO-101 Biological Rationale, page 151
6.We note your response stating that you have revised disclosure on page 152 to ensure that
the graphics included are legible. However, we observe that the revisions are not sufficient

 FirstName LastNameAmit  Etkin
 Comapany NameAlto Neuroscience, Inc.
 January 9, 2024 Page 3
 FirstName LastName
Amit  Etkin
Alto Neuroscience, Inc.
January 9, 2024
Page 3
to render your disclosures easily readable without magnification, as certain text remains
too small to be clear.  Please further review and revise as appropriate.
            Please contact Li Xiao at 202-551-4391 or Mary Mast at 202-551-3613 if you have
questions regarding comments on the financial statements and related matters. Please contact
Lauren Hamill at 303-844-1008 or Tim Buchmiller at 202-551-3635 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Divakar Gupta