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 CORRESP

 January 29, 2026
 VIA EDGAR AND EMAIL United States Securities and
Exchange Commission Division of Corporation Finance 100 F
Street, N.E. Washington, DC 20549 Attn: Tim Buchmiller

 Re:
 Dianthus Therapeutics, Inc.
 Registration Statement on Form S-3
 Filed January 28, 2026
 File No. 333-293014 Ladies and
Gentlemen: Pursuant to Rules 460 and 461 promulgated under the Securities Act of 1933, as amended (the “Act”), Dianthus
Therapeutics, Inc., a Delaware corporation (the “Company”), hereby respectfully requests that the effective time of the above referenced Registration Statement on Form S-3 filed by the Company be
accelerated to 4:00 p.m., Eastern Standard Time, on January 30, 2026 or as soon thereafter as practicable, unless we or our outside counsel, Gibson, Dunn & Crutcher LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its obligations under the Act.
 Once the Registration Statement is effective, please orally confirm the event with our counsel, Gibson, Dunn & Crutcher LLP by
calling Melanie Neary at (415) 393-8243.

 Very truly yours,

 Dianthus Therapeutics, Inc.

 By:

 /s/ Ryan Savitz

 Name:

 Ryan Savitz

 Title:

 Chief Financial Officer and Chief Business Officer

 cc:

 Marino Garcia, Dianthus Therapeutics, Inc. Adam
Veness, Dianthus Therapeutics, Inc. Ryan A. Murr, Gibson, Dunn & Crutcher LLP
 Branden C. Berns, Gibson, Dunn & Crutcher LLP

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 January 29, 2026

Marino Garcia
Chief Executive Officer
Dianthus Therapeutics, Inc.
7 Times Square, 43rd Floor
New York, NY 10036

 Re: Dianthus Therapeutics, Inc.
 Registration Statement on Form S-3
 Filed January 28, 2026
 File No. 333-293014
Dear Marino Garcia:

 This is to advise you that we have not reviewed and will not review your
registration
statement.

 Please refer to Rules 460 and 461 regarding requests for acceleration.
We remind you
that the company and its management are responsible for the accuracy and
adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action
by the staff.

 Please contact Tim Buchmiller at 202-551-3635 with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: Melanie E. Neary, Esq.
</TEXT>
</DOCUMENT>

October 7, 2024
Adam Veness
General Counsel
Dianthus Therapeutics, Inc.
7 Times Square, 43rd Floor
New York, NY 10036
Re:Dianthus Therapeutics, Inc.
Registration Statement on Form S-3
File No. 333-282446
Filed October 1, 2024
Dear Adam Veness:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration. We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Tamika Sheppard at 202-551-8346 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:Branden Burns

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 October 7, 2024

VIA EDGAR AND EMAIL

 United States Securities and
Exchange Commission

 Division of Corporation Finance

 100 F
Street, N.E.

 Washington, DC 20549

 Attn: Tamika Sheppard

Re:
 Dianthus Therapeutics, Inc.

Registration Statement on Form S-3

Filed October 1, 2024

File No. 333-282446

 Ladies and
Gentlemen:

 Pursuant to Rules 460 and 461 promulgated under the Securities Act of 1933, as amended (the “Act”), Dianthus
Therapeutics, Inc., a Delaware corporation (the “Company”), hereby respectfully requests that the effective time of the above referenced Registration Statement on Form S-3 filed by the Company be
accelerated to 4:15 p.m., Eastern Standard Time, on October 9, 2024 or as soon thereafter as practicable, unless we or our outside counsel, Gibson, Dunn & Crutcher LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its obligations under the Act.

Once the Registration Statement is effective, please orally confirm the event with our counsel, Gibson, Dunn & Crutcher LLP by
calling Branden Berns at (415) 393-4631.

Very truly yours,

Dianthus Therapeutics, Inc.

By:

/s/ Ryan Savitz

Name:

Ryan Savitz

Title:

Chief Financial Officer and Chief Business Officer

cc:
 Marino Garcia, Dianthus Therapeutics, Inc.

Adam Veness, Dianthus Therapeutics, Inc.

Ryan A. Murr, Gibson, Dunn & Crutcher LLP

Branden C. Berns, Gibson, Dunn & Crutcher LLP

CORRESP
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 October 7, 2024

VIA EDGAR AND EMAIL

 United States Securities and
Exchange Commission

 Division of Corporation Finance

 100 F
Street, N.E.

 Washington, DC 20549

 Attn: Tamika Sheppard

Re:
 Dianthus Therapeutics, Inc.

Registration Statement on Form S-3

Filed October 1, 2024

File No. 333-282443

 Ladies and
Gentlemen:

 Pursuant to Rules 460 and 461 promulgated under the Securities Act of 1933, as amended (the “Act”), Dianthus
Therapeutics, Inc., a Delaware corporation (the “Company”), hereby respectfully requests that the effective time of the above referenced Registration Statement on Form S-3 filed by the Company be
accelerated to 4:15 p.m., Eastern Standard Time, on October 9, 2024 or as soon thereafter as practicable, unless we or our outside counsel, Gibson, Dunn & Crutcher LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its obligations under the Act.

Once the Registration Statement is effective, please orally confirm the event with our counsel, Gibson, Dunn & Crutcher LLP by
calling Branden Berns at (415) 393-4631.

Very truly yours,

Dianthus Therapeutics, Inc.

By:

/s/ Ryan Savitz

Name:

Ryan Savitz

Title:

Chief Financial Officer and Chief Business Officer

cc:
 Marino Garcia, Dianthus Therapeutics, Inc.

Adam Veness, Dianthus Therapeutics, Inc.

Ryan A. Murr, Gibson, Dunn & Crutcher LLP

Branden C. Berns, Gibson, Dunn & Crutcher LLP

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 March 25, 2024

VIA EDGAR AND EMAIL

 United States Securities and
Exchange Commission

 Division of Corporation Finance

 100 F
Street, N.E.

 Washington, DC 20549

 Attn: Dillon Hagius and
Laura Crotty

Re:
 Dianthus Therapeutics, Inc.

Registration Statement on Form S-1

Filed March 21, 2024

File No. 333-274863

 Ladies and
Gentlemen:

 Pursuant to Rules 460 and 461 promulgated under the Securities Act of 1933, as amended (the “Act”), Dianthus
Therapeutics, Inc., a Delaware corporation (the “Company”), hereby respectfully requests that the effective time of the above referenced Registration Statement on Form S-1 filed by the Company be
accelerated to 4:15 p.m., Eastern Standard Time, on March 27, 2024 or as soon thereafter as practicable, unless we or our outside counsel, Gibson, Dunn & Crutcher LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its obligations under the Act.

Once the Registration Statement is effective, please orally confirm the event with our counsel, Gibson, Dunn & Crutcher LLP by
calling Branden Berns at (415) 393-4631.

 Very truly yours,

 Dianthus Therapeutics, Inc.

By:

/s/ Ryan Savitz

Name:

Ryan Savitz

Title:

Chief Financial Officer and Chief Business Officer

cc:
 Marino Garcia, Dianthus Therapeutics, Inc.

Adam Veness, Dianthus Therapeutics, Inc.

Ryan A. Murr, Gibson, Dunn & Crutcher LLP

Branden C. Berns, Gibson, Dunn & Crutcher LLP

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 Gibson, Dunn & Crutcher LLP

One Embarcadero, Suite 2600

 San Francisco, CA 94111-3715

Tel 415.393.8200

 gibsondunn.com

 February 7, 2024  

EDGAR CORRESPONDENCE

 U.S. Securities and Exchange
Commission

 Division of Corporation Finance

 Office of Life
Sciences

 100 F Street, N.E.

 Washington, D.C. 20549

Attn: Dillon Hagius and Laura Crotty

Re:
 Dianthus Therapeutics, Inc.

Registration Statement on Form S-1

Filed on December 21, 2023

File No. 333-274863

Ladies and Gentlemen:

 On behalf of Dianthus
Therapeutics, Inc. (the “Company” or “Dianthus”), this letter responds to the comment of the staff of the Securities and Exchange Commission Division of Corporation Finance (the “Staff”) contained
in your letter, dated December 28, 2023 (the “Comment Letter”), regarding the above-referenced Registration Statement on Form S-1 (the “Registration Statement”), which
was originally filed on Form S-3 on October 4, 2023 (Registration No. 333-274863). The Staff’s comment is set forth below, followed by the Company’s
response. For ease of reference, the heading and numbered paragraphs below correspond to the heading and numbered comments in the Comment Letter. The Company’s response is set forth in ordinary type beneath the Staff comment, which is set out
in bold type. References are made to the Company’s Amendment No. 1 to the Registration Statement (“Amendment No. 1”).

Amendment No. 1 to Form S-3 on Form S-1

General

1.
 We note the representation in Section 3.4 of the Agreement and Plan of Merger that Dianthus’
security holders were required to consent to the merger. We further note that it appears the Form S-1 seeks to register the resale of securities issued and issuable to certain of such security holders as
consideration for the merger. Please revise to identify all former affiliates of Dianthus reselling pursuant to the Form S-1 as underwriters and fix a selling price for the duration of their offering. Refer to
Securities Act Rule 145(c).

 Abu Dhabi • Beijing
• Brussels • Century City • Dallas • Denver • Dubai • Frankfurt • Hong Kong • Houston • London • Los Angeles

Munich • New York • Orange County • Palo Alto • Paris • San Francisco • Singapore • Washington, D.C.

 U.S. Securities and Exchange Commission

February 7, 2024

 In response to the Staff’s comment, the Company has removed from Amendment No. 1 the shares of
Common Stock issued to affiliate stockholders of Former Dianthus at the time of the stockholder approval of the Merger, namely, Avidity Private Master Fund I LP, Avidity Master Fund LP, Avidity Capital Fund II LP, Fairmount SPV III, LLC, Fairmount
Healthcare Fund L.P., Fairmount Healthcare Fund II L.P. and Tellus BioVentures, LLC, which stockholders were the only affiliate stockholders of Former Dianthus at the time of the stockholder approval of the Merger that were listed as selling
stockholders in the Registration Statement; provided, that, Amendment No. 1 does contain shares of Common Stock and shares of Common Stock issuable upon the exercise of 2024 Pre-Funded Warrants purchased
by certain of such stockholders in the 2024 Private Placement.

 ***

Thank you for your consideration of this response. If you have any questions regarding the response set forth above, please do not hesitate to call me at
(415) 393-4631.

 Sincerely,

 /s/ Branden C. Berns

 Branden C. Berns

cc:
 Ryan A. Murr, Gibson, Dunn & Crutcher LLP

Melanie Neary, Gibson, Dunn & Crutcher LLP

Marino Garcia, Dianthus Therapeutics, Inc.

Ryan Savitz, Dianthus Therapeutics, Inc.

Adam Veness, Dianthus Therapeutics, Inc.

United States securities and exchange commission logo
December 28, 2023
Ryan Savitz
Chief Financial Officer
Dianthus Therapeutics, Inc.
7 Times Square
43rd Floor
New York, New York, 10036
Re:Dianthus Therapeutics, Inc.
Amendment No. 1 to Registration Statement on Form S-1
Filed December 21, 2023
File No. 333-274863
Dear Ryan Savitz:
            We have reviewed your amended registration statement and have the following comment.
            Please respond to this letter by amending your registration statement and providing the
requested information. 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 any amendment to your registration statement and the information you
provide in response to this letter, we may have additional comments.
Amendment No. 1 to Form S-3 on Form S-1
General
1.We note the representation in Section 3.4 of the Agreement and Plan of Merger that
Dianthus’ security holders were required to consent to the merger. We further note that it
appears the Form S-1 seeks to register the resale of securities issued and issuable to
certain of such security holders as consideration for the merger. Please revise to identify
all former affiliates of Dianthus reselling pursuant to the Form S-1 as underwriters and fix
a selling price for the duration of their offering. Refer to Securities Act Rule 145(c).

 FirstName LastNameRyan Savitz
 Comapany NameDianthus Therapeutics, Inc.
 December 28, 2023 Page 2
 FirstName LastName
Ryan Savitz
Dianthus Therapeutics, Inc.
December 28, 2023
Page 2
            Please contact Dillon Hagius at 202-551-7967 or Laura Crotty at 202-551-7614 with any
questions.

Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Branden C. Berns

United States securities and exchange commission logo
November 14, 2023
Ryan Savitz
Chief Financial Officer
Dianthus Therapeutics, Inc.
7 Times Square
43rd Floor
New York, New York, 10036
Re:Dianthus Therapeutics, Inc.
Registration Statement on Form S-3
Filed October 4, 2023
File No. 333-274863
Dear Ryan Savitz:
            We have conducted a limited review of your registration statement and have the
following comment.
            Please respond to this letter by amending your registration statement and providing the
requested information. 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 any amendment to your registration statement and the information you
provide in response to this letter, we may have additional comments.
Registration Statement on Form S-3
General
1.We note that on September 11, 2023, Dianthus completed its merger with Magenta
Therapeutics, Inc. and, as you disclose on page 4, the business now conducted by the
combined company is primarily the business conducted by Dianthus Therapeutics OpCo,
Inc. As part of the merger transaction, the company distributed to Magenta stockholders of
record a non-transferrable contingent value right relating to the disposition or
monetization of Magenta’s legacy business assets and separately terminated most of
Magenta’s legacy employees and executives. Given these circumstances, please tell us
your basis for registering this transaction on Form S-3. See Use of Form S-8, Form 8-K,
and Form 20-F by Shell Companies, Release No. 33-8587 (July 15, 2005) at n. 32 as
reiterated in Special Purpose Acquisition Companies, Shell Companies, and Projections,
Release No. 33-11048 (March 30, 2022) at n. 239 and accompanying text.

 FirstName LastNameRyan Savitz
 Comapany NameDianthus Therapeutics, Inc.
 November 14, 2023 Page 2
 FirstName LastName
Ryan Savitz
Dianthus Therapeutics, Inc.
November 14, 2023
Page 2
Alternatively, please amend your registration statement to register the offering on Form S-
1.
            We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
            Refer to Rules 460 and 461 regarding requests for acceleration. Please allow adequate
time for us to review any amendment prior to the requested effective date of the registration
statement.
            Please contact Dillon Hagius at 202-551-7967 or Laura Crotty at 202-551-7614 with any
other questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Branden C. Berns

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 Magenta Therapeutics, Inc.

300 Technology Square, 8th Floor

Cambridge, MA 02139

 July 31, 2023

VIA EDGAR

 Office of Life Sciences

Division of Corporation Finance

 U.S. Securities and Exchange Commission

100 F Street NE

 Washington, DC 20549

Attention:
 Ms. Doris Stacey Gama

Mr. Jason Drory

 Ms. Jenn Do

Mr. Kevin Vaughn

Re:
 Magenta Therapeutics, Inc.

Acceleration Request for Registration Statement on Form S-4

File No. 333-271917

Requested Date:

August 1, 2023

Requested Time:

4:15 p.m. Eastern Time

 Dear. Ms. Gama, Mr. Drory, Ms. Do and Mr. Vaughn:

Pursuant to Rule 461 under the Securities Act of 1933, as amended (the “Act”), Magenta Therapeutics, Inc. (the
“Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration Statement”) be accelerated to August 1, 2023, at 4:15 p.m., Eastern Time, or as soon
thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time. In making this acceleration request, the Company acknowledges that it
is aware of its responsibilities under the Act.

 Once the Registration Statement is effective, please orally confirm the event with our counsel,
Goodwin Procter LLP by calling Marianne Sarrazin at (415) 733-6134. We also respectfully request that a copy of the written order from the Securities and Exchange Commission verifying the effective time and
date of the Registration Statement be sent to our counsel, Goodwin Procter LLP, Attention: Marianne Sarrazin, by email to msarrazin@goodwinlaw.com or by facsimile to (415) 651-9491.

If you have any questions regarding this request, please contact Marianne Sarrazin of Goodwin Procter LLP at
(415) 733-6134.

Sincerely,

Magenta Therapeutics, Inc.

/s/ Stephen Mahoney

Stephen Mahoney

President, Chief Financial and Operating Officer

cc:
 Marianne Sarrazin, Goodwin Procter LLP

William D. Collins, Goodwin Procter LLP

 Michael
Patrone, Goodwin Procter LLP

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 Goodwin Procter LLP

 Three Embarcadero Center, 28th Floor

 San Francisco, CA 94111

goodwinlaw.com

 +1 (415)
733-6000

 July 17, 2023

 VIA EDGAR

Office of Life Sciences

 Division of Corporation Finance

U.S. Securities and Exchange Commission

 100 F Street NE

Washington, DC 20549

Attention:

Ms. Doris Stacey Gama

Mr. Jason Drory

Ms. Jenn Do

Mr. Kevin Vaughn

Re:
 Magenta Therapeutics, Inc.

Amendment No. 1 to

 Registration
Statement on Form S-4

 Filed June 22, 2023

File No. 333-271917

 Dear. Ms. Gama, Mr. Drory, Ms. Do
and Mr. Vaughn:

 This letter is submitted on behalf of Magenta Therapeutics, Inc. (“Magenta”) in response to the comments of the
staff of the Division of Corporation Finance (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with respect to Magenta’s Amendment No. 1 to Registration Statement on Form S-4 (File No: 333-271917), filed on June 22, 2023 (“Amendment No. 1”), as set forth in the Staff’s letter dated July 6, 2023
(the “Comment Letter”). Magenta is concurrently submitting Amendment No. 2 to the Registration Statement on Form S-4 (“Amendment No. 2”), which
includes changes to reflect responses to the Staff’s comments and other updates.

 For reference purposes, the text of the Comment Letter has
been reproduced herein with responses below each numbered comment. For your convenience, we have italicized the reproduced the Staff’s comments from the Comment Letter. Unless otherwise indicated, page references in the descriptions of the
Staff’s comments refer to Amendment No. 1, and page references in the responses refer to Amendment No. 2. All capitalized terms used and not otherwise defined herein shall have the meanings set forth in Amendment No. 2.

Amendment No. 1 to Registration Statement on Form S-4

Opinion of Houlihan Lokey to the Magenta Board Material Financial Analyses, page 162

1.
 We note your response to our prior comment 10 that Houlihan Lokey identified a sufficient number of companies but may
not have included all companies that might be deemed comparable to Dianthus. Please revise your disclosure to state how Houlihan Lokey identified which companies to include and which to exclude in its analysis.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on page 163 of Amendment No. 2 to reflect the Staff’s comment.

 U.S. Securities and Exchange Commission

July 17, 2023

  Page
 2

 Dianthus’ Business

Dianthus’ Pipeline of Next-Generation Complement Therapeutics, page 285

2.
 We note your response to our prior comment 17. Please revise your pipeline table so that all your text is legible. We
note the text appearing directly below the table is too small to be legible. Also, eliminate the shadow arrows, as they do not reflect the current status of your trials.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the pipeline table on page 285 of Amendment No. 2 to reflect the Staff’s
comment.

3.
 We note your response to our prior comment 18 and reissue in part. Your revised pipeline table contains a row
depicting “Ongoing Discovery Efforts to Identify Additional Active Selective Complement Targets” with no specific program or target identified. Given the early stage of development, it seems premature to highlight your ongoing discovery
efforts as a specific row in the pipeline table. Please remove this row from your pipeline table. You may disclose your ongoing discovery efforts elsewhere in your Business section.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the pipeline table on page 285 of Amendment No. 2 to reflect the Staff’s
comment.

 Unaudited Pro Forma Condensed Combined Financial Information, page 373

4.
 Please address the following regarding your response to comment 25 in our letter dated June 13,
2023:

•

 Tell us how you considered whether the merger should be recorded as an asset acquisition by Dianthus under ASC 805 given
the contingent cash flow streams resulting from the sales of certain assets, including intellectual property, related to its MGTA-117 antibody, MGTA-45 program and MGTA-145 program.

 RESPONSE: Magenta acknowledges the Staff’s comment and respectfully advises
the Staff that for purposes of pro forma presentation, in determining the appropriate accounting treatment under ASC 805 “Business Combinations” (“ASC 805”), Magenta concluded that at the effective date of the merger
substantially all of its assets are expected to consist of cash and cash equivalents, marketable securities and nominal non-operating assets. Because Magenta’s non-operating assets, other than cash and
cash equivalents and marketable securities, will have nominal value upon closing of the merger, Magenta expects to account for the asset acquisition as a reverse capitalization.

With respect to the contingent cash flow streams, which Magenta views as variable consideration, resulting from the April 2023 sales of certain assets, including
intellectual property, related to its MGTA-117 antibody, MGTA-45 program and MGTA-145 program, it is not probable that this
variable consideration will be received by Magenta as the achievement of these milestones is highly susceptible to factors outside Magenta’s influence that are not expected to be resolved for a long period of time, if at all. In particular,
this variable consideration is highly susceptible to the actions and judgments of third parties and the buyers and is based on the buyers progressing the in-process research and development assets into
clinical trials, and in the case of one of the agreements, to a regulatory milestone and as such, no receivables are recorded on the balance sheet relating to such contingent payments. The value of such contingent cash flow streams is therefore not
material to Magenta or the merger.

 U.S. Securities and Exchange Commission

July 17, 2023

  Page
 3

 Magenta also notes that at or prior to the effective time of the merger, Magenta and a rights agent will enter into a
Contingent Value Rights Agreement, or the CVR Agreement, pursuant to which Magenta’s stockholders of record as of immediately prior to the effective time of the merger will receive
one non-transferable CVR for each outstanding share of Magenta common stock held by such stockholder on such date. Pursuant to the CVR Agreement, each CVR holder will be entitled to rights to receive
a pro rata portion of certain proceeds, if any, received by Magenta after the effective time of the merger, which proceeds will include the contingent payments related to the April 2023 asset sales. As of the effective date of the Merger, Magenta
does not believe that it has a liability, as the contingent events obligating Magenta to pay Magenta’s stockholders of record are not probable of occurring. Magenta notes that if, following the merger, Magenta were to record a receivable once
the variable consideration is not constrained, for the contingent payments resulting from the April 2023 asset sales, it will also record a corresponding liability.

•

 Tell us how you evaluated the extent to which the accounting would be different if you accounted for the merger as an
asset purchase versus a reverse recapitalization, providing quantification where possible.

 RESPONSE: Magenta acknowledges the
Staff’s comment and respectfully advises the Staff that if the merger was accounted for as an asset purchase, it would be a reverse asset purchase, with Dianthus as the acquirer, issuing stock for the net assets acquired. The net assets
acquired would be recorded at relative fair value, determined in accordance with ASC 820 “Fair Value Measurement” (“ASC 820”). Goodwill is not recognized in an asset acquisition. Under the reverse recapitalization, the net assets
of Magenta would be recorded at relative fair value, determined in accordance with ASC 820 with goodwill and intangible assets not recognized. Because as of the effective date of the merger, Magenta expects no intangible assets to be owned, no
intangible assets would be recognized. Because substantially all of Magenta’s net assets are expected to consist of cash and cash equivalents and marketable securities with the remaining non-operating
assets at the effective date of the merger having nominal value and therefore relative fair value approximates historical cost as such, there would not be a material difference under the reverse recapitalization accounting versus the accounting for
a reverse asset acquisition.

•

 As part of your response and with a view to revised disclosure, clearly detail how you determined that the intangible
assets for the contingent significant future cash flows resulting from the sales of certain assets, including intellectual property, related to its MGTA-117 antibody,
MGTA-45 program and MGTA-145 program meet the definition of “nominal other assets” in section 1160.2 of the Financial Reporting Manual available on our
website. In your response, specifically address your evaluation of these assets in isolation of the Contingent Value Right (CVR) agreement rather than net of the CVR.

RESPONSE: Magenta acknowledges the Staff’s comment and respectfully advises the Staff that Magenta expects there to be no intangible assets related to MGTA-145 or MGTA-45 program candidates, or the MGTA-117 antibodies as of the effective date of the merger, all such assets having been
sold to third parties. In addition, any sales of other assets with no carrying amounts, completed to date or that are completed prior to the closing of the merger, if any, would be of only nominal value and result in nominal cash, given the early
development stage of such assets. Magenta views the contingent payments related to the April 2023 asset sales to be variable consideration that is fully constrained as of the effective date of the merger.

In response to the Staff’s comment, Magenta has revised the disclosure on page 373 of Amendment No. 2 to clarify this point.

•

 Tell us and revise to reconcile the apparent inconsistency in your conclusion to treat the merger as a reverse
recapitalization for accounting purposes with the contractual provision on page A-41 that “Magenta has not been and is not currently determined to be a “shell company” as defined under
Section 12b-2 of the Exchange Act.”

 U.S. Securities and Exchange Commission

July 17, 2023

  Page
 4

 RESPONSE: Magenta respectfully advises the Staff that Magenta does not meet the SEC’s definition of a shell
company because it had significant pre-combination assets and/or activities, including multiple development programs, a robust patent estate and a research and development team, prior to its decision to seek
strategic alternatives following its decision to voluntarily pause the development of its lead program, MGTA-117.

 As noted
above in the response to the first bullet of this comment 4, in determining the appropriate accounting treatment under ASC 805, Magenta concluded that at the effective date of the merger substantially all of Magenta’s assets are expected to
consist of cash and cash equivalents, marketable securities with the remaining assets comprised of other nominal non-operating assets. Because Magenta’s assets, other than cash and cash equivalents and
marketable securities, will have nominal value upon closing of the merger, Magenta expects to account for the asset acquisition as a reverse recapitalization.

 The
above treatment is consistent with the views provided in Section 9.015 of KPMG’s Business Combinations Handbook, February 2023, which states (emphasis added): “Even if a public company does not meet the SEC’s
definition of a shell company, the public company may have little to no assets (other than cash or cash equivalents) or activities by the time the reverse acquisition is consummated. If the public company’s assets or activities just prior
to the reverse acquisition meet the definition of a business, and the private company is the acquirer for accounting purposes, the transaction constitutes a business combination. However, if the assets and activities of the public company are not
sufficient to meet the definition of a business, and the private company is the acquirer for accounting purposes, the accounting acquirer would account for this transaction as the acquisition of a group of assets.”

5.
 Please address the following regarding your response to comment 26 of our letter dated June 13,
2023:

•

 Revise your pro forma presentation to give separate pro forma effect to the April asset sales and CVR liability
transactions pursuant to Article 11-1(a)(8) of Regulation S-X. The transactions have occurred and it appears given the nature of the transactions the disclosure would be
material to investors.

 RESPONSE: In response to the Staff’s comment, Magenta respectfully advises the Staff that it has revised
the unaudited pro forma condensed combined financial information in Amendment No. 2 to reflect receipt of the upfront consideration of the April 2023 asset sales.

In addition, Magenta respectfully advises the Staff that the CVR Agreement has not yet occurred. However, at or prior to the effective time of the merger the CVR
Agreement will be executed and therefore, in response to the Staff’s comment, Magenta has revised the disclosure on pages 375 and 381 of Amendment No. 2 to further clarify this point.

Potential future contingent payments to Magenta of up to $20.0 million under the April 2023 asset sales agreements were not recorded in the unaudited pro forma
condensed combined financial information as an asset because Magenta has determined that the achievement of the contingent milestone events are fully constrained pursuant to ASC 606 “Revenue from Contracts with Customers” (“ASC
606”). Magenta respectfully advises the Staff that the corresponding CVR liabilities under the CVR Agreement that will be entered into, were also not recorded, as such liabilities will only be recognized if and when achievement of the milestone
events, as defined in the CVR Agreement, becomes probable in accordance with ASC 450 “Contingencies” (“ASC 450”). In response to the Staff’s comment, Magenta has revised the disclosure on pages 375 and 381 of Amendment
No. 2 to allow an investor to understand the terms of the contingent milestones to Magenta and corresponding CVR liabilities, and the basis for not including pro forma effects for such items.

 U.S. Securities and Exchange Commission

July 17, 2023

  Page
 5

•

 To the extent you believe the asset sales are not material to Magenta, provide us with your evaluation of the sale
transactions in isolation of the CVR agreements, including quantification of the amounts involved.

 RESPONSE: Magenta respectfully
advises the Staff that revisions were made as indicated in the response to the first bullet of this comment 4.

•

 Tell us in detail and revise to clearly describe how Magenta accounted for and valued each of the individual
transactions from the April asset sales and CVR liability for accounting purposes in their historical financial statements.

 RESPONSE:
In response to the Staff’s comment, Magenta assessed the accounting for each of the individual April 2023 asset sales under the guidance contained in ASC 610-20 “Other Income – Gains and Losses
from the Derecognition of Nonfinancial Assets” (“ASC 610-20”), and ASC 606, as each of the asset sales represents a single identifiable asset that does not meet the definition of a business,
individually or collectively. Magenta concluded that the purchasers of the individual April 2023 asset sales are not customers as that term is defined in ASC 606, and therefore accounted for the sales under ASC
610-20. Each of the individual April 2023 sales transactions for certain of Magenta’s in-process research and development assets, which are non-financial assets, included an upfront payment and a contingent payment upon the achievement of either a clinical or regulatory mil

United States securities and exchange commission logo
July 6, 2023
Stephen Mahoney
President, Chief Financial and Operating Officer
Magenta Therapeutics, Inc.
300 Technology Square, 8th Floor
Cambridge, MA 02139
Re:Magenta Therapeutics, Inc.
Amendment No. 1 to Registration Statement on Form S-4
Filed June 22, 2023
File No. 333-271917
Dear Stephen Mahoney:
            We have reviewed your amended 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 amending your registration statement and providing the
requested information.  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 any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.  Unless we note
otherwise, our references to prior comments are to comments in our June 13, 2023 letter.
Amendment No. 1 to Registration Statement on Form S-4
Opinion of Houlihan Lokey to the Magenta Board
Material Financial Analyses, page 162
1.We note your response to our prior comment 10 that Houlihan Lokey identified a
sufficient number of companies but may not have included all companies that might be
deemed comparable to Dianthus. Please revise your disclosure to state how Houlihan
Lokey identified which companies to include and which to exclude in its analysis.

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 July 6, 2023 Page 2
 FirstName LastName
Stephen Mahoney
Magenta Therapeutics, Inc.
July 6, 2023
Page 2
Dianthus' Business
Dianthus' Pipeline of Next-Generation Complement Therapeutics, page 285
2.We note your response to our prior comment 17. Please revise your pipeline table so that
all your text is legible. We note the text appearing directly below the table is too small to
be legible. Also, eliminate the shadow arrows, as they do not reflect the current status of
your trials.
3.We note your response to our prior comment 18 and reissue in part. Your revised pipeline
table contains a row depicting "Ongoing Discovery Efforts to Identify Additional Active
Selective Complement Targets" with no specific program or target identified. Given the
early stage of development, it seems premature to highlight your ongoing discovery
efforts as a specific row in the pipeline table. Please remove this row from your pipeline
table. You may disclose your ongoing discovery efforts elsewhere in your Business
section.
Unaudited Pro Forma Condensed Combined Financial Information, page 373
4.Please address the following regarding your response to comment 25 in our letter dated
June 13, 2023:
•Tell us how you considered whether the merger should be recorded as an asset
acquisition by Dianthus under ASC 805 given the contingent cash flow streams
resulting from the sales of certain assets, including intellectual property, related to
its MGTA-117 antibody, MGTA-45 program and MGTA-145 program.
•Tell us how you evaluated the extent to which the accounting would be different if
you accounted for the merger as an asset purchase versus a reverse recapitalization,
providing quantification where possible.
•As part of your response and with a view to revised disclosure, clearly detail how you
determined that the intangible assets for the contingent significant future cash flows
resulting from the sales of certain assets, including intellectual property, related to
its MGTA-117 antibody, MGTA-45 program and MGTA-145 program meet the
definition of "nominal other assets" in section 1160.2 of the Financial Reporting
Manual available on our website. In your response, specifically address your
evaluation of these assets in isolation of the Contingent Value Right (CVR)
agreement rather than net of the CVR.
•Tell us and revise to reconcile the apparent inconsistency in your conclusion to treat
the merger as a reverse recapitalization for accounting purposes with the contractual
provision on page A-41 that "Magenta has not been and is not currently determined to
be a “shell company” as defined under Section 12b-2 of the Exchange Act."
5.Please address the following regarding your response to comment 26 of our letter dated
June 13, 2023:
•Revise your pro forma presentation to give separate pro forma effect to the April
asset sales and CVR liability transactions pursuant to Article 11-1(a)(8) of Regulation

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 July 6, 2023 Page 3
 FirstName LastName
Stephen Mahoney
Magenta Therapeutics, Inc.
July 6, 2023
Page 3
S-X.  The transactions have occurred and it appears given the nature of the
transactions the disclosure would be material to investors.
•To the extent you believe the asset sales are not material to Magenta, provide us with
your evaluation of the sale transactions in isolation of the CVR agreements, including
quantification of the amounts involved.
•Tell us in detail and revise to clearly describe how Magenta accounted for and valued
each of the individual transactions from the April asset sales and CVR liability for
accounting purposes in their historical financial statements.
•We note your statement on page 380 that "As any amounts related to the asset
purchase agreements and CVRs are expected to be either not material and/or not
probable to be recognized, the agreements were not deemed to be significant and it
was determined not to give an effect to these agreements in the unaudited pro forma
condensed combined financial information."  To the extent you determine the initial
recognition of one or all of these individual transactions will be de minimis because
the probability of the receipt (or payment) of the contingent future contractual cash
flows is so low as of the date of the transaction together with the cash paid at the time
of the sale, clearly disclose that fact, and provide accompanying disclosure of the
potential maximum future cash flows along with your assertion as to the probability
of receipt (or payment). Clearly identify that your evaluation of the materiality of the
asset sales is in isolation from the CVR agreements.
            You may contact Jenn Do at 202-551-3743 or Kevin Vaughn at 202-551-3494 if you
have questions regarding comments on the financial statements and related matters.  Please
contact Doris Stacey Gama at 202-551-3188 or Jason Drory at 202-551-8342 with any other
questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Marianne Sarrazin, Esq.

CORRESP
1
filename1.htm

CORRESP

 Goodwin Procter LLP

 Three Embarcadero Center,
28th Floor

 San Francisco, CA 94111

 goodwinlaw.com

+1 (415) 733-6000

 June 22, 2023

 VIA
EDGAR

 Office of Life Sciences

 Division of
Corporation Finance

 U.S. Securities and Exchange Commission

100 F Street NE

 Washington, DC 20549

Attention:

Ms. Doris Stacey Gama

Mr. Jason Drory

Ms. Jenn Do

Mr. Kevin Vaughn

 Re:         Magenta Therapeutics, Inc.

               Registration Statement on Form
S-4

                Filed
May 15, 2023

                File No. 333-271917

Dear. Ms. Gama, Mr. Drory, Ms. Do and Mr. Vaughn:

This letter is submitted on behalf of Magenta Therapeutics, Inc. (“Magenta”) in response to the comments of the staff of the
Division of Corporation Finance (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with respect to Magenta’s Registration Statement on Form
S-4 (File No: 333-271917), initially filed on May 15, 2023 (the “Registration Statement”), as set forth in the Staff’s letter dated
June 13, 2023 (the “Comment Letter”). Magenta is concurrently submitting Amendment No. 1 to the Registration Statement (“Amendment No. 1”), which includes changes to reflect responses to
the Staff’s comments and other updates.

 For reference purposes, the text of the Comment Letter has been reproduced herein with
responses below each numbered comment. For your convenience, we have italicized the reproduced Staff comments from the Comment Letter. Unless otherwise indicated, page references in the descriptions of the Staff’s comments refer to the
Registration Statement, and page references in the responses refer to Amendment No. 1. All capitalized terms used and not otherwise defined herein shall have the meanings set forth in Amendment No. 1.

Registration Statement on Form S-4

Questions and Answers About the Merger

 Q: What are
contingent value rights (“CVR”)?, page 4

1.
 We note your disclosure that, “[i]n April 2023, Magenta sold certain assets, including intellectual
property, related to its product candidates MGTA-45, MGTA-145 and the CD117 antibodies including the clinical antibody that was used with
MGTA-117, and is continuing to explore strategic alternatives related to its other assets.” Please specify the programs or pre-merger assets held by Magenta the are
covered by the CVR Agreement. We note from your disclosure on pages 253 and 254 that the April 2023 asset sales included certain up-front cash payments as well as future potential milestone payments.
Please clarify whether or not any of the April 2023 asset sales by Magenta, including future milestone payments, are covered by the CVR Agreement.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on pages 4, 23,
258-259, 374, 380 of Amendment No. 1 to reflect the Staff’s comment.

 U.S. Securities and Exchange Commission

June 22, 2023

  Page
 2

2.
 Please revise your disclosure to clarify the material terms of the CVR Agreement, your intentions with
Magenta’s pre-merger assets and describe any material assets that either have been sold or may be sold by Magenta pursuant to the CVR Agreement or otherwise advise.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on pages 4, 11, 23, 37, 206, 374 and 380 of Amendment No. 1
to reflect the Staff’s comment.

 The Companies Magenta, page 10

3.
 You state here and on page 252 that in April 2023, Magenta sold certain assets, related to Magenta’s
prior product candidates. However, you also state that Magenta is continuing to explore strategic alternatives related to its “other assets.” Given your recent sales in April 2023, please revise your disclosure to clarify what you mean
when you state “other assets” to specifically describe any material assets or otherwise advise.

 RESPONSE: Magenta
acknowledges the Staff’s comment and has revised the disclosure on pages 11 and 256 of Amendment No. 1 to reflect the Staff’s comment. Magenta supplementally advises the Staff that the “other assets” include intellectual
property related to its legacy business that are not currently in development and that Magenta does not consider to be material.

 Prospectus Summary,
page 12

4.
 Please balance your discussion here, and on page 145, to disclose the negative factors or potential risks
associated with your merger agreement that were considered by the boards of directors of Magenta and Dianthus, respectively, when each voted to approve the merger agreement.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on pages 13-16 and 152
of Amendment No. 1 to reflect the Staff’s comment.

 Risk Factors

Risks Related to the Merger

 Some Magenta and Dianthus
directors and executive officers have interests in the merger..., page 28

5.
 We note your disclosure that “certain of Dianthus’ directors are affiliated with investment funds
which hold an interest in Dianthus and are participating in the Dianthus pre- closing financing.” Please update your disclosure here to identify the directors and the fund(s) they are affiliated with that are participating in the pre-closing financing.

 RESPONSE: Magenta acknowledges the Staff’s comment and has
revised the disclosure on page 30 of Amendment No. 1 to reflect the Staff’s comment.

 The Merger

Background of the Merger, page 133

6.
 Please revise your disclosure to identify the individuals who negotiated the material terms of the merger.
For example only, we note your disclosure that “Magenta’s management,” “participants” and certain “financial advisors” were part of the negotiations related to the merger.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on pages 134, and
142-148 of Amendment No. 1 to reflect the Staff’s comment.

 U.S. Securities and Exchange Commission

June 22, 2023

  Page
 3

7.
 We note your disclosure on page 136 discussing certain “Criteria” that would be used to evaluate
any potential indications of interest. Please revise to more specifically describe the criteria proposed to assess potential counterparties. For example, if you were looking for parties with a product candidate that had achieved a specific stage of
development, what stage was that? What were you looking for with respect to the attractiveness of the counterparty’s technology and development pipeline? Additionally, please discuss whether the criteria and/or the prioritization of the
criteria changed over time.

 RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on pages 138-139 of Amendment No. 1 to reflect the Staff’s comment. Magenta advises the Staff that it has further revised the defined term “Criteria” on
pages 138-139 and 141 of Amendment No. 1 (which was previously included on page 136 of the Registration Statement) to add more specificity in response to the Staff’s comment. Magenta further
advises the Staff (and as disclosed on page 139 of Amendment No. 1), Magenta applied the Criteria to potential counterparties on a holistic basis in considering their relative potential strengths and weaknesses and did not change (nor
reprioritize) the Criteria over time.

8.
 On page 140 you state that on March 21, 2023 representatives of Wedbush communicated to
representatives of Dianthus Magenta’s willingness to agree to a traditional reverse merger in exchange for an increase in the valuation attributed to Magenta. Please include a description of Dianthus’ response to such communication.

 RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on page 143 of Amendment No. 1 in
response to the Staff’s comment.

9.
 We note your disclosure that “after reviewing all of the submitted indications of interest, the
participants selected 12 indications of interest to prioritize and invite to make management and due diligence presentations.” However, your disclosure appears to only disclose Parties A through D. Please update your disclosure to describe the
seven other parties that were invited to make presentations. In addition, update your existing disclosure where you describe Parties A through D to provide additional details about each party, including a description of the general industry of the
company.

 RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on pages 139-140 of Amendment No. 1 to reflect the Staff’s comment.

 Opinion of Houlihan Lokey to the Magenta Board,
page 154

10.
 Revise to provide additional information regarding how Houlihan Lokey selected the comparable companies and
whether it excluded any comparable companies that fit those criteria.

 RESPONSE: Magenta acknowledges the Staff’s
comment and has revised the disclosure on page 162 of Amendment No. 1 in response to the Staff’s comment. Magenta further advises the Staff that, as noted in the revised disclosure, Houlihan Lokey may not have included all companies that
might be deemed comparable to Dianthus, but Magenta supplementally advises the Staff that Houlihan Lokey did not exclude any companies that it otherwise deemed relevant.

 U.S. Securities and Exchange Commission

June 22, 2023

  Page
 4

11.
 Please explain the statement “Houlihan Lokey selected an implied enterprise value reference range for
Dianthus of $150.0 million to $200.0 million, which resulted in an aggregate implied equity value reference range for Dianthus of $274.2 million to $324.2 million, and an implied per share
reference range for Dianthus of $4.75 to $5.62.” Please clarify how Houlihan Lokey arrived at the $150.0 million to $200.0 million range. For example, did Houlihan Lokey use the mean, median, high or low value from the calculations of
the comparable companies? Please explain what other considerations Houlihan Lokey deemed relevant and how they impacted Houlihan Lokey’s analysis.

RESPONSE: Magenta acknowledges the Staff’s comment and has revised the disclosure on page 163 of Amendment No. 1 in response to the
Staff’s comment.

12.
 We note your disclosure that “[t]he Magenta Liquidation Analysis and Houlihan Lokey’s selected
companies analysis for Dianthus indicated an implied exchange ratio reference range of 4.42844313 to 5.33756289 shares of Magenta common stock for each share of Dianthus capital stock, as compared to the exchange ratio in the merger pursuant to the
Merger Agreement of 3.88182949 shares of Magenta common stock for each share of Dianthus capital stock.” Please revise to describe the conclusions Houlihan Lokey reached with respect to the implied exchange ratio as a result of such
comparisons.

 RESPONSE: Magenta acknowledges the Staff’s comment and advises the Staff that, as described on page 163 of
Amendment No. 1, “Houlihan Lokey arrived at its opinion based on the results of all analyses undertaken by it and assessed as a whole and did not draw, in isolation, conclusions from or with regard to any individual analysis, methodology
or factor. While the results of each analysis were taken into account in reaching Houlihan Lokey’s overall conclusion with respect to fairness, Houlihan Lokey did not make separate or quantifiable judgments regarding individual analyses.”
Magenta also supplementally advises the Staff that, because Houlihan Lokey’s opinion addressed the fairness, from a financial point of view, to Magenta of the exchange ratio provided for in the merger, the fact that the implied exchange ratio
reference range indicated by Houlihan Lokey’s financial analyses was above the exchange ratio provided for in the Merger supported Houlihan Lokey’s opinion.

The Merger Agreement, page 177 Potential

 Asset Sale,
page 183

13.
 You state hereunder that in April 2023, Magenta entered into asset purchase agreements related to each of
(i) MGTA-145, (ii) MGTA-45 and (iii) the CD117 antibodies, including the clinical antibody that was used with MGTA-117. We note from Magenta’s Form 10-Q for the period then ended that assets held for sale appears to consist of only remaining lab equipment (referring to page 15
therein). Please address the following:

•

 Tell us how you considered the guidance of ASC
205-20-45 in determining whether discontinued operations accounting was appropriate for some or all of the asset purchase agreements for the drug candidates.

•

 Further in this regard, noting the sale of MGTA-45 on
April 7, 2023 (page 143), tell us why you reported the $1.1 million recorded as other income as of March 31, 2023 (referring to page 21 of the March 31, 2023 Form 10-Q), instead of gain from discontinued operations, is appropriate.

 RESPONSE: Magenta
acknowledges the Staff’s comment and advises the Staff that it has considered the provisions of ASC 205-20-45, Discontinued Operations, in concluding that
each of the MGTA-145, MGTA-45, and CD117 antibodies, including the clinical antibody that was used with MGTA-117, asset sales do
not qualify as discontinued operations.

 MGTA-145 and MGTA-45 represent
product candidates that Magenta was advancing through pre-clinical and clinical trials. CD117 antibodies were used with Magenta’s MGTA-117 product candidate, which
Magenta was

 U.S. Securities and Exchange Commission

June 22, 2023

  Page
 5

advancing through clinical trials. The asset sale agreements are comprised of the transfer of intellectual property and related data; contracts and licenses directly related to the assets; and
additional information such as regulatory correspondence and other information, as applicable. Each of the three asset purchase agreements consist of the sale of a single asset that is comprised of intellectual property and associated support
relating to that specific asset.

 Pursuant to ASC
205-20-45-1B, the operations related to a disposal of the MGTA-145, MGTA-45 and CD117 antibodies assets are reported in discontinued operations in the statement of operations if all of the following criteria are met:

•

 The disposed assets (and liabilities) together represent a component of an entity (or a group of components of an
entity).

•

 The component (or group of components) (1) meets the criteria to be classified as held for sale,
(2) has been sold, or (3) has been disposed of other than by sale.

•

 The disposal of the component “represents a strategic shift that has (or will have) a major effect on an
entity’s operations and financial results”.

 In regard to the criteria described above, a component of an entity is defined in
the U.S. GAAP Master Glossary as follows:

 A component of an entity comprises operations and cash flows that can be clearly
distinguished, operationally and for financial reporting purposes, from the rest of the entity. A component of an entity may be a reportable segment or an operating segment, a reporting unit, a subsidiary, or an asset group.

As noted in Magenta’s filings on Forms 10-K and 10-Q, direct research and
development expenses are tracked on a program-by-program basis and consist primarily of external costs, such as fees paid to consultants, central laboratories,
contractors, contract development and manufacturing organizations (”CDMOs”) and contract research organizations (“CROs”) in connection with its preclinical and clinical development activities. Magenta does not allocate employee
costs, costs associated with its platform technology or facility expenses, including depreciation or other indirect costs, to specific product development programs because these costs are deployed across multiple product development programs and, as
such, are not separately classified. MGTA-145 was a product candidate being developed as part of Magenta’s mobilization program. MGTA-45 and MGTA-117, which CD-117 was used with, were product candidates being developed as part of Magenta’s conditioning program.

Neither operations or cash flows for each of the product candidates within these two development programs could be clearly distinguished as internal employee
resources, equipment and facility costs

United States securities and exchange commission logo
June 13, 2023
Stephen Mahoney
President, Chief Financial and Operating Officer
Magenta Therapeutics, Inc.
300 Technology Square, 8th Floor
Cambridge, MA 02139
Re:Magenta Therapeutics, Inc.
Registration Statement on Form S-4
Filed May 15, 2023
File No. 333-271917
Dear Stephen Mahoney:
            We have reviewed your 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 amending your registration statement and providing the
requested information.  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 any amendment to your registration statement and the information you
provide in response to these comments, we may have additional comments.
Registration Statement on Form S-4
Questions and Answers About the Merger
Q: What are contingent value rights ("CVR")?, page 4
1.We note your disclosure that, "[i]n April 2023, Magenta sold certain assets, including
intellectual property, related to its product candidates MGTA-45, MGTA-145 and the
CD117 antibodies including the clinical antibody that was used with MGTA-117, and is
continuing to explore strategic alternatives related to its other assets." Please specify the
programs or pre-merger assets held by Magenta the are covered by the CVR Agreement.
We note from your disclosure on pages 253 and 254 that the April 2023 asset
sales included certain up-front cash payments as well as future potential milestone
payments. Please clarify whether or not any of the April 2023 asset sales by Magenta,
including future milestone payments, are covered by the CVR Agreement.

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 June 13, 2023 Page 2
 FirstName LastNameStephen Mahoney
Magenta Therapeutics, Inc.
June 13, 2023
Page 2
2.Please revise your disclosure to clarify the material terms of the CVR Agreement, your
intentions with Magenta's pre-merger assets and describe any material assets that either
have been sold or may be sold by Magenta pursuant to the CVR Agreement or otherwise
advise.
The Companies
Magenta, page 10
3.You state here and on page 252 that in April 2023, Magenta sold certain assets, related to
Magenta's prior product candidates. However, you also state that Magenta is continuing to
explore strategic alternatives related to its "other assets." Given your recent sales in April
2023, please revise your disclosure to clarify what you mean when you state "other assets"
to specifically describe any material assets or otherwise advise.
Prospectus Summary, page 12
4.Please balance your discussion here, and on page 145, to disclose the negative factors or
potential risks associated with your merger agreement that were considered by the boards
of directors of Magenta and Dianthus, respectively, when each voted
to approve the merger agreement.
Risk Factors
Risks Related to the Merger
Some Magenta and Dianthus directors and executive officers have interests in the merger..., page
28
5.We note your disclosure that "certain of Dianthus’ directors are affiliated with investment
funds which hold an interest in Dianthus and are participating in the Dianthus pre-
closing financing." Please update your disclosure here to identify the directors and the
fund(s) they are affiliated with that are participating in the pre-closing financing.
The Merger
Background of the Merger, page 133
6.Please revise your disclosure to identify the individuals who negotiated the material terms
of the merger. For example only, we note your disclosure that "Magenta's management,"
"participants" and certain "financial advisors" were part of the negotiations related to the
merger.
7.We note your disclosure on page 136 discussing certain "Criteria" that would be used to
evaluate any potential indications of interest. Please revise to more specifically describe
the criteria proposed to assess potential counterparties. For example, if you were looking
for parties with a product candidate that had achieved a specific stage of development,
what stage was that? What were you looking for with respect to the attractiveness of the
counterparty’s technology and development pipeline? Additionally, please discuss
whether the criteria and/or the prioritization of the criteria changed over time.

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 June 13, 2023 Page 3
 FirstName LastNameStephen Mahoney
Magenta Therapeutics, Inc.
June 13, 2023
Page 3
8.On page 140 you state that on March 21, 2023 representatives of Wedbush communicated
to representatives of Dianthus Magenta's willingness to agree to a traditional reverse
merger in exchange for an increase in the valuation attributed to Magenta. Please include a
description of Dianthus' response to such communication.
9.We note your disclosure that "after reviewing all of the submitted indications of interest,
the participants selected 12 indications of interest to prioritize and invite to make
management and due diligence presentations." However, your disclosure appears to only
disclose Parties A through D. Please update your disclosure to describe the seven other
parties that were invited to make presentations. In addition, update your existing
disclosure where you describe Parties A through D to provide additional details about
each party, including a description of the general industry of the company.
Opinion of Houlihan Lokey to the Magenta Board, page 154
10.Revise to provide additional information regarding how Houlihan Lokey selected the
comparable companies and whether it excluded any comparable companies that fit those
criteria.
11.Please explain the statement "Houlihan Lokey selected an implied enterprise value
reference range for Dianthus of $150.0 million to $200.0 million, which resulted in an
aggregate implied equity value reference range for Dianthus of $274.2 million to $324.2
million, and an implied per share reference range for Dianthus of $4.75 to $5.62.” Please
clarify how Houlihan Lokey arrived at the $150.0 million to $200.0 million range. For
example, did Houlihan Lokey use the mean, median, high or low value from the
calculations of the comparable companies? Please explain what other considerations
Houlihan Lokey deemed relevant and how they impacted Houlihan Lokey's analysis.
12.We note your disclosure that “[t]he Magenta Liquidation Analysis and Houlihan Lokey’s
selected companies analysis for Dianthus indicated an implied exchange ratio reference
range of 4.42844313 to 5.33756289 shares of Magenta common stock for each share of
Dianthus capital stock, as compared to the exchange ratio in the merger pursuant to the
Merger Agreement of 3.88182949 shares of Magenta common stock for each share of
Dianthus capital stock.” Please revise to describe the conclusions Houlihan Lokey reached
with respect to the implied exchange ratio as a result of such comparisons.
The Merger Agreement, page 177
Potential Asset Sale, page 183
13.You state hereunder that in April 2023, Magenta entered into asset purchase agreements
related to each of (i) MGTA-145, (ii) MGTA-45 and (iii) the CD117 antibodies, including
the clinical antibody that was used with MGTA-117. We note from Magenta's Form 10-Q
for the period then ended that assets held for sale appears to consist of only remaining lab
equipment (referring to page 15 therein).  Please address the following:
•Tell us how you considered the guidance of ASC 205-20-45 in determining whether

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 June 13, 2023 Page 4
 FirstName LastNameStephen Mahoney
Magenta Therapeutics, Inc.
June 13, 2023
Page 4
discontinued operations accounting was appropriate for some or all of the asset
purchase agreements for the drug candidates.
•Further in this regard, noting the sale of MGTA-45 on April 7, 2023 (page 143), tell
us why you reported the $1.1 million recorded as other income as of March 31, 2023
(referring to page 21 of the March 31, 2023 Form 10-Q), instead of gain from
discontinued operations, is appropriate.
Dianthus' Business
DNTH103, page 281
14.Please update your disclosure to define C1s and clarify what you mean when you state
you are targeting "Active C1s." In addition, please revise your disclosure to clarify how
preventing further progression of the classical pathway cascade helps severe autoimmune
and inflammatory diseases.
15.Please define all technical and scientific terms throughout the business section, such as
"diplopia and ptosis" and "MAC formation" on first use.
16.We note your disclosure that "DNTH103 has the potential to become a first-line, steroid-
sparing treatment option." Please revise your disclosure to clarify what you mean when
you state "steroid-sparing treatment" or otherwise advise. We note your disclosure
elsewhere appears to indicate that biologics such as IVIG or FcRn inhibitors are currently
being use to treat gMG.
Dianthus' Pipeline of Next-Generation Complement Therapeutics, page 281
17.We note your pipeline table on page 281. Specifically, we note that Dianthus appears to
currently only have an ongoing Phase 1 trial for DNTH103 yet your pipeline table
includes five arrows under DNTH103, four of which appear to depict completion of Phase
1 clinical trials. Progress arrows should be moved to clearly depict the progress of each
candidate to date and should not encroach on phases not commenced. Please amend the
table to properly reflect the current status of Dianthus' product candidate.
18.The pipeline table includes two separate programs with the general description
“Additional Active Selective Complement Target” that are all in the early stages of
discovery. Please limit your table to product candidates that are sufficiently material to
your business to warrant inclusion in your table. If these new targets are material, identify
the indications and expand your disclosure elsewhere to identify more specifically these
programs or candidates.
Dianthus’ First Product Candidate, DNTH103, page 286
19.We note your disclosure of trials relating to your product candidates throughout this
section. Please revise to clarify whether each trial was powered for statistical significance.
In addition, if a trial was powered for statistical significance please provide p-values for
the results of each trial.

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 June 13, 2023 Page 5
 FirstName LastNameStephen Mahoney
Magenta Therapeutics, Inc.
June 13, 2023
Page 5
20.We note your disclosure that, "[a]ccording to published scientific literature, Dianthus
anticipates a significantly longer half-life in humans." Please update your disclosure to
discuss the "specific literature" you are referring to.
21.We note your disclosure here and elsewhere in your registration statement in which you
make statements related to potential safety and efficacy, which are premature given the
stage of development of Dianthus' product candidates. For example, we note your
disclosure here that DNTH103 has a "[m]ore favorable safety profile." Please revise your
disclosure throughout your document, including but not limited to the statement noted
above, to eliminate the implication that your product candidates have been or will
ultimately be determined safe and/or effective or have demonstrated safety and/or efficacy
for purposes of approval by the FDA or comparable agency.
22.We note your disclosure of a "representative experiment" for which DNTH103 was
compared to "recombinantly-generated" sutimlimab and ravulizumab that were based on
amino acid sequences from patent filings." Please clarify what "recombinantly-generated
based off of patent filings" means and describe any risks to using "recombinantly-
generated" sutimlimab and ravulizumab in your experiment or otherwise advise. In
addition, please update your disclosure to clarify that the results in the "representative
experiment" may not be predictive of or consistent with the results of later trials.
License Agreements
Zenas BioPharma, page 296
23.Please file your license agreement with Zenas BioPharma Limited as an exhibit to your
filing, or provide us with your updated analysis as to why it need not be filed under Item
601 of Regulation S-K.
Management Following the Merger
Executive Officers and Directors, page 349
24.Please revise your disclosure regarding the background and history of your executive
officer and director to comply with Item 401(e)(1) of Regulation S-K. Specifically, revise
your disclosure to describe the business experience, principal occupations and
employment, of Anne McGeorge during the past five years, including the dates and
duration of their employment.
Unaudited Pro Forma Condensed Combined Financial Information, page 365
25.You disclose on page 365 that the merger is expected to be treated as a reverse
recapitalization because on the effective date of the merger, the pre-combination assets of
Magenta are expected to be primarily cash and cash equivalents and marketable
securities. Please address the following:
•Tell us and revise your pro forma narrative and MD&A to more clearly disclose the
extent to which you expect there to be any residual research and development
activities and expenses or facilities expense continuing in Magenta after the sale of

 FirstName LastNameStephen Mahoney
 Comapany NameMagenta Therapeutics, Inc.
 June 13, 2023 Page 6
 FirstName LastNameStephen Mahoney
Magenta Therapeutics, Inc.
June 13, 2023
Page 6
certain assets under the April 2023 asset purchase agreements.
•If so, explain how you considered this fact as part of your determination that Magenta
will be a shell company for purposes of reverse recapitalization treatment.
•Tell us how you considered the potential future revenue streams associated with the
asset purchase agreements including milestone and royalty payments in your
determination that the company will be a shell company for purposes
of recapitalization accounting.
•Tell us how you considered the Contingent Value Right (CVR) agreements
associated with the asset purchase agreements in determining that the company will
be a shell company for purposes of recapitalization accounting.

26.You disclose that you expect the merger to be treated as a reverse recapitalization and
such accounting is reflected in the pro forma financial information. Given the asset
purchase agreements and CVR are central to the consideration of whether Magenta will
effectively be a shell company as of the merger date and appear to be significant, tell us
how you determined that it was appropriate under Article 11 of Regulation S-X not to give
effect to the asset purchase agreements and the CVR in the pro forma financial
information. As part of your response, specifically explain how you determined whether
these arrangements represent the disposition of a business under the guidance of Section
11-01(a)(4) of Regulation S-X.
General
27.We note the disclosure that the merger is " intended to qualify as a “reorganization”
within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended
(the “Code”) for U.S. federal income tax purposes.” Please revise to clarify the tax
consequences of the merger to investors and file a tax opinion. For guidance, please refer
to Staff Legal Bulletin No. 19.
            We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
            Refer to Rules 460 and 461 regarding requests for acceleration.  Please allow adequate
time for us to review any amendment prior to the requested effective date of the registration
statement.
            You may cont

CORRESP
1
filename1.htm

CORRESP

 Magenta Therapeutics, Inc.

100 Technology Square

 Cambridge,
MA 02139

 August 10, 2022

 Via EDGAR
Transmission

 United States Securities and Exchange Commission

Division of Corporation Finance

 Office of Life Sciences

100 F Street, N.E.

 Washington, D.C. 20549

Attention: Tyler Howes

Re:
 Magenta Therapeutics, Inc.: Registration Statement on
Form S-3 filed August 4, 2022 (File No. 333-266511)

Ladies and Gentlemen:

 Pursuant to Rule 461
under the Securities Act of 1933, as amended (the “Act”), Magenta Therapeutics, Inc. (the “Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration
Statement”) be accelerated to August 12, 2022, at 4:01 pm Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

If you have any questions regarding this request, please contact William Collins of Goodwin Procter LLP at (617) 570-1447.

Sincerely,

Magenta Therapeutics, Inc.

 /s/ Stephen Mahoney

Stephen Mahoney

Chief Financial and Operating Officer

cc:
 Thomas W. Beetham, Secretary and Chief Legal Officer, Magenta Therapeutics, Inc.

William Collins, Esq., Goodwin Procter LLP

Mitchell S. Bloom, Esq., Goodwin Procter LLP

United States securities and exchange commission logo
August 9, 2022
Jason Gardner
Chief Executive Officer
Magenta Therapeutics, Inc.
100 Technology Square
Cambridge, Massachusetts 02139
Re:Magenta Therapeutics, Inc.
Registration Statement on Form S-3
Filed August 4, 2022
File No. 333-266511
Dear Dr. Gardner:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration.  We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Tyler Howes at 202-551-3370 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       William Collins, Esq.

CORRESP
1
filename1.htm

CORRESP

 Magenta Therapeutics, Inc.

100 Technology Square

 Cambridge,
MA 02139

 July 6, 2021

 Via EDGAR Transmission

 United States Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

Re:
 Magenta Therapeutics, Inc.: Registration Statement on
Form S-3 filed June 25, 2021 (File No. 333-257381)

Ladies and Gentlemen:

 Pursuant to Rule 461
under the Securities Act of 1933, as amended (the “Act”), Magenta Therapeutics, Inc. (the “Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration
Statement”) be accelerated to July 9, 2021, at 4:01 pm Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

If you have any questions regarding this request, please contact William Collins of Goodwin Procter LLP at (617) 570-1447.

 Sincerely,

 Magenta Therapeutics, Inc.

/s/ Jason Gardner

 Jason Gardner

 President and Chief Executive Officer

cc:
 Thomas W. Beetham, Secretary and Chief Legal Officer, Magenta Therapeutics, Inc.

William Collins, Esq., Goodwin Procter LLP

Mitchell S. Bloom, Esq., Goodwin Procter LLP

United States securities and exchange commission logo
July 1, 2021
Jason Gardner, PhD
President and Chief Executive Officer
Magenta Therapeutics, Inc.
100 Technology Square
Cambridge, MA 02139
Re:Magenta Therapeutics, Inc.
Registration Statement on Form S-3
Filed June 25, 2021
File No. 333-257381
Dear Dr. Gardner:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration.  We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Lauren Hamill at 303-844-1008 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       William D. Collins

CORRESP
1
filename1.htm

CORRESP

 Magenta Therapeutics, Inc.

100 Technology Square

 Cambridge,
MA 02139

 August 14, 2019

 Via EDGAR
Transmission

 United States Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

Re:
 Magenta Therapeutics, Inc.: Registration Statement on
Form S-3 filed August 8, 2019 (File No. 333-233127)

Ladies and Gentlemen:

 Pursuant to Rule 461
under the Securities Act of 1933, as amended (the “Act”), Magenta Therapeutics, Inc. (the “Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration
Statement”) be accelerated to August 19, 2019, at 4:01 pm Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared
effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

If you have any questions regarding this request, please contact William Collins of Goodwin Procter LLP at (617) 570-1447.

Sincerely,

Magenta Therapeutics, Inc.

/s/ Jason Gardner

 Jason Gardner

 President and Chief Executive
Officer

cc:
 Zoran Zdraveski, Secretary and Chief Legal Officer, Magenta Therapeutics, Inc.

William Collins, Esq., Goodwin Procter LLP

Mitchell S. Bloom, Esq., Goodwin Procter LLP

August 9, 2019
Jason Gardner
Chief Executive Officer
Magenta Therapeutics, Inc.
100 Technology Square
Cambridge, MA 02139
Re:Magenta Therapeutics, Inc.
Registration Statement on Form S-3
Filed August 8, 2019
File No. 333-233127
Dear Mr. Gardner:
            This is to advise you that we have not reviewed and will not review your registration
statement.
            Please refer to Rules 460 and 461 regarding requests for acceleration.  We remind you
that the company and its management are responsible for the accuracy and adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action by the staff.
            Please contact Donald Field at 202-551-3680 with any questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance

CORRESP
1
filename1.htm

CORRESP

 VIA EDGAR

April 29, 2019

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 Mail Stop 4561

 100 F Street, N.E.

 Washington, D.C. 20549

Attention: Tonya K. Aldave

Re:
 Magenta Therapeutics, Inc.

Acceleration Request for Registration Statement on Form S-1

File No. 333-231097

 Dear Ms. Aldave:

In accordance with Rule 461 under the Securities Act of 1933, as amended (the “Act”), we, as representatives of the several
underwriters, (the “Underwriters”) hereby join in the request of Magenta Therapeutics, Inc. (the “Company”) for acceleration of the effective date of the above-referenced Registration Statement so that it becomes
effective on May 1, 2019 at 4:00 p.m. Eastern Time or as soon thereafter as practicable, or at such other time as the Company or its outside counsel, Goodwin Procter LLP, may orally request by telephone call that such Registration Statement be
declared effective.

 Pursuant to Rule 460 under the Act, the Underwriters wish to advise you that there will be distributed to each
Underwriter or dealer, who is reasonably anticipated to participate in the distribution of the security, as many copies of the proposed form of preliminary prospectus as appears to be reasonable to secure adequate distribution of the preliminary
prospectus.

 We, the undersigned, as representatives of the several underwriters, have complied and will comply with the requirements of
Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.

 [Signature pages as follows]

Accepted: As of the date first written above

J.P. MORGAN SECURITIES LLC

GOLDMAN SACHS & CO. LLC

COWEN AND COMPANY, LLC

For themselves and on behalf of the several Underwriters listed in Schedule 1 hereto.

J.P. MORGAN SECURITIES LLC

By:

 /s/ David Ke

Name: David Ke

Title: Executive Director

GOLDMAN SACHS & CO. LLC

By:

 /s/ Elizabeth Wood

Name: Elizabeth Wood

Title: Managing Director

COWEN AND COMPANY, LLC

By:

 /s/ George Milstein

Name: George Milstein

Title: Managing Director

 [Signature Page to Acceleration Request]

CORRESP
1
filename1.htm

CORRESP

 VIA EDGAR

April 29, 2019

 United States Securities and Exchange
Commission

 Division of Corporation Finance

 Mail Stop 4561

 100 F Street, N.E.

 Washington, D.C. 20549

Attention: Tonya K. Aldave

Re:
 Magenta Therapeutics, Inc.

Acceleration Request for Registration Statement on Form S-1

File No. 333-231097

Dear Ms. Aldave:

 Pursuant to Rule 461 under the Securities Act
of 1933, as amended (the “Act”), Magenta Therapeutics, Inc. (the “Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration Statement”) be
accelerated to May 1, 2019, at 4:00 p.m., Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time.
In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act.

 Once the Registration Statement is
effective, please orally confirm the event with our counsel, Goodwin Procter LLP by calling William Collins at (617) 570-1447. We also respectfully request that a copy of the written order from the Securities
and Exchange Commission (the “Commission”) verifying the effective time and date of the Registration Statement be sent to our counsel, Goodwin Procter LLP, Attention: William Collins, by facsimile to (617) 321-4422.

 If you have any questions regarding this request, please contact William Collins of Goodwin Procter LLP at
(617) 570-1447.

 Sincerely,

 MAGENTA THERAPEUTICS, INC.

/s/ Jason Gardner

 Jason Gardner

President and Chief Executive Officer

cc:
 Jason Gardner, President and Chief Executive Officer, Magenta Therapeutics, Inc.

William Collins, Esq., Goodwin Procter LLP

 Mitchell Bloom,
Esq., Goodwin Procter LLP

April 4, 2019
Jason Gardner
Chief Executive Officer
Magenta Therapeutics, Inc.
100 Technology Square
Cambridge, MA 02139
Re:Magenta Therapeutics, Inc.
Draft Registration Statement on Form S-1
Submitted March 29, 2019
CIK No. 0001690585
Dear Dr. Gardner:
            This is to advise you that we do not intend to review your registration statement.
            We request that you publicly file your registration statement no later than 48 hours prior
to the requested effective date and time. Please refer to Rules 460 and 461 regarding requests for
acceleration. We remind you that the company and its management are responsible for the
accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or
absence of action by the staff.
            Please contact Tonya K. Aldave at (202) 551-3601 with any questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       William D. Collins, Esq.

CORRESP
1
filename1.htm

CORRESP

 June 18, 2018

VIA EDGAR

 Securities and Exchange Commission

 Division of Corporation Finance

 100 F Street, N.E.

Washington, DC 20549

Re:
Magenta Therapeutics, Inc.

 Registration Statement on Form
S-1 (File No. 333-225178)

 Ladies and Gentlemen:

 In accordance with Rule 461 under the Securities Act of 1933, as amended (the “Act”), we, as representatives of the
several underwriters (the “Underwriters”), hereby join in the request of Magenta Therapeutics, Inc. with respect to the effective time of the above-referenced Registration Statement so that it will become effective June 20, 2018, at
3:00 p.m. Eastern Time, or as soon thereafter as practicable.

 In connection with this acceleration request and pursuant to Rule 460 under
the Act, please be advised that, during the period from June 8, 2018 to the date of this letter, we have effected approximately the following distribution of copies of the preliminary prospectus, dated June 8, 2018, to underwriters,
dealers, institutions, and others:

 Requesting Party

Number of Copies

 J.P. Morgan Securities LLC

1,580

 Goldman Sachs & Co. LLC

40

 Cowen and Company, LLC

137

 Wedbush Securities Inc.

145

 We, the undersigned, as representatives of the several Underwriters, have complied and will comply, and we
have been informed by the participating Underwriters that they have complied and will comply, with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.

[Remainder of Page Intentionally Left Blank]

 Very truly yours,

J.P. MORGAN SECURITIES LLC

 GOLDMAN SACHS & CO. LLC

COWEN AND COMPANY, LLC

on behalf of themselves and as representatives of the Underwriters

J.P. MORGAN SECURITIES LLC

By:

/s/ David Ke

 Name:

 Title:

 David Ke

 Executive Director

GOLDMAN SACHS & CO. LLC

By:

/s/ Raffael Fiumara

 Name:

 Title:

 Raffael Fiumara

 Vice President

COWEN AND COMPANY, LLC

By:

/s/ Bill Follis

 Name:

 Title:

 Bill Follis

 Managing Director

 [Signature Page to Underwriters’ Acceleration Request Letter]

CORRESP
1
filename1.htm

CORRESP

 Magenta Therapeutics, Inc.

50 Hampshire Street, 8th Floor

Cambridge, MA 02139

 VIA EDGAR AND
FACSIMILE

 June 18, 2018

 United States Securities
and Exchange Commission

 Division of Corporation Finance

Mail Stop 4561

 100 F Street, N.E.

Washington, D.C. 20549

 Attention: Irene Paik

RE:
Magenta Therapeutics, Inc.

Registration Statement on Form S-1

File No. 333- 225178

 Dear Ms. Paik:

Pursuant to Rule 461 under the Securities Act of 1933, as amended (the “Act”), Magenta Therapeutics, Inc. (the
“Company”) hereby requests that the effective date of the above-referenced registration statement (the “Registration Statement”) be accelerated to June 20, 2018, at 3:00 p.m., Eastern Time, or as soon thereafter as
practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its
responsibilities under the Act.

 Once the Registration Statement is effective, please orally confirm the event with our counsel, Goodwin
Procter LLP by calling William D. Collins at (617) 570-1447. We also respectfully request that a copy of the written order from the Securities and Exchange Commission (the “Commission”)
verifying the effective time and date of the Registration Statement be sent to our counsel, Goodwin Procter LLP, Attention: William D. Collins, by facsimile to (617) 321-4422.

In connection with the foregoing, the Company hereby acknowledges the following:

•

should the Commission or the staff of the Commission, acting pursuant to delegated authority, declare the Registration Statement effective, it does not foreclose the Commission from taking any action with respect to the
Registration Statement;

•

the action of the Commission or the staff of the Commission, acting pursuant to delegated authority, in declaring the Registration Statement effective, does not relieve the Company from its full responsibility for the
adequacy and accuracy of the disclosure in the Registration Statement; and

•

the Company may not assert staff comments and the declaration of effectiveness as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

 If you have any questions regarding this request, please contact William D. Collins of Goodwin Procter LLP at (617) 570-1447.

 [Remainder of Page Intentionally Left Blank]

 Sincerely,

MAGENTA THERAPEUTICS, INC.

/s/ Jason Gardner

 Jason Gardner

 President and Chief Executive
Officer

cc:
Zoran Zdraveski, Esq., Magenta Therapeutics, Inc.

 Mitchell S. Bloom, Esq., Goodwin
Procter LLP

CORRESP
1
filename1.htm

CORRESP

 June 8, 2018

Irene Paik

 Ada D. Sarmento

Office of Healthcare and Insurance

 Division of Corporation
Finance

 Securities and Exchange Commission

 100 F Street,
N.E.

 Washington, D.C. 20549

Re:
Magenta Therapeutics, Inc.

Registration Statement on Form S-1

Filed May 24, 2018

File No. 333-225178

 Dear Ms. Paik and Ms. Sarmento:

On behalf of our client, Magenta Therapeutics, Inc. (the “Company”), we are responding to the comment from the Staff
(the “Staff”) of the Securities and Exchange Commission (the “Commission”) relating to the Company’s Registration Statement on Form S-1 (the
“Registration Statement”) contained in the Staff’s letter dated June 6, 2018 (the “Comment Letter”). In response to the comment set forth in the Comment Letter, the Company has revised the
Registration Statement and is publicly filing its Amendment No. 1 to the Registration Statement on Form S-1 (“Amendment No. 1”) together with this
response letter. Amendment No. 1 also contains certain additional updates and revisions. We are also sending, under separate cover, a copy of Amendment No. 1 (including exhibits) and four marked copies of Amendment No. 1 showing the
changes to the Registration Statement publicly filed on May 24, 2018.

 Set forth below is the Company’s response to the
Staff’s comment in the Comment Letter. The response and information below are based on information provided to us by the Company. For convenience, the Staff’s comment is repeated below in italics, followed by the Company’s response to
the comment as well as a summary of the responsive actions taken. We have included page numbers to refer to the location in Amendment No. 1 submitted herewith where the revised language addressing a particular comment appears. Capitalized terms
used but not defined herein are used herein as defined in Amendment No. 1.

 Registration Statement on Form
S-1

 Prospectus Summary

Our Current Programs, page 4

1.
 We note your response to our prior comment 1. While we do not object to the presentation of your most advanced
discovery programs as a graphic in the Business section or the narrative discussion of such programs following the graphic in the Prospectus Summary, we believe that presenting these programs as a prominent graphic on page 4, in the forepart of the
prospectus, is not appropriate given that product

candidates have yet to be identified and these programs remain in the discovery phase. Please revise to remove this graphic from page 4.

Response to Comment No. 1: The Company acknowledges the Staff’s comment and respectfully advises the Staff that the Company has removed its
preclinical development programs graphic on page 4 of Amendment No. 1.

 Should you have any further comments or questions with
regard to the foregoing, please contact the undersigned at 617-570-1447.

Sincerely,

/s/ William D. Collins

William D. Collins

 Enclosures

cc:
Jason Gardner, Magenta Therapeutics, Inc.

Zoran Zdraveski, Magenta Therapeutics, Inc.

Mitchell S. Bloom, Goodwin Procter LLP

Deanna L. Kirkpatrick, Davis Polk & Wardwell LLP

June 6, 2018
Jason Gardner
President and Chief Executive Officer
Magenta Therapeutics, Inc.
50 Hampshire Street
Cambridge, Massachusetts 02139
Re:Magenta Therapeutics, Inc.
Registration Statement on Form S-1
Filed May 24, 2018
File No. 333-225178
Dear Dr. Gardner:
            We have reviewed your amended registration statement and have the following
comment.
            Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe our comment applies to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.
            After reviewing any amendment to your registration statement and the information you
provide in response to this comment, we may have additional comments.  Unless we note
otherwise, our references to prior comments are to comments in our May 16, 2018 letter.
Registration Statement on Form S-1
Prospectus Summary
Our Current Programs, page 4
1.We note your response to our prior comment 1. While we do not object to the presentation
of your most advanced discovery programs as a graphic in the Business section or the
narrative discussion of such programs following the graphic in the Prospectus Summary,
we believe that presenting these programs as a prominent graphic on page 4, in the
forepart of the prospectus, is not appropriate given that product candidates have yet to be
identified and these programs remain in the discovery phase. Please revise to
remove this graphic from page 4.

 FirstName LastNameJason Gardner
 Comapany NameMagenta Therapeutics, Inc.
 June 6, 2018 Page 2
 FirstName LastName
Jason Gardner
Magenta Therapeutics, Inc.
June 6, 2018
Page 2
            You may contact Vanessa Robertson at 202-551-3649 or Sharon Blume at 202-551-3474
if you have questions regarding comments on the financial statements and related
matters.  Please contact Irene Paik at 202-551-6553 or Ada D. Sarmento at 202-551-3798 with
any other questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       William D. Collins - Goodwin Procter

CORRESP
1
filename1.htm

CORRESP

 CONFIDENTIAL TREATMENT REQUESTED

BY MAGENTA THERAPEUTICS, INC.

MGTA-0001

 Goodwin Procter
LLP

 100 Northern Avenue

 Boston,
MA 02210

 T: 617.570.1000

 F:
617.523.1231

 May 31, 2018

 FOIA CONFIDENTIAL
TREATMENT REQUEST

 The entity requesting confidential treatment is

Magenta Therapeutics, Inc.

 50 Hampshire Street

Cambridge, MA 02139

 Telephone: (857) 242-0170

CERTAIN PORTIONS OF THIS LETTER HAVE BEEN OMITTED FROM THE VERSION FILED VIA EDGAR. CONFIDENTIAL TREATMENT HAS BEEN
REQUESTED WITH RESPECT TO THE OMITTED PORTIONS. INFORMATION THAT WAS OMITTED IN THE EDGAR VERSION HAS BEEN NOTED IN THIS LETTER WITH A PLACEHOLDER IDENTIFIED BY THE MARK “[***].”

VIA EDGAR, FACSIMILE AND FEDERAL EXPRESS

 United
States Securities and Exchange Commission

 Division of Corporation Finance

Office of Healthcare and Insurance

 100 F Street, N.E.

Washington, D.C. 20549

 Attention: Irene Paik

Ada D. Sarmento

RE:
Magenta Therapeutics, Inc.

 Registration Statement on Form
S-1 (the “Registration Statement”)

 File No.
333-225178

 CIK No. 0001690585

Rule 83 Confidential Treatment Request by Magenta Therapeutics, Inc.

Dear Ms. Paik and Ms. Sarmento:

 This letter is being
submitted on behalf of Magenta Therapeutics, Inc. (the “Company”) to supplementally provide the Staff (the “Staff”) of the U.S. Securities and Exchange Commission (the “Commission”) with additional
information with respect to the above-referenced Registration Statement that was filed with the Commission on May 24, 2018.

 To assist the Staff of
the Commission in the review of the Registration Statement, the Company advises the Staff that the managing underwriters in the initial public offering have communicated to the Company that they currently expect the proposed price range for the
common stock to be between $[***] to $[***] per share, before giving effect to a reverse stock split to be implemented prior to the initial public offering (“IPO”). The anticipated price range for this offering is based on a number
of factors, including the prevailing market conditions and estimates of the Company’s business potential, the general condition of the securities market, the recent market prices of, and the demand for, publicly traded common stock of generally
comparable companies and preliminary discussions with the underwriters for this offering regarding potential valuations of the Company. The actual bona fide price range to be included in a subsequent amendment to the Registration Statement
has not yet been determined and remains subject

 1

 CONFIDENTIAL TREATMENT REQUESTED

BY MAGENTA THERAPEUTICS, INC.

MGTA-0002

to adjustment based on factors outside of the Company’s control. However, the Company believes that the actual bona fide price range will be within this estimated price range. In
addition, the actual price range to be included in such amendment will comply with the Staff’s interpretation regarding the parameters of a bona fide price range.

We confirm on behalf of the Company that, prior to circulating copies of the preliminary prospectus in connection with the offering, the Company will file a pre-effective amendment to the Registration Statement that will include all information other than information that may be excluded in reliance upon Rule 430A of Regulation C, and the actual price range to be
included in such amendment which will comply with the Staff’s interpretation regarding the parameters of a bona fide price range.

 Magenta
Therapeutics, Inc. respectfully requests that the bracketed information contained in this letter be treated as confidential information and that the Commission provide timely notice to Cindy Driscoll, Vice President, Finance, Magenta Therapeutics,
Inc., 50 Hampshire Street, Cambridge, MA 02139, and Zoran Zdraveski, Esq., Chief Legal Officer, Magenta Therapeutics, Inc., 50 Hampshire Street, Cambridge, MA 02139, before it permits any disclosure of the bracketed information in this letter.

 Estimated Initial Public Offering Price

 The
estimated price range for this offering was determined with reference to several quantitative and qualitative factors. In May 2018, the Company and the underwriters determined the estimated price range, which is $[***] to $[***] per share. In
comparison, the Company’s estimate of the fair value of its common stock was $3.67 per share as of April 2, 2018 immediately following its Series C Preferred Stock financing round, based upon a third-party valuation of the Company’s
common stock that applied both an option-pricing method and a probability-weighted expected return method. This analysis probability-weighted IPO and remain-private scenarios. The Company notes that, as is typical in initial public offerings, the
price range for this offering was not derived using a formal determination of fair value, but was determined based upon discussions between the Company and the underwriters. Among the factors considered in setting the price range for this offering
were the following:

•

a fundamental analysis of the business including a discounted cash flow valuation;

•

an analysis of the typical valuation ranges seen in recent IPOs for companies in the Company’s industry;

•

the general condition of the securities market and the recent market prices of, and the demand for, publicly traded common stock of generally comparable companies;

•

an assumption that there would be a receptive public trading market for biopharmaceutical companies such as the Company; and

•

an assumption that there would be sufficient demand for the Company’s common stock to support an offering of the size contemplated by the Company and the underwriters, based on the response to and feedback from the
Company’s “testing the waters” meetings.

 In addition, the Company believes that the difference in value reflected between
the midpoint of the estimated price range for this offering and the board of directors’ determination of the fair value of the Company’s common stock on April 2, 2018 was primarily the result of the following subsequent events and
circumstances:

•

The Company continued to advance its clinical program, including its continued Phase II clinical trial of MGTA-456 for treatment of patients with inherited metabolic diseases;

•

The Company continued to advance its pipeline, including preclinical studies of its CD117-ADC probe compounds, which have allowed the Company to begin to evaluate efficacy and
safety in non-human primates prior to conducting human clinical trials;

•

The public filing of the Company’s Registration Statement on Form S-1;

 2

 CONFIDENTIAL TREATMENT REQUESTED

BY MAGENTA THERAPEUTICS, INC.

MGTA-0003

•

In April 2018, the Company conducted “testing the waters” meetings with prospective investors and the Company received favorable feedback in late April, and as a result, the Company elected to continue with
the potential IPO;

•

Since September 2017, at least 30 biotechnology companies successfully completed initial public offerings, suggesting a potentially favorable market for companies similar to the Company in pursuing and completing
initial public offerings;

•

The price that investors are willing to pay in the IPO, for which the price range is intended to serve as an estimate, may take into account other factors that have not been expressly considered in prior valuations of
the Company’s common stock, but are significant to investors in their own subjective and qualitative assessment of the Company, and thus may not be objectively determinable or quantifiable under the above-described valuation models;

•

In the public markets, the Company believes there are investors who may apply more qualitative valuation criteria to certain of the Company’s assets than the above-described valuation methods applied in the
historical valuations of the Company’s common stock;

•

The estimated price range for the IPO necessarily assumes that the IPO has occurred and that a public market for the Company’s common stock has been created, and therefore excludes any discount for lack of
marketability of the Company’s common stock;

•

The IPO price is based only upon a scenario in which the Company completes this offering and is not probability weighted, in contrast to the Company’s prior valuations of the Company’s common stock, which
considered multiple potential outcomes, some of which would have resulted in a lower value of the Company’s common stock than an initial public offering. In the April 2, 2018 third-party valuation considered by the Company’s board of
directors, the probability weightings for IPO and remain-private scenarios were 60% and 40%, respectively;

•

The IPO price necessarily assumes that the IPO has occurred and that a public market for the Company’s common stock has been created, and, therefore, it excludes any discount for lack of marketability of the
Company’s common stock, which was taken into account in the Company’s board of directors’ determination of the fair value of the Company’s common stock on April 2, 2018. In the April 2, 2018 third-party valuation
considered by the Company’s board of directors, the discounts for lack of marketability that was applied to the IPO and remain-private scenarios were 5% and 22%, respectively;

•

The significant benefits the Company expects to accrue as a result of becoming publicly traded through the IPO, including (i) a substantial increase in the Company’s cash position after receiving the net
proceeds from the IPO, (ii) an anticipated improved ability of the Company to raise equity and debt capital going forward, and at a lower expected cost of capital and with reduced borrowing costs, as a result of being a publicly traded company,
and (iii) the expected increased attractiveness of the Company’s equity as a currency to raise capital, compensate employees and other strategic transactions; and

•

The Company’s currently outstanding convertible preferred stock has substantial economic rights and preferences superior to the Company’s common stock, including an aggregate liquidation preference of
$140,463,613. The IPO price assumes the conversion of the Company’s convertible preferred stock to common stock upon the completion of this offering and the corresponding elimination of such superior economic rights and preferences.

 The Company believes the anticipated price range for this offering is reasonable based on the above referenced factors. The Company also
refers you to the discussion of its general approach of determining fair value of equity awards set forth in the Registration Statement under the heading “Management’s Discussion and Analysis of Financial Condition and Results of
Operations – Critical Accounting Policies and Significant Judgments and Estimates – Stock-Based Compensation” for additional background regarding its equity grant valuation methodologies to date.

 3

 CONFIDENTIAL TREATMENT REQUESTED

BY MAGENTA THERAPEUTICS, INC.

MGTA-0004

 Because of the financially sensitive nature of the estimated price range, the Company requests confidential
treatment under 17 C.F.R. § 200.83 of the contents of this letter and has submitted a separate request for confidential treatment in accordance therewith to the Commission’s Office of Freedom and Information Privacy Act Operations.
Pursuant to Rule 418 under the Securities Act of 1933, as amended (the “Securities Act”), the information contained in this letter is being provided to the Commission on a confidential supplemental basis only and is not to be filed
with or deemed part of the Registration Statement. The Company respectfully requests that the Staff return the unredacted version of this letter to it pursuant to Rule 418 of the Securities Act once the Staff has completed its review. We have
provided a self-addressed stamped envelope for this purpose. Kindly acknowledge receipt of this letter by stamping the enclosed copy of this letter and returning it in the envelope provided.

*-*-*-*

 4

 CONFIDENTIAL TREATMENT REQUESTED

BY MAGENTA THERAPEUTICS, INC.

MGTA-0005

 If you have any questions or comments regarding the foregoing, or if there is any additional information that
we might provide to assist the Staff’s review, please contact the undersigned at (617) 570-1447 or Mitchell S. Bloom at (617) 570-1055.

Sincerely,

/s/ William D. Collins

William D. Collins

Enclosures

 cc:

Jason Gardner, Magenta Therapeutics, Inc.

 Zoran
Zdraveski, Magenta Therapeutics, Inc.

 Cindy Driscoll, Magenta Therapeutics, Inc.

Mitchell S. Bloom, Goodwin Procter LLP

 5

CORRESP
1
filename1.htm

CORRESP

 May 24, 2018

Irene Paik

 Ada D. Sarmento

Office of Healthcare and Insurance

 Division of Corporation
Finance

 Securities and Exchange Commission

 100 F Street,
N.E.

 Washington, D.C. 20549

Re:
Magenta Therapeutics, Inc.

Amendment No. 1 to Draft Registration Statement on Form S-1

Confidentially Submitted on May 7, 2018

CIK No. 0001690585

 Dear Ms. Paik and Ms. Sarmento:

On behalf of our client, Magenta Therapeutics, Inc. (the “Company”), we are responding to the comments from the Staff
(the “Staff”) of the Securities and Exchange Commission (the “Commission”) relating to the Company’s confidential Amendment No. 1 to Draft Registration Statement on Form S-1 (the “Draft Registration Statement”) contained in the Staff’s letter dated May 16, 2018 (the “Comment Letter”). In response to the comments set forth in
the Comment Letter, the Company has revised the Draft Registration Statement and is publicly filing its Registration Statement on Form S-1 (the “Registration Statement”) together with
this response letter. The Registration Statement also contains certain additional updates and revisions. We are also sending, under separate cover, a copy of the Registration Statement (including exhibits) and four marked copies of the Registration
Statement showing the changes to the Draft Registration Statement confidentially submitted on May 7, 2018.

 Set forth below are the
Company’s responses to the Staff’s comments in the Comment Letter. The responses and information below are based on information provided to us by the Company. For convenience, the Staff’s comments are repeated below in italics,
followed by the Company’s response to the comments as well as a summary of the responsive actions taken. We have included page numbers to refer to the location in the Registration Statement submitted herewith where the revised language
addressing a particular comment appears. Capitalized terms used but not defined herein are used herein as defined in the Registration Statement.

Amendment No. 1 to Draft Registration Statement on Form S-1

Prospectus Summary

 Our Current Program Pipeline, page
4

1.
We note your response to our prior comment 4. Please remove C100, C200, C300, E478 and G100 from the pipeline table. We do not object to a discussion of each program below the table, but research and discovery
activities that precede the identification of a product candidate are too remote to be highlighted in the pipeline table.

 Response to Comment No. 1: The Company acknowledges the Staff’s comment and respectfully
advises the Staff that the Company made adjustments on pages 4, 101, and 102 of the Registration Statement to address the Staff’s request by further clarifying that C100, C200, C300, E478 and G100 are early stage development programs.
Specifically, we:

•

Separated and differentiated the relevant graphics to reflect the separation between our preclinical development programs on the one hand and our IND-enabling and clinical stage
programs on the other. To highlight this distinction, we inserted additional lead-in disclosure about the intent of the graphic to appropriately orient the reader. In addition, each graphic has its own sub-header to reinforce the distinction between our preclinical development programs and IND-enabling and clinical-stage product candidates.

•

Revised the header of the graphic to clarify that we are disclosing our current programs across all stages of maturity (instead of a more developed product pipeline), as we believe it is important for investors to
understand the scope of our current and potential product candidates from our discovery programs given the potentially integrated nature of our future offerings to patients.

•

Retained the asterisked information in the graphic from our May 7, 2018 confidential submission to clarify for readers that the graphic covers both our IND-enabling and
clinical stage product candidates as well as high-priority areas of focus of our most advanced discovery efforts where development candidates have not yet been identified.

Business

 Clinical history of MGTA-456

 Initial first-in-human
studies: double blood cord transplant, page 123

2.
We note your statement on page 124 that infusion of MGTA-456 showed a “favorable safety profile” overall. This is a conclusion that is within the FDA’s
authority. Please remove this statement.

 Response to Comment No. 2: The Company acknowledges the Staff’s comment and
respectfully advises the Staff that the Registration Statement has been revised to remove the above-referenced statement.

 Principal Stockholders, page
189

3.
Please revise your disclosure to identify the natural person or persons who have voting and investment control of the shares held by the entities affiliated with Casdin Partners, LP.

Response to Comment No. 3: The Company acknowledges the Staff’s comment and respectfully advises the Staff that it has revised its disclosure
on page 194 of the Registration Statement.

 Should you have any further comments or questions with regard to the foregoing, please contact
the undersigned at 617-570-1447.

Sincerely,

/s/ William D. Collins

William D. Collins

 Enclosures

cc:
Jason Gardner, Magenta Therapeutics, Inc.

Zoran Zdraveski, Magenta Therapeutics, Inc.

Mitchell S. Bloom, Goodwin Procter LLP

Deanna L. Kirkpatrick, Davis Polk & Wardwell LLP

May 16, 2018
Jason Gardner
President and Chief Executive Officer
Magenta Therapeutics, Inc.
50 Hampshire Street
Cambridge, Massachusetts 02139
Re:Magenta Therapeutics, Inc.
Amendment No. 1 to Draft Registration Statement on Form S-1
Submitted May 8, 2018
CIK No. 0001690585
Dear Dr. Gardner:
            We have reviewed your amended 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.
Amendment No. 1 to Draft Registration Statement on Form S-1
Prospectus Summary
Our Current Program Pipeline, page 4
1.We note your response to our prior comment 4. Please remove C100, C200, C300, E478
and G100 from the pipeline table. We do not object to a discussion of each program below
the table, but research and discovery activities that precede the identification of a product
candidate are too remote to be highlighted in the pipeline table.

 FirstName LastNameJason Gardner
 Comapany NameMagenta Therapeutics, Inc.
 May 16, 2018 Page 2
 FirstName LastName
Jason Gardner
Magenta Therapeutics, Inc.
May 16, 2018
Page 2
Business
Clinical history of MGTA-456
Initial first-in-human studies: double blood cord transplant, page 123
2.We note your statement on page 124 that infusion of MGTA-456 showed a "favorable
safety profile" overall.  This is a conclusion that is within the FDA's authority.  Please
remove this statement.
Principal Stockholders, page 189
3.Please revise your disclosure to identify the natural person or persons who have voting
and investment control of the shares held by the entities affiliated with Casdin Partners,
LP.
            You may contact Vanessa Robertson at 202-551-3649 or Sharon Blume at 202-551-
3474 if you have questions regarding comments on the financial statements and related matters.
Please contact Irene Paik at 202-551-6553 or Ada D. Sarmento at 202-551-3798 with any other
questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       William D. Collins - Goodwin Procter

April 24, 2018
Ted White
Chief Executive Officer and President
Magenta Therapeutics, Inc.
200 Garrett Street, Suite S
Charlottesville, Virginia 22902
Re:Magenta Therapeutics, Inc.
Draft Registration Statement on Form S-1
Submitted March 28, 2018
CIK No. 0001690585
Dear Mr. White:
            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 on Form S-1 submitted March 28, 2018
Prospectus Summary, page 1
1.We note your statements here and in the Business section that your product candidates are
first-in-class and that you are developing first-in-class therapeutics.  These statements
imply an expectation of regulatory approval and are inappropriate given the early stage of
development. Please remove or revise these statements.
2.Please disclose here and in the Business section the details of your active IND for MGTA-
456, such as the date of filing, the sponsor, the subject matter and the status. Please

 FirstName LastNameTed White
 Comapany NameMagenta Therapeutics, Inc.
 June 16, 2017 Page 2
 FirstName LastNameTed White
Magenta Therapeutics, Inc.
April 24, 2018
Page 2
include similar disclosure with respect to the EMA or any other drug regulatory
authorities.
Clinical History of MGTA-456, page 1
3.For each of the clinical trials discussed in this section, to the extent that you have not
already done so, please disclose the dates that such trials were conducted, where they
were conducted, the number of participants, the method by which your products were
administered, all serious adverse effects observed, primary and secondary endpoints and
the results of any completed trials.
Our Current Product Pipeline, page 4
4.Please include a column for Phase III in your product pipeline chart on pages 4 and 97.  It
does not appear that you have selected a development candidate yet for your C100, C200,
C300, E478 or G100 programs.  If this is the case, please remove these programs from
your pipeline chart.  If you have not identified a product candidate for these programs, it is
premature to include them in a product pipeline table.
Risk Factors
Clinical development involves a lengthy and expensive process..., page 19
5.We note your disclosure on page 20 that the FDA imposed a partial clinical hold on the
cryopreserved part of the protocol covered by the IND application for MGTA-456 until
Novartis demonstrated comparability between the fresh and cryopreserved product.
Please provide additional information regarding the comparability study that caused the
FDA to remove the partial clinical hold, such as the results Novartis needed to achieve in
order for the FDA to determine that the comparability study was successful.  Please also
revise the Business section to disclose when MGTA-456 was placed on a partial clinical
hold by the FDA and when the partial clinical hold was lifted.
Use of Proceeds, page 70
6.We note that you intend to use the net proceeds from this offering to fund the
development of MGTA-145, including a first-in-human study and proof-of-concept trial.
Please revise your disclosure to clarify whether the net proceeds will be sufficient to
complete the first-in-human study and proof-of-concept trial.  If any material amounts of
other funds are necessary to accomplish these specified purposes, state the amounts and
sources of such other funds needed for each such specified purpose and the sources
thereof.  Refer to Instruction 3 to Item 504 of Regulation S-K.

 FirstName LastNameTed White
 Comapany NameMagenta Therapeutics, Inc.
 June 16, 2017 Page 3
 FirstName LastNameTed White
Magenta Therapeutics, Inc.
April 24, 2018
Page 3
Management's Discussion and Analysis of Financial Condition and Results of Operations
Critical Accounting Policies and Significant Judgments and Estimates
Stock-Based Compensation, page 85
7.Once you have an estimated offering price or range, please explain to us the reasons for
any differences between the recent valuations of your common stock leading up to the
IPO and the estimated offering price. This information will help facilitate our review of
your accounting for equity issuances including stock compensation and beneficial
conversion features.
Emerging Growth Company Status, page 91
8.At this time, you must make your choice whether to opt out of the transition period for
complying with new or revised accounting standards pursuant to Section 107 (b)(1) of the
JOBS Act. Please indicate your choice in your next amendment.
9.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.
Business, page 92
10.Please define "SEM" and "PBMC" at first use.  In addition, where you first provide p-
values, please explain for the benefit of the lay reader the significance of p-values and
clarify the threshold p-value that corresponds to statistical significance.
Hematopoietic Stem and Progenitor Cell Number in Bone Marrow, page 108
11.Please define "PBS" and "ns" as used in this table.
C300 Program, page 112
12.Please define CFU-GM in the chart on page 114 and clarify what each of the colored lines
represents.  It is not clear from the legend in the top right corner.
Alliance with Novartis, page 135
13.We note your disclosure that Novartis is entitled to receive tiered mid-single digit to
"double digit royalties" under the license agreement.  Please revise your disclosure to
narrow the royalty range of the highest tier of royalty to no more than ten percentage
points.

 FirstName LastNameTed White
 Comapany NameMagenta Therapeutics, Inc.
 June 16, 2017 Page 4
 FirstName LastName
Ted White
Magenta Therapeutics, Inc.
April 24, 2018
Page 4
Harvard University License Agreement, page 136
14.Please revise to disclose to which of your product candidates or programs the license from
Harvard University relates.

Narrative to Summary Compensation Table, page 168
15.We note your disclosure that you have entered into offer letters with each of your named
executive officers.  Please file these offer letters as exhibits or tell us why you believe that
you are not required to do so pursuant to Item 601(b)(10) of Regulation S-K.
General
16.Please provide us proofs of all graphics, visual, or photographic information you will
provide in the printed prospectus prior to its use, for example in a preliminary prospectus.
Please note that we may have comments regarding this material.
            You may contact Vanessa Robertson at 202-551-3649 or Sharon Blume at 202-551-3474
if you have questions regarding comments on the financial statements and related
matters.  Please contact Irene Paik at 202-551-6553 or Ada D. Sarmento at 202-551-3798 with
any other questions.
Division of Corporation Finance
Office of Healthcare & Insurance
cc: William D. Collins - Goodwin Procter