SecProbe.io

<DOCUMENT>
<TYPE>TEXT-EXTRACT
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<FILENAME>filename2.txt
<TEXT>
 September 16, 2025

Bruce Steel
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa
Suite 105
La Jolla, CA 92037

 Re: Equillium, Inc.
 Form 10-K for the Year Ended December 31, 2024
 File No. 001-38692
Dear Bruce Steel:

 We have completed our review of your filing. 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.

 Sincerely,

 Division of Corporation
Finance
 Office of Life Sciences
</TEXT>
</DOCUMENT>

CORRESP
 1
 filename1.htm

 CORRESP

 E QUILLIUM , I NC .
 2223 Avenida de la Playa, Suite 105
 La Jolla, California 92037 September 16,
2025 Securities and Exchange Commission Division of
Corporation Finance Office of Life Sciences 100 F. Street
N.E. Washington, D.C. 20549-3010 Attention: Jason Drory

 Re:
 Equillium, Inc.
 Registration Statement on Form S-3
 Filed: September 9, 2025
 File No. 333-290138
 Ladies and Gentlemen: Equillium, Inc. (the
“ Registrant ”) hereby requests that the U.S. Securities and Exchange Commission (the “ Commission ”) take appropriate action to cause the above-referenced Registration Statement on Form S-3 to become effective on September 18, 2025, at 4:00 p.m., Eastern Time, or as soon thereafter as is practicable or at such later time as the Registrant may orally request via telephone call to the staff of
the Commission. The Registrant hereby authorizes Dylan Kornbluth of Cooley LLP, counsel to the Registrant, to make such request on its behalf. Once the
Registration Statement has been declared effective, please orally confirm that event with Dylan Kornbluth of Cooley LLP at (858) 550-6173.
 [ Signature Page Follows ]

 Very truly yours,

 EQUILLIUM, INC.

 By:

 /s/ Bruce D. Steel

 Name: Bruce D. Steel

 Title: Chief Executive Officer

 cc:
 Penny Tom, Equillium, Inc.
 Thomas A. Coll, Esq., Cooley LLP
 Dylan S. Kornbluth, Esq., Cooley LLP
 [C OMPANY
S IGNATURE P AGE TO A CCELERATION R EQUEST ]

CORRESP
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 filename1.htm

 CORRESP

 September 11, 2025
 VIA EDGAR United States Securities and Exchange
Commission Division of Corporation Finance Office of Life
Sciences 100 F Street, N.E. Washington, D.C. 20549-3628
 Attention: Christine Torney
  Kevin Vaughn

 Re:

 Equillium, Inc.

 Form 10-K for the Year Ended December 31, 2024
 File No. 001-38692
 Dear Christine Torney and Kevin Vaughn:
 We are writing in response to the comment received from the staff (the “ Staff ”) of the Securities and Exchange Commission
(the “ Commission ”) by letter dated September 8, 2025 with respect to the above-referenced filing of Equillium, Inc. (the “ Company ”). For your convenience, we have repeated the
Staff’s comment before the Company’s response below. Management’s Discussion and Analysis of Financial Condition and Results of
Operations Results of Operations, page 93

 1.
 To the extent you track any of your costs by product candidate and indication, please provide disclosures to
be presented in future filings to separately disclose your research and development expenses by product candidate and indication. To the extent you are not able to quantify any such costs by product candidate or indication, disclose that fact as
well as the reasons why not, and provide separate quantification for unallocated expenses by their natural expense categories or type. The total of quantifiable expenses should reconcile to the amount of research and development expenses presented
on the face of your Statement of Operations. We note from your disclosures in the Notes to Consolidated Financial Statement that you are able to separately classify accrued expenses for Biocon clinical development related to ulcerative colitis
study. We also note from disclosures in the Comparison of the Years Ended December 31, 2024 and 2023 in Results of Operations that you are able to distinguish preclinical and clinical research and development expenses .
 Response : The Company respectfully acknowledges the Staff’s comment and advises that the Company is currently only
advancing the development of a single product candidate, EQ504, for the treatment of ulcerative colitis (see disclosure in the Company’s Form 10-Q for the quarter ended June 30, 2025 on page 17).
While the Company has additional preclinical and clinical stage assets, the Company currently has no intentions of further developing those assets (see disclosure in the Company’s Form 10-Q for the
quarter ended June 30, 2025 on page 18). Since there is currently only one product candidate in development for a single indication,
the Company respectfully submits that a breakdown of the research and development expenses along the lines requested in the Staff’s comment is not practicable. Notwithstanding the foregoing, commencing with its Quarterly Report on Form 10-Q for the quarter ending September 30, 2025, the Company will enhance its disclosure

U.S. Securities and Exchange Commission Division of Corporation Finance
 Office of Life Sciences September 11, 2025
 Page 2

in the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations - Results of Operations - Research and Development Expenses”
to provide (i) a quantitative breakdown of the research and development expense components by type and nature of expense and (ii) a quantification for unallocated expenses by their natural expense categories or type.
 If the Company commences development of another product candidate or pursues development of an additional indication for EQ504, the Company
intends to separately disclose research and development expenses by product candidate or indication. To the extent the Company is not able to quantify any such costs by product candidate or indication, the Company will disclose that fact as well as
the reasons why not, and provide separate quantification for unallocated expenses by their natural expense categories or type. *****
 The Company respectfully requests the Staff’s assistance in completing the review of the Company’s response as soon as possible. Please
advise us if we can provide any further information or assistance to facilitate your review. Please direct any further comments or questions regarding this response letter to me at (858) 412-5302.

 Sincerely,

 /s/ Bruce D. Steel

 Bruce D. Steel, CFA

 Chief Executive Officer

 Equillium, Inc.

 cc:
 Penny Tom, Equillium, Inc.
 Thomas A. Coll, Esq., Cooley LLP
 Dylan S. Kornbluth, Esq., Cooley LLP

<DOCUMENT>
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<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 September 11, 2025

Bruce Steel
President and Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 105
La Jolla, CA 92037

 Re: Equillium, Inc.
 Registration Statement on Form S-3
 Filed September 9, 2025
 File No. 333-290138
Dear Bruce Steel:

 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 Jason Drory at 202-551-8342 with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: Dylan Kornbluth
</TEXT>
</DOCUMENT>

<DOCUMENT>
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<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 September 8, 2025

Bruce Steel
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa
Suite 105
La Jolla, CA 92037

 Re: Equillium, Inc.
 Form 10-K for the Year Ended December 31, 2024
 File No. 001-38692
Dear Bruce Steel:

 We have limited our review of your filing to the financial statements
and related
disclosures and have the following comment.

 Please respond to this letter within ten business days by providing the
requested
information or advise us as soon as possible when you will respond. If you do
not believe
this comment applies to your facts and circumstances, please tell us why in
your response.

 After reviewing your response to this letter, we may have additional
comments.

Management's Discussion and Analysis of Financial Condition and Results of
Operations
Results of Operations, page 93

1. To the extent you track any of your costs by product candidate and
indication, please
 provide disclosures to be presented in future filings to separately
disclose your
 research and development expenses by product candidate and indication.
To the extent
 you are not able to quantify any such costs by product candidate or
indication,
 disclose that fact as well as the reasons why not, and provide separate
quantification
 for unallocated expenses by their natural expense categories or type.
The total of
 quantifiable expenses should reconcile to the amount of research and
development
 expenses presented on the face of your Statement of Operations. We note
from your
 disclosures in the Notes to Consolidated Financial Statement that you
are able to
 separately classify accrued expenses for Biocon clinical development
related to
 ulcerative colitis study. We also note from disclosures in the
Comparison of the Years
 Ended December 31, 2024 and 2023 in Results of Operations that you are
able to
 distinguish preclinical and clinical research and development expenses.
 September 8, 2025
Page 2

 In closing, 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 Christine Torney at 202-551-3652 or Kevin Vaughn at
202-551-3494
with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
</TEXT>
</DOCUMENT>

CORRESP
1
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CORRESP

 Equillium, Inc.

2223 Avenida de la Playa Suite 105

La Jolla, CA 92037

 January 13, 2023

VIA EDGAR

 United States Securities and Exchange Commission

Division of Corporation Finance

 100 F Street, N.E.

Washington, D.C. 20549

 Attn:    Alan
Campbell

Re:
 Equillium, Inc.

Registration Statement on Form S-3

Filed: January 6, 2023

File No. 333-269153

 Ladies and
Gentlemen:

 Pursuant to Rule 461 under the Securities Act of 1933, as amended, Equillium, Inc. (the “Registrant”) hereby requests
that the Securities and Exchange Commission (the “Commission”) take appropriate action to cause the above-referenced Registration Statement on Form S-3 to become effective at 4:30 p.m.
Eastern Time on Wednesday, January 18, 2023, or as soon thereafter as is practicable.

 In connection with this request, the Registrant hereby
acknowledges that:

•

 should the Commission or the staff of the Commission (the “Staff”), acting pursuant to
delegated authority, declare the filing effective, it does not foreclose the Commission from taking any action with respect to the filing;

•

 the action of the Commission or the Staff, acting pursuant to delegated authority, in declaring the filing
effective, does not relieve the Registrant from its full responsibility for the adequacy and accuracy of the disclosure in the filing; and

•

 the Registrant 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 Wade W. Andrews of Cooley LLP at (858) 550-6042.

 Sincerely,

EQUILLIUM, INC.

By:

 /s/ Bruce D. Steel

Bruce D. Steel

President and Chief Executive Officer

United States securities and exchange commission logo
January 12, 2023
Bruce D. Steel
President and Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 105
La Jolla, California 92037
Re:Equillium, Inc.
Registration Statement on Form S-3
Filed January 6, 2023
File No. 333-269153
Dear Bruce D. Steel:
            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 Alan Campbell at 202-551-4224 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Wade W. Andrews, Esq.

CORRESP
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    Equillium, Inc.

    2223 Avenida de la Playa, Suite 105

    La Jolla, California 92037

    November 9, 2022

    Via Edgar

    United States Securities and Exchange Commission

    Division of Corporation Finance

    100 F Street, N.E.

    Washington, D.C. 20549

    Attn:        Tim Buchmiller

    Re:          Equillium, Inc.

    Registration Statement on Form S-4 (File No. 333-268024)

    Dear Mr. Austin:

    This letter is sent on behalf of Equillium, Inc. (the “Company”) in connection with the above-referenced Registration Statement on Form S-4 (the “Registration Statement”) filed with the Securities and
      Exchange Commission (the “Commission”) by the Company pursuant to the Securities Act of 1933, as amended (the “Securities Act”). Pursuant to Rule 461 promulgated under the Securities Act, the Company hereby requests that the effective
      date of the Registration Statement be accelerated to 4:00 p.m., Eastern Time, on November 10, 2022, or as soon thereafter as practicable.

    Please contact Tom Coll or Dylan Kornbluth, each of Cooley LLP, at (858) 550-6013 or (858) 550-6173, respectively, with any questions you may have concerning this request. In addition, please notify Mr. Coll or Mr.
      Kornbluth when the request for acceleration has been granted.

    Sincerely,

            Equillium, Inc.

            By:

            /s/ Bruce D. Steel

            Name:

            Bruce D. Steel

            Title:

            Chief Executive Officer

    cc:          Tom Coll, Cooley LLP

    Rama Padamanabhan, Cooley LLP

    Dylan Kornbluth, Cooley LLP

    Robert Ishii, Wilson Sonsini Goodrich & Rosati PC

    Miranda Biven, Wilson Sonsini Goodrich & Rosati PC

    Megan J. Baier, Wilson Sonsini Goodrich & Rosati PC

    Catherine Riley Tzipori, Wilson Sonsini Goodrich & Rosati PC

    David G. Sharon, Wilson Sonsini Goodrich & Rosati PC

    Preston Klassen, Metacrine, Inc.

United States securities and exchange commission logo
November 1, 2022
Bruce D. Steel
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 105
La Jolla, California 92037
Re:Equillium, Inc.
Registration Statement on Form S-4
Filed October 27, 2022
File No. 333-268024
Dear Bruce D. Steel:
            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:       Tom Coll, Esq.

CORRESP
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eq-corresp.htm

April 3, 2020

United States Securities and Exchange Commission

Via EDGAR

Division of Corporation Finance

100 F Street, N.E.

Mail Stop 4546

Washington, D.C. 20549

Attn:

Mr. William Mastrianna

Re:

Equillium, Inc.

Registration Statement on Form S-1

File No. 333-237491

Acceleration Request

Requested Date:Tuesday, April 7, 2020

Requested Time:4:30 P.M. Eastern Time

Ladies and Gentlemen:

In accordance with Rule 461 under the Securities Act of 1933, as amended, the undersigned registrant (the “Registrant”) hereby requests that the Securities and Exchange Commission (the “Commission”) take appropriate action to cause the above-referenced Registration Statement on Form S-1 (the “Registration Statement”) to become effective on April 7, 2020, at 4:30 p.m., Eastern Time, or as soon thereafter as is practicable, or at such later time as the Registrant may orally request via telephone call to the staff (the “Staff”). This request for acceleration is subject, however, to your receiving a telephone call prior to such time from our legal counsel, Cooley LLP, confirming this request. The Registrant hereby authorizes each of Wade Andrews and Timothy Hance of Cooley LLP, counsel to the Registrant, to make such request on its behalf.

Once the Registration Statement has been declared effective, please orally confirm that event with Wade Andrews of Cooley LLP, counsel to the Registrant, at (858) 550-6042, or in his absence, Timothy Hance at (858) 550-6145.

In connection with this request, the Registrant acknowledges that:

•

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

•

the Registrant 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.

223263638 v2

Very truly yours,

Equillium, Inc.

By: /s/ Bruce D. Steel

Bruce D. Steel

Chief Executive Officer

223263638 v2

April 2, 2020
Bruce Steel
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 105
La Jolla, CA 92037
Re:Equillium, Inc.
Registration Statement on Form S-1
Filed March 30, 2020
File No. 333-237491
Dear Mr. Steel:
            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 William Mastrianna, Attorney-Adviser, at (202) 551-3778 with any
questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Wade Andrews

CORRESP
1
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CORRESP

 Equillium, Inc.

2223 Avenida de la Playa

 Suite 105

 La Jolla, CA 92037

 (858) 412-5302

 November 21, 2019

VIA EDGAR

United States Securities and Exchange Commission

Division of Corporation Finance

100 F Street, N.E.

 Washington,
D.C. 20549

 Attn:

 Irene Paik

 Re:

 Equillium, Inc.

 Registration Statement on Form S-3

 Filed: November 13, 2019

 File No. 333-234683

Ladies and Gentlemen:

 Pursuant
to Rule 461 under the Securities Act of 1933, as amended, Equillium, Inc. (the “Registrant”) hereby requests that the Securities and Exchange Commission (the “Commission”) take appropriate action to
cause the above-referenced Registration Statement on Form S-3 to become effective at 4:30 p.m. Eastern Time on Monday, November 25, 2019, or as soon thereafter as is practicable.

In connection with this request, the Registrant hereby acknowledges that:

 •

 should the Commission or the staff of the Commission (the “Staff”), acting pursuant to
delegated authority, declare the filing effective, it does not foreclose the Commission from taking any action with respect to the filing;

 •

 the action of the Commission or the Staff, acting pursuant to delegated authority, in declaring the filing
effective, does not relieve the Registrant from its full responsibility for the adequacy and accuracy of the disclosure in the filing; and

 •

 the Registrant 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 Wade W. Andrews of Cooley LLP at (858) 550-6042.

 Sincerely,

EQUILLIUM, INC.

By: /s/ Jason A.
Keyes

  Jason A. Keyes

  Chief Financial Officer

November 20, 2019
Daniel M. Bradbury
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 105
La Jolla, California 92037
Re:Equillium, Inc.
Registration Statement on Form S-3
Filed November 13, 2019
File No. 333-234683
Dear Mr. Bradbury:
            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 Irene Paik at 202-551-6553 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Wade Andrews - Cooley LLP

CORRESP
1
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CORRESP

 October 9, 2018

 United States Securities and Exchange Commission

 VIA EDGAR

 Division of
Corporation Finance

 100 F Street, N.E.

 Mail
Stop 4720

 Washington, D.C. 20549

Attn:
 Mr. Donald E. Field

Re:
 Equillium, Inc.

Registration Statement on Form S-1

File No. 333-227387

Acceleration Request

Requested Date:          Thursday, October 11, 2018

Requested Time:         4:45 P.M. Eastern Time

Ladies and Gentlemen:

 In
accordance with Rule 461 under the Securities Act of 1933, as amended, the undersigned registrant (the “Registrant”) hereby requests that the Securities and Exchange Commission (the “Commission”) take
appropriate action to cause the above-referenced Registration Statement on Form S-1 (the “Registration Statement”) to become effective on October 11, 2018, at 4:45 p.m., Eastern
Time, or as soon thereafter as is practicable, or at such later time as the Registrant may orally request via telephone call to the staff (the “Staff”). This request for acceleration is subject, however, to your receiving a
telephone call prior to such time from our legal counsel, Cooley LLP, confirming this request. The Registrant hereby authorizes each of Karen E. Anderson and Wade Andrews of Cooley LLP, counsel to the Registrant, to make such request on its behalf.

 Once the Registration Statement has been declared effective, please orally confirm that event with Karen E. Anderson of
Cooley LLP, counsel to the Registrant, at (858) 550-6088, or in her absence, Wade Andrews at (858) 550-6042.

In connection with this request, the Registrant acknowledges that:

•

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

•

 the Registrant 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.

 Very truly yours,

 Equillium, Inc.

 By:

 /s/ Daniel M. Bradbury

 Daniel M. Bradbury

 Chief Executive Officer

CORRESP
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CORRESP

 October 9, 2018

VIA EDGAR

 U.S. Securities and Exchange
Commission

 Division of Corporation Finance

 100 F Street,
N.E.

 Mail Stop 4720

 Washington, D.C. 20549-3628

Attn:
 Donald E. Field

Re:
 Equillium, Inc. (the “Company”) – Request for Acceleration

Registration Statement on Form S-1 (File
No. 333-227387)

 Ladies and Gentlemen:

In accordance with Rule 461 under the Securities Act of 1933, as amended (the “Act”), and as representatives of the several underwriters of the
Company’s proposed public offering of common shares, we hereby join the Company’s request for acceleration of the above-referenced Registration Statement, as amended, requesting effectiveness for 4:45 p.m. Eastern Time on October 11,
2018, or as soon thereafter as is practicable.

 Pursuant to Rule 460 of the Act, we wish to advise you that we have distributed approximately 2,571 copies
of the Company’s Preliminary Prospectus dated October 2, 2018 through the date hereof to underwriters, dealers, institutions and others.

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

 [Signature Page Follows]

 Very truly yours,

Jefferies LLC

Leerink Partners LLC

Stifel, Nicolaus & Company, Incorporated

As representatives of the several Underwriters

By: Jefferies LLC

By:

 /s/ Michael Brinkman

Name:

Michael Brinkman

Title:

Managing Director

By: Leerink Partners LLC

By:

 /s/ Stuart Nayman

Name:

Stuart Nayman

Title:

Managing Director

By: Stifel, Nicolaus & Company, Incorporated

By:

 /s/ Nathan Thompson

Name:

Nathan Thompson

Title:

Director

 [Signature Page to Acceleration Request Letter]

CORRESP
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CORRESP

 Karen E. Anderson

+1 858 550 6088

kanderson@cooley.com

Via EDGAR

 October 2, 2018

 United States Securities and
Exchange Commission

 Division of Corporation Finance

 Office of Healthcare and
Insurance

 Mail Stop 4720

 100 F Street, N.E.

Washington, D.C. 20549

 Attn: Donald E. Field

Re:
 Equillium, Inc.

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

Filed September 28, 2018

File No. 333-227387

Dear Mr. Field:

 Enclosed on behalf of our
client, Equillium, Inc., a Delaware corporation (the “Company”), is an amendment (“Amendment No. 2”) to the Company’s registration statement on Form S-1 originally filed with the Securities and Exchange Commission (the “Commission”) on September 17, 2018, as amended by Amendment No. 1 filed with the Commission on
September 28, 2018 (the “Amended Registration Statement”). The copy of Amendment No. 2 that is enclosed with the paper copy of this letter is marked to show changes from the Amended Registration Statement.

Amendment No. 2 is being submitted in response to comments received from the staff of the Commission (the “Staff”) by
letter dated September 28, 2018 with respect to the Amended Registration Statement (the “Comment Letter”). The numbering of the paragraph below corresponds to the numbering in the Comment Letter, the text of which we
have incorporated into this response letter for convenience. Except where otherwise indicated, page references in the text of the responses below correspond to the page numbers of Amendment No. 2.

Staff Comment and Company Response

 Description of Capital Stock

Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws, page 144

1.
 We note that your amended and restated certificate of incorporation identifies U.S. federal district courts as the
exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act. Please revise your prospectus to disclose this provision, and to address any uncertainty about the enforceability of such provision.

 Response: The Company has revised the disclosures on pages 56 and 144 of Amendment No. 2 to clarify that the
Company’s amended and restated certificate of incorporation, to be effective upon completion of the Company’s initial public offering, includes a forum selection provision that identifies U.S. federal district courts as the exclusive forum
for the resolution of any complaint asserting a cause of action arising under the Securities Act of 1933, as amended. The Company has also clarified that the enforceability of similar choice of forum provisions in other companies’ certificates
of incorporation has been challenged in legal proceedings, and it is possible that a court could find these types of provisions to be inapplicable or unenforceable.

Cooley LLP    4401 Eastgate Mall    San Diego, CA    92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

 United States Securities and Exchange

Commission

October 2, 2018

Page Two

 *        *        *

The Company respectfully requests the Staff’s assistance in completing the review of Amendment No. 2 as soon as possible. Please advise us if
we can provide any further information or assistance to facilitate your review. Please direct any further comments or questions regarding Amendment No. 2 or this response letter to me at (858) 550-6088.

 Sincerely,

 Cooley LLP

/s/ Karen E. Anderson

 Karen E. Anderson

 cc:

 Daniel M. Bradbury, Equillium, Inc.

 Bruce Steel, Equillium, Inc.

 Cheston J. Larson, Latham & Watkins LLP

 Matthew T. Bush, Latham & Watkins LLP

 Cooley LLP    4401 Eastgate Mall    San Diego, CA    92121

 t: (858) 550-6000 f: (858) 550-6420 cooley.com

September 28, 2018
Daniel M. Bradbury
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 108
La Jolla, CA 92037
Re:Equillium, Inc.
Amendment No. 1 to Registration Statement on Form S-1
Filed September 28, 2018
File No. 333-227387
Dear Mr. Bradbury:
            We have reviewed your amended registration statement and have the following
comment.  In our comment, 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 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.
Amendment No. 1 to Registration Statement on Form S-1
Description of Capital Stock
Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws, page
144
1.We note that your amended and restated certificate of incorporation identifies U.S. federal
district courts as the exclusive forum for the resolution of any complaint asserting a cause
of action arising under the Securities Act.  Please revise your prospectus to disclose this
provision, and to address any uncertainty about the enforceability of such provision.

 FirstName LastNameDaniel M. Bradbury
 Comapany NameEquillium, Inc.
 September 28, 2018 Page 2
 FirstName LastName
Daniel M. Bradbury
Equillium, Inc.
September 28, 2018
Page 2
            You may contact Bonnie Baynes at 202-551-4924 or Lisa Vanjoske at 202-551-3614 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Donald Field at 202-551-3680 or Justin Dobbie, Legal Branch Chief, at 202-551-3469
with any other questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance

CORRESP
1
filename1.htm

CORRESP

 Karen E. Anderson

 +1 858 550
6088

 kanderson@cooley.com

Via EDGAR

 September 28, 2018

 United States Securities
and Exchange Commission

 Division of Corporation Finance

 Office of Healthcare
and Insurance

 Mail Stop 4720

 100 F Street, N.E.

Washington, D.C. 20549

 Attn: Donald E. Field

Re:
 Equillium, Inc.

Registration Statement on Form S-1

Filed September 17, 2018

File No. 333-227387

Dear Mr. Field:

 Enclosed on behalf of our
client, Equillium, Inc., a Delaware corporation (the “Company”), is an amendment (“Amendment No. 1”) to the Company’s registration statement on Form S-1 originally filed with the Securities and Exchange Commission (the “Commission”) on September 17, 2018 (the “Original Registration Statement”). The copy of
Amendment No. 1 that is enclosed with the paper copy of this letter is marked to show changes from the Original Registration Statement.

Amendment No. 1 is being submitted in response to comments received from the staff of the Commission (the “Staff”) by
letter dated September 26, 2018 with respect to the Original Registration Statement (the “Comment Letter”). The numbering of the paragraphs below corresponds to the numbering in the Comment Letter, the text of which we
have incorporated into this response letter for convenience. Except where otherwise indicated, page references in the text of the responses below correspond to the page numbers of Amendment No. 1.

Staff Comments and Company Responses

 Government Regulation and Product
Approval, page 101

1.
 We note the risk factor added to the bottom of page 11. Please revise this section to discuss in detail U.S. export
control laws and regulations which may be applicable to the company due to EQ001 being derived from Cuban-origin intellectual property. Please discuss in enough detail so that investors can clearly understand the applicable laws and regulations and
the company’s current status with and expectations for obtaining interpretive guidance from OFAC or the required licenses necessary to deal in, or otherwise commercialize, EQ001.

Response: The Company has revised the disclosure on pages 3, 12 and 114 of Amendment No. 1.

Cooley LLP    4401 Eastgate Mall    San Diego, CA    92121

t: (858) 550-6000    f: (858)
550-6420    cooley.com

 United States Securities and Exchange

Commission

 September 28, 2018

Page Two

 Description of Capital Stock

Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws, page 142

2.
 We note that your forum selection provisions in your certificate of incorporation and bylaws identify the Court of
Chancery in the State of Delaware as the exclusive forum for certain litigation, including any “derivative action.” Please disclose whether these provisions apply to actions arising under the federal securities laws. In that regard, we
note that Section 27 of the Exchange Act creates exclusive federal jurisdiction over all suits brought to enforce any duty or liability created by the Exchange Act or the rules and regulations thereunder. If these provisions do
not apply to actions arising under the federal securities laws, please also ensure that the exclusive forum provision in each of your governing documents states this clearly.

Response: The Company has revised the disclosure on pages 56 and 144 of Amendment No. 1 and has revised its amended and restated certificate
of incorporation and amended and restated bylaws to be effective upon completion of the Company’s initial public offering to clarify that the forum selection provision that identifies the Court of Chancery of the State of Delaware as the
exclusive forum for certain litigation, including any “derivative action”, would not apply to suits to enforce a duty or liability created by the Securities Exchange Act of 1934, as amended, or any other claim for which the federal courts
have exclusive jurisdiction.

*            *             *

The Company respectfully requests the Staff’s assistance in completing the review of Amendment No. 1 as soon as possible. Please advise us if
we can provide any further information or assistance to facilitate your review. Please direct any further comments or questions regarding Amendment No. 1 or this response letter to me at (858) 550-6088.

 Sincerely,

 Cooley LLP

/s/ Karen E. Anderson

 Karen E. Anderson

 cc:

 Daniel M. Bradbury, Equillium, Inc.

 Bruce Steel, Equillium, Inc.

 Cheston J. Larson, Latham & Watkins LLP

 Matthew T. Bush, Latham & Watkins LLP

 Cooley LLP    4401 Eastgate Mall    San Diego, CA    92121

 t: (858) 550-6000    f: (858)
550-6420    cooley.com

September 26, 2018
Daniel M. Bradbury
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 108
La Jolla, CA 92037
Re:Equillium, Inc.
Registration Statement on Form S-1
Filed September 17, 2018
File No. 333-227387
Dear Mr. Bradbury:
            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-1
Government Regulation and Product Approval, page 101
1.We note the risk factor added to the bottom of page 11.  Please revise this section to
discuss in detail U.S. export control laws and regulations which may be applicable to the
company due to EQ001 being derived from Cuban-origin intellectual property.  Please
discuss in enough detail so that investors can clearly understand the applicable laws and
regulations and the company's current status with and expectations for obtaining
interpretive guidance from OFAC or the required licenses necessary to deal in, or
otherwise commercialize, EQ001.

 FirstName LastNameDaniel M. Bradbury
 Comapany NameEquillium, Inc.
 September 26, 2018 Page 2
 FirstName LastName
Daniel M. Bradbury
Equillium, Inc.
September 26, 2018
Page 2
Description of Capital Stock
Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws, page
142
2.We note that your forum selection provisions in your certificate of incorporation and
bylaws identify the Court of Chancery in the State of Delaware as the exclusive forum for
certain litigation, including any “derivative action.”  Please disclose whether these
provisions apply to actions arising under the federal securities laws.  In that regard, we
note that Section 27 of the Exchange Act creates exclusive federal jurisdiction over all
suits brought to enforce any duty or liability created by the Exchange Act or the rules and
regulations thereunder.  If these provisions do not apply to actions arising under the
federal securities laws, please also ensure that the exclusive forum provision in each of
your governing documents states this clearly.
            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 contact Bonnie Baynes at 202-551-4924 or Lisa Vanjoske at 202-551-3614 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Donald Field at 202-551-3680 or Justin Dobbie, Legal Branch Chief, at 202-551-3469
with any other questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance

CORRESP
1
filename1.htm

CORRESP

 *FOIA Confidential Treatment Request*

Confidential Treatment Requested by

Equillium, Inc. in connection

with its Registration Statement on Form S-1

filed September 17, 2018

 Karen E. Anderson

 T: +1 858 550-6088

 kanderson@cooley.com

VIA EDGAR AND FEDEX

 September 21, 2018

United States Securities and Exchange Commission

 Division of
Corporation Finance

 Office of Healthcare and Insurance

 Mail
Stop 4720

 100 F Street, N.E.

 Washington, D.C. 20549

Attn: Donald E. Field

 Re:    Equillium, Inc.

 Registration Statement on Form S-1

Filed September 17, 2018

File No. 333-227387

Dear Mr. Field:

 On behalf of our client,
Equillium, Inc. (the “Company”), we are submitting this letter in response to comments received from the staff (the “Staff”) of the Securities and Exchange Commission (the
“Commission”) by letter dated August 28, 2018 (the “Comment Letter”), relating to the Company’s confidential draft registration statement on Form S-1
submitted to the Commission on August 3, 2018, which was subsequently amended on August 30, 2018 and filed with the Commission on September 17, 2018 (as amended, the “Registration Statement”). In this letter,
we are responding only to comment number 8 in the Comment Letter, the text of which we have incorporated into this response letter for convenience.

Confidential Treatment Request

 Due to
the commercially sensitive nature of information contained herein, the Company hereby requests, pursuant to 17 C.F.R. § 200.83, that certain portions of this letter be maintained in confidence, not be made part of any public record and not be
disclosed to any person as they contain confidential information. The Company has filed a separate copy of this letter, marked to show the portions redacted from the version filed via EDGAR and for which the Company is requesting confidential
treatment. In accordance with 17 C.F.R. § 200.83(d)(1), if any person (including any governmental employee who is not an employee of the Commission) should request access to or an opportunity to inspect this letter, we request that we be
immediately notified of any such request, be furnished with a copy of all written materials pertaining to such request (including, but not limited to, the request itself) and be given at least ten business days advance notice of any intended release
so that the Company may, if deemed necessary or appropriate, pursue any remedies available to it. In such an event, we request that you telephone the undersigned rather than rely upon the U.S. mail for such notice. The address and telephone number
for Karen E. Anderson, the responsible representative, is c/o Cooley LLP, 4401 Eastgate Mall, San Diego, California 92121-1909, telephone number (858) 550-6088.

 4401 EASTGATE MALL, SAN
DIEGO, CA 92121 T: (858) 550-6000 F: (858) 550-6420 WWW.COOLEY.COM

 September 21, 2018

  Page
 2
 of 7

CONFIDENTIAL

 Staff Comment and Company Response

Critical Accounting Policies and Significant Judgement and Estimates

Stock-Based Compensation Expense, page 75

8.
 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 initial public offer and the estimated offering price. This information will help facilitate our review of your accounting for equity issuances including stock
compensation.

 Response:

Historically, the fair value of the common stock underlying the Company’s stock-based awards has been determined on each grant date by the
Company’s board of directors (the “Board”), with input from management. All options to purchase shares of the Company’s common stock were intended to be granted with an exercise price per share no less than the fair value per
share of the Company’s common stock underlying those options on the date of grant, determined in good faith and based on the information known to the Board on the date of grant. In the absence of a public trading market for the Company’s
common stock, on each grant date, the Board considered various objective and subjective factors as set forth on page 75 of the Registration Statement, along with input from management, to determine the fair value of the Company’s common
stock.

 In addition to the above factors, as part of its assessment of the fair value of the Company’s common stock for purposes of
making stock option grants, the Board most recently also considered and relied upon appraisals of the fair value of the Company’s common stock as of March 31, 2018, July 31, 2018 and September 12, 2018 from independent
third-party valuation specialists using methodologies, approaches and assumptions consistent with the American Institute of Certified Public Accountants’ Audit and Accounting Practice Aid Series: Valuation of Privately-Held-Company Equity
Securities Issued as Compensation (the “Practice Aid”).

 4401 EASTGATE MALL, SAN
DIEGO, CA 92121 T: (858) 550-6000 F: (858) 550-6420 WWW.COOLEY.COM

 September 21, 2018

  Page
 3
 of 7

CONFIDENTIAL

 The following is a summary of recent valuations:

March 31, 2018 Valuation and June 2018 Option Grants

In accordance with the Practice Aid, the March 31, 2018 valuation used an option pricing method (“OPM”). The
enterprise value was determined using a precedent transaction “backsolve” method based upon the Company’s pro forma Series A financing1, which was based on the Company’s
anticipated valuation as determined by management in good faith after a review of all relevant facts and circumstances and the Company’s financing target and terms. A discount for lack of marketability (“DLOM”) of 40%
was applied to the OPM utilizing three scenarios that assumed (1) financing in late 2018, (2) financing in early 2019 or (3) dissolution in early 2019, weighted at 35%, 35% and 30%, respectively. The resulting fair value of the
Company’s common stock was $0.35 per share.

 On June 6, 2018, the Board granted options to purchase an aggregate of 43,478
shares of common stock. On such grant date, the Board determined that the fair value of the Company’s common stock was $0.35 per share in connection with the grants of such stock options, in consideration of the valuation analysis as of
March 31, 2018 and the other objective and subjective factors described in the Registration Statement. The Board determined that, as of June 6, 2018, no significant business or market developments had occurred since the valuation date of
March 31, 2018.

 June 30, 2018 Valuation

In accordance with the Practice Aid, the June 30, 2018 valuation used an OPM. The enterprise value was determined using a precedent
transaction “backsolve” method based again upon the Company’s pro forma Series A financing. A DLOM of 40% was applied to the OPM and three scenarios were utilized that assumed (1) financing in late 2018, (2) financing in early
2019 or (3) dissolution in early 2019, weighted at 35%, 35% and 30%, respectively. The resulting fair value of the Company’s common stock was $0.41 per share. All assumptions utilized in the March 31, 2018 and June 30, 2018
valuations were the same as no significant business or market developments had occurred. The resulting increase was due primarily to the passage of time between the valuation dates.

The Company did not grant any stock options during the period between June 6, 2018 and August 15, 2018.

Value Creating Events/Actions Post June 30, 2018

Prior to June 30, 2018, the Company had not taken steps regarding the possibility of an initial public offering
(“IPO”).    In addition, prior to such time, the Company’s sole financing sources were the founders and friends and family of the Company’s management team who invested in the Company through
convertible notes. As of June 30, 2018, the Company was comprised of just seven employees, had not received authorization from the U.S. Food and Drug Administration (the “FDA”) that it could commence clinical development
of its only product candidate, EQ001 (itolizumab), and faced an uncertain future with respect to being able to raise the necessary capital to fund its operations and continue as a going concern.

1
 Note: The Company never actually completed a Series A Financing or any financing transaction in which an
independent third party investor provided validation of the valuation of the Company’s capital stock. The planned IPO will be the first such valuation-validating event.

 4401 EASTGATE MALL, SAN
DIEGO, CA 92121 T: (858) 550-6000 F: (858) 550-6420 WWW.COOLEY.COM

 September 21, 2018

  Page
 4
 of 7

CONFIDENTIAL

 Between June 30, 2018 and July 31, 2018, a number of developments occurred that
significantly increased the Company’s value and made it more likely that the Company could consummate a private financing or the IPO, including:

(i)
 The Company engaged investment banks for purposes of serving as underwriters for an IPO.

(ii)
 On July 10, 2018, the Company and the underwriters held an organizational meeting for the planned IPO.

(iii)
 On July 27, 2018, the Company received a “study may proceed” letter from the FDA with respect to
the Company’s Investigational New Drug application (“IND”) for its only product candidate, EQ001, for the treatment of acute graft-versus-host disease. As a result of such letter, the Company went from having, with
respect to its only product candidate EQ001, a preclinical-stage asset with limited IND enabling data to having an asset that was able to proceed into human clinical trials in the United States, thereby
shortening the potential development of EQ001 by 12 to 18 months. Further, having authority from the FDA to commence human clinical trials in the United States, meant that the Company would not have to conduct the extensive research and development
activities required to support an IND nor the research and development that is expensive and time-consuming and that had already been completed by the Company’s collaboration partner, Biocon S.A. outside the United States with respect to
itolizumab, the biocomparability to EQ001 of which was reviewed by the FDA in approving the IND.

(iv)
 The Company undertook significant preparations to submit a confidential draft registration statement on Form S-1 to the Commission, which was first submitted on August 3, 2018.

(v)
 The Company conducted initial
“testing-the-waters” meetings with potential investors.

(vi)
 The Company progressed its clinical trial plans for EQ001 including activities related to selecting and
commencing contracting discussions with a contract research organization.

(vii)
 The U.S. IPO market for biotechnology companies continued to be strong, with seven biotechnology IPOs pricing
in the month of July 2018, alone.

(viii)
 The capital markets in the United States continued to perform strongly with each of the Dow Jones Industrials,
S&P500, Nasdaq 100, and Nasdaq composite indexes all ending the month of July positively.

 Subsequent to
July 31, 2018, additional developments occurred that further increased the Company’s value and made it more likely that the Company could consummate a successful IPO, including:

(i)
 The Company hired key personnel, including the Company’s Chief Medical Officer, Krishna R. Polu, M.D., a
Vice President of Development Operations, and a Vice President of Commercial.

 4401 EASTGATE MALL, SAN
DIEGO, CA 92121 T: (858) 550-6000 F: (858) 550-6420 WWW.COOLEY.COM

 September 21, 2018

  Page
 5
 of 7

CONFIDENTIAL

(ii)
 The Company added the following three independent members to the Board: Martha J. Demski, Charles McDermott and
Mark Pruzanski, M.D.

(iii)
 The Company conducted additional
“testing-the-waters” meetings with potential investors.

(iv)
 The Company progressed its clinical trial plans for EQ001 including activities related to protocol amendment,
assay development and validation work, and packaging of clinical drug supply.

(v)
 The capital markets remained strong and two additional biotechnology IPOs priced in the traditionally-slow
month of August.

 July 31, 2018 Valuation and August 2018 Option Grants

In accordance with the Practice Aid, the July 31, 2018 valuation used a hybrid method of an OPM and the probability-weighted expected
return method (“PWERM”) to allocate enterprise value. The enterprise value for the OPM arm of the analysis (the stay private scenario) was determined using a precedent transaction “backsolve” method based upon the
Company’s pro forma Series A financing. The enterprise value for the PWERM arm of the analysis (the IPO scenario) was determined using a guideline public company method by choosing a group of comparable companies that recently conducted an IPO.
An analysis was performed for two potential IPO scenarios: (1) an early-term IPO scenario and (2) a late-term IPO scenario. The enterprise values used for the OPM and PWERM were each less than the enterprise value that is implied by the
estimated public offering price discussed below. This was due primarily to the early stage of the Company’s development programs, the belief that the Company may conduct a private equity financing before it could pursue an IPO, and that not
being able to complete a financing was still a risk for the Company. A DLOM of 8%, 13% and 22% was applied to the early-term IPO scenario, late-term IPO scenario and OPM arm, respectively. The hybrid model weighted the PWERM arm at 25% and 25% for
the early-term IPO and late-term IPO scenarios, respectively, the OPM arm at 30% and dissolution at 20%. The resulting fair value of the Company’s common stock was $28.39 per share.

On August 16, 2018, the Board granted an option to purchase an aggregate of 24,155 shares of common stock. On such grant date, the Board
determined that the fair value of the Company’s common stock was $28.39 per share in connection with the grant of such stock option, in consideration of the valuation analysis as of July 31, 2018 and the other objective and subjective
factors described in the Registration Statement. The Board determined that on August 16, 2018, no significant business or market developments had occurred since the valuation date of July 31, 2018, as the Company’s initial draft
submission of the Registration Statement had already been assumed and taken into account in the July 31, 2018 valuation.

 4401 EASTGATE MALL, SAN
DIEGO, CA 92121 T: (858) 550-6000 F: (858) 550-6420 WWW.COOLEY.COM

 September 21, 2018

  Page
 6
 of 7

CONFIDENTIAL

 September 12, 2018 Valuation and September 2018 Option Grants

In accordance with the Practice Aid, the September 12, 2018 valuation used a hybrid method of an OPM and a PWERM to allocate enterprise
value. The enterprise value for the OPM arm of the analysis (the stay private scenario) was determined using a precedent transaction “backsolve” method based upon the Company’s pro forma Series A financing. The enterprise value for
the PWERM arm of the analysis (the IPO scenario) was determined using a guideline public company method by choosing a group of comparable companies that recently conducted an IPO. An analysis was performed for two potential IPO scenarios:
(1) an early-term IPO scenario and (2) a late-term IPO scenario. The enterprise values used for the OPM and PWERM were each less than the enterprise value that is implied by the estimated public offering price discussed below. This was due
primarily to the early stage of the Company’s development programs and financing uncertainty. A DLOM of 6%, 12% and 22% was applied to the early-term IPO scenario, late-term IPO scenario and OPM arm, respectively. The hybrid model weighted the
PWERM arm at 30% and 25% for the early-term IPO and late-term IPO scenarios, respectively, the OPM arm at 30% and dissolution at 15%. The resulting fair value of the Company’s common stock was $33.32 per share.

On September 13, 2018, the Board granted options to purchase an aggregate of 28,897 shares of common stock and on September 14,
2018, the Board

CORRESP
1
filename1.htm

CORRESP

 Karen E. Anderson

 +1 858 550 6088

kanderson@cooley.com

VIA EDGAR

 September 17, 2018

 United
States Securities and Exchange Commission

 Division of Corporation Finance

Office of Healthcare and Insurance

 Mail Stop 4720

100 F Street, N.E.

 Washington, D.C. 20549

Attn: Donald E. Field

Re:
 Equillium, Inc.

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

 Submitted August 30, 2018

 CIK No. 0001746466

Dear Mr. Field:

 Enclosed on behalf of our client,
Equillium, Inc., a Delaware corporation (the “Company”), is a registration statement on Form S-1 (the “Registration Statement”). The Registration Statement
updates the Company’s confidential draft registration statement on Form S-1 originally submitted to the Securities and Exchange Commission (the “Commission”) on August 3, 2018
and amended on August 30, 2018 (the “Amended Draft Registration Statement”). The copy of the Registration Statement that is enclosed with the paper copy of this letter is marked to show changes from the Amended Draft
Registration Statement.

 The Registration Statement is being submitted in response to comments received from the staff of the Commission (the
“Staff”) by letters dated August 28, 2018 (the “August Comment Letter”) and September 14, 2018 (the “September Comment Letter” and together with the August Comment
Letter, the “Comment Letters”) with respect to the Amended Draft Registration Statement as well as to generally update the disclosure; provided that the Company is only providing a response to comment #6 of the August Comment
Letter in this letter. The numbering of the paragraphs below corresponds to the numbering in the Comment Letters, the text of which we have incorporated into this response letter for convenience. Except where otherwise indicated, page references in
the text of the responses below correspond to the page numbers of Registration Statement.

 Staff Comments and Company Responses

August Comment Letter

 Use of Proceeds, page 59

6.
 We note your disclosure that you intend to use net proceeds to fund research and development of EQ001.
Please revise to specify how far in the development of EQ001 you expect to reach with the proceeds of the offering. If any material amounts of other funds are necessary to accomplish the specified purposes for which the proceeds are to be obtained,
state the amounts and sources of such other funds needed for each such specified purpose and the sources thereof. Refer to Instruction 3 of Item 504 of Regulation S-K.

Cooley LLP    4401 Eastgate Mall    San Diego, CA    92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

 United States Securities and Exchange Commission

September 17, 2018

 Page Two

 Response: The Company has revised the disclosure on page 59 of the Registration Statement.

September Comment Letter

 Overview, page 1

1.
 We note your responses to our prior comments 1 and 2. Please include a footnote to the table on page 1 to
clarify that the Phase 1 trial was completed by your collaboration partner Biocon and was not completed in the U.S. or Canada.

Response: The Company has revised the disclosure on pages 2 and 79 of the Registration Statement.

*        *         *

The Company respectfully requests the Staff’s assistance in completing the review of the Registration Statement as soon as possible. Please advise us if
we can provide any further information or assistance to facilitate your review. Please direct any further comments or questions regarding the Registration Statement or this response letter to me at (858)
550-6088.

 Sincerely,

/s/ Karen E. Anderson

 Karen E. Anderson

cc:
 Daniel M. Bradbury, Equillium, Inc.

Bruce Steel, Equillium, Inc.

Cheston J. Larson, Latham & Watkins LLP

Matthew T. Bush, Latham & Watkins LLP

Cooley LLP    4401 Eastgate Mall    San Diego, CA    92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

September 14, 2018
Daniel M. Bradbury
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 108
La Jolla, CA 92037
Re:Equillium, Inc.
Amendment No. 1 to
Draft Registration Statement on Form S-1
Submitted August 30, 2018
CIK No. 0001746466
Dear Mr. Bradbury:
            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
Overview, page 1
1.We note your responses to our prior comments 1 and 2.  Please include a footnote to the
table on page 1 to clarify that the Phase 1 trial was completed by your collaboration
partner Biocon and was not completed in the U.S. or Canada.

 FirstName LastNameDaniel M. Bradbury
 Comapany NameEquillium, Inc.
 September 14, 2018 Page 2
 FirstName LastName
Daniel M. Bradbury
Equillium, Inc.
September 14, 2018
Page 2
            You may contact Bonnie Baynes at 202-551-4924 or Lisa Vanjoske at 202-551-3614 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Donald Field at 202-551-3680 or Justin Dobbie, Legal Branch Chief, at 202-551-3469
with any other questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance

August 28, 2018
Daniel M. Bradbury
Chief Executive Officer
Equillium, Inc.
2223 Avenida de la Playa, Suite 108
La Jolla, CA 92037
Re:Equillium, Inc.
Draft Registration Statement on Form S-1
Submitted August 3, 2018
CIK No. 0001746466
Dear Mr. Bradbury:
            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
Overview, page 1
1.Please refer to the second paragraph.  We note your disclosure that "[f]ollowing
completion of a Phase 3 clinical trial, itolizumab was approved in India for the treatment
of moderate to severe plaque psoriasis."  Please revise to clarify that the Phase 3 trial was
not completed in the U.S. or Canada nor is itolizumab approved in the U.S. or Canada.
Please also clarify in the summary that none of your product candidates have commenced
clinical trials or been approved in the U.S. or Canada.

 FirstName LastNameDaniel M. Bradbury
 Comapany NameEquillium, Inc.
 August 28, 2018 Page 2
 FirstName LastNameDaniel M. Bradbury
Equillium, Inc.
August 28, 2018
Page 2
Development Plans Chart, page 2
2.Please revise the chart to reflect the actual, and not the anticipated, status of EQ001 and
the various indications as of the latest practicable date.  In this regard, we note that you
have not completed any Phase 1 clinical trials for any indications.  Please revise the chart
to include a pre-clinical phase, to indicate that your aGVHD and cGVHD indications are
at the beginning of Phase 1 and that your severe asthma indication is in the pre-clinical
phase.  Additionally, please delete the to be determined 4th indication as that reference
appears premature.
3.We note that the chart is intended to summarize your development plans and the status
thereof.  Please delete the reference to Biocon and that ALZUMAb has been developed
and marketed in India as it is not one of your products.
Strategy, page 3
4.We note the statement that you believe that the unique mechanism of action of EQ001
may be effective in treating a subset of severe asthma patients who are underserved by
currently marketed therapies.  The statement implies that your product candidate is
effective, which is a determination solely within the authority of the FDA.  Since your
product candidate has not completed clinical trials and the FDA has not made such
determination, the inference is not appropriate.  Please remove this statement and similar
statements throughout the prospectus, including the statement that you believe EQ001
may effectively treat Th2-low patients.
Implications of Being an Emerging Growth Company, page 5
5.Please supplementally provide us with copies of all written communications, as defined in
Rule 405 under the Securities Act, that you, or anyone authorized to do so on your behalf,
present to potential investors in reliance on Section 5(d) of the Securities Act, whether or
not they retain copies of the communications.
Use of Proceeds, page 59
6.We note your disclosure that you intend to use net proceeds to fund research and
development of EQ001.  Please revise to specify how far in the development of
EQ001 you expect to reach with the proceeds of the offering.  If any material amounts of
other funds are necessary to accomplish the specified purposes for which the proceeds are
to be obtained, state the amounts and sources of such other funds needed for each such
specified purpose and the sources thereof.  Refer to Instruction 3 of Item 504 of
Regulation S-K.

 FirstName LastNameDaniel M. Bradbury
 Comapany NameEquillium, Inc.
 August 28, 2018 Page 3
 FirstName LastNameDaniel M. Bradbury
Equillium, Inc.
August 28, 2018
Page 3
Management’s Discussion and Analysis of Financial Condition and Results of Operations
Contractual Obligations, page 74
7.Tell us your consideration of including the convertible promissory notes and interest on
the notes in the table.
Critical Accounting Policies and Significant Judgement and Estimates
Stock-Based Compensation Expense, page 75
8.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
initial public offer and the estimated offering price. This information will help facilitate
our review of your accounting for equity issuances including stock compensation.
Business
EQ001 Product Development, page 92
9.The inclusion of the "equillium" logo in the chart on page 93 suggests that the company
was responsible for the Phase 1 clinical trial referenced underneath the logo in the chart.
This suggestion, however, is inconsistent with the disclosure regarding the trial that
follows the chart.  Please revise the chart or explain the inconsistency.
Development Plan in GVHD, page 95
10.We note the statement that you plan to initiate a Phase 2 clinical trial of EQ001 for the
treatment of cGVHD in the first half of 2019.  Please revise your disclosure to discuss any
additional steps necessary to initiate such a trial, including the filing of an IND and any
other material requirements you must satisfy.
Collaboration and License Agreement with Biocon, page 97
11.We note your disclosure in the second paragraph that you are "required to pay quarterly
tiered royalties based on a percentage from the mid-single digits to low double-digits."
Please revise your description of royalty rates to provide a range that does not exceed ten
percent (e.g., between twenty and thirty percent).
Biocon Agreements, page 134
12.We note the disclosure elsewhere in the prospectus that Mr. Bradbury, the company's
Chief Executive Officer, is a member of the board of directors of Biocon.  Please revise
your disclosure in this section to identify Mr. Bradbury as a related party with respect to
the Biocon agreements or tell us why you believe he is not a related party.

 FirstName LastNameDaniel M. Bradbury
 Comapany NameEquillium, Inc.
 August 28, 2018 Page 4
 FirstName LastName
Daniel M. Bradbury
Equillium, Inc.
August 28, 2018
Page 4
Certain Relationships and Related Party Transactions, page 134
13.Please include a description of the common stock purchase agreement with Biocon in this
section.  Please also file the common stock purchase agreement and investor rights
agreement as exhibits to the registration statement or tell us why you are not required to
do so.
Financial Statements, page F-1
14.You have only included one year of audited financial statements when two years are
required.  Please advise if you are omitting one year under Section 71003 of the FAST Act
and will include audited financial statements for 2018 prior to requesting effectiveness.
General
15.Please provide us mockups of any pages that include any additional pictures or graphics to
be presented, including any accompanying captions.  Please keep in mind, in scheduling
your printing and distribution of the preliminary prospectus, that we may have comments
after our review of these materials.
16.We note you have filed several exhibits pursuant to a request for confidential treatment.
We will provide any comments we have on your application for confidential treatment
under separate cover.
            You may contact Bonnie Baynes at 202-551-4924 or Lisa Vanjoske at 202-551-3614 if
you have questions regarding comments on the financial statements and related matters.  Please
contact Donald E. Field at 202-551-3680 or Justin Dobbie at 202-551-3469 with any other
questions.
Sincerely,
Division of Corporation Finance
Office of Healthcare & Insurance
cc:       Karen Anderson