SecProbe.io

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 SUTRO BIOPHARMA, INC.
 111 Oyster Point Blvd. South San Francisco, CA 94080
 March 30, 2026 VIA EDGAR
 United States Securities and Exchange Commission Division of
Corporation Finance 100 F Street, N.E. Washington, DC 20549

 Attention:

 Office of Life Sciences

 Re:

 Sutro Biopharma, Inc. Registration Statement on
Form S-3 Filed March 23, 2026
 File No. 333-294541
 Requested Date: April 1, 2026
 Requested Time: 4:00 p.m. Eastern Time Ladies and Gentlemen:
 Sutro Biopharma, Inc. (the “ Registrant ”) hereby requests that the Securities and Exchange Commission (the
“ Commission ”) take appropriate action to make the above-captioned Registration Statement on Form S - 3 effective at the “Requested Date” and “Requested Time” set forth above or as soon
thereafter as 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 Amanda Rose or Ryan Mitteness, both of whom are attorneys with the Registrant’s outside legal counsel,
Fenwick & West LLP, to orally modify or withdraw this request for acceleration. The Registrant requests that it be notified of
such effectiveness by a telephone call to Ms. Rose at (206) 389-4553 or, in her absence, to Mr. Mitteness at (206) 389-4533.
 * * *

 Sincerely,

 SUTRO BIOPHARMA, INC.

 By:

 /s/ Gregory Chow

 Gregory Chow

 Chief Financial Officer

 cc:
 Jane Chung, Chief Executive Officer
 Sutro Biopharma, Inc. Amanda Rose, Esq.
 Ryan Mitteness, Esq. Fenwick & West LLP
 [Signature Page to Company Acceleration Request Letter]

<DOCUMENT>
<TYPE>TEXT-EXTRACT
<SEQUENCE>2
<FILENAME>filename2.txt
<TEXT>
 March 27, 2026

Jane Chung
Chief Executive Officer
Sutro Biopharma, Inc.
111 Oyster Point Blvd.
South San Francisco, California

 Re: Sutro Biopharma, Inc.
 Registration Statement on Form S-3
 Filed March 23, 2026
 File No. 333-294541
Dear Jane Chung:

 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 Chris Edwards at 202-551-6761 with any questions.

 Sincerely,

 Division of
Corporation Finance
 Office of Life
Sciences
cc: Ryan Mitteness, Esq.
</TEXT>
</DOCUMENT>

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CORRESP

 SUTRO BIOPHARMA, INC.

111 Oyster Point Blvd.

 South San Francisco, CA 94080

November 17, 2023

 VIA EDGAR

United States Securities and Exchange Commission

 Division of
Corporation Finance

 100 F Street, N.E.

 Washington, DC 20549

Attention:

Office of Life Sciences

Re:

 Sutro Biopharma, Inc.

 Registration Statement on
Form S-3

 Filed November 13, 2023

File No. 333-275525

 Requested Date: November 21, 2023

Requested Time: 4:00 p.m. Eastern Time

 Ladies and Gentlemen:

 Sutro Biopharma, Inc. (the “Registrant”) hereby requests that the Securities and Exchange Commission (the
“Commission”) take appropriate action to make the above-captioned Registration Statement on Form S-3 effective at the “Requested Date” and “Requested Time” set forth above or as soon thereafter as
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 Amanda Rose or Ryan Mitteness, both of whom are attorneys with the Registrant’s outside legal counsel, Fenwick & West LLP, to orally modify or withdraw this request for acceleration.

The Registrant requests that it be notified of such effectiveness by a telephone call to Ms. Rose at (206)
389-4553 or, in her absence, to Mr. Mitteness at (206) 389-4533.

* * *

Sincerely,

SUTRO BIOPHARMA, INC.

By:

 /s/ Edward C. Albini

Edward C. Albini

Chief Financial Officer

cc:
 William J. Newell, Chief Executive Officer

Sutro Biopharma, Inc.

Amanda Rose, Esq.

 Ryan
Mitteness, Esq.

 Fenwick & West LLP

[Signature Page to Company Acceleration Request Letter]

United States securities and exchange commission logo
November 16, 2023
William Newell
Chief Executive Officer
Sutro Biopharma, Inc.
111 Oyster Point Blvd.
South San Francisco, CA 94080
Re:Sutro Biopharma, Inc.
Registration Statement on Form S-3
Filed November 13, 2023
File No. 333-275525
Dear William Newell:
            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 Daniel Crawford at 202-551-7767 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Ryan Mitteness, Esq.

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 SUTRO BIOPHARMA, INC.

310 Utah Avenue,

 Suite 150

South San Francisco, CA 94080

October 9, 2019

 United States Securities
and Exchange Commission

 Division of Corporation Finance

 100
F Street, N.E.

 Washington, DC 20549

Attention:

Office of Life Sciences

Re:

 Sutro Biopharma, Inc.

 Registration Statement on
Form S-3

 Filed October 4, 2019

File No. 333-234101

 Requested
Date:                 October 11, 2019

 Requested
Time:                4:00 p.m. Eastern Time

 Ladies and Gentlemen:

 Sutro Biopharma, Inc. (the “Registrant”) hereby requests that the Securities and Exchange Commission (the
“Commission”) take appropriate action to make the above-captioned Registration Statement on Form S-3 effective at the “Requested Date” and “Requested
Time” set forth above or as soon thereafter as practicable.

 The Registrant hereby authorizes Amanda Rose or Ryan Mitteness, both of
whom are attorneys with the Registrant’s outside legal counsel, Fenwick & West LLP, to orally modify or withdraw this request for acceleration.

 Sincerely,

Sutro Biopharma, Inc.

By:

/s/ Edward C. Albini

Edward C. Albini

Chief Financial Officer

 cc:

 William J. Newell, Chief Executive Officer

Sutro Biopharma, Inc.

Amanda Rose, Esq.

 Ryan Mitteness, Esq.

Fenwick & West LLP

October 8, 2019
William J. Newell
Chief Executive Officer
Sutro Biopharma, Inc.
310 Utah Avenue, Suite 150
South San Francisco, CA 94080
Re:Sutro Biopharma, Inc.
Registration Statement on Form S-3
Filed October 4, 2019
File No. 333-234101
Dear Mr. Newell:
            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 Jeffrey Gabor at 202-551-2544 with any questions.
Sincerely,
Division of Corporation Finance
Office of Life Sciences
cc:       Ryan Mitteness, Esq.

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CORRESP

 September 24, 2018

United States Securities and Exchange Commission

 Division of
Corporation Finance

 100 F Street, N.E.

 Washington, DC 20549

Attention:
 John Reynolds, Assistant Director

 Irene Barberena-Meissner, Staff Attorney

 Kevin Dougherty, Staff Attorney

 Ethan Horowitz, Accounting Branch Chief

 Wei Lu, Staff Accountant

Re:
 Sutro Biopharma, Inc.

Registration Statement on Form S-1 (File No. 333-227103)

Ladies and Gentlemen:

 Pursuant to Rule 460 of the General
Rules and Regulations under the Securities Act of 1933, as amended, we wish to advise that between September 17, 2018 and the date hereof, approximately 675 copies of the Preliminary Prospectus dated September 17, 2018 were distributed to
prospective underwriters, institutional investors and prospective dealers in connection with the above-captioned Registration Statement.

 We wish to
advise you that the participating underwriters have informed us that they have complied and will continue to comply with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended.

 We hereby join in the request of the registrant that the effectiveness of the above-captioned Registration Statement, as amended, be accelerated to 4:00
p.m. Eastern Time, on Wednesday, September 26, 2018 or as soon thereafter as practicable.

 [Signature page follows]

 Very truly yours,

COWEN AND COMPANY, LLC

 PIPER JAFFRAY & CO.

As representatives of the Underwriters

 By:

 Cowen and Company, LLC

By:

/s/ Jason Fenton

 Name:

 Jason Fenton

 Title:

Managing Director

 By:

 Piper Jaffray & Co.

By:

/s/ Neil Riley

 Name:

 Neil Riley

 Title:

Managing Director

CORRESP
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CORRESP

 Sutro Biopharma, Inc.

310 Utah Avenue, Suite 150

 South San Francisco, CA 94080

September 24, 2018

 VIA EDGAR

United States Securities and Exchange Commission

 Division of
Corporation Finance

 100 F Street, NE

 Washington, DC 20549

Attention:
 John Reynolds, Assistant Director

 Irene Barberena-Meissner, Staff Attorney

 Kevin Dougherty, Staff Attorney

 Ethan Horowitz, Accounting Branch Chief

 Wei Lu, Staff Accountant

Re:
 Sutro Biopharma, Inc. Registration Statement on Form S-1 (File No. 333-227103)

 originally filed August 29, 2018, as amended, and corresponding Registration Statement

 on Form 8-A (File
No. 001-38662) filed September 18, 2018

 Requested Date: September 26, 2018

Requested Time: 4:00 PM Eastern Time

 Ladies and Gentlemen:

Sutro Biopharma, Inc. (the “Registrant”) hereby requests that the Securities and Exchange Commission take appropriate
action to declare the above-captioned Registration Statements on Form S-1 and Form 8-A effective at the “Requested Date” and “Requested Time” set forth above or as soon thereafter as practicable.

The Registrant hereby authorizes Robert A. Freedman or Amanda L. Rose, both of whom are attorneys with the Registrant’s outside legal
counsel, Fenwick & West LLP, to orally modify or withdraw this request for acceleration.

 The Registrant requests that it be
notified of such effectiveness by a telephone call to Mr. Freedman at (650) 335-7292 or, in his absence, Ms. Rose at (206) 389-4553.

* * *

Sincerely,

SUTRO BIOPHARMA, INC.

By:

/s/ Edward Albini

Edward Albini

Chief Financial Officer

cc:
 William J. Newell, Chief Executive Officer

Sutro Biopharma, Inc.

Robert A. Freedman, Esq.

 Amanda
L. Rose, Esq.

 Fenwick & West LLP

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September 17, 2018

ROBERT A. FREEDMAN

 EMAIL: RFREEDMAN@FENWICK.COM

Direct Dial: +1 (650) 335-7292

 VIA EDGAR AND OVERNIGHT DELIVERY

U.S. Securities and Exchange Commission

 Division of Corporation
Finance

 100 F Street, NE

 Washington, DC 20549

Attention:
 John Reynolds, Assistant Director

 Irene Barberena-Meissner, Staff Attorney

 Kevin Dougherty, Staff Attorney

 Ethan Horowitz, Accounting Branch Chief

 Wei Lu, Staff Accountant

Re:
 Sutro Biopharma, Inc.

 Registration Statement on Form S-1 filed on August 29, 2018

 File No. 333-227103

Ladies and Gentlemen:

 On behalf of Sutro
Biopharma, Inc. (the “Company”), we are concurrently transmitting herewith Amendment No. 1 (“Amendment No. 1”) to the Registration Statement on Form S-1 (File No. 333-227103) initially filed by the Company with the U.S. Securities and Exchange Commission (the “Commission”) on August 29,
2018 (the “Registration Statement”). In this letter, we respond to the comments of the staff of the Commission (the “Staff”) contained in the Staff’s letter dated September 11, 2018 (the
“Letter”) with respect to the Registration Statement. The numbered paragraphs below correspond to the numbered comments in the Letter and the Staff’s comments are presented in bold italics. We have also enclosed with the
copy of this letter that is being transmitted via overnight courier copies of Amendment No. 1 in paper format, marked to show changes from the Registration Statement as initially filed.

Risk Factors, page 13

 Anti-takeover
provisions in our charter documents and under Delaware law…., page 65

1.
 We note your revised disclosure that under your bylaws, the U.S. federal district courts will be the
exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act. Please expand your disclosure here or include a separate risk factor to discuss the risks associated with such provision.

 In response to the Staff’s comment, the Company has revised its disclosure on pages 66 and 67 of Amendment
No. 1.

 U.S. Securities and Exchange Commission

September 17, 2018

  Page
 2

 Description of Capital Stock, page 169

Restated Certificate of Incorporation and Restated Bylaw Provisions, page 173

Choice of Forum, page 174

2.
 We note that your forum selection provision identifies the Court of Chancery of the State of Delaware as
the exclusive forum for certain litigation, including any “derivative action.” Please disclose whether this provision applies to actions arising under the Exchange Act. 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 this provision does not apply to actions arising under the Exchange Act, please
also ensure that the exclusive forum provision in your governing documents states this clearly.

 In response to
the Staff’s comment, the Company has revised its disclosure on page 177 of Amendment No. 1 and has revised its restated certificate of incorporation 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.

 * * * * * * *

 U.S. Securities and Exchange Commission

September 17, 2018

  Page
 3

 Should the Staff have additional questions or comments regarding the foregoing, please do not
hesitate to contact the undersigned at (650) 335-7292, or, in his absence, Amanda Rose at (206) 389-4553.

Sincerely,

FENWICK & WEST LLP

/s/ Robert A. Freedman

Robert A. Freedman

Partner

cc:
 William J. Newell, Chief Executive Officer

 Edward Albini, Chief Financial Officer

 Sutro Biopharma, Inc.

 Amanda L. Rose

 Fenwick & West LLP

 David Peinsipp

 Charles S. Kim

 Andrew S. Williamson

 Cooley LLP

Mail Stop 4628

September  11, 2018

William J. Newell
Chief Executive Officer
Sutro Biopharma , Inc.
310 Utah Avenue, Suite 150
South San Francisco, CA 94080

Re: Sutro Biopharma, Inc.
Registration Statement on Form S -1
Filed August 29 , 2018
File No. 333 -227103

Dear Mr. Newell :

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 amendm ent 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.

Risk Factors, page 13

Anti-takeover provisions in our charter documents and under Delaware law…, page 65

1. We note your revised disclosure that under your bylaws, the U.S. federal district courts
will be the exclusive forum for resolving any complaint asse rting a cause of action arising
under the Securiti es Act.  Please expand your disclosure here or include a separate risk
factor to discuss the risks associated with such provision.

William J. Newell
Sutro Biopharma, Inc.
September 11 , 2018
Page 2

 Description of Capital Stock, page 169

Restated Certificate of Incorporation and Restated Bylaw Provisions, page  173

Choice of Forum, page 174

2. We note that your forum selection provision identifies the Court of Chancery of the State
of Delaware as the exclusive forum for certain litigation, incl uding any “derivative
action.”  Please disclose whether this provision  applies to actions arising under the
Exchange Act.  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 reg ulations thereunder.  If this provision does not
apply to actions arising under the Exchange Act, please also ensure that the exclusive
forum provision in 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  Wei Lu , Staff Accountant, at (202) 551 -3725  or Ethan Horowitz ,
Accounti ng Branch Chief, at 202 -551-3311 if you have questions regarding comments on the
financial s tatements and related matters.  Please contact Irene Barberena -Meissner, Staff
Attorney , at (202) 551 -6548 or Loan Lauren P. Nguyen, Legal Branch Chief , at (202) 551 -3642
with any other questions.

Sincerely,

 /s/ Loan Lauren P. Nguyen  for

John Reynolds
Assistant Director
Office of Natural Resources

cc: Rob Freedman , Esq.
Fenwick & West  LLP

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CORRESP

 September 10, 2018

CERTAIN PORTIONS OF THIS LETTER AS FILED VIA EDGAR HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE COMMISSION. CONFIDENTIAL TREATMENT HAS
BEEN REQUESTED FOR THE OMITTED PORTIONS, WHICH HAVE BEEN REPLACED WITH THE FOLLOWING PLACEHOLDER: “[*].”

 VIA EDGAR AND OVERNIGHT
DELIVERY

Securities and Exchange Commission
Division of Corporation Finance
100 F Street, NE
Washington, DC 20549

Attention:

 John Reynolds

 Irene Barberena-Meissner

Kevin Dougherty

 Ethan Horowitz

Wei Lu

Re:

 Sutro Biopharma, Inc.

 Registration
Statement on Form S-1

 Filed August 29, 2018

File No. 333-227103

 Ladies and Gentlemen:

 On
behalf of Sutro Biopharma, Inc. (the “Company”), and in connection with the submission of a letter dated July 10, 2018, in response to comments from the staff (the “Staff”) of the Securities and
Exchange Commission (the “Commission”) contained in your letter dated June 29, 2018 (the “Comment Letter”), relating to the above-referenced Registration Statement on Form S-1 (the “Registration Statement”), we submit this supplemental letter to further address comment 6 of the Comment Letter concerning valuation considerations related to the Company’s
recent equity awards. For the convenience of the Staff, we are providing to the Staff by overnight delivery copies of this letter.

 Because of the
commercially sensitive nature of information contained herein, this submission is accompanied by the Company’s request for confidential treatment of selected portions of this letter pursuant to Rule 83 of the Commission’s
Rules on Information and Requests, 17 C.F.R. § 200.83 and the Freedom of Information Act.

 CONFIDENTIAL TREATMENT REQUESTED BY
SUTRO BIOPHARMA, INC.

 SUTRO - 1

 Securities and Exchange Commission

Division of Corporation Finance

 September 10, 2018

 Page
 2

 The Company advises the Staff that the Company currently anticipates that it will include an expected price
range in its preliminary prospectus (the “Preliminary Prospectus”) for the proposed initial public offering (the “IPO”) that will be between approximately $[*] and $[*] per share after effecting a
proposed approximate [*]-to-1 reverse stock split (the “Price Range”). The Company plans to effect the reverse stock split in connection with its IPO pursuant to a future amendment of
the Company’s certificate of incorporation that will be filed with the Secretary of State of the State of Delaware before filing the Preliminary Prospectus with the Commission (the “Stock Split”). The share numbers and
stock prices set forth in this letter reflect the Stock Split and are all post-split. The Price Range has been determined based, in part, upon current market conditions, recent public offerings of other comparable companies and input received from
the lead underwriters of the proposed offering, including discussions that took place on September 4, 2018 between senior management of the Company, the Board of Directors of the Company (the “Board”) and representatives
of Cowen and Company, LLC and Piper Jaffray & Co., the lead underwriters.

 Prior to September 4, 2018, the Company had not held formal
discussions with the underwriters regarding a price range for the IPO. The Price Range does not take into account the current lack of liquidity for the Company’s common stock and assumes a successful initial public offering as of the date of
that discussion with no weighting attributed to any other outcome for the Company’s business, such as remaining a privately held company.

 The
Company expects to include a bona fide price range in an amendment to the Registration Statement that would shortly precede the commencement of the Company’s public marketing process, which it anticipates could commence as soon as [*]. Such
price range could differ from the Price Range based on then-current market conditions, continuing discussions with the lead underwriters and further business developments impacting the Company.

We supplementally advise the Staff that, as described on pages 96-97 of the Registration Statement, for all periods
prior to the IPO, the fair values of the shares of common stock underlying the Company’s share-based awards were estimated on each grant date by the Board. In order to determine the fair value of the Company’s common stock underlying
option grants, the Board considered, among other things, timely valuations of the Company’s common stock prepared by an unrelated third-party valuation firm in accordance with the guidance provided by the American Institute of Certified Public
Accountants Practice Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Given the absence of a public trading market for the Company’s common stock, the Board exercised reasonable judgment and
considered a number of objective and subjective factors to determine the best estimate of the fair value of the Company’s common stock, including important developments in the Company’s operations, its stage of development, valuations
performed by an independent third party valuation firm, sales of the Company’s redeemable convertible preferred stock, actual operating results and financial performance, the conditions in the biotechnology industry and the economy in general,
the stock price performance and volatility of comparable public companies, the lack of liquidity of the Company’s common stock, and the likelihood of achieving a liquidity event, such as an initial public offering or sale.

The following table summarizes the grant of options by the Company since January 1, 2017.

 CONFIDENTIAL TREATMENT
REQUESTED BY SUTRO BIOPHARMA, INC.

 SUTRO - 2

 Securities and Exchange Commission

Division of Corporation Finance

 September 10, 2018

 Page
 3

 Award Date

Shares
Underlying

Valuation Report
Date

Exercise Price of
Option

Fair Value of
Common Stock
for Accounting
Purposes

 February 6, 2017

[*]

September 30, 2016

$[*]

$[*]

 May 11, 2017

[*]

September 30, 2016

$[*]

$[*]

 September 19, 2017

[*]

September 30, 2017

$[*]

$[*]

 December 13, 2017

[*]

September 30, 2017

$[*]

$[*]

 February 15, 2018

[*]

September 30, 2017

$[*]

$[*]

 The Company used the following valuation and allocation methods for each of the valuation reports:

September 30, 2016

September 30, 2017

Equity value determination

Market Adjusted Approach

Life Science Expected Compound Method

Allocation method

OPM

OPM

 Estimated Fair Value

 of common stock

$[*]

$[*]

 The September 30, 2016 valuation was prepared on a minority, non-marketable
interest basis using the enterprise value determined as of the September 30, 2014 valuation analysis (derived from an Option Pricing Method, or OPM, backsolve performed on the Series D-2 redeemable
convertible preferred stock issuance that occurred in September 2014) as a starting point, which was then adjusted for market-related trends and Company-specific changes since the Series D-2 redeemable
convertible preferred stock issuance.

 The September 30, 2017 valuation was prepared on a minority,
non-marketable interest basis with the enterprise value determined by using a value per compound at the 20th percentile based on a study of 13 guideline public companies and multiplied such value per compound
by the expected number of compounds to estimate the enterprise value. Such estimated enterprise value was adjusted for the cash available and debt balance at September 30, 2017 to derive the equity value.

Both the September 30, 2016 and September 30, 2017 valuations used the OPM given the very wide range of possible future exit events, and given that
forecasting specific probabilities at either date would render potential values associated with any future events to be highly speculative and imprecise. The Probability Weighted Expected Return Method, or PWERM, was considered but ultimately was
not used due to the uncertainty surrounding future potential liquidity events.

 After the aggregate enterprise value was determined and allocated to the
various classes of stock, a Discount for Lack of Marketability, or DLOM, was applied to the estimated fair value of the Company’s common stock. DLOM is applied based on the premise that a private company valuation analysis relies on data from
publicly traded companies, which are marketable and the common stock of a private company is not.

 CONFIDENTIAL TREATMENT
REQUESTED BY SUTRO BIOPHARMA, INC.

 SUTRO - 3

 Securities and Exchange Commission

Division of Corporation Finance

 September 10, 2018

 Page
 4

 For the September 30, 2016 valuation, the OPM included a term of 2.5 years, volatility of 64% and
risk-free rate of 0.83%. The term of the option of 2.5 years was estimated as the average expected holding period of the investors in the security based on management estimates. Volatility was calculated by analyzing the implied volatilities of
publicly traded companies with operations similar to the Company. The guideline company equity volatility indications were adjusted based on each company’s capital structure to arrive at an asset volatility. A selected asset volatility for the
Company was estimated and then adjusted based on the Company’s capital structure to arrive at the applicable equity volatility for the Company. The risk-free rate of 0.83% was based on the yield of U.S. Treasury notes, matching the expected
term with time to maturity. The final step in calculating the value of the Company’s common stock was to apply a per share DLOM of 35.0%, which reflects the lower value placed on securities that are not freely transferable, as compared to those
that trade frequently in an established market.

 For the September 30, 2017 valuation, the OPM included a term of 2.5 years, volatility of 64% and
risk-free rate of 1.55%. The term of the option of 2.5 years was estimated as the average expected holding period of the investors in the security based on management estimates. The volatility was the expected volatility of the business enterprise,
typically defined through analysis of guideline public company equity market data. The risk-free rate of 1.55% was based on the yield of U.S. Treasury notes, matching the expected term with time to maturity. The final step in calculating the value
of the Company’s common stock was to apply a per share DLOM of 35.0%, which reflects the lower value placed on securities that are not freely transferable, as compared to those that trade frequently in an established market.

The Board used the valuation report as of September 30, 2016 to determine the fair value of common stock as of February 4, 2017 and May 11,
2017. During the period from September 30, 2016 to May 11, 2017, there were no significant corporate events, developments or additional equity financings that occurred. Given the lack of clarity around a future liquidity event, and the
lack of significant program progression or additional funding received, in the judgment of the Board, there were no internal or external developments that would indicate that the fair value of the Company’s common stock would have increased
from the fair value at September 30, 2016 of $[*] per share for the grants in February 2017 and May 2017.

 In August 2017, the Company entered an
Amended and Restated Collaboration and License Agreement with Celgene (the “2017 Celgene Agreement”) to refocus its prior agreement with Celgene on four programs that are advancing throughout preclinical development. Upon
signing of the 2017 Celgene Agreement, the Company received a payment of $12.5 million in August 2017. Per the terms of the 2017 Celgene Agreement, the Company is entitled to earn development and regulatory contingent payments for each of the
four programs under the collaboration, and royalties on sales of any commercial products that may result from the 2017 Celgene Agreement.

 As discussed
above, the Company obtained a third-party valuation report as of September 30, 2017 which indicated the fair value of the Company’s common stock as of that date was $[*] per share. The Board had approved option grants on September 19,
2017 with an exercise price of $[*] per share. The Board believed it was reasonable to estimate the common stock fair value at September 19, 2017 based on the valuation report as of September 30, 2016 as that report was the most current
one they had at the time of grant. As the 2017 Celgene Agreement could potentially be deemed to be a factor that would change the estimated enterprise value of the Company and such event occurred in August 2017, which was before the
September 19, 2017 option grant date, the Company reassessed the fair value of its common stock at September 19, 2017 for financial reporting purposes.

 CONFIDENTIAL TREATMENT
REQUESTED BY SUTRO BIOPHARMA, INC.

 SUTRO - 4

 Securities and Exchange Commission

Division of Corporation Finance

 September 10, 2018

 Page
 5

 Given that the next valuation report obtained was dated as of September 30, 2017, which was less than
two weeks after the option grant date in September 2017, the Company evaluated the impact on its stock-based compensation expense of using a fair value of $[*] per share rather than the exercise price value of $[*]. The Company calculated what the
additional expense would be if it used a fair value of $[*] per share for the September 19, 2017 grants. Assuming the difference in fair value of common stock of $[*] per share ($[*] - $[*] = $[*]) is equal to the increase in the fair value
under a Black-Scholes option pricing model, total stock-based compensation expense is understated by approximately $[*]. Given that the options vest over a four-year period, the impact on 2017 and future periods was concluded to not be material to
the overall financial results and to the overall financial statements of the Company. As such, the Company elected to not adjust its stock-based compensation for the September 19, 2017 option grants.

The Board used the valuation report as of September 30, 2017 to determine the fair value of common stock as of December 13, 2017 and
February 15, 2018. During the period from September 30, 2017 to February 15, 2018, there were no significant corporate events, developments or additional equity financings that occurred. Given the lack of clarity around a future
liquidity event, and the lack of significant program progression or additional funding received, in the judgment of the Board, there were no internal or external developments that would indicate that the fair value of the Company’s common stock
would have increased from September 30, 2017 for the grants in December 2017 and February 2018.

 The Company has not granted any options since
February 2018. The Company expects to grant additional options as well as restricted stock units effective upon the pricing of the IPO with an exercise price equal to the price at which the shares are sold to the public in the IPO.

The Company respectfully submits that there is only a [*]% difference between the fair value per share as of February 15, 2018 and the midpoint of the
Price Range. Furthermore, if the lack of marketability discount is removed, the fair value per share as of February 15, 2018 would be $[*], or [*]% above the midpoint of the Price Range.

The Company submits that the primary reason for the difference between the fair value per share used for the stock options granted in February 2018 and the
midpoint of the Price Range are:

•

 Differences in the valuation methodologies, assumptions and inputs used by the underwriters in their valuation
analysis discussed with the Company and used to determine the Price Range, which assume a successful IPO as of today’s date with no weighting attributed to any other outcome for the Company’s business, such as remaining a privately held
company, compared to the valuation methodologies, assumptions and inputs used in the valuations determined by the Board as described above in connection with the desc

CORRESP
1
filename1.htm

CORRESP

August 29, 2018

ROBERT A. FREEDMAN

EMAIL: RFREEDMAN@FENWICK.COM
Direct Dial: +1 (650) 335-7292

 VIA EDGAR AND OVERNIGHT DELIVERY

 U.S. Securities and Exchange Commission
Division of Corporation Finance

100 F Street, NE
Washington, DC 20549

Attention:

 John Reynolds, Assistant Director

 Irene
Barberena-Meissner, Staff Attorney

 Kevin Dougherty, Staff Attorney

Ethan Horowitz, Accounting Branch Chief

 Wei Lu, Staff
Accountant

Re:

 Sutro Biopharma, Inc.

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

 Response dated August 20, 2018

CIK No. 0001382101

 Ladies and Gentlemen:

On behalf of Sutro Biopharma, Inc. (the “Company”), we are concurrently transmitting herewith the Registration
Statement on Form S-1 that was filed by the Company with the U.S. Securities and Exchange Commission (the “Commission”) on August 29, 2018 (the “Registration
Statement”). In this letter, we respond to the comments from the staff of the Commission (the “Staff”) contained in the Staff’s letter dated August 23, 2018 (the “Letter”). The
numbered paragraph below corresponds to the numbered comment in the Letter and the Staff’s comments are presented in bold italics.

 General

1.
 Please disclose the specific indication(s) for the Immuno-oncology Bispecific Antibody (bsAb) product
candidate in your Celgene collaboration program or tell us why you are not able to do so.

 In response to the
Staff’s comment, the Company advises the Staff that it has revised the Prospectus Summary to remove the pipeline chart. In addition, the Company has revised the pipeline chart on page 111 of the Registration Statement to remove reference
to the Immuno-oncology Bispecific Antibody (bsAb) product candidate in the Celgene collaboration program.

2.
 While we do not object to a narrative discussion of your discovery and preclinical programs in the
Prospectus Summary or the inclusion of your discovery program and preclinical programs as a graphic in the Business section, we believe that presenting these programs as a prominent graphic in the Prospectus Summary is not appropriate given that the
product candidates have yet to be identified and these programs remain in the discovery or preclinical development stage and may not reach any of the clinical stages. In addition, please expand this graphic to include additional columns reflecting
the clinical stage phases to describe each program’s progress toward clinical development.

 In
response to the Staff’s comment, the Company advises the Staff that it has revised the Prospectus Summary to remove the discovery and preclinical programs chart. In addition, the Company has revised the discovery and preclinical programs chart
on page 111 of the Registration Statement to include an additional column reflecting the clinical stage phases to describe each program’s progress toward clinical development.

* * * * * * *

 U.S. Securities and Exchange Commission

August 29, 2018

  Page
 2

 Should the Staff have additional questions or comments regarding the foregoing, please do not
hesitate to contact the undersigned at (650) 335-7292, or, in his absence, Amanda Rose at (206) 389-4553.

Sincerely,

FENWICK & WEST LLP

/s/ Robert A. Freedman

Robert A. Freedman

Partner

cc:
 William J. Newell, Chief Executive Officer

Edward Albini, Chief Financial Officer

Sutro Biopharma, Inc.

Amanda L. Rose

Fenwick & West LLP

David Peinsipp

 Charles S. Kim

 Andrew S. Williamson

Cooley LLP

Mail Stop 4628
August  23, 2018

William J. Newell
Chief Executive Officer
Sutro Biopharma , Inc.
310 Utah Avenue, Suite 150
South San Francisco, CA 94080

Re: Sutro Biopharma, Inc.
Amendment No. 1 to Draft Registration Statement on Form S -1
Response dated August 20 , 2018
CIK No.  0001382101

Dear Mr. Newell :

We have reviewed  your response letter 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.  I f 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.

General

1. Please disclose  the specific indication (s) for the Immuno -oncology Bispecific Antibody
(bsAb) product candidate in your Celgene  collaboration program  or tell us why you are
not able to do  so.

2. While we do not object to a narrative discussion of your discovery and preclinical
programs in the Prospectus Summary or the inclusion of your discovery program  and
preclinical program s as a gr aphic in the Business section, we believe that presenting these
programs as a prominent graphic in the  Prospectus  Summary is not appropriate given that
the product candidates have yet to be identified and these programs remain in the
discovery or preclinic al development stage  and may not reach any of the clinical stages .
In addition, please expand  this graphic to include  additional colum ns reflecting  the
clinical stage phases to describe  each program ’s progress  toward clinical development .

William J. Newell
Sutro  Biopharma, Inc.
August  23, 2018
Page 2

   You may contact  Wei Lu , Staff Accountant, at (202) 551 -3725  or Ethan Horowitz ,
Accounti ng Branch Chief, at 202 -551-3311 if you have questions regarding comments on the
financial s tatements and related matters.  Please contact Irene Barberena -Meissner, Staff
Attorn ey, at (202) 551 -6548 or Kevin Dougherty, Staff Attorney, at (202) 551 -3271  with any
other questions.

Sincerely,

 /s/ John Reynolds

John Reynolds
Assistant Director
Office of Natural Resources

cc: Rob Freedman , Esq.
Fenwick & West  LLP

Mail Stop 4628
July 27, 2018

William J. Newell
Chief Executive Officer
Sutro Biopharma, Inc.
310 Utah Avenue, Suite 150
South San Francisco, CA 94080

Re: Sutro Biopharma, Inc.
Amendment No. 1 to Draft Registration Statement on Form S -1
Submitted July 10, 2018
CIK No.  0001382101

Dear Mr. Newell :

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
stateme nt 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 yo ur
amended draft registration statement or filed registration statement,  we may have  additional
comments.   Unless we note otherwise, our references to prior comments  are to comments in
our June 29 , 2018 letter.

Our Pipeline, page 2

1. We note your  response to our prior comment 3, and we reissue in part:

 We do not object to a discussion of each program below the table  or in the
business section , but research and discovery activities that precede the
identification of a product candidate are too re mote to be highlighted in the
pipeline table.   Please limit your table to products that are at least in the
preclinical stage of development.

 For products in such preclinical stage of development that you retain, please
clarify the indication intended to  be pursued for each program more
specifically than “oncology,” or disclose why such indication is not material.

William J. Newell
Sutro Biopharma, Inc.
July 27, 2018
Page 2

Merck KGaA, Darmstadt, Germany Collaboration, page 115

2. We note your response to prior comment 10.  Please revise to disclose the
informatio n included in your response addressing the expiration terms of the MDA
agreement, including that the term of the MDA Agreement is based on the later of the
expiration of the patents covering products licensed under the MDA Agreement or ten
years after the first commercial sale of a product covered under the MDA Agreement.

You may contact  Wei Lu , Staff Accountant, at (202) 551 -3725  or Ethan Horowitz,
Accounting Branch Chief, at 202 -551-3311 if you have questions regarding comments on the
financial s tatement s and related matters.  Please contact Irene Barberena -Meissner, Staff
Attorney, at (202) 551 -6548 or  Kevin Dougherty, Staff Attorney, at (202) 551 -3271  with any
other questions.

Sincerely,

 /s/ John Reynolds

John Reynolds
Assistant Director
Office of Natural Resources

cc: Rob Freedman , Esq.
Fenwick & West  LLP

Mail Stop 4628
June 29, 2018

William J. Newell
Chief Executive Officer
Sutro Biopharma , Inc.
310 Utah Avenue, Suite 150
South San Francisco, CA 94080

Re: Sutro Biopharma, Inc.
Draft Registration Statement on Form S -1
Submitted June 1, 2018
CIK No.  0001382101

Dear Mr. Newell :

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 registra tion statement or filed registration statement,  we may have  additional
comments.

Prospectus Summary, page 1

1. We note your disclosure here and in the Business section that your preclinical models for
STRO -001 have demonstrated “potent anti -tumor activity ” and its properties “suggest a
low likelihood of off -target toxicity ” and potential for improved therapeutic index, and
for STRO -002 that your preclinical  models have demonstrated “superior inhibition of
tumor growth” and greater linker stability relative  to the benchmark molecule you
created.  Please revise your disclosure to eliminate any suggestion that your candidates
have been or will ultimately be determined to be safe or effective or to have demonstrated
efficacy for purposes of granting marketing a pproval by the FDA or comparable agency,
including comparisons to the current standard of care.

2. We note your statements in this section and throughout your filing that your product
candidates will be first -in-class and best-in-class , and that your platform allows you to

William J. Newell
Sutro Biopharma, Inc.
June 29 , 2018
Page 2

 accelerate the discovery of first -in-class and best -in-class molecules.  Since these
statements imply an expectation of regulatory approval, they are inappropriate given your
early stage of development and lack of cli nical trial data.  Please remove these statements
and similar statements from the descriptions of your platform and product candidates.

Our Pipeline, page 2

3. We note  your product pipeline table s here and in your Business section include  programs
that are in the discovery phase.  Because you have not identified a product candidate for
these programs , it appears  premature to include them in a product pipeline table.  Please
revise or ad vise.  Please also include in the table columns for Phases 2 and 3 and the
indications intended t o be pursued for each product candidate.

Corporate Information, page 5

4. Please explain the difference between XpressCF and XpressCF+ at an appropriate place
in your filing.

Use of Proceeds, page 68

5. We note your disclosure that the expected net proceeds  of the offering will not be
sufficient to fund any of your product candidates through regulatory approval, and you
will need to raise substantial additional capital to complete the development and
commercialization of your product candidates. Please clari fy the expected stage of
development you expect to achieve with your current assets and the proceeds from this
offering.

Management’s Discussion and Analysis of Financial Condition and Results of Operations, page
79

Critical Accounting Polices and Estimates , page 88

Stock -Based Compensation, page 90

6. Revise the disclosure regarding your estimates of the fair value of stock options granted
to your employees to specify the methods used to determine the fair value of the shares
underlying these award s and to provide additional detail regarding the nature of the
material assumptions involved in making those estimates.   Separately, p rovide us with an
analysis explaining the reasons for material differences between recent valuations of your
common stock and your estimated offering price, once it is available.

William J. Newell
Sutro Biopharma, Inc.
June 29 , 2018
Page 3

 Business, page 94

Our Product Candidates, page 104

7. We note that the studies discussed in this section provide data without providing proper
context for such data.  For each of the studies discusse d in this section, please disclose the
date(s) of the studies, the sponsor and the location; scope and size; dosage and duration;
and actual results observed, including any negative findings.  Please also state whether
you have published the data for any of your studies.

8. You disclose on pages 107 and 111 that the toxicology studies you conducted to
investigate the safety of STRO -001 and STRO -002, respectively, did not result in any
“unexpected toxicity findings. ”  Please revise your disclosure to explain what you mean
by this statement.

Collaboration and License Agreements, page 112

Celgene Collaboration, page 112

9. We note that you are eligible to earn tiered royalties ranging from single -digit to low
double -digit percentages on worldwide sales of any commercial product that may result
from the 2017 Calgene Agreement. This disclosure is too broad and could imply that
your royalty rate is up to 49%.   Please revise your disclosure here and throughout the
prospectus to give investors a reasonable idea of  the amount of the royalty rate that does
not exceed 10 percentage points .

Merck KGaA, Darmstadt, Germany Collaboratio n, page 113

10. We note your disclosure that the MDA Agreement term expires on a product -by-product
and country -by-country basis, and that upon expiration, Merck KGaA, Darmstadt,
Germany will have a fully paid -up, royalty free, perpetual, and irrevocable non -exclusive
license, with the right to grant sublicenses, under certain of your intellectual property
rights.  Please disclose the years , or range of years if more appropriate, in which this
agreement will expire.

Intellectual Property, page 116

11. Please revise your dis closure to clearly identify your material patents or patent
applications, including the patents or patent applications relating to your Xpress CF
Platform, and your product  candidates, STRO -001 and STRO -002.  For each such
material patent or patent application, please disclose (1) whether the patents relate to
XpressCF Plaform or the specific product(s) to which such patents or patent applications
relate; (2) whether the pat ents are owned or licensed from  Stanford or other third parties
(3) the type of patent protection; (4) patent expiration dates and expected expiration dates

William J. Newell
Sutro Biopharma, Inc.
June 29 , 2018
Page 4

 for patent applications; and (5) the jurisdictions where such patents were issued and such
patent a pplications are pendi ng.

Management, page 131

12. We note that your website indicates that you have a scientific advisory board and a
clinical advisory board.  Please revise your disclosure to describe the role or function of
each of your scientific advisory board and clinical advisory board, and whether there are
any rul es of procedures governing these boards.  Please also disclose how members of
such boards are compensated.

Certain Relationships and Related Party Transactions, page 150

Letter Agre ement with Four Oaks, page 151

13. Please revise your disclosure to describe the compensation terms under you letter
agreement with Four Oaks.   In this regard, please clarify whether your future payments to
Four Oaks of amount s equal to 2% of any future payme nts received under your 2017
Celgene Agreement  are your only payment obligations under  the letter agreement .  Please
also file a copy of this agreement as an exhibit or explain why it is not required to be
filed.  Refer to 601(b)(1 0)(ii)(B) of Regulation S -K.

Principal Stockholders, page 153

14. Consistent with Item 403 of Regulation S -K and Exch ange Act Rule 13d -3, please
identify the person or persons who directly or indirectly exercise sole or shared voting
and/or dispositive power with respect to the shares held by Mutual Fund Series Trust, on
behalf of Eventide Healthcare & Life Sciences Fund.

General

15. Please supplementally provide us with copies of all written communications, as defined
in Rule 405 under the Securities Act, that you, or anyon e 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.

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.

William J. Newell
Sutro Biopharma, Inc.
June 29 , 2018
Page 5

 You may contact  Wei Lu , Staff Accountant, at (202) 551 -3725  or Ethan Horowitz ,
Accounti ng Branch Chief, at 202 -551-3311 if you have questions regarding comments on the
financial s tatements and related matters.  Please contact Irene Barberena -Meissner, Staff
Attorney , at (202) 551 -6548 or Kevin Dougherty, Staff Attorney, at (202) 551 -3271  with any
other questions.

Sincerely,

 /s/ John Reynolds

John Reynolds
Assistant Director
Office of Natural Resources

cc: Rob Freedman , Esq.
Fenwick & West  LLP