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. 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.

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 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.
 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,
Accounting Branch Chief, at 202-551-3311 if you have questions regarding
comments on the
financial statements 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