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
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. 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 remote 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
       information 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 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