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                          November 9, 2021

       Stephen G. Dilly
       Chief Executive Officer
       Sierra Oncology, Inc.
       1820 Gateway Drive, Suite 110
       San Mateo, CA 94404

                                                        Re: Sierra Oncology,
Inc.
                                                            Registration
Statement on Form S-3
                                                            Filed November 5,
2021
                                                            File No. 333-260799

       Dear Mr. Dilly:

              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 Ada D.
Sarmento at 202-551-3798 with any questions.




                          Sincerely,


                          Division of Corporation Finance

                          Office of Life Sciences
       cc:                                              Michael Nordtvedt, Esq.