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                          October 25, 2021

       Andrew Allen
       President and Chief Executive Officer
       Gritstone bio, Inc.
       5959 Horton Street, Suite 300
       Emeryville, California 94608

                                                        Re: Gritstone bio, Inc.
                                                            Registration
Statement on Form S-3
                                                            Filed October 15,
2021
                                                            File No. 333-260292

       Dear Dr. Allen:

              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 Jordan
Nimitz at 202-551-6001 with any questions.




                          Sincerely,


                          Division of Corporation Finance

                          Office of Life Sciences
       cc:                                              Brian Cuneo, Esq.