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                          October 9, 2020

       Mike Donaldson
       Chief Financial Officer
       Summit Therapeutics Inc.
       One Broadway, 14th Floor
       Cambridge, Massachusetts 02142

                                                        Re: Summit Therapeutics
Inc.
                                                            Registration
Statement on Form S-1
                                                            File No. 333-249316
                                                            Filed October 5,
2020

       Dear Mr. Donaldson:

              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 Courtney
Lindsay at (202) 551-7237 with any questions.




                          Sincerely,


                          Division of Corporation Finance

                          Office of Life Sciences