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                 March 28, 2022

       Ashish Khanna
       Chief Financial Officer & Chief Business Officer
       Aptinyx Inc.
       909 Davis Street, Suite 600
       Evanston, IL 60201

                                                        Re: Aptinyx Inc.
                                                            Registration
Statement on Form S-3
                                                            Filed March 24,
2022
                                                            File No. 333-263808

       Dear Mr. Khanna:

              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 Doris Gama at 202-812-3232 or Laura Crotty at
202-551-7614 with any
       questions.




                 Sincerely,


                 Division of Corporation Finance

                 Office of Life Sciences
       cc:                                              Mitchell S. Bloom, Esq.