United States securities and exchange commission logo

                           July 30, 2020

       Peter Hecht, Ph.D.
       Chief Executive Officer
       Cyclerion Therapeutics, Inc.
       301 Binney Street
       Cambridge, MA, 02142

                                                        Re: Cyclerion
Therapeutics, Inc.
Statement on Form S-3
                                                            Filed July 24, 2020
                                                            File No. 333-240095

       Dear Dr. Hecht:

              This is to advise you that we have not reviewed and will not
review your registration

               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 Jason L.
Drory at 202-551-8342 with any questions.


                           Division of Corporation Finance

                           Office of Life Sciences
       cc:                                              Gary J. Simon, Esq.