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. Registration 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 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 Jason L. Drory at 202-551-8342 with any questions. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Gary J. Simon, Esq.