Filed by Cyclerion Therapeutics, Inc.
pursuant to Rule 425 under the Securities Act of 1933
and deemed filed pursuant to Rule 14a-12
under the Securities Exchange Act of 1934
Subject Company: Cyclerion Therapeutics, Inc.
Commission File No.: 333-295175
Date: August 3, 2026
This filing relates to
the proposed transaction pursuant to the terms of that certain Agreement and Plan of Merger and Reorganization dated as of April 1, 2026, by and among Cyclerion Therapeutics, Inc., a Massachusetts corporation (“Cyclerion”),
Cariboos Merger Sub Corp., a Delaware corporation and a wholly-owned subsidiary of Cyclerion (“First Merger Sub”), Cariboos Merger Sub II, LLC, a Delaware limited liability company and wholly-owned subsidiary of Cyclerion
(“Second Merger Sub” and, together with First Merger Sub, the “Merger Subs”), and Korsana Biosciences, Inc., a Delaware corporation (“Korsana”) (as may be amended from time to time, the
“Merger Agreement”), pursuant to which, among other matters, and subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, (i) First Merger Sub will merge with and into Korsana, with Korsana
continuing as a wholly owned subsidiary of Cyclerion and the surviving corporation of the merger (the “First Merger”) and (ii) immediately following the First Merger and as part of the same overall transaction as the First
Merger, Korsana will merge with and into Second Merger Sub.
On August 3, 2026, Korsana published the following communication:
Korsana Biosciences Strengthens Leadership with Executive and Board Appointments to Support Next Phase of
Growth
Matthew Leoni, M.D., appointed Chief Medical Officer and
Gan Wei, Ph.D., appointed Chief Technical Officer
Heidi Henson appointed to Board of Directors and will serve as Chair of the Audit Committee
Leadership additions enhance clinical, technical and governance capabilities as Korsana advances lead program
KRSA-028 for the treatment of Alzheimer’s disease
WALTHAM, Mass., August 3, 2026—Korsana
Biosciences, Inc. (“Korsana” or the “Company”), a biotechnology company discovering and developing novel therapies to reduce the burden of neurodegenerative diseases, today announced the appointments of Matthew Leoni, M.D.,
as Chief Medical Officer, Gan Wei, Ph.D., as Chief Technical Officer, and Heidi Henson as a member of its Board of Directors, where she will serve as Chair of the Audit Committee. Collectively, these appointments strengthen Korsana’s
leadership team as the Company advances KRSA-028, its lead THETA-enabled therapeutic candidate for Alzheimer’s disease, toward clinical
development while continuing to progress its pipeline of potential best-in-class therapies for neurodegenerative diseases.
“We are delighted to welcome Matt, Gan, and Heidi to Korsana as we enter our next phase of growth,” said Jonathan Violin, Ph.D., President and
Chief Executive Officer of Korsana. “As Korsana advances toward becoming a clinical-stage company, we are assembling a leadership team with the expertise needed to execute our strategy and position Korsana for long-term success. Matt, Gan, and
Heidi each bring exceptional experience building and scaling innovative biotechnology organizations, and together they significantly strengthen our ability to advance KRSA-028 and realize the full potential of
our THETA platform for patients with neurodegenerative diseases.”
Korsana continues to
expect its previously announced merger with Cyclerion Therapeutics to close in the third quarter of 2026, subject to the satisfaction of customary closing conditions. Upon completion of the transaction, the combined company plans to operate under
the name Korsana Biosciences, Inc. and trade on Nasdaq under the ticker symbol “KRSA.” The Company is also advancing KRSA-028 toward the clinic, with Phase 1 healthy volunteer data expected in mid-2027 and interim proof-of-concept data evaluating amyloid plaque clearance in Alzheimer’s disease patients anticipated by the
end of 2027 or the first quarter of 2028.