Cyclerion Halts CYC-126 Work and Aims for Third-Quarter Korsana Close
The company said cash limits have suspended its treatment-resistant depression program as it targets a third-quarter 2026 merger close.
Cyclerion Therapeutics (CYCN), a biotechnology company focused on neuropsychiatric therapeutics, said cash limitations have suspended efforts to advance an integrated clinical, regulatory, and commercial strategy for CYC-126, its individualized therapy for treatment-resistant depression.
That pause replaced language in the prior annual report that the program team was currently advancing that strategy. The company licensed Massachusetts Institute of Technology intellectual property supporting the program in September 2025 and entered a collaboration and option-to-license agreement with Medsteer SAS covering anesthesia delivery and monitoring technology in January 2026.
The defining development of the quarter was the company’s decision to stop spending on that program while it waits to close a merger that will make Korsana’s neurodegenerative-disease business the primary operation. Cyclerion anticipates the merger will close in the third quarter of 2026, subject to shareholder approvals and other customary conditions, and said current cash and cash equivalents are expected to fund operating expenses until that closing.
On April 1, 2026, Cyclerion entered a Plan of Merger and Reorganization with Korsana Biosciences, Inc., a privately held biotechnology company. After closing, Korsana will become a wholly owned subsidiary, the surviving entity will be renamed Korsana Biosciences Operating Company, LLC, and Cyclerion will change its name to Korsana Biosciences, Inc.
In connection with the merger, Korsana agreed on the same date to sell shares and pre-funded warrants to institutional and accredited investors for an aggregate purchase price of approximately $380.0 million immediately before closing. Those securities will convert into Cyclerion common stock and pre-funded warrants at the exchange ratio.
The estimated exchange ratio rose to approximately 1.4735 shares of Cyclerion common stock per share of Korsana common stock and Series A preferred stock, from approximately 1.1009 in the prior quarterly report. The new estimate uses Cyclerion capitalization as of June 30, 2026, and assumes Cyclerion net cash at closing of $(2.5) million, versus a $0 net-cash assumption and earlier capitalization dates. The ratio does not give effect to a proposed reverse stock split and remains subject to adjustment based on estimated net cash at closing.
Research and development expenses fell to $0 for the three months ended June 30, 2026, from $730 thousand in the three months ended March 31, 2026. Personnel and related internal costs were $0 versus $7 thousand, and other R&D costs were $0 versus $723 thousand.
The company continues to seek opportunities to monetize legacy soluble guanylate cyclase stimulator assets, including collaborations, licenses, or other strategic transactions. Pre-merger shareholders will receive one contingent value right for each outstanding share of Cyclerion common stock and Series A preferred stock, entitling holders to certain net proceeds, if any, from dispositions of pre-merger legacy assets, including the Akebia praliciguat license and Tisento equity interests, over specified windows after closing.
Praliciguat remains licensed to Akebia Therapeutics. Under a 2024 amendment, a $1.0 million development milestone was due upon initiation of a U.S. Phase 2 trial; that payment was received in February 2026. Cyclerion is eligible for additional milestone cash payments of up to approximately $557.5 million related to the future development, regulation, and commercialization of praliciguat, plus higher-tiered sales-based royalties ranging from mid-single digits to twenty percent.
Olinciguat’s option agreement was terminated in October 2025 after the parties could not agree on a definitive license; the company is exploring potential license opportunities. Zagociguat and CY3018 were sold to Tisento in 2023. Tisento completed enrollment in its global Phase 2b PRIZM study of zagociguat in MELAS in January 2026, after the FDA granted Fast Track designation in June 2025.
Cyclerion could use its capital resources sooner than it expects, and the cash-to-close estimate rests on assumptions that may prove to be wrong.