EX-99.1

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EX-99.1

EX-99.1

Exhibit 99.1

Korsana Biosciences Completes Closing of Merger with Cyclerion Therapeutics and Previously Announced Private Placement of $380 Million

Advancing lead program KRSA-028

toward the clinic, with Phase 1 healthy volunteer data expected mid-2027 and interim proof-of-concept data in Alzheimer’s patients anticipated by year-end 2027 or first quarter of 2028

Strong financial position with post-transaction cash and cash equivalents of approximately $475 million1 expected to fund operations into 2029

Shares to begin trading on Nasdaq under ticker symbol “KRSA” on September 9

WALTHAM, Mass., Sept. 08, 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 completion of its previously announced merger with Cyclerion Therapeutics, Inc. (“Cyclerion”). The combined company will operate under the name Korsana Biosciences, Inc., and its shares are expected to begin trading on the Nasdaq Capital Market on September 9, 2026, under the ticker symbol “KRSA.”

Immediately prior to the closing of the merger, Korsana completed a previously announced private financing of $380 million in gross proceeds from a syndicate of new and existing investors led by Fairmount and Venrock Healthcare Capital Partners, with participation from General Atlantic, TCGX, Forbion, Wellington Management, Commodore Capital, RA Capital Management, RTW Investments, Vivo Capital, Janus Henderson Investors, Foresite Capital, J.P. Morgan Life Sciences Private Capital, SR One, Sanofi Ventures, Kalehua Capital, Spruce Street Capital, and other leading investment management firms. The financing includes common stock and pre-funded warrants to purchase additional shares of common stock. This financing, together with existing cash, is expected to support the Company’s operations into 2029, including through multiple clinical milestones for KRSA-028.

Pursuant to the terms of the previously disclosed merger agreement, each outstanding share of Korsana common stock was converted into the right to receive approximately 0.2074 shares of common stock of the combined company, as adjusted for the reverse stock split of Cyclerion Therapeutics’ common stock at a ratio of 1-for-7 shares, effected immediately prior to the merger. The new CUSIP number for the combined company following the reverse stock split and merger is 23255M303. Following the completion of the reverse stock split, the private placement, and the merger, there are approximately 55.1 million shares of the combined company’s common stock and common stock equivalents outstanding, including shares of common stock underlying pre-funded warrants and Series B convertible preferred stock, and excluding shares underlying equity awards.

“Today marks the beginning of an exciting new chapter for Korsana. With an exceptional team, a strong financial foundation supported by leading biotechnology investors, and a pipeline of differentiated therapeutic candidates, we are well positioned to execute on our long-term vision,” said Jonathan Violin, Ph.D., Korsana’s President and Chief Executive Officer. “As we advance KRSA-028 toward the clinic, we remain focused on our mission to reduce the burden of neurodegenerative diseases by bringing forward innovative therapies for patients and caregivers.”

KRSA-028 is an investigational, next-generation shuttled antibody targeting amyloid beta for

the treatment of Alzheimer’s disease. KRSA-028 leverages the proprietary Therapeutic Targeting (THETA™) technology platform, which combines clinically validated transferrin receptor (TfR1) and Fc engineering and is designed to improve brain delivery, safety, and convenience. The Company is 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.

About Korsana Biosciences

Korsana Biosciences is committed to building best-in-class therapeutics with

the goal of reducing the burden of neurodegenerative diseases for patients and caregivers. The Company’s lead program, KRSA-028, is a next-generation shuttled antibody targeting amyloid beta for the treatment of Alzheimer’s disease. KRSA-028 leverages Therapeutic Targeting (THETA™), a novel CNS shuttle technology developed in partnership with Paragon Therapeutics and designed to enable dramatically higher drug concentrations in the brain and overcome the limitations of earlier shuttle technologies. In addition, Korsana is advancing a pipeline of innovative therapies for neurodegenerative diseases. For more information, please visit www.korsana.com and follow the Company on LinkedIn.

Forward-Looking Statements

Certain statements in this press release, other than purely historical information