Initial Statement of Beneficial Ownership (Form 3)

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person * Leoni Matthew James 2. Date of Event Requiring Statement (Month/Day/Year) 09/08/2026 3. Issuer Name and Ticker or Trading Symbol Korsana Biosciences, Inc. [KRSA] (Last) (First) (Middle) C/O KORSANA BIOSCIENCES, INC., 203 CRESCENT STREET, SUITE 503 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Medical Officer 5. If Amendment, Date Original Filed (Month/Day/Year) (Street) WALTHAM, MA 02453 6. Individual or Joint/Group Filing (Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	(1)(2)	06/07/2036	Common Stock	253,415	$7.48	D
Stock Option (Right to Buy)	(1)(3)	06/29/2036	Common Stock	394,314	$8.06	D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Leoni Matthew James C/O KORSANA BIOSCIENCES, INC. 203 CRESCENT STREET, SUITE 503 WALTHAM, MA 02453			Chief Medical Officer

Signatures

/s/ Mark Vignola, as attorney-in-fact for Matthew Leoni		09/10/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Effective as of September 8, 2026 (the "Effective Time"), (i) Cariboos Merger Sub Corp., a wholly owned subsidiary of Cyclerion Therapeutics, Inc. ("Cyclerion"), merged with and into Korsana Biosciences, Inc. ("Pre-Merger Korsana"), with Pre-Merger Korsana continuing as a wholly owned subsidiary of Cyclerion and the surviving corporation of the merger (the "First Merger"), and (ii) immediately thereafter, Pre-Merger Korsana merged with and into Cariboos Merger Sub II, LLC, a second wholly owned subsidiary of Cyclerion ("Second Merger Sub"), with Second Merger Sub being the surviving entity of the merger under the name Korsana Biosciences Operating Company, LLC (the "Second Merger" and, together with the First Merger, the "Merger"). At the Effective Time, Cyclerion changed its name to "Korsana Biosciences, Inc." (hereinafter, the "Issuer").
(2)	Represents options to purchase shares of the Issuer's common stock received by the Reporting Person in the Merger in exchange for options of Pre-Merger Korsana held by the Reporting Person prior to the Merger. This option will vest as to 25% on June 8, 2027 and in equal monthly installments thereafter through June 8, 2030, subject to the Reporting Person's continued service to the Issuer on each such vesting date.
(3)	Represents options to purchase shares of the Issuer's common stock received by the Reporting Person in the Merger in exchange for options of Pre-Merger Korsana held by the Reporting Person prior to the Merger. This option will vest as to 25% on June 18, 2027 and in equal monthly installments thereafter through June 18, 2030, subject to the Reporting Person's continued service to the Issuer on each such vesting date.
Remarks: Exhibit 24 - Power of Attorney

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure. Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.