SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549

SCHEDULE 13D Under the Securities Exchange Act of 1934

Korsana Biosciences, Inc. (Name of Issuer)

Common Stock, no par value per share (Title of Class of Securities)

(CUSIP Number)

Sherman G. Souther Venrock, 3340 Hillview Avenue Palo Alto, CA, 94304 (650) 561-9580 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

09/08/2026 (Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No.

1	Name of reporting person Venrock Healthcare Capital Partners III, L.P.
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) PN

SCHEDULE 13D

CUSIP No.

1	Name of reporting person VHCP Co-Investment Holdings III, LLC
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) OO

SCHEDULE 13D

CUSIP No.

1	Name of reporting person Venrock Healthcare Capital Partners EG, L.P.
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) PN

SCHEDULE 13D

CUSIP No.

1	Name of reporting person Venrock Healthcare Capital Partners XP, L.P.
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) PN

SCHEDULE 13D

CUSIP No.

1	Name of reporting person VHCP Management III, LLC
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) OO

SCHEDULE 13D

CUSIP No.

1	Name of reporting person VHCP Management EG, LLC
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) OO

SCHEDULE 13D

CUSIP No.

1	Name of reporting person VHCP Management XP, LLC
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) OO

SCHEDULE 13D

CUSIP No.

1	Name of reporting person Bong Y. Koh
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) IN

SCHEDULE 13D

CUSIP No.

1	Name of reporting person Nimish Shah
2	Check the appropriate box if a member of a Group (See Instructions)   (a)   (b)
3	SEC use only
4	Source of funds (See Instructions) WC
5	Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
6	Citizenship or place of organization UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:	7 Sole Voting Power 0.00 8 Shared Voting Power 4,552,277.00 9 Sole Dispositive Power 0.00 10 Shared Dispositive Power 4,552,277.00
11	Aggregate amount beneficially owned by each reporting person 4,552,277.00
12	Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
13	Percent of class represented by amount in Row (11) 9.9 %
14	Type of Reporting Person (See Instructions) IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, no par value per share
(b)	Name of Issuer: Korsana Biosciences, Inc.
(c)	Address of Issuer's Principal Executive Offices: 245 First Street, 18th Floor, Cambridge, MASSACHUSETTS , 02142.
Item 2.	Identity and Background
(a)	This Schedule 13D is being filed on behalf of Venrock Healthcare Capital Partners III, L.P. ("VHCP III"), VHCP Co-Investment Holdings III, LLC ("VHCP Co-Investment III"), Venrock Healthcare Capital Partners EG, L.P. ("VHCP EG"), Venrock Healthcare Capital Partners XP, L.P. ("VHCP XP"), VHCP Management III, LLC ("VHCP Management III"), VHCP Management EG, LLC ("VHCP Management EG"), VHCP Management XP, LLC ("VHCP Management XP"), Bong Koh ("Koh") and Nimish Shah ("Shah"). The foregoing entities and individuals are collectively referred to herein as the "Reporting Persons." The agreement among the Reporting Persons to file this Schedule 13D jointly in accordance with Rule 13d-1(k) of the Act is attached hereto as Exhibit 99.1.
(b)	The address of the principal business office of each of the Reporting Persons is: New York Office 7 Bryant Park, 23rd Floor, New York, NY 10018 Palo Alto Office 3340 Hillview Avenue, Palo Alto, CA 94304
(c)	The principal business of each of the entities, Shah and Koh is the venture capital investment business.
(d)	During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).
(e)	During the last five years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree of final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	All of the entities were organized in Delaware. Shah and Koh are both United States citizens.
Item 3.	Source and Amount of Funds or Other Consideration
	On September 8, 2026, the Issuer completed the transactions contemplated by the Agreement and Plan of Merger, dated April 1, 2026, by and among the Issuer (which was formerly known as Cyclerion Therapeutics, Inc.), Cariboos Merger Sub Corp., a Delaware corporation and wholly owned subsidiary of Cyclerion, Cariboos Merger Sub II, LLC, a Delaware limited liability company and wholly owned subsidiary of the Issuer, and Korsana Biosciences, Inc., a private Delaware corporation ("Old Korsana" and such transaction, the "Merger"). In connection with the closing of the Merger, the Issuer changed its name to Korsana Biosciences, Inc. Between November 2024 and the closing of the Merger, the Reporting Persons had collectively purchased from Old Korsana, in a series of private offerings, an aggregate of 10,000,000 shares of Series Seed preferred stock, 37,871,909 shares of Series A preferred stock, 21,936,295 shares of common stock and pre-funded warrants to purchase 15,935,614 shares of common stock for an aggregate purchase price of $134,843,200 (collectively, the "Old Korsana Securities"). At the effective time of the Merger, (i) each then-outstanding share of Old Korsana common stock was converted into shares of the Issuer's common stock equal to 0.2074 for each share of Old Korsana common stock (the "Exchange Ratio"), (ii) each then-outstanding share of Old Korsana Series Seed preferred stock was converted into shares of the Issuer's Series B non-voting preferred stock, equal to the Exchange Ratio divided by 1,000, (iii) each then-outstanding share of Old Korsana Series A preferred stock was converted into shares of the Issuer's common stock equal to the Exchange Ratio, and (iv) each then-outstanding pre-funded warrant to purchase Old Korsana common stock that was converted into a pre-funded warrant to purchase the Issuer's common stock equal to the Exchange Ratio. All purchases of the Old Korsana Securities described above were for cash and were funded by working capital of VHCP III, VHCP Co-Investment III, VHCP EG and VHCP XP.
Item 4.	Purpose of Transaction
	The Reporting Persons purchased the aforementioned securities for investment purposes with the aim of increasing the value of their investments and the Issuer. Subject to applicable legal requirements, one or more of the Reporting Persons may purchase additional securities of the Issuer from time to time in open market or private transactions, depending on its evaluation of the Issuer's business, prospects and financial condition, the market for the Issuer's securities, other developments concerning the Issuer, the reaction of the Issuer to the Reporting Persons' ownership of the Issuer's securities, other opportunities available to the Reporting Persons, and general economic, money market and stock market conditions. In addition, depending upon the factors referred to above, the Reporting Persons may dispose of all or a portion of their securities of the Issuer at any time (including by means of programs adopted pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934 (the "Act")). Each of the Reporting Persons reserves the right to increase or decrease its holdings on such terms and at such times as each may decide. Except as set forth in this Item 4 and Item 6 below, none of the Reporting Persons has a present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D of the Act. However, each of the Reporting Persons reserves the right to propose or participate in future transactions which may result in one or more of such actions, including but not limited to, an extraordinary corporate transaction, such as a merger, reorganization or liquidation, sale of a material amount of assets of the Issuer or its subsidiaries, or other transactions which might have the effect of causing the common stock to become eligible for termination of registration under Section 12(g) of the Act. The Reporting Persons also retain the right to change their investment intent at any time, to acquire additional shares of common stock or other securities of the Issuer from time to time, or to sell or otherwise dispose of all or part of the common stock beneficially owned by them (or any shares of common stock into which such securities are converted) in any manner permitted by law. The Reporting Persons may engage from time to time in ordinary course transactions with financial institutions with respect to the securities described herein. Shah and Andrew Gottesdiener, each a partner of Venrock, are members of the board of directors of the Issuer. As a director of the Issuer, each of Messrs. Shah and Gottesdiener may have influence over the corporate activities of the Issuer, including activities which may relate to the transactions described in clauses (a) through (j) of Item 4 of Schedule 13D.
Item 5.	Interest in Securities of the Issuer
(a)	Rows 11 and 13 of each Reporting Person's cover page to this Schedule 13D set forth the aggregate number of shares of common stock of the Issuer and percentage of the shares of common stock of the Issuer beneficially owned by such Reporting Person and are incorporated herein by reference. Due to the Beneficial Ownership Blocker described below, each Reporting Person's beneficial ownership percentage is 9.995%. Such percentage is based upon the sum of (i) 45,541,425 shares of common stock outstanding upon the closing of the Merger, as reported in the Issuer's Current Report on Form 8-K, filed with the Securities and Exchange Commission (the "SEC") on September 11, 2026 and (ii) 2,692 shares of common stock issuable upon exercise of stock options held by Shah that will vest within 60 days of the date of this filing. Due to field limitations of the EDGAR filing system, the percentages listed in Row 11 of the Reporting Persons' cover pages have been rounded down to 9.9%. The Reporting Persons' ownership of the Issuer's securities consists of: (i) 1,385,432 shares of common stock, 130 shares of Series B preferred stock (the "Series B Preferred") and pre-funded warrants (the "Pre-Funded Warrants") exercisable for up to 1,006,446 shares of common stock held by VHCP III; (ii) 138,542 shares of common stock, 13 shares of Series B Preferred and Pre-Funded Warrants exercisable for up to 100,644 shares of common stock held by VHCP Co-Investment III; (iii) 2,024,520 shares of common stock, 935 shares of Series B Preferred and Pre-Funded Warrants exercisable for up to 1,470,712 shares of common stock held by VHCP EG; (iv) 1,001,091 shares of common stock, 830 shares of Series B Preferred and Pre-Funded Warrants exercisable for up to 727,242 shares of common stock held by VHCP XP; and (v) stock options exercisable for up to 48,455 shares of common stock held by Shah. Each share of Series B Preferred is convertible, at the option of the holder, into 1,000 shares of common stock. Each of the Series B Preferred and Pre-Funded Warrants contains a provision (the "Beneficial Ownership Blockers") which precludes conversion of the Series B Preferred and/or exercise of the Pre-Funded Warrants to the extent that, following conversion and/or exercise, VHCP III, VHCP Co-Investment III, VHCP EG and VHCP XP, together with their affiliates and other attribution parties, would own more than 9.99% of the outstanding shares of common stock. Each of VHCP III, VHCP Co-Investment III, VHCP EG and VHCP XP is currently prohibited from converting Series B Preferred and/or exercising Pre-Funded Warrants by virtue of the Beneficial Ownership Blockers. VHCP Management III is the general partner of VHCP III and the manager of VHCP Co-Investment III. VHCP Management EG is the general partner of VHCP EG. VHCP Management XP is the general partner of VHCP XP. Messrs. Shah and Koh are the voting members of VHCP Management III, VHCP Management EG and VHCP Management XP.
(b)	Rows 7 through 10 of each Reporting Person's cover page to this Schedule 13D set forth the number of shares of common stock of the Issuer as to which such Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition and are incorporated herein by reference.
(c)	Except as set forth herein, none of the Reporting Persons has effected any transactions with respect to the securities of the Issuer during the past sixty days.
(d)	No other person is known to have the right to receive or the power to direct the receipt of dividends from, or any proceeds from the sale of, the securities beneficially owned by any of the Reporting Persons.
(e)	Not applicable.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Pre-Funded Warrants The Pre-Funded Warrants have an exercise price per share equal to $0.0001 (as adjusted from time to time as provided in the form of Pre-Funded Warrant) and may be exercised at any time and from time to time, subject to the Beneficial Ownership Blocker described below. The Pre-Funded Warrants do not expire. The exercise price may be paid in cash or, at the election of the holder, on a cashless basis. The Pre-Funded Warrants are transferable, in whole or in part, subject to compliance with applicable securities laws. Holders of Pre-Funded Warrants are not entitled to vote, receive dividends or exercise any other rights as a stockholder of the Issuer with respect to the underlying shares of common stock prior to exercise. Neither VHCP III, VHCP Co-Investment III, VHCP EG nor VHCP XP may exercise any portion of a Pre-Funded Warrant to the extent that, immediately prior to or after giving effect to such exercise, the holder, together with its attribution parties, would beneficially own shares of the Issuer's common stock in excess of 9.99% of the shares of the Issuer's common stock outstanding immediately following such exercise. A holder may, upon written notice to the Issuer, increase or decrease the Beneficial Ownership Blocker applicable to its Pre-Funded Warrants to any other percentage not in excess of 19.99%, provided that any increase will not be effective until the sixty-first (61st) day after such notice is delivered to the Issuer. The foregoing description of the Pre-Funded Warrants is not complete and is subject to and qualified in its entirety by reference to the complete text of the form of Pre-Funded Warrant, which is filed as Exhibit 99.2 to this Schedule 13D and is incorporated herein by reference. Lock-up Agreements Certain of Old Korsana's executive officers, directors, including Shah, and stockholders, including VHCP III, VHCP Co-Investment III, VHCP EG and VHCP XP, entered into lock-up agreements (the "Lock-Up Agreements"), pursuant to which such parties have agreed not to, except in limited circumstances, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend or otherwise transfer or dispose of, directly or indirectly, any shares of the Issuer's common stock or any securities convertible into or exercisable or exchangeable for the Issuer's common stock, currently or thereafter owned, including shares of the Issuer's common stock issuable upon conversion of the Issuer's Series B Preferred, but excluding, as applicable, shares purchased by existing Old Korsana shareholders pursuant to the terms of the Securities Purchase Agreement dated April 1, 2026 (including any shares of the Issuer's common stock issuable upon exercise of Pre-Funded Warrants issued in exchange for pre-funded warrants to purchase shares of Old Korsana common stock sold thereunder), until 180 days after the closing of the Merger. The foregoing description of the Lock-Up Agreements is not complete and is subject to and qualified in its entirety by reference to the complete text of the form of Lock-up Agreement, which is filed as Exhibit 99.3 to this Schedule 13D and incorporated by reference herein. Equity Awards Shah was granted a stock option to purchase 48,455 shares of the Issue's common stock on September 9, 2026 and may be granted other equity awards by the Issuer in the future. Under an agreement between the Reporting Person and Venrock Management, LLC, an investment advisor to and an affiliate of certain Reporting Persons (the "Management Company"), Shah is deemed to hold the such equity award and the shares underlying such equity awards for the sole benefit of the Management Company and must exercise such equity awards solely upon the direction of the Management Company, which is entitled to the shares underlying such equity awards.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 24.1 Power of Attorney for Bong Koh, dated September 15, 2026. Exhibit 24.2 Power of Attorney for Nimish Shah, dated September 15, 2026. Exhibit 99.1 Joint Filing Agreement. Exhibit 99.2 Form of Pre-Funded Warrant (incorporated by reference to Exhibit 4.2 to the Issuer's Current Report on Form 8-K (File No. 001-38787), filed with the SEC on September 11, 2026). Exhibit 99.3 Form of Lock-Up Agreement (incorporated by reference to Exhibit 10.5 to Cyclerion Therapeutics, Inc.'s Current Report on Form 8-K (File No. 001-38787), filed with the SEC on April 1, 2026).

SIGNATURE
	After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Venrock Healthcare Capital Partners III, L.P.

Signature: /s/ Sherman G. Souther Name/Title: By VHCP Management III, LLC, its General Partner, By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

VHCP Co-Investment Holdings III, LLC

Signature: /s/ Sherman G. Souther Name/Title: By VHCP Management III, LLC, its Manager, By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

Venrock Healthcare Capital Partners EG, L.P.

Signature: /s/ Sherman G. Souther Name/Title: By VHCP Management EG, LLC, its General Partner, By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

Venrock Healthcare Capital Partners XP, L.P.

Signature: /s/ Sherman G. Souther Name/Title: By VHCP Management XP, LLC, its General Partner, By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

VHCP Management III, LLC

Signature: /s/ Sherman G. Souther Name/Title: By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

VHCP Management EG, LLC

Signature: /s/ Sherman G. Souther Name/Title: By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

VHCP Management XP, LLC

Signature: /s/ Sherman G. Souther Name/Title: By Sherman G. Souther, Authorized Signatory Date: 09/15/2026

Bong Y. Koh

Signature: /s/ Sherman G. Souther Name/Title: By Sherman G. Souther, Attorney-in-fact Date: 09/15/2026

Nimish Shah

Signature: /s/ Sherman G. Souther Name/Title: By Sherman G. Souther, Attorney-in-fact Date: 09/15/2026

EXHIBIT 24.1

POWER OF ATTORNEY

KNOW ALL BY THESE PRESENTS, that the undersigned hereby constitutes and appoints each of Jessica Baron, Evan W. Neu and Sherman G. Souther, Jr., signing individually, the undersigned’s true and lawful attorney-in fact and agent to:

(i)

prepare, execute and file, for and on behalf of the undersigned, any and all documents and filings that are required or advisable to be made with the United States Securities and Exchange Commission, any stock exchange or similar authority, under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations promulgated thereunder, including without limitation (a) any Joint Filing Agreement under Rule 13d-1(k) of the Exchange Act (or any successor provision thereunder), Schedule 13D and Schedule 13G (or any successor schedules or forms adopted under the Exchange Act) and any amendments thereto in accordance with Section 13 of the Exchange Act and the rules thereunder, and (b) Forms 3, 4 and 5 and any amendments thereto in accordance with Section 16(a) of the Exchange Act and the rules thereunder; and

(ii)

take any other action of any nature whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact’s discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted.  The undersigned acknowledges that the foregoing attorney-in-fact, in serving in such capacity at the request of the undersigned, is not assuming, nor is Venrock assuming, any of the undersigned’s responsibilities to comply with the Exchange Act, including without limitation Sections 13 and 16 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the earliest to occur of (a) the undersigned is no longer required to file any form or document with respect to the undersigned’s holdings of and transactions in securities issued by a company, (b) revocation by the undersigned in a signed writing delivered to the foregoing attorney-in-fact or (c) until such attorney-in-fact shall no longer be employed by Venrock.

IN WITNESS WHEREOF, the undersigned has cause this Power of Attorney to be executed as of this 15th day of September 15, 2026.

/s/ Bong Koh

Bong Koh

EXHIBIT 24.2

POWER OF ATTORNEY

KNOW ALL BY THESE PRESENTS, that the undersigned hereby constitutes and appoints each of Jessica Baron, Evan W. Neu and Sherman G. Souther, Jr., signing individually, the undersigned’s true and lawful attorney-in fact and agent to:

(i)

prepare, execute and file, for and on behalf of the undersigned, any and all documents and filings that are required or advisable to be made with the United States Securities and Exchange Commission, any stock exchange or similar authority, under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations promulgated thereunder, including without limitation (a) any Joint Filing Agreement under Rule 13d-1(k) of the Exchange Act (or any successor provision thereunder), Schedule 13D and Schedule 13G (or any successor schedules or forms adopted under the Exchange Act) and any amendments thereto in accordance with Section 13 of the Exchange Act and the rules thereunder, and (b) Forms 3, 4 and 5 and any amendments thereto in accordance with Section 16(a) of the Exchange Act and the rules thereunder; and

(ii)

take any other action of any nature whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit, in the best interest of, or legally required by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in such attorney-in-fact’s discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact’s substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted.  The undersigned acknowledges that the foregoing attorney-in-fact, in serving in such capacity at the request of the undersigned, is not assuming, nor is Venrock assuming, any of the undersigned’s responsibilities to comply with the Exchange Act, including without limitation Sections 13 and 16 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the earliest to occur of (a) the undersigned is no longer required to file any form or document with respect to the undersigned’s holdings of and transactions in securities issued by a company, (b) revocation by the undersigned in a signed writing delivered to the foregoing attorney-in-fact or (c) until such attorney-in-fact shall no longer be employed by Venrock.

IN WITNESS WHEREOF, the undersigned has cause this Power of Attorney to be executed as of this 15th day of September 15, 2026.

/s/ Nimish Shah

Nimish Shah

EXHIBIT 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the common stock of Korsana Biosciences, Inc. and further agree that this agreement be included as an exhibit to such filing. Each party to the agreement expressly authorizes each other party to file on its behalf any and all amendments to such statement. Each party to this agreement agrees that this joint filing agreement may be signed in counterparts.

In evidence whereof, the undersigned have caused this Agreement to be executed on their behalf this 15th day of September, 2026.