Mersana Therapeutics, Inc. attracted an updated ownership filing showing that a former significant holder now reports no stake in the company’s common stock. A group of reporting persons — Nextech Crossover I SCSp, Nextech Crossover I GP S.a. r.l., Ian Charoub, Costas Constantinides, and Rocco Sgobbo — each report beneficial ownership of 0.00 shares of Mersana’s common stock, representing 0.0% of the class as of the event date of January 6, 2026.
The filing is an Amendment No. 3 to a Schedule 13G and confirms that each reporting person now owns 5% or less of Mersana’s outstanding common stock. The filers also certify that the securities referenced were not acquired and are not held for the purpose of changing or influencing control of Mersana Therapeutics, but instead are not related to any control-seeking transaction.
Positive
None.
Negative
None.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 3)
MERSANA THERAPEUTICS, INC.
(Name of Issuer)
Common Stock, $0.0001 par value per share
(Title of Class of Securities)
59045L205
(CUSIP Number)
01/06/2026
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)
SCHEDULE 13G
CUSIP No.
59045L205
1
Names of Reporting Persons
Nextech Crossover I GP S.a. r.l.
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
LUXEMBOURG
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
0.0 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP No.
59045L205
1
Names of Reporting Persons
Nextech Crossover I SCSp
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
LUXEMBOURG
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
0.0 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP No.
59045L205
1
Names of Reporting Persons
Ian Charoub
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
SWEDEN
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
0.0 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
CUSIP No.
59045L205
1
Names of Reporting Persons
Costas Constantinides
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
CYPRUS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
0.0 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
CUSIP No.
59045L205
1
Names of Reporting Persons
Rocco Sgobbo
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
SWITZERLAND
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
0.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
0.0 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
MERSANA THERAPEUTICS, INC.
(b)
Address of issuer's principal executive offices:
840 Memorial Drive, Cambridge, MA, 02139.
Item 2.
(a)
Name of person filing:
The names of the persons filing this report (collectively, the 'Reporting Persons') are:
Nextech Crossover I SCSp ('Nextech Crossover LP')
Nextech Crossover I GP S.a r.l. ('Nextech Crossover GP')
Ian Charoub ('Charoub')
Costas Constantinides ('Constantinides')
Rocco Sgobbo ('Sgobbo')
The Reporting Persons expressly disclaim status as a 'group' for purposes of this Schedule 13G.
(b)
Address or principal business office or, if none, residence:
8 rue Lou Hemmer
L-1748 Luxembourg-Findel
Grand-Duche de Luxembourg
(c)
Citizenship:
Nextech Crossover LP Luxembourg
Nextech Crossover GP Luxembourg
Charoub Sweden
Constantinides Cyprus
Sgobbo Switzerland
(d)
Title of class of securities:
Common Stock, $0.0001 par value per share
(e)
CUSIP No.:
59045L205
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
Row 9 of each Reporting Person's cover page to this Schedule 13G sets forth the aggregate number of shares of Common Stock beneficially owned by such Reporting Person and is incorporated by reference.
(b)
Percent of class:
Row 11 of each Reporting Person's cover page to this Schedule 13G sets forth the percentages of the shares of Common Stock beneficially owned by such Reporting Person and is incorporated by reference.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Row 5 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to vote or to direct the vote of Common Stock beneficially owned by such Reporting Person and is incorporated by reference.
(ii) Shared power to vote or to direct the vote:
Row 6 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to vote or to direct the vote of Common Stock beneficially owned by such Reporting Person and is incorporated by reference.
(iii) Sole power to dispose or to direct the disposition of:
Row 7 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to dispose or to direct the disposition of Common Stock beneficially owned by such Reporting Person and is incorporated by reference.
(iv) Shared power to dispose or to direct the disposition of:
Row 8 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to dispose or to direct the disposition of Common Stock beneficially owned by such Reporting Person and is incorporated by reference.
Item 5.
Ownership of 5 Percent or Less of a Class.
Ownership of 5 percent or less of a class
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
Not Applicable
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
Not Applicable
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.
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.
Nextech Crossover I GP S.a. r.l.
Signature:
/s/ Ian Charoub
Name/Title:
By Ian Charoub, Manager
Date:
01/09/2026
Signature:
/s/ Costas Constantinides
Name/Title:
By Costas Constantinides, Manager
Date:
01/09/2026
Nextech Crossover I SCSp
Signature:
/s/ Ian Charoub
Name/Title:
By Nextech Crossover I GP S.a r.l., its General Partner, By Ian Charoub, Manager
Date:
01/09/2026
Signature:
/s/ Costas Constantinides
Name/Title:
By Nextech Crossover I GP S.a r.l., its General Partner, By Costas Constantinides, Manager
Date:
01/09/2026
Ian Charoub
Signature:
/s/ Ian Charoub
Name/Title:
Ian Charoub
Date:
01/09/2026
Costas Constantinides
Signature:
/s/ Costas Constantinides
Name/Title:
Costas Constantinides
Date:
01/09/2026
Rocco Sgobbo
Signature:
/s/ Rocco Sgobbo
Name/Title:
Rocco Sgobbo
Date:
01/09/2026
Exhibit Information
Exhibit 99.1 Joint Filing Agreement (incorporated by reference to Exhibit 99.1 to the Reporting Persons' Schedule 13G/A filed with the SEC on December 26, 2024).
What does the latest Schedule 13G/A for Mersana Therapeutics (MRSN) report?
The Schedule 13G/A (Amendment No. 3) reports that Nextech Crossover I SCSp, Nextech Crossover I GP S.a. r.l., Ian Charoub, Costas Constantinides, and Rocco Sgobbo each beneficially own 0.00 shares of Mersana Therapeutics, Inc. common stock, representing 0.0% of the class as of January 6, 2026.
Who are the reporting persons in the Mersana Therapeutics (MRSN) Schedule 13G/A?
The reporting persons are Nextech Crossover I SCSp, Nextech Crossover I GP S.a. r.l., Ian Charoub, Costas Constantinides, and Rocco Sgobbo. They collectively refer to themselves as the "Reporting Persons" and each reports 0.0% beneficial ownership of Mersana’s common stock.
How much of Mersana Therapeutics’ common stock do the reporting persons currently own?
Each reporting person lists an aggregate amount beneficially owned of 0.00 shares of Mersana Therapeutics, Inc. common stock and a corresponding 0.0% of the outstanding class. They also report 0.00 shares for sole or shared voting and dispositive power.
Why is the Mersana Therapeutics (MRSN) Schedule 13G/A being amended?
This filing is labeled Amendment No. 3 to a Schedule 13G. It updates the ownership information to show that the reporting persons now own 5 percent or less of the class, with each reporting person at 0.0% beneficial ownership.
Does this Schedule 13G/A indicate an attempt to influence control of Mersana Therapeutics?
No. The certification states that the securities referred to were not acquired and are not held for the purpose or effect of changing or influencing the control of Mersana Therapeutics, Inc., and are not held in connection with any transaction having that purpose or effect, other than activities solely in connection with a nomination under Rule 240.14a-11.
What type of security is covered in this Mersana Therapeutics ownership filing?
The filing covers common stock of Mersana Therapeutics, Inc., with a par value of $0.0001 per share, identified by CUSIP number 59045L205.
