Form SCHEDULE 13D/A Werewolf Therapeutics, Filed by: MPM BioVentures 2014, L.P.
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549 |
SCHEDULE 13D
Under the Securities Exchange Act of 1934
(Amendment No. 6)*
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WEREWOLF THERAPEUTICS, INC. (Name of Issuer) |
Common Stock (Title of Class of Securities) |
(CUSIP Number) |
Ansbert Gadicke c/o MPM BioImpact LLC, 339 Boylston Street, Suite 1100 Boston, MA, 02116 617-425-9200 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) |
05/01/2026 (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
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| CUSIP No. |
| 1 |
Name of reporting person
MPM BioVentures 2014, 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: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,131,359.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
2.3 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM BioVentures 2014 (B), 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
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
75,458.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
0.2 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM Asset Management Investors BV2014 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: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
38,939.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
0.1 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
UBS Oncology Impact Fund 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
CAYMAN ISLANDS
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
936,031.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.9 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM BioVentures 2014 GP 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
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,206,817.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
2.5 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM BioVentures 2014 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
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
1,245,756.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
2.6 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Oncology Impact Fund (Cayman) Management 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
CAYMAN ISLANDS
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
936,031.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.9 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM BioImpact 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
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
936,031.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.9 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
ANSBERT GADICKE | ||||||||
| 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)
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| 6 | Citizenship or place of organization
UNITED STATES
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
2,608,501.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
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| 13 | Percent of class represented by amount in Row (11)
5.4 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
LUKE EVNIN | ||||||||
| 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)
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| 6 | Citizenship or place of organization
UNITED STATES
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
1,672,470.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
3.4 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Todd Foley | ||||||||
| 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)
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| 6 | Citizenship or place of organization
UNITED STATES
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
1,245,756.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
2.6 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM ASSET MANAGEMENT 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
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
179,188.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
0.4 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM ONCOLOGY INNOVATIONS FUND LP | ||||||||
| 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)
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| 6 | Citizenship or place of organization
DELAWARE
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| Number of Shares Beneficially Owned by Each Reporting Person With: |
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| 11 | Aggregate amount beneficially owned by each reporting person
247,526.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
0.5 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
MPM Oncology Innovations Fund GP 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: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
247,526.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
0.5 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
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| Item 1. | Security and Issuer | |
| (a) | Title of Class of Securities:
Common Stock | |
| (b) | Name of Issuer:
WEREWOLF THERAPEUTICS, INC. | |
| (c) | Address of Issuer's Principal Executive Offices:
200 TALCOTT AVENUE, 2ND FLOOR, WATERTOWN,
MASSACHUSETTS
, 02472. | |
Item 1 Comment:
Explanatory Note: This Amendment No. 6 to Schedule 13D ("Amendment No. 6") is being filed as an amendment to the initial statement on Schedule 13D relating to the common stock (the "Common Stock"), of Werewolf Therapeutics Inc. (the 'Issuer'), as filed with the Securities and Exchange Commission (the "SEC") on May 14, 2021 and as amended by Amendment No. 1 filed November 4, 2025, Amendment No. 2 filed November 17, 2025, Amendment No. 3 filed December 3, 2025, Amendment No. 4 filed December 29, 2025 and Amendment No. 5 filed January 16, 2026 (as amended, the "Original Schedule 13D"). This Schedule 13D/A is being filed by the Filing Persons to report the open market sales of the Issuer's Common Stock by certain Filing Persons.
Items 5 and 7 of the Original Schedule 13D are hereby amended and supplemented to the extent hereinafter expressly set forth and, except as amended and supplemented hereby, the Original Schedule 13D remains in full force and effect. All capitalized terms used in this Amendment No. 6 but not defined herein shall have the meanings ascribed thereto in the Original Schedule 13D.
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| Item 5. | Interest in Securities of the Issuer | |
| (a) | See rows (11) and (13) of the Filing Persons Owner Profile of this Amendment No. 6 for the aggregate number of Common Stock and percentages of the shares of Common Stock beneficially owned by the Filing Person.
The Common Stock is held as follows:
* 1,131,359 shares are held directly by BV 2014;
* 75,458 shares are held directly by BV 2014(B);
* 38,939 shares are held directly by AM BV2014 LLC;
* 247,526 shares are held directly by MPM OIF;
* 179,188 shares by AM LLC; and
* 936,031 shares are held directly by UBS Oncology.
BV 2014 GP and BV 2014 LLC are the direct and indirect general partners of BV 2014 and BV 2014(B) and, accordingly, may be deemed to beneficially own the shares held by BV 2014 and BV 2014(B).
BV 2014 LLC is the managing member of AM BV2014 LLC and, accordingly, may be deemed to beneficially own the shares held by AM BV2014 LLC.
MPM OIF GP is the general Partner of MPM OIF and, accordingly, may be deemed to beneficially own the shares held by MPM OIF.
BioImpact and Oncology Cayman are the direct and indirect general partners of UBS Oncology and, accordingly, may be deemed to beneficially own the shares held by UBS Oncology.
Drs. Gadicke and Evnin and Mr. Foley are the managing directors of BV 2014 LLC and, accordingly, may be deemed to beneficially own the shares held by BV 2014, BV 2014(B) and AM BV2014 LLC.
Drs. Gadicke and Evnin are the members of AM LLC and managers of MPM OIF GP and, accordingly, may be deemed to beneficially own the shares held by AM LLC and MPM OIF.
Dr. Gadicke is the managing partner of BioImpact and, accordingly may be deemed to beneficially own the shares held by UBS Oncology.
Calculation of the percentage of the shares of Common Stock beneficially owned is based upon 48,596,817 shares of Common Stock outstanding as of March 20, 2026, as reported in the Issuer's Form 10-K filed with the SEC on March 27, 2026.
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| (b) | See rows (7) through (10) of the Filing Persons Owner Profile of this Amendment No. 6 for the number of shares as to which there is sole power to vote or to direct the vote, sole power to dispose or to direct the disposition, or shared power to dispose or to direct the disposition. | |
| (c) | The Reporting Persons sold the following Common Stock in the open market in the last 60 days:
Date of Price Range Ave. Price Sold by Sold by Sold By Sold by Sold by Sold by
Sale BV 2014 BV AM BV2014 MPM OIF AM LLC UBS
2014(B) LLC Oncology
04/27/26 $0.818-$0.8788 $0.85 36,488 2,434 1,256 7,983 5,779 30,188
04/28/26 $0.673-$0.82 $0.73 64,541 4,305 2,222 14,121 10,223 53,400
04/29/26 $0.68-$0.75 $0.69 38,259 2,552 1,317 8,371 6,060 31,654
04/30/26 $0.688-$0.7458 $0.72 113,821 7,592 3,918 24,903 18,028 94,172
05/01/26 $0.7011-$0.74 $0.73 39,501 2,635 1,360 8,642 6,256 32,682
05/04/26 $0.69-$0.7497 $0.72 32,455 2,164 1,117 7,098 5,139 26,843
05/05/26 $0.6616-$0.7253 $0.69 4,640 310 160 1,015 735 3,840
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| (d) | Inapplicable. | |
| (e) | Inapplicable. | |
| Item 7. | Material to be Filed as Exhibits. | |
Exhibit 99.C - Joint Filing Statement | ||
| 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.
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ATTACHMENTS / EXHIBITS