SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 792,254.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 792,254.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

792,254.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.6 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 52,840.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 52,840.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

52,840.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

0.1 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 27,267.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 27,267.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

27,267.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

0.1 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 655,471.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 655,471.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

655,471.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.3 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 845,094.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 845,094.00

11

Aggregate amount beneficially owned by each reporting person

845,094.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.7 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 872,361.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 872,361.00

11

Aggregate amount beneficially owned by each reporting person

872,361.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.8 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 655,471.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 655,471.00

11

Aggregate amount beneficially owned by each reporting person

655,471.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.3 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 655,471.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 655,471.00

11

Aggregate amount beneficially owned by each reporting person

655,471.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.3 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 1,826,646.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,826,646.00

11

Aggregate amount beneficially owned by each reporting person

1,826,646.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

3.8 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 1,171,175.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,171,175.00

11

Aggregate amount beneficially owned by each reporting person

1,171,175.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

2.4 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 872,361.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 872,361.00

11

Aggregate amount beneficially owned by each reporting person

872,361.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

1.8 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 125,480.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 125,480.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

125,480.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

0.3 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 173,334.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 173,334.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

173,334.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

0.4 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s):

95075A107

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)

Checkbox not checked

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 173,334.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 173,334.00

11

Aggregate amount beneficially owned by each reporting person

173,334.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

13

Percent of class represented by amount in Row (11)

0.4 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

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. 7 to Schedule 13D ("Amendment No. 7") 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, Amendment No. 5 filed January 16, 2026 and Amendment No. 6 filed May 5, 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. 7 but not defined herein shall have the meanings ascribed thereto in the Original Schedule 13D.

Item 5.

Interest in Securities of the Issuer

(a)

See rows (11) and (13) of the Filing Persons Owner Profile of this Amendment No. 7 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: * 792,254 shares are held directly by BV 2014; * 52,840 shares are held directly by BV 2014(B); * 27,267 shares are held directly by AM BV2014 LLC; * 173,334 shares are held directly by MPM OIF; * 125,480 shares by AM LLC; and * 655,471 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 May 1, 2026, as reported in the Issuer's Form 10-Q filed with the SEC on May 7, 2026.

(b)

See rows (7) through (10) of the Filing Persons Owner Profile of this Amendment No. 7 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 since Amendment No. 6: 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 05/06/26 $0.65-$0.7054 $0.66 9,900 660 341 2,166 1,568 8,190 05/07/26 $0.62-$0.667 $0.63 53,499 3,568 1,841 11,705 8.473 44,262 05/08/26 $0.6183-$0.7668 $0.70 206,820 13,795 7,119 45,250 32,757 171,114 05/11/26 $0.66-$0.7002 $0.67 22,965 1,532 790 5,024 3,637 19,000 05/12/26 $0.6286-$0.66 $0.64 45,921 3,063 1,581 10,047 7,273 37,994

(d)

Inapplicable.

(e)

May 8, 2026

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.

MPM BioVentures 2014, L.P.

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC, the General Partner of MPM BioVentures 2014, L.P.
Date:	05/12/2026

MPM BioVentures 2014 (B), L.P.

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Director of MPM BioVentures 2014 LLC, Managing Member of MPM BioVentures 2014 GP LLC, the General Partner of MPM BioVentures 2014 (B), L.P.
Date:	05/12/2026

MPM Asset Management Investors BV2014 LLC

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Director of MPM BioVentures 2014 LLC, the manager of MPM Asset Management Investors BV2014 LLC
Date:	05/12/2026

UBS Oncology Impact Fund L.P.

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Partner of MPM BioImpact LLC, the GP of Oncology Impact Fund (Cayman) Management L.P., the GP of UBS Oncology Impact Fund L.P.
Date:	05/12/2026

MPM BioVentures 2014 GP LLC

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Director of MPM BioVentures 2014 LLC, the Managing Member of MPM BioVentures 2014 GP LLC
Date:	05/12/2026

MPM BioVentures 2014 LLC

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Director
Date:	05/12/2026

Oncology Impact Fund (Cayman) Management L.P.

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Partner of MPM BioImpact LLC, the General Partner of Oncology Impact Fund (Cayman) Management L.P.
Date:	05/12/2026

MPM BioImpact LLC

Signature:	/s/ Ansbert Gadicke
Name/Title:	Managing Partner
Date:	05/12/2026

ANSBERT GADICKE

Signature:	/s/ Ansbert Gadicke
Name/Title:	Ansbert Gadicke
Date:	05/12/2026

LUKE EVNIN

Signature:	/s/ Luke Evnin
Name/Title:	Luke Evnin
Date:	05/12/2026

Todd Foley

Signature:	/s/ Todd Foley
Name/Title:	Todd Foley
Date:	05/12/2026

MPM ASSET MANAGEMENT LLC

Signature:	/s/ Ansbert Gadicke
Name/Title:	Member
Date:	05/12/2026

MPM ONCOLOGY INNOVATIONS FUND LP

Signature:	/s/ Ansbert Gadicke
Name/Title:	Manager of MPM Oncology Innovations Fund GP LLC, the General Partner of MPM Oncology Innovations Fund, L.P.
Date:	05/12/2026

MPM Oncology Innovations Fund GP LLC

Signature:	/s/ Ansbert Gadicke
Name/Title:	Manager
Date:	05/12/2026