SCHEDULE 13D/A 0001193125-21-162185 0001609492 XXXXXXXX LIVE 1 Common Stock 10/31/2025 false 0001785530 95075A107 WEREWOLF THERAPEUTICS, INC.

200 TALCOTT AVENUE 2ND FLOOR WATERTOWN MA 02472

Ansbert Gadicke 617-425-9200 c/o MPM BioImpact LLC 339 Boylston Street, Suite 1100 Boston MA 02116 0001609492 N MPM BioVentures 2014, L.P. b WC N DE 2666424.00 0.00 2666424.00 0.00 2666424.00 N 5.8 PN 0001609493 N MPM BioVentures 2014 (B), L.P. b WC N DE 177846.00 0.00 177846.00 0.00 177846.00 N 0.4 PN 0001609495 N MPM Asset Management Investors BV2014 LLC b WC N DE 91778.00 0.00 91778.00 0.00 91778.00 N 0.2 OO 0001691428 N UBS Oncology Impact Fund L.P. b WC N E9 2204251.00 0.00 2204251.00 0.00 2204251.00 N 4.8 PN 0001765091 N MPM BioVentures 2014 GP LLC b WC N DE 0.00 2844270.00 0.00 2844270.00 2844270.00 N 6.2 OO 0001765021 N MPM BioVentures 2014 LLC b WC N DE 0.00 2936048.00 0.00 2936048.00 2936048.00 N 6.4 OO 0001721036 N Oncology Impact Fund (Cayman) Management L.P. b WC N E9 0.00 2204251.00 0.00 2204251.00 2204251.00 N 4.8 PN 0001687078 N MPM BioImpact LLC b WC N DE 0.00 2204251.00 0.00 2204251.00 2204251.00 N 4.8 OO 0001134655 N ANSBERT GADICKE b WC N X1 0.00 6147610.00 0.00 6147610.00 6147610.00 N 13.4 IN 0001134657 N LUKE EVNIN b WC N X1 0.00 3943359.00 0.00 3943359.00 3943359.00 N 8.6 IN 0001473930 N Todd Foley b WC N X1 0.00 2936048.00 0.00 2936048.00 2936048.00 N 6.4 IN 0001263048 N MPM ASSET MANAGEMENT LLC b WC N DE 422201.00 0.00 422201.00 0.00 422201.00 N 0.9 OO 0001719960 N MPM ONCOLOGY INNOVATIONS FUND LP b WC N DE 585110.00 0.00 585110.00 0.00 585110.00 N 1.3 PN 0001857903 N MPM Oncology Innovations Fund GP LLC b WC N DE 0.00 585110.00 0.00 585110.00 585110.00 N 1.3 OO Common Stock WEREWOLF THERAPEUTICS, INC. 200 TALCOTT AVENUE 2ND FLOOR WATERTOWN MA 02472 Explanatory Note: This Amendment No. 1 to Schedule 13D ("Amendment No. 1") 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 (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 2, 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. 1 but not defined herein shall have the meanings ascribed thereto in the Original Schedule 13D. The entities and persons filing this statement are MPM BioVentures 2014, L.P. ("BV 2014"), MPM BioVentures 2014 (B), L.P. ("BV 2014(B)"), MPM Asset Management Investors BV2014 LLC ("AM BV2014 LLC"), MPM Asset Management LLC ("AM LLC"), MPM Oncology Innovations Fund, L.P. ("MPM OIF"), UBS Oncology Impact Fund L.P. ("UBS Oncology"), MPM BioVentures 2014 GP LLC ("BV 2014 GP"), MPM BioVentures 2014 LLC ("BV 2014 LLC"), MPM Oncology Innovations Fund GP LLC ("MPM OIF GP"), Oncology Impact Fund (Cayman) Management LP ("Oncology Cayman"), MPM BioImpact LLC ("BioImpact") (collectively, the "MPM Entities") and Ansbert Gadicke, Luke Evnin and Todd Foley (collectively, the "Listed Persons" and together with the MPM Entities, the "Filing Persons"). The address of the principal place of business for each of the MPM Entities and Ansbert Gadicke, Luke Evnin and Todd Foley is 399 Boylston Street, Boston, MA 02116. The principal business of each of the Filing Persons is the venture capital investment business. During the last five years, none of the Filing Persons has been convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors). During the last five years, none of the Filing 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, or 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. Each of the Listed Persons is a United States citizen and each of the MPM Entities is a Delaware limited partnership or limited liability company, other than UBS Oncology and Oncology Cayman who are limited partnerships organized in the Cayman Islands. In accordance with the provisions of General Instruction C to Schedule 13D, information concerning the managers and each other person controlling the general partners of the MPM Entities required by Item 2 of Schedule 13D is listed on Schedule 1 hereto and is incorporated by reference herein. See rows (11) and (13) of the Filing Persons Owner Profile of this Amendment No. 1 for the aggregate number of Common Stock and percentages of the shares of Common Stock beneficially owned by the Filing Person. The Common Stock are held as follows: * 2,666,424 shares are held directly by BV 2014; * 177,846 shares are held directly by BV 2014(B); * 91,778 shares are held directly by AM BV2014 LLC; * 585,110 shares are held directly by MPM OIF; * 422,201 share by AMC LLC; and * 2,204,251 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 OIFOIF 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 45,728,999 Common Stock outstanding as of August 8, 2025, as reported in the Issuer's Form 10-Q filed with the SEC on August 14, 2025. See rows (7) through (10) of the Filing Persons Owner Profile of this Amendment No. 1 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. The Reporting Persons sold the following Common Stock in the open market in the sixty days preceding the date of this filing: Date of Price Range Ave. Price Sold by Sold by Sold By AM BV Sold by Sold by Sold by Sale BV 2014 BV 2104(B) 2014 LLC MPM OIF AM LLC UBS Oncology 10/27/25 $1.675-$.182 $1.72 31,538 2,104 1,085 6,945 4,992 26,045 10/28/25 $1.605-$1.70 $1.64 29,958 1,988 1,031 6,598 4,742 24,741 10/29/25 $1.51-$1.62 $1.55 58,227 3,884 2,004 12,823 9,216 48 086 10/30/25 $1.365-$1.55 $1.43 37,709 2,515 1,298 8,304 5,969 31,141 10/31/25 $1.205-$1.415 $1.28 49,467 3,299 1,702 10,894 7,830 40,852 11/03/25 $1.245-$1.33 $1.29 40,800 2,721 1,405 8,985 6,458 33,694 Inapplicable. Inapplicable. Joint Filing Statement MPM BioVentures 2014, L.P. /s/ Ansbert Gadicke 11/04/2025 MPM BioVentures 2014 (B), L.P. /s/ Ansbert Gadicke 11/04/2025 MPM Asset Management Investors BV2014 LLC /s/ Ansbert Gadicke 11/04/2025 UBS Oncology Impact Fund L.P. /s/ Ansbert Gadicke 11/04/2025 MPM BioVentures 2014 GP LLC /s/ Ansbert Gadicke 11/04/2025 MPM BioVentures 2014 LLC /s/ Ansbert Gadicke 11/04/2025 Oncology Impact Fund (Cayman) Management L.P. /s/ Ansbert Gadicke 11/04/2025 MPM BioImpact LLC /s/ Ansbert Gadicke 11/04/2025 ANSBERT GADICKE /s/ Ansbert Gadicke 11/04/2025 LUKE EVNIN /s/ Luke Evnin 11/04/2025 Todd Foley /s/ Todd Foley 11/04/2025 MPM ASSET MANAGEMENT LLC /s/ Ansbert Gadicke 11/04/2025 MPM ONCOLOGY INNOVATIONS FUND LP /s/ Ansbert Gadicke 11/04/2025 MPM Oncology Innovations Fund GP LLC /s/ Ansbert Gadicke 11/04/2025