X0407 4 2023-06-01 1 0001750019 TCR2 THERAPEUTICS INC. TCRR 0001609492 MPM BioVentures 2014, L.P. C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON MA 02116 0 0 1 0 0001473930 Foley Todd C/O MPM CAPITAL 399 BOYLSTON STREET, 1100 BOSTON MA 02116 0 0 1 0 0001134657 EVNIN LUKE C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON MA 02116 0 0 1 0 0001609493 MPM BioVentures 2014 (B), L.P. C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON MA 02116 0 0 1 0 0001609495 MPM Asset Management Investors BV2014 LLC C/O MPM CAPITAL 399 BOYLSTON STREET, 1100 BOSTON MA 02116 0 0 1 0 0001765021 MPM BioVentures 2014 LLC C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON MA 02116 0 0 1 0 0001765091 MPM BioVentures 2014 GP LLC C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON MA 02116 0 0 1 0 0001263048 MPM ASSET MANAGEMENT LLC C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON MA 02116 0 0 1 0 0 Common Stock 2023-06-01 4 J 0 4158964 0.00 D 0 I See Footnote This Form 4 reports securities disposed of pursuant to the terms of the Agreement and Plan of Merger, dated as of March 5, 2023, by and among TCR2 Therapeutics Inc. (the "Company"), Adaptimmune Therapeutics plc ("Parent") and CM Merger Sub, Inc., an indirect wholly-owned subsidiary of Parent ("Merger Sub"), as amended by that certain Amendment No. 1 to the Agreement and Plan of Merger, dated April 5, 2023, by and among the Company, Parent and Merger Sub (the "Merger Agreement"), pursuant to which Merger Sub merged with and into the Company (the "Merger") with the Company surviving the Merger as an indirect wholly-owned subsidiary of Parent effective as of June 1, 2023 (the "Effective Time"). At the Effective Time, each issued and outstanding share of common stock of the Company (each, a "Share") (excluding any Shares held in treasury of the Company or owned, directly or indirectly, by Parent or Merger Sub immediately prior to the Effective Time) was cancelled and converted into the right to receive 1.5117 (the "Exchange Ratio") American Depositary Shares of Parent ("Parent ADS") representing six ordinary shares of Parent ("Parent Ordinary Shares"). The Reporting Persons disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein. The shares were held as follows: 3,056,272 by MPM BioVentures 2014, L.P. ("BV 2014"), 203,846 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)"), 110,859 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"), 304,001 by MPM Asset Management LLC ("AM LLC"), 421,070 by MPM SunStates Fund, L.P. ("MPM SunStates") and 62,916 by MPM Asset Management Investors Sunstates Fund LLC ("AM SunStates"). MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B) and BV LLC is the manager of AM BV2014. MPM SunStates Fund GP LLC and MPM SunStates GP Managing Member LLC ("SunStates GP") are the direct and indirect general partners of MPM SunStates and SunStates GP is the manager of AM SunStates. Luke Evnin, Ansbert Gadicke and Todd Foley are the managing directors of BV LLC, Ansbert Gadicke is a member of SunStates GP and Luke Evnin and Anbsert Gadicke are the members of AM LLC. See Form 4 for MPM SunStates Fund, L.P for additional members of this joint filing. /s/ Ansbert Gadicke, 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. 2023-06-05 /s/ Todd Foley 2023-06-05 /s/ Luke Evnin 2023-06-05 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC, the general partner of MPM BioVentures 2014 (B), L.P. 2023-06-05 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, manager of MPM Asset Management Investors BV2014 LLC 2023-06-05 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC 2023-06-05 /s/ Ansbert Gadicke, managing director of MPM BioVentures 2014 LLC, the managing member of MPM BioVentures 2014 GP LLC 2023-06-05 /s/ Ansbert Gadicke, member of MPM Asset Management LLC 2023-06-05