Statement of Changes in Beneficial Ownership (4)

FORM 4 ☒ Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * MPM SunStates Fund, L.P.	2. Issuer Name and Ticker or Trading Symbol TCR2 THERAPEUTICS INC. [ TCRR ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                    __X__ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) C/O MPM CAPITAL, 399 BOYLSTON STREET, SUITE 1100	3. Date of Earliest Transaction (MM/DD/YYYY) 6/1/2023
(Street) BOSTON, MA 02116	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _ X _ Form filed by More than One Reporting Person
(City)        (State)        (Zip)	Rule 10b5-1(c) Transaction Indication ☐ Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	6/1/2023		J(1)		4158964	D	$0.00 (2)	0	I	See Footnote (3)(4)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:
(1)	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").
(2)	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").
(3)	The Reporting Persons disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein.
(4)	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.

Remarks: See Form 4 for MPM BioVentures 2014, L.P. for additional members of this joint filing.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MPM SunStates Fund, L.P. C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA 02116		X
MPM Asset Management Investors SunStates Fund LLC C/O MPM CAPITAL 399 BOYLSTON STREET, 1100 BOSTON, MA 02116		X
MPM SunStates Fund GP LLC C/O MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA 02116		X
MPM SunStates GP Managing Member LLC MPM CAPITAL 399 BOYLSTON STREET, SUITE 1100 BOSTON, MA 02116		X

Signatures
/s/ Ansbert Gadicke, member of MPM Sunstates GP Managing Member LLC, the managing member of MPM SunStates Fund GP LLC, the general partner of MPM SunStates Fund, L.P.		6/5/2023
**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, member of MPM SunStates GP Managing Member LLC, manager of MPM Asset Management Investors SunStates Fund LLC		6/5/2023
**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, member of MPM SunStates GP Managing Member LLC, the managing member of MPM SunStates Fund GP LLC		6/5/2023
**Signature of Reporting Person		Date
/s/ Ansbert Gadicke, member of MPM SunStates GP Managing Member LLC		6/5/2023
**Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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