SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* UBS Oncology Impact Fund L.P. (Last) (First) (Middle) C/O MPM CAPITAL 450 KENDALL STREET (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 02/13/2019	3. Issuer Name and Ticker or Trading Symbol TCR2 THERAPEUTICS INC. [ TCRR ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Preferred Stock	(1)	(1)	Common Stock	2,421,775	0.00(1)	D(2)(3)
Series B Preferred Stock	(1)	(1)	Common Stock	282,540	0.00(1)	D(2)(3)

1. Name and Address of Reporting Person* UBS Oncology Impact Fund L.P. (Last) (First) (Middle) C/O MPM CAPITAL 450 KENDALL STREET (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)

1. Name and Address of Reporting Person* MPM Oncology Impact Management GP LLC (Last) (First) (Middle) C/O MPM CAPITAL 450 KENDALL STREET (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)

1. Name and Address of Reporting Person* MPM Oncology Impact Management LP (Last) (First) (Middle) C/O MPM CAPITAL 450 KENDALL STREET (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)

1. Name and Address of Reporting Person* Oncology Impact Fund (Cayman) Management L.P. (Last) (First) (Middle) C/O MPM CAPITAL 450 KENDALL STREET (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)

Explanation of Responses:

1. Each share of Series A Preferred Stock and Series B Preferred Stock is convertible into shares of the Issuer's Common Stock on a 6.1938: 1 basis. Upon the closing of the Issuer's initial public offering, all shares of Series A Preferred Stock and Series B Preferred Stock will convert into shares of Common Stock of the Issuer. The Series A Preferred Stock and Series B Preferred Stock have no expiration dates.

2. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.

3. The reported securities are held in the account of UBS Oncology Impact Fund L.P. ("UBS Oncology"). MPM Oncology Impact Management GP LLC ("Oncology GP LLC") is the General Partner of MPM Oncology Impact Management LP, the General Partner of Oncology Impact Fund (Cayman) Management L.P., the General Partner of UBS Oncology. Ansbert Gadicke is the managing director of Oncology GP LLC.

Remarks:

	/s/ Ansbert Gadicke, managing director of MPM Oncology Impact Management GP LLC, the general partner of MPM Oncology Impact Management LP, the general partner of Oncology Impact Fund (Cayman) Management L.P., the GP of UBS Oncology Impact Fund L.P	02/13/2019
	/s/ Ansbert Gadicke, managing director of MPM Oncology Impact Management GP LLC	02/13/2019
	/s/ Ansbert Gadicke, managing director of MPM Oncology Impact Management GP LLC, the general partner of MPM Oncology Impact Management LP	02/13/2019
	/s/ Ansbert Gadicke, managing director of MPM Oncology Impact Management GP LLC, the general partner of MPM Oncology Impact Management LP, the general partner of Oncology Impact Fund (Cayman) Management L.P.	02/13/2019
	** Signature of Reporting Person	Date
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