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* Atlas Venture Fund IX, L.P. (Last) (First) (Middle) 25 FIRST STREET, SUITE 303 (Street) CAMBRIDGE MA 02141 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 03/28/2018	3. Issuer Name and Ticker or Trading Symbol Unum Therapeutics, Inc. [ UMRX ]
		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	3,184,446	(1)	D(2)
Series B Preferred Stock	(1)	(1)	Common Stock	83,067	(1)	D(2)

1. Name and Address of Reporting Person* Atlas Venture Fund IX, L.P. (Last) (First) (Middle) 25 FIRST STREET, SUITE 303 (Street) CAMBRIDGE MA 02141 (City) (State) (Zip)

1. Name and Address of Reporting Person* Atlas Venture Associates IX, L.P. (Last) (First) (Middle) 25 FIRST STREET, SUITE 303 (Street) CAMBRIDGE MA 02141 (City) (State) (Zip)

1. Name and Address of Reporting Person* Atlas Venture Associates IX, LLC (Last) (First) (Middle) 25 FIRST STREET, SUITE 303 (Street) CAMBRIDGE MA 02141 (City) (State) (Zip)

Explanation of Responses:

1. Each share is convertible on a 1.5701314513884-for-1 basis into Common Stock at any time at the election of the Reporting Person and will automatically convert upon the closing of the Issuer's initial public offering into the number of shares of the Issuer's Common Stock shown in column 3 without payment or further consideration. The shares have no expiration date.

2. The shares are held directly by Atlas Venture Fund IX, L.P. ("Atlas Venture Fund IX"). The general partner of Atlas Venture Fund IX is Atlas Venture Associates IX, L.P. ("AVA IX LP"). Atlas Venture Associates IX, LLC ("AVA IX LLC") is the general partner of AVA IX LP. Each of AVA IX LP and AVA IX LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Fund IX, except to the extent of its pecuniary interest therein, if any.

Remarks:

	Atlas Venture Fund IX, LP, By: Atlas Venture Associates IX, LP, its general partner, By: Atlas Venture Associates IX, LLC, its general partner, By: Frank Castellucci, General Counsel /s/ Frank Castellucci	03/28/2018
	Atlas Venture Associates IX, LP, By: Atlas Venture Associates IX, LLC, its general partner, By: Frank Castellucci, General Counsel /s/ Frank Castellucci	03/28/2018
	Atlas Venture Associates IX, LLC, By: Frank Castellucci, General Counsel /s/ Frank Castellucci	03/28/2018
	** 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 5 (b)(v).
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