SEC Form 4

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

1. Name and Address of Reporting Person* Flagship Ventures Fund IV General Partner LLC (Last) (First) (Middle) C/O FLAGSHIP PIONEERING INC. 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Axcella Health Inc. [ AXLA ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 05/18/2020
	4. 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 Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction 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	05/18/2020		P		1,520,000	A	$4.75	4,808,780	I	See Footnote(1)
Common Stock	05/18/2020		P		380,000	A	$4.75	1,056,752	I	See Footnote(2)
Common Stock	05/18/2020		P		1,900,000	A	$4.75	2,886,023	I	See Footnote(3)
Common Stock								2,035,830	I	See Footnote(4)
Common Stock								1,761,029	I	See Footnote(5)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction 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 (Month/Day/Year)		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: 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

1. Name and Address of Reporting Person* Flagship Ventures Fund IV General Partner LLC (Last) (First) (Middle) C/O FLAGSHIP PIONEERING INC. 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Flagship Ventures Fund IV, L.P. (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Flagship Ventures Fund IV-Rx, L.P. (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Flagship Ventures Opportunities Fund I General Partner LLC (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Flagship Ventures Opportunities Fund I, L.P. (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* AFEYAN NOUBAR (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E (Street) CAMBRIDGE MA 02142 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. is the sole manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein. Edwin M. Kania, Jr. is retired both from Flagship Pioneering, Inc. and as a manager of Flagship Fund IV GP.

2. Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. Noubar B. Afeyan, Ph.D. is the sole manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

3. Shares held by Flagship Ventures Opportunities Fund I, L.P. ("Flagship Opportunities I"). Flagship Ventures Opportunities Fund I General Partner LLC ("Flagship Opportunities GP") is the general partner of Flagship Opportunities I. Noubar B. Afeyan, Ph.D. is the sole manager of Flagship Opportunities. Each of the reporting persons except for Flagship Opportunities I disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.

4. Shares held by Flagship VentureLabs IV, LLC ("VentureLabs IV"). Flagship Fund IV is a member of VentureLabs IV and also serves as its manager. Flagship Fund IV GP is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. is the sole manager of Flagship Fund IV GP. Each of the reporting persons except for VentureLabs IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

5. Shares held by Flagship Ventures Fund 2007, L.P. ("Flagship Fund 2007"). Flagship Ventures 2007 General Partner LLC ("Fund 2007 GP") is the general partner of Flagship Fund 2007. Noubar B. Afeyan, Ph.D. is the sole manager of Fund 2007 GP. Each of the reporting persons except for Flagship Fund 2007 disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein. Edwin M. Kania, Jr. is retired both from Flagship Pioneering, Inc. and as a manager of Fund 2007 GP.

Remarks:

	Flagship Ventures Fund IV General Partner LLC, By: /s/ Noubar B. Afeyan, Ph.D., Name: Noubar B. Afeyan, Ph.D., Title: Manager	05/20/2020
	Flagship Ventures Fund IV, L.P., By: Flagship Ventures Fund IV General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Ph.D., Name: Noubar B. Afeyan, Ph.D., Title: Manager	05/20/2020
	Flagship Ventures Fund IV-Rx, L.P., By: Flagship Ventures Fund IV General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Ph.D., Name: Noubar B. Afeyan, Ph.D., Title: Manager	05/20/2020
	Flagship Ventures Opportunities Fund I General Partner LLC, By: /s/ Noubar B. Afeyan, Ph.D., Name: Noubar B. Afeyan, Ph.D., Title: Manager	05/20/2020
	Flagship Ventures Opportunities Fund I, L.P. By: Flagship Ventures Opportunities Fund I General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Ph.D., Name: Noubar B. Afeyan, Ph.D., Title: Manager	05/20/2020
	Noubar B. Afeyan, Ph.D. By: /s/ Noubar B. Afeyan, Ph.D.	05/20/2020
	** 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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