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
X	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* KIRK RANDAL J (Last) (First) (Middle) C/O THIRD SECURITY, LLC 1881 GROVE AVENUE (Street) RADFORD VA 24141 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Synthetic Biologics, Inc. [ SYN ]	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) 04/01/2019
	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	04/01/2019		S		11,413(1)	D	$0.67(1)	92,159(2)	I	by NRM VII Holdings(3)
Common Stock	04/01/2019		S		30,265(1)	D	$0.67(1)	244,402(2)	I	by Intrexon(4)
Common Stock	04/02/2019		S		3,737(1)	D	$0.66(1)	88,422(2)	I	by NRM VII Holdings(3)
Common Stock	04/02/2019		S		9,909(1)	D	$0.66(1)	234,493(2)	I	by Intrexon(4)
Common Stock	04/03/2019		S		26,080(1)	D	$0.65(1)	62,342(2)	I	by NRM VII Holdings(3)
Common Stock	04/03/2019		S		69,161(1)	D	$0.65(1)	165,332(2)	I	by Intrexon(4)

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* KIRK RANDAL J (Last) (First) (Middle) C/O THIRD SECURITY, LLC 1881 GROVE AVENUE (Street) RADFORD VA 24141 (City) (State) (Zip)

1. Name and Address of Reporting Person* INTREXON CORP (Last) (First) (Middle) C/O LEGAL DEPARTMENT 20374 SENECA MEADOWS PARKWAY (Street) GERMANTOWN MD 20876 (City) (State) (Zip)

Explanation of Responses:

1. Pursuant to a joint selling program, NRM VII Holdings I, LLC ("NRM VII Holdings") and Intrexon Corporation ("Intrexon") sold shares on a pro rata basis.

2. The indicated share amount is reflective of a 1:35 reverse stock split effected by the issuer on August 10, 2018.

3. Randal J. Kirk controls NRM VII Holdings. Shares held by this entity may be deemed to be indirectly beneficially owned (as defined under Rule 13d- 3 promulgated under the Securities Exchange Act of 1934, as amended) by Mr. Kirk. Mr. Kirk disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein.

4. Randal J. Kirk, directly and through certain affiliates, is the largest shareholder of Intrexon and serves as Intrexon's Chairman of the Board and Chief Executive Officer. Mr. Kirk may therefore be deemed to have voting and dispositive power over the shares of the issuer owned by Intrexon. Shares held by Intrexon may be deemed to be indirectly beneficially owned (as defined under Rule 13d-3 promulgated under the Securities Exchange Act of 1934, as amended) by Mr. Kirk. Mr. Kirk disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein.

	/s/ Randal J. Kirk	04/03/2019
	/s/ Randal J. Kirk, CEO of Intrexon Corporation	04/03/2019
	** 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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