Sec Form 4 Filing - Flagship Ventures Fund 2007, L.P. @ SELECTA BIOSCIENCES INC - 2016-06-27

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 Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Flagship Ventures Fund 2007, L.P. 2. Issuer Name and Ticker or Trading Symbol SELECTA BIOSCIENCES INC [ SELB] 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) ONE MEMORIAL DRIVE, 7TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 06/27/2016 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 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)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 06/27/2016 C 318,752 A 349,867 I See Footnote ( 1 ) Common Stock 06/27/2016 C 631,458 A 981,325 I See Footnote ( 1 ) Common Stock 06/27/2016 C 235,042 A 1,216,367 I See Footnote ( 1 ) Common Stock 06/27/2016 C 241,718 A 1,458,085 I See Footnote ( 1 ) Common Stock 06/27/2016 C 193,777 A 1,651,862 I See Footnote ( 1 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of U nderlying Securities (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 Series A Convertible Preferred Stock ( 2 ) 06/27/2016 C 318,752 ( 2 ) ( 2 ) Common Stock 318,752 $ 0 0 I See Footnote ( 1 ) Series B Convertible Preferred Stock ( 2 ) 06/27/2016 C 631,458 ( 2 ) ( 2 ) Common Stock 631,458 $ 0 0 I See Footnote ( 1 ) Series C Convertible Preferred Stock ( 2 ) 06/27/2016 C 235,042 ( 2 ) ( 2 ) Common Stock 235,042 $ 0 0 I See Footnote ( 1 ) Series D Convertible Preferred Stock ( 2 ) 06/27/2016 C 241,718 ( 2 ) ( 2 ) Common Stock 241,718 $ 0 0 I See Footnote ( 1 ) Series E Convertible Preferred Stock ( 3 ) 06/27/2016 C 125,008 ( 3 ) ( 3 ) Common Stock 193,777 $ 0 0 I See Footnote ( 1 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Flagship Ventures Fund 2007, L.P. ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X Flagship Ventures 2007 General Partner LLC ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X AFEYAN NOUBAR ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X Signatures FLAGSHIP VENTURES FUND 2007, L.P. By: Flagship Ventures 2007 General Partner LLC By: /s/ Noubar B. Afeyan, Ph.D., Manager 06/29/2016 Signature of Reporting Person Date FLAGSHIP VENTURES 2007 GENERAL PARTNER LLC By: /s/ Noubar B. Afeyan, Ph.D., Manager 06/29/2016 Signature of Reporting Person Date s/ Noubar B. Afeyan, Ph.D. 06/29/2016 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Held by Flagship Ventures Fund 2007, L.P. ("Flagship 2007"). Flagship Ventures 2007 General Partner LLC ("Flagship 2007 LLC") is the general partner of Flagship 2007. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship 2007 LLC. Flagship 2007 LLC and each of these individuals may be deemed to share voting and investment power with respect to all shares held by Flagship 2007. Each of the filing persons disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein. ( 2 )The preferred stock is convertible at any time, at the holder's election and has no expiration date. The preferred stock automatically converted into common stock on a 1-for-1 basis upon the closing of the Issuer's initial public offering. ( 3 )The Series E Convertible Preferred Stock is convertible at any time, at the holder's election and has no expiration date. The Series E Convertible Preferred Stock automatically converted into common stock on an approximately 1-for-1.550115 basis upon the closing of the Issuer's initial public offering.

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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