X0206 3 2016-06-21 0 0001453687 SELECTA BIOSCIENCES INC SELB 0001508052 Flagship Ventures Fund 2007, L.P. ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE MA 02142 1 0 1 0 0001508053 Flagship Ventures 2007 General Partner LLC ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE MA 02142 1 0 1 0 0001222012 AFEYAN NOUBAR ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE MA 02142 1 0 1 0 0001255927 KANIA EDWIN M JR ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE MA 02142 1 0 1 0 Common Stock 31115 I See Footnote Series A Convertible Preferred Stock Common Stock 318752 I See Footnote Series B Convertible Preferred Stock Common Stock 631458 I See Footnote Series C Convertible Preferred Stock Common Stock 235042 I See Footnote Series D Convertible Preferred Stock Common Stock 241718 I See Footnote Series E Convertible Preferred Stock Common Stock 125008 I See Footnote Common Warrants 17.55 2015-07-24 2018-07-24 Common Stock 20262 I See Footnote 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. The preferred stock is convertible at any time, at the holder's election and has no expiration date. The preferred stock will automatically convert into common stock upon the closing of the Issuer's initial public offering. Exhibit 24 - Power of Attorney Flagship Ventures Fund 2007, L.P., Flagship Ventures 2007 General Partner LLC and Noubar B. Afeyan are directors by deputization based on Edwin M. Kania, Jr.'s position on the Issuer's Board of Directors. FLAGSHIP VENTURES FUND 2007, L.P. By: Flagship Ventures 2007 General Partner LLC By: /s/ Noubar B. Afeyan, Ph.D., Manager 2016-06-21 FLAGSHIP VENTURES 2007 GENERAL PARTNER LLC By: /s/ Noubar B. Afeyan, Ph.D., Manager 2016-06-21 s/ Noubar B. Afeyan, Ph.D. 2016-06-21 /s/ Edwin M. Kania Jr. 2016-06-21