Polaris Venture Partners V SC 13D/A Selecta Biosciences Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

SELECTA BIOSCIENCES, INC.

(Name of Issuer)

Common Stock, $0.0001 par value

(Title of Class of Securities)

816212104

(CUSIP Number)

Polaris Partners One Marina Park Drive, 10th Floor Boston, MA 02210 Gunderson Dettmer Stough Villeneuve Franklin & Hachigian, LLP One Marina Park Drive, Suite 900 Boston, MA 02210 Attn: Jay K. Hachigian, Esq. (617)648-9100

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

December 23, 2019

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of§§240.13d-1(e),240.13d-1(f) or240.13d-1(g), check the following box:  ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See§240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

1.	Names of Reporting Persons.   Polaris Venture Partners V, L.P. (“PVP V”)
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a)  ☐        (b)  ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   WC
5.	Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   Delaware

Number of Shares Beneficially Owned by Each Reporting Person With	7.	Sole Voting Power 2,676,234 shares, except that (i) Polaris Venture Management Co. V, L.L.C. (“PVM V”), the general partner of PVP V, may be deemed to have sole power to vote these shares, and (ii) Jonathan A. Flint (“Flint”), a managing member of PVM V, may be deemed to have shared power to vote these shares, Terrance G. McGuire (“McGuire”), a managing member of PVM V, may be deemed to have shared power to vote these shares and Amir Nashat (“Nashat”), a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to vote these shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 2,676,234 shares, except that (i) PVM V, the general partner of PVP V, may be deemed to have sole power to dispose of these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to dispose of these shares and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, maybe be deemed to have shared power to dispose of these shares.
	10.	Shared Dispositive Power See response to row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   2,676,234
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   3.1%
14.	Type of Reporting Person (See Instructions)    PN

1.	Names of Reporting Persons.   Polaris Venture Partners Entrepreneurs’ Fund V, L.P. (“PVPE V”)
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a)  ☐        (b)  ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   WC
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   Delaware

Number of Shares Beneficially Owned by Each Reporting Person With	7.	Sole Voting Power 52,156 shares, except that (i) PVM V, the general partner of PVPE V, may be deemed to have sole power to vote these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to vote these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to vote these shares and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to vote these shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 52,156 shares, except that (i) PVM V, the general partner of PVPE V, may be deemed to have sole power to dispose of these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to dispose of these shares.
	10.	Shared Dispositive Power See response to Row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   52,156
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   0.1%
14.	Type of Reporting Person (See Instructions)    PN

1.	Names of Reporting Persons. Polaris Venture Partners Founders’ Fund V, L.P. (“PVPFF V”)
2.	Check the Appropriate Box if a Member of a Group (See Instructions) (a) ☐        (b) ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions) WC
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e) ☐
6.	Citizenship or Place of Organization Delaware

Number of Shares Beneficially   Owned by Each Reporting Person With	7.	Sole Voting Power 18,329 shares, except that (i) PVM V, the general partner of PVPFF V, may be deemed to have sole power to vote these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to vote these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to vote these shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to vote these shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 18,329 shares, except that (i) PVM V, the general partner of PVPFF V, may be deemed to have sole power to dispose of these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to dispose of these shares.
	10.	Shared Dispositive Power See response to Row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   18,329
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   0.0%
14.	Type of Reporting Person (See Instructions)   PN

1.	Names of Reporting Persons.   Polaris Venture Partners Special Founders’ Fund V, L.P. (“PVPSFF V”)
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a) ☐        (b) ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   WC
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   Delaware

Number of Shares Beneficially   Owned by Each Reporting Person With	7.	Sole Voting Power 26,760 shares, except that (i) PVM V, the general partner of PVPSFF V, may be deemed to have sole power to vote these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to vote these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to vote these shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to vote these shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 26,760 shares, except that (i) PVM V, the general partner of PVPSFF V, may be deemed to have sole power to dispose of these shares, and (ii) Flint, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, McGuire, a managing member of PVM V, may be deemed to have shared power to dispose of these shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to dispose of these shares.
	10.	Shared Dispositive Power See response to row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   26,760
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   0.0%
14.	Type of Reporting Person (See Instructions)   PN

1.	Names of Reporting Persons.   Polaris Venture Management Co. V, L.L.C. (“PVM V”)
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a) ☐        (b) ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   AF
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   Delaware

Number of Shares Beneficially   Owned by Each Reporting Person With	7.	Sole Voting Power 2,773,479 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF and (d) 26,760 shares are directly owned by PVPSFF V, except that Flint, a managing member of PVM V, the general partner of each of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have shared power to vote PVP V’s, PVPE V’s, PVPFF V’s and PVPSFF V’s shares (collectively, the “Fund V Shares”) shares, McGuire, a managing member of PVM V, may be deemed to have shared power to vote the Fund V Shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to vote the Fund V Shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 2,773,479 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF and (d) 26,760 shares are directly owned by PVPSFF V, except that Flint, a managing member of PVM V, the general partner of each of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have shared power to dispose of the Fund V Shares, McGuire, a managing member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares, and Nashat, a member of PVM V and member of the Board of Directors of the Issuer, may be deemed to have shared power to dispose of the Fund V Shares.
	10.	Shared Dispositive Power See response to row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   2,773,479
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   3.2%
14.	Type of Reporting Person (See Instructions)   OO

1.	Names of Reporting Persons.   Jonathan A. Flint
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a)  ☐        (b)  ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   AF
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   USA

Number of Shares Beneficially Owned by Each Reporting Person With	7.	Sole Voting Power 2,773,479 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF and (d) 26,760 shares are directly owned by PVPSFF V, except that PVM V, the general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have sole power to vote the Fund V Shares, McGuire, as a managing member of PVM V, may be deemed to have shared power to vote the Fund V Shares, and Nashat, a member of PVM V, may be deemed to have shared power to vote the Fund V Shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 2,773,479 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF and (d) 26,760 shares are directly owned by PVPSFF V, except that PVM V, as general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, maybe deemed to have sole power to dispose of the Fund V Shares, McGuire, as a managing member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares, and Nashat, a member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares.
	10.	Shared Dispositive Power See response to row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   2,773,479
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   3.2%
14.	Type of Reporting Person (See Instructions)    IN

1.	Names of Reporting Persons.   Terrance G. McGuire
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a)  ☐        (b)  ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   AF
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   USA

Number of Shares Beneficially Owned by Each Reporting Person With	7.	Sole Voting Power 2,773,479 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF and (d) 26,760 shares are directly owned by PVPSFF V, except that PVM V, the general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have sole power to vote the Fund V Shares, Flint, as a managing member of PVM V, may be deemed to have shared power to vote the Fund V Shares, and Nashat, a member of PVM V, may be deemed to have shared power to vote the Fund V Shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 2,773,479 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF and (d) 26,760 shares are directly owned by PVPSFF V, except that PVM V, as general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have sole power to dispose of the Fund V Shares, Flint, as a managing member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares, and Nashat, a member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares.
	10.	Shared Dispositive Power See response to row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   2,773,479
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   3.2%
14.	Type of Reporting Person (See Instructions)    IN

1.	Names of Reporting Persons.   Amir Nashat
2.	Check the Appropriate Box if a Member of a Group (See Instructions)   (a)  ☐        (b)  ☒
3.	SEC Use Only
4.	Source of Funds (See Instructions)   AF
5.	Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)   ☐
6.	Citizenship or Place of Organization   USA

Number of Shares Beneficially Owned by Each Reporting Person With	7.	Sole Voting Power 2,789,889 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF, (d) 26,760 shares are directly owned by PVPSFF V and (e) 16,410 shares which represent Common Stock underlying a Stock Option owned by Nashat directly, except that PVM V, the general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have sole power to vote the Fund V Shares, Flint, as a managing member of PVM V, may be deemed to have shared power to vote the Fund V Shares, and McGuire, a managing member of PVM V, may be deemed to have shared power to vote the Fund V Shares.
	8.	Shared Voting Power See response to row 7.
	9.	Sole Dispositive Power 2,789,889 shares, of which (a) 2,676,234 shares are directly owned by PVP V, (b) 52,156 shares are directly owned by PVPE V, (c) 18,329 shares are directly owned by PVPFF, (d) 26,760 shares are directly owned by PVPSFF V and (e) 16,410 shares which represent Common Stock underlying a Stock Option owned by Nashat directly, except that PVM V, as general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to have sole power to dispose of the Fund V Shares, Flint, as a managing member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares, and McGuire, a managing member of PVM V, may be deemed to have shared power to dispose of the Fund V Shares.
	10.	Shared Dispositive Power See response to row 9.

11.	Aggregate Amount Beneficially Owned by Each Reporting Person   2,789,889
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)   ☐
13.	Percent of Class Represented by Amount in Row (11)   3.2%
14.	Type of Reporting Person (See Instructions)    IN

CUSIP No. 816212104

SCHEDULE 13D

This Amendment No. 4 (“Amendment No. 4”) amends and supplements the Schedule 13D originally filed with the Securities and Exchange Commission (the “SEC”) on July 7, 2016 and amended on September 29, 2017 , May 3, 2018 and February 4, 2019 (collectively, the “Schedule 13D”) by the Reporting Persons. The “Reporting Persons” are, collectively, Polaris Venture Partners V, L.P. (“PVP V”), Polaris Venture Partners Entrepreneurs’ Fund V, L.P. (“PVPE V”), Polaris Venture Partners Founders’ Fund V, L.P (“PVPFF V”), Polaris Venture Partners Special Founders’ Fund, L.P. (“PVPSFF V”), Polaris Venture Management Co. V, L.L.C. (“PVM V), Jonathan A. Flint (“Flint”), Terrance G. McGuire (“McGuire”) and Amir Nashat (“Nashat”). The Reporting Persons are making this single, joint filing because they may be deemed to constitute a “group” within the meaning of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended. The agreement between the Reporting Persons to file as a group (the “Joint Filing Agreement”) is attached hereto as Exhibit A.

This Amendment No. 4 is being filed to report that the Reporting Persons have ceased to be the beneficial owners of more than 5% of the class of securities as of December 23, 2019. Only those items that are hereby reported are amended; all other items reported in the Schedule 13D remain unchanged. Information given in response to each item below shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms used herein but not defined shall have the meanings ascribed thereto in the Schedule 13D.

Item 5. Interest in Securities of the Issuer.

Item 5(a) of the Schedule 13D is hereby amended and restated in its entirety as follows:

The information in the cover page of each Reporting Person, except Nashat is based on a total of 86,325,547 shares of the Issuer’s Common Stock outstanding as of December 23, 2019 as reported on the Issuer’s Registration Statement on FormS-3 and filed with the United States Securities and Exchange Commission on January 29, 2020.

The information in the cover page of Nashat is based on a total of 86,341,957 shares, comprised of (i) 86,325,547 shares of the Issuer’s Common Stock outstanding as of December 23, 2019 as reported on the Issuer’s Registration Statement on FormS-3 and filed with the United States Securities and Exchange Commission on January 29, 2020, plus (ii) 16,410 shares of the Issuer’s Common Stock underlying fully vested stock options issued to Nashat for service as a member of the Issuer’s Board of Directors.

(a) Regarding aggregate beneficial ownership, see Row 11 of the cover page of each Reporting Person. Regarding percentage of class of beneficial ownership, see Row 13 of the cover page of each Reporting Person. Regarding sole power to vote shares, see Row 7 of the cover page of each Reporting Person. Regarding shared power to vote shares, see Row 8 of the cover page of each Reporting Person. Regarding sole power to dispose of shares, see Row 9 of the cover page of each Reporting Person. Regarding shared power to dispose of shares, see Row 10 of the cover page of each Reporting Person.

(c) Except as described in this statement and below, none of the Reporting Persons has effected any transactions in the Common Stock in the 60 days prior to December 23, 2019.

Each of the Reporting Persons ceased to be that beneficial owner of more than five percent of the Issuer’s Common Stock on December 23, 2019.

Item 7. Material to be Filed as Exhibits.

Exhibit A - Joint Filing Agreement

Exhibit E - Power of Attorney (Amir Nashat)

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: February 12, 2020

POLARIS VENTURE PARTNERS V, L.P.
By:	Polaris Venture Management Co. V, L.L.C.
By:	*
	Managing Member
POLARIS VENTURE PARTNERS ENTREPRENEURS’ FUND V, L.P.
By:	Polaris Venture Management Co. V, L.L.C.
By:	*
	Managing Member
POLARIS VENTURE PARTNERS FOUNDERS’ FUND V, L.P.
By:	Polaris Venture Management Co. V, L.L.C.
By:	*
	Managing Member
POLARIS VENTURE PARTNERS SPECIAL FOUNDERS’ FUND V, L.P.
By:	Polaris Venture Management Co. V, L.L.C.
By:	*
	Managing Member
POLARIS VENTURE MANAGEMENT CO. V, L.L.C.
By:	*
	Managing Member

JONATHAN A. FLINT
By:	*
	Jonathan A. Flint
TERRANCE G. MCGUIRE
By:	*
	Terrance G. McGuire
AMIR NASHAT
By:	*
	Amir Nashat

*By:	/s/ Lauren Crockett
Name:	Lauren Crockett
	Attorney-in-Fact

[This Schedule 13D Amendment No. 4 was executed pursuant to Powers of Attorney. Note that copies of the applicable Powers of Attorney for the Reporting Persons other than Nashat are already on file with the appropriate agencies. The Power of Attorney of Amir Nashat is attached hereto as Exhibit E.]