SEC Filing - Cartesian Therapeutics, Inc

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SC 13D/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

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)

September 20, 2016

(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) or 240.13d-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 1,628,440 shares, of which (a) 1,550,478 shares are Common Stock and (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 1,628,440 shares, of which (a) 1,550,478 shares are Common Stock and (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 1,628,440
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) ☐
13.	Percent of Class Represented by Amount in Row (11) 7.4%
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 31,734 shares, of which (a) 30,215 shares are Common Stock and (b) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 31,734 shares, of which (a) 30,215 shares are Common Stock and (b) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 31,734
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 11,152 shares, of which (a) 10,618 shares are Common Stock and (b) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 11,152 shares, of which (a) 10,618 shares are Common Stock and (b) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 11,152
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 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 19,518 shares, of which (a) 15,502 shares are Common Stock and (b) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 19,518 shares, of which (a) 15,502 shares are Common Stock and (b) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days, 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 19,518
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 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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 1,690,844
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) ☐
13.	Percent of Class Represented by Amount in Row (11) 7.7%
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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 1,690,844
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) ☐
13.	Percent of Class Represented by Amount in Row (11) 7.7%
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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 1,690,844
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) ☐
13.	Percent of Class Represented by Amount in Row (11) 7.7%
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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 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 1,690,844 shares, of which (a) 1,550,478 shares are directly owned by PVP V, (b) 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V, (c) 30,215 shares are directly owned by PVPE V, (d) 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V, (e) 10,618 shares are directly owned by PVPFF V, (g) 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V, (h) 15,502 shares are directly owned by PVPSFF V and (i) 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to 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 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 1,690,844
12.	Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions) ☐
13.	Percent of Class Represented by Amount in Row (11) 7.7%
14.	Type of Reporting Person (See Instructions) IN

CUSIP No. 816212104

SCHEDULE 13D

This Amendment No. 1 (“Amendment No. 1”) amends and supplements the Schedule 13D originally filed with the Securities and Exchange Commission (the “SEC”) on July 7, 2016 (the “Schedule 13D”) by Polaris Venture Partners V, L.P. (“PVP V”), Polaris Venture Partners Entrepreneurs’ Fund V, L.P. (“PVPE V”), Polar 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”) (collectively, the “Reporting Persons”). 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. 1 is being filed to report the disposition of Common Stock by PVP V, PVPE V, PVPFF V and PVPSFF V on September 20, 2017, September 21, 2017, September 22, 2017, September 25, 2017 and September 26, 2017; all other information is as set forth in the Schedule 13D. Information given in response to each item 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 4. Purpose of Transaction.

Item 4 of the original Schedule 13D is hereby amended to add the following statements:

On September 20, 2017, PVP V sold 41,116 shares of Common Stock on the open market, PVPE V sold 801 shares of Common Stock on the open market, PVPFF V sold 282 shares of Common Stock on the open market, and PVPSFF V sold 411 shares of Common Stock on the open market.

On September 21, 2017, PVP V sold 100,911 shares of Common Stock on the open market, PVPE V sold 1,967 shares of Common Stock on the open market, PVPFF V sold 690 shares of Common Stock on the open market, and PVPSFF V sold 1,009 shares of Common Stock on the open market.

On September 22, 2017, PVP V sold 40,562 shares of Common Stock on the open market, PVPE V sold 790 shares of Common Stock on the open market, PVPFF V sold 278 shares of Common Stock on the open market, and PVPSFF V sold 406 shares of Common Stock on the open market.

On September 25, 2017, PVP V sold 35,872 shares of Common Stock on the open market, PVPE V sold 699 shares of Common Stock on the open market, PVPFF V sold 245 shares of Common Stock on the open market, and PVPSFF V sold 359 shares of Common Stock on the open market.

On September 26, 2017, PVP V sold 67,764 shares of Common Stock on the open market, PVPE V sold 1,321 shares of Common Stock on the open market, PVPFF V sold 464 shares of Common Stock on the open market, and PVPSFF V sold 677 shares of Common Stock on the open market.

Item 5. Interest in Securities of the Issuer.

Items 5(a) and (c) of the Schedule 13D are hereby amended and restated in their entirety as follows:

The information below is based on a total of 22,074,378 shares of Common Stock outstanding as reported on the Issuer’s Form 10-Q, Quarterly Report Pursuant to Section 13 or 15(d) of the Security Exchange Act of 1934 filed with the SEC on August 11, 2017.

(a) PVP V beneficially owns 1,628,440 shares of Common Stock, or approximately 7.4% of the Common Stock outstanding, of which 1,550,478 shares are directly owned by PVP V and 77,962 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVP V. PVPE V beneficially owns 31,734 shares of Common Stock, or approximately 0.1% of the Common Stock outstanding, of which 30,215 shares are directly owned by PVPE V and 1,519 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPE V. PVPFF V beneficially owns 11,152 shares of Common Stock, or approximately 0.1% of the Common Stock outstanding, of which 10,618 shares are directly owned by PVPFF V and 534 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPFF V. PVPSFF V beneficially owns 19,518 shares of Common Stock, or approximately 0.1% of the Common Stock outstanding, of which 15,502 shares are directly owned by PVPSFF V and 4,016 shares represent underlying Common Stock pursuant to a warrant exercisable within 60 days issued to PVPSFF V. PVM V, the general partner of PVP V, PVPE V, PVPFF V and PVPSFF V, may be deemed to indirectly beneficially own the securities owned by PVP V, PVPE V, PVPFF V and PVPSFF V. Each of Flint, McGuire and Nashat, in their respective capacities with respect to PVM V, may be deemed to indirectly beneficially own the securities owned by each of PVP V, PVPE V, PVPFF V and PVPSFF V. Each of PVM, Flint, McGuire and Nashat disclaim beneficial ownership of the securities owned by each of PVP V, PVPE V, PVPFF V and PVPSFF V and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for any purpose, except to the extent of their respective pecuniary interests therein.

(c) Except as described in this statement and this Item 5(c), none of the Reporting Persons has effected any transactions in the Common Stock in the 60 days prior to the date of this statement.

Item 7. Material to be Filed as Exhibits.

Exhibit A—Joint Filing Agreement

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: September 29, 2017


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/ Max Eisenberg
Name:		Max Eisenberg
		Attorney-in-Fact

[This Schedule 13D was executed pursuant to a Power of Attorney. Note that copies of the applicable Powers of Attorney are already on file with the appropriate agencies.]

EX-99.A

Exhibit A

AGREEMENT REGARDING THE JOINT FILING OF

SCHEDULE 13D

The undersigned, being duly authorized thereunto, hereby execute this agreement as an exhibit to this Schedule 13D to evidence the agreement of the below-named parties, in accordance with the rules promulgated pursuant to the Securities Exchange Act of 1934, to file this Schedule jointly on behalf of each such party.

Date: September 29, 2017


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/ Max Eisenberg
Name:		Max Eisenberg
		Attorney-in-Fact

[This Schedule 13D was executed pursuant to a Power of Attorney. Note that copies of the applicable Powers of Attorney are already on file with the appropriate agencies.]