Polaris Partners

One Marina Park Drive, 10^th Floor

Boston, MA 02210

Attn: Max Eisenberg

(855) 787-3500

Gunderson Dettmer Stough Villeneuve

Franklin & Hachigian, LLP

One Marina Park Drive, Suite 900

Boston, MA 02210

Attn: Jay K. Hachigian, Esq.

(617) 648-9100

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.

Names of Reporting Persons.

Polaris Venture Partners IV, L.P. (“PVP IV”)

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Source of Funds (See Instructions)

WC

Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)

☐

Citizenship or Place of Organization

Delaware

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power

141,098 shares⁽¹⁾, except that (i) Polaris Venture Management Co. IV, L.L.C. (“PVM IV”), the general partner of PVP IV, may be deemed to have sole power to vote these shares, and (ii) Jonathan A. Flint (“Flint”), a managing member of PVM IV, may be deemed to have shared power to vote these shares and Terrance G. McGuire (“McGuire”), a managing member of PVM IV, may be deemed to have shared power to vote these shares.

Shared Voting Power

See response to row 7.

Sole Dispositive Power

141,098 shares⁽¹⁾, except that (i) PVM IV, the general partner of PVP IV, may be deemed to have sole power to dispose of these shares, and (ii) Flint, a managing member of PVM IV, may be deemed to have shared power to dispose of these shares and McGuire, a managing member of PVM IV, may be deemed to have shared power to dispose of these shares.

Shared Dispositive Power

See response to row 9.

Aggregate Amount Beneficially Owned by Each Reporting Person

141,098 shares⁽¹⁾

Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (11)

1.2%⁽²⁾

Type of Reporting Person (See Instructions)

PN

Consists of (a) 140,574 shares of Common Stock held by PVP IV and (b) 524 shares of Common Stock issuable upon exercise of warrants held by PVP IV.

Based on 11,422,161 shares of the Issuer’s Common Stock outstanding, as adjusted to reflect the additional 524 shares of Common Stock which would be outstanding following the exercise of the warrants held by PVP IV.

Names of Reporting Persons.

Polaris Venture Partners Entrepreneurs’ Fund IV, L.P. (“PVPE IV”)

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Source of Funds (See Instructions)

WC

Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)

☐

Citizenship or Place of Organization

Delaware

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power

2,644 shares⁽¹⁾, except that (i) PVM IV, the general partner of PVPE IV, may be deemed to have sole power to vote these shares, and (ii) Flint, a managing member of PVM IV, may be deemed to have shared power to vote these shares and McGuire, a managing member of PVM IV, may be deemed to have shared power to vote these shares.

Shared Voting Power

See response to row 7.

Sole Dispositive Power

2,644 shares⁽¹⁾, except that (i) PVM IV, the general partner of PVPE IV, may be deemed to have sole power to dispose of these shares, and (ii) Flint, a managing member of PVM IV, may be deemed to have shared power to dispose of these shares and McGuire, a managing member of PVM IV, may be deemed to have shared power to dispose of these shares.

Shared Dispositive Power

See response to row 9.

Aggregate Amount Beneficially Owned by Each Reporting Person

2,644 shares⁽¹⁾

Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (11)

0.0%⁽²⁾

Type of Reporting Person (See Instructions)

PN

Consists of (a) 2,635 shares of Common Stock held by PVPE IV and (b) 9 shares of Common Stock issuable upon exercise of warrants held by PVPE IV.

Based on 11,422,161 shares of the Issuer’s Common Stock outstanding, as adjusted to reflect the additional 524 shares of Common Stock which would be outstanding following the exercise of the warrants held by PVP IV.

Names of Reporting Persons.

Polaris Venture Management Co. IV, L.L.C. (“PVM IV”)

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Source of Funds (See Instructions)

WC

Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)

☐

Citizenship or Place of Organization

Delaware

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power

143,742 shares, of which 141,098 shares are directly owned by PVP IV⁽¹⁾ and 2,644 shares are directly owned by PVPE IV⁽²⁾, except that Flint, a managing member of PVM IV (which is general partner of PVP IV and PVPE IV), may be deemed to have shared power to vote these shares and McGuire, a managing member of PVM IV, may be deemed to have shared power to vote these shares.

Shared Voting Power

See response to row 7.

Sole Dispositive Power

143,742 shares, of which 141,098 shares are directly owned by PVP IV⁽¹⁾ and 2,644 shares are directly owned by PVPE IV⁽²⁾, except that Flint, a managing member of PVM IV (which is general partner of PVP IV and PVPE IV), may be deemed to have shared power to dispose of these shares and McGuire, a managing member of PVM IV, may be deemed to have shared power to dispose of these shares.

Shared Dispositive Power

See response to row 9.

Aggregate Amount Beneficially Owned by Each Reporting Person

143,742 shares^{(1), (2)}

Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (11)

1.3%⁽³⁾

Type of Reporting Person (See Instructions)

OO

Consists of (a) 140,574 shares of Common Stock held by PVP IV and (b) 524 shares of Common Stock issuable upon exercise of warrants held by PVP IV.

Consists of (a) 2,635 shares of Common Stock held by PVPE IV and (b) 9 shares of Common Stock issuable upon exercise of warrants held by PVPE IV.

Based on 11,422,161 shares of the Issuer’s Common Stock outstanding, as adjusted to reflect the additional 533 shares of Common Stock which would be outstanding following the exercise of the warrants held by PVP IV and PVPE IV.

Names of Reporting Persons.

Jonathan A. Flint

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Source of Funds (See Instructions)

AF

Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)

☐

Citizenship or Place of Organization

Delaware

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power

143,742 shares, of which 141,098 shares are directly owned by PVP IV⁽¹⁾ and 2,644 shares are directly owned by PVPE IV⁽²⁾, except that PVM IV, as the general partner of PVP IV and PVPE IV, may be deemed to have sole power to vote PVP IV’s and PVPE IV’s shares (collectively the “Fund IV Shares”) and McGuire, as a managing member of PVM IV, may be deemed to have shared power to vote the Fund IV Shares.

Shared Voting Power

See response to row 7.

Sole Dispositive Power

143,742 shares, of which 141,098 shares are directly owned by PVP IV⁽¹⁾ and 2,644 shares are directly owned by PVPE IV⁽²⁾, except that PVM IV, as the general partner of PVP IV and PVPE IV, may be deemed to have sole power to dispose of the Fund IV Shares and McGuire, as a managing member of PVM IV, may be deemed to have shared power to dispose of the Fund IV Shares.

Shared Dispositive Power

See response to row 9.

Aggregate Amount Beneficially Owned by Each Reporting Person

143,742 shares^{(1), (2)}

Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (11)

1.3%⁽³⁾

Type of Reporting Person (See Instructions)

IN

Consists of (a) 140,574 shares of Common Stock held by PVP IV and (b) 524 shares of Common Stock issuable upon exercise of warrants held by PVP IV.

Consists of (a) 2,635 shares of Common Stock held by PVPE IV and (b) 9 shares of Common Stock issuable upon exercise of warrants held by PVPE IV.

Based on 11,422,161 shares of the Issuer’s Common Stock outstanding, as adjusted to reflect the additional 533 shares of Common Stock which would be outstanding following the exercise of the warrants held by PVP IV and PVPE IV.

Names of Reporting Persons.

Terrance G. McGuire

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Source of Funds (See Instructions)

AF

Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d) or 2(e)

☐

Citizenship or Place of Organization

Delaware

Number of

Shares

Beneficially

Owned by

Each

Reporting

Person

With

Sole Voting Power

143,742 shares, of which 141,098 shares are directly owned by PVP IV⁽¹⁾ and 2,644 shares are directly owned by PVPE IV⁽²⁾, except that PVM IV, as the general partner of PVP IV and PVPE IV, may be deemed to have sole power to vote the Fund IV Shares and Flint, as a managing member of PVM IV, may be deemed to have shared power to vote the Fund IV Shares.

Shared Voting Power

See response to row 7.

Sole Dispositive Power

143,742 shares, of which 141,098 shares are directly owned by PVP IV⁽¹⁾ and 2,644 shares are directly owned by PVPE IV⁽²⁾, except that PVM IV, as the general partner of PVP IV and PVPE IV, may be deemed to have sole power to dispose of the Fund IV Shares and Flint, as a managing member of PVM IV, may be deemed to have shared power to dispose of the Fund IV Shares.

Shared Dispositive Power

See response to row 9.

Aggregate Amount Beneficially Owned by Each Reporting Person

143,742 shares^{(1), (2)}

Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (11)

1.3% ⁽³⁾

Type of Reporting Person (See Instructions)

IN

Consists of (a) 140,574 shares of Common Stock held by PVP IV and (b) 524 shares of Common Stock issuable upon exercise of warrants held by PVP IV.

Consists of (a) 2,635 shares of Common Stock held by PVPE IV and (b) 9 shares of Common Stock issuable upon exercise of warrants held by PVPE IV.

Based on 11,422,161 shares of the Issuer’s Common Stock outstanding, as adjusted to reflect the additional 533 shares of Common Stock which would be outstanding following the exercise of the warrants held by PVP IV and PVPE IV.

/s/ Max Eisenberg

/s/ Max Eisenberg