Flint Jonathan A

Row 1 · Balance 3,120,194

F1: These shares are held of record by Polaris Venture Partners V, L.P. ("PVP V"). The general partner of PVP V is Polaris Venture Management Co. V, L.L.C. ("PVM V") and may be deemed to have shared voting and investment power with respect to the shares held by PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of the securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein. McGuire is a director of the Issuer and, accordingly, files separate Section 16 reports.

Row 2 · Balance 60,814

F2: These shares are held of record by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). The general partner of PVPEF V is PVM V and may be deemed to have shared voting and investment power with respect to the shares held by PVPEF V. Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPEF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of the securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein. McGuire is a director of the Issuer and, accordingly, files separate Section 16 reports.

Row 3 · Balance 21,374

F3: These shares are held of record by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). The general partner of PVPFF V is PVM V and may be deemed to have shared voting and investment power with respect to the shares held by PVPFF V. Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPEF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of the securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein. McGuire is a director of the Issuer and, accordingly, files separate Section 16 reports.

Row 4 · Balance 31,198

F4: These shares are held of record by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). The general partner of PVPSFF V is PVM V and may be deemed to have shared voting and investment power with respect to the shares held by PVPSFF V. Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPEF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of the securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein. McGuire is a director of the Issuer and, accordingly, files separate Section 16 reports.

Row 5 · Balance 4,800,460

F5: These shares are held of record by Polaris Partners IX, L.P. ("PP IX"). The general partner of PP IX is Polaris Partners GP IX, L.L.C. ("PPGP IX") and may be deemed to have shared voting and investment power with respect to the shares held by PP IX. Each of David Barrett ("Barrett"), Brian Chee ("Chee"), Amir Nashat ("Nashat") and Amy Schulman ("Schulman") are the managing members of PPGP IX (collectively, the "PPGP IX Managing Members"), and McGuire is an interest holder in PPGP IX, and may be deemed to have shared voting and dispositive power over the shares held by PP IX. Each of PPGP IX, the PPGP IX Managing Members and McGuire disclaims beneficial ownership of the securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F6: (Continued from footnote 5) McGuire is a director of the Issuer and, accordingly, files separate Section 16 reports.

Row 6 · Balance 497,660

F7: These shares are held of record by Polaris Healthcare Technology Opportunities Fund, L.P. ("PHCT"). The general partner of PHCT is Polaris Healthcare Technology Opportunities Fund GP, L.L.C. ("PHCT GP") and may be deemed to have shared voting and investment power with respect to the shares held by PHCT. Each of Barrett, Chee, Nashat and Schulman are the managing members of PHCT GP (collectively, the "PHCT GP Managing Members"), and McGuire is an interest holder in PHCT GP, and may be deemed to have shared voting and dispositive power over the shares held by PHCT. Each of PHCT GP, the PHCT GP Managing Members and McGuire disclaims beneficial ownership of the securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F8: (Continued from footnote 7) McGuire is a director of the Issuer and, accordingly, files separate Section 16 reports.

Row 1 · 2020-05-05 · Conversion · Acquired 993,981 · Balance 993,981

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 2 · 2020-05-05 · Conversion · Acquired 19,370 · Balance 19,370

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 3 · 2020-05-05 · Conversion · Acquired 9,936 · Balance 9,936

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 4 · 2020-05-05 · Conversion · Acquired 6,807 · Balance 6,807

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 5 · 2020-05-05 · Other · Acquired 17,304 · Balance 1,011,285

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 6 · 2020-05-05 · Sale · Disposed 9,334 · Balance 1,001,951

F6: On May 5, 2020, PVP V exercised a warrant to purchase 17,304 shares of the Issuer's common stock for $16.00 a share, which represents the Issuer's initial public offering price. In connection with the automatic net exercise of the warrant immediately prior to the closing of the Issuer's initial public offering, the Issuer withheld 9,334 of the warrant shares to pay the exercise price and issued the remaining warrant shares to PVP V. The Issuer also paid $10.48 to PVP V in lieu of a fractional share.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 7 · 2020-05-05 · Other · Acquired 337 · Balance 19,707

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 8 · 2020-05-05 · Sale · Disposed 182 · Balance 19,525

F7: On May 5, 2020, PVPE V exercised a warrant to purchsae 337 shares of the Issuer's common stock for $16.00 a share, which represents the Issuer's initial public offering price. In connection with the automatic net exercise of the warrant immediately prior to the closing of the Issuer's initial public offering, the Issuer withheld 182 of the warrant shares to pay the exercise price and issued the remaining warrant shares to PVPE V. The Issuer also paid $3.69 to PVPE V in lieu of a fractional share.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 9 · 2020-05-05 · Other · Acquired 173 · Balance 10,109

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 10 · 2020-05-05 · Sale · Disposed 94 · Balance 10,015

F8: On May 5, 2020, PVPSFF V exercised a warrant to purchase 173 shares of the Issuer's common stock for $16.00 a share, which represents the Issuer's initial public offering price. In connection with the automatic net exercise of the warrant immediately prior to the closing of the Issuer's initial public offering, the Issuer withheld 94 of the warrant shares to pay the exercise price and issued the remaining warrant shares to PVPSFF V. The Issuer also paid $11.01 to PVPSFF V in lieu of a fractional share.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 11 · 2020-05-05 · Other · Acquired 118 · Balance 6,925

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 12 · 2020-05-05 · Sale · Disposed 64 · Balance 6,861

F9: On May 5, 2020, PVPFF V exercised a warrant to purchase 118 shares of the Issuer's common stock for $16.00 a share, which represents the Issuer's initial public offering price. In connection with the automatic net exercise of the warrant immediately prior to the closing of the Issuer's initial public offering, the Issuer withheld 64 of the warrant shares to pay the exercise price and issued the remaining warrant shares to PVPFF V. The Issuer also paid $5.66 to the PVPFF V in lieu of a fractional share.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 13 · 2020-05-05 · Purchase · Acquired 60,308 · Balance 1,062,259

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 14 · 2020-05-05 · Purchase · Acquired 1,176 · Balance 20,701

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 15 · 2020-05-05 · Purchase · Acquired 603 · Balance 10,618

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 16 · 2020-05-05 · Purchase · Acquired 413 · Balance 7,274

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 17 · 2020-05-05 · Conversion · Disposed 6,268,687 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 18 · 2020-05-05 · Conversion · Disposed 122,177 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 19 · 2020-05-05 · Conversion · Disposed 62,687 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 20 · 2020-05-05 · Conversion · Disposed 42,941 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 21 · 2020-05-05 · Conversion · Disposed 3,296,014 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 22 · 2020-05-05 · Conversion · Disposed 64,237 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 23 · 2020-05-05 · Conversion · Disposed 32,961 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 24 · 2020-05-05 · Conversion · Disposed 22,580 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 25 · 2020-05-05 · Conversion · Disposed 8,610,081 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 26 · 2020-05-05 · Conversion · Disposed 167,809 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 27 · 2020-05-05 · Conversion · Disposed 86,101 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 28 · 2020-05-05 · Conversion · Disposed 58,980 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 29 · 2020-05-05 · Conversion · Disposed 7,693,406 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 30 · 2020-05-05 · Conversion · Disposed 149,944 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 31 · 2020-05-05 · Conversion · Disposed 76,934 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 32 · 2020-05-05 · Conversion · Disposed 52,700 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 33 · 2020-05-05 · Conversion · Disposed 6,418,387 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 34 · 2020-05-05 · Conversion · Disposed 125,094 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 35 · 2020-05-05 · Conversion · Disposed 64,183 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 36 · 2020-05-05 · Conversion · Disposed 43,966 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 37 · 2020-05-05 · Conversion · Disposed 1,988,991 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 38 · 2020-05-05 · Conversion · Disposed 38,765 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 39 · 2020-05-05 · Conversion · Disposed 19,890 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 40 · 2020-05-05 · Conversion · Disposed 13,625 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 41 · 2020-05-05 · Other · Disposed 17,304 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners V, L.P. ("PVP V"). Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 42 · 2020-05-05 · Other · Disposed 337 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F3: The reportable securities are owned directly by Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"). PVM V is the general partner of PVPE V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 43 · 2020-05-05 · Other · Disposed 173 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V"). PVM V is the general partner of PVPSFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 44 · 2020-05-05 · Other · Disposed 118 · Balance 0

F1: Each share of preferred stock was automatically converted into 0.0289998 shares of common stock upon the closing of the Issuer's initial public offering. The preferred stock had no expiration date.

F5: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"). PVM V is the general partner of PVPFF V. Each of Flint and McGuire are the managing members of PVM V and may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 1 · 2018-04-03 · Purchase · Acquired 345,551 · Balance 1,556,676

F1: The reported securities were included within 345,551 Units purchased by Polaris Venture Partners IV, L.P. ("PVP IV") for $0.65 per Unit (each, a "Unit"). Each Unit consisted of one share of common stock, one Series A Warrant to purchase one share of common stock at an exercise price of $0.65 per share, and one Series B Warrant to purchase one share of common stock at an exercise price of $0.75 per share.

F2: Securities held of record by PVP IV.

F3: Polaris Venture Management Co. IV, L.L.C. ("PVM IV") is the general partner of PVP IV and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM IV, may be deemed to have shared voting and dispositive power over the shares held by each of PVP IV and PVPE IV.

F4: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 2 · 2018-04-03 · Purchase · Acquired 6,478 · Balance 29,178

F5: The reported securities were included within 6,478 Units purchased by PVPE IV.

F3: Polaris Venture Management Co. IV, L.L.C. ("PVM IV") is the general partner of PVP IV and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM IV, may be deemed to have shared voting and dispositive power over the shares held by each of PVP IV and PVPE IV.

F4: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F6: Securities held of record by PVPE IV.

Row 3 · 2018-04-03 · Purchase · Acquired 769,989 · Balance 3,468,190

F7: The reported securities were included within 769,989 Units purchased by Polaris Venture Partners V, L.P. ("PVP V").

F8: Securities held of record by PVP V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 4 · 2018-04-03 · Purchase · Acquired 15,007 · Balance 67,729

F11: The reported securities were included within 15,007 Units purchased by PVPEF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F12: Securities held of record by PVPEF V.

Row 5 · 2018-04-03 · Purchase · Acquired 5,275 · Balance 23,875

F13: The reported securities were included within 5,275 Units purchased by PVPFF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F14: Securities held of record by PVPFF V.

Row 6 · 2018-04-03 · Purchase · Acquired 7,700 · Balance 34,587

F15: The reported securities were included within 7,700 Units purchased by PVPSFF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F16: Securities held of record by PVPSFF V.

Row 7 · 2018-04-03 · Purchase · Acquired 345,551 · Balance 345,551

F1: The reported securities were included within 345,551 Units purchased by Polaris Venture Partners IV, L.P. ("PVP IV") for $0.65 per Unit (each, a "Unit"). Each Unit consisted of one share of common stock, one Series A Warrant to purchase one share of common stock at an exercise price of $0.65 per share, and one Series B Warrant to purchase one share of common stock at an exercise price of $0.75 per share.

F2: Securities held of record by PVP IV.

F3: Polaris Venture Management Co. IV, L.L.C. ("PVM IV") is the general partner of PVP IV and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM IV, may be deemed to have shared voting and dispositive power over the shares held by each of PVP IV and PVPE IV.

F4: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 9 · 2018-04-03 · Purchase · Acquired 6,478 · Balance 6,478

F5: The reported securities were included within 6,478 Units purchased by PVPE IV.

F3: Polaris Venture Management Co. IV, L.L.C. ("PVM IV") is the general partner of PVP IV and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM IV, may be deemed to have shared voting and dispositive power over the shares held by each of PVP IV and PVPE IV.

F4: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F6: Securities held of record by PVPE IV.

Row 11 · 2018-04-03 · Purchase · Acquired 769,989 · Balance 769,989

F7: The reported securities were included within 769,989 Units purchased by Polaris Venture Partners V, L.P. ("PVP V").

F8: Securities held of record by PVP V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 13 · 2018-04-03 · Purchase · Acquired 15,007 · Balance 15,007

F11: The reported securities were included within 15,007 Units purchased by PVPEF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F12: Securities held of record by PVPEF V.

Row 15 · 2018-04-03 · Purchase · Acquired 5,275 · Balance 5,275

F13: The reported securities were included within 5,275 Units purchased by PVPFF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F14: Securities held of record by PVPFF V.

Row 17 · 2018-04-03 · Purchase · Acquired 7,700 · Balance 7,700

F15: The reported securities were included within 7,700 Units purchased by PVPSFF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F16: Securities held of record by PVPSFF V.

Row 8 · 2018-04-03 · Purchase · Acquired 345,551 · Balance 345,551

F1: The reported securities were included within 345,551 Units purchased by Polaris Venture Partners IV, L.P. ("PVP IV") for $0.65 per Unit (each, a "Unit"). Each Unit consisted of one share of common stock, one Series A Warrant to purchase one share of common stock at an exercise price of $0.65 per share, and one Series B Warrant to purchase one share of common stock at an exercise price of $0.75 per share.

F2: Securities held of record by PVP IV.

F3: Polaris Venture Management Co. IV, L.L.C. ("PVM IV") is the general partner of PVP IV and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM IV, may be deemed to have shared voting and dispositive power over the shares held by each of PVP IV and PVPE IV.

F4: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 10 · 2018-04-03 · Purchase · Acquired 6,478 · Balance 6,478

F5: The reported securities were included within 6,478 Units purchased by PVPE IV.

F3: Polaris Venture Management Co. IV, L.L.C. ("PVM IV") is the general partner of PVP IV and Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM IV, may be deemed to have shared voting and dispositive power over the shares held by each of PVP IV and PVPE IV.

F4: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F6: Securities held of record by PVPE IV.

Row 12 · 2018-04-03 · Purchase · Acquired 769,989 · Balance 769,989

F7: The reported securities were included within 769,989 Units purchased by Polaris Venture Partners V, L.P. ("PVP V").

F8: Securities held of record by PVP V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

Row 14 · 2018-04-03 · Purchase · Acquired 15,007 · Balance 15,007

F11: The reported securities were included within 15,007 Units purchased by PVPEF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F12: Securities held of record by PVPEF V.

Row 16 · 2018-04-03 · Purchase · Acquired 5,275 · Balance 5,275

F13: The reported securities were included within 5,275 Units purchased by PVPFF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F14: Securities held of record by PVPFF V.

Row 18 · 2018-04-03 · Purchase · Acquired 7,700 · Balance 7,700

F15: The reported securities were included within 7,700 Units purchased by PVPSFF V.

F9: Polaris Venture Management Co. V, LLC ("PVM V") is the general partner of PVP V, Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V"), Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") and Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPEF V"). Each of Jonathan A. Flint and Terrance G. McGuire are the managing members of PVM V. PVM V disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM V is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint and Terrance G. McGuire, in their respective capacities with regard to PVM V, may be deemed to have shared voting and dispositive power over the shares held by each of PVP V, PVPFF V, PFPSFF V and PVPEF V.

F10: Each of Messrs. Flint and McGuire disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

F16: Securities held of record by PVPSFF V.

Row 1 · 2017-11-20 · Conversion · Acquired 18,848 · Balance 18,848

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 5 · 2017-11-20 · Conversion · Acquired 243,385 · Balance 262,233

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 9 · 2017-11-20 · Conversion · Acquired 317,376 · Balance 579,609

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 13 · 2017-11-20 · Conversion · Acquired 110,312 · Balance 689,921

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 17 · 2017-11-20 · Conversion · Acquired 631,041 · Balance 1,320,962

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 21 · 2017-11-20 · Purchase · Acquired 482,467 · Balance 1,803,429

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 2 · 2017-11-20 · Conversion · Acquired 367 · Balance 367

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 3 · 2017-11-20 · Conversion · Acquired 129 · Balance 129

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 4 · 2017-11-20 · Conversion · Acquired 188 · Balance 188

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 6 · 2017-11-20 · Conversion · Acquired 4,743 · Balance 5,110

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 7 · 2017-11-20 · Conversion · Acquired 1,667 · Balance 1,796

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 8 · 2017-11-20 · Conversion · Acquired 2,433 · Balance 2,621

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 10 · 2017-11-20 · Conversion · Acquired 6,185 · Balance 11,295

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 11 · 2017-11-20 · Conversion · Acquired 2,173 · Balance 3,969

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 12 · 2017-11-20 · Conversion · Acquired 3,173 · Balance 5,794

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 14 · 2017-11-20 · Conversion · Acquired 2,150 · Balance 13,445

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 15 · 2017-11-20 · Conversion · Acquired 755 · Balance 4,724

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 16 · 2017-11-20 · Conversion · Acquired 1,102 · Balance 6,896

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 18 · 2017-11-20 · Conversion · Acquired 12,298 · Balance 25,743

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 19 · 2017-11-20 · Conversion · Acquired 4,322 · Balance 9,046

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 20 · 2017-11-20 · Conversion · Acquired 6,310 · Balance 13,206

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 22 · 2017-11-20 · Purchase · Acquired 9,403 · Balance 35,146

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 23 · 2017-11-20 · Purchase · Acquired 3,305 · Balance 12,351

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 24 · 2017-11-20 · Purchase · Acquired 4,825 · Balance 18,031

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 25 · 2017-11-20 · Conversion · Disposed 64,329 · Balance 0

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 26 · 2017-11-20 · Conversion · Disposed 1,254 · Balance 0

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 27 · 2017-11-20 · Conversion · Disposed 441 · Balance 0

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 28 · 2017-11-20 · Conversion · Disposed 643 · Balance 0

F1: The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 29 · 2017-11-20 · Conversion · Disposed 680,130 · Balance 0

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 30 · 2017-11-20 · Conversion · Disposed 13,256 · Balance 0

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 31 · 2017-11-20 · Conversion · Disposed 4,659 · Balance 0

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 32 · 2017-11-20 · Conversion · Disposed 6,801 · Balance 0

F7: The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 33 · 2017-11-20 · Conversion · Disposed 710,817 · Balance 0

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 34 · 2017-11-20 · Conversion · Disposed 13,854 · Balance 0

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 35 · 2017-11-20 · Conversion · Disposed 4,869 · Balance 0

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 36 · 2017-11-20 · Conversion · Disposed 7,108 · Balance 0

F8: The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 37 · 2017-11-20 · Conversion · Disposed 221,638 · Balance 0

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 38 · 2017-11-20 · Conversion · Disposed 4,315 · Balance 0

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 39 · 2017-11-20 · Conversion · Disposed 1,516 · Balance 0

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 40 · 2017-11-20 · Conversion · Disposed 2,213 · Balance 0

F9: The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 41 · 2017-11-20 · Conversion · Disposed 2,153,746 · Balance 0

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F2: These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").

F3: (Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 42 · 2017-11-20 · Conversion · Disposed 41,976 · Balance 0

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F4: These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 43 · 2017-11-20 · Conversion · Disposed 14,752 · Balance 0

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F5: These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.

Row 44 · 2017-11-20 · Conversion · Disposed 21,537 · Balance 0

F10: The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.

F6: These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.