Polaris Venture Management Co. VI, L.L.C.

Row 1 · 2024-05-29 · Other · Disposed 500,000 · Balance 9,853,817

F1: Represents a pro-rata distribution, and not a purchase or sale, without additional consideration by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"), Polaris Venture Partners VI (AIV), L.P. ("PVP VI AIV") and Polaris Venture Partners VI (AIV-B), L.P. (p/k/a PVP VI (AIV) Feeder Corp. Holding Partnership, L.P., "PVP VI AIV-B" and, together with PVPFF VI, PVP VI AIV and Polaris Venture Partners VI, L.P. ("PVP VI"), the "Polaris Funds").

F2: 27,606 shares were distributed by PVPFF VI, 379,180 shares were distributed by PVP VI AIV and 93,214 shares were distributed by PVP VI AIV-B. The general partner of each of the Polaris Funds is Polaris Venture Management Co. VI, L.L.C. ("PVM"). Each of Amir Nashat, Brian Chee, David Barrett, Bryce Youngren, Jonathan Flint, and Terrance McGuire are managing members of PVM (collectively, the "Managing Members") and may be deemed to have shared power to vote and dispose of the shares held by the Polaris Funds.

F3: (Continued from footnote 2) Each of the Managing Members and PVM disclaims beneficial ownership of the securities held by the Polaris Funds, 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 interest therein.

F4: 544,039 shares are held by PVPFF VI, 7,072,644 shares are held by PVP VI AIV, 1,738,666 shares are held by PVP VI AIV-B and 498,468 shares are held by PVP VI. Each of the Managing Members and PVM disclaims beneficial ownership of the securities held by the Polaris Funds, 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 interest therein.

Row 2 · 2024-05-29 · Other · Acquired 98,533 · Balance 98,533

F5: Represents a change in the form of ownership of PVM by virtue of the receipt of shares in the pro-rata in-kind distribution of common stock of the Issuer for no consideration by the Polaris Funds.

F6: Shares held by PVM. 276 shares received from PVPFF VI, 78,869 shares received from PVP VI AIV and 19,388 shares received from PVP VI AIV-B. The Managing Members are managing members of PVM and may be deemed to have shared power to vote and dispose of the shares held by the Polaris Funds.

F7: (Continued from footnote 6) Each of the Managing Members disclaims beneficial ownership of the securities held by the Polaris Funds, 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 interest therein.

Row 3 · 2024-05-29 · Other · Disposed 98,533 · Balance 0

F8: Represents a pro-rata distribution, and not a purchase or sale, without additional consideration by PVM to its members.

F6: Shares held by PVM. 276 shares received from PVPFF VI, 78,869 shares received from PVP VI AIV and 19,388 shares received from PVP VI AIV-B. The Managing Members are managing members of PVM and may be deemed to have shared power to vote and dispose of the shares held by the Polaris Funds.

F7: (Continued from footnote 6) Each of the Managing Members disclaims beneficial ownership of the securities held by the Polaris Funds, 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 interest therein.

Row 1 · 2016-12-07 · Sale · Disposed 75,000 · Balance 3,797,144

F1: Represents 70,859 shares disposed of by Polaris Venture Partners VI, L.P. ("PVP VI") and 4,141 shares disposed of by Polaris Venture Partners Founders' Fund VI, L.P ("PVPFF VI").

F2: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.70 to $15.93, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote (2) to this Form 4.

F3: 3,587,503 of these shares are owned directly by PVP VI and 209,641 of the shares are owned by PVPFF VI (together with PVP VI, the "Polaris Funds"). Polaris Venture Management Co. VI, L.L.C. ("Polaris Management") is the general partner of each of the Polaris Funds. Kevin Bitterman, a member of the Board of Directors of the Issuer, has an assignee interest in Polaris Management. Each of Polaris Management and Mr. Bitterman disclaim beneficial ownership of all the shares owned by the Polaris Funds and this report shall not be deemed an admission that either is the beneficial owner of such shares for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interests therein.

Row 1 · 2018-05-29 · Conversion · Acquired 330,948 · Balance 330,948

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 493,705 · Balance 824,653

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 479,634 · Balance 1,304,287

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 260,670 · Balance 1,564,957

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 693,294 · Balance 2,258,251

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 283,090 · Balance 2,541,341

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Purchase · Acquired 134,970 · Balance 2,676,311

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 19,340 · Balance 19,340

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 28,851 · Balance 48,191

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 28,028 · Balance 76,219

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 15,233 · Balance 91,452

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 40,514 · Balance 131,966

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Acquired 16,542 · Balance 148,508

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Purchase · Acquired 7,887 · Balance 156,395

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 944,789 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 55,211 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 1,409,429 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 82,363 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 1,369,259 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 80,016 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 744,162 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 43,487 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 1,979,216 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 115,659 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 808,166 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F2: The reportable securities are owned directly by Polaris Venture Partners VI, L.P. ("PVP VI"). Polaris Venture Management Co. VI, L.L.C. ("PVM VI") is the general partner of PVP VI. PVM VI is managed by its managing members, one of whom is Dr. Amir Nashat, a member of the Issuer's Board of Directors (collectively, the "Managing Members"). PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVP VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVP VI.

F3: Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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 · 2018-05-29 · Conversion · Disposed 47,225 · Balance 0

F1: Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis upon the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.

F4: The reportable securities are owned directly by Polaris Venture Partners Founders' Fund VI, L.P. ("PVPFF VI"). PVM VI is the general partner of PVPFF VI. PVM VI may be deemed to have sole voting and dispositive power with respect to the shares held by PVPFF VI and the Managing Members may each be deemed to have shared voting and dispositive power with respect to the shares held by PVPFF VI. Each of PVM VI and the Managing Members disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM VI or any of the Managing Members is a 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.