KALA

SEC source: 0000947871-18-000083 · ss77686_4.xml · nonDerivative · entry 2

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 3,022,760

F2 · price: These Shares were purchased in a block order at a price of $14.99.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercised this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F4 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000083 · ss77686_4.xml · nonDerivative · entry 1

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,972,760

F1 · price: The price reported in Column 4 is a weighted average price. These shares of the Issuer's common stock ("Shares") were purchased in multiple transactions at prices ranging from $14.85 to $14.99 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the Securities and Exchange Commission full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercised this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F4 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000049 · ss76870_4.xml · nonDerivative · entry 5

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,950,000

F5 · price: The price reported in Column 4 is a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $14.75 to $14.99 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the SEC full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F6 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F7 · ownership.nature: Samuel D. Isaly, who was included as a Reporting Person on previous reports under Section 16 of the Exchange Act filed by GP VI and Advisors, is no longer subject to Section 16 with respect to securities of the Issuer.

F8 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000049 · ss76870_4.xml · nonDerivative · entry 4

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,885,363

F4 · price: The price reported in Column 4 is a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $14.96 to $14.99 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the SEC full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F6 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F7 · ownership.nature: Samuel D. Isaly, who was included as a Reporting Person on previous reports under Section 16 of the Exchange Act filed by GP VI and Advisors, is no longer subject to Section 16 with respect to securities of the Issuer.

F8 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000049 · ss76870_4.xml · nonDerivative · entry 3

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,881,000

F3 · price: The price reported in Column 4 is a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $14.86 to $15.00 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the SEC full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F6 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F7 · ownership.nature: Samuel D. Isaly, who was included as a Reporting Person on previous reports under Section 16 of the Exchange Act filed by GP VI and Advisors, is no longer subject to Section 16 with respect to securities of the Issuer.

F8 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000049 · ss76870_4.xml · nonDerivative · entry 2

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,806,000

F2 · price: The price reported in Column 4 is a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $14.75 to $14.99 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the SEC full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F6 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F7 · ownership.nature: Samuel D. Isaly, who was included as a Reporting Person on previous reports under Section 16 of the Exchange Act filed by GP VI and Advisors, is no longer subject to Section 16 with respect to securities of the Issuer.

F8 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000035 · ss75283_4.xml · nonDerivative · entry 3

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

ISALY SAMUEL D · CIK 0001055949 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,692,715

F3 · price: The price reported in Column 4 is a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $14.85 to $15.60 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the SEC full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F4 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, GP VI, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").

F5 · ownership.nature: This report on Form 4 is jointly filed by GP VI, Advisors and Isaly. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the reporting persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000049 · ss76870_4.xml · nonDerivative · entry 1

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,731,069

F1 · price: The price reported in Column 4 is a weighted average price. These shares of the Issuer's common stock ("Shares") were purchased in multiple transactions at prices ranging from $13.85 to $14.84 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the Securities and Exchange Commission (the "SEC") full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F6 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. By virtue of such relationships, GP VI and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the Shares held by OPI VI.

F7 · ownership.nature: Samuel D. Isaly, who was included as a Reporting Person on previous reports under Section 16 of the Exchange Act filed by GP VI and Advisors, is no longer subject to Section 16 with respect to securities of the Issuer.

F8 · ownership.nature: This report on Form 4 is jointly filed by GP VI and Advisors. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000035 · ss75283_4.xml · nonDerivative · entry 2

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

ISALY SAMUEL D · CIK 0001055949 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,664,269

F2 · price: The price reported in Column 4 is a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $13.09 to $13.95 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the SEC full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F4 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, GP VI, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").

F5 · ownership.nature: This report on Form 4 is jointly filed by GP VI, Advisors and Isaly. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the reporting persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0000947871-18-000035 · ss75283_4.xml · nonDerivative · entry 1

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner

ISALY SAMUEL D · CIK 0001055949 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,622,569

F1 · price: The price reported in Column 4 is a weighted average price. These shares of the Issuer's common stock ("Shares") were purchased in multiple transactions at prices ranging from $12.30 to $13.15 inclusive. Upon request, the Reporting Persons undertakes to provide the Issuer, any security holder of the Issuer, or the Securities and Exchange Commission (the "SEC") full information regarding the Shares purchased at each separate price within the range set forth in this footnote.

F4 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, GP VI, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").

F5 · ownership.nature: This report on Form 4 is jointly filed by GP VI, Advisors and Isaly. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the reporting persons is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act, or for any other purposes.

SEC source: 0001179110-17-014415 · edgar.xml · derivative · entry 1

Bazemore Todd · CIK 0001605767 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 172,000

Underlying: Common Stock · 172,000 shares

Expires 2027-11-19

F1 · derivative.exercise_date: This option was granted on November 20, 2017 and vests over four years, with 25% of the shares underlying the option vesting on November 20, 2018, and an additional 2.0833% of the shares underlying the option vesting at the end of each successive one-month period thereafter.

SEC source: 0001179110-17-012839 · edgar.xml · derivative · entry 1

KOVEN ANDREW I · CIK 0001258673 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 25,920

Underlying: Common Stock · 25,920 shares

Expires 2027-09-28

F1 · derivative.exercise_date: This option was granted on September 28, 2017 and vests with respect to 1/3 of the shares on the first anniversary of the grant and with respect to an additional 1/36th of the shares on each monthly anniversary thereafter and will vest automatically as to 100% of the unvested portion of such option upon specified change in control events.

SEC source: 0001179110-17-011492 · edgar.xml · derivative · entry 8

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 149,985

Underlying: Common Stock · 12,150 shares

Expires 2026-06-17

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: This option was granted on June 17, 2016 and vests over four years, with 25% of the shares underlying the option vested on June 17, 2017 and an additional 2.0833% vesting at the end of each successive one-month period thereafter.

SEC source: 0001179110-17-011492 · edgar.xml · derivative · entry 7

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,247

Underlying: Common Stock · 44,313 shares

Expires 2024-10-02

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: This option was granted on October 2, 2014 and vests over four years, with 25% of the shares underlying the option vested on September 25, 2015 and an additional 2.0833% vesting at the end of each successive one-month period thereafter.

SEC source: 0001179110-17-011492 · edgar.xml · derivative · entry 6

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,880

Underlying: Common Stock · 16,168 shares

Expires 2023-05-10

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: This option was granted on May 10, 2013 and vests over four years, with 25% of shares underlying the option vesting 12 months after the date the Issuer submits an investigational new drug application for its loteprednol etabonate program and an additional 2.0833% vesting at the end of each successive one-month period thereafter.

SEC source: 0001179110-17-011492 · edgar.xml · derivative · entry 5

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 36,094 shares

Expires 2023-05-10

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The option with respect to these shares is fully vested.

SEC source: 0001179110-17-011492 · edgar.xml · nonDerivative · entry 4

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 108,725

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001179110-17-011492 · edgar.xml · nonDerivative · entry 3

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 96,575

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001179110-17-011492 · edgar.xml · nonDerivative · entry 2

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 52,262

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001179110-17-011492 · edgar.xml · nonDerivative · entry 1

Brazzell Romulus K · CIK 0001298079 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 36,094

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001104659-17-046803 · a4.xml · derivative · entry 4

Hadley Harbor Master Investors (Cayman) L.P. · CIK 0001641080 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 846,566 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The Series C Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · derivative.exercise_date: The Series C Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · derivative.expiration_date: The Series C Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

SEC source: 0001104659-17-046803 · a4.xml · derivative · entry 3

Hadley Harbor Master Investors (Cayman) L.P. · CIK 0001641080 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 888,894 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series B-1 Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series B-1 Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series B-1 Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

SEC source: 0001104659-17-046803 · a4.xml · nonDerivative · entry 2

Hadley Harbor Master Investors (Cayman) L.P. · CIK 0001641080 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 846,566

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · price: The Series C Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

SEC source: 0001104659-17-046803 · a4.xml · nonDerivative · entry 1

Hadley Harbor Master Investors (Cayman) L.P. · CIK 0001641080 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 888,894

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: The Series B-1 Convertible Preferred Stock converted into Common Stock on a 5.2083-for-one basis upon the closing of the Issuer's initial public offering. The shares had no expiration date.

SEC source: 0001179110-17-010704 · edgar.xml · derivative · entry 3

Grunberg Gregory · CIK 0001711080 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Longitude Venture Partners II, L.P.

Disclosed balance after: 0

Underlying: Common Stock · 2,055,946 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F4 · ownership.nature: These shares were held by Longitude Venture Partners II, L.P. The Reporting Person is a member of Longitude Capital Partners II, LLC, the general partner of Longitude Venture Partners II, L.P., and may be deemed to share voting and investment power over these shares. The Reporting Person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010704 · edgar.xml · nonDerivative · entry 2

Grunberg Gregory · CIK 0001711080 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Longitude Venture Partners II, L.P.

Disclosed balance after: 2,270,946

F2 · ownership.nature: These shares are held by Longitude Venture Partners II, L.P. The Reporting Person is a member of Longitude Capital Partners II, LLC, the general partner of Longitude Venture Partners II, L.P., and may be deemed to share voting and investment power over these shares. The Reporting Person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.

F3 · ownership.nature: Includes 215,000 shares of Common Stock acquired by Longitude Venture Partners, II, L.P in the Issuer's initial public offering.

SEC source: 0001179110-17-010704 · edgar.xml · nonDerivative · entry 1

Grunberg Gregory · CIK 0001711080 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Longitude Venture Partners II, L.P.

Disclosed balance after: 2,055,946

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: The Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: These shares are held by Longitude Venture Partners II, L.P. The Reporting Person is a member of Longitude Capital Partners II, LLC, the general partner of Longitude Venture Partners II, L.P., and may be deemed to share voting and investment power over these shares. The Reporting Person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.

SEC source: 0001144204-17-038358 · v471595_4.xml · derivative · entry 4

RA CAPITAL MANAGEMENT, LLC · CIK 0001346824 · Director

RA Capital Healthcare Fund LP · CIK 0001315082 · former 10% owner

Kolchinsky Peter · CIK 0001384859 · former 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 0

Underlying: Common Stock · 846,566 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F6 · shares: Includes (a) 3,627,688 shares of Series C Convertible Preferred Stock that were held by the Fund and (b) 781,482 shares of Series C Convertible Preferred Stock that were held in the Account.

F1 · derivative.exercise_date: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F6 · ownership.nature: Includes (a) 3,627,688 shares of Series C Convertible Preferred Stock that were held by the Fund and (b) 781,482 shares of Series C Convertible Preferred Stock that were held in the Account.

F7 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of the Fund and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser. The Adviser and Mr. Kolchinsky disclaim beneficial ownership of the reported securities in reliance on Rule 16a-1(a)(1)(v) and (vii) and disclaim any obligation to file reports under Section 16 other than as directors by deputization. The Adviser and Dr. Kolchinsky have no pecuniary interest in the reported securities held in the Account and disclaim: (A) beneficial ownership thereof for purposes of Rule 16a-1(a)(2) and (B) beneficial ownership of securities held by the Fund, for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

SEC source: 0001144204-17-038358 · v471595_4.xml · derivative · entry 3

RA CAPITAL MANAGEMENT, LLC · CIK 0001346824 · Director

RA Capital Healthcare Fund LP · CIK 0001315082 · former 10% owner

Kolchinsky Peter · CIK 0001384859 · former 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 0

Underlying: Common Stock · 733,337 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F5 · shares: Includes (a) 3,143,402 shares of Series B Convertible Preferred Stock that were held by the Fund and (b) 676,042 shares of Series B Convertible Preferred Stock that were held in the Account.

F1 · derivative.exercise_date: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F5 · ownership.nature: Includes (a) 3,143,402 shares of Series B Convertible Preferred Stock that were held by the Fund and (b) 676,042 shares of Series B Convertible Preferred Stock that were held in the Account.

F7 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of the Fund and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser. The Adviser and Mr. Kolchinsky disclaim beneficial ownership of the reported securities in reliance on Rule 16a-1(a)(1)(v) and (vii) and disclaim any obligation to file reports under Section 16 other than as directors by deputization. The Adviser and Dr. Kolchinsky have no pecuniary interest in the reported securities held in the Account and disclaim: (A) beneficial ownership thereof for purposes of Rule 16a-1(a)(2) and (B) beneficial ownership of securities held by the Fund, for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

SEC source: 0001144204-17-038358 · v471595_4.xml · nonDerivative · entry 2

RA CAPITAL MANAGEMENT, LLC · CIK 0001346824 · Director

RA Capital Healthcare Fund LP · CIK 0001315082 · former 10% owner

Kolchinsky Peter · CIK 0001384859 · former 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 2,113,236

F3 · shares: Includes (a) 427,043 shares of Common Stock held by the Fund and (b) 106,290 held in the Account, in each case acquired in the Issuer's initial public offering.

F4 · balance_after: These securities include 1,727,100 shares held by the Fund and 386,136 shares held in the Account.

F3 · ownership.nature: Includes (a) 427,043 shares of Common Stock held by the Fund and (b) 106,290 held in the Account, in each case acquired in the Issuer's initial public offering.

F7 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of the Fund and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser. The Adviser and Mr. Kolchinsky disclaim beneficial ownership of the reported securities in reliance on Rule 16a-1(a)(1)(v) and (vii) and disclaim any obligation to file reports under Section 16 other than as directors by deputization. The Adviser and Dr. Kolchinsky have no pecuniary interest in the reported securities held in the Account and disclaim: (A) beneficial ownership thereof for purposes of Rule 16a-1(a)(2) and (B) beneficial ownership of securities held by the Fund, for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

SEC source: 0001144204-17-038358 · v471595_4.xml · nonDerivative · entry 1

RA CAPITAL MANAGEMENT, LLC · CIK 0001346824 · Director

RA Capital Healthcare Fund LP · CIK 0001315082 · former 10% owner

Kolchinsky Peter · CIK 0001384859 · former 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 1,579,903

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: The Series B Preferred Stock and the Series C Preferred Stock converted into Common Stock on a 5.2083-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: Includes (a) 1,300,057 shares of Common Stock that are held by RA Capital Healthcare Fund, L.P.(the "Fund") and (b) 279,846 shares of Common Stock that are held in an account owned by a separately managed account (the "Account").

F7 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of the Fund and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser. The Adviser and Mr. Kolchinsky disclaim beneficial ownership of the reported securities in reliance on Rule 16a-1(a)(1)(v) and (vii) and disclaim any obligation to file reports under Section 16 other than as directors by deputization. The Adviser and Dr. Kolchinsky have no pecuniary interest in the reported securities held in the Account and disclaim: (A) beneficial ownership thereof for purposes of Rule 16a-1(a)(2) and (B) beneficial ownership of securities held by the Fund, for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · derivative · entry 7

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 16,152

Underlying: Common Stock · 16,152 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · derivative.exercise_date: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F7 · derivative.expiration_date: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F9 · ownership.nature: Includes Common Stock Warrants to purchase (a) 15,502 shares of Series Common Stock that are held by Lux Ventures II, L.P. and (b) 650 shares of Common Stock that are held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · derivative · entry 6

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Series B Preferred Stock · 84,130 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · derivative.exercise_price: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F7 · shares: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F7 · derivative.exercise_date: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F7 · derivative.expiration_date: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F7 · derivative.underlying_shares: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F7 · balance_after: The Series B Preferred Stock Warrants were exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrants automatically became exercisable for 16,152 shares of Common Stock at an exercise price of $7.50 per share. The Warrants are exercisable at any time at the holder's election.

F8 · ownership.nature: Includes Series B Convertible Preferred Stock Warrants to purchase (a) 80,744 shares of Series B Convertible Preferred Stock that are held by Lux Ventures II, L.P. and (b) 3,386 shares of Series B Convertible Preferred Stock that are held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · derivative · entry 5

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 6,046 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F6 · ownership.nature: Includes (a) 30,226 shares of Series C Convertible Preferred Stock that were held by Lux Ventures II, L.P. and (b) 1,268 shares of Series C Convertible Preferred Stock that were held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · derivative · entry 4

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 172,829 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F5 · ownership.nature: Includes (a) 863,917 shares of Series B Convertible Preferred Stock that were held by Lux Ventures II, L.P. and (b) 36,229 shares of Series B Convertible Preferred Stock that were held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · derivative · entry 3

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 320,002 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F4 · ownership.nature: Includes (a) 1,599,586 shares of Series A Convertible Preferred Stock that were held by Lux Ventures II, L.P. and (b) 67,080 shares of Series A Convertible Preferred Stock that were held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · derivative · entry 2

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 706,060 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F3 · ownership.nature: Includes (a) 3,529,364 shares of Seed Convertible Preferred Stock that were held by Lux Ventures II, L.P and (b) 148,009 shares of Seed Convertible Preferred Stock that were held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010705 · edgar.xml · nonDerivative · entry 1

Paull Robert Bradley · CIK 0001711254 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 1,204,937

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: Includes (a) 1,156,441 shares of Common Stock that are held by Lux Ventures II, L.P. and (b) 48,496 shares of Common Stock that are held by Lux Ventures II Sidecar, L.P. The Reporting Person is a venture partner at Lux Capital Management, and disclaims beneficial ownership of the shares held by each of Lux Ventures II, L.P. and Lux Ventures II Sidecar, L.P., except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010703 · edgar.xml · derivative · entry 4

Shah Rajeev M. · CIK 0001619841 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 846,566 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F5 · shares: Includes (a) 3,627,688 shares of Series C Convertible Preferred Stock that were held by RA Capital Healthcare Fund, L.P. and (b) 781,482 shares of Series C Convertible Preferred Stock that were held in the Account.

F1 · derivative.exercise_date: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F5 · ownership.nature: Includes (a) 3,627,688 shares of Series C Convertible Preferred Stock that were held by RA Capital Healthcare Fund, L.P. and (b) 781,482 shares of Series C Convertible Preferred Stock that were held in the Account.

F6 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of RA Capital Healthcare Fund, L.P. and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser, and Mr. Shah is a member of the Adviser. Mr. Shah has no pecuniary interest in the reported securities held in the Account and therefore disclaims beneficial ownership of those securities. Mr. Shah disclaims beneficial ownership of the reported securities held by the RA Capital Healthcare Fund, L.P. except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010703 · edgar.xml · derivative · entry 3

Shah Rajeev M. · CIK 0001619841 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 733,337 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F4 · shares: Includes (a) 3,143,402 shares of Series B Convertible Preferred Stock that were held by RA Capital Healthcare Fund, L.P. and (b) 676,042 shares of Series B Convertible Preferred Stock that were held in the Account.

F1 · derivative.exercise_date: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F4 · ownership.nature: Includes (a) 3,143,402 shares of Series B Convertible Preferred Stock that were held by RA Capital Healthcare Fund, L.P. and (b) 676,042 shares of Series B Convertible Preferred Stock that were held in the Account.

F6 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of RA Capital Healthcare Fund, L.P. and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser, and Mr. Shah is a member of the Adviser. Mr. Shah has no pecuniary interest in the reported securities held in the Account and therefore disclaims beneficial ownership of those securities. Mr. Shah disclaims beneficial ownership of the reported securities held by the RA Capital Healthcare Fund, L.P. except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010703 · edgar.xml · nonDerivative · entry 2

Shah Rajeev M. · CIK 0001619841 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 2,113,236

F3 · ownership.nature: Includes (a) 427,043 shares of Common Stock held by RA Capital Healthcare Fund, L.P. and (b) 106,290 held in the Account, in each case acquired in the Issuer's initial public offering.

F6 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of RA Capital Healthcare Fund, L.P. and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser, and Mr. Shah is a member of the Adviser. Mr. Shah has no pecuniary interest in the reported securities held in the Account and therefore disclaims beneficial ownership of those securities. Mr. Shah disclaims beneficial ownership of the reported securities held by the RA Capital Healthcare Fund, L.P. except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010703 · edgar.xml · nonDerivative · entry 1

Shah Rajeev M. · CIK 0001619841 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 1,579,903

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: The Series B Preferred Stock and Series C Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock and Series C Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: Includes (a) 1,300,057 shares of Common Stock that are held by RA Capital Healthcare Fund, L.P. and (b) 279,846 shares of Common Stock that are held in an account owned by a separately managed account (the "Account").

F6 · ownership.nature: RA Capital Management, LLC (the "Adviser") is the general partner of RA Capital Healthcare Fund, L.P. and the investment adviser of the Account. Peter Kolchinsky is the sole manager of the Adviser, and Mr. Shah is a member of the Adviser. Mr. Shah has no pecuniary interest in the reported securities held in the Account and therefore disclaims beneficial ownership of those securities. Mr. Shah disclaims beneficial ownership of the reported securities held by the RA Capital Healthcare Fund, L.P. except to the extent of his pecuniary interest therein.

SEC source: 0001179110-17-010702 · edgar.xml · derivative · entry 6

TEPPER ROBERT I · CIK 0001192595 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 33,333

Underlying: Common Stock · 33,333 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F2 · derivative.expiration_date: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F4 · ownership.nature: These shares are held by TRV. The general partner of TRV is TRV GP. The general partner of TRV GP is TRV GP LLC. The individual managers of TRV GP LLC are Levin, Starr and Tepper. Each of TRV GP, TRV GP LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001179110-17-010702 · edgar.xml · derivative · entry 5

TEPPER ROBERT I · CIK 0001192595 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Series B Preferred Stock · 173,611 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F2 · shares: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F2 · derivative.exercise_date: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F2 · derivative.expiration_date: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F2 · derivative.underlying_shares: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F2 · balance_after: The Series B Preferred Stock Warrant was exercisable for such shares of Preferred Stock at an exercise price of $1.44 per share. Upon the closing of the Issuer's initial public offering, the Warrant automatically became exercisable for 33,333 shares of Common Stock at an exercise price of $7.50 per share. The Warrant is exercisable at any time at the holder's election on or before April 16, 2021.

F3 · ownership.nature: These shares were held by Third Rock Ventures, L.P. ("TRV"). The general partner of TRV is Third Rock Ventures GP, L.P. ("TRV GP"). The general partner of TRV GP is TRV GP, LLC ("TRV GP LLC"). The individual managers of TRV GP LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP, TRV GP LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001179110-17-010702 · edgar.xml · derivative · entry 4

TEPPER ROBERT I · CIK 0001192595 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 435,029 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F3 · ownership.nature: These shares were held by Third Rock Ventures, L.P. ("TRV"). The general partner of TRV is Third Rock Ventures GP, L.P. ("TRV GP"). The general partner of TRV GP is TRV GP, LLC ("TRV GP LLC"). The individual managers of TRV GP LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP, TRV GP LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001179110-17-010702 · edgar.xml · derivative · entry 3

TEPPER ROBERT I · CIK 0001192595 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 480,003 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F3 · ownership.nature: These shares were held by Third Rock Ventures, L.P. ("TRV"). The general partner of TRV is Third Rock Ventures GP, L.P. ("TRV GP"). The general partner of TRV GP is TRV GP, LLC ("TRV GP LLC"). The individual managers of TRV GP LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP, TRV GP LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001179110-17-010702 · edgar.xml · derivative · entry 2

TEPPER ROBERT I · CIK 0001192595 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 0

Underlying: Common Stock · 706,060 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F3 · ownership.nature: These shares were held by Third Rock Ventures, L.P. ("TRV"). The general partner of TRV is Third Rock Ventures GP, L.P. ("TRV GP"). The general partner of TRV GP is TRV GP, LLC ("TRV GP LLC"). The individual managers of TRV GP LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP, TRV GP LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001179110-17-010702 · edgar.xml · nonDerivative · entry 1

TEPPER ROBERT I · CIK 0001192595 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote.

Disclosed balance after: 1,621,092

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock converted into Common Stock on a 5.2083-for-one-basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series Seed Preferred Stock, Series A Preferred Stock and Series B Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F4 · ownership.nature: These shares are held by TRV. The general partner of TRV is TRV GP. The general partner of TRV GP is TRV GP LLC. The individual managers of TRV GP LLC are Levin, Starr and Tepper. Each of TRV GP, TRV GP LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0000947871-17-000581 · ss53130_4.xml · derivative · entry 3

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner · See Remarks

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner · See Remarks

ISALY SAMUEL D · CIK 0001055949 · 10% owner · See Remarks

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 2,055,946 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series C Preferred Stock was converted into Common Stock on a 5.2083-for-one basis.

F2 · derivative.exercise_date: The Series C Preferred Stock was convertible into Common Stock at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · derivative.expiration_date: The Series C Preferred Stock was convertible into Common Stock at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F3 · ownership.nature: The reportable securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, GP VI, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").

F4 · ownership.nature: This report on Form 4 is jointly filed by GP VI, Advisors, and Isaly. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

SEC source: 0000947871-17-000581 · ss53130_4.xml · nonDerivative · entry 2

ORBIMED ADVISORS LLC · CIK 0001055951 · 10% owner · See Remarks

OrbiMed Capital GP VI LLC · CIK 0001682115 · 10% owner · See Remarks

ISALY SAMUEL D · CIK 0001055949 · 10% owner · See Remarks

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 2,375,279

F3 · ownership.nature: The reportable securities are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the sole general partner of OPI VI, and OrbiMed Advisors LLC ("Advisors"), a registered adviser under the Investment Advisors Act of 1940, as amended, is the sole managing member of GP VI. Samuel D. Isaly ("Isaly"), a natural person, is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, GP VI, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by OPI VI noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").

F4 · ownership.nature: This report on Form 4 is jointly filed by GP VI, Advisors, and Isaly. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.