KNSA

SEC source: 0001104659-18-036485 · a4.xml · derivative · entry 5

BOESS CARSTEN · CIK 0001277495 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 473,035

Underlying: Class A Common Shares · 107,050 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.

F4 · derivative.exercise_price: Each share of Class B Common Shares is convertible at any time at the election of the holder into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

F4 · derivative.exercise_date: Each share of Class B Common Shares is convertible at any time at the election of the holder into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

F4 · derivative.expiration_date: Each share of Class B Common Shares is convertible at any time at the election of the holder into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

SEC source: 0001104659-18-036485 · a4.xml · derivative · entry 4

BOESS CARSTEN · CIK 0001277495 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Class A Common Shares · 6,392 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: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

SEC source: 0001104659-18-036485 · a4.xml · derivative · entry 3

BOESS CARSTEN · CIK 0001277495 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Class B Common Shares · 107,050 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.

F3 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

F3 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

F3 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

SEC source: 0001104659-18-036485 · a4.xml · nonDerivative · entry 1

BOESS CARSTEN · CIK 0001277495 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 79,589

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: 0001104659-18-036484 · a4.xml · derivative · entry 6

Mahoney Stephen F. · CIK 0001741389 · President & COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 656,027

Underlying: Class A Common Shares · 107,050 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.

F4 · derivative.exercise_price: Each share of Class B Common Shares is convertible at any time at the election of the holder, subject to certain contractual arrangements entered into between the Reporting Person and the Issuer, into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

F4 · derivative.exercise_date: Each share of Class B Common Shares is convertible at any time at the election of the holder, subject to certain contractual arrangements entered into between the Reporting Person and the Issuer, into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

F4 · derivative.expiration_date: Each share of Class B Common Shares is convertible at any time at the election of the holder, subject to certain contractual arrangements entered into between the Reporting Person and the Issuer, into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

SEC source: 0001104659-18-036484 · a4.xml · derivative · entry 5

Mahoney Stephen F. · CIK 0001741389 · President & COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Class A Common Shares · 6,392 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: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

SEC source: 0001104659-18-036484 · a4.xml · derivative · entry 4

Mahoney Stephen F. · CIK 0001741389 · President & COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Class B Common Shares · 107,050 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.

F3 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

F3 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

F3 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

SEC source: 0001104659-18-036484 · a4.xml · nonDerivative · entry 1

Mahoney Stephen F. · CIK 0001741389 · President & COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 79,589

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: 0001104659-18-036483 · a4.xml · derivative · entry 6

Heberlig Chris · CIK 0001532217 · Exec VP & CFO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 440,920

Underlying: Class A Common Shares · 74,935 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.

F4 · derivative.exercise_price: Each share of Class B Common Shares is convertible at any time at the election of the holder into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

F4 · derivative.exercise_date: Each share of Class B Common Shares is convertible at any time at the election of the holder into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

F4 · derivative.expiration_date: Each share of Class B Common Shares is convertible at any time at the election of the holder into one share of Class A Common Shares or one share of Class B1 Common Shares and will automatically convert into Class A Common Shares upon transfer to an unaffiliated party.

SEC source: 0001104659-18-036483 · a4.xml · derivative · entry 5

Heberlig Chris · CIK 0001532217 · Exec VP & CFO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Class A Common Shares · 6,392 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: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

SEC source: 0001104659-18-036483 · a4.xml · derivative · entry 4

Heberlig Chris · CIK 0001532217 · Exec VP & CFO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Class B Common Shares · 74,935 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.

F3 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

F3 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

F3 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class B Common Shares on a one-for-one basis.

SEC source: 0001104659-18-036483 · a4.xml · nonDerivative · entry 1

Heberlig Chris · CIK 0001532217 · Exec VP & CFO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 42,991

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: 0001193805-18-000778 · e618063_4-kiniksa.xml · derivative · entry 6

Flynn James E · CIK 0001352546 · 10% owner · *Possible member of 10% group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · *Possible member of 10% group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · *Possible member of 10% group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · *Possible member of 10% group

DEERFIELD PARTNERS, L.P. · CIK 0001301041 · 10% owner · *Possible member of 10% group

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

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Special Situations Fund, L.P.

Disclosed balance after: 0

Underlying: Class A Common Stock · 383,538 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: Each share of Series C Preferred Stock converted into one share of the Issuer's Class A Common Stock upon the closing of the Issuer's initial public offering. The number of shares reported herein gives effect to the 1-for-2.73235 reverse stock split of the Issuer's common stock and preferred stock effected by the Issuer in connection with its initial public offering.

F1 · price: Each share of Series C Preferred Stock converted into one share of the Issuer's Class A Common Stock upon the closing of the Issuer's initial public offering. The number of shares reported herein gives effect to the 1-for-2.73235 reverse stock split of the Issuer's common stock and preferred stock effected by the Issuer in connection with its initial public offering.

F1 · derivative.exercise_date: Each share of Series C Preferred Stock converted into one share of the Issuer's Class A Common Stock upon the closing of the Issuer's initial public offering. The number of shares reported herein gives effect to the 1-for-2.73235 reverse stock split of the Issuer's common stock and preferred stock effected by the Issuer in connection with its initial public offering.

F1 · derivative.expiration_date: Each share of Series C Preferred Stock converted into one share of the Issuer's Class A Common Stock upon the closing of the Issuer's initial public offering. The number of shares reported herein gives effect to the 1-for-2.73235 reverse stock split of the Issuer's common stock and preferred stock effected by the Issuer in connection with its initial public offering.

F5 · ownership.nature: This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of each of Deerfield Partners, L.P. and Deerfield Special Situations Fund, L.P. (the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

F6 · ownership.nature: In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

SEC source: 0001193805-18-000778 · e618063_4-kiniksa.xml · nonDerivative · entry 5

Flynn James E · CIK 0001352546 · 10% owner · *Possible member of 10% group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · *Possible member of 10% group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · *Possible member of 10% group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · *Possible member of 10% group

DEERFIELD PARTNERS, L.P. · CIK 0001301041 · 10% owner · *Possible member of 10% group

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

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Partners, L.P.

Disclosed balance after: 843,352

F4 · price: The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $19.00 to $19.255, inclusive.

F5 · ownership.nature: This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of each of Deerfield Partners, L.P. and Deerfield Special Situations Fund, L.P. (the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

F6 · ownership.nature: In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

SEC source: 0001193805-18-000778 · e618063_4-kiniksa.xml · nonDerivative · entry 4

Flynn James E · CIK 0001352546 · 10% owner · *Possible member of 10% group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · *Possible member of 10% group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · *Possible member of 10% group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · *Possible member of 10% group

DEERFIELD PARTNERS, L.P. · CIK 0001301041 · 10% owner · *Possible member of 10% group

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

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Partners, L.P.

Disclosed balance after: 608,333

F3 · price: The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $20.78 to $21.00, inclusive.

F5 · ownership.nature: This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of each of Deerfield Partners, L.P. and Deerfield Special Situations Fund, L.P. (the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

F6 · ownership.nature: In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

SEC source: 0001193805-18-000778 · e618063_4-kiniksa.xml · nonDerivative · entry 3

Flynn James E · CIK 0001352546 · 10% owner · *Possible member of 10% group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · *Possible member of 10% group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · *Possible member of 10% group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · *Possible member of 10% group

DEERFIELD PARTNERS, L.P. · CIK 0001301041 · 10% owner · *Possible member of 10% group

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

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Partners, L.P.

Disclosed balance after: 583,333

F2 · price: The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $19.30 to $20.00, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnotes (2), (3) and (4) of this Form 4.

F5 · ownership.nature: This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of each of Deerfield Partners, L.P. and Deerfield Special Situations Fund, L.P. (the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

F6 · ownership.nature: In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

SEC source: 0001193805-18-000778 · e618063_4-kiniksa.xml · nonDerivative · entry 2

Flynn James E · CIK 0001352546 · 10% owner · *Possible member of 10% group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · *Possible member of 10% group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · *Possible member of 10% group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · *Possible member of 10% group

DEERFIELD PARTNERS, L.P. · CIK 0001301041 · 10% owner · *Possible member of 10% group

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

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Partners, L.P.

Disclosed balance after: 333,333

F5 · ownership.nature: This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of each of Deerfield Partners, L.P. and Deerfield Special Situations Fund, L.P. (the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

F6 · ownership.nature: In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

SEC source: 0001193805-18-000778 · e618063_4-kiniksa.xml · nonDerivative · entry 1

Flynn James E · CIK 0001352546 · 10% owner · *Possible member of 10% group

Deerfield Mgmt L.P. · CIK 0001010823 · 10% owner · *Possible member of 10% group

DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) · CIK 0001009258 · 10% owner · *Possible member of 10% group

Deerfield Special Situations Fund, L.P. · CIK 0001354395 · 10% owner · *Possible member of 10% group

DEERFIELD PARTNERS, L.P. · CIK 0001301041 · 10% owner · *Possible member of 10% group

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

10b5-1 filing: Not disclosed

Ownership: Indirect · Through Deerfield Special Situations Fund, L.P.

Disclosed balance after: 383,538

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: Each share of Series C Preferred Stock converted into one share of the Issuer's Class A Common Stock upon the closing of the Issuer's initial public offering. The number of shares reported herein gives effect to the 1-for-2.73235 reverse stock split of the Issuer's common stock and preferred stock effected by the Issuer in connection with its initial public offering.

F5 · ownership.nature: This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt, L.P. is the general partner of each of Deerfield Partners, L.P. and Deerfield Special Situations Fund, L.P. (the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P. and Deerfield Management Company, L.P.

F6 · ownership.nature: In accordance with Instruction 4(b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 16

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 14,658,102

Underlying: Class A Common Shares · 14,658,102 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.

F12 · derivative.exercise_price: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F12 · derivative.exercise_date: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F12 · derivative.expiration_date: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F12 · derivative.underlying: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F12 · ownership.nature: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 15

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: Class B1 Common Shares · 14,658,102 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.

F11 · derivative.exercise_price: Series A Convertible Preferred Shares of the Issuer ("Series A Preferred") convert on a 1 for 1 basis (the "Series A Conversion Ratio") into Class B1 common shares of the Issuer as per the election of the Adviser at anytime and automatically convert at the Series A Conversion Ratio upon the closing of the Issuer's initial public offering. The Series A Preferred have no expiration date.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F11 · derivative.exercise_date: Series A Convertible Preferred Shares of the Issuer ("Series A Preferred") convert on a 1 for 1 basis (the "Series A Conversion Ratio") into Class B1 common shares of the Issuer as per the election of the Adviser at anytime and automatically convert at the Series A Conversion Ratio upon the closing of the Issuer's initial public offering. The Series A Preferred have no expiration date.

F11 · derivative.expiration_date: Series A Convertible Preferred Shares of the Issuer ("Series A Preferred") convert on a 1 for 1 basis (the "Series A Conversion Ratio") into Class B1 common shares of the Issuer as per the election of the Adviser at anytime and automatically convert at the Series A Conversion Ratio upon the closing of the Issuer's initial public offering. The Series A Preferred have no expiration date.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F12 · ownership.nature: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 14

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 1,399,516

Underlying: Class A Common Shares · 1,399,516 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.

F12 · derivative.exercise_price: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F12 · derivative.exercise_date: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F12 · derivative.expiration_date: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F12 · derivative.underlying: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F12 · ownership.nature: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 13

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: Class B1 Common Shares · 1,399,516 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.

F11 · derivative.exercise_price: Series A Convertible Preferred Shares of the Issuer ("Series A Preferred") convert on a 1 for 1 basis (the "Series A Conversion Ratio") into Class B1 common shares of the Issuer as per the election of the Adviser at anytime and automatically convert at the Series A Conversion Ratio upon the closing of the Issuer's initial public offering. The Series A Preferred have no expiration date.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F11 · derivative.exercise_date: Series A Convertible Preferred Shares of the Issuer ("Series A Preferred") convert on a 1 for 1 basis (the "Series A Conversion Ratio") into Class B1 common shares of the Issuer as per the election of the Adviser at anytime and automatically convert at the Series A Conversion Ratio upon the closing of the Issuer's initial public offering. The Series A Preferred have no expiration date.

F11 · derivative.expiration_date: Series A Convertible Preferred Shares of the Issuer ("Series A Preferred") convert on a 1 for 1 basis (the "Series A Conversion Ratio") into Class B1 common shares of the Issuer as per the election of the Adviser at anytime and automatically convert at the Series A Conversion Ratio upon the closing of the Issuer's initial public offering. The Series A Preferred have no expiration date.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F12 · ownership.nature: Represents conversion of the Issuer's Series A Preferred shares into Class B1 common shares as per the election of the Adviser at the Series A Conversion Ratio upon the closing of the initial public offering of the Issuer. Class B1 common shares are, subject to a beneficial ownership limitation, convertible at the election of the holder on a 1 for 1 basis into either Class B common shares or Class A common shares. The Class B1 common shares have no expiration date. Each Class B1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 12

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 7,018,874

Underlying: Class A Common Shares · 3,284,771 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.

F10 · derivative.exercise_price: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F10 · derivative.exercise_date: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F10 · derivative.expiration_date: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F10 · ownership.nature: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 11

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: Class A1 Common Shares · 3,284,771 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.

F9 · derivative.exercise_price: Series B Convertible Preferred Shares of the Issuer ("Series B Preferred") convert into the Issuer's Class A1 common shares on a 1 for 1 basis (the "Series B Conversion Ratio") as per the election of the Adviser at any time and automatically convert at the Series B Conversion Ratio upon the closing of the Issuer's initial public offering. The Series B Preferred have no expiration date.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F9 · derivative.exercise_date: Series B Convertible Preferred Shares of the Issuer ("Series B Preferred") convert into the Issuer's Class A1 common shares on a 1 for 1 basis (the "Series B Conversion Ratio") as per the election of the Adviser at any time and automatically convert at the Series B Conversion Ratio upon the closing of the Issuer's initial public offering. The Series B Preferred have no expiration date.

F9 · derivative.expiration_date: Series B Convertible Preferred Shares of the Issuer ("Series B Preferred") convert into the Issuer's Class A1 common shares on a 1 for 1 basis (the "Series B Conversion Ratio") as per the election of the Adviser at any time and automatically convert at the Series B Conversion Ratio upon the closing of the Issuer's initial public offering. The Series B Preferred have no expiration date.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F10 · ownership.nature: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 10

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 734,518

Underlying: Class A Common Shares · 313,621 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.

F10 · derivative.exercise_price: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F10 · derivative.exercise_date: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F10 · derivative.expiration_date: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F10 · ownership.nature: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 9

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: Class A1 Common Shares · 313,621 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.

F9 · derivative.exercise_price: Series B Convertible Preferred Shares of the Issuer ("Series B Preferred") convert into the Issuer's Class A1 common shares on a 1 for 1 basis (the "Series B Conversion Ratio") as per the election of the Adviser at any time and automatically convert at the Series B Conversion Ratio upon the closing of the Issuer's initial public offering. The Series B Preferred have no expiration date.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F9 · derivative.exercise_date: Series B Convertible Preferred Shares of the Issuer ("Series B Preferred") convert into the Issuer's Class A1 common shares on a 1 for 1 basis (the "Series B Conversion Ratio") as per the election of the Adviser at any time and automatically convert at the Series B Conversion Ratio upon the closing of the Issuer's initial public offering. The Series B Preferred have no expiration date.

F9 · derivative.expiration_date: Series B Convertible Preferred Shares of the Issuer ("Series B Preferred") convert into the Issuer's Class A1 common shares on a 1 for 1 basis (the "Series B Conversion Ratio") as per the election of the Adviser at any time and automatically convert at the Series B Conversion Ratio upon the closing of the Issuer's initial public offering. The Series B Preferred have no expiration date.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F10 · ownership.nature: Represents conversion of the Issuer's Series B Convertible Preferred shares into Class A1 common shares as per the election of the Adviser upon the closing of the initial public offering of the Issuer. Class A1 common shares are subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 8

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 3,734,103

Underlying: Class A Common Shares · 3,734,103 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.

F8 · derivative.exercise_price: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F8 · derivative.exercise_date: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F8 · derivative.expiration_date: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F8 · ownership.nature: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 7

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: Class A1 Common Shares · 3,734,103 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.

F5 · derivative.exercise_price: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F5 · derivative.exercise_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F5 · derivative.expiration_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F8 · ownership.nature: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 6

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 420,897

Underlying: Class A Common Shares · 420,897 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.

F8 · derivative.exercise_price: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F8 · derivative.exercise_date: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F8 · derivative.expiration_date: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F8 · ownership.nature: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 5

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: Class A1 Common Shares · 420,897 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.

F5 · derivative.exercise_price: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F13 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F5 · derivative.exercise_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F5 · derivative.expiration_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F8 · ownership.nature: Represents conversion of the Issuer's Series C Preferred Shares into Class A1 common shares as per the election of the Adviser at the Series C Conversion Ratio upon the closing of the initial public offering of the Issuer. Class A1 common shares are, subject to a beneficial ownership limitation, convertible at any time at the election of the holder on a 1 for 1 basis into Class A common shares. The Class A1 common shares have no expiration date. Each Class A1 common share automatically converts into one Class A common share upon transfer, except for transfers to or between affiliated holders.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · nonDerivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 2,700,597

F1 · ownership.nature: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds") purchased 299,403 and 2,700,597 Class A common shares of Kiniksa Pharmaceuticals, Ltd. (the "Issuer"), respectively, for $18.00 per share pursuant to the Issuer's initial public offering that closed on May 29, 2018.

F3 · ownership.nature: After giving effect to the transaction reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's Class A common shares reported in column 5 of Table I that are directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · nonDerivative · entry 1

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 299,403

F1 · ownership.nature: 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds") purchased 299,403 and 2,700,597 Class A common shares of Kiniksa Pharmaceuticals, Ltd. (the "Issuer"), respectively, for $18.00 per share pursuant to the Issuer's initial public offering that closed on May 29, 2018.

F2 · ownership.nature: After giving effect to the transaction reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's Class A common shares reported in column 5 of Table I that are directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001140361-18-026543 · doc1.xml · derivative · entry 3

Cormorant Asset Management, LP · CIK 0001583977 · 10% owner

Chen Bihua · CIK 0001599214 · Director · 10% owner

Cormorant Global Healthcare GP, LLC · CIK 0001618451 · 10% owner

Cormorant Global Healthcare Master Fund, LP · CIK 0001618442 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 830,999 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 Shares were convertible at any time, at the holder's election, on a 1-for-2.73235 basis and had no expiration date but converted automatically upon the closing of the Issuer's initial public offering.

F1 · price: The Series C Preferred Shares were convertible at any time, at the holder's election, on a 1-for-2.73235 basis and had no expiration date but converted automatically upon the closing of the Issuer's initial public offering.

F1 · derivative.exercise_date: The Series C Preferred Shares were convertible at any time, at the holder's election, on a 1-for-2.73235 basis and had no expiration date but converted automatically upon the closing of the Issuer's initial public offering.

F1 · derivative.expiration_date: The Series C Preferred Shares were convertible at any time, at the holder's election, on a 1-for-2.73235 basis and had no expiration date but converted automatically upon the closing of the Issuer's initial public offering.

F2 · ownership.direct: Shares reported herein are held by Cormorant Private Healthcare Fund I, LP (the "Fund I"), Cormorant Global Healthcare Master Fund, LP (the "Master Fund") and by a managed account (the "Account"). Cormorant Asset Management, LLC ("Cormorant") serves as the investment manager of Fund I, the Master Fund and the Account. Bihua Chen serves as manager of Cormorant. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the extent of its or her pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any such shares for purposes of Section 16(a) of the Securities Exchange Act of 1934 or for any other purpose.

F3 · ownership.direct: Shares reported herein represent (i) 640,617 Common Shares held by Fund I, (ii) 161,962 Common Shares held by the Master Fund, and (iii) 28,420 Common Shares held by the Account.

SEC source: 0001140361-18-026543 · doc1.xml · nonDerivative · entry 2

Cormorant Asset Management, LP · CIK 0001583977 · 10% owner

Chen Bihua · CIK 0001599214 · Director · 10% owner

Cormorant Global Healthcare GP, LLC · CIK 0001618451 · 10% owner

Cormorant Global Healthcare Master Fund, LP · CIK 0001618442 · 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: 900,443

F2 · ownership.nature: Shares reported herein are held by Cormorant Private Healthcare Fund I, LP (the "Fund I"), Cormorant Global Healthcare Master Fund, LP (the "Master Fund") and by a managed account (the "Account"). Cormorant Asset Management, LLC ("Cormorant") serves as the investment manager of Fund I, the Master Fund and the Account. Bihua Chen serves as manager of Cormorant. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the extent of its or her pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any such shares for purposes of Section 16(a) of the Securities Exchange Act of 1934 or for any other purpose.

F4 · ownership.nature: Shares reported as purchased herein on May 29, 2018 represents (i) 60,291 shares purchased by the Master Fund, and (ii) 9,153 shares purchased by the Account.

SEC source: 0001140361-18-026543 · doc1.xml · nonDerivative · entry 1

Cormorant Asset Management, LP · CIK 0001583977 · 10% owner

Chen Bihua · CIK 0001599214 · Director · 10% owner

Cormorant Global Healthcare GP, LLC · CIK 0001618451 · 10% owner

Cormorant Global Healthcare Master Fund, LP · CIK 0001618442 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 830,999

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 Shares were convertible at any time, at the holder's election, on a 1-for-2.73235 basis and had no expiration date but converted automatically upon the closing of the Issuer's initial public offering.

F2 · ownership.nature: Shares reported herein are held by Cormorant Private Healthcare Fund I, LP (the "Fund I"), Cormorant Global Healthcare Master Fund, LP (the "Master Fund") and by a managed account (the "Account"). Cormorant Asset Management, LLC ("Cormorant") serves as the investment manager of Fund I, the Master Fund and the Account. Bihua Chen serves as manager of Cormorant. Each of the Reporting Persons disclaims beneficial ownership of the shares reported herein except to the extent of its or her pecuniary interest therein, and the filing of this Form 4 shall not be construed as an admission that any of the Reporting Persons is the beneficial owner of any such shares for purposes of Section 16(a) of the Securities Exchange Act of 1934 or for any other purpose.

F3 · ownership.nature: Shares reported herein represent (i) 640,617 Common Shares held by Fund I, (ii) 161,962 Common Shares held by the Master Fund, and (iii) 28,420 Common Shares held by the Account.

SEC source: 0001104659-18-036488 · a4.xml · derivative · entry 3

Patel Sanj K · CIK 0001532218 · Director · Chairman & CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 63,922

Underlying: Class A Common Shares · 63,922 shares

Expires not disclosed

F1 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · price: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · derivative.underlying_shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · balance_after: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

SEC source: 0001104659-18-036487 · a4.xml · derivative · entry 2

Beetham Thomas W. · CIK 0001741382 · Chief Legal Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,392

Underlying: Class A Common Shares · 6,392 shares

Expires not disclosed

F1 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · price: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · derivative.underlying_shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · balance_after: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

SEC source: 0001104659-18-036485 · a4.xml · derivative · entry 2

BOESS CARSTEN · CIK 0001277495 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,392

Underlying: Class A Common Shares · 6,392 shares

Expires not disclosed

F1 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · price: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · derivative.underlying_shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · balance_after: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

SEC source: 0001104659-18-036484 · a4.xml · derivative · entry 3

Mahoney Stephen F. · CIK 0001741389 · President & COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,392

Underlying: Class A Common Shares · 6,392 shares

Expires not disclosed

F1 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · price: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · derivative.underlying_shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · balance_after: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

SEC source: 0001104659-18-036483 · a4.xml · derivative · entry 3

Heberlig Chris · CIK 0001532217 · Exec VP & CFO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,392

Underlying: Class A Common Shares · 6,392 shares

Expires not disclosed

F1 · derivative.exercise_price: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · price: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F1 · derivative.exercise_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F1 · derivative.expiration_date: Upon closing of the Issuer's initial public offering, the preferred shares automatically converted into the Issuer's Class A Common Shares on a one-for-one basis.

F2 · derivative.underlying_shares: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

F2 · balance_after: Reflects the 1-for-2.73235 share consolidation effected May 11, 2018.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 4

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 3,734,103

Underlying: Class A1 Common Shares · 3,734,103 shares

Expires not disclosed

F5 · derivative.exercise_price: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F4 · price: On February 9, 2018, 667 and Life Sciences purchased 420,897 and 3,734,103 Series C Convertible Preferred shares ("Series C Preferred") of the Issuer, adjusted for a 2.73235 for 1 reverse split on May 11, 2018, respectively, for $15.64 per share in a private financing.

F5 · derivative.exercise_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F5 · derivative.expiration_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F4 · ownership.nature: On February 9, 2018, 667 and Life Sciences purchased 420,897 and 3,734,103 Series C Convertible Preferred shares ("Series C Preferred") of the Issuer, adjusted for a 2.73235 for 1 reverse split on May 11, 2018, respectively, for $15.64 per share in a private financing.

F7 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's securities reported in column 9 of Table II directly held by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000584 · doc4_5431.xml · derivative · entry 3

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 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: 420,897

Underlying: Class A1 Common Shares · 420,897 shares

Expires not disclosed

F5 · derivative.exercise_price: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F4 · price: On February 9, 2018, 667 and Life Sciences purchased 420,897 and 3,734,103 Series C Convertible Preferred shares ("Series C Preferred") of the Issuer, adjusted for a 2.73235 for 1 reverse split on May 11, 2018, respectively, for $15.64 per share in a private financing.

F5 · derivative.exercise_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F5 · derivative.expiration_date: Series C Preferred will convert on a 1 for 1 basis (the "Series C Conversion Ratio") into Class A1 common shares of the Issuer as per the election of Baker Bros. Advisors LP (the "Adviser") at any time and automatically convert at the Series C Conversion Ratio upon the closing of the Issuer's initial public offering. The Series C Preferred have no expiration date.

F4 · ownership.nature: On February 9, 2018, 667 and Life Sciences purchased 420,897 and 3,734,103 Series C Convertible Preferred shares ("Series C Preferred") of the Issuer, adjusted for a 2.73235 for 1 reverse split on May 11, 2018, respectively, for $15.64 per share in a private financing.

F6 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in securities reported in column 9 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F14 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F15 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.