14159, L.P.

SEC source: 0001638599-19-000909 · doc4_6320.xml · nonDerivative · entry 5

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

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · 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: 7,642,042

F1 · ownership.nature: 185 shares of restricted stock (the "Restricted Stock") of Genomic Health, Inc. (the "Issuer") issued to Felix J. Baker and 185 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F2 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F3 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F8 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I 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 their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F9 · 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 managing members 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.

F10 · 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.

F11 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 370 shares. The 370 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F12 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 17,071 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares of Common Stock which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000909 · doc4_6320.xml · nonDerivative · entry 4

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

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · 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: 1,217,279

F1 · ownership.nature: 185 shares of restricted stock (the "Restricted Stock") of Genomic Health, Inc. (the "Issuer") issued to Felix J. Baker and 185 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F2 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F3 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I 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 their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F9 · 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 managing members 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.

F10 · 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.

F11 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 370 shares. The 370 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F12 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 17,071 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares of Common Stock which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000909 · doc4_6320.xml · nonDerivative · entry 3

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

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · 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: 244,595

F1 · ownership.nature: 185 shares of restricted stock (the "Restricted Stock") of Genomic Health, Inc. (the "Issuer") issued to Felix J. Baker and 185 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F2 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F3 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F9 · 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 managing members 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.

F10 · 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.

F11 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 370 shares. The 370 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F13 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 17,071 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000909 · doc4_6320.xml · nonDerivative · entry 2

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

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · 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: 160,223

F1 · ownership.nature: 185 shares of restricted stock (the "Restricted Stock") of Genomic Health, Inc. (the "Issuer") issued to Felix J. Baker and 185 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F2 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F3 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by Baker Bros. Investments, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Bros. Investments.

F9 · 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 managing members 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.

F10 · 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.

F11 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 370 shares. The 370 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F13 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 17,071 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000909 · doc4_6320.xml · nonDerivative · entry 1

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

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · 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: 165,980

F1 · ownership.nature: 185 shares of restricted stock (the "Restricted Stock") of Genomic Health, Inc. (the "Issuer") issued to Felix J. Baker and 185 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F2 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F3 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F4 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker/Tisch Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in common stock of the Issuer ("Common Stock") reported in column 5 of Table I directly held by Baker Tisch, a limited partnership of which the sole general partner is Baker/Tisch Capital, L.P., a limited partnership of which the sole general partner is Baker/Tisch Capital (GP), LLC, due to Baker/Tisch Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Tisch.

F9 · 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 managing members 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.

F10 · 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.

F11 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 370 shares. The 370 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F13 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 17,071 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000821 · doc4_6276.xml · nonDerivative · entry 10

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: Direct

Disclosed balance after: 0

F16 · balance_after: Represents shares of Common Stock donated by Felix J. Baker.

SEC source: 0001638599-19-000821 · doc4_6276.xml · nonDerivative · entry 9

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: Direct

Disclosed balance after: 0

F15 · balance_after: Represents shares of Common Stock donated by Julian C. Baker.

SEC source: 0001638599-19-000821 · doc4_6276.xml · nonDerivative · entry 8

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: Direct

Disclosed balance after: 95,289

F14 · balance_after: Common Stock held directly by Felix J. Baker, including 8,341 shares of Common Stock received from the in-kind pro rata distributions without consideration reported above as well as 86,948 shares of Common Stock formerly held indirectly through FBB Associates.

SEC source: 0001638599-19-000821 · doc4_6276.xml · nonDerivative · entry 7

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: Direct

Disclosed balance after: 95,289

F13 · balance_after: Common Stock held directly by Julian C. Baker, including 8,340 shares of Common Stock received from the in-kind pro rata distributions without consideration reported above as well as 86,949 shares of Common Stock formerly held indirectly through FBB Associates.

SEC source: 0001638599-19-000821 · doc4_6276.xml · nonDerivative · entry 6

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 43,361

F12 · kind: Represents shares of Common Stock distributed by Bros. II as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker and Felix J. Baker. Julian C. Baker received 4,433 shares of Common Stock and Felix J. Baker received 4,433 shares of Common Stock.

F12 · price: Represents shares of Common Stock distributed by Bros. II as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker and Felix J. Baker. Julian C. Baker received 4,433 shares of Common Stock and Felix J. Baker received 4,433 shares of Common Stock.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by Baker Bros. Investments II, L.P. ("Bros. II" and together with Bros. I, 14159, 667, Life Sciences, and Baker/Tisch, the "Funds"), a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros. II.

F7 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F8 · 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.

F10 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000821 · doc4_6276.xml · nonDerivative · entry 5

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 165,610

F11 · kind: Represents shares of Common Stock distributed by Baker/Tisch as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker and Felix J. Baker. Julian C. Baker received 3,907 shares of Common Stock and Felix J. Baker received 3,908 shares of Common Stock.

F11 · price: Represents shares of Common Stock distributed by Baker/Tisch as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker and Felix J. Baker. Julian C. Baker received 3,907 shares of Common Stock and Felix J. Baker received 3,908 shares of Common Stock.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker/Tisch Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by Baker/Tisch Investments, L.P. ("Baker/Tisch"), a limited partnership of which the sole general partner is Baker/Tisch Capital, L.P., a limited partnership of which the sole general partner is Baker/Tisch Capital (GP), LLC, due to Baker/Tisch Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker/Tisch.

F7 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F8 · 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.

F10 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000643 · doc4_6171.xml · nonDerivative · entry 7

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 7,641,672

F2 · ownership.nature: 212 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 212 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F3 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F4 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), Baker Bros. Investments II, L.P. ("Baker Bros. Investments II"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, Baker Bros. Investments II, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F10 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I 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.

F11 · 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 managing members 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.

F12 · 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.

F13 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 424 shares. The 424 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F14 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares of Common Stock which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000643 · doc4_6171.xml · nonDerivative · entry 6

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 1,216,909

F2 · ownership.nature: 212 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 212 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F3 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F4 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), Baker Bros. Investments II, L.P. ("Baker Bros. Investments II"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, Baker Bros. Investments II, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F9 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I 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.

F11 · 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 managing members 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.

F12 · 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.

F13 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 424 shares. The 424 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F14 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares of Common Stock which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000643 · doc4_6171.xml · nonDerivative · entry 5

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 244,225

F2 · ownership.nature: 212 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 212 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F3 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F4 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), Baker Bros. Investments II, L.P. ("Baker Bros. Investments II"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, Baker Bros. Investments II, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F8 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F11 · 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 managing members 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.

F12 · 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.

F13 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 424 shares. The 424 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F15 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000643 · doc4_6171.xml · nonDerivative · entry 4

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 159,853

F2 · ownership.nature: 212 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 212 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F3 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F4 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), Baker Bros. Investments II, L.P. ("Baker Bros. Investments II"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, Baker Bros. Investments II, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by Baker Bros. Investments, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Bros. Investments.

F11 · 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 managing members 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.

F12 · 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.

F13 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 424 shares. The 424 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F15 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000643 · doc4_6171.xml · nonDerivative · entry 3

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 52,227

F2 · ownership.nature: 212 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 212 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F3 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F4 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), Baker Bros. Investments II, L.P. ("Baker Bros. Investments II"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, Baker Bros. Investments II, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by Baker Bros. Investments II, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Bros. Investments II.

F11 · 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 managing members 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.

F12 · 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.

F13 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 424 shares. The 424 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F15 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000643 · doc4_6171.xml · nonDerivative · entry 2

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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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: 173,425

F2 · ownership.nature: 212 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 212 shares of Restricted Stock issued to Julian C. Baker pursuant to the Issuer's 2005 Stock Incentive Plan, as amended (the "Stock Incentive Plan") in lieu of director retainer fees of $12,500, respectively. The shares of Restricted Stock are fully vested. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors as representatives of the Funds (as defined below).

F3 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds (as defined below) are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees.

F4 · ownership.nature: Baker/Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments, L.P. ("Baker Bros. Investments"), Baker Bros. Investments II, L.P. ("Baker Bros. Investments II"), 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with Baker Tisch, Baker Bros. Investments, Baker Bros. Investments II, 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Restricted Stock.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker/Tisch Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by Baker Tisch, a limited partnership of which the sole general partner is Baker/Tisch Capital, L.P., a limited partnership of which the sole general partner is Baker/Tisch Capital (GP), LLC, due to Baker/Tisch Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Tisch.

F11 · 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 managing members 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.

F12 · 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.

F13 · ownership.nature: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 424 shares. The 424 shares are reported for each of the Funds as each has an indirect pecuniary interest.

F15 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,701 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

SEC source: 0001638599-19-000616 · doc4_6156.xml · derivative · entry 8

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 13,166

Underlying: Common Stock · 13,166 shares

Expires 2029-06-14

F13 · derivative.exercise_date: 6,583 Stock Options were granted to each of Felix J. Baker and Julian C. Baker pursuant to the Stock Incentive Plan. The Stock Options have a strike price of $52.41 and fully vest on the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders, if earlier. Felix J. Baker and Julian C. Baker serve on the Board as representatives of the Funds. Pursuant to the policies of the Adviser, Felix J. Baker and Julian C. Baker do not have any right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all of the pecuniary interest in the securities issued.

F3 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker/Tisch Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I and non-qualified stock options ("Stock Options") exercisable solely into Common Stock reported in Table II directly held by Baker/Tisch Investments, L.P. ("Baker Tisch"), a limited partnership of which the sole general partner is Baker/Tisch Capital, L.P., a limited partnership of which the sole general partner is Baker/Tisch Capital (GP), LLC, due to Baker/Tisch Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Tisch.

F4 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in Table II directly held by Baker Bros. Investments II, L.P. ("Bros II"), a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros II.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital, LP, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in Table II, directly held by Baker Bros. Investments, L.P. ("Bros I"), a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros I.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in Table II, directly held by 14159, L.P. ("14159"), a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital's, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667"), Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in 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: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with Baker Tisch, Bros I, Bros II, 14159 and 667, the "Funds"), Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in 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: 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 managing members 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.

F11 · 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.

F13 · ownership.nature: 6,583 Stock Options were granted to each of Felix J. Baker and Julian C. Baker pursuant to the Stock Incentive Plan. The Stock Options have a strike price of $52.41 and fully vest on the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders, if earlier. Felix J. Baker and Julian C. Baker serve on the Board as representatives of the Funds. Pursuant to the policies of the Adviser, Felix J. Baker and Julian C. Baker do not have any right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all of the pecuniary interest in the securities issued.

SEC source: 0001638599-19-000616 · doc4_6156.xml · nonDerivative · entry 7

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 7,641,248

F2 · ownership.nature: 955 Restricted Stock Units (each, an "RSU") of the Issuer payable solely in Common Stock granted to each of Felix J. Baker and Julian C. Baker on June 14, 2019, pursuant to the Issuer's Amended and Restated 2005 Stock Incentive Plan ("Stock Incentive Plan"). The RSUs fully vest on the earlier of the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors (the "Board") as representatives of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have a right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the RSUs.

F8 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with Baker Tisch, Bros I, Bros II, 14159 and 667, the "Funds"), Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in 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.

F9 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,277 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares of Common Stock which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

F10 · 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 managing members 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.

F11 · 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.

F14 · ownership.nature: The disclosure of the grant of RSUs reported on this form is a single grant of 955 shares to each of Felix J. Baker and Julian C. Baker. The 1,910 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-19-000616 · doc4_6156.xml · nonDerivative · entry 6

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 1,216,485

F2 · ownership.nature: 955 Restricted Stock Units (each, an "RSU") of the Issuer payable solely in Common Stock granted to each of Felix J. Baker and Julian C. Baker on June 14, 2019, pursuant to the Issuer's Amended and Restated 2005 Stock Incentive Plan ("Stock Incentive Plan"). The RSUs fully vest on the earlier of the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors (the "Board") as representatives of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have a right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the RSUs.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667"), Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in 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.

F9 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,277 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares of Common Stock which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

F10 · 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 managing members 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.

F11 · 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.

F14 · ownership.nature: The disclosure of the grant of RSUs reported on this form is a single grant of 955 shares to each of Felix J. Baker and Julian C. Baker. The 1,910 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-19-000616 · doc4_6156.xml · nonDerivative · entry 5

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 243,801

F2 · ownership.nature: 955 Restricted Stock Units (each, an "RSU") of the Issuer payable solely in Common Stock granted to each of Felix J. Baker and Julian C. Baker on June 14, 2019, pursuant to the Issuer's Amended and Restated 2005 Stock Incentive Plan ("Stock Incentive Plan"). The RSUs fully vest on the earlier of the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors (the "Board") as representatives of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have a right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the RSUs.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in Table II, directly held by 14159, L.P. ("14159"), a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital's, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F10 · 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 managing members 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.

F11 · 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.

F12 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,277 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares of Common Stock which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

F14 · ownership.nature: The disclosure of the grant of RSUs reported on this form is a single grant of 955 shares to each of Felix J. Baker and Julian C. Baker. The 1,910 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-19-000616 · doc4_6156.xml · nonDerivative · entry 4

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 159,429

F2 · ownership.nature: 955 Restricted Stock Units (each, an "RSU") of the Issuer payable solely in Common Stock granted to each of Felix J. Baker and Julian C. Baker on June 14, 2019, pursuant to the Issuer's Amended and Restated 2005 Stock Incentive Plan ("Stock Incentive Plan"). The RSUs fully vest on the earlier of the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors (the "Board") as representatives of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have a right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the RSUs.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital, LP, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in Table II, directly held by Baker Bros. Investments, L.P. ("Bros I"), a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros I.

F10 · 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 managing members 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.

F11 · 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.

F12 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,277 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares of Common Stock which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

F14 · ownership.nature: The disclosure of the grant of RSUs reported on this form is a single grant of 955 shares to each of Felix J. Baker and Julian C. Baker. The 1,910 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-19-000616 · doc4_6156.xml · nonDerivative · entry 3

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 51,803

F2 · ownership.nature: 955 Restricted Stock Units (each, an "RSU") of the Issuer payable solely in Common Stock granted to each of Felix J. Baker and Julian C. Baker on June 14, 2019, pursuant to the Issuer's Amended and Restated 2005 Stock Incentive Plan ("Stock Incentive Plan"). The RSUs fully vest on the earlier of the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors (the "Board") as representatives of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have a right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the RSUs.

F4 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I and the Stock Options reported in Table II directly held by Baker Bros. Investments II, L.P. ("Bros II"), a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros II.

F10 · 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 managing members 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.

F11 · 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.

F12 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,277 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares of Common Stock which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

F14 · ownership.nature: The disclosure of the grant of RSUs reported on this form is a single grant of 955 shares to each of Felix J. Baker and Julian C. Baker. The 1,910 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-19-000616 · doc4_6156.xml · nonDerivative · entry 2

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

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · Director · 10% owner

Baker Bros. Investments, L.P. · CIK 0001551136 · 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: 173,001

F2 · ownership.nature: 955 Restricted Stock Units (each, an "RSU") of the Issuer payable solely in Common Stock granted to each of Felix J. Baker and Julian C. Baker on June 14, 2019, pursuant to the Issuer's Amended and Restated 2005 Stock Incentive Plan ("Stock Incentive Plan"). The RSUs fully vest on the earlier of the first anniversary of the date of grant or immediately prior to the Issuer's next annual meeting of stockholders. Felix J. Baker and Julian C. Baker serve on the Issuer's board of directors (the "Board") as representatives of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Felix J. Baker and Julian C. Baker do not have a right to any of the Issuer's securities issued as part of their service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the RSUs.

F3 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker/Tisch Capital, L.P., Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I and non-qualified stock options ("Stock Options") exercisable solely into Common Stock reported in Table II directly held by Baker/Tisch Investments, L.P. ("Baker Tisch"), a limited partnership of which the sole general partner is Baker/Tisch Capital, L.P., a limited partnership of which the sole general partner is Baker/Tisch Capital (GP), LLC, due to Baker/Tisch Capital, L.P.'s right to receive an allocation of a portion of the profits from Baker Tisch.

F10 · 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 managing members 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.

F11 · 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.

F12 · ownership.nature: Includes beneficial ownership of 1,910 RSUs, 16,277 shares of Common Stock issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares of Common Stock which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the Funds may be deemed to own a portion.

F14 · ownership.nature: The disclosure of the grant of RSUs reported on this form is a single grant of 955 shares to each of Felix J. Baker and Julian C. Baker. The 1,910 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-19-000602 · doc4_6150.xml · nonDerivative · entry 6

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

14159, L.P. · CIK 0001551138 · 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: Direct

Disclosed balance after: 281,190

F9 · balance_after: Common Stock held directly by Julian C. Baker including 220,141 shares of Common Stock received from the in-kind pro rata distributions without consideration reported above.

SEC source: 0001638599-19-000602 · doc4_6150.xml · nonDerivative · entry 5

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

14159, L.P. · CIK 0001551138 · 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: Direct

Disclosed balance after: 278,773

F8 · balance_after: Common Stock held directly by Felix J. Baker including 220,141 shares of Common Stock received from the in-kind pro rata distributions without consideration reported above.

SEC source: 0001638599-19-000602 · doc4_6150.xml · nonDerivative · entry 4

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

14159, L.P. · CIK 0001551138 · 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

F4 · kind: Represents shares of Common Stock distributed by 14159, L.P. ("14159", and together with Life Sciences and 667, the "Funds") as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker, Felix J. Baker and other investors in 14159.

F4 · price: Represents shares of Common Stock distributed by 14159, L.P. ("14159", and together with Life Sciences and 667, the "Funds") as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker, Felix J. Baker and other investors in 14159.

F6 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) 14159 Capital, L.P. and (ii) 14159, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP),LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159. Due to the fact that 14159 has fully distributed all of the Issuer's securities it no longer has the right to the pecuniary interest in the securities issued pursuant to the Stock Incentive Plan for securities received.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000602 · doc4_6150.xml · nonDerivative · entry 3

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

14159, L.P. · CIK 0001551138 · 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: 2,826,766

F3 · kind: Represents shares of Common Stock distributed by 667, L.P. ("667") as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker, Felix J. Baker and other investors in 667.

F3 · price: Represents shares of Common Stock distributed by 667, L.P. ("667") as part of an in-kind pro rata distribution without consideration in accordance with pecuniary interest to Julian C. Baker, Felix J. Baker and other investors in 667.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I 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.

F7 · ownership.nature: Includes beneficial ownership of 3,376 shares previously issued pursuant to the Stock Incentive Plan in lieu of director retainer fees, 135,000 shares received previously from exercise of 135,000 stock options of the Issuer and 1,520 restricted stock units payable solely in Common Stock that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000433 · doc4_6073.xml · derivative · entry 9

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

14159, L.P. · CIK 0001551138 · 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: 12,472

Underlying: Common Stock · 12,472 shares

Expires 2029-04-25

F13 · derivative.exercise_date: Non-qualified stock options ("Stock Options") convertible solely into Common Shares granted to Julian C. Baker on April 26, 2019, pursuant to the Incentive Plan. The Stock Options with a strike price of $75.03 vest on the earlier of April 26, 2020, the date of the next annual shareholder meeting of the Issuer or upon a change of control as defined in the Incentive Plan.

F11 · 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 managing members 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.

F12 · 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.

F14 · ownership.nature: Julian C. Baker serves on the Board as a representative of the Funds. Pursuant to the policies of the Adviser, Julian C. Baker does not have a right to any of the Issuer's securities issued as part of his service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the Stock Options. Solely as a result of Felix J. Baker's and Julian C. Baker's ownership interest in the general partners of the general partners of the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Stock Options (i.e. no direct pecuniary interest).

F17 · ownership.nature: As a result of their ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 12,472 Stock Options beneficially owned by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is Baker 14159 Capital (GP), LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159.

SEC source: 0001638599-19-000433 · doc4_6073.xml · derivative · entry 8

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

14159, L.P. · CIK 0001551138 · 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: 12,472

Underlying: Common Stock · 12,472 shares

Expires 2029-04-25

F13 · derivative.exercise_date: Non-qualified stock options ("Stock Options") convertible solely into Common Shares granted to Julian C. Baker on April 26, 2019, pursuant to the Incentive Plan. The Stock Options with a strike price of $75.03 vest on the earlier of April 26, 2020, the date of the next annual shareholder meeting of the Issuer or upon a change of control as defined in the Incentive Plan.

F11 · 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 managing members 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.

F12 · 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.

F14 · ownership.nature: Julian C. Baker serves on the Board as a representative of the Funds. Pursuant to the policies of the Adviser, Julian C. Baker does not have a right to any of the Issuer's securities issued as part of his service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the Stock Options. Solely as a result of Felix J. Baker's and Julian C. Baker's ownership interest in the general partners of the general partners of the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Stock Options (i.e. no direct pecuniary interest).

F16 · ownership.nature: As a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 12,472 Stock Options beneficially owned 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.

SEC source: 0001638599-19-000433 · doc4_6073.xml · derivative · entry 7

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

14159, L.P. · CIK 0001551138 · 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: 12,472

Underlying: Common Stock · 12,472 shares

Expires 2029-04-25

F13 · derivative.exercise_date: Non-qualified stock options ("Stock Options") convertible solely into Common Shares granted to Julian C. Baker on April 26, 2019, pursuant to the Incentive Plan. The Stock Options with a strike price of $75.03 vest on the earlier of April 26, 2020, the date of the next annual shareholder meeting of the Issuer or upon a change of control as defined in the Incentive Plan.

F11 · 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 managing members 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.

F12 · 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.

F14 · ownership.nature: Julian C. Baker serves on the Board as a representative of the Funds. Pursuant to the policies of the Adviser, Julian C. Baker does not have a right to any of the Issuer's securities issued as part of his service on the Board and the Funds are entitled to receive all the pecuniary interest in the securities issued. The Funds each own an indirect proportionate pecuniary interest in the Stock Options. Solely as a result of Felix J. Baker's and Julian C. Baker's ownership interest in the general partners of the general partners of the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Stock Options (i.e. no direct pecuniary interest).

F15 · ownership.nature: As a result of their ownership interest in Baker Biotech Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 12,472 Stock Options beneficially owned 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.

SEC source: 0001638599-19-000433 · doc4_6073.xml · nonDerivative · entry 6

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

14159, L.P. · CIK 0001551138 · 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: 812,602

F4 · ownership.nature: Restricted Stock Units (the "Restricted Stock Units") payable solely in Common Shares granted to Julian C. Baker on April 26, 2019, pursuant to the Amended and Restated 2010 Stock Incentive Plan ("Incentive Plan"). The Restricted Stock Units fully vest on the earlier of April 26, 2020, the date of the next annual shareholder meeting of the Issuer or upon a change in control as defined in the Incentive Plan.

F5 · ownership.nature: Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does not have a right to any of the Issuer's securities issued as part of his service on the Board and the Funds (as defined below) are entitled to receive all the pecuniary interest in the securities issued. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159")(collectively the "Funds") each owns an indirect proportionate pecuniary interest in the Restricted Stock Units. Solely as a result of Julian C. Baker's and Felix J. Baker's ownership interest in the general partners of the general partners of the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Restricted Stock Units.

F8 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 812,602 shares of common stock of the Issuer beneficially owned by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F10 · ownership.nature: The disclosure of the grant of Restricted Stock Units and Stock Options (as defined below) reported on this form is a single grant of 1,520 Restricted Stock Units and 12,472 Stock Options. The 1,520 Restricted Stock Units and 12,472 Stock Options (as defined below) are reported for each of the Funds as each has an indirect pecuniary interest.

F11 · 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 managing members 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.

F12 · 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.

F18 · ownership.nature: Includes beneficial ownership of 3,376 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 115,000 shares received previously from exercise of 115,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000433 · doc4_6073.xml · nonDerivative · entry 5

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

14159, L.P. · CIK 0001551138 · 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: 29,290,533

F4 · ownership.nature: Restricted Stock Units (the "Restricted Stock Units") payable solely in Common Shares granted to Julian C. Baker on April 26, 2019, pursuant to the Amended and Restated 2010 Stock Incentive Plan ("Incentive Plan"). The Restricted Stock Units fully vest on the earlier of April 26, 2020, the date of the next annual shareholder meeting of the Issuer or upon a change in control as defined in the Incentive Plan.

F5 · ownership.nature: Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does not have a right to any of the Issuer's securities issued as part of his service on the Board and the Funds (as defined below) are entitled to receive all the pecuniary interest in the securities issued. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159")(collectively the "Funds") each owns an indirect proportionate pecuniary interest in the Restricted Stock Units. Solely as a result of Julian C. Baker's and Felix J. Baker's ownership interest in the general partners of the general partners of the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Restricted Stock Units.

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, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 29,290,533 shares of common stock of the Issuer beneficially owned 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.

F9 · ownership.nature: Includes beneficial ownership of 3,376 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 135,000 shares received previously from exercise of 135,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: The disclosure of the grant of Restricted Stock Units and Stock Options (as defined below) reported on this form is a single grant of 1,520 Restricted Stock Units and 12,472 Stock Options. The 1,520 Restricted Stock Units and 12,472 Stock Options (as defined below) are reported for each of the Funds as each has an indirect pecuniary interest.

F11 · 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 managing members 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.

F12 · 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: 0001638599-19-000433 · doc4_6073.xml · nonDerivative · entry 4

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

14159, L.P. · CIK 0001551138 · 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: 4,430,004

F4 · ownership.nature: Restricted Stock Units (the "Restricted Stock Units") payable solely in Common Shares granted to Julian C. Baker on April 26, 2019, pursuant to the Amended and Restated 2010 Stock Incentive Plan ("Incentive Plan"). The Restricted Stock Units fully vest on the earlier of April 26, 2020, the date of the next annual shareholder meeting of the Issuer or upon a change in control as defined in the Incentive Plan.

F5 · ownership.nature: Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below). Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does not have a right to any of the Issuer's securities issued as part of his service on the Board and the Funds (as defined below) are entitled to receive all the pecuniary interest in the securities issued. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159")(collectively the "Funds") each owns an indirect proportionate pecuniary interest in the Restricted Stock Units. Solely as a result of Julian C. Baker's and Felix J. Baker's ownership interest in the general partners of the general partners of the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Restricted Stock Units.

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, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 4,430,004 shares of common stock of the Issuer beneficially owned 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.

F9 · ownership.nature: Includes beneficial ownership of 3,376 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 135,000 shares received previously from exercise of 135,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: The disclosure of the grant of Restricted Stock Units and Stock Options (as defined below) reported on this form is a single grant of 1,520 Restricted Stock Units and 12,472 Stock Options. The 1,520 Restricted Stock Units and 12,472 Stock Options (as defined below) are reported for each of the Funds as each has an indirect pecuniary interest.

F11 · 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 managing members 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.

F12 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 25

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 7,648,570

F15 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $66.63 to $67.44, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F8 · 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, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Life Sciences, and together with Baker Tisch, Bros I, Bros II, 14159 and 667, (the "Funds"), 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: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.

F14 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 24

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 1,215,992

F15 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $66.63 to $67.44, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I 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: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.

F14 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 23

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 242,135

F15 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $66.63 to $67.44, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital's, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 22

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 157,661

F15 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $66.63 to $67.44, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Bros I, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros I.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 21

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 49,904

F15 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $66.63 to $67.44, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F4 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Bros II, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros II.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 20

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 171,249

F15 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $66.63 to $67.44, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

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

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 19

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 7,712,345

F13 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $64.60 to $65.15, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F8 · 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, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Life Sciences, and together with Baker Tisch, Bros I, Bros II, 14159 and 667, (the "Funds"), 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: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.

F14 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 18

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 1,225,783

F13 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $64.60 to $65.15, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I 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: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.

F14 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 17

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 243,823

F13 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $64.60 to $65.15, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital's, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 16

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 158,640

F13 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $64.60 to $65.15, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Bros I, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros I.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 15

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 49,978

F13 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $64.60 to $65.15, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F4 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Bros II, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros II.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000429 · doc4_6063.xml · nonDerivative · entry 14

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 172,342

F13 · price: The price reported in Column 4 is a weighted average price. These shares were traded by the Funds in multiple transactions at prices ranging from $64.60 to $65.15, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff, upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

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

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000430 · doc4_6064.xml · nonDerivative · entry 7

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 7,639,338

F2 · price: The price reported in Column 4 is a weighted average price. These shares were traded by Baker/ Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments II, L.P. ("Bros II"), Baker Bros. Investments, L.P. ("Bros I"), 14159, L.P. ("14159"), 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences") in multiple transactions at prices ranging from $65.15 to $66.15, 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 (the "Staff"), upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F8 · 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, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Life Sciences, and together with Baker Tisch, Bros I, Bros II, 14159 and 667, (the "Funds"), 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: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.

F12 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000430 · doc4_6064.xml · nonDerivative · entry 6

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 1,214,575

F2 · price: The price reported in Column 4 is a weighted average price. These shares were traded by Baker/ Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments II, L.P. ("Bros II"), Baker Bros. Investments, L.P. ("Bros I"), 14159, L.P. ("14159"), 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences") in multiple transactions at prices ranging from $65.15 to $66.15, 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 (the "Staff"), upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F7 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I 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: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.

F12 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 33,000 shares which were received from exercise of 33,000 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

SEC source: 0001638599-19-000430 · doc4_6064.xml · nonDerivative · entry 5

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 241,891

F2 · price: The price reported in Column 4 is a weighted average price. These shares were traded by Baker/ Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments II, L.P. ("Bros II"), Baker Bros. Investments, L.P. ("Bros I"), 14159, L.P. ("14159"), 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences") in multiple transactions at prices ranging from $65.15 to $66.15, 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 (the "Staff"), upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F6 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital's, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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: 0001638599-19-000430 · doc4_6064.xml · nonDerivative · entry 4

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

Baker Bros. Investments, L.P. · CIK 0001551136 · Director · 10% owner

Baker/Tisch Investments, LP · CIK 0001551137 · Director · 10% owner

14159, L.P. · CIK 0001551138 · 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

Baker Bros. Investments II, L.P. · CIK 0001551132 · 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: 157,519

F2 · price: The price reported in Column 4 is a weighted average price. These shares were traded by Baker/ Tisch Investments, L.P. ("Baker Tisch"), Baker Bros. Investments II, L.P. ("Bros II"), Baker Bros. Investments, L.P. ("Bros I"), 14159, L.P. ("14159"), 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences") in multiple transactions at prices ranging from $65.15 to $66.15, 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 (the "Staff"), upon request, full information regarding the number of shares traded at each separate price within the range set forth in this footnote.

F5 · ownership.nature: After giving effect to the transactions reported herein and as a result of their ownership interest in Baker Bros. Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in column 5 of Table I directly held by Bros I, a limited partnership of which the sole general partner is Baker Bros. Capital, L.P., a limited partnership of which the sole general partner is Baker Bros. Capital (GP), LLC, due to Baker Bros. Capital, L.P.'s right to receive an allocation of a portion of the profits from Bros I.

F9 · ownership.nature: Includes beneficial ownership of 16,277 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares which were received from exercise of 24,750 stock options of the Issuer that were issued to Julian C. Baker in his capacity as a director of the Issuer, of which the fund may be deemed to own a portion.

F10 · ownership.nature: Baker Bros. Advisors LP (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 managing members 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.

F11 · 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.