14159, L.P.

SEC source: 0001638599-18-000401 · doc4_5350.xml · nonDerivative · entry 2

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

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 34,206,600

F1 · ownership.nature: 5,401 shares of common stock (the "Common Stock") issued to Julian C. Baker and 7,948 shares of Common Stock issued to Dr. Kelvin M. Neu, respectively, a principal and a full-time employee of Baker Bros. Advisors LP (the "Adviser") pursuant to the Issuer's 2013 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $8,750 and $12,875, respectively. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds (as defined below). Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F2 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F4 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 34,206,600 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. Includes beneficial ownership of 142,075 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees, of which the fund may be deemed to own a portion.

F6 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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.

F7 · ownership.nature: The disclosure of the grant of Common Stock reported on this form is the sum of two grants totaling 13,349 shares. The 13,349 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000401 · doc4_5350.xml · nonDerivative · entry 1

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

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 4,116,145

F1 · ownership.nature: 5,401 shares of common stock (the "Common Stock") issued to Julian C. Baker and 7,948 shares of Common Stock issued to Dr. Kelvin M. Neu, respectively, a principal and a full-time employee of Baker Bros. Advisors LP (the "Adviser") pursuant to the Issuer's 2013 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $8,750 and $12,875, respectively. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds (as defined below). Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F2 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F3 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 4,116,145 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. Includes beneficial ownership of 142,075 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees of which the fund may be deemed to own a portion.

F6 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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.

F7 · ownership.nature: The disclosure of the grant of Common Stock reported on this form is the sum of two grants totaling 13,349 shares. The 13,349 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000399 · doc4_5349.xml · nonDerivative · entry 7

BAKER BROS. ADVISORS LP · CIK 0001263508 · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 339,585

F2 · ownership.nature: 319 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 319 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F10 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 339,585 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. Includes beneficial ownership of 14,989 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 638 shares. The 638 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000399 · doc4_5349.xml · nonDerivative · entry 6

BAKER BROS. ADVISORS LP · CIK 0001263508 · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 11,369,920

F2 · ownership.nature: 319 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 319 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F9 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 11,369,920 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. Includes beneficial ownership of 14,989 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 638 shares. The 638 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000399 · doc4_5349.xml · nonDerivative · entry 5

BAKER BROS. ADVISORS LP · CIK 0001263508 · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 1,779,251

F2 · ownership.nature: 319 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 319 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F8 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 1,779,251 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. Includes beneficial ownership of 14,989 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 638 shares. The 638 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000399 · doc4_5349.xml · nonDerivative · entry 4

BAKER BROS. ADVISORS LP · CIK 0001263508 · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 52,977

F2 · ownership.nature: 319 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 319 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F7 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 52,977 shares of Common Stock of the Issuer beneficially owned 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. Includes beneficial ownership of 14,989 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 638 shares. The 638 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000399 · doc4_5349.xml · nonDerivative · entry 3

BAKER BROS. ADVISORS LP · CIK 0001263508 · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 213,636

F2 · ownership.nature: 319 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 319 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F6 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 213,636 shares of Common Stock of the Issuer beneficially owned 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. Includes beneficial ownership of 14,989 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 638 shares. The 638 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000399 · doc4_5349.xml · nonDerivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 233,900

F2 · ownership.nature: 319 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 319 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F5 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 233,900 shares of Common Stock of the Issuer beneficially owned 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. Includes beneficial ownership of 14,989 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 638 shares. The 638 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000388 · doc4_5343.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: 790,006

F4 · ownership.nature: 228 shares of common stock (the "Common Stock") issued to Julian C. Baker pursuant to the Issuer's Amended and Restated 2010 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $19,000. The shares of Common Stock are fully vested. Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below).

F5 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F8 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 790,006 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. Includes beneficial ownership of 2,300 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 95,000 shares received previously from exercise of 95,000 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The 228 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000388 · doc4_5343.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: 29,247,937

F4 · ownership.nature: 228 shares of common stock (the "Common Stock") issued to Julian C. Baker pursuant to the Issuer's Amended and Restated 2010 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $19,000. The shares of Common Stock are fully vested. Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below).

F5 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F7 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 29,247,937 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. Includes beneficial ownership of 2,300 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 95,000 shares received previously from exercise of 95,000 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The 228 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000388 · doc4_5343.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: 4,387,408

F4 · ownership.nature: 228 shares of common stock (the "Common Stock") issued to Julian C. Baker pursuant to the Issuer's Amended and Restated 2010 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $19,000. The shares of Common Stock are fully vested. Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below).

F5 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F6 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 4,387,408 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. Includes beneficial ownership of 2,300 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 95,000 shares received previously from exercise of 95,000 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The 228 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000337 · doc4_5319.xml · derivative · 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: 0

Underlying: Common Stock · 439,036 shares

Expires 2018-05-07

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

F8 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F1 · ownership.nature: On March 15, 2018, 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667 and Life Sciences the "Funds") exercised a warrant to purchase 2,250,846, 17,626,445 and 439,036 shares of the common stock of Idera Pharmaceuticals, Inc. (the "Issuer") for $0.47 per share ("2018 Warrants").

F4 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in 14159 Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F7 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000337 · doc4_5319.xml · derivative · 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: 0

Underlying: Common Stock · 17,626,445 shares

Expires 2018-05-07

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

F8 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F1 · ownership.nature: On March 15, 2018, 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667 and Life Sciences the "Funds") exercised a warrant to purchase 2,250,846, 17,626,445 and 439,036 shares of the common stock of Idera Pharmaceuticals, Inc. (the "Issuer") for $0.47 per share ("2018 Warrants").

F3 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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, 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.

F7 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000337 · doc4_5319.xml · derivative · 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

Underlying: Common Stock · 2,250,846 shares

Expires 2018-05-07

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

F8 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F1 · ownership.nature: On March 15, 2018, 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667 and Life Sciences the "Funds") exercised a warrant to purchase 2,250,846, 17,626,445 and 439,036 shares of the common stock of Idera Pharmaceuticals, Inc. (the "Issuer") for $0.47 per share ("2018 Warrants").

F2 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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.

F7 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000337 · doc4_5319.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: 602,867

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

F1 · ownership.nature: On March 15, 2018, 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667 and Life Sciences the "Funds") exercised a warrant to purchase 2,250,846, 17,626,445 and 439,036 shares of the common stock of Idera Pharmaceuticals, Inc. (the "Issuer") for $0.47 per share ("2018 Warrants").

F4 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in 14159 Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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, L.P.'s right to receive an allocation of a portion of the profits from 14159.

F5 · ownership.nature: Includes beneficial ownership of 128,726 shares issued pursuant to the Stock Incentive Plan to Julian C. Baker and Kelvin M. Neu, respectively, a principal and an employee of Baker Bros. Advisors LP (the "Adviser") in lieu of director retainer fees, of which the fund may be deemed to own a portion. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds . Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F6 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees. The Funds each own an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F7 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000337 · doc4_5319.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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 34,193,251

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

F1 · ownership.nature: On March 15, 2018, 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667 and Life Sciences the "Funds") exercised a warrant to purchase 2,250,846, 17,626,445 and 439,036 shares of the common stock of Idera Pharmaceuticals, Inc. (the "Issuer") for $0.47 per share ("2018 Warrants").

F3 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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, 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.

F5 · ownership.nature: Includes beneficial ownership of 128,726 shares issued pursuant to the Stock Incentive Plan to Julian C. Baker and Kelvin M. Neu, respectively, a principal and an employee of Baker Bros. Advisors LP (the "Adviser") in lieu of director retainer fees, of which the fund may be deemed to own a portion. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds . Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F6 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees. The Funds each own an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F7 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000337 · doc4_5319.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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 4,102,796

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

F1 · ownership.nature: On March 15, 2018, 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667 and Life Sciences the "Funds") exercised a warrant to purchase 2,250,846, 17,626,445 and 439,036 shares of the common stock of Idera Pharmaceuticals, Inc. (the "Issuer") for $0.47 per share ("2018 Warrants").

F2 · ownership.nature: After giving effect to the transactions reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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.

F5 · ownership.nature: Includes beneficial ownership of 128,726 shares issued pursuant to the Stock Incentive Plan to Julian C. Baker and Kelvin M. Neu, respectively, a principal and an employee of Baker Bros. Advisors LP (the "Adviser") in lieu of director retainer fees, of which the fund may be deemed to own a portion. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds . Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F6 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu do not have any right to the pecuniary interest in the Issuer's securities issued in lieu of director retainer fees and the Funds are entitled to an indirect proportionate pecuniary interest in the securities issued in lieu of director fees. The Funds each own an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F7 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

SEC source: 0001638599-18-000321 · doc4_5312.xml · derivative · entry 13

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

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

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: 0

Underlying: Common Stock · 8,250 shares

Expires 2018-05-22

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

F14 · price: These non-qualified stock options are not priced.

F13 · ownership.nature: The disclosure of the exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

F20 · 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 8,250 shares of Common Stock of the Issuer received upon the exercise of stock options of the Issuer 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. The policy of the Funds and the Adviser, does not permit full-time employees or principals of the Adviser to receive compensation for serving as Directors of the Issuer.

SEC source: 0001638599-18-000321 · doc4_5312.xml · derivative · entry 12

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

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

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: 0

Underlying: Common Stock · 8,250 shares

Expires 2018-05-22

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

F14 · price: These non-qualified stock options are not priced.

F13 · ownership.nature: The disclosure of the exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

F19 · 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 8,250 shares of Common Stock of the Issuer received upon the exercise of stock options of the Issuer 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. The policy of the Funds and the Adviser, does not permit full-time employees or principals of the Adviser to receive compensation for serving as Directors of the Issuer.

SEC source: 0001638599-18-000321 · doc4_5312.xml · derivative · entry 11

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

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

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: 0

Underlying: Common Stock · 8,250 shares

Expires 2018-05-22

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

F14 · price: These non-qualified stock options are not priced.

F13 · ownership.nature: The disclosure of the exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

F18 · 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 8,250 shares of Common Stock of the Issuer received upon the exercise of stock options of the Issuer 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. The policy of the Funds and the Adviser, does not permit full-time employees or principals of the Adviser to receive compensation for serving as Directors of the Issuer.

SEC source: 0001638599-18-000321 · doc4_5312.xml · derivative · entry 10

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

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

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: 0

Underlying: Common Stock · 8,250 shares

Expires 2018-05-22

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

F14 · price: These non-qualified stock options are not priced.

F13 · ownership.nature: The disclosure of the exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

F17 · ownership.nature: 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 8,250 shares of Common Stock of the Issuer received upon the exercise of stock options of the Issuer 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 the profits from Baker Bros. Investments II. The policy of the Funds and the Adviser, does not permit full-time employees or principals of the Adviser to receive compensation for serving as Directors of the Issuer.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 0

Underlying: Common Stock · 8,250 shares

Expires 2018-05-22

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

F14 · price: These non-qualified stock options are not priced.

F13 · ownership.nature: The disclosure of the exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

F16 · ownership.nature: 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 8,250 shares of Common Stock of the Issuer received upon the exercise of stock options of the Issuer 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. The policy of the Funds and the Adviser, does not permit full-time employees or principals of the Adviser to receive compensation for serving as Directors of the Issuer.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 0

Underlying: Common Stock · 8,250 shares

Expires 2018-05-22

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

F14 · price: These non-qualified stock options are not priced.

F13 · ownership.nature: The disclosure of the exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

F15 · ownership.nature: 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 8,250 shares of Common Stock of the Issuer received upon the exercise of stock options of the Issuer 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. The policy of the Funds and the Adviser, does not permit full-time employees or principals of the Adviser to receive compensation for serving as Directors of the Issuer.

SEC source: 0001638599-18-000321 · doc4_5312.xml · nonDerivative · 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

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

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: 338,947

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

F2 · ownership.nature: The shares of common stock were received upon exercise of 8,250 stock options that were issued to Julian C. Baker in his capacity as a director of the Issuer. Julian C. Baker, pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), does not have any right to the pecuniary interest in the stock options issued for his service on the Board of Directors of the Issuer (the "Board") or the shares of common stock received upon exercise of such stock options.

F3 · ownership.nature: Each of 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") owns an indirect proportionate pecuniary interest in the shares of common stock received upon exercise of the stock options issued in connection with Julian C. Baker's service on the Board less the exercise cost of those options. Solely as a result of their 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 shares issued upon exercise of the stock options (i.e. no direct pecuniary interest).

F9 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 338,947 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: Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares, 16,500 of which were received previously, 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F12 · ownership.nature: 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. 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 exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 11,369,282

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

F2 · ownership.nature: The shares of common stock were received upon exercise of 8,250 stock options that were issued to Julian C. Baker in his capacity as a director of the Issuer. Julian C. Baker, pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), does not have any right to the pecuniary interest in the stock options issued for his service on the Board of Directors of the Issuer (the "Board") or the shares of common stock received upon exercise of such stock options.

F3 · ownership.nature: Each of 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") owns an indirect proportionate pecuniary interest in the shares of common stock received upon exercise of the stock options issued in connection with Julian C. Baker's service on the Board less the exercise cost of those options. Solely as a result of their 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 shares issued upon exercise of the stock options (i.e. no direct pecuniary interest).

F8 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 11,369,282 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.

F10 · ownership.nature: Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares, 16,500 of which were received previously, 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F12 · ownership.nature: 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. 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 exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 1,778,613

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

F2 · ownership.nature: The shares of common stock were received upon exercise of 8,250 stock options that were issued to Julian C. Baker in his capacity as a director of the Issuer. Julian C. Baker, pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), does not have any right to the pecuniary interest in the stock options issued for his service on the Board of Directors of the Issuer (the "Board") or the shares of common stock received upon exercise of such stock options.

F3 · ownership.nature: Each of 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") owns an indirect proportionate pecuniary interest in the shares of common stock received upon exercise of the stock options issued in connection with Julian C. Baker's service on the Board less the exercise cost of those options. Solely as a result of their 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 shares issued upon exercise of the stock options (i.e. no direct pecuniary interest).

F7 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 1,778,613 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.

F10 · ownership.nature: Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares, 16,500 of which were received previously, 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F12 · ownership.nature: 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. 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 exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 52,339

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

F2 · ownership.nature: The shares of common stock were received upon exercise of 8,250 stock options that were issued to Julian C. Baker in his capacity as a director of the Issuer. Julian C. Baker, pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), does not have any right to the pecuniary interest in the stock options issued for his service on the Board of Directors of the Issuer (the "Board") or the shares of common stock received upon exercise of such stock options.

F3 · ownership.nature: Each of 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") owns an indirect proportionate pecuniary interest in the shares of common stock received upon exercise of the stock options issued in connection with Julian C. Baker's service on the Board less the exercise cost of those options. Solely as a result of their 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 shares issued upon exercise of the stock options (i.e. no direct pecuniary interest).

F6 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 52,339 shares of Common Stock of the Issuer beneficially owned 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 the profits from Baker Bros. Investments II.

F10 · ownership.nature: Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares, 16,500 of which were received previously, 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F12 · ownership.nature: 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. 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 exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 212,998

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

F2 · ownership.nature: The shares of common stock were received upon exercise of 8,250 stock options that were issued to Julian C. Baker in his capacity as a director of the Issuer. Julian C. Baker, pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), does not have any right to the pecuniary interest in the stock options issued for his service on the Board of Directors of the Issuer (the "Board") or the shares of common stock received upon exercise of such stock options.

F3 · ownership.nature: Each of 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") owns an indirect proportionate pecuniary interest in the shares of common stock received upon exercise of the stock options issued in connection with Julian C. Baker's service on the Board less the exercise cost of those options. Solely as a result of their 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 shares issued upon exercise of the stock options (i.e. no direct pecuniary interest).

F5 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 212,998 shares of Common Stock of the Issuer beneficially owned 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.

F10 · ownership.nature: Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares, 16,500 of which were received previously, 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F12 · ownership.nature: 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. 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 exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000321 · doc4_5312.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

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

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: 233,262

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

F2 · ownership.nature: The shares of common stock were received upon exercise of 8,250 stock options that were issued to Julian C. Baker in his capacity as a director of the Issuer. Julian C. Baker, pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), does not have any right to the pecuniary interest in the stock options issued for his service on the Board of Directors of the Issuer (the "Board") or the shares of common stock received upon exercise of such stock options.

F3 · ownership.nature: Each of 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") owns an indirect proportionate pecuniary interest in the shares of common stock received upon exercise of the stock options issued in connection with Julian C. Baker's service on the Board less the exercise cost of those options. Solely as a result of their 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 shares issued upon exercise of the stock options (i.e. no direct pecuniary interest).

F4 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 233,262 shares of Common Stock of the Issuer beneficially owned 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.

F10 · ownership.nature: Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 24,750 shares, 16,500 of which were received previously, 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F12 · ownership.nature: 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. 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 exercise of directors options for shares of common stock reported in this form is a single exercise of 8,250 shares. The 8,250 shares is reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000057 · doc4_5183.xml · nonDerivative · entry 3

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 163,831

F1 · ownership.nature: 3,960 shares of common stock (the "Common Stock") issued to Julian C. Baker and 5,373 shares of Common Stock issued to Dr. Kelvin M. Neu, respectively, a principal and an employee of Baker Bros. Advisors LP (the "Adviser") pursuant to the Issuer's 2013 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $8,750 and $11,875, respectively. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds (as defined below). Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F2 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F5 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 163,831 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. Includes beneficial ownership of 128,726 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees, of which the fund may be deemed to own a portion.

F6 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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.

F7 · ownership.nature: The disclosure of the grant of Common Stock reported on this form is the sum of two grants totaling 9,333 shares. The 9,333 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000057 · doc4_5183.xml · nonDerivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 16,566,806

F1 · ownership.nature: 3,960 shares of common stock (the "Common Stock") issued to Julian C. Baker and 5,373 shares of Common Stock issued to Dr. Kelvin M. Neu, respectively, a principal and an employee of Baker Bros. Advisors LP (the "Adviser") pursuant to the Issuer's 2013 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $8,750 and $11,875, respectively. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds (as defined below). Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F2 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F4 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 16,566,806 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. Includes beneficial ownership of 128,726 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees, of which the fund may be deemed to own a portion.

F6 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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.

F7 · ownership.nature: The disclosure of the grant of Common Stock reported on this form is the sum of two grants totaling 9,333 shares. The 9,333 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000057 · doc4_5183.xml · nonDerivative · entry 1

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 1,851,950

F1 · ownership.nature: 3,960 shares of common stock (the "Common Stock") issued to Julian C. Baker and 5,373 shares of Common Stock issued to Dr. Kelvin M. Neu, respectively, a principal and an employee of Baker Bros. Advisors LP (the "Adviser") pursuant to the Issuer's 2013 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $8,750 and $11,875, respectively. The shares of Common Stock are fully vested. Julian C. Baker and Dr. Neu serve on the Issuer's Board of Directors (the "Board") as representatives of the Funds (as defined below). Dr. Neu also serves on the Compensation Committee of the Board for which he receives additional director retainer fees.

F2 · ownership.nature: Pursuant to the policies of the Adviser, Julian C. Baker and Dr. Neu 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (i.e., no direct pecuniary interest).

F3 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 1,851,950 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. Includes beneficial ownership of 128,726 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees of which the fund may be deemed to own a portion.

F6 · ownership.nature: The Adviser serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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.

F7 · ownership.nature: The disclosure of the grant of Common Stock reported on this form is the sum of two grants totaling 9,333 shares. The 9,333 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000048 · doc4_5177.xml · nonDerivative · 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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 330,697

F2 · ownership.nature: 292 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 292 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F10 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 330,697 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. Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 16,500 shares which were received from exercise of 16,500 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 584 shares. The 584 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000048 · doc4_5177.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

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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 11,361,032

F2 · ownership.nature: 292 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 292 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F9 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 11,361,032 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. Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 16,500 shares which were received from exercise of 16,500 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 584 shares. The 584 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000048 · doc4_5177.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 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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 1,770,363

F2 · ownership.nature: 292 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 292 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F8 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 1,770,363 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. Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 16,500 shares which were received from exercise of 16,500 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 584 shares. The 584 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000048 · doc4_5177.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 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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 44,089

F2 · ownership.nature: 292 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 292 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F7 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 44,089 shares of Common Stock of the Issuer beneficially owned 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. Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 16,500 shares which were received from exercise of 16,500 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 584 shares. The 584 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000048 · doc4_5177.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 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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 204,748

F2 · ownership.nature: 292 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 292 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F6 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 204,748 shares of Common Stock of the Issuer beneficially owned 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. Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 16,500 shares which were received from exercise of 16,500 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 584 shares. The 584 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000048 · doc4_5177.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 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

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 225,012

F2 · ownership.nature: 292 shares of restricted stock (the "Restricted Stock") issued to Felix J. Baker and 292 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 $10,000, 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 the Adviser (as defined below), 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. Solely as a result of their 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 shares of Restricted Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F5 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 225,012 shares of Common Stock of the Issuer beneficially owned 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. Includes beneficial ownership of 14,351 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 16,500 shares which were received from exercise of 16,500 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.

F11 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The disclosure of the grant of Restricted Stock reported on this form is the sum of two grants totaling 584 shares. The 584 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000047 · doc4_5178.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: 789,778

F4 · ownership.nature: 200 shares of common stock (the "Common Stock") issued to Julian C. Baker pursuant to the Issuer's Amended and Restated 2010 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $19,000. The shares of Common Stock are fully vested. Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below).

F5 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F8 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's ownership interest in 14159 Capital (GP), LLC, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in 789,778 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. Includes beneficial ownership of 2,072 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 95,000 shares received previously from exercise of 95,000 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The 200 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000047 · doc4_5178.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: 29,247,709

F4 · ownership.nature: 200 shares of common stock (the "Common Stock") issued to Julian C. Baker pursuant to the Issuer's Amended and Restated 2010 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $19,000. The shares of Common Stock are fully vested. Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below).

F5 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F7 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 29,247,709 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. Includes beneficial ownership of 2,072 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 95,000 shares received previously from exercise of 95,000 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The 200 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-18-000047 · doc4_5178.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: 4,387,180

F4 · ownership.nature: 200 shares of common stock (the "Common Stock") issued to Julian C. Baker pursuant to the Issuer's Amended and Restated 2010 Stock Incentive Plan (the "Stock Incentive Plan") in lieu of director retainer fees of $19,000. The shares of Common Stock are fully vested. Julian C. Baker serves on the Issuer's Board of Directors (the "Board") as a representative of the Funds (as defined below).

F5 · ownership.nature: Pursuant to the policies of Baker Bros. Advisors LP (the "Adviser"), Julian C. Baker does 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. 667, L.P. ("667"), Baker Brothers Life Sciences, L.P. ("Life Sciences") and 14159, L.P. ("14159", and together with 667, and Life Sciences, the "Funds") each owns an indirect proportionate pecuniary interest in the shares of Common Stock. Solely as a result of their 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 shares of Common Stock issued in lieu of director retainer fees (ie. no direct pecuniary interest).

F6 · ownership.nature: As a result of Felix J. Baker's and Julian C. Baker's 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 4,387,180 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. Includes beneficial ownership of 2,072 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees and 95,000 shares received previously from exercise of 95,000 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.

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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: The 200 shares are reported for each of the Funds as each has an indirect pecuniary interest.

SEC source: 0001638599-17-001172 · doc4_5089.xml · derivative · 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: 0

Underlying: Common Stock · 39,378 shares

Expires 2018-01-11

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

F3 · shares: On November 27, 2017, 14159, L.P. ("14159", and together with Life Sciences and 667, the "Funds") exercised a warrant to purchase 39,378 shares of the common stock of the Issuer for $1.38 per share ("2018 Warrants"). 14159 paid the exercise price on a cashless basis, resulting in the Issuer withholding of 1,941 of the 2018 Warrant shares to pay the exercise price and issuing to 14159 the remaining 37,437 shares of common stock of the Issuer. The Issuer also paid $6.36 to 14159 for the fractional shares. The Issuer's Board of Directors approved the exercise of the 2018 Warrants by 14159 on the cashless basis described in this footnote in advance of such exercise.

F7 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F4 · 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 the Issuer's shares of Common Stock reported in column 5 of Table I and warrants to purchase the Common Stock of the Issuer reported in column 9 of Table II 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.

F5 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds have relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · 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: 0001638599-17-001172 · doc4_5089.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: 489,977

F3 · shares: On November 27, 2017, 14159, L.P. ("14159", and together with Life Sciences and 667, the "Funds") exercised a warrant to purchase 39,378 shares of the common stock of the Issuer for $1.38 per share ("2018 Warrants"). 14159 paid the exercise price on a cashless basis, resulting in the Issuer withholding of 1,941 of the 2018 Warrant shares to pay the exercise price and issuing to 14159 the remaining 37,437 shares of common stock of the Issuer. The Issuer also paid $6.36 to 14159 for the fractional shares. The Issuer's Board of Directors approved the exercise of the 2018 Warrants by 14159 on the cashless basis described in this footnote in advance of such exercise.

F4 · 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 the Issuer's shares of Common Stock reported in column 5 of Table I and warrants to purchase the Common Stock of the Issuer reported in column 9 of Table II 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.

F5 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds have relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · 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: 0001638599-17-001172 · doc4_5089.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: 491,918

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

F3 · shares: On November 27, 2017, 14159, L.P. ("14159", and together with Life Sciences and 667, the "Funds") exercised a warrant to purchase 39,378 shares of the common stock of the Issuer for $1.38 per share ("2018 Warrants"). 14159 paid the exercise price on a cashless basis, resulting in the Issuer withholding of 1,941 of the 2018 Warrant shares to pay the exercise price and issuing to 14159 the remaining 37,437 shares of common stock of the Issuer. The Issuer also paid $6.36 to 14159 for the fractional shares. The Issuer's Board of Directors approved the exercise of the 2018 Warrants by 14159 on the cashless basis described in this footnote in advance of such exercise.

F4 · 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 the Issuer's shares of Common Stock reported in column 5 of Table I and warrants to purchase the Common Stock of the Issuer reported in column 9 of Table II 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.

F5 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds have relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · 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: 0001638599-17-001032 · doc4_5028.xml · nonDerivative · entry 3

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 16,557,473

F2 · ownership.nature: On October 26, 2017, 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667 and 14159 the "Funds") purchased 795,348 and 7,204,652 shares of the Common Stock, respectively of Idera Pharmaceuticals, Inc. (the "Issuer"), pursuant to an underwritten public offering.

F4 · ownership.nature: After giving effect to the transactions reported herein and as a result of Felix J. Baker's and Julian C. Baker's 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 16,557,473 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. Includes beneficial ownership of 119,393 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees, of which the fund may be deemed to own a portion.

F5 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · 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: 0001638599-17-001032 · doc4_5028.xml · nonDerivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director

14159, L.P. · CIK 0001551138 · Director

667, L.P. · CIK 0001551139 · Director

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

Baker Brothers Life Sciences LP · CIK 0001363364 · Director

BAKER FELIX · CIK 0001087940 · Director

BAKER JULIAN · CIK 0001087939 · Director

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnotes

Disclosed balance after: 1,842,617

F2 · ownership.nature: On October 26, 2017, 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667 and 14159 the "Funds") purchased 795,348 and 7,204,652 shares of the Common Stock, respectively of Idera Pharmaceuticals, Inc. (the "Issuer"), pursuant to an underwritten public offering.

F3 · ownership.nature: After giving effect to the transactions reported herein and as a result of Felix J. Baker's and Julian C. Baker's 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 1,842,617 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. Includes beneficial ownership of 119,393 shares issued pursuant to the Stock Incentive Plan in lieu of director retainer fees of which the fund may be deemed to own a portion.

F5 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · 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: 0001638599-17-001020 · doc4_4974.xml · nonDerivative · entry 7

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

14159, L.P. · CIK 0001551138 · Director · 10% owner

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

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

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

Baker Brothers Life Sciences LP · CIK 0001363364 · 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: 7,102

F8 · ownership.direct: Reflects 7,102 ADS of the Issuer held directly by Felix J. Baker received from the in-kind pro rata distribution without consideration reported above.

SEC source: 0001638599-17-001020 · doc4_4974.xml · nonDerivative · entry 6

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

14159, L.P. · CIK 0001551138 · Director · 10% owner

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

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

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

Baker Brothers Life Sciences LP · CIK 0001363364 · 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: 7,102

F7 · ownership.direct: Reflects 7,102 ADS of the Issuer held directly by Julian C. Baker received from the in-kind pro rata distribution without consideration reported above.

SEC source: 0001638599-17-001020 · doc4_4974.xml · nonDerivative · entry 5

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

14159, L.P. · CIK 0001551138 · Director · 10% owner

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

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

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

Baker Brothers Life Sciences LP · CIK 0001363364 · 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 · ownership.nature: Represents 49,200 ADS of the Issuer, each representing 13 Ordinary Shares distributed by 14159, L.P. 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, L.P. Prior to the pro rata distribution, on September 15, 2017, 639,600 Ordinary Shares directly held by 14159, L.P. were converted to 49,200 ADS.

F5 · ownership.nature: As a result of their ownership interest in 14159 Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's Ordinary Shares reported in column 5 of Table I directly held by 14159, L.P. ("14159" and together with Life Sciences and 667, the "Funds"), 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.

F6 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. 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: 0001638599-17-001019 · doc4_5024.xml · derivative · 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: 0

Underlying: Common Stock · 1,426,590 shares

Expires 2018-01-11

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

F7 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F4 · ownership.nature: As a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker each 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, 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.

F5 · 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 principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds have relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F6 · 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.