BAKER BROS. ADVISORS LP - 05 Jun 2024 Form 4 Insider Report for Kiniksa Pharmaceuticals, Ltd. (KNSA)

Footnote F1

Includes 3,173 restricted stock units (each an "RSU") payable solely in Class A common shares ("Class A Common Shares") granted by Kiniksa Pharmaceuticals, Ltd. (the "Issuer") to each of Felix J. Baker, a managing member of Baker Bros. Advisors (GP) LLC (the "Adviser GP"), and Dr. Stephen R. Biggar, an employee of Baker Bros. Advisors LP (the "Adviser"), on June 5, 2024, pursuant to the Issuer's 2018 Incentive Award Plan (the "Incentive Award Plan"). The RSUs fully vest on the first anniversary of the grant date subject to the applicable director's continuous service on the board of directors of the Issuer (the "Board") through the vesting date. Felix J. Baker and Dr. Biggar serve on the Board as representatives of 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds") and their affiliates and control persons.

Footnote F2

After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Class A Common Shares reported in column 5 of Table I and the Share Options (as defined below) reported in column 9 of Table II held directly by or held for the benefit of 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

Footnote F3

Pursuant to the policies of the Adviser, Felix J. Baker and Dr. Biggar do not have a right to any of the Issuer's securities issued as compensation for their service on the Board and the Funds are entitled to an indirect proportionate pecuniary interest in such securities. The Funds each own an indirect proportionate pecuniary interest in the non-qualified share options exercisable solely into Class A Common Shares ("Share Options") and RSUs. Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the Share Options, RSUs and any Class A Common Shares acquired upon the exercise of Share Options or vesting of RSUs (i.e. no direct pecuniary interest) issued as compensation for such Board Service.

Footnote F4

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 directly by the Funds or for the benefit of the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held directly by the Funds or for the benefit of 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 directly by the Funds or for the benefit of the Funds.

Footnote F5

Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by or held for the benefit of 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.

Footnote F6

Pursuant the policies of the Adviser, the Adviser has voting and dispositive power over the Share Options, RSUs and any Class A Common Shares received as a result of the exercise of Share Options or vesting of RSUs.

Footnote F7

The acquisitions of the RSUs and Share Options reported on this form represent grants to each of Felix J. Baker and Dr. Biggar of 3,173 RSUs on Table I and 19,040 Share Options on Table II. These grants, totaling 6,346 RSUs and 38,080 Share Options for Felix J. Baker and Dr. Biggar in the aggregate, are reported for each of the Funds as each has an indirect pecuniary interest in such securities.

Footnote F8

Includes beneficial ownership of 9,373 Class A Common Shares received from vested RSUs each previously granted to Felix J. Baker and Dr. Biggar in their capacity as directors of the Issuer.

Footnote F9

After giving effect to the transactions reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Class A Common Shares reported in column 5 of Table I and the Share Options reported in column 9 of Table II held directly by or held for the benefit of Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

Footnote F10

Class A Common Shares held directly by Felix J. Baker.

Footnote F11

Class A Common Shares held directly by Julian C. Baker.

Footnote F12

Includes 19,040 Share Options granted by the Issuer to each of Felix J. Baker and Dr. Biggar on June 5, 2024, pursuant to the Incentive Award Plan. The Share Options have a strike price of $19.71, vest in 12 equal monthly installments and expire 10 years from the date of grant.