Page 8 of 12 – SEC Filing
Amendment No. 24 to Schedule 13D
This Amendment No. 24 to Schedule 13D amends and supplements the
statements on the previously filed Schedule 13D, as amended, filed by Baker Bros. Advisors LP (the “Adviser”), Baker
Bros. Advisors (GP) LLC (the “Adviser GP”), Julian C. Baker, Felix J. Baker, FBB2, LLC (“FBB2”) and FBB3
LLC (“FBB3”) (collectively the “Reporting Persons”). Except as supplemented herein, such statements, as
heretofore amended and supplemented, remain in full force and effect. Information given in response to each item shall be deemed
incorporated by reference in all other items, as applicable. Each capitalized term used but not defined herein has the meaning
ascribed to such term in the Schedule 13D, as amended.
The Adviser GP is the sole general partner of the Adviser. Pursuant
to management agreements, as amended, among the Adviser, Baker Brothers Life Sciences, L.P. (“Life Sciences”) and 667,
L.P. (“667”, and together with Life Sciences, the “Funds”), and their respective general partners, the
Funds’ respective general partners relinquished to the Adviser all discretion and authority with respect to the investment
and voting power of the securities held by the Funds, and thus the Adviser has complete and unlimited discretion and authority
with respect to the Funds’ investments and voting power over investments.
Item 3. Source and Amount of Funds or Other Consideration.
Item 3 of Schedule 13D is supplemented and amended, as the case
may be, as follows:
The disclosure in Item 4 below is incorporated herein by reference.
Item 4. Purpose of the Transaction.
Item 4 of Schedule 13D is supplemented and superseded, as the case
may be, as follows:
On May 15, 2017, the Adviser acquired beneficial ownership of 10,000
shares of common stock of Seattle Genetics, Inc. (the “Issuer”), as a result of the exercise of 10,000 options to purchase
the Issuer’s common stock at $10.20 per share (the “Exercised Stock Options”) held directly by Felix J. Baker.
Felix J. Baker currently serves on the Issuer’s Board of Directors (the “Board”) as a representative of the Funds.
The policy of the Funds and the Adviser does not permit employees of the Adviser to receive compensation for serving as directors
of the Issuer, and the Funds are instead entitled to the pecuniary interest in the Exercised Stock Options. Felix J. Baker, as
an agent in his capacity as a director of the Issuer, entered into a proceeds agreement (the “Proceeds Agreement”)
with the Adviser on May 15, 2017. Pursuant to the Proceeds Agreement, Felix J. Baker agreed that, with respect to the Exercised
Stock Options and the common stock received as a result of the exercise of the Exercised Stock Options (the “Common Stock”)
on May 15, 2017, the Adviser will have dispositive power as well as the ability to control the timing of exercise of the Exercised
Stock Options and that any proceeds from the sale of the Common Stock will be remitted to the Adviser net of brokerage commissions.
Other than through their control of the Adviser, Felix J. Baker and Julian C. Baker have neither voting nor dispositive power and
have no direct pecuniary interest in the Exercised Stock Options or the Common Stock. Pursuant to the Proceeds Agreement, the Adviser
funded Felix J. Baker’s exercise of the Exercised Stock Options through loans from the Funds (the “Loan Agreements”).
The total amount expended on acquiring the Common Stock was $102,000.
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