Page 8 of 16 – SEC Filing Amendment No. 22 to Schedule 13D
This Amendment No. 22 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”). 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
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 regarding the purchases in Item 5(c) 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Item 4 of Schedule 13D is supplemented and superseded, as the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:
The Funds hold securities of Seattle Genetics, Inc. (the “Issuer”)
for investment purposes. The Reporting Persons or their affiliates may purchase additional securities or dispose of securities
in varying amounts and at varying times depending upon the Reporting Persons’ continuing assessments of pertinent factors,
including the availability of shares of Common Stock or other securities for purchase at particular price levels, the business
prospects of the Issuer, other business investment opportunities, economic conditions, stock market conditions, money market conditions,
the attitudes and actions of the board of directors and management of the Issuer, the availability and nature of opportunities
to dispose of shares in the Issuer and other plans and requirements of the particular entities. The Reporting Persons may discuss
items of mutual interest with the Issuer, which could include items in subparagraphs (a) through (j) of Schedule 13D.
Depending upon their assessments of the above factors, the Reporting
Persons or their affiliates may change their present intentions as stated above and they may assess whether to make suggestions
to the management of the Issuer regarding financing, and whether to acquire additional securities of the Issuer, including shares
of Common Stock (by means of open market purchases, privately negotiated purchases, exercise of some or all of the Stock Options
(as defined below), or otherwise) or to dispose of some or all of the securities of the Issuer, including shares of Common Stock,
under their control.
Except as otherwise disclosed herein, at the present time, the
Reporting Persons do not have any plans or proposals with respect to any extraordinary corporate transaction involving the Issuer
including, without limitation, those matters described in subparagraphs (a) through (j) of Item 4 of Schedule 13D.
Page 8 of 16
Amendment No. 22 to Schedule 13D
This Amendment No. 22 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”). 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
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 regarding the purchases in Item 5(c) 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:
The Funds hold securities of Seattle Genetics, Inc. (the “Issuer”)
for investment purposes. The Reporting Persons or their affiliates may purchase additional securities or dispose of securities
in varying amounts and at varying times depending upon the Reporting Persons’ continuing assessments of pertinent factors,
including the availability of shares of Common Stock or other securities for purchase at particular price levels, the business
prospects of the Issuer, other business investment opportunities, economic conditions, stock market conditions, money market conditions,
the attitudes and actions of the board of directors and management of the Issuer, the availability and nature of opportunities
to dispose of shares in the Issuer and other plans and requirements of the particular entities. The Reporting Persons may discuss
items of mutual interest with the Issuer, which could include items in subparagraphs (a) through (j) of Schedule 13D.
Depending upon their assessments of the above factors, the Reporting
Persons or their affiliates may change their present intentions as stated above and they may assess whether to make suggestions
to the management of the Issuer regarding financing, and whether to acquire additional securities of the Issuer, including shares
of Common Stock (by means of open market purchases, privately negotiated purchases, exercise of some or all of the Stock Options
(as defined below), or otherwise) or to dispose of some or all of the securities of the Issuer, including shares of Common Stock,
under their control.
Except as otherwise disclosed herein, at the present time, the
Reporting Persons do not have any plans or proposals with respect to any extraordinary corporate transaction involving the Issuer
including, without limitation, those matters described in subparagraphs (a) through (j) of Item 4 of Schedule 13D.
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