Exhibit 10.2

THIRD AMENDMENT TO LEASE

This THIRD AMENDMENT TO LEASE (this “Amendment”) between B&N 141-302, LLC, a
Washington limited liability company (“Landlord”) and SEATTLE GENETICS, INC., a
Delaware corporation (“Tenant”).

Tenant, and Landlord, as successor owner to WCM 132-302, LLC, are parties to
that certain Lease dated December 1, 2000, as amended by that certain First
Amendment to Lease dated May 28, 2003 and that certain Second Amendment to Lease
dated July 1, 2008 (as amended, the “Lease”). Capitalized terms which are not
defined herein shall have the meanings set forth in the Lease.

WCM HIGHLANDS II, LLC, an affiliate of Landlord, and Tenant are in the process
of entering into a lease for the building located at 21717 30th Drive SE (the
“Ridgepoint Lease”). In order to induce the landlord to provide a $[***]
allowance in the Ridgepoint Lease, Tenant has agreed to cancel the termination
options contained in the Lease.

Landlord and Tenant agree as follows:

1. CANCELLATION OF TERMINATION RIGHTS. In consideration of the inclusion of a
$[***]allowance for lobby improvements in the Ridgepoint Lease, Tenant’s
termination rights set forth in Section 7 of the Second Amendment to the Lease
are hereby cancelled.

2. EFFECTIVE DATE. This Amendment shall take effect upon the mutual execution
and delivery of the Ridgepoint Lease.

3. NO OTHER AMENDMENTS. Except as modified by this Amendment, the First and
Second Amendment, the Lease remains in full force and effect and has not been
modified or amended.

 

DATED: May 9, 2011   Landlord:   B&N 131-302, LLC,     a Washington limited
liability company     By: Washington Capital Management, Inc.     Its: Manager

 

              By: /s/ Cory A. Carlson                                        
                                           Cory A. Carlson, President

 

    Tenant:   SEATTLE GENETICS, INC.,     a Delaware corporation     By: /s/
Clay B. Siegall, PhD                                         
                              Its: President &
CEO                                         
                                    

Confidential treatment has been requested for portions of this exhibit. The copy
filed herewith omits the

information subject to the confidentiality request. Omissions are designated as
[***]. A complete version of

this exhibit has been filed separately with the Securities and Exchange
Commission.

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STATE OF WASHINGTON           )           ) ss. COUNTY OF KING           )

I certify that I know or have satisfactory evidence that Patrick S. Malley is
the person who appeared before me, and said person acknowledged that he/she
signed this instrument, on oath stated that he/she was authorized to execute the
instrument and acknowledged it as Senior Vice President of Washington Capital
Management, Inc., Manager of B&N 141-302, LLC, a Washington limited liability
company to be the free and voluntary act of such party for the uses and purposes
mentioned in this instrument.

 

DATED: May 9, 2011.             /s/ Jennifer Ourada    

 

(Signature of Notary Public)

    Jennifer Ourada    

 

(Printed Name of Notary Public)

    My Appointment expires 8-20-14

STATE OF WASHINGTON           )           ) ss. COUNTY OF KING           )

I certify that I know or have satisfactory evidence that Todd Simpson is the
person who appeared before me, and said person acknowledged that he/she signed
this instrument, on oath stated that he/she was authorized to execute the
instrument and acknowledged it as CFO of SEATTLE GENETICS, INC., a Delaware
corporation to be the free and voluntary act of such party for the uses and
purposes mentioned in this instrument.

 

DATED: May 9, 2011.              /s/ Amy L. Olofson    

 

(Signature of Notary Public)

    Amy L. Olofson    

 

(Printed Name of Notary Public)

    My Appointment expires 10-9-14