SECOND AMENDMENT TO OFFICE LEASE AGREEMENT

Exhibit 10.15

SECOND AMENDMENT
TO
OFFICE LEASE AGREEMENT

     THIS SECOND AMENDMENT TO OFFICE LEASE (this “ Amendment ”) is made this 9th day of March, 2009, by and between SELIG HOLDINGS COMPANY, L.L.C., a Delaware limited liability company (“ Lessor ”) and DENDREON CORPORATION, a Delaware corporation (“ Lessee” ).

RECITALS:

     A. Lessor is the owner of that certain real property commonly known as 3101 Western Avenue in Seattle, Washington and legally described in Exhibit A (the “ Property ”).

     B. Lessor is the successor in interest to SELIG REAL ESTATE HOLDINGS XIV, L.L.C., a Washington limited liability company, the prior owner of the Property.

     C. Lessor and Lessee are parties to that certain Office Lease dated September 2, 2004 (the “ 2004 Lease ”) for approximately: (i) 21,795 rentable square feet on the eighth floor of the Property; and (ii) 1,818 rentable square feet of the exercise facility on the upper parking level of the Property. The Lease was amended by that certain First Amendment to Office Lease dated March 8, 2005 (the “ 2005 Amendment ”). The 2004 Lease and the 2005 Amendment are collectively referred to herein as the “ Lease ”.

     D. Under the terms of the Lease, Lessee’s current term expires on September 30, 2009 (the “ Existing Expiration Date ”). Lessee desires to extend the term of the Lease through December 31, 2011 (the “ Amended Expiration Date ”).

     E. Lessor and Lessee desire to amend the Lease in order to provide for the extension of the Lease term as described herein and to memorialize other changes they have agreed to by entering into this Amendment.

AGREEMENT:

     NOW, THEREFORE, in consideration of the above and the mutual promises contained in this Amendment, and other good and valuable consideration, the receipt and sufficiency of which are acknowledged, Lessor and Lessee agree as follows:

     1.  Confirmation of Lease . Lessor and Lessee each agree and confirm that the Lease is in full force and effect and has not been previously modified and neither Lessor nor Lessee is aware of any failure of the other party to perform its obligations under the Lease that are accrued as of the date of this Amendment.

     2.  Term . The term of the Lease is hereby extended for a period of twenty-seven (27) months beginning on the day after the Existing Expiration Date and ending on the Amended Expiration Date.

     3.  Rent . During the period between the Existing Expiration Date and the Amended Expiration Date, Lessee covenants and agrees to pay to Lessor rent each month in advance on the first day of each calendar month. Except for Lessee’s share of increases in the co