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REDACTED VERSION

SUBLEASE AGREEMENT

    This Sublease Agreement ("Sublease") dated as of July 24, 2000, is made
between F5 Networks, Inc., a Washington corporation ("Sublandlord"), and NeoRx
Corporation Inc., a Washington corporation ("Subtenant").

RECITALS

    A.  Pursuant to the Amended and Restated Office Lease Agreement dated
April 3, 2000 between 401 Elliott West, LLC, a Washington limited liability
corporation, as lessor ("Landlord") and Sublandlord as lessee (together with all
modifications, amendments, riders and exhibits thereto, the "Master Lease"), a
copy of which is attached hereto as Exhibit A, Landlord leased to Sublandlord
approximately 110,111 rentable square feet of space in Building 3 located at 401
Elliott Avenue West in Seattle, Washington (the "Building").

    B.  Sublandlord wishes to sublease to Subtenant 28,854 rentable square feet
of the Building located on the second floor of the Building shown cross-hatched
on Exhibit B attached hereto (the "Subleased Premises").

    NOW, THEREFORE, in consideration of the mutual covenants contained in this
Sublease, and for other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged by the parties, Sublandlord and
Subtenant hereby agree as follows:

AGREEMENT

1.  Sublease  

    Sublandlord hereby subleases to Subtenant and Subtenant hereby subleases
from Sublandlord, for the Term, at the rental, and upon all of the conditions
set forth herein, the Subleased Premises, together with the right to use, in
common with others entitled thereto, the hallways, stairways and elevators
necessary for access to the Subleased Premises and the lavatories nearest to the
Subleased Premises.

2.  Term and Possession  

2.1  Term  

    The term of this Sublease ("Term") shall commence on November 1, 2000
("Commencement Date"). The Term shall expire on October 31, 2003 ("Expiration
Date"). Effective at the end of the initial 24 months of the Sublease term,
Sublandlord and Subtenant shall have the right to cancel the Sublease with nine
months prior notice.

2.2  Condition of Subleased Premises  

    Sublandlord shall deliver to Subtenant possession of the Subleased Premises
on the Commencement Date in a turnkey condition ("Possession") pursuant to
Sublandlord's construction documents. If for any reason Sublandlord does not
deliver Possession to Subtenant on the Commencement Date, Base Rent, as defined
in Section 3.1, shall abate until delivery of Possession. Attached is a plan
that shows the "scope and nature" of improvements that will be provided.

3.  Base Rent and Operating Expenses  

3.1  Base Rent  

    Subtenant shall pay to Sublandlord Base Rent on or before the first day of
each calendar month during the Term. The monthly installments of Base Rent shall
be prorated on a per diem basis for the

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first or last month of the Term if the Commencement Date or Expiration Date is
not the first day or last day of a calendar month.

Period

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  Monthly

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  Annual

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November 1, 2000 to October 31, 2001   [*]   [*] November 1, 2001 to October 31,
2002   [*]   [*] November 1, 2002 to October 31, 2003   [*]   [*]

3.2  Operating Expenses  

    Subtenant agrees to pay as Additional Rent its proportionate share of all
expenses, as defined in Section 4 of the Master Lease, attributable to its lease
of the Sublease Premises, including all increases in said expenses over the term
of the lease. Subtenant's percentage of the building area of Building Three is
26.20%.

4.  Tenant Improvements  

    Sublandlord shall provide scale floor plans for floor 2 including dimensions
of private offices, conference rooms, kitchen or break rooms, cubicles, etc.
Subtenant may make modifications to the attached plan, and will restore the
Subleased Premises to its original condition at the end of the Sublease term at
Subtenant's expense.

5.  Parking  

    Subtenant shall have the right to 1.9 stalls per 1,000 square feet of space
leased throughout the term of the Sublease on an unreserved basis in the
Building parking garage. The cost for the stalls shall be at market rate.

6.  Early Access  

    Subtenant and Subtenant's contractors shall have early access to the
Subleased Premises one month prior to occupancy by Subtenant, for Subtenant's
installation of furniture, equipment, telephone lines, data network wiring and
security.

7.  Security Deposit  

    Contemporaneously with the execution hereof, Subtenant shall deposit with
Sublandlord the sum of the first month's rent and the last three months' due
(which equates to [*]) as security for Subtenant's faithful performance of
Sublandlord's obligations hereunder ("Security Deposit"). The Security Deposit
shall be applied to Subtenant's last month's rent due; provided, however, if
Subtenant fails to pay rent or other charges when due under this Sublease, or
fails to perform any of its obligations hereunder, Sublandlord may use or apply
all or any portion of the Security Deposit for the payment of any rent or other
amount then due hereunder and unpaid, for the payment of any other sum for which
Sublandlord may become obligated by reason of Subtenant's default or breach, or
for any loss or damage sustained by Sublandlord as a result of Subtenant's
default or breach.

8.  Use of Subleased Premises  

    The Subleased Premises shall be used and occupied only for general office
purposes and for any other purpose permitted under the Master Lease.

9.  Assignment and Sublease  

    Subtenant shall be permitted to sublease individual offices to any subagents
and/or clients without obtaining Sublandlord's consent. Subtenant shall be
permitted to sublease or assign all or portion of the Subleased Premises subject
to Sublandlord's and Landlord's consent per the terms and conditions of the
Master Lease.

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10.  Incorporation by Reference  

10.1  Subject to Lease  

    This Sublease is subject to all of the terms and condition of the Master
Lease by and between Sublandlord and Landlord. Subtenant shall obtain insurance
for the Subleased Premises and name Sublandlord as an additional insured in the
policy.

10.2  Interpretation  

    The terms, conditions and respective obligations of Sublandlord and
Subtenant to each other under this Sublease shall be the terms and conditions of
the Master Lease except for those provisions of the Master Lease which are
directly contradicted by this Sublease, in which event the terms of this
Sublease shall control over the Master Lease. Therefore, for the purposes of
this Sublease, wherever in the Master Lease the word "Lessor" is used it shall
be deemed to mean the Sublandlord herein and wherever in the Master Lease the
word "Lessee" is used it shall be deemed to mean the Subtenant herein.

11.  Sublandlord's Representations and Warranties  

    Sublandlord represents and warrants to Subtenant as follows:

    11.1  The Master Lease is in full force and effect and has not been
modified, supplemented or amended.

    11.2  Sublandlord has the right to and is in full and complete possession of
the Master Premises.

    11.3  Sublandlord has fulfilled all its duties under the Master Lease and is
not in default under the Master Lease.

    11.4  To the best of Sublandlord's knowledge, Landlord has fulfilled all its
duties under the Master Lease and is not in default under the Master Lease.

    11.5  Sublandlord has not assigned, transferred or delegated any of its
right or duties under the Master Lease or pledged or encumbered any of its
interest in, or right under the Master Lease.

    11.6  Sublandlord has reviewed the Master Lease (as that term is defined in
the Master Lease), the Master Lease does not in any way prohibit this Sublease,
the consent of the lessor under the Master Lease is not required for this
Sublease, and no provision of the Master Lease could adversely affect the
Subleased Premises or Subtenant's rights or obligations under this Sublease.

    11.7  Landlord has consented to the Sublease pursuant to the letter
agreement attached hereto as Exhibit C.

    11.8  Sublandlord has all right, power and authority necessary to enter into
and deliver this Sublease and to perform its obligations hereunder.

12.  Covenants Regarding Lease  

    12.1  Sublandlord shall not commit or suffer any act or omission that will
result in a violation of or a default under any of the provisions of the Lease.

    12.2  Sublandlord shall exercise commercially reasonable efforts in
attempting to cause Landlord to perform its obligations and give any required
consents under the Master Lease for the benefit of Subtenant.

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    12.3  Sublandlord agrees to deliver to Subtenant a copy of any notice
received from Landlord relating to the Subleased Premises within three (3) days
of its receipt thereof.

    12.4  In the event that Sublandlord defaults under its obligations to be
performed under the Master Lease, Subtenant shall have the right to cure the
default before the date Sublandlord's applicable cure period expires. If such
default is cured by Subtenant, Sublandlord shall reimburse Subtenant for such
amounts within ten (10) days after notice and demand therefor from Subtenant,
together with interest at the interest rate specified in the Master Lease. If
Sublandlord fails to reimburse Subtenant within such ten (10) day period,
Subtenant may deduct such amounts from subsequent installments of rent due to
Sublandlord under this Sublease.

    12.5  Sublandlord shall not voluntarily terminate the Master Lease without
Subtenant's prior written consent.

    12.6  Sublandlord shall not amend the Master Lease in any way that would
affect the Subleased Premises or Subtenant's rights or obligations under this
Sublease without Subtenant's prior written consent.

13.  Indemnification  

13.1  Subtenant's Indemnification  

    Subtenant shall indemnify, defend and hold harmless Sublandlord from and
against all losses, costs, damages, expenses and liabilities, including, without
limitation, reasonable attorneys' fees and disbursements, which Sublandlord may
incur or pay out (including, without limitation, to Landlord) by reason of
(a) any accidents, damages or injuries to persons or property occurring in, on
or about the Subleased Premises (unless the same shall have been caused by
Sublandlord's negligence or wrongful act or the negligence or wrongful act of
Landlord), (b) any breach or default hereunder on Subtenant's part, (c) the
successful enforcement of Sublandlord's rights under this Section or any other
Section of this Sublease, (d) any work done after the date hereof in or to the
Subleased Premises except if done by Sublandlord or Landlord, or (e) any act,
omission or negligence on the part of Subtenant and/or its officers, partners,
employees, agents, customers and/or invitees, or any person claiming through or
under Subtenant.

13.2  Sublandlord's Indemnification  

    Sublandlord shall indemnify, defend and hold harmless Subtenant from and
against all losses, costs, damages, expenses and liabilities, including, without
limitation, reasonable attorneys' fees and disbursements, which Subtenant may
incur or pay out (including, without limitation, to Landlord) by reason of
(a) any accidents, damages or injuries to persons or property occurring in, on
or about any portion of the Master Premises other than the Subleased Premises
(unless the same shall have been caused by Subtenant's negligence or wrongful
act), (b) any breach or default hereunder or under the Master Lease on
Sublandlord's part, (c) the successful enforcement of Subtenant's rights under
this Section or any other Section of this Sublease, or (d) any act, omission or
negligence on the part of Sublandlord and/or its officers, partners, employees,
agents, customers and/or invitees, or any person claiming through or under
Sublandlord.

14.  Notices  

    All notices and demands that may or are to be required or permitted are to
be given by either party on the other hereunder shall be in writing. All notices
and demands by Sublandlord to Subtenant shall be personally delivered or sent by
a nationally recognized private carrier of overnight mail (e.g. FedEx) or by
United States Certified Mail, return receipt requested and postage prepaid, to
the parties

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at the addresses listed below or at such other addresses as the parties may
designate by notice from time to time.

To Sublandlord:   F5 Networks, Inc
401 Elliott Ave West
Seattle, Washington 98119
Attention: Joann Reiter, General Counsel  
To Subtenant:  
   
NeoRx Corporation
410 West Harrison Street
Seattle, Washington 98119
Attention: Paul Abrams, CEO

15.  Quiet Enjoyment  

    Provided that Subtenant is not in default of any term or provision of the
Master Lease or this Sublease, Subtenant shall have peaceful and quiet enjoyment
of the Subleased Premises without interference from Sublandlord or any person or
entity claiming by, through or under Sublandlord.

15.  Attorney's Fees  

    If Sublandlord or Subtenant shall commence an action against the other
arising out of or in connection with this Sublease, the prevailing party shall
be entitled to recover its costs of suit and reasonable attorney's fees.

16.  Entire Agreement  

    This Sublease, the Exhibits attached hereto and the Master Lease, which is
incorporated herein by reference, constitute the entire agreement between
Sublandlord and Subtenant with respect to the Subleased Premises and may not be
amended or altered except by written agreement executed by both parties.

17.  Binding on Successors  

    This Sublease shall bind the parties' heirs, successors, representatives and
permitted assigns.

    IN WITNESS WHEREOF, the parties hereto hereby execute this Sublease as of
the day and year first above written.

 
SUBLANDLORD: F5 Networks, Inc.  
   
SUBTENANT: NeoRx Corporation Inc.  
By  
   
/s/ Robert J. Chamberlain  
   
By  
   
/s/ Paul G. Abrams  
Name  
   
Robert J. Chamberlain  
   
Name  
   
Paul G. Abrams  
Title  
   
CFO  
   
Title  
   
CEO  
   
   
   
   
   
   
 

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STATE OF WASHINGTON   )         ) ss.     COUNTY OF KING   )    

    On this 24th day of July, 2000, before me, the undersigned, a Notary Public
in and for the State of Washington, duly commissioned and sworn, personally
appeared Robert J. Chamberlain, to me known to be the person who signed as CFO
of F5 NETWORKS, INC., the corporation that executed the within and foregoing
instrument, and acknowledged said instrument to be the free and voluntary act
and deed of said corporation for the uses and purposes therein mentioned, and on
oath stated that he was duly elected, qualified and acting as said officer of
the corporation, that he was authorized to execute said instrument and that the
seal affixed, if any, is the corporate seal of said corporation.

    IN WITNESS WHEREOF I have hereunto set my hand and official seal the day and
year first above written.

    (Not Legible) G. Gilbert

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Signature  
   
   
NOTARY PUBLIC in and for the State of Washington, residing at Snohomish County.
My appointment expires: 6/1/02

STATE OF WASHINGTON

COUNTY OF KING

    On this 14 day of July, 2000, before me, the undersigned, a Notary Public in
and for the State of Washington, duly commissioned and sworn, personally
appeared Paul G. Abrams, to me known to be the person who signed as CEO of NEORX
CORPORATION INC., the corporation that executed the within and foregoing
instrument, and acknowledged said instrument to be the free and voluntary act
and deed of said corporation for the uses and purposes therein mentioned, and on
oath stated that he was duly elected, qualified and acting as said officer of
the corporation, that he was authorized to execute said instrument and that the
seal affixed, if any, is the corporate seal of said corporation.

    IN WITNESS WHEREOF I have hereunto set my hand and official seal the day and
year first above written.

    /s/ T. H. Craven

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Signature

NOTARY PUBLIC in and for the State
of Washington, residing at Redmond, WA.
My appointment expires: 9/4/2003

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