Document:

<PAGE>

                                                                   EXHIBIT 10.18

                             SECOND LEASE AMENDMENT

                                     BETWEEN

                          BENAROYA CAPITAL COMPANY, LLC

                                       AND

                                ICOS CORPORATION

This Second Lease Amendment dated August 13, 2001 is attached to and made part
of that certain Lease dated May 20th, 1997, as amended by that First Lease
Amendment dated February 18, 1998 (the "Lease") between Benaroya Capital
Company, LLC., a Washington limited liability company, as Lessor ("Lessor") and
ICOS Corporation., a Delaware corporation, as Lessee ("Lessee") in the Building
known as Canyon Park - 4, at 2222 220th Street SE in Bothell, Washington (the
"Premises"). The Premises are more particularly described in the Lease.

The terms used herein shall have the same definitions as set forth in the Lease.

In consideration of the mutual covenants and promises contained in this Second
Lease Amendment, the First Lease Amendment, and the Lease, Lessor and Lessee
agree as follows:

1.    SECTION 1 PREMISES. The Premises' area is hereby amended to be 17,390
      square feet, consisting of 13,022 square feet of office/laboratory area
      and 4,368 square feet of mezzanine storage area, as outlined on the floor
      plan of the Premises attached hereto as Exhibit A-1, which hereby replaces
      Exhibit A of the Lease.

2.    SECTION 2 TERM. The Term of the Lease is hereby extended for an additional
      term of three (3) years, ten (10) months, and ten (10) days, commencing
      May 22, 2002 and expiring March 31, 2006 ("the First Extended Term"). This
      extension constitutes Lessee's exercise of the first (1st) of two (2)
      successive options to renew as provided in Section 34, Option to Extend,
      of the Lease, as amended by the First Lease Amendment, thereby leaving one
      (1) five (5) year option to renew remaining (the term of that renewal, if
      exercised will be for the period of April 1, 2006 to March 31, 2011). The
      actual term of this extension is (3) years, ten (10) months, and ten (10)
      days, rather than 5 years. Lessee has requested of Lessor, and Lessor has
      agreed, to revise the Term of the First Extended Term to be co-terminus
      with the other lease between Lessor and Lessee for the adjacent space in
      the CP-4 Building.

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8/13/01, Page 2

3.    SECTION 3 RENT. During the First Extension Term, the Base Monthly Rent
      shall be as follows:

<TABLE>
<CAPTION>
                        Months                          Base Monthly Rent
                        ------                          -----------------
<S>                                                        <C>
          May 22, 2002 - May 21, 2003                      $ 9,944.00
          May 22, 2003 - May 21, 2004                      $10,416.00
          May 22, 2004 - May 21, 2005                      $10,911.00
          May 22, 2005 - March 31, 2006                    $11,429.00
</TABLE>

4.    SECTION 4 SECURITY DEPOSIT. The Security Deposit is hereby increased by
      Two Thousand Eight Hundred Twenty-Three and No/100 dollars ($2,823.00),
      from Eight Thousand Six Hundred Six and No/100 dollars ($8,606.00), to
      Eleven Thousand Four Hundred Twenty-Nine and No/100 dollars ($11,429.00).

Except as otherwise modified by the Terms of this Second Lease Amendment, all
other terms and conditions of the Lease remain unchanged and in full force and
effect.

LESSOR:                                  LESSEE:
BENAROYA CAPITAL COMPANY, LLC.           ICOS CORPORATION

     /s/ Larry R. Benaroya                    /s/ Gary Wilcox
------------------------------------     ---------------------------------------
By: Larry R. Benaroya                    By: Gary Wilcox
Its: Manager                             Its: EVP, Operations

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8/13/01, Page 3

STATE OF WASHINGTON      ]
                         ] ss.
COUNTY OF KING           ]

I certify that I know or have satisfactory evidence that Larry R. Benaroya is
the person who appeared before me, a Notary Public in and for the State of
Washington duly commissioned and sworn, and acknowledged that he is the Manager
of BENAROYA CAPITAL COMPANY, LLC, a Washington limited liability company who
executed the within and foregoing instrument, and acknowledged the instrument to
be the free and voluntary act and deed of said company for the uses and purposes
therein mentioned, and on oath stated that affiant is authorized to execute said
instrument on behalf of said company.

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

                                     /s/ Rebecca A. Bethel
                                     -------------------------------------------
                                     Notary Public in and for the
                                     State of Washington
                                     residing at Seattle
                                     Commission expires 11/9/02
                                     Print Name Rebecca A. Bethel

STATE OF WASHINGTON      ]
                         ] ss.
COUNTY OF Snohomish      ]

      I certify that I know or have satisfactory evidence that Gary Wilcox is
the person who appeared before me, a Notary Public in and for the State of
Washington duly commissioned and sworn, and acknowledged that he/she is the
representative, of ICOS CORPORATION, a Delaware corporation, who executed the
within and foregoing instrument, and acknowledged the 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 affiant is authorized to execute said
instrument on behalf of said corporation.

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

                                     /s/ Lori L. Briseno
                                     -------------------------------------------
                                     Notary Public in and for the
                                     State of Washington
                                     residing at Snohomish
                                     Commission expires 4/29/02
                                     Print Name Lori L. Briseno
<PAGE>

8/13/01, Page 4

                                   EXHIBIT A-1
                           FLOOR PLAN OF THE PREMISES<PAGE>
                                                                   EXHIBIT 10.22

                        INDUSTRIAL LEASE - SINGLE TENANT

THIS LEASE AGREEMENT made this 4th day of June, 2001, by and between BENAROYA
CAPITAL COMPANY, LLC, a Washington limited liability company (the "Lessor") and
ICOS CORPORATION, a Delaware corporation (the "Lessee").

1.    PREMISES. Lessor does hereby lease to Lessee those certain premises, to
      wit: 22,200 square feet of space in Suite 100 in the Building known as
      Canyon Park - 12 located at 22032 23rd Drive SE, in Bothell, Washington as
      outlined on Exhibit A attached hereto (hereinafter called "Premises"). The
      Building is hereafter sometimes referred to as the "Project". In addition,
      the Lessee has the right, subject to the Rules and Regulations, to use of
      the Common Areas including the parking areas.

2.    TERM. The Lease shall be for a term of five (5) years commencing on the
      Lease Commencement Date and expiring five (5) years thereafter. The Lease
      Commencement Date will be the earlier to occur of the following, but in no
      event before June 1, 2002 or later than October 1, 2002:

            (a)   any date specified by Lessee with at least six months prior
                  written notice to Lessor; or

            (b)   any date specified by Lessor with at least five months prior
                  written notice to Lessee.

      Upon acknowledgment of receipt of the notice specified in (a) or (b) above
      by either Lessor or Lessee respectively, the date specified in such notice
      shall thereafter be the Lease Commencement Date.

3.    RENT. Lessee covenants and agrees to pay Lessor at 1001 Fourth Avenue,
      Suite 4700, Seattle, WA 98154, or to such other party or at such other
      place as Lessor may hereafter designate, monthly rent in advance without
      offset or deduction, on or before the first (1st) day of each month of the
      Lease term in the amounts as follows:

<TABLE>
<CAPTION>
               Months:                             Base Rent:
               -------                             ----------
<S>                                                <C>
               Months 1 - 12                       $28,465.00 per month
               Months 13 - 24                      $29,461.00 per month
               Months 25 - 36                      $30,492.00 per month
               Months 37 - 48                      $31,560.00 per month
               Months 49 - 60                      $32,664.00 per month
</TABLE>

4.    SECURITY DEPOSIT. Lessee shall deposit with Lessor on the Commencement
      Date Thirty-Two Thousand Six Hundred Sixty-Four and No/100 dollars
      ($32,664.00). Said sum shall be held by Lessor as security for the
      faithful performance by Lessee of all the terms, covenants and conditions
      of this Lease to be kept and performed by Lessee during the entire Term
      hereof. If Lessee defaults with respect to any provision of this Lease,
      including, but not limited to, the provisions relating to the payment of
      Rent or other charges or sums due under this Lease, Lessor may (but shall
      not be required to) use, apply or retain all or any part of the security
      deposit for the payment of any Rent or other charges or sums due under
      this Lease or any sum in default, or for the payment of any amount which
      Lessor may spend or become obligated to spend by reason of Lessee's
      default, or to compensate Lessor for any other loss, damage, cost or
      expense (including reasonable attorneys' fees) which Lessor may suffer or
      incur by reason of Lessee's default. If any portion of said security
      deposit is so used or applied, Lessee shall, within five (5) days after
      written demand therefor, deposit a certified or cashier's check with
      Lessor in an amount sufficient to restore the security deposit to its
      original amount and Lessee's failure to do so shall be a default under
      this Lease. Lessor shall not be required to keep the security deposit
      separate from its general funds and Lessee shall not be entitled to
      interest on such deposit. If Lessee shall fully and faithfully perform
      every provision of this Lease to be performed by it, the security deposit
      or any balance thereof after deduction hereunder by Lessor shall be
      returned to Lessee (or, at Lessor's option, to the last assignee of
      Lessee's interest hereunder) within thirty (30) days

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<PAGE>

      following expiration of the Lease Term; provided, that in the event this
      Lease shall be terminated upon the default of the Lessee, the security
      deposit shall be retained by Lessor and all of Lessee's interest therein
      shall terminate and the security deposit will be applied against the
      damages suffered by Lessor by reason of the Lessee's default. In the event
      of termination of Lessor's interest in this Lease, Lessor shall transfer
      said deposit to Lessor's successor in interest.

5.    USE. Lessee shall use and occupy the Premises for the purposes of office,
      laboratory, process development and related support services (including
      light manufacturing and storage related to the foregoing) and for no other
      purposes, without prior written consent of Lessor (which consent shall not
      be unreasonably withheld or delayed), and shall comply with all
      governmental laws, ordinances, regulations, orders and directives and
      insurance requirements applicable to Lessee's use of the Premises. Lessee
      shall not occupy or use or permit any portion of the Premises to be
      occupied or used in such a manner or for any purpose which would increase
      the cost of insurance coverage upon the Premises, the building or the
      contents thereof.

6.    RULES AND REGULATIONS. Lessee agrees to comply with any Rules and
      Regulations attached hereto, any recorded Covenants, Conditions and
      Restrictions affecting the Project, as well as such other reasonable rules
      and regulations as may from time to time be adopted by Lessor for the
      management, good order and safety of common areas, the building and its
      Lessee(s), provided, however, such rules, regulations, covenants,
      conditions or restrictions do not prohibit or prevent Lessee's permitted
      use of the Premises. Lessee shall be responsible for the compliance with
      such rules and regulations by its employees, agents and invitees. Lessor's
      failure to enforce any of such rules and regulations against Lessee or any
      other Lessee shall not be deemed to be a waiver of same, provided,
      however, Lessor agrees to enforce the rules and regulations equitably
      among all tenants of the Project.

7.    MAINTENANCE. Lessee agrees by taking possession that the Premises are in
      tenantable and good condition. Lessee shall at its expense and at all
      times keep, maintain, repair and replace the Premises, including but not
      limited to storefronts, exterior doors and windows, Lessee division walls
      and mechanical, electrical, sprinkler and other utility systems, together
      with connections to utility distribution systems, in good condition,
      repair and order and in accordance with applicable laws, ordinances,
      rules, regulations and requirements of government authorities and
      insurance rating bureaus. Lessee agrees to maintain a preventative
      maintenance contract, or to establish a preventative maintenance program,
      providing for the regular inspection and maintenance of the heating and
      air conditioning systems with a licensed mechanical contractor and
      containing terms and specifications acceptable to Lessor. Lessee shall
      further keep the Premises and adjoining common areas in a neat, clean,
      safe and sanitary condition; protect water, drain, gas and other pipes to
      prevent freezing or clogging and repair all leaks and damage caused
      thereby; replace all glass and panels in windows and doors of the Premises
      which become cracked, broken or damaged; and remove ice and snow from
      entries and common areas immediately adjacent to the Premises. After
      reasonable notice from Lessee, Lessor shall repair the roof, exterior
      walls (excluding storefronts, doors and windows), foundations and common
      areas and facilities, if any, and the cost thereof shall be shared as
      provided in Section 9 hereof.

8.    UTILITIES AND FEES. Lessee agrees to pay promptly when due all charges for
      light, heat, water, sewer, garbage, fire protection and other utilities
      and services to the Premises, and all license fees and other governmental
      charges levied on Lessee's property and the operation of Lessee's business
      on the Premises. Lessor shall not be liable for any injury or damages
      suffered as a result of the interruption of utilities or services by fire,
      or other casualty, strike, riot, vandalism, the making of necessary
      repairs or improvements, or other causes beyond Lessor's reasonable
      control.

9.    MONTHLY OPERATING EXPENSE ADJUSTMENTS. Lessee shall pay as additional
      monthly rent its prorata share of all expenses incurred by Lessor for
      operation of the Project during the term or any extension hereof, as
      follows:

      A.    Real Estate taxes and assessments, together with any assessments
            levied by the Owner's Association, if any.

                                       2
<PAGE>

      B.    Usual and necessary costs of operation, management, maintenance and
            repair (including replacement) as determined by standard accounting
            practice, including without limitation, all utilities and services
            not metered or charged directly to Lessee, insurance (including, but
            not limited to the insurance provided for under Paragraph 16 C
            below), painting, upkeep and repair of building exterior, roofing,
            parking, landscaping, and all common areas and facilities. If any
            portion of the Property, or any system or equipment is replaced by
            Lessor, and if the useful life of such replaced item extends beyond
            the term of this Lease (as such term may be extended by the exercise
            of any options), the cost of such replacement will be amortized over
            its useful life and Lessee will be responsible only for that portion
            of the cost which is applicable to the lease term (as extended).

      C.    A Management fee equal to four and one quarter percent (4 1/4%) of
            Lessee's monthly rent, including Base Rent and any Additional Rent.
            Lessor shall from time to time estimate and provide notice to Lessee
            of its monthly expense based upon existing or expected costs. Such
            monthly estimated amount shall be paid by Lessee on or before the
            first day of each month. Lessor, annually or upon termination
            hereof, shall compute Lessee's actual expenses. Any overpayment
            shall be applied as a credit to Lessee against future expense
            payments.

            Any deficiency shall be paid to Lessor by Lessee within fifteen (15)
            days after the date of Lessor's statement. Lessor's records showing
            expenditures made for such expenses shall be available for Lessee's
            inspection at any reasonable time.

            The determination of actual costs and estimated costs allocable to
            the Premises shall be made by Lessor. Lessor or its agent shall keep
            records showing all expenditures made for the items enumerated
            above, which records shall be available for inspection and review by
            Lessee. The Lessee shall have the right, at reasonable times and
            upon reasonable prior notice to the Lessor to review the Lessor's
            records relating to the actual costs and estimated costs allocable
            to the Premises for a particular Lease Year, which review must be
            conducted within six (6) months after Lessee's receipt of the
            statement of actual costs allocable to the Premises for that
            particular Lease Year. Lessor shall repay Lessee any overstated
            amount(s) within thirty (30) days following Lessor's and Lessee's
            mutual agreement that such overpayment by Lessee did occur. If such
            review is not conducted within such six (6) month period, then the
            matters set forth in the statement of actual costs allocable to the
            Premises for that particular Lease Year shall be deemed conclusive.
            The Lessee shall pay the costs and expenses of such review unless
            such review reveals that the Lessor has overstated the Operating
            Expenses for the Lease Year in question by an amount equal to 5% or
            more for that particular Lease Year in which event the Lessor shall
            pay up to $1,000 in payment of the actual costs incurred by Lessee
            in the performance of such review.

10.   LESSOR'S RESERVATIONS. Lessor reserves the right without liability to
      Lessee: (a) at reasonable times and with notice that is reasonable under
      the circumstances (except in the case of an emergency when no notice is
      required) to inspect the Premises, and to show them to prospective Lessees
      within the last twelve (12) months of the Lease Term or earlier
      termination thereof, partners or lenders and if they are vacated, to
      prepare them for re-occupancy; (b) to retain at all times and to use in
      appropriate instances keys to doors within and into the Premises; (c) to
      make repairs, alterations, additions or improvements, whether structural
      or otherwise, in or about the building, and for such purposes to enter
      upon the Premises and during the continuance of any work, to close common
      areas and to interrupt or temporarily suspend building services and
      facilities, all without affecting any of Lessee's obligations hereunder,
      so long as the Premises are reasonably accessible; and (d) generally to
      perform any act relating to the safety, protection and preservation of the
      Premises or building.

11.   POSSESSION. If Lessor does not deliver possession of the Premises at the
      Commencement Date of the term of this Lease, then, unless such delay is
      caused by Lessee, Lessee may give Lessor written notice of its intention
      to cancel this Lease if possession is not delivered within ninety (90)
      days after receipt of such notice by Lessor. Lessor shall not be liable
      for any damages caused by failure to deliver possession of the Premises
      and

                                       3
<PAGE>

      Lessee shall not be liable for any rent for such time and until such time
      as Lessor delivers possession. A delay of possession shall not extend the
      termination date. Notwithstanding the above, in the event the delay was
      caused by Lessee, then the payment of Rent shall commence on the
      Commencement Date and Lessee shall not have any right to cancel this Lease
      as a result of such delay. If Lessor offers access to the Premises or any
      portion thereof prior to the Commencement Date of the term of this Lease,
      and if Lessee accepts such early access, then both parties shall be bound
      by all of the covenants and terms contained herein during such period.

12.   ASSIGNMENT AND SUBLETTING. Lessee shall not either voluntarily or by
      operation of law assign, transfer, convey or encumber this Lease or any
      interest under it, or sublet its right to occupy or use all or any portion
      of the Premises without Lessor's prior written consent, which consent
      shall not be unreasonably withheld or delayed. Among the criteria to be
      used by Lessor in evaluating a request for assignment or subletting will
      be (i) the proposed use of the Premises; (ii) the anticipated impact, if
      any, on parking; (iii) the financial capacity of the assignee/sublessee to
      perform the obligations under this Lease; (iv) the compatibility of the
      proposed user with the remainder of the tenants and operation of the
      Building. Lessor reserves the right to recapture the Premises or
      applicable portion thereof in lieu of giving its consent by notice given
      to Lessee within twenty (20) days after receipt of Lessee's written
      request for assignment or subletting. Such recapture shall terminate this
      Lease as to the applicable space effective on the prospective date of
      assignment or subletting, which shall be the last day of a calendar month
      and not earlier than sixty (60) days after receipt of Lessee's request
      hereunder. Lessee may condition its request for Lessor's consent to an
      assignment or subletting on Lessor's waiver of its recapture right. In the
      event that Lessor shall not elect to recapture and shall thereafter give
      its consent, Lessee shall pay Lessor a reasonable fee, not to exceed One
      Thousand And No/100 Dollars ($1,000.00) to reimburse Lessor for processing
      costs incurred in connection with such consent. Lessor's consent shall not
      release or discharge Lessee from future liability under this Lease and
      shall not waive Lessor's right to consent to any future assignment or
      sublease. Any assignment or subletting without Lessor's consent shall be
      void and shall, at Lessor's option, constitute a default under this Lease.
      A transfer by the present majority shareholders of ownership or control of
      a majority of the voting stock of a corporate Lessee, or the change in
      form of entity of the Lessee, shall be deemed an assignment.

      The Lessee shall not assign its interest in or under this Lease for
      security purposes, nor shall the Lessee grant any security interest, lien
      or encumbrance against its interest in this Lease or in or to any property
      in or affixed to the Premises without the prior written consent of the
      Lessor, which consent shall be granted, withheld or conditioned in
      Lessor's sole discretion. In no event shall the Lessee grant, or allow to
      exist, any security interest in, or lien or encumbrance against the fee
      title to the Premises, the building in which the Premises is located or
      the real property on which the building is located.

13.   ALTERATIONS. Lessee shall lease the Premises in its "as is" broomswept
      clean condition, as delivered to Lessee by Lessor. After obtaining the
      prior written consent of Lessor, Lessee may make minor alterations,
      additions and improvements in said Premises (so long as such alterations,
      additions or improvements are not structural in nature and not visible
      from the exterior of the Premises) at its sole cost and expense. Lessee
      agrees to save Lessor harmless from any damage, loss, or expense arising
      therefrom and to comply with all laws, ordinances, rules and regulations.
      Upon termination of this Lease, all alterations, additions and
      improvements made in, to or on the Premises (including without limitation
      all electrical, lighting, plumbing, heating, air conditioning, and
      communications equipment and systems, doors, windows, partitions, drapery,
      carpeting, shelving, counters, and physically attached fixtures, except
      trade fixtures, unless otherwise excluded by written agreement annexed
      hereto), shall remain upon and be surrendered as a part of the Premises;
      provided however, upon Lessor's request, Lessee shall remove its trade
      fixtures and those items excluded by written agreement, and those
      additions, alterations, or improvements as may be specified by Lessor, and
      repair and restore the Premises to is original condition at Lessee's sole
      cost and expense prior to expiration of the Term. Lessee may accompany its
      request for consent with an additional request for a determination by
      Lessor of its requirements with regard to the disposition of such
      improvements at the expiration of the Lease. Lessor will respond to such
      request along with it response to the request for consent.

                                       4
<PAGE>

14.   LIENS. Lessee shall keep the Premises free from any liens arising out of
      any work performed, materials furnished, equipment supplied, or
      obligations incurred by or on behalf of Lessee. No work performed,
      material furnished, equipment supplied or obligations incurred by or on
      behalf of Lessee shall be deemed to be for the immediate use and benefit
      of Lessor so that no mechanic's lien or other lien shall be allowed
      against Lessor's estate in the premises. Lessee shall provide, at Lessee's
      own cost, waivers of lien signed by any party (including the Lessee) who
      performs work, furnishes materials, or supplies equipment to the Premises.
      For any single project, the cost of which will exceed Two Hundred Fifty
      Thousand and No/100 dollars ($250,000.00), Lessor may require, at Lessee's
      sole cost and expense, a lien release and completion bond in an amount
      equal to either the actual contract price or one and one-half times the
      estimated cost of any improvements, additions or alterations in the
      Premises which Lessee desires to make, to insure Lessor against any
      liability for lien and to insure completion of the work.

15.   SIGNS. All signs or symbols placed by Lessee in the windows and doors of
      the Premises, or upon any exterior part of the building, shall be subject
      to Lessor's prior written approval. Prior to termination of this Lease,
      Lessee will remove all signs placed by it upon the Premises, and will
      repair any damages caused by such removal.

16.   INSURANCE.

      A.    Lessee shall pay for and maintain, during the entire Lease Term, the
            following policies of insurance:

            (i)   Commercial general liability insurance, including products,
                  completed operations coverage and auto liability insurance
                  covering Lessee's operations and the Premises with limits of
                  not less than $2,000,000 combined single limit for death,
                  personal injury and property damage per occurrence, including
                  Lessor as an additional insured. Such policies shall be
                  endorsed to provide contractual liability insurance covering
                  all liability assumed by Lessee under the provisions of this
                  Lease and a copy of said endorsement will be delivered to
                  Lessor prior to commencement of the Term.

            (ii)  Special cause of loss or "all risk" perils and sprinkler
                  leakage property insurance upon all building improvements and
                  alterations on the Premises for which Lessee is responsible
                  and upon Lessee's property in the amount of one hundred
                  percent (100%) full replacement cost. The policy shall include
                  Lessor and Lessor's mortgagee, if any, as additional insureds,
                  as their interests may appear, with a loss payable clause in
                  favor of Lessor and Lessor's mortgagee to the extent of their
                  interest in the property.

        B.     Each policy provided by Lessee shall expressly provide that it
               shall not be subject to cancellation or material change without
               at least thirty (30) days prior written notice to the Lessor.
               Lessee shall furnish Lessor, prior to commencement of the Term,
               with insurance certificates naming Lessor as additional insured
               and, upon request, copies of such policies required to be
               maintained hereunder.

        C.     Lessor shall maintain property insurance during the entire Lease
               Term in the amount of one hundred percent (100%) full replacement
               value of the Building and Lessor's improvements. Lessors coverage
               may include the perils of Special cause of loss ("all risk") and
               earthquake.

17.   INDEMNITY AGAINST LIABILITY FOR LOSS OR DAMAGE

      A.    Lessee assumes all liability for and shall indemnify, hold harmless
            and defend Lessor from and against all loss, damage or expense which
            the Lessor may sustain or incur, and against any and all claims,
            demands, suits and actions whatsoever, including expense of
            investigation and litigation, on account of injury to or death of
            persons, including without limitation employees of Lessor, employees
            of Lessee or its affiliated companies or on account of damage to or

                                       5
<PAGE>

            destruction of property, including without limitation property owned
            by and property in the care, custody or control of Lessor during the
            Term, due to or arising in any manner from:

            (i)   The acts or negligence of Lessee or any contractor,
                  subcontractor, or agent of Lessee or their respective
                  employees;

            (ii)  The condition, use or operation of the Premises and/or
                  materials or substances used by Lessee or any of its
                  contractors, subcontractors or agents of Lessee or by their
                  respective employees, regardless of whether or not furnished
                  by Lessor under this Lease or otherwise;

            (iii) Any damage or injury to persons or property arising out of
                  Lessee's breach or this Lease, including, but not limited to,
                  obligations of Lessee under Section 7, Maintenance.

      B.    Lessor shall have no liability to Lessee as a result of loss or
            damage to Lessee's property or for death or bodily injury caused by
            the acts or omissions of other tenants in the project or by third
            parties (including criminal acts).

      C.    Lessee shall not be obligated to indemnify Lessor for the portion of
            any claim or liability caused by or arising from the act, or
            negligence of Lessor.

      D.    Lessee, its agents, trustees, officers, employees, contractors and
            invitees, shall not be liable to Lessor or its agents, employees,
            contractors or invitees or to any third party for any damage to
            person or the Premises caused by or arising from or in connection
            with any act, or negligence of Lessor. Lessor agrees to indemnify,
            hold harmless and defend Lessee, its agents, trustees, officers,
            employees, contractors and invitees from and against any and all
            liability claims, causes of action, damages, costs and expenses
            (including, without limitation, attorney's fees) arising from or in
            connection with any act, or neglect of Lessor or its agents,
            employees, contractors or invitees; and from any breach or default
            under this Lease by Lessor.

      E.    It is mutually understood and agreed that the assumption of
            liabilities and indemnification provided for in this Section 17
            shall survive any termination of this Lease.

18.   DAMAGE OR DESTRUCTION. If any of the Premises, or a substantial part of
      the building in which the Premises are located, shall be damaged or
      destroyed by fire or other insured casualty to the extent of more than 40%
      of its replacement cost, and repair of the damage can not be completed
      within one hundred eighty (180) days, following receipt by Lessor of
      actual notice of such damage or destruction Lessor shall have the option
      either (a) to repair or rebuild within a reasonable time utilizing the
      insurance proceeds to effect such repair, or (b) not to repair or rebuild,
      and to cancel this Lease on thirty (30) days notice. If Lessor fails to
      give Lessee written notice of its election within thirty (30) days from
      the date of damage, or if the restoration of the Premises cannot be
      completed within one hundred eighty (180) days from date of notice, Lessee
      may cancel this Lease at its option on thirty (30) days notice. During the
      period of untenantability, rent shall abate in the same ratio as the
      portion of the Premises rendered untenantable bears to the whole of the
      Premises; provided that if the damage is due to the fault or neglect of
      Lessee, there shall be no abatement of rent.

      If the Premises or the building in which the Premises are located shall be
      damaged or destroyed by fire or other insured casualty, and repair of the
      damage can be completed within one hundred eighty (180) days, Lessor shall
      repair or rebuild within a reasonable time utilizing the insurance
      proceeds to effect such repair.

      If a substantial part of the Premises or the building in which the
      Premises are located shall be damaged or destroyed by an uninsured
      casualty Lessor shall have the option either (a) to repair or rebuild
      within a reasonable time, or (b) not to repair or rebuild, and to cancel
      this Lease on thirty (30) days notice. In the event of cancellation by
      Lessor as a result of an uninsured casualty, Lessee shall have the right,
      within five (5) days following Lessor's notice of cancellation, to
      override such cancellation by agreeing to

                                       6
<PAGE>

      repair the damage at Lessee's sole cost and expense. In such event, the
      Lessee shall repair or rebuild within a reasonable time following the
      damage or destruction.

19.   EMINENT DOMAIN. If the whole of the Premises shall be taken by any public
      authority under the power of eminent domain, or purchased by the condemnor
      in lieu thereof, then the term of this Lease shall cease as of the date
      possession is taken by such public authority. If only part of the Premises
      shall be so taken, the Lease shall terminate only as to the portion taken,
      and shall continue in full force and effect as to the remainder of said
      Premises, and the monthly rent shall be reduced proportionately; provided,
      however, if the remainder of the Premises cannot be made tenantable for
      the purposes for which Lessee has been using the Premises or if more than
      twenty-five percent (25%) of the rentable square footage of the Premises
      shall be so taken, then either party, by written notice to the other,
      given at least thirty (30) days prior to the date that possession must be
      surrendered to the public authority, may terminate this Lease effective as
      of such surrender of possession. If any part of the building other than
      the Premises shall be so taken so as to render in Lessor's opinion the
      termination of this Lease beneficial to the remaining portion of the
      building, Lessor shall have the right within sixty (60) days of said
      taking to terminate this Lease upon thirty (30) days written notice to
      Lessee. In the event of any taking, whether whole or partial, Lessor shall
      be entitled to all awards, settlements, or compensation which may be given
      for the land and buildings. Lessee shall have no claim against Lessor for
      the value of any unexpired term of this Lease. Lessee shall have the right
      to seek an independent and separate award from the condemning authority so
      long as such award does not diminish the amount of the award payable to
      Lessor.

20.   INSOLVENCY. If Lessee shall be declared insolvent or bankrupt, or if
      Lessee's leasehold interest herein shall be levied upon or seized under
      writ of any court of law, or if a trustee, receiver or assignee be
      appointed for the property of Lessee, whether under operation of State or
      Federal statutes, then Lessor may, at its option, immediately, without
      notice (notice being expressly waived), terminate this Lease and take
      possession of said Premises.

21.   DEFAULT AND RE-ENTRY. If Lessee fails to keep or perform any of the
      covenants and agreements herein contained, then the same shall constitute
      a breach hereof, and if Lessee has not remedied such breach within five
      (5) days after any payment is due if the breach is non-payment of rent or
      other charges, or within ten (10) days after written notice thereof from
      Lessor in the event of the breach of any other covenant, except that if
      the breach cannot reasonably be cured within such ten (10) day period,
      then if Lessee fails to commence to cure within such ten (10) day period
      and thereafter, diligently prosecute such cure to completion, then Lessor
      may, at its option, without further notice or demand:

      A.    Cure such breach for the account and at the expense of Lessee
            (including entry upon the Premises to make repairs on behalf of the
            Lessee where Lessee has failed to make such repairs as required
            under this Lease) and such expense shall be deemed additional rent
            due on the first of the following month; or

      B.    Re-enter the Premises, remove all persons therefrom, take possession
            of the Premises and remove all personal property therein at Lessee's
            risk and expense and (1) terminate this Lease, or (2) without
            terminating the Lease or in any way affecting the rights and
            remedies of Lessor or the obligations of Lessee, re-let the whole or
            any part of the Premises as agent for Lessee, upon such terms and
            conditions as Lessor may deem advisable. In either event, any moneys
            received from Lessee and any deposit or other amounts held by Lessor
            may first be applied by Lessor to any damages suffered by Lessor as
            a result of such default, including without limitation, costs and
            expenses incurred on re-entry and re-letting, any unamortized tenant
            improvements and commissions, cleaning, necessary repairs,
            restoration and alteration, and any commissions incurred on
            re-letting, and the balance of such amounts may be applied toward
            payment of other sums due to Lessor hereunder. In the event the
            Premises are re-let for Lessee's account, Lessee shall pay to Lessor
            monthly any deficiency; however, Lessor shall not be required to pay
            any excess to Lessee. Upon termination of this Lease or of Lessee's
            right to possession, Lessor has the right to recover from Lessee:
            (1) The worth of the unpaid rent that had been earned at the time of
            such

                                       7
<PAGE>

            termination; (2) The worth of the amount of the unpaid rent that
            would have been earned after the date of such termination; and (3)
            Any other amount, including court, reasonable attorney and
            collection costs, necessary to compensate Lessor. "The Worth," as
            used in Section (1) is to be calculated allowing interest at 18% per
            year (or, if applicable, at such lower rate as may represent the
            highest legal limit allowed in the State of Washington). "The worth"
            as used for Section (2) is to be computed by discounting the amount
            at the discount rate of the Federal Reserve Bank of San Francisco at
            the time of termination. The above remedies of Lessor are cumulative
            and in addition to any other remedies now or hereafter allowed by
            law or elsewhere provided for in this Lease. Notwithstanding
            anything to the contrary in this Section 21, Lessee does not waive
            any right it may have to require Lessor to mitigate its damages.

22.   REMOVAL OF PROPERTY. Any personal property (excluding intellectual
      property) of Lessee removed by Lessor in accordance with Section 21 above
      may be stored, sold, or disposed of by Lessor without any additional
      notice to Lessee at the sole risk and expense of Lessee and without any
      further responsibility of Lessor. Proceeds therefrom may be applied by
      Lessor upon any indebtedness due from Lessee to Lessor. Lessee waives all
      claims for damages that may be caused by Lessor re-entering the Premises
      and removing or disposing of said property as herein provided.

23.   COSTS AND ATTORNEYS' FEES. In the event either party shall commence legal
      action to enforce any provision of this Lease, the court shall award to
      the prevailing party all reasonable attorneys' fees and all costs incurred
      in connection therewith, including fees and costs on appeal. Any action
      relating to this Lease shall be brought in the County in which the
      Premises are located or, at Lessor's election, in King County, Washington.

24.   SUBROGATION WAIVER. Lessor and Lessee each herewith and hereby release and
      relieve the other and waive its entire right of recovery against the other
      for loss or damage arising out of or incident to the perils of fire,
      explosion or any other perils described in the "all risk" insurance and
      the events covered under the property insurance coverages required under
      this Lease, whether due to the negligence of either party, their agents,
      employees or otherwise. Each party shall obtain from its respective
      insurer under each insurance policy that it maintains a waiver of all
      rights of subrogation which the insurer may have against the other party
      for claims that are released under this Section 24.

25.   HOLDING OVER. If Lessee, with the express consent of Lessor, shall hold
      over after the expiration of the term of this Lease, Lessee shall remain
      bound by all the covenants and agreements herein, except that (a) the
      tenancy shall be from month-to-month and (b) the monthly rent to be paid
      by Lessee shall be determined by multiplying the monthly rent in effect
      immediately preceding such expiration times 150%. If Lessee holds
      possession of the Demised Premises after the expiration of the Lease
      without the express written consent of Lessor, Lessee shall remain bound
      by all the covenants and agreements herein, except that (a) the tenancy
      shall be from month-to-month and (b) the monthly rent to be paid by Lessee
      shall be the greater of twice the Monthly Minimum Rent in effect
      immediately preceding such expiration or the total loss to Lessor as a
      result of Lessee's holdover, if, effective during the term of such
      holdover, Lessor has leased all or part of the Premises to other
      Lessee(s). Any such tenancy may be terminated with twenty (20) days prior
      notice as provided by Washington State law.

      In the event of any unauthorized holding over, Lessee shall also indemnify
      and hold Lessor harmless from and against all liability, losses, claims,
      causes of action, damages, costs and expenses (including without
      limitation attorney fees) resulting from Lessee's failure to surrender the
      Premises, including without limitation claims made by succeeding Lessees
      resulting from Lessee's failure to surrender the Premises.

      Lessee's obligations under this Section 25 shall survive the expiration or
      termination of this Lease.

26.   SUBORDINATION AND ATTORNMENT; MORTGAGE PROTECTION.

      A.    SUBORDINATION-NOTICE TO MORTGAGEE. At the request of Lessor, Lessee
            shall promptly execute, acknowledge and deliver, all instruments
            which may be

                                       8
<PAGE>

            required to subordinate this Lease to any existing or future
            mortgages, deeds of trust and/or other security documents on or
            encumbering the Premises or on the leasehold interest held by
            Lessor, and to any extensions, renewals, or replacements thereof,
            provided that the mortgagee or beneficiary, as the case may be,
            shall agree to recognize this Lease in the event of foreclosure if
            Lessee is not in material default at such time by providing a
            subordination and non-disturbance agreement in a commercially
            reasonable form.

      B.    LESSEE'S CERTIFICATE. Lessee shall at any time, and from time to
            time, within fourteen (14) days after written notice from Lessor,
            execute, acknowledge and deliver to Lessor a statement in writing
            (a) certifying that this Lease is unmodified and in full force and
            effect (or, if modified, stating the nature of such modification and
            certifying that this Lease as so modified is in full force and
            effect), and the date to which the rental and other charges are paid
            in advance, if any; and (b) acknowledging that there are not, to
            Lessee's knowledge, any uncured defaults on the part of the Lessor
            or Lessee hereunder, or specifying such defaults if any are claimed;
            and (c) setting forth the date of commencement of rents and
            expiration of the Lease Term hereof; and, (d) such other information
            as the Lessor shall reasonably require. Any such statement may be
            relied upon by any prospective purchaser or encumbrancer of all or
            any portion of the Premises of which the Premises are a part.

      C.    MORTGAGEE PROTECTION CLAUSE. Lessee agrees to notify any mortgagee
            and/or trust deed holders, by registered mail, with a copy of any
            notice of default served upon the Lessor, provided that prior to
            such notice Lessee has been notified in writing (by way of Notice of
            Assignment of Rents and Lease, or otherwise) of the addresses of
            such mortgagees and/or trust deed holders. Lessee further agrees
            that if Lessor shall have failed to cure such default, then the
            mortgagees and/or trust deed holders have thirty (30) days within
            which to cure such default or if such default cannot be cured within
            that time, then such additional times as may be necessary if within
            such thirty (30) days any mortgagee and/or trust deed holder has
            commenced and is diligently pursuing the remedies necessary to cure
            such default (including but not limited to commencement of
            foreclosure proceedings if necessary to affect such cure), in which
            event this Lease shall not be terminated if such remedies are being
            so diligently pursued.

27.   SURRENDER OF POSSESSION. Lessee shall, prior to the termination of this
      Lease or of Lessee's right to possession, remove from the Premises all
      personal property which Lessee is entitled to remove and those
      alterations, additions, improvements or signs which may be required by
      Lessor to be removed, pursuant to Sections 13 and 15 above, and shall
      repair or pay for all damage to the Premises caused by such removal. All
      such property remaining and every interest of Lessee in the same shall be
      conclusively presumed to have been conveyed by Lessee to Lessor under this
      Lease as a bill of sale, without compensation, allowance, or credit to
      Lessee. Lessee shall upon termination of this Lease or of Lessee's right
      of possession, deliver all keys to Lessor and peacefully quit and
      surrender the Premises without notice, neat and clean, and in as good
      condition as when Lessee took possession, except for reasonable wear and
      tear as determined by Lessor and except for damage by casualty or
      condemnation.

28.   LATE PAYMENT AND INTEREST. If any amount due from Lessee is not received
      in the office of Lessor on or before the fifth (5th) day following the
      date upon which such amount is due and payable, a late charge of five
      percent (5%) of said amount shall become immediately due and payable,
      which late charge Lessor and Lessee agree represents a fair and reasonable
      estimate of the processing and accounting costs that Lessor will incur by
      reason of such late payment. All past due amounts owing to Lessor under
      this Lease, including rent, shall be assessed interest at an annual
      percentage rate of eighteen percent (18%) from the date due until paid.

29.   NOTICE. Any notice, communication or remittance required or permitted by
      this Lease by either party to the other shall be deemed given, served or
      delivered, in writing, delivered personally or by courier or by telephonic
      facsimile transmission with automatic confirmation, addressed to the
      Lessor at the address specified for the

                                       9
<PAGE>

      payment of rent under paragraph 3 of this Lease or to Lessee at the
      Premises or to such other address as either party may designate to the
      other in writing from time to time.

30.   NO WAIVER OF COVENANTS. Time is of the essence of this Lease. Any waiver
      by either party of any breach hereof by the other shall not be considered
      a waiver of any future similar or other breach.

31.   ENTIRE AGREEMENT. It is expressly understood and agreed by Lessor and
      Lessee that there are no promises, agreements, conditions, understandings,
      inducements, warranties, or representations, oral or written, express or
      implied, between them, other than as herein set forth and that this Lease
      shall not be modified in any manner except by an instrument in writing
      executed by the parties.

32.   BINDING ON HEIRS, SUCCESSORS AND ASSIGNS. The covenants and agreements of
      this Lease shall be binding upon the heirs, executors, administrators,
      successors and assigns of both parties hereto, except as hereinabove
      provided.

33.   LESSOR'S ASSIGNMENT. It is fully understood that Lessor shall have the
      full right to assign this Lease, without any notice to Lessee, thereby
      relieving Lessor from all and any liabilities; provided however, that the
      assignee assumes all Lessor's responsibilities as set forth in this Lease.

34.   ENVIRONMENTAL. See Rider One attached and incorporated into this Lease by
      this reference.

35.   BROKERS; AGENCY DISCLOSURE; BROKERAGE RELATIONSHIPS.

                     [Intentionally deleted.]

36.   FORCE MAJEURE. Lessor shall have no liability to Lessee on account of the
      following acts of "force majeure," which shall include (a) the inability
      of Lessor to fulfill, or delay in fulfilling, any of Lessor's obligations
      under this Lease by reason of strike, lockout, other labor trouble,
      dispute or disturbance; (b) governmental regulation, moratorium, action,
      inaction, preemption or priorities or other controls, including delays in
      receipt of permits; (c) shortages of fuel, supplies or labor; (d) any
      failure or defect in the supply, quantity or character of electricity or
      water furnished to the Premises by reason of any requirement, act or
      omission of the public utility or others furnishing the Building with
      electricity or water; or (e) for any other reason, whether similar or
      dissimilar to the above, or for act of God, beyond Lessor's reasonable
      control. If this Lease specifies a time period for performance of an
      obligation of Lessor, that time period shall be extended by the period of
      any delay in Lessor's performance caused by any of the events of force
      majeure described herein.

37.   LIMITATION OF LIABILITY. The recourse of Lessee to recover any claim
      against Lessor arising under this Lease shall be limited to Lessor's
      interest in the Building and to the rents, issues and profits from the
      Building. Lessee waives any and all recourse for any such liability
      against Lessor's members, partners, shareholders, trustees or
      beneficiaries, or any property or assets of Lessor other than the
      Building.

38.   OPTION TO EXTEND. Lessor hereby grants to Lessee two successive options to
      extend this Lease for additional terms of five (5) years each commencing
      on the first day after the Expiration Date of the previous term. Lessee
      must exercise the option to extend, if at all, by giving Lessor written
      notice of such exercise not less than twelve (12) months prior to the
      expiration date of the then current term. Upon the exercise of the option
      to extend, the term of this Lease shall be extended through the expiration
      date of the Renewal Term on the same terms and conditions as contained
      herein, except that there shall be no option to extend the term of this
      Lease beyond the Second Renewal Term, and the Base Monthly Rent during the
      Renewal Terms shall be determined pursuant to this Section.

      Base Monthly Rent for each Renewal Term shall be the greater of (a) the
      Base Monthly Rent scheduled for the final month of the preceding term (the
      initial term or the First Renewal Term, as the case may be), or (b) the
      fair market base rental value of the Premises.

                                       10
<PAGE>

      Lessor and Lessee agree to be reasonable in their negotiation of rent for
      the option periods. Lessor and Lessee shall have thirty (30) days after
      Lessee provides Lessor of its notice to exercise its Option to Renew to
      set the rent for the option period(s). If Lessor and Lessee are unable to
      establish the rent for the option period(s) within the thirty (30) day
      period then Lessor and Lessee shall each appoint an appraiser with not
      less than ten (10) years experience in real estate appraisal in the
      Bellevue real estate market, to set the rent for the option period(s). If
      the rents proposed by each appraiser are within ten (10%) percent of each
      other, then the rent for the option period(s) shall be the average of the
      two rents. If the rents proposed by each appraiser are greater than ten
      (10%) percent from each other then the two appraisers will select a third
      appraiser who shall also have at least (10) years real estate appraisal
      experience in the Bellevue real estate market, to set the rent for the
      option period(s). The rent established by the third appraiser will be
      binding on Lessor and Lessee and will be no less than the rent proposed by
      Lessee and no higher than the rent proposed by Lessor. The total cost of
      all of the appraiser's fees will be the responsibility of the party whose
      proposed rental rate is farthest from that of the final rental rate
      established by the appraisers.

39.   RIGHT OF FIRST OPPORTUNITY TO PURCHASE.

      39.1 GRANT OF RIGHTS. In the event Lessor intends to sell or to make the
      Building in which the Premises are located available for purchase to
      unrelated third parties, and provided Lessor is not selling the Building
      as part of a portfolio of buildings, Lessor shall give Lessee written
      notice of this intention and of the intended offering sale price of the
      Premises ("Lessor's Notice"). Lessor will offer the sales price to Lessee
      in good faith. In the event Lessee desires to purchase the Premises at the
      offering sale price indicated by Lessor, Lessee shall give to Lessor a
      written notice of such desire ("Lessee's Notice") within seven days of
      receipt of the Lessor's Notice. If the Lessee's Notice is not timely given
      by Lessee, Lessee shall have no further rights under this Section 39. In
      the event Lessee's Notice is timely given by Lessee, then Lessor and
      Lessee shall negotiate during the remainder of the 30 day period following
      the giving of Lessor's Notice in good faith to attempt to execute a
      definitive purchase and sale agreement whereby Lessor would sell to Lessee
      and Lessee would purchase from Lessor the Premises at the price stated in
      Lessor's Notice. During the 30 day period any offer of the property
      publicly or privately will be subject to Lessee's rights hereunder.
      Neither party shall have any obligation to execute a purchase and sale
      agreement not acceptable to such party, in its sole and absolute
      discretion. In the event the parties fail to execute a mutually agreeable
      purchase and sale agreement within the 30 day period allowed, or in the
      event such a purchase and sale agreement is executed but is subsequently
      terminated without consummation of the sale, Lessee shall have no further
      rights under this Section 39. In no event shall Lessee have the right to
      assert any right to purchase the Building once Lessor has executed a
      contract for the sale of the Premises to a third party as otherwise
      permitted under this Section 39, even if the price under such contract, as
      the same may be amended, is less than the price stated in Lessor's Notice.
      It is expressly agreed that any price set forth in Lessor's Notice given
      to Lessee, and any transaction whereby the Building is sold to Lessee,
      will be on the basis that Lessor shall pay no real estate commission on
      account of such sale to any broker representing Lessee. It is further
      acknowledged that Lessor may subsequently offer the Premises to third
      parties at a price less than, equal to or greater than the price set forth
      in the Lessor's Notice.

      39.2 LIMITATION OF RIGHTS. The notification and negotiation rights allowed
      to Lessee pursuant to Section 39.1 are allowed on a "one time" basis only,
      and except as otherwise provided in Section 39.1 above, Lessor shall have
      no obligation to re-notify Lessee of any changes in its sales intentions
      or offering price, nor to re-notify Lessee of subsequent sales efforts if
      Lessor does not sell the Building following the Lessor's Notice.

      39.3 EXCLUSIONS. The rights of Lessee under this Section 39 are limited to
      notification and negotiation in anticipation of Lessor offering the
      Building to purchase by unrelated third parties. There shall be no
      notification or negotiation rights of Lessee in any other case whatsoever,
      including but not limited to cases of (a) a conveyance by Lessor to an
      affiliated party and any conveyance in connection with a merger or other
      corporate transaction, (b) a conveyance by Lessor to a lender who then
      holds a lien on the

                                       11
<PAGE>

      Premises, (c) a conveyance in connection with a foreclosure sale, (d) a
      conveyance or taking in connection with a condemnation, (e) a conveyance
      which is part of a financing transaction (for example, a sale and master
      lease back), (f) a conveyance by any subsequent owner of the Building
      other than the Lessor originally named herein, or (g) a sale or offering
      in which Lessor packages the Building with one or more other properties
      owned by Lessor and/or any affiliate of Lessor for sale as a group, on the
      open market or otherwise. No conveyance of any or all of the ownership
      interests within Lessor (for example, membership interests in the limited
      liability company) shall be deemed a conveyance or sale of the Premises.

      39.4 PERSONAL NATURE OF RIGHTS. Upon any assignment of this Lease or of
      any sublease of all or a part of the Premises, the rights granted to
      Lessee pursuant to Section 39.1 shall terminate. The rights granted to
      Lessee pursuant to Section 39.1 shall also terminate upon the termination
      of this Lease or of Lessee's right of possession.

40.   EXHIBITS. The following exhibits or riders are made a part of this Lease
      and are incorporated herein by reference:

               Rider One - Environmental
               Exhibit A - Premises
               Exhibit B - Rules and Regulations
               Rider Two - Additional Lease Provisions

        LESSOR:                                    LESSEE:

        BENAROYA CAPITAL COMPANY, LLC              ICOS CORPORATION

        /s/ Larry R. Benaroya
        By:  Larry R. Benaroya                     By: /s/ Gary Wilcox
           -----------------------                    -------------------------
        Its:  Manager                              Its: EVP, Operations
            ----------------------                     ------------------------
        Date:  6/12/01                             Date: 6/12/01
            ----------------------                      -----------------------

                                       12
<PAGE>

STATE OF WASHINGTON   ]
                      ] ss.
COUNTY OF KING        ]

      I certify that I know or have satisfactory evidence that Larry R. Benaroya
is the person who appeared before me, a Notary Public in and for the State of
Washington duly commissioned and sworn, and acknowledged that he is the Manager
of BENAROYA CAPITAL COMPANY, LLC, a Washington limited liability company, who
executed the within and foregoing instrument, and acknowledged the instrument to
be the free and voluntary act and deed of said company for the uses and purposes
therein mentioned, and on oath stated that affiant is authorized to execute said
instrument on behalf of said company.

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

                                            /s/ Rebecca A. Bethel
                                            ------------------------------------
                                            Notary Public in and for the
                                            State of Washington
                                            residing at Seattle
                                            Commission expires 11/9/02
                                            Print Name Rebecca A. Bethel

STATE OF WASHINGTON   ]
                      ] ss.
COUNTY OF  Snohomish  ]

        I certify that I know or have satisfactory evidence that Gary Wilcox is
the person who appeared before me, a Notary Public in and for the State of
Washington duly commissioned and sworn, and acknowledged that he/she is the
representative, of ICOS CORPORATION, a Delaware corporation, who executed the
within and foregoing instrument, and acknowledged the 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 affiant is authorized to execute said
instrument on behalf of said corporation.

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

                                            /s/ Lori L. Briseno
                                            ------------------------------------
                                            Notary Public in and for the
                                            State of Washington
                                            residing at Snohomish
                                            Commission expires 4/29/02
                                            Print Name Lori L. Briseno

                                       13
<PAGE>

                                    RIDER ONE
                  EMISSIONS; STORAGE, USE AND DISPOSAL OF WASTE

a.    EMISSIONS. Lessee shall not discharge, emit or permit to be discharged or
      emitted, any liquid, solid or gaseous matter, or any combination thereof,
      into the atmosphere, the ground or any body of water, which does or may
      pollute or contaminate the same, or does or may adversely affect the
      health or safety of persons, or the use or enjoyment of the Premises.
      Lessee may transmit, receive or permit to be transmitted or received, any
      electromagnetic, microwave or other radiation in, on or about the
      Premises, provided, however, that such electromagnetic, microwave or other
      radiation is used in connection with Lessee's Permitted Use of the
      Premises, and that such use complies with all pertinent federal, state,
      and local statutes, rules, regulations, ordinances and orders that such
      use does not interfere with the use of any other tenant or owner within
      Canyon Park.

b.    STORAGE. If, with or without violation of this Lease, Lessee possesses at
      the Premises any matter described in Section A above or any Hazardous
      Substances (as defined below), Lessee shall store the same in appropriate
      leak proof containers and/or areas which comply with all laws and all
      prudent practices.

c.    DISPOSAL OF WASTE. Lessee shall not keep any trash, garbage, waste or
      other refuse on the Premises except in sanitary containers and shall
      regularly and frequently remove same from the Premises. Lessee shall keep
      all such containers in a clean and sanitary condition. Lessee shall
      properly dispose of all sanitary sewage and shall not use the sewage
      system for the disposal of anything except sanitary sewage, nor in excess
      of capacity. Lessee shall not cause any obstruction in the sewage disposal
      system.

d.    COMPLIANCE OF LAW. Notwithstanding any other provision in the Lease to the
      contrary, Lessee shall comply with all Laws in complying with its
      obligations under this Lease, and in particular, Laws relating to the
      storage, use and disposal of Hazardous Substances (as defined below).

e.    INDEMNIFICATION FOR BREACH. Lessee shall defend, indemnify and hold
      Lessor, the Project and the holder of a trust deed or mortgage on the
      Project harmless from any loss, claim, liability or expense, including,
      without limitation, attorneys fees and costs, at trial and/or on appeal
      and review, arising out of or in connection with its failure to observe or
      comply with the provisions of this Rider. This indemnity shall survive the
      expiration or earlier termination of the term of the Lease or the
      termination of Lessee's right of possession and be fully enforceable
      thereafter.

f.    INDEMNIFICATION REGARDING HAZARDOUS SUBSTANCES. In addition to the
      indemnity obligations contained elsewhere herein, Lessee shall indemnify,
      defend and hold harmless Lessor, the Premises, the Project, and the holder
      of a trust deed or mortgage on the Project, from and against all claims,
      losses, damages, monitoring costs, response costs, liabilities, and other
      costs expenses caused by, arising out of, or in connection with, the
      generation, release, handling, storage, discharge, transportation, deposit
      or disposal in, on, under or about the Premises by Lessee or any of
      Lessee's agents of the following (collectively referred to as "Hazardous
      Substances"): hazardous materials, hazardous substances, toxic wastes,
      toxic substances, pollutants, petroleum products, underground tanks, oils,
      pollution, asbestos, PCB's, radioactive materials, or contaminants, as
      those terms are commonly used or as defined by federal, state, and/or
      local law or regulation related to protection of health or the environment
      as any of same may be amended from time to time, and/or by any rules and
      regulations promulgated thereunder. Such damages, costs, liability and
      expenses shall include such as are claimed by any regulating and/or
      administering agency, any ground lessor or master lessor of the Project,
      the holder of any Mortgage or Deed of Trust on the Project, and/or any
      successor of the Lessor named herein. This indemnity shall include (i)
      claims of third parties, including governmental agencies, for damages,
      fines, penalties, response costs, monitoring costs, injunctive or other
      relief; (ii) the costs, expenses or losses resulting from any injunctive
      relief, including preliminary or temporary injunctive relief; (iii) the
      expenses, including fees of attorneys and experts, of report the existence
      of Hazardous Substances to an agency of the State of which the Premises is
      located or of the United States as required by applicable laws and
      regulations; and (iv) any and all expenses or obligations, including
      attorney's fees, incurred at, before and after any

                                       14
<PAGE>

      administrational proceeding, trial, appeal and review. This indemnity
      shall survive the expiration or earlier termination of the term of the
      Lease or the termination of Lessee's right of possession and shall remain
      fully enforceable thereafter.

g.    INFORMATION. Lessee shall give prior written notice to Lessor of any use,
      whether incidental or otherwise, of Hazardous Substances on the Premises,
      and shall immediately deliver to Lessor a copy of any notice of any
      violation of any Law with respect to such use. Lessee shall also provide
      to Lessor, upon request, with any and all information regarding Hazardous
      Substances in the Premises, including contemporaneous copies of all
      filings and reports to governmental entities, and any other information
      requested by Lessor. In the event of any accident, spill or other incident
      involving Hazardous Substances, Lessee shall immediately report the same
      to Lessor and supply Lessor with all information and reports with respect
      to the same. All information described herein shall be provided to Lessor
      regardless of any claim by Lessee that it is confidential or privileged.

                                       15
<PAGE>

                                    EXHIBIT A
                                    PREMISES

                                       16
<PAGE>

                                    EXHIBIT B
                              RULES AND REGULATIONS

1.    Except as specifically provided in the Lease to which these Rules and
      Regulations are attached, no sign, placard, picture, advertisement, name
      or notice shall be installed or displayed on any part of the outside or
      inside of the Building or Project without the prior written consent of
      Lessor. Lessor shall have the right to remove, at Lessee's expense and
      without notice, any sign installed or displayed in violation of this rule.
      All approved signs or lettering on doors and walls shall be printed,
      painted, affixed or inscribed at the expense of Lessee by a person
      approved by Lessor.

2.    If Lessor objects in writing to any curtains, blinds, shades, screens or
      hanging plants or other similar objects attached to or used in connection
      with any window or door of the Premises, or placed on any windowsill,
      which is visible from the exterior of the Premises, Lessee shall
      immediately discontinue such use. Lessee shall not place anything against
      or near glass partitions or doors or windows which may appear unsightly
      from outside the Premises.

3.    Lessee shall not obstruct any sidewalks, halls, passages, exits,
      entrances, elevators or stairways of the Project. The halls, passages,
      exits, entrances, elevators and stairways are not open to the general
      public, but are open, subject to reasonable regulations, to Lessee's
      business invitees. Lessor shall in all cases retain the right to control
      and prevent access thereto of all persons whose presence in the judgment
      of Lessor would be prejudicial to the safety, character, reputation and
      interest of the Project and its Lessees; provided that nothing herein
      contained shall be construed to prevent such access to personnel with whom
      any Lessee normally deals in the ordinary course of its business, unless
      such persons are engaged in illegal or unlawful activities. No Lessee and
      no employee or invitee of any Lessee shall go upon the roof(s) of the
      Project, except certified HVAC employees of Lessee or Lessee's HVAC
      contractor.

4.    Lessor will furnish Lessee, free of charge, with two keys to each door
      lock in the Premises. Lessor may make a reasonable charge for any
      additional keys. Lessee shall have the right to install a card key system
      and to make or have made additional keys, and Lessee shall have the right
      to lock or install a new additional lock or bolt on any door of its
      Premises, provided Lessee provides Lessor with a pass key to access the
      Premises or any portion thereof. Lessee, upon the termination of its
      tenancy, shall deliver to Lessor the keys of all doors which have been
      furnished to Lessee, and in the event of loss of any keys so furnished,
      shall pay Lessor therefor.

5.    If Lessee requires telegraphic, telephonic, burglar alarm or similar
      services, it shall first obtain, and comply with, Lessor's instructions in
      their installation.

6.    No equipment, materials, furniture, packages, supplies, merchandise or
      other property will be received in the Building or carried in the
      elevators except between such hours and in such elevators as may be
      designated by Lessor. Lessee's initial move in and subsequent deliveries
      of bulky items, such as furniture, safes and similar items shall, unless
      otherwise agreed in writing by Lessor, be made during the hours of 6:00
      p.m. to 6:00 a.m. or on Saturday or Sunday. Deliveries during normal
      office hours shall be limited to normal office supplies and other small
      items. No deliveries shall be made which impede or interfere with other
      Lessees or the operation of the Building.

7.    Lessee shall not place a load upon any floor of the Premises which exceeds
      the load per square foot which such floor was designed to carry and which
      is allowed by Law. Lessor shall have the right to prescribe the weight,
      size and position of all equipment, materials, furniture or other property
      brought into the Building. Heavy objects shall, if considered necessary by
      Lessor, stand on such platforms as determined by Lessor to be necessary to
      properly distribute the weight, which platforms shall be provided at
      Lessee's expense. Business machines and mechanical equipment belonging to
      Lessee which cause noise or vibration that may be transmitted to the
      structure of the Building or to any space therein shall be placed and
      maintained by Lessee, at Lessee's expense, on vibration eliminators, or
      other devices sufficient to eliminate noise or vibration. The persons
      employed to move such equipment in or out of the Building must be
      acceptable to Lessor. Lessor will not be responsible for loss of, or
      damage to, any such equipment

                                       17
<PAGE>

      or other property from any cause, and all damage done to the building by
      maintaining or moving such equipment or other property shall be repaired
      at the expense of Lessee.

8.    Lessee shall use the Premises only for general office, laboratory,
      research, process and product development and related uses, including
      without limitation, light manufacturing and storage. Lessee shall not
      allow any use of the Premises which will negatively affect cost of
      coverage of Lessor's insurance on the Project. Lessee shall not allow any
      use of the Premises which would cause the value of any part of the
      Premises to diminish or would interfere with the use of any other tenant
      or owner within Canyon Park. Lessee shall not permit any nuisance or waste
      upon the Premises, or allow any offensive noise or odor in or around the
      Premises.

9.    Lessee shall use heating or air conditioning systems supplied by the
      Lessor, and/or heating and air conditioning systems added to the building
      by the Lessee.

10.   Lessee shall not waste electricity, water or air conditioning and agrees
      to cooperate fully with Lessor to assure the most effective operation of
      the Building's heating and air conditioning and to comply with any
      governmental energy-saving rules, laws or regulations of which Lessee has
      actual notice, and shall refrain from attempting to adjust controls.
      Lessee shall keep corridor doors closed, and shall close window coverings
      at the end of each business day.

11.   Lessor reserves the right, exercisable without notice and without
      liability to Lessee, to change the name and street address of the
      Building.

12.   Lessor reserves the right to exclude from the Building between the hours
      of 6 p.m. and 7 a.m. the following day, or such other hours as may be
      established from time to time by Lessor, and on Sundays and legal
      holidays, any person unless that person is known to the person or employee
      in charge of the Building and has a pass or is properly identified. Lessee
      shall be responsible for all persons for whom it requests passes and shall
      be liable to Lessor for all acts of such persons. Lessor shall not be
      liable for damages for any error with regard to the admission to or
      exclusion from the Building of any person. Lessor reserves the right to
      prevent access to the Building in case of invasion, mob, riot, public
      excitement or other commotion by closing the doors or by other appropriate
      action.

13.   Lessee shall entirely shut off any water faucets or other water apparatus,
      and electricity, gas or air outlets before Lessee and its employees leave
      the Premises. Lessee shall be responsible for any damage or injuries
      sustained by other Lessees or occupants of the Building or by Lessor for
      noncompliance with this rule.

14.   The toilet rooms, toilets, urinals, wash bowls and other apparatus shall
      not be used for any purpose other than that for which they were
      constructed and no foreign substance of any kind whatsoever shall be
      thrown therein. The expense of any breakage, stoppage or damage resulting
      form the violation of this rule shall be borne by the Lessee who, or whose
      employees or invitees, shall have caused it.

15.   Lessee shall not sell, or permit the sale at retail of newspapers,
      magazines, periodicals, theater tickets or any other goods or merchandise
      to the general public in or on the Premises. Lessee shall not make any
      room-to-room solicitation of business from other Lessees in the Project.
      Lessee shall not use the Premises for any business or activity other than
      that specifically provided for in Lessee's Lease. Canvassing, soliciting
      and distribution of handbills or any other written material, and peddling
      in the Project are prohibited, and Lessee shall cooperate to prevent such
      activities.

16.   Lessee shall not install any radio or television antenna, loudspeaker or
      other devices on the roof(s) or exterior walls of the Building or Project.
      Lessee shall not interfere with radio or television broadcasting or
      reception from or in the Project or elsewhere.

17.   Lessee shall not mark, drive nails, screw or drill into the partitions,
      woodwork or plaster or in any way deface the Premises or any part thereof,
      except in accordance with the provisions of the Lease pertaining to
      alterations. Lessor reserves the right to direct electricians as to where
      and how telephone and telegraph wires are to be introduced to

                                       18
<PAGE>

      the Premises. Lessee shall not cut or bore holes for wires. Lessee shall
      not affix any floor covering to the floor of the Premises in any manner
      except as approved by Lessor. Lessee shall repair any damage resulting
      from noncompliance with this rule.

18.   Lessee shall not install, maintain or operate upon the Premises any
      vending machines without the written consent of Lessor.

19.   Lessor reserves the right to exclude or expel from the Project any person
      who, in Lessors' judgment, is intoxicated or under the influence of liquor
      or drugs or who is in violation of any of the Rules and Regulations of the
      Building.

20.   Lessee shall store all its trash and garbage within its own storage
      facilities on the Premises, and shall be responsible, at its sole cost and
      expense, for disposal of its trash and garbage (in a manner reasonably
      acceptable to Lessor). Lessee shall not place in any trash box or
      receptacle any material which cannot be disposed of in the ordinary and
      customary manner of trash and garbage disposal.

21.   Except as otherwise provided herein, the Premises shall not be used for
      the storage of merchandise held for sale to the general public, or for
      lodging or for manufacturing of any kind, nor shall the Premises be used
      for any improper, immoral or objectionable purpose. No cooking shall be
      done or permitted on the Premises without Lessor's consent, except that
      used by Lessee of Underwriters' Laboratory approved equipment for brewing
      coffee, tea, hot chocolate and similar beverages or use of microwave ovens
      for employee use shall be permitted, provided that such equipment and use
      is in accordance with all applicable Laws.

22.   Lessee shall not use in any space or in the public halls of the Project
      any hand truck except those equipped with rubber ties and side guards or
      such other material-handling equipment as Lessor may approve. Lessee shall
      not bring any other vehicles of any kind into the Building or Project.

23.   Lessee shall comply with all safety, fire protection and evacuation
      procedures and regulations established by Lessor or any governmental
      agency.

24.   Lessee assumes any and all responsibility for protecting its Premises from
      theft, robbery and pilferage, which includes keeping doors locked and
      other means of entry to the Premises closed.

25.   Lessee's requirements will be attended to only upon appropriate
      application to the Project management office by an authorized individual.
      Employees of Lessor shall not perform any work or do anything outside of
      their regular duties unless under special instructions from Lessor.

26.   Lessor may waive any one or more of these Rules and Regulations for the
      benefit of Lessee or any other Lessee, but no such waiver by Lessor shall
      be construed as a waiver of such Rules and Regulations in favor of Lessee
      or any other Lessee, nor prevent Lessor from thereafter enforcing any such
      Rules and Regulations against any or all of the Lessees of the Project.

27.   These Rules and Regulations are in addition to, and shall not be construed
      to in any way modify or amend, in whole or in part, the terms, covenants,
      agreements and conditions of the Lease.

28.   Lessor reserves the right to make such other and reasonable Rules and
      Regulations as, in its judgment, may from time to time be needed for
      safety and security, for care and cleanliness of the Project and for the
      preservation of good order therein. Lessee agrees to abide by all such
      Rules and Regulations hereinabove stated and any additional rules and
      regulations which are adopted.

29.   Lessee shall be responsible for the observance of all of the foregoing
      rules by Lessee's employees, agents, clients, customers, invitees and
      guests.

30.   Lessee shall comply with the "No Smoking" policy in all interior areas of
      the building.

                                       19
<PAGE>

                                    RIDER TWO
                           ADDITIONAL LEASE PROVISIONS

1.    ADDITIONAL PROVISIONS CONCERNING OPERATING EXPENSES

      Notwithstanding anything to the contrary contained in the Lease, the
following items shall be excluded (or, as applicable, deducted) from the
calculation of Lessee's share (if any) of operating costs and expenses of the
Building and/or Project:

      (a) The cost of repairs or other work occasioned by fire, windstorm or
other casualty or loss in excess of the insurance proceeds therefore (or, if
greater, the proceeds that would have been available had Lessor maintained the
insurance required to be maintained by Lessor pursuant to this Lease), or by the
exercise of eminent domain;

      (b) Deductibles under Lessor's insurance policies in excess of $50,000.00;

      (c) Costs resulting from the correction of any latent construction defects
in all or any portion of the Building or Project, or any condition with regard
to the structure and the common areas that is, as of the date of this Lease, not
in compliance with applicable laws, codes rules or regulations;

      (d) Rental concessions or lease buyouts;

      (e) The costs of renovating or otherwise improving or decorating, painting
or redecorating space (exclusive of common areas) for any lessee or other
occupants of the Building or Project, including, without limitation, Lessee;

      (f) Depreciation of the real property;

      (g) Payments of principal, interest or other payments of any kind on any
deeds to secure debt, mortgages, ground or underlying leases, or other
hypothecations for security of all or any part of the Building or Project by
Lessor;

      (h) Rents payable in connection with any ground or underlying lease of all
or any portion of the Building or Project;

      (i) Lessor's general overhead and any other expense not directly related
to the Building or Project (other than the management fee referred to in
paragraph 9(c) above);

      (j) All items, services and/or goods for which Lessee or any other lessee,
occupant, person or other party is obligated to reimburse Lessor or to pay third
parties;

      (k) Advertising and promotional expenses with respect to leasing space in
or selling the Building or Project;

      (l) Brokerage, legal and professional fees expended by Lessor in
connection with negotiating and entering into any leases and any related
instruments (including, without limitation, guaranties, surrender agreements,
leasing amendments and consents to assignment or subletting) with any lessee or
other occupant of any portion of the Building or Project, and the enforcement of
any such instruments; or which are expended or incurred by Lessor in connection
with the negotiation and entering of sale, ground lease, financing, partnership
or similar transactions pertaining to the Building, Project, or any portion
thereof, and/or to Lessor or an interest in Lessor, including without
limitation, promissory notes, security deeds, mortgages, ground or master
leases, purchase and sale agreements, options, and any and all similar and/or
related documents, instruments and agreements;

      (m) Estate, inheritance, gift, franchise and income taxes of Lessor;

      (n) Wages, salaries and other compensation paid to employees of the Lessor
who are at or above the level of Property Manager;

      (o) All items that would be capitalized under generally accepted
accounting principles as of the date hereof except as expressly provided in
Section 9 of this Lease;

                                       20
<PAGE>

      (p) The cost of defending against claims in regard to the existence or
release of hazardous substances or materials at the Building or Project and
costs of any cleanup of any such hazardous substances or materials (except with
respect to those costs for which Lessee is otherwise responsible pursuant to the
express Terms of this Lease);

      (q) Costs and expenses incurred in connection with compliance with or the
contesting or settlement of any claimed violation of law or requirements of law;

      (r) Interest, penalties or damages incurred by Lessor for late payment of
taxes or assessments or under any agreement to which Lessor is a party by reason
of the breach or default of Lessor;

      (s) Expenses incurred in connection with relocating lessee in the Building
or Project;

      (t) Amounts received by Lessor through proceeds of insurance to the extent
the proceeds are compensation for expenses which were previously included in
Building operating costs charged to lessees;

      (u) Costs related to public transportation, transit or van pools, unless
required by an appropriate government or quasi-government authority or as a
result of the activities of Lessee; and

      (v) All other items for which Lessee or any other lessee, occupant or
other party compensates Lessor, so that no duplication of payments by Lessee or
to Lessor shall occur.

2.    ASSIGNMENT AND SUBLETTING BY LESSEE

      Lessor hereby consents to an assignment of this Lease or a subletting of
all or part of the Premises to (a) a parent of Lessee, the parent of such
parent, or a wholly owned subsidiary of Lessee, of such parent, or of the parent
of such parent and (b) any entity to whom Lessee sells all or substantially of
its assets provided that any such entity expressly assumes all Lessee's
obligations hereunder.

3.    HAZARDOUS SUBSTANCES

      To the best of Lessor's knowledge, after reasonable inquiry, there are no
hazardous wastes or substances in the soil or groundwater of the real property
on which the building is located and Lessor has not disposed of or approved any
disposal by any other party of any hazardous wastes or substances on or from the
Building.

4.    NOTICE

      Any notice required to be given to Lessee shall be sent via facsimile,
overnight express mail or U.S. mail, postage prepaid, addressed as follows:

               ICOS Corporation
               22021 20th Avenue SE
               Bothell, Washington  98021
               Attn: Facilities Manager
               Fax: (206) 481-8305

      Notices shall be effective upon receipt.

                                       21

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