<PAGE>   1
                                                                    EXHIBIT 10.8

                   SECOND AMENDMENT TO COLUMBIA BUILDING LEASE


            THIS SECOND AMENDMENT TO COLUMBIA BUILDING LEASE (this "SECOND
AMENDMENT") dated for reference purposes only as of September 25, 1998, is made
by and between ALEXANDRIA REAL ESTATE EQUITIES, INC., a Maryland corporation
("LANDLORD"), and CORIXA CORPORATION, a Delaware corporation ("TENANT").
Capitalized terms used in this Second Amendment but not expressly defined herein
will have the meanings given them in the amended Lease (as such term is
hereinafter defined), which is incorporated herein by reference.

                                    RECITALS

            A.    Fred Hutchinson Cancer Research Center, a Washington nonprofit
corporation ("FHCRC"), Landlord's predecessor in interest, and Tenant previously
entered into that certain Columbia Building Lease dated as of October 28, 1994
(together with all exhibits thereto, the "ORIGINAL LEASE"), providing for the
lease of certain premises described therein upon the terms and conditions
specified therein.

            B.    FHCRC and Tenant previously entered into that certain Columbia
Building Lease First Amendment dated as of December 29, 1995 (together with all
exhibits thereto, the "FIRST AMENDMENT"), providing for the amendments to the
Original Lease specified therein.

            C.    On or about May 31, 1996, FHCRC sold to Landlord the Research
Complex, including, without limitation, the Building of which the Premises are a
part, and assigned to Landlord the Original Lease as amended by the First
Amendment (the "LEASE").

            D.    Landlord and Tenant desire to amend the Lease to provide for,
among other things, Landlord's lease to Tenant and Tenant's lease from Landlord
of certain additional premises described herein and in Exhibits A, B, and C
attached hereto (collectively, the "SECOND AMENDMENT PREMISES"), upon the terms
and conditions specified herein and in the Lease.

            NOW, THEREFORE, in consideration of the mutual covenants and
agreements herein contained and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant
agree as follows:

            1.    Scope of Second Amendment. This Second Amendment is intended
to supplement (and not supersede) the Lease. Except as expressly provided
herein, or to the extent of an inconsistency between the Lease and this Second
Amendment (in which case this Second Amendment will control), all of the terms
of the Lease will continue in full force and effect and will apply to the
existing, from time to time, and expanded 


                                       1
<PAGE>   2
Premises, the Premises to include, without limitation, the Second Amendment
Premises (except where expressly stated or the context clearly requires
otherwise.)

            2.    Second Amendment of Lease. Effective as of the date hereof,
the following provisions of the Lease are amended as specified below:

                  a.    Additional Defined Terms. To the end of the introductory
paragraph of the Lease is added the following:

      "This Lease has been amended by that certain Columbia Building Lease First
      Amendment dated as of December 29, 1995 (the "FIRST AMENDMENT"), and by
      that certain Second Amendment to Columbia Building Lease dated as of
      September 25, 1998 (the "SECOND AMENDMENT"). Except where expressly stated
      or the context clearly requires otherwise, references herein to "the
      Lease" or "this Lease" or any similar construction, will mean the Lease as
      amended from time to time."

                  b.    Confirmation of Landlord. The first block of Section 1
of the Lease entitled "LESSOR" is deleted in its entirety and replaced with the
following:

      "LESSOR                      Alexandria Real Estate Equities, Inc.

      Address for all notices:     135 N. Los Robles Avenue, Suite 250
                                   Pasadena, California 91101
                                   Attention: General Counsel
                                   Tel: (626) 578-0777
                                   Fax: (626) 578-0770

      with a copy to:              11440 W. Bernardo Court, Suite 170
                                   San Diego, California 92127
                                   Attention:  Asset Management
                                   Tel: (619) 592-6801
                                   Fax: (619) 592-6814"

                  c.    Premises. The first and second sentences of Subsection
2.1(a) of the Lease are deleted in their entirety and replaced with the
following:

      "Landlord hereby leases to Tenant and Tenant hereby leases from Landlord
      on the terms and conditions stated in this Lease (as amended from time to


                                       2
<PAGE>   3
      time) the laboratory, office, and other space described herein (the
      "PREMISES") in the building and connected underground annex commonly known
      as the Columbia Building (collectively, the "BUILDING") and located on the
      real property legally described on Exhibit A to this Lease (the
      "PROPERTY"). The original premises are generally depicted on Exhibit B to
      this Lease."

                  d.    Second Amendment Premises. To the end of Section 2 of
the Lease is added the following:

      "2.8 SECOND AMENDMENT FIFTH FLOOR PREMISES. Commencing on June 1, 1998,
      Landlord will lease to Tenant and Tenant will lease from Landlord, on the
      terms and subject to the conditions set forth in this Lease, the
      additional space depicted on Exhibit A attached to the Second Amendment
      (the "SECOND AMENDMENT FIFTH FLOOR PREMISES"), which Landlord and Tenant
      stipulate and agree will be deemed to consist of a total of 949 rentable
      square feet.

      2.9 SECOND AMENDMENT SIXTH FLOOR PREMISES. Commencing on June 1, 1998,
      and, notwithstanding anything to the contrary contained herein, extending
      only until May 31, 1999, (at which time Tenant will vacate the space and
      surrender possession thereof to Landlord in accordance with all the terms
      and conditions of this Lease relating thereto), Landlord will lease to
      Tenant and Tenant will lease from Landlord, on the terms and subject to
      the conditions set forth in this Lease, the additional space depicted on
      Exhibit B attached to the Second Amendment (the "SECOND AMENDMENT SIXTH
      FLOOR PREMISES"), which Landlord and Tenant stipulate and agree will be
      deemed to consist of a total of 12,305 rentable square feet.

      2.10 SECOND AMENDMENT FIRST FLOOR PREMISES. Commencing on October 1, 1998,
      Landlord will lease to Tenant and Tenant will lease from Landlord, on the
      terms and subject to the conditions set forth in this Lease, the
      additional space depicted on Exhibit C attached to the Second Amendment
      (the "SECOND AMENDMENT FIRST FLOOR Premises"), which Landlord and Tenant
      stipulate and agree will be deemed to consist of a total of 5,991 rentable
      square feet. (The Second Amendment First Floor Premises, the Second
      Amendment Fifth Floor Premises, and the Second Amendment Sixth Floor
      Premises are sometimes collectively referred to herein as the "SECOND
      AMENDMENT PREMISES," and individually referred to herein as a "component
      of" the Second Amendment Premises.)"


                                       3
<PAGE>   4
                  e.    Base Rent. Section 4.1 of the Lease is deleted in its
entirety and replaced with the following:

      "4.1 BASE RENT

      (a) Except with respect to the Second Amendment Premises, Tenant agrees to
      pay Landlord annual base rent for the Premises at the rate of $28.00 per
      rentable square foot, payable in twelve equal monthly installment in
      advance of the first day of each calendar month, subject to increase as
      provided in Sections 4.2 and 8.6(c) below (the "PRE-SECOND AMENDMENT BASE
      RENT"). Except as otherwise provided herein, the Pre-Second Amendment Base
      Rent for expansion space (including, without limitation, the Initial
      Fourth Floor Expansion Space, Second Floor and Long Term Expansion Space)
      will be the Pre-Second Amendment Base Rent in effect as of the date the
      expansion space is added to the Premises. Rent for the Second Floor and
      any Long Term Expansion Space (as defined below) will commence on the date
      specified in Section 8.7 below.

      (b) Tenant agrees to pay Landlord annual base rent for the Second
      Amendment Fifth Floor Premises at the rate of $8.00 per rentable square
      foot, payable in twelve equal monthly installments in advance on the first
      day of each calendar month, subject to increase as provided in Section 4.2
      below (the "SECOND AMENDMENT FIFTH FLOOR BASE RENT").

      (c) Tenant agrees to pay Landlord annual base rent for the Second
      Amendment Sixth Floor Premises at the rate of $28.84 per rentable square
      foot, payable in twelve equal monthly installments in advance on the first
      day of each calendar month, subject to increase as provided in Section 4.2
      below (the "SECOND AMENDMENT SIXTH FLOOR BASE RENT")."

      (d) Tenant agrees to pay Landlord annual base rent for the Second
      Amendment First Floor Premises at the rate of $16.65 per rentable square
      foot, payable in twelve equal monthly installments in advance on the first
      day of each calendar month, subject to increase as provided in Section 4.2
      below (the "SECOND AMENDMENT FIRST FLOOR BASE RENT"). (The Second
      Amendment First Floor Base Rent, the Second Amendment Fifth Floor Base
      Rent, and the Second Amendment Sixth Floor Base Rent are sometimes
      collectively referred to herein as the "SECOND AMENDMENT BASE RENT;" the
      Pre-Second Amendment Base Rent and the Second Amendment Base Rent are
      sometimes collectively referred to herein as the "BASE RENT;" 


                                       4
<PAGE>   5
      and the Base Rent and any applicable Additional Base Rent are sometimes
      collectively referred to herein as "RENT").

      (e) Rent will be paid by Tenant to Landlord at the first address shown on
      Section 1 of the Lease or such other place as Landlord may designated by
      written notice to Tenant. Rent for any period during the Term that is less
      than one month will be prorated on a per diem basis based upon a
      thirty-day month."

                  f.    Base Rent Adjustment. Subsections 4.2(a) and 4.2(b) of
the Lease are deleted in their entirety and replaced with the following, and
subsections 4.2(c) and 4.2(d) of the Lease are renumbered as 4.2(d) and 4.2(e)
respectively:

      "(a) Beginning January 15, 1998, Pre-Second Amendment Base Rent will be
      increased on each anniversary thereof (the "ADJUSTMENT DATE") by the
      percentage increase in the Consumer Price Index (defined below) over the
      preceding twelve (12) month period, measured by the percentage difference
      between the Consumer Price Index most recently published prior to that
      Adjustment Date and the Consumer Price Index most recently published prior
      to the previous Adjustment Date In no event, however, will the increase in
      Pre-Second Amendment Base Rent for any Lease year be less than three
      percent (3%) or more than six percent (6%). "Consumer Price Index" will
      mean the Consumer Price Index - All Urban Consumers, All Cities, 1988
      Revision (1982-84 = 100), which is published by the United States Bureau
      of Labor Statistics or such comparable successor index as may be published
      by the United States Bureau of Labor Statistics from time to time.

      (b) Each segment of Additional Base Rent (i.e., Second Floor Additional
      Base Rent, Third Floor Additional Base Rent and Fourth Floor Additional
      Base Rent), and each segment of Second Amendment Base Rent (i.e., the
      Second Amendment First Floor Base Rent, Second Amendment Fifth Floor Base
      Rent, and Second Amendment Sixth Floor Base Rent) will also be adjusted
      annually on the anniversary of the Adjustment Date in the same manner as
      Pre-Second Amendment Base Rent; provided, however, that the first
      adjustment for each will be calculated using as a base index the Consumer
      Price Index published on the Adjustment Date immediately prior to the date
      on which that segment of Additional Base Rent or of Second Amendment Base
      Rent, as the case may be, commenced, and the amount of the adjustment will
      be pro-rated for the period between the date such 


                                       5
<PAGE>   6
      Additional Base Rent or Second Amendment Base Rent, as the case may be,
      first becomes payable and the next following Adjustment Date.

      (c) If the Consumer Price Index is discontinued and no comparable
      successor index is published by the United States Bureau of Labor
      Statistics, the parties will select another similar index which reflects
      consumer prices, and if the parties cannot agree on another index, it will
      be selected by binding arbitration pursuant to the terms of this Lease. If
      arbitration is required to select another index, Tenant will continue to
      pay an amount equal to the Pre-Second Amendment Base Rent, Second
      Amendment Base Rent, and Additional Base Rent or adjusted Pre-Second
      Amendment Base Rent, Second Amendment Base Rent, and Additional Base Rent
      last payable until the newly adjusted Pre-Second Amendment Base Rent,
      Second Amendment Base Rent, and Additional Base Rent can be determined
      (which in no event will be less than the Pre-Second Amendment Base Rent,
      Second Amendment Base Rent, and Additional Base Rent last payable), at
      which time Tenant will pay any additional amounts owed for that Lease year
      based on the newly adjusted Pre-Second Amendment Base Rent, Second
      Amendment Base Rent, and Additional Base Rent as determined by the
      arbitration, and Tenant will thereafter pay such newly adjusted Pre-Second
      Amendment Base Rent, Second Amendment Base Rent, and Additional Base Rent,
      subject to further adjustments as provided herein."

                  g.    Pro Rata Share Calculation. Subsection 4.3(b) of the
Lease is deleted in its entirety and replaced with the following:

      "(b) Tenant's "Pro Rata Share" will mean the percentage that is obtained
      by dividing (i) the total rentable square feet of the Premises (not ever
      including the Second Amendment First Floor Premises, and not including the
      Second Amendment Fifth Floor Premises except as provided in Subsection
      4.3(j) of this Lease, but expressly including, without limitation, the
      Second Amendment Sixth Floor Premises) from time to time by (ii) the total
      rentable square feet of the Building (not ever including the rentable
      square footage on the first floor thereof), which Landlord and Tenant
      stipulate and agree will be deemed to consist of a total of 143,631
      rentable square feet. In the event of a change in the amount of Tenant's
      Pro Rata Share, Landlord will deliver to Tenant a statement showing the
      amount payable by Tenant, the manner in which the amount was calculated,
      and the data or documentation supporting those calculations."


                                       6
<PAGE>   7
                  h.    Gross Operating Expenses and Operating Expenses. All
occurrences of the words "Operating Expenses" in Subsections 2.4(a)(2), 4.3(d),
4.3(e), and 6.2(a) of the Lease, in the second sentence of Subsection 8.1(a) of
the Lease, and in Sections 10.2 and 24 of the Lease, are deleted in their
entirety and replaced with the words "Gross Operating Expenses."

                  i.    Additional Operating Expenses; Change in Pro Rata Share
Calculation. To the end of Section 4.3 of the Lease is added the following:

      "(h) "Operating Expenses" for any period will mean the mathematical
      difference calculated by subtracting (i) the product of the First Floor
      Operating Expense Rate (as hereinafter defined) during such period by the
      total rentable square footage on the first floor of the Building (which
      Landlord and Tenant stipulate and agree will be deemed to consist of a
      total of 16,893 rentable square feet) from (ii) Gross Operating Expenses
      for such period.

      (i) Notwithstanding anything to the contrary contained herein, commencing
      on October 1, 1998, Tenant will pay to Landlord as additional rent, and in
      the same manner as Tenant's Pro Rata Share of Operating Expenses,
      additional annual expenses relating to the Second Amendment First Floor
      Premises (the "SECOND AMENDMENT FIRST FLOOR OPERATING EXPENSES") at the
      rate of $8.00 per rentable square foot thereof, subject to adjustment as
      hereinafter provided (the "FIRST FLOOR OPERATING EXPENSE RATE"). Second
      Amendment First Floor Operating Expenses will be payable in twelve equal
      monthly installments in advance on the first calendar day of each calendar
      month. Second Amendment First Floor Operating Expenses will be increased
      by three percent (3%) each calendar year commencing on January 1, 2000,
      including, without limitation, throughout any Option Period and any period
      of Tenant's retention of the Second Amendment First Floor Premises after
      the expiration of the Term.

                  j.    Condition of Second Amendment Premises. To the end of
Section 7.1 of the Lease is added the following:

      "Landlord will deliver the components of the Second Amendment Premises to
      Tenant clean and free of debris and hazardous materials (without any
      obligation to paint the same), and with any existing cabinetry and
      equipment included (in its current state), but otherwise in an AS-IS
      condition."


                                       7
<PAGE>   8
                  k.    Alterations and Utility Installations. Subsections
8.3(h), 8.3(i), and 8.3(k) of the Lease are deleted in their entirety and
replaced with the following:

      "(h) Tenant may make Alterations and Utility Installations to the Premises
      on the terms and conditions of this Section 8.3. In addition: (i) the
      initial Alterations and Utility Installations planned by Tenant for the
      Second, Third and Fourth Floors (the "TENANT IMPROVEMENT WORK") will be
      performed in accordance with a work letter attached as Exhibit I to the
      First Amendment (the "WORK LETTER"), which Work Letter was executed by
      Tenant and Landlord concurrently with their execution of the First
      Amendment; and (ii) the initial Alternations and Utility Installations
      planned by Tenant for the Second Amendment Premises (the "SECOND AMENDMENT
      TENANT IMPROVEMENT WORK") will be performed in accordance with a work
      letter attached as Exhibit D to the Second Amendment (the "SECOND
      AMENDMENT WORK LETTER"), which Second Amendment Work Letter was executed
      by Tenant and Landlord concurrently with their execution of the Second
      Amendment. Landlord will provide Tenant and its contractors with access to
      the relevant Premises for purposes of completing the work under the Work
      Letter and the Second Amendment Work Letter as provided under Section 8.7
      below.

      (i) Prior to Landlord allowing Tenant to enter upon the relevant Premises
      for the purpose of performing the Tenant Improvement Work or the Second
      Amendment Tenant Improvement Work pursuant to the Work Letter and the
      Second Amendment Work Letter respectively, or for the placing of personal
      property, Tenant will furnish to Landlord evidence satisfactory to
      Landlord that insurance coverage required of Tenant under the provisions
      of Section 10 of the Lease are in effect, and such entry will be subject
      to all the terms and conditions of the Lease other than the payment of
      Base Rent or Operating Expenses.

      (k) Any unresolved dispute arising under this Section 8.3, the Work
      Letter, or the Second Amendment Work Letter will be submitted to binding
      arbitration as set forth in Section 25 of the Lease."

                  l.    Allowances. To the end of Section 8.6 of the Lease is
added the following:

      "(e) Landlord will also provide Tenant with an allowance, in an amount not
      to exceed $191,712.00, to reimburse Tenant for its disbursements to 


                                       8
<PAGE>   9
      third parties incurred solely in connection with Alterations and Utility
      Installations for the Second Amendment First Floor Premises (the "SECOND
      AMENDMENT ALLOWANCE"), subject to the terms and conditions of this Section
      8.6 and the Second Amendment Work Letter; provided, however, that Tenant
      will not be entitled to any part of the Second Amendment Allowance unless
      and until Tenant has completed the installation of sprinklers in the
      Second Amendment First Floor Premises in accordance with this Lease, the
      Second Amendment Work Letter, and all applicable Laws. Tenant agrees to
      complete such work prior to commencing any of its business in the Second
      Amendment First Floor Premises."

      "(f) Landlord will also provide Tenant with an allowance, in an amount not
      to exceed $35,000.00, to reimburse Tenant for one-half (1/2) of its
      disbursements to third parties incurred solely in connection with the
      installation of sprinklers on the Third Floor and the Fourth Floor in
      accordance with the Lease, the Second Amendment Work Letter, and all
      applicable Laws. Tenant agrees to complete such work on or before May 31,
      1999.

                  m.    Access to Second Amendment Premises. To the end of
Section 8.7 of the Lease is added the following:

      "Landlord will provide Tenant with access to the Second Amendment Sixth
      Floor Premises on or prior to June 1, 1998. Landlord may provide Tenant
      access to the Second Amendment Fifth Floor Premises and the Second
      Amendment First Floor Premises prior to the dates Tenant is to receive
      possession thereof pursuant to Sections 2.8 and 2.10 of the Lease
      respectively, solely for the construction of Alterations and Utility
      Installations relating thereto and the placing of personal property
      therein, but Landlord will be under no obligation to do so and will assume
      no liability for any failure to do so."

                  n.    Landlord's Indemnity. Subsection 11.8(b) of the Lease is
deleted in its entirety, and Landlord and Tenant agree that such provision will
be deemed to have been null and void ab initio.

                  o.    Remedies. Subsection 19.2(a) of the Lease is deleted in
its entirety and replaced with the following:


                                       9
<PAGE>   10
      "(a) Terminate Tenant's right to possession of the Premises by any lawful
      means, in which case Tenant shall immediately surrender possession of the
      Premises to Landlord. In such event, Landlord shall be entitled to recover
      from Tenant all damages incurred by Landlord by reason of Tenant's default
      including, but not limited to, the cost of recovering possession of the
      Premises, including reasonable attorneys' fees and expenses, and Landlord
      shall be entitled to enforce all of Landlord's rights and remedies under
      this Lease, including the right to recover rent as it becomes due."

And to the end of Section 19.2 of the Lease is added the following:

      "(d) Terminate the Lease by any lawful means, in which case Tenant shall
      immediately surrender possession of the Premises to Landlord. In such
      event, Landlord shall be entitled to recover from Tenant all damages
      incurred by Landlord by reason of Tenant's default including, but not
      limited to, the cost of recovering possession of the Premises, including
      reasonable attorneys' fees and expenses."

                  p.    Signage. To the end of Section 27 of the Lease is added
the following:

      "Landlord may at any time place on or about the Building or the Research
      Complex any ordinary "For Sale" or "For Lease" signs provided such signs
      or the installation thereof do not damage, cover, or otherwise obstruct in
      any manner the public view of any signage placed at the Research Complex
      by Tenant in accordance with the terms and conditions of this Lease."

                  q.    Second Amendment Basement Space. To the end of the Lease
is added the following:

      "45. LICENSE; SHIPPING AND RECEIVING SERVICES.

      45.1 GRANT AND USE OF LICENSE. Landlord hereby grants to Tenant a
      revocable license (the "LICENSE") for the use by Tenant of certain space
      located in the basement of the Building and depicted on Exhibit E attached
      to the Second Amendment (the "SECOND AMENDMENT BASEMENT SPACE"). Tenant
      may use such space exclusively for the purposes of operating and
      maintaining (at Tenant's sole expense) shipping and receiving services for
      the benefit of Tenant and all other tenants of the Building as described
      in Section 45.6 hereof (the "SHIPPING AND RECEIVING SERVICES"), and to the


                                       10
<PAGE>   11
      extent it does not interfere therewith, the storage of Tenant's belongings
      (excluding Hazardous Substances), both in accordance with all federal,
      state, and local laws, rules, and regulations. Although the Second
      Amendment Basement Space does not and will not constitute a part of the
      Premises or rentable square footage at the Building, Tenant nevertheless
      acknowledges and agrees that all of Tenant's obligations, duties, and
      burdens (but none of its rights and privileges except as expressly
      provided in this Section 45) pertaining to the Premises, except for the
      payment of Rent and Operating Expenses, shall also apply to the Second
      Amendment Basement Space including, without limitation, the obligations,
      duties, and burdens imposed on Tenant pursuant to Sections 6, 7, 8, 10 and
      11 of this Lease; provided, however, that nothing contained in this
      sentence shall in any way diminish or otherwise abrogate Tenant's
      agreements herein that specifically relate to the License, the Shipping
      and Receiving Services, or the use of the Second Amendment Basement Space.
      The License is made upon and subject to the terms, covenants, and
      conditions herein set forth, and Tenant agrees as a material part of the
      consideration for this License to keep and perform each and all of the
      terms, covenants, and conditions hereof to be kept and performed by
      Tenant, and this License is made upon the condition of such performance.

      45.2 TERM OF LICENSE. The term of the License shall be for a period
      commencing on June 1, 1998, and ending on the earlier of: (i) the
      expiration or earlier termination of this Lease; (ii) five business days
      after Landlord's written notification to Tenant of Landlord's
      determination, in its sole and absolute discretion, to terminate the
      License; and (iii) thirty calendar days after Tenant's written
      notification to Landlord of Tenant's determination, in its sole and
      absolute discretion, to both cease providing the Shipping and Receiving
      Services and terminate the License. Upon any termination of the License as
      provided in clause (i) immediately preceding, Tenant shall immediately
      vacate, surrender possession of, and turn over to Landlord the entire
      Second Amendment Basement Space. Upon any termination of the License as
      provided in clauses (ii) and (iii) immediately preceding, Tenant shall
      immediately vacate, surrender possession of, and turn over to Landlord
      that portion of the Second Amendment Basement Space shown on Exhibit E as
      the "Terminable Second Amendment Basement Space," but Tenant may, if
      Tenant so desires, retain for its use for the remaining Term that portion
      of the Second Amendment Basement Space described on Exhibit E as the
      "Retainable Second Amendment Basement Space provided that Tenant shall
      advise Landlord in writing, prior to the termination of the License, of
      its intent to retain such space, 


                                       11
<PAGE>   12
      and further provided that Tenant shall thereafter pay Landlord a fixed
      monthly rent of $8.00 per square foot for the continued use of such space.

      45.3 NATURE AND SCOPE OF LICENSE. Tenant hereby acknowledges and agrees
      that the License is a revocable, personal, non-exclusive, unassignable
      privilege only, and not a grant of a property interest in the Building,
      the Research Complex, or elsewhere.

      45.4 LICENSE FEE AND SECURITY DEPOSIT. Except as provided in Section 45.2
      above, Tenant's use of the Second Amendment Basement Space shall be
      without payment to Landlord of any Rent or Operating Expenses relating
      thereto for so long as Tenant is using said space in accordance herewith.
      If Tenant remains in possession of the Terminable Second Amendment
      Basement Space or any part thereof after the License is for any reason
      terminated, Tenant shall immediately pay to Landlord therefor, in addition
      to all other loss, cost, damage, and liability suffered by Landlord on
      account thereof, without deduction, setoff, prior notice, or demand, a
      daily hold-over rental of $100.00, which amount shall be deemed earned in
      full by Landlord on a daily basis. Notwithstanding anything to the
      contrary contained in this Lease, the Security Deposit also shall be held
      and used by Landlord as security for the faithful performance by Tenant of
      all the terms, covenants, and conditions to be kept and performed by
      Tenant pursuant to this Section 45 of the Lease.

      45.5 ADDITIONAL COSTS OF LICENSE. Tenant shall pay, as an additional cost
      of obtaining and maintaining the License, all amounts paid or incurred by
      Tenant in connection with the staffing, operation, and maintenance of the
      Shipping and Receiving Services, and any costs incurred in connection with
      the termination of such services whether or not such termination is
      required by Landlord. Tenant shall not earn a profit by providing Shipping
      and Receiving Services, and may charge other tenants of the Building only
      for the amount of disbursements made by Tenant to third party shippers and
      vendors on such tenants' behalf.

      45.6 SHIPPING AND RECEIVING SERVICES. Tenant shall staff, operate, and
      maintain, and otherwise make the Shipping and Receiving Services available
      to all the other tenants of the Building, from 8:00 a.m. to 4:30 p.m.,
      Monday through Friday. Tenant shall be solely responsible for staffing,
      operating, and maintaining the Shipping and Receiving Services, and shall
      do so in a manner consistent with the level of services that were
      previously provided to tenants at the Building by FHCRC. Tenant shall
      provide Shipping and Receiving Services for the other tenants of the
      Building by: (i) providing timely notification to tenants of the arrival


                                       12
<PAGE>   13
      of packages and other materials addressed to such tenants; (ii) arranging
      appropriate and timely unloading of containers, packages, and equipment;
      (iii) arranging a drop-off zone for the pick-up of packages by express
      mail couriers; and (iv) using reasonable efforts to monitor and direct the
      flow of traffic in the area of the loading dock in a manner that
      accommodates all vehicles as efficiently as possible. Tenant shall obtain
      such additional insurance relating to its furnishing of the Shipping and
      Receiving Services as Landlord may, from time to time, reasonably require,
      and as Tenant may, from time to time, deem desirable. Notwithstanding
      anything herein to the contrary, Tenant shall have the right in connection
      with performing the Shipping and Receiving Services to establish standard
      operating procedures, reasonable in the biotechnology and biomedical
      industries, relating to safety, security, and orderliness, and Tenant
      shall also have the right to refuse to perform any or all of the Shipping
      and Receiving Services for any tenant of the Building not materially
      complying with such procedures."

                  r.    Description of the Property. The legal description in
Exhibit A attached to the Lease and in Exhibit A attached to the First Amendment
is deleted in its entirety and replaced with the following:

      "Lots 1-4, 6, and 7 , Block 94, Terry's Second Addition to the Town (now
      City) of Seattle, according to the plat thereof recorded in Volume 1 of
      Plats, Page 87, records of King County, Washington, together with the
      vacated alley adjoining said lots, all situate in the City of Seattle,
      County of King, State of Washington."

                  s.    Rentable Square Footage at Building. The language and
chart in Exhibit F attached to the First Amendment is deleted in its entirety
and replaced with the following:

        "Landlord and Tenant stipulate and agree that the rentable square
        footages of the Building will be deemed to consist of the following:


<TABLE>
<CAPTION>
                             Floor                                   RSF
<S>                                                              <C>

                          First Floor                              16,893

                         Second Floor                              21,143

                          Third Floor                              21,429

                         Fourth Floor                              21,434
</TABLE>


                                       13
<PAGE>   14
<TABLE>
<S>                                                              <C>
                          Sixth Floor                              22,166

                         Seventh Floor                             22,171

                        Annex Level 100                            11,482

                        Annex Level 200                            12,923

                        Annex Level 300                            13,883

                             TOTAL                                163,524
</TABLE>


            3.    The Second Amendment Premises. Tenant acknowledges that it has
determined to its satisfaction that the Second Amendment Premises can be used by
it for the purposes described in Subsection 6.1(a) of the Lease, and that the
Second Amendment Basement Space can be used by it for the purposes described in
Section 45 of the Lease. Except as otherwise stated in this Second Amendment,
Tenant hereby acknowledges that neither Landlord nor any of Landlord's employees
or agents has made any oral or written warranties or representations to Tenant
relating to the condition or use by Tenant of the Second Amendment Premises, the
Second Amendment Basement Space, or the Research Complex, and Tenant further
acknowledges that Tenant assumes all responsibility regarding the Occupational
Safety Health Act, the legal use and adaptability of the Second Amendment
Premises and the Second Amendment Basement Space, and the compliance thereof
with all applicable laws, rules, and regulations in effect during the term of
the Lease, except as otherwise expressly and specifically stated therein or
herein. Landlord and Tenant further agree that the provisions of Section 22 of
the Lease will not apply to Landlord's demising and Tenant's leasing of the
Second Amendment Premises pursuant to this Second Amendment, that the Second
Amendment Premises are not, as of the date hereof, "public accommodations"
within the scope of the ADA, and that the Second Amendment Basement Space shall
not be included as "space Tenant occupies" in connection with the provisions of
Section 11.1 of the Lease. If Landlord has not delivered to Tenant possession of
any of the various components of the Second Amendment Premises within sixty (60)
days of the dates scheduled therefor in Sections 2.8, 2.9 and 2.10 of the Lease,
Landlord and Tenant agree that, as Tenant's sole remedy therefor, Tenant may at
Tenant's sole and absolute option by written notice to Landlord advise Landlord,
at anytime thereafter and before accepting possession of such space, that the
relevant provisions of Paragraph 2 of this Second Amendment relating thereto
will be ineffective and of no force or effect, in which event Landlord and
Tenant will be discharged from all obligations relating thereto, Landlord will
return to or adjust with Tenant any funds received from Tenant in connection
therewith, and Landlord and Tenant will promptly 


                                       14
<PAGE>   15
enter into a further written amendment to the Lease (as amended hereby) to
document the same.

            4.    Brokers. Landlord and Tenant each represent and warrant to the
other that it has had no dealings with any broker or finder other than the firm
of Kidder, Mathews & Segner (who represents Landlord and will receive a fee from
Landlord pursuant to a separate written agreement) in connection with the
negotiation of this Second Amendment and the consummation of the transaction
contemplated hereby, and that no broker, finder, or entity other than said named
broker is entitled to any commission or finder's fee in connection with said
transaction. Landlord and Tenant do each agree to indemnify, defend, and hold
the other harmless from and against liability for compensation or charges which
may be claimed by any such unnamed broker, finder, or other similar party by
reason of any dealings or actions of the indemnifying party, including any
costs, expenses, and/or attorneys' fees and disbursements reasonably incurred
with respect thereto, and Landlord agrees to pay the commission of its broker.

            5.    Authority to Amend. Each party hereto represents and warrants
to the other that it holds all the right, title, and interest of the lessor (in
the case of Landlord ) or the lessee (in the case of Tenant) under the Lease,
and that it has full power and authority to amend the Lease as provided herein
without the consent or agreement of any third party.

            6.    Further Assurances. Landlord and Tenant hereby agree to
execute and deliver to the other any additional instrument or other document
which the other party may reasonably request to evidence or to better effect the
amendments and agreements contained herein, promptly upon the request of such
other party; provided, however, that neither party will be obligated to execute
or deliver any such other document which would enlarge the obligations or
liabilities, or diminish the rights, of such party hereunder.

            7.    Enforcement Cost. If either Landlord or Tenant institute any
actions or proceedings to enforce any provision of this Second Amendment, or for
damages or other losses incurred by reason of an alleged breach of any provision
hereof, then the prevailing party will be entitled to receive all costs and
expenses (including reasonable attorneys' fees and disbursements) incurred by
the prevailing party in connection with such action or proceeding.

            8.    Modification; Binding Effect; Benefit. This Second Amendment
may not be modified, amended, supplemented, or otherwise changed except by a
writing executed by the party against whom such modification, amendment,
supplement, or other agreement is to be enforced. The terms and provisions
contained herein will be binding 


                                       15
<PAGE>   16
upon and inure to the benefit of the parties hereto and to their respective
successors and assigns (subject to Section 18 of the Lease), but upon and to no
other.

            9.    Counterparts. This Second Amendment may be executed in any
number of counterparts, each of which when executed and delivered will be deemed
an original, and all of which taken together will constitute but one and the
same instrument.

            10.   Governing Law. This Second Amendment will be governed by,
interpreted under, and construed and enforced in accordance with the laws of the
State of Washington without giving effect to the principles of conflict of laws
thereof.

            11.   Entire Agreement. This Second Amendment sets forth the entire
agreement of the parties hereto with respect to the subject matter contained
herein, and any prior agreement, whether oral or written, express or implied, of
the parties hereto and with respect to the subject matter contained herein is
hereby declared null and void. No agreements or representations, oral or
otherwise, express or implied, with respect to the subject matter hereof have
been made by the parties hereto, that are not set forth expressly in this Second
Amendment.

            12.   Captions. The captions in this Second Amendment are for
convenience of reference only and will not be deemed to modify, explain,
restrict, alter, or affect the meaning or interpretation of any provision of
this Second Amendment.


                                       16
<PAGE>   17
            13.   Time. Time is of the essence of each and every provision
hereof.

            IN WITNESS WHEREOF, the undersigned parties have caused this

                  [Remainder of Page Intentionally Left Blank]


                                       17
<PAGE>   18
Second Amendment to be executed and delivered by their respective
representatives, thereunto duly authorized, as of the date first above written.

                                       LANDLORD:

                                       ALEXANDRIA REAL ESTATE,
                                       EQUITIES, INC., a Maryland corporation
                                       By:     /s/ PETER J. NELSON
                                               ---------------------------------
                                       Name:   Peter J. Nelson                
                                               ---------------------------------
                                       Title:  CFO
                                               ---------------------------------


                                       TENANT:

                                       CORIXA CORPORATION,
                                       a Delaware corporation
                                       By:     /s/MARK MCDADE   
                                               ---------------------------------
                                       Name:   Mark McDade
                                               ---------------------------------
                                       Title:  COO
                                               ---------------------------------


                                       18
<PAGE>   19
                                    EXHIBIT A

              DIAGRAM OF THE SECOND AMENDMENT FIFTH FLOOR PREMISES









                                    [drawing]


                                       19
<PAGE>   20
                                    EXHIBIT B

                         DIAGRAM OF THE SECOND AMENDMENT
                              SIXTH FLOOR PREMISES









                                    [drawing]


                                       20
<PAGE>   21
                                    EXHIBIT C

              DIAGRAM OF THE SECOND AMENDMENT FIRST FLOOR PREMISES











                                    [drawing]


                                       21
<PAGE>   22
                                    EXHIBIT D

                          SECOND AMENDMENT WORK LETTER


                                       22
<PAGE>   23
                          SECOND AMENDMENT WORK LETTER

            THIS SECOND AMENDMENT WORK LETTER (this "WORK LETTER") is dated for
reference purposes only as of the 25 day of September, 1998, and by and between
ALEXANDRIA REAL ESTATE EQUITIES, INC., a Maryland corporation ("LANDLORD") and
CORIXA CORPORATION, a Delaware corporation ("TENANT") with reference to the
following facts:

                                    RECITALS

        A.      Landlord and Tenant have concurrently herewith executed that
certain Second Amendment to Columbia Building Lease dated of even date herewith
(the "SECOND AMENDMENT") to which this Work Letter is attached as Exhibit D. The
Second Amendment amends that certain Columbia Building Lease dated as of October
28, 1994, as previously amended by that certain Columbia Building Lease First
Amendment dated as of December 29, 1995 (together, the " ORIGINAL LEASE"). All
capitalized terms used but not otherwise defined herein shall have the meaning
ascribed to them in the Original Lease as amended by the Second Amendment (as
so amended, the "LEASE").

        B.      The provisions of this Work Letter shall apply to the initial
Tenant Improvement Work (as such term is hereinafter defined) planned by Tenant
for the various components of the Second Amendment Premises described in
Sections 2.8, 2.9, and 2.10 of the Lease (each, a "BUILD-OUT SITE," and
collectively, the "BUILD-OUT SITES"). The Tenant Improvement Work will be
performed in stages as Tenant prepares to renovate and occupy each Build-Out
Site. As a result, the provisions of this Work Letter will be applied to each
Build-Out Site as Tenant plans and accomplishes the Tenant Improvement Work for
such Site.

        Now, therefore, in consideration of these premises and for other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:



                                    ARTICLE 1
                              GENERAL REQUIREMENTS


        1.1     Tenant Improvement Work. Planning, construction, and payment for
the Tenant Improvement Work shall be carried out in accordance with the terms
and conditions of the Lease and this Work Letter. To the extent this Work Letter
and the Lease are in conflict, the terms of this Work Letter shall prevail.

        1.2     Architect. Tenant shall retain the services of a fully qualified
laboratory and office architect ("ARCHITECT") licensed in the State of
Washington, who shall be responsible for the preparation of fully detailed
working drawings and specifications (the "TENANT IMPROVEMENT PLANS") from which
the Tenant Improve-



<PAGE>   24
ment Work shall be constructed. Tenant shall be responsible for directing
Architect in the preparation of the Tenant Improvement Plans and Architect shall
be employed by Tenant. Tenant's selection of Architect, Contractor (as such term
is defined below), and major subcontractors shall be subject to the written
approval of Landlord and, if applicable, Landlord's lender. Landlord hereby
approves in advance Tenant's use of Mahlum & Norfors McKinley Gordon as
Architect and DPR as Contractor. At Landlord's request from time to time,
meetings shall be held and attended by Tenant, Architect, Contractor, and any
other tenant improvement consultants selected by Tenant, to discuss with
Landlord the construction of the Tenant Improvement Work.

        1.3     Tenant Improvement Plans. Contractor shall prepare and deliver
to Landlord, at the same time the Tenant Improvement Plans are delivered to
Landlord, a detailed time schedule for the Tenant Improvement Work in form and
substance acceptable to Landlord. Such schedule shall include the earliest and
latest anticipated dates of completion of the Tenant Improvement Work.

        1.4     Approval of the Tenant Improvement Plans.

                1.4.1   The design, quality of materials, and installations
undertaken in the Second Amendment Premises pursuant to the Tenant Improvement
Plans shall be subject to the prior written approval of Landlord and, if
applicable, Landlord's lender, and shall conform to and meet all applicable
city, county, state, and federal laws, and all building codes, rules, and
regulations, and shall meet or exceed all guidelines, standards, and
recommendations prepared and issued by all other government authorities having
jurisdiction over or other control of the development and use of laboratory and
office space of the type to be constructed within the Second Amendment Premises.

                1.4.2   Landlord shall review and approve or disapprove the
Tenant Improvement Plans in writing within ten (10) business days after
Landlord's receipt of such documents from Architect (together with the detailed
time schedule from Contractor). Landlord shall be responsible, at its sole
expense, for the cost of reviewing the Tenant Improvement Plans. If Landlord
disapproves any portion of the Tenant Improvement Plans, then Landlord shall
specifically: (a) approve those portions which are acceptable to Landlord; and
(b) disapprove those portions which are not acceptable to Landlord, specifying
the reasons for such disapproval and describing in reasonable detail the change
Landlord requests for each item disapproved.


                                       2
<PAGE>   25
                1.4.3   Landlord shall have full access to the Tenant
Improvement Plans during the course of the Tenant Improvement Work. Any changes,
modifications, improvements, amendments, additions, supplements, or alterations
(collectively, "CHANGES") to the Tenant Improvement Plans which Landlord may
consider necessary in order to protect its or other tenants' interests in the
Research Complex shall be conveyed to Tenant who shall instruct Architect to
make said Changes.

                1.4.4   Where final Tenant Improvement Plans approved by
Landlord in writing conflict with this Work Letter or the Lease, the provisions
of the final Landlord-approved Tenant Improvement Plans shall prevail.

        1.5     Permits for the Tenant Improvement Work. Tenant or Architect
shall be responsible for obtaining all necessary building and other permits,
licenses, and approvals (collectively, "PERMITS") relating to the Tenant
Improvement Work from the applicable governing agencies. If any such governing
agency shall reject the Tenant Improvement Work and thereby prevent the issuance
of a Permit, Tenant shall immediately take such action and make all necessary
corrections to the Tenant Improvement Plans required by said agencies and
approved by Landlord in writing. Upon said agency's approval of Tenant's Permit
applications, Tenant or Architect shall obtain the Permits from said agency and
deliver a copy of the same to Landlord.

        1.6     Construction of the Tenant Improvement Work.

                1.6.1   Tenant agrees, as soon as practical after receipt of the
required Permits therefor and after obtaining access to the respective Build-Out
Sites, to diligently and continuously prosecute the Tenant Improvement Work to
completion in accordance with the final Landlord-approved Tenant Improvement
Plans, and in accordance with all city, county, state, and federal laws,
ordinances, rules, and regulations relating thereto.

                1.6.2   Commencing on the date Tenant begins the Tenant
Improvement Work on a Build-Out Site, Tenant shall indemnify and hold Landlord
harmless from any loss of or damage to Tenant's or Contractor's property,
completed work, fixtures, equipment, materials, or merchandise, and from
liability for death of or injury to any person except as caused by the willful
misconduct or gross negligence of Landlord.


                                       3
<PAGE>   26
                1.6.3   Tenant agrees that except for any available Second
Amendment Allowance, Landlord neither assumes nor shall bear any cost for the
Tenant Improvement Work.

                1.6.4   Tenant shall deliver a completed City of Seattle
sign-off inspection card and an original Certificate of Occupancy to Landlord
prior to opening for business any Build-Out Site.

        1.7     Changes to the Tenant Improvement Work.

                1.7.1   Tenant shall notify Landlord in writing of any requested
Changes to the Tenant Improvement Work, describing in detail the nature and
extent of any such Change. If the nature of such Changes requires revisions to
the Tenant Improvement Plans, then Architect shall revise the Tenant Improvement
Plans and deliver a revised set of the affected portion of the Tenant
Improvement Plans to Landlord for Landlord's review and approval or disapproval
as provided below.

                1.7.2   Material changes to the Tenant Improvement Work (each a
"MATERIAL Change") are Changes that: (a) alter any of the structural portions of
the Building including, without limitation, a load bearing wall, the roof, the
foundation, or the floor slabs; (b) alter the function of the mechanical,
electrical, heating, ventilation, air conditioning, plumbing, or other systems
of the Building; (c) exceed $5,000.00 in cost for a single Change; or (d) are
visible from the Common Area of the Research Complex. Landlord shall review and
approve or disapprove in writing Material Changes within ten (10) business days
of the written receipt from Tenant of the requested Material Changes. Landlord
shall review and approve or disapprove in writing all other Changes within five
(5) business days of the written receipt from Tenant of the requested Change.

                1.7.3   Tenant shall reimburse Landlord for all reasonable and
actual fees incurred by Landlord in connection with its third party consultants
reviewing Charges and Material Changes to the Tenant Improvement Plans.

        1.8     Diligence. Landlord and Tenant agree that each shall use due
diligence in performing their respective obligations pursuant to this Work
Letter.


                                       4
<PAGE>   27
                                    ARTICLE 2
                           THE TENANT IMPROVEMENT WORK


        2.1     General. "The Tenant Improvement Work" shall include the
demolition, construction, purchase, and installation of all of the items of a
permanent or fixed nature described in the final Landlord-approved Tenant
Improvement Plans.

        2.2     The Tenant Improvement Work. Tenant shall cause the Tenant
Improvement Work to be performed in a good and workman like manner and in
accordance with Section 1.6.1 above. At completion of each phase of the Tenant
Improvement Work, Tenant shall provide Landlord with complete as-built plans of
the Tenant Improvement Work.

        2.3     Equipment and Furnishing. Tenant shall be responsible for the
placement within the Build-Out Sites of the personal property of Tenant. Tenant
shall purchase and install, at Tenant's sole expense, which shall not be
reimbursable from the Second Amendment Allowance, all equipment, furnishings,
and other personal property required by Tenant in the operation of its business,
other than the improvements described in the final Landlord-approved Tenant
Improvement Plans.

        2.4     Removal of Waste. During the Tenant Improvement Work, Contractor
shall promptly remove all related trash and debris to Contractor supplied trash
receptacles. Tenant shall not permit disposal of such waste material into the
Research Complex's trash receptacles.


                                      ARTICLE 3
                         THE TENANT IMPROVEMENT WORK BUDGET


        3.1     Budget for the Tenant Improvement Work.

                3.1.1   Tenant shall submit to Landlord for its review and
approval, prior to commencing construction of any Tenant Improvement Work, a
specific line item budget of the cost to complete such Tenant Improvement Work
(the "BUDGET") prepared by Contractor or Tenant and certified by Architect.


                3.1.2   Tenant shall provide a copy of the fully executed
construction contract for the Tenant Improvement Work between Tenant and
Contractor to Landlord.


                                       5
<PAGE>   28
                                    ARTICLE 4
                          TENANT'S USE OF A CONTRACTOR


        4.1     Contractor Selection. Contractor must be bondable and meet all
licensing and insurance requirements established by the State of Washington and
the City of Seattle, and have in force a general liability insurance policy of
not less than $2,000,000.00 or such higher limits as Landlord may reasonably
request, which policy of insurance shall name Landlord as an additional insured.
During the construction of any Tenant Improvement Work, Tenant shall provide or
cause Contractor to provide all-risk builder's insurance in such form and amount
as is required by Landlord. Tenant shall provide Landlord with certificates of
insurance naming Landlord as an additional insured prior to the commencement of
the Tenant Improvement Work. At the request of Landlord, Tenant shall also
provide Landlord with a copy of Contractor's most recent financial statements
and proof of bondability.

        4.2     Special Conditions. Tenant shall incorporate into the contract
with Contractor the following items as "Special Conditions:"

                4.2.1   Contractor shall diligently perform its work in a manner
and at times which do not unreasonably impede or delay any other work at the
Building.

                4.2.2   Contractor shall be responsible for the repair,
replacement, and clean-up of any damage caused by Contractor at or to the Second
Amendment Premises, the Building, the Research Complex.

                4.2.3   Except as shown on the final Landlord-approved Tenant
Improvement Plans, Contractor shall: (a) obtain written approval from Landlord
prior to penetrating any structural portion of the Building including, without
limitation, any floor slab, roof, or load bearing wall; and (b) obtain prior
written approval of such work by a structural engineer acceptable to Landlord.
Landlord's approval shall not relieve Tenant or Contractor from responsibility
for damage to the Building because of any such penetration by Contractor.

                4.2.4   Contractor shall store all construction materials and
contain all operations within the relevant Build-Out Sites and such other space
as Landlord may specifically permit in writing. Contractor shall at all times
avoid interfering with or delaying other work and other tenants at the Research
Complex. All trash, construction debris, and surplus construction materials
shall be promptly removed from the Research Complex by Contractor.

                4.2.5   Contractor shall notify Landlord in advance in writing,
and obtain Landlord's written prior approval: (a) two (2) business days in
advance of any 


                                       6
<PAGE>   29
work to be done on weekends or of any interruption of Building services; and (b)
one (1) business day in advance of any work to be done at other than regular job
hours.


                4.2.6   Contractor shall comply with all applicable federal,
state, and local laws, codes, rules, and regulations governing the performance
of the Tenant Improvement Work, and all applicable regulations established by
Landlord for the Research Complex, including, without limitation, the procedures
for maintenance of air quality during construction set out by Landlord.


                4.2.7   Neither Contractor nor any subcontractors shall post
signs at the Research Complex without first obtaining Landlord's written
consent, except for those necessary for health and safety.


                4.2.8   Work performed by Contractor shall be performed in a
manner so as to avoid any labor dispute which results in a work stoppage or
impairment.


                4.2.9   Access to other tenant's premises are to be scheduled at
least two (2) business days in advance and are to be requested in writing.


                4.2.10  No music, animals, or inappropriate language is allowed
at the Building.


                4.2.11  Construction personnel are to use the entrance,
elevator, or emergency stairs designated by Landlord. Loading of construction
materials, supplies, trash, and office/laboratory equipment shall not exceed the
maximum load requirement for each elevator or floor.


                4.2.12  No construction parking is permitted in the designated
visitor parking stalls, in front of the Building's main entrance, in the loading
dock area, in the designated ambulance space, or in the vehicle area of the
basement of the Building.


                4.2.13  Prior to the use or installation of heavy equipment of
any kind on the Building roof, written review and approval of the proposed
installation by a structural engineer acceptable to Landlord is required.


                                       7
<PAGE>   30
                                    ARTICLE 5
                 TENANT IMPROVEMENT (SECOND AMENDMENT) ALLOWANCE


        5.1     Second Amendment Allowance. Payment to Contractor of portions of
the Second Amendment Allowance shall be made by Landlord subject to Subsections
8.3 and 8.6 of the Lease, and disbursed as provided below. Any additional funds
which may be needed to complete the Tenant Improvement Work, or any work related
thereto, shall be paid by Tenant. Tenant shall provide Landlord with evidence
reasonably acceptable to Landlord of the availability of such additional funds.

        5.2     Disbursements. Payments from the Second Amendment Allowance
shall be made no more frequently than on a monthly basis by Landlord. Payments
shall be released only upon the approval of Architect who shall prepare a
monthly certificate for payment which shall be submitted to Landlord and which
in turn shall be based upon invoices from Contractor and others (including
Architect) for work completed to date and for services or materials provided to
date. The certificate shall be submitted to Landlord at least ten (10) business
days prior to the date the disbursement is requested and shall include: (a)
copies of bills received by Tenant for all sums expended or due; (b) to the
extent applicable, a statement from Architect that states that the Tenant
Improvement Work for which the previous disbursement was made was completed in
accordance with the final Landlord-approved Tenant Improvement Plans; and (c)
such other documentation or information as may be requested by Landlord. All
submittals for payment shall be accompanied by a lien release, conditioned upon
receipt of the applied for payment, executed by Contractor and when applicable,
by subcontractors, suppliers, and others who provided work, services, or
material to the Build-Out Site. At Landlord's option, disbursements may be made
directly to Architect, Contractor, subcontractors, materialmen, laborers, and
other persons planning or performing the Tenant Improvement Work.

                5.2.1   Landlord shall have no obligation to make any
disbursement of the Second Amendment Allowance if the Tenant Improvement Work
shall have been materially injured or damaged by fire or other casualty, unless
Tenant shall demonstrate to landlord's reasonable satisfaction that Tenant has
sufficient funds available to complete the Tenant Improvement Work.

                5.2.2   Landlord shall have the right to decline to make any
requested disbursement if Landlord, in the exercise of its reasonable
discretion, determines that the Tenant Improvement Work with respect to which
the disbursement has been requested has not been constructed substantially in
accordance with the final 

                                       8
<PAGE>   31
Landlord-approved Tenant Improvement Plans and as otherwise required by this 
Work Letter or the Lease.

                5.2.3   Landlord shall have no obligation to make a disbursement
from the Second Amendment Allowance for any Tenant Improvement Work if Landlord
has not received Architect's certificate and the other documentation required
under Section 5.2 above.


        5.3     Outside Date. Any Second Amendment Allowance funds not disbursed
by December 31, 1999, shall remain with Landlord and no longer be available to
Tenant.


                5.3.1   Tenant shall pay for all Tenant Improvement Work costs
in excess of the available Second Amendment Allowance within thirty (30) days of
invoicing by the party providing such work or materials, and shall obtain and
deliver to Landlord unconditional lien releases in connection with such payment.


                5.3.2   Notwithstanding Section 5.3.1, if Tenant is unable to
obtain unconditional lien releases or if any liens are filed against the
Building or the Research Complex as a result of the Tenant Improvement Work,
then within thirty (30) days after completion of the work or immediately after
receipt of notice of any lien, Tenant shall cause the lien or lien rights to be
released of record or to be bonded over by a bond reasonably satisfactory to
Landlord in the amount of 150% of the amount of such lien.

        5.4     Use of Second Amendment Allowance. The Tenant Improvement Work
chargeable against the Second Amendment Allowance may include, in addition to
the cost of construction for work shown on the final Landlord-approved Tenant
Improvement Plans, the cost of space planning, engineering work, and building
permits. Tenant shall be responsible for the cost of the matters described in
Section 2.3 above, which cost shall not be charged against the Second Amendment
Allowance. In addition, the Second Amendment Allowance shall not be used, among
other things, for the following: (a) the purchase of equipment, furnishings, or
other personal property for Tenant or for the Second Amendment Premises; (b)
costs for improvements which are not shown on or described in the final
Landlord-approved Tenant Improvement Plans unless otherwise approved by Landlord
in writing; (c) attorneys' fees and costs incurred by Tenant in connection with
the negotiation of construction contracts, and attorneys' or experts' fees and
costs or other expenses incurred by Tenant in connection with disputes with
Landlord or third parties; (d) costs incurred as a consequence of delay (unless
the delay is caused by 


                                       9
<PAGE>   32
Landlord and excepting any Permitted Delay); (e) construction defects or
defaults caused by Architect, Contractor, or any subcontractor or supplier; (f)
costs recoverable by Tenant on account of warranties or insurance; and (g)
wages, labor, and overhead for Tenant's employees or for overtime or premium
time unless approved by Landlord in writing.

        5.5     Responsibilities. Architect and Tenant shall jointly be
responsible for ensuring that all construction work is carried out by Contractor
in accordance with the final Landlord-approved Tenant Improvement Plans, and
Contractor shall in turn be responsible for the execution of the Tenant
Improvement Work in accordance with the final Landlord-approved Tenant
Improvement Plans and as directed by Architect and Tenant.


                                    ARTICLE 6
                                  MISCELLANEOUS

        6.1     Work Completion. "Substantially Complete" shall mean: (a)
Contractor has completed the Tenant Improvement Work as shown on the final
Landlord-approved Tenant Improvement Plans (subject only to a punch list of
items that do not materially interfere with Tenant's use of the Build-Out Site);
Tenant has obtained a temporary certificate of occupancy or similar occupancy
permit from the City of Seattle or other appropriate governmental agency; or (c)
a substantial completion certificate has been given by Architect to Landlord.

        6.2     Lender Requirements. This Work Letter is subject to any
requirements of Landlord's lender, if any, and Tenant agrees to cooperate with
Landlord in meeting Landlord's lender's requirements and in obtaining said
lender's approvals.

        6.3     Delays. "Permitted Delay" shall mean: (a) the occurrence of a
force majeure such as the unavailability of supplies or strikes by trade groups
necessary for Substantial Completion of work; (b) extraordinary acts of
government that force a general halt of construction at the Building and in the
surrounding vicinity; or (c) governmental or regulatory delays in inspecting or
approving Tenant Improvement Work, in each case beyond the reasonable control of
Tenant.

        6.4     Approvals. In all cases where this Work Letter provides for
approval by Landlord or Tenant, the approval may not be unreasonably withheld or
delayed unless such provision states to the contrary. Except where otherwise
specifically provided, where approval is required, the reviewing party shall
respond within ten 


                                       10
<PAGE>   33
(10) business days, either granting its approval or giving the other party
detailed information as to what is not acceptable and why.


        6.5     Modification. No modification, waiver, or amendment of this Work
Agreement or of any of its conditions or provisions shall be binding upon
Landlord or Tenant unless in a writing signed by Landlord and Tenant.

        6.6     Counterparts. This Work Letter may be executed in any number of
counterparts but all counterparts taken together shall constitute a single
document.

        6.7     Governing Law. This Work Letter shall be governed by, construed,
and enforced in accordance with the laws of the State of Washington.

        6.8     Time of the Essence. Time is of the essence of this Work
Agreement and of each and all of the provisions thereof.

        6.9     Severability. If any term or provision of this Work Letter is
declared invalid or unenforceable, the remainder of this Work Letter shall not
be affected by such determination and shall continue to be valid and
enforceable.

        6.10    Merger. All understanding and agreements, oral or written,
heretofore made between the parties hereto and relating to Landlord's Work are
merged in this Work Letter, which alone (but inclusive of provisions of the
Lease incorporated herein and the final Landlord-approved Tenant Improvement
Plans) fully and completely expresses the agreement between Landlord and Tenant
with regard to the matters set forth in this Work Letter.

        6.11    Liability. Tenant shall indemnify and hold Landlord harmless
from all costs, expenses, losses, claims, liabilities, and damages to the
Research Complex or to the person or property of tenants or guests at the
Research Complex arising in connection with or related to the performance of the
Tenant Improvement Work by Tenant, Contractor, any subcontractor, or
representatives of such parties.

        6.12    Entire Agreement. This Work Letter is made as a part of and
pursuant to the Lease and, together with the Lease, constitutes the entire
agreement of the parties with respect to the subject matter hereof. This Work
Letter is subject to all of the terms and limitation set forth in the Lease, and
neither party shall have any rights or remedies under this Work Letter separate
and apart from their respective remedies pursuant to the Lease.

        6.13    Captions. The headings and captions in this Work Letter are for
purposes of convenience only and shall not be used to modify or interpret any of
the provisions herein.


        IN WITNESS WHEREOF, the parties hereto have executed this Work Letter as
of the date first above written.


                                       11
<PAGE>   34
Landlord:                              Tenant:
Alexandria Real Estate Equities, Inc.  Corixa Corporation
By:_______________________________     By:_______________________________
Name:_____________________________     Name:_____________________________
Its:______________________________     Its:______________________________
                                       


                                       12
<PAGE>   35
                                    EXHIBIT E


                 DIAGRAM OF THE SECOND AMENDMENT BASEMENT SPACE









                                    [drawing]


                                       13