<PAGE>   1

                                                                   EXHIBIT 10.26

                           EXCLUSIVE LICENSE AGREEMENT

     This Exclusive License Agreement (this "Agreement") is made as of this ___
day of July, 1999 (the "Effective Date") by and between Introgen Therapeutics,
Inc., a Texas corporation having its principal place of business at 301 Congress
Avenue, Suite 1850, Austin, Texas 78701 ("Introgen"), Corixa Corporation, a
Delaware corporation having its principal place of business at 1124 Columbia
Street, Suite 200, Seattle, Washington 98104 (the "Company"), and Chinook
Corporation, a Delaware corporation and a wholly-owned subsidiary of the Company
("Chinook," and, collectively with the Company, "Corixa").

                                    RECITALS

     A.   GenQuest, Inc., a Delaware corporation ("GenQuest"), and Introgen
entered into a Special Biological Materials Transfer and Collaboration Agreement
dated February 4, 1998 (the "Prior Agreement"), pursuant to which GenQuest
granted to Introgen (i) an exclusive license to use the Licensed Technology (as
defined below) to conduct the research set forth on Schedule 1 to the Prior
Agreement (the "Research") upon the terms and subject to the conditions of the
Prior Agreement and (ii) an option to obtain an exclusive license to the
Licensed Technology as described in the Prior Agreement (the "Option").

     B.   Effective September 15, 1998, GenQuest was acquired by Corixa by
merger with and into Chinook Corporation, which is wholly owned by Corixa and
was the surviving entity in such merger.

     C.   In satisfaction of the Option, Introgen desires to obtain, and Corixa
is willing to grant to Introgen, an exclusive license to the Licensed
Technology, including the results of the Research, upon the terms and subject to
the conditions of this Agreement.

     NOW, THEREFORE, in consideration of the promises and the mutual covenants
herein set forth, the receipt and sufficiency of which are hereby acknowledged,
the parties hereto agree as follows:

     1.   DEFINITIONS

     In addition to the terms defined elsewhere in this Agreement, the following
words and phrases, whenever capitalized in this Agreement, shall have the
following meanings:

          1.1  "Affiliate" shall mean, with respect to a party, any entity that
controls, is controlled by, or is under common control of a party. For this
purpose, control of an entity shall mean direct or indirect ownership of fifty
percent (50%) or more of the voting interest in, or a fifty percent (50%) or
greater interest in the equity of, such corporation or other business entity, or
the maximum percentage allowed by law in the country of the controlled entity.

          1.2  "Annual Net Sales" shall mean, in each calendar year during the
term of this Agreement, the gross amounts received by Introgen or its Affiliates
in the case of sales by Introgen or its Affiliates to Third Parties (or to
Affiliates that are end users), or the gross amounts received by sublicensees of
Introgen or its Affiliates in the case of sales by such sublicensees to Third
Parties (or to Affiliates that are end users), for sales of Licensed Products to
Third Parties (or to Affiliates that




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are end users) less the following amounts: (a) normal customary trade, quantity,
cash and other discounts allowed and actually taken; (b) allowances for credits
granted for returns, rebates and the like; (c) sales, use, value added and
similar taxes and duties paid; and (d) packaging and handling fees and prepaid
shipping, freight and insurance. For the removal of doubt, Annual Net Sales
shall not include sales by Introgen to its Affiliates for resale, provided that
if Introgen sells a Licensed Product to an Affiliate for resale, Annual Net
Sales shall include the amounts received by such Affiliate to Third Parties on
the resale of such Licensed Product. Notwithstanding the foregoing, Annual Net
Sales shall not include amounts received in consideration of a transfer or sale
of reasonable quantities of Licensed Products for use in research and
development or in clinical trials.

          1.3  "Combination Product" shall mean any subject matter, including,
but not limited to, products and processes, containing both a component that
constitutes a Licensed Product and one or more devices or active components that
would not alone constitute Licensed Products.

          1.4  "Fair Market Value," with respect to equity securities, shall
mean a price per share of not greater than [*] of, (a) if such securities are
traded on a securities exchange or The Nasdaq Stock Market, the average of the
closing prices over the ten (10) trading days preceding the date of calculation,
(b) if such securities are actively traded over-the-counter, the average of the
closing bid or sales price (whichever is applicable) over the ten (10) trading
days preceding the date of calculation and (c) if such securities are not so
traded, the fair market value as determined in good faith by the Board of
Directors of the issuer, with due consideration given to the potential earnings,
business and prospects of such issuer and the price at which other equity
securities of the issuer have been issued.

          1.5  "Field" shall mean [*]. Notwithstanding the foregoing, the Field
shall not include any administration of the Licensed Gene or Gene Products in
any formulation for the primary purpose of [*].

          1.6  "Gene Products" shall mean any and all peptide(s) and protein(s)
encoded by the Licensed Gene, any derivatives of such peptide(s) and protein(s),
and antibodies to such protein(s) and derivatives.

          1.7  "Licensed Gene" shall mean the MDA-7 gene and any fragments or
derivatives thereof, as and to the extent covered by the Licensed Patents.

          1.8  "Licensed Know-How" shall mean any and all technical information,
processes, compositions, formulae, data, engineering, materials, reports,
analyses, know-how, trade secrets and other subject matter owned and/or
controlled by Corixa relating directly and specifically to the Licensed Gene and
that is reasonably necessary for the development, manufacture and/or
commercialization of the Licensed Products in the Field.

          1.9  "Licensed Patents" shall mean any and all rights owned and/or
controlled by Corixa in and to:

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             separately with the Commission. Confidential treatment has been
             requested with respect to the omitted portions.


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               (a)  all worldwide patents and patent applications owned or
controlled by Corixa or its Affiliates claiming or disclosing the subject matter
claimed or disclosed in those patent applications listed on Exhibit 1.9 hereto
or in any foreign counterpart of the foregoing;

               (b)  all worldwide patents and patent applications claiming or
disclosing inventions owned or controlled by Corixa or its Affiliates relating
to the MDA-7 gene of any fragment or derivatives thereof that are made prior to
the second anniversary of the Effective Date; and

               (c)  all divisions, continuations, continuations-in-part, foreign
counterparts, patents of addition, and substitutions of, and all patents issuing
on, any of the foregoing patents, together with all registrations, reissues,
reexaminations or extensions of any kind with respect to any of the foregoing
patents.

          1.10 "Licensed Technology" shall mean, collectively, (a) the Licensed
Gene, (b) the Licensed Patents and (c) the Licensed Know-How.

          1.11 "Licensed Products" shall mean any product, composition or
material the manufacture, sale or use of which would, but for the license
granted herein, infringe a Valid Claim in the country for which such product,
composition or material is sold.

          1.12 "Major Indication" shall mean any indication in humans for which
the parties mutually agree that at least [*] patients exist in the
United States.

          1.13 "Major Market" shall mean any one of the following: [*].

          1.14 "Market Launch" shall mean the date on which Introgen or an
Affiliate in the case of sales by Introgen or its Affiliates to Third Parties
(or to an Affiliate that is an end-user) or a sublicensee of Introgen or any of
its Affiliates in the case of sales by such sublicensee to Third Parties (or to
an Affiliate that is an end-user), first transfers title to or otherwise sells a
Licensed Product to a Third Party in exchange for revenue. The transfer of a
reasonable amount of Licensed Products intended for clinical use or for research
or other non-commercial use shall not be included in the calculation of the date
of Market Launch.

          1.15 "Net Licensing Proceeds" shall mean the license fees received by
Introgen from a sublicensee in consideration of a sublicense under the Licensed
Technology, including up-front license fees, sublicense fees and technology
access fees, and all milestone payments so received, less (i) any applicable
withholding taxes and any other amounts credited or deducted against the amounts
actually received by Introgen, unless and until Introgen recoups such taxes or
charges through a credit against taxes due or against other cash payments that
Introgen otherwise would be required to make, and (ii) any amounts paid to a
Third Party (including without limitation the Fair Market Value as of the date
of issuance of any equity issued to such Third Party to the extent that such
equity is issued as a license fee and is not purchased for other consideration
by such Third Party) with respect to the license, sublicense or acquisition of
additional intellectual property rights and relating to a Licensed Product
covered by such sublicense agreement. Net Licensing Proceeds

         [*] Certain information on this page has been omitted and filed
             separately with the Commission. Confidential treatment has been
             requested with respect to the omitted portions.


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shall not include (a) any equity or amounts received as payment for equity
securities (up to the Fair Market Value of such securities as of the date of
issuance), (b) any amounts received in direct connection with the sale or
provision of products or materials or services or (c) any amounts received in
consideration of bona fide research or development activities. For the avoidance
of doubt, it is understood that in no event shall Net Licensing Proceeds be
deemed to include Annual Net Sales, running royalties or any amount other than
cash payments expressly included above in this Section 1.15; nor shall Net
Licensing Proceeds be deemed to include amounts received in consideration for a
sale of all or substantially all of the business or assets of Introgen to which
this Agreement pertains (whether by way of merger, sale of stock, sale of assets
or otherwise) or in connection with any other transaction resulting in an
assignment of this Agreement in accordance with Section 13.3.

          1.16 "Regulatory Authority" shall mean the U.S. Food and Drug
Administration or its foreign equivalent.

          1.17 "Third Party" shall mean a party other than Introgen, Corixa or
either of their Affiliates.

          1.18 "Valid Claim" shall mean a claim of an issued and unexpired
patent or a claim of a pending patent application within the Joint Patents or
the Licensed Patents which has not been held unpatentable, invalid or
unenforceable by a court or other government agency of competent jurisdiction
and has not been admitted to be invalid or unenforceable through reissue,
re-examination, disclaimer or otherwise; provided, however, that if the holding
of such court or agency is later reversed by a court or agency with overriding
authority, the claim shall be reinstated as a Valid Claim with respect to Annual
Net Sales made after the date of such reversal.

          1.19 "Singular and Plural". Where the context hereto requires, the
singular number shall be deemed to include the plural and vice versa.

     2.   LICENSE GRANT; SUMMARY DATA

          2.1  Exclusive License. Corixa hereby grants to Introgen an exclusive,
worldwide license, with the right to sublicense under the Licensed Technology
solely to research, make, have made, use, sell, offer to sell, have sold, import
and otherwise distribute Licensed Products, practice any method, process or
procedure, or otherwise exploit the Licensed Technology; provided that such
license shall in each case be limited to the Field (the "Exclusive License").

          2.2  Sublicensing. Introgen may grant and authorize sublicenses within
the scope of the Exclusive License. Introgen shall keep Corixa reasonably
informed as to its progress in entering into sublicense agreements. Each such
sublicense agreement shall comply with the terms and conditions of this
Agreement.

          2.3  Summary Data. During the term of this Agreement, Introgen will
supply Corixa with summary data pertaining to research, development and uses of
the Licensed Technology, including, without limitation, the Licensed Products,
in the Field. The type and frequency of the disclosure of such summary data
shall be mutually agreed upon by the parties. Such summary data shall be
considered Confidential Information of Introgen under Section 8 of this
Agreement.

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          2.4  Supply of Materials. Upon reasonable request by Introgen and in
consideration for the research and development payments set forth in Section
4.3, Corixa shall provide reasonable quantities of the materials, reagents and
other items within the Licensed Technology listed on Exhibit A attached hereto.
Such reagents shall be delivered subject to the Terms and Conditions of Purchase
and Supply of Reagents attached hereto as Exhibit B.

          2.5  Notwithstanding any provision in this Agreement to the contrary,
Corixa shall not assert against Introgen or a Licensed Product any patent now or
hereafter obtained or controlled by Corixa or its Affiliate, solely to the
extent that such patent claims cover the Licensed Gene or Gene Products, or the
use or production thereof.

     3.   DUE DILIGENCE; RESEARCH PROGRAM

          3.1  Due Diligence. Introgen shall use diligent efforts (itself or
through others) to achieve the following milestones for the Licensed Products
within the specified number of months after the Effective Date:

<TABLE>
<CAPTION>

                 ----------------------------------------------- ------------------------------------------

                 EVENT                                                MONTHS AFTER THE EFFECTIVE DATE
                 ----------------------------------------------- ------------------------------------------
<S>                                                               <C>
                 (a) Acquisition or development of                                  [*]
                 [*] either internally or through a
                 funded collaboration with a Third Party,
                 reasonably sufficient to enable Introgen to
                 deliver Licensed Technology for [*].
                 ----------------------------------------------- ------------------------------------------
                 (b) Completion of [*] in an                                        [*]
                 animal model using [*].
                 ----------------------------------------------- ------------------------------------------
                 (c) Commencement of [*] Clinical Trial of                          [*]
                 a Licensed Product for a Major Indication.
                 ----------------------------------------------- ------------------------------------------
                 (d) Completion of [*] Clinical Trial of a                          [*]
                 Licensed Product for a Major Indication.
                 ----------------------------------------------- ------------------------------------------
                 (e) Completion of [*] Clinical Trial of a                          [*]
                 Licensed Product for a Major Indication.
                 ----------------------------------------------- ------------------------------------------
                 (f) Completion of [*] Clinical Trial of a                          [*]
                 Licensed Product for a Major Indication.
                 ----------------------------------------------- ------------------------------------------
</TABLE>

With respect to Introgen's obligations under events (a) and (b) above, the
parties acknowledge that, notwithstanding Introgen's use of diligent efforts,
Introgen may not achieve the event described therein. In such event, so long as
Introgen is conducting research or development activities (directly or through
others) with respect to [*] or using diligent efforts to seek to acquire

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             separately with the Commission. Confidential treatment has been
             requested with respect to the omitted portions.



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[*] to achieve the milestones in (a) and (b) above, Introgen shall not be
considered in breach of same by reason of its failure to achieve such
milestones. In addition, in any event, the sole remedy for any breach by
Introgen of its obligations with respect to (a) and (b) above, shall be that the
Exclusive License granted hereunder shall be converted to a non-exclusive
license with respect to the delivery of the Licensed Genes by means of a
delivery system that does not involve viral vectors or viral particles. In the
event that Corixa shall be obligated or shall elect to make any payments to
Columbia as set forth in Section 6(b) of the Amended and Restated Research and
License Agreement (the "Columbia Agreement") dated July 18, 1997 by and between
GenQuest and The Trustees of Columbia University in the City of New York
("Columbia") and as amended by Paragraph 3 of Amendment No. 1 to the Columbia
Agreement dated March 5, 1999 (including, without limitation, Appendix C) for
failure to achieve, or to extend, its due diligence milestones thereunder,
Introgen shall reimburse Corixa for [*] of such payments at the time Corixa is
obligated to make such payment to Columbia.

     3.2  Research Program.

          (a)  During the term of the Research Program (as set forth below), the
parties shall collaborate with respect to a research program, as described on
Exhibit C attached hereto (the "Research Program"). The Research Program may be
amended from time to time by mutual agreement of the parties, and any such
revised Research Program shall be set forth in writing and attached hereto as
Exhibit C. No material deviation in the subject matter or scope of the Research
Program shall be made without the mutual written agreement of both parties. The
term of the Research Program shall commence on the Effective Date and terminate
on the [*] anniversary of the Effective Date, subject to extension on
mutually agreeable terms and conditions by agreement of the parties; provided,
however, that the Research Program shall terminate effective upon any
termination of this Agreement in accordance with Section 9.

          (b)  Corixa shall keep Introgen reasonably informed as to the progress
and results of the Research Program, including without limitation, submitting to
Introgen biannual written reports within thirty (30) days of the end of each
calendar half year summarizing the research and results obtained therefrom
during the prior six (6) month period relating to the research in connection
with the Research Program. Without limiting the foregoing, Corixa shall promptly
notify Introgen in writing of all discoveries and inventions developed during
the Research Program and, with respect to such discoveries or inventions, either
file a patent application [*] in accordance with Article 12 below or authorize
and cooperate fully to permit Introgen to do so. It is understood and agreed
that Corixa shall expend the funds paid to Corixa by Introgen under Section 4.3
solely to conduct the Research Program, subject to Section 9.4 below.

     4.   FEES AND PAYMENTS

          4.1  License Fee. In consideration of the Exclusive License, within
five (5) days of the Effective Date Introgen shall pay to Corixa a one-time fee
of [*].

          4.2  Initial Research and Development Payment. In consideration of the
research and development services performed by Corixa prior to the Effective
Date, within five (5) days of

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             separately with the Commission. Confidential treatment has been
             requested with respect to the omitted portions.

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the Effective Date Introgen shall pay to Corixa a one-time fee of [*].

          4.3  Future Research and Development Payments. In consideration of the
research and development services to be performed by Corixa under the Research
Program, Introgen shall pay to Corixa [*] payments in the amount of [*] each,
the first of which shall be due and payable within five (5) days of the
Effective Date and the remainder of which shall be due and payable at the end of
each three-month period thereafter.

          4.4  Milestones; Net Licensing Proceeds; Payments.

               (a)  In further consideration of the Exclusive License, Introgen
shall make the following milestone payments to Corixa with respect to the first
Licensed Product to meet the corresponding milestone event specified below:

                    (i)  [*] within thirty (30) days following the successful
completion by Introgen of the [*] for such Licensed Product for the first Major
Indication that is [*];

                    (ii) [*] within thirty (30) days following the successful
completion by Introgen of the [*] for a Licensed Product for the first Major
Indication that is [*];

                    (iii) [*] within thirty (30) days following the successful
completion by Introgen of the [*] for such Licensed Product for the first Major
Indication that is [*];

                    (iv) [*] within thirty (30) days following the successful
completion by Introgen of the [*] for a Licensed Product for the first Major
Indication that is [*];

                    (v)  [*] within thirty (30) days following the [*] of such
Licensed Product for the first Major Indication that is [*];

                    (vi) [*] within thirty (30) days following the [*] of a
Licensed Product for the first Major Indication that is [*];

                    (vii) [*] within thirty (30) days following the [*] of a
Licensed Product for the first Major Indication that is [*]; and

                    (viii) [*] within thirty (30) days following the [*] of a
Licensed Product for an additional Major Indication that is [*] (each, an
"Additional Major Indication"). It is understood that payments under this
Section 4.2(a)(viii) shall be due for no more than [*]


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             separately with the Commission. Confidential treatment has been
             requested with respect to the omitted portions.


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Additional Major Indications, and, accordingly, the total amount due under this
Section 4.2(a)(viii) shall not exceed [*].

                    For purposes of this Section 4.4, "successful completion"
shall be deemed to occur, with respect to a particular clinical trial for a
Licensed Product, upon the earlier of (i) the dosing of all patients to be
treated in such clinical trial, and completion in all material respects of any
monitoring period, as described in the protocol for such trial, and the
completion of a summary report of such trial by the principal investigator, or
(ii) initiation of a later phase clinical trial for the same Licensed Product.
It is understood that, except as noted in milestone (viii) above, each of the
foregoing milestone payments shall be due only once and that, accordingly, the
total amount to be paid under this Section 4.4(a) shall not exceed [*].

                    (b)  Introgen shall pay to Corixa [*] of all Net Licensing
Proceeds; but in no event shall the aggregate cumulative amount paid under this
Section 4.4(b) exceed [*]. Payment of such amounts shall be made in accordance
with Section 5.1 hereof. [*].

          4.5  Royalties.

                    (a)  Introgen shall pay to Corixa a royalty equal to the
following percentages of Annual Net Sales:

<TABLE>
<CAPTION>

           --------------------------------------------------------- ---------------------------------------------------
                                                                        PERCENTAGE OF ANNUAL NET SALES TO BE
                               ANNUAL NET SALES                                    PAID TO CORIXA
           --------------------------------------------------------- ---------------------------------------------------
<S>                                                                  <C>
           [*]                                                                        [*]
           --------------------------------------------------------- ---------------------------------------------------

           [*]                                                                        [*]
           --------------------------------------------------------- ---------------------------------------------------
</TABLE>

                    (b)  In the event that Annual Net Sales are at least [*]
in the first [*] following Market Launch, then Introgen shall pay to Corixa a
[*], payable along with the royalty payment for the fourth quarter of such year
in accordance with Section 5.1.

          4.6  Credit. [*]

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             separately with the Commission. Confidential treatment has been
             requested with respect to the omitted portions.



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                                      [*]


          4.7  Single Royalty; Non-Royalty Sales. In the event that more than
one Valid Claim(s) within the Licensed Patents is applicable to any Licensed
Product subject to royalties under this Section 4, then only one royalty shall
be paid to Corixa in respect of such Licensed Product. It is understood that
royalties shall only be payable under this Section 4 with respect to sales of
Licensed Products that would, but for the license granted hereunder, infringe a
Valid Claim in the country in which such Licensed Product is sold or
manufactured. In no event shall more than one royalty be due hereunder with
respect to any Licensed Product unit.

          4.8  Combination Products. For purposes of calculating the amounts due
under this Section 4 for Combination Products, Annual Net Sales shall be
reasonably allocated between such Licensed Product and the device or active
component(s) of such Combination Product that do not constitute Licensed
Products based upon their relative importance and proprietary protection and the
gross selling price of such device or active component(s) sold separately;
provided, however, that in no event shall less than [*] of the Annual Net Sales
of a Combination Product be allocated to the Licensed Product. Similarly, in the
event that a Combination Product is sublicensed without a separate license fee,
then, for purposes of determining Net Licensing Proceeds, the license fees paid
for the Combination Product shall be reasonably allocated between the Licensed
Product and such other subject matter; provided, however, that in no event shall
less than [*] of the Net Licensing Proceeds of a Combination Product be
allocated to the Licensed Product.

     5.   PAYMENTS AND REPORTS

          5.1  Payments and Reports. The payments required pursuant to Sections
4.4(b) and 4.5 shall be paid on a quarterly basis, and shall be due and payable
within forty-five (45) days after the last day of March, June, September and
December of each year. All amounts past due shall bear interest at an annual
rate of [*] from the date they are due until the date they are paid. Each such
payment shall be accompanied by a statement, in sufficient detail describing the
Annual Net Sales invoiced, Net Licensing Proceeds received, the Licensed
Products sold, the amount of Licensed Product sold and the basis for calculating
the accrued royalties. All information provided by Introgen pursuant to this
Section 5.1 shall be deemed Confidential Information of Introgen.

          5.2  Calculation of Payment. The calculation of the payments required
hereunder shall be based on Annual Net Sales and Net Licensing Proceeds in U.S.
Dollars. Annual Net Sales or Net Licensing Proceeds paid in any foreign currency
shall be converted into and paid on the basis of an average rate of exchange,
which shall be computed as the rate of exchange quoted under Foreign Exchange in
The Wall Street Journal (U.S. West Coast edition) for the last business day of
the calendar quarter to which such payment pertains. If at any time legal
restrictions in a particular country prevent the prompt remittance of any
amounts from such jurisdiction, Introgen may make such payments with respect to
such jurisdiction by depositing the amount thereof in local currency in


         [*]    Certain information on this page has been omitted and filed
                separately with the Commission. Confidential treatment has been
                requested with respect to the omitted portions.




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a bank account or other depository in such country in the name of Corixa, and
Introgen shall have no further obligations under this Agreement with respect
thereto.

          5.3  Payment of Applicable Taxes. Each party shall bear and pay any
and all taxes, duties, levies, and other similar charges (and any related
interests and penalties), however designated, imposed on that party as a result
of the existence or operation of this Agreement.

          5.4  Records. Introgen shall keep full, complete and proper records
and accounts of Annual Net Sales and Net Licensing Proceeds. Upon reasonable
notice to Introgen, Corixa shall have the right to have an independent certified
public accountant, selected by Corixa and acceptable to Introgen, audit
Introgen's records pertaining to the Licensed Products during normal business
hours to verify the amounts payable pursuant to this Agreement; provided,
however, that: (a) such audit shall not take place more frequently than once
each calendar year, and (b) shall not cover such records for more than the
preceding three (3) years. The independent certified public accountant will be
obliged to execute a reasonable confidentiality agreement prior to commencing
any such inspection. Such audit shall be at Corixa's expense unless Introgen has
paid Corixa less than ninety-two and a half percent (92.5%) of the amount
determined to be due for the time period covered by such audit, in which case
such audit shall be at Introgen's expense. Introgen shall preserve and maintain
all such records and accounts required for audit for a period of at least three
(3) years after the quarter to which such records and accounts apply.

     6.   OWNERSHIP OF INTELLECTUAL PROPERTY

          6.1  Acknowledgement. The parties hereby acknowledge that except as
expressly set forth herein, neither party shall receive any right, title or
interest to any proprietary rights or intellectual property rights of the other
party.

          6.2  Corixa Inventions. All inventions, discoveries and improvements
("Inventions") related to the Licensed Technology, whether or not patentable,
made solely by employees or others acting on behalf of Corixa during the term of
this Agreement ("Corixa Inventions") shall be owned solely and exclusively by
Corixa. For purposes of this Article 6, an Invention shall be deemed "made" by
an individual if such individual would be the inventor thereof under applicable
patent law (or the author or creator thereof under applicable intellectual
property law, for non-patentable inventions).

          6.3  Introgen Inventions. All Inventions related to the Licensed
Products or based in whole or in part upon any Licensed Technology in the Field,
whether or not patentable, made solely by employees or others acting on behalf
of Introgen during the term of this Agreement ("Introgen Inventions") shall be
owned solely and exclusively by Introgen.

          6.4  Joint Inventions and Joint Patents.

               (a)  Joint Inventions. All Inventions related to Licensed
Technology in the Field, whether or not patentable, made jointly by employees or
others acting on behalf of Introgen and Corixa during the term of this Agreement
("Joint Inventions"), shall be jointly owned by Introgen and Corixa under United
States federal laws pertaining to joint ownership of inventions. All of Corixa's
right, title and


                                      -10-
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interest in the Joint Inventions (other than Corixa's right, title and interest
in the Joint Patents, as defined below) shall be considered part of Licensed
Know-How. Each party shall promptly disclose in writing the existence of Joint
Inventions to the other party.

               (b)  Joint Patents; License Grant. All patents and patent
applications covering Joint Inventions, including without limitation all patents
and/or patent applications arising during or after the term of this Agreement
which claim the priority of any patent and/or patent application claiming and
disclosing Joint Inventions ("Joint Patents"), shall be jointly owned by
Introgen and Corixa under United States federal laws pertaining to joint
ownership of patents. Corixa hereby grants to Introgen an exclusive, worldwide
license, with right of sublicense, to all of Corixa's right, title and interest
in the Joint Patents, to develop, make, have made, use, sell, have sold, import
and otherwise distribute Licensed Products within the Field. Introgen shall have
the first right, but not the obligation, to prosecute and reasonably maintain
the Joint Patents to effectively cover discoveries and inventions relating to
the Field. All costs and expenses incurred in such prosecution will be borne by
Introgen. In the event that Introgen decides not to continue the prosecution or
maintenance of any Joint Patent in general or in any particular country,
Introgen will promptly notify Corixa in writing in reasonably sufficient time
for Corixa to assume such prosecution or maintenance, and Introgen will take the
necessary steps and execute the necessary documents to permit Corixa to assume
such prosecution or maintenance. Corixa will have the right but not the
obligation to assume such prosecution or maintenance at its own expense. At the
request of the party performing the prosecution of any patent application under
this Section 6.4(b), the other party will cooperate, in all reasonable ways, in
connection with the prosecution and maintenance of all such patent applications.
Each party will make available to the other party or its respective authorized
attorneys, agents or representatives such of its employees as the other party in
its reasonable judgment deems necessary in order to assist such other party with
the prosecution and maintenance of such patents. Each party will sign or use its
best efforts to have signed at no charge to the other party all legal documents
necessary in connection with such prosecution and maintenance. Upon request,
each party shall advise the other promptly of any action or development in the
prosecution of Joint Patents, including without limitation those involving the
question of scope or the issuance of, the rejection of, an interference
involving, or an opposition to any such patent application or patent.
Additionally, each party shall provide the other party copies of all such
patents and draft patent applications to be filed by such party on Joint
Inventions, and the other party shall have the opportunity to review all such
pending applications and other proceedings and make recommendations to the
filing party concerning them and their conduct.

     7.   PATENT INFRINGEMENT AND ENFORCEMENT

          7.1  Defense. If the development, manufacture, sale or use of any
Licensed Product within the Field pursuant to this Agreement results in a claim,
suit or proceeding alleging patent infringement against Introgen, its Affiliates
or any of its or any of its Affiliates' suppliers, sublicensees, distributors,
or customers (collectively, "Actions"), Introgen shall promptly notify Corixa
and send Corixa copies of all papers that have been served, to the extent
Introgen has the right to do so. As between the parties to this Agreement,
Introgen shall be entitled to control the defense of such Action and Corixa
shall, and Corixa shall cause its Affiliates to, at all times cooperate with
Introgen. In the event of any such Action relating to the portion of the coding
region of the Licensed Gene that codes for any portion of the Gene Product,
Introgen shall have the right to withhold [*] of the amounts otherwise payable
to Corixa under Article 4 with respect to the Licensed Products that are the
subject of such Action, and use the withheld amounts to reimburse


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                requested with respect to the omitted portions.





                                      -11-
<PAGE>   12

up to [*] of the legal defense costs, attorneys' fees and liability
incurred in such Actions. Notwithstanding the foregoing, Introgen agrees to
withhold only that portion of such amounts as may be reasonably necessary to
reimburse amounts in accordance with this Section 7.1. [*]

          7.2  Infringement. If during the term of this Agreement, either party
becomes aware of a third party infringement or threatened infringement of any
Licensed Patents, the following provisions shall apply:

               (a)  Introgen shall have the right, but not the obligation, to
bring suit (itself or through a designee) to enforce the Licensed Patents,
and/or to defend any declaratory judgment action with respect thereto, in each
case with respect to the manufacture, sale or use of a product within the Field;
provided, however, that Introgen shall keep Corixa reasonably informed as to the
defense and/or settlement of such action. Corixa shall have the right to
participate in any such action with counsel of its own choice at its own
expense. Without limiting the provisions of Section 7.3 below, Corixa agrees to
cooperate with Introgen with respect to actions brought by Introgen under this
Section 7.2(a) at Introgen's request and expense. If Introgen decides to
undertake such suit, then [*] received by Introgen in such Action with
respect to infringement that occurred prior to the judgment awarding such
amounts shall be [*].

               (b)  If Introgen elects not to so initiate an action to enforce
the Licensed Patents against a commercially significant infringement by a Third
Party within the Field, within one hundred eighty (180) days of a request by
Corixa to do so, Corixa may initiate such action at its expense; provided,
however, that Corixa shall keep Introgen reasonably informed as to the defense
and/or settlement of such action, as requested from time to time by Introgen,
and provided that there is not then ongoing a litigation in any country with
respect to the Licensed Technology. Introgen shall have the right to participate
in any such action with counsel of its own choice at its own expense. Introgen
agrees to cooperate with Corixa with respect to actions brought by Corixa under
this Section 7.2(b) at Corixa's request and expense. If Corixa undertakes such
suit, then, after deducting the costs incurred by Corixa in connection with such
Action, Introgen shall be entitled to receive [*] of any amounts received by
Corixa in such action.

               (c)  Upon Introgen's reasonable request, Corixa agrees to use
reasonable efforts, including, but not limited to, with respect to the exercise
of rights under the Columbia Agreement (as defined in Section 10.1) to cause
Columbia (as defined in Section 10.1) to cooperate in any suit, action or other
proceeding under this Section 7.2, at Introgen's expense.

          7.3  Cooperation. In any suit, action or other proceeding in
connection with enforcement and/or defense of the Licensed Patents, the party
not bringing such suit, action or proceeding shall cooperate fully, at the other
party's expense, including without limitation by joining as a party plaintiff
and executing such documents as the other party may reasonably request. Upon the
request of and at the expense of the party bringing such suit, the other party
shall use reasonable efforts to make available at reasonable times and under
appropriate conditions all relevant personnel,


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                                      -12-
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records, papers, information, samples, specimens and other similar materials in
such party's possession.

          7.4  Settlement. Neither party shall be permitted to settle a legal
action, to the extent such settlement expressly admits that the Licensed Patents
are invalid, without the consent of the other party, which consent shall not be
unreasonably withheld.

     8.   CONFIDENTIALITY

          8.1  Definition of Confidential Information. It is contemplated that
in the course of the performance of this Agreement each party may, from time to
time, disclose proprietary and confidential information to the other
("Confidential Information"). Confidential Information shall include all
disclosures made hereunder or under previous confidentiality agreements between
the Parties in writing and identified as being "Confidential," or if disclosed
orally, which are reduced to writing within thirty (30) days of oral disclosure
and clearly identified as being "Confidential." Introgen and Corixa agree that
this Agreement shall supersede all previous confidentiality agreements between
the parties and all disclosures made under any previous confidentiality
agreements shall be subject to the terms of this Section 8.

          8.2  Nondisclosure of Confidential Information. Except to the extent
expressly authorized by this Agreement or otherwise agreed to in writing, during
the term of this Agreement and for a period of five (5) years following the
termination of this Agreement, each party shall take such reasonable measures to
protect the secrecy of and avoid disclosure or use of such Confidential
Information of the other party in order to prevent it from falling into the
public domain or the possession or person other than those persons authorized
under this Agreement to have any such information. Such measures shall include,
but not be limited to, the highest degree of care the receiving party takes to
protect its own proprietary and confidential information of a similar nature,
which shall be no less than reasonable care. Neither party shall disclose or
permit disclosure of any Confidential Information of the other party to third
parties or to employees of the party receiving Confidential Information, other
than directors, officers, employees, consultants and agents who are required to
have the information in order to carry out the terms of this Agreement and who
are bound by appropriate confidentiality restrictions. Each party shall notify
the other in writing of any actual or suspected misuse, misappropriation or
unauthorized disclosure of the other party's Confidential Information that may
come to such party's attention.

          8.3  Exceptions. The following information shall not be considered
Confidential Information:

                    (a)  information which was already known to the receiving
party, other than under an obligation of confidentiality to the disclosing
party, at the time of disclosure by the other party;

                    (b)  information which was generally available to the public
or otherwise part of the public domain at the time of its disclosure to the
receiving party;

                    (c)  information which becomes generally available to the
public or otherwise part of the public domain after its disclosure and other
than through any act or omission of the receiving party in breach of this
Agreement;

                                      -13-
<PAGE>   14

                    (d)  information which was disclosed to the receiving party,
other than under an obligation of confidentiality, by a third party who had no
obligation to the disclosing party not to disclose such information; or

                    (e)  information which was developed independently without
reference to Confidential Information received from the other party hereunder as
evidenced by the receiving party's own written records.

          8.4  Permitted Usage. Notwithstanding the provisions of Section 8.1
above, the receiving party may use or disclose Confidential Information of the
disclosing party in connection with the exercise of its rights hereunder
(including commercialization and/or sublicensing) or the fulfillment of its
obligations and/or duties hereunder and in filing for, prosecuting or
maintaining any proprietary rights, prosecuting or defending litigation,
complying with applicable governmental regulations and/or submitting information
to tax or other governmental authorities; provided that if the receiving party
is required by law to make any public disclosures of Confidential Information of
the disclosing party, to the extent it may legally do so, it shall give
reasonable advance notice to the disclosing party of such disclosure and shall
use its reasonable efforts to secure confidential treatment of Confidential
Information prior to its disclosure (whether through protective orders or
otherwise).

     9.   TERM/TERMINATION

          9.1  Term and Expiration. Unless earlier terminated pursuant to this
Article 9 the term of this Agreement shall expire upon the expiration of the
last to expire patent of the Licensed Patents. Sections 2.1 and 2.2 shall, with
respect to the Licensed Know-How, survive the expiration (but not an earlier
termination) of this Agreement.

          9.2  Termination For Material Breach. In the event of a material
breach of this Agreement, the nonbreaching party shall be entitled to terminate
this Agreement by written notice to the breaching party, if such breach is not
cured within ninety (90) days after written notice is given by the nonbreaching
party to the breaching party specifying the breach. However, if the party
alleged to be in breach of this Agreement disputes such breach within such
ninety (90) day period, the nonbreaching party shall not have the right to
terminate this Agreement unless it has been determined in accordance with
Section 13.9 below that this Agreement was materially breached, and the
breaching party fails to comply with its obligations hereunder within ninety
(90) days after such determination.

          9.3  Termination for Insolvency. Either party may terminate this
Agreement upon written notice to the other in the event of (a) the appointment,
by a court of competent jurisdiction, of a receiver for all or any substantial
part of the other party's properties, provided that such receiver is not
discharged within sixty (60) days of its appointment; (b) the adjudication of
the other party as bankrupt; or (c) the execution by the other party of an
assignment of substantially all of its assets for the benefit of its creditors.

          9.4  Termination Upon Notice. Any provision herein notwithstanding,
Introgen may terminate this Agreement, in its entirety, as to any particular
patent or patent application within the Licensed Patents or as to any particular
Licensed Product, at any time by giving Corixa written



                                      -14-
<PAGE>   15


notice thereof. From and after the effective date of a termination under this
Section 9.4 with respect to a particular patent or application, such patent(s)
and patent application(s) in the particular country shall cease to be within the
Licensed Patents for all purposes of this Agreement, and all rights and
obligations of Introgen with respect to such patent(s) and patent application(s)
shall terminate. From and after the effective date of a termination under this
Section 9.4 with respect to a particular Licensed Product, the Exclusive License
shall terminate with respect to such Licensed Product, and the same shall cease
to be a Licensed Product for all purposes of this Agreement. Upon a termination
of this Agreement in its entirety under this Section 9.4, (a) all rights and
obligations of the parties shall terminate, except as provided in Section 9.9
below and (b) all payments set forth in Sections 4.1, 4.2 and 4.3 shall
accelerate and shall be due and payable to Corixa on the effective date of such
termination.

          9.5  Consequences of Early Termination. If this Agreement is
terminated pursuant to Section 9.2 above, each party shall return or destroy,
and certify to such destruction of, all Confidential Information of the other
party, except that each party may maintain one (1) copy for archival purposes
solely to confirm compliance with the provisions of Section 8.

          9.6  Survival of Sublicenses. Upon termination of this Agreement for
any reason, any sublicense granted by Introgen hereunder shall survive; provided
that, upon request by Corixa, such sublicensee agrees in writing to be bound by
all the applicable terms and conditions of this Agreement.

          9.7  Inclusive Remedy. Except as otherwise provided in this Agreement,
each party shall have the rights and remedies set forth herein in addition to
any other remedies which it may have under applicable statutory or common law.
Each party shall have the sole discretion to determine which of its rights and
remedies, if any, it shall pursue and such party shall not be required to
exhaust any of its other rights or remedies before pursuing any one of the
rights and remedies set forth in this Agreement.

          9.8  Inventory. Upon any termination of this Agreement, Corixa hereby
grants Introgen a license to sell, or otherwise dispose of, any of Introgen's or
its Affiliates' inventories of Licensed Products in process of manufacture, in
use or in stock that have not previously been sold on the date of such
termination, provided that Introgen shall make all applicable royalty or other
payments on such sales pursuant to Section 4 above.

          9.9  Survival. Expiration or early termination of this Agreement shall
not relieve either party of its obligations for payments that were due or
accrued prior to expiration or early termination, included, but not limited to,
any payments due or accrued. In addition, the provisions of Sections 1, 6, 8, 9,
10, 11 and 13 shall survive any expiration or early termination of this
Agreement.

     10.  REPRESENTATIONS AND WARRANTIES

          10.1 By Introgen. Introgen represents and warrants to Corixa that (a)
Introgen has full right and authority to enter into this Agreement, and that
this Agreement is a valid and binding obligation of Introgen enforceable in
accordance with its terms, and (b) Introgen shall use its best commercial
efforts to ensure that all of the Licensed Products manufactured by it or on its
behalf comply with all relevant legislation in force from time to time in each
country where the Licensed



                                      -15-
<PAGE>   16


Products are manufactured or sold, including but not limited to the requirements
of any relevant Regulatory Authority or legislation requiring that the Licensed
Products be manufactured in accordance with current good manufacturing
practices. Introgen acknowledges that the Exclusive License includes sublicenses
under technology that has been licensed to Corixa pursuant to the Columbia
Agreement, and Introgen represents, warrants and covenants that it will comply
with Section 12 of the Columbia Agreement.

          10.2 By Corixa. Corixa warrants and represents to Introgen that: (a)
it has and will maintain the full right and authority to enter into this
Agreement and grant the rights and licenses granted herein, subject to the
provisions of the Columbia Agreement; (b) it has not previously granted and will
not grant any rights or licenses in conflict with the rights and licenses
granted herein; (c) to its knowledge, no action, suit or claim has been
initiated or threatened with respect to the Licensed Technology that would call
into question Corixa's right to enter into and perform its obligations under
this Agreement; (d) Corixa has provided to Introgen true, correct and complete
copies of the Columbia Agreement, except for the redaction of financial terms
that do not affect Introgen's rights or obligations hereunder; (e) the Columbia
Agreement is in full force and effect as of the Effective Date and grants to
Corixa the right and power to grant the rights and licenses granted to Introgen
herein, subject to Introgen's obligation pursuant to Section 10.1 to comply with
all applicable terms and conditions of the Columbia Agreement; (f) to Corixa's
knowledge, neither Corixa, nor Columbia is in breach of any provision of the
Columbia Agreement, and Corixa has neither given to, nor received from, Columbia
notice of any such breach and there is no dispute pending that relates to the
Columbia Agreement; (g) as of the Effective Date, except for those patents and
patent applications set forth on Exhibit 1.9 (including any foreign counterparts
of such patent applications and patents and all divisions, continuations,
continuations-in-part, patents of addition, substitutions, registrations,
reissues, reexaminations or extensions of any kind with respect to any of the
foregoing), neither Corixa nor any of its Affiliates control any patent or
patent application claiming or disclosing inventions relating to the Licensed
Gene or the Gene Products or that would reasonably be expected to cover the
commercialization of a product within the Field incorporating the Licensed Gene;
and (h) to Corixa's knowledge as of the Effective Date, except as set forth on
Exhibit 10.2 attached hereto, the practice of the Licensed Patents within the
Field will not infringe any intellectual property right of a third party, and
Exhibit 10.2 lists all patents and patent applications of which, as of the
Effective Date, Corixa is aware that Corixa expects to have a direct material
adverse effect on Introgen's ability to commercialize a product within the Field
incorporating the Licensed Gene; and (i) as of the Effective Date, Corixa is not
aware of any reason that would reasonably be expected to preclude the issuance
as a valid patent the pending claims of patent applications within the Licensed
Patents, or that would reasonably be expected to render invalid or unenforceable
any claims of an issued patent within the Licensed Patents.

          10.3 Extent of Warranties. EXCEPT AS SPECIFICALLY PROVIDED IN THIS
AGREEMENT, NEITHER CORIXA NOR INTROGEN MAKES ANY WARRANTIES OF ANY KIND, WHETHER
EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

                                      -16-
<PAGE>   17

     11.  INDEMNIFICATION

          11.1 Indemnification by Corixa. Corixa shall defend, indemnify and
hold Introgen and its directors, officers and employees harmless from and
against any and all liabilities, damages, losses, costs or expenses (including
legal fees) resulting from claims, actions, suits or proceedings brought by
third parties arising out of or resulting from Corixa's (a) material breach of
its obligations hereunder, (b) breach of its representations and warranties set
forth in Section 10.2 above or (c) gross negligence or willful misconduct.

          11.2 Indemnification by Introgen. Introgen shall defend, indemnify and
hold Corixa and Columbia and their respective directors, officers and employees
harmless from and against any and all liabilities, damages, losses, costs or
expenses (including legal fees) resulting from claims, actions, suits or
proceedings brought by third parties arising out of or resulting from Introgen's
(a) material breach of its obligations hereunder, (b) breach of its
representations and warranties set forth in Section 10.1 above, (c) gross
negligence or willful misconduct, (d) manufacture, packaging, use, sale, rental
or lease of Licensed Products by or under the authority of Introgen, even if
altered for use for a purpose not intended, or (e) use of the Licensed
Technology by or under the authority of Introgen.

          11.3 Conditions of Indemnification. The agreements of indemnity set
forth in Sections 10.1 and 10.2 above are conditioned upon the indemnified
party's obligation to: (i) advise the indemnifying party of any claim or suit,
in writing, within sixty (60) days after the indemnified party has received
notice of such claim or suit, and (ii) assist the indemnifying party and its
representatives in the investigation and defense of any claim and/or suit for
which indemnification is provided. This agreement of indemnity shall not be
valid as to any settlement of a claim or suit or offer of settlement or
compromise without the prior written approval of the indemnifying party.

          11.4 Insurance. No later than the initiation of the first clinical
trial for a Licensed Product and continuing during the term of this Agreement
and for five (5) years thereafter, Introgen shall, at its sole cost and expense,
obtain and keep in force a policy of comprehensive general liability insurance
with bodily injury, death and property damage limits of [*] per occurrence and
[*] in the aggregate, including product liability coverage and such additional
provisions or coverage as is reasonable and customary under the circumstances.
Such insurance shall include Corixa and Columbia and their respective trustees,
directors, officers, employees and agents as additional insureds, and shall
provide that the insurer will give Corixa not less than thirty (30) days advance
notice of any material change in or cancellation of coverage. At Corixa's
request, Introgen shall furnish a certificate of insurance evidencing the
insurance required hereunder.

          11.5 No Consequential Damages. NOTWITHSTANDING ANY OTHER PROVISION OF
THIS AGREEMENT, NEITHER PARTY SHALL BE LIABLE TO THE OTHER WITH RESPECT TO THE
SUBJECT MATTER OF THE AGREEMENT UNDER ANY CONTRACT, NEGLIGENCE, STRICT LIABILITY
OR OTHER LEGAL OR EQUITABLE THEORY FOR (A) ANY CONSEQUENTIAL, INCIDENTAL,
SPECIAL OR INDIRECT DAMAGES WHATSOEVER, (B) COST OF PROCUREMENT OF SUBSTITUTE
GOODS, TECHNOLOGY OR SERVICES OR (C) LOSS OF PROFIT OR ANTICIPATED BUSINESS.



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                separately with the Commission. Confidential treatment has been
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                                      -17-
<PAGE>   18

     12.  PATENT PROSECUTION; PAYMENT OF PATENT EXPENSES

          12.1 Prosecution and Payment. The parties acknowledge and agree that
all patent applications relating to the Licensed Technology will be prepared,
filed and prosecuted by Columbia upon the terms and subject to the conditions of
the Columbia Agreement. All costs incurred by Corixa prior to the Effective Date
with respect to the Licensed Patents are the sole responsibility of Corixa, and
all costs incurred by Corixa during the term of this Agreement pursuant to the
Columbia Agreement with respect to the reimbursement of patent expenses incurred
by Columbia are the sole responsibility of Introgen to the extent such Licensed
Patents pertain to the Field. To the extent that Corixa has the right to
prosecute Licensed Patents within the Field under the Columbia Agreement or
otherwise and Corixa reasonably elects to do so (which election Corixa shall not
withhold unreasonably if Introgen so requests), Introgen shall bear all expenses
incurred in connection therewith. In any event, Corixa agrees to keep Introgen
fully informed on a timely basis with respect to the prosecution and
maintenance, and any proceedings (including without limitation any interference
or opposition proceedings, or the like) with respect to, the Licensed Patents.
Notwithstanding the foregoing, Introgen shall be responsible for all costs
incurred by Corixa from the Effective Date through August 20, 1999 on Licensed
Patents in Exhibit 1.9 to the extent necessary to effect the filing of
divisionals and continuations within the Field during such time.

          12.2 [*]

     13.  MISCELLANEOUS

          13.1 Notices. All notices, requests or other communications required
or permitted to be given under this Agreement to any party shall be in writing
and shall be deemed to have been sufficiently given when delivered by personal
service or sent by registered mail, telex or facsimile, to the recipient
addressed as follows:

                           (a)      If to Corixa:

                                    Corixa Corporation
                                    1124 Columbia Street
                                    Suite 200
                                    Seattle, WA  98104
                                    Facsimile:  (206) 754-5762
                                    Attention:  President
                                                Director of Legal Affairs
                           With a copy to:

                                    William W. Ericson
                                    Venture Law Group
                                    4750 Carillon Point
                                    Kirkland, WA 98033
                                    Facsimile:  (425) 739-8750


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                separately with the Commission. Confidential treatment has been
                requested with respect to the omitted portions.




                                      -18-
<PAGE>   19

                           (b)      If to Introgen:

                                    Introgen Therapeutics, Inc.
                                    301 Congress Avenue
                                    Suite 1850
                                    Austin, TX 78701
                                    Facsimile: (512) 320-4166
                                    Attn:  Vice President, Corporate Development

                           With a copy to:

                                    Wilson Sonsini Goodrich & Rosati
                                    650 Page Mill Road
                                    Palo Alto, CA 94304
                                    Attn:  Kenneth A. Clark
                                    Facsimile: (650) 493-6811

     All such communications shall be deemed to be effective on the day on which
personally served, or, if sent by registered mail, on the fourth day following
the date presented to the postal authorities for delivery to the other party
(the cancellation date stamped on the envelope being evidence of the date of
such delivery), or if by telex or facsimile, on the telex or facsimile date.
Either party may give to the other written notice of change of address, in which
event any communication shall thereafter be given to such party as above
provided at such changed address.

          13.2 Publication. If either party shall desire to publish or present,
orally or in writing, including, without limitation at symposia, national or
regional professional meetings, or to publish in journals or other publications,
any Confidential Information of the other party derived from or in anyway
related to its activities under this Agreement, including without limitation
Confidential Information of the other party relating to the Licensed Patents or
the Licensed Know-How, such party shall first provide the other party with
copies of the proposed presentation or publication materials at least sixty (60)
days in advance of the presentation or publication date. Within thirty (30) days
after its receipt of such information, the party receiving such materials shall
advise the other party whether it consents to the disclosure of the submitted
information. If the party receiving the materials does not provide its written
consent thereto, the party desiring to publish or present shall modify the
proposed presentation or publication to eliminate the other party's Confidential
Information or cancel its plans for publications. The parties agree that
publication can be delayed for an appropriate period of time in the event that
either party reasonably determines that it needs time to seek patent or other
intellectual property counsel and/or protection of its Confidential Information.

          13.3 Assignment. This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their successors and assigns. Notwithstanding
the foregoing, neither party hereto shall have the right to assign any of its
rights or obligations under this Agreement without the prior written consent of
the other party; provided, however, that either party may assign this Agreement
to either (a) a party that succeeds to all or substantially all of the assigning
party's business or assets involving the Licensed Technology, whether by sale,
merger, acquisition, other consolidation of such party with or into another
party, operation of law or otherwise, so long as such assignee or transferee
agrees in writing to be bound by the terms and conditions of this Agreement,


                                      -19-
<PAGE>   20


or (b) an entity that is an Affiliate of the assigning party at the time of such
assignment. Notwithstanding the foregoing, upon a termination of the Columbia
Agreement, the rights and obligations of Corixa under this Agreement shall be
assigned to Columbia. Upon a permitted assignment of this Agreement by a party,
all references herein to such party shall be deemed a reference to the assignee.

          13.4 Waivers. The failure of a party hereto to enforce any provision
of this Agreement shall not be construed as a waiver of other breaches of the
same nature or other covenants or conditions of this Agreement.

          13.5 No Agency, Etc. This Agreement is not intended to create, nor
should it be construed as creating, an agency, joint venture, partnership or
employer-employee relationship between Introgen and Corixa. Each party shall act
solely as an independent contractor and shall have no right to act for or to
sign the name of or bind the other party in any way or to make quotations or to
write letters under the name of the other party or to represent that the party
is in any way responsible for any acts or omissions of such party.

          13.6 Force Majeure. Introgen and Corixa shall not be liable for loss,
damage, detention or delay resulting from any cause whatsoever beyond its
reasonable control or resulting from a force majeure, including, without
limitation, earthquake, fire, flood, strike, lockout, civil or military
authority, insurrection, war, embargo, container or transportation shortage or
delay of suppliers due to such causes, and delivery dates shall be extended to
the extent of any delays resulting from the foregoing or similar causes. The
party so affected shall give prompt notice to the other party of such cause, and
shall take whatever reasonable steps are necessary to relieve the effect of such
cause as rapidly as reasonably possible. The party giving such notice shall
thereupon be excused from such of its obligations hereunder as it is thereby
disabled from performing for so long as it is so disabled and for thirty (30)
days thereafter, whichever is longer; provided, however, that such affected
party commences and continues to take reasonable and diligent actions to cure
such cause.

          13.7 Governing Law. This Agreement shall be governed by and construed
in accordance with the laws of the State of Washington, without regard to its
principles of conflicts of laws.

          13.8 Public Announcements. During the term of this Agreement, the
parties agree to consult with each other before issuing any press release or
making any public statement with respect to this Agreement or any other
transaction contemplated herein and, except as may be required by applicable law
or any listing agreement with any national securities exchange, shall not issue
any such press release or make any such public statement prior to obtaining the
written consent of the other party.

          13.9 Disputes and Alternative Dispute Resolution. If Corixa and
Introgen are unable to resolve any dispute, controversy or claim arising out of
or in relation to this Agreement or the breach, termination or invalidity hereof
(each, a "Dispute"), either party may, by written notice to the other, have such
Dispute referred to the Chief Executive Officers of the respective parties for
attempted resolution. The Chief Executive Officers of the respective parties
shall attempt in good faith within thirty (30) days after such notice is
received to resolve such Dispute. Any Dispute that



                                      -20-
<PAGE>   21

cannot be settled amicably by agreement of the parties pursuant to the preceding
sentence shall be finally settled by binding arbitration in accordance with the
Licensing Rules of the American Arbitration Association ("AAA") then in force by
three (3) arbitrators appointed in accordance with said rules, unless the
parties agree that such arbitration shall be conducted by a single arbitrator.
If arbitration is initiated by Corixa, the arbitration shall occur in Austin,
Texas, and, if arbitration is initiated by Introgen, the arbitration shall occur
in Seattle, Washington. The decision and/or award rendered shall be written,
final, non-appealable and binding on both parties. The judgment rendered by the
arbitrator(s) shall include costs of arbitration, reasonable attorneys' fees and
reasonable costs for any expert and other witnesses. Nothing in this Agreement
shall be deemed as preventing either party from seeking injunctive relief (or
any other provisional remedy) from any court having jurisdiction over the
parties and the subject matter of the dispute as necessary to preserve either
party's name, proprietary information, trade secrets, know-how or any other
proprietary rights. Judgment upon the award may be entered in any court having
jurisdiction, or application may be made to such court for judicial acceptance
of the award and/or an order of enforcement as the case may be.

          13.10 Severability. If any provision of this Agreement is finally held
to be invalid, illegal or unenforceable by a court or agency of competent
jurisdiction, that provision shall be severed or shall be modified by the
parties so as to be legally enforceable (and to the extent modified, it shall be
modified so as to reflect, to the extent possible, the intent of the parties)
and the validity, legality and enforceability of the remaining provisions shall
not be affected or impaired in any way.

          13.11 Amendments. Except as otherwise expressly provided herein,
neither this Agreement nor any provision hereof may be amended or waived except
by a written instrument signed by the party against whom enforcement of the
amendment or waiver is sought.

          13.12 Headings. The headings of the paragraphs and subparagraphs of
this Agreement have been added for the convenience of the parties and shall not
be deemed a part hereof.

          13.13 Counterparts. This Agreement may be executed in any number of
counterparts, all of which together shall constitute a single Agreement.

          13.14 Final Agreement. This Agreement is the agreement of the parties
hereto with respect to the subject matter hereof and supersedes all other such
prior agreements and understandings, including without limitation the Prior
Agreement.




                                      -21-
<PAGE>   22

     IN WITNESS WHEREOF, each of the parties has caused this Exclusive License
Agreement to be executed by its duly authorized representative.


CORIXA CORPORATION                            INTROGEN THERAPEUTICS, INC.



By:                                           By:
   ----------------------------------            -------------------------------



Name:                                         Name:
     --------------------------------              -----------------------------



Title:                                        Title:
      -------------------------------               ----------------------------



CHINOOK CORPORATION



By:
   ----------------------------------


Name:
      -------------------------------


Title:
      -------------------------------





                                      -22-
<PAGE>   23





                                    EXHIBIT A

                       REAGENTS TO BE SUPPLIED TO INTROGEN

1.   [*]

2.   [*]






         [*]    Certain information on this page has been omitted and filed
                separately with the Commission. Confidential treatment has been
                requested with respect to the omitted portions.
<PAGE>   24



                                    EXHIBIT B

             TERMS AND CONDITIONS OF PURCHASE AND SUPPLY OF REAGENTS

     In accordance with the terms and conditions of the Exclusive License
Agreement to which this Exhibit A is attached (the "Agreement"), any Licensed
Technology provided by Corixa to Introgen shall be subject to the terms and
conditions set forth below. Unless otherwise defined herein, all capitalized
terms used herein shall have the respective meanings given them in the
Agreement.

1.   Any other terms provided by Introgen in connection with any purchase order,
the receipt or acceptance of the reagents hereunder, or otherwise, which are
different than, or in addition to, the terms hereof are hereby objected to by
Corixa. Shipment of the reagents hereunder shall not constitute acceptance by
Corixa of any conflicting terms and conditions proposed by Introgen.

2.   All shipments of reagents hereunder shall be F.O.B. Corixa's place of
manufacture and Introgen shall bear the risk of loss and cost of transportation
of such reagents.

3.   Unless otherwise expressly agreed by Corixa in writing, Introgen shall use
the reagents only in accordance with the terms and conditions of the Agreement.

4.   THE REAGENTS ARE SUPPLIED HEREUNDER "AS IS" AND CORIXA HEREBY DISCLAIMS ANY
AND ALL REPRESENTATIONS AND WARRANTIES WITH REGARD TO THE REAGENTS, EXPRESS OR
IMPLIED, AND SPECIFICALLY DISCLAIMS ANY OTHER EXPRESS OF IMPLIED WARRANTIES,
INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE OR USE AND ANY OTHER STATUTORY WARRANTIES OR ANY WARRANTY OF
PATENTABILITY OR NONINFRINGEMENT.

5.   In the event of any conflict between these terms and conditions of this
Exhibit A and the Agreement, the terms and conditions of the Agreement shall
govern.


<PAGE>   25




                                    EXHIBIT C

                                RESEARCH PROGRAM


                                      [*]








         [*]    Certain information on this page has been omitted and filed
                separately with the Commission. Confidential treatment has been
                requested with respect to the omitted portions.






<PAGE>   26




                                   EXHIBIT 1.9

                                LICENSED PATENTS





<PAGE>   27



                                  EXHIBIT 10.2

                               THIRD PARTY PATENTS


                                      [*]






         [*]    Certain information on this page has been omitted and filed
                separately with the Commission. Confidential treatment has been
                requested with respect to the omitted portions.