Document:

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                                                                   EXHIBIT 10.25

DATED                                                                       1998

(1) IMPERIAL CANCER RESEARCH TECHNOLOGY
    LIMITED
(2) INTROGEN THERAPEUTICS, INC

OPTION AGREEMENT
FOR TUMOUR SUPPRESSOR GENES

                                [RICHARDS BUTLER
                          INTERNATIONAL LAW FIRM LOGO]

                                                                  [CONFIDENTIAL]
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CONTENTS

CLAUSE

1 INTRODUCTION .............................................................  1
2 INTERPRETATION ...........................................................  1
3 GRANT OF THE FIRST OPTION ................................................  5
4 EXERCISE OF THE FIRST OPTION .............................................  7
5 THE PROJECT ..............................................................  8
6 OWNERSHIP OF TECHNOLOGY AND INTELLECTUAL PROPERTY ........................ 11
7 CONFIDENTIALITY AND PUBLICATION .......................................... 16
8 TERMINATION .............................................................. 19
9 GENERAL .................................................................. 21
10 NOTICES AND SERVICE ..................................................... 25
11 MISCELLANEOUS............................................................ 26

SCHEDULES

SCHEDULE 1 ................................................................. 27
     THE EXISTING PATENTS .................................................. 27
SCHEDULE 2 ................................................................. 28
     THE TERMS OF THE FIRST LICENCE ........................................ 28
SCHEDULE 3 ................................................................. 34
     OBJECTIVES OF THE PROJECT ............................................. 34
SCHEDULE 4 ................................................................. 36
     THE TERMS OF THE SECOND LICENCE ....................................... 36

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AGREEMENT dated                                                             1998

BETWEEN:

(1)   IMPERIAL CANCER RESEARCH TECHNOLOGY LIMITED, incorporated in England and
      Wales with registered number 1662284, whose registered office is at
      Sardinia House, Sardinia Street, London WC2A 3NL, England ('ICRT')

(2)   INTROGEN THERAPEUTICS, INC, incorporated in the State of Delaware, whose
      principal office is at 301 Congress Avenue, Suite 1850, Austin, Texas
      78701, USA ('INTROGEN')

1     INTRODUCTION

1.1   Imperial Cancer Research Fund ('ICRF') and ICRT have identified and
      carried out a programme of research work relating to certain tumour
      suppressor genes which have potential therapeutic uses, and in respect of
      which certain patent applications have been or are to be made by ICRT,
      details of which are given in Schedule 1.

1.2   Introgen wishes to acquire rights in relation to the Genes in order to
      develop DNA based therapeutic products for the treatment of cancer, and is
      willing to fund a project in ICRT's laboratory to evaluate the potential
      of the Genes in cancer gene therapy.

1.3   ICRT is a company wholly owned by ICRF and, by arrangement with ICRF, owns
      and is responsible for the management and exploitation of ICRF technology.

2     INTERPRETATION

2.1   In this Agreement -

      'AFFILIATE' means, in relation to either party, a company which controls
      that party, or is controlled by that party or by a company which controls
      that party; and for these purposes a company controls another company if,
      either directly or indirectly through one or more other companies, it can
      exercise a majority of the votes attached to the

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      shares in the other company, or appoint or remove a majority of the board
      of directors of the other company;

      'THE EFFECTIVE DATE' means 1st January 1999;

      'THE EXISTING PATENTS' means the patent applications referred to in clause
      1.1, and any other patent application which relates to the Field and
      claims the composition, use and/or method of action of any of the Genes,
      as disclosed in any of the patent applications referred to in clause 1.1,
      and which is made by ICRT at any time during the period from the Effective
      Date until the expiration of the First Option Period, any extension,
      reissue, division, continuation or continuation-in-part of any such
      application or patent and any patent of addition, supplementary protection
      certificate or similar rights based on any such patent;

      'EXISTING TECHNOLOGY' means any Technology relating to any of the Genes
      which has been obtained, developed, found, produced or made by or for ICRF
      or ICRT at any time prior to the Effective Date;

      'THE FIELD' means the field of [*];

      'THE FIRST LICENCE' means the licence to be granted pursuant to clause
      4.1;

      'THE FIRST OPTION' means the option granted by ICRT under clause 3.1;

      'THE FIRST OPTION PERIOD' means the period of [*] from the Effective
      Date;

      'THE GENES' means the tumour suppressor genes referred to in clause 1.1
      (i.e. Rsk3, DBCCR1, 11q24 and 16q23) including, for the avoidance of
      doubt, any splice variants or other derivatives of any such gene and for
      the purposes of the foregoing, a

                                                                  [CONFIDENTIAL]

         [*]    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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      "derivative" means a nucleotide sequence derived from that gene (including
      fragments thereof) the product of which has tumour suppressor activity;

      'ICRF' means Imperial Cancer Research Fund;

      'INTELLECTUAL PROPERTY' means any patent application or patent (including
      any extension, reissue, division, continuation or continuation-in-part of
      any such application or patent and any patent of addition, supplementary
      protection certificate or similar rights based on any patent), copyright
      or other form of protection, the right to make any application for any
      such protection in any part of the world, and any right in respect of any
      trade secret or other confidential information;

      'THE INVENTIONS' means the inventions claimed or disclosed in the Existing
      Patents;

      'MATERIALS' means any model, prototype, material or substance (including,
      without limitation, any living organism or genetic material), and includes
      any progeny or derivative of any of the foregoing;

      'THE NEGOTIATION PERIOD' means the period of [*] from the date of exercise
      of the First Option or the Second Option, as the case may be, or such
      longer period as the parties may agree in either case;

      'THE PROJECT' means the programme of collaborative research referred to in
      clause 5.1;

      'PROJECT TECHNOLOGY' means any Technology obtained, developed, found,
      produced or made at any time on or after the Effective Date in the course
      of the Project;

      'PROJECT PATENTS' means any patent applications claiming any Project
      Technology, any patents issued in pursuance of any such application, any
      extension, reissue, division, continuation or continuation-in-part of any
      such application or patent and any patent of addition, supplementary
      protection certificate or similar rights based on any such patent;

         [*]    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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      'THE SECOND LICENCE' means the agreement to be entered into pursuant to
      clause 6.7;

      'THE SECOND OPTION' and 'THE SECOND OPTION PERIOD' have the meanings given
      in clause 6.6;

      'TECHNOLOGY' means any methods, techniques, processes, discoveries,
      inventions (whether patentable or not), formulae, results of
      experimentation, statistics, data, computer software or plans, any
      Materials and any records in any form relating to any of the foregoing;
      and

      'YEAR' means a period of 365 (or, in the case of a leap year, 366) days.

2.2   Unless the context otherwise requires, each reference in this Agreement to

      (a) 'WRITING', and any cognate expression, includes a reference to any
          communication effected by facsimile transmission or similar means
          (but not electronic mail);

      (b) a licence includes a sub-licence; and 'LICENSE' (as a verb) and
          cognate expressions shall be construed accordingly;

      (c) a statute or a provision of a statute is a reference to that statute
          or provision as amended, re-enacted or extended at the relevant time,
          and includes any statute or a corresponding provision in a statute
          replacing that statute or provision;

      (d) 'THIS AGREEMENT' is a reference to this Agreement and each of the
          Schedules, as amended or supplemented at the relevant time;

      (e) a Schedule is a reference to a schedule to this Agreement;

      (f)  a clause or a paragraph is a reference to a clause of this Agreement
          (other than the Schedules) or a paragraph of the relevant Schedule;

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      (g) any reference to the parties includes a reference to their
          respective successors in title and permitted assignees;

      (h) any reference to a person includes any body corporate, unincorporated
          association, partnership or other legal entity;

      (i) the singular includes the plural and vice versa; and

      (j) words importing any gender include any other gender.

2.3   The headings in this Agreement are for convenience only and shall not
      affect its interpretation.

3     GRANT OF THE FIRST OPTION

3.1   ICRT hereby grants to Introgen, on and subject to the terms of this
      Agreement, the exclusive option to obtain an exclusive, world-wide licence
      (to the extent that ICRT is able to grant such a licence under any
      applicable law) in respect of the Existing Patents relating to any one
      or more of the Genes and any Materials or other Existing Technology
      referred to in clause 5.4, in respect of the Gene or Genes in question, on
      the terms referred to in clause 4.1.

3.2   The First Option shall be exercisable by Introgen, in respect of any
      one or more of the Genes, subject to payment of the sum referred to in
      clause 3.3, by giving written notice to ICRT at any time during the First
      Option Period, specifying the Gene or Genes in respect of which it is
      exercised. If Introgen so exercises the First Option in respect of one or
      more but not all of the Genes it may do so at any subsequent time within
      the First Option Period in respect of the remaining Gene or Genes.

3.3   In consideration of the grant of the First Option, Introgen shall pay to
      ICRT the sum of [*] on the Effective Date.

3.4   The sum referred to in clause 3.3 shall not be refunded in any
      circumstances.

         [*]    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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3.5   If Introgen does not duly exercise the First Option during the First
      Option Period in respect of one or more of the Genes, it shall forthwith
      lapse in respect of the Gene or Genes in question for which Introgen did
      not so exercise the First Option.

3.6   During the First Option period ICRT shall diligently prosecute and
      maintain the Existing Patents and keep Introgen fully informed as to the
      prosecution status of the Existing Patents (including, without limitation,
      furnishing to Introgen information relevant to such prosecution and
      maintenance) and shall give fair consideration to suggestions made by
      Introgen in respect of the prosecution strategy in so far as they relate
      to the Field, but if ICRT notifies Introgen in writing that -

      (a) it wishes to abandon any patent application or patent within the
          Existing Patents which relates to the Field, it shall give a prompt
          written notice Introgen offering to assign it to Introgen at the
          expense of Introgen but otherwise free of charge, and if Introgen does
          not accept the offer in writing within 30 days, ICRT shall have no
          further obligation with respect to the patent or patent application;
          or

      (b) it does not wish to elect to proceed from PCT stage to national stage
          with respect to any such application in any country, it shall give a
          prompt written notice to Introgen, and ICRT shall have no further
          obligation with respect to the application unless Introgen notifies
          ICRT in writing within thirty (30) days that it wishes ICRT so to
          proceed, in which event ICRT shall do so but at the sole expense of
          Introgen, and accordingly for the purposes of -

          (i)  clause 3.7(b), that application and any Existing Patent granted
               pursuant to it in the relevant country shall be treated as if
               they had been assigned to Introgen; and

          (ii) the provisions of the First Licence as to royalties summarised in
               paragraph 9 of Schedule 2, that application and any Existing
               Patent

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               granted pursuant to it shall be deemed not to exist in the
               relevant country.

3.7   During the First Option Period the out-of-pocket costs and expenses of
      prosecuting and maintaining the Existing Patents shall be borne -

      (a) in respect of any of the Existing Patents the claims of which relate
          exclusively to any matter outside the Field, [*];

      (b) in respect of any of the Existing Patents the claims of which relate
          exclusively to the Field, or which have been assigned to Introgen
          pursuant to clause 3.6(a) (or are treated as if they had been so
          assigned pursuant to clause 3.6(b)(i), [*];

      (c) in respect of any other of the Existing Patents, [*];

      and Introgen shall accordingly pay to ICRT the [*] of those costs and
      expenses incurred from time to time within 30 days after receipt from ICRT
      of an account setting out the relevant information to enable its share to
      be ascertained.

4     EXERCISE OF THE FIRST OPTION

4.1   If Introgen exercises the First Option in accordance with clause 3.2, in
      respect of one or more of the Genes, ICRT and Introgen shall forthwith use
      their best endeavours during the Negotiation Period to negotiate in good
      faith the terms and conditions for the grant to Introgen of the licence
      referred to in clause 3.1 ('THE FIRST LICENCE'), which shall include the
      terms and conditions set out in Schedule 2 and such other terms and
      conditions (consistent with those set out in Schedule 2) as are reasonable
      and customary in the biopharmaceutical industry for arrangements of the
      type contemplated by the First Licence. If Introgen subsequently exercises
      the First Option in respect of any of the Genes, the Gene or Genes in
      question shall be deemed as from the date of exercise to be covered by the
      terms of the First Licence.

         [*]    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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4.2   Upon agreement being reached between ICRT and Introgen as to the terms of
      the First Licence, the parties shall forthwith execute an agreement
      containing the terms so agreed between ICRT and Introgen.

4.3   If, notwithstanding their best endeavours, ICRT and Introgen do not agree
      upon the terms for the grant of the First Licence to Introgen during the
      Negotiation Period, Introgen shall have the right, exercisable by
      notifying ICRT in writing at any time within fifteen (15) days after the
      expiration of the Negotiation Period, to initiate a binding arbitration
      proceeding, pursuant to which the terms and conditions of the First
      Licence shall be established. Any arbitration under this provision shall
      be held in accordance with clause 9.12 by a single arbitrator and the sole
      issue before such arbitrator shall be to establish the terms and
      conditions of the First Licence in accordance with clause 4.1, to the
      extent that they have not been agreed. If Introgen does not exercise the
      foregoing right to initiate arbitration within the applicable fifteen (15)
      day period, the First Option shall lapse in respect of the Gene or Genes
      in question.

4.4   If the First Option lapses pursuant to clause 3.5 or 4.3 (and if Introgen
      has no further right to exercise the First Option in respect of any of the
      Genes) then, except to the extent that clauses 5, 6 and 7 continue to
      operate, this Agreement shall terminate automatically, in which case all
      rights and obligations of the parties shall terminate except as provided
      in clause 8.4.

5     THE PROJECT

5.1   As further consideration for the grant of the First Option, Introgen
      shall co-operate with ICRT on a programme of collaborative research on the
      following terms.

5.2   Subject to the following provisions, the Project shall be carried on for a
      period of [*] from the Effective Date.

5.3   The overall objectives of the Project shall be as set out in Schedule 3.
      Within those overall objectives, the detailed objectives and
      implementation of the Project, and the

         [*]    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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      work to be carried out by ICRT and Introgen respectively as part of the
      Project, shall be as agreed between Dr. David Snary of ICRT and Dr. Sunil
      Chada of Introgen from time to time, but initially as set out in Schedule
      3.

5.4   ICRT shall, as soon as practicable after the Effective Date -

      (a) supply to Introgen samples of such of the Materials relating to the
          Genes and in the possession or control of ICRT as are reasonably
          necessary to enable Introgen to carry its tasks in relation to the
          Project or as are otherwise requested by Introgen from time to time in
          connection with its evaluation of the Genes with a view to deciding
          whether or not to exercise the First Option or the Second Option; and

      (b) disclose to Introgen such other of the Existing Technology as is
          relevant to the Project or it exercise of the First Option or the
          Second Option;

      and Introgen shall be entitled to use and practice the Inventions, and to
      use any Materials so supplied and any Existing Technology so disclosed
      during the continuance of the Project, for the purposes only of carrying
      out its part of the Project and planning the development and exploitation
      in the Field of the Existing Technology and Project Technology or as
      otherwise reasonably necessary to evaluate the Genes with a view to
      deciding whether or not to exercise the First Option or the Second Option.

5.5   Subject as provided in clause 5.4, the resources to be applied to the
      Project by each of ICRT and Introgen shall be solely at its discretion.

5.6   Introgen shall pay to ICRT, as a contribution to the work to be carried
      out by ICRT as part of the Project, the sum of [*] on the
      Effective Date and [*].

5.7   For the avoidance of doubt, each sum payable pursuant to clause 5.6 shall
      not be refunded in any circumstances, and if Introgen exercises the First
      Option before the

         [*]    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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      end of the First Option Period, any such sum which is outstanding shall
      continue to be payable.

5.8   If at any time Introgen in its reasonable opinion decides that all, or a
      major part of, the objectives set out in Schedule 3 have been achieved,
      and proposes to proceed to full pre-clinical and clinical development of
      the Gene in the Field, it shall be entitled to terminate the Project by
      giving to ICRT not less than one month's written notice setting out
      details of its description and its proposals.

5.9   If within one year from the Effective Date Introgen has not commenced good
      faith active steps with a view to carrying out its part of the Project for
      any reason, ICRT shall be entitled to terminate the Project by giving to
      Introgen not less than one month's written notice provided that Introgen
      does not commence such steps within such one (1) month period, in which
      case the parties shall forthwith take such steps as may be necessary to
      terminate the Project, and subject to those steps being taken this
      Agreement shall terminate automatically.

5.10  For the purposes of the Project the principal points of contact between
      the parties will be as follows -

      for ICRT:     Dr David Snary

      for Introgen: Dr Sunil Chada.

5.11  ICRT and Introgen shall ensure that Dr Snary and Dr Chada respectively
      shall communicate and meet with one another as necessary to progress the
      work on the Project, and that each of them shall report their research
      data at semi-annual intervals in a short written report to Introgen and
      ICRT respectively.

5.12  If any employees or other representatives of ICRT are requested to visit
      the premises of Introgen for the purposes of the Project, Introgen shall -

         [*]    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) at its own cost give all reasonable assistance required by any of them
          for that purpose; and

      (b) reimburse ICRT for their reasonable travel, accommodation and other
          expenses incurred, within 30 days after receipt of an invoice for the
          sum in question.

5.13  If by agreement with ICRT any employees or other representatives of
      Introgen visit the premises of ICRT for the purposes of the Project -

      (a) ICRT shall at the cost of Introgen give all reasonable assistance
          required by any of them for that purpose, and Introgen shall reimburse
          to ICRT any out-of-pocket sum incurred by ICRT for that purpose
          within 30 days after receipt of an invoice for the sum in question;
          and

      (b) Introgen shall be responsible for their travel, accommodation and
          other expenses.

6     OWNERSHIP OF TECHNOLOGY AND INTELLECTUAL PROPERTY

6.1   Subject to provisions of this Agreement, the Inventions, the Existing
      Patents, the Existing Technology and all Intellectual Property in respect
      of any of the Existing Technology shall remain the exclusive property of
      ICRT.

6.2   Any Project Technology, and any Project Patents or other Intellectual
      Property in respect of any Project Technology, shall -

      (a) if made solely by ICRT staff working on the Project, belong
          exclusively to ICRT;

      (b) if made solely by Introgen staff working on the Project, belong
          exclusively to Introgen;

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      (c) if made jointly by ICRT staff and Introgen staff working on the
          Project, belong to ICRT and Introgen jointly in equal undivided
          shares.

6.3   Except as otherwise provided in this Agreement and subject to the rights
      and licences granted herein, neither party shall have any obligation to
      account to the other for profits, or to obtain any approval or consent of
      the other party to license or exploit any Intellectual Property, by reason
      of their joint ownership of such Intellectual Property.

6.4   ICRT and Introgen shall discuss and seek to agree upon the extent to
      which, and the countries in which, patent protection for any Project
      Technology owned by ICRT or jointly owned by ICRT and Introgen should be
      obtained and, except to the extent that they otherwise agree in writing -

      (a) the protection shall be applied for by ICRT in the name of ICRT, or
          jointly in the names of ICRT and Introgen, as the case may be;

      (b) ICRT shall diligently prosecute and maintain the Project Patents in
          question and keep Introgen fully informed as to the prosecution status
          of the Project Patents (including, without limitation, furnishing to
          Introgen information relevant to such prosecution and maintenance) and
          shall give fair consideration to suggestions made by Introgen in
          respect of the prosecution strategy in as far as they relate to the
          Field, but if ICRT notifies Introgen in writing that -

          (i)  it wishes to abandon any such patent application or patent, it
               shall give a prompt written notice to Introgen offering to assign
               it to Introgen at the expense of Introgen but otherwise free of
               charge, and if Introgen does not accept the offer in writing
               within 30 days, ICRT shall have no further obligation with
               respect to the patent or patent application in question; or

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          (ii) it does not wish to elect to proceed from PCT stage to national
               stage with respect to any such application in any country, it
               shall give a prompt written notice to Introgen;

      (c) where ICRT gives such a notice pursuant to clause 6.4(b)(ii) above,
          ICRT shall have no further obligation with respect to the application
          unless Introgen notifies ICRT in writing within 30 days that it wishes
          ICRT so to proceed, in which event ICRT shall do so but at the sole
          expense of Introgen, and accordingly for the purposes of -

          (i)  clause 6.4(d), that application and any Project Patent granted
               pursuant to it in the relevant country shall be treated as if
               they had been assigned to Introgen; and

          (ii) the provisions of the First Licence as to royalties summarised in
               paragraph 9 of Schedule 2 (as they apply to Project Patents
               pursuant to paragraph 3 of Schedule 4), that application and any
               Existing Patent granted pursuant to it shall be deemed not to
               exist in the relevant country;

      (d) the out of pocket costs and expenses of prosecuting and maintaining
          the Project Patents in question shall be borne, as if they were
          Existing Patents, in the manner provided in clause 3.7 which shall
          apply with the necessary changes (and so that the reference therein to
          clause 3.6(b)(i) shall be deemed to be a reference to clause
          6.4(c)(i));

      (e) Introgen shall keep ICRT informed as to the prosecution status of all
          patent applications within the Project Patents owned by Introgen; and

      (f) each of ICRT and Introgen shall give the other such assistance as the
          other may reasonably require and at the other party's expense in order
          to obtain and maintain such protection.

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6.5   ICRT hereby grants to Introgen the exclusive option to take an exclusive
      licence under any or all of the Project Patents and Project Technology
      owned exclusively by ICRT and the exclusive right to exploit any and all
      Project Patents owned jointly by ICRT and Introgen, in each case insofar
      as the Project Patents and Project Technology relate to any one or more of
      the Genes in respect of which Introgen has exercised the First Option.

6.6   The option granted under clause 6.5 ('THE SECOND OPTION') shall be
      exercisable by Introgen by giving written notice to ICRT at any time
      during the period ('THE SECOND OPTION PERIOD') of [*] after the
      termination of the Project (except where this Agreement is terminated by
      ICRT pursuant to clause 8.2 or 8.3).

6.7   If Introgen exercises the Second Option in accordance with clause 6.6, the
      First Licence shall be modified to include such Project Patents and
      Project Technology within the scope of the First Licence, in accordance
      with the provisions of Schedule 4, and ICRT and Introgen shall forthwith
      execute an agreement ('THE SECOND LICENCE') to effect such a modification.
      In the event of any disagreement as to the terms of the Second Licence,
      the provisions of clause 4.3 shall apply with the necessary changes.

6.8   Notwithstanding any licence or right granted by ICRT pursuant to this
      Agreement, ICRT (for itself and ICRF) shall retain -

      (a) the exclusive right to use any Existing Technology (and any Existing
          Patents or other Intellectual Property in respect thereof) for any
          purpose outside the Field;

      (b) the exclusive right to use any Project Technology which belongs
          exclusively to ICRT (and any Project Patents or other Intellectual
          Property in respect thereof), for any purpose outside the Field;

      (c) the exclusive right to use any Project Technology which belongs to
          ICRT and Introgen jointly (and any Project Patents or other
          Intellectual Property in respect thereof) for [*]; and

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

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      (d) the non-exclusive right to use any Project Technology which belongs to
          ICRT and Introgen jointly (and any Project Patents or other
          Intellectual Property in respect thereof) for research and all other
          applications (except [*]) outside the Field.

6.9   Introgen hereby grants to ICRT (for itself and ICRF) an irrevocable,
      perpetual, nonexclusive, worldwide, royalty-free licence, with the right
      to grant sublicences, in respect of any Introgen Improvement, and any
      Project Patents or other Intellectual Property in respect of any such
      Introgen Improvement, for the purposes of research and the manufacture,
      sale and use of products for [*] outside the Field.

      For the purpose of this Agreement 'INTROGEN IMPROVEMENT' means any Project
      Technology which belongs exclusively to Introgen and which is a derivative
      (as defined in clause 2.1) of any of the Genes or a method of using any of
      the Genes (including derivative thereof); provided, however, that an
      'Introgen Improvement' shall not include any vector, delivery system,
      method, composition or other subject matter which is proprietary to
      Introgen, or any such Project Technology which necessarily involves or
      includes the use of or combination of any such vector, delivery system,
      method, composition or other subject matter.

6.10  If Introgen does not duly exercise the Second Option during the Second
      Option Period in respect of any one or more of the Genes, the Second
      Option shall lapse in respect of the Gene or Genes in question, and ICRT
      shall have the option, exercisable within a further [*] by giving written
      notice to Introgen, to negotiate for the grant to ICRT of an exclusive
      licence in respect of any Introgen Improvement, a nonexclusive licence in
      respect of any other Project Technology which belongs to ICRT and Introgen
      jointly, and all Project Patents or other Intellectual Property in respect
      thereof relating to the Gene or Genes in question (but excluding any
      rights in respect of any vector, delivery system, method, composition or
      other technology which is proprietary to Introgen, or any such Project
      Technology which necessarily involves or includes the use of or
      combination of any such vector, delivery system, method,

         [*]    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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      composition or other technology), to use the same for any purpose, on a
      world-wide, royalty-bearing basis, to the extent that Introgen is able to
      grant such a licence or right.

6.11  If ICRT exercises the option referred to in clause 6.10, ICRT and Introgen
      shall forthwith use their best endeavours to negotiate in good faith the
      terms of an agreement for the grant of the licence or right within the
      period of [*] from the date of exercise of the option (provided that any
      such agreement shall contain the right for ICRT to grant licences (or
      sub-licences) under the Project Patents and Project Technology in question
      to any other person). In the event of any disagreement as to the terms of
      such agreement, the provisions of clause 4.3 shall apply with the
      necessary changes.

7     CONFIDENTIALITY AND PUBLICATION

7.1   Except as provided herein, each party shall maintain in confidence during
      the term of this Agreement and for seven (7) years thereafter, and shall
      not use for any purpose or disclose to any third party, any Technology or
      other information disclosed by the other party in writing and marked
      "Confidential" or that is disclosed orally and confirmed in writing as
      confidential within forty-five (45) days following such disclosure
      (collectively 'CONFIDENTIAL INFORMATION'), except to the extent that any
      such Confidential Information -

      (a) is at the time of being so provided or after that time through no
          fault of the party to whom it was so provided becomes public
          knowledge; or

      (b) was lawfully available on a non-confidential basis to the party to
          whom it was so provided before that time; or

      (c) can be shown by the party to whom it was so provided to have been
          independently produced by that party without any use of such
          confidential information provided to it by the other party; or

         [*]    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.

                                                                  [CONFIDENTIAL]
                                     PAGE 16
<PAGE>   19

      (d) is made available to the party to whom it was so provided otherwise
          than in breach of an obligation of confidentiality owed to the other
          party.

7.2   The results of the Project may be made public by either party (or, in the
      case of ICRT, by ICRF) except to the extent that -

      (a) publication would include any Confidential Information of the other
          party; or

      (b) publication would prejudice the obtaining of patent protection for an
          invention constituting Project Technology, or the commercial
          exploitation of any unpatented or unpatentable Project Technology
          which remains unpublished.

7.3   To allow time for review of any proposed disclosure of any subject matter
      which may be precluded from being made public under clause 7.2, each of
      ICRT and Introgen shall provide to the other -

      (a) a copy of any manuscript disclosing any results of the Project not
          less than 45 days notice before submitting the manuscript for
          publication; and

      (b) a copy of any slides to be used in an oral presentation disclosing any
          results of the Project together with an outline of the presentation
          not less than 20 working days before making any such oral
          presentation.

7.4   The party receiving any such material pursuant to clause 7.3 shall
      promptly and in any event prior to the proposed date of submission for
      publication review the proposed disclosure and notify the other party in
      writing of its conclusions, failing which the other party shall be free to
      make the proposed disclosure.

7.5   If in the reasonable opinion of the party receiving the material the
      proposed disclosure does not include subject matter which is precluded
      from being made public under clause 7.2, it shall promptly notify the
      other party which shall thereupon be free to make the proposed disclosure.

                                                                  [CONFIDENTIAL]
                                     PAGE 17
<PAGE>   20

7.6   If in the reasonable opinion of either party -

      (a) the proposed disclosure includes subject matter which is precluded
          from being made public under clause 7.2 and which is patentable,
          neither party shall publish or otherwise disclose the material in
          question for a period of three months from the date on which the
          relevant material was received by the party in question and, if a
          patent application is made within that period of three months, for a
          further period as agreed but in any event not exceeding a total of 18
          months from that date (including such period of three months),
          following which the other party shall be free to make the proposed
          disclosure; or

      (b) the proposed disclosure includes unpatented (or unpatentable) Project
          Technology which that party wishes to maintain as unpublished and
          which has been identified in Project reports pursuant to clause 5.11
          as being of potential commercial significance, neither party shall
          publish or otherwise disclose the material in question for a period of
          18 months from that date, following which either party shall be free
          to make the proposed disclosure; or

      (c) the proposed disclosure includes Confidential Information of the
          reviewing party, the disclosing party shall remove such Confidential
          Information prior to such disclosure.

7.7   Notwithstanding the foregoing provisions of this clause 7 above, the
      receiving party may use or disclose Confidential Information of the
      disclosing party -

      (a) to the extent necessary to exercise its rights hereunder (including
          providing such information to bona fide licensees or prospective
          licensees as contemplated by this Agreement or otherwise and to
          potential investors or partners on reasonable terms of
          confidentiality) or to fulfill its obligations and/or duties
          hereunder;

      (b) in filing for, prosecuting or maintaining any proprietary rights,
          prosecuting or defending litigation; and

                                                                  [CONFIDENTIAL]
                                     PAGE 18
<PAGE>   21

      (c) in complying with applicable governmental regulations and/or
          submitting information to tax or other governmental authorities; or as
          otherwise required by law;

      provided that if the receiving party is required by law to make any public
      disclosures of Confidential Information of the disclosing party then, 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).

8     TERMINATION

8.1   This Agreement shall be deemed to have come into force on the Effective
      Date and, subject to the following provisions, shall continue in force for
      the respective periods of time provided for in this Agreement and
      otherwise without any time limit.

8.2   ICRT shall be entitled to terminate this Agreement forthwith by giving
      fifteen (15) days' prior written notice to Introgen if any sum payable
      under this Agreement is not paid in full within seven (7) days after the
      due date for payment and Introgen fails to make such payment within such
      fifteen (15) day period.

8.3   Either party shall be entitled to terminate this Agreement forthwith by
      giving written notice to the other party if -

      (a) the other party commits a breach of any of its obligations under this
          Agreement (other than, in the case of Introgen, a breach to which
          clause 8.2 applies) and fails to remedy to breach within thirty (30)
          days after receiving a written notice from the first mentioned party
          specifying the breach and requiring it to be remedied; or

      (b) the other party goes into liquidation, has a receiver appointed over
          any of its assets, has an administrator appointed, makes any voluntary
          arrangement with

                                                                  [CONFIDENTIAL]
                                     PAGE 19
<PAGE>   22

          any of its creditors, or ceases to carry on business, or any similar
          event under the law of any foreign jurisdiction occurs in relation to
          the other party.

8.4   On the termination of this Agreement for any reason (including, for the
      avoidance of doubt, any termination or partial termination pursuant to
      clause 4.4 or clause 5.9) -

      (a) the rights and obligations of Introgen under the First Licence (if it
          has been executed) and the Second Licence (if it has been executed) or
          of ICRT under any agreement entered into pursuant to clause 6.11 (if
          it has been executed) shall continue in force;

      (b) subject to paragraph (a), Introgen shall forthwith cease all use of
          the Genes, the Inventions, the Existing Technology and any Project
          Technology which belongs exclusively to ICRT, and destroy all
          Materials in the possession or control of Introgen which have been
          supplied by ICRT or produced or derived from any Materials so
          supplied;

      (c) except to the extent that paragraph (a) above applies (and that
          accordingly this paragraph (c) does not apply), ICRT shall be entitled
          to license the Existing Patents and the Existing Technology, any
          Project Patents (other than any of them which belong exclusively to
          Introgen) and any unpatented (or unpatentable) Project Technology
          (other than data which Introgen reasonably considers proprietary to
          itself) to any other person;

      (d) the provisions of clause 6.1, 6.2, 6.3, 6.8, 6.9, 6.10, 6.11, 7, 9.10,
          9.11 and 9.12 shall continue in force in accordance with their terms,

          but subject to the foregoing, and except for any accrued right or
          obligation of either ICRT or Introgen, neither of them shall be under
          any further obligation to the other.

8.5   Notwithstanding anything herein to the contrary, if either party disputes
      in good faith the other party's right to terminate this Agreement
      pursuant to the foregoing provisions of this clause 8 by reason of a
      breach by the other party, the other party's

                                                                  [CONFIDENTIAL]
                                     PAGE 20
<PAGE>   23

      right to terminate shall be stayed unless or until it has been determined
      in accordance with clause 9.12 that such party has such a right and, if it
      is so determined, the party in breach has failed to remedy the breach in
      question within thirty (30) days after such determination.

9     GENERAL

9.1   This Agreement and the rights granted under it are personal to each party,
      which may not assign, transfer or charge to any other person any of its
      rights under this Agreement, or subcontract or otherwise transfer to any
      other person any of its obligations under this Agreement.

9.2   Notwithstanding clause 9.1, either party may assign this Agreement and its
      obligations hereunder to a party that is an Affiliate of the assigning
      party at the time of the assignment or a party that succeeds to all or
      substantially all of its business or assets relating to this Agreement
      whether by sale, merger, operation of law or otherwise; provided that in
      either case such assignee promptly enters into an agreement in writing
      with the other party to be bound by the terms and conditions of this
      Agreement.

9.3   ICRT warrants to Introgen that -

      (a) except as disclosed in writing to Introgen, ICRT owns all right, title
          and interest in and to the Existing Technology, the Existing Patents
          and all other Intellectual Property of ICRT in respect of the Existing
          Technology and, subject to clause 9.4, it has the authority to enter
          into this Agreement and to grant the rights granted by it under this
          Agreement;

      (b) the execution by ICRT of, and the performance of its obligations
          under, this Agreement require no governmental or other approvals or,
          if required, all such approvals have been obtained;

      (c) it has not granted and, except as otherwise provided in this
          Agreement, will not during the continuance of this Agreement grant to
          any third party any rights

                                                                  [CONFIDENTIAL]
                                     PAGE 21
<PAGE>   24

          which are inconsistent with the rights granted by it under or
          pursuant to this Agreement;

      (d) except as disclosed in writing to Introgen, it is not aware of any
          third party claims or governmental restrictions (other than legal
          provisions of general application) which would restrict its ability to
          grant the rights agreed to be granted by it under this Agreement; and

      (e) except for the Existing Patents, as at the Effective Date ICRT does
          not own or control any patents or patent applications the claims of
          which would dominate the practice of the rights to be granted to
          Introgen pursuant to this Agreement.

9.4   Without limiting clause 9.3, ICRT does not warrant -

      (a) the efficacy or usefulness of the Existing Technology or any Project
          Technology; or

      (b) that the exercise of the rights granted under this Agreement will not
          infringe the patent or other Intellectual Property rights of any third
          party; or

      (c) that any of the Existing Patents or Project Patents is or will be
          valid or enforceable, or (in the case of an application) will proceed
          to grant.

9.5   Introgen warrants to ICRT that -

      (a) it has the authority to enter into this Agreement and to grant the
          rights granted by it under this Agreement;

      (b) the execution by Introgen of, and the performance of its obligations
          under, this Agreement require no governmental or other approvals or,
          if required, all such approvals have been obtained;

      (c) it has not granted and, except as otherwise provided in this
          Agreement, will not during the continuance of this Agreement grant to
          any third party any rights

                                                                  [CONFIDENTIAL]
                                     PAGE 22
<PAGE>   25

          which are inconsistent with the rights granted by it under or
          pursuant to this Agreement; and

      (d) it is not aware of any third party claims or governmental restrictions
          (other than legal provisions of general application) which would
          restrict its ability to grant the rights agreed to be granted by it
          under this Agreement.

9.6   Subject to the terms of the First Licence (if executed), the Second
      Licence (if executed) or any agreement entered into pursuant to clause
      6.11, if either party becomes aware of any infringement of any of the
      Existing Patents or the Project Patents, or any claim is made or
      threatened against either party that the exercise of any rights granted
      under this Agreement infringes the patent or other Intellectual Property
      rights of any third party, it shall forthwith notify the other party,
      whereupon the parties shall consult and seek to decide what steps if any
      to take, and each of them shall give the other party (at the other party's
      expense) such assistance as the other party may reasonably request in
      connection therewith.

9.7   Neither party nor its representatives or employees (or, in the case of
      ICRT, those of ICRF) shall be deemed in any circumstances to be the
      employees or representatives of the other party (or, in the case of ICRT,
      to be those of ICRF), or shall have any authority or power to bind the
      other party or to contract in its name.

9.8   This Agreement contains the entire agreement between the parties with
      respect to its subject matter and may not be modified except by an
      instrument in writing signed by the duly authorised representatives of the
      parties, and each party acknowledges that, in entering into this
      Agreement, it does not do so in reliance on any representation, warranty
      or other provision, except as expressly provided herein, and any implied
      warranties are hereby excluded to the fullest extent permitted by law, but
      nothing in this provision shall affect the liability of either party for
      any fraudulent misrepresentation.

                                                                  [CONFIDENTIAL]
                                     PAGE 23
<PAGE>   26

9.9   Except with regard to the exercise of the First Option and the Second
      Option, no failure or delay by either party in exercising any of its
      rights under this Agreement shall be deemed to be a waiver of that right,
      and no waiver by either party of a breach of any provision of this
      Agreement shall be deemed to be a waiver of any subsequent breach of the
      same or any other provision.

9.10  If any provision of this Agreement is held by any court or other competent
      authority to be invalid or unenforceable in whole or in part, the other
      provisions of this Agreement and the remainder of the affected provision
      shall continue to be valid.

9.11  This Agreement (and any licence to be entered into pursuant to this
      Agreement) shall be governed and construed in all respects in accordance
      with the laws of England, and the parties agree to submit to the
      non-exclusive jurisdiction of the English Courts.

9.12  Any dispute or arising out of, in relation to, or in connection with this
      Agreement, or the validity, enforceability, construction, performance or
      breach hereof, shall be settled by binding arbitration in London, England,
      under the then-current Rules of Arbitration of the International Chamber
      of Commerce Court of Arbitration by a single arbitrator appointed in
      accordance with such rules, provided that if either party so requests (and
      unless otherwise provided hereunder) the arbitration shall be conducted by
      a panel of three (3) arbitrators appointed in accordance with the Rules.
      The decision and/or award rendered by the arbitrator(s) shall be written,
      final and non-appealable and may be entered in any court of competent
      jurisdiction. Accordingly, the parties hereby waive any and all rights of
      appeal to the Court under the Arbitration Act 1996. The parties agree
      that, any provision of applicable law notwithstanding, they will not
      request, and the arbitrator shall have no authority to award, punitive or
      exemplary damages against any party. The costs of any arbitration,
      including administrative fees and fees of the arbitrator(s), shall be
      shared equally by the parties, unless otherwise determined by the
      arbitrator(s). Each party shall bear the cost of its own legal and expert
      fees; provided that the arbitrator(s) may in his or their discretion
      award to the prevailing party the costs and expenses incurred by the
      prevailing party in connection with the arbitration proceeding.

                                                                  [CONFIDENTIAL]
                                     PAGE 24
<PAGE>   27

10    NOTICES AND SERVICE

10.1  Any notice or other information required or authorised by this Agreement
      to be given by either party to the other shall be given by -

      (a) delivering it by hand;

      (b) sending it by pre-paid registered post; or

      (c) sending it by facsimile transmission or similar means of communication
          (but not electronic mail);

      to the other party at the address given in clause 10.4.

10.2  Any notice or information sent by post in the manner provided by clause
      10.1(b) which is not returned to the sender as undelivered shall be deemed
      to have been given on the seventh day after the envelope containing it was
      so posted; and proof that the envelope containing any such notice or
      information was properly addressed, pre-paid, registered and posted, and
      that it has not been so returned to the sender, shall be sufficient
      evidence that the notice or information has been duly given.

10.3  Any notice or information sent by facsimile transmission or similar means
      of communication (but not electronic mail) shall be deemed to have been
      duly given on the date of transmission, provided that a confirming copy is
      sent as provided in clause 10.1(b) to the other party at the address given
      in clause 10.4 within 24 hours after transmission.

10.4  The address of either party for service of any legal proceedings
      concerning or arising out of this Agreement, or for the purposes of clause
      10.1, shall be that of its registered or principal office, or such other
      address as it may last have notified to the other party in writing from
      time to time.

                                                                  [CONFIDENTIAL]
                                     PAGE 25
<PAGE>   28

11    MISCELLANEOUS

11.1  Each sum payable pursuant to this Agreement is exclusive of any applicable
      Value Added Tax or other taxes or duties (other than taxes on profits or
      income), which shall be additionally payable by Introgen together with the
      relevant sum.

11.2  Each party shall from time to time do all such acts and execute all such
      documents as may be reasonably necessary in order to give effect to the
      provisions of this Agreement.

11.3  The parties shall bear their own costs of and incidental to the
      preparation, execution and implementation of this Agreement.

11.4  Except as required by law, neither party shall make any press or other
      public announcement concerning any aspect of this Agreement or use the
      name of the other (including, in the case of ICRT, that of ICRF) without
      first obtaining the agreement in writing of an authorised representative
      of the other party.

11.5  This Agreement may be executed in more than one counterpart and shall come
      into force once each party has executed such a counterpart in identical
      form and exchanged it with the other party.

                                                                  [CONFIDENTIAL]
                                     PAGE 26
<PAGE>   29

                                   SCHEDULE 1

                              THE EXISTING PATENTS

<TABLE>
<CAPTION>
GENE             ORIGINATING                    PATENT            DATE
                 SCIENTIST                      APPLICATION
<S>              <C>                            <C>               <C>

[*]

</TABLE>

         [*]    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.

                                                                  [CONFIDENTIAL]
                                    PAGE 27
<PAGE>   30

                                   SCHEDULE 2

                         THE TERMS OF THE FIRST LICENCE

1 Parties:          ICRT (the Licensor) and Introgen (the Licensee).

2 Definitions:      'LICENSED PRODUCT' will mean any product (i) which
                    incorporates any of the Genes, in respect of which the First
                    Option is exercised by Introgen, or (ii) the manufacture,
                    use or sale of which would in the absence of the licence
                    granted to Introgen infringe a valid claim within any of
                    the Existing Patents in respect of the Gene or Genes in
                    question in the country for which the product is sold.

                    A 'VALID CLAIM' will include the claims of issued patents
                    (including patents of addition, supplementary protection
                    certificates or similar rights based on any such patent) and
                    patent applications; provided that in the case of a patent
                    application which has not been issued, not more than [*]
                    have elapsed from the earliest priority filing date to,
                    which the claim is entitled.

                    'LICENSED SUBJECT MATTER' will mean the Existing Technology,
                    the Existing Patents and any other Intellectual Property of
                    ICRT in respect of the Existing Technology, relating to the
                    Gene or Genes in question.

                    Subject as provided above, the provisions of clause 2 shall
                    apply.

3 Licence:          ICRT will grant to Introgen an exclusive, worldwide licence,
                    with the right to grant and authorise sublicences, under the
                    Licensed Subject Matter to make, have made, use and sell
                    Licensed Products, practice any method, process or procedure
                    and otherwise exploit the Licensed Subject Matter, in each
                    case within the Field. For the avoidance of

                                                                  [CONFIDENTIAL]
                                     PAGE 28

      [*] 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>   31

                    doubt, Introgen will not have any rights in respect of any
                    [*] or in respect of any
                    [*] outside the Field.

4 Retained Rights:  Notwithstanding the foregoing, ICRT (for itself and ICRF)
                    will retain the rights under the Licensed Subject Matter
                    referred to in clause 6.8.

5 Clinical          Introgen will be responsible for conducting, directly or
  Development:      through third parties, clinical development with respect to
                    Licensed Products. Such clinical development shall include
                    carrying out clinical trials sufficient to market a Licensed
                    Product in all Major Markets. Without limiting the
                    foregoing, Introgen will use the same diligent efforts to
                    initiate and complete such clinical trials as it expends for
                    its other products being developed with similar market
                    potential. The detailed plans and budgets for clinical
                    development will be determined by Introgen in consultation
                    with ICRT (and in default of agreement settled by
                    arbitration pursuant to clause 4.3) and set forth in the
                    Agreement. Introgen will consult with and keep ICRT
                    reasonably informed relating to the scope and progress of
                    such clinical development and will provide semi-annual
                    reports to ICRT on each stage of product development.

                    'MAJOR MARKET' will mean the [*], [*] and
                    the [*].

6 Data Access:      During the term of the Agreement, Introgen will have access
                    to copies of data, reports, analyses and other information
                    in ICRT's possession or control, which are reasonably
                    necessary for Introgen's exercise of its rights under the
                    Licensed Subject Matter. In addition, ICRT will provide
                    Introgen with reasonable quantities of the Gene or Genes in
                    question from time to time.

7 Licence Fee:      Introgen shall pay to ICRT on the execution of the First
                    Licence (and on any subsequent exercise of the First Option)
                    a licence fee, in respect

                                                                  [CONFIDENTIAL]
                                     PAGE 29

      [*] 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>   32
                    of each of the Genes in respect of which the First Licence
                    is granted, of [*], which shall be non-refundable and
                    non-creditable against royalties.

8 Milestone         Upon the occurrence of the events set forth below for the
  Payments:         first Licensed Product relating to each of the Genes in
                    respect of which the First Licence is granted, Introgen will
                    make the corresponding payment below to ICRT -

<TABLE>
<CAPTION>
                     Milestone                        Amount
                     ---------                        ------

          <S>                                       <C>
          Completion of [*] trials                   [*]

          Completion of [*] trials                   [*]

          First approval for [*]                     [*]

          First approval for [*]                     [*]

          First year where Net Sales of a            [*]
          Licensed Product exceeds [*]

          TOTAL IN RESPECT OF EACH GENE              [*]
</TABLE>

                                                                  [CONFIDENTIAL]
                                     PAGE 30

      [*] 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>   33

9 Royalties:        Introgen will pay to ICRT as royalties the following
                    percentages of Net Sales by Introgen and its sublicensees,
                    based upon the aggregate Net Sales of all Licensed
                    Products in respect of each of the Genes -

<TABLE>
<CAPTION>
                                             ROYALTIES ON INCREMENTAL
          ANNUAL NET SALES                             AMOUNT
          ----------------                   ------------------------
         <S>                                 <C>
         [*]                                           [*]

         [*]                                           [*]
</TABLE>

                    The foregoing royalties will be reduced by [*] in countries
                    where no valid claim of any of the Existing Patents covers a
                    Licensed Product in respect of the Gene in question.

                    In the event that Licensed Products are sold in combination
                    with one or more other registered products for which a
                    royalty would not otherwise be due, it is understood that
                    Net Sales from the combination product will be reasonably
                    allocated as to be set forth in the First Licence.

                    In the event that Introgen or any of its Affiliates or
                    sublicensees becomes obligated to pay a royalty to a third
                    party in respect of patent rights covering the Gene or the
                    use thereof such that the total royalty burden on the Gene
                    or use thereof (prior to reductions) is in excess of [*]
                    Net Sales, Introgen may deduct [*] of such excess royalty
                    from the royalty owing to ICRT on the applicable Net Sales;
                    provided, however, that the royalty rate payable on
                    applicable Net Sales to such third party after adjustments
                    will not exceed the royalty rate payable (after adjustments)
                    to ICRT on such Net Sales (except with the consent of ICRT,
                    which consent will not be unreasonably withheld) and in no
                    case will the amount paid to ICRT be so reduced to less than
                    [*] of the amount that would otherwise be due to ICRT on
                    such Net Sales.

                                                                  [CONFIDENTIAL]
                                     PAGE 31

      [*] 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>   34

                    Each royalty payment will be accompanied by a proper
                    statement and will be made without deduction. Introgen will
                    keep proper accounts to enable the accuracy of royalty
                    payments to be confirmed, and will allow ICRT access to
                    inspect and take copies.

10 Marketing:       Introgen will be responsible for the establishment, control
                    and implementation of the promotion and marketing strategy,
                    plans and budgets for Licensed Products. Introgen will use
                    the same diligent efforts with respect to the marketing,
                    sale and promotion of Licensed Products for each Major
                    Market as Introgen expends for its own products being
                    developed with similar market potential.

11 Patent           The provisions of clauses 3.6 and 3.7 above will apply
   Prosecution:     throughout the term of the First Licence as they apply
                    during the First Option Period.

12 Miscellaneous:   Each party will keep Confidential Information of the other
                    confidential on the same terms as under clause 7 above.

                    The First Licence will be subject to termination on the same
                    terms as under clause 8 above. On termination all rights
                    will revert to ICRT.

                    Introgen will assume responsibility for the exploitation of
                    the Licensed Subject Matter and will indemnify ICRT (and
                    ICRF) accordingly. ICRT (or ICRF) will have no liability
                    howsoever arising under or in connection with the First
                    Licence for loss of profit or indirect or consequential loss
                    or for sums exceeding the amount of royalties paid by
                    Introgen.

                    Clauses 9,10 and 11 above will apply to the First Licence.

                    The First Licence will include other reasonable and
                    customary terms and conditions contained in similar
                    agreements of this type, in so far as

                                                                  [CONFIDENTIAL]
                                     PAGE 32
<PAGE>   35

                    they are consistent with the above.

                                                                  [CONFIDENTIAL]
                                     PAGE 33
<PAGE>   36

                                   SCHEDULE 3

                            OBJECTIVES OF THE PROJECT

                                      [*]

                                                                  [CONFIDENTIAL]
                                     PAGE 34

      [*] 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>   37

                                      [*]
                                                                [CONFIDENTIAL]

                                     PAGE 35

      [*] 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>   38

                                   SCHEDULE 4

                         THE TERMS OF THE SECOND LICENCE

1     'LICENSED SUBJECT MATTER' will include, in addition to the Existing
      Patents and Existing Technology, any Project Technology and Project Patent
      owned exclusively by ICRT or owned jointly by ICRT and Introgen.

2     'LICENSED PRODUCT' will mean any product (i) which incorporates any of the
      Genes, or (d) the manufacture, use or sale of which would in the absence
      of the licence granted to Introgen infringe a valid claim within any of
      the Existing Patents or the Project Patents in respect of the Gene or
      Genes in question owned exclusively by ICRT or owned jointly by ICRT and
      Introgen (or, in the latter case, would do so if the Project Patent in
      question was owned exclusively by ICRT) in the country for which the
      product is sold.

3     Royalties will be payable, at the rates specified in Schedule 2, on Net
      Sales of Licensed Products (as defined above), where the product (i)
      incorporates any of the Genes or (ii) is covered by a valid claim of an
      Existing Patent or a Project Patent owned exclusively by ICRT in respect
      of the Gene or Genes in question. The foregoing royalties will be reduced
      by [*] in countries where no valid claim of an Existing Patent or a
      Project Patent owned exclusively by ICRT covers a Licensed Product.

4     Clauses 6.3, 6.4, 6.8, and 6.9 shall apply throughout the term of the
      Second Licence.

5     Subject to paragraphs 1 to 4 above, the provisions of Schedule 2 shall
      apply with the necessary changes (and so that references to Existing
      Technology and Existing Patents shall be construed as references to
      Existing Technology and Existing Patents and/or Project Technology and
      Project Patents owned exclusively by ICRT or owned jointly by ICRT and
      Introgen).

                                                                  [CONFIDENTIAL]

      [*] 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 36
<PAGE>   39
                                   SCHEDULE 1

                              THE EXISTING PATENTS

<TABLE>
<S>                  <C>                             <C>                   <C>
GENE                 ORIGINATING SCIENTIST           PATENT APPLICATION       DATE

                                      [*]
</TABLE>

          [*] 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>   40
For IMPERIAL CANCER RESEARCH TECHNOLOGY LIMITED

/s/ JOHN C. WALL
-----------------------------------
Director

For INTROGEN THERAPEUTICS, INC.

/s/ MAHENDRA G. SHAH                       11/24/98
-----------------------------------
Director

                                                                  [CONFIDENTIAL]

                                    PAGE 37<PAGE>   1

                                                                   EXHIBIT 10.26

                           EXCLUSIVE LICENSE AGREEMENT

     This Exclusive License Agreement (this "Agreement") is made as of this 19th
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

                                      -1-
<PAGE>   2

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 one hundred twenty percent (120%) 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:

         [*] 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.

                                      -2-
<PAGE>   3

               (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.

                                      -3-
<PAGE>   4

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.

                                      -4-
<PAGE>   5

          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

         [*] 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.

                                      -5-
<PAGE>   6

[*] 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

         [*] 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.

                                      -6-
<PAGE>   7

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 [*]

         [*] 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.

                                      -7-
<PAGE>   8

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. [*]

         [*] 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.

                                      -8-
<PAGE>   9

                                      [*]

          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.

                                      -9-
<PAGE>   10

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-
<PAGE>   11

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

         [*]    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.

                                      -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,

         [*]    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.

                                      -12-
<PAGE>   13

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 Two Million Dollars
($2,000,000) per occurrence and Three Million Dollars ($3,000,000) 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.

         [*]    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.

                                      -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

         [*]    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.

                                      -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: /s/ [ILLEGIBLE]                           By: /s/ MAHENDRA G. SHAH
   ----------------------------------            -------------------------------

Name: [ILLEGIBLE]                             Name: Mahendra G. Shah
     --------------------------------              -----------------------------

Title: President, COO                         Title: Vice President
      -------------------------------               ----------------------------

CHINOOK CORPORATION

By: /s/ [ILLEGIBLE]
   ----------------------------------

Name:  [ILLEGIBLE]
      -------------------------------

Title: President
      -------------------------------

                                      -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.

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