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                                                                   EXHIBIT 10.45




                                2,859,427 SHARES

                           INTROGEN THERAPEUTICS, INC.


                             SHARES OF COMMON STOCK
                                ($.001 PAR VALUE)

                            PLACEMENT AGENT AGREEMENT

                                                               November 26, 2003


SG COWEN SECURITIES CORPORATION
FIRST ALBANY CAPITAL INC.
c/o SG Cowen Securities Corporation
1221 Avenue of the Americas
New York, New York 10020

Dear Sirs:

         INTROGEN THERAPEUTICS, INC., a Delaware corporation (the "COMPANY"),
proposes to sell to the Purchasers (defined below), pursuant to the terms of
this Placement Agent Agreement (this "AGREEMENT") and the Subscription
Agreements in the form of Exhibit A attached hereto (the "SUBSCRIPTION
AGREEMENTS") entered into with the Purchasers identified therein (each a
"PURCHASER" and, collectively, the "PURCHASERS"), an aggregate of 2,859,427
shares of Common Stock, $.001 par value (the "COMMON STOCK"), of the Company.
The aggregate 2,859,427 shares so proposed to be sold is hereinafter referred to
as the "STOCK." The Company hereby confirms its agreement with the placement
agents named in Schedule I attached hereto (the "PLACEMENT AGENTS" or, each, a
"PLACEMENT AGENT"). SG Cowen Securities Corporation is acting as the
representative of the Placement Agents and in such capacity is hereinafter
referred to as the "REPRESENTATIVE." Certain terms used herein are defined in
Section 13 hereof).

1. AGREEMENT TO ACT AS PLACEMENT AGENTS; PLACEMENT OF SECURITIES. On the basis
of the representations, warranties and agreements of the Company herein
contained, and subject to all the terms and conditions of this Agreement:

         (a) The Company hereby authorizes the Placement Agents to act as its
         exclusive agents to solicit offers for the purchase of all or part of
         the Stock from the Company in connection with the proposed offering of
         the Stock (the "OFFERING"). Until the sale of the Stock contemplated by
         this Agreement has been consummated or until this Agreement is
         otherwise terminated, the Company shall


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         not, without the prior consent of the Representative, solicit or accept
         offers to purchase the Stock otherwise than through the Placement
         Agents.

         (b) The Placement Agents agree, as agents of the Company, to use their
         best efforts to solicit offers to purchase the Stock from the Company
         on the terms and subject to the conditions set forth in the Base
         Prospectus (as defined below) and the Prospectus Supplement (as defined
         below). The Placement Agents shall make commercially reasonable efforts
         to assist the Company in obtaining performance by each Purchaser whose
         offer to purchase Stock has been solicited by the Placement Agents and
         accepted by the Company, but the Placement Agents shall not, except as
         otherwise provided in this Agreement, be obligated to disclose the
         identity of any potential purchaser or have any liability to the
         Company in the event any such purchase is not consummated for any
         reason. Under no circumstances will the Placement Agents be obligated
         to purchase any Stock for their own accounts and, in soliciting offers
         to purchase of Stock, the Placement Agents shall act solely as the
         Company's agents and not as principals. Notwithstanding the foregoing
         and except as otherwise provided in Section 1(c), it is understood and
         agreed that the Placement Agents (or their affiliates) may, solely at
         their discretion and without any obligation to do so, purchase Stock as
         principals.

         (c) Subject to the provisions of this Section 1, offers for the
         purchase of Stock may be solicited by the Placement Agents as agents
         for the Company at such times and in such amounts as the Placement
         Agents deem advisable in consultation with the Company. Each Placement
         Agent shall communicate to the Company, orally or in writing, each
         reasonable offer to purchase Stock received by it as agent of the
         Company. The Company shall have the sole right to accept offers to
         purchase the Stock and may reject any such offer, in whole or in part,
         in its sole discretion. Each Placement Agent shall have the right, in
         its discretion reasonably exercised, without notice to the Company, to
         reject any offer to purchase Stock received by it, in whole or in part,
         and any such rejection shall not be deemed a breach of its agreement
         contained herein.

         (d) The purchases of the Stock by the Purchasers shall be evidenced by
         the execution of the Subscription Agreements.

         (e) As compensation for services rendered, on the Closing Date (as
         defined below) the Company shall pay to the Placement Agents by wire
         transfer of immediately available funds to an account or accounts
         designated by the Representative, an aggregate amount equal to six
         percent (6.0%) of the gross proceeds received by the Company from the
         sale of the Stock on such Closing Date, 5.25% of such gross proceeds
         shall be paid to SG Cowen Securities Corporation and 0.75% of such
         gross proceeds shall be paid to First Albany Capital Inc.



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         (f) No Stock which the Company has agreed to sell pursuant to this
         Agreement shall be deemed to have been purchased and paid for, or sold
         by the Company, until such Stock shall have been delivered to the
         Purchaser thereof against valid payment by such Purchaser. If the
         Company shall default in its obligations to deliver Stock to a
         Purchaser whose offer it has accepted, the Company shall indemnify and
         hold the Placement Agents harmless against any loss, claim or damage
         arising from or as a result of such default by the Company.

2. REPRESENTATIONS AND WARRANTIES OF THE COMPANY. The Company represents and
warrants to, and agrees with, the Placement Agents and the Purchasers that:

         (a) At the time of filing of the registration statement referenced
         below, the Company met the requirements for use of Form S-3 under the
         Securities Act of 1933, as amended (the "SECURITIES ACT"), and has
         filed with the Securities and Exchange Commission (the "COMMISSION") a
         registration statement on such Form (Registration File No. 333-107799),
         which became effective as of August 25, 2003, for the registration
         under the Securities Act of the Stock. Such registration statement
         meets the requirements set forth in Rule 415(a)(1)(x) under the
         Securities Act and complies in all other material respects with said
         Rule. The Company will file with the Commission pursuant to Rule 424(b)
         under the Securities Act, and the rules and regulations (the "RULES AND
         REGULATIONS") of the Commission promulgated thereunder, a supplement to
         the form of prospectus included in such registration statement relating
         to a placement of the Stock and the plan of distribution thereof and
         has advised the Representative of all further information (financial
         and other) with respect to the Company to be set forth therein. Such
         registration statement, including the exhibits thereto, as amended at
         the date of this Agreement, as applicable, is hereinafter called the
         "REGISTRATION STATEMENT"; such prospectus in the form in which it
         appears in the Registration Statement is hereinafter called the "BASE
         PROSPECTUS"; and the supplemented form of prospectus, in the form in
         which it will be filed with the Commission pursuant to Rule 424(b)
         (including the Base Prospectus as so supplemented) is hereinafter
         called a "PROSPECTUS SUPPLEMENT." Any reference herein to the
         Registration Statement, the Base Prospectus or the Prospectus
         Supplement shall be deemed to refer to and include the documents
         incorporated by reference therein (the "INCORPORATED DOCUMENTS")
         pursuant to Item 12 of Form S-3 which were filed under the Securities
         Exchange Act of 1934, as amended (the "EXCHANGE ACT"), on or before the
         date of this Agreement, or the date of the Base Prospectus or the
         Prospectus Supplement, as the case may be; and any reference herein to
         the terms "amend," "amendment" or "supplement" with respect to the
         Registration Statement, the Base Prospectus or the Prospectus
         Supplement shall be deemed to refer to and include the filing of any
         document under the Exchange Act after the date of this Agreement, or
         the date of the Base Prospectus or the Prospectus Supplement, as the
         case may be, deemed to be incorporated therein by reference. All
         references in this Agreement to financial statements and schedules and
         other information which is "contained," "included," "described," "set
         forth" or "stated" in the Registration Statement, the Base Prospectus
         or the Prospectus Supplement



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<PAGE>

         (and all other references of like import) shall be deemed to mean and
         include all such financial statements and schedules and other
         information which is or is deemed to be incorporated by reference in
         the Registration Statement, the Base Prospectus or the Prospectus
         Supplement, as the case may be. No stop order suspending the
         effectiveness of the Registration Statement or the use of the Base
         Prospectus or the Prospectus Supplement has been issued, and no
         proceeding for any such purpose is pending or has been initiated or, to
         the Company's knowledge, is threatened by the Commission.

         (b) The Registration Statement (and any post-effective amendment
         thereto to be filed with the Commission) contains all exhibits and
         schedules as required by the Securities Act. Each of the Registration
         Statement and any post-effective amendment thereto, at the time it
         became effective, complied in all material respects with the Securities
         Act and the Exchange Act and the applicable Rules and Regulations and
         did not and, as amended or supplemented, if applicable, will not, as of
         the effective date thereof, the date hereof or the Closing Date (as
         defined below), contain any untrue statement of a material fact or omit
         to state a material fact required to be stated therein or necessary to
         make the statements therein not misleading. Each of the Base Prospectus
         and the Prospectus Supplement, as of its respective date, complies in
         all material respects with the Securities Act and the Exchange Act and
         the applicable Rules and Regulations. Each of the Base Prospectus and
         the Prospectus Supplement, as amended or supplemented, if applicable,
         did not and will not contain as of the effective date thereof any
         untrue statement of a material fact or omit, as of the effective date
         thereof, to state a material fact necessary in order to make the
         statements therein, in light of the circumstances under which they were
         made, not misleading. The Incorporated Documents, when they were filed
         with the Commission, conformed in all material respects to the
         requirements of the Exchange Act and the applicable Rules and
         Regulations, and none of such documents, when they were filed with the
         Commission, contained any untrue statement of a material fact or
         omitted to state a material fact necessary to make the statements
         therein not misleading; and any further documents so filed and
         incorporated by reference in the Base Prospectus or Prospectus
         Supplement, when such documents are filed with the Commission, will
         conform in all material respects to the requirements of the Exchange
         Act and the applicable Rules and Regulations, as applicable, and will
         not contain any untrue statement of a material fact or omit to state a
         material fact necessary to make the statements therein, in light of the
         circumstances under which they were made, not misleading.
         Notwithstanding the foregoing, the Company makes no representations or
         warranties as to information, if any, contained in or omitted from the
         Prospectus Supplement or any amendment thereof or supplement thereto in
         reliance upon and in conformity with information furnished in writing
         to the Company by or on behalf of any Placement Agent specifically for
         use in the Registration Statement or the Prospectus Supplement. No
         post-effective amendment to the Registration Statement reflecting any
         facts or events arising after the date hereof which represent,
         individually or in the aggregate, a fundamental change in the
         information set forth therein is required to be filed with the
         Commission. There are no documents required to be filed with



                                       4
<PAGE>

         the Commission in connection with the transaction contemplated hereby
         that have not been filed as required pursuant to the Securities Act or
         will not be filed within the requisite time period. There are no
         contracts or other documents required to be described in the Base
         Prospectus or Prospectus Supplement, or to be filed as exhibits or
         schedules to the Registration Statement, which have not been described
         or filed as required.

         (c) The Company has delivered, or will as promptly as practicable
         deliver, to the Representative complete conformed copies of the
         Registration Statement and of each consent and certificate of experts
         filed as a part thereof, and conformed copies of the Registration
         Statement (without exhibits) and the Base Prospectus and the Prospectus
         Supplement, as amended or supplemented, in such quantities and at such
         places as the Representative reasonably requests. The Company has not
         distributed and will not distribute, prior to the completion of the
         distribution of the Stock, any offering material in connection with the
         offering and sale of the Stock other than the Base Prospectus and the
         Prospectus Supplement or the Registration Statement and copies of the
         documents incorporated by reference therein.

         (d) The Company and each of its subsidiaries have been duly organized
         and are validly existing as corporations or other legal entities in
         good standing (or the equivalent thereof, if any) under the laws of
         their respective jurisdictions of incorporation, are duly qualified to
         do business and are in good standing (or the equivalent thereof, if
         any) as foreign corporations in each jurisdiction in which their
         respective ownership or lease of property or the conduct of their
         respective businesses requires such qualification, and have all
         corporate power and authority necessary to own or hold their respective
         properties and to conduct the businesses in which they are engaged,
         except where the failure to be so qualified and in good standing or
         have such power or authority would not have, singularly or in the
         aggregate, a material adverse effect on the condition (financial or
         otherwise), results of operations, business, properties or prospects of
         the Company and its subsidiaries taken as a whole (a "MATERIAL ADVERSE
         EFFECT").

         (e) Except as set forth in the Base Prospectus and Prospectus
         Supplement, the Stock to be issued and sold by the Company hereunder
         and under the Subscription Agreements has been duly and validly
         authorized and, when issued and delivered against payment therefor as
         provided herein, will be duly and validly issued, fully paid and
         nonassessable and free of any preemptive rights and will conform to the
         description thereof contained in the Base Prospectus and the Prospectus
         Supplement.

         (f) The Company has an authorized capitalization as set forth in the
         Base Prospectus and the Prospectus Supplement, all of the issued shares
         of capital stock of the Company have been duly and validly authorized
         and issued, are fully paid and non-assessable and conform to the
         description thereof contained in the Base Prospectus and the Prospectus
         Supplement and, except as set forth in the Base Prospectus and the
         Prospectus Supplement, no options, warrants or other



                                       5
<PAGE>

         rights to purchase, agreements or other obligations to issue, or rights
         to convert any obligations into or exchange any securities for, shares
         of capital stock of, or ownership interests in, the Company are
         outstanding.

         (g) All the outstanding shares of capital stock of each subsidiary of
         the Company have been duly authorized and validly issued, are fully
         paid and nonassessable and, except to the extent set forth in the Base
         Prospectus and the Prospectus Supplement, are owned by the Company
         directly or indirectly through one or more wholly-owned subsidiaries,
         free and clear of any claim, lien, encumbrance, security interest,
         restriction upon voting or transfer or any other claim of any third
         party. The Company owns or controls, directly or indirectly, only the
         following corporations, associations or other entities: Gendux, Inc.,
         Gendux AB and TMX Realty Corporation. In addition, the Company owns
         1,517,145 shares of the Series A Preferred Stock of VirRx, Inc.

         (h) The Company has the full right, power and authority to enter into
         this Agreement and each of the Subscription Agreements and to perform
         and to discharge its obligations hereunder and thereunder; and each of
         this Agreement and each of the Subscription Agreements has been duly
         authorized, executed and delivered by the Company, and constitutes a
         valid and binding obligation of the Company enforceable in accordance
         with its terms.

         (i) The execution, delivery and performance of this Agreement and the
         Subscription Agreements by the Company and the consummation of the
         transactions contemplated hereby and thereby will not conflict with or
         result in a breach or violation of any of the terms or provisions of,
         or constitute a default under, any indenture, mortgage, deed of trust,
         loan agreement or other agreement or instrument to which the Company or
         any of its subsidiaries is a party or by which the Company or any of
         its subsidiaries is bound or to which any of the property or assets of
         the Company or any of its subsidiaries is subject, nor will such
         actions result in any violation of the provisions of the charter or
         by-laws of the Company or any of its subsidiaries or any statute, law,
         rule or regulation or any judgment, order or decree of any court or
         governmental agency or body having jurisdiction over the Company or any
         of its subsidiaries or any of their properties or assets.

         (j) There is no franchise, contract, lease, instrument or other
         document of a character required by the Securities Act or the Rules and
         Regulations to be described in the Base Prospectus and the Prospectus
         Supplement, or to be filed as an exhibit to the Registration Statement,
         which is not described or filed as required; and all statements
         summarizing any such franchises, contracts, leases, instruments or
         other documents or legal matters contained in the Registration
         Statement are accurate and complete in all material respects.

         (k) All existing minute books of the Company, including all existing
         records of all meetings and actions of the board of directors
         (including the Audit and Compensation Committees) and stockholders of
         the Company through the date of



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         the latest meeting and action (collectively, the "CORPORATE RECORDS")
         have been made available to the Placement Agents and counsel for the
         Placement Agents. All such Corporate Records are complete and
         accurately reflect, in all material respects, all transactions referred
         to in such Corporate Records. There are no material transactions or
         agreements of the Company required to be approved by the board of
         directors or stockholders of the Company that are not properly approved
         and/or recorded in the Corporate Records.

         (l) No consent, approval, authorization, filing with or order of or
         registration with, any court or governmental agency or body is required
         in connection with the transactions contemplated herein, except a
         filing of a listing of additional shares notice with the Nasdaq
         National Market, and except such as have been obtained or made under
         the Securities Act or the Exchange Act and such as may be required
         under the securities, or blue sky, laws of any jurisdiction in
         connection with the offer and sale of the Stock by the Company in the
         manner contemplated herein and in the Base Prospectus and the
         Prospectus Supplement.

         (m) Except as described in the Base Prospectus and the Prospectus
         Supplement, no person or entity has the right to require registration
         of shares of Common Stock or other securities of the Company because of
         the filing or effectiveness of the Registration Statement or otherwise,
         except for persons and entities who have expressly waived such right or
         who have been given proper notice and have failed to exercise such
         right within the time or times required under the terms and conditions
         of such right, and the Company is not required to file any registration
         statement for the registration of any securities of any person or
         register any such securities pursuant to any other registration
         statement filed by the Company under the Securities Act for a period of
         at least 180 days after the date hereof.

         (n) The financial statements, together with the related notes and
         schedules, of the Company included in the Base Prospectus, the
         Prospectus Supplement or the Registration Statement, or incorporated by
         reference therein, present fairly the financial condition, results of
         operations and cash flows of the Company and its consolidated
         subsidiaries as of the dates and for the periods indicated, comply as
         to form with the applicable accounting requirements of the Securities
         Act and have been prepared in conformity with generally accepted
         accounting principles of the United States applied on a consistent
         basis throughout the periods involved.

         (o) Except as set forth in the Base Prospectus and the Prospectus
         Supplement, there is no legal or governmental proceeding pending to
         which the Company or any of its subsidiaries is a party or of which any
         property or assets of the Company or any of its subsidiaries is the
         subject which, singularly or in the aggregate, if determined adversely
         to the Company or any of its subsidiaries, would reasonably be expected
         to have a Material Adverse Effect or would prevent or adversely affect
         the ability of the Company to perform its obligations under this
         Agreement; and to the best of the Company's knowledge, no such
         proceedings are threatened or contemplated.



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         (p) The Company and each of its subsidiaries have good and marketable
         title in fee simple to, or have valid rights to lease or otherwise use,
         all items of real or personal property which are material to the
         business of the Company and its subsidiaries taken as a whole, in each
         case free and clear of all liens, encumbrances, claims and defects that
         would reasonably be expected to result in a Material Adverse Effect.

         (q) Except as set forth in the Base Prospectus and Prospectus
         Supplement, neither the Company nor any of its subsidiaries is (i) in
         violation of any provision of its charter or bylaws, (ii) is in default
         in any respect, and no event has occurred which, with notice or lapse
         of time or both, would constitute such a default, in the due
         performance or observance of any term, covenant, or condition of any
         indenture, contract, lease, mortgage, deed of trust, note agreement,
         loan agreement or other agreement, obligation, condition, covenant or
         instrument to which it is a party or by which it is bound or to which
         any of its property or assets is subject, or (iii) is in violation in
         any respect of any statute, law, rule, regulation, ordinance, judgment,
         order or decree of any court, regulatory body, administrative agency,
         governmental body, arbitrator or other authority having jurisdiction
         over the Company, its subsidiaries or any of its properties, as
         applicable (including, without limitation, those administered by the
         Food and Drug Administration of the U.S. Department of Health and Human
         Services (the "FDA") or by any foreign, federal, state or local
         governmental or regulatory authority performing functions similar to
         those performed by the FDA), except, with respect to clauses (ii) and
         (iii), any violations or defaults which, singularly or in the
         aggregate, would not have a Material Adverse Effect.

         (r) The contracts described in the Company's reports on Forms 10-Q,
         10-K, and 8-K as filed by the Company with the Commission or
         incorporated by reference therein that are material to the Company and
         necessary to the continuing business of the Company taken as a whole
         are in full force and effect on the date hereof (except those that have
         been terminated or expired by their terms), and neither the Company
         nor, to the Company's knowledge, any other party to such contracts is
         in breach of or default under any of such contracts, which breach would
         have a Material Adverse Effect.

         (s) No labor problem or dispute with the employees of the Company
         exists or, to the Company's knowledge, is threatened or imminent, which
         might be expected to have a Material Adverse Effect. The Company is not
         aware that any key employee or significant group of employees of the
         Company or any subsidiary whose departure would have a Material Adverse
         Effect plans to terminate employment with the Company or any such
         subsidiary.

         (t) No "PROHIBITED TRANSACTION" (as defined in Section 406 of the
         United States Employee Retirement Income Security Act of 1974
         ("ERISA"), or Section 4975 of the Internal Revenue Code of 1986, as
         amended from time to time (the "CODE")) has occurred with respect to
         any employee benefit plan which could have a Material Adverse Effect.
         Each "PENSION PLAN" (as defined in ERISA) for



                                       8
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         which the Company would have any liability that is intended to be
         qualified under Section 401(a) of the Code is so qualified in all
         material respects and nothing has occurred, whether by action or by
         failure to act, which, to the Company's knowledge, could cause the loss
         of such qualification.

         (u) Except as set forth in the Base Prospectus and the Prospectus
         Supplement, the Company and each of its subsidiaries is insured by
         insurers of recognized financial responsibility against such losses and
         risks and in such amounts as are customary in the businesses in which
         they are engaged; all policies of insurance and fidelity or surety
         bonds insuring the Company and each of its subsidiaries and their
         businesses, assets, employees, officers and directors are in full force
         and effect; the Company and each of its subsidiaries is in compliance
         with the terms of such policies and instruments in all material
         respects; and there are no claims by the Company and each of its
         subsidiaries under any such policy or instrument as to which any
         insurance company is denying liability or defending under a reservation
         of rights clause; the Company and each of its subsidiaries has not been
         refused any insurance coverage sought or applied for; and the Company
         and each of its subsidiaries has no reason to believe that it will not
         be able to renew its existing insurance coverage as and when such
         coverage expires or to obtain similar coverage from similar insurers as
         may be necessary to continue its business at a cost that would not have
         a Material Adverse Effect, except as set forth in the Base Prospectus
         or the Prospectus Supplement.

         (v) Except as set forth in the Base Prospectus and the Prospectus
         Supplement, the Company has made all filings, applications and
         submissions required by, and possesses all approvals, licenses,
         certificates, certifications, clearances, consents, exemptions, marks,
         notifications, orders, permits and other authorizations issued by, the
         appropriate federal, state or foreign regulatory authorities
         (including, without limitation, the FDA, and any other foreign,
         federal, state or local government or regulatory authorities performing
         functions similar to those performed by the FDA) necessary to conduct
         its businesses (collectively, "PERMITS"), except for such Permits which
         the failure to obtain would not have a Material Adverse Effect, and is
         in compliance with the terms and conditions of all such Permits; all of
         such Permits held by the Company and each of its subsidiaries are valid
         and in full force and effect; there is no pending or threatened action,
         suit, claim or proceeding which may cause any such Permit to be
         limited, revoked, cancelled, suspended, modified or not renewed and the
         Company and each of its subsidiaries has not received any notice of
         proceedings relating to the limitation, revocation, cancellation,
         suspension, modification or non-renewal of any such Permit which,
         singly or in the aggregate, if the subject of an unfavorable decision,
         ruling or finding, would have a Material Adverse Effect, whether or not
         arising from transactions in the ordinary course of business, except as
         set forth in or contemplated by the Base Prospectus or the Prospectus
         Supplement.

         (w) Ernst & Young LLP, who have certified certain financial statements
         of the Company and delivered their report with respect to the audited
         consolidated financial statements and schedules included in the Base
         Prospectus, the



                                       9
<PAGE>

         Prospectus Supplement or the Registration Statement, or incorporated by
         reference therein, are, to the Company's knowledge, independent public
         accountants with respect to the Company within the meaning of the
         Securities Act and the Rules and Regulations.

         (x) The Company and each of its subsidiaries has filed all foreign,
         federal, state and local tax returns that are required to be filed or
         has requested extensions thereof (except in any case in which the
         failure so to file would not have a Material Adverse Effect, except as
         set forth in the Base Prospectus and the Prospectus Supplement) and has
         paid all taxes required to be paid by it and any other assessment, fine
         or penalty levied against it, to the extent that any of the foregoing
         is due and payable, except for any such assessment, fine or penalty
         that is currently being contested in good faith or as would not have a
         Material Adverse Effect, except as set forth in the Base Prospectus and
         the Prospectus Supplement.

         (y) The principal executive officer and principal financial officer of
         the Company have made all certifications required by the Sarbanes-Oxley
         Act of 2002 and the rules and regulations promulgated in connection
         therewith (the "SARBANES-OXLEY ACT"), and the statements contained in
         any such certification are, to the Company's knowledge, complete and
         correct. The Company maintains "disclosure controls and procedures" (as
         defined in Rule 13a-14(c) under the Exchange Act), and such controls
         and procedures are designed (i) to ensure that information required to
         be disclosed by the Company in the reports that it files or submits
         under the Exchange Act is recorded, processed, summarized and reported,
         within the time periods specified in the Commission's rules and forms
         and (ii) to ensure that information required to be disclosed by the
         Company in the reports that it files or submits under the Exchange Act
         is accumulated and communicated to the Company's management, including
         its principal executive officer and principal financial officer, as
         appropriate to allow timely decisions regarding required disclosure.
         The Company does not have any material weaknesses in internal controls,
         and there has been no fraud, whether or not material, that involves
         management or other employees who have a significant role in the
         Company's internal controls. The Company is otherwise in compliance in
         all material respects with all applicable effective provisions of the
         Sarbanes-Oxley Act and the rules and regulations promulgated by the
         Commission (and intends to comply with all applicable provisions that
         are not yet effective upon effectiveness).

         (z) The Company and each of its subsidiaries maintains a system of
         internal accounting controls sufficient to provide reasonable assurance
         that (i) transactions are executed in accordance with management's
         general or specific authorizations; (ii) transactions are recorded as
         necessary to permit preparation of financial statements in conformity
         with generally accepted accounting principles and to maintain
         accountability of assets; (iii) access to assets is permitted only in
         accordance with management's general or specific authorization; and
         (iv) the recorded accountability for assets is compared with the
         existing assets at


                                       10
<PAGE>

         reasonable intervals and appropriate action is taken with respect to
         any differences.

         (aa) Neither the Company nor any of its subsidiaries nor, to the
         Company's knowledge, any of their officers, directors or affiliates has
         taken or will take, directly or indirectly, any action designed or
         intended to stabilize or manipulate (as such terms are used or defined
         in Regulation M promulgated under the Exchange Act) the price of any
         security of the Company, or which caused or resulted in, or which might
         in the future reasonably be expected to cause or result in,
         stabilization or manipulation of the price of any security of the
         Company.

         (bb) The Company and each of its subsidiaries (i) is in compliance in
         all material respects with any and all applicable foreign, federal,
         state and local laws and regulations relating to the protection of
         human health and safety, the environment or hazardous or toxic
         substances or wastes, pollutants or contaminants ("ENVIRONMENTAL
         Laws"), (ii) has received and is in compliance with all permits,
         licenses or other approvals required of it under applicable
         Environmental Laws to conduct its business and (iii) has not received
         notice of any actual or potential liability for the investigation or
         remediation of any disposal or release of hazardous or toxic substances
         or wastes, pollutants or contaminants, except where such non-compliance
         with Environmental Laws, failure to receive required permits, licenses
         or other approvals, or liability would not, individually or in the
         aggregate, have a Material Adverse Effect, whether or not arising from
         transactions in the ordinary course of business, except as set forth in
         or contemplated by the Base Prospectus and the Prospectus Supplement
         (exclusive of any supplement thereto). The Company has not been named
         as a "POTENTIALLY RESPONSIBLE PARTY" under the Comprehensive
         Environmental Response, Compensation, and Liability Act of 1980, as
         amended.

         (cc) There has been no storage, disposal, generation, manufacture,
         refinement, transportation, handling or treatment of medical wastes,
         toxic wastes, hazardous wastes or hazardous substances by the Company
         or its subsidiaries (or, to the Company's knowledge, any of their
         predecessors in interest) at, upon or from any of the property now or
         previously owned or leased by the Company or its subsidiaries in
         violation of any applicable Environmental Law which would require
         remedial action under any applicable Environmental Law, except for any
         violation or remedial action which would not cause, singularly or in
         the aggregate with all such violations and remedial actions, a Material
         Adverse Effect; there has been no material spill, discharge, leak,
         emission, injection, escape, dumping or release of any kind onto such
         property or of any medical wastes, toxic wastes, hazardous wastes or
         hazardous substances due to or caused by the Company or its
         subsidiaries or with respect to which the Company or its subsidiaries
         had knowledge, except for any such spill, discharge, leak, emission,
         injection, escapes, dumpings or releases which would not cause or would
         not be reasonably likely to cause, singularly or in the aggregate with
         all such spills, discharges, leaks, emissions, injections, escapes,
         dumpings or releases, a Material Adverse Effect; and the terms
         "hazardous substances," "toxic wastes," "hazardous wastes"



                                       11
<PAGE>

         and "medical wastes" shall have the meanings specified in any
         applicable Environmental Laws.

         (dd) The Company has evaluated the effect of Environmental Laws on its
         business, operations and properties, in the course of which it
         identifies and evaluates associated costs and liabilities. On the basis
         of such review, the Company has reasonably concluded that such
         associated costs and liabilities would not, singly or in the aggregate,
         have a Material Adverse Effect, whether or not arising from
         transactions in the ordinary course of business, except as set forth in
         or contemplated by the Base Prospectus and the Prospectus Supplement.

         (ee) The Company and its subsidiaries own, possess, license or have
         other rights to use all foreign and domestic patents, patent
         applications, trade and service marks, trade and service mark
         registrations, trade names, copyrights, licenses, inventions, trade
         secrets, technology, Internet domain names, know-how and other
         intellectual property (collectively, the "INTELLECTUAL PROPERTY")
         necessary for the conduct of the Company's business as now conducted or
         as proposed in the Base Prospectus and the Prospectus Supplement to be
         conducted. Except as set forth in the Base Prospectus and the
         Prospectus Supplement (a) there are no rights of third parties to any
         such Intellectual Property; (b) to the best of the Company's knowledge,
         there is no infringement by third parties of any such Intellectual
         Property; (c) there is no pending or, to the best of the Company's
         knowledge, threatened action, suit, proceeding or claim by others
         challenging the Company's and its subsidiaries' rights in or to any
         such Intellectual Property, except as set forth in the Base Prospectus
         and the Prospectus Supplement, and the Company is unaware of any facts
         which would form a reasonable basis for any such claim; (d) there is no
         pending or, to the best of the Company's knowledge, threatened action,
         suit, proceeding or claim by others challenging the validity or scope
         of any such Intellectual Property, except as set forth in the Base
         Prospectus and the Prospectus Supplement; (e) there is no pending or,
         to the best of the Company's knowledge, threatened action, suit,
         proceeding or claim by others that the Company and its subsidiaries
         infringe or otherwise violate any patent, trademark, copyright, trade
         secret or other proprietary rights of others, and the Company is
         unaware of any other fact which would form a reasonable basis for any
         such claim, except as set forth in the Base Prospectus and the
         Prospectus Supplement; (f) to the Company's knowledge, there is no
         third-party U.S. patent or published U.S. patent application which
         contains claims for which an Interference Proceeding could be commenced
         against any patent or patent application described in the Base
         Prospectus and the Prospectus Supplement as being owned by or licensed
         to the Company; and (g) the Company and its subsidiaries have taken all
         steps necessary to perfect its ownership of the Intellectual Property.

         (ff) Except as set forth in the Base Prospectus and the Prospectus
         Supplement, the clinical, pre-clinical and other studies and tests
         conducted by or on behalf of or sponsored by the Company and its
         subsidiaries were and, if still pending, are being conducted in
         accordance with all statutes, laws, rules and regulations, as


                                       12
<PAGE>

         applicable (including, without limitation, those administered by the
         FDA or by any foreign, federal, state or local governmental or
         regulatory authority performing functions similar to those performed by
         the FDA), except where the failure to observe such statutes, laws,
         rules and regulations would not cause, singularly or in the aggregate
         with all such violations, a Material Adverse Effect. The descriptions
         of the results of such studies and tests are accurate and complete in
         all material respects and fairly present the published data derived
         from such studies and tests, and the Company has no knowledge of other
         studies or tests the results of which call into question the results
         described or referred to in the Base Prospectus and the Prospectus
         Supplement, except as described in the Base Prospectus and the
         Prospectus Supplement. Neither the Company nor any of its subsidiaries
         has received any notices or other correspondence from the FDA or any
         other foreign, federal, state or local governmental or regulatory
         authority performing functions similar to those performed by the FDA
         with respect to any ongoing clinical or pre-clinical studies or tests
         that would presently require the termination, suspension or
         modification of such studies or tests.

         (gg) Except as set forth in the Base Prospectus and Prospectus
         Supplement, neither the Company nor any of its subsidiaries has failed
         to file with the applicable regulatory authorities (including, without
         limitation, the FDA or any foreign, federal, state or local
         governmental or regulatory authority performing functions similar to
         those performed by the FDA) any required filing, declaration, listing,
         registration, report or submission; all such filings, declarations,
         listings, registrations, reports or submissions were in compliance with
         applicable laws when filed and no deficiencies have been asserted by
         any applicable regulatory authority (including, without limitation, the
         FDA or any foreign, federal, state or local governmental or regulatory
         authority performing functions similar to those performed by the FDA)
         with respect to any such filings, declarations, listings,
         registrations, reports or submissions, except where such failure would
         not cause, singularly or in the aggregate with all such failures, a
         Material Adverse Effect.

         (hh) No relationship, direct or indirect, exists between or among the
         Company on the one hand and the directors, officers, stockholders,
         customers or suppliers of the Company on the other hand which is
         required to be described in the Base Prospectus and the Prospectus
         Supplement and which is not so described.

         (ii) Neither the Company nor, to the Company's knowledge, any other
         person associated with or acting on behalf of the Company including,
         without limitation, any director, officer, agent or employee of the
         Company or any of its subsidiaries, has, directly or indirectly, while
         acting on behalf of the Company or any of its subsidiaries (i) used any
         corporate funds for unlawful contributions, gifts, entertainment or
         other unlawful expenses, or received or retained any funds, relating to
         political activity; (ii) made any unlawful payment from corporate funds
         to, or received or retained any unlawful funds from, foreign or
         domestic government officials or employees or to or from foreign or
         domestic political parties or campaigns; (iii) violated any provision
         of the Foreign Corrupt Practices



                                       13
<PAGE>

         Act of 1977, as amended; or (iv) made any other unlawful payment or
         received or retained any other unlawful funds.

         (jj) Neither the Company nor any of its subsidiaries is or, after
         giving effect to the offering and sale of the Stock and the application
         of the proceeds thereof as described in the Base Prospectus and the
         Prospectus Supplement, will become an "INVESTMENT COMPANY" as defined
         in the Investment Company Act of 1940, as amended.

         (kk) No forward-looking statement (within the meaning of Section 27A of
         the Securities Act and Section 21E of the Exchange Act) contained in
         the Base Prospectus and the Prospectus Supplement has been made or
         reaffirmed without a reasonable basis or has been disclosed other than
         in good faith.

         (ll) Other than as contemplated by this Agreement, neither the Company
         nor any of its subsidiaries is a party to any contract, agreement or
         understanding with any person that would give rise to a valid claim
         against the Company or the Placement Agents for a brokerage commission,
         finder's fee or like payment in connection with the offering and sale
         of the Stock.

         (mm) Neither the Company nor any of its subsidiaries has sustained,
         since the date of the latest audited financial statements included in
         the Base Prospectus, the Prospectus Supplement or the Registration
         Statement, or incorporated by reference therein, any material loss or
         interference with its business from fire, explosion, flood, terrorist
         act or other calamity, whether or not covered by insurance, or from any
         labor dispute or court or governmental action, order or decree,
         otherwise than as set forth in or contemplated by the Base Prospectus
         and the Prospectus Supplement; and, since such date, there has not been
         any change in the capital stock or long-term debt of the Company, or
         any Material Adverse Effect, otherwise than as set forth or
         contemplated by the Base Prospectus and the Prospectus Supplement.

         (nn) The Stock is duly listed and admitted and authorized for trading,
         subject to official notice of issuance, on the Nasdaq National Market.

         (oo) There are no affiliations with the NASD among the Company's
         officers, directors or, to the best of the Company's knowledge, any
         five percent or greater stockholder of the Company, except as set forth
         in the Base Prospectus, the Prospectus Supplement or the Registration
         Statement or otherwise disclosed in writing to the Representative.

         (pp) Other than the execution of the Subscription Agreements by the
         Company, the Company has not entered into any side letters, ancillary
         agreements, supplemental arrangements or other similar documents with
         any of the Purchasers relating to the sale of the Stock.

         Any certificate signed by any officer of the Company and delivered to
the Placement Agents or counsel for the Placement Agents in connection with the
offering of



                                       14
<PAGE>

the Stock shall be deemed a representation and warranty by the Company and its
subsidiaries, as to the matters covered thereby, to the Placement Agents and the
Purchasers.

3. THE CLOSING. The time and date of closing and delivery of the documents
required to be delivered to the Placement Agents pursuant to Section 6 hereof
shall be at 9:00 A.M., local time, on December 2, 2003 (the "CLOSING DATE") at
the office of Wilson Sonsini Goodrich & Rosati, counsel for the Company, at 8911
Capital of Texas Highway North, Westech 360, Suite 3350, Austin, Texas. Subject
to the terms and conditions hereof, payment of the purchase price for the Stock
shall be made to the Company by Federal funds wire transfer, against delivery of
the certificates for the Stock, through the facilities of The Depository Trust
Company ("DTC"), to such persons, and shall be registered in such name or names
and shall be in such denominations, as the Representative may request at least
one business day before the time of purchase. Payment of the purchase price for
the Stock shall be made at the time of purchase by the Purchasers thereof,
through an escrow agent, to the Company. Electronic transfer of the Stock shall
be made at the time of purchase in such names and in such denominations as the
Representative shall specify.

4. FURTHER AGREEMENTS OF THE COMPANY. The Company agrees with the Placement
Agents and the Purchasers:

         (a) (i) to make no further amendment or supplement prior to the Closing
         Date to the Registration Statement or any amendment or supplement to
         the Prospectus Supplement, without prior notice to the Representative;
         (ii) for so long as the delivery of a prospectus is required in
         connection with the offering or sale of the Stock, to advise the
         Representative promptly after it receives notice thereof, of the time
         when any amendment to the Registration Statement has been filed or
         becomes effective or any supplement to the Prospectus Supplement or any
         amended Prospectus Supplement has been filed and to furnish the
         Representative with copies thereof; (iii) to file promptly all reports
         and any definitive proxy or information statements required to be filed
         by the Company with the Commission pursuant to Section 13(a), 15 or
         15(d) of the Exchange Act subsequent to the date of the Prospectus
         Supplement and for so long as the delivery of a prospectus is required
         in connection with the offering or sale of the Stock; (iv) to advise
         the Representative, promptly after it receives notices thereof, (x) of
         any request by the Commission to amend the Registration Statement or to
         amend or supplement the Prospectus Supplement or for additional
         information and (y) of the issuance by the Commission of any stop order
         suspending the effectiveness of the Registration Statement or any
         post-effective amendment thereto or any order directed at any
         Incorporated Document or any amendment or supplement thereto or any
         order preventing or suspending the use of the Base Prospectus or the
         Prospectus Supplement or any amendment or supplement thereto, of the
         suspension of the qualification of the Stock for offering or sale in
         any jurisdiction, of the institution or threatening of any proceeding
         for any such purpose, or of any request by the Commission for the
         amending or supplementing of the Registration Statement or Prospectus
         Supplement or for additional information; and, (v) in the event of the



                                       15
<PAGE>

         issuance of any stop order or of any order preventing or suspending the
         use of the Base Prospectus or Prospectus Supplement or suspending any
         such qualification, promptly to use its reasonable best efforts to
         obtain the withdrawal of such order.

         (b) To comply with the Securities Act and the Exchange Act, and the
         Rules and Regulations thereunder, so as to permit the completion of the
         distribution of the Stock as contemplated in this Agreement and the
         Prospectus Supplement. If during the period in which a prospectus is
         required by law to be delivered by a Placement Agent in connection with
         the distribution of Stock contemplated by the Prospectus Supplement,
         any event shall occur as a result of which, in the judgment of the
         Company or in the reasonable opinion of the Placement Agents or counsel
         for the Placement Agents, it becomes necessary to amend or supplement
         the Prospectus Supplement in order to make the statements therein, in
         the light of the circumstances existing at the time the Prospectus
         Supplement is delivered to a purchaser, not misleading, or, if it is
         necessary at any time to amend or supplement the Prospectus Supplement
         to comply with any law, the Company promptly will prepare and file with
         the Commission, and furnish at its own expense to the Representative,
         an appropriate amendment to the Registration Statement or supplement to
         the Prospectus Supplement so that the Prospectus Supplement as so
         amended or supplemented will not, in the light of the circumstances
         when it is so delivered, be misleading, or so that the Prospectus
         Supplement will comply with such law. Before amending the Registration
         Statement or supplementing the Base Prospectus in connection with the
         Offering, the Company will furnish the Representative with a copy of
         such proposed amendment or supplement and will not file such amendment
         or supplement to which the Representative reasonably objects.

         (c) To deliver promptly to the Representative such number of the
         following documents as the Representative shall reasonably request: (i)
         conformed copies of the Registration Statement as originally filed with
         the Commission and each amendment thereto (in each case excluding
         exhibits), (ii) the Base Prospectus, (iii) the Prospectus Supplement
         (not later than 10:00 A.M., New York time, on the Business Day
         following the execution and delivery of this Agreement) and any
         amendment or supplement thereto (not later than 10:00 A.M., New York
         City time, on the Business Day following the date of such amendment or
         supplement); and (iv) any document incorporated by reference in the
         Base Prospectus or Prospectus Supplement. The Company will pay the
         expenses of printing or other production of all documents relating to
         the Offering.

         (d) To make generally available to its stockholders as soon as
         practicable, but in any event not later than eighteen months after the
         effective date of the Registration Statement (as defined in Rule 158(c)
         under the Securities Act), an earnings statement of the Company (which
         need not be audited) complying with Section 11(a) of the Securities Act
         and the Rules and Regulations (including, at the option of the Company,
         Rule 158).



                                       16
<PAGE>

         (e) To promptly take from time to time such actions as the
         Representative may reasonably request to qualify the Stock for offering
         and sale under the securities, or blue sky, laws of such jurisdictions
         as the Representative may designate and to continue such qualifications
         in effect for so long as required for the distribution of the Stock,
         and the Company will pay the fee of the National Association of
         Securities Dealers, Inc. ("NASD") in connection with its review of the
         Offering. The Company shall not be obligated to qualify as a foreign
         corporation in any jurisdiction in which it is not so qualified or to
         file a general consent to service of process in any jurisdiction.

         (f) Not to directly or indirectly offer, sell, assign, transfer,
         pledge, contract to sell, or otherwise dispose of any shares of Common
         Stock or securities convertible into or exercisable or exchangeable for
         Common Stock for a period of 45 days from the date of the Prospectus
         Supplement without the prior written consent of the Representative,
         other than the Company's sale of the Stock and the issuance of shares
         or options to purchase shares pursuant to qualified stock option plans,
         currently outstanding options, warrants or rights. The Company will
         cause each of its executive officers and directors to furnish to the
         Representative, prior to the Closing Date, a letter, substantially in
         the form of Exhibit B attached hereto, pursuant to which each such
         person shall agree not to directly or indirectly offer, sell, assign,
         transfer, pledge, contract to sell, or otherwise dispose of any shares
         of Common Stock or securities convertible into or exercisable or
         exchangeable for Common Stock for a period of 90 days from the date of
         the Prospectus Supplement, without the prior written consent of the
         Representative.

         (g) Prior to the Closing Date, to furnish to the Representative, as
         soon as they have been prepared, copies of any unaudited interim
         consolidated financial statements of the Company for any periods
         subsequent to the periods covered by the financial statements appearing
         or incorporated by reference in the Base Prospectus, the Prospectus
         Supplement or the Registration Statement.

         (h) Prior to the Closing Date, not to issue any press release or other
         communication directly or indirectly or hold any press conference with
         respect to the Company, its condition, financial or otherwise, or
         earnings, business affairs or business prospects (except for routine
         oral marketing communications in the ordinary course of business and
         consistent with the past practices of the Company and of which the
         Representative is notified), without the prior written consent of the
         Representative, unless in the judgment of the Company and its counsel,
         and after notification to the Representative, such press release or
         communication is required by law.

         (i) To apply the net proceeds from the sale of the Stock as set forth
         in the Prospectus Supplement under the heading "USE OF PROCEEDS."

         (j) To comply in all material respects with all applicable securities
         and other applicable laws, rules and regulations, including, without
         limitation, the Sarbanes-Oxley Act, and use its best efforts to cause
         the Company's directors and officers,



                                       17
<PAGE>

         in their capacities as such, to comply with such laws, rules and
         regulations, including, without limitation, the provisions of the
         Sarbanes-Oxley Act.

         (k) To engage and maintain, at its expense, a registrar and transfer
         agent for the Stock.

         (l) To not take any action prior to the Closing Date which would
         require the Prospectus Supplement to be amended or supplemented
         pursuant to Section 4(b).

         (m) To supply the Representative with copies of all correspondence to
         and from, and all documents issued to and by, the Commission in
         connection with the registration of the Stock under the Securities Act.

5. PAYMENT OF EXPENSES. The Company agrees with the Placement Agents to pay (a)
the costs incident to the authorization, issuance, sale, preparation and
delivery of the Stock to the Purchasers and any taxes payable in that
connection; (b) the costs incident to the Registration of the Stock under the
Securities Act; (c) the costs incident to the preparation, printing and
distribution of the Registration Statement, Base Prospectus and Prospectus
Supplement and any amendments and exhibits thereto or any document incorporated
by reference therein, and the costs of printing, reproducing and distributing,
this Agreement by mail, telex or other means of communication; (d) the fees and
expenses (including related fees and expenses of counsel for the Placement
Agents) incurred in connection with filings made with the NASD; (e) any
applicable listing or other fees; (f) the fees and expenses of qualifying the
Stock under the securities laws of the several jurisdictions as provided in
Section 4(f) and of preparing, printing and distributing Blue Sky Memoranda
(including related fees and expenses of counsel to the Placement Agents); (g)
all fees and expenses of the registrar and transfer agent of the Stock; and (h)
all other costs and expenses incident to the performance of the obligations of
the Company under this Agreement (including, without limitation, the fees and
expenses of the Company's counsel and the Company's independent accountants);
provided that, except as otherwise provided in this Section 5 and in Section 9,
the Placement Agents shall pay their own costs and expenses, including the fees
and expenses of their counsel.

6. CONDITIONS TO THE OBLIGATIONS OF THE PLACEMENT AGENTS AND THE PURCHASERS, AND
THE SALE OF THE STOCK. The respective obligations of the Placement Agents and
the Purchasers, and the closing of the sale of the Stock hereunder are subject
to the accuracy, when made and on the Closing Date, of the representations and
warranties on the part of the Company and its subsidiaries contained herein, to
the accuracy of the statements of the Company and its subsidiaries made in any
certificates pursuant to the provisions hereof, to the performance by the
Company and its subsidiaries of their obligations hereunder, and to each of the
following additional terms and conditions:

         (a) No stop order suspending the effectiveness of the Registration
         Statement shall have been issued and remain in effect and no
         proceedings for that purpose shall have been initiated or threatened by
         the Commission, and any request for



                                       18
<PAGE>

         additional information on the part of the Commission (to be included in
         the Registration Statement, the Base Prospectus or the Prospectus
         Supplement or otherwise) shall have been complied with to the
         reasonable satisfaction of the Representative. Any filings required to
         be made by the Company in accordance with Section 4(a) shall have been
         timely filed with the Commission.

         (b) None of the Placement Agents shall have discovered and disclosed to
         the Company on or prior to the Closing Date that the Registration
         Statement, the Base Prospectus or the Prospectus Supplement or any
         amendment or supplement thereto contains an untrue statement of a fact
         which, in the opinion of counsel for the Placement Agents, is material
         or omits to state any fact which, in the opinion of such counsel, is
         material and is required to be stated therein or is necessary to make
         the statements therein not misleading.

         (c) All corporate proceedings and other legal matters incident to the
         authorization, form and validity of each of this Agreement, the Stock,
         the Registration Statement, the Base Prospectus and the Prospectus
         Supplement and all other legal matters relating to this Agreement and
         the transactions contemplated hereby shall be reasonably satisfactory
         in all material respects to counsel for the Placement Agents, and the
         Company shall have furnished to such counsel all documents and
         information that they may reasonably request to enable them to pass
         upon such matters.

         (d) The Placement Agents shall have received from each of (i) Wilson
         Sonsini Goodrich & Rosati, Professional Corporation, corporate counsel
         for the Company and (ii) Fulbright & Jaworski LLP, patent counsel for
         the Company such counsel's written opinion, addressed to the Placement
         Agents and dated as of the Closing Date, in form and substance
         satisfactory to the Representative.

                  Such counsel shall also have furnished to the Placement Agents
         a written statement, addressed to the Placement Agents and dated the
         Closing Date, in form and substance satisfactory to the Representative,
         to the effect that (x) such counsel has acted as counsel to the Company
         in connection with the preparation of the Registration Statement, (y)
         based on such counsel's examination of the Registration Statement and
         such counsel's conferences with certain officers and employees of and
         with auditors for and counsel to the Company, although such counsel
         need not pass upon or assume responsibility for the accuracy,
         completeness or fairness of the statements included in the Registration
         Statement, the Base Prospectus or the Prospectus Supplement (and such
         counsel may rely as to materiality to a large extent upon discussions
         with and opinions of the officers and other representatives of the
         Company) nothing has come to the attention of such counsel to cause
         such counsel to believe that the Registration Statement, as of its
         effective date, contained any untrue statement of a material fact or
         omitted to state any material fact required to be stated therein or
         necessary in order to make the statements therein not misleading, or
         that the Base Prospectus or the Prospectus Supplement contains any
         untrue statement of a material fact or omits to state any material fact
         required to be stated therein or necessary in order to



                                       19
<PAGE>

         make the statements therein, in light of the circumstances under which
         they were made, not misleading; it being understood that such counsel
         need express no opinion as to the financial statements or other
         financial data contained in the Registration Statement, the Base
         Prospectus or the Prospectus Supplement.

         (e) The Placement Agents shall have received from Brown Raysman
         Millstein Felder & Steiner LLP, such opinion or opinions, dated the
         Closing Date and addressed to the Placement Agents, with respect to the
         issuance and sale of the Stock, the Registration Statement, the Base
         Prospectus, the Prospectus Supplement (together with any supplement
         thereto) and other related matters as the Representative may reasonably
         require, and the Company shall have furnished to such counsel such
         documents as they request for the purpose of enabling them to pass upon
         such matters.

         (f) The Company shall have furnished to the Placement Agents and the
         Purchasers a certificate, dated as of the Closing Date, executed by its
         Chairman of the Board, its Chief Executive Officer or a Vice President
         and its Chief Financial Officer stating that (i) such officers have
         carefully examined the Registration Statement, the Base Prospectus and
         the Prospectus Supplement and, in their opinion, the Registration
         Statement (including the Base Prospectus) as of its effective date and
         the Prospectus Supplement, as of each such effective date, did not
         include any untrue statement of a material fact and did not omit to
         state a material fact required to be stated therein or necessary to
         make the statements therein, in the case of the Registration Statement,
         in light of the circumstances under which they were made, not
         misleading, (ii) since the effective date of the Registration Statement
         no event has occurred which should have been set forth in a supplement
         or amendment to the Registration Statement, the Base Prospectus or the
         Prospectus Supplement, (iii) to the best of their knowledge after
         reasonable investigation, as of the Closing Date, the representations
         and warranties of the Company and its subsidiaries in this Agreement
         are true and correct and the Company and its subsidiaries have complied
         with all agreements and satisfied all conditions on its part to be
         performed or satisfied hereunder at or prior to the Closing Date, and
         (iv) subsequent to the date of the most recent financial statements
         included or incorporated by reference in the Base Prospectus and the
         Prospectus Supplement, there has been no change in the financial
         position or results of operation of the Company and its subsidiaries
         that would have a Material Adverse Effect, or any change, or any
         development including a prospective change, in or affecting the
         condition (financial or otherwise), results of operations, business or
         prospects of the Company and its subsidiaries taken as a whole, except
         as set forth in the Base Prospectus and the Prospectus Supplement.

         (g) At the time of the Execution Time, the Representative shall have
         received from Ernst & Young LLP a letter, addressed to the Placement
         Agents and dated such date, in form and substance reasonably
         satisfactory to the Representative (i) confirming that they are
         independent certified public accountants with respect to the Company
         within the meaning of the Securities Act and the Rules and Regulations
         and (ii) stating the conclusions and findings of such firm with respect


                                       20
<PAGE>

         to the financial statements and certain financial information contained
         or incorporated by reference in the Base Prospectus and the Prospectus
         Supplement.

         (h) On the Closing Date, the Representative shall have received a
         letter (the "BRING-DOWN LETTER") from Ernst & Young LLP addressed to
         the Placement Agents, and dated the Closing Date confirming, as of the
         date of the bring-down letter (or, with respect to matters involving
         changes or developments since the respective dates as of which
         specified financial information is given in the Base Prospectus and the
         Prospectus Supplement as of a date not more than three Business Days
         prior to the date of the bring-down letter), the conclusions and
         findings of such firm with respect to the financial information and
         other matters covered by its letter delivered to the Representative
         concurrently with the execution of this Agreement pursuant to Section
         6(g).

         (i) (i) Neither the Company nor any of its subsidiaries shall have
         sustained since the date of the latest audited financial statements
         included or incorporated by reference in the Base Prospectus and the
         Prospectus Supplement any material loss or interference with its
         business from fire, explosion, flood, terrorist act or other calamity,
         whether or not covered by insurance, or from any labor dispute or court
         or governmental action, order or decree, otherwise than as set forth in
         or contemplated by the Base Prospectus and the Prospectus Supplement,
         and (ii) since such date there shall not have been any change in the
         capital stock or long-term debt of the Company or any of its
         subsidiaries or any change, or any development involving a prospective
         change, in or affecting the business, general affairs, management,
         financial position, stockholders' equity, results of operations or
         prospects of the Company and its subsidiaries, otherwise than as set
         forth in or contemplated by the Base Prospectus and the Prospectus
         Supplement, the effect of which, in any such case described in clause
         (i) or (ii), is, in the judgment of the Representative, so material and
         adverse as to make it impracticable or inadvisable to proceed with the
         sale or delivery of the Stock on the terms and in the manner
         contemplated by the Base Prospectus and the Prospectus Supplement.

         (j) The Stock shall have been listed and admitted and authorized for
         trading on the Nasdaq National Market, and satisfactory evidence of
         such actions shall have been provided to the Representative.

         (k) At the Execution Time, the Company shall have furnished to the
         Representative a letter substantially in the form of Exhibit B hereto
         from each executive officer and director of the Company.

         (l) Subsequent to the execution and delivery of this Agreement, there
         shall not have occurred any of the following: (i) trading in securities
         generally on the New York Stock Exchange, the Nasdaq National Market or
         the American Stock Exchange or in the over-the-counter market, or
         trading in any securities of the Company on any exchange or in the
         over-the-counter market, shall have been suspended or minimum or
         maximum prices or maximum ranges for prices shall have been established
         on any such exchange or such market by the Commission,



                                       21
<PAGE>

         by such exchange or by any other regulatory body or governmental
         authority having jurisdiction, (ii) a banking moratorium shall have
         been declared by Federal or state authorities or a material disruption
         has occurred in commercial banking or securities settlement or
         clearance services in the United States, (iii) the United States shall
         have become engaged in hostilities, or the subject of an act of
         terrorism, there shall have been an escalation in hostilities involving
         the United States or there shall have been a declaration of a national
         emergency or war by the United States or (iv) there shall have occurred
         any other calamity or crisis or any change in general economic,
         political or financial conditions in the United States or elsewhere, if
         the effect of any such event in clause (iii) or (iv) makes it, in the
         sole judgment of the Representative, impracticable or inadvisable to
         proceed with the sale or delivery of the Stock on the terms and in the
         manner contemplated by the Base Prospectus and the Prospectus
         Supplement.

         (m) No action shall have been taken and no statute, rule, regulation or
         order shall have been enacted, adopted or issued by any governmental
         agency or body which would, as of the Closing Date, prevent the
         issuance or sale of the Stock; and no injunction, restraining order or
         order of any other nature by any federal or state court of competent
         jurisdiction shall have been issued as of the Closing Date which would
         prevent the issuance or sale of the Stock.

         (n) The Company shall have prepared and filed with the Commission
         within 48 hours of the Closing Date a Current Report on Form 8-K with
         respect to the Offering, including as an exhibit thereto this
         Agreement.

         (o) The Company shall have entered into a Subscription Agreement with
         each of the Purchasers and such agreements shall be in full force and
         effect.

         (p) Prior to the Closing Date, the Company shall have furnished to the
         Placement Agents such further information, certificates and documents
         as the Representative may reasonably request.

         All opinions, letters, evidence and certificates mentioned above or
elsewhere in this Agreement shall be deemed to be in compliance with the
provisions hereof only if they are in form and substance reasonably satisfactory
to counsel for the Placement Agents.

7.       INDEMNIFICATION AND CONTRIBUTION.

         (a) The Company shall indemnify and hold harmless each Placement Agent,
         its officers, employees, representatives and agents and each person, if
         any, who controls any Placement Agent (within the meaning of Section 15
         of the Securities Act or Section 20 of the Exchange Act) (collectively
         the "PLACEMENT AGENT INDEMNIFIED PARTIES" and each a "PLACEMENT AGENT
         INDEMNIFIED PARTY") against any loss, claim, damage or liability, joint
         or several, or any action in respect thereof, to which that Placement
         Agent Indemnified Party may become subject, under the Securities Act or
         otherwise, insofar as such loss, claim,



                                       22
<PAGE>
         damage, liability or action arises out of or is based upon (i) any
         untrue statement or alleged untrue statement of a material fact
         contained in the Base Prospectus, the Registration Statement or the
         Prospectus Supplement or in any amendment or supplement thereto, (ii)
         the omission or alleged omission to state therein a material fact
         required to be stated therein or necessary to make the statements
         therein not misleading or (iii) any breach of the representations and
         warranties of the Company contained herein, and shall reimburse each
         Placement Agent Indemnified Party promptly upon demand for any legal or
         other expenses reasonably incurred by that Placement Agent Indemnified
         Party in connection with investigating or preparing to defend or
         defending against or appearing as a third party witness in connection
         with any such loss, claim, damage, liability or action as such expenses
         are incurred; provided, however, that the Company shall not be liable
         in any such case to the extent that any such loss, claim, damage,
         liability or action arises out of or is based upon an untrue statement
         or alleged untrue statement in or omission or alleged omission from the
         Base Prospectus, the Registration Statement or the Prospectus
         Supplement or any such amendment or supplement in reliance upon and in
         conformity with written information furnished to the Company through
         the Representative specifically for use therein, which information the
         parties hereto agree is limited to the Placement Agents' Information
         (as defined in Section 15). This indemnity agreement is not exclusive
         and will be in addition to any liability, which the Company might
         otherwise have and shall not limit any rights or remedies which may
         otherwise be available at law or in equity to each Placement Agent
         Indemnified Party.

         (b) Each Placement Agent, severally and not jointly, shall indemnify
         and hold harmless the Company its officers, employees, representatives
         and agents, each of its directors and each person, if any, who controls
         the Company within the meaning of the Securities Act (collectively the
         "COMPANY INDEMNIFIED PARTIES" and each a "COMPANY INDEMNIFIED PARTY")
         against any loss, claim, damage or liability, joint or several, or any
         action in respect thereof, to which the Company Indemnified Parties may
         become subject, under the Securities Act or otherwise, insofar as such
         loss, claim, damage, liability or action arises out of or is based upon
         (i) any untrue statement or alleged untrue statement of a material fact
         contained in the Base Prospectus, the Registration Statement or the
         Prospectus Supplement or in any amendment or supplement thereto or (ii)
         the omission or alleged omission to state therein a material fact
         required to be stated therein or necessary to make the statements
         therein not misleading, but in each case only to the extent that the
         untrue statement or alleged untrue statement or omission or alleged
         omission was made in reliance upon and in conformity with written
         information furnished to the Company by or on behalf of that Placement
         Agent specifically for use therein, and shall reimburse each Company
         Indemnified Party promptly upon demand for any legal or other expenses
         reasonably incurred by such parties in connection with investigating or
         preparing to defend or defending against or appearing as third party
         witness in connection with any such loss, claim, damage, liability or
         action as such expenses are incurred; provided that the parties hereto
         hereby agree that such written information provided by the Placement
         Agents consists solely of the Placement Agents' Information. This



                                       23
<PAGE>

         indemnity agreement is not exclusive and will be in addition to any
         liability, which the Placement Agents and the Purchasers might
         otherwise have and shall not limit any rights or remedies which may
         otherwise be available at law or in equity to the Company Indemnified
         Parties. Notwithstanding the provisions of this Section 7(b), in no
         event shall any indemnity by any Placement Agent under this Section
         7(b) exceed the total compensation received by such Placement Agent in
         accordance with Section 1(e).

         (c) Promptly after receipt by an indemnified party under this Section 7
         of notice of any claim or the commencement of any action, the
         indemnified party shall, if a claim in respect thereof is to be made
         against the indemnifying party under this Section 7, notify the
         indemnifying party in writing of the claim or the commencement of that
         action; provided, however, that the failure to notify the indemnifying
         party shall not relieve it from any liability which it may have under
         this Section 7 except to the extent it has been materially prejudiced
         by such failure; and, provided, further, that the failure to notify the
         indemnifying party shall not relieve it from any liability which it may
         have to an indemnified party otherwise than under this Section 7. If
         any such claim or action shall be brought against an indemnified party,
         and it shall notify the indemnifying party thereof, the indemnifying
         party shall be entitled to participate therein and, to the extent that
         it wishes, jointly with any other similarly notified indemnifying
         party, to assume the defense thereof with counsel reasonably
         satisfactory to the indemnified party. After notice from the
         indemnifying party to the indemnified party of its election to assume
         the defense of such claim or action, the indemnifying party shall not
         be liable to the indemnified party under this Section 7 for any legal
         or other expenses subsequently incurred by the indemnified party in
         connection with the defense thereof other than reasonable costs of
         investigation; provided, however, that any indemnified party shall have
         the right to employ separate counsel in any such action and to
         participate in the defense thereof but the fees and expenses of such
         counsel shall be at the expense of such indemnified party unless (i)
         the employment thereof has been specifically authorized by the
         indemnifying party in writing, (ii) such indemnified party shall have
         been advised by such counsel that there may be one or more legal
         defenses available to it which are different from or additional to
         those available to the indemnifying party and in the reasonable
         judgment of such counsel it is advisable for such indemnified party to
         employ separate counsel or (iii) the indemnifying party has failed to
         assume the defense of such action and employ counsel reasonably
         satisfactory to the indemnified party, in which case, if such
         indemnified party notifies the indemnifying party in writing that it
         elects to employ separate counsel at the expense of the indemnifying
         party, the indemnifying party shall not have the right to assume the
         defense of such action on behalf of such indemnified party, it being
         understood, however, that the indemnifying party shall not, in
         connection with any one such action or separate but substantially
         similar or related actions in the same jurisdiction arising out of the
         same general allegations or circumstances, be liable for the reasonable
         fees and expenses of more than one separate firm of attorneys at any
         time for all such indemnified parties, which firm shall be designated
         in writing by the



                                       24
<PAGE>

         Representative, if the indemnified parties under this Section 7 consist
         of any Placement Agent Indemnified Party, or by the Company if the
         indemnified parties under this Section 7 consist of any Company
         Indemnified Parties. Each indemnified party, as a condition of the
         indemnity agreements contained in Sections 7(a) and 7(b) shall use all
         reasonable efforts to cooperate with the indemnifying party in the
         defense of any such action or claim. Subject to the provisions of
         Section 7(d) below, no indemnifying party shall be liable for any
         settlement, compromise or consent to the entry of judgment in
         connection with any such action effected without its written consent
         (which consent shall not be unreasonably withheld), but if settled with
         its written consent or if there be a final judgment for the plaintiff
         in any such action (other than a judgment entered with the consent of
         such indemnified party), the indemnifying party agrees to indemnify and
         hold harmless any indemnified party from and against any loss or
         liability by reason of such settlement or judgment.

         (d) If at any time an indemnified party shall be entitled to employ
         separate counsel at the expense of an indemnifying party in accordance
         with Section 7(c) and shall have requested that an indemnifying party
         reimburse the indemnified party for fees and expenses of counsel, such
         indemnifying party agrees that it shall be liable for any settlement of
         the nature contemplated by this Section 7 effected without its written
         consent if (i) such settlement is entered into more than 45 days after
         receipt by such indemnifying party of the request for reimbursement,
         (ii) such indemnifying party shall have received notice of the terms of
         such settlement at least 30 days prior to such settlement being entered
         into and (iii) such indemnifying party shall not have reimbursed such
         indemnified party in accordance with such request prior to the date of
         such settlement.

         (e) If the indemnification provided for in this Section 7 is
         unavailable or insufficient to hold harmless an indemnified party under
         Section 7(a) or 7(b), then each indemnifying party shall, in lieu of
         indemnifying such indemnified party, contribute to the amount paid or
         payable by such indemnified party as a result of such loss, claim,
         damage or liability, or action in respect thereof, (i) in such
         proportion as shall be appropriate to reflect the relative benefits
         received by the Company on the one hand and the Placement Agents on the
         other from the offering of the Stock or (ii) if the allocation provided
         by clause (i) above is not permitted by applicable law, in such
         proportion as is appropriate to reflect not only the relative benefits
         referred to in clause (i) above but also the relative fault of the
         Company on the one hand and the Placement Agents on the other with
         respect to the statements or omissions which resulted in such loss,
         claim, damage or liability, or action in respect thereof, as well as
         any other relevant equitable considerations. The relative benefits
         received by the Company on the one hand and the Placement Agents on the
         other with respect to such offering shall be deemed to be in the same
         proportion as the total net proceeds from the offering of the Stock
         purchased under this Agreement (before deducting expenses) received by
         the Company bears to the total compensation received by the Placement
         Agents with respect to the Stock purchased under this Agreement. The
         relative fault shall be determined by reference to, among other things,
         whether the untrue



                                       25
<PAGE>

         or alleged untrue statement of a material fact or the omission or
         alleged omission to state a material fact relates to information
         supplied by the Company on the one hand or the Placement Agents on the
         other, the intent of the parties and their relative knowledge, access
         to information and opportunity to correct or prevent such untrue
         statement or omission; provided that the parties hereto agree that the
         written information furnished to the Company by the Representative for
         use in the Prospectus Supplement consists solely of the Placement
         Agents' Information. The Company and the Placement Agents agree that it
         would not be just and equitable if contributions pursuant to this
         Section 7(e) were to be determined by pro rata allocation or by any
         other method of allocation which does not take into account the
         equitable considerations referred to herein. The amount paid or payable
         by an indemnified party as a result of the loss, claim, damage or
         liability, or action in respect thereof, referred to above in this
         Section 7(e) shall be deemed to include, for purposes of this Section
         7(e), any legal or other expenses reasonably incurred by such
         indemnified party in connection with investigating or defending any
         such action or claim. Notwithstanding the provisions of this Section
         7(e), the Placement Agents shall not be required to contribute any
         amount in excess of the amount by which the total price at which the
         Stock was offered and sold to the Purchasers less the amount of any
         damages which such Placement Agents have otherwise paid or become
         liable to pay by reason of any untrue or alleged untrue statement or
         omission or alleged omission. No person guilty of fraudulent
         misrepresentation (within the meaning of Section 11(f) of the
         Securities Act) shall be entitled to contribution from any person who
         was not guilty of such fraudulent misrepresentation.

8. TERMINATION. The obligations of the Placement Agents and the Purchasers
hereunder and under the Subscription Agreements may be terminated by the
Representative, in its absolute discretion by prior written notice given to the
Company prior to delivery (including electronic delivery) of and payment for the
Stock if, prior to that time, any of the events described in Sections 6(i) or
6(l) have occurred or if the Purchasers, or the Representative on behalf of the
Purchasers, shall decline to purchase the Stock for any reason permitted under
this Agreement.

         If the sale of the Stock, as contemplated by this Agreement, is not
carried out by the Placement Agents for any reason permitted under this
Agreement or if such sale is not carried out because the Company shall be unable
to comply with any of the terms of this Agreement, no party hereunder shall be
under any obligation or liability under this Agreement to any other party
(except to the extent provided in Sections 5, 7 and 9 herein).

9. REIMBURSEMENT OF THE REPRESENTATIVE'S EXPENSES. If the sale of the Stock
provided for herein is not consummated because any condition to the obligations
of the Placement Agents and the Purchasers set forth in Section 6 hereof is not
satisfied, because of any termination pursuant to Section 8 hereof or because of
any refusal, inability or failure on the part of the Company to perform any
agreement herein or comply with any provision hereof other than by reason of a
default by the Representative, the Company will reimburse the Representative
upon demand for all out-of-pocket



                                       26
<PAGE>

expenses (including reasonable fees and disbursements of counsel) that shall
have been incurred by the Representative in connection with this Agreement and
the proposed purchase and sale of the Stock and, upon demand, the Company shall
pay the amount thereof to the Representative, up to the aggregate amount of
$100,000.

10. SUCCESSORS; PERSONS ENTITLED TO BENEFIT OF AGREEMENT. This Agreement shall
inure to the benefit of and be binding upon the Placement Agents, the
Purchasers, the Company, and their respective successors. Nothing expressed or
mentioned in this Agreement is intended or shall be construed to give any person
other than the persons mentioned in the preceding sentence any legal or
equitable right, remedy or claim under or in respect of this Agreement, or any
provisions herein contained, this Agreement and all conditions and provisions
hereof being intended to be and being for the sole and exclusive benefit of such
persons and for the benefit of no other person; except that the representations,
warranties, covenants, agreements and indemnities of the Company contained in
this Agreement shall also be for the benefit of the Placement Agent Indemnified
Parties, and the indemnities of the Placement Agents shall also be for the
benefit of the Company Indemnified Parties. It is understood that the Placement
Agents' responsibilities to the Company are solely contractual in nature and the
Placement Agents do not owe the Company, or any other party, any fiduciary duty
as a result of this Agreement.

11. SURVIVAL OF INDEMNITIES, REPRESENTATIONS, WARRANTIES, ETC. The respective
indemnities, covenants, agreements, representations, warranties and other
statements of the Company and the Placement Agents, as set forth in this
Agreement or made by them respectively, pursuant to this Agreement, shall remain
in full force and effect, regardless of any investigation made by or on behalf
of the Placement Agents, the Company, or any person controlling any of them and
shall survive delivery of and payment for the Stock.

12. NOTICES. All statements, requests, notices and agreements hereunder shall be
in writing, and:

         (a) if to the Placement Agents, shall be delivered or sent by mail,
         telex or facsimile transmission to SG Cowen Securities Corporation,
         1221 Avenue of the Americas, New York, New York 10020, Attention:
         Michelle Bowe (Fax: 212-278-7438), with a copy to: Brown Raysman
         Millstein Felder & Steiner LLP, 900 Third Avenue, New York, New York
         10022, Attention: Stuart Bressman, Esq. (Fax: 212-895-2900).

         (b) if to the Company shall be delivered or sent by mail, telex or
         facsimile transmission to Introgen Therapeutics, Inc., 301 Congress
         Avenue, Suite 1850, Austin, Texas 78701, Attention: James W. Albrecht,
         Jr. (Fax: 512-708-9311), with a copy to: Wilson Sonsini Goodrich &
         Rosati, 8911 Capital of Texas Highway North, Westech 360, Suite 3350,
         Austin, Texas 78759-8497, Attention: Christopher Ozburn, Esq. (Fax:
         512-338-5499), and with a copy to: Wilson & Varner, LLP, 301 Congress
         Avenue, Suite 2025, Austin, Texas 78701, Attention: Rodney Varner (Fax:
         512-495-9441).



                                       27
<PAGE>

13. DEFINITIONS OF CERTAIN TERMS. The terms which follow, when used in this
Agreement, shall have the meanings indicated.

                  "BUSINESS DAY" shall mean any day other than a Saturday, a
         Sunday, a legal holiday, a day on which banking institutions or trust
         companies are authorized or obligated by law to close in New York City
         or any day on which the Nasdaq National Market is not open for trading.

                  "EFFECTIVE DATE" shall mean each date and time that the
         Registration Statement (and any post-effective amendment or amendments
         thereto) became or becomes effective.

                  "EXECUTION TIME" shall mean the date and time that this
         Agreement is executed and delivered by the parties hereto.

                  "INTERFERENCE PROCEEDING" shall have the meaning set forth in
         35 U.S.C. Section 135.

                  "TO THE COMPANY'S KNOWLEDGE" shall mean that which the Company
         knows or should have known using the exercise of reasonable due
         diligence.

14. GOVERNING LAW. This Agreement shall be governed by and construed in
accordance with the laws of the State of New York.

15. PLACEMENT AGENTS' INFORMATION. The parties hereto acknowledge and agree
that, for all purposes of this Agreement, the Placement Agents' Information
consists solely of the statements concerning the Placement Agents contained in
the first and third paragraphs under the heading "Plan of Distribution" and the
second sentence under the heading "Legal Matters" in the Prospectus Supplement.

16. PARTIAL UNENFORCEABILITY. The invalidity or unenforceability of any Section,
paragraph or provision of this Agreement shall not affect the validity or
enforceability of any other Section, paragraph or provision hereof. If any
Section, paragraph or provision of this Agreement is for any reason determined
to be invalid or unenforceable, there shall be deemed to be made such minor
changes (and only such minor changes) as are necessary to make it valid and
enforceable.

17. GENERAL. This Agreement constitutes the entire agreement of the parties to
this Agreement and supersedes all prior written or oral and all contemporaneous
oral agreements, understandings and negotiations with respect to the subject
matter hereof. In this Agreement, the masculine, feminine and neuter genders and
the singular and the plural include one another. The section headings in this
Agreement are for the convenience of the parties only and will not affect the
construction or interpretation of this Agreement. This Agreement may be amended
or modified, and the observance of any term of this Agreement may be waived,
only by a writing signed by the Company and the Representative.



                                       28
<PAGE>

18. COUNTERPARTS. This Agreement may be signed in any number of counterparts,
each of which shall be an original, with the same effect as if the signatures
thereto and hereto were upon the same instrument.

19. CONSENT TO ACT AS REPRESENTATIVE. First Albany Capital Inc. ("FIRST ALBANY")
consents and agrees that SG Cowen Securities Corporation ("SG COWEN") will act
as Representative of the Placement Agents under this Agreement and with respect
to the sale of the Stock. Accordingly, First Albany authorizes SG Cowen to
manage the Offering and sale of the Stock and to take such action in connection
therewith as SG Cowen in its sole discretion deems appropriate or desirable,
consistent with the provisions of the Agreement Among Underwriters previously
entered into between SG Cowen and First Albany, taking into account that the
Offering of the Stock will be in the form of a best efforts placement and not a
firm commitment underwriting.




                                       29
<PAGE>



         If the foregoing is in accordance with your understanding of the
agreement between the Company and the Placement Agents, kindly indicate your
acceptance in the space provided for that purpose below.

                                        Very truly yours,


                                        INTROGEN THERAPEUTICS, INC.


                                        By: /s/ David G. Nance
                                            ---------------------------------
                                            Name:  David G. Nance
                                            Title: President and CEO



Accepted as of
the date first above written:

SG COWEN SECURITIES CORPORATION


By: /s/ Richard Gormley
    ------------------------
    Name:  Richard Gormley
    Title: Managing Director



FIRST ALBANY CAPITAL INC.


By: /s/ David Bohn
    ------------------------
    Name:  David Bohn
    Title: Co-Head, Private Capital Group



                                       30
<PAGE>
                                   SCHEDULE I

                                PLACEMENT AGENTS


SG Cowen Securities Corporation
First Albany Capital Inc.


                                       31
<PAGE>



                                    EXHIBIT A

                         FORM OF SUBSCRIPTION AGREEMENT


                                       32
<PAGE>
                                    EXHIBIT B

                            FORM OF LOCK-UP AGREEMENT






                                       33