
<PAGE>   1
                                                                REDACTED VERSION

                                 EXHIBIT 10.29

                                       TO

                         TARGETED GENETICS CORPORATION

                                AMENDMENT NO. 1

                                       TO

                                    FORM S-1

                            TO BE FILED ON OR BEFORE

                                  MAY 30, 1996


"[*]" = confidential information omitted and filed separately with the 
Securities and Exchange Commission pursuant to a request for confidential 
treatment.
<PAGE>   2
                     PATENT AND TECHNOLOGY LICENSE AGREEMENT

                  THIS AGREEMENT ("AGREEMENT") is made by and between the BOARD
OF REGENTS ("BOARD") of THE UNIVERSITY OF TEXAS SYSTEM ("SYSTEM"), an agency of
the State of Texas, whose address is 201 West 7th Street, Austin, Texas 78701,
THE UNIVERSITY OF TEXAS M.D. ANDERSON CANCER CENTER ("MDA"), a component
institution of the SYSTEM, and RGENE THERAPEUTlCS, INC., a corporation having a
principal place of business located at The Woodlands, Texas ("LICENSEE").

                                    RECITALS

                  A. BOARD owns certain PATENT RIGHTS and TECHNOLOGY RIGHTS
related to LICENSED SUBJECT MATTER, which were developed at MDA, a component
institution of SYSTEM.

                  B. BOARD desires to have the LICENSED SUBJECT MATTER developed
and used for the benefit of LICENSEE, the inventor, BOARD, and the public as
outlined in the Intellectual Property Policy promulgated by the BOARD.

                  C. The LICENSED SUBJECT MATTER is the subject of SPONSORED
RESEARCH AGREEMENTS between MDA and LICENSEE, copies of which are attached
hereto as Exhibits 1A and 1B for approval by BOARD, although certain LICENSED
SUBJECT MATTER was developed with funding from, and is subject to the rights of,
the Federal Government.

                  D. LICENSEE is a company which was formed to develop and
commercially exploit the inventions of LICENSED SUBJECT MATTER, and LICENSEE,
therefore, wishes to obtain a license from BOARD to practice LICENSED SUBJECT
MATTER.

                  E. A copy of an executed Stock Purchase Agreement between
LICENSEE and Gabriel Lopez-Berestein, M.D., an employee of MDA, which provides
for, among other things, the circumstances and methods under which Gabriel
Lopez-Berestein, M.D. shall be able to divest himself of stock in LICENSEE
acquired under said Stock Purchase Agreement, is attached hereto as Exhibit 2
for approval by BOARD.

                  F. A copy of an executed Stock Purchase Agreement between
LICENSEE and Mien-Chie Hung, Ph.D., an employee of MDA, which provides for,
among other things, the circumstances and methods under which Mien-Chie Hung,
Ph.D. shall be able to divest himself of stock in LICENSEE acquired under said
Stock Purchase Agreement, is attached hereto as Exhibit 3 for approval by BOARD.
<PAGE>   3
                  G. A copy of an executed Stockholder Agreement between
LICENSEE and BOARD is attached hereto as Exhibit 4 for approval by BOARD.

                  NOW, THEREFORE, in consideration of the mutual covenants and
premises herein contained, the parties hereto agree as follows:

1.                EFFECTIVE DATE

                  1.1 This AGREEMENT shall be effective as of March 1, 1994
subject to approval by BOARD ("EFFECTIVE DATE").

2.                DEFINITIONS

                  As used in this AGREEMENT, the following terms shall have the
meanings indicated:

                  2.1 IMPROVEMENTS shall mean any inventions and discoveries
which are within the scope of either pending patent applications or issued
patents included within PATENT RIGHTS and which are developed in the
laboratories of either Mien Chie Hung, Ph.D. or Gabriel Lopez-Berestein, M.D. at
MDA.

                  2.2 LICENSED FIELD shall mean all compositions and fields of
use of the LICENSED SUBJECT MATTER.

                  2.3 LICENSED PRODUCT shall mean any product SOLD by LICENSEE
or its sublicensees comprising LICENSED SUBJECT MATTER pursuant to this
AGREEMENT.

                  2.4 LICENSED SUBJECT MATTER shall mean inventions and
discoveries covered by PATENT RIGHTS, TECHNOLOGY RIGHTS, LICENSEE SPONSORED
TECHNOLOGY and/or IMPROVEMENTS.

                  2.5 LICENSED TERRITORY shall mean the entire world.

                  2.6 LICENSEE SPONSORED TECHNOLOGY shall have the meaning given
to it under either of the SPONSORED RESEARCH AGREEMENTS, or any extension
thereof.

                  2.7 NET SALES shall mean the gross revenues received by
LICENSEE from the SALE of LICENSED PRODUCTS less sales and/or use taxes actually
paid, import and/or export duties actually paid, outbound transportation prepaid
or allowed, and amounts allowed or credited due to returns (not to exceed the
original billing or invoice amount).

                                      -2-
<PAGE>   4
                  2.8 PATENT RIGHTS shall mean BOARD's rights in information or
discoveries covered by patents and/or patent applications, whether domestic or
foreign, and all divisionals, continuations, continuations-in-part, reissues,
reexaminations or extensions thereof, and any letters patent that issue thereon,
for the inventions listed on Attachment A hereto and incorporated herein and for
any inventions comprising LICENSEE SPONSORED TECHNOLOGY and/or IMPROVEMENTS,
from time to time.

                  2.9 SALE or SOLD shall mean the transfer or disposition of a
LICENSED PRODUCT for value to a party other than LICENSEE or an AFFILIATE.

                  2.10 SPONSORED RESEARCH AGREEMENT shall mean each of the
SPONSORED RESEARCH AGREEMENTS of even date herewith between LICENSEE and MDA,
copies of which are attached as Exhibit 1A and Exhibit 1B hereto.

                  2.11 AFFILIATE shall mean any business entity more than 50%
owned by LICENSEE, any business entity which owns more than 50% of LICENSEE, or
any business entity that is more than 50% owned by a business entity that owns
more than 50% of LICENSEE.

                  2.12 TECHNOLOGY RIGHTS shall mean BOARD's rights in any
technical information, know-how, process, procedure, composition, device,
method, formula, protocol, technique, software, design, drawing or data relating
to LICENSED SUBJECT MATTER, which is not covered by PATENT RIGHTS but which is
necessary for practicing the invention at any time claimed in PATENT RIGHTS.

3.                WARRANTY:  SUPERIOR-RIGHTS

                  3.1 Except for the rights, if any, of the Government of the
United States as set forth hereinbelow, BOARD represents and warrants that it is
the owner of the entire right, title, and interest in and to LICENSED SUBJECT
MATTER, and that it has the sole right to grant licenses thereunder, and that it
has not granted licenses thereunder to any other entity that would restrict
rights granted hereunder except as stated herein.

                  3.2 LICENSEE understands that the LICENSED SUBJECT MATTER may
have been developed under a funding agreement with the Government of the United
States of America and, if so, that the Government may have certain rights
relative thereto. This AGREEMENT is explicitly made subject to the Government's
rights under any such agreement and any applicable law or regulation, including
P.L. 96-517 as amended by P.L. 98-620. To the extent that there is a conflict
between any such agreement, applicable law or regulation and this AGREEMENT, the
terms of such Government agreement, applicable law or regulation shall prevail.

                                      -3-
<PAGE>   5
                  3.3 LICENSEE understands that BOARD can make no
representations or guarantees as to the patentability or breadth of the
inventions contained in the PATENT RIGHTS. LICENSEE also understands that BOARD
can make no representations or guarantees as to whether or not there are any
patents now held, or which will be held, by others or by BOARD in the LICENSED
FIELD or whether or not the inventions contained in PATENT RIGHTS may infringe
any other patents now held or that will be held by others or by BOARD.

4.                LICENSE

                  4.1 BOARD hereby grants to LICENSEE a royalty-bearing,
exclusive license under LICENSED SUBJECT MATTER to manufacture, have
manufactured, use and/or sell LICENSED PRODUCT within LICENSED TERRITORY for use
within LICENSED FIELD and shall extend to BOARD's undivided interest in any
LICENSED SUBJECT MATTER developed during the term of this AGREEMENT and jointly
owned by BOARD and LICENSEE. This grant shall also extend to LICENSEE SPONSORED
TECHNOLOGY and IMPROVEMENTS. The grant shall be subject to Paragraph 3.2,
hereinabove, the payment by LICENSEE to BOARD of all consideration as provided
in this AGREEMENT (including the timely payment of all amounts due under the
SPONSORED RESEARCH AGREEMENT as well as reimbursement of MDA's patent expenses),
and shall be further subject to rights retained by BOARD and MDA to:

                       (a) Publish the general scientific findings from research
related to LICENSED SUBJECT MATTER, provided that LICENSEE shall be provided
written notice of any such proposed publication at least sixty (60) days in
advance thereof in order to determine whether BOARD should file a patent
application with respect to such scientific findings, and no such publication
shall occur until BOARD has adequately protected the patentability of such
findings.

                       (b) Use any information contained in LICENSED SUBJECT
MATTER for research, teaching, unreimbursed experimental patient care, and other
educationally related purposes.

                  4.2 LICENSEE shall have the right to extend the license 
granted herein to any AFFILIATE provided that such AFFILIATE consents to be 
bound by this AGREEMENT to the same extent as LICENSEE.

                  4.3 LICENSEE shall have the right to grant sublicenses
consistent with this AGREEMENT provided that LICENSEE shall be responsible for
the operations of its sublicensees relevant to this AGREEMENT as if such
operations were carried out by LICENSEE. LICENSEE further agrees to deliver to
BOARD a true and correct copy of each sublicense granted by LICENSEE, and any
modification or termination thereof, within thirty (30) days after execution,
modification, or termination. Upon termination of


                                      -4-
<PAGE>   6
this AGREEMENT, any and all existing sublicenses granted by LICENSEE may, at 
BOARD's sole discretion, be assigned to BOARD.

                  4.4 BOARD shall have the right at any time after (i) three (3)
years from the date of this Agreement or (ii) termination of both of the
SPONSORED RESEARCH AGREEMENTS, whichever is later, to terminate the exclusivity
of the license granted herein in any national political jurisdiction in which
patent protection for the LICENSED SUBJECT MATTER is either being sought or is
in effect within LICENSED TERRITORY if LICENSEE, within ninety (90) days after
written notice from BOARD as to such intended termination, fails to provide
written evidence that it has commercialized or is actively attempting to
commercialize an invention hereunder. Evidence provided by LICENSEE that it has
an ongoing and active research, development, manufacturing, marketing or
licensing program as appropriate, directed toward production and sale of
products based on the invention disclosed and claimed in PATENTS or
incorporating TECHNOLOGY within such jurisdiction shall be deemed satisfactory
evidence. BOARD agrees to negotiate in good faith with LICENSEE for adjusting
terms under such a nonexclusive arrangement.

                  4.5 The parties hereto agree to annually update the schedule
of patents and patent applications listed on Attachment A.

5.                PAYMENTS AND REPORTS

                  5.1 In consideration of rights granted by BOARD to LICENSEE
under this AGREEMENT, LICENSEE agrees to pay MDA the following:

                       (a) A running royalty equal to [*] of NET SALES for
LICENSED PRODUCTS SOLD by LICENSEE;

                       (b) [*] of all royalties received by LICENSEE for SALES
by a sublicensee, but in no event more than [*] of NET SALES for LICENSED
PRODUCT SOLD by such sublicensee, received by LICENSEE from a sublicensee from
SALES of LICENSED PRODUCT by such sublicensee;

                       (c) [*] royalty on all cash considerations received by
LICENSEE from a sublicensee as a result of a sublicense for Licensed Products in
the form of licensing fees, marketing fees, milestone payments, bonus payments
and the like, but excluding payments for equity and sponsored research; and

                       (d) [*] royalty on all cash consideration received by
LICENSEE from a sublicensee as a result of a sublicense for Licensed Products
for sponsored research if, 

- ---------------------
[*] Confidential Treatment Requested.

                                      -5-
<PAGE>   7
and only if, the SPONSORED RESEARCH AGREEMENT for such Licensed Products is not
in existence at the time any such payment is received.

                  5.2 During the Term of this AGREEMENT and for one (1) year
thereafter, LICENSEE shall keep complete and accurate records of its and its
sublicensees' SALES and NET SALES of LICENSED PRODUCTS to enable the royalties
and other amounts payable hereunder to be determined. LICENSEE shall permit
BOARD or its representatives, at BOARD's expense, to periodically examine its
books, ledgers, and records during regular business hours for the purpose of and
to the extent necessary to verify any report required under this AGREEMENT. In
the event that the amounts due to BOARD are determined to have been underpaid by
ten percent (10%) or more, LICENSEE shall pay the cost of such examination, and
accrued interest at twelve percent (12%), or at the highest rate allowed by law,
if lower, on which the amount which was deficient.

                  5.3 Within thirty (30) days after March 31, June 30, September
30, and December 31, LICENSEE shall deliver to BOARD and MDA a true and accurate
report, giving such particulars of the business conducted by LICENSEE and its
sublicensee, if any exist, during the preceding three (3) calendar months under
this AGREEMENT as are pertinent to an account for payments hereunder. Such
report shall include at least (a) the quantities of LICENSED SUBJECT MATTER that
it has produced; (b) the total SALES, (c) the calculation of royalties thereon;
and (d) the total royalties so computed and due BOARD. Simultaneously with the
delivery of each such report, LICENSEE shall pay to BOARD the amount, if any,
due for the period of such report. If no payments are due, it shall be so
reported.

                  5.4 Upon the request of BOARD or MDA but not more often than
once per calendar year, LICENSEE shall deliver to BOARD and MDA a written report
as to LICENSEE's efforts and accomplishments during the preceding year in
commercializing LICENSED SUBJECT MATTER in the LICENSED TERRITORY and its
commercialization plans for the upcoming year.

                  5.5 All amounts payable hereunder by LICENSEE shall be
payable in United States funds without deductions for taxes, assessments, fees,
or charges of any kind. Checks shall be made payable to The University of Texas
M.D. Anderson Cancer Center.

                  5.6 LICENSEE shall reimburse BOARD for all its out-of-pocket
expenses thus far incurred in filing, prosecuting, enforcing and maintaining
PATENT RIGHTS exclusively licensed hereunder, and shall pay all such future
expenses so long as and in such countries as its license remains exclusive.
LICENSEE shall reimburse all of BOARD's expenses thus far incurred upon
execution of this AGREEMENT. To the extent such expenses are greater than
$10,000, the excess over $10,000 shall be reimbursed within ninety (90) days
after the EFFECTIVE DATE. Thereafter, MDA will 


                                      -6-
<PAGE>   8
invoice LICENSEE on a quarterly basis beginning July 1, 1994, with such invoices
 being due and payable within thirty (30) days thereafter.

                  5.7 No payments due or royalty rates under this AGREEMENT
shall be reduced as the result of co-ownership of LICENSED SUBJECT MATTER by
BOARD and LICENSEE.

                  5.8 Notwithstanding the above, MDA shall have the right,
exercisable until such time as LICENSEE has completed a public offering of its
equity securities under the Securities Act of 1933, as amended, pursuant to an
effective registration statement filed with the Securities and Exchange
Commission, to acquire shares of Common Stock of the LICENSEE in lieu of the
payments due MDA under Section 5.1(c) above, in an amount determined by dividing
the amount of payments otherwise due MDA under Section 5.1(c) by the sale price
of the LICENSEE's equity securities stock determined by the Board of Directors
of the LICENSEE in the most recent financing completed by LICENSEE prior to the
date any such payments under Section 5.1(c) accrued.

                  In the event that any payment under Section 5.1(c) shall be
due and so long as MDA's right under this Section 5.8 shall exist, LICENSEE
shall provide written notice to MDA of the amount of the payment due to MDA
under Section 5.1(c) and the price of its most recent sale of preferred stock,
together with the number of shares of Common Stock available to MDA hereunder.
MDA shall have a period of thirty (30) days from the date of such notice to
exercise its right hereunder, and shall provide written notice to LICENSEE prior
to the expiration of such time period of its desire to exercise its rights
hereunder. If MDA fails to provide such notice in such time period, or fails to
exercise its rights hereunder, MDA shall receive such amounts owed under Section
5.1(c) in U.S. dollars, provided that such financing occurred within 12 months
of the date such payments accrued. In the event that such financing occurred
more than 12 months before the date such payments accrued, then in such event
the fair market value of the LICENSEE's equity securities, as determined in the
good faith opinion of the Board of Directors of the LICENSEE, shall be used
instead of such sale price, provided, however, that if LICENSOR disagrees with
such determination, LICENSOR shall be able to appoint an independent third party
knowledgeable and experienced in such matters, reasonably acceptable to
LICENSEE, to make its own determination of such fair market value, at the sole
expense of LICENSOR, which determination shall govern and control for the
purposes hereof.

                  5.9 LICENSEE agrees that it will not, during the term of this
AGREEMENT, enter into a license agreement with another institution which license
agreement licenses to the LICENSEE on an exclusive basis technology and/or
patent rights on terms which are more favorable to such institution on an
aggregate basis than the terms contained in this Agreement, taking into account
all of the financial terms contained in any such license agreement, including
but not limited to terms relating to the payment of royalties, 



                                      -7-
<PAGE>   9
sublicensee royalties, equity issued by LICENSEE to MDA or any such other 
institution as consideration for the license, milestone payments, annual license
fees, minimum royalties and all other similar terms.

6.                PATENTS AND INVENTIONS

                  6.1 LICENSEE shall reimburse BOARD for all reasonable future
third party expenses incurred by BOARD in searching, filing, prosecuting and
maintaining patent applications and patents relating to Patent Rights. If after
consultation with LICENSEE it is agreed by BOARD and LICENSEE that a new patent
application should be filed for LICENSED SUBJECT MATTER, BOARD will prepare and
file appropriate patent applications, and LICENSEE will pay the reasonable third
party cost of searching, preparing, filing, prosecuting and maintaining same. If
LICENSEE notifies BOARD that it does not intend to pay the third party cost of
an application, or if LICENSEE does not respond or make an effort to agree with
BOARD on the disposition of rights of the subject invention, then BOARD may file
such application at its own expense and LICENSEE shall have no rights to such
invention other than TECHNOLOGY RIGHTS. BOARD shall provide LICENSEE with a copy
of the application for which LICENSEE has paid the cost of filing, as well as
copies of any documents received or filed during prosecution thereof.

                  6.2 The parties acknowledge that research in laboratories at
MDA which are under the direct supervision of Mien Chie Hung, Ph.D. or Gabriel
Lopez-Berestein, M.D. may result in discoveries and inventions which are in the
field of the molecular biology of oncogenes and/or growth factors and lipid
based gene, nucleic acid and/or oligonucleotide delivery technologies, are
related to the LICENSED SUBJECT MATTER but not included therein, and did not
result from the Sponsored Research Agreements attached hereto as Exhibit 1A and
1B (RELATED TECHNOLOGY). MDA hereby grants to the LICENSEE the right of first
review with respect to the RELATED TECHNOLOGY (excluding, however, any RELATED
TECHNOLOGY as to which any other commercial organization has rights therein)
under the following terms:

                       (a) MDA shall notify the LICENSEE in writing of the
RELATED TECHNOLOGY and provide the LICENSEE with sufficient detail to evaluate
the RELATED TECHNOLOGY.

                       (b) The LICENSEE shall have ninety (90) days after such
notification to evaluate the RELATED TECHNOLOGY and notify MDA in writing that
the LICENSEE desires to license the RELATED TECHNOLOGY.

                       (c) Upon notification by the LICENSEE of its desire to
acquire rights in the RELATED TECHNOLOGY, the LICENSEE and MDA shall negotiate
in good faith for a period not to exceed ninety (90) days, unless extended by
mutual written agreement of MDA and the LICENSEE, in an effort to arrive at
terms and conditions satisfactory to 


                                      -8-
<PAGE>   10
MDA and LICENSEE for the license by the LICENSEE of the RELATED TECHNOLOGY.

                  (d) If MDA and the LICENSEE do not reach such agreement within
said ninety (90) day period, MDA shall be free to deal with such RELATED
TECHNOLOGY as it in its discretion may decide, and shall have no further
obligations to the LICENSEE with respect to such RELATED TECHNOLOGY; provided
that any subsequent license to a third party by MDA of such RELATED TECHNOLOGY
shall be on terms no less favorable to MDA than were last offered by MDA to the
LICENSEE in writing.

7.       INFRINGEMENT BY THIRD PARTIES

         7.1 LICENSEE shall have the obligation of enforcing at its expense any
patent exclusively licensed hereunder against infringement by third parties and
shall be entitled to retain recovery from such enforcement. LICENSEE shall pay
MDA a royalty equal to the amount set out in Section 5.1(a) on any monetary
recovery to the extent that such monetary recovery by LICENSEE is in excess of
the cost thereof and to the extent held to be damages or a reasonable royalty in
lieu thereof. In the event that LICENSEE does not file suit against a
substantial infringer of such patents within six (6) months of knowledge
thereof, then BOARD shall have the right to enforce any patent licensed
hereunder on behalf of itself and LICENSEE (MDA retaining all recoveries from
such enforcement).

         7.2 In any suit or dispute involving an infringer, the parties shall
cooperate fully, and upon the request and at the expense of the party bringing
suit, the other party shall make available to the party bringing suit at
reasonable times and under appropriate conditions all relevant personnel,
records, papers, information, samples, specimens, and the like which are in its
possession.

         7.3 In the event of any infringement or likely infringement by any of
the LICENSED SUBJECT MATTER or LICENSEE SPONSORED TECHNOLOGY of any third
party's intellectual property (collectively, INFRINGING RIGHTS), BOARD, SYSTEM
and MDA shall, together with LICENSEE, cooperate in good faith and on a mutual
and reasonable basis, with each party responsible for its respective expenses:

                  (a) To negotiate and settle any dispute with any such third
party concerning the INFRINGING RIGHTS, and otherwise resolve any such
infringement and secure LICENSEE's continued rights to the INFRINGING RIGHTS;
and

                  (b) To make a reasonable and equitable adjustment, if any, to
the royalties paid or otherwise due under this AGREEMENT in respect of licenses
or other rights obtained by LICENSEE from third parties under such INFRINGING
RIGHTS in order for LICENSEE to continue to exercise rights granted under this
AGREEMENT.

                                      -9-
<PAGE>   11
8.       PATENT MARKING

         8.1 LICENSEE agrees that all packaging containing individual LICENSED
PRODUCT(S), and documentation therefor, sold by LICENSEE, SUBSIDIARIES, and
sublicensees of LICENSEE will be marked permanently and legibly with the number
of the applicable patent(s) licensed hereunder in accordance with each country's
patent laws, including Title 35, United States Code.

9.       INDEMNIFICATION

         9.1 LICENSEE shall hold harmless and indemnify BOARD, SYSTEM, MDA, its
Regents, officers, employees, students, and agents from and against those
damages finally awarded a third party in respect of any claims, demand, or
causes of action whatsoever, including without limitation those arising on
account of any injury or death of persons or damage to property caused by, or
arising out of, or resulting from, the exercise or practice of the license
granted hereunder by LICENSEE or its officers, employees, agents or
representatives, except to the extent such claim, demand or cause of action
arose from the negligence, recklessness or willful misconduct of BOARD, SYSTEM,
MDA, its Regents, officers, employees and agents, for which BOARD, SYSTEM, MDA,
to the extent authorized under the constitution and laws of the State of Texas,
shall similarly hold harmless and indemnify LICENSEE, its officers, employees,
agents or representatives.

         9.2 In no event shall any party to this AGREEMENT be liable for
indirect, consequential or similar damages, even if advised of the possibility
of such liability.

10.      USE OF BOARD AND COMPONENT'S NAME

         10.1 LICENSEE shall not use the name of MDA, SYSTEM or BOARD without
express written consent. Notwithstanding the above, LICENSEE may use the name of
MDA, BOARD or SYSTEM when indicating, as a factual matter, that MDA is a
licensor of LICENSEE under this AGREEMENT and only in connection with either or
both of the following:

                  (a) Communications associated with LICENSEE's financing
activities; and

                  (b) Communications (other than promotions and advertisements)
directed to describing or responding to inquiries concerning the business,
technology, products, services and associated activities of LICENSEE.

         LICENSEE may otherwise use the name of MDA, BOARD or SYSTEM when and as
required by applicable law, rules and regulations or upon MDA's consent, which
shall not be unreasonably withheld or delayed.

                                      -10-
<PAGE>   12
11.      CONFIDENTIAL INFORMATION

         11.1 BOARD and LICENSEE each agree that all information contained in
documents marked "confidential" which are forwarded to one by the other shall be
received in strict confidence, used only for the purposes of this AGREEMENT, and
not disclosed by the recipient party (except as required by law or court order),
its agents or employees without the prior written consent of the other party,
unless such information (a) was in the public domain at the time of disclosure,
(b) later became part of the public domain through no act or omission of the
recipient party, its employees, agents, successors or assigns, (c) was lawfully
disclosed to the recipient party by a third party having the right to disclose
it, (d) was already known by the recipient party at the time of disclosure, (e)
was independently developed or (f) is required to be submitted to a government
agency pursuant to any preexisting obligation.

         11.2 Each party's obligation of confidence hereunder shall be fulfilled
by using at least the same degree of care with the other party's confidential
information as it uses to protect its own confidential information. This
obligation shall exist while this AGREEMENT is in force and for a period of
three (3) years thereafter.

12.      ASSIGNMENT

         12.1 Except in connection with sale of LICENSEE's business, this
AGREEMENT may not be assigned by LICENSEE without the prior written consent of
BOARD, which shall not be unreasonably withheld.

13.      TERMS AND TERMINATION

         13.1 The term of this AGREEMENT shall extend from the EFFECTIVE DATE
set forth hereinabove to the full end of the term or terms for which PATENT
RIGHTS have not expired and if only TECHNOLOGY RIGHTS are licensed and no PATENT
RIGHTS are applicable, for a term of fifteen (15) years.

         13.2 BOARD shall have the right at any time after (i) five (5) years
from the date of this AGREEMENT or (ii) termination of both of the SPONSORED
RESEARCH AGREEMENTS, whichever is later, to terminate the license in any
national political jurisdiction if LICENSEE, within ninety days after written
notice from BOARD of such intended termination, fails to provide written
evidence that it has commercialized or is actively attempting to commercialize
an invention licensed hereunder within such jurisdiction. Evidence provided by
LICENSEE that it has an ongoing and active research, development, manufacturing,
marketing or licensing program as appropriate, directed toward production and
sale of products based on the invention disclosed and claimed in PATENTS or
incorporating TECHNOLOGY within such jurisdiction shall be deemed satisfactory
evidence.

                                      -11-
<PAGE>   13
         13.3     This AGREEMENT will earlier terminate in its entirety:

                  (a) automatically if LICENSEE shall become bankrupt or
insolvent and/or if the business of LICENSEE shall be placed in hand of a
receiver, assignee, or trustee, whether by voluntary act of LICENSEE or
otherwise;

                  (b) (i) upon thirty (30) days' written notice from BOARD if
LICENSEE shall breach or default on the payment obligations of Article V, or use
of name obligations of Article X; or (ii) upon ninety (90) days' written notice
if LICENSEE shall breach or default on any other obligation under this
AGREEMENT; provided, however, LICENSEE may avoid such termination if before the
end of such period LICENSEE notifies BOARD that such breach has been cured and
states the manner of such cure;

         13.4 Upon termination of this AGREEMENT for any cause, nothing herein
shall be construed to release either party of any obligation matured prior to
the effective date of such termination. LICENSEE may, after the effective date
of such termination, sell all LICENSED PRODUCT that it may have on hand at the
date of termination, provided that it pays earned royalty thereon as provided in
this AGREEMENT.

         13.5 Upon and effective as of the date of termination of this AGREEMENT
pursuant to Paragraphs 13.2 and 13.3 above, LICENSEE agrees to grant to BOARD a
royalty bearing license with the right to sublicense others with respect to
improvements made solely by LICENSEE in the LICENSED SUBJECT MATTER on terms to
be negotiated.

14.      GENERAL

         14.1 This AGREEMENT and the SPONSORED RESEARCH AGREEMENTS constitute
the entire and only AGREEMENT between the parties for LICENSED SUBJECT MATTER
and all other prior negotiations, representations, agreements and understandings
are superseded hereby. No agreements altering or supplementing the terms hereof
may be made except by means of a written document signed by the duly authorized
representatives of the parties.

         14.2 Any notice required by this AGREEMENT shall be given by prepaid,
first class, certified mail, return receipt requested, addressed in the case of
BOARD to:

                                        BOARD OF REGENTS

                                        The University of Texas System
                                        201 West Seventh Street
                                        Austin, Texas 78701
                                        ATTENTION:  Office of General 
                                        Counsel

                                      -12-
<PAGE>   14
   with copy to:                        The University of Texas
                                        M.D. Anderson Cancer Center
                                        Office of Technology Development
                                        1020 Holcombe Boulevard, Suite 1405
                                        Houston, Texas 77030
                                        ATTENTION:  William J. Doty

   or in the case of LICENSEE to:       RGene Therapeutics, Inc.
                                        2170 Buckthorne Place, Suite 170
                                        The Woodlands, Texas 77350
                                        ATTENTION:  Martin P. Sutter

or such other address as may be given from time to time under the terms of this
notice provision.

         14.3 LICENSEE shall comply with all applicable federal, state and local
laws and regulations in connection with its activities pursuant to this
AGREEMENT.

         14.4 This AGREEMENT shall be construed and enforced in accordance with
the laws of the United States of America and of the State of Texas.

         14.5 Failure of a party to enforce a right under this AGREEMENT shall
not act as a waiver of that right or the ability to later assert that right
relative to the particular situation involved.

         14.6 Headings included herein are for convenience only and shall not be
used to construe this AGREEMENT.

         14.7 If any provision of this AGREEMENT shall be found by a court to be
void, invalid or unenforceable, the same shall be reformed to comply with
applicable law or stricken if not so conformable, so as not to affect the
validity or enforceability of this AGREEMENT.

         14.8 This AGREEMENT may be executed in two counterparts, each of which
shall be deemed an original but all of which, taken together, shall constitute
one and the same instrument.


                                      -13-
<PAGE>   15
         IN WITNESS WHEREOF, parties hereto have caused their duly authorized
representatives to execute this AGREEMENT.

THE UNIVERSITY OF TEXAS                     BOARD OF REGENTS OF THE
M.D. ANDERSON CANCER CENTER                 UNIVERSITY OF TEXAS SYSTEM

By    /s/ DAVID J. BACHRACH              By    /s/ THOMAS G. RICKS
      -----------------------------            -------------------
      David J. Bachrach                        Thomas G. Ricks
      Executive Vice President                 Vice Chancellor for
      for Administration and Finance           Asset Management



APPROVED AS TO CONTENT:                     APPROVED AS TO FORM:

By    /s/ WILLIAM J. DOTY                By    /s/ DUDLEY R. DOBIE, JR.
      --------------------------               ----------------------------
      William J. Doty                          Dudley R. Dobie, Jr.
      Director, Technology Development         Manager, Intellectual Property

RGENE THERAPEUTICS, INC.

By    /s/ MARTIN P. SUTTER
     ------------------------------
      Martin P. Sutter
      Chairman of the Board


                                      -14-
<PAGE>   16
                                  ATTACHMENT A

         Patent and technology rights for U.S. Patent Application entitled:

         -        Methods and Compositions for the Suppression of Neu Mediated
 Transformation

                  Inventors:   Mien-Chie Hung, Ph.D. and Di-hua Yu, M.D., Ph.D.;
                               and

                  -        U.S. Serial No. 621,465, filed December 4, 1990, 
                           (MDA Ref: UTSC:203); and

                  -        Continuation-in-part Serial No. 070,410, filed June 
                           4, 1993, (MDA Ref: UTSC:256); and

                  -        Continuation-in-part, Serial No. 162,406, filed 
                           December 3, 1993, (MDA Ref: UTSC:364)
<PAGE>   17
                                                                      EXHIBIT 1A

SR94-02

                          SPONSORED RESEARCH AGREEMENT

         Agreement, made this 1st day of March, 1994, by and between The
University of Texas M.D. Anderson Cancer Center (hereinafter referred to as
"Cancer Center"), a component institution of The University of Texas System
(hereinafter referred to as "System"), located in Houston, Texas, and RGene
Therapeutics, Inc. (hereinafter referred to as "Sponsor"), located in The
Woodlands, Texas.

                                   WITNESSETH:

         WHEREAS, Sponsor is the manufacturer or licensee of the lipid based
gene and oligonucleotide delivery technologies which have potential utilization
in patient care and treatment; and

         WHEREAS, Cancer Center has research facilities and situations which
would allow investigation and study of "Targeting and Delivery of
Oligonucleotides to Leukemic Cells" as described in Exhibit I (hereinafter
referred to as "Research"), a copy of which is attached hereto and incorporated
herein by reference; and

         WHEREAS, both Sponsor and Cancer Center consider it necessary and 
desirable to perform the Research;

         NOW, THEREFORE, the parties agree as follows:

1.       EVALUATION

         Sponsor agrees to engage the services of Cancer Center as an
independent contractor to perform the Research. The Research will be under the
supervision of Gabriel Lopez-Berestein, M.D. (Principal Investigator) at Cancer
Center, with the assistance of appropriate associates and colleagues at Cancer
Center as may be required.

2.       RESEARCH

         Cancer Center agrees as an independent contractor to conduct the
Research. Such Research was originally approved by Cancer Center in accordance
with Cancer Center policy and may be subsequently amended only in accordance
with Cancer Center policy and the written agreement of Cancer Center and Sponsor
as provided for in Article 16 hereinbelow. Cancer Center shall provide written
report to Sponsor as requested, summarizing results of the Research, and all
such reports, test data, information, etc. shall be the property of Sponsor.
<PAGE>   18
3.       INVENTION AND PATENTS

         (a) For all purposes herein, "Invention" shall mean any discovery,
concept or idea whether or not patentable or copyrightable, which (i) arises out
of work performed pursuant to the obligations of this Agreement; (ii) is
conceived and reduced to practice during the term of the Agreement as defined in
Article 14 hereinbelow and within the six (6) month period thereafter; and (iii)
includes but is not limited to processes, methods, software, formulae,
techniques, compositions of matter, devices, and improvements thereof and
know-how relating thereto. Inventions made solely by the Principal Investigator
and/or other Cancer Center personnel as identified in Article 1 hereinabove or
agents of Cancer Center shall be the sole property of Cancer Center. Inventions
made jointly by employees or agents of Cancer Center and Sponsor shall be
jointly owned by Cancer Center and Sponsor. Inventions made solely by employees
or agents of Sponsor shall be the sole property of Sponsor

         (b) In the event that an Invention is made, either solely by employees
or agents of Cancer Center or jointly by employees or agents of Cancer Center
and Sponsor, Cancer Center and Sponsor agree to give notice of such Invention to
each other within thirty (30) days of the identification of such Invention.
Within thirty (30) days of notice of Invention, Cancer Center and Sponsor will
thereupon exert their best reasonable efforts in cooperation with each other to
investigate, evaluate and determine to the mutual satisfaction of both parties,
the disposition of rights to the Invention, including whether, by whom, and
where any patent applications are to be filed, subject to the terms of this
Article 3.

         (c) If, after consultation with Sponsor, it is agreed by the parties
that a patent application should be filed, Cancer Center will prepare and file
appropriate United States and foreign patent applications on Inventions made
under this Agreement and owned by Cancer Center, in whole or in part, and
Sponsor will pay the cost of preparing, filing and maintenance thereof. If
Sponsor notifies Cancer Center that it does not intend to pay the costs of an
application, or if Sponsor does not respond or make an effort to agree with
Cancer Center on the disposition of rights to the Invention, then Cancer Center
may file such application at its own expense, and Sponsor shall have no rights
to such Invention. Cancer Center will provide Sponsor a copy of the application
filed for which Sponsor has paid the cost of filing, as well as copies of any
documents received or filed during prosecution thereof. Sponsor agrees to
maintain any such application in confidence until it is published by Cancer
Center or by the respective patent office.

         (d) Any Invention made hereunder which is in the field of the molecular
biology of oncogenes and/or growth factors and/or nucleic acid, lipid based
gene, and/or oligonucleotide delivery technology and which results from the
research described in this Agreement ("Licensee Sponsored Technology") shall be
automatically licensed to Sponsor pursuant to the terms of the Patent and
Technology License Agreement dated 


                                       -2-
<PAGE>   19
March 1, 1994 between Cancer Center, the Board of Regents of The University of
Texas System and Sponsor (the "Patent and Technology License Agreement"), a copy
of which is attached hereto and incorporated herein as Exhibit II, without any
further action. This shall apply with like result to any Invention which
constitutes an Improvement (as defined in the Patent and Technology License
Agreement).

         (e) Any Invention made hereunder which is outside of the field
identified in Article 3(d) shall be subject to an option to Sponsor to negotiate
and acquire an exclusive, worldwide, royalty-bearing license to commercialize
such Invention (as well as patent applications, patents and copyrights thereon),
provided that Sponsor shall pay all costs and expenses associated with patent
and copyright filing, prosecution, issuance, and maintenance relating thereto.
Sponsor shall have ninety (90) days from the date of notice of Invention from
Cancer Center pursuant to Article 3(b) hereinabove, to give written notice to
Cancer Center exercising said option. In the event that Sponsor elects to
exercise its option to negotiate and acquire such a license in the time and
manner provided hereinabove, the parties agree to enter into good faith
negotiations regarding the terms and conditions of said license and further
agree to negotiate license fee rates and other payments which are fair and
reasonable to both parties.

         (f) In the event that parties fail to reach an agreement regarding the
terms and conditions of said license, within ninety (90) days after Sponsor's
notification to Cancer Center of Sponsor's exercise of said option pursuant to
Article 3(e) hereinabove, Cancer Center shall have the right to enter into
license agreements concerning the same Inventions with third parties on terms no
less favorable to Cancer Center than were last offered in writing by Sponsor.

4.       CONFIDENTIALITY

         Because Cancer Center and Sponsor will be cooperating with each other
in this Research, and because each may reveal to the other in the course of this
Research certain confidential information, Cancer Center and Sponsor agree to
hold any confidential information which (a) is obtained during the course of and
as a result of this work and (b) is related thereto and (c) is marked as
"CONFIDENTIAL" in confidence, and each party will not disclose same to any third
party without the express written consent of the other party to this Agreement.
This requirement shall remain in force during the term of this Agreement and for
a period of three (3) years following completion of work under this Agreement.
Nothing in this paragraph shall in any way restrict the rights of either Cancer
Center or Sponsor to use, disclose or otherwise deal with any information which:

                  (a) Can be demonstrated to have been in public domain as of
the effective date of this Agreement or comes into the public domain through the
term of this Agreement through no act of the recipient; or

                                       -3-
<PAGE>   20
         (b) Can be demonstrated to have been known to the recipient prior to
the execution of this Agreement; or

         (c) Can be demonstrated to have been rightfully received by the
recipient after disclosure under this Agreement from a third party who did not
require the recipient to hold it in confidence or limit its use and who did not
acquire it, directly or indirectly, under obligation of confidentiality to the
disclosing party; or

         (d) Shall be required for disclosure to federal regulatory agencies
pursuant to approval for use; or

         (e) Is independently invented by researchers of the recipient, which in
the case of Cancer Center includes System, who have not had access to the
information provided to the recipient hereunder.

Except as permitted under the Patent and Technology License Agreement, nothing
herein is intended to give Sponsor the right to use for any purpose preexisting
confidential information of Cancer Center. Notwithstanding the confidentiality
obligations of this Agreement, nothing herein shall prevent Cancer Center and
any other component of System from using any information generated hereunder for
ordinary research and educational purposes of a university.

5.   PUBLICATION RIGHTS

     Notwithstanding the provisions of Article 4 of this Agreement, Cancer
Center may publish scientific papers relating to the collaborative research
performed under this Agreement. In the event that Cancer Center wishes to
publish, Cancer Center shall notify Sponsor of its desire to publish at least
thirty (30) days in advance of publication and shall furnish to Sponsor a
written description of the subject matter of the publication in order to permit
Sponsor to review and comment thereon. Sponsor shall notify Cancer Center IN
writing within thirty (30) days of receipt of such draft whether such draft
contains information deemed to be confidential under the provisions of Article
4, or information that if published within thirty (30) days would have an
adverse effect on a patent application in which Sponsor owns full or part
interest, or intends to obtain an interest from Cancer Center pursuant to this
Agreement. In the latter case Sponsor has the right to request a delay and
Cancer Center agrees to delay said publication for a period not exceeding ninety
(90) days. In any such notification, Sponsor shall indicate with specificity to
what manner and degree Cancer Center may disclose said information. Cancer
Center shall have the final authority to determine the scope and content of any
publication, provided that such authority shall be exercised with reasonable
regard for the commercial interests of Sponsor.

                                      -4-
<PAGE>   21
6.   PUBLICITY

     Cancer Center acknowledges Sponsor's intention to distribute periodically
informational releases and announcements to the news media regarding the
progress of research hereunder. Sponsor shall not release such materials
containing the name of Cancer Center or any of its employees without prior
written approval by an authorized representative of Cancer Center, and said
approval shall not be unreasonably withheld. Should Cancer Center reject the
news release, Cancer Center and Sponsor agree to discuss the reasons for Cancer
Center's rejection, and every effort shall be made to develop an appropriate
informational news release within the bounds of accepted academic practices.
Sponsor reserves the same right in the event that Cancer Center desires to
distribute a news release concerning the research program. Nothing herein shall
be construed as prohibiting Cancer Center or Sponsor from reporting on this
study to a governmental agency or as prohibiting Sponsor from using the name of
Cancer Center or its employees, but only when indicating, as a factual matter,
that Sponsor is sponsoring research at Cancer Center under this Agreement and
only in connection with either or both of the following: (a) communications
associated with Sponsor's financing activities; and (b) communications (other
than promotions and advertisements) directed to describing or responding to
inquiries concerning the business, technology products, services and associated
activities of Sponsor. Sponsor may otherwise use the name of Cancer Center when
and as required by applicable law, rules and regulations, or upon Cancer
Center's consent, which shall not be unreasonably withheld or delayed.

7.   RESPONSIBILITY

     The parties each agree to assume individual responsibility for the actions
and omissions of their respective employees, agents and assigns in conjunction
with this evaluation.

8.   INDEPENDENT CONTRACTOR

     Sponsor will not have the right to direct or control the activities of
Cancer Center in performing the services provided herein, and Cancer Center
shall perform services hereunder only as an independent contractor, and nothing
herein contained shall be construed to be inconsistent with this relationship or
status. Under no circumstances shall Cancer Center be considered to be an
employee or agent of Sponsor. This Agreement shall not constitute, create or in
any way be interpreted as a joint venture, partnership or formal business
organization of any kind.

9.   TITLE TO EQUIPMENT

     Cancer Center shall retain title to all equipment purchased and/or
fabricated by it with funds provided by Sponsor under this Agreement.

                                      -5-
<PAGE>   22
10.  SURVIVORSHIP

     The provisions of Articles 3, 4, 5, 6, and 12 shall survive any expiration
or termination of this Agreement.

11.  ASSIGNMENT

     This Agreement may not be assigned by either party without the prior
written consent of the other party; provided, however, that Sponsor may assign
this Agreement to any purchaser or transferee of all or substantially all of
Sponsor's business upon prior written notice to Cancer Center.

12.  INDEMNIFICATION

     Cancer Center shall, to the extent authorized under the Constitution and
the laws of the State of Texas, indemnify and hold Sponsor and its officers,
directors, employees, agents and stockholders harmless from any and all
liability resulting from the negligent acts or omissions of Cancer Center, its
agents or employees pertaining to the activities to be carried out pursuant to
the obligations of this Agreement; provided, however, that Cancer Center shall
not hold Sponsor harmless from claims arising out of the negligence of Sponsor,
its officers, agents or any person or entity not subject to Cancer Center's
supervision or control.

     Sponsor shall indemnify and hold harmless System, Cancer Center, their
regents, officers, agents and employees from any liability or loss resulting
from judgments or claims against them arising out of the activities to be
carried out pursuant to the obligations of this Agreement or the use by Sponsor
of the results of the Research, provided, however, that the following is
excluded from Sponsor's obligation to indemnify and hold harmless:

         (a) the negligent failure of Cancer Center to comply with any
applicable governmental requirements; or

         (b) the negligence or willful malfeasance by a regent, officer, agent
or employee of Cancer Center or System.

13.  AWARD

     Sponsor agrees to pay Cancer Center a fee of [*] for expenses and other
related costs incurred in conjunction with the Research. This fee, as shown by
approximate category of expense in the attached Exhibit I which is attached
hereto and is incorporated 

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

     [*] Confidential Treatment Requested.

                                      -6-
<PAGE>   23
herein by reference, for information only, shall be payable in equal
installments of [*] each by Sponsor to Cancer Center. The first such installment
shall be due within thirty (30) days of the date of execution of this Agreement.
The subsequent installments shall be due and payable on a quarterly basis.

14.  BASIC TERM

     This Agreement shall become effective as of the date first hereinabove
written and unless earlier terminated as hereinafter provided, shall continue in
force for a period of two (2) years after the same, except as otherwise provided
herein.

15.  DEFAULT AND TERMINATION

     In the event that either party to this Agreement shall be in default of any
of its material obligations hereunder and shall fail to remedy such default
within thirty (30) days after receipt of written notice thereof, the party not
in default shall have the option of terminating this Agreement by giving written
notice thereof, notwithstanding anything to the contrary contained in this
Agreement. Termination of this Agreement shall not affect the rights and
obligations of the parties which accrued prior to the effective date of
termination. Sponsor shall pay Cancer Center for all reasonable expenses
incurred or committed to be expended as of the effective termination date,
subject to the maximum amount as specified in Article 13.

16.  ENTIRE AGREEMENT

     The parties acknowledge that this Agreement and Exhibit I and Exhibit II
(the Patent and Technology License Agreement) attached hereto represent the sole
and entire Agreement between the parties hereto pertaining to the Research and
that such supersedes all prior Agreements, understandings, negotiations and
discussions between the parties regarding same, whether oral or written. There
are no warranties, representations or other Agreements between the parties in
connection with the subject matter hereof except as specifically set forth
herein. No supplement, amendment, alteration, modification, waiver or
termination of this Agreement shall be binding unless executed in writing by the
parties hereto.

17.  REFORM OF AGREEMENT

     If any provision of this Agreement is, becomes or is deemed invalid,
illegal or unenforceable in any United States jurisdiction, such provision shall
be deemed amended to conform to applicable laws so as to be valid and
enforceable; or if it cannot be so 

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

     [*] Confidential Treatment Requested.

                                      -7-
<PAGE>   24
amended without materially altering the intention of the parties, it shall be
stricken, and the remainder of this Agreement shall remain in full force and
effect.

18.  NOTICES

     Any notices, statements or reports required by this Agreement shall be
considered given if sent by United States Certified Mail, postage prepaid and
addressed as follows:

     If to Cancer Center:

                   Michael J. Best
                   Chief Financial Officer
                   The University of Texas M.D. Anderson Cancer Center
                   1515 Holcombe Blvd.
                   Houston, Texas 77030

        If to Sponsor:

                   Martin P. Sutter
                   President
                   RGene Therapeutics, Inc.
                   2170 Buckthorne Place, Suite 170
                   The Woodlands, Texas 77380

19.  CAPTIONS

     The captions in this Agreement are for convenience only and shall not be
considered a part of or affect the construction or interpretation of any
provision of this Agreement.

20.  GOVERNING LAW

     This Agreement shall be governed and interpreted in accordance with the
substantive laws of the State of Texas and with applicable laws of the United
States of America.

        IN WITNESS WHEREOF, Cancer Center and Sponsor entered into this
Agreement effective as of the date first hereinabove written and have executed
two (2) originals each of which are of equal dignity.

RGENE THERAPEUTICS, INC.                           THE UNIVERSITY OF TEXAS
                                                   M.D. ANDERSON CANCER CENTER


BY: /s/ MARTIN P. SUTTER                           BY: /s/ MICHAEL J. BEST
    -------------------------                          -------------------------

                                      -8-
<PAGE>   25
TITLE:  Chairman                                     Michael J. Best
                                                     Chief Financial Officer

I have read this agreement and understand        CONTENT APPROVED:
my obligations hereunder:

BY: /s/ GABRIEL LOPEZ-BERESTEIN, M.D.            BY: /s/ DONNA S. GILBERG
    ---------------------------------                ---------------------------
    Gabriel Lopez-Berestein, M.D.                    Donna S. Gilberg, CPA
    Principal Investigator                           Manager, Sponsored Programs

                                                 FORM APPROVED:

BY: /s/ MARTIN N. RABER, M.D.                    BY: /s/ MATTHEW E. BURR
    -------------------------                        ---------------------------
    Martin N. Raber, M.D.                            Matthew E. Burr, J.D.
    Acting Head, Div. of Medicine                    Legal Services Officer

        Make Payment To:
        The University of Texas
        M.D. Anderson Cancer Center
        Attn:  Manager, Sponsored Programs
        P.O. Box 297402
        Houston, TX  77297
        Tax I.D. 74 6001118 A1

                                      -9-
<PAGE>   26
                                                                      EXHIBIT 1B

SR94-03

                          SPONSORED RESEARCH AGREEMENT

     Agreement, made this 1st day of March, 1994, by and between The University
of Texas M.D. Anderson Cancer Center (hereinafter referred to as "Cancer
Center"), a component institution of The University of Texas System (hereinafter
referred to as "System"), located in Houston, Texas, and RGene Therapeutics,
Inc. (hereinafter referred to as "Sponsor"), located in The Woodlands, Texas.

                                   WITNESSETH:

     WHEREAS, Sponsor is the manufacturer or licensee of the HER-2/neu gene
which has potential utilization in patient care and treatment; and

     WHEREAS, Cancer Center has research facilities and situations which would
allow investigation and study of "HER-2/neu Targeting Cancer Therapy" as
described in Exhibit I (hereinafter referred to as "Research"), a copy of which
is attached hereto and incorporated herein by reference; and

     WHEREAS, both Sponsor and Cancer Center consider it necessary and desirable
to perform the Research;

     NOW, THEREFORE, the parties agree as follows:

1.   EVALUATION

     Sponsor agrees to engage the services of Cancer Center as an independent
contractor to perform the Research. The Research will be under the supervision
of Mien-Chie Hung, Ph.D. (Principal Investigator) at Cancer Center, with the
assistance of appropriate associates and colleagues at Cancer Center as may be
required.

2.   RESEARCH

     Cancer Center agrees as an independent contractor to conduct the Research.
Such Research was originally approved by Cancer Center in accordance with Cancer
Center policy and may be subsequently amended only in accordance with Cancer
Center policy and the written agreement of Cancer Center and sponsor as provided
for in Article 16 herein below. Cancer Center shall provide written report to
Sponsor as requested, summarizing results of the Research, and all such reports,
test data, information, etc. shall be the property of Sponsor.
<PAGE>   27
3.   INVENTION AND PATENTS

     (a) For all purposes herein, "Invention" shall mean any discovery, concept
or idea whether or not patentable or copyrightable, which (i) arises out of work
performed pursuant to the obligations of this Agreement; (ii) is conceived and
reduced to practice during the term of the Agreement as defined in Article 14
hereinbelow and within the six (6) month period thereafter; and (iii) includes
but is not limited to processes, methods, software, formulae, techniques,
compositions of matter, devices, and improvements thereof and know-how relating
thereto. Inventions made solely by the Principal Investigator and/or other
Cancer Center personnel as identified in Article 1 hereinabove or agents of
Cancer Center shall be the sole property of Cancer Center. Inventions made
jointly by employees or agents of Cancer Center and Sponsor shall be jointly
owned by Cancer Center and Sponsor. Inventions made solely by employees or
agents of Sponsor shall be the sole property of Sponsor.

     (b) In the event that an Invention is made, either solely by employees or
agents of Cancer Center or jointly by employees or agents of Cancer Center and
Sponsor, Cancer Center and Sponsor agree to give notice of such Invention to
each other within thirty (30) days of the identification of such Invention.
Within thirty (30) days of notice of Invention, Cancer Center and Sponsor will
thereupon exert their best reasonable efforts in cooperation with each other to
investigate, evaluate and determine to the mutual satisfaction of both parties,
the disposition of rights to the invention, including whether, by whom, and
where any patent applications are to be filed, subject to the terms of this
Article 3.

     (c) If, after consultation with Sponsor, it is agreed by the parties that a
patent application should be filed, Cancer Center will prepare and file
appropriate United States and foreign patent applications on Inventions made
under this Agreement and owned by Cancer Center, in whole or in part, and
Sponsor will pay the cost of preparing, filing and maintenance thereof. If
Sponsor notifies Cancer Center that it does not intend to pay the costs of an
application, or if Sponsor does not respond or make an effort to agree with
Cancer Center on the disposition of rights to the invention, then Cancer Center
may file such application at its own expense, and Sponsor shall have no rights
to such Invention. Cancer Center will provide Sponsor a copy of the application
filed for which Sponsor has paid the cost of filing, as well as copies of any
documents received or filed during prosecution thereof. Sponsor agrees to
maintain any such application in confidence until it is published by Cancer
Center or by the respective patent office.

     (d) Any Invention made hereunder which is in the field of the molecular
biology of oncogenes and/or growth factors and/or nucleic acid, lipid based
gene, and/or oligonucleotide delivery technology and which results from the
research described in this Agreement ("Licensee Sponsored Technology") shall be
automatically licensed to Sponsor pursuant to the terms of the Patent and
Technology License Agreement dated

                                      -2-
<PAGE>   28
March 1, 1994 between Cancer Center, the Board of Regents of The University of
Texas System and Sponsor (the "Patent and Technology License Agreement"), a copy
of which is attached hereto and incorporated herein as Exhibit II, without any
further action. This shall apply with like result to any Invention which
constitutes an Improvement (as defined in the Patent and Technology License
Agreement).

     (e) Any Invention made hereunder which is outside of the field identified
in Article 3(d) shall be subject to an option to Sponsor to negotiate and
acquire an exclusive, worldwide, royalty-bearing license to commercialize such
Invention (as well as patent applications, patents and copyrights thereon),
provided that Sponsor shall pay all costs and expenses associated with patent
and copyright filing, prosecution, issuance, and maintenance relating thereto.
Sponsor shall have ninety (90) days from the date of notice of Invention from
Cancer Center pursuant to Article 3(b) hereinabove, to give written notice to
Cancer Center exercising said option. In the event that Sponsor elects to
exercise its option to negotiate and acquire such a license in the time and
manner provided hereinabove, the parties agree to enter into good faith
negotiations regarding the terms and conditions of said license and further
agree to negotiate license fee rates and other payments which are fair and
reasonable to both parties.

     (f) In the event that parties fail to reach an agreement regarding the
terms and conditions of said license, within ninety (90) days after Sponsor's
notification to Cancer Center of Sponsor's exercise of said option pursuant to
Article 3(e) hereinabove, Cancer Center shall have the right to enter into
license agreements concerning the same Inventions with third parties on terms no
less favorable to Cancer Center than were last offered in writing by Sponsor.

4.   CONFIDENTIALITY

     Because Cancer Center and Sponsor will be cooperating with each other in
this Research, and because each may reveal to the other in the course of this
Research certain confidential information, Cancer Center and Sponsor agree to
hold any confidential information which (a) is obtained during the course of and
as a result of this work and (b) is related thereto and (c) is marked as
"CONFIDENTIAL" in confidence, and each party will not disclose same to any third
party without the express written consent of the other party to this Agreement.
This requirement shall remain in force during the term of this Agreement and for
a period of three (3) years following completion of work under this Agreement.
Nothing in this paragraph shall in any way restrict the rights of either Cancer
Center or Sponsor to use, disclose or otherwise deal with any information which:

         (a) Can be demonstrated to have been in public domain as of the
effective date of this Agreement or comes into the public domain through the
term of this Agreement through no act of the recipient; or

                                      -3-
<PAGE>   29
         (b) Can be demonstrated to have been known to the recipient prior to
the execution of this Agreement; or

         (c) Can be demonstrated to have been rightfully received by the
recipient after disclosure under this Agreement from a third party who did not
require the recipient to hold it in confidence or limit its use and who did not
acquire it, directly or indirectly, under obligation of confidentiality to the
disclosing party; or

         (d) Shall be required for disclosure to federal regulatory agencies
pursuant to approval for use; or

         (e) Is independently invented by researchers of the recipient, which in
the case of Cancer Center includes System, who have not had access to the
information provided to the recipient hereunder; or

         (f) Is disclosed pursuant to any research grant relating to technology
included within the field from a noncommercial granting entity such as grants
from the Department of Health and Human services and other governmental and
private nonprofit agencies.

Except as permitted under the Patent and Technology License Agreement, nothing
herein is intended to give Sponsor the right to use for-any purpose pre-existing
confidential information of Cancer Center. Notwithstanding the confidentiality
obligations of this Agreement, nothing herein shall prevent Cancer Center and
any other component of System from using any information generated hereunder for
ordinary research and educational purposes of a university.

5.   PUBLICATION RIGHTS

     Notwithstanding the provisions of Article 4 of this Agreement, Cancer
Center may publish scientific papers relating to the collaborative research
performed under this Agreement. In the event that Cancer Center wishes to
publish, Cancer Center shall notify Sponsor of its desire to publish at least
thirty (30) days in advance of publication and shall furnish to Sponsor a
written description of the subject matter of the publication in order to permit
Sponsor to review and comment thereon. Sponsor shall notify Cancer Center in
writing within thirty (30) days of receipt of such draft whether such draft
contains information deemed to be confidential under the provisions of Article
4, or information that if published within thirty (30) days would have an
adverse effect on a patent application in which Sponsor owns full or part
interest, or intends to obtain an interest from Cancer Center pursuant to this
Agreement. In the latter case Sponsor has the right to request a delay and
Cancer Center agrees to delay said publication for a period not exceeding ninety
(90) days. In any such notification, Sponsor shall indicate with specificity to
what manner and degree Cancer Center may disclose said information. Cancer
Center shall have the final authority to determine the scope and content of any

                                      -4-
<PAGE>   30
publication, provided that such authority shall be exercised with reasonable
regard for the commercial interests of Sponsor.

6.   PUBLICITY

     Cancer Center acknowledges Sponsor's intention to distribute periodically
informational releases and announcements to the news media regarding the
progress of research hereunder. Sponsor shall not release such materials
containing the name of Cancer Center or any of its employees without prior
written approval by an authorized representative of Cancer Center, and said
approval shall not be unreasonably withheld. Should Cancer Center reject the
news release, Cancer Center and Sponsor agree to discuss the reasons for Cancer
Center's rejection, and every effort shall be made to develop an appropriate
informational news release within the bounds of accepted academic practices.
Sponsor reserves the same right in the event that Cancer Center desires to
distribute a news release concerning the research program. Nothing herein shall
be construed as prohibiting Cancer Center or Sponsor from reporting on this
study to a governmental agency or as prohibiting Sponsor from using the name of
Cancer Center or its employees, but only when indicating, as a factual matter,
that Sponsor is sponsoring research at Cancer Center under this Agreement and
only in connection with either or both of the following: (a) communications
associated with Sponsor's financing activities; and (b) communications (other
than promotions and advertisements) directed to describing or responding to
inquiries concerning the business, technology products, services and associated
activities of Sponsor. Sponsor may otherwise use the name of Cancer Center when
and as required by applicable law, rules and regulations, or upon Cancer
Center's consent, which shall not be unreasonably withheld or delayed.

7.   RESPONSIBILITY

     The parties each agree to assume individual responsibility for the actions
and omissions of their respective employees, agents and assigns in conjunction
with this evaluation.

8.   INDEPENDENT CONTRACTOR

     Sponsor will not have the right to direct or control the activities of
Cancer Center in performing the services provided herein, and Cancer Center
shall perform services hereunder only as an independent contractor, and nothing
herein contained shall be construed to be inconsistent with this relationship or
status. Under no circumstances shall Cancer Center be considered to be an
employee or agent of Sponsor. This Agreement shall not constitute, create or in
any way be interpreted as a joint venture, partnership or formal business
organization of any kind.

                                      -5-
<PAGE>   31
9.   TITLE TO EQUIPMENT

     Cancer Center shall retain title to all equipment purchased and/or
fabricated by it with funds provided by Sponsor under this Agreement.

10.  SURVIVORSHIP

     The provisions of Articles 3, 4, 5, 6, and 12 shall survive any expiration
or termination of this Agreement.

11.  ASSIGNMENT

     This Agreement may not be assigned by either party without the prior
written consent of the other party; provided, however, that Sponsor may assign
this Agreement to any purchaser or transferee of all or substantially all of
Sponsor's business upon prior written notice to Cancer Center.

12.  INDEMNIFICATION

     Cancer Center shall, to the extent authorized under the Constitution and
the laws of the State of Texas, indemnify and hold Sponsor and its officers,
directors, employees, agents and stockholders harmless from any and all
liability resulting from the negligent acts or omissions of Cancer Center, its
agents or employees pertaining to the activities to be carried out pursuant to
the obligations of this Agreement; provided, however, that Cancer Center shall
not hold Sponsor harmless from claims arising out of the negligence of Sponsor,
its officers, agents or any person or entity not subject to Cancer Center's
supervision or control.

     Sponsor shall indemnify and hold harmless System, Cancer Center, their
regents, officers, agents and employees from any liability or loss resulting
from judgments or claims against them arising out of the activities to be
carried out pursuant to the obligations of this Agreement or the use by Sponsor
of the results of the Research, provided, however, that the following is
excluded from Sponsor's obligation to indemnify and hold harmless:

         (a) the negligent failure of Cancer Center to comply with any
applicable governmental requirements; or

         (b) the negligence or willful malfeasance by a regent, officer, agent
or employee of Cancer Center or System.

                                      -6-
<PAGE>   32
13.  AWARD

     Sponsor agrees to pay Cancer Center a fee of [*] for expenses and other
related costs incurred in conjunction with the Research. This fee, as shown by
approximate category of expense in Exhibit I which is attached hereto and is
incorporated herein by reference, for information only, shall be payable in
equal installments of [*] each by Sponsor to Cancer Center. The first such
installment shall be due within thirty (30) days of the date of execution of
this Agreement. The subsequent installments shall be due and payable on a
quarterly basis.

14.  BASIC TERM

     This Agreement shall become effective as of the date first hereinabove
written and unless earlier terminated as hereinafter provided, shall continue in
force for a period of two (2) years after the same, except as otherwise provided
herein.

15.  DEFAULT AND TERMINATION

     In the event that either party to this Agreement shall be in default of any
of its material obligations hereunder and shall fail to remedy such default
within thirty (30) days after receipt of written notice thereof, the party not
in default shall have the option of terminating this Agreement by giving written
notice thereof, notwithstanding anything to the contrary contained in this
Agreement. Termination of this Agreement shall not affect the rights and
obligations of the parties which accrued prior to the effective date of
termination. Sponsor shall pay Cancer Center for all reasonable expenses
incurred or committed to be expended as of the effective termination date,
subject to the maximum amount as specified in Article 13.

16.  ENTIRE AGREEMENT

     The parties acknowledge that this Agreement, Exhibit I and Exhibit II (the
patent and Technology License Agreement) attached hereto represent the sole and
entire Agreement between the parties hereto pertaining to the Research and that
such supersedes all prior Agreements, understandings, negotiations and
discussions between the parties regarding same, whether oral or written. There
are no warranties, representations or other Agreements between the parties in
connection with the subject matter hereof except as specifically set forth
herein. No supplement, amendment, alteration, modification, waiver or
termination of this Agreement shall be binding unless executed in writing by the
parties hereto.

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     [*] Confidential Treatment Requested.

                                      -7-
<PAGE>   33

17.  REFORM OF AGREEMENT

     If any provision of this Agreement is, becomes or is deemed invalid,
illegal or unenforceable in any United States jurisdiction, such provision shall
be deemed amended to conform to applicable laws so as to be valid and
enforceable; or if it cannot be so amended without materially altering the
intention of the parties, it shall be stricken, and the remainder of this
Agreement shall remain in full force and effect.

18.  NOTICES

     Any notices, statements or reports required by this Agreement shall be
considered given if sent by United States Certified Mail, postage prepaid and
addressed as follows:

     If to Cancer Center:

                   Michael J. Best
                   Chief Financial Officer
                   The University of Texas M.D. Anderson Cancer Center
                   1515 Holcombe Blvd.
                   Houston, Texas 77030

     If to Sponsor:

                   Martin P. Sutter
                   President
                   RGene Therapeutics, Inc.
                   2170 Buckthorne Place, Suite 170
                   The Woodlands, Texas 77380

19.  CAPTIONS

     The captions in this Agreement are for convenience only and shall not be
considered a part of or affect the construction or interpretation of any
provision of this Agreement.

20.  GOVERNING LAW

     This Agreement shall be governed and interpreted in accordance with the
substantive laws of the State of Texas and with applicable laws of the United
States of America.

                                      -8-
<PAGE>   34
     IN WITNESS WHEREOF, Cancer Center and Sponsor entered into this Agreement
effective as of the date first hereinabove written and have executed two (2)
originals each of which are of equal dignity.

RGENE THERAPEUTICS, INC.                       THE UNIVERSITY OF TEXAS
                                               M.D. ANDERSON CANCER CENTER


BY:   /s/ MARTIN P. SUTTER                     BY:   /s/ MICHAEL J. BEST
      ---------------------------                    ---------------------------
TITLE:  Chairman                                     Michael J. Best
                                                     Chief Financial Officer

I have read this agreement and understand      CONTENT APPROVED:
my obligations hereunder:


BY:   /s/ MIEN-CHIE HUNG                       BY:   /s/  DONNA S. GILBERG 
      ---------------------------                    ---------------------------
      Mien-Chie Hung, Ph.D.                          Donna S. Gilberg, CPA
      Principal Investigator                         Manager, Sponsored Programs

                                               FORM APPROVED:



BY:   /s/ GARTH L. NICOLSON                    BY:   /s/  MATTHEW E. BURR
      ---------------------------                    ---------------------------
      Garth L. Nicolson, Ph.D.                       Matthew E. Burr, J.D.
      Chairman, Dept. of Tumor Biology               Legal Services Officer

        Make Payment To:
        The University of Texas
        M.D. Anderson Cancer Center
        Attn:  Manager, Sponsored Programs
        P.O. Box 297402
        Houston, TX  77297
        Tax I.D. 74 6001118 A1

                                      -9-
<PAGE>   35
                                                                       EXHIBIT 2


                            RGENE THERAPEUTICS, INC.
                             GABRIEL LOPEZ-BERESTEIN

                            STOCK PURCHASE AGREEMENT

        This Stock Purchase Agreement (this "Agreement") dated February 14, 1994
is entered into by and between RGene Therapeutics, Inc., a Delaware corporation
(the "Company"), and Gabriel Lopez-Berestein (the "Buyer").

                              W I T N E S S E T H:

        WHEREAS, the Company desires to sell certain shares of common stock,
$.001 par value, of the Company (the "Common Stock") to the Buyer; and

        WHEREAS, the Buyer desires to purchase certain shares of Common Stock
from the Company; and

        WHEREAS, the Buyer and the Company desire that the Buyer grant to the
Company, and under certain circumstances to holders of the Company's Preferred
Stock or other securities issued by the Company to investors (the "Investors"),
options to repurchase certain shares of Common Stock purchased by the Buyer on
the terms and conditions set forth;

        NOW, THEREFORE, for and in consideration of the mutual promises,
covenants and obligations contained herein, the parties agree as follows:

1.      PURCHASE AND SALE OF SHARES

        1.1    PURCHASE AND SALE OF SHARES

        Subject to the terms and conditions of this Agreement and in
consideration of the payment of the Purchase Price (as defined below) by the
Buyer to the Company at the Closing (as defined below), the Company agrees to
sell to the Buyer, and the Buyer agrees to purchase from the Company, [*] shares
of Common Stock (the "Shares").

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

     [*] Confidential Treatment Requested.
<PAGE>   36
        1.2    PURCHASE PRICE

        The Purchase Price payable to the Company shall be $[*]per Share,
payable in cash at the Closing.

        1.3    CLOSING

        The closing for the sale of the Shares to the Buyer shall occur on or
before February 15, 1994, or at such other date and time as the parties may
agree (the "Closing"). Concurrent with the payment by Buyer of the Purchase
Price, or within a reasonable time thereafter, the Company shall deliver to
Buyer a certificate or certificates representing the number of Shares as set
forth in Section 1.1 hereof, in the name of the Buyer.

2.      REPRESENTATIONS AND WARRANTIES

        To induce the Company to deliver the Shares to the Buyer, the Buyer
represents and warrants to the Company:

               (a) The Buyer is acquiring the Shares for his own account as
principal, for investment purposes only, and not with a view to, or for, resale
or distribution, and no other person has a direct or indirect beneficial
interest in the Shares;

               (b) The Buyer has not offered any of the Shares for resale and
has no present intention of dividing his interest with others or of reselling or
otherwise disposing of any of the Shares;

               (c) Any information the Buyer has furnished to the Company with
respect to the Buyer's status as a sophisticated or accredited investor, his
business experience or financial position is correct;

               (d) The financial capacity of the Buyer is such that the
investment in the Shares is not material to his total financial capacity; the
Buyer has the financial ability to bear the economic risk of his investment, has
adequate means for providing for his current needs and personal contingencies
and has no need for liquidity with respect to his investment in the Shares;

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

     [*] Confidential Treatment Requested.

                                      -2-
<PAGE>   37
               (e) The Buyer considers himself to be a sophisticated investor
and has such knowledge and experience in financial and business matters as to be
capable of evaluating the merits and risks of the prospective investment in the
Shares;

               (f) The Buyer has been furnished with all information concerning
the Shares and the Company that he desires;

               (g) The Buyer has been given the opportunity to ask questions of,
and receive answers from, the Company with respect to the Shares, concerning the
terms and conditions of the offering and other matters pertaining to this
investment, and has been given the opportunity to obtain such additional
information necessary to verify the accuracy of the information provided to him
by the Company in order for him to evaluate the merits and risks of investment
in the Shares to the extent that the Company possessed such information or could
acquire it without unreasonable effort or expense; and

               (h) The Buyer is not relying on the Company with respect to any
economic considerations of the Buyer related to this investment. In regard to
the economic considerations related to this investment, the Buyer has relied on
the advice of, or has consulted with, only his own advisors.

        The Buyer further represents, warrants and agrees that he will not sell
or otherwise transfer the Shares without registration under the Securities Act
of 1933, as amended (the "Act"), or an exemption therefrom, and fully
understands and agrees that he must bear the economic risk of his purchase for
an indefinite period of time because, among other reasons, the Shares have not
been registered under the Act or under the securities laws of any state and,
therefore, cannot be resold, pledged, assigned or otherwise disposed of unless
they are subsequently registered under the Act and under the applicable
securities laws of such states or an exemption from such registration is
available. He also understands that the Company is under no obligation to
register the Shares on his behalf or to assist him in complying with any
exemption from registration under the Act. He further understands that any
certificate evidencing the Shares will bear a legend restricting the transfer
thereof consistent with the foregoing and that a notation may be made in the
records of the Company restricting the transfer of any Shares in a manner
consistent with the foregoing.

3.      BUYER AWARENESS

        The Buyer acknowledges that he is aware that:

               (a) No federal or state agency has passed upon the Shares or made
any finding or determination as to the fairness of this investment;

                                      -3-
<PAGE>   38
               (b) There are substantial risks of loss of investment incident to
an investment in the Shares and such an investment is highly speculative;

               (c) The Company is only recently organized, has not conducted any
substantial business to date and does not have any substantial working capital
or financial resources. The business in which the Company proposes to engage is
highly competitive and success in the Company's business may depend on, among
other things, the Company's ability to obtain financing, to complete product
development, to attract qualified employees and to obtain patent protection and
governmental approvals, market acceptance of products and numerous other factors
over which the Company does not have control.

4.      RESTRICTIONS ON TRANSFER; RIGHT OF FIRST REFUSAL

        4.1    COMPANY'S PURCHASE OPTION

        Buyer shall not sell, transfer, pledge, hypothecate or otherwise dispose
of any Shares which are purchased hereunder without first complying with the
terms of this Section 4.

        4.2    RIGHT OF FIRST REFUSAL

        Before any of the Shares registered in the name of Buyer may be sold or
transferred (including transfer by operation of law), except as permitted in
Section 5, such Shares shall first be offered to the Company and to the
Investors, in accordance with the terms set out herein, provided, however, that
until the Company has completed a public offering of its equity securities
pursuant to an effective registration statement filed with the Securities and
Exchange Commission, no transfer of Shares may be made under any circumstances.

               (i) Buyer shall deliver a notice ("Notice") to the Company and to
the Investors stating (A) his bona fide intention to sell or transfer such
Shares, (B) the number of such Shares to be sold or transferred, (C) the price
for which he proposes to sell or transfer such Shares, and (D) the name of the
proposed purchaser or transferee.

              (ii) Within thirty (30) days after receipt of the Notice, the
Company and/or the Investors may elect to purchase some or all of the Shares to
which the Notice refers, at the price per share specified in the Notice. The
closing for such purchase by the Company and/or the Investors shall occur,
unless otherwise agreed by the Company, the Investors electing to purchase
Shares, and the Buyer, no later than 30 days after the election by the Company
and/or the Investors to purchase same. In

                                      -4-
<PAGE>   39
the event that the number of Shares which the Company and the Investors desire
to purchase exceeds the number of Shares proposed for sale by Buyer in the
Notice, then in such instance the Company shall have full preference to acquire
such Shares to the exclusion of the Investors, and, to the extent that there are
Shares still available for purchase by the Investors, the Investors desiring to
purchase Shares shall be entitled to purchase the remaining amount thereof on a
pro rata basis based upon the number of shares of Common Stock and Preferred
Stock, or securities convertible into shares of Common Stock and Preferred
Stock, then held by each of them so electing to purchase bears to the total
number of shares of Common Stock and Preferred Stock, or securities convertible
into shares of Common Stock and Preferred Stock, held by all Investors desiring
to acquire Shares, on a fully diluted as if converted to Common Stock basis.

             (iii) If all of the Shares to which the Notice refers are not
purchased by the Company and the Investors, as provided in Section 4.2(ii)
hereof, Buyer may sell such Shares which the Company and the Investors elected
not to purchase to any person or persons named in the Notice at the price
specified in the Notice or at a higher price, provided that such sale or
transfer is consummated within 120 days of the date of said Notice to the
Company and the investors, and provided, further, that any such sale is in
accordance with all the terms and conditions hereof.

              (iv) Upon the closing of a firm commitment public offering
pursuant to an effective registration statement filed by the Company under the
Securities Act of 1933, as amended (the "Act"), covering the offering and sale
of shares of Common Stock for the account of the Company in which the aggregate
gross proceeds received by the Company equal or exceed $7,500,000 and in which
the public offering price per share equals or exceeds $5.00 per share, the
thirty (30) day period specified in Section 4.2(ii) above shall be reduced to a
ten (10) day period; and the requirement to identify the name of the proposed
purchaser and the proposed price shall be inapplicable if the Buyer proposed to
sell the Shares in an over-the-counter sale or on a national or regional
exchange transaction. In such instance, any such sale to the Company and/or the
Investors shall be at the average closing price of the Company's Common Stock on
the date of notice of election to purchase such shares by the Company and/or the
Investors. The average closing price is defined as the last closing price
regular way on the exchange where the Common Stock is listed for trading or the
average of the bid and ask prices if applicable.

        4.3    STANDOFF AGREEMENT

        Buyer agrees, in connection with each of the Company's public offerings
of its equity securities, and upon request of the Company or the underwriters
managing such offering, not to sell, make any short sale of, loan, grant any
option for the 

                                      -5-
<PAGE>   40
purchase of or otherwise dispose of any of the Shares (other than those included
in the registration, if any) without the prior written consent of the Company or
such underwriters, as the case may be, for such period of time from the
effective date of such registration as may be requested by the Company or such
underwriters; provided, that the officers and directors of the Company who own
stock of the Company also agree to such restrictions.

        4.4    OTHER RESTRICTIONS ON TRANSFER

        The Company shall not be required (i) to transfer on its books any of
the Shares which shall have been sold or transferred in violation of any of the
provisions set forth in this Agreement, or (ii) to treat as owner of such Shares
or to accord the right to vote as such owner or to pay dividends to any
transferee to whom such Shares shall have been so transferred.

5.      EXEMPT TRANSACTIONS

        5.1    CERTAIN TRANSACTIONS

        The prohibition in Section 4 against the sale of the Shares shall not
apply to the exchange of Shares pursuant to a plan or merger, consolidation,
recapitalization, reorganization, or sale of the Company, in which the Company
is the surviving entity, but any stock or securities received in exchange
therefor shall also become subject to this Agreement.

        5.2    PERMITTED TRANSFERS

        The prohibition in Section 4 against the sale of Shares shall not apply
to a transfer by Buyer of all or part of his Shares during his lifetime or on
death by will or by intestacy to or for the benefit of himself, his spouse, his
ancestors or his lineal descendants, provided that any such transferee or
transferees shall receive and hold the Shares subject to the terms of this
Agreement, and there shall be no further transfer of such Shares except in
accordance with the terms of this Agreement.

6.      ASSIGNMENT

        The Company may assign this Agreement or any of its rights and
obligations hereunder. The Buyer may not assign this Agreement or any of his
rights and obligations hereunder. All covenants and agreements of, and benefits
for, the Investors contained in this Agreement shall inure to the benefit of
their respective successors and assigns and be binding on the Company and its
successors and on the Buyer and his heirs, executors, administrators and
successors. All such covenants and 

                                      -6-
<PAGE>   41
agreements are fully assignable by the Investors, provided, however, that any
assignment of any of its rights under this Agreement by any Investor (other than
to partners of such Investor or successors of such Investor or such partners by
operation of law) shall be made only in connection with the sale or other
transfer of all or any portion of the Preferred Stock, Common Stock, convertible
notes, warrants, options or other securities of the Company which are
exchangeable or convertible into shares of Common Stock or Preferred Stock of
the Company held by such Investor and such assignee or transferee shall execute
this Agreement.

7.      ADJUSTMENTS

        If, from time to time during the term of this Agreement (i) there is any
stock dividend or liquidating dividend of cash or property, stock split or other
change in the character or amount of any of the outstanding securities of the
Company, or (ii) there is any transaction involving the consolidation, merger or
sale of all, or substantially all, of the assets of the Company, then, in such
event, (x) any and all new, substituted or additional securities or other
property to which the Buyer is entitled by reason of his ownership of the Shares
shall be immediately subject to right of first refusal provided to the Company
and the Investors as described in Section 4 hereof and (y) all Shares purchased
by Buyer hereunder shall be treated on the same basis as all other outstanding
shares of Common Stock of the Company so that Buyer's Shares shall not be
diluted by any such event any differently than any other holder of Common Stock
of the Company.

8.      LEGENDS

        All certificates representing any of the Shares subject to the
provisions of this Agreement shall have endorsed thereon a legend substantially
as follows:

                      "ANY DISPOSITION, GRANT OR OTHER TRANSFER OF ANY INTEREST
               IN THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS SUBJECT TO
               CERTAIN RESTRICTIONS, AND THE SECURITIES REPRESENTED BY THIS
               CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL, CONTAINED IN
               A CERTAIN AGREEMENT BY THE RECORDHOLDER HEREOF AND THE
               CORPORATION, A COPY OF WHICH WILL BE MAILED TO ANY HOLDER OF THIS
               CERTIFICATE WITHOUT CHARGE AFTER RECEIPT BY THE CORPORATION OF A
               WRITTEN REQUEST THEREFOR."

                                      -7-
<PAGE>   42
        Upon presentation to the Company or any authorized transfer agent, the
certificates representing the Shares or any appropriate portion thereof shall be
exchanged for certificates not bearing such legend if the certificates are
presented after the termination of this Agreement.

9.      RIGHTS AS A STOCKHOLDER; VOTING AGREEMENT

        Subject to the provisions of Section 4 above, the Buyer shall, during
the term of this Agreement, exercise all rights and privileges of a stockholder
of the Company with respect to the Shares, including the right to vote such
Shares at any stockholder meeting. Notwithstanding anything herein to the
contrary, Buyer hereby agrees that he will, for a ninety-day period following
the issuance of the Shares or until the closing of the first round financing by
the Company in an amount at least equal to $2,000,000, whichever comes first,
vote such Shares, at any stockholder meeting, in person, by proxy, by written
consent, or otherwise, for the directors nominated for election to the Board of
Directors of the Company by The Woodlands Venture Fund and no others, and, in
any other matter coming before the stockholders of the Company, in accordance
with the directive of The Woodlands Venture Fund.

        In order to secure the obligation to vote in accordance with the
provisions hereof, the Buyer hereby appoints Martin P. Sutter as his true and
lawful proxy and attorney, with full power of substitution, to vote all of his
Shares for the matters specified hereinabove. The irrevocable proxy granted by
the Buyer may be exercised at any time Buyer fails to comply with the terms of
this Section 9. The proxy and power granted by the Buyer pursuant to this
section are coupled with an interest and are given to secure the duties of the
Buyer pursuant hereto. Such proxy will be irrevocable and will survive the
death, incompetency, and disability of Buyer, provided that it shall terminate
upon the expiration of twelve months following the issuance of the Shares.

        Buyer hereby consents to the placement of an appropriate legend
evidencing the voting restrictions provided for in this Agreement, on the
certificates representing the Shares and any certificates issued in replacement
or exchange therefor, and Buyer will take all actions reasonably requested by
the Company to effect such placement.

10.     TERMINATION

        Except as may be otherwise provided herein, this Agreement shall
terminate on the 91st calendar day immediately succeeding the third anniversary
of the public offering referenced in Section 4.2.

                                      -8-
<PAGE>   43
11.     MISCELLANEOUS

        11.1   NOTICE

        For purposes of this Agreement, notices and all other communications
provided for herein shall be in writing and shall be deemed to have been duly
given when personally delivered or when mailed by United States registered or
certified mail, return receipt requested, postage prepaid, addressed as follows:

        If to the Company:

               RGene Therapeutics, Inc.
               c/o The Woodlands Venture Fund
               2170 Buckthorne Place, Suite 170
               The Woodlands, Texas 77380
               Attention:  Martin P. Sutter

        If to the Buyer, at the address identified on the signature page hereof,
and if to an Investor, at the address identified on the records of the Company
hereto, or to such other address as either party or an Investor may furnish to
the other in writing in accordance herewith, except that notices of change of
address shall be effective only upon receipt.

        11.2   APPLICABLE LAW

        The substantive laws of the State of Texas, excluding any law, rule or
principle which might refer to the substantive law of another jurisdiction, will
govern the interpretation, validity and effect of this Agreement without regard
to the place of execution or the place for performance thereof. This Agreement
is to be at least partially negotiated, executed and performed in Harris County,
Texas, and, as such, the Company and the Buyer agree that personal jurisdiction
and venue shall be proper with the state or federal courts situated in Harris
County, Texas, to hear such disputes arising under this Agreement.

        11.3   NO WAIVER

        No failure by either party hereto at any time to give notice of any
breach by the other party of, or to require compliance with, any condition or
provision of this Agreement shall be deemed a waiver of similar or dissimilar
provisions or conditions at the same or at any prior or subsequent time.

                                      -9-
<PAGE>   44
        11.4   SEVERABILITY

        If a court of competent jurisdiction determined that any provision of
this Agreement, including any appendices attached hereto, is invalid or
unenforceable, then the invalidity or unenforceability of that provision shall
not affect the validity or enforceability of any other provision of this
Agreement, and all other provisions shall remain in full force and effect.
Further, such provision shall be reformed and construed to the extent permitted
by law so that it may be valid, legal and enforceable to the maximum extent
possible.

        11.5   COUNTERPARTS

        This Agreement may be executed in one or more counterparts, each of
which shall be deemed to be an original, but all of which together will
constitute one and the same Agreement.

        11.6   HEADINGS

        The section headings have been inserted for purposes of convenience and
shall not be used for interpretive purposes.

        11.7   SUCCESSORS; THIRD PARTY BENEFICIARY

        This Agreement shall inure to the benefit of the successors and assigns
of the Company and the Investors and be binding upon the Buyer and his heirs,
executors, administrators and successors. The Buyer agrees that any and all
Investors in the Company shall be treated as third party beneficiaries of this
Agreement without the necessity of execution of this Agreement, and shall be
entitled to all of the rights rendered to them herein.

        11.8   ENTIRE AGREEMENT

        This Agreement constitutes the entire agreement of the parties with
regard to the subject matter hereof, and contains all the covenants, promises,
representations, warranties and agreements between the parties with respect to
the subject matter hereof. Each party to this Agreement acknowledges that no
representation, inducement, promise or agreement, oral or written, with regard
to the subject matter hereof, has been made by either party, or by anyone acting
on behalf of either party, which is not embodied herein, and that no agreement,
statement or promise relating to the subject matter hereof which is not
contained in this Agreement or in such other agreements shall be valid and
binding.

                                      -10-
<PAGE>   45
        11.9   AMENDMENTS

        No amendment or modification to this Agreement will be effective unless
it is in writing and signed by the Company, the Buyer and, if such amendment
alters or amends any of the rights of the Investors, by Investors holding a
majority of the outstanding shares of capital stock of the Company held by such
Investors, if any.

        11.10  INDEMNITY

        The Buyer agrees to indemnify and hold harmless the Company and any
person, if any, who controls the Company or such successor within the meaning of
Section 15 of the Act against any and all loss, liability, claim, damage and
expense whatsoever (including, but not limited to, any and all expenses
whatsoever reasonably incurred in investigating, preparing or defending against
any litigation commenced or threatened or any claim whatsoever) arising out of
or based upon any fuse representation or warranty or breach or failure by the
Buyer to comply with any covenant or agreement made by the Buyer herein or in
any other document furnished by the Buyer in connection with this transaction.

        11.11  INJUNCTIVE RELIEF

        In view of the inadequacy of money damages, and in view of the fact that
the stock of the Company cannot be readily purchased or sold in the general
market, if the Buyer or any other person shall fail to comply with any provision
of this Agreement, the Company shall be entitled, to the extent permissible by
law, to injunctive relief in the case of the violation, or attempted or
threatened violation, by Buyer or other person of any such provision, or to a
decree compelling specific performance by the Buyer or other person, of any such
provision, or to any other remedies legally available.

        11.12  SPOUSES

        The spouse of the Buyer, if any, hereby represents and acknowledges that
he or she is fully aware of, understands, and fully consents and agrees to the
provisions of this Agreement and its binding effect upon any community property
interest he or she may now or hereafter own. Said spouse agrees that the
termination of their marital relationship with the Buyer for any reason or his
or her death shall not have the effect of removing any stock of the Company
otherwise subject to this Agreement from its coverage. Said spouse's awareness,
understanding, consent and agreement is evidenced by the execution of this
Agreement. All stock described in this Agreement shall include the community
property interest of the spouse of Buyer.

                                      -11-
<PAGE>   46
        11.13  VOID TRANSFERS

        If any Stock shall be sold or transferred otherwise than in accordance
with the terms and conditions of this Agreement, such sale shall be void. Any
such attempted sale or other transfer shall create a right in the Company to
purchase the Stock which is the subject of such purported transfer at the
applicable purchase price specified herein. Such right shall constitute an
"adverse claim" within the meaning of such term as used within the meaning of
the Uniform Commercial Code of any State. In addition to, and without prejudice
to, any and all other rights or remedies which may be available to the Company,
the Buyer agrees that the Company may, but shall have no obligation to, hold and
refuse to transfer any Stock, or any certificate therefor, tendered to it for
transfer if the transfer violates the provisions of the Agreement.

        11.14  TAX REPRESENTATIONS

        The Buyer acknowledges that the Company has made no warranties or other
representations to Buyer with respect to the income tax consequences of the
transactions contemplated by this Agreement and the Buyer is in no manner
relying on the Company or its representatives for an account of such tax
consequences.

        11.15  FURTHER ASSURANCES

        The parties agree to execute such further instruments and to take such
further action as may reasonably be necessary to carry out the intent of this
Agreement.

                                      -12-
<PAGE>   47
     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
and delivered as of the day and year first above written.

                                            Company

                                            RGENE THERAPEUTICS, INC.


                                            By:    /s/ MARTIN P. SUTTER
                                                   -----------------------------
                                            Name:  Martin P. Sutter
                                                   -----------------------------
                                            Title: Chairman
                                                   -----------------------------

Buyer's Spouse                              Buyer

Signed:     /s/ SONIA LOPEZ                 Signed:     /s/ G. LOPEZ-BERESTEIN
            -----------------------------               ------------------------
Print Name: Sonia Lopez                     Print Name: G. Lopez-Berestein
            -----------------------------               ------------------------
Address:                                    Address:
            -----------------------------               ------------------------
            -----------------------------               ------------------------
            -----------------------------               ------------------------
            -----------------------------               ------------------------

                                      -13-
<PAGE>   48
                                                                       EXHIBIT 3


                            RGENE THERAPEUTICS, INC.
                              MIEN CHIE HUNG, PH.D.

                            STOCK PURCHASE AGREEMENT

        This Stock Purchase Agreement (this "Agreement") dated February 14, 1994
is entered into by and between RGene Therapeutics, Inc., a Delaware corporation
(the "Company"), and Mien Chie Hung, Ph.D. (the "Buyer").

                                   WITNESSETH:

        WHEREAS, the Company desires to sell certain shares of common stock,
$.001 par value, of the Company (the "Common Stock") to the Buyer; and

        WHEREAS, the Buyer desires to purchase certain shares of Common Stock
from the Company; and

        WHEREAS, the Buyer and the Company desire that the Buyer grant to the
Company options to repurchase certain shares of Common Stock purchased by the
Buyer on the terms and conditions set forth;

        NOW, THEREFORE, for and in consideration of the mutual promises,
covenants and obligations contained herein, the parties agree as follows:

1.      PURCHASE AND SALE OF SHARES

        1.1    PURCHASE AND SALE OF SHARES

        Subject to the terms and conditions of this Agreement and in
consideration of the payment of the Purchase Price (as defined below) by the
Buyer to the Company at the Closing (as defined below), the Company agrees to
sell to the Buyer, and the Buyer agrees to purchase from the Company, [*] shares
of Common Stock (the "Shares").

        1.2    PURCHASE PRICE

        The Purchase Price payable to the Company shall be $[*] per Share,
payable as follows: the Company shall deduct the Purchase Price from the first
month's consulting fee owed to Buyer under that certain Consulting Agreement
between the Buyer and the Company dated the date hereof (the "Consulting
Agreement").

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

     [*] Confidential Treatment Requested.

<PAGE>   49
        1.3    CLOSING

        The closing for the sale of the Shares to the Buyer shall occur on or
before February 15, 1994, or at such other date and time as the parties may
agree (the "Closing"). Concurrent with the payment by Buyer of the Purchase
Price, or within a reasonable time thereafter, the Company shall deliver to
Buyer a certificate or certificates representing the number of Shares as set
forth in Section 1.1 hereof, in the name of the Buyer.

2.      REPURCHASE OPTION

        (a) A total of [*] of the Shares purchased by Buyer pursuant to this
Agreement (hereinafter, the "Option Shares") shall be subject to the option
("Repurchase Option") set forth in this Section 2. In the event the Buyer shall
cease to be engaged by the Company (including a parent or subsidiary of the
Company) as a Consultant for any reason, voluntarily or involuntarily, the
Company shall have the right, at any time within 90 days after the date Buyer
ceases to be so engaged, to exercise the Repurchase Option, which consists of
the right to purchase from the Buyer at a purchase price of $[*] per share (the
"Unvested Option Price"), up to but not exceeding the number of Option Shares
specified in Section 2(b)(i) below, upon the terms hereinafter set forth.

        (b) (i) If the Buyer's engagement by the Company under the Consulting
Agreement is terminated at any time prior to the second anniversary thereof, the
Company may exercise the Repurchase Option at the Unvested Option Price as to
all or any number of the Option Shares less the number of Option Shares equal to
1/24th of the balance of the Option Shares (rounded down to the nearest whole
Option Share) for each and every full calendar month that the Buyer was engaged
by the Company as a consultant pursuant to the Consulting Agreement.

           (ii) The Repurchase Option provided in this Section 2 is assignable 
by the Company in whole or in part to the holders of the Company's Preferred
Stock or other securities issued by the Company to investors (herein the
"Investors"). If the Company should decide not to exercise the Repurchase Option
or not to exercise the Repurchase Option for all Option Shares, it shall give
the Investors (or the Investor if at the time there is only one Investor) the
right to purchase all of the Option Shares or all of the remaining Option
Shares, as the case may be, then subject to the Repurchase Option or such lesser
portion thereof as may be selected by the Investors. Within 30 days after the
Section 2(b) Event, the Company shall notify each Investor in writing thereof
and the number of Option Shares remaining subject to the Repurchase Option. If
within 30 days after the Company gives its aforesaid notice, one or more of the
Investors do not notify the Company that they desire to purchase all of such
Option Shares, the Repurchase Option

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

     [*] Confidential Treatment Requested.

                                      -2-
<PAGE>   50
shall expire. If the Investors oversubscribe for such Option Shares, each
Investor who notifies the Company that it desires to purchase Option Shares
shall have a right to purchase a pro rata portion of such Option Shares based on
the percentage of Common Stock and Preferred Stock then owned by it or which may
be acquired upon exercise of any outstanding convertible notes, warrants,
options or other securities, on a fully diluted as if converted to Common Stock
basis, bears to the number of shares of Common Stock and Preferred Stock then
owned by all Investors who notify the Company of their desire to purchase any of
such Option Shares or which may be acquired upon exercise of any outstanding
convertible notes, warrants, options or other securities, on a fully diluted as
if converted to Common Stock basis. The Company shall promptly advise each
Investor of the amount of such Option Shares it is entitled to purchase as a
result of such allocation.

        (c) The Repurchase Option shall be exercised by written notice or
notices signed by an officer of the Company or the purchasing Investors, as the
case may be, and delivered or mailed as provided in Section 12.1 hereof. The
Unvested Option Price shall be payable, at the option of the Company or the
purchasing Investors, as the case may be, in cancellation of all or a portion of
any outstanding indebtedness of the Company or the purchasing Investors, as the
case may be, to the Buyer or in cash (by check) or both. The provisions of this
Section 2(c) shall survive any termination of this Agreement.

        (d) Nothing in this Agreement shall affect in any manner whatsoever the
right or power of the Company, or a parent or subsidiary of the Company, to
terminate the Buyer's engagement, for any reason, with or without cause.

        (e) The Buyer shall not sell, assign or otherwise transfer any of the
Option Shares or any interest therein, or grant or otherwise allow to exist any
lien, claim or other encumbrance on or with respect to any of the Option Shares
then subject to the Repurchase Option.

3.      REPRESENTATIONS AND WARRANTIES

        To induce the Company to deliver the Shares to the Buyer, the Buyer
represents and warrants to the Company:

               (a) The Buyer is acquiring the Shares for his own account as
principal, for investment purposes only, and not with a view to, or for, resale
or distribution, and no other person has a direct or indirect beneficial
interest in the Shares;

               (b) The Buyer has not offered any of the Shares for resale and
has no present intention of dividing his interest with others or of reselling or
otherwise disposing of any of the Shares;

                                      -3-
<PAGE>   51
               (c) Any information the Buyer has furnished to the Company with
respect to the Buyer's status as a sophisticated or accredited investor, his
business experience or financial position is correct;

               (d) The financial capacity of the Buyer is such that the
investment in the Shares is not material to his total financial capacity; the
Buyer has the financial ability to bear the economic risk of his investment, has
adequate means for providing for his current needs and personal contingencies
and has no need for liquidity with respect to his investment in the Shares;

               (e) The Buyer considers himself to be a sophisticated investor
and has such knowledge and experience in financial and business matters as to be
capable of evaluating the merits and risks of the prospective investment in the
Shares;

               (f) The Buyer has been furnished with all information concerning
the Shares and the Company that he desires;

               (g) The Buyer has been given the opportunity to ask questions of,
and receive answers from, the Company with respect to the Shares, concerning the
terms and conditions of the offering and other matters pertaining to this
investment, and has been given the opportunity to obtain such additional
information necessary to verify the accuracy of the information provided to him
by the Company in order for him to evaluate the merits and risks of investment
in the Shares to the extent that the Company possessed such information or could
acquire it without unreasonable effort or expense; and

               (h) The Buyer is not relying on the Company with respect to any
economic considerations of the Buyer related to this investment. In regard to
the economic considerations related to this investment, the Buyer has relied on
the advice of, or has consulted with, only his own advisors.

        The Buyer further represents, warrants and agrees that he will not sell
or otherwise transfer the Shares without registration under the Securities Act
of 1933, as amended (the "Act"), or an exemption therefrom, and fully
understands and agrees that he must bear the economic risk of his purchase for
an indefinite period of time because, among other reasons, the Shares have not
been registered under the Act or under the securities laws of any state and,
therefore, cannot be resold, pledged, assigned or otherwise disposed of unless
they are subsequently registered under the Act and under the applicable
securities laws of such states or an exemption from such registration is
available. He also understands that the Company is under no obligation to
register the Shares on his behalf or to assist him in complying with any
exemption from registration under the Act. He further understands that any
certificate evidencing the Shares will bear a legend restricting the transfer
thereof consistent with the foregoing and that a notation may be made in the
records of the Company restricting the transfer of any Shares in a manner
consistent with the foregoing.

                                      -4-
<PAGE>   52
4.      BUYER AWARENESS

        The Buyer acknowledges that he is aware that:

               (a) No federal or state agency has passed upon the Shares or made
any finding or determination as to the fairness of this investment;

               (b) There are substantial risks of loss of investment incident to
an investment in the Shares and such an investment is highly speculative;

               (c) The Company is only recently organized, has not conducted any
substantial business to date and does not have any substantial working capital
or financial resources. The business in which the Company proposes to engage is
highly competitive and success in the Company's business may depend on, among
other things, the Company's ability to obtain financing, to complete product
development, to attract qualified employees and to obtain patent protection and
governmental approvals, market acceptance of products and numerous other factors
over which the Company does not have control.

5.      RESTRICTIONS ON TRANSFER; RIGHT OF FIRST REFUSAL

        5.1    COMPANY'S PURCHASE OPTION

        Buyer shall not sell, transfer, pledge, hypothecate or otherwise dispose
of any Shares which are purchased hereunder without first complying with the
terms of this Section 5.

        5.2    RIGHT OF FIRST REFUSAL

        Before any of the Shares registered in the name of Buyer that are not
subject to the Repurchase Option may be sold or transferred (including transfer
by operation of law), except as permitted in Section 6, such Shares shall first
be offered to the Company and to the Investors, in accordance with the terms set
out herein, provided, however, that until the Company has completed a public
offering of its equity securities pursuant to an effective registration
statement filed with the Securities and Exchange Commission, no transfer of the
Shares may be made under any circumstances.

               (i) Buyer shall deliver a notice ("Notice") to the Company and to
the Investors stating (A) his bona fide intention to sell or transfer such
Shares, (B) the number of such Shares to be sold or transferred, (C) the price
for which he proposes to sell or transfer such Shares, and (D) the name of the
proposed purchaser or transferee.

              (ii) Within thirty (30) days after receipt of the Notice, the
Company and/or the Investors may elect to purchase some or all of the Shares to
which the Notice refers, at the price per share specified in the Notice. The
closing for such purchase by the

                                      -5-
<PAGE>   53
Company and/or the Investors shall occur, unless otherwise agreed by the
Company, the Investors electing to purchase Shares, and the Buyer, no later than
30 days after the election by the Company and/or the Investors to purchase same.
In the event that the number of Shares which the Company and the Investors
desire to purchase exceeds the number of Shares proposed for sale by Buyer in
the Notice, then in such instance the Company shall have full preference to
acquire such Shares to the exclusion of the Investors, and, to the extent that
there are Shares still available for purchase by the Investors, the Investors
desiring to purchase Shares shall be entitled to purchase the remaining amount
thereof on a pro rata basis based upon the number of shares of Common Stock and
Preferred Stock, or securities convertible into shares of Common Stock and
Preferred Stock, then held by each of them so electing to purchase bears to the
total number of shares of Common Stock and Preferred Stock, or securities
convertible into shares of Common Stock and Preferred Stock, held by all
Investors desiring to acquire Shares, on a fully diluted as if converted to
Common Stock basis.

             (iii) If all of the Shares to which the Notice refers are not
purchased by the Company and the Investors, as provided in Section 5.2(ii)
hereof, Buyer may sell such Shares which the Company and the Investors elected
not to purchase to any person or persons named in the Notice at the price
specified in the Notice or at a higher price, provided that such sale or
transfer is consummated within 120 days of the date of said Notice to the
Company and the Investors, and provided, further, that any such sale is in
accordance with all the terms and conditions hereof.

              (iv) Upon the closing of a firm commitment public offering
pursuant to an effective registration statement filed by the Company under the
Securities Act of 1933, as amended (the "Act"), covering the offering and sale
of shares of Common Stock for the account of the Company in which the aggregate
gross proceeds received by the Company equal or exceed $7,500,000 and in which
the public offering price per share equals or exceeds $5.00 per share, the
thirty (30) day period specified in Section 5.2(ii) above shall be reduced to a
ten (10) day period; and the requirement to identify the name of the proposed
purchaser and the proposed price shall be inapplicable if the Buyer proposed to
sell the Shares in an over-the-counter sale or on a national or regional
exchange transaction. In such instance, any such sale to the Company and/or the
Investors shall be at the average closing price of the Company's Common Stock on
the date of notice of election to purchase such shares by the Company and/or the
Investors. The average closing price is defined as the last closing price
regular way on the exchange where the Common Stock is listed for trading or the
average of the bid and ask prices if applicable.

        5.3    STANDOFF AGREEMENT

        Buyer agrees, in connection with each of the Company's public offerings
of its equity securities, and upon request of the Company or the underwriters
managing such offering, not to sell, make any short sale of, loan, grant any
option for the purchase of or 

                                      -6-
<PAGE>   54
otherwise dispose of any of the Shares (other than those included in the
registration, if any) without the prior written consent of the Company or such
underwriters, as the case may be, for such period of time from the effective
date of such registration as may be requested by the Company or such
underwriters; provided, that the officers and directors of the Company who own
stock of the Company also agree to such restrictions.

        5.4    OTHER RESTRICTIONS ON TRANSFER

        The Company shall not be required (i) to transfer on its books any of
the Shares which shall have been sold or transferred in violation of any of the
provisions set forth in this Agreement or (ii) to treat as owner of such Shares
or to accord the right to vote as such owner or to pay dividends to any
transferee to whom such Shares shall have been so transferred.

6.      EXEMPT TRANSACTIONS

        6.1    CERTAIN TRANSACTIONS

        The prohibition in Section 5 against the sale of the Shares shall not
apply to the exchange of Shares pursuant to a plan or merger, consolidation,
recapitalization, reorganization, or sale of the Company, in which the Company
is the surviving entity, but any stock or securities received in exchange
therefor shall also become subject to this Agreement.

        6.2    PERMITTED TRANSFERS

        The prohibition in Section 5 against the sale of Shares shall not apply
to a transfer by Buyer of all or part of his Shares during his lifetime or on
death by will or by intestacy to or for the benefit of himself, his spouse, his
ancestors or his lineal descendants, provided that any such transferee or
transferees shall receive and hold the Shares subject to the terms of this
Agreement, and there shall be no further transfer of such Shares except in
accordance with the terms of this Agreement.

7.      ASSIGNMENT

        The Company may assign this Agreement or any of its rights and
obligations hereunder. The Buyer may not assign this Agreement or any of his
rights and obligations hereunder. All covenants and agreements of, and benefits
for, the Investors contained in this Agreement shall inure to the benefit of
their respective successors and assigns and be binding on the Company and its
successors and on the Buyer and his heirs, executors, administrators and
successors. All such covenants and agreements are fully assignable by the
Investors, provided, however, that any assignment of any of its rights under
this Agreement by any Investor (other than to partners of such Investor or
successors of such Investor or such partners by operation of law) shall be made
only in connection with the 

                                      -7-
<PAGE>   55
sale or other transfer of all or any portion of the Preferred Stock, Common
Stock, convertible notes, warrants, options or other securities of the Company
which are exchangeable or convertible into shares of Common Stock or Preferred
Stock of the Company held by such Investor and such assignee or transferee shall
execute this Agreement.

8.      ADJUSTMENTS

        If, from time to time during the term of this Agreement (i) there is any
stock dividend or liquidating dividend of cash or property, stock split or other
change in the character or amount of any of the outstanding securities of the
Company, or (ii) there is any transaction involving the consolidation, merge or
sale of all, or substantially all, of the assets of the Company, then, in such
event, (x) any and all new, substituted or additional securities or other
property to which the Buyer is entitled by reason of his ownership of the Shares
shall be immediately subject to right of first refusal provided to the Company
and the Investors as described in Section 5 hereof and to the Repurchase Option
and be included in the term "Option Shares" for all purposes of the Repurchase
Option with the same force and effect as the Option Shares subject to the
Repurchase Option under the terms of Section 2 hereof and (y) all Shares
purchased by Buyer hereunder shall be treated on the same basis as all other
outstanding shares of Common Stock of the Company so that Buyer's Shares shall
not be diluted by any such event any differently than any other holder of Common
Stock of the Company. While the total Unvested Option Price shall remain the
same after each such event, the Unvested Option Price per Option Share upon
exercise of the Repurchase Option shall be appropriately adjusted.

9.      LEGENDS

        All certificates representing any of the Shares subject to the
provisions of this Agreement shall have endorsed thereon a legend substantially
as follows:

                      "ANY DISPOSITION, GRANT OR OTHER TRANSFER OF ANY INTEREST
               IN THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS SUBJECT TO
               CERTAIN RESTRICTIONS, AND THE SECURITIES REPRESENTED BY THIS
               CERTIFICATE ARE SUBJECT TO A RIGHT OF REPURCHASE AND RIGHT OF
               FIRST REFUSAL, CONTAINED IN A CERTAIN AGREEMENT BY THE
               RECORDHOLDER HEREOF AND THE CORPORATION, A COPY OF WHICH WILL BE
               MAILED TO ANY HOLDER OF THIS CERTIFICATE WITHOUT CHARGE AFTER
               RECEIPT BY THE CORPORATION OF A WRITTEN REQUEST THEREFOR."

                                      -8-
<PAGE>   56
        Upon presentation to the Company or any authorized transfer agent, the
certificates representing the Shares or any appropriate portion thereof shall be
exchanged for certificates not bearing such legend if the certificates are
presented after the termination of this Agreement.

10.     RIGHTS AS A STOCKHOLDER; VOTING AGREEMENT

        Subject to the provisions of Sections 2 and 5 above, the Buyer shall,
during the term of this Agreement, exercise all rights and privileges of a
stockholder of the Company with respect to the Shares, including the right to
vote such Shares at any stockholder meeting. Notwithstanding anything herein to
the contrary, Buyer hereby agrees that he will, for a ninety-day period
following the issuance of the Shares or until the closing of the first round
financing by the Company in an amount at least equal to $2,000,000, whichever
comes first, vote such Shares, at any stockholder meeting, in person, by proxy,
by written consent, or otherwise, for the directors nominated for election to
the Board of Directors of the Company by The Woodlands Venture Fund and no
others, and, in any other matter coming before the stockholders of the Company,
in accordance with the directive of The Woodlands Venture Fund.

        In order to secure the obligation to vote in accordance with the
provisions hereof, the Buyer hereby appoints Martin P. Sutter as his true and
lawful proxy and attorney, with full power of substitution, to vote all of his
Shares for the matters specified hereinabove. The irrevocable proxy granted by
the Buyer may be exercised at any time Buyer fails to comply with the terms of
this Section 10. The proxy and power granted by the Buyer pursuant to this
section are coupled with an interest and are given to secure the duties of the
Buyer pursuant hereto. Such proxy will be irrevocable and will survive the
death, incompetency, and disability of Buyer, provided that it shall terminate
upon the expiration of twelve months following the issuance of the Shares.

        Buyer hereby consents to the placement of an appropriate legend
evidencing the voting restrictions provided for in this Agreement, on the
certificates representing the Shares and any certificates issued in replacement
or exchange therefor, and Buyer will take all actions reasonably requested by
the Company to effect such placement.

11.     TERMINATION

        Except as may be otherwise provided herein, this Agreement shall
terminate on the 91st calendar day immediately succeeding the third anniversary
of the public offering referenced in Section 5.2.

                                      -9-
<PAGE>   57
12.     MISCELLANEOUS

        12.1   NOTICE

        For purposes of this Agreement, notices and all other communications
provided for herein shall be in writing and shall be deemed to have been duly
given when personally delivered or when mailed by United States registered or
certified mail, return receipt requested, postage prepaid, addressed as follows:

        If to the Company:

               RGene Therapeutics, Inc.
               c/o The Woodlands Venture Fund
               2170 Buckthorne Place, Suite 170
               The Woodlands, Texas 77380
               Attention:  Martin P. Sutter

        If to the Buyer, at the address identified on the signature page hereof,
and if to an Investor, at the address identified on the records of the Company
hereto, or to such other address as either party or an Investor may furnish to
the other in writing in accordance herewith, except that notices of change of
address shall be effective only upon receipt.

        12.2   APPLICABLE LAW

        The substantive laws of the State of Texas, excluding any law, rule or
principle which might refer to the substantive law of another jurisdiction, will
govern the interpretation, validity and effect of this Agreement without regard
to the place of execution or the place for performance thereof. This Agreement
is to be at least partially negotiated, executed and performed in Harris County,
Texas, and, as such, the Company and the Buyer agree that personal jurisdiction
and venue shall be proper with the state or federal courts situated in Harris
County, Texas, to hear such disputes arising under this Agreement.

        12.3   NO WAIVER

        No failure by either party hereto at any time to give notice of any
breach by the other party of, or to require compliance with, any condition or
provision of this Agreement shall be deemed a waiver of similar or dissimilar
provisions or conditions at the same or at any prior or subsequent time.

        12.4   SEVERABILITY

        If a court of competent jurisdiction determined that any provision of
this Agreement, including any appendices attached hereto, is invalid or
unenforceable, then the invalidity or unenforceability of that provision shall
not affect the validity or 

                                      -10-
<PAGE>   58
enforceability of any other provision of this Agreement, and all other
provisions shall remain in full force and effect. Further, such provision shall
be reformed and construed to the extent permitted by law so that it may be
valid, legal and enforceable to the maximum extent possible.

        12.5   COUNTERPARTS

        This Agreement may be executed in one or more counterparts, each of
which shall be deemed to be an original, but all of which together will
constitute one and the same Agreement.

        12.6   HEADINGS

        The section headings have been inserted for purposes of convenience and
shall not be used for interpretive purposes.

        12.7   SUCCESSORS; THIRD PARTY BENEFICIARY

        This Agreement shall inure to the benefit of the successors and assigns
of the Company and the Investors and be binding upon the Buyer and his heirs,
executors, administrators and successors. The Buyer agrees that any and all
Investors in the Company shall be treated as third party beneficiaries of this
Agreement without the necessity of execution of this Agreement, and shall be
entitled to all of the rights accorded to them herein.

        12.8   ENTIRE AGREEMENT

        This Agreement constitutes the entire agreement of the parties with
regard to the subject matter hereof, and contains all the covenants, promises,
representations, warranties and agreements between the parties with respect to
the subject matter hereof. Each party to this Agreement acknowledges that no
representation, inducement, promise or agreement, oral or written, with regard
to the subject matter hereof, has been made by either party, or by anyone acting
on behalf of either party, which is not embodied herein, and that no agreement,
statement or promise relating to the subject matter hereof which is not
contained in this Agreement or in such other agreements shall be valid and
binding.

        12.9   AMENDMENTS

        No amendment or modification to this Agreement will be effective unless
it is in writing and signed by the Company, the Buyer and, if such amendment
alters or amends any of the rights of the Investors, by Investors holding a
majority of the outstanding shares of capital stock of the Company held by such
Investors, if any.

                                      -11-
<PAGE>   59
        12.10  INDEMNITY

        The Buyer agrees to indemnify and hold harmless the Company and any
person, if any, who controls the Company or such successor within the meaning of
Section 15 of the Act against any and all loss, liability, claim, damage and
expense whatsoever (including, but not limited to, any and all expenses
whatsoever reasonably incurred in investigating, preparing or defending against
any litigation commenced or threatened or any claim whatsoever) arising out of
or based upon any false representation or warranty or breach or failure by the
Buyer to comply with any covenant or agreement made by the Buyer herein or in
any other document furnished by the Buyer in connection with this transaction.

        12.11  INJUNCTIVE RELIEF

        In view of the inadequacy of money damages, and in view of the fact that
the stock of the Company cannot be readily purchased or sold in the general
market, if the Buyer or any other person shall fail to comply with any provision
of this Agreement, the Company shall be entitled, to the extent permissible by
law, to injunctive relief in the case of the violation, or attempted or
threatened violation, by Buyer or other person of any such provision, or to a
decree compelling specific performance by the Buyer or other person, of any such
provision, or to any other remedies legally available.

        12.12  SPOUSES

        The spouse of the Buyer, if any, hereby represents and acknowledges that
he or she is fully aware of, understands, and fully consents and agrees to the
provisions of this Agreement and its binding effect upon any community property
interest he or she may now or hereafter own. Said spouse agrees that the
termination of their marital relationship with the Buyer for any reason or his
or her death shall not have the effect of removing any stock of the Company
otherwise subject to this Agreement from its coverage. Said spouse's awareness,
understanding, consent and agreement is evidenced by the execution of this
Agreement. All stock described in this Agreement shall include the community
property interest of the spouse of Buyer.

        12.13  VOID TRANSFERS

        If any Stock shall be sold or transferred otherwise than in accordance
with the terms and conditions of this Agreement, such sale shall be void. Any
such attempted sale or other transfer shall create a right in the Company to
purchase the Stock which is the subject of such purported transfer at the
applicable purchase price specified herein. Such right shall constitute an
"adverse claim" within the meaning of such term as used within the meaning of
the Uniform Commercial Code of any State. In addition to, and without prejudice
to, any and all other rights or remedies which may be available to the Company,
the Buyer agrees that the Company may, but shall have no obligation to, hold and
refuse 

                                      -12-
<PAGE>   60


to transfer any Stock, or any certificate therefor, tendered to it for
transfer if the transfer violates the provisions of the Agreement.

        12.14  TAX REPRESENTATIONS

        The Buyer acknowledges that the Company has made no warranties or other
representations to Buyer with respect to the income tax consequences of the
transactions contemplated by this Agreement and Buyer is in no manner relying on
the Company or its representatives for an account of such tax consequences.

        12.15  FURTHER ASSURANCES

        The parties agree to execute such further instruments and to take such
further action as may reasonably be necessary to carry out the intent of this
Agreement.

                                      -13-
<PAGE>   61
     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
and delivered as of the day and year first above written.

                                     Company

                                            RGENE THERAPEUTICS, INC.

                                            By:    /s/ MARTIN P. SUTTER
                                                   -----------------------------
                                            Name:  Martin P. Sutter
                                                   -----------------------------
                                            Title: Chairman
                                                   -----------------------------


Buyer's Spouse                              Buyer

Signed:     /s/ KING LAN C. HUNG            Signed:     /s/ HIEN-CHIE HUNG
            ------------------------                    ------------------------
Print Name: King Lan C. Hung                Print Name: Hien-Chie Hung
            ------------------------                    ------------------------
Address:    5762 Birdwood R.                Address:    5762 Birdwood Rd.
            ------------------------                    ------------------------
            Houston, Texas  77096                       Houston, Texas  77096
- ------------------------------------        ------------------------------------
- ------------------------------------        ------------------------------------
- ------------------------------------        ------------------------------------

                                      -14-
<PAGE>   62
                                                                       EXHIBIT 4



                            RGENE THERAPEUTICS, INC.

                              STOCKHOLDER AGREEMENT

        This Stockholder Agreement (this "Agreement") dated March __, 1994 is
entered into by and between RGene Therapeutics, Inc., a Delaware corporation
(the "Company"), and Board of Regents of the University of Texas System, an
agency of the State of Texas ("Stockholder").

                                   WITNESSETH:

        WHEREAS, the Company desires to issue certain shares of common stock,
$.001 par value, of the Company (the "Common Stock") to the Stockholder; and

        WHEREAS, the Stockholder desires to acquire certain shares of Common
Stock from the Company; and

        WHEREAS, the Stockholder and the Company desire that the Stockholder
grant to the Company, and under certain circumstances to holders of the
Company's Preferred Stock or other securities issued by the Company to investors
(the "Investors"), options to repurchase certain shares of Common Stock
purchased by the Stockholder on the terms and conditions set forth;

        NOW, THEREFORE, for and in consideration of the mutual promises,
covenants and obligations contained herein, the parties agree as follows:

1.      ISSUANCE OF SHARES

        1.1    PURCHASE AND SALE OF SHARES

        Subject to the terms and conditions of this Agreement and in
consideration of the execution of the Patent and Technology License Agreement
between the Company and the Stockholder dated the date hereof relating to
certain patent applications and technology owned by Stockholder and invented by
Dr. Mien Chie Hung, Ph.D., the Company agrees to issue to the Stockholder
[ * ] shares of Common Stock (the "Shares").




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

        [*] Confidential Treatment Requested.
<PAGE>   63
        1.2    CLOSING

        The closing for the issuance of the Shares to the Stockholder shall
occur on or before March __, 1994, or at such other date and time as the parties
may agree (the "Closing"). At the Closing, or within a reasonable time
thereafter, the Company shall deliver to Stockholder a certificate or
certificates representing the number of Shares as set forth in Section 1.1
hereof, in the name of the Stockholder.

2.      REPRESENTATIONS AND WARRANTIES

        To induce the Company to deliver the Shares to the Stockholder, the
Stockholder represents and warrants to the Company:

               (a) The Stockholder is acquiring the Shares for its own account
as principal, for investment purposes only, and not with a view to, or for,
resale or distribution, and no other person or entity has a direct or indirect
beneficial interest in the Shares;

               (b) The Stockholder has not offered any of the Shares for resale
and has no present intention of dividing its interest with others or of
reselling or otherwise disposing of any of the Shares;

               (c) Any information the Stockholder has furnished to the Company
with respect to the Stockholder's status as a sophisticated or accredited
investor, its business experience or financial position is correct;

               (d) The financial capacity of the Stockholder is such that the
investment in the Shares is not material to its total financial capacity; the
Stockholder has the financial ability to bear the economic risk of its
investment, has adequate means for providing for its current needs and personal
contingencies and has no need for liquidity with respect to its investment in
the Shares;

               (e) The Stockholder considers itself to be a sophisticated
investor and has such knowledge and experience in financial and business matters
as to be capable of evaluating the merits and risks of the prospective
investment in the Shares;

               (f) The Stockholder has been furnished with all information
concerning the Shares and the Company that it desires;

               (g) The Stockholder has been given the opportunity to ask
questions of, and receive answers from, the Company with respect to the Shares,
concerning the terms and conditions of the offering and other matters pertaining
to this investment, and has been given the opportunity to obtain such additional
information necessary to verify the accuracy of the information provided to him
by the Company in order for him to evaluate 



                                      -2-
<PAGE>   64
the merits and risks of investment in the Shares to the extent that the Company
possessed such information or could acquire it without unreasonable effort or
expense; and

               (h) The Stockholder is not relying on the Company with respect to
any economic considerations of the Stockholder related to this investment. In
regard to the economic considerations related to this investment, the
Stockholder has relied on the advice of, or has consulted with, only its own
advisors.

        The Stockholder further represents, warrants and agrees that it will not
sell or otherwise transfer the Shares without registration under the Securities
Act of 1933, as amended (the "Act"), or an exemption therefrom, and fully
understands and agrees that it must bear the economic risk of its purchase for
an indefinite period of time because, among other reasons, the Shares have not
been registered under the Act or under the securities laws of any state and,
therefore, cannot be resold, pledged, assigned or otherwise disposed of unless
they are subsequently registered under the Act and under the applicable
securities laws of such states or an exemption from such registration is
available. It also understands that the Company is under no obligation to
register the Shares on its behalf or to assist him in complying with any
exemption from registration under the Act. It further understands that any
certificate evidencing the Shares will bear a legend restricting the transfer
thereof consistent with the foregoing and that a notation may be made in the
records of the Company restricting the transfer of any Shares in a manner
consistent with the foregoing.

3.      STOCKHOLDER AWARENESS

        The Stockholder acknowledges that it is aware that:

               (a) No federal or state agency has passed upon the Shares or made
any finding or determination as to the fairness of this investment;

               (b) There are substantial risks of loss of investment incident to
an investment in the Shares and such an investment is highly speculative;

               (c) The Company is only recently organized, has not conducted any
substantial business to date and does not have any substantial working capital
or financial resources. The business in which the Company proposes to engage is
highly competitive and success in the Company's business may depend on, among
other things, the Company's ability to obtain financing, to complete product
development, to attract qualified employees and to obtain patent protection and
governmental approvals, market acceptance of products and numerous other factors
over which the Company does not have control.




                                      -3-
<PAGE>   65

4.      RESTRICTIONS ON TRANSFER; RIGHT OF FIRST REFUSAL

        4.1    COMPANY'S PURCHASE OPTION

        Stockholder shall not sell, transfer, pledge, hypothecate or otherwise
dispose of any Shares which are purchased hereunder without first complying with
the terms of this Section 4.

        4.2    RIGHT OF FIRST REFUSAL

        Before any of the Shares registered in the name of Stockholder may be
sold or transferred (including transfer by operation of law), except as
permitted in Section 5, such Shares shall first be offered to the Company and to
the Investors, in accordance with the terms set out herein.

               (i) Stockholder shall deliver a notice ("Notice") to the Company
and to the Investors stating (A) its bona fide intention to sell or transfer
such Shares, (B) the number of such Shares to be sold or transferred, (C) the
price for which it proposes to sell or transfer such Shares, and (D) the name of
the proposed purchaser or transferee.

              (ii) Within thirty (30) days after receipt of the Notice, the
Company and/or the Investors may elect to purchase some or all of the Shares to
which the Notice refers, at the price per share specified in the Notice. The
closing for such purchase by the Company and/or the Investors shall occur,
unless otherwise agreed by the Company, the Investors electing to purchase
Shares, and the Stockholder, no later than 30 days after the election by the
Company and/or the Investors to purchase same. In the event that the number of
Shares which the Company and the Investors desire to purchase exceeds the number
of Shares proposed for sale by Stockholder in the Notice, then in such instance
the Company shall have full preference to acquire such Shares to the exclusion
of the Investors, and, to the extent that there are Shares still available for
purchase by the Investors, the Investors desiring to purchase Shares shall be
entitled to purchase the remaining amount thereof on a pro rata basis based upon
the number of shares of Common Stock and Preferred Stock, or securities
convertible into shares of Common Stock and Preferred Stock, then held by each
of them so electing to purchase bears to the total number of shares of Common
Stock and Preferred Stock, or securities convertible into shares of Common Stock
and Preferred Stock, held by all Investors desiring to acquire Shares, on a
fully diluted as if converted to Common Stock basis.

             (iii) If all of the Shares to which the Notice refers are not
purchased by the Company and the Investors, as provided in Section 4.2(ii)
hereof, Stockholder may sell such Shares which the Company and the Investors
elected not to purchase to any person or persons named in the Notice at the
price specified in the Notice or at a higher price, provided that such sale or
transfer is consummated within 120 days of the date of 



                                      -4-
<PAGE>   66
said Notice to the Company and the Investors, and provided, further, that any
such sale is in accordance with all the terms and conditions hereof.

              (iv) Upon the closing of a firm commitment public offering
pursuant to an effective registration statement filed by the Company under the
Securities Act of 1933, as amended (the "Act"), covering the offering and sale
of shares of Common Stock for the account of the Company in which the aggregate
gross proceeds received by the Company equal or exceed $7,500,000 and in which
the public offering price per share equals or exceeds $5.00 per share, the
thirty (30) day period specified in Section 4.2(ii) above shall be reduced to a
ten (10) day period; and the requirement to identify the name of the proposed
purchaser and the proposed price shall be inapplicable if the Stockholder
proposed to sell the Shares in an over-the-counter sale or on a national or
regional exchange transaction. In such instance, any such sale to the Company
and/or the Investors shall be at the average closing price of the Company's
Common Stock on the date of notice of election to purchase such shares by the
Company and/or the Investors. The average closing price is defined as the last
closing price regular way on the exchange where the Common Stock is listed for
trading or the average of the bid and ask prices if applicable.

        4.3    STANDOFF AGREEMENT

        Stockholder agrees, in connection with each of the Company's public
offerings of its equity securities, and upon request of the Company or the
underwriters managing such offering, not to sell, make any short sale of, loan,
grant any option for the purchase of or otherwise dispose of any of the Shares
(other than those included in the registration, if any) without the prior
written consent of the Company or such underwriters, as the case may be, for
such period of time from the effective date of such registration as may be
requested by the Company or such underwriters; provided, that the officers and
directors of the Company who own stock of the Company also agree to such
restrictions.

        4.4    OTHER RESTRICTIONS ON TRANSFER

        The Company shall not be required (i) to transfer on its books any of
the Shares which shall have been sold or transferred in violation of any of the
provisions set forth in this Agreement or (ii) to treat as owner of such Shares
or to accord the right to vote as such owner or to pay dividends to any
transferee to whom such Shares shall have been so transferred.

5.      EXEMPT TRANSACTIONS

        The prohibition in Section 4 against the sale of the Shares shall not
apply to the exchange of Shares pursuant to a plan or merger, consolidation,
recapitalization, reorganization, or sale of the Stockholder in which the
Stockholder is the surviving entity, 



                                      -5-
<PAGE>   67
but any stock or securities received in exchange therefor shall also become
subject to this Agreement.

6.      ASSIGNMENT

        The Company may assign this Agreement or any of its rights and
obligations hereunder. The Stockholder may not assign this Agreement or any of
its rights and obligations hereunder. All covenants and agreements of, and
benefits for, the Investors contained in this Agreement shall inure to the
benefit of their respective successors and assigns and be binding on the Company
and its successors and on the Stockholder and its successors and assigns. All
such covenants and agreements are fully assignable by the investors, provided,
however, that any assignment of any of its rights under this Agreement by any
Investor (other than to partners of such Investor or successors of such Investor
or such partners by operation of law) shall be made only in connection with the
sale or other transfer of all or any portion of the Preferred Stock, Common
Stock, convertible notes, warrants, options or other securities of the Company
which are exchangeable or convertible into shares of Common Stock or Preferred
Stock of the Company held by such Investor and such assignee or transferee shall
execute this Agreement.

7.      ADJUSTMENTS

        If, from time to time during the term of this Agreement (i) there is any
stock dividend or liquidating dividend of cash or property, stock split or other
change in the character or amount of any of the outstanding securities of the
Company or (ii) there is any transaction involving the consolidation, merger or
sale of all, or substantially all, of the assets of the Company, then, in such
event, (x) any and all new, substituted or additional securities or other
property to which the Stockholder is entitled by reason of its ownership of the
Shares shall be immediately subject to right of first refusal provided to the
Company and the Investors as described in Section 4 hereof and (y) all Shares
purchased by Stockholder hereunder shall be treated on the same basis as all
other outstanding shares of Common Stock of the Company so that Stockholder's
Shares shall not be diluted by any such event any differently than any other
holder of Common Stock of the Company.

8.      LEGENDS

        All certificates representing any of the Shares subject to the
provisions of this Agreement shall have endorsed thereon a legend substantially
as follows:

                      "ANY DISPOSITION, GRANT OR OTHER TRANSFER OF ANY INTEREST
               IN THE SECURITIES REPRESENTED BY THIS CERTIFICATE IS SUBJECT TO
               CERTAIN RESTRICTIONS, AND THE SECURITIES REPRESENTED BY THIS


                                      -6-
<PAGE>   68
               CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL, CONTAINED IN
               A CERTAIN AGREEMENT BY THE RECORDHOLDER HEREOF AND THE
               CORPORATION, A COPY OF WHICH WILL BE MAILED TO ANY HOLDER OF THIS
               CERTIFICATE WITHOUT CHARGE AFTER RECEIPT BY THE CORPORATION OF A
               WRITTEN REQUEST THEREFOR."

        Upon presentation to the Company or any authorized transfer agent, the
certificates representing the Shares or any appropriate portion thereof shall be
exchanged for certificates not bearing such legend if the certificates are
presented after the termination of this Agreement.

9.      RIGHTS AS A STOCKHOLDER; VOTING AGREEMENT

        (a) Subject to the provisions of Section 4 above, the Stockholder shall,
during the term of this Agreement, exercise all rights and privileges of a
stockholder of the Company with respect to the Shares, including the right to
vote such Shares at any stockholder meeting. Notwithstanding anything herein to
the contrary, Stockholder hereby agrees that it will, for a ninety-day period
following the issuance of the Shares or until the closing of the first round
financing by the Company in an amount at least equal to $2,000,000, whichever
comes first, vote such Shares, at any stockholder meeting, in person, by proxy,
by written consent, or otherwise, for the directors nominated for election to
the Board of Directors of the Company by The Woodlands Venture Fund and no
others, and, in any other matter coming before the stockholders of the Company,
in accordance with the directive of The Woodlands Venture Fund.

        In order to secure the obligation to vote in accordance with the
provisions hereof, the Stockholder hereby appoints Martin P. Sutter as its true
and lawful proxy and attorney, with full power of substitution, to vote all of
its Shares for the matters specified hereinabove. The irrevocable proxy granted
by the Stockholder may be exercised at any time Stockholder fails to comply with
the terms of this Section 9. The proxy and power granted by the Stockholder
pursuant to this section are coupled with an interest and are given to secure
the duties of the Stockholder pursuant hereto. Such proxy will be irrevocable
and will survive the death, incompetency, and disability of Stockholder,
provided that it shall terminate upon the expiration of ninety days following
the issuance of the Shares or until the above-referenced closing, if earlier.

        Stockholder hereby consents to the placement of an appropriate legend
evidencing the voting restrictions provided for in this Agreement, on the
certificates representing the Shares and any certificates issued in replacement
or exchange therefor, and Stockholder will take all actions reasonably requested
by the Company to effect such placement.



                                      -7-
<PAGE>   69
10.     TERMINATION

        Except as may be otherwise provided herein, this Agreement shall
terminate on the 91st calendar day immediately succeeding the third anniversary
of the public offering referenced in Section 4.2.

11.     MISCELLANEOUS

        11.1   NOTICE

        For purposes of this Agreement, notices and all other communications
provided for herein shall be in writing and shall be deemed to have been duly
given when personally delivered or when mailed by United States registered or
certified mail, return receipt requested, postage prepaid, addressed as follows:

               If to the Company:

               RGene Therapeutics, Inc.
               c/o The Woodlands Venture Fund
               2170 Buckthorne Place, Suite 170
               The Woodlands, Texas  77380
               Attention:  Martin P. Sutter

        If to the Stockholder, at the address identified on the signature page
hereof, and if to an Investor, at the address identified on the records of the
Company hereto, or to such other address as either party or an Investor may
furnish to the other in writing in accordance herewith, except that notices of
change of address shall be effective only upon receipt.

        11.2   APPLICABLE LAW

        The substantive laws of the State of Texas, excluding any law, rule or
principle which might refer to the substantive law of another jurisdiction, will
govern the interpretation, validity and effect of this Agreement without regard
to the place of execution or the place for performance thereof. This Agreement
is to be at least partially negotiated, executed and performed in Harris County,
Texas, and, as such, the Company and the Stockholder agree that personal
jurisdiction and venue shall be proper with the state or federal courts situated
in Harris County, Texas, to hear such disputes arising under this Agreement.

        11.3   NO WAIVER

        No failure by either party hereto at any time to give notice of any
breach by the other party of, or to require compliance with, any condition or
provision of this 


                                      -8-
<PAGE>   70
Agreement shall be deemed a waiver of similar or dissimilar provisions or
conditions at the same or at any prior or subsequent time.

        11.4   SEVERABILITY

        If a court of competent jurisdiction determined that any provision of
this Agreement, including any appendices attached hereto, is invalid or
unenforceable, then the invalidity or unenforceability of that provision shall
not affect the validity or enforceability of any other provision of this
Agreement, and all other provisions shall remain in full force and effect.
Further, such provision shall be reformed and construed to the extent permitted
by law so that it may be valid, legal and enforceable to the maximum extent
possible.

        11.5   COUNTERPARTS

        This Agreement may be executed in one or more counterparts, each of
which shall be deemed to be an original, but all of which together will
constitute one and the same Agreement.

        11.6   HEADINGS

        The section headings have been inserted for purposes of convenience and
shall not be used for interpretive purposes.

        11.7   SUCCESSORS; THIRD PARTY BENEFICIARY

        This Agreement shall inure to the benefit of the successors and assigns
of the Company and the Investors and be binding upon the Stockholder and its
successors and assigns. The Stockholder agrees that any and all Investors in the
Company shall be treated as third party beneficiaries of this Agreement without
the necessity of execution of this Agreement, and shall be entitled to all of
the rights rendered to them herein.

        11.8   ENTIRE AGREEMENT

        This Agreement constitutes the entire agreement of the parties with
regard to the subject matter hereof, and contains all the covenants, promises,
representations, warranties and agreements between the parties with respect to
the subject matter hereof. Each party to this Agreement acknowledges that no
representation, inducement, promise or agreement, oral or written, with regard
to the subject matter hereof, has been made by either party, or by anyone acting
on behalf of either party, which is not embodied herein, and that no agreement,
statement or promise relating to the subject matter hereof which is not
contained in this Agreement or in such other agreements shall be valid and
binding.



                                      -9-
<PAGE>   71
        11.9   AMENDMENTS

        No amendment or modification to this Agreement will be effective unless
it is in writing and signed by the Company, the Stockholder and, if such
amendment alters or amends any of the rights of the Investors, by Investors
holding a majority of the outstanding shares of capital stock of the Company
held by such Investors, if any.

        11.10  INDEMNITY

        The Stockholder agrees to indemnify and hold harmless the Company and
any person, if any, who controls the Company or such successor within the
meaning of Section 15 of the Act against any and all loss, liability, claim,
damage and expense whatsoever (including, but not limited to, any and all
expenses whatsoever reasonably incurred in investigating, preparing or defending
against any litigation commenced or threatened or any claim whatsoever) arising
out of or based upon any false representation or warranty or breach or failure
by the Stockholder to comply with any covenant or agreement made by the
Stockholder herein or in any other document furnished by the Stockholder in
connection with this transaction.

        11.11  INJUNCTIVE RELIEF

        In view of the inadequacy of money damages, and in view of the fact that
the stock of the Company cannot be readily purchased or sold in the general
market, if the Stockholder or any other person shall fail to comply with any
provision of this Agreement, the Company shall be entitled, to the extent
permissible by law, to injunctive relief in the case of the violation, or
attempted or threatened violation, by Stockholder or other person of any such
provision, or to a decree compelling specific performance by the Stockholder or
other person, of any such provision, or to any other remedies legally available.

        11.12  VOID TRANSFERS

        If any Stock shall be sold or transferred otherwise than in accordance
with the terms and conditions of this Agreement, such sale shall be void. Any
such attempted sale or other transfer shall create a right in the Company to
purchase the Stock which is the subject of such purported transfer at the
applicable purchase price specified herein. Such right shall constitute an
"adverse claim" within the meaning of such term as used within the meaning of
the Uniform Commercial Code of any State. In addition to, and without prejudice
to, any and all other rights or remedies which may be available to the Company,
the Stockholder agrees that the Company may, but shall have no obligation to,
hold and refuse to transfer any Stock, or any certificate therefor, tendered to
it for transfer if the transfer violates the provisions of the Agreement.




                                      -10-
<PAGE>   72
        11.13  TAX REPRESENTATIONS

        The Stockholder acknowledges that the Company has made no warranties or
other representations to Stockholder with respect to the income tax consequences
of the transactions contemplated by this Agreement and Stockholder is in no
manner relying on the Company or its representatives for an account of such tax
consequences.

        11.14  FURTHER ASSURANCES

        The parties agree to execute such further instruments and to take such
further action as may reasonably be necessary to carry out the intent of this
Agreement.




                                      -11-
<PAGE>   73
     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
and delivered as of the day and year first above written.

                                            Company

                                            RGENE THERAPEUTICS, INC.




                                     By: /s/ MARTIN P. SUTTER
                                         -------------------------------------
                                     Name: Martin P. Sutter
                                           -----------------------------------
                                     Title: Chairman
                                            ----------------------------------


                                     Stockholder

                                     BOARD OF REGENTS OF THE 
                                     UNIVERSITY OF TEXAS SYSTEM



                                     By: /s/  THOMAS E. RICKS
                                         -------------------------------------
                                     Name: Thomas E. Ricks
                                           -----------------------------------
                                     Title: Vice Chairman for Asset Management
                                            ----------------------------------




                                      -12-
