Document:

Exhibit 10.1 D

             THIRD AMENDMENT TO COLLABORATION AND LICENSE AGREEMENT

               Third amendment, dated March 25, 2002, (this "Amendment"), to the
Collaboration  and License  Agreement and the Subscription  Agreement dated June
12, 1998, each as amended through Amendment No. 1 dated May 10, 2000 and through
Amendment No. 2 dated July 2, 2001, and each by and between Aphton  Corporation,
a company  organized  under the laws of Delaware  with its  principal  executive
offices at the World  Trade  Center,  80 SW Eight  Street,  Suite  2160,  Miami,
Florida  (hereinafter  "Aphton"),  and SmithKline Beecham PLC, having a place of
business at New Horizon Court,  Great West Road,  Brentford,  Middlesex TW8 9EP,
United Kingdom  (hereinafter  "SB").  All capitalized  terms used herein but not
otherwise defined herein shall have the respective  meanings given to such terms
in the Collaboration and License Agreement.

                              W I T N E S S E T H:
                              - - - - - - - - - -

               WHEREAS, Aphton and SB are parties to a Collaboration and License
Agreement and a  Subscription  Agreement  dated June 12, 1998,  amended  through
Amendment No. 1 to the  Collaboration and License Agreement and the Subscription
Agreement  dated  May 10,  2000  (hereinafter  "Amendment  No.  1") and  through
Amendment No. 2 to the  Collaboration and License Agreement and the Subscription
Agreement dated July 2, 2001; and

               WHEREAS,  Aphton and SB wish to amend  certain  provisions of the
Collaboration  and  License  Agreement  (the  "Agreement")  as  amended  through
Amendments No. 1 and No. 2, as herein provided.

               NOW, THEREFORE, it is agreed:

               1.  Section  3.1  (i) of the  Agreement,  as  previously  revised
through Amendment No. 1 shall be further amended to read as follows:

               3.1.(i) Before end of April 2002, Aphton undertakes to deliver to
SB a full and detailed report  describing  preclinical  and clinical  activities
performed and results obtained so far as well as an Updated  Development Plan to
be accepted by the  Steering  Committee.  The  Steering  Committee  shall either
accept or reject Aphton's  proposed Updated  Development Plan within thirty (30)
days  of  submission  by  Aphton  to the  Steering  Committee.  If the  Steering
Committee rejects Aphton's proposed Updated Development Plan, it will provide to
Aphton the reasons for such  rejection  and Aphton shall be entitled to submit a
revised Updated  Development  Plan to the Steering  Committee within thirty (30)
days thereof. If the Steering Committee rejects such revised Updated Development
Plan, SB shall be entitled to terminate forthwith the Agreement by giving Aphton
a written  notice of its  election  to do so.  Upon  acceptance  of the  Updated
Development Plan, SB shall provide the Conjugate (being defined in Amendment No.
1 as anti-GnRH  conjugate  manufactured  under contract for SB) at no expense to
Aphton for its clinical use while stocks of GMP lot DD1DTP002  last.  After such
stock has run out,  SB shall not  provide any more  Conjugate  to Aphton.  After
April 1st,  2002,  Aphton  shall be  responsible

                                -1-
<PAGE>

for  verifying  at  its  expense  adequate  stability  of the  Conjugate  before
formulation into clinical lots, will provide SB with documented evidence of such
stability  and will  bear all  liability  related  to any lack of  stability  of
Conjugate  supplied  after April 1st,  2002.  The  parties  agree to replace the
Development  Plan  contained  in  schedule  B of the  Agreement  and  amended by
Amendment  No. 1 with the New  Development  Plan,  as approved  by the  Steering
Committee. The Development Program Term shall be amended accordingly.

               2. The sixth  sentence of Section 3.1 (ii) of the  Agreement,  as
previously revised through Amendment No. 1 and Amendment No. 2, shall be further
amended to read as follows:

           "In no event shall the Presentation Date be later than [ Redacted]*."

               3. The first  sentence  of Section  13.3.1 of the  Agreement,  as
previously revised through Amendment No. 1 and Amendment No. 2, shall be further
amended to read as follows:

               "Prior  to the  Acceptance  Date,  SB  shall  have  the  right to
terminate  this  Agreement  by serving  notice of no less than 30 days to Aphton
which will be effective as from September 30, 2003."

               4.  This   Amendment  is  limited  as  specified  and  shall  not
constitute a  modification,  acceptance or waiver of any other  provision of the
Collaboration  and License  Agreement and the Subscription  Agreement dated June
12,  1998,  as amended  through  Amendment  No. 1 dated May 10, 2000 and through
Amendment No. 2 dated July 2, 2001.

               5. This  Amendment may be executed in any number of  counterparts
and by the  different  parties  hereto on separate  counterparts,  each of which
counterparts when executed and delivered shall be an original,  but all of which
shall together constitute one and the same instrument.

               6. This Amendment and the rights of the parties  hereunder  shall
be governed by, and interpreted in accordance with, the laws of the State of New
York, without giving effect to the principles of conflict of law thereunder.

               7.  This  Amendment  shall  become  effective  on the  date  (the
"Amendment  Effective  Date")  when  each of the  Parties  shall  have  signed a
counterpart hereof (whether the same or different counterparts).

               8. From and after the Amendment Effective Date, all references in
the  Agreement  shall be deemed to be  references to the Agreement as amended by
this Amendment, Amendment No. 1 and Amendment No. 2.

----------------------------
*    The  redacted  portion of this  document  has been  omitted  pursuant  to a
     request for confidential treatment and such redacted portion has been filed
     separately with the Securities and Exchange Commission.

                              -2-
<PAGE>

               IN WITNESS  WHEREOF,  the parties  hereto have duly executed this
Amendment as of the date and year first above written.

                                   APHTON CORPORATION

                                     /s/ Philip C. Gevas
                                   --------------------------------------------
                                   Name:   Philip C. Gevas
                                   Title:  Chairman, President and
                                           Chief Executive Officer

                                   SMITHKLINE BEECHAM PLC

                                     /s/ Jean Stephenne
                                   --------------------------------------------
                                   Name:  Jean Stephenne
                                   Title:  Attorney- in-fact

                                -3-<PAGE>
                                                                     EXHIBIT 4.1

                             SUPPLEMENTAL INDENTURE

                                       OF

                                   GUARANTORS

         THIS SUPPLEMENTAL INDENTURE dated as of November 12, 2001 is delivered
pursuant to Section 10.04 of the Indenture dated as of November 15, 1996 (as
heretofore or hereafter modified and supplemented and in effect from time to
time, the "Indenture") among LAMAR MEDIA CORP., a Delaware corporation,
(formerly Lamar Advertising Company) certain of its subsidiaries ("Guarantors")
and STATE STREET BANK AND TRUST COMPANY, a Massachusetts banking corporation, as
Trustee ("Trustee") (all terms used herein without definition having the
meanings ascribed to them in the Indenture).

         The undersigned hereby agree that:

         1. The undersigned is a Guarantor under the Indenture with all of the
rights and obligations of a Guarantor thereunder.

         2. The undersigned hereby grants, ratifies and confirms the guarantee
provided for by Article Ten of the Indenture to guarantee unconditionally,
jointly and severally with the other Guarantors, to each Holder of a Note
authenticated and delivered by the Trustee, and to the Trustee on behalf of such
Holder, the due and punctual payment of the principal of (and premium, if any)
and interest on such Note when and as the same shall become due and payable.

         3. The undersigned hereby represents and warrants that the
representations and warranties set forth in the Indenture, to the extent
relating to the undersigned as Guarantor, are correct on and as of the date
hereof.

         4. All notices, requests and other communications provided for in the
Indenture should be delivered to the undersigned at the address specified in
Section 12.02 of the Indenture.

         5. A counterpart of this Supplemental Indenture may be attached to any
counterpart of the Indenture.

         6. This Supplemental Indenture shall be governed by and construed in
accordance with the laws of the State of New York.

<PAGE>

         IN WITNESS WHEREOF, the undersigned have caused this Supplemental
Indenture to be duly executed as of the day and year first above written.

                                    Guarantor:

                                    Trans West Outdoor Advertising, Inc.,
                                    a California company

                                    By:  /s/ Keith A. Istre
                                       -----------------------------------------
                                         Keith A. Istre
                                         Vice President - Finance and Chief
                                         Financial Officer

Attest:

By:      /s/ James R. McIlwain
   ----------------------------------
     James R. McIlwain, Secretary

Accepted:

STATE STREET BANK AND TRUST
    COMPANY, as Trustee

By:      /s/ Andrew L. Sciorz
   ---------------------------------

Title:   Assistant Vice President
      ------------------------------

                                       2

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