LICENSE AGREEMENT

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                                                                  Exhibit 10.3.1

          Confidential Materials omitted and filed separately with the
         Securities and Exchange Commission. Asterisks denote omissions.

                                 LICENSE AGREEMENT

                                 by and between

                           WYETH HOLDINGS CORPORATION

                                       and

                                 BIOVEX LIMITED

                                    dated as of

                                  April 1, 2005

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                                LICENSE AGREEMENT

THIS AGREEMENT is made as of April 1, 2005 (the "Effective Date") by and between
Wyeth Holdings Corporation, having a place of business at Five Giralda Farms,
Madison, New Jersey, 07940 ("Licensor"), and Biovex Limited, (company number
3480520), having its registered office at 70 Milton Park, Abingdon, Oxford OX14
4RX England ("Licensee").

     Licensor is the owner of the Licensed Patents, as defined below.

     Licensee wishes to obtain a license under the Licensed Patents, to develop,
have developed, make, have made, use, offer to sell, sell and have sold, import
and have imported, Licensed Products and perform Licensed Services, as defined
below.

     Licensor is willing to grant such a license to Licensee on the terms and
conditions of this Agreement.

     Licensor and Licensee have therefore agreed as follows.

1. DEFINITIONS

     The following terms shall have the meanings indicated in this Agreement:

     1.1. "Agreement" means this Agreement, including all Schedules hereto.

     1.2. "Affiliate" means any Person controlled by, controlling, or under
common control with either Licensee or Licensor. For this purpose, "control"
means direct or indirect beneficial ownership of at least fifty percent (50%)
interest in the voting stock (or the equivalent) of such Person or having the
right to direct, appoint or remove a majority or more of the members of its
board of directors (or their equivalent), or having the power to control the
general management of such Person, by contract, law or otherwise.
Notwithstanding the foregoing, the term "Affiliate" shall not include Persons in
which a Party or its Affiliates owns a majority of the ordinary voting power to
elect a majority of the board of directors or other governing body, but is
restricted from electing such majority by contact or otherwise, until such time
as such restrictions are no longer in effect.

     1.3. "Applicable Percentage" means [**] percent ([**]%).

     1.4. "Bankruptcy Event" means, with respect to a specified Person, (a) the
filing by such Person in any court or agency, pursuant to any statute or
regulation of any state or country, a petition in bankruptcy or insolvency or
for reorganization or for the appointment of a receiver or trustee of such
Person or of its assets, (b) the filing against such Person of an involuntary
petition for any bankruptcy or insolvency proceeding which petition is not
dismissed within ninety (90) days after filing, (c) the making by such Person of
an assignment for the benefit of its creditors, (d) the taking of possession of
any material part of the assets of such Person by a lien holder or other
encumbrancer, or (e) the levy or enforcement of any distress, execution or other
process upon or against any of the material assets of such Person.


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     1.5. "Confidential Information" means, with respect to any Party
("Disclosing Party"), any information relating to the Licensed Product(s) or
Improvements that is disclosed in writing or by email to the other Party
("Receiving Party") during the term of this Agreement, but shall not include
information that:

          1.5.1. the Receiving Party or an Affiliate owned or controlled prior
     to receipt from the Disclosing Party, or

          1.5.2. is or becomes public through no breach of this Agreement by the
     Receiving Party or any Affiliate thereof, or

          1.5.3. is hereafter developed by the Receiving Party or an Affiliate
     independent of any disclosure from the Disclosing Party as evidenced by
     competent written evidence, or

          1.5.4. the Receiving Party or an Affiliate obtains from a third Person
     not under a confidentiality obligation to the Disclosing Party.

     1.6. "Effective Date" has the meaning given to it in the Preamble.

     1.7. "Improvements" means any information, patentable or otherwise,
developed or acquired (by license or otherwise, provided in the case of
acquisition that the terms of the acquisition do not prohibit Licensee from
making the grant set forth in Section 2.1.5) by Licensee during the term of this
Agreement and which relates to improvements to inventions disclosed in the
Licensed Patents as follows:

          "Improvements in Area A" means patentable and non-patentable [**] to
     regions of the HSV-1 and/or HSV-2 genome other than regions represented by
     the [**] gene or between the [**] and [**] sites on the [**] corresponding
     to [**] that result in improved [**] in and [**] neoplastic cells conceived
     under and/or reduced to practice by BioVex during the term of this
     Agreement;

          "Improvements in Area B" means patentable and non-patentable [**]
      within regions of the HSV-1 and/or HSV-2 genome represented by the [**]
     gene or between the [**] and [**] sites on the [**] corresponding to [**]
     that result in improved [**] in and [**] neoplastic cells conceived under
     and/or reduced to practice by BioVex during the term of this Agreement.

     1.8. "Licensed Patents" means United States patent application Serial
Number 08/686631 filed July 24, 1996 and any divisional, continuation or
continuation-in-part thereof or substitute therefor, any foreign patent
applications corresponding to any such patent applications claiming priority
from such patents and applications, and any U.S. or foreign patent or the
equivalent thereof issuing therefrom and any reissue, re-examination, renewal,
supplementary protection certificate or extension thereof.

     1.9. "Licensed Product(s)" means any product which would, or the
development, manufacture, use, sale or importation of which product would,
absent the license granted by


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Licensor to Licensee herein, infringe any Valid Claim in any Licensed Patent in
a country where a Licensed Patent subsists.

     1.10. "Licensed Service(s)" means any commercial research, development or
manufacturing services provided to a third Person, the provision of which
utilizes or embodies any process, product or discovery claimed by one or more
Valid Claims of any Licensed Patent in a country where a Licensed Patent
subsists.

     1.11. "Net Sales" shall mean the actual gross amount invoiced by Licensee
or its Affiliate or any sublicensee (as defined in Section 2.1.1(d)) for sales
or other commercial disposition of a Licensed Product, or provision of a
Licensed Service, to a third Person customer (including any distributor as
defined in Section 2.1.1 (b)), less the following deductions with respect to
such sales or services:

               a) any rebates, quantity, trade and cash discounts, and other
          usual and customary discounts to customers;

               b) compulsory payments and rebates, actually paid or deducted;

               c) retroactive price reductions, credits or allowances actually
          granted upon rejections or returns of Licensed Products, including for
          recalls or damaged goods;

               d) freight, postage, shipping and insurance charges actually
          allowed or paid for delivery of Licensed Products, to the extent
          included in the gross sales price;

               e) sales taxes, excise taxes, use taxes, import/export duties or
          other governmental charges actually due or incurred with respect to
          such sales, including without limitation value-added taxes;

               f) discounts and performance discounts to the extent that such
           discounts are associated with the Licensed Products together with
          other products of Licensee and its Affiliates, and to the extent that
          such discounts cannot be attributed only to the Licensed Products.
          Such discounts and performance discounts will be allocated to the
          Licensed Products on a reasonable pro rata basis (based on the amount
          of the sales of products by Licensee and its Affiliates prior to
          discount); and

               g) charge-back payments and rebates granted to managed health
          care organizations or to federal, state and local governments, their
          respective agencies, purchasers or reimbursers;

all as incurred in the ordinary course of business in type and amount consistent
with good industry practice and determined in accordance with generally accepted
accounting principles on a basis consistent with Licensee's audited consolidated
financial statements.


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For sake of clarity and avoidance of doubt, sales by Licensee, its Affiliates or
any sublicensee defined in Section 2.1.1 (d) of a Licensed Product to a
distributor defined in Section 2.1.1 (b) of such Licensed Product in a given
country shall be considered a sale to a third Person customer.

Any Licensed Products used as samples or used for clinical or other research
purposes and for donations shall not be included in Net Sales.

     1.12. "Party" means each party to this Agreement and their respective
successors and permitted assigns.

     1.13. "Person" means any natural person or legal entity.

     1.14. "Phase II" means any controlled clinical study involving the use of a
Licensed Product in human patients designed primarily to obtain preliminary data
on the effectiveness of a specific therapy involving the use of a Licensed
Product in human patients.

     1.15. "Phase III" means any Phase IIb/III clinical study involving a
Licensed Product designed to have adequate statistical power to meet the
requirements for regulatory approval by regulatory authorities either in the
United States, European Union, or Japan.

     1.16. "Royalty Payments" is defined in Section 3.1.4.

     1.17. "Territory" means all countries in the world.

     1.18 "Valid Claim" means any claim of any issued and unexpired patent that
has not been held permanently revoked, deemed unenforceable or invalid by a
decision of a court or other government agency of competent jurisdiction, which
decision is unappealable or unappealed within the time allowed for appeal.

2. LICENSE

     2.1. Grant of License. Licensor hereby grants to Licensee for the term of
this Agreement a non-exclusive, royalty bearing license under the Licensed
Patents, with the limited right to grant sublicenses only as set forth in
Section 2.1.1, to develop, have developed, make, have made, use, offer to sell,
sell, have sold, import and have imported, Licensed Products and to provide
Licensed Services in the Territory. In addition to the other terms and
conditions of this Agreement, the license granted hereby is subject to the
following:

          2.1.1. Sublicensing. Notwithstanding anything herein to the contrary,
     Licensee shall have the right to grant sublicenses only to (a) Licensee's
     Affiliates, (b) any distributor of Licensed Products pursuant to a bona
     fide arm's length distribution agreement between such distributor and
     Licensee, (c) any subcontractor that performs all or a portion of the
     manufacturing of Licensed Products pursuant to a bona fide arm's length
     manufacturing agreement between such subcontractor and Licensee, or (d) any
     third Person that enters into a bona fide license agreement with Licensee
     to make, use, sell or promote Licensed Products; provided, however, that
     Licensee shall be responsible for the operations of any sublicensee
     relevant to this Agreement as if such operations were carried out by
     Licensee itself, including


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     (without limitation) the payment of any royalties or other payments
     provided for hereunder. All sublicenses granted hereunder shall be
     consistent with and subject to the terms and conditions of this Agreement.
     Licensee shall notify Licensor of any such sublicense and provide Licensor
     with a copy of any such sublicense agreement within ten (10) days of the
     execution thereof.

          2.1.2. Restriction on other Rights. No right or license is granted to
     Licensee in or to any right or interest of Licensor that is not
     specifically set forth in this Agreement.

          2.1.3. Due Diligence. Licensee shall comply with all applicable laws
     and regulations. Licensee shall be responsible for obtaining all regulatory
     approvals required for the manufacture and sale of Licensed Products.
     Licensee shall provide Licensor (i) prompt written notice of all regulatory
     approvals for Licensed Products in the Territory, and (ii) on an annual
     basis with a summary of the development status of the Licensed Products and
     Licensed Services. Licensee shall use reasonable commercial efforts to
     research, develop and bring to market Licensed Products and Licensed
     Services; provided that Licensee shall always be free to stop development
     or put development of any Licensed Product or Licensed Service on hold
     without termination of this Agreement. In case Licensee provides written
     notice to Licensor that the development of all Licensed Products and
     Licensed Services is stopped or put on hold, all obligations of the
     Licensee hereunder shall cease or shall be suspended respectively, until
     such time as Licensee restarts development of a Licensed Product, except
     for the following: Section 2.1.3 first and third sentences, Sections, 3, 5,
     6, 7 and 8.

          2.1.4. Licensee shall inform Licensor within ten (10) business days
     upon achievement of any milestone described in Section 3.1.3.

          2.1.5. Improvements. Licensee hereby grants to Licensor (i) a [**]
     non-exclusive, [**] license [**] to the Improvements in Area A, and (ii) a
     [**] license [**] to the Improvements in Area B. Licensee shall keep
     Licensor currently and generally advised in writing of all Improvements,
     and shall provide Licensor with a written report thereof not less than once
     each calendar year. Upon request of Licensor, Licensee shall finish to
     Licensor one copy of all available documents relating to such Improvements.

3. PAYMENTS

     3.1. Payments. Licensee shall make the following payments to Licensor as
consideration for the rights granted by Licensor hereunder:

          3.1.1. Licensing Fee. Upon execution of this Agreement, Licensee shall
     pay within ten (10) days to Licensor a non-refundable licensing fee of [**]
     U.S. Dollars (U.S. $[**]) in immediately available funds to an account
     designated in writing by Licensor.

          3.1.2. Annual Maintenance Fee. Within thirty (30) days of each annual
     anniversary of the Effective Date, Licensee shall pay to Licensor [**] U.S.
     Dollars


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     (U.S. $[**]) creditable against payments under Section 3.1.4 in the
     Calendar year in which such annual maintenance fee is paid.

          3.1.3. Milestone Payments. Licensee shall pay to Licensor the
     following non-refundable milestone payments, to be paid only once, at the
     time when a Licensed Product reaches a milestone described below:

               (i) upon initiation of the first Phase II clinical trial by or on
          behalf of Licensee (for the purposes of this Section, initiation shall
          mean the first administration of the first Licensed Product in a
          clinical trial): [**] U.S. Dollars (U.S. $[**]);

               (ii) upon initiation of the first Phase II clinical trial by or
          on behalf of Licensee (for the purposes of this Section, initiation
          shall mean the first administration of the second and each subsequent
           Licensed Product in a clinical trial): [**] U.S. Dollars (U.S. $[**]);

               (iii) upon initiation of a Phase III clinical trial of each
          Licensed Product by or on behalf of Licensee (for the purposes of this
          Section, initiation shall mean the first administration of each
          Licensed Product in such a trial): [**] U.S. Dollars (U.S. $[**]); and

               (iv) upon receiving an approval for marketing anywhere in the
          Territory of each Licensed Product: [**] U.S. Dollars (U.S. $[**]).

     Each such milestone payment shall be due and payable to Licensor within
     thirty (30) days of the date such milestone is achieved (whether achieved
     by or on behalf of Licensee or any of its Affiliates or sublicensees).
     Licensee shall remit to Licensor each such milestone payment in immediately
     available funds to an account designated in writing by Licensor.

          3.1.4. Royalties. Licensee shall pay or cause to be paid to Licensor a
     royalty equal to the Applicable Percentage of all Net Sales of any Licensed
     Product or Licensed Service by Licensee or any of its Affiliates, or
     permitted sublicensees ("Royalty Payments") on a country-by-country basis.
     No multiple royalties shall be payable because a Licensed Product or
     Licensed Service, its manufacture, use or sale is or shall be covered by
     more than one Valid Claim of a patent included in the Licensed Patents or
     more than one patent under the Licensed Patents. Royalty shall only be
     payable once in respect of each Licensed Product. Royalty Payments shall be
     made in accordance with Sections 3.4 and 3.5.

     3.2. Records. During the Term of this Agreement and for three (3) years
thereafter, Licensee shall (and shall cause its Affiliates and permitted
sublicensees to) keep complete and accura