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                                                                    EXHIBIT 10.7

[*******] INDICATES MATERIAL THAT HAS BEEN OMITTED AND FOR WHICH CONFIDENTIAL
TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED MATERIAL HAS BEEN FILED WITH
THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 406 PROMULGATED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED.

                                LICENCE AGREEMENT

THIS AGREEMENT dated December 8, 2000 is between:

(1)    CAMBRIDGE UNIVERSITY TECHNICAL SERVICES LIMITED an English Company,
       Registered Number 1069886, whose registered office is at The Old Schools,
       Cambridge CB2 ITS, England ("CUTS"); and

(2)    TOLERRX (the "Licensee") a company incorporated in the State of Delaware
       whose registered office is at 675 Mass Ave., Cambridge, MA 02139, USA.

RECITALS:

A.     The University of Cambridge ("UC") has conducted research into anti-CD4
       and anti-CD8 antibodies, through its Department of Pathology under the
       Supervision of Professor H Waldmann, which has generated the Patents, the
       YNB Patent, the YNB Antibodies and the Antibodies.

B.     UC wishes to exploit the Patents, the YNB Patent, the YNB Antibodies and
       the Antibodies.

C.     The Licensee wishes to acquire rights under the Patents and YNB Patent
       and to use the Antibodies and YNB Antibodies for the development and
       commercialisation of Licensed Products in the Field and in the Territory,
       in accordance with the provisions of this Agreement.

D.     UC is willing to grant the licence through its wholly owned subsidiary
       CUTS subject to the terms and conditions of this Agreement.

IT IS AGREED as follows:

1.     DEFINITIONS

In this Agreement, the following words shall have the following meanings:

AFFILIATE                In relation to a Party, means any entity or person
                         which controls, is controlled by, or is under common
                         control with that Party. For the purposes of this
                         definition, "control" shall mean direct or indirect
                         beneficial ownership of 50% (or, outside a Party's home
                         territory, such lesser percentage as is the maximum,
                         permitted level of foreign investment) or more of the
                         share capital, stock or other participating interest
                         carrying the right to vote or to distribution of
                         profits of that entity or person, as the case may be.

ANNUAL NET SALES VALUE   The total Net Sales Value achieved by the Licensee
                         during a calendar year.

ANTIBODIES               Any and all of the monoclonal antibodies described in
                         Schedule 1, fragments of such antibodies, the clones
                         for producing such antibodies and the genetic material
                         encoding such antibodies,

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                         including but not limited to all derivatives,
                         modifications, progeny or part thereof.

COMMENCEMENT DATE        December 8, 2000

FIELD                    The prevention and treatment of human diseases and
                         disorders and the diagnoses and monitoring of or
                         susceptibility to human diseases, including, but not
                         limited to, those characterised by autoimmune,
                         immune-mediated, and/or immunological component(s) and
                         monitoring, therapeutic induction, and therapeutic
                         maintenance of immunological tolerance.

LICENSED PRODUCTS        Any and all products that (a) are within any Valid
                         Claim of the Patents and/or (b) incorporate any of the
                         Antibodies and/or (c) are within any Valid Claim of the
                         YNB Antibody Claims and/or (d) incorporate the YNB
                         Antibody.

NET SALES VALUE          The invoiced price of Licensed Products sold by the
                         Licensee or its Affiliates or its Sub-Licensee(s) to
                         independent third parties in arm's length transactions
                         exclusively for money or, where the sale is not at
                         arm's length, the price that would have been so
                         invoiced if it had been at arm's length, after
                         deduction of (i) normal trade discounts actually
                         granted and any credits actually given, and, (ii)
                         provided the amounts are separately charged on the
                         relevant invoice any costs of packaging, insurance,
                         carriage and freight, (iii) any value added tax or
                         other sales tax, and any import duties or similar
                         applicable government levies, and (iv) any and all US
                         Federal, estate or local government rebates, whether in
                         existence now, or enacted at any time during the term
                         of this Agreement, insofar as it applies to Licensed
                         Product, and (v) any invoiced price of Licensed
                         Products for which payment has not been received by the
                         Licensee due to bad debt.

OPTION FEE               The sum of $[*******] paid by the Licensee under the
                         terms of the Heads of Agreement and Option to Negotiate
                         a License Agreement of 27 September 2000 between CUTS
                         and the Licensee.

PARTIES                  CUTS and the Licensee, and "Party" shall mean either of
                         them.

PATENTS                  Any and all of the patents and patent applications
                         referred to in Schedule 1, including any continuations,
                         continuations in part, extensions, reissues,
                         reexaminations, divisions, and any patents,
                         supplementary protection certificates and similar
                         rights that are based on or derive priority from the
                         foregoing.

SUB-LICENSEE(S)          Any person or entity to whom Licensee grants a
                         sublicense under Patents or YNB Patent or to Antibodies
                         or to YNB Antibody.

TERRITORY                World-wide.

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

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VALID CLAIM              A claim of a patent or patent application that has not
                         expired or been disclaimed or been held invalid or
                         unenforceable by a court of competent jurisdiction or
                         other government agency of competent jurisdiction in a
                         final and non-appealable judgement or decision.

YNB ANTIBODIES           The monoclonal antibodies described in Schedule 2,
                         fragments of such antibodies, the clones for producing
                         such antibodies and the genetic material encoding such
                         antibodies, including but not limited to all
                         derivatives, modifications, progeny or part thereof.

YNB ANTIBODY CLAIMS      Any and all claims of the YNB Patent which are directed
                         solely to (i) an antibody capable of binding to human
                         CD4 antigen, or (ii) a pharmaceutical composition
                         comprising such antibody.
                         For the avoidance of doubt, any and all claims of the
                         YNB Patent which are directed to a process for the
                         preparation of an antibody chain are not included.

YNB PATENT               The patents and patent applications referred to in
                         Schedule 2, including any continuations, continuations
                         in part, extensions, reissues, reexaminations,
                         divisions, and any patents, supplementary protection
                         certificates and similar rights that are based on or
                         derive priority from the foregoing.

2.     GRANT OF RIGHTS

2.1    LICENCES. CUTS hereby grants to the Licensee, subject to the provisions
       of this Agreement:

       (a)    an exclusive licence in the Field under the Patents, with the
              right to sub-licence, subject to Clause 2.5 below, to develop,
              manufacture, have manufactured, use, offer to sell, import and
              sell Licensed Products but only in the Field in the Territory; and

       (b)    an exclusive licence in the Field, with the right to sub-licence,
              subject to Clause 2.5 below, to develop, manufacture, have
              manufactured, use, offer to sell, import and sell Licensed
              Products that incorporate Antibodies but only in the Field in the
              Territory, which licence shall take effect upon CUTS obtaining a
              written assignment of the Antibodies from the inventors to CUTS.
              CUTS shall use reasonable commercial efforts to obtain such
              assignment; and

       (c)    a non-exclusive licence in the Field: i) to the YNB Antibodies,
              and ii) under the YNB Antibody Claims, to develop, manufacture,
              have manufactured, use, offer to sell, import and sell Licensed
              Products that incorporate YNB Antibodies but only in the Field in
              the Territory, which licences shall take effect upon CUTS
              obtaining a written assignment of the YNB Antibodies from the
              inventors to CUTS. CUTS shall use reasonable commercial efforts to
              obtain such assignment. Such licence shall also be subject to any
              licence granted by CUTS to a third party with whom CUTS is
              currently negotiating a licence that may include rights to such
              YNB Antibodies and/or YNB Antibody Claims and/or YNB Patent. For
              the avoidance of doubt, no rights are granted under this Agreement
              to use the process for the preparation of an antibody chain under
              the YNB Patent Licensee shall have the

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              right to sub-licence the non-exclusive licence granted under this
              clause 2.1(c) with prior written permission of CUTS, and such
              permission not to be unreasonably withheld.

2.2    CUTS will not manufacture or sell the Licensed Products in the Field
       exclusively reserved to the Licensee, and will not grant a licence to
       other parties to use the Patents or Antibodies to make and sell the
       Licensed Products in the Field exclusively reserved to the Licensee.

2.3    For the avoidance of doubt, CUTS will have the right to grant licences to
       use the Patents and Antibodies to other parties for commercial purposes
       outside the Field.

2.4    FORMAL LICENCES. The Parties shall execute such formal licences as may be
       necessary or appropriate for registration with Patent Offices and other
       relevant authorities in particular territories. In the event of any
       conflict in meaning between any such licence and the provisions of this
       Agreement, the provisions of this Agreement shall prevail wherever
       possible. Prior to the execution of the formal licence(s) (if any)
       referred to in Clause 2.4, the Parties shall so far as possible have the
       same rights and obligations towards one another as if such licence(s) had
       been granted. The Parties shall use reasonable endeavours to ensure that,
       to the extent permitted by relevant authorities, this Agreement shall not
       form part of any public record.

2.5    SUB-LICENSING. The Licensee shall be entitled to grant sub-licences of
       its rights under this Agreement to any person, provided that:

       (a)            the sub-licence shall include obligations on the
              Sub-Licensee which are equivalent to the obligations on the
              Licensee under this Agreement and the Sub-Licensee shall be made
              aware of the obligations under this Agreement;

       (b)            within 30 days of the grant of any sub-licence the
              Licensee shall provide to CUTS a true copy of it; and

       (c)            the Licensee shall be responsible for any breach of the
              sub-licence by the Sub-Licensee that is also a breach of this
              Agreement, as if the breach had been that of Licensee under this
              Agreement, and the Licensee shall indemnify CUTS against any loss,
              damages, costs, claims or expenses which are awarded against or
              suffered by CUTS as a result of any such breach by the
              Sub-Licensee.

2.6    RESERVATION OF RIGHTS. Subject to clause 2.10, CUTS and UC specifically
       reserve the non-exclusive right to use the Antibodies and the Patents in
       the Field for the purposes of academic research and teaching and to
       publish the general scientific findings from research related to the
       Patents and/or the Antibodies, provided that no commercial entity has
       rights to the results of such research in the Field. CUTS agrees that it
       shall not and that it shall use all reasonable efforts to procure that UC
       shall not use Antibodies in humans, without prior consent from the
       Licensee. For the avoidance of doubt, CUTS and UC also reserve the right
       to use the YNB Antibodies and the YNB Patent in the Field for the
       purposes of academic research and teaching and to publish the general
       scientific findings from research related to the YNB Patent and YNB
       Antibodies.

2.7    NO OTHER LICENCE. It is acknowledged and agreed that no licence is
       granted by CUTS to the Licensee other than the licence(s) expressly
       granted by the provisions of this Clause 2.

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       Without prejudice to the generality of the foregoing CUTS reserves all
       rights under the Patents, YNB Patent, YNB Antibodies and Antibodies
       outside the Field.

2.8    QUALITY. The Licensee shall ensure that all of the Licensed Products
       marketed by it and its Sub-Licensees are of satisfactory quality and
       comply with all applicable laws and regulations in each part of the
       Territory.

2.9    RESPONSIBILITY FOR DEVELOPMENT OF LICENSED PRODUCTS. The Licensee shall
       be exclusively responsible for the technical and commercial development
       and manufacture of Licensed Products and for incorporating any
       modifications or developments thereto that may be necessary or desirable
       and for all Licensed Products sold or supplied, and accordingly the
       Licensee shall indemnify CUTS in the terms of Clause 7.3.

2.10   CUTS agrees that it shall not and that it shall use all reasonable
       efforts to procure that UC shall not transfer Antibodies in the
       possession of CUTS or UC to any for-profit organisation for use in the
       Field. CUTS further agrees that it shall use all reasonable efforts to
       procure that the transfer of Antibodies to any third party for use in the
       Field by CUTS and/or UC shall be subject to the completion of a material
       transfer agreement between said third party and UC and that the terms of
       such material transfer agreement shall:

       (a)    prohibit use of the Antibodies in humans, and

       (b)    prohibit publication of the genetic sequence of the Antibodies
              without prior reasonable consent from CUTS and/or UC, and

       (c)    prohibit use of the Antibodies in the Field for the benefit of any
              for-profit organisation.

2.11   CUTS agrees that it shall and that it shall use reasonable efforts to
       procure that UC shall provide to Licensee within thirty (30) days after
       the signing of this Agreement a sample of each material that is
       encompassed by Antibodies and that is in the possession of CUTS and/or
       UC.

3.     CONFIDENTIAL INFORMATION

3.1    CONFIDENTIALITY OBLIGATIONS. Each Party ("Receiving Party") undertakes:

       (a)            to maintain as secret and confidential all technical or
              commercial information obtained directly or indirectly from the
              other Party ("Disclosing Party") in the course of or in
              anticipation of this Agreement and to respect the Disclosing
              Party's rights therein,

       (b)            to use the same exclusively for the purposes of this
              Agreement, and

       (c)            to disclose the same only to those of its employees,
              contractors and Sub-Licensees pursuant to this Agreement (if any)
              to whom and to the extent that such disclosure is reasonably
              necessary for the purposes of this Agreement.

3.2    EXCEPTIONS TO OBLIGATIONS. The provisions of Clause 3.1 shall not apply
       to information which the Receiving Party can demonstrate by reasonable,
       written evidence:

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       (a)            was, prior to its receipt by the Receiving Party from the
              Disclosing Party, in the possession of the Receiving Party and at
              its free disposal; or

       (b)            is subsequently disclosed to the Receiving Party without
              any obligations of confidence by a third party who has not derived
              it directly or indirectly from the Disclosing Party; or

       (c)            is or becomes generally available to the public through no
              act or default of the Receiving Party or its agents, employees,
              Affiliates or Sub-Licensees; or

       (d)            the Receiving Party is required to disclose to the courts
              of any competent jurisdiction, or to any government regulatory
              agency or financial authority, provided that the Receiving Party
              shall (i) inform the Disclosing Party as soon as is reasonably
              practicable, and (ii) at the Disclosing Party's request seek to
              persuade the court, agency or authority to have the information
              treated in a confidential manner, where this is possible under the
              court, agency or authority's procedures; or

       (e)            in the case of information disclosed by CUTS to the
              Licensee, is disclosed to actual or potential customers for
              Licensed Products in so far as such disclosure is reasonably
              necessary to promote the sale or use of Licensed Products; or

       (f)            in the case of information disclosed by CUTS to Licensee,
              Licensee shall have the right to disclose information of CUTS to a
              third party in exercising the rights and licences granted to
              Licensee under this Agreement, provided that such third party
              agrees to be bound by confidentiality obligations at least as
              restrictive as Clauses 3.1 and 3.2.

3.3    DISCLOSURE TO EMPLOYEES. The Receiving Party shall procure that all of
       its employees, contractors and Sub-Licensees pursuant to this Agreement
       (if any) who have access to any of the Disclosing Party's information to
       which Clause 3.1 applies, shall be made aware of and subject to these
       obligations and shall have entered into written undertakings of
       confidentiality at least as restrictive as Clauses 3.1 and 3.2 and which
       apply to the Disclosing Party's information.

3.4    The obligations of the Parties under this Clause 3 shall survive the
       expiration or termination of this Agreement for whatever reason for a
       period of 5 years.

4.     PAYMENTS

4.1    INITIAL PAYMENT. On the later of 30 (thirty) days of the Commencement
       Date or the date on which CUTS provides to Licensee a written assignment
       of the Antibodies from the inventors thereof to CUTS, the Licensee shall
       pay to CUTS the non-refundable, non-deductible sum of $[*******]. On the
       later of 30 (thirty) days of the Commencement Date or the date on which
       CUTS provides to Licensee a written assignment of the Antibodies from the
       inventors thereof to CUTS, the Licensee shall also pay to CUTS the sum of
       all patent costs incurred by CUTS from 1 January 2000 to the Commencement
       Date to maintain, renew, prosecute and/or register ownership of the
       Patents, less the Option Fee.

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.
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4.2    MILESTONE PAYMENTS. In addition to the payments made under Clause 4.1,
       the Licensee shall pay CUTS the following sums ("Milestone Payments") for
       each Licensed Product:

       a)             $[*******] within 30 (thirty) days of initiation of Phase
                      II clinical trials for each Licensed Product; and

       (b)            $[*******] within 30 (thirty) days of initiation of Phase
                      III clinical trials for each Licensed Product.

       (c)            It is expressly understood that a Milestone Payment shall
                      not be due with respect to a Licensed Product for which
                      such Milestone Payment has already been paid that replaces
                      a Licensed Product or for clinical trials directed to new
                      indications for the same Licensed Product or for clinical
                      trials for a Licensed Product in a new dosage form.

4.3    ROYALTIES. The Licensee shall pay to CUTS a royalty as a percentage of
       the Net Sales Value of all Licensed Products or any part thereof sold by
       Licensee or its Sub-Licensees as follows:

              (i)     [*******] of the Net Sales Value when the Annual Net Sales
                      Value of Licensed Products is less than or equal to
                      $[*******]; or

              (ii)    [*******] of the Net Sales Value when the Annual Net Sales
                      Value of Licensed Products is greater than $[*******] and
                      less than or equal to $[*******]; or

              (iii)   [*******] of the Net Sales Value when the Annual Net Sales
                      Value of Licensed Products is greater than $[*******].

4.4    If, during the continuation of this Agreement, the Licensee considers it
       necessary to obtain a licence from any third party ("Third Party
       Licence(s)") in order to avoid infringing such third party's patent(s) in
       the course of manufacture or sale of Licensed Products AND the total
       royalty payable by the Licensee on the Licensed Products under this
       Agreement and all Third Party Licence(s) exceeds [*******] of the Net
       Sales Value, all royalties paid under the Third Party Licence(s) shall be
       treated as a deductible item when calculating Net Sales Value, provided
       that the amount of royalty payable by the Licensee to CUTS in any period
       shall not be reduced by more than [*******] of the amount which would
       have been payable in the absence of this Clause 4.4.

4.5    PAYMENT TERMS. Royalties due under this Agreement shall be paid within 60
       days of the end of each calendar year, in respect of sales of Licensed
       Products made during such calendar year and within 60 days of the
       termination of this Agreement.

4.6    All sums due under this Agreement:-

       (a)            are exclusive of Value Added Tax which where applicable
              will be paid by the Licensee to CUTS in addition;

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

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       (b)            shall be paid in pounds sterling by telegraphic transfer
              to the account of C.U.T.S. Ltd at [*******] and in the case of
              sales made by Licensee or a Sub-Licensee in a currency other than
              pounds sterling, the royalty shall be calculated in the other
              currency and then converted into equivalent pounds sterling at the
              buying rate of such other currency as quoted by Barclays Bank plc
              in London as at the close of business on the last business day of
              the quarterly period with respect to which the payment is made;

       (c)            shall be made without deduction of income tax or other
              taxes charges or duties that may be imposed on Licensee, except
              insofar as the Licensee is required to deduct the same to comply
              with applicable laws. The Parties shall cooperate and take all
              steps reasonably and lawfully available to them, at the expense of
              CUTS, to avoid deducting such taxes and to obtain double taxation
              relief. If the Licensee is required to make any such deduction it
              shall provide CUTS with such certificates or other documents as it
              can reasonably obtain to enable CUTS to obtain appropriate relief
              from double taxation of the payment in question; and

       (d)            shall be made by the due date, failing which CUTS may
              charge interest on any outstanding amount on a daily basis at a
              rate equivalent to 3% above the Barclays Bank plc base lending
              rate then in force.

4.7    If at any time during the continuation of this Agreement the Licensee is
       prohibited from making any of the payments required hereunder by a
       governmental authority in any country then the Licensee will within the
       prescribed period for making the said payments in the appropriate manner
       use its best endeavours to secure from the proper authority in the
       relevant country permission to make the said payments and will make them
       within 7 days of receiving such permission. If such permission is not
       received within 30 (thirty) days of the Licensee making a request for
       such permission then, at the option of CUTS, the Licensee shall deposit
       the royalty payments due in the currency of the relevant country either
       in a bank account designated by CUTS within such country or such royalty
       payments shall be made to an associated company of CUTS designated by
       CUTS and having offices in the relevant country designated by CUTS.

4.8    ROYALTY STATEMENTS. The Licensee shall send to CUTS at the same time as
       each royalty payment is made in accordance with Clause 4.5 a statement
       setting out, in respect of each territory or region in which Licensed
       Products are sold, the types of Licensed Product sold, the quantity of
       each type sold, and the total Net Sales Value in respect of each type,
       expressed both in local currency and pounds sterling and showing the
       conversion rates used, during the period to which the royalty payment
       relates.

4.9    RECORDS

4.9.1  The Licensee shall keep at its normal place of business detailed and up
       to date records and accounts showing the quantity, description and Net
       Sales Value of Licensed Product sold, and the amount of sublicensing
       revenues received by it in respect of Licensed Products, on a country by
       country basis, and being sufficient to ascertain the royalties due under
       this Agreement.

4.9.2  The Licensee shall make such records and accounts available, on
       reasonable notice, for inspection during business hours by an independent
       chartered accountant nominated by

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

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       CUTS for the purpose of verifying the accuracy of any statement or report
       given by the Licensee to CUTS under this Clause 4. The accountant shall
       be required to keep confidential all information learnt during any such
       inspection, and to disclose to CUTS only such details as may be necessary
       to report on the accuracy of the Licensee's statement or report. CUTS
       shall be responsible for the accountant's charges unless the accountant
       certifies that there is an underpayment of more than 5 per cent in any
       royalty statement, in which case the Licensee shall pay his charges in
       respect of that inspection.

4.9.3  The Licensee shall ensure that CUTS has the same rights as those set out
       in this Clause 4.9 in respect of any Sub-Licensee of the Licensee.

4.10   Only one royalty shall be due for each unit of a Licensed Product. As a
       result, a purchaser of a Licensed Product for which a royalty has been
       paid shall have the right to use or resell such Licensed Product without
       the payment of a further royalty under this Agreement.

5.     COMMERCIALISATION

5.1    (a)    Taking into account the complexity, and stage of development of
              the Licensed Products, Licensee shall use reasonable commercial
              efforts under the circumstances to research, develop and then
              commercialise Licensed Product in the United States, European
              Union and in other countries of the world in which Licensee can
              reasonably develop and market Licensed Product. The efforts of a
              Sub-Licensee and/or an Affiliate and/or a collaborator of Licensee
              shall be considered as efforts of Licensee.

       (b)    In the event that CUTS reasonably believes that Licensee is not
              making reasonable commercial efforts under the circumstances to
              research, develop and then commercialise Licensed Products
              pursuant to subclause 5.1(a), then CUTS shall provide written
              notice to Licensee which specifies CUTS' basis for such belief.
              Upon receipt of such written notice, CUTS and Licensee shall enter
              into good faith negotiations in order to reach mutual agreement as
              to what efforts by Licensee shall satisfy the requirements of
              Clause 5.1(a), and if such mutual agreement is not reached within
              ninety (90) days after receipt of such written notice, then the
              Parties agree to submit to arbitration pursuant to Clause 9.14 to
              determine the efforts which should be exerted by Licensee.
              Thereafter, Licensee shall exert the efforts determined by the
              Parties or in such arbitration.

       (c)    If Licensee fails to meet the goals and objectives determined by
              the Parties or in such arbitration and such failure results from
              Licensee failing to reasonably attempt to meet such goals and
              objectives, CUTS' sole and exclusive remedy is for the licences
              granted hereunder to be terminated which shall take effect sixty
              (60) days after written notice to Licensee unless prior to
              expiration of such sixty (60) day period, Licensee provides CUTS
              with reasonable assurances that such goals and objectives can be
              met in a reasonable time thereafter.

5.2    Without prejudice to the generality of the Licensee's obligations under
       Clause 5.1, the Licensee shall provide at least annually to CUTS an
       updated, written report, showing all past, current and projected
       activities taken or to be taken by the Licensee to bring Licensed
       Products to market and after initiating sales in a country, the
       activities taken to

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       market Licensed Product in such country. CUTS' receipt or approval of any
       such plan shall not be taken to waive or qualify the Licensee's
       obligations under Clause 5.1.

6.     INTELLECTUAL PROPERTY

6.1    OBTAIN AND MAINTAIN THE PATENTS.

       (a)    Licensee shall file, prosecute and maintain Patents, so as to
              secure the broadest patent protection reasonably available,
              through patent counsel selected by Licensee and reasonably
              acceptable to CUTS who shall consult with CUTS and keep CUTS
              advised with respect thereto.

              After the Effective Date of this Agreement, Licensee shall bear
              the cost and expense for the filing, prosecution and maintenance
              of Patents in the United States, European Patent Office, and Japan
              and any other foreign countries designated by Licensee.

       (b)    With respect to any Patents, each patent application, office
              action, response to office action, request for terminal
              disclaimer, and request for reissue or reexamination of any patent
              issuing from such application shall be provided to CUTS. CUTS
              shall have the right to take any action that in its judgement is
              necessary to preserve such Patents.

       (c)    CUTS shall and shall cause the inventors and UC to cooperate with
              Licensee with respect to filing, prosecution and maintenance of
              Patents.

       (d)    If the Licensee wishes to abandon any such application or not to
              maintain any such Patent (or to cease funding such application or
              Patent) it shall give 3 months' prior written notice to CUTS and
              on the expiry of such notice period the Licensee shall cease to be
              licensed under the patent application or Patent identified in the
              notice and shall take all actions necessary to transfer the
              prosecution and maintenance of such patent application or Patent
              to CUTS.

6.2    OBTAIN AND MAINTAIN THE YNB PATENT

       6.2.1  CUTS shall file, prosecute and maintain the YNB Patent, so as to
              secure the broadest patent protection reasonably available,
              through patent counsel selected by CUTS. CUTS shall consult with
              Licensee and keep Licensee advised with respect thereto.

       6.2.2  For the period of time Licensee remains the sole licensee of the
              YNB Patent, Licensee will pay all fees, costs, and expenses
              reasonably incurred from the Commencement Date in the prosecution
              and maintenance of the YNB Patent. For the avoidance of doubt,
              Licensee will not be liable for any costs incurred in relation to
              prosecuting and/or obtaining allowance of and/or defending claims
              other than YNB Antibody Claims.

       6.2.3  In any country in which CUTS desires patent protection under the
              YNB Patent but in which Licensee does not desire to pay the
              expenses thereof under Clause 6.2.2, the Licensee shall give three
              (3) months prior written notice to CUTS and on the

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              expiry of such notice period the licence granted hereunder will
              for such country be revoked.

       6.2.4  In the event that the YNB Patent is licensed to other parties
              patent costs pursuant to Clause 6.2.2 will be shared on a pro-rata
              basis according to the number of licences granted.

       6.2.5  For the avoidance of doubt, Licensee shall not be responsible for
              any costs or expenses associated with the opposition in the
              European Patent Office with respect to the YNB Patent.

6.3    INFRINGEMENT OF THE PATENTS

6.3.1  Each Party shall inform the other Party promptly if it becomes aware of
       any infringement or potential infringement of any of the Patents and/or
       YNB Patent in the Field, and the Parties shall consult with each other to
       decide the best way to respond to such infringement.

6.3.2  If the Parties fail to agree on a joint program of action within thirty
       (30) days, including how the costs of any such action are to be borne and
       how any damages or other sums received from such action are to be
       distributed, then the Licensee shall be entitled to take action against
       the third party at its sole expense and it shall reimburse CUTS for any
       reasonable expenses incurred in assisting it in such action. CUTS shall
       agree to be joined in any suit to enforce such rights subject to being
       indemnified and secured in a reasonable manner as to any costs, damages,
       expenses or other liability awarded against CUTS in such suit and shall
       have the right to be separately represented by its own counsel at its own
       expense. If the alleged infringement is both within and outside the
       Field, the Parties shall also co-operate with CUTS' other licensees (if
       any) in relation to any such action.

6.3.3  The Licensee shall be entitled to retain any monetary recovery from
       settlement with third parties after reimbursement of CUTS expenses
       pursuant to Clause 6.3.2, provided that the Licensee shall pay CUTS a
       royalty in accordance with Clause 4.3 on any monetary recovery as if such
       monetary recovery was Net Sales Value, to the extent that such monetary
       recovery by the Licensee exceeds its reasonable expenses in respect of
       the protection and enforcement of the Patents and/or YNB Patent within
       the Field.

6.3.4  In any infringement suit either Party may institute to enforce the rights
       in Patents and/or YNB Patent pursuant to this Agreement, the other Party
       hereto shall, at the request and expense of the Party initiating such
       suit, cooperate in all respects and, to the extent possible, have its
       employees testify when requested and make available relevant records,
       papers, information, samples, specimens, and the like. The Party
       requesting cooperation shall reimburse the other Party for amounts paid
       to a third party by such other Party pursuant to such cooperation.

6.4    INFRINGEMENT OF THIRD PARTY RIGHTS

6.4.1  If any warning letter or other notice of infringement is received by a
       Party, or legal suit or other action is brought against a Party, alleging
       infringement of third party rights in the manufacture, use or sale of any
       Licensed Product or use of any Patents or use of the YNB

11
<Page>

       Patent or use of any Antibodies or use of any YNB Antibodies, that Party
       shall promptly provide full details to the other Party, and the Parties
       shall discuss the best way to respond.

6.4.2  The Licensee shall have the right but not the obligation to defend such
       suit and shall have the right to settle with such third party, provided
       that if any action or proposed settlement involves the making of any
       statement, express or implied, concerning the validity of any Patent or
       YNB Patent, the consent of CUTS must be obtained before taking such
       action or making such settlement.

7.     WARRANTIES AND LIABILITY

7.1    WARRANTIES BY CUTS, CUTS warrants, represents and undertakes as follows:-

       (a)            subject to Clause 7.3, it is the absolute and unencumbered
              owner of the Patents and YNB Patent and has caused and will cause
              its directors and employees and UC to execute such assignments of
              the Patents and YNB Patent as may be necessary to give title to
              the Patents to CUTS; and

       (b)            it has not done, and will not do nor agree to do during
              the continuation of this Agreement, any of the following things if
              to do so would be inconsistent with the exercise by the Licensee
              of the rights granted to it under this Agreement, namely:

              (i)          grant or agree to grant any rights in the Patents or
                      Antibodies or YNB Patent or YNB Antibodies or any
                      improvements thereto; or

              (ii)         assign, mortgage, charge or otherwise transfer any of
                      the Patents or Antibodies or YNB Patent or YNB Antibodies
                      or (subject to Clause 9.3 below) any of its rights or
                      obligations under this Agreement.

7.2    NO OTHER WARRANTIES

7.2.1  Each of the Licensee and CUTS acknowledges that, in entering into this
       Agreement, it does not do so in reliance on any representation, warranty
       or other provision except as expressly provided in this Agreement, and
       any conditions, warranties or other terms implied by statute or common
       law are excluded from this Agreement to the fullest extent permitted by
       law.

7.2.2  Without limiting the scope of Clause 7.2.1, CUTS does not give any
       warranty, representation or undertaking:-

       (a)            as to the efficacy or usefulness of the Patents or YNB
              Patent or YNB Antibodies or Antibodies; or

       (b)            that any of the Patents or YNB Patent are or will be valid
              or subsisting or (in the case of an application) will proceed to
              grant; or

       (c)            that the use of any of the Patents or Antibodies or YNB
              Patent or YNB Antibodies, the manufacture, sale or use of the
              Licensed Products or the exercise

12
<Page>

              of any of the rights granted under this Agreement will not
              infringe any other intellectual property or other rights of any
              other person; or

       (d)            that any information communicated by CUTS to the Licensee
              under or in connection with this Agreement will produce Licensed
              Products of satisfactory quality or fit for the purpose for which
              the Licensee intended; or

       (e)            as imposing any obligation on CUTS to bring or prosecute
              actions or proceedings against third parties for infringement or
              to defend any action or proceedings for revocation of any of the
              Patents or YNB Patent; or

       (f)            as imposing any liability on CUTS in the event that any
              third party supplies Licensed Products to customers located in the
              Territory.

7.3    INDEMNITY. (a) The Licensee shall indemnify CUTS against any loss,
       damages, costs or expenses which are awarded against or incurred by CUTS
       as a result of any third party claim or threatened claim concerning the
       use by the Licensee or any of its Sub-Licensees of the Patents or
       Antibodies or YNB Patent or YNB Antibodies or otherwise in connection
       with the manufacture, use or sale of or any other dealing in any of the
       Licensed Products by Licensee or its Affiliates or any of its
       Sub-Licensees.

       (b)            Licensee's indemnification under (a) shall not apply to
              any liability, damage, loss or expense to the extent that it is
              directly attributable to the negligent activities or intentional
              misconduct of the Indemnitees or a breach of a warranty made by
              CUTS.

       (c)            Licensee shall have the right to control the defence,
              settlement or compromise of any such action and shall select
              counsel for such defence.

7.4    LIABILITY. Notwithstanding any other provision of this Agreement, no
       Party shall be liable to any other Party to this Agreement in contract,
       tort, negligence, breach of statutory duty or otherwise for any loss,
       damage, costs or expenses of any nature whatsoever incurred or suffered
       by that other party or its Affiliates of an indirect or consequential
       nature including without limitation any economic loss or other loss of
       turnover, profits, business or goodwill.

8.     DURATION AND TERMINATION

8.1    COMMENCEMENT AND TERMINATION BY EXPIRY. This Agreement, and the licences
       granted hereunder, shall come into effect on the Commencement Date and,
       unless terminated earlier in accordance with this Clause 8, shall
       continue in force on a country by country basis until the later of:

              (a)     the date on which all the Patents or YNB Patent in a
                      country have expired or been revoked or declared invalid
                      or unenforceable without a right of further appeal, or

              (b)     the tenth anniversary of the Commencement Date;

13
<Page>

       and on such date in such country the licences granted under sub-clause
       2.1(a) and 2.1(c) shall terminate automatically by expiry and the licence
       granted under sub-clause 2.1(b) shall become a fully paid-up,
       royalty-free non-exclusive licence.

8.2    EARLY TERMINATION

8.2.1  The Licensee may terminate this Agreement at any time on 90 (ninety) days
       notice in writing to CUTS.

8.2.2  Without prejudice to any other right or remedy, either Party may
       terminate this Agreement at any time by notice in writing to the other
       Party ("Other Party"), such notice to take effect as specified in the
       notice:-

       (a)    if the Other Party is in material breach of a material obligation
              of this Agreement and, in the case of a breach capable of remedy
              within ninety (90) days, the breach is not remedied within ninety
              (90) days of the Other Party receiving notice specifying the
              breach and requiring its remedy; or

       (b)    if the Other Party becomes insolvent, or if an order is made or a
              resolution is passed for the winding up of the Other Party (other
              than voluntarily for the purpose of solvent amalgamation or
              reconstruction), or if an administrator, administrative receiver
              or receiver is appointed in respect of the whole or any part of
              the Other Party's assets or business, or if the Other Party makes
              any composition with its creditors or takes or suffers any similar
              or analogous action in consequence of debt.

8.2.3  CUTS may forthwith terminate this Agreement by giving written notice to
       the Licensee if the Licensee or its Affiliate or Sub-Licensee commences
       legal proceedings, or assists any third party to commence legal
       proceedings, to challenge the validity or ownership of any of the Patents
       and/or Antibodies and/or YNB Patent and/or YNB Antibodies.

8.3    CONSEQUENCES OF TERMINATION

8.3.1  Upon termination of this Agreement for any reason otherwise than in
       accordance with Clause 8.1:

       (a)            the Licensee and its Sub-Licensees shall be entitled to
              sell, use or otherwise dispose of (subject to payment of royalties
              under Clause 4.3) any unsold or unused stocks of the Licensed
              Products for a period of 6 months following the date of
              termination;

       (b)            subject to paragraph (a) above, the Licensee shall no
              longer be licensed to use or otherwise exploit in any way, either
              directly or indirectly, the Patents or YNB Patent, in so far and
              for as long as any of the Patents or YNB Patent remains in force
              or the Antibodies or YNB Antibodies;

       (c)            subject to paragraph (a) above, the Licensee shall consent
              to the cancellation of any formal licence granted to it, or of any
              registration of it in any register, in relation to any of the
              Patents or YNB Patent;

14
<Page>

       (d)            subject as provided in this Clause 8.3.1 and 8.3.2, and
              except in respect of any accrued rights, and except with respect
              to clauses 3, 7.3, and 8.4 which shall survive termination of this
              Agreement, neither party shall be under any further obligation to
              the other.

8.3.2  In the event that this Agreement is terminated and at the time of
       termination Licensee and its Sub-Licensee(s) no longer intend to pursue
       development of Licensed Products and/or a CD4 and/or CD8 antibody, if
       requested by CUTS, Licensee agrees to negotiate in good faith with CUTS a
       royalty bearing licence on reasonable commercial terms to technology
       owned by Licensee that is useful for Licensed Product. In no event is
       Licensee obligated to grant such a license and Licensee and/or CUTS shall
       have the right to terminate such negotiations at any time by written note
       to the other party.

8.4    In the event that this Agreement and/or the rights and licences granted
       under this Agreement to Licensee are terminated, any sublicense granted
       under this Agreement shall remain in full force and effect as a direct
       licence between CUTS and the Sub-Licensee under the terms and conditions
       of this Agreement, subject to the Sub-Licensee agreeing to be bound to
       CUTS under such terms and conditions within thirty (30) days after CUTS
       provides written notice to the Sub-Licensee of the termination of
       Licensee's rights and licences under this Agreement. At the request of
       Licensee, CUTS will acknowledge to a Sub-Licensee, CUTS' obligations to
       the Sub-Licensee under this paragraph.

9.     GENERAL

9.1    FORCE MAJEURE. Neither Party shall have any liability or be deemed to be
       in breach of this Agreement for any delays or failures in performance of
       this Agreement which result from circumstances beyond the reasonable
       control of that Party, including without limitation labour disputes
       involving that Party. The Party affected by such circumstances shall
       promptly notify the other Party in writing when such circumstances cause
       a delay or failure in performance and when they cease to do so.

9.2    AMENDMENT. This Agreement may only be amended in writing signed by duly
       authorised representatives of CUTS and the Licensee.

9.3    ASSIGNMENT AND THIRD PARTY RIGHTS.

9.3.1  Subject to Clause 9.3.2 below and Licensee's right to grant sublicenses,
       neither Party shall assign this Agreement, nor any of the Patents or
       rights under the Patents, nor any of the Antibodies or rights to the
       Antibodies, nor any of the YNB Patent or rights under the YNB Patent, nor
       any of the YNB Antibodies or rights to the YNB Antibodies, without the
       prior written consent of the other Party, which shall not be withheld
       unreasonably.

9.3.2  Either Party may assign all its rights and obligations under this
       Agreement together with its rights in the Patents, the YNB Patent, the
       YNB Antibodies and the Antibodies to any company to which it transfers
       all or part of its assets or business or to a successor-in-interest or to
       an Affiliate, PROVIDED that the assignee undertakes to the other Party to
       be bound by and perform the obligations of the assignor under this
       Agreement.

9.4    WAIVER. No failure or delay on the part of either Party to exercise any
       right or remedy under this Agreement shall be construed or operate as a
       waiver thereof, nor shall any

15
<Page>

       single or partial exercise of any right or remedy preclude the further
       exercise of such right or remedy.

9.5    INVALID CLAUSES. If any provision or part of this Agreement is held to be
       invalid, amendments to this Agreement may be made by the addition or
       deletion of wording as appropriate to remove the invalid part or
       provision but otherwise retain the provision and the other provisions of
       this Agreement to the maximum extent permissible under applicable law.

9.6    NO AGENCY. Neither Party shall act or describe itself as the agent of the
       other, nor shall it make or represent that it has authority to make any
       commitments on the other's behalf.

9.7    INTERPRETATION. In this Agreement:

       (a)            the headings are used for convenience only and shall not
              affect its interpretation;

       (b)            references to persons shall include incorporated and
              unincorporated persons; references to the singular include the
              plural and vice versa; and references to the masculine include the
              feminine;

       (c)            references to Clauses and Schedules mean clauses of, and
              schedules to, this Agreement; and

       (d)            references to the grant of "exclusive" rights shall mean
              that the person granting the rights shall neither grant the same
              rights (in the same Field and Territory) to any other person, nor
              exercise those rights directly to the extent that and for as long
              as the Licensed Products are within Valid Claims of unexpired
              Patents.

9.8    NOTICES

9.8.1  Any notice to be given under this Agreement shall be in writing and shall
       be sent by first class mail or air mail, or by fax (confirmed by first
       class mail or air mail) to the address of the relevant Party set out at
       the head of this Agreement, or to the relevant fax number set out below,
       or such other address or fax number as that Party may from time to time
       notify to the other Party in accordance with this Clause 9.8. The fax
       numbers of the Parties are as follows: CUTS +44 (0)1223 332797 ; Licensee
       (001) 617 354 8300.

9.8.2  Notices sent as above shall be deemed to have been received three working
       days after the day of posting (in the case of inland first class mail),
       or seven working days after the date of posting (in the case of air
       mail), or on the next working day after transmission (in the case of fax
       messages, but only if a transmission report is generated by the sender's
       fax machine recording a message from the recipient's fax machine,
       confirming that the fax was sent to the number indicated above and
       confirming that all pages were successfully transmitted).

9.9    DISPUTES. Notwithstanding the provisions of Clause 5.1, any disputes
       incapable of resolution shall be settled by mediation at the Centre for
       Dispute Resolution (CEDR) or if ineffective then either by court
       proceedings if considered expedient by the complainant or alternatively
       and if agreed at the time by sole arbitrator to be appointed, and to
       proceed

16
<Page>

       according to the Rules of the International Chamber of Commerce (ICC)
       whose decision will be final.

9.10   LAW AND JURISDICTION. The validity, construction and performance of this
       Agreement shall be governed by English law and shall be subject to the
       nonexclusive jurisdiction of the English courts to which the parties
       hereby submit, except that a Party may seek an interim injunction in any
       court of competent jurisdiction.

9.11   FURTHER ACTION. Each Party agrees to execute, acknowledge and deliver
       such further instruments, and do all further similar acts, as may be
       necessary or appropriate to carry out the purposes and intent of this
       Agreement.

9.12   ANNOUNCEMENTS. Neither Party shall make any press or other public
       announcement concerning any aspect of this Agreement, or make any use of
       the name of the other Party in connection with or in consequence of this
       Agreement, without the prior written consent of the other Party, which
       consent shall not be withheld or delayed unreasonably. No consent shall
       be required where the disclosure is in conjunction with a financing or
       offering of securities or where required by applicable law, rule or
       regulation.

9.13   ENTIRE AGREEMENT. This Agreement, including its Schedules, sets out the
       entire agreement between the Parties relating to its subject matter and
       supersedes all prior oral or written agreements, arrangements or
       understandings between them relating to such subject matter. The Parties
       acknowledge that they are not relying on any representation, agreement,
       term or condition which is not set out in this Agreement.

9.14   Any matter or disagreement under Clause 5.1(b) which this Agreement
       specifies is to be resolved by arbitration shall be submitted to a
       mutually selected single arbitrator to so decide any such matter or
       disagreement. The arbitrator shall conduct the arbitration in accordance
       with the Rules of the International Chamber of Commerce, unless the
       Parties agree otherwise. If the Parties are unable to mutually select an
       arbitrator, the arbitrator shall be selected in accordance with the
       procedures of the International Chamber of Commerce. The decision
       rendered by the arbitrator shall be final and binding. Any arbitration
       pursuant to this section shall be held in London, England, or such other
       place as may be mutually agreed upon in writing by the Parties.

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<Page>

AGREED by the parties through their authorized signatories:-

For and on behalf of                      For and on behalf of
CAMBRIDGE UNIVERSITY TECHNICAL            TOLERRX
SERVICES LIMITED

/s/ R.C. Jennings                                /s/ D.J. Ringler
-------------------------------------     --------------------------------------
signed                                    signed

R.C. JENNINGS                                    D.J. Ringler
-------------------------------------     --------------------------------------
print name                                print name

DIRECTOR                                         C.E.O.
-------------------------------------     --------------------------------------
title                                     title

8 December 2000                                  Dec 8, 2000
-------------------------------------     --------------------------------------
date                                      date

                                       18
<Page>

                                    AGREEMENT

THIS AGREEMENT dated July 23, 2001 is between:

(1)    CAMBRIDGE UNIVERSITY TECHNICAL SERVICES LIMITED an English Company,
       Registered Number 1069886, whose registered office is at The Old Schools,
       Cambridge CB2 1TS, England ("CUTS"); and

(2)    TOLERRX (the "Licensee") a company incorporated in the State of Delaware
       whose registered office is at 675 Mass Avenue, Cambridge, MA 02139, USA.

       WHEREAS CUTS and Licensee have entered into License Agreement dated
December 8, 2000 (the "License Agreement"); and

       WHEREAS the parties desire to amend the License Agreement.

IT IS AGREED as follows:

1.     DEFINITIONS:

       1.01   All initially capitalized word and phrases shall be defined as
              defined in the License Agreement, except as amended herein.

2.     AMENDMENTS:

       2.01   Schedule 1 of the License Agreement is hereby amended to include
              the following:

              4.      TRX1 Antibody and Uses Therefor which is the subject
              matter of British patent application no. 0114517.6 and all patent
              applications and granted patents taking priority from such British
              application and all re-issues, re-evaluations and continuations in
              part therefrom.

3.     EFFECT

       Except as amended herein, the License Agreement shall be unaffected by
       this Agreement.

<Page>

AGREED by the parties through their authorized signatories:

For and on behalf of                      For an on behalf of
CAMBRIDGE UNIVERSITY TECHNICAL            TOLERRX
SERVICES LIMITED

/s/ R.C. Jennings                                /s/ D.J. Ringler
-------------------------------------     --------------------------------------
Signed                                    Signed

R.C. JENNINGS                                    D.J. Ringler
-------------------------------------     --------------------------------------
Print Name                                Print Name

DIRECTOR                                         CEO
-------------------------------------     --------------------------------------
Title                                     Title

23.7.01                                          18 July, 2001
-------------------------------------     --------------------------------------
Date                                      Date

<Page>

                               AMENDMENT AGREEMENT

THIS AMENDMENT AGREEMENT dated December 31, 2001 is between:

1.  CAMBRIDGE UNIVERSITY TECHNICAL SERVICES LIMITED, an English Company,
    Register Number 1069886, whose registered office is at The Old Schools,
    Cambridge CB2 TS, England ("CUTS"); and

2.  TOLERRX, INC. a company incorporated in the State of Delaware whose
    register office is at 675 Mass Ave., Cambridge, MA 02139, USA (the
    "Licensee").

WHEREAS CUTS and Licensee entered into a Licence Agreement dated December, 8
2000 that, among other things, is directed to certain CD4 and CD8 antibodies
(the "Licence Agreement");

WHEREAS the CUTS and Licensee desired to amend the Licence Agreement, INTER
ALIA, to include a non-exclusive licence to the YNB Patent (as defined below);
and

WHEREAS on the date hereof, CUTS shall assign the YNB Patent to BRITISH
TECHNOLOGY GROUP INTER-CORPORATE LICENSING LIMITED, an English Company,
Registered Number 2501784, whose registered office is at 10 Fleet Place,
Limeburner Lane, London EC4M 7SB ("BTG") by way of assignment and
commercialisation agreements (the "BTG Agreements"). Under the BTG Agreements,
BTG shall grant CUTS a non-exclusive licence to the YNB Patent (with the right
to sub-license to the Licensee).

In consideration of the sum of L 1 paid by each party
hereto to the other (the receipt of which is hereby acknowledged) IT IS
AGREED as follows:

1.     All defined terms of the Licence Agreement shall have the same meaning in
this Amendment. For the avoidance of doubt, the term "Parties" in this Amendment
shall have the meaning given in the Licence Agreement and shall not include BTG
unless otherwise stated.

2.     The following is added to the Licence Agreement as clause 2.1 (d):

            (d) "TO THE EXTENT NOT LICENSED UNDER CLAUSE 2.1 (c) A NON-EXCLUSIVE
            LICENCE IN THE FIELD: UNDER THE YNB PATENT, TO DEVELOP, MANUFACTURE,
            HAVE MANUFACTURED, USE, OFFER TO SELL, IMPORT AND SELL LICENSED
            PRODUCTS THAT INCORPORATE ANTIBODIES AND/OR LICENSED PRODUCTS THAT
            INCORPORATE YNB ANTIBODIES, BUT ONLY IN THE FIELD IN THE TERRITORY.
            LICENSEE SHALL HAVE THE RIGHT TO SUB-LICENSE THE NON-EXCLUSIVE
            LICENCE GRANTED UNDER THIS CLAUSE 2.1(d): (i) IN RESPECT OF LICENSED
            PRODUCTS INCORPORATING ANTIBODIES, SUBJECT TO CLAUSE 2.5; AND (ii)
            IN RESPECT OF LICENSED PRODUCTS INCORPORATING YNB ANTIBODIES, ON THE
            BASIS SET OUT IN CLAUSE 2.1(c). FOR THE AVOIDANCE OF DOUBT, NO
            RIGHTS ARE GRANTED UNDER THIS AGREEMENT TO USE THE PROCESS FOR THE
            PREPARATION OF AN ANTIBODY UNDER THE YNB PATENT (THE "YNB PROCESS
            CLAIMS") OTHER THAN IN RELATION TO LICENSED PRODUCTS INCORPORATING
            ANTIBODIES AND/OR YNB ANTIBODIES."

3.     The description of the "YNB Patent" (but not the "YNB Antibodies") set
out in Schedule 2 of the Licence Agreement shall be replaced with the schedule
attached hereto.

<Page>

4.     The following sentence shall be added to Clause 6.2.1:

       "6.2.1 CUTS SHALL HAVE THE RIGHT TO PERFORM ITS OBLIGATIONS UNDER THIS
              CLAUSE 6.2.1 THROUGH BTG."

5.     At the beginning of Clause 6.3.2, add the following:

       "IN RELATION TO ONLY THE YNB ANTIBODY CLAIMS AND THE PATENTS".

6.     The following shall be added at the end of Clause 6.3.2:

       "BTG (AND NOT THE OTHER PARTIES) SHALL BE ENTITLED TO TAKE SUCH ACTION AS
       IT SHALL SEE FIT IN RESPECT OF INFRINGEMENT OR POTENTIAL INFRINGEMENT OF
       THE YNB PROCESS CLAIMS".

7.     The following clause shall be added after Clause 6.3.4:

       "6.3.5 WITH RESPECT TO YNB PATENT ONLY, FOR THE PURPOSES OF CLAUSES
              6.3.1, 6.3.2, 6.3.3 AND 6.3.4, PARTY SHALL INCLUDE CUTS, BTG AND
              LICENSEE."

8.     After Clause 6.4.1 add the following sentence:

       "WITH  RESPECT TO YNB PATENT ONLY, BTG SHALL BE A PARTY UNDER THIS CLAUSE
       6.4.1."

9.     Clause 7.4 shall be renumbered as clause 7.5 and the following shall be
added to that clause:

       "BTG SHALL NOT HAVE ANY LIABILITY TO LICENSEE OR CUTS IN CONTRACT, TORT,
       NEGLIGENCE, BREACH OF STATUTORY DUTY OR OTHERWISE FOR ANY LOSS, DAMAGE,
       COSTS OR EXPENSES OF ANY NATURE WHATSOEVER INCURRED OR SUFFERED BY CUTS,
       LICENSEE OR ITS AFFILIATES OR SUB-LICENSEES AS A DIRECT OR INDIRECT
       RESULT OF THE USE OF THE YNB PATENTS AND/OR YNB ANTIBODIES."

10.    The following shall be added as a new clause 7.4:

    "7.4    LICENSEE SHALL INDEMNIFY BTG (AND ITS PARENT COMPANY, BTG PLC AND
            THE OTHER DIRECT OR INDIRECT SUBSIDIARIES OF BTG PLC AND THEIR
            RESPECTIVE DIRECTORS, OFFICERS AND EMPLOYEES) ON THE SAME BASIS AS
            THAT PROVIDED TO CUTS UNDER CLAUSES 2.5(c) AND 7.3 BUT IN RESPECT OF
            THE YNB PATENTS AND YNB ANTIBODIES ONLY"

11.    Licensee agrees (for the purposes of clause 9.3.1 of the Licence
Agreement) that CUTS may assign the YNB Patents to BTG pursuant to the BTG
Agreements, that is subject to the sublicense granted by CUTS to Licensee under
the YNB Patent and provided that CUTS obtains a license under the YNB Patent of
a scope necessary to grant the rights and licenses that are granted by CUTS to
Licensee under the YNB Patent in accordance with the License Agreement and this
Amendment Agreement.

                                        2
<Page>

12.    The Licence Agreement is amended as provided herein as of the date first
written above. All other terms and provisions of the Licence Agreement shall be
unaffected by this Amendment.

                                        3
<Page>

Agreed by the parties through their authorized signature.

CAMBRIDGE UNIVERSITY                      TOLERRX, INC.
TECHNICAL SERVICES LIMITED

By: /s/ R. C. Jennings                    By: /s/ D.J. Ringler
-------------------------------------     --------------------------------------

       In order to induce Licensee and CUTS to enter into this Amendment
Agreement and to induce CUTS to assign the YNB Patent to BTG and to induce
Licensee to agree to such assignment, BTG agrees that the license to CUTS from
BTG under the YNB Patent to the extent that the YNB Patent is licensed to
Licensee under the License Agreement and the Amendment Agreement shall continue
so long as the YNB Patents are sublicensed to Licensee under those agreements
and shall, if necessary, survive any earlier termination of the BTG agreements
and BTG hereby accepts its rights and obligations as set forth in this Amendment
Agreement.

BRITISH TECHNOLOGY GROUP
INTER-CORPORATE LICENSING LIMITED

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

                                        5
<Page>

#142536 v9 - Amendment Agreement

                               AMENDMENT AGREEMENT

       THIS AMENDMENT AGREEMENT dated December 19, 2002 is between:

       CAMBRIDGE UNIVERSITY TECHNICAL SERVICE LIMITED, an English Company,
Register Number 1069886, whose registered office is at The Old Schools,
Cambridge CB2 ITS, England ("CUTS"); and

       TOLERRX, INC., a company incorporated in the State of Delaware whose
registered office at 300 Technology Square, Cambridge, MA 02139, USA ("the
Licensee").

       WHEREAS, CUTS and Licensee entered into a License Agreement dated
December 8, 2000, including an amendment dated July 23 2001, that, among other
things, is directed to certain CD4 and CD8 antibodies ("the License Agreement");
and

       WHEREAS, the Licensee is seeking to enter into a sublicensing agreement
with Genentech, Inc. ("Genentech") in order to progress the development of
certain CD4 antibodies; and

       WHEREAS, the terms of the License Agreement dated December 8, 2000 made
such sublicensing agreement commercially non-viable; and

       WHEREAS, CUTS and Licensee desire to amend the License Agreement.

       In consideration of the sum of L 1 paid by each party hereto
to the other (the receipt of which is hereby acknowledged), IT IS AGREED as
follows:

1.     Save as provided below, all defined terms of the License Agreement shall
have the same meaning in this Amendment.
2.     In clause 4.2, reletter existing subclause (c) as subclause -(d)--and add
the following as subclause (c) which shall apply only to Licensed Product sold
under a sublicense granted to Genentech.
--(c)  [*******] on first regulatory approval of Licensed Product under a
sublicense granted to Genentech that permits sale thereof in the United States
and/or the European Union and/or Japan.--
3.     Add clauses 4.11, 4.12 and 4.13 which shall be applicable as referred to
below with respect to Licensed Product sold under a sublicense granted to
Genentech pursuant to an agreement between Genentech and Licensee (the
"Genentech Agreement").
            --4.11 In lieu of royalties under Section 4.3, the Licensee shall
       pay to CUTS a royalty as a percentage of net sales as calculated under
       the Genentech Agreement, including net sales in the United States as to
       which TolerRx is entitled to receive royalties or profits or losses under
       such U.S. Profit/Loss Sharing Option whether or not Licensee properly
       exercises and participates in the US Profit/Loss Sharing Option (as
       defined in the Genentech Agreement) ("Genentech Sales") of all Licensed
       Products or any part thereof sold under a sublicense granted to Genentech
       under the Genentech Agreement, on a country-by-country basis and Licensed
       Product-by Licensed Product basis, as follows:

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

<Page>

            (a)   As to Licensed Product that infringes a Valid Claim (as
       defined in the Genentech Agreement) of the Patents or a Valid Claim (as
       defined in the Genentech Agreement) of the YNB Patents:

                  (i)    [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that is less than or equal to
            $[*******] and

                  (ii)   [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that is greater than $[*******]
            and less than or equal to $[*******] and

                  (iii)  [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that exceeds $[*******] and less
            than or equal to $[*******] and

                  (iv)   [*******] of the portion of Genentech Sales of such
            Licensed Product that exceeds $[*******]

            (b)   As to Licensed Product that does not infringe a Valid Claim
       (as defined in the Genentech Agreement) of the Patents and does not
       infringe a Valid Claim (as defined in the Genentech Agreement) of the
       YNB Patents:

                  (i)    [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that is less than or equal to
            $[*******] and

                  (ii)   [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that is greater than $[*******]
            and less than or equal to $[*******]

                  (iii)  [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that exceeds $[*******] and less
            than or equal to $[*******] and

                  (iv)   [*******] of the portion of Genentech Sales of such
            Licensed Product in a calendar year that exceeds $[*******]

            4.12  In the event that Licensee's royalty payment from Genentech is
       reduced for a country as a result of another CD4 antibody product being
       marketed by a third party in that country, then any such reduction in the
       payment from Genentech shall be creditable against any royalty to be paid
       by Licensee under clause 4.11 of this

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

                                        2
<Page>

       Agreement but in no event shall any royalty payment under clause 4.11 be
       reduced by more than [*******] as a result of this clause.

            4.13 In lieu of clause 4.4, in the event that Licensee owes a
       royalty in a country for Licensed Product under a license agreement with
       a third party(ies) ("Third Party License(s)") or Licensee's payment from
       Genentech for a country is reduced because Genentech owes a royalty to a
       third party with respect to Licensed Product in that country, then any
       such royalty due under such a Third Party License(s) or any such
       reduction in the payment from Genentech shall be creditable against any
       royalty to be paid by Licensee under clause 4.11 of this Agreement but in
       no event shall any royalty payment under clause 4.11 be reduced by more
       than [*******] if this clauses applies and clause 4.12 does not apply, or
       by more than [*******] if this clause and clause 4.12 both apply. It is
       expressly understood that for the purpose of this clause 4.13, a Third
       Party License does not include the License between Isis Innovation
       Limited and the Chancellor Masters and Scholars of the University of
       Oxford with Licensee dated December 5, 2000 and/or the License between
       Mochida and Licensee dated September 20, 2001.

            4.14 The royalties in clauses 4.11, 4.12 and 4.13 herein shall be
       calculated on a country-by-country and Licensed Product-by-Licensed
       Product basis. A royalty due for Genentech Sales of a Licensed Product in
       a country under 4.11 may be reduced by [*******] if clause 4.12 applies
       and by a further [*******] if clause 4.13 applies in addition to clause
       4.12. For example purposes only: in a country where there is a valid
       claim as defined in the clause 4.11, another CD4 antibody product is
       marketed, but no royalties are owed to third parties the [*******]
       royalty would be reduced to [*******]. In a country where there is a
       valid claim as defined in clause 4.11, no other CD4 antibody product is
       marketed, but royalties are owed to third parties the [*******] royalty
       would be also reduced to [*******]. In a country where there is a valid
       claim as defined in clause 4.11, another CD4 antibody product is marketed
       and royalties are owed to third parties the [*******] royalty would be
       reduced by [*******] under clause 4.12 and by another [*******] under
       clause 4.13 whereby the cumulative reduction would be [*******] i.e.
       [*******] x [*******] x [*******].

4.     With respect to Clauses 2.5, 2.8, 3.3, 4.9.3, and 8.2.3 of the License
Agreement, CUTS waives any and all rights thereunder with respect to
sublicenses granted under the Genentech Agreement. For the avoidance of
doubt, clause 8.2.3 shall remain applicable to Licensee.

5.     Upon the written request of Licensor, Licensee agrees to exercise the
audit rights of Licensee under the Genentech Agreement.

6.     Licensee will provide to Licensor a true copy of the Genentech Agreement
within thirty (30) days of signing thereof by all parties thereto.

7.     For the avoidance of doubt, in the event of conflict between clauses 7.3
and 7.4 of the License Agreement, clause 7.3 shall prevail.

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

                                        3
<Page>

Agreed by the parties through their authorized signature.

CAMBRIDGE UNIVERSITY                      TOLERRX, INC.
TECHNICAL SERVICES LIMITED

By:    /s/ R.C. Jennings                  By:    /s/ D. J. Ringler

Name:  DR. R.C. JENNINGS                  Name:  Douglas J. Ringler

Title: DIRECTOR                           Title: President and CEO

Date:  19 Dec. '02                        Date:  December 19, 2002

                                        4<Page>
                                                                EXHIBIT 10.8

[*******] INDICATES MATERIAL THAT HAS BEEN OMITTED AND FOR WHICH CONFIDENTIAL
TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED MATERIAL HAS BEEN FILED WITH
THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO RULE 406 PROMULGATED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED.

                         CD2 ANTIBODY LICENCE AGREEMENT

THIS AGREEMENT dated 25 September 2001 is between:

1) CAMBRIDGE UNIVERSITY TECHNICAL SERVICES LIMITED an English Company,
   Registered Number 1069886, whose registered office is at The Old Schools,
   Cambridge CB2 ITS, England ("CUTS"); and

A. TOLERRX (the "Licensee") a company incorporated in the State of Delaware
   whose registered office is at 675 Mass Avenue, Cambridge, MA 02139.

RECITALS:

A.     The University of Cambridge ("UC") has conducted research into anti-CD2
       antibodies, through its Department of Pathology under the Supervision of
       Professor H Waldmann, which has generated the Patents and the Antibodies.

B.     UC wishes to exploit the Patents and the Antibodies.

C.     The Licensee wishes to acquire rights under the Patents and to use the
       Antibodies for the development and commercialisation of Licensed Products
       in the Field and in the Territory, in accordance with the provisions of
       this Agreement.

D.     UC is willing to grant the licence through its wholly owned subsidiary
       CUTS subject to the terms and conditions of this Agreement.

IT IS AGREED as follows:

1.     DEFINITIONS

In this Agreement, the following words shall have the following meanings:

AFFILIATE                In relation to a Party, means any entity or person
                         which controls, is controlled by, or is under common
                         control with that Party. For the purposes of this
                         definition, "control" shall mean direct or indirect
                         beneficial ownership of 50% (or, outside a Party's home
                         territory, such lesser percentage as is the maximum,
                         permitted level of foreign investment) or more of the
                         share capital, stock or other participating interest
                         carrying the right to vote or to distribution of
                         profits of that entity or person, as the case may be.

ANNUAL NET SALES VALUE   The total Net Sales Value achieved by the Licensee
                         during the calendar year.

ANTIBODIES               Any and all of the monoclonal antibodies described in
                         Schedule I, fragments of such antibodies, the clones
                         for producing such antibodies (and progeny thereof) and
                         the genetic material encoding such antibodies.

                                        1
<Page>

COMMENCEMENT DATE        25 September 2001

FIELD                    The prevention and treatment of human diseases and
                         disorders.

LICENSED PRODUCTS        Any and all products that (a) are within any Valid
                         Claim of the Patents and/or (b) incorporate any of the
                         Antibodies, provided to Licensee by or on behalf of
                         CUTS.

NET SALES VALUE          The invoiced price of Licensed Products sold by the
                         Licensee or its Affiliates or its Sub-Licensees to
                         independent third parties in arm's length transactions
                         exclusively for money or, where the sale is not at
                         arm's length, the price that would have been so
                         invoiced if it had been at arm's length, after
                         deduction of (i) normal trade discounts actually
                         granted and any credits actually given, and, (ii)
                         provided the amounts are separately charged on the
                         relevant invoice any costs of packaging, insurance,
                         carriage and freight, (iii) any value added tax or
                         other sales tax, and any import duties or similar
                         applicable government levies, and (iv) any and all US
                         Federal, estate or local government rebates, whether in
                         existence now, or enacted at any time during the term
                         of this Agreement, insofar as it applies to Licensed
                         Product, and (v) any invoiced price of Licensed
                         Products for which payment has not been received by the
                         Licensee due to bad debt.

PARTIES                  CUTS and the Licensee, and "Party" shall mean either of
                         them.

PATENTS                  Any and all of the patents and patent applications
                         referred to in Schedule I, including any continuations,
                         continuations in part, extensions, reissues,
                         reexaminations, divisions, and any patents,
                         supplementary protection certificates and similar
                         rights that are based on or derive priority from the
                         foregoing.

SUB-LICENSEE(S)          Any person or entity to whom Licensee grants a
                         sublicense under Patents or to Antibodies.

TERRITORY                World-wide.

VALID CLAIM              A claim of a patent or patent application that has not
                         expired or been disclaimed or been held invalid or
                         unenforceable by a court of competent jurisdiction or
                         other government agency of competent jurisdiction in a
                         final and non-appealable judgement or decision.

2.     GRANT OF RIGHTS

a)     LICENCES. CUTS hereby grants to the Licensee, subject to the provisions
       of this Agreement:

                                        2
<Page>

       (a)  an exclusive licence in the Field under the Patents, with the right
            to sub-licence, subject to Clause 2.5 below, to develop,
            manufacture, have manufactured, use, offer to sell, import and sell
            Licensed Products but only in the Field in the Territory; and

       (b)  an exclusive licence in the Field, with the right to sub-licence,
            subject to Clause 2.5 below, to develop, manufacture, have
            manufactured, use, offer to sell, import and sell Licensed Products
            that incorporate Antibodies but only in the Field in the Territory.

2.2    CUTS will not manufacture or sell the Licensed Products in the Field
       exclusively reserved to the Licensee, and will not grant a licence to
       other parties to use the Patents or Antibodies to make and sell the
       Licensed Products in the Field exclusively reserved to the Licensee.

2.3    For the avoidance of doubt, CUTS will have the right to grant licences to
       use the Patents and Antibodies to other parties for commercial purposes
       outside the Field.

2.4    FORMAL LICENCES. The Parties shall execute such formal licences as may be
       necessary or appropriate for registration with Patent Offices and other
       relevant authorities in particular territories. In the event of any
       conflict in meaning between any such licence and the provisions of this
       Agreement, the provisions of this Agreement shall prevail wherever
       possible. Prior to the execution of the formal licence(s) (if any)
       referred to in Clause 2.4, the Parties shall so far as possible have the
       same rights and obligations towards one another as if such licence(s) had
       been granted. The Parties shall use reasonable endeavours to ensure that,
       to the extent permitted by relevant authorities, this Agreement shall not
       form part of any public record.

2.5    SUB-LICENSING. The Licensee shall be entitled to grant sub-licences of
       its rights under this Agreement to any person, provided that:

       (a)  the sub-licence shall include obligations on the Sub-Licensee which
            are equivalent to the obligations on the Licensee under this
            Agreement and the Sub-Licensee shall be made aware of the
            obligations under this Agreement;
       (b)  within 30 days of the grant of any sub-licence the Licensee shall
            provide to CUTS a true copy of it; and
       (c)  the Licensee shall be responsible for any breach of the sub-licence
            by the Sub-Licensee that is also a breach of this Agreement, as if
            the breach had been that of Licensee under this Agreement, and the
            Licensee shall indemnify CUTS against any loss, damages, costs,
            claims or expenses which are awarded against or suffered by CUTS as
            a result of any such breach by the Sub-Licensee.

2.6    RESERVATION OF RIGHTS. Subject to clause 2.10, CUTS and UC specifically
       reserve the non-exclusive right to use the Antibodies and the Patents in
       the Field for the purposes of academic research and teaching and to
       publish the general scientific findings from research related to the
       Patents and/or the Antibodies, provided that no commercial entity has
       rights to the results of such research in the Field. CUTS agrees that it
       shall not use and that it shall use reasonable efforts to procure that UC
       shall not use Antibodies in humans, without prior consent from the
       Licensee.

                                        3
<Page>

2.7    NO OTHER LICENCE. It is acknowledged and agreed that no licence is
       granted by CUTS to the Licensee other than the licence(s) expressly
       granted by the provisions of this Clause 2. Without prejudice to the
       generality of the foregoing CUTS reserves all rights under the Patents
       and Antibodies outside the Field.

2.8    QUALITY. The Licensee shall ensure that all of the Licensed Products
       marketed by it and its Sub-Licensees are of satisfactory quality and
       comply with all applicable laws and regulations in each part of the
       Territory.

2.9    RESPONSIBILITY FOR DEVELOPMENT OF LICENSED PRODUCTS. The Licensee shall
       be exclusively responsible for the technical and commercial development
       and manufacture of Licensed Products and for incorporating any
       modifications or developments thereto that may be necessary or desirable
       and for all Licensed Products sold or supplied, and accordingly the
       Licensee shall indemnify CUTS in the terms of Clause 7.3.

2.10   CUTS agrees that it shall not transfer Antibodies and that it shall exert
       reasonable efforts to procure that UC shall not transfer Antibodies in
       the possession of CUTS or UC to any for-profit organisation for use in
       the Field. CUTS further agrees that the transfer of Antibodies to any
       third party for use in the Field by CUTS and/or UC shall be subject to
       the completion of a material transfer agreement between said third party
       and UC and that the terms of such material transfer agreement shall:

       (a)  prohibit use of the Antibodies in humans, and

       (b)  prohibit use of the Antibodies in the Field for the benefit of any
            for-profit organisation.

2.11   Licensor agrees to provide to Licensee within thirty (30) days after the
       signing of this Agreement a sample of each material that is encompassed
       by Antibodies and that is in the possession of CUTS and/or UC.

3.     CONFIDENTIAL INFORMATION

3.1    CONFIDENTIALITY OBLIGATIONS. Each Party ("Receiving Party") undertakes:

       (a)        to maintain as secret and confidential all technical or
            commercial information obtained directly or indirectly from the
            other Party ("Disclosing Party") in the course of or in anticipation
            of this Agreement and to respect the Disclosing Party's rights
            therein.

       (b)        to use the same exclusively for the purposes of this
            Agreement, and

       (c)        to disclose the same only to those of its employees,
            contractors and Sub-Licensees pursuant to this Agreement (if any) to
            whom and to the extent that such disclosure is reasonably necessary
            for the purposes of this Agreement.

3.2    EXCEPTIONS TO OBLIGATIONS. The provisions of Clause 3.1 shall not apply
       to information which the Receiving Party can demonstrate by reasonable,
       written evidence:

                                        4
<Page>

       (a)        was, prior to its receipt by the Receiving Party from the
            Disclosing Party, in the possession of the Receiving Party and at
            its free disposal; or

       (b)        is subsequently disclosed to the Receiving Party without any
            obligations of confidence by a third party who has not derived it
            directly or indirectly from the Disclosing Party; or

       (c)        is or becomes generally available to the public through no act
            or default of the Receiving Party or its agents, employees,
            Affiliates or Sub-Licensees; or

       (d)        the Receiving Party is required to disclose to the courts of
            any competent jurisdiction, or to any government regulatory agency
            or financial authority, provided that the Receiving Party shall (i)
            inform the Disclosing Party as soon as is reasonably practicable,
            and (ii) at the Disclosing Party's request seek to persuade the
            court, agency or authority to have the information treated in a
            confidential manner, where this is possible under the court, agency
            or authority's procedures; or

       (e)        in the case of information disclosed by CUTS to the Licensee,
            is disclosed to actual or potential customers for Licensed Products
            in so far as such disclosure is reasonably necessary to promote the
            sale or use of Licensed Products; or

       (f)        in the case of information disclosed by CUTS to Licensee,
            Licensee shall have the right to disclose information of CUTS to a
            third party in exercising the rights and licences granted to
            Licensee under this Agreement, provided that such third party agrees
            to be bound by confidentiality obligations at least as restrictive
            as Clauses 3.1 and 3.2.

3.3    DISCLOSURE TO EMPLOYEES. The Receiving Party shall procure that all of
       its employees, contractors and Sub-Licensees pursuant to this Agreement
       (if any) who have access to any of the Disclosing Party's information to
       which Clause 3.1 applies, shall be made aware of and subject to these
       obligations and shall have entered into written undertakings of
       confidentiality at least as restrictive as Clauses 3.1 and 3.2 and which
       apply to the Disclosing Party's information.

3.4    The obligations of the Parties under this Clause 3 shall survive the
       expiration or termination of this Agreement for whatever reason for a
       period of 5 years.

4.     PAYMENTS

4.1    INITIAL PAYMENT. Within 30 (thirty) days of the Commencement Date, the
       Licensee shall pay to CUTS the non-refundable, non-deductible sum of
       $[*******].

4.2    MILESTONE PAYMENTS. In addition to the payments made under Clause 4.1,
       the Licensee shall pay CUTS the following sums ("Milestone Payments") for
       each Licensed Product upon Licensee or its Sub-Licensee achieving the
       following:

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

                                        5
<Page>

       a)   $[*******] upon initiation of a Phase I clinical trial or a first in
            man study for each Licensed Product; and

       b)   $[*******] within 30 (thirty) days of initiation of Phase II
            clinical trials for each Licensed Products; and

       c)   $[*******] within 30 (thirty) days of initiation of Phase III
            clinical trials for each Licensed Product.

       d)   It is expressly understood that a Milestone Payment shall not be due
            with respect to a Licensed Product for which such Milestone Payment
            has already been paid that replaces a Licensed Product or for
            clinical trials directed to new indications for the same Licensed
            Product or for clinical trials for a Licensed Product in a new
            dosage form, provided, however that within (30) thirty days of
            regulatory approval in the United States or Europe of a Licensed
            Product for a different additional indication after regulatory
            approval of a first indication, Licensee shall pay CUTS $[*******]

4.3    ROYALTIES.

       (a) The Licensee shall pay to CUTS a royalty as a percentage of the Net
       Sales Value of all Licensed Products or any part thereof sold by Licensee
       as follows:

            (i)   [*******] of the Net Sales Value when the Annual Net Sales
                  Value of Licensed Products is less than or equal to
                  $[*******] or
            (ii)  [*******] of the Net Sales Value when the Annual Net Sales
                  Value of Licensed Products is greater than $[*******] and
                  less than or equal to $[*******] or
            (iii) [*******] of the Net Sales Value when the Annual Net Sales
                  Value of Licensed Products is greater than $[*******].

       (b) Licensee shall pay to CUTS a royalty of [*******] of the running
       royalties that Licensee receives from a Sub-Licensee based on Net Sales
       Value of Licensed Product PROVIDED ALWAYS THAT such royalty paid to CUTS
       under this Clause 4.3(b) shall not be less than [*******] of the Net
       Sales Value of all Licensed Products or any part thereof sold by such
       Sub-Licensee.

4.4    If, during the continuation of this Agreement, the Licensee considers it
       necessary to obtain a licence from any third party ("Third Party
       Licence(s)") in order to avoid infringing such third party's patent(s) in
       the course of manufacture or sale of Licensed Products AND the total
       royalty payable by the Licensee on the Licensed Products under this
       Agreement and all Third Party Licence(s) exceeds [*******] of the Net
       Sales Value, then all royalties paid under the Third Party Licence(s)
       shall be treated as a deductible item against royalties under Clause 4.3
       until the aggregate royalty is reduced to [*******] of the Net Sales
       Value, provided that the amount of royalty payable by the Licensee to
       CUTS in any period shall not be less than [*******] of the Net Sales
       Value.

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

                                        6
<Page>

4.5    PAYMENT TERMS. Royalties due under this Agreement shall be paid within 60
       days of the end of each calendar year, in respect of sales of Licensed
       Products made during such calendar year and within 60 days of the
       termination of this Agreement.

4.6    All sums due under this Agreement:-

       (a)        are exclusive of Value Added Tax which where applicable will
            be paid by the Licensee to CUTS in addition;

       (b)        shall be paid in pounds sterling by telegraphic transfer to
            the account of Cambridge University Technical Services Ltd at
            [*******] and in the case of sales made by Licensee or a
            Sub-Licensee in a currency other than pounds sterling, the royalty
            shall be calculated in the other currency and then converted into
            equivalent pounds sterling at the buying rate of such other currency
            as quoted by Barclays Bank plc in London as at the close of business
            on the last business day of the quarterly period with respect to
            which the payment is made;

       (c)        shall be made without deduction of income tax or other taxes
            charges or duties that may be imposed on Licensee, except insofar as
            the Licensee is required to deduct the same to comply with
            applicable laws. The Parties shall cooperate and take all steps
            reasonably and lawfully available to them, at the expense of CUTS,
            to avoid deducting such taxes and to obtain double taxation relief.
            If the Licensee is required to make any such deduction it shall
            provide CUTS with such certificates or other documents as it can
            reasonably obtain to enable CUTS to obtain appropriate relief from
            double taxation of the payment in question; and

       (d)        shall be made by the due date, failing which CUTS may charge
            interest on any outstanding amount on a daily basis at a rate
            equivalent to 3% above the Barclays Bank plc base lending rate then
            in force.

4.7    If at any time during the continuation of this Agreement the Licensee is
       prohibited from making any of the payments required hereunder by a
       governmental authority in any country then the Licensee will within the
       prescribed period for making the said payments in the appropriate manner
       use its best endeavours to secure from the proper authority in the
       relevant country permission to make the said payments and will make them
       within 7 days of receiving such permission. If such permission is not
       received within 30 (thirty) days of the Licensee making a request for
       such permission then, at the option of CUTS, the Licensee shall deposit
       the royalty payments due in the currency of the relevant country either
       in a bank account designated by CUTS within such country or such royalty
       payments shall be made to an associated company of CUTS designated by
       CUTS and having offices in the relevant country designated by CUTS.

4.8    ROYALTY STATEMENTS. The Licensee shall send to CUTS at the same time as
       each royalty payment is made in accordance with Clause 4.5 a statement
       setting out, in respect of each territory or region in which Licensed
       Products are sold, the types of Licensed Product sold, the quantity of
       each type sold, and the total Net Sales Value in respect of each type,

                                        * Confidential treatment requested:
                                          material has been omitted and filed
                                          separately with the Commission.

                                        7
<Page>

       expressed both in local currency and pounds sterling and showing the
       conversion rates used, during the period to which the royalty payment
       relates.

4.9    RECORDS

4.9.1  The Licensee shall keep at its normal place of business detailed and up
       to date records and accounts showing the quantity, description and Net
       Sales Value of Licensed Product sold, and the amount of sublicensing
       revenues received by it in respect of Licensed Products, on a country by
       country basis, and being sufficient to ascertain the royalties due under
       this Agreement.

4.9.2  The Licensee shall make such records and accounts available, on
       reasonable notice, for inspection during business hours by an independent
       chartered accountant nominated by CUTS for the purpose of verifying the
       accuracy of any statement or report given by the Licensee to CUTS under
       this Clause 4. The accountant shall be required to keep confidential all
       information learnt during any such inspection, and to disclose to CUTS
       only such details as may be necessary to report on the accuracy of the
       Licensee's statement or report. CUTS shall be responsible for the
       accountant's charges unless the accountant certifies that there is an
       underpayment of more than 5 per cent in any royalty statement, in which
       case the Licensee shall pay his charges in respect of that inspection.

4.9.3  The Licensee shall ensure that CUTS has the same rights as those set out
       in this Clause 4.9 in respect of any Sub-Licensee of the Licensee.

4.10   Only one royalty shall be due for each unit of a Licensed Product. As a
       result, a purchaser of a Licensed Product for which a royalty has been
       paid shall have the right to use or resell such Licensed Product without
       the payment of a further royalty under this Agreement.

5.     COMMERCIALISATION

5.1    (a)  Taking into account the complexity, and stage of development of the
            Licensed Products, Licensee shall use reasonable commercial efforts
            under the circumstances to research, develop and then commercialise
            Licensed Product in the United States, European Union and in other
            countries of the world in which Licensee can reasonably develop and
            market Licensed Product. The efforts of a Sub-Licensee and/or an
            Affiliate and/or a collaborator of Licensee shall be considered as
            efforts of Licensee.

       (b)  In the event that CUTS reasonably believes that Licensee is not
            making reasonable commercial efforts under the circumstances to
            research, develop and then commercialise Licensed Products pursuant
            to subclause 5.1(a), then CUTS shall provide written notice to
            Licensee which specifies CUTS' basis for such belief. Upon receipt
            of such written notice, CUTS and Licensee shall enter into good
            faith negotiations in order to reach mutual agreement as to what
            efforts by Licensee shall satisfy the requirements of Clause 5.1(a),
            and if such mutual agreement is not reached within ninety (90) days
            after receipt of such written notice, then the Parties agree to
            submit to arbitration pursuant to Clause 9.14 to determine the
            efforts which

                                        8
<Page>

            should be exerted by Licensee. Thereafter, Licensee shall exert the
            efforts determined by the Parties or in such arbitration.

       (c)  If Licensee fails to meet the goals and objectives determined by the
            Parties or in such arbitration and such failure results from
            Licensee failing to reasonably attempt to meet such goals and
            objectives, CUTS' sole and exclusive remedy is for the licences
            granted hereunder to be terminated which shall take effect sixty
            (60) days after written notice to Licensee unless prior to
            expiration of such sixty (60) day period, Licensee provides CUTS
            with reasonable assurances that such goals and objectives can be met
            in a reasonable time thereafter.

5.2    Without prejudice to the generality of the Licensee's obligations under
       Clause 5.1, the Licensee shall provide at least annually to CUTS an
       updated, written report, showing all past, current and projected
       activities taken or to be taken by the Licensee to bring Licensed
       Products to market and after initiating sales in a country, the
       activities taken to market Licensed Product in such country. CUTS'
       receipt or approval of any such plan shall not be taken to waive or
       qualify the Licensee's obligations under Clause 5.1.

6.     INTELLECTUAL PROPERTY

6.1    OBTAIN AND MAINTAIN THE PATENTS.

       (a)  Licensee shall file, prosecute and maintain Patents, so as to secure
            the broadest patent protection reasonably available, through patent
            counsel selected by Licensee and reasonably acceptable to CUTS who
            shall consult with CUTS and keep CUTS advised with respect thereto.

            After the Effective Date of this Agreement, Licensee shall bear the
            cost and expense for the filing, prosecution and maintenance of
            Patents in the United States, European Patent Office, and Japan and
            any other foreign countries designated by Licensee.

       (b)  With respect to any Patents, each patent application, office action,
            response to office action, request for terminal disclaimer, and
            request for reissue or reexamination of any patent issuing from such
            application shall be provided to CUTS. CUTS shall have the right to
            take any action that in its judgement is necessary to preserve such
            Patents.

       (c)  CUTS shall and shall cause the inventors and UC to cooperate with
            Licensee with respect to filing, prosecution and maintenance of
            Patents.

       (d)  If the Licensee wishes to abandon any such application or not to
            maintain any such Patent (or to cease funding such application or
            Patent) it shall give 3 months' prior written notice to CUTS and on
            the expiry of such notice period the Licensee shall cease to be
            licensed under the patent application or Patent identified in the
            notice and shall take all actions necessary to transfer the
            prosecution and maintenance of such patent application or Patent to
            CUTS.

6.2    INFRINGEMENT OF THE PATENTS

                                        9
<Page>

6.2.1  Each Party shall inform the other Party promptly if it becomes aware of
       any infringement or potential infringement of any of the Patents in the
       Field, and the Parties shall consult with each other to decide the best
       way to respond to such infringement.

6.2.2  If the Parties fail to agree on a joint program of action within thirty
       (30) days, including how the costs of any such action are to be borne and
       how any damages or other sums received from such action are to be
       distributed, then the Licensee shall be entitled to take action against
       the third party at its sole expense and it shall reimburse CUTS for any
       reasonable expenses incurred in assisting it in such action. CUTS shall
       agree to be joined in any suit to enforce such rights subject to being
       indemnified and secured in a reasonable manner as to any costs, damages,
       expenses or other liability awarded against CUTS in such suit and shall
       have the right to be separately represented by its own counsel at its own
       expense. If the alleged infringement is both within and outside the
       Field, the Parties shall also co-operate with CUTS' other licensees (if
       any) in relation to any such action.

6.2.3  The Licensee shall be entitled to retain any monetary recovery from
       settlement with third parties after reimbursement of CUTS expenses
       pursuant to Clause 6.2.2, provided that the Licensee shall pay CUTS a
       royalty in accordance with Clause 4.3 on any monetary recovery as if such
       monetary recovery was Net Sales Value, to the extent that such monetary
       recovery by the Licensee exceeds its reasonable expenses in respect of
       the protection and enforcement of the Patents within the Field.

6.2.4  In any infringement suit either Party may institute to enforce the rights
       in Patents pursuant to this Agreement, the other Party hereto shall, at
       the request and expense of the Party initiating such suit, cooperate in
       all respects and, to the extent possible, have its employees testify when
       requested and make available relevant records, papers, information,
       samples, specimens, and the like. The Party requesting cooperation shall
       reimburse the other Party for amounts paid to a third party by such other
       Party pursuant to such cooperation.

6.3    INFRINGEMENT OF THIRD PARTY RIGHTS

6.3.1  If any warning letter or other notice of infringement is received by a
       Party, or legal suit or other action is brought against a Party, alleging
       infringement of third party rights in the manufacture, use or sale of any
       Licensed Product or use of any Patents or use of any Antibodies, that
       Party shall promptly provide full details to the other Party, and the
       Parties shall discuss the best way to respond.

6.3.2  The Licensee shall have the right but not the obligation to defend such
       suit and shall have the right to settle with such third party, provided
       that if any action or proposed settlement involves the making of any
       statement, express or implied, concerning the validity of any Patent, the
       consent of CUTS must be obtained before taking such action or making such
       settlement.

7.     WARRANTIES AND LIABILITY

7.1    WARRANTIES BY CUTS. CUTS warrants, represents and undertakes as follows:-

                                       10
<Page>

       (a)        subject to Clause 7.3, it is the absolute and unencumbered
            owner of the Patents and has caused and will cause its directors and
            employees and UC to execute such assignments of the Patents as may
            be necessary to give title to the Patents to CUTS; and

       (b)        it has not done, and will not do nor agree to do during the
            continuation of this Agreement, any of the following things if to do
            so would be inconsistent with the exercise by the Licensee of the
            rights granted to it under this Agreement, namely:

            (i)          grant or agree to grant any rights in the Patents or
                  Antibodies or any improvements thereto; or

            (ii)         assign, mortgage, charge or otherwise transfer any of
                  the Patents or Antibodies or (subject to Clause 9.3 below) any
                  of its rights or obligations under this Agreement.

7.2    NO OTHER WARRANTIES

7.2.1  Each of the Licensee and CUTS acknowledges that, in entering into this
       Agreement, it does not do so in reliance on any representation, warranty
       or other provision except as expressly provided in this Agreement, and
       any conditions, warranties or other terms implied by statute or common
       law are excluded from this Agreement to the fullest extent permitted by
       law.

7.2.2  Without limiting the scope of Clause 7.2.1, CUTS does not give any
       warranty, representation or undertaking:-

       (a)        as to the efficacy or usefulness of the Patents or Antibodies;
            or

       (b)        that any of the Patents is or will be valid or subsisting or
            (in the case of an application) will proceed to grant; or

       (c)        that the use of any of the Patents or Antibodies, the
            manufacture, sale or use of the Licensed Products or the exercise of
            any of the rights granted under this Agreement will not infringe any
            other intellectual property or other rights of any other person; or

       (d)        that any information communicated by CUTS to the Licensee
            under or in connection with this Agreement will produce Licensed
            Products of satisfactory quality or fit for the purpose for which
            the Licensee intended; or

       (e)        as imposing any obligation on CUTS to bring or prosecute
            actions or proceedings against third parties for infringement or to
            defend any action or proceedings for revocation of any of the
            Patents; or

       (f)        as imposing any liability on CUTS in the event that any third
            party supplies Licensed Products to customers located in the
            Territory.

                                       11
<Page>

7.3    INDEMNITY. (a) The Licensee shall indemnify CUTS against any loss,
       damages, costs or expenses which are awarded against or incurred by CUTS
       as a result of any third party claim or threatened claim concerning the
       use by the Licensee or any of its Sub-Licensees of the Patents or
       Antibodies or otherwise in connection with the manufacture, use or sale
       of or any other dealing in any of the Licensed Products by Licensee or
       its Affiliates or any of its Sub-Licensees.

       (b)        Licensee's indemnification under (a) shall not apply to any
            liability, damage, loss or expense to the extent that it is directly
            attributable to the negligent activities or intentional misconduct
            of the Indemnitees.

       (c)        Licensee shall have the right to control the defence,
            settlement or compromise of any such action and shall select counsel
            for such defence.

7.4    LIABILITY. Notwithstanding any other provision of this Agreement, no
       Party shall be liable to any other Party to this Agreement in contract,
       tort, negligence, breach of statutory duty or otherwise for any loss,
       damage, costs or expenses of any nature whatsoever incurred or suffered
       by that other party or its Affiliates of an indirect or consequential
       nature including without limitation any economic loss or other loss of
       turnover, profits, business or goodwill.

8.     DURATION AND TERMINATION

8.1    COMMENCEMENT AND TERMINATION BY EXPIRY. This Agreement, and the licences
       granted hereunder, shall come into effect on the Commencement Date and,
       unless terminated earlier in accordance with this Clause 8, shall
       continue in force on a country by country basis until the later of:

            (a)   the date on which all the Patents in a country have expired or
                  been revoked or declared invalid or unenforceable without a
                  right of further appeal, or

            (b)   the tenth anniversary of the Commencement Date;

       and on such date in such country the licence granted under sub-clause
       2.1(a) shall terminate automatically by expiry and the licence granted
       under sub-clause 2.1(b) shall become a fully paid-up, royalty-free
       non-exclusive licence.

8.2    EARLY TERMINATION

8.2.1  The Licensee may terminate this Agreement at any time on 90 (ninety) days
       notice in writing to CUTS.

8.2.2  Without prejudice to any other right or remedy, either Party may
       terminate this Agreement at any time by notice in writing to the other
       Party ("Other Party"), such notice to take effect as specified in the
       notice:-

       (a)  if the Other Party is in material breach of a material obligation of
            this Agreement and, in the case of a breach capable of remedy within
            ninety (90) days, the breach is not remedied within ninety (90) days
            of the Other Party receiving notice

                                       12
<Page>

            specifying the breach and requiring its remedy; or (b) if the Other
            Party becomes insolvent, or if an order is made or a resolution is
            passed for the winding up of the Other Party (other than voluntarily
            for the purpose of solvent amalgamation or reconstruction), or if an
            administrator, administrative receiver or receiver is appointed in
            respect of the whole or any part of the Other Party's assets or
            business, or if the Other Party makes any composition with its
            creditors or takes or suffers any similar or analogous action in
            consequence of debt.

8.2.3  CUTS may forthwith terminate this Agreement by giving written notice to
       the Licensee if the Licensee or its Affiliate or Sub-Licensee commences
       legal proceedings, or assists any third party to commence legal
       proceedings, to challenge the validity or ownership of any of the Patents
       and/or Antibodies.

8.3    CONSEQUENCES OF TERMINATION

8.3.1  Upon termination of this Agreement for any reason otherwise than in
       accordance with Clause 8.1:

       (a)        the Licensee and its Sub-Licensees shall be entitled to sell,
            use or otherwise dispose of (subject to payment of royalties under
            Clause 4.3) any unsold or unused stocks of the Licensed Products for
            a period of 6 months following the date of termination;

       (b)        subject to paragraph (a) above, the Licensee shall no longer
            be licensed to use or otherwise exploit in any way, either directly
            or indirectly, the Patents, in so far and for as long as any of the
            Patents remains in force or the Antibodies;

       (c)        subject to paragraph(a) above, the Licensee shall consent to
            the cancellation of any formal licence granted to it, or of any
            registration of it in any register, in relation to any of the
            Patents;

       (d)        subject as provided in this Clause 8.3.1 and 8.3.2, and except
            in respect of any accrued rights, and except with respect to clauses
            3.7.3, and 8.4 which shall survive termination of this Agreement,
            neither party shall be under any further obligation to the other.

8.3.2  In the event that this Agreement is terminated and at the time of
       termination Licensee and its Sub-Licensee(s) no longer intend to pursue
       development of Licensed Products, if requested by CUTS, Licensee agrees
       to negotiate in good faith with CUTS a royalty bearing licence on
       reasonable commercial terms to technology owned by Licensee that is
       useful for Licensed Product. In no event is Licensee obligated to grant
       such a license and Licensee and/or CUTS shall have the right to terminate
       such negotiations at any time by written note to the other party.

8.4    In the event that this Agreement and/or the rights and licences granted
       under this Agreement to Licensee are terminated, any sublicense granted
       under this Agreement shall remain in full force and effect as a direct
       licence between CUTS and the Sub-Licensee under the terms and conditions
       of this Agreement, subject to the Sub-Licensee agreeing to be bound to
       CUTS under such terms and conditions within thirty (30) days after CUTS

                                       13
<Page>

       provides written notice to the Sub-Licensee of the termination of
       Licensee's rights and licences under this Agreement. At the request of
       Licensee, CUTS will acknowledge to a Sub-Licensee, CUTS' obligations to
       the Sub-Licensee under this paragraph.

9.     GENERAL

9.1    FORCE MAJEURE. Neither Party shall have any liability or be deemed to be
       in breach of this Agreement for any delays or failures in performance of
       this Agreement which result from circumstances beyond the reasonable
       control of that Party, including without limitation labour disputes
       involving that Party. The Party affected by such circumstances shall
       promptly notify the other Party in writing when such circumstances cause
       a delay or failure in performance and when they cease to do so.

9.2    AMENDMENT. This Agreement may only be amended in writing signed by duly
       authorised representatives of CUTS and the Licensee.

9.3    ASSIGNMENT AND THIRD PARTY RIGHTS.

9.3.1  Subject to Clause 9.3.2 below and Licensee's right to grant sublicenses,
       neither Party shall assign this Agreement, nor any of the Patents or
       rights under the Patents, nor any of the Antibodies or rights to the
       Antibodies, without the prior written consent of the other Party, which
       shall not be withheld unreasonably.

9.3.2  Either Party may assign all its rights and obligations under this
       Agreement together with its rights in the Patents and the Antibodies to
       any company to which it transfers all or part of its assets or business
       or to a successor-in-interest or to an Affiliate, PROVIDED that the
       assignee undertakes to the other Party to be bound by and perform the
       obligations of the assignor under this Agreement.

9.4    WAIVER. No failure or delay on the part of either Party to exercise any
       right or remedy under this Agreement shall be construed or operate as a
       waiver thereof, nor shall any single or partial exercise of any right or
       remedy preclude the further exercise of such right or remedy.

9.5    INVALID CLAUSES. If any provision or part of this Agreement is held to be
       invalid, amendments to this Agreement may be made by the addition or
       deletion of wording as appropriate to remove the invalid part or
       provision but otherwise retain the provision and the other provisions of
       this Agreement to the maximum extent permissible under applicable law.

9.6    NO AGENCY. Neither Party shall act or describe itself as the agent of the
       other, nor shall it make or represent that it has authority to make any
       commitments on the other's behalf.

9.7    INTERPRETATION. In this Agreement:

       (a)        the headings are used for convenience only and shall not
            affect its  interpretation:

                                       14
<Page>

       (b)        references to persons shall include incorporated and
            unincorporated persons; references to the singular include the
            plural and vice versa; and references to the masculine include the
            feminine:

       (c)        references to Clauses and Schedules mean clauses of, and
            schedules to, this Agreement; and

       (d)        references to the grant of "exclusive" rights shall mean that
            the person granting the rights shall neither grant the same rights
            (in the same Field and Territory) to any other person, nor exercise
            those rights directly to the extent that and for as long as the
            Licensed Products are within Valid Claims of unexpired Patents.

9.8    NOTICES

9.8.1  Any notice to be given under this Agreement shall be in writing and shall
       be sent by first class mail or air mail, or by fax (confirmed by first
       class mail or air mail) to the address of the relevant Party set out at
       the head of this Agreement, or to the relevant fax number set out below,
       or such other address or fax number as that Party may from time to time
       notify to the other Party in accordance with this Clause 9.8. The fax
       numbers of the Parties are as follows: CUTS +44 (0)1223 332797;
       Licensee (001) 617 426 3071.

9.8.2  Notices sent as above shall be deemed to have been received three working
       days after the day of posting (in the case of inland first class mail),
       or seven working days after the date of position (in the case of air
       mail), or on the next working day after transmission (in the case of fax
       messages, but only if a transmission report is generated by the sender's
       fax machine recording a message from the recipient's fax machine,
       confirming that the fax was sent to the number indicated above and
       confirming that all pages were successfully transmitted).

9.9    DISPUTES. Except as provided in Clause 5.1, any disputes incapable of
       resolution shall be settled by mediation at the Centre for Dispute
       Resolution (CEDR) or if ineffective then either by court proceedings if
       considered expedient by the complainant or alternatively and if agreed at
       the time by sole arbitrator to be appointed, and to proceed according to
       the Rules of the International Chamber of Commerce(ICC) whose decision
       will be final.

9.10   LAW AND JURISDICTION. The validity, construction and performance of this
       Agreement shall be governed by English law and shall be subject to the
       nonexclusive jurisdiction of the English courts to which the parties
       hereby submit, except that a Party may seek an interim injunction in any
       court of competent jurisdiction.

9.11   FURTHER ACTION. Each Party agrees to execute, acknowledge and deliver
       such further instruments, and do all further similar acts, as may be
       necessary or appropriate to carry out the purposes and intent of this
       Agreement.

9.12   ANNOUNCEMENTS. Neither Party shall make any press or other public
       announcement concerning any aspect of this Agreement, or make any use of
       the name of the other Party in connection with or in consequence of this
       Agreement, without the prior written consent of the other Party, which
       consent shall not be withheld or delayed unreasonably. No

                                       15
<Page>

       consent shall be required where the disclosure is in conjunction with a
       financing or offering of securities or where required by applicable law,
       rule or regulation.

9.13   ENTIRE AGREEMENT. This Agreement, including its Schedules, sets out the
       entire agreement between the Parties relating to its subject matter and
       supersedes all prior oral or written agreements, arrangements or
       understandings between them relating to such subject matter. The Parties
       acknowledge that they are not relying on any representation, agreement,
       term or condition which is not set out in this Agreement.

9.14   Any matter or disagreement under Clause 5.1(b) which this Agreement
       specifies is to be resolved by arbitration shall be submitted to a
       mutually selected single arbitrator to so decide any such matter or
       disagreement. The arbitrator shall conduct the arbitration in accordance
       with the Rules of the International Chamber of Commerce, unless the
       Parties agree otherwise. If the Parties are unable to mutually select an
       arbitrator, the arbitrator shall be selected in accordance with the
       procedures of the International Chamber of Commerce. The decision
       rendered by the arbitrator shall be final and binding. Any arbitration
       pursuant to this section shall be held in London, England, or such other
       place as may be mutually agreed upon in writing by the Parties.

                                       16
<Page>

AGREED by the parties through their authorised signatories:-

For and on behalf of                      For and on behalf of
CAMBRIDGE UNIVERSITY TECHNICAL SERVICES   TOLERRX
LIMITED

/s/ David Secher                               /s/ D. J. Ringler
----------------------------              ----------------------------
signed                                    signed

DAVID SECHER                                   D. J. Ringler
----------------------------              ----------------------------
print name                                print name

DIRECTOR                                       CEO
----------------------------              ----------------------------
title                                     title

21 SEPTEMBER 2001                              25 September 2001
----------------------------              ----------------------------
date                                      date

                                       17
<Page>

                               AMENDMENT AGREEMENT

THIS AMENDMENT AGREEMENT dated December 31, 2001 is between:

1.  CAMBRIDGE UNIVERSITY TECHNICAL SERVICES LIMITED, an English Company,
    Register Number 1069886, whose registered office is at The Old Schools,
    Cambridge CB2 TS, England ("CUTS"); and

2.  TOLERRX, INC. a company incorporated in the State of Delaware whose register
    office is at 675 Mass Ave., Cambridge, MA 02139, USA (the "Licensee").

WHEREAS CUTS and Licensee entered into a Licence Agreement dated September 25,
2001 that, among other things, is directed to certain CD2 antibodies (the
"Licence Agreement");

WHEREAS CUTS and Licensee desired to amend the Licence Agreement, INTER ALIA, to
include a non-exclusive licence to the YNB Patents (as defined below);

WHEREAS on the date hereof, CUTS shall assign the YNB Patents to BRITISH
TECHNOLOGY GROUP INTER-CORPORATE LICENSING LIMITED, an English Company,
Registered Number 2501784, whose registered office is at 10 Fleet Place,
Limeburner Lane, London EC4M 7SB ("BTG") by way of assignment and
commercialisation agreements (the "BTG Agreements"). Under the BTG Agreements,
BTG shall grant CUTS a non-exclusive licence to the YNB Patents (with the right
to sub-license to the Licensee); and

In consideration of the sum of L 1 paid by each party hereto to the other (the
receipt of which is hereby acknowledged) IT IS AGREED as follows:

1.  All defined terms of the Licence Agreement shall have the same meaning in
this Amendment.

2.  The following is added to the definitions of Clause 1 of the Licence
Agreement:

    "YNB PATENTS: THOSE PATENTS AND PATENT APPLICATIONS IDENTIFIED IN SCHEDULE 2
    TOGETHER WITH ALL CONTINUATIONS, CONTINUATIONS IN PART, RE-ISSUES,
    EXTENSIONS, RE-EXAMINATIONS, DIVISIONS AND ANY PATENTS AND SUPPLEMENTARY
    PROTECTION CERTIFICATES THAT ARE BASED ON OR DERIVE PRIORITY THEREFROM."

3.  The patents and patent applications set out in the schedule hereto shall be
added to the Licence Agreement as Schedule 2.

4.  The following is added to the Licence Agreement as Clause 2.1(c):

    "(c) A NON-EXCLUSIVE LICENCE IN THE FIELD UNDER THE YNB PATENTS WITH RIGHT
    TO SUB-LICENSE, SUBJECT TO CLAUSE 2.5 BELOW, TO DEVELOP, MANUFACTURE, HAVE
    MANUFACTURED, USE, OFFER TO SELL, IMPORT AND SELL LICENSED PRODUCTS THAT
    INCORPORATE ANTIBODIES BUT ONLY IN THE FIELD IN THE TERRITORY. FOR THE
    AVOIDANCE OF DOUBT, NO RIGHTS ARE GRANTED UNDER THIS AGREEMENT TO USE THE
    PROCESS FOR THE PREPARATION OF AN ANTIBODY CHAIN UNDER THE YNB PATENTS OTHER
    THAN IN RELATION TO LICENSED PRODUCTS INCORPORATING ANTIBODIES."

<Page>

5.  The following shall be added to the Licence Agreement:

    "6.3.3 NOTWITHSTANDING 6.3.1, IF ANY WARNING LETTER OR OTHER NOTICE OF
           INFRINGEMENT IS RECEIVED BY CUTS, LICENSEE OR BTG, OR LEGAL SUIT OR
           OTHER ACTION IS BROUGHT AGAINST ANY OF THEM, ALLEGING INFRINGEMENT OF
           THIRD PARTY RIGHTS IN THE MANUFACTURE, USE OR SALE OF ANY LICENSED
           PRODUCTS BY USE OF ANY OF THE YNB PATENTS, THE RELEVANT ENTITY SHALL
           PROMPTLY PROVIDE FULL DETAILS TO THE OTHERS.

    6.3.4  NEITHER CUTS NOR LICENSEE SHALL TAKE ANY ACTION OR MAKE ANY
           STATEMENT, EXPRESS OR IMPLIED, CONCERNING THE VALIDITY OF ANY OF THE
           CLAIMS OF ANY OF THE YNB PATENTS, WITHOUT FIRST OBTAINING THE CONSENT
           OF BTG WHICH CONSENT SHALL NOT BE UNREASONABLY WITHHELD.

    6.3.5  BTG AS THE OWNER OF THE YNB PATENTS (AND NOT CUTS NOR LICENSEE) SHALL
           HAVE THE RIGHT TO ENFORCE AND DEFEND THE YNB PATENTS AS IT MAY SEE
           FIT, SAVE THAT BTG SHALL CONSULT WITH CUTS AND KEEP CUTS ADVISED WITH
           RESPECT THERETO. IT SHALL BE THE OBLIGATION OF CUTS (AND NOT BTG) TO
           CONSULT WITH LICENSEE AND KEEP LICENSEE ADVISED IN RESPECT OF SUCH
           ACTIONS."

6.  Clause 7.4 shall be renumbered as clause 7.5 and the following shall be
added to that clause 7.5:

    7.5    "BTG SHALL NOT HAVE ANY LIABILITY TO LICENSEE OR CUTS IN CONTRACT,
           TORT, NEGLIGENCE, BREACH OF STATUTORY DUTY OR OTHERWISE FOR ANY LOSS,
           DAMAGE, COSTS OR EXPENSES OF ANY NATURE WHATSOEVER INCURRED OR
           SUFFERED BY CUTS, LICENSEE OR ITS AFFILIATES OR SUB-LICENSEES AS A
           DIRECT OR INDIRECT RESULT OF THE USE OF THE YNB PATENTS".

7.  The following shall be added as a new clause 7.4:

    "7.4   LICENSEE SHALL INDEMNIFY BTG (AND ITS PARENT COMPANY, BTG PLC AND THE
           OTHER DIRECT OR INDIRECT SUBSIDIARIES OF BTG PLC AND THEIR RESPECTIVE
           DIRECTORS, OFFICERS AND EMPLOYEES) ON THE SAME BASIS AS THAT PROVIDED
           TO CUTS UNDER CLAUSES 2.5(c) AND 7.3 BUT IN RESPECT OF THE YNB
           PATENTS ONLY"

8.  CUTS and BTG agree that the assignment of the YNB Patents to BTG shall be
subject to the sublicense granted to Licensee to the YNB Patents under this
Amendment Agreement, and that the license that CUTS obtains under the BTG
Agreements to the YNB Patents shall not be terminable prior to the termination
or expiry of the licence of the YNB Patents from CUTS to Licensee.

9.  CUTS and Licensee agree that by virtue of the Contracts (Rights of Third
Parties) Act 1999 BTG (but no other person) not a party hereto shall have the
right to enforce Clauses 6.3.3, 6.3.4, 6.3.5, 7.4 and 7.5 of the Licence
Agreement (as amended by this Amendment Agreement) as if it was a party to it.

10. The Licence Agreement is amended as provided herein as of the date first
written above. All other terms and provisions of the Licence Agreement shall be
unaffected by this Amendment.

                                        2
<Page>

    In order to induce Licensee and CUTS to enter into this Amendment Agreement
and to induce CUTS to assign the YNB Patents to BTG, BTG agrees that the license
to CUTS under the YNB Patents shall continue so long as the YNB Patents are
sublicensed to Licensee under this Amendment and shall, if necessary, survive
any earlier termination of the BTG Agreements.

Agreed by the parties through their authorized signature.

CAMBRIDGE UNIVERSITY                                TOLERRX, INC.
TECHNICAL SERVICES LIMITED

By: /s/ R. C. Jennings                              By: /s/ D. J. Ringler
   ----------------------                              ----------------------

BRITISH TECHNOLOGY GROUP
INTER-CORPORATE LICENSING LIMITED

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

                                        4

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