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                                                                    EXHIBIT 10.9

                             DATED DECEMBER 5, 2000

                           (1) ISIS INNOVATION LIMITED

          (2) THE CHANCELLOR MASTERS AND SCHOLARS OF THE UNIVERSITY OF
                                     OXFORD

                                (3) TOLERRX, INC

                         Licence of Certain Improvements
                       to anti-CD4 and anti-CD8 Antibodies

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[*******] 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.

THIS AGREEMENT dated December 5, 2000 is made BETWEEN:

(1)  ISIS INNOVATION LIMITED whose registered office is at University Offices,
     Wellington Square, Oxford OX1 2JD, England ("the Licensor");

(2)  THE CHANCELLOR MASTERS AND SCHOLARS OF THE UNIVERSITY OF OXFORD whose
     administrative offices are at Wellington Square, Oxford OX1 2JD, England
     ("the University"); and

(3)  TOLERRX, INC, a Delaware Corporation whose principal place of business is
     at 675 Mass Ave., Cambridge, MA 02139 ("the Licensee"):-

1.   1.     SUBJECT-MATTER

     1.1    This Agreement relates to the intellectual property and know how
            described in the Schedule.

     1.2    For the purposes of this Agreement, the following definitions apply:

            (a)  "Affiliate" means with respect to a party, an entity that
                 controls, is controlled by or is under common control with a
                 party. As used herein, "control" means possession, of the power
                 to direct or cause the direction of the management and policies
                 whether through the ownership of voting securities, by contract
                 or otherwise.

            (b)  "Antibody(ies)" means, individually and collectively, any and
                 all antibodies (or portions thereof) encoded by genetic
                 material of a Cell Line.

            (c)  "Cell Line(s)" means, individually and collectively (i) the
                 cell lines and cell banks of the Schedule and genetic material
                 contained therein.

            (d)  "Know-How" means the know-how described in the Schedule.

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            (e)  "Licensed Patents" means any patent application or patent
                 anywhere in the world that is owned by the Licensor and that
                 claims Licensed Technology.

            (f)  "Licensed Product" means any product or composition that is or
                 includes one or more Antibodies.

            (g)  "Licensed Technology" means, individually and collectively,
                 Cell Lines, Antibodies and Know-How.

            (h)  "Net Sales" means the gross selling price of the Licensed
                 Product in the form in which it is sold or leased to a customer
                 after regulatory approval thereof by Licensee or its
                 sublicensee (as recorded in the standard customer pricing
                 records of the Licensee or the Licensee's sub-licensee if and
                 to the extent that such records are applicable to the Licensed
                 Product in question), after deducting:

                 (i) transportation charges or allowances, including freight
                 pickup allowances, and shipping packaging costs, if any; (ii)
                 trade, quantity or cash discounts, if any, allowed or paid;
                 (iii) credits or allowances, if any, given or made on account
                 of returns, any and all Federal, state or local government
                 rebates, whether in existence now, or enacted at any time
                 during the term of this Agreement, rejections, recalls or
                 destruction (voluntarily made or requested or made by an
                 appropriate government agency, sub-division or department) for
                 the Licensed Product; (iv) any tax, excise or other
                 governmental charge upon or measured by the production, sale,
                 transportation, delivery or use of the Licensed Product,
                 exclusive of income tax; (v) any government mandated surcharge,
                 levy, tax or

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                 assessment to fund a compensation program or reserve for
                 persons injured or alleged to be injured by the Licensed
                 Product; and (vi) a reasonable allowance for bad debt.

            It is understood that a Licensed Product may be marketed in a
            combination package containing other products or materials or in
            combination with active ingredients that are not Antibodies. In such
            a case "Net Sales", for the purpose of determining royalty payments
            on the combination package, shall be calculated by multiplying the
            Net Sales of that combination package by the fraction A/(A+B); where
            A is the gross selling price, during the royalty-paying period in
            question, of the Licensed Product marketed separately and B is the
            aggregate of the gross selling prices, during the royalty-paying
            period in question, of the other products or materials marketed
            separately. In the event that no such separate sales or leases are
            made of the Licensed Product or any of the other products or
            materials in such combination package during the royalty-paying
            period in question, "Net Sales," for the purpose of determining
            royalty payments, shall be calculated by multiplying the Net Sales
            of the combination package by the fraction C/(C+D); where C is the
            standard fully-absorbed cost to the Licensee of the Licensed
            Product, and D is the aggregate of the standard, fully-absorbed
            costs to the Licensee of the other products or materials, such costs
            being determined by using the Licensee's standard accounting
            procedures, which shall be in accordance with generally accepted
            practice.

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2.   GRANT

 2.1 (a)    Subject to Section 2.1(b), Licensor reserves the right to grant to
            the University of Oxford ("University") a licence for the University
            and every employee, student, agent and appointee of the University
            to use and publish (notwithstanding clause 2.3) the Licensed
            Technology and any Licensor Improvement made under clause 2.8 for
            academic and research purposes: and this will include the right for
            the University to use the Licensed Technology as enabling technology
            in other research projects (including projects which benefit from
            third-party funding received from commercial entities).

     (b)    Notwithstanding anything herein to the contrary, Licensor and
            University agree, (i) not to disclose or publish sequence
            information with respect to Antibody and/or Cell Line to any person
            or entity other than Licensee or as permitted by Section 2.5(b);
            (ii) not to transfer Antibody or Cell Line to any person or entity
            other than Licensee or students or employees of University, provided
            that any student or employee agrees not to transfer Antibody or Cell
            Line, or as permitted by Section 2.5(b).

2.2  (a)    The Licensor grants to the Licensee:

          (i)   a licence to use the Cell Lines and the Licensed Patents to the
     extent that the Licensed Patents relate to the Cell Lines worldwide; and

          (ii)  a licence in, to and under the Antibodies and the Licensed
     Patents to the extent that the Licensed Patents relate to the Antibodies
     worldwide to make, have made, use, sell, offer to sell, and import Licensed
     Product (together, the "Licences"). Subject only to clause 2.1, the Licence
     shall be exclusive.

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     (b)    Licensor agrees to provide Licensee with samples of the Cell Lines
            and vectors of the Schedule and with the Know-How.

2.3  During the term of this Agreement, it is contemplated that each party will
     disclose to the other proprietary and confidential technology, inventions,
     technical information, biological materials and the like which are owned or
     controlled by the party providing such information or which that party is
     obligated to maintain in confidence and which is designated by the party
     providing such information as confidential ("Confidential Information").
     For this purpose, Confidential Information includes the Licensed Technology
     to the extent that such Licensed Technology is not disclosed by any patents
     or published patent applications. Subject to subclause 2.4 and 2.5, each
     party agrees to retain the other party's Confidential Information in
     confidence and not to disclose any such Confidential Information to a third
     party without the prior written consent of the party providing such
     information and to use the other party's Confidential Information only for
     the purposes of this Agreement, which obligation shall terminate five (5)
     years after the expiration or termination of this Agreement.

2.4  The obligations of confidentiality will not apply to Confidential
     Information which:

     (i)    was known to the receiving party or generally known to the public
            prior to its disclosure hereunder; or

     (ii)   subsequently becomes known to the public by some means other than a
            breach of this Agreement;

     (iii)  is subsequently disclosed to the receiving party by a third party
            having a lawful right to make such disclosure;

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     (iv)   is required by law or BONA FIDE legal process to be disclosed,
            provided that the party required to make the disclosure takes all
            reasonable steps to restrict and maintain confidentiality of such
            disclosure and provides reasonable notice to the party providing the
            Confidential Information; or

     (v)    is approved for release by the parties, or

     (vi)   is independently developed by the employees or agents of either
            party without any knowledge of the Confidential Information provided
            by the other party.

     (vii)  is disclosed to a government body, agency or authority as required
            by applicable law, rule, or regulation or in order to obtain
            regulatory approval for or authorization to market and sell Licensed
            Product.

2.5   (a)        Notwithstanding the foregoing, the parties shall have the right
                 to disclose Confidential Information to a third party who
                 undertakes an obligation of confidentiality and non-use with
                 respect to such information, at least as restrictive as
                 Licensee's obligation under subclause 2.4 and 2.5.

       (b)       Notwithstanding the foregoing, the University and every
                 employee, student, agent and appointee of the University shall
                 have the right to:

                 (i)   disclose Confidential Information, to the extent that it
                       relates to the Licensed Technology, to other employees
                       and students of the University for academic and research
                       purposes only so long as such employees and students of
                       the University are subject to obligations of
                       confidentiality; and

                 (ii)  transfer Antibody to any academic collaborator to use
                       solely for academic and research purposes (not including
                       commercially funded

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                       research purposes) for in vitro research provided that
                       the academic collaborator signs a material transfer
                       agreement in the form of the University material transfer
                       agreement attached as Exhibit A.

2.6  Each of University, Licensor and Licensee warrants and represents to the
     other that it has the full right and authority to enter into this
     Agreement, and that it is not aware of any impediment which would inhibit
     its ability to perform the terms and conditions imposed on it by this
     Agreement.

2.7  Licensor warrants and represents that except for rights of Cambridge
     University (i) it owns all right, title and interest in and to Licensed
     Technology, (ii) it has not licensed or assigned any right or interest in
     or to Licensed Technology to any third party; (iii) it has the right to
     grant the rights granted hereunder; (iv) that, so far as it is aware, after
     a reasonable investigation, the granting of such rights does not require
     the consent of a third party; and (v) that, so far as it is aware, after a
     reasonable investigation, there are and will be no outstanding agreements,
     assignments or encumbrances entered into or incurred by the Licensor
     inconsistent with the provisions of this Agreement.

2.8  The Licensor will communicate to the Licensee any improvements which the
     Licensor and the University makes to the Licensed Technology, to the extent
     that the Licensor is aware of the improvements made by the University (the
     "Licensor Improvements"). The Licensor and the Licensee may enter into
     negotiations with respect to the Licensee licensing the Licensor
     Improvements from the Licensor. Subject to clause 2.1, neither the Licensor
     nor the University will grant rights to exploit or use the Licensor
     Improvements, even if the Licensee does not enter into a licence in respect
     of the

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     Licensor Improvements, so long as the Licensor Improvements remain
     confidential for the purposes of clause 2.3.

2.9  At the request of the Licensee in writing, the Licensor agrees to grant to
     the Licensee a non-exclusive, [*******] licence to use any improvements
     which:

     (a) are made to the Licensed Technology by academic collaborators in
         accordance with a material transfer agreement entered into under clause
         2.5(b)(ii); and

     (b) have been assigned by the University to the Licensor.

     The Licensee may, at any time, subject to negotiating the terms of the
     licence with the Licensor, request the Licensor to convert the
     non-exclusive [*******] licence to an exclusive, [*******] licence.

3.   UNDERTAKINGS BY AND RIGHTS OF THE LICENSEE

3.1  Except as provided in Section 9.6, the Licensee will not assign the
     Licence. The Licensee may grant sub-licences, and may disclose to
     sub-licensees such of the Licensed Technology as is necessary for the
     exercise of the rights sub-licensed. Immediately following the grant of
     each sub-licence, the Licensee will forward to the Licensor in writing a
     note of the name and address of the sub-licensee, a description of the
     technology sub-licensed and its intended applications, and confirmation of
     the duration of the sub-licence. By controlling the wording of its
     contracts with sub-licensees, the Licensee will ensure that the
     sub-licensees are subject to the confidentiality obligations of this
     Agreement in order to protect the intellectual property rights in the
     Licensed Technology, and the interests of the Licensor therein; and that in
     no circumstances do the terms of any sub-licence in force from time to time
     conflict with the terms of this Agreement.

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

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3.2  The Licensee will be responsible for the design and construction of the
     Licensed Products and the Licensor shall have no responsibility or
     liability in that respect.

3.3  The Licensee will ensure that the Licensed Products and the packages
     associated with them are marked suitably with any relevant patent or patent
     application numbers of Licensed Patents to satisfy the laws of each of the
     countries in which the Licensed Products are sold or supplied and in which
     they are covered by the claims of any patent or patent application of
     Licensed Patents, to the intent that the Licensor shall not suffer any loss
     or loss of damages in an infringement action.

3.4  The Licensee agrees not to change its name to or trade under any name which
     includes the word "Oxford".

3.5  (a) Taking into account the complexity, and stage of development of the
     Licensed Technology, the Licensee shall select and use reasonable
     commercial efforts under the circumstances to research, develop and then
     commercialize the Licensed Technology. The efforts of a sublicensee of
     Licensee or a person or entity performing work for Licensee under a
     contract negotiated at arm's length shall be considered as efforts of
     Licensee.

     (b) In the event that Licensor reasonably believes that Licensee is not
     making reasonable commercial efforts under the circumstances to research,
     develop and then commercialize the Licensed Technology pursuant to
     subclause 3.5(a), then Licensor shall provide written notice to Licensee
     which specifies Licensor's basis for such belief and what additional
     efforts Licensor believes should be made by Licensee. Upon receipt of such
     written notice, Licensor and Licensee shall enter into good faith
     negotiations in order to reach mutual agreement as to what efforts by
     licensee shall

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     satisfy the requirements of subclause 3.5(a), and if such mutual agreement
     is not reached within thirty (30) days after receipt of such written
     notice, then the parties agree to submit to arbitration pursuant to
     subclause 9.8 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)  Within sixty (60) days after the end of each calendar year, Licensee shall
     provide Licensor with a report detailing progress made and steps taken
     during the calendar year in:

     (i)    applying for and defending any patent, design, trade mark, copyright
            and other registrations which may be available for the protection of
            the Licensed Technology;

     (ii)   taking legal action against any misappropriation or infringement of
            the Licensed Technology of which the Licensee becomes or is made
            aware;

     (iii)  developing the Licensed Technology in order to facilitate its
            commercial exploitation;

     (iv)   promoting and marketing Licensed Products.

3.6  In the event that the Licensed Technology includes potentially patentable
     subject matter (an "Invention"), Licensee shall file, prosecute and
     maintain patent applications and patents directed to Inventions in the name
     of the Licensor through patent counsel selected by Licensee and approved by
     the Licensor (which approval shall not be unreasonably withheld or delayed)
     who shall consult with and keep Licensor 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 Licensed Patents
     in

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     the United States, European Patent Office and subsequent national filings
     which derive from it, and Japan and any other foreign countries mutually
     agreed by the Licensee and the Licensor. If, in good faith, the Licensor
     believes a patent may be granted in a country but the Licensee is unwilling
     to bear the cost and expense for filing, prosecuting and maintaining the
     patent in that country, the Licensor may instruct the patent counsel
     selected by the Licensee at its own cost to file, prosecute or maintain the
     Licensed Patents in that country, and the country in question shall be
     removed from the scope of this Agreement.

3.7  With respect to any Licensed Patents, each patent application, office
     action, response to office action, request for terminal disclaimer, and
     request for reissue or re-examination of any patent issuing from such
     application shall be provided to Licensor. Licensor shall have the right to
     take any action that in its judgement is necessary to preserve such
     Licensed Patents.

3.8  Licensor and the University shall cooperate with Licensee with respect to
     filing, prosecution and maintenance of Licensed Patents and shall use
     reasonable endeavours to cause the inventors to cooperate.

3.9  (a) If any of the Licensed Technology or Licensed Patents under which
     Licensee is licensed hereunder is infringed by a third party, Licensee
     shall have the right and option but not the obligation to bring an action
     for infringement, at its sole expense, against such third party in the name
     of Licensor and/or in the name of Licensee, and to join Licensor as a party
     plaintiff if required. Licensee shall promptly notify Licensor of any such
     infringement and shall keep Licensor informed as to the prosecution of any
     action for such infringement. No settlement, consent judgment or other
     voluntary final disposition

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     of the suit which adversely affects Licensed Technology or Licensed Patents
     may be entered into without the consent of Licensor, which consent shall
     not unreasonably be withheld.

(b)  Any recovery of damages by Licensee for any such suit shall be applied
     first in satisfaction of any unreimbursed expenses and legal fees of
     Licensee relating to the suit and the remainder thereof shall be retained
     by Licensee and treated as Net Sales subject to royalty under this
     Agreement.

3.10 In the event that Licensee elects not to pursue an action for infringement,
     upon written notice to Licensor by Licensee that an unlicensed third party
     is an infringer of Licensed Technology or Licensed Patents, Licensor shall
     have the right and option, but not the obligation at its cost and expense
     to initiate infringement litigation and to retain any recovered damages.

3.11 In any infringement suit either party may institute to enforce the rights
     in Licensed Technology or Licensed Patents pursuant to this Agreement, the
     other party hereto shall, at the request 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. All reasonable out-of-pocket
     costs incurred in connection with rendering cooperation requested hereunder
     shall be paid by the party requesting cooperation.

3.12 The Licensee will communicate to the Licensor any improvements which the
     Licensee makes to the Licensed Technology (the "Licensee's Improvements").
     The Licensee and the Licensor may enter into negotiations with respect to
     the Licensor licensing the

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     Improvements from the Licensee, but Licensee shall not be under any
     obligation to enter into such a license.

4.   4.     PAYMENT

     4.1    The Licensee agrees to pay to the Licensor the sum of [*******] US
            dollars (US $[*******]) on the signature of this Agreement.
            Thereafter, for so long as any Licensed Products are used or
            marketed by the Licensee and its sub-licensees, the Licensee will
            pay to the Licensor a royalty equal to [*******] of the Net Sales
            of all such Licensed Products.

     4.2    The Licensee will pay to the Licensor the following non-refundable
            non-creditable milestone payments within sixty (60) days after the
            occurrence of the specified events with the total milestones due
            under this Section 4.2 being [*******]

<Table>
<Caption>
            EVENT                                                      AMOUNT
            <S>                                                       <C>
            Initiation of Phase II trials for a Licensed              [*******]
            Product
            Initiation of Phase III trials for a Licensed             [*******]
            Product
</Table>

     4.3    The Licensee shall provide the Licensor with a royalty report within
            sixty (60) days after the close of each calendar quarter for each
            Licensed Product marketed, and for each Licensed Product brought
            into use by or within the groups of the Licensee and sub-licensees.
            Each report shall state the Net Sales and provide a calculation of
            the royalties due, and shall be accompanied by payment to the
            Licensor of the royalties due.

     4.4    In marketing the Licensed Products, the Licensee will not accept or
            solicit any non-monetary consideration without the prior written
            consent of the Licensor.

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

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            The use by the Licensee of a commercially reasonable quantity of
            Licensed Products for promotional sampling shall not violate this
            prohibition.

     4.5    In the case of a Licensed Product which is not marketed, but rather
            manufactured by the Licensee or a sub-licensee for use by that
            party, or within that party's group, the term "Net Sales" shall mean
            [*******] of the gross selling price of the Licensed Product in the
            form in which it is normally sold, as recorded in the standard
            customer pricing records of the Licensee or the sub-licensee or
            sub-sub-licensee if and to the extent that such records are
            applicable to the Licensed Product in question, or as ascertained by
            applying reasonable uplifts to the standard, fully-absorbed cost of
            the Product to the Licensee, sub-licensee or sub-sub-licensee if and
            to the extent that those records are not so applicable. For the
            avoidance of doubt, this clause shall not apply to Licensed Product
            used by the Licensee or within the Licensee's group solely for the
            purposes of internal research or solely for the purposes of internal
            quality control.

     4.6    For the purpose of calculating running-earned royalties under this
            clause, a Licensed Product shall be regarded as sold or leased by
            the Licensee or a sub-licensee when invoiced, or if not invoiced,
            when shipped or delivered by the Licensee or sub-licensee. If a
            Licensed Product marketed by the Licensee or a sub-licensee is sold
            to an Affiliate for re-sale, the royalty on each such Licensed
            Product so re-sold shall be calculated on the highest of the prices
            at which it is (i) marketed or sold to an Affiliate for re-sale or
            (ii) re-sold; provided, however, that in no event shall royalty be
            paid more than once on each Licensed Product.

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

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     4.7    If the Licensee or a sub-licensee is obliged to pay royalties to
            third parties (other than the Licensee's Affiliate, for the right to
            make, use or sell a Licensed Product, then the Licensee shall be
            entitled to deduct from the royalty payment due to the Licensor a
            portion of the royalty payment actually made to such third party as
            the Licensee has negotiated with the Licensor, but in any event, not
            greater than [*******] of the royalty payment due to the Licensor.

     4.8    For the avoidance of doubt, any payment made by a [*******] relevant
            for the purposes of calculating Net Sales.

     4.9    All payments provided for under this clause 4 shall be made to the
            Licensor in US dollars without any deductions apart from any tax
            which is required to be withheld under applicable local law. Any
            exchange of currency made to calculate sales for the purpose of this
            clause 4 shall be determined as at the last business day of each
            quarter, using the average of the average daily buying and selling
            rates quoted by Barclays Bank plc during that quarter. Where the
            Licensee is required to withhold tax under applicable local law, the
            Licensee shall deduct such tax, pay it to the relevant taxing
            authority, and supply the Licensor with a Certificate of Tax
            Deduction at the time of payment to the Licensor. The parties shall
            co-operate under any applicable Double Taxation Treaty so that, if
            possible, payments are made gross or, if payment gross is not
            possible, the Licensor obtains appropriate relief under the Treaty.

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

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     4.10   Where the Licensee is obliged to make a payment to the Licensor
            under this Agreement which attracts value-added, sales, use, excise
            or other similar taxes or duties, the Licensee shall be responsible
            for paying such taxes and duties.

     4.11   In the event that full payment of any amount due from the Licensee
            to the Licensor under this Agreement is not made by any of the dates
            stipulated, the Licensee shall be liable to pay interest on the
            amount unpaid at the rate of two percent (2%) over the base rate for
            the time being of Barclays Bank plc, from the date when payment was
            due until the date of actual payment.

     4.12   The Licensee and the Licensee's sub-licensees shall keep complete
            and accurate accounts of all Licensed Products used and marketed;
            and will permit the Licensor through an independent certified
            accountant to audit such accounts on at least thirty (30) days'
            written notice and no more than once each calendar year solely for
            the purpose of determining the accuracy of the royalty reports and
            payments. The Licensee's obligation and that of the Licensee's
            sub-licensees concerning audit of their accounts shall terminate as
            to any report three (3) years after the date of that report.

5.   5.     DURATION AND TERMINATION

     5.1    Subject to clause 5.2, this Agreement shall take effect on the date
            of signature and (subject to the remaining sub-clauses of this
            clause) shall continue in force until the expiration of the period
            of ten (10) years from the date on which a Licensed Product is first
            put on the market by the Licensee or one of its sub-licensees, after
            which time Licensee shall have a fully paid-up license under Section
            2.2 and no further royalties will be due.

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     5.2    Insofar as the rights and obligations in this Agreement concern
            territories in which the commercial practice of the Licensed
            Technology is covered by a claim being prosecuted in a patent
            application filed by the Licensee that is a Licensed Patent, or by a
            valid claim of an unexpired patent which issues in response to such
            an application, the royalty obligations shall extend for those
            territories beyond the period defined in clause 5.1 if and for so
            long as the commercial practice of the Licensed Technology is
            covered in those territories.

     5.3    If Licensee commits a material breach of clause 2.3, 3.1, 3.6 and 4
            of this Agreement or fails to exert the efforts determined by the
            parties or by arbitration under clause 3.5(b), and such breach or
            failure is not remedied within the period allowed by notice given by
            Licensor in writing calling on the Licensee to remedy such failure
            (such period being not less than thirty (30) days), the Licensor may
            by further written notice terminate this Agreement immediately.

     5.4    The Licensee may terminate this Agreement at any time by serving not
            less than three (3) months' written notice on the Licensor.

     5.5    The Licensor shall have the right to terminate this Agreement by
            serving written notice on the Licensee in the event that Licensee
            files a voluntary petition in bankruptcy, is adjudicated a bankrupt,
            makes a general assignment for the benefit of creditors, or fails to
            discharge within 30 days an involuntary petition in bankruptcy filed
            against it. Such notice may terminate this Agreement either
            immediately or at the end of such period as the Licensor shall
            select.

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     5.6    Clauses 2.3, 2.4, 2.5, 4 (in relation to any payments which have
            fallen due but not been made), 5.1, 5.2, 5.6, 5.8, 5.9 6, 7, 8, 9.4
            and 9.8 shall survive the termination or expiration of this
            Agreement, for whatever reason.

     5.7    This Agreement may be terminated only as set forth in this clause 5.

     5.8    Upon any termination of this Agreement, Licensee, at its option,
            shall be entitled to finish any work-in-progress which is completed
            within six (6) months of termination of this Agreement and to sell
            any completed inventory of a Licensed Product covered by this
            Agreement which remains on hand as of the date of the termination,
            so long as Licensee pays to Licensor the royalties applicable to
            said subsequent sales in accordance with the same terms and
            conditions as set forth in this Agreement.

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

6.   LIABILITY

     6.1    (a)  The Licensee agrees to indemnify the Licensor and the
            University and hold the Licensor and the University harmless from
            and against any and all claims,

18
<Page>

            damages and liabilities asserted by third parties and arising
            directly or indirectly from use of the Licensed Technology or the
            sale of Licensed Products by the Licensee and its sub-licensees and
            sub-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
            and solely attributable to the intentional misconduct of the
            Indemnitees.

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

            (d)  Licensor and the University shall notify Licensee promptly of
            any claim or threatened claim under this subclause 6.1(a) and shall
            fully cooperate with all reasonable requests of Licensee with
            respect thereto.

     6.2    The Licensor makes no representation or warranty that advice given
            to the Licensee pursuant to this Agreement by any employee, student,
            agent or appointee of the Licensor or of the University, or the use
            of any works, designs or information which they, the Licensor or the
            University provide in connection with this Agreement, will not
            result in infringement of third-party rights.

     6.3    The Licensee undertakes to make no claim against any employee,
            student, agent or appointee of the Licensor or of the University
            which seeks to enforce against any of them any liability whatsoever
            in connection with this Agreement or its subject-matter. It is
            understood that this Clause 6.3 does not prevent Licensee from
            asserting a claim(s) against Licensor or University.

19
<Page>

     6.4    The liability of any party for any breach of this Agreement, or
            arising in any other way out of the subject-matter of this
            Agreement, will not extend to loss of business or profit or to any
            indirect or consequential damages or losses.

     6.5    Except in the case of fraud or intentional misconduct or intentional
            breach of this Agreement or a breach of a warranty where Licensor
            had knowledge that the warranty was untrue or by the investigation
            undertaken by the University the Licensor would have known that the
            warranty was untrue, Licensor's maximum liability with respect to
            payment of damages awarded to the Licensee by a court of law under
            or otherwise in connection with this Agreement or its subject
            matter, shall be the return of all royalty, milestone and up-front
            payments paid by the Licensee under this Agreement, together with
            interest on the balance of such moneys from time to time
            outstanding, accruing from day to day at two percent over the
            Barclays Bank plc base rate from time to time in force and
            compounded annually as at 31 December and if the damages awarded
            exceed such amount, such excess may be credited against future
            royalties and milestones owed by Licensee under this Agreement, as
            and when they become due.

     6.6    The University's maximum liability with respect to payment of
            damages awarded to the Licensee by a court of law under or otherwise
            in connection with this Agreement or its subject matter, shall not
            exceed the return of all royalty, milestone and up-front payments
            paid by the Licensee to the Licensor under this Agreement less any
            return of those royalties, milestones or up-front payments by the
            Licensor to the Licensee under clause 6.5, together with interest on
            the balance of such moneys from time to time outstanding, accruing
            from day to day

20
<Page>

            at two percent over the Barclays Bank plc base rate from time to
            time in force and compounded annually as at 31 December and if the
            damages awarded exceed such amount, such excess may be credited
            against future royalties and milestones owed by Licensee under this
            Agreement less any return of those royalties, milestone or up-front
            payments by the Licensor to the Licensee under clause 6.5, as and
            when they become due.

     6.7    If any sub-clause of this clause 6 is held to be invalid or
            unenforceable under any applicable statute or rule of law, then it
            shall be deemed to be omitted, and if as a result any party becomes
            liable for loss or damage which would otherwise have been excluded,
            then such liability shall be subject to the remaining sub-clauses of
            this clause 6.

7.   FORCE MAJEURE

     If the performance by either party of any of its obligations under this
     Agreement (other than an obligation to make payment) shall be prevented by
     circumstances beyond its reasonable control, then such party shall be
     excused from performance of that obligation for the duration of the
     relevant event.

8.   NOTICES

     The Licensor's representative for the purpose of receiving payments and
     notices shall until further notice be:

               The Managing Director
               Isis Innovation Limited
               Ewert House
               Ewert Place
               Summertown
               Oxford OX2 7DD
               England

21
<Page>

     The Licensee's representative for the purpose of receiving notices shall
     until further notice be:

               TOLERRX, Inc.
               675 Mass. Ave.
               Cambridge, MA 02139
               Attn: CEO

9.   GENERAL

     9.1    Clause headings are inserted in this Agreement for convenience only,
            and they shall not be taken into account in the interpretation of
            this Agreement.

     9.2    Nothing in this Agreement shall create, imply or evidence any
            partnership or joint venture between the Licensor and the Licensee
            or the relationship between them of principal and agent.

     9.3    This Agreement constitutes the entire agreement between the parties
            with regard to the Licence. Specifically, but without limitation,
            this Agreement does not impose or imply any obligation on the
            Licensor or the University to conduct development work: any
            arrangements for such work shall be the subject of a separate
            agreement between the University and the Licensee. Any variation of
            this Agreement shall be in writing and signed by authorised
            signatories for both parties.

     9.4    This Agreement shall be governed by English Law. Except as provided
            in Section 9.8, Licensee submits to the non-exclusive jurisdiction
            of the English courts with respect to any dispute which may arise
            out of or in connection with this Agreement.

22
<Page>

     9.5    If any one or more clauses or sub-clauses of this Agreement would
            result in this Agreement being prohibited pursuant to any applicable
            competition law, then it or they shall be deemed to be omitted. The
            parties shall uphold the remainder of this Agreement, and shall
            negotiate an amendment which, as far as legally feasible, maintains
            the economic balance between the parties.

     9.6    This Agreement shall not be assignable by either of the parties
            without the prior written consent of the other party (which consent
            shall not be unreasonably withheld), except that Licensee without
            the consent of Licensor may assign this Agreement to an Affiliate or
            to a successor in interest or to a transferee of all or
            substantially all of the portion of the business to which this
            Agreement relates.

     9.7    Subject to the limitations on assignment herein, this Agreement
            shall be binding upon and inure to the benefit of said successors in
            interest and assigns of Licensee and Licensor. Any such successor or
            assignee of a party's interest shall expressly assume in writing the
            performance of all the terms and conditions of this Agreement to be
            performed by said party.

     9.8    Any dispute, controversy or claim arising under subclause 3.5(b) of
            this Agreement will be submitted to mediation in accordance with the
            WIPO Mediation Rules. The place of mediation will be London. The
            language to be used in the mediation will be English. If, and to the
            extent that, any such dispute, controversy or claim has not been
            settled pursuant to the mediation within 60 days of the commencement
            of the mediation, it will, upon the filing of a request for
            arbitration by either party, be referred to and finally determined
            by arbitration

23
<Page>

            in accordance with the WIPO Arbitration Rules. The arbitral tribunal
            will consist of a sole arbitrator. The place of arbitration will be
            London.

     9.9    The parties to this Agreement intend that by virtue of the Contracts
            (Rights of Third Parties) Act 1999 the people referred to in clause
            6.3 will be able to enforce the terms of clause 6.3 of this
            Agreement as if the people referred to in clause 6.3 were a party to
            it.

24
<Page>

AS WITNESS the hands of authorised signatories for the parties on the date first
mentioned above

SIGNED for and on behalf of
Name: D. J. Ringler
     ------------------------
Positions: President
          -------------------
Signature: /s/ D. J. Ringler
          -------------------

SIGNED for and on behalf of
ISIS INNOVATION LTD
Name: T. Cook
      -----------------------
Position: Director
         --------------------
Signature: /s/ T. Cook
          -------------------

SIGNED for and on behalf of
THE CHANCELLOR
MASTER AND SCHOLARS OF THE
UNIVERSITY OF OXFORD:
Name: S.R. Clements
     ------------------------
Position: Director
         --------------------
Signature: /s/ S.R. Clements
          -------------------

Please note that these signatures are subject to the underlying documents having
been changed as we discussed and are conditional upon us receiving signed copies
of the original documents in agreed form.

<Page>

THIS AMENDMENT AGREEMENT, dated December 19, 2002 (the "Effective Date") is made
BETWEEN:

         (1)     ISIS INNOVATION LIMITED, a company registered in England (No.
         02199542), whose registered office is at University Offices, Wellington
         Square, Oxford OX1 2JD, England (the "Licensor"); and

         (2)     THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF
         OXFORD whose administrative offices are at the University Offices,
         Wellington Square, Oxford OX1 2JD, England ("the University"); and

         (3)     TOLERRX, INC., a Delaware corporation whose principal place of
         business is at 300 Technology Square, Cambridge, MA 02139 (the
         "Licensee").

WHEREAS, the parties have entered into a License Agreement dated December 5,
2000 that is directed to Anti-CD4 and Anti-CD8 Antibodies (the "License
Agreement"); and

WHEREAS, the parties wish to amend the License Agreement.

In consideration of the sum of $1 (United States) paid by each party hereto to
each of the other parties, IT IS AGREED as follows:

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

  2. Clause 3.1 of the License Agreement shall be replaced in its entirety with
     the following:

     3.1 The Licensee:

            3.1.1  will not assign the License, except as provided in clause 9.6
of this Agreement.
            3.1.2  may grant sub-licenses, and may disclose to sub-licensees
such of the Licensed Technology as is necessary for the exercise of the rights
sub-licensed.
            3.1.3  will, immediately following the grant of each sub-license,
forward to the Licensor in writing a note of the name and address of the
sub-licensee, a description of the technology sub-licensed and its intended
applications, and confirmation of the duration of the sublicense.
            3.1.4  will ensure that any and all sub-licensees are subject to
reasonable obligations of confidentiality sufficient to protect the intellectual
property rights in the Licensed Technology and the interests of the Licensor
therein
            3.1.5, will, except in respect of the Genentech Agreement, take
reasonable steps to ensure that the terms of any sublicense in force from time
to time do not conflict with the terms of this Agreement.
            3.1.6  will ensure that the terms of the Genentech Agreement do not
conflict with clauses 2.1 and 2.5(b) of this Agreement.
            3.1.7  acknowledges that, notwithstanding the above clauses 3.1.5
and 3.1.6, clause 5.9 will remain in full force and effect, and Licensee's
obligations

<Page>

to Licensor and University under clause 4.4 and clause 6 will remain in full
force and effect.
            3.1.8  agrees that nothing in any sub-license in force from time to
time absolves the Licensee of its obligations to pay royalties under this
Agreement, or its other obligations as set out in this Agreement.

  3. Clause 3.3 of the License Agreement shall be replaced in its entirety with
the following:

     3.3 The Licensee will take reasonable endeavours to ensure that the
     Licensed Products and the packages associated with them are marked suitably
     with any relevant patent or patent application numbers of Licensed Patents
     to satisfy the laws of the countries in which the Licensed Products are
     sold or supplied and in which they are covered by the claims of any patent
     or patent application of Licensed Patents, to the intent that the Licensor
     shall not suffer any loss or loss of damages in an infringement action. For
     the avoidance of doubt, in respect of the Genentech Agreement, reasonable
     endeavours shall be limited to requesting that Genentech mark Licensed
     Products and the packages associated with them as described in this clause
     3.3. The Parties Acknowledge that the Licensee has no power to force
     Genentech to comply with such a request.

4.   Clause 3.4 of the License Agreement shall be replaced in its entirety with
the following:

     3.4    No right, express or implied is granted by this License for the
     Licensee or any of its sublicensees to use in any manner the names "Oxford"
     or "Isis" or any other trademark or trade name of the University or Isis
     without the prior written consent of the University and/or Isis. The
     Licensee agrees not to change it name to or trade under any name that
     includes the word "Oxford".

5.   Clause 4.1 of the License Agreement will be replaced in its entirety with
the following:

     4.1(a) The Licensee agrees to pay to the Licensor the sum of [*******] the
            receipt of which is acknowledged. For so long as any Licensed
            Products are used or marketed by the Licensee and its sublicensees,
            subject to clauses 4.1 (b) and (c), the Licensee will pay to the
            Licensor a royalty equal to [*******] of the Net Sales of all such
            Licensed Products.

     4.1(b) In regard to royalty payments with respect to Licensed Product for
            which royalties are due under clause 4.1(a) of this Agreement that
            are sold pursuant to an agreement between Licensee and Genentech,
            Inc. (the "Genentech Agreement") (which for the avoidance of doubt
            includes any sublicense under the Genentech Agreement), such royalty
            payments shall be (i) calculated based on net sales of Licensed
            Product where net sales are determined as defined in the Genentech
            Agreement (and not Net Sales as defined in the License Agreement),
            both in the case where TolerRx is receiving royalty payments under
            the Genentech Agreement and in the case where

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

                                        2
<Page>

            TolerRx is receiving a share of Operating Profits and Losses under
            the Genentech Agreement.

     4.1(c) In the event that royalties based on Licensed Product pursuant to
            the Genentech Agreement are reduced thereunder as a result of
            commercialization of a product by a third party, then, with respect
            to Licensed Products to which such reduction applies, the royalty
            rate under clause 4.1(a) of the License Agreement [*******].

6.   Clause 4.3 of the License Agreement shall be replaced in its entirety with
the following:

     4.3.1  Except as provided in clause 4.3.2, the Licensor shall provide the
            Licensor with a royalty report within sixty (60) days after the
            close of each calendar quarter for each Licensed Product brought
            into use by or within the groups of the Licensee and sub-licensees.
            Each report shall state the Net Sales and provide a calculation of
            the royalties due, and shall be accompanied by payment to the
            Licensor of the royalties due.

     4.3.2  In respect of royalty payments and royalty reports as to royalties
            due under the Genentech Agreement, such sales and reports will be
            due thirty (30) days after such payments and reports from Genentech
            become due with respect to Genentech Sales.

7.   Clause 4.12 of the License Agreement shall be replaced in its entirety with
the following:

     4.12.1 Except as provided in clause 4.12.2, the Licensee and the Licensee's
            sub-licensees shall keep complete and accurate accounts of all
            Licensed Products used and marketed and will permit the Licensor
            through an independent certified accountant to audit such accounts
            on at least thirty days' written notice and no more than once each
            calendar year solely for the purpose of determining the accuracy of
            the royalty reports and payments. The Licensee's obligation and that
            of the Licensee's sub-licensees concerning audit of their accounts
            shall terminate as to any report three (3) years after the date of
            that report

     4.12.2 Where the Licensee enters into a sub-license with Genentech, the
            Licensor expressly agrees to waive the audit-rights set out in
            sub-clause 4.12.1 above in respect of Genentech and its
            sub-licensees. However, upon the written request of the Licensor,
            Licensee agrees to exercise the audit rights of the Licensee under
            the Genentech Agreement. The Licensor retains the right to audit the
            Licensee and to inspect any records of audits carried out by the
            Licensee upon Genentech

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

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

                                        3
<Page>

9.   The License Agreement is amended as provided herein with effect from the
date of this Amendment Agreement. All other terms and provisions of the License
Agreement shall be unaffected by this Amendment Agreement.

10.  All references in the License Agreement to the "Agreement" shall be deemed
to include this Amendment Agreement.

11.  This Amendment Agreement shall be governed by English Law. The Licensee
     submits to the non-exclusive jurisdiction of the English courts with
     respect to any dispute which may arise out of or in connection with this
     Amendment Agreement.

     AS WITNESS the hands of authorized signatories for the parties on the date
first mentioned above.

     SIGNED for and on behalf of
     ISIS INNOVATION LIMITED:

Name:       Mr. T. Hockaday
Position:   Executive Director
            Isis Innovation Ltd
Signature:  /s/ T. Hockaday

SIGNED for and on behalf of
THE CHANCELLOR, MASTERS
AND SCHOLARS OF THE
UNIVERSITY OF OXFORD:

Name:       Dr. Richard Liwicki
Position:   Associate Director
            Research Services
            University of Oxford
Signature:  /s/ Richard Liwicki

SIGNED for and on behalf of
TOLERRX, INC.:

Name: Douglas J. Ringler
Position: President and Chief Executive Officer
Signature: /s/ Douglas J. Ringler

                                        4<Page>

                                                                   EXHIBIT 10.10

                              DATED  1 FEBRUARY 2001

                           (1) ISIS INNOVATION LIMITED

                                (2) TOLERRX, INC

                        Licence of the Stealth Technology

<Page>

[*******] 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.

THIS AGREEMENT dated 1 February 2001 (the "EFFECTIVE DATE") is made BETWEEN:

(1)     ISIS INNOVATION LIMITED a company registered in England (No. 02199542),
        whose registered office is at University Offices, Wellington Square,
        Oxford OX1 2JD, England (the "LICENSOR"); and

(2)     TOLERRX, INC., a Delaware corporation whose principal place of business
        is at 675 Mass Ave., Cambridge, MA 02139 (the "LICENSEE").

1.      DEFINITIONS
        For the purposes of this Agreement, the following definitions apply:

(a)            "Affiliate" means with respect to a party, an entity that
        controls, is controlled by or is under common control with a party. As
        used herein, "control" means possession, of the power to direct or cause
        the direction of the management and policies whether through the
        ownership of voting securities, by contract or otherwise.

(b)            "Fields" mean: i. the prevention and treatment of human diseases
        and disorders; and ii. the diagnosis and monitoring of or susceptibility
        to human diseases.

(c)            "Improvement" means any development of the Licensed Technology
        claimed in a patent or patent application which, if commercially
        practised, would infringe and/or be covered by a claim being prosecuted
        in a patent application included in the Licensed Technology, or by a
        Valid Claim of any issued patent included in the Licensed Technology.

(d)            "Licence" means the licence granted to the Licensee pursuant to
        clause 2.2(a).

(e)            "Licence Year" means each twelve month period of this Agreement
        commencing on the Effective Date or an anniversary of the Effective Date
        and ending on the subsequent anniversary of the Effective Date.

(f)            "Licensed Product" means any product or composition but for this
        license infringes a Valid Claim of any patent or patent application,
        pending for no longer than seven years, included in the Licensed
        Technology in the country where sold.

(g)            "Licensed Technology" means U.K. Patent Application No. 0024673.6
        filed on 9 October 2000 and any patent application filed in the world
        based on that application, including any division, continuation, or
        continuation-in-part thereof and any foreign patent application or
        equivalent corresponding thereto and any Letters Patent or the
        equivalent thereof issuing thereon or reissue, re-

                                        1
<Page>

        examination or extension of any of the foregoing, and any patent or
        equivalent thereof based on any of the foregoing.

(h)            "Licensee Improvements" means the Improvements described in
        clause 5.13.

(i)            "Licensor Improvements" means the Improvements described in
        clause 4.2.

(j)            "Net Sales" means the gross selling price of the Licensed Product
        in the form in which it is sold or leased to a customer after regulatory
        approval thereof by Licensee (as recorded in the standard customer
        pricing records of the Licensee if and to the extent that such records
        are applicable to the Licensed Product in question), after deducting:
        (i) transportation charges or allowances, including freight pickup
        allowances, and shipping packaging costs, if any; (ii) trade, quantity
        or cash discounts, if any, allowed or paid; (iii) credits or allowances,
        if any, given or made on account of returns, any and all Federal, state
        or local government rebates, whether in existence now, or enacted at any
        time during the term of this Agreement, rejections, recalls or
        destruction (voluntarily made or requested or made by an appropriate
        government agency, sub-division or department) for the Licensed Product;
        (iv) any tax, excise or other governmental charge upon or measured by
        the production, sale, transportation, delivery or use of the Licensed
        Product, exclusive of income tax; (v) any government mandated surcharge,
        levy, tax or assessment to fund a compensation program or reserve for
        persons injured or alleged to be injured by the Licensed Product; and
        (vi) a reasonable allowance for bad debt.

        It is understood that a Licensed Product may be marketed in a
        combination package containing other products or materials or in
        combination with active ingredients that are not Licensed Product. Where
        a Licensed Product is marketed in combination with other products or
        materials, the Net Sales for the purpose of determining royalty payments
        will be calculated in accordance with the following formula:

        NS = A x   B
                 -----
                 B + C

        Where:

        NS means the Net Sales for the purpose of determining royalty payments;
        A means the net sales of the combination package;
        B means the gross sales of the Licensed Product during the royalty
        period if sold separately; and
        C means the aggregate of the gross sales of the other products or
        materials during the royalty period if sold separately.

                                        2
<Page>

        In the event that there are no separate sales of the Licensed Product
        during the royalty period:

        B means the standard fully-absorbed cost to the Licensee of the Licensed
        Product, calculated in accordance with generally accepted accounting
        principles; and
        C means the aggregate of the standard, fully-absorbed costs to the
        Licensee of the other products or materials, calculated in accordance
        with generally accepted accounting principles.

(k)            "University" means the Chancellor Masters and Scholars of the
        University of Oxford whose administrative offices are at Wellington
        Square, Oxford OX1 2JD, England.

(l)            "Valid Claim" means a claim of an issued patent which has not
        lapsed or become abandoned or disclaimed or been declared invalid or
        unenforceable by a court of competent jurisdiction or an administrative
        agency from which no appeal can be or is taken.

2.      GRANT

2.1     The Licensor reserves the right to grant to the University a licence for
        the University and every employee, student, agent and appointee of the
        University to use and publish the Licensed Technology and any Licensor
        Improvement made under clause 4.2 for academic and research purposes:
        and this will include the right for the University to use the Licensed
        Technology as enabling technology in other research projects (including
        projects which benefit from third-party funding received from commercial
        entities).

2.2     (a) The Licensor grants to the Licensee a licence in, to and under the
        Licensed Technology world-wide to make, have made, use, sell, offer to
        sell, and import Licensed Product in the Fields. Subject only to clause
        2.1, the Licence shall be exclusive. The Licensee recognises that this
        Agreement confers no rights in relation to products intended or adapted
        for other fields.

        (b) The Licensor agrees to provide Licensee with samples of genetic
        material, clones and proteins contained in the Licensed Technology that
        are in the possession of Licensor at the date of this Agreement.

3.      CONFIDENTIALITY

3.1     During the term of this Agreement, it is contemplated that each party
        will disclose to the other proprietary and confidential technology,
        inventions, technical information, biological materials and the like,
        which are owned or controlled by the party providing such information or
        which that party is obligated to maintain in confidence and which is
        designated by the party

                                        3
<Page>

        providing such information as confidential ("CONFIDENTIAL INFORMATION").
        Subject to the other terms of this Agreement, each party agrees to
        retain the other party's Confidential Information in confidence and not
        to disclose any such Confidential Information to a third party without
        the prior written consent of the party providing such information and to
        use the other party's Confidential Information only for the purposes of
        this Agreement, which obligation shall terminate five (5) years after
        the expiration or termination of this agreement.

3.2     The obligations of confidentiality will not apply to Confidential
        Information which:
        (i)    was known to the receiving party or generally known to the public
               prior to its disclosure hereunder including, but not limited to,
               publication in a patent or patent application;
        (ii)   subsequently becomes known to the public by some means other than
               a breach of this Agreement, including, but not limited to,
               publication in a patent or patent application;
        (iii)  is subsequently disclosed to the receiving party by a third party
               having a lawful right to make such disclosure;
        (iv)   is required by law or bona fide legal process to be disclosed,
               provided that the party required to make the disclosure takes all
               reasonable steps to restrict and maintain confidentiality of such
               disclosure and provides reasonable notice to the party providing
               the Confidential Information;
        (v)    is approved for release by the parties;
        (vi)   is independently developed by the employees or agents of either
               party without any knowledge of the Confidential Information
               provided by the other party; or
        (vii)  is disclosed to a government body, agency or authority as
               required by applicable law, rule, or regulation or in order to
               obtain regulatory approval for or authorization to market and
               sell Licensed Product, provided such Confidential Information is
               marked "Confidential" at the time of disclosure.

3.3     Notwithstanding the foregoing, the parties shall have the right to
        disclose Confidential Information to a third party who undertakes an
        obligation of confidentiality and non-use with respect to such
        information, at least as restrictive as the obligations under sub-clause
        3.1 and 3.2.

3.4     In the event that Confidential Information of Licensor becomes publicly
        available as a result of the Licensee's breach of its confidentiality
        obligations under this Agreement or as a breach of such confidentiality
        obligations owed by an entity that receives the Licensor's Confidential
        Information from the Licensee, the Licensee will continue paying
        royalties under clause 6, without prejudice to the payment of any
        additional damages in the event of the Confidential Information becoming
        publicly known as a result of breach of this Agreement.

                                        4
<Page>

4.      UNDERTAKINGS BY THE LICENSOR

4.1     The Licensor warrants and represents to the Licensee that it has the
        full right and authority to enter into this Agreement, and that it is
        not aware of any impediment which would inhibit its ability to perform
        the terms and conditions imposed on it by this Agreement.

4.2     The Licensor will communicate to the Licensee any Improvements which the
        Licensor makes to the Licensed Technology. The Licensor and the Licensee
        may enter into negotiations with respect to the Licensee licensing the
        Licensor Improvements from the Licensor.

4.3     The Licensor will inform the Licensee of any misappropriation or
        infringement of the Licensed Technology of which the Licensor becomes
        aware.

5.      UNDERTAKINGS BY THE LICENSEE

5.1     The Licensee may grant sub-licences and may disclose to sub-licensees
        such of the Licensed Technology as is necessary for the exercise of the
        rights sub-licensed. The Licensee may also grant sub-licensees the right
        to grant sub-licences, but only with the prior written consent of the
        Licensor (which shall not be unreasonably withheld). Immediately
        following the grant of each sub-licence, the Licensee will forward to
        the Licensor in writing a note of the name and address of the
        sub-licensee, a description of the technology sub-licensed and its
        intended applications, and confirmation of the duration of the
        sub-licence. By controlling the wording of its contracts with
        sub-licensees, the Licensee will ensure that the sub-licensees are
        subject to the confidentiality obligations in clause 3 of this Agreement
        in order to protect the intellectual property rights in the Licensed
        Technology, and the interests of the Licensor therein; and that in no
        circumstances do the terms of any sub-licence in force from time to time
        conflict with the terms of this Agreement.

5.2     The Licensee will be responsible for the design and construction of the
        Licensed Products and the Licensor will have no responsibility or
        liability in that respect.

5.3     The Licensee will ensure that the Licensed Products and the packages
        associated with them are marked suitably with any relevant patent or
        patent application numbers of Licensed Technology to satisfy the laws of
        each of the countries in which the Licensed Products are sold or
        supplied and in which they are covered by the claims of any patent or
        patent application of Licensed Technology, to the intent that the
        Licensor shall not suffer any loss or loss of damages in an infringement
        action.

                                        5
<Page>

5.4     (a)    Taking into account the complexity, and stage of development of
        the Licensed Technology, the Licensee shall select and use reasonable
        commercial efforts under the circumstances to research, develop and then
        commercialize the Licensed Technology. The efforts of the Licensee's
        sub-licensee or a person or entity performing work for Licensee under a
        contract negotiated at arm's length shall be considered as efforts of
        Licensee.
        (b)    In the event that Licensor reasonably believes that Licensee is
        not making reasonable commercial efforts under the circumstances to
        research, develop and then commercialize the Licensed Technology
        pursuant to sub-clause 5.4(a), then Licensor shall provide written
        notice to Licensee which specifies Licensor's basis for such belief and
        what additional efforts Licensor believes should be made by Licensee.
        Upon receipt of such written notice, Licensor 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
        5.4(a), and if such mutual agreement is not reached within thirty (30)
        days after receipt of such written notice, then the parties agree to
        submit to arbitration pursuant to clause 11.8 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)    Within sixty (60) days after the end of each calendar year of
        this Agreement, Licensee shall provide Licensor with a report detailing
        progress made and steps taken during that calendar year and plans for
        the next calendar year in:
               (i)     applying for and defending any patent, design, trade
                       mark, copyright and other registrations which may be
                       available for the protection of the Licensed Technology;
               (ii)    taking legal action against any misappropriation or
                       infringement of the Licensed Technology of which the
                       Licensee becomes or is made aware;
               (iii)   developing the Licensed Technology in order to facilitate
                       its commercial exploitation, including, without
                       limitation:
                       -   identification of generic approaches or process to
                           finding peptide blockers of appropriate affinities
                           for any given antibody;
                       -   identification of suitable linkers for the purpose of
                           constructing engineered blockers;
                       -   identification of suitable cleavable linkers that
                           might have practical applications IN VIVO;
                       -   identification of a universal blocking peptide that
                           interacts with the framework of all antibody
                           combining sites, and
               (iv)    promoting and marketing Licensed Products.

5.5     Subject to clause 5.6, the Licensee shall file, prosecute and maintain
        patent applications and patents directed to the Licensed Technology in
        the name of the Licensor through patent counsel selected by Licensee and
        approved by the Licensor (which approval shall not be unreasonably
        withheld or delayed) who shall consult with and keep Licensor 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 Licensed Technology in the United

                                        6
<Page>

        States, European Patent Office and subsequent national filings which
        derive from it, Japan, Canada and Australia and any other foreign
        countries mutually agreed by the Licensee and the Licensor. If, in good
        faith, the Licensor believes a patent may be granted in a country but
        the Licensee is unwilling to bear the cost and expense for filing,
        prosecuting and maintaining the patent in that country, the Licensor may
        instruct the patent counsel selected by the Licensee at its own cost to
        file, prosecute or maintain the Licensed Technology in that country, and
        the country in question shall be removed from the scope of this
        Agreement.

5.6     With respect to Licensed Technology, 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 Licensor for Licensor's comments at
        least fourteen days prior to filing in a patent office. In the absence
        of comments from Licensor, Licensee shall have the right to file any
        such paper. Licensor shall have the right to take any action that in its
        judgement is necessary to preserve such patents.

5.7     The Licensor shall co-operate with Licensee with respect to filing,
        prosecution and maintenance of Licensed Technology and shall use
        reasonable endeavours to cause the inventors to co-operate.

5.8     The Licensee will inform the Licensor of any misappropriation or
        infringement of the Licensed Technology of which the Licensee becomes
        aware.

5.9     (a)    Subject to clause 5.10, if any of the Licensed Technology under
        which Licensee is licensed hereunder is infringed by a third party,
        Licensee shall have the right and option but not the obligation to bring
        an action for infringement, at its sole expense, against such third
        party in the name of Licensor and/or in the name of Licensee, and to
        join Licensor as a party plaintiff if required. Licensee shall promptly
        notify Licensor of any such infringement and shall keep Licensor
        informed as to the prosecution of any action for such infringement. No
        settlement, consent judgement or other voluntary final disposition of
        the suit which adversely affects Licensed Technology may be entered into
        without the consent of Licensor, which consent shall not unreasonably be
        withheld.
        (b)    Any recovery of damages by Licensee for any such suit shall be
        applied first in satisfaction of any unreimbursed expenses and legal
        fees of Licensee relating to the suit and the remainder thereof shall be
        retained by Licensee and treated as Net Sales subject to royalty under
        this Agreement.

5.10    At the written request of the Licensor, the Licensee shall be obliged to
        bring an action for any misappropriation or infringement of the Licensed
        Technology at its sole expense against a third party, in any one
        jurisdiction where the misappropriation or infringement is occurring,
        where:

                                        7
<Page>

        (a)    the third party is selling a product substantially identical to a
               Licensed Product sold by TolerRx (the "Third Party Product") that
               infringes an issued patent included in the Licensed Technology;
               and
        (b)    the aggregate sales of the Third Party Product exceed
               US$[*******] and are equal to or greater than [*******] of the
               world-wide sales of such Licensed Product sold by TolerRx; and
        (c)    in the opinion of an independent patent attorney, there is
               reasonable likelihood that such an action would be successful.

5.11    In the event that Licensee elects not to pursue an action for
        infringement, upon written notice to Licensor by Licensee that an
        unlicensed third party is an infringer of Licensed Technology, Licensor
        shall have the right and option, but not the obligation at its cost and
        expense to initiate infringement litigation and to retain any recovered
        damages.

5.12    In any infringement suit either party may institute to enforce the
        rights in Licensed Technology pursuant to this Agreement, the other
        party hereto shall, at the request 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. All reasonable
        out-of-pocket costs incurred in connection with rendering cooperation
        requested hereunder shall be paid by the party requesting cooperation.

5.13    (a)    The Licensee will communicate to the Licensor any Improvements
        which the Licensee makes to the Licensed Technology.

        (b)    The Licensee will, on a case-by-case basis and subject to the
        Licensee's consent, grant the Licensor a non-exclusive, royalty-free
        license to use the Licensee's Improvements for academic and research
        purposes only, with the right to grant a sub-license only to the
        University and every employee, student, agent and appointee of the
        University to use the Licensee's Improvements for academic research
        purposes only, and the University shall have no right to grant
        sublicenses. For the avoidance of doubt, the license granted under this
        clause 5.13(b) shall only take effect if Licensee provides written
        consent to such license and if Licensee has the right to grant such
        license, provided that Licensee uses reasonable endeavors to ensure that
        its contracts with third parties do not preclude the Licensee from
        granting the license under this clause 5.13(b). University shall have
        the ability to publish results obtained using Licensee's Improvements
        licensed to Licensor and sublicensed to the University subject to the
        confidentiality provisions of clauses 3.1 and 3.2.

5.14    The Licensee warrants and represents to the Licensor that it has the
        full right and authority to enter into this Agreement, and that it is
        not aware of any impediment which would inhibit its ability to perform
        the terms and conditions imposed on it by this Agreement.

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

                                        8
<Page>

6.      PAYMENT

6.1     The Licensee must pay to the Licensor all of the costs incurred by the
        Licensor prior to the date of this Agreement in filing UK Patent
        Application No. 0024673.6 to an amount not exceeding [*******] within
        thirty (30) days of receiving an invoice for such amount from the
        Licensor.

6.2     The Licensee must pay to the Licensor the sum of [*******] on the
        signature of this Agreement.

6.3     (a) For as long as any Licensed Products are used or marketed by the
        Licensee, the Licensee will pay royalties to the Licensor equal to the
        following percentages of all Net Sales of Licensed Products sold by the
        Licensee and gross up-front and milestone (as opposed to
        periodically-recurring or running-earned) consideration received by the
        Licensee under or in respect of sub-licences granted by the Licensee
        with respect to the Licensed Technology in each Licence Year:

<Table>
<Caption>
          CUMULATIVE NET SALES AND GROSS UP-
                 FRONT CONSIDERATION                         PERCENTAGE
        <S>                                                   <C>
        Net Sales and gross up-front consideration            [*******]
        of up to [*******] in a Licence Year

        Net Sales and gross up-front consideration            [*******]
        of greater than [*******] up to [*******]
        in a Licence Year

        Net Sales and gross up-front consideration            [*******]
        of over [*******] in a Licence Year
</Table>

        Subject to the following, no royalties shall be payable under this
        sub-clause 6.3 with respect to payments made to the Licensee by a
        sub-licensee for stock or equity or for research performed or to be
        performed by the Licensee specifically relating to the development of
        the Licensed Technology. Where a sub-licensee or a third party who, at a
        later stage, becomes a sub-licensee (a "PURCHASER"), purchases stock or
        equity in the Licensee, royalties will be payable in accordance with
        this sub-clause 6.3 on the amount paid by the Purchaser to the Licensee
        for that stock or equity to the extent that the amount paid by the
        Purchaser exceeds the fair market value for that stock or equity, and
        such excess is disguised consideration for the sub-licence. If there is
        a dispute as to the fair market value, it shall be submitted to
        arbitration under clause 11.8.

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

                                        9
<Page>

        (b)    The amounts paid by Licensee under Clause 6.3(a) based on
        milestones received under or in respect of sublicenses shall be fully
        creditable until exhausted against any amount owed by Licensee under
        Clause 6.6.

6.4     For as long as the Licensee sub-licenses the Licensed Technology, the
        Licensee will pay royalties to the Licensor of [*******] of all
        royalties paid to Licensee by a sublicensee for sales of a Licensed
        Product.

6.5     In the event that the royalties paid to the Licensor under clauses 6.3
        and 6.4 in a Licence Year do not exceed the following amounts in respect
        of the relevant Licence Year (the "MINIMUM SUM"), the Licensee must make
        up the difference between the aggregate of the royalties paid and the
        Minimum Sum in that Licence Year; and will do so concurrently with the
        report under clause 5.4(c) which immediately follows the end of the
        period:

<Table>
<Caption>
               LICENCE YEAR                                  MINIMUM SUM
        <S>                                                   <C>
        The 12-month period which                             [*******]
        begins on the Effective Date
        ("LICENCE YEAR 1")

        The next 12 month period                              [*******]
        (i.e. beginning on the first
        anniversary of the Effective
        Date) ("LICENCE YEAR 2")

        Licence year 3                                        [*******]

        Licence Year 4                                        [*******]

        Licence Year 5 and Licence Year 6                     [*******]
</Table>

        In the event that no royalties are due to the Licensor in a Licence
        Year, the Licensee must pay the Minimum Sum to the Licensor.

        The payments under this Clause 6.5 shall terminate on the earlier of the
        end of Licence Year 6 or the initiation of a Phase I Clinical Trial for
        a Licensed Product.

6.6     The Licensee will pay to the Licensor the following non-refundable
        non-creditable milestone payments within thirty (30) days after the
        occurrence of the specified events (including, for the avoidance of
        doubt, where the specified events are performed by a sub-licensee) (the
        "MILESTONES") in respect of only the first Licensed Product produced by
        the Licensee:

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

                                       10
<Page>

<Table>
<Caption>
                     EVENT                                     AMOUNT
        <S>                                                   <C>
        Demonstration of tolerance induction                  [*******]
        IN VIVO to an antibody engineered to
        contain sequences from a species
        different than the experimental
        animals

        Initiation of Phase I clinical trials                 [*******]

        Initiation of Phase II clinical trials                [*******]

        Initiation of Phase III clinical trials               [*******]

        Entering into first sub-licence by                    [*******]
        Licensee

        Grant of patent in respect of the                     [*******]
        Licensed Technology in the first of
        the European Union, the United States
        of America, Japan, Canada or Australia.

        6 months from the Effective Date                      [*******]
</Table>

6.7     The Licensee acknowledges that the range of Net Sales used for changing
        royalty rates under Section 6.3 and gross up-front considerations set
        out in clause 6.3, the Minimum Sums and the amounts payable in respect
        of the Milestones will be indexed to the CPI-U (Consumer Price Index -
        All Urban Consumers) and will be adjusted at the end of each Licence
        Year to take account of increases in the CPI-U in the preceding year.
        The Licensor will notify the Licensee of any increase in the range of
        Net Sales and gross up-front considerations set out in clause 6.3, the
        Minimum Sums and the amounts payable in respect of the Milestones as a
        result of an increase in the CPI-U in writing at least 30 days before
        the end of each Licence Year.

6.8     The Licensee shall provide the Licensor with a royalty report within
        sixty (60) days after the close of each calendar quarter for each
        Licensed Product marketed, and for each Licensed Product brought into
        use by or within the groups of the Licensee, sub-licensees and
        sub-sub-licensees. Each report shall set out the Net Sales and all gross
        revenues received from sub-licensees, provide a calculation of the
        royalties due and shall be accompanied by payment to the Licensor of the
        royalties due.

6.9     In marketing the Licensed Products, the Licensee will not accept or
        solicit any non-monetary consideration without the prior written consent
        of the Licensor. The use by the Licensee of a commercially reasonable
        quantity of Licensed Products for promotional sampling shall not violate
        this prohibition.

6.10    In the case of a Licensed Product which is not marketed, but rather
        manufactured by the Licensee or a sub-licensee for use by that party, or
        within

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

                                       11
<Page>

        that party's group, the term "Net Sales" shall mean [*******] of the
        gross selling price of the Licensed Product in the form in which it is
        normally sold, as recorded in the standard customer pricing records of
        the Licensee or the sub-licensee if and to the extent that such records
        are applicable to the Licensed Product in question, or as ascertained by
        applying reasonable uplifts to the standard, fully-absorbed cost of the
        Product to the Licensee, sub-licensee if and to the extent that those
        records are not so applicable. For the avoidance of doubt, this clause
        shall not apply to Licensed Product used by the Licensee or within the
        Licensee's group solely for the purposes of internal research or solely
        for the purposes of internal quality control.

6.11    For the purpose of calculating running-earned royalties under this
        clause, a Licensed Product shall be regarded as sold or leased by the
        Licensee or a sub-licensee when invoiced, or if not invoiced, when
        shipped or delivered by the Licensee or sub-licensee. If a Licensed
        Product marketed by the Licensee or a sub-licensee is sold to an
        Affiliate for re-sale, the royalty on each such Licensed Product so
        re-sold shall be calculated on the highest of the prices at which it is
        (i) marketed or sold to an Affiliate for re-sale or (ii) re-sold;
        provided, however, that in no event shall royalty be paid more than once
        on each Licensed Product.

6.12    Subject to the following, if the Licensee or a sub-licensee is obliged
        to pay royalties to third parties (other than the Licensee's Affiliate),
        for the right to make, use or sell a Licensed Product, then the Licensee
        shall be entitled to deduct from the royalty payment due to the Licensor
        a portion of the royalty payment actually made to such third party as
        the Licensee has negotiated with the Licensor, but in any event, not
        greater than [*******] of the royalty payment due to the Licensor. This
        clause 6.12 will not apply until the Licensee is obliged to pay in the
        aggregate to third parties and Licensor more than [*******] of Net Sales
        in royalties and will only apply to the amount of royalties payable to
        third parties which exceed [*******] of Net Sales.

6.13    All payments provided for under this clause 6 shall be made to the
        Licensor in US dollars without any deductions apart from any tax which
        is required to be withheld under applicable local law. Any exchange of
        currency made to calculate sales for the purpose of this clause 6 shall
        be determined as at the last business day of each quarter, using the
        average of the average daily buying and selling rates quoted by Barclays
        Bank plc during that quarter. Where the Licensee is required to withhold
        tax under applicable local law, the Licensee shall deduct such tax, pay
        it to the relevant taxing authority, and supply the Licensor with a
        Certificate of Tax Deduction at the time of payment to the Licensor. The
        parties shall co-operate under any applicable Double Taxation Treaty so
        that, if possible, payments are made gross or, if payment gross is not
        possible, the Licensor obtains appropriate relief under the Treaty.

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

                                       12
<Page>

6.14    Where the Licensee is obliged to make a payment to the Licensor under
        this Agreement which attracts value-added, sales, use, excise or other
        similar taxes or duties, the Licensee shall be responsible for paying
        such taxes and duties.

6.15    In the event that full payment of any amount due from the Licensee to
        the Licensor under this Agreement is not made by any of the dates
        stipulated, the Licensee shall be liable to pay interest on the amount
        unpaid at the rate of two percent (2%) over the base rate for the time
        being of Barclays Bank plc, from the date when payment was due until the
        date of actual payment.

6.16    The Licensee and the Licensee's sub-licensees shall keep complete and
        accurate accounts of all Licensed Products used and marketed; and will
        permit the Licensor through an independent certified accountant to audit
        such accounts on at least thirty (30) days' written notice and no more
        than once each calendar year solely for the purpose of determining the
        accuracy of the royalty reports and payments. The Licensee's obligation
        and that of the Licensee's sub-licensees concerning audit of their
        accounts shall terminate as to any report three (3) years after the date
        of that report.

7.      DURATION AND TERMINATION

7.1     This Agreement shall take effect on the date of signature and (subject
        to the remaining sub-clauses of this clause) shall continue in force
        until the expiration of the period of 10 years thereafter, provided
        however, that such terms shall be extended with respect to each patent
        or patent application that is Licensed Technology for the life of that
        issued patent.

7.2     If either party commits a material breach of Clause 3.1, 5.1, 5.5, 5.6,
        5.10, 5.13(a), 6 or 8 of this Agreement or fails to exert the efforts
        determined by the parties or by arbitration under clause 5.4(c) and the
        breach or failure is not remedied (where remediable) within the period
        allowed by notice given by the other party in writing calling on the
        party in breach to effect such remedy or failure (such period being not
        less than thirty (30) days), the other party may by further written
        notice terminate this Agreement immediately.

7.3     PURPOSELY OMITTED

7.4     The Licensee may terminate this Agreement at any time by serving not
        less than three (3) months' written notice on the Licensor.

7.5     The Licensor shall have the right to terminate this Agreement by serving
        written notice on the Licensee in the event that the Licensee files a
        voluntary petition in bankruptcy, is adjudicated a bankrupt, makes a
        general assignment for the benefit of creditors, or fails to discharge
        within 30 days an involuntary petition in bankruptcy filed against it.
        Such notice may terminate their Agreement either immediately or at the
        end of such period as the Licensor shall select.

                                       13
<Page>

7.6     Clauses 3, 5.12, 7.8, 7.9, 7.10, 7.11, 8 and 11.4 shall survive the
        termination or expiration of this Agreement for whatever reason.

7.7     This Agreement may be terminated only as set forth in this clause 7.

7.8     Upon any termination of this Agreement, Licensee, at its option, shall
        be entitled to finish any work-in-progress which is completed within six
        (6) months of termination of this Agreement and to sell any completed
        inventory of a Licensed Product covered by this Agreement which remains
        on hand as of the date of the termination, so long as Licensee pays to
        Licensor the royalties applicable to said subsequent sales in accordance
        with the same terms and conditions as set forth in this Agreement.

7.9     In the event that this Agreement and/or the rights and licenses 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 Licensor and the sub-licensee under the terms and
        conditions of this Agreement, subject to the sub-licensee agreeing to be
        bound to Licensor under such terms and conditions within thirty (30)
        days after Licensor provides written notice to the sub-licensee of the
        termination of Licensee's rights and licenses under this Agreement. At
        the request of Licensee, Licensor will acknowledge to a sub-licensee,
        Licensor's obligations to the sub-licensee under this paragraph.

7.11    On termination of this Agreement, howsoever caused, the Licensee agrees
        that, at the request of the Licensor, it will negotiate with the
        Licensor in good faith a royalty-bearing licence on reasonable
        commercial terms of the Licensee's Improvements to the Licensor. The
        parties agree, however, that in no event is the Licensee obliged to
        grant such a licence to the Licensor and either Licensee or Licensor
        will have the right to terminate such negotiations at any time by
        written notice to the other party.

8.      LIABILITY

8.1     (a) The Licensee agrees to indemnify the Licensor and hold the Licensor
        harmless from and against any and all claims, damages and liabilities
        asserted by third parties (including claims for negligence) which arise
        directly or indirectly from the use of the Licensed Technology or the
        sale of Licensed Products by the Licensee and its sub-licensees.
        (b) The Licensee shall have the right to control the defence, settlement
        or compromise of any such action and shall select counsel for such
        defence.
        (c) The Licensor shall promptly notify the Licensee of any claim or
        threatened claim under this sub-clause 8.1(a) and shall fully co-operate
        with all reasonable requests of the Licensee with respect thereto.

                                       14
<Page>

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

8.2     The Licensor makes no representation or warranty that advice given to
        the Licensee pursuant to this Agreement by any employee, student, agent
        or appointee of the Licensor or of the University of Oxford, or the use
        of any works, designs or information which they, the Licensor or the
        University provide in connection with this Agreement, will not result in
        infringement of third-party rights.

8.3     The Licensee undertakes to make no claim against any employee, student,
        agent or appointee of the Licensor or of the University of Oxford, being
        a claim which seeks to enforce against any of them any liability
        whatsoever in connection with this Agreement or its subject-matter. It
        is understood that this clause 8.3 does not prevent the Licensee from
        asserting a claim(s) against the Licensor.

8.4     The liability of either party for any breach of this Agreement, or
        arising in any other way out of the subject-matter of this Agreement,
        will not extend to any incidental or consequential damages or losses or
        to any loss of profits.

8.5     The Licensor's maximum liability with respect to payment of damages
        awarded to the Licensee by a court of law under or otherwise in
        connection with this Agreement or its subject matter, shall be the
        return of all royalty, Milestone and up-front payments paid by the
        Licensee under this Agreement, together with interest on the balance of
        such moneys from time to time outstanding, accruing from day to day at
        two percent over the Barclays Bank plc base rate from time to time in
        force and compounded annually as at 31 December and if the damages
        awarded exceed such amount, such excess may be credited against future
        royalties and milestones owed by Licensee under this Agreement, as and
        when they become due.

8.6     If any sub-clause of this clause 8 is held to be invalid or
        unenforceable under any applicable statute or rule of law, then it shall
        be deemed to be omitted, and if as a result any party becomes liable for
        loss or damage which would otherwise have been excluded, then such
        liability shall be subject to the remaining sub-clauses of this
        clause 8.

9.      FORCE MAJEURE

        If the performance by either party of any of its obligations under this
        Agreement (other than an obligation to make payment) shall be prevented
        by circumstances beyond its reasonable control, then such party shall be
        excused from performance of that obligation for the duration of the
        relevant event.

10.     NOTICES

                                       15
<Page>

        The Licensor's representative for the purpose of receiving payments and
        notices shall until further notice be:

                       The Managing Director
                       Isis Innovation Limited
                       Ewert House, Ewert Place
                       Summertown
                       OXFORD OX2 7DD
                       England.

        The Licensee's representative for the purpose of receiving notices shall
        until further notice be:

                      TolerRx, Inc.
                      675 Mass. Ave.
                      Cambridge, MA 02139
                      Attn: CEO

11.     GENERAL

11.1    Clause headings are inserted in this Agreement for convenience only, and
        they shall not be taken into account in the interpretation of this
        Agreement.

11.2    Nothing in this Agreement shall create, imply or evidence any
        partnership or joint venture between the Licensor and the Licensee or
        the relationship between them of principal and agent.

11.3    This Agreement constitutes the entire agreement between the parties with
        regard to the Licence. Specifically, but without limitation, this
        Agreement does not impose or imply any obligation on the Licensor or the
        University of Oxford to conduct development work: any arrangements for
        such work shall be the subject of a separate agreement between the
        University and the Licensee. Any variation of this Agreement shall be in
        writing and signed by authorised signatories for both parties.

11.4    This Agreement shall be governed by English Law. Except as provided in
        clause 11.8, the Licensee submits to the non-exclusive jurisdiction of
        the English courts with respect to any dispute which may arise out of or
        in connection with this Agreement.

11.5    If any one or more clauses or sub-clauses of this Agreement would result
        in this Agreement being prohibited pursuant to any competition law, then
        it or they shall be deemed to be omitted. The parties shall uphold the
        remainder of this

                                       16
<Page>

        Agreement, and shall negotiate an amendment which, as far as legally
        feasible, maintains the economic balance between the parties.

11.6    This Agreement shall not be assignable by either of the parties without
        the prior written consent of the other party (which consent shall not be
        unreasonably withheld), except that Licensee without the consent of
        Licensor may assign this Agreement to an Affiliate or to a successor in
        interest or to a transferee of all or substantially all of the portion
        of the business to which this Agreement relates after giving the
        Licensor reasonable prior notice of such assignment.

11.7    Subject to the limitations on assignment herein, this Agreement shall be
        binding upon and inure to the benefit of said assigns of Licensee and
        Licensor. Any such assignee of a party's interest shall expressly assume
        in writing the performance of all the terms and conditions of this
        Agreement to be performed by said party.

11.8    Any dispute, controversy or claim arising under sub-clause 5.4(c) or 6.3
        of this Agreement will be submitted to mediation in accordance with the
        WIPO Mediation Rules. The place of mediation will be London. The
        language to be used in the mediation will be English. If, and to the
        extent that, any such dispute, controversy or claim has not been settled
        pursuant to the mediation within 60 days of the commencement of the
        mediation, it will, upon the filing of a request for arbitration by
        either party, be referred to and finally determined by arbitration in
        accordance with the WIPO Arbitration Rules. The arbitral tribunal will
        consist of a sole arbitrator. The place of arbitration will be London.

11.9    The parties to this Agreement intend that by virtue of the Contracts
        (Rights of Third Parties) Act 1999 the University of Oxford and the
        people referred to in clause 8.3 will be able to enforce the terms of
        this Agreement as if the University of Oxford and the people referred to
        in clause 8.3 were a party to it.

AS WITNESS the hands of authorised signatories for the parties on the date first
mentioned above

SIGNED for and on behalf of
ISIS INNOVATION LIMITED:

NAME:          Dr. T. Cook
POSITION:      Managing Director
SIGNATURE:     /s/ T. Cook

SIGNED for and on behalf of
TOLERRX, INC.:

NAME:          Dr. Douglas J. Ringler
POSITION:      Chief Executive Officer
SIGNATURE:     /s/ Douglas J. Ringler

                                       17
<Page>

THIS AMENDMENT AGREEMENT, dated December 19, 2002 (the "Effective Date") is made
BETWEEN:

(1)     ISIS INNOVATION LIMITED, a company registered in England (No. 02199542),
whose registered office is at University Offices, Wellington Square, Oxford
OX1 2JD, England (the "Licensor"); and

(2)     TOLERRX, INC., a Delaware corporation whose principal place of business
is at 675 Mass Ave., Cambridge, MA 02139 (the "Licensee").

        WHEREAS, Licensor and Licensee entered into a License Agreement dated
February 1, 2001 that is directed to Stealth Technology (the "License
Agreement"); and

        WHEREAS, the Licensor and Licensee desired 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.     All defined terms of the License Agreement shall have the same
meaning in this Amendment.

        2.     Rewrite clause 5.9(a) of the License Agreement in its entirety to
read as follows:

               5.9(a)  Subject to clause 5.10, if any of the Licensed
               Technology under which Licensee is licensed hereunder
               is infringed by a third party, Licensee shall have the
               right and option but not the obligation to bring an
               action for infringement at its sole expense, against
               such third party in the name of Licensor and/or in the
               name of Licensee, and to join Licensor as a party, if
               required. Licensee shall promptly notify Licensor of
               any such infringement and shall keep Licensor informed
               as to the prosecution of any action for such
               infringement. No settlement, consent judgement or other
               voluntary final disposition of the suit which adversely
               affects Licensor and/or Licensed Technology may be
               entered into without the consent of Licensor, which
               consent shall not unreasonably be withheld.

        3.     Rewrite clause 5.12 of the License Agreement in its entirety to
read as follows:

               5.12    In any infringement suit either party may
               institute to enforce the rights in Licensed Technology
               pursuant to this Agreement, the other party hereto
               shall, at the request of the party initiating such
               suit, co-operate in all respects and, to the extent
               possible, have its employees testify when requested and
               make available relevant records, papers, information,
               samples,

<Page>

               specimens, and the like, provided that the Licensee
               provides the Licensor with an indemnity in terms
               satisfactory to the Licensor against all reasonable
               out-of-pocket costs incurred in connection with
               rendering co-operation requested hereunder For the
               avoidance of doubt, all expenses of the Licensor agreed
               by the Licensee in advance will be considered
               reasonable.

               4.      Rewrite clause 6.3(a) of the License Agreement in it
entirety to read as follows:

               --6.3   (a) For as long as any Licensed Products are used
               or marketed by the Licensee, the Licensee will pay
               royalties to the Licensor equal to the following
               percentages of all Net Sales of Licensed Products sold
               by the Licensee and gross up-front and milestone (as
               opposed to periodically recurring or running-earned)
               consideration received by the Licensee under or in
               respect of sublicenses or sub-sub-licenses granted by
               the Licensee with respect to the Licensed Technology in
               each License Year, as calculated on a
               Licensed-Product-by-Licensed Product basis:

<Table>
<Caption>
                Cumulative Net Sales and Gross Up-front
                             Consideration                          Percentage
               <S>                                                   <C>
               Net Sales and gross up-front consideration
               for a Licensed Product of up to [*******]             [*******]
               in a License Year

               Net Sales and gross up-front consideration
               for a Licensed Product of greater than                [*******]
               [*******] up to [*******] in a License Year

               Net Sales and gross up-front consideration
               for a Licensed Product of over [*******]              [*******]
               up to [*******] in a License Year

               Net Sales and gross up-front consideration
               for a Licensed Product of over [*******]              [*******]
               in a License Year
</Table>

               Subject to the following, no royalties shall be payable under
this sub-clause 6.3 with respect to payments made to the Licensee by a
sub-licensee for stock or equity or for research performed or to be performed by
the Licensee specifically relating to the development of the Licensed
Technology. Where a sub-licensee or a third party who, at a later stage, becomes
a sub-licensee (a "Purchaser"), purchases stock or equity in the Licensee,
royalties will be payable in accordance with this sub-clause 6.3 on the amount
paid by the Purchaser to the Licensee for that

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

                                        2
<Page>

stock or equity to the extent that the amount paid by the Purchaser exceeds the
fair market value for that stock or equity, and such excess is disguised
consideration for the sub-license. If there is a dispute as to the fair market
value, it shall be submitted to arbitration under clause 11.8---

               5.      Rewrite clause 6.4 of the License Agreement in its
entirety to read as follows:

               --6.4   For as long as the Licensee sub-licenses the
               Licensed Technology, the Licensee will pay royalties to
               the Licensor of [*******] of all royalties paid to
               Licensee by a sublicensee for sales of a Licensed
               Product.--

               6.      Rewrite clause 6.5 of the License Agreement in its
entirety to read as follows:

               --6.5   In the event that the royalties paid to the
               Licensor under clauses 6.3 and 6.4 in a License Year do
               not exceed the following amounts in respect of the
               relevant License Year (the "Minimum Sum"), the Licensee
               must make up the difference between the aggregate of
               the royalties paid and the Minimum Sum in that License
               Year; and will do so concurrently with the report under
               clause 5.4(c) which immediately follows the end of the
               period:

<Table>
<Caption>
                           License Year                             Minimum Sum
               <S>                                                   <C>
               The 12-month period which begins on the               [*******]
               Effective Date ("License Year 1")

               The next 12 month period (i.e. beginning              [*******]
               on the first anniversary of the Effective
               Date) ("License Year 2")

               License Year 3                                        [*******]

               License Year 4                                        [*******]

               License Year 5 and thereafter                         [*******]
</Table>

                       In the event that no royalties are due to the
               Licensor in a License Year, the Licensee must pay the
               Minimum Sum to the Licensor.

                       The payments under this Clause 6.5 shall
               terminate on the initiation by the Licensee or a
               sublicensee or sub-sublicensee of a Phase I Clinical
               Trial for a Licensed Product.--

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

                                        3
<Page>

               7.      Rewrite clause 6.6 of the License Agreement in its
entirety to read as follows:

               --6.6   (a) The Licensee will pay to the Licensor the
               following non-refundable non-creditable milestone
               payments within thirty (30) days after the occurrence
               of the specified events (including, for the avoidance
               of doubt, where the specified events are performed by a
               sub-licensee) (the "Milestones") in respect of only the
               first Licensed Product produced by the Licensee:

<Table>
<Caption>
                               Event                                  Amount
               <S>                                                   <C>
               Demonstration of tolerance induction in               [*******]
               vivo to an antibody engineered to contain
               sequences from a species different than the
               experimental animals

               Initiation of Phase I clinical trials                 [*******]

               Initiation of Phase II clinical trials                [*******]

               Initiation of Phase III clinical trials               [*******]

               Entering into first sub-license by Licensee           [*******]

               Grant of patent in respect of the Licensed            [*******]
               Technology in the first of the European
               Union, the United States of America, Japan,
               Canada or Australia

               Approved for marketing in the United                  [*******]
               States by the Food and Drug
               Administration
</Table>

                       (b) In addition, for each additional Licensed
               Product after the first Licensed Product that is
               approved for marketing in the United States by the Food
               and Drug Administration, Licensee shall pay to Licensor
               [*******] within thirty (30) days after such event,
               which payment shall be non- creditable and
               non-refundable.--

        8.     Rewrite clause 6.12 of the License Agreement in its entirety to
               read as follows:

               6.12    Subject to the following, if the Licensee is
               obliged to pay royalties to third parties (other than
               the Licensee's Affiliates), for the right to make, use
               or sell a Licensed Product, then the Licensee

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

                                        4
<Page>

               shall be entitled to deduct from the royalty payment
               due to the Licensor a portion of the royalty payment
               actually made to such third party as the Licensee has
               negotiated with the Licensor, but in any event, not
               greater than [*******] of the royalty payment due to
               the Licensor. This clause 6.12 will not apply until the
               Licensee is obliged to pay in aggregate to third
               parties and the Licensor more than [*******] of Net
               Sales in royalties and will only apply to the amount of
               royalties payable to third parties which exceed
               [*******] of Net Sales.

        9.     Rewrite clause 7.2 of the License Agreement in its entirety to
read as follows:

               7.2     If either party commits a material breach of this
               Agreement or fails to exert the efforts determined by
               the parties or by arbitration under clause 5.4 (c) and
               the breach or failure is not remedied (where
               remediable) within the period allowed by notice given
               by the other party in writing calling on the party in
               breach or failure to effect such remedy (such period
               being not less than thirty (30) days), the other party
               may by further written notice terminate this Agreement
               immediately.

        10.    Rewrite clause 7.6 of the License Agreement in its entirety to
read as follows:

               Clauses 3, 5.12, 5.13, 7.6, 7.8, 7.9, 7.10, 7.11, 8, 9,
               10 and 11.4 shall survive the termination or expiration
               of this Agreement for whatever reason

        11.    Rewrite clause 7.9 in its entirety to read as follows:

               7.9     Upon the granting of a sub-license under this
               Agreement, at the request of Licensee and if the
               sub-licensee is not engaged in a business that the
               Licensor, acting reasonably, would consider to be
               inconsistent with or contrary to the Licensor's
               position as a subsidiary of the University, the
               Licensor will provide the sub-licensee with a letter
               agreement in the form set out in Schedule 1.

        12.    Rewrite clause 8.1 (c) of the License Agreement in its entirety
to read as follows:

               8.1 (c) The Licensor shall promptly notify the Licensee
               of any claim or threatened claim under this sub-clause
               8.1 (a) and shall, at the cost of the Licensee, fully
               co-operate with all reasonable requests of the Licensee
               with respect thereto.

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

                                        5
<Page>

        13.    Rewrite clause 8.5 of the License Agreement in its entirety to
read as follows:

               8.5     The Licensor's maximum liability with respect
               to payment of damages awarded to the Licensee by a
               court of law under or otherwise in connection with this
               Agreement or its subject matter, shall not exceed the
               return of all royalty and Milestone payments paid by
               the Licensee to the Licensor under this Agreement,
               together with interest on the balance of such moneys
               from time to time outstanding, accruing from day to day
               at two percent over the Barclays Bank plc base rate
               from time to time in force and compounded annually as
               at 31 December and if the damages awarded exceed such
               amount, such excess may be credited against future
               royalties and milestones owed by Licensee under this
               Agreement as and when they become due, provided that
               the amount payable by the Licensee to the Licensor will
               not be reduced below [*******] of the royalties and
               milestone payments that would have been due if such
               excess payments had not been credited.

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

        15.    All references in the License Agreement to the "Agreement" shall
be deemed to include this Agreement.

        16.    This Amendment Agreement shall be governed by English Law. The
Licensee submits to the non-exclusive jurisdiction of the English courts with
respect to any dispute which may arise out of or in connection with this
Amendment Agreement.

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

                                        6
<Page>

        AS WITNESS the hands of authorized signatories for the parties on the
date first mentioned above.

SIGNED for and on behalf of
ISIS INNOVATION LIMITED:

Name:      Mr. T. Hockaday
Position:  Executive Director
           Isis Innovation Ltd

Signature: /s/ T. Hockaday
          ------------------------------

SIGNED for and on behalf of
TOLERRX, INC.:

Name:      Douglas J. Ringler
Position:  President and Chief Executive Officer

Signature: /s/ Douglas J. Ringler
          ------------------------------

                                        7

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