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Agreement - Celgene Corp., Children's Medical Center Corp., Bioventure Investments kft and EntreMed Inc.

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                                    AGREEMENT

                                  by and among

                     CHILDREN'S MEDICAL CENTER CORPORATION,

                              CELGENE CORPORATION,

                           BIOVENTURE INVESTMENTS KFT

                                       and

                                 ENTREMED, INC.
  (Solely for purposes of Sections 2.2.5, 2.7, 5, 7, 8.1, 12, 13, 15.2, 15.7,
                                  15.9 and 16)


<PAGE>

                                    AGREEMENT



         This Agreement, dated this ___ day of August, 2001, is made by and
among CELGENE CORPORATION, a Delaware corporation located at 7 Powder Horn
Drive, Warren, New Jersey 07059 ("CELGENE"), CHILDREN'S MEDICAL CENTER
CORPORATION, a corporation duly organized and existing under the laws of the
Commonwealth of Massachusetts and having its principal office at 300 Longwood
Avenue, Boston, Massachusetts 02115 ("CMCC"), BIOVENTURE INVESTMENTS KFT, a
company located at Wesselenyi ut 16, Budapest, Hungary, organized under the laws
of Hungary ("BIOVENTURE"), and, solely for purposes of Sections 2.2.5, 2.7, 5,
7, 8.1, 12, 13, 15.2, 15.7, 15.9 and 16 of this Agreement, EntreMed, Inc., a
Delaware corporation located at 9640 Medical Center Drive, Suite 200, Rockville,
Maryland 20850 ("ENTREMED").

         WHEREAS, CMCC is the owner of certain PATENT RIGHTS, as hereinafter
defined, relating to THALIDOMIDE (as hereinafter defined) and certain analogs of
THALIDOMIDE, and has the right to grant licenses under said PATENT RIGHTS;

         WHEREAS, pursuant to that certain License Agreement, dated as of May
26, 1994, by CMCC and ENTREMED (as subsequently amended, the "ENTREMED
LICENSE"), CMCC licensed to ENTREMED the PATENT RIGHTS;

         WHEREAS, pursuant to that certain Agreement, dated as of December 9,
1998 by and between ENTREMED and CELGENE (the "CELGENE SUBLICENSE"), ENTREMED
exclusively sublicensed to CELGENE its THALIDOMIDE rights under the PATENT
RIGHTS, as set forth in the ENTREMED LICENSE; and



                                       1

<PAGE>

         WHEREAS, BIOVENTURE desires to buy, and ENTREMED has agreed to sell to
BIOVENTURE, all of ENTREMED'S right, title and interest to certain payments
otherwise due ENTREMED under the CELGENE SUBLICENSE, net of any payments owed to
CMCC by ENTREMED pursuant to the ENTREMED LICENSE;

         WHEREAS, ENTREMED, BIOVENTURE, CMCC and CELGENE desire to terminate the
ENTREMED LICENSE and the CELGENE SUBLICENSE and for CELGENE to enter into this
Agreement, pursuant to which CMCC shall directly grant CELGENE an exclusive
license under the PATENT RIGHTS relating to THALIDOMIDE, which will supercede
and replace in its entirety the ENTREMED LICENSE, to the extent same relates to
THALIDOMIDE, and the CELGENE SUBLICENSE;

         WHEREAS, CMCC and ENTREMED shall execute, concurrently herewith, a new
agreement relating to the THALIDOMDE analog rights licensed to ENTREMED under
the ENTREMED LICENSE (the "NEW ANALOG AGREEMENT"), which will supercede and
replace in its entirety the ENTREMED LICENSE to the extent same relates to
THALIDOMIDE analogs;

         WHEREAS, the ENTREMED LICENSE and the CELGENE SUBLICENSE will
automatically terminate upon execution of both this Agreement and the NEW ANALOG
AGREEMENT;

         NOW, THEREFORE, in consideration of the mutual promises and other good
and valuable consideration, the parties agree as follows:


                             SECTION 1 - DEFINITIONS

The terms used in this Agreement have the following meaning:




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<PAGE>

1.1      The term "AFFILIATE" as applied to either party shall mean any company
         or other legal entity other than the party in question in whatever
         country organized, controlling controlled by or under common control
         with that party. The term "control" means ownership or control,
         directly or indirectly, of at least fifty percent (50%) of the
         outstanding stock or voting rights entitled to elect directors.

1.2      The term "CALENDAR QUARTER" shall mean the period of three (3)
         consecutive calendar months ending on March 31, June 30, September 30
         or December 31, as the case may be.

1.3      The term "CELGENE DEVELOPED INTELLECTUAL PROPERTY" shall mean CELGENE
         DEVELOPED PATENT RIGHTS and CELGENE DEVELOPED TECHNOLOGY RIGHTS.

         (a)   The term "CELGENE DEVELOPED PATENT RIGHTS" The term "CELGENE
               DEVELOPED PATENT RIGHTS" shall mean any United States or foreign
               patents or patent applications filed by CELGENE, or an AFFILIATE,
               successor or assign thereof at any time subsequent to December 9,
               1998, in which CELGENE has a transferrable interest, relating to
               a modification of a PRODUCT described in any of the PATENT RIGHTS
               or a method of using such PRODUCT, which modification is (a)
               necessary for the manufacture, use, or sale of such PRODUCT, and
               (b) then currently in use by CELGENE at the time CMCC exercises
               its rights under Section 15.4(b), for the manufacture, use, or
               sale of such PRODUCT.

         (b)   The term "CELGENE DEVELOPED TECHNOLOGY RIGHTS" shall mean any
               TECHNOLOGY RIGHTS developed, obtained, or acquired by CELGENE or
               an AFFILIATE, successor or assign thereof at any time subsequent
               to December 9,


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<PAGE>

               1998 in which CELGENE has a transferrable interest, relating to a
               modification of a PRODUCT described in any of the PATENT RIGHTS
               or a method of using or use of such PRODUCT, which modification
               is (a) necessary for the manufacture, use, or sale of such
               PRODUCT, and (b) then currently in use by CELGENE at the time
               CMCC exercises its rights under Section 15.4(b) for the
               manufacture, use, or sale of such PRODUCT.

1.4      The term "CMCC Royalty Purchaser(s)" shall mean the buyers, if any, of
         all or a portion of CMCC's right, title and interest to certain
         payments otherwise due CMCC under this Agreement, as expressly
         permitted pursuant to Section 13 hereof.

1.5      The term "EFFECTIVE DATE" shall mean the date of this Agreement.

1.6      The term "FIELD" shall mean the use of THALIDOMIDE, alone or in
         combination, in humans or animals, including without limitation any and
         all diagnostic, prophylactic, therapeutic, and research and development
         uses.

1.7      The term "FIRST COMMERCIAL SALE" shall mean, in each country of the
         TERRITORY, the first sale after December 9, 1998, whether prior to or
         after the EFFECTIVE DATE hereof, in such country to a THIRD PARTY in
         connection with the nationwide introduction of any PRODUCT by CELGENE,
         its AFFILIATES or SUBLICENSEES following marketing and/or pricing
         approval by the appropriate governmental agency for the country in
         which the sale is to be made and, when governmental approval is not
         required, the first sale in that country in connection with the
         nationwide introduction of a PRODUCT in that country.



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<PAGE>

1.8      The term "LICENSED METHOD" shall mean any method the practice of which,
         by an unlicensed third party, would infringe any VALID CLAIM of the
         PATENT RIGHTS in the country in which it is practiced.

1.9      The term "MIXED PATENT RIGHTS" shall mean any of the PATENT RIGHTS that
         claim, either generically or specifically, either (i) both (a)
         THALIDOMIDE and/or the use or manufacture thereof and (b) THALIDOMIDE
         analogs and/or the use or manufacture thereof; or (ii) THALIDOMIDE
         analogs and/or the use or manufacture thereof, but not THALIDOMIDE
         and/or the use or manufacture thereof; which MIXED PATENT RIGHTS, as of
         the EFFECTIVE DATE, are set forth on Appendix B, which may be amended
         from time to time as necessary to accurately identify same.

1.10     The term "MIXED PATENT THALIDOMIDE CLAIM" shall mean any claim of any
         MIXED PATENT RIGHTS that would be infringed by the making, using,
         offering for sale, selling or importing of THALIDOMIDE and/or a
         PRODUCT.

1.11     The term "NDA" shall mean a New Drug Application filed with the United
         States Food and Drug Administration.

1.12     The term "NET SALES" means the gross amount received by CELGENE or its
         AFFILIATES or SUBLICENSEES for sale of PRODUCTS to THIRD PARTIES, less:
         (i) cost of freight, postage, and freight insurance, (if paid by
         seller); (ii) sales taxes, value added taxes, excise taxes, and customs
         duties; (iii) cost of export licenses and any taxes, fees or other
         charges associated with the exportation or importation of PRODUCTS;
         (iv) rebates accrued, incurred or paid to Federal Medicare and State
         Medicaid and any other price reductions required by a governmental
         agency; (v) rejected shipments, returns, and retroactive deductions;
         (vi) the amount received for sales which become the



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<PAGE>
         subject of a subsequent temporary or partial recall by a regulatory
         agency for safety or efficacy reasons outside the control of CELGENE;
         and (vii) customary cash, quantity, and trade discounts; provided,
         however, that a sale or transfer to an AFFILIATE or SUBLICENSEE for
         re-sale by such AFFILIATE or SUBLICENSEE shall not be considered a sale
         for the purpose of this provision but the resale by such AFFILIATE or
         SUBLICENSEE shall be a sale for such purposes. A "sale" shall also
         include a transfer or other disposition for consideration, but not such
         transfers or dispositions, without consideration, for pre-clinical,
         clinical, regulatory or governmental purposes prior to receiving
         marketing approval for the specific indication for which such transfer
         is made. In the event that consideration in addition to or in lieu of
         money is received for PRODUCT, such consideration shall be added to the
         NET SALES as valued on the day of receipt thereof by CELGENE. To the
         extent that a PRODUCT is sold in other than an arms length transaction,
         NET SALES shall be the fair market value of such PRODUCT if sold in an
         arms length transaction, less the costs identified in subsections
         (i)-(vi) of this Section 1.12. PRODUCT shall be considered "sold" at
         the earlier of (a) the transfer of title in such PRODUCT to a person
         other than an AFFILIATE or SUBLICENSEE of CELGENE or (b) the shipment
         of such PRODUCT from the manufacturing or warehouse facilities of
         CELGENE or its AFFILIATE or SUBLICENSEE to a THIRD PARTY.

1.13     The term "PATENT RIGHT(s)" shall mean:

         (a)   the United States patent applications and patents listed in
               Appendix A;

         (b)   the United States and foreign patents issued from applications
               listed in Appendix A and from divisionals and continuations of
               such applications;




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<PAGE>

         (c)   claims of United States continuation-in-part applications and of
               equivalent foreign applications, and of the resulting patent(s),
               that are directed to subject matter described in the United
               States and foreign applications listed in Appendix A;

         (d)   claims of all later-filed foreign patent applications, and of the
               resulting patents, that are directed to subject matter described
               in the United States patents and/or patent applications in the
               foregoing subsections of this Section 1.13;

         (e)   any reissues, re-examinations, renewals or extensions of United
               States patents described in the foregoing subsections of this
               Section 1.13.

1.14     The term "PRODUCT" shall mean any article of manufacture, substance,
         material, chemical, formulation or composition for use in the FIELD
         which is or includes THALIDOMIDE as an active ingredient, including,
         without limitation, a composition that comprises THALIDOMIDE and a
         non-steroidal anti-inflammatory compound(s). PRODUCT expressly excludes
         THALIDOMIDE analogs.

1.15     The term "SUBLICENSEE" shall mean any THIRD PARTY licensed by CELGENE
         to make, have made, use, offer to sell, sell or import any PRODUCT
         and/or practice any LICENSED METHOD in the FIELD or any portion
         thereof.

1.16     The term "TERRITORY" shall mean the entire world.

1.17     The term "THALIDOMIDE" shall mean a compound with the chemical
         structure described as 2-(2,6-Dioxo-3-piperidinyl)-1H-isoindole-
         1,3(2H)-dione, or as otherwise defined in the Merck Index, entry 9390,
         12th ed., and pharmaceutically acceptable salts thereof.

1.18     The term "TECHNOLOGY RIGHTS" shall mean any information relating to
         PRODUCTS that is not covered by a patent or patent application,
         including without


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<PAGE>
         limitation technical and non-technical information, know-how, methods,
         processes, procedures, compositions, devices, formulae, protocols,
         techniques, software, designs, drawings, plans, diagrams,
         specifications, data, the results of tests or assays, and all other
         information relating to PRODUCTS.

1.19     The term "THALIDOMIDE PATENT RIGHT(s)" shall mean any of the PATENT
         RIGHTS that claim, either generically or specifically, (a) THALIDOMIDE
         and/or the use or manufacture thereof but not (b) THALIDOMIDE analogs
         and/or the use or manufacture thereof; which THALIDOMIDE PATENT RIGHTS,
         as of the EFFECTIVE DATE, are set forth on Appendix C, which may be
         amended from time to time as necessary to accurately identify same.

1.20     The term "THIRD PARTY(IES)" shall mean a person or entity who or which
         is neither a party hereto nor an AFFILIATE of a party hereto. Except
         for purposes of Sections 2.2.5, 2.7, 5, 7, 8.1, 12, 13, 15.2, 15.7,
         15.9 and 16, ENTREMED shall be considered a THIRD PARTY.

1.21     The term "VALID CLAIM" shall mean an issued claim of an unexpired
         patent ("ISSUED VALID CLAIM") or a claim of a pending patent
         application, which shall not have been withdrawn, canceled or
         disclaimed, or held invalid or unenforceable by a court of competent
         jurisdiction in an unappealed or unappealable decision. Notwithstanding
         the foregoing to the contrary, a claim of a pending patent application,
         divisional application or continuation-in-part shall cease to be a
         VALID CLAIM if no patent has issued on such claim within five (5) years
         of the filing of such claim, provided that such claim shall once again
         become a VALID CLAIM on the issue date of a patent that subsequently
         issues and covers such claim.




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<PAGE>

1.22     The use herein of the plural shall include the singular, and the use of
         the masculine shall include the feminine.

                                SECTION 2 - GRANT

2.1      Grant. CMCC hereby grants to CELGENE an exclusive, worldwide right and
         license under the THALIDOMIDE PATENT RIGHTS and the MIXED PATENT
         RIGHTS, subject to the provisions of Sections 2.2 and 2.6 herein, to
         make, have made, use, lease, offer for sale, sell and import PRODUCTS
         and practice LICENSED METHODS in the FIELD.

2.2      Reservation of Research Rights.
         -------------------------------

         2.2.1 CMCC-Retained Rights. The license granted in Section 2.1 of this
               Agreement is subject to, and expressly limited by, CMCC's
               non-exclusive rights to make and use, and to grant to other
               research and educational institutions (each, a "THIRD PARTY
               RESEARCHER"), subject to their prior written agreement to be
               bound by the terms and conditions of this Section 2.2, a
               non-exclusive license to make and use, the technology and the
               subject matter described and claimed in the PATENT RIGHTS for
               research and educational purposes only, whether or not such
               activities are sponsored by or otherwise paid for by or performed
               in conjunction with or on behalf of any commercial entity (the
               "CMCC RETAINED RIGHTS")

         2.2.2 Option(s) to Celgene on THALIDOMIDE INVENTIONS . If, in the
               exercise of the CMCC RETAINED RIGHTS, CMCC or any THIRD PARTY
               RESEARCHER makes any potentially patentable inventions or
               discoveries


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<PAGE>

               relating to THALIDOMIDE or to PRODUCTS ("THALIDOMIDE INVENTION"),
               including without limitation any modifications to any PRODUCT or
               any improvement to any of the THALIDOMIDE PATENT RIGHTS or any
               MIXED PATENT THALIDOMIDE CLAIMS, CMCC shall, and CMCC shall
               contractually obligate any such THIRD PARTY RESEARCHER to,
               promptly notify CELGENE and BIOVENTURE in writing, provided that
               the notice to BIOVENTURE need not contain any confidential
               technical information. CMCC hereby grants, and shall
               contractually obligate each such THIRD PARTY RESEARCHER to grant,
               CELGENE an exclusive option ("Option") to enter into a license
               agreement granting CELGENE an exclusive, worldwide,
               royalty-bearing license, with the right to sublicense, under any
               patent applications and patents directed to such THALIDOMIDE
               INVENTION, to make, have made, use, lease, offer for sale, sell,
               and import PRODUCTS and practice methods in the FIELD.

         2.2.3 Exercise of Option(s). The term of each Option granted to CELGENE
               hereunder shall run and be exercisable independently on a
               THALIDOMIDE INVENTION-by-THALIDOMIDE INVENTION basis, beginning
               on the date on which CELGENE receives notice thereof pursuant to
               Section 2.2.2 and continuing for a period of three (3) months
               ("Option Period"). In the event that this Agreement terminates
               during any Option Period(s) for any reason other than due to
               CELGENE's breach of this Agreement, each such Option Period, and
               the rights and obligations of the parties under Sections 2.2.3,
               2.2.4 and 2.2.5 with respect to the relevant THALIDOMIDE
               INVENTION, shall continue in full force and effect for the
               duration of each such three (3) month period and, if applicable,
               the


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<PAGE>

               relevant Negotiation Period. The relevant THALIDOMIDE INVENTION
               shall be deemed to be CMCC's CONFIDENTIAL INFORMATION, pursuant
               to the terms of this Agreement. CELGENE may exercise its Option
               with respect to any THALIDOMIDE INVENTION at any time during the
               relevant Option Period by providing written notice to CMCC and/or
               such THIRD PARTY RESEARCHER, as applicable, with a copy to
               BIOVENTURE, stating its intention to exercise such Option.
               CELGENE agrees that it shall reimburse CMCC for all reasonable
               out-of-pocket expenses, including reasonable attorney's fees,
               incurred in connection with the preparation, filing and
               prosecution of patent applications directed towards the relevant
               THALIDOMIDE INVENTION in the FIELD ("Patent Costs") during the
               Option Period, provided that if CELGENE notifies CMCC in writing
               that it rejects its Option with respect to the relevant
               THALIDOMIDE INVENTION, CELGENE shall have no obligation to pay
               for any Patent Costs incurred after the receipt of such notice by
               CMCC. If CELGENE expressly rejects its Option or the Option
               Period lapses without any such written notice from CELGENE, then
               CMCC and such THIRD PARTY RESEARCHER shall have no further
               obligation to CELGENE with respect to the relevant THALIDOMIDE
               INVENTION.

         2.2.4 Negotiation of License Agreement. Upon the exercise by CELGENE of
               the Option set forth in Section 2.2.2, CELGENE and CMCC and/or
               such THIRD PARTY RESEARCHER, as applicable, shall negotiate in
               good faith for up to three (3) months for the financial and other
               material terms, including diligence and indemnification terms, of
               the license agreement ("Initial Negotiation


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<PAGE>

               Period"). If written agreement has been reached between CMCC
               and/or the THIRD PARTY RESEARCHER, as applicable, on the one
               hand, and CELGENE, on the other hand, regarding such terms during
               such three (3) month period, then the Initial Negotiation Period
               shall automatically, without any further action by either party,
               be extended for an additional three (3) months (or any longer
               period as agreed to by the parties) (together with the Initial
               Negotiation Period, the "Negotiation Period") to permit
               negotiation and execution of a mutually-agreeable license
               agreement. CELGENE agrees that it shall reimburse CMCC for all
               Patent Costs incurred during the Negotiation Period, provided
               that (a) if the parties cease good faith negotiations with
               respect to the relevant THALIDOMIDE INVENTION, CELGENE may notify
               CMCC in writing, and CELGENE shall have no obligation to pay for
               any Patent Costs incurred after the receipt of such notice by
               CMCC and (b) if CMCC and/or the THIRD PARTY RESEARCHER, as
               applicable, on the one hand, and CELGENE, on the other hand,
               execute a license agreement relating to the relevant THALIDOMIDE
               INVENTION, the terms and conditions of such agreement shall
               govern the payment of Patent Costs incurred thereafter. CELGENE
               agrees that it shall not be entitled to reduce the royalties owed
               under Section 4 of this Agreement, pursuant to the terms of
               Section 7.7 hereof or otherwise, to offset payments owed to a
               THIRD PARTY RESEARCHER pursuant to a license agreement executed
               as set forth in this Section 2.2. CELGENE and CMCC agree that the
               payments due pursuant to Section 4 of this Agreement shall not be
               affected by any payment terms of a license agreement between
               CELGENE and CMCC executed as set forth in this


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<PAGE>
               Section 2.2, it being understood that CELGENE and CMCC are free
               to agree that payments due under such license agreement may be
               offset or otherwise reduced by payments due hereunder. BIOVENTURE
               agrees that it shall not be entitled to any portion of any amount
               that becomes payable by CELGENE to CMCC or any THIRD PARTY
               RESEARCHER pursuant to a license agreement executed as set forth
               in this Section 2.2. CMCC agrees, and shall contractually
               obligate such THIRD PARTY RESEARCHER, as applicable, to agree,
               that it will not, during the Option Period and the Negotiation
               Period, enter into or negotiate with any third party any
               agreement or contract that would be inconsistent with the grant
               of the Option to CELGENE hereunder. If the parties are unable to
               negotiate and execute a mutually acceptable license agreement
               within the Negotiation Period, CMCC and such THIRD PARTY
               RESEARCHER shall have no further obligation to CELGENE with
               respect to the relevant THALIDOMIDE INVENTION. CMCC shall notify
               BIOVENTURE if the Negotiation Period expires without execution of
               a license agreement between CELGENE and CMCC.

         2.2.5 Entremed Release. ENTREMED agrees that all rights ENTREMED may
               have in any THALIDOMIDE INVENTION, and any obligations of CMCC to
               disclose to ENTREMED a THALIDOMIDE INVENTION or to grant to, or
               negotiate with, ENTREMED a license to a THALIDOMIDE INVENTION,
               shall be subject to the terms of Sections 2.2.2, 2.2.3 and 2.2.4.

2.3      CELGENE'S Right To Sublicense. Subject to the provisions of Section
         7.5, CMCC hereby grants to CELGENE the right to sublicense the rights,
         duties and/or obligations



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<PAGE>

         granted to it hereunder in the THALIDOMIDE PATENT RIGHTS and/or the
         MIXED PATENT RIGHTS, in whole or in part, in the FIELD, provided that,
         in all cases, CELGENE shall first (a) provide CMCC with such
         commercially relevant, publicly available information about the
         potential SUBLICENSEE as CELGENE determines, in its sole good faith
         judgment, to be necessary to enable CMCC to make a reasonably informed
         decision regarding the relevant commercial capacity of such potential
         SUBLICENSEE, such information to be provided to CMCC sufficiently in
         advance of CELGENE's expected date of entering into a sublicense
         agreement with the potential SUBLICENSEE so as to allow CMCC to
         reasonably consider such information, and (b) obtain the written
         consent of CMCC to the potential SUBLICENSEE, which consent shall not
         be unreasonably withheld, delayed, or conditioned. Prior to granting or
         withholding its consent, CMCC shall provide to BIOVENTURE copies of any
         information received from CELGENE about the potential SUBLICENSEE and
         shall consult with BIOVENTURE thereon; provided that CMCC shall not be
         required to obtain the consent of BIOVENTURE in providing or
         withholding CMCC's consent to such potential SUBLICENSEE, and that
         neither such consultation nor any consultation with any CMCC ROYALTY
         PURCHASER(s) shall in any way delay or otherwise obstruct the delivery
         of CMCC's notice regarding its consent. In the event that CMCC
         reasonably withholds consent to any potential SUBLICENSEE, CELGENE
         shall nonetheless have the right to enter into a sublicense agreement
         with such SUBLICENSEE and, in such event, CELGENE shall guarantee and
         be responsible for the payment of all royalties and other amounts due
         and the making of reports under this Agreement by such SUBLICENSEE and
         SUBLICENSEE's compliance with all applicable terms of this


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<PAGE>
         Agreement. CMCC and CELGENE acknowledge and agree that CMCC shall have
         no right of consent with respect to the terms and conditions of the
         relevant sublicense agreement, and that CELGENE shall use reasonable
         efforts to negotiate sublicense agreements that are commercially
         reasonable according to contemporaneous prevailing standards within the
         pharmaceutical industry.

2.4      Sublicense Obligations.
         -----------------------

         (a)   CELGENE agrees that any sublicense granted by it shall provide
               that the obligations to CMCC of Sections 2, 4.7, 4.8, 4.9, 9, 10,
               11, 12, 15 and 16 of this Agreement, and, to the extent
               applicable pursuant to the terms of the relevant sublicense,
               Sections 7.2, 7.3, 7.4, 7.5, 7.6, shall be binding upon the
               SUBLICENSEE as if it were a party to this Agreement. CELGENE
               further agrees to attach copies of the above-identified Sections
               to any such sublicense agreements. Further, CELGENE hereby agrees
               that every sublicensing agreement to which it shall be a party
               and which shall relate to the rights, privileges and license
               granted hereunder shall contain a statement setting forth the
               event or date upon which CELGENE'S exclusive rights, privileges
               and license hereunder shall terminate.

         (b)   CELGENE agrees to forward to each of CMCC and BIOVENTURE a copy
               of any and all fully executed sublicense agreements and any
               amendments thereto, and further agrees to forward to each of CMCC
               and BIOVENTURE annually a copy of such reports received by
               CELGENE from its SUBLICENSEES during the preceding twelve (12)
               month period under the sublicenses as shall be pertinent to a
               royalty accounting under said sublicense agreements.




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<PAGE>

         (c)   CELGENE shall not receive from SUBLICENSEES anything of value in
               lieu of cash payments based upon payment obligations of any
               sublicense under this Agreement, without the express prior
               written permission of CMCC which shall not be unreasonably
               withheld or delayed. Prior to granting or withholding its
               consent, CMCC shall consult with BIOVENTURE as to the
               advisibility of granting or withholding consent; provided that
               CMCC shall not be required to obtain the consent of BIOVENTURE,
               and that such consultation shall in no way delay or otherwise
               obstruct the delivery of CMCC's notice regarding its consent.

2.5      No Other Rights. The license granted hereunder shall not be construed
         to confer any rights upon CELGENE by implication, estoppel or otherwise
         as to any technology not specifically set forth in Appendices A, B
         and/or C hereof.

2.6      Government Rights. The license granted in Section 2.1 of this Agreement
         is subject to, and expressly limited by, any rights the United States
         government may have pursuant to Public Laws 96-517 and 98-620.

2.7      Acknowledgement of Transfers Under Celgene Sublicense. CELGENE and
         ENTREMED represent and warrant that the obligations described in
         Sections 2.5 and 2.6 of the CELGENE SUBLICENSE necessary for CELGENE to
         fulfill its obligations under this Agreement were fully satisfied.

                            SECTION 3 - DUE DILIGENCE

3.1      In the United States.
         ---------------------

         (a)   CELGENE shall initiate and diligently use reasonable efforts to
               develop, or to file for regulatory approval of or register, and
               to market and sell PRODUCTS in the


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<PAGE>
               United States. Reasonable efforts with respect to the development
               and/or pursuit of regulatory approval or registration for
               PRODUCTS in the United States shall be demonstrated by CELGENE or
               a SUBLICENSEE thereof, either prior to or after the EFFECTIVE
               DATE hereof, (i) developing and pursuing regulatory approval for
               PRODUCTS for those uses CELGENE, in good faith, determines to be
               commercially and scientifically reasonable, including but not
               limited to (a) one (1).........., (b) one (1)........., and (c)
               one (1).........; and (ii) funding and conducting clinical trials
               for PRODUCTS for other uses in order to enhance scientific
               knowledge with regard to such PRODUCTS, including for the
               publication of data and results in scientific journals, whether
               or not such clinical trials result in or facilitate the pursuit
               of regulatory approval.

         (b)   CELGENE shall provide a written summary report to CMCC within
               thirty (30) days after June 30th and December 31st of each
               calendar year concerning the efforts being made in accordance
               with this Section 3.1 with respect to PRODUCTS. CELGENE shall
               provide CMCC with any additional information reasonably requested
               by CMCC in this respect. All information provided to CMCC
               pursuant to this Section 3.1 shall be treated by CMCC as
               CELGENE's CONFIDENTIAL INFORMATION, in accordance with Section 5
               hereof. Except as set forth in Section 3.4, in the event that
               CELGENE fails to meet any of its obligations under this Section
               3.1 with respect to PRODUCTS in the United States, and such
               failure is not cured within sixty (60) days after written notice
               thereof is received by CELGENE from CMCC, then CMCC shall have
               the right and option to terminate the license granted in this
               Agreement and this Agreement


                                      -17-
<PAGE>

               by giving CELGENE sixty (60) days prior written notice thereof,
               in accordance with Section 15.4(b)(ii).

3.2      Outside the United States.
         --------------------------

         (a)   Diligence. CELGENE shall initiate and diligently use reasonable
               efforts to develop, or to file for regulatory approval of or
               register, and to market and sell PRODUCTS in Europe, in Canada,
               and in the Pacific Rim, Japan, and Australia (collectively, the
               "PACIFIC RIM"). Reasonable efforts with respect to the
               development and/or pursuit of regulatory approval or registration
               for PRODUCTS in Europe, Canada, and the PACIFIC RIM shall be
               demonstrated by CELGENE, or a SUBLICENSEE thereof, either prior
               to or after the EFFECTIVE DATE hereof, pursuing regulatory
               approval for PRODUCTS (a) in Italy, France, the United Kingdom,
               and Germany (in the case of Europe), and in Japan and one other
               country of the PACIFIC RIM (in the case of the PACIFIC RIM),
               within.........from the date of the first FDA approval of a
               PRODUCT for an.........or........., whichever occurs earlier; and
               (b) in Canada, within.........from the date of the first FDA
               approval of a PRODUCT for an.........or........., whichever
               occurs earlier.

         (b)   Cooperation. If CELGENE fails to use reasonable efforts in
               Europe, Canada, or the PACIFIC RIM, as set forth in Section
               3.2(a) of this Agreement, or to sublicense such rights to a THIRD
               PARTY, then CMCC shall have the right to COOPERATE with CELGENE
               to find an appropriate SUBLICENSEE for such rights. For purposes
               of this Section 3.2(b), and for Sections 3.3(b) and 3.4, the term
               "COOPERATE" means that (i) CMCC shall have the right to (a)
               identify for


                                      -18-
<PAGE>

               CELGENE a THIRD PARTY interested in entering into a sublicense
               agreement with CELGENE, pursuant to which CELGENE would grant
               such THIRD PARTY a sublicense of the rights, duties and/or
               obligations granted to CELGENE hereunder in the THALIDOMIDE
               PATENT RIGHTS and/or the MIXED PATENT RIGHTS, in whole or in
               part, in the relevant region and/or for the relevant indication
               and (b) to the extent CELGENE so requests, assist or participate
               in the drafting and/or negotiation of such sublicense agreement,
               and (ii) CELGENE shall have the obligation to negotiate in good
               faith with such THIRD PARTY for such sublicense agreement. Prior
               to and from time to time during the exercise of its right to
               COOPERATE, CMCC shall consult with BIOVENTURE as to potential
               SUBLICENSEES; provided that (x) CMCC shall not be required to
               obtain the consent of BIOVENTURE; (y) BIOVENTURE's right to
               consult shall not create in CELGENE or in CMCC any right to
               withhold or delay the fulfillment of its obligation to COOPERATE.
               If CELGENE fails to negotiate in good faith with such THIRD PARTY
               to execute such a sublicense agreement within a reasonable period
               of time, and CELGENE has not, within such time period, entered
               into such a sublicense agreement with another THIRD PARTY or
               otherwise cured the relevant breach of its diligence obligations
               under this Section 3.2, then CMCC shall have the right and option
               to terminate the licenses granted in the region where such
               failure has occurred, i.e., Europe, Canada, or the PACIFIC RIM,
               respectively, by giving CELGENE sixty (60) days prior written
               notice thereof, in accordance with Section 15.4(b)(ii).




                                      -19-
<PAGE>

3.3      For PRODUCTS For Use In Animals.
         -------------------------------

         (a)   Diligence. CELGENE shall initiate and diligently use reasonable
               efforts to develop, or to file for regulatory approval of or
               register, and to market and sell PRODUCTS for use in animals.
               Such reasonable efforts shall be demonstrated by CELGENE
               obtaining regulatory approval for the sale of a PRODUCT for use
               in animals within ......... of the EFFECTIVE DATE in the United
               States and, outside the United States, in one of the following
               countries: Italy, France, the United Kingdom, or Germany.

         (b)   Cooperation. If CELGENE fails to use reasonable efforts either in
               the United States or outside the United States, as set forth in
               Section 3.3(a) of this Agreement, or to sublicense its rights in
               such regions to a THIRD PARTY, then CMCC shall have the right to
               COOPERATE with CELGENE to find an appropriate SUBLICENSEE for
               such rights. Prior to and from time to time during the exercise
               of its right to COOPERATE, CMCC shall consult with BIOVENTURE as
               to potential SUBLICENSEES; provided that (x) CMCC shall not be
               required to obtain the consent of BIOVENTURE and (y) BIOVENTURE's
               right to consult shall not create in CELGENE or CMCC any right to
               withhold or delay the fulfillment of its obligation to COOPERATE.
               If CELGENE fails to negotiate in good faith with such THIRD PARTY
               to execute such a sublicense agreement within a reasonable period
               of time, and CELGENE has not, within such time period, entered
               into such a sublicense agreement with another THIRD PARTY or
               otherwise cured the relevant breach of its diligence obligations
               under


                                      -20-
<PAGE>
               this Section 3.3, then CMCC shall have the right and option to
               terminate the licenses granted in and to such PRODUCTS for use in
               animals in the region where such failure has occurred, i.e.,
               inside the United States or outside the United States, as
               applicable, by giving CELGENE sixty (60) days prior written
               notice thereof, in accordance with Section 15.4(b)(ii).

3.4      For PRODUCTS For Ophthalmologic Use. If CELGENE fails to use reasonable
         efforts in the United States to develop, or to file for regulatory
         approval of or register, and to market and sell PRODUCTS for
         ophthalmologic use or to sublicense its rights in the United States for
         such indication to a THIRD PARTY, or CELGENE notifies CMCC that it does
         not intend to take any further activities with respect to PRODUCTS for
         ophthalmologic use in the United States, then CMCC shall have the right
         to COOPERATE with CELGENE to find an appropriate SUBLICENSEE for such
         rights. Prior to and from time to time during the exercise of its right
         to COOPERATE, CMCC shall consult with BIOVENTURE as to potential
         SUBLICENSEES; provided that (x) CMCC shall not be required to obtain
         the consent of BIOVENTURE and (y) BIOVENTURE's right to consult shall
         not create in CELGENE or CMCC any right to withhold or delay the
         fulfillment of its obligation to COOPERATE. If CELGENE fails to
         negotiate in good faith with such THIRD PARTY to execute such a
         sublicense agreement within a reasonable period of time, and CELGENE
         has not, within such time period, entered into such a sublicense
         agreement with another THIRD PARTY or otherwise cured the relevant
         breach of its diligence obligations under this Section 3.4, then CMCC
         shall have the right and option to terminate the licenses granted in
         and to


                                      -21-
<PAGE>
         PRODUCTS for ophthalmologic use in the United States by giving CELGENE
         sixty (60) days prior written notice thereof, in accordance with
         Section 15.4(b)(ii).

3.5      CELGENE's Discretion. CMCC agrees that (i) the decision regarding which
         uses to pursue regulatory approval of PRODUCTS for, and/or to fund and
         conduct clinical trials of PRODUCTS for, pursuant to Sections 3.1, 3.2,
         3.3 and 3.4 of this Agreement, shall be made by and in the sole
         discretion of CELGENE; and (ii) with respect to the manner in which
         regulatory approval is sought and/or clinical trials are funded and
         conducted, CELGENE shall have sole discretion, including, without
         limitation, complete control over all regulatory submissions of
         PRODUCTS to the appropriate regulatory agencies worldwide, including
         whether, when, and how to file, maintain, withdraw, or abandon an
         application for regulatory approval of PRODUCTS.

                              SECTION 4 - ROYALTIES

4.1      Royalty Payments.
         ----------------

         (a)   First Twelve Years From FIRST COMMERCIAL SALE. CELGENE shall pay
               to CMCC ......... of, and shall pay to BIOVENTURE ......... of,
               the following royalties on the NET SALES of PRODUCTS sold by
               CELGENE or its AFFILIATES in each country of the TERRITORY: (i)
               for the first consecutive twelve (12) years from the date of the
               FIRST COMMERCIAL SALE of a PRODUCT in each country of the
               TERRITORY, and, separately and independently, (ii) for the first
               consecutive twelve (12) years from the date of the FIRST
               COMMERCIAL SALE of each PRODUCT that contains, as a second


                                      -22-
<PAGE>
               active ingredient, a compound other than THALIDOMIDE, in each
               country of the

               TERRITORY:

<TABLE>
<CAPTION>

               <S>           <C>
               (i) ......... of NET SALES up to ......... of such sales;
               (ii) ........ of NET SALES between ......... and ......... of such sales;
               (iii) ....... of NET SALES between ......... and ......... of such sales; and
               (iv) ........ of NET SALES over ......... of such sales.
</TABLE>

         (b)   After Twelve Years From FIRST COMMERCIAL SALE. For each PRODUCT
               in each country in the TERRITORY in which the twelve (12) year
               period provided for in Section 4.1(a) of this Agreement shall
               have terminated, CELGENE shall pay to CMCC.........of, and shall
               pay to BIOVENTURE.........of, the following royalties on the NET
               SALES of such PRODUCT covered by an ISSUED VALID CLAIM of the
               PATENT RIGHTS that are sold by CELGENE or its AFFILIATES in such
               country:
<TABLE>
<CAPTION>

               <S>           <C>
               (i)    ...... of NET SALES up to.........of such sales;
               (ii)   ...... of NET SALES between.........and.........of such sales;
               (iii)  ...... of NET SALES between.........and.........of such sales; and
               (iv)   ...... of NET SALES over.........of such sales;

</TABLE>

               and such royalties under this Section 4.1(b) shall be payable
               until the last to expire PATENT RIGHT containing an ISSUED VALID
               CLAIM covering such PRODUCT sold by CELGENE or its AFFILIATES in
               such country.

4.2      Sublicensing Payments and Royalties.
         -----------------------------------

         (a)   If CELGENE grants a sublicense of its exclusive rights under this
               Agreement, pursuant to Section 2.3 of this Agreement, in any
               country(ies) of the


                                      -23-
<PAGE>
               TERRITORY, CELGENE shall pay to CMCC ......... of, and shall pay
               to BIOVENTURE ......... of, (i) ......... of any non-royalty
               consideration, including but not limited to any sublicensing
               and/or milestone payments received by CELGENE pursuant to such
               sublicense for the sublicense of CELGENE's rights hereunder, and
               (ii) ......... of the royalty income paid by SUBLICENSEES to
               CELGENE on NET SALES of PRODUCTS including, without limitation,
               ......... of any lump-sum commercialization milestone payments
               due to CELGENE upon the occurrence of certain threshold levels of
               NET SALES of PRODUCTS by such SUBLICENSEE.

         (b)   If CELGENE grants a sublicense of any of its rights under this
               Agreement in any area of the FIELD or any country of the
               TERRITORY with respect to which CMCC and CELGENE are COOPERATING
               pursuant to Sections 3.2(b), 3.3(b) and 3.4 of this Agreement,
               CELGENE shall pay to CMCC.........of, and shall pay to
               BIOVENTURE.........of,.........of any non-royalty consideration,
               including but not limited to any sublicensing and/or milestone
               payments received by CELGENE pursuant to such sublicense. CELGENE
               shall also pay to CMCC.........of, and shall pay to
               BIOVENTURE.........of, the following, as applicable: (i) if
               CELGENE and CMCC are COOPERATING in any country(ies) pursuant to
               Section 3.2(b) of this Agreement,.........of the royalty income
               paid by SUBLICENSEES to CELGENE on NET SALES, in such
               country(ies), of PRODUCTS; and (ii) if CELGENE and CMCC are
               COOPERATING in any country(ies) with regard to PRODUCTS for use
               in animals pursuant to Section 3.3(b) of this
               Agreement,.........of the royalty income paid by SUBLICENSEES


                                      -24-
<PAGE>

               to CELGENE on NET SALES in such country(ies) of such PRODUCTS;
               and (iii) if CELGENE and CMCC are COOPERATING in the United
               States with regard to PRODUCTS for ophthalmologic use pursuant to
               Section 3.4 of this Agreement,.........of the royalty income paid
               by SUBLICENSEES to CELGENE on NET SALES in the United States of
               such PRODUCTS for such use.

4.3      Later-Issued VALID CLAIM. In the event that there is no ISSUED VALID
         CLAIM of a PATENT RIGHT in a country within the TERRITORY on the date
         the twelve (12) year period provided for in Section 4.1(a) of this
         Agreement expires, no royalties shall be owed by CELGENE under Sections
         4.1(b) and 4.2 of this Agreement on PRODUCTS sold by CELGENE or its
         AFFILIATES or SUBLICENSEES in such country; provided, however, that if
         a VALID CLAIM of a PATENT RIGHT thereafter issues in such country,
         CELGENE shall thereafter pay to CMCC ......... of, and shall pay to
         BIOVENTURE ......... of, royalties on the NET SALES in such country of
         PRODUCTS covered by such ISSUED VALID CLAIM of the PATENT RIGHTS that
         are sold by CELGENE or its AFFILIATES or SUBLICENSEES, according to the
         royalty rates set forth in Sections 4.1(b) and 4.2 of this Agreement,
         and such royalties under this Section 4.3 shall be payable until the
         last to expire PATENT RIGHT containing an ISSUED VALID CLAIM covering
         the PRODUCTS sold by CELGENE or its AFFILIATES or SUBLICENSEES in such
         country.

4.4      No Multiple Royalties. No multiple royalties shall be payable because
         any PRODUCT, its manufacture, use, importation, lease, offer for sale
         or sale is or shall be covered by more than one PATENT RIGHT.




                                      -25-
<PAGE>

4.5      Milestone Payment. CELGENE will, at its own expense, timely pay to CMCC
         a milestone payment of ......... upon the first filing, after the
         EFFECTIVE DATE, of a Product License Application, NDA or supplemental
         NDA in the United States for a PRODUCT for any indication, unless such
         milestone payment has otherwise been paid by CELGENE pursuant to
         Section 8.2(e) hereof.

4.6      THIRD PARTY Sales. In any country where sales by a THIRD PARTY of a
         PRODUCT(s) for a similar dosage form and/or route of administration
         (except where sales by a THIRD PARTY are made pursuant to a sublicense
         from CELGENE):

         (a)   are equal to or greater than ......... of the dollar market share
               for such PRODUCT in such country ("MARKET SHARE"), but less than
               ......... of the MARKET SHARE, then the royalty payable to CMCC
               and BIOVENTURE pursuant to Sections 4.1 and 4.3 of this Agreement
               in respect of such country shall be reduced by ......... ;

         (b)   are equal to or greater than ......... of the MARKET SHARE, but
               less than ......... of the MARKET SHARE, then the royalty payable
               to CMCC and BIOVENTURE pursuant to Sections 4.1 and 4.3 of this
               Agreement in respect of such country shall be reduced by
               ......... ;

         (c)   are equal to or greater than ......... of the MARKET SHARE, but
               less than ......... of the MARKET SHARE, then the royalty payable
               to CMCC and BIOVENTURE pursuant to set Sections 4.1 and 4.3 of
               this Agreement in respect of such country shall be reduced by
               .........; and


                                      -26-
<PAGE>

         (d)   are equal to or greater than ......... of the MARKET SHARE, then
               the royalty payable to CMCC and BIOVENTURE pursuant to Sections
               4.1 and 4.3 of this Agreement in respect of such country shall be
               reduced by .........;

         provided that, with respect to (a), (b), (c) and/or (d) above,
         royalties payable to CMCC and BIOVENTURE in respect of any country,
         based on NET SALES by CELGENE or its AFFILIATES in such country, shall
         never be reduced below ......... of NET SALES in each royalty bracket.
         For purposes of this Section 4.6, oral dosage forms shall include,
         without limitation, all capsule, caplet, tablet, and liquid
         formulations for oral administration.

4.7      Recordkeeping. CELGENE shall keep, and shall require each of its
         AFFILIATES and SUBLICENSEES to keep, full and accurate books of account
         containing all particulars relevant to its sales of PRODUCTS that may
         be necessary for the purpose of calculating all royalties payable to
         CMCC and BIOVENTURE pursuant to Sections 4.1, 4.2 and 4.3 of this
         Agreement. Such books of account, as well as all reasonably necessary
         supporting data, shall be kept at the principal place of business of
         CELGENE and each AFFILIATE and SUBLICENSEE, as applicable, for the five
         (5) years next following the end of the calendar year to which each
         shall pertain, and shall be open for inspection by an independent
         certified public accountant reasonably acceptable to CELGENE, upon
         reasonable notice during normal business hours at BIOVENTURE or CMCC'S
         expense, as the case may be, for the sole purpose of verifying royalty
         statements or compliance with this Agreement. In the event the
         inspection determines that royalties due BIOVENTURE or CMCC for any
         period have been underpaid by ......... or more, which


                                      -27-
<PAGE>

         underpayment has not since been remedied, then CELGENE and/or its
         AFFILIATE or SUBLICENSEE, as applicable, shall pay for all costs of the
         inspection. All royalty payments set forth in this Agreement shall, if
         overdue, bear interest until payment at a per annum rate of .........
         above the prime rate in effect at Fleet Bank on the due date. The
         payment of such interest shall not foreclose BIOVENTURE or CMCC, as the
         case may be, from exercising any other rights it may have as a
         consequence of the lateness of any payment. All information and data
         reviewed in the inspection shall be used only for the purpose of
         verifying royalties and shall be treated as CELGENE'S CONFIDENTIAL
         INFORMATION subject to the obligations of this Agreement. No audit
         shall be conducted hereunder more frequently than once during any
         twelve (12) month period, irrespective of whether such audit is on
         behalf of CMCC or on behalf of BIOVENTURE.

4.8      Quarterly Payments and Reports. In each year the amount of royalty due
         shall be calculated quarterly as of the end of each CALENDAR QUARTER
         and shall be paid quarterly within the forty-five (45) days next
         following such date. Every such payment shall be supported by the
         accounting described in Section 4.9 of this Agreement. All royalties
         due BIOVENTURE and CMCC are payable in United States dollars.
         BIOVENTURE and CMCC shall each designate, in writing, one bank account
         to which CELGENE shall make all payments due hereunder to each,
         respectively. When PRODUCTS are sold for currency other than United
         States dollars, the earned royalties will first be determined in the
         foreign currency of the country in which such PRODUCTS were sold and
         then converted into equivalent United States funds. The exchange rate
         will be that rate quoted in The Wall Street Journal, NY Edition on the
         last business day of the CALENDAR QUARTER in which such sales were
         made.




                                      -28-
<PAGE>

4.9      Accounting Reports. With each quarterly payment, CELGENE shall deliver
         to each of BIOVENTURE and CMCC a full and accurate accounting to
         include at least the following information:

         (a)   Quantity of PRODUCT subject to royalty sold, by country, by
               CELGENE, its AFFILIATES or SUBLICENSEES;

         (b)   Total receipts for each PRODUCT subject to royalty, by country
               and, to the extent used in any royalty calculations during such
               quarter, the exchange rate set forth in Section 4.8 of this
               Agreement;

         (c)   Deductions applicable as provided in Section 1.12;

         (d)   Compensation on PRODUCTS received from SUBLICENSEES pursuant to a
               sublicense of CELGENE's rights under this Agreement;

         (e)   Total royalties and/or compensation payable to BIOVENTURE and
               CMCC, as the case may be; and

         (f)   Names and addresses of all SUBLICENSEES of CELGENE.



                           SECTION 5 - CONFIDENTIALITY

5.1      Confidential Information. During the term of this Agreement, it is
         contemplated that each of CMCC, CELGENE, ENTREMED and BIOVENTURE (the
         "disclosing party") may disclose to the other(s) proprietary and
         confidential technology, inventions, technical information, material,
         reagents, biological materials and the like, and any other information
         which is deemed to be confidential pursuant to this Agreement, which
         are owned or controlled by the disclosing party or which the disclosing
         party is obligated to


                                      -29-
<PAGE>
         maintain in confidence and which is designated by the disclosing party
         as confidential ("CONFIDENTIAL INFORMATION"). Each of CMCC, CELGENE,
         ENTREMED and BIOVENTURE agrees (a) not to disclose the disclosing
         party's CONFIDENTIAL INFORMATION to any other person or entity,
         including THIRD PARTIES, other than its AFFILIATES, agents,
         representatives and employees, and (b) to maintain the disclosing
         party's CONFIDENTIAL INFORMATION in strict confidence, to cause all of
         its AFFILIATES, agents, representatives and employees to maintain the
         disclosing 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 disclosing party, and not to use such
         CONFIDENTIAL INFORMATION for any purpose other than as provided under
         this Agreement. The secrecy obligations of the parties with respect to
         CONFIDENTIAL INFORMATION shall continue for a period ending ten (10)
         years from the termination of this Agreement.

5.2      Non-Confidential Information. The obligations of confidentiality will
         not apply to information that:

         (a)   was known to the receiving party or generally known to the public
               prior to its disclosure hereunder through no fault of the
               disclosing party or any agent, representative or employee
               thereof; or

         (b)   subsequently becomes known to the public by some means other than
               a breach of this Agreement, including publication and/or laying
               open to inspection of any patent applications or patents;



                                      -30-
<PAGE>

         (c)   is subsequently disclosed to the receiving party by a THIRD PARTY
               having a lawful right to make such disclosure and who is not
               under an obligation of confidentiality to the disclosing party;

         (d)   is required by law, rule, regulation or bona fide legal process
               to be disclosed, to the extent so required, provided that the
               party wishing to make such disclosure takes all reasonable steps
               to restrict and maintain confidentiality of such disclosure and
               provides reasonable notice to the disclosing party; or

         (e)   is approved for release by the parties.

5.3      Disclosure To THIRD PARTIES. The obligations of Section 5.1
         notwithstanding,

         (a)   CELGENE may disclose CONFIDENTIAL INFORMATION disclosed to it
               hereunder to THIRD PARTIES:

               (i)  who need to know the same in order to obtain regulatory
                    approval for a PRODUCT under this Agreement,

               (ii) who need to know the same in order to work towards the
                    commercial development of PRODUCT(s) on behalf of CELGENE,

               provided that, with respect to (i) and (ii) above, such THIRD
               PARTIES are bound by obligations of confidentiality and non-use
               at least as stringent as those set forth herein; and

         (b)   each party hereto may disclose CONFIDENTIAL INFORMATION disclosed
               to it hereunder to a THIRD PARTY to the extent such disclosure is
               required by any applicable laws or the rules or regulations of
               any applicable securities exchange or quotation system or market.




                                      -31-
<PAGE>

5.4      Disclosure To Sublicensees and CMCC ROYALTY PURCHASER(S). CELGENE may
         disclose CMCC's CONFIDENTIAL INFORMATION to an actual or potential
         SUBLICENSEE without CMCC's consent, provided that such actual or
         potential SUBLICENSEES are bound by obligations of confidentiality and
         non-use at least as stringent as those set forth herein. CMCC may
         disclose to actual and potential CMCC ROYALTY PURCHASERS the following
         information without CELGENE's, ENTREMED's or BIOVENTURE's consent,
         provided that such CMCC ROYALTY PURCHASERS first agree in writing to be
         bound by obligations of confidentiality and non-use at least as
         stringent as those set forth herein: (a) this Agreement, including any
         amendments thereto, and the Consents (as defined in Section 5.5); (b)
         information disclosed to CMCC pursuant to Section 4 hereof; (c)
         information disclosed to CMCC pursuant to Sections 2.3 and 2.4(b)
         hereof; and (d) any notices provided to CMCC pursuant to the
         requirements of this Agreement, and the disclosures of (a) through (d)
         above may include without limitation any CONFIDENTIAL INFORMATION
         contained therein.

5.5      Public Statements. Neither CELGENE, BIOVENTURE, ENTREMED, CMCC nor any
         CMCC ROYALTY PURCHASER(S) may issue a public statement, including
         without limitation a press release, with regard to (1) this Agreement,
         (2) the CMCC Acknowledgment and Consent made and entered into August
         __, 2001 by and among CMCC, ENTREMED and BIOVENTURE, or (3) the Celgene
         Acknowledgment and Consent made and entered into as of August __, 2001
         by and among CELGENE, ENTREMED and BIOVENTURE ((2) and (3), together,
         the "Consents") without the prior written consent of the other parties,
         which consent in any case shall not be


                                      -32-
<PAGE>

         unreasonably withheld; provided that (a) to the extent required by any
         applicable law, including without limitation any applicable securities
         law or the rules or regulations of any applicable securities exchange
         or quotation system or market or any legal or administrative
         proceeding, any of CELGENE, BIOVENTURE, ENTREMED, CMCC or the CMCC
         ROYALTY PURCHASER(S), may make public statements or otherwise disclose
         the matters covered by this Agreement or the Consents and (b) nothing
         herein shall prohibit any party hereto or the CMCC ROYALTY
         PURCHASER(S), or any of their respective AFFILIATES, from disclosing
         such party's (or the CMCC ROYALTY PURCHASER's, as applicable) royalty
         interest hereunder (1) to any of their respective AFFILIATES, agents,
         representatives and employees, (2) in any annual or other periodic
         corporate report, (3) to any financing sources (whether equity or debt)
         and its legal, financial and industry advisors, or (4) to any actual or
         potential underwriter, and its legal, accounting and industry advisors,
         in connection with securing financing. In accordance with the rules and
         regulations promulgated by the Securities and Exchange Commission, if
         this Agreement is required to be filed by any party hereto or by the
         CMCC ROYALTY PURCHASER(S), the filing party will request that this
         Agreement be treated as confidential to the maximum permissible extent.



                     SECTION 6 - ADVERSE MEDICAL EXPERIENCES

6.1      Adverse Medical Experience Reporting. CELGENE shall comply fully with
         all applicable medical/adverse experience reporting requirements in all
         countries where CELGENE intends to carry out clinical trials and/or
         market PRODUCT.


                                      -33-
<PAGE>

                               SECTION 7 - PATENTS

7.1      Patent Prosecution
         ------------------

         (a)  THALIDOMIDE PATENT RIGHTS.
              --------------------------

               (1)  By CELGENE. CELGENE shall have the right, but not the
                    obligation, to prepare, file, prosecute and maintain the
                    THALIDOMIDE PATENT RIGHTS, at CELGENE's sole expense,
                    through patent counsel selected by CELGENE and reasonably
                    acceptable to CMCC. CELGENE agrees to ADVISE CMCC and
                    BIOVENTURE with respect thereto. For purposes of this
                    Section 7, to "ADVISE" shall mean to provide copies of all
                    substantive documents received from or filed in any patent
                    office, including without limitation copies of each patent
                    application, office action, response to office action,
                    declaration, information disclosure statement, request for
                    terminal disclaimer, request for patent term extension and
                    request for reissue or reexamination.

               (2)  By CMCC. In the event that CELGENE decides not to prepare,
                    file, prosecute and/or maintain any of the THALIDOMIDE
                    PATENT RIGHTS in any country(ies) or region(s) in the
                    TERRITORY, CELGENE shall notify CMCC and BIOVENTURE
                    promptly, and in any event in sufficient time for CMCC to
                    preserve its rights thereunder, and (a) any rights granted
                    to CELGENE in and to such THALIDOMIDE PATENT


                                      -34-
<PAGE>

                    RIGHTS, in the relevant country or region in the TERRITORY,
                    shall terminate; (b) CELGENE shall have no obligation to pay
                    for any costs incurred after the receipt of such notice by
                    CMCC in connection with the preparation, filing, prosecution
                    or maintenance of any such THALIDOMIDE PATENT RIGHTS in the
                    relevant country or region in the TERRITORY; and (c) CMCC
                    shall thereafter have the sole right, but not the
                    obligation, to prepare, file, prosecute and/or maintain such
                    THALIDOMIDE PATENT RIGHTS in such country(ies) or region(s)
                    in the TERRITORY, at CMCC's sole expense. CMCC agrees to
                    ADVISE BIOVENTURE with respect thereto.

               (3)  By BIOVENTURE. In the event that CMCC decides not to
                    prepare, file, prosecute and/or maintain any of the
                    THALIDOMIDE PATENT RIGHTS in any country(ies) or region(s)
                    in the TERRITORY, CMCC shall notify BIOVENTURE promptly, and
                    in any event in sufficient time for BIOVENTURE to preserve
                    its economic rights hereunder, CMCC shall have no obligation
                    to pay for any costs incurred after the receipt of such
                    notice by BIOVENTURE in connection with the preparation,
                    filing, prosecution or maintenance of any such THALIDOMIDE
                    PATENT RIGHTS in the relevant country or region in the
                    TERRITORY; and BIOVENTURE shall thereafter have the sole
                    right, but not the obligation, to prepare, file, prosecute
                    and/or maintain such THALIDOMIDE PATENT RIGHTS in such
                    country(ies) or region(s) in the TERRITORY, at BIOVENTURE's
                    sole expense, using patent counsel selected by


                                      -35-
<PAGE>

                    BIOVENTURE and reasonably acceptable to CMCC. BIOVENTURE
                    agrees to ADVISE CMCC with respect thereto.





                                      -36-
<PAGE>

(b)      MIXED PATENT RIGHTS.
         --------------------

               (1)  By ENTREMED. Subject to Section 7.1(b)(2), ENTREMED shall
                    have the sole right, but not the obligation, to prepare,
                    file, prosecute and maintain the MIXED PATENT RIGHTS, at
                    ENTREMED's sole expense, through patent counsel selected by
                    ENTREMED and reasonably acceptable to CELGENE and CMCC.
                    ENTREMED shall ADVISE CMCC with respect to any MIXED PATENT
                    RIGHTS, and shall ADVISE BIOVENTURE with respect to any
                    MIXED PATENT THALIDOMIDE CLAIMS.

               (2)  Cooperation on MIXED PATENT THALIDOMIDE CLAIMS. Whichever
                    parties are prosecuting the THALIDOMIDE PATENT RIGHTS and
                    the MIXED PATENT RIGHTS, respectively, shall consult with
                    each other in good faith regarding the preparation, filing,
                    prosecution and maintenance of all MIXED PATENT THALIDOMIDE
                    CLAIMS, and, to the extent necessary to accomplish same, the
                    MIXED PATENT RIGHTS, including without limitation the
                    content, timing and jurisdiction of the filing of


                                      -37-
<PAGE>

                    same. A copy of each document or a draft thereof pertaining
                    to the preparation, filing, prosecution, or maintenance of
                    each MIXED PATENT THALIDOMIDE CLAIM, including but not
                    limited to each patent application, office action, response
                    to office action, declaration, information disclosure
                    statement, request for terminal disclaimer, request for
                    patent term extension and request for reissue or
                    reexamination of any MIXED PATENT RIGHTS, to the extent
                    MIXED PATENT THALIDOMIDE CLAIMS are or may be affected,
                    shall be provided to the party prosecuting the MIXED PATENT
                    THALIDOMIDE CLAIMS as follows: documents received from any
                    patent office and/or counsel's analysis thereof shall be
                    provided promptly after receipt; and drafts of all documents
                    to be filed in any patent office shall be provided
                    sufficiently prior to their filing deadlines to allow for
                    review and comment by the party(ies) prosecuting the
                    THALIDOMIDE PATENT RIGHTS, which comments the party(ies)
                    prosecuting the MIXED PATENT RIGHTS shall incorporate in
                    good faith. In order to protect its commercial interests,
                    the party(ies) prosecuting the THALIDOMIDE PATENT RIGHTS may
                    request that certain MIXED PATENT THALIDOMIDE CLAIMS be
                    prepared, filed, prosecuted, and/or maintained, or that such
                    steps be undertaken in certain countries or regions in the
                    TERRITORY, and patent counsel of the relevant party(ies)
                    prosecuting the MIXED PATENT RIGHTS shall follow such
                    request, at a cost to be shared by the parties on a basis to
                    be determined in good faith by such parties, taking into
                    account


                                      -38-
<PAGE>

                    the relative commercial value of such MIXED PATENT
                    THALIDOMIDE CLAMS to each. ENTREMED or, in accordance with
                    Section 7.1(b)(4), CMCC, shall have the right to take any
                    action that, in its judgment, is necessary to preserve any
                    claims of any MIXED PATENT RIGHTS that are not MIXED PATENT
                    THALIDOMIDE CLAIMS. In the event that information relating
                    to the prosecution of MIXED PATENT RIGHTS generally, and not
                    solely to the MIXED PATENT THALIDOMIDE CLAIMS, is provided
                    to the party(ies) prosecuting the THALIDOMIDE PATENT RIGHTS
                    pursuant to this Section 7.1(b)(2), ENTREMED or CMCC, as the
                    case may be, may require that the party(ies) prosecuting the
                    THALIDOMIDE PATENT RIGHTS limit disclosure of such
                    information, as it relates to MIXED PATENT RIGHTS generally,
                    to such party's outside counsel, and such party agrees to do
                    so, unless otherwise agreed by the parties.

               (3)  By CELGENE. In the event that ENTREMED decides not to
                    prepare, file, prosecute and/or maintain any MIXED PATENT
                    THALIDOMIDE CLAIM(s) in any country(ies) or region(s) in the
                    TERRITORY, ENTREMED shall notify CELGENE and CMCC promptly,
                    and in any event in sufficient time for CELGENE and CMCC to
                    preserve their rights hereunder, and: (a) any rights granted
                    to ENTREMED pursuant to the NEW ANALOG AGREEMENT in and to
                    such MIXED PATENT


                                      -39-
<PAGE>

                    THALIDOMIDE CLAIMS, in the relevant country or region in the
                    TERRITORY, shall terminate; and (b) CELGENE shall thereafter
                    have the sole right, but not the obligation, to prepare,
                    file, prosecute and/or maintain such MIXED PATENT
                    THALIDOMIDE CLAIM(s) in such country(ies) or region(s) in
                    the TERRITORY, at CELGENE's sole expense, and shall ADVISE
                    CMCC and BIOVENTURE with respect thereto.

               (4)  By CMCC. In the event that CELGENE decides not to prepare,
                    file, prosecute and/or maintain any of the MIXED PATENT
                    THALIDOMIDE CLAIMS in any country(ies) or region(s) in the
                    TERRITORY, or in the event that ENTREMED decides not to
                    prepare, file, prosecute and/or maintain any of the MIXED
                    PATENT RIGHTS that are not MIXED PATENT THALIDOMIDE CLAIMS,
                    CELGENE or ENTREMED, as the case may be, shall notify CMCC
                    and, in the case of MIXED PATENT THALIDOMIDE CLAIMS only,
                    BIOVENTURE, promptly, and in any event in sufficient time
                    for CMCC to preserve its rights thereunder, and: (a) any
                    rights granted to CELGENE in and to such MIXED PATENT
                    THALIDOMIDE CLAIMS, or, any rights granted to ENTREMED in
                    and to such MIXED PATENT RIGHTS, as the case may be, in the
                    relevant country or region in the TERRITORY, shall
                    terminate; (b) CELGENE or


                                      -40-
<PAGE>

                    ENTREMED, as the case may be, shall have no obligation to
                    pay for any costs incurred after the receipt of such notice
                    by CMCC in connection with the preparation, filing,
                    prosecution or maintenance of any such MIXED PATENT
                    THALIDOMIDE CLAIMS and/or MIXED PATENT RIGHTS in the
                    relevant country or region in the TERRITORY; and (c) CMCC
                    shall thereafter have the sole right, but not the
                    obligation, to prepare, file, prosecute and/or maintain such
                    MIXED PATENT THALIDOMIDE CLAIMS and/or MIXED PATENT RIGHTS
                    in such country(ies) or region(s) in the TERRITORY, at
                    CMCC's sole expense. CMCC shall ADVISE BIOVENTURE with
                    respect thereto.

               (5)  By BIOVENTURE. In the event that CMCC decides not to
                    prepare, file, prosecute and/or maintain any of the MIXED
                    PATENT THALIDOMIDE CLAIMS in any country(ies) or region(s)
                    in the TERRITORY, CMCC shall notify BIOVENTURE promptly, and
                    in any event in sufficient time for BIOVENTURE to preserve
                    its economic rights hereunder, CMCC shall have no obligation
                    to pay for any costs incurred after the receipt of such
                    notice by BIOVENTURE in connection with the preparation,
                    filing, prosecution or maintenance of any such MIXED PATENT
                    THALIDOMIDE CLAIMS in the relevant country or region in the



                                      -41-
<PAGE>

                    TERRITORY; and BIOVENTURE shall thereafter have the sole
                    right, but not the obligation, to prepare, file, prosecute
                    and/or maintain such MIXED PATENT THALIDOMIDE CLAIMS in such
                    country(ies) or region(s) in the TERRITORY, at BIOVENTURE's
                    sole expense. BIOVENTURE shall ADVISE CMCC with respect
                    thereto.

         (c)   Change In Status of Patent Rights. In the event that, during the
               course of prosecution in accordance with this Section 7.2, any
               patent application within the MIXED PATENT RIGHTS becomes a
               patent application within the THALIDOMIDE PATENT RIGHTS, or vice
               versa, the parties agree to promptly notify each other, and to
               cooperate in good faith to preserve the rights of the parties
               thereunder and to effectuate the foregoing provisions.

7.2      Infringement Actions.
         --------------------

         (a)   Notification. In the event that any party learns of the
               infringement of any THALIDOMIDE PATENT RIGHT and/or MIXED PATENT
               RIGHT by a THIRD PARTY, or the filing of a Declaratory Judgment
               action by a third party alleging the invalidity,
               unenforceability, or noninfringement of any of same ("DJ
               ACTION"), that party must promptly notify the other parties to
               this Agreement of the infringement or DJ ACTION, as the case may
               be, in writing, and must provide reasonable evidence of the
               infringement. The notifying party shall also inform the other
               parties to this Agreement whether, in its reasonable judgment,
               the infringement is alleged to be (1) the making, using, offering
               for sale, selling or importing of a product that is or contains
               THALIDOMIDE in such a way as to


                                      -42-
<PAGE>
               infringe any of the THALIDOMIDE PATENT RIGHTS and/or any MIXED
               PATENT THALIDOMIDE CLAIMS ("THALIDOMIDE INFRINGEMENT"); and/or
               (2) the making, using, offering for sale, selling or importing of
               a product that is or contains an analog of THALIDOMIDE in such a
               way as to infringe any claim of any MIXED PATENT RIGHTS
               ("NON-THALIDOMIDE INFRINGEMENT"). If any party disagrees with the
               characterization of the infringement as THALIDOMIDE INFRINGEMENT
               or NON-THALIDOMIDE INFRINGEMENT, the parties hereto shall
               promptly negotiate in good faith a resolution to such dispute. If
               the parties are unable to resolve such dispute within three (3)
               months, the matter shall be resolved in accordance with the
               provisions of Section 12. If the parties determine that such
               infringement is both a THALIDOMIDE INFRINGEMENT and a
               NON-THALIDOMIDE INFRINGEMENT, the parties shall cooperate in good
               faith to effectuate the applicable provisions of this Section 7
               to the fullest extent possible, taking into account the relative
               commercial interests of the parties. None of the parties will
               notify a THIRD PARTY (except their attorneys) of the infringement
               of any THALIDOMIDE PATENT RIGHT or MIXED PATENT RIGHT (including
               without limitation the foregoing characterization of the
               infringement), or of the filing of a DJ ACTION directed to any
               PATENT RIGHT, without first obtaining the consent of each party
               to this Agreement having rights in such PATENT RIGHT and/or in
               the relevant claims thereof, including without limitation any
               economic rights therein BIOVENTURE may have, either pursuant to
               this Agreement or pursuant to the NEW ANALOG AGREEMENT, which
               rights are


                                      -43-
<PAGE>

               actually or potentially impacted by such alleged infringement or
               DJ ACTION ("INTERESTED PARTY"), which consent shall not be
               unreasonably withheld or delayed.

         (b)   Enforcement by CELGENE of Certain PATENT RIGHTS against
               THALIDOMIDE INFRINGEMENT. If, at any time during the term of this
               Agreement, any party hereto furnishes notice, pursuant to Section
               7.2(a), of a THALIDOMIDE INFRINGEMENT, then CELGENE shall have
               the right, but not the obligation, to bring a suit or action to
               compel termination of such infringement, at CELGENE's sole
               expense. CELGENE may join CMCC, ENTREMED and/or BIOVENTURE as
               parties as required, at CELGENE's sole expense. CMCC, ENTREMED
               and BIOVENTURE independently shall each have the right to join,
               at its own expense, any such suit or action brought by CELGENE,
               to the extent same are INTERESTED PARTIES therein.

         (c)   Enforcement by ENTREMED of Certain PATENT RIGHTS against
               NON-THALIDOMIDE INFRINGEMENT. If, at any time during the term of
               this Agreement, any party hereto furnishes notice, pursuant to
               Section 7.2(a), of a NON-THALIDOMIDE INFRINGEMENT, then ENTREMED
               shall have the right, but not the obligation, to bring a suit or
               action to compel termination of such infringement, at ENTREMED's
               sole expense. ENTREMED may join CMCC, CELGENE and/or BIOVENTURE
               as parties as required, at ENTREMED's sole expense. CMCC, CELGENE
               and BIOVENTURE independently shall each have the right to join,
               at its own expense, any such suit


                                      -44-
<PAGE>

               or action brought by ENTREMED, to the extent same are INTERESTED
               PARTIES therein.

         (d)   Enforcement of PATENT RIGHTS by CMCC. If within six (6) months
               after the date of any notice provided under Section 7.2(a) of
               this Agreement with respect to any THALIDOMIDE INFRINGEMENT,
               CELGENE fails to cause such infringement to terminate, to enter
               into negotiations to sublicense such alleged infringer, or to
               bring a suit or action to compel termination, or if CELGENE
               notifies CMCC that it does not intend to take any action in such
               regard (which CELGENE shall do promptly upon making such
               decision, and which notice CELGENE shall likewise promptly
               provide to ENTREMED and BIOVENTURE, to the extent same are
               INTERESTED PARTIES), CMCC shall thereafter have the sole right,
               but not the obligation, to cause such infringement to terminate,
               including without limitation by granting a sublicense hereunder
               in accordance with Section 7.5 hereof, and/or to bring such suit
               or action to compel termination at CMCC's sole expense. If within
               six (6) months after the date of any notice provided under
               Section 7.2(a) of this Agreement with respect to any
               NON-THALIDOMIDE INFRINGEMENT, ENTREMED fails to cause such
               infringement to terminate, to enter into negotiations to
               sublicense such alleged infringer, or to bring a suit or action
               to compel termination, or if ENTREMED notifies CMCC that it does
               not intend to take any action in such regard (which ENTREMED
               shall do promptly upon making such decision, and which notice
               ENTREMED shall likewise promptly provide to CELGENE and
               BIOVENTURE, to the extent same are INTERESTED PARTIES), CMCC
               shall thereafter have the


                                      -45-
<PAGE>

               sole right, but not the obligation, to cause such infringement to
               terminate, including without limitation by granting a sublicense
               hereunder in accordance with Section 7.5 hereof, and/or to bring
               such suit or action to compel termination at CMCC's sole expense.
               CMCC may join ENTREMED, CELGENE and/or BIOVENTURE as parties as
               required, at CMCC's sole expense. ENTREMED, CELGENE and
               BIOVENTURE independently shall each have the right to join, at
               its own expense, any such suit or action brought by CMCC, to the
               extent same are INTERESTED PARTIES therein.

         (e)   Enforcement by BIOVENTURE of Certain PATENT RIGHTS against
               THALIDOMIDE INFRINGEMENT. If, within three (3) months after the
               date on which CMCC's right to bring any suit or action under
               Section 7.2(d) with respect to THALIDOMIDE INFRINGEMENT
               commences, CMCC fails to cause such infringement to terminate, to
               enter into negotiations to sublicense such alleged infringer, or
               to bring a suit or action to compel termination of such
               infringement, or if CMCC notifies BIOVENTURE that it does not
               intend to take any action in such regard (which CMCC shall do
               promptly upon making such decision), BIOVENTURE shall thereafter
               have the sole right, but not the obligation, to bring such suit
               or action to compel termination at BIOVENTURE's sole expense.
               BIOVENTURE may join ENTREMED, CELGENE and/or CMCC as parties as
               required, at BIOVENTURE's sole expense. ENTREMED, CELGENE and
               CMCC independently shall each have the right to join, at its own
               expense, any such suit or action brought by BIOVENTURE, to the
               extent same are INTERESTED PARTIES therein.


                                      -46-
<PAGE>


7.3      Declaratory Judgment Actions.
         ----------------------------


         (a)   THALIDOMIDE DJ ACTIONS Defended by CELGENE. In the event that a
               DJ ACTION relating to the making, using, offering for sale,
               selling or importing of a product that is or contains THALIDOMIDE
               ("THALIDOMIDE DJ ACTION") is brought against CMCC, CELGENE,
               ENTREMED or BIOVENTURE concerning any of the PATENT RIGHTS,
               CELGENE, at its option, shall have the right, within thirty (30)
               days after commencement of such THALIDOMIDE DJ ACTION, to
               intervene, as applicable, and to assume control of the defense of
               such DJ ACTION, at its sole expense. CMCC, ENTREMED and
               BIOVENTURE shall each have the right, at its own expense, to join
               any THALIDOMIDE DJ ACTION defended by CELGENE hereunder, to the
               extent same are INTERESTED PARTIES therein. Except as otherwise
               stated in Section 7.5 of this Agreement, CELGENE shall have the
               sole right, but not the obligation, to grant a sublicense of its
               rights hereunder for future use of any THALIDOMIDE PATENT RIGHTS
               and/or MIXED PATENT THALIDOMIDE CLAIMS in connection with any
               THALIDOMIDE DJ ACTION.

         (b)   NON-THALIDOMIDE DJ ACTIONS Defended by ENTREMED. In the event
               that a DJ ACTION relating to the making, using, offering for
               sale, selling or importing of a product that is or contains an
               analog of THALIDOMIDE ("NON-THALIDOMIDE DJ ACTION") is brought
               against CMCC, CELGENE, ENTREMED or BIOVENTURE concerning any of
               the PATENT RIGHTS, ENTREMED, at its option, shall have the right,
               within thirty (30) days after


                                      -47-
<PAGE>

               commencement of such DJ ACTION, to intervene, as applicable, and
               to assume control of the defense of such NON-THALIDOMIDE DJ
               ACTION, at its sole expense. CMCC, CELGENE and BIOVENTURE shall
               each have the right, at its own expense, to join any
               NON-THALIDOMIDE DJ ACTION defended by ENTREMED hereunder, and to
               the extent same are INTERESTED PARTIES therein. Except as
               otherwise stated in Section 7.5 of this Agreement, ENTREMED shall
               have the sole right, but not the obligation, to grant a
               sublicense of its rights hereunder for future use of any
               THALIDOMIDE PATENT RIGHTS and/or MIXED PATENT THALIDOMIDE CLAIMS
               in connection with any NON-THALIDOMIDE DJ ACTION.

         (c)   Defense of THALIDOMIDE DJ ACTIONS By CMCC. In the event of any
               THALIDOMIDE DJ ACTION in which CELGENE does not assume control of
               the defense, as provided for in Section 7.3(a) hereof, or any
               NON-THALIDOMIDE DJ ACTION in which ENTREMED does not assume
               control of the defense, as provided for in Section 7.3(b) hereof,
               CMCC shall thereafter have the sole right, but not the
               obligation, to intervene and assume control of the defense of
               such THALIDOMIDE DJ ACTION, at its sole expense. CELGENE,
               BIOVENTURE, and/or ENTREMED shall each have the right, at its own
               expense, to join in any such THALIDOMIDE DJ ACTION or
               NON-THALIDOMIDE DJ ACTION defended by CMCC hereunder, to the
               extent same are INTERESTED PARTIES therein.

         (d)   Defense of THALIDOMIDE DJ ACTIONS By BIOVENTURE. If CMCC fails to
               assume defense of any THALIDOMIDE DJ ACTION within thirty (30)
               days of


                                      -48-
<PAGE>

               CMCC's right to do so, pursuant to Section 7.3(c), BIOVENTURE
               shall thereafter have the sole right, but not the obligation, to
               intervene and assume control of the defense of such THALIDOMIDE
               DJ ACTION, at its sole expense. CMCC, CELGENE and/or ENTREMED
               shall each have the right, at its own expense, to join in any
               such THALIDOMIDE DJ ACTION defended by BIOVENTURE hereunder, to
               the extent same are INTERESTED PARTIES therein.

7.4      Allocation of any Damages Award. Any damages recovered in connection
         with any suit or action brought pursuant to Section 7.2, or any DJ
         ACTION defended pursuant to section 7.3 shall be used (a) first to
         reimburse the party primarily responsible for conduct or defense of the
         litigation (i.e., CELGENE if the action is brought pursuant to Section
         7.2(b) or defended pursuant to Section 7.3(a), ENTREMED if the action
         is brought pursuant to Section 7.2(c) or defended pursuant to Section
         7.3(b), CMCC if the action is brought pursuant to Section 7.2(d) or
         defended pursuant to Section 7.3(c), and BIOVENTURE if the action is
         brought pursuant to Section 7.2(e) or defended pursuant to Section
         7.3(d)) (each, as applicable, the "PRIMARY LITIGANT") for the cost of
         such suit or action (including attorney's fees) actually paid by such
         PRIMARY LITIGANT, then (b) to reimburse any INTERESTED PARTY that has,
         pursuant to the terms of Section 7.2 or 7.3, voluntarily joined any
         action brought or defended hereunder, for the cost of such suit or
         action (including attorney's fees) actually paid by such
         voluntarily-joined INTERESTED PARTY, then (c) to reimburse CMCC and
         BIOVENTURE pro rata for any loss of royalties payable hereunder or
         under the NEW ANALOG AGREEMENT, as applicable. In the event that
         CELGENE and/or ENTREMED has, pursuant to the terms


                                      -49-
<PAGE>

         of Section 7.2 or 7.3, voluntarily joined any action brought or
         defended hereunder, then any damages remaining after the distributions
         set forth in subsections (a) through (c) of this Section 7.4 ("RESIDUAL
         DAMAGES") shall first be used to reimburse CELGENE and/or ENTREMED, as
         applicable, for their lost profits. Any remaining RESIDUAL DAMAGES
         shall next be distributed to or among the PRIMARY LITIGANT and any
         INTERESTED PARTIES that have, pursuant to the terms of Section 7.2 or
         7.3, voluntarily joined any action brought or defended hereunder, on a
         basis to be determined in good faith by such INTERESTED PARTIES and the
         PRIMARY LITIGANT based on each such party's respective commercial
         interest in the subject matter of such suit or action.

         7.5 Settlement of Enforcement Actions and DJ ACTIONS. In the event that
         any INTERESTED PARTY has, pursuant to the terms of Section 7.2 or 7.3,
         voluntarily joined any action brought or defended hereunder, then no
         settlement, consent judgment or other voluntary final disposition of
         such suit or action may be entered into without the prior consent of
         all such joined INTERESTED PARTIES, which consent shall not be
         unreasonably withheld or delayed. Except as otherwise stated below in
         this Section 7.5, (i) CELGENE shall have the sole right but not the
         obligation, in accordance with the terms and conditions of this
         Agreement, to sublicense any alleged infringer for future use of any
         THALIDOMIDE PATENT RIGHTS and/or any MIXED PATENT THALIDOMIDE CLAIMS
         with respect to any THALIDOMIDE INFRINGEMENT and (ii) ENTREMED shall
         have the sole right but not the obligation, in accordance with the
         terms and conditions of the NEW ANALOG AGREEMENT, to sublicense any
         alleged infringer for future use of any MIXED PATENT RIGHTS with
         respect to any NON-


                                      -50-
<PAGE>

         THALIDOMIDE INFRINGEMENT. CELGENE and ENTREMED shall each have the
         right to grant such sublicenses in accordance with the terms and
         conditions of this Agreement and the NEW ANALOG AGREEMENT,
         respectively, provided that neither shall grant any such sublicense to
         the detriment of the rights of CMCC or any such joined INTERESTED PARTY
         hereunder or under the NEW ANALOG AGREEMENT. In the event that CELGENE
         and/or ENTREMED elect not to exercise their right to initiate
         litigation against an alleged infringer, as set forth in Sections
         7.2(b) and (c), respectively, or to defend a DJ ACTION, as set forth in
         Sections 7.3(a) and (b), respectively, then the PRIMARY LITIGANT shall
         have the right, but no obligation, to license or sublicense, as
         applicable, any alleged infringer for future use of any THALIDOMIDE
         PATENT RIGHTS and/or any MIXED PATENT RIGHTS, provided, however, that
         (1) the terms and conditions of such license or sublicense shall be
         commercially reasonable and commensurate in scope with the alleged
         infringement, (2) such license or sublicense shall not permit the
         further sublicensing, assignment or transfer of any right or license
         under the PATENT RIGHTS granted therein, and (3) but for a change in
         the grant under the relevant PATENT RIGHTS, as set forth in Section
         2.1, from exclusive to co-exclusive in the region where such
         infringement has occurred and in the field to which such infringement
         relates, neither CELGENE's rights and licenses hereunder, nor
         ENTREMED's rights and licenses under the NEW ANALOG AGREEMENT, shall be
         affected.

7.6      Cooperation. In any suit or action any party may institute or control
         with respect to the enforcement or defense of any of the PATENT RIGHTS
         pursuant to this Agreement, the other parties hereto shall, at the
         request of the PRIMARY LITIGANT, cooperate in all


                                      -51-
<PAGE>

         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 PRIMARY LITIGANT, except as otherwise set forth in
         this Section 7. In any such suit or action that involves any MIXED
         PATENT THALIDOMIDE CLAIMS, all INTERESTED PARTIES shall consult and
         cooperate in good faith to the extent any argument, claim, counterclaim
         or defense advanced by any party to such suit or action actually or
         potentially impacts the rights of any other INTERESTED PARTY including,
         without limitation, with respect to any claim construction and
         infringement issues.

7.7      THIRD PARTY Royalty Reduction. In the event that an infringement action
         is brought by a THIRD PARTY against CELGENE alleging that CELGENE's
         making, using, offering for sale, selling or importing of a PRODUCT
         infringes a THIRD PARTY patent, and results in a judgment or settlement
         requiring royalties to be paid by CELGENE to such THIRD PARTY, the
         royalties owed by CELGENE to CMCC and BIOVENTURE under Section 4 of
         this Agreement shall be reduced pro rata by an amount equal to
         ......... of the royalties owed to such THIRD PARTY, provided that the
         royalties owed to CMCC and BIOVENTURE shall not be reduced under this
         Section 7.7 to less than ......... of NET SALES, nor shall any specific
         royalty payment be reduced under this Section 7.7 by more than.........

                                      -52-
<PAGE>

                   SECTION 8 - REPRESENTATIONS AND WARRANTIES

8.1      Each party hereby represents and warrants that each has the full right
         and authority to enter into this Agreement and that the entry into this
         Agreement does not require the consent of a THIRD PARTY whose consent
         has not been obtained.

8.2      CELGENE hereby represents and warrants to CMCC as follows:

         (a)   Prior to the EFFECTIVE DATE, the CELGENE SUBLICENSE contained all
               of the understandings and agreements between CELGENE and ENTREMED
               with respect to the subject matter thereof, and, prior to the
               EFFECTIVE DATE, the CELGENE SUBLICENSE was in existence in full
               force and effect. There are no written amendments or
               modifications in effect with respect to the CELGENE SUBLICENSE.

         (b)   CELGENE has no actual knowledge of any legal claims asserted by
               any third parties against CELGENE relating to the PRODUCTS, other
               than any product liability claims for which CELGENE has adequate
               insurance.

         (c)   Except as previously disclosed to CMCC, CELGENE has not actually
               received any written notice that it is in violation of any
               governmental law or regulation applicable to the sale of the
               PRODUCTS, and does not believe that there are valid grounds for
               any claim of any such violation.

         (d)   CELGENE confirms that, to its knowledge, all of ENTREMED's
               obligations under Sections 2.4, 2.5, 2.7(c) and 3.1(c), and the
               first sentence of Section 2.6 of the CELGENE SUBLICENSE have been
               fully performed and satisfied prior to the date hereof and that
               ENTREMED has no further obligations under such sections.


                                      -53-
<PAGE>

         (e)   CELGENE agrees that it shall pay directly to CMCC any milestone
               payment that would have been due to ENTREMED, pursuant to Section
               2.7(d) of the CELGENE SUBLICENSE, for the milestone payment
               described therein if such milestone payment was reached after
               December 8, 1998 but before the Effective Date of this Agreement,
               it being understood that if such milestone is reached after the
               Effective Date hereof, such milestone shall be payable to CMCC
               pursuant to Section 4.5 hereof.

         (f)   No right of off-set pursuant to Section 7.3(g) of the CELGENE
               SUBLICENSE has been asserted by CELGENE under the CELGENE
               SUBLICENSE .



                    SECTION 9 - INDEMNIFICATION AND INSURANCE

9.1      By CELGENE. CELGENE will defend, indemnify and hold harmless each of
         CMCC, BIOVENTURE, their successors and AFFILIATES and their employees,
         agents, officers, trustees, shareholders and directors and each of them
         (the "Indemnified Parties") from and against any and all THIRD PARTY
         claims, causes of action and costs (including reasonable attorney's
         fees) of any nature made or lawsuits or other proceedings filed or
         otherwise instituted against the applicable Indemnified Parties in
         connection with any claims, suits or judgments arising out of any
         theory of product liability concerning the development, testing,
         manufacture, sale or use of any PRODUCT by CELGENE, its AFFILIATES or
         its SUBLICENSEES.

         (a)   CELGENE's indemnification under this Section 9.1 shall not apply
               to any liability, damage, loss or expense to the extent that it
               is directly attributable to the


                                      -54-
<PAGE>

               negligent activity, reckless misconduct or intentional misconduct
               of any Indemnified Party.

         (b)   Commencing not later than the date of FIRST COMMERCIAL SALE of a
               PRODUCT, CELGENE shall obtain and carry in full force and effect
               product liability insurance against any claims, judgments,
               liabilities and expenses for which it is obligated to indemnify
               CMCC and others to the extent required under Section 9.1 of this
               Agreement, in such amounts and with such deductibles as are
               customary at the time for companies engaged in a similar
               business, and shall provide CMCC and BIOVENTURE with written
               evidence of such insurance upon request.

9.2      Conditions to Indemnification. CELGENE's obligations under this Section
         9 shall apply only if the Indemnified Parties promptly notify CELGENE
         of any loss, claim, damage, liability or action in respect of which the
         Indemnified Parties intend to claim such indemnification. CELGENE shall
         assume the defense thereof with counsel mutually satisfactory to the
         Indemnified Parties whether or not such claim is rightfully brought.
         Each Indemnified Party shall have the right to retain its own counsel,
         at its own expense, provided that CELGENE shall reimburse such
         Indemnified Party for such expense if representation of such
         Indemnified Party by the counsel retained by CELGENE would be
         inappropriate due to actual or potential differing interests between
         such Indemnified Party and any other person represented by such counsel
         in such proceedings. The failure to deliver notice to CELGENE within a
         reasonable time after the commencement of any such action, only if
         prejudicial to its ability to defend such action, shall relieve CELGENE
         of any liability to any Indemnified Party under this Section 9, but the



                                      -55-
<PAGE>

         omission so to deliver notice to CELGENE will not relieve it of any
         liability that it may have to any Indemnified Party otherwise than
         under this Section 9. Each Indemnified Party under this Section 9 shall
         cooperate fully with CELGENE and its legal representatives in the
         investigations of any action, claim or liability covered by this
         indemnification.



                          SECTION 10 - EXPORT CONTROLS

10.1     It is understood that CMCC is subject to United States laws and
         regulations controlling the export of technical data, computer
         software, laboratory prototypes and other commodities (including the
         Arms Export Control Act, as amended and the Export Administration Act
         of 1979) and that its obligations hereunder are contingent on
         compliance with applicable United States export laws and regulations.
         The transfer of certain technical data and commodities may require a
         license from the cognizant agency of the United States Government
         and/or written assurances by CELGENE that CELGENE shall not export data
         or commodities to certain foreign countries without prior written
         approval of such agency. CMCC neither represents that a license shall
         not be required nor that, if required, it shall be issued.

                          SECTION 11 - NON-USE OF NAMES

11.1     No party hereunder shall use the names of any other party hereunder,
         nor of any of its employees, nor any adaptation thereof, in any
         advertising, promotional or sales literature without prior written
         consent obtained from the party to be named, except that


                                      -56-
<PAGE>
         CELGENE and CMCC may state that CELGENE is licensed by CMCC under the
         PATENT RIGHTS in the FIELD.



                            SECTION 12 - ARBITRATION

12.1     Any and all claims, disputes or controversies arising under, out of, or
         in connection with the this Agreement, which have not been resolved by
         good faith negotiations between the parties, shall be resolved by final
         and binding arbitration in Boston, Massachusetts, under patent
         arbitration rules of the American Arbitration Association then
         obtaining. The arbitrators shall have no power to add to, subtract from
         or modify any of the terms or conditions of this Agreement. Any award
         rendered in such arbitration may be enforced by any party in either the
         courts of the Commonwealth of Massachusetts or in the United States
         District Court for the District of Massachusetts, to whose jurisdiction
         for such purposes each of CMCC, CELGENE, BIOVENTURE and ENTREMED hereby
         irrevocably consents and submits.

12.2.    Notwithstanding the foregoing, nothing in this Section 12 shall be
         construed (a) to waive any rights or timely performance of any
         obligations existing under this Agreement or (b) to apply to the
         provisions of Section 7.2 (Infringement Actions) (other than the fourth
         sentence of Section 7.3(a)) or Section 7.4 (Declaratory Judgment
         Actions).


                                      -57-
<PAGE>

                     SECTION 13 - ASSIGNMENT AND SUCCESSORS

13.1     By Any Party. This Agreement shall not be assignable by CELGENE, CMCC,
         ENTREMED or BIOVENTURE without the prior written consent of the other
         parties to this Agreement, except that (a) CELGENE, CMCC, ENTREMED
         and/or BIOVENTURE may assign this Agreement to an AFFILIATE, successor
         in interest or transferee of all or substantially all of the portion of
         the business to which this Agreement relates without the consent of any
         other party; and (b) CMCC may assign its right, title and interest to
         certain payments due to CMCC pursuant to Section 4 of this Agreement to
         the CMCC ROYALTY PURCHASER(S) provided that such CMCC ROYALTY PURCHASER
         first agrees in writing to be bound by the terms and conditions of
         Section 5 hereof as they apply to CMCC. Notwithstanding the foregoing,
         nothing contained herein shall prevent CMCC, the CMCC ROYALTY PURCHASER
         or BIOVENTURE from assigning, pledging or otherwise encumbering any of
         their respective rights to receive payments hereunder (but not any
         other rights or any obligations hereunder) in connection with any
         financing of CMCC, the CMCC ROYALTY PURCHASERS or BIOVENTURE, as
         applicable, by a financial institution regularly engaged in the
         business of providing financing. In the event that CMCC assigns such
         rights to the CMCC ROYALTY PURCHASER(s), CMCC shall be solely
         responsible for delivery to and distribution among any CMCC ROYALTY
         PURCHASERS of any payments so assigned. CELGENE shall not have any
         liability with respect to any aspect of the delivery to or distribution
         among any CMCC ROYALTY PURCHASER(S) of any payments due to CMCC
         hereunder, and delivery to CMCC, in accordance with the terms and
         conditions of this Agreement, of any payments due hereunder by CELGENE
         to CMCC shall satisfy in


                                      -58-
<PAGE>
         full any obligations CELGENE may have to CMCC and/or the CMCC ROYALTY
         PURCHASERS with respect thereto. Each CMCC ROYALTY PURCHASER shall be
         able to exercise certain of the rights of CMCC under Section 4 of this
         Agreement to the extent provided in the agreement between CMCC and such
         CMCC ROYALTY PURCHASER, and shall be considered an assignee of such
         rights of CMCC for such purposes, provided that, cumulatively, CMCC and
         any CMCC ROYALTY PURCHASERS may conduct no more than one (1) inspection
         pursuant to Section 4.7 hereof in any consecutive twelve (12) month
         period. Any attempted assignment in violation of this Section 13.1
         shall be null, void and of no effect.

13.2     Satisfaction of Obligations. Performance or satisfaction of any
         obligations of CELGENE under this Agreement by any of its AFFILIATES or
         SUBLICENSEES shall be deemed performance or satisfaction of such
         obligation by CELGENE.

13.3     Binding Effect. This agreement shall be binding upon and inure to the
         benefit of said successors in interest and permitted assignees to the
         parties. 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 and such
         Assignment shall not relieve the Assignor of any of its obligations
         under this Agreement.



                           SECTION 14 - FORCE MAJEURE

14.1     None of the parties shall be liable to any other party for damages or
         loss occasioned by failure of performance by the defaulting party if
         the failure is occasioned by war, fire,



                                      -59-
<PAGE>
         explosion, flood, strike or lockout, embargo, or any similar cause
         beyond the control of the defaulting party, provided that the party
         claiming this exception has exerted all reasonable efforts to avoid or
         remedy such event and provided such event does not extend for more than
         six (6) months.



                            SECTION 15 - TERMINATION

15.1     Term. Unless earlier terminated as hereinafter provided, this Agreement
         shall remain in full force and effect until CELGENE's obligations to
         pay royalties or other compensation under Section 4 of this Agreement,
         either directly or pursuant to a sublicense, terminate.

15.2     By Reason Of FDA Action. If the FDA withdraws or recalls THALIDOMIDE
         from the market permanently, or in any other way permanently revokes or
         terminates CELGENE's regulatory approval to market and sell THALIDOMIDE
         and/or PRODUCTS, CELGENE shall promptly notify CMCC and BIOVENTURE in
         writing, and this Agreement and all of CELGENE's, CMCC's, BIOVENTURE's
         and ENTREMED's rights and obligations hereunder shall terminate with
         respect to THALIDOMIDE and/or such PRODUCTS, as applicable, upon
         receipt by CMCC and BIOVENTURE of such notice.

15.3     Termination Of Royalty Obligations. Upon termination of CELGENE's
         obligation to pay royalties and other compensation hereunder with
         respect to a specific country and specific PRODUCT as to which
         CELGENE's license is then in effect, the license granted to CELGENE
         with respect to such country and such PRODUCT pursuant to Section 2 of
         this Agreement shall be deemed to be fully paid and CELGENE shall
         thereafter have a


                                      -60-
<PAGE>

         royalty free, exclusive right to use the PATENT RIGHTS to make, have
         made, use, offer to sell, sell and import such PRODUCT in such country.

15.4     Breach.
         ------

         (a)   By Either CMCC or CELGENE. This Agreement shall be terminable by
               CELGENE or CMCC, respectively, upon the material breach or
               default of either CMCC or CELGENE, as applicable. In the event of
               a material breach or default by CMCC or CELGENE ("Defaulting
               Party"), the other party ("Non-Defaulting Party") shall give the
               Defaulting Party written notice of the default. The Defaulting
               Party will then have sixty (60) days to cure the breach. If cure
               has not been effected within said sixty (60) days, the
               Non-Defaulting Party shall have the right to terminate this
               Agreement. Notwithstanding anything in this Agreement to the
               contrary, CMCC agrees not to terminate this Agreement, for any
               reason, including pursuant to Sections 3.1(b), 3.2(b), 3.3(b),
               3.4 and 15.4(b), without the prior written consent of BIOVENTURE,
               provided that (i) CMCC shall not be required to obtain the prior
               consent of BIOVENTURE prior to any termination based upon (1) a
               material breach of payment provisions of this Agreement or (2) a
               material breach of this Agreement the action or circumstances of
               which are, or may reasonably be expected to be, deleterious to
               CMCC's reputation and good standing within the healthcare
               community and (ii) CMCC shall terminate this Agreement if
               BIOVENTURE so requests in writing if the material breach
               entitling CMCC to terminate falls within Section 15.4(b)(i) of
               this Agreement.




                                      -61-
<PAGE>

(b)      By CELGENE.
         -----------

         (i)   Payments. If and only if CELGENE materially breaches this
               Agreement by failure to pay royalties and/or sublicensing or
               milestone payments due under Section 4 of this Agreement, and
               fails to cure such material breach within sixty (60) days of
               receiving written notice thereof pursuant to Section 15.4(a) of
               this Agreement, then CELGENE's rights under this Agreement shall
               terminate, and CELGENE shall grant to CMCC, to the extent not
               prohibited by the United States Government or by prior
               contractual obligations to any THIRD PARTY:

         (a)   an exclusive, worldwide, royalty-free license, with the right to
               sublicense, under CELGENE DEVELOPED INTELLECTUAL PROPERTY; and

         (b)   a non-exclusive, worldwide, irrevocable, royalty-free license,
               with the right to sublicense, under (1) that certain Agreement by
               and between the Division of Cancer Treatment at the National
               Cancer Institute ("NCI") and ENTREMED, dated November 16, 1994,
               and executed on behalf of ENTREMED on November 23, 1994, and on
               behalf of NCI on November 18, 1994, as assigned by ENTREMED to
               CELGENE ("NCI AGREEMENT"), and (2) any Orphan Drug Status and
               Investigational New Drug applications filed by ENTREMED as of
               December 9, 1998, as set forth in Appendix C of the CELGENE
               SUBLICENSE, to the extent same were assigned or licensed to
               CELGENE pursuant to Section 2.4 of the CELGENE SUBLICENSE
               ("REGULATORY APPLICATIONS");


                                      -62-
<PAGE>
               in the case of both (a) and (b), to make, have made, use, lease,
               offer to sell, sell, and import PRODUCTS in the TERRITORY.

         (ii)  Diligence. If and only if (i) CMCC exercises its right and option
               to terminate the license granted to CELGENE in the entire
               TERRITORY, pursuant to Section 3.1(b) of this Agreement, or (ii)
               CMCC exercises its right and option to terminate the license
               granted to CELGENE in Europe, Canada, or the PACIFIC RIM,
               pursuant to Section 3.2(b) of this Agreement, or (iii) CMCC
               exercises its right and option to terminate the license granted
               to CELGENE for use in animals, pursuant to Section 3.3(b) of this
               Agreement or (iv) CMCC exercises its right and option to
               terminate the license granted to CELGENE for PRODUCTS for
               ophthalmologic use in the United States pursuant to Section 3.4
               of this Agreement, then, only in the region in which such
               termination has occurred, and only to the extent of such
               termination as specified in Section 3.1(b), 3.2(b), 3.3(b) and/or
               3.4, as applicable:

                    a)   CELGENE's rights under this Agreement shall terminate;
                         and

                    b)   CELGENE shall grant to CMCC, to the extent not
                         prohibited by the United States Government or by prior
                         contractual obligations to any THIRD PARTY, solely to
                         the extent necessary to permit CMCC to exercise its
                         rights under such terminated PATENT RIGHTS in the
                         relevant region or territory and solely to the extent
                         CELGENE's



                                      -63-
<PAGE>
                         rights thereunder have terminated, pursuant to Section
                         3: (1) a non-exclusive, worldwide, royalty-free
                         license, with the right to sublicense, under the NCI
                         AGREEMENT and any REGULATORY APPLICATIONS, to make,
                         have made, use, lease, offer to sell, sell, and import
                         PRODUCTS in the TERRITORY; and (2) immunity from suit
                         for any causes of action CELGENE may have arising out
                         of or in connection with any CELGENE DEVELOPED
                         INTELLECTUAL PROPERTY that would otherwise be infringed
                         by the making, having made, using, leasing, offering
                         for sale, selling, or importing of any PRODUCTS in such
                         region or TERRITORY. The term of the rights granted to
                         CMCC under this Section 15.4(b)(ii)(b) shall continue
                         for so long as any PATENT RIGHT exists, within the
                         relevant region or TERRITORY, that contains an ISSUED
                         VALID CLAIM covering a PRODUCT (only for animal use in
                         the case of termination pursuant to Section 3.3(b), and
                         only for ophthalmologic use, in the case of termination
                         pursuant to Section 3.4), provided that if any patent
                         applications within the PATENT RIGHTS are pending, in
                         the relevant region or TERRITORY, at the end of such
                         term, and any ISSUED VALID CLAIM covering a PRODUCT
                         (only for animal use in the case of termination



                                      -64-
<PAGE>

                         pursuant to Section 3.3(b), and only for ophthalmologic
                         use, in the case of termination pursuant to Section
                         3.4) subsequently issues from such PATENT RIGHTS, then
                         CMCC's rights under this Section 15.4(b)(ii)(b) shall
                         recommence, in the relevant region or TERRITORY, on the
                         issuance date of such ISSUED VALID CLAIMS and continue
                         until the date of expiration or termination of the last
                         to expire of such ISSUED VALID CLAIMS in such region or
                         TERRITORY. CMCC shall have the right to sublicense the
                         rights granted to it under this Section 15.4(b)(ii)(b),
                         with CELGENE's prior written consent, as set forth
                         herein, only to its AFFILIATES and other THIRD PARTIES
                         in connection with and commensurate in scope with a
                         bona fide license of CMCC's rights under the PATENT
                         RIGHTS. Prior to granting any such sublicense, CMCC
                         shall notify CELGENE in writing of such AFFILIATE or
                         THIRD PARTY and CELGENE shall have the right to consent
                         to such AFFILIATE or THIRD PARTY (which consent shall
                         not be unreasonably withheld or delayed) on the basis
                         of such AFFILIATE or THIRD PARTY's safety record and
                         capacity to satisfy all applicable health and safety
                         laws, rules and regulations

                                      -65-
<PAGE>

                         governing the manufacture, use, offer for sale, sale
                         and/or importation of PRODUCTS.

         (c)   Termination under this Section 15.4 will be effective upon the
               date specified in the written notice. All termination rights
               shall be in addition to and not in substitution for any other
               remedies that may be available to the Non-Defaulting Party.
               Termination pursuant to this Section 15.4 shall not relieve the
               Defaulting Party from liability and damages to the Non-Defaulting
               Party for default. Waiver by either party of a single default or
               a succession of defaults shall not deprive such party of any
               right to terminate or convert this Agreement arising by reason of
               any subsequent default.

         (d)   Upon any termination of this Agreement in its entirety, or with
               respect to any PATENT RIGHTS pursuant to Section 15.4(b)(ii), for
               any reason, whether by CELGENE or by CMCC, each of CMCC and
               CELGENE agrees not to enter into any other agreement, arrangement
               or understanding with each other granting a license to CELGENE
               under any PATENT RIGHTS in the FIELD without providing for the
               payment to BIOVENTURE of.........of royalties and other
               consideration payable to CMCC under such other agreement,
               arrangement or understanding. In addition, upon any termination
               of this Agreement in its entirety or with respect to any PATENT
               RIGHTS pursuant to Section 15.4(b)(ii), for any reason, CMCC
               agrees not to enter into any other agreement, arrangement or
               understanding with a THIRD PARTY granting a license under PATENT
               RIGHTS in the FIELD without providing for the payment to
               BIOVENTURE of.........of


                                      -66-
<PAGE>
               royalties and other consideration payable to CMCC under such
               other agreement, arrangement or understanding.

15.5     Insolvency. CMCC may terminate this Agreement upon receipt of notice
         that CELGENE has become insolvent or has suspended business in all
         material respects hereof, or has consented to an involuntary petition
         purporting to be pursuant to any reorganization or insolvency law of
         any jurisdiction, or has made an assignment for the benefit of
         creditors or has applied for or consented to the appointment of a
         receiver or trustee for a substantial part of its property, by giving
         written notice to all other parties, and termination of this Agreement
         will be effective upon receipt of such notice.

15.6     Work-In-Progress. Upon termination of this Agreement, CELGENE shall be
         entitled, but shall not be obligated, to finish any work-in-progress at
         the time of termination and sell the same as well as all completed
         inventory of PRODUCTS which remains on hand as of the date of the
         termination, so long as CELGENE pays to CMCC and BIOVENTURE the
         royalties applicable to said subsequent sales in accordance with the
         same terms and conditions as set forth in this Agreement.

15.7     Survival. The obligations of Sections 2.2.3, 2.2.4, 2.2.5, 2.4, 2.5,
         4.7, 5, 9, 11, 12 and 13.3, as well as Sections 15.4(b)(i),
         15(b)(ii)(b), 15.4(d), 15.5, 15.6, 15.7, 15.8, 16.2, 16.3, 16.4, 16.5,
         16.6, 16.7 and 16.9 shall survive any termination of this Agreement.
         Any payment obligations accrued and owing as of the date of termination
         or expiration of this Agreement shall survive such termination or
         expiration. The rights and obligations of CMCC and ENTREMED relating to
         MIXED PATENT RIGHTS, as set forth in Section 7 of this Agreement, shall
         survive termination or expiration hereof pursuant to the terms and
         conditions of the NEW ANALOG AGREEMENT.



                                      -67-
<PAGE>
15.8     Reversion of Rights. Upon termination of this Agreement or of the
         rights and licenses granted to CELGENE in any country of the TERRITORY,
         CELGENE agrees not to use the PATENT RIGHTS in any country other than
         those countries in which CELGENE retains a license under this
         Agreement. In addition, all rights to the PATENT RIGHTS in any such
         country shall revert to CMCC and, subject to Section 15.4(d), may be
         used by CMCC without restriction in any country other than those
         countries in which CELGENE retains a license under this Agreement.

15.9     Termination or Expiration of NEW ANALOG AGREEMENT. In the event that
         the NEW ANALOG AGREEMENT terminates or expires during the Term of this
         Agreement, EntreMed's rights and obligations hereunder shall, as of the
         effective date of such termination or expiration, immediately cease,
         except for any rights and obligations which survive termination or
         expiration of this Agreement, pursuant to Section 15.7 hereof.



                         SECTION 16 - GENERAL PROVISIONS

16.1     Relationship of Parties. The relationship between CMCC, CELGENE,
         BIOVENTURE and ENTREMED is that of independent contractors. CMCC,
         CELGENE, BIOVENTURE and ENTREMED are not joint venturers, partners,
         principal and agent, master and servant, employer or employee, and have
         no relationship other than as independent contracting parties. None of
         the parties shall have any power to bind or obligate any of the other
         parties in any manner.



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<PAGE>
16.2     Entire Understanding. This Agreement, the NEW ANALOG AGREEMENT and the
         Consents sets forth the entire agreement and understanding among the
         parties as to the subject matter thereof and supersede all prior
         agreements in this respect, including without limitation the ENTREMED
         LICENSE and the CELGENE SUBLICENSE, both of which shall automatically
         and without any further action of the parties terminate on the
         EFFECTIVE DATE hereof. Notwithstanding anything to the contrary set
         forth herein, ENTREMED shall be and remain solely liable and
         responsible for the past breach of performance of any duties,
         obligations and covenants under the ENTREMED LICENSE, and the
         performance of any duties, obligations and covenants that survive
         termination of the ENTREMED LICENSE.

16.3     Governing Law. This Agreement shall be construed and enforced in
         accordance with the laws of the Commonwealth of Massachusetts, U.S.A.
         without reference to its choice of law principles. Each party agrees
         that the state and federal courts located in the Commonwealth of
         Massachusetts, including any courts of appeal therefrom, shall have
         exclusive jurisdiction over any dispute arising under this Agreement,
         and the parties hereby consent to personal jurisdiction of such courts
         in any such action.

16.4     Headings. The headings in this Agreement have been inserted for the
         convenience of reference only and are not intended to limit or expand
         on the meaning of the language contained in the particular or section
         or paragraph.

16.5     Amendments. Any provisions of this Agreement may be amended, modified
         or waived, if and only if, such amendment, modification or waiver is in
         writing and signed by all parties to this Agreement, including, without
         limitation, BIOVENTURE, or, in the case of a waiver, by the party
         against whom the waiver is to be effective. The consent of



                                      -69-
<PAGE>
         ENTREMED shall not be required with respect to any amendment or
         modification of this Agreement, except any such amendment or
         modification to Section 7.

16.6     No Waiver. Any delay in enforcing a party's rights under this Agreement
         or any waiver as to a particular default or other matter shall not
         constitute a waiver of a party's right to the future enforcement of its
         rights under this Agreement, excepting only as to an expressed written
         and signed waiver as to a particular matter for a particular period of
         time.

16.7     Severability. The provisions of this Agreement are severable, and in
         the event that any provisions of this Agreement shall be determined to
         be invalid or unenforceable under any controlling body of law, such
         invalidity or unenforceability shall not in any way affect the validity
         or enforceability of the remaining provisions hereof.

16.8     Patent Marking. CELGENE agrees to mark the labels of PRODUCTS with all
         applicable patent numbers in accordance with standard practice in the
         pharmaceutical industry.

16.9     Notices. Any notices given pursuant to this Agreement shall be in
         writing and shall be deemed delivered upon the earlier of (i) when
         received at the address set forth below, or (ii) three (3) business
         days after mailed by certified or registered mail postage prepaid and
         properly addressed, with return receipt requested, or (iii) when sent,
         if sent by facsimile, as confirmed by certified or registered mail.
         Notices shall be delivered to the respective parties as indicated
         below:

                  If to CMCC:          Children's Medical Center Corporation
                                       c/o Children's Hospital Boston
                                       Intellectual Property Office
                                       300 Longwood Avenue
                                       Boston, MA  02115
                                       Attn: Chief Intellectual Property Officer
                                       Fax: (617) 232-7485



                                      -70-
<PAGE>


                  If to CELGENE:       Celgene Corporation
                                       7 Powder Horn Drive
                                       Warren, NJ 07059
                                       Attn: President and COO
                                       Fax: (732) 805-3931


                  If to BIOVENTURE:    Bioventure Investments kft
                                       c/o Royalty Pharma Management
                                       675 Third Avenue, Suite 3000
                                       New York, NY  10017
                                       Attn: Dave Madden
                                             Pablo Legorreta
                                       Fax: (917) 368-0021

                  If to ENTREMED:      EntreMed, Inc.
                                       9640 Medical Center Drive, Suite 200
                                       Rockville, MD  20850
                                       Attn: Thomas P. Russo
                                       Fax: (302) 217-9594

16.10    Original Counterparts. This Agreement may be executed in four separate
         counterparts, each of which shall be deemed to be an original, but
         which together shall constitute one and the same instrument.


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                                      -71-
<PAGE>
IN WITNESS WHEREOF, the parties have executed this Agreement as of the date set
forth above.

                                           CELGENE CORPORATION


                                           By: ______________________________

                                           Name: ____________________________

                                           Title: _____________________________



                                           CHILDREN'S MEDICAL CENTER
                                           CORPORATION


                                           By: ______________________________

                                           Name: ____________________________

                                           Title: _____________________________



                                           BIOVENTURE INVESTMENTS KFT


                                           By: ______________________________

                                           Name: ____________________________

                                           Title: _____________________________


                                           ENTREMED, INC.
                                           (Solely for purposes of Sections
                                           2.2.5, 2.7, 5, 7, 8.1, 12, 13, 15.2,
                                           15.7, 15.9 and 16)

                                           By: ______________________________

                                           Name: ____________________________

                                           Title: _____________________________





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