Document:

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                                                                    EXHIBIT 10.2

                                 EXECUTION COPY

                              TERMINATION AGREEMENT

     This Termination Agreement, dated as of this 19th day of August, 2002 (the
"SIGNING DATE"), is by and between PRAECIS PHARMACEUTICALS INCORPORATED, a
Delaware corporation having its principal place of business at 830 Winter
Street, Waltham, Massachusetts 02451-1420 ("PRAECIS"), and Amgen Inc., a
Delaware corporation with its principal place of business at One Amgen Center
Drive, Thousand Oaks, California 91320-1789 ("AMGEN").

     WHEREAS, PRAECIS and Amgen are parties to an Amended and Restated Binding
Agreement in Principle, effective as of March 8, 1999, as amended (the
"COLLABORATION AGREEMENT"), providing for a collaboration between the parties
for the development and commercialization of certain LHRH Antagonist Compounds;

     WHEREAS, on September 18, 2001, Amgen delivered a notice to PRAECIS
terminating in whole the Collaboration Agreement pursuant to Section 18(b)(ii)
thereof, which termination, in accordance with such Section 18(b)(ii), became
effective on December 17, 2001 (the "TERMINATION DATE");

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     WHEREAS, PRAECIS and Amgen entered into a letter agreement dated September
20, 2001, regarding the transfer from Amgen to PRAECIS effective September 20,
2001 of all obligations, responsibility and control over regulatory and
operational matters with respect to certain clinical studies identified therein
(the "CLINICAL STUDIES LETTER AGREEMENT");

     WHEREAS, PRAECIS and Amgen entered into an Assignment of Development and
Supply Agreement dated January 18, 2002 and attached hereto as Exhibit A (the
"UCB ASSIGNMENT AGREEMENT"), regarding the assignment from Amgen to PRAECIS
effective as of the Termination Date of all of Amgen's rights, interests and
obligations under a Development and Supply Agreement between Amgen and UCB
attached hereto as Exhibit B (the "UCB-AMGEN AGREEMENT");

     WHEREAS, PRAECIS and Amgen wish to confirm the termination of the
Collaboration Agreement and related instruments and documents to the extent
provided herein, and to finally resolve all outstanding issues as to the amounts
of monies the parties may owe each other under the Collaboration Agreement and
as to the continuing rights and obligations of the parties arising out of or
relating to the Collaboration Agreement or the termination thereof.

     NOW THEREFORE, in consideration of the foregoing, and the representations
and agreements set forth herein, PRAECIS and Amgen agree as follows:

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1.   CERTAIN CAPITALIZED TERMS. As used in this Termination Agreement, the
following terms shall have the respective meanings set forth below. Additional
capitalized terms used but not defined herein shall have the respective meanings
for such terms set forth in the Collaboration Agreement.

     (a)  "AFFILIATE" of a party shall mean a Person which controls, is
          controlled by, or is under common control with such party. A Person
          shall be regarded as in "control" of another Person if it owns or
          directly or indirectly controls the voting and disposition of fifty
          percent (50%) or more of the voting stock or other ownership interest
          of the other Person, or if it possesses, directly or indirectly, the
          power to direct or cause the direction of the management and policies
          of the Person or the power to elect or appoint fifty percent (50%) or
          more of the members of the governing body of the Person.

     (b)  "AMGEN CONFIDENTIAL INFORMATION" has the meaning set forth in Section
          11(b) hereof.

     (c)  "AMGEN INVENTORY" has the meaning set forth in Section 3(a) hereof.

     (d)  "API" has the meaning ascribed thereto in the first sentence of
          Section 1.2 of the UCB-Amgen Agreement.

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     (e)  "ASSUMED CLINICAL STUDIES" has the meaning set forth in Section 8(a)
          hereof.

     (f)  "ASSUMED OTHER CONTRACTS" has the meaning set forth in Section 7(b)
          hereof.

     (g)  "CLINICAL STUDIES ASSIGNMENT AGREEMENTS" has the meaning set forth in
          Section 8(b) hereof.

     (h)  "CLINICAL STUDIES LETTER AGREEMENT" has the meaning set forth in the
          Recitals.

     (i)  "CLINICAL STUDIES CONTRACTS" has the meaning set forth in Section 8(b)
          hereof.

     (j)  "COLLABORATION AGREEMENT" has the meaning set forth in the Recitals.

     (k)  "COLLABORATION TRANSACTION DOCUMENTS" has the meaning set forth in
          Section 2 hereof.

     (l)  "DELIVERABLES" has the meaning set forth in Section 4 hereof.

     (m)  "DELIVERY DATE" has the meaning set forth in Section 3(a) hereof.

     (n)  "ENDO IND TRANSFER LETTER" has the meaning set forth in Section 5
          hereof.

     (o)  "LOSSES" has the meaning set forth in Section 12(a) hereof.

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     (p)  "OTHER CONTRACTS" has the meaning set forth in Section 7(b) hereof.

     (q)  "PERSON" shall mean any natural person, corporation, business trust,
          association, partnership, limited liability company, joint venture,
          governmental entity or any other entity.

     (r)  "PRAECIS CONFIDENTIAL INFORMATION" has the meaning set forth in
          Section 11(a) hereof.

     (s)  "SALSBURY INVENTORY" has the meaning set forth in Section 3(a) hereof.

     (t)  "SIGNING DATE" has the meaning set forth in the Recitals.

     (u)  "SURVIVING AGREEMENTS" has the meaning set forth in Section 2 hereof.

     (v)  "TERMINATION DATE" has the meaning set forth in the Recitals.

     (w)  "UCB" means UCB S.A., having a registered office at Allee de la
          Recherche 60, B-1070 Brussels, Belgium.

     (x)  "UCB-AMGEN AGREEMENT" has the meaning set forth in the Recitals.

     (y)  "UCB ASSIGNMENT AGREEMENT" has the meaning set forth in the Recitals.

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2.   TERMINATION OF COLLABORATION AGREEMENT AND RELATED AGREEMENTS; REVERSION OF
RIGHTS AND OBLIGATIONS TO PRAECIS. The parties hereby agree, acknowledge and
confirm that, except as expressly set forth in this Section 2 below with respect
to the Surviving Agreements, effective as of the Termination Date, the
Collaboration Agreement and all agreements or instruments between PRAECIS and
Amgen (or by PRAECIS or Amgen for the benefit of the other) entered into
pursuant to the Collaboration Agreement or in connection therewith prior to the
Termination Date (collectively, the "COLLABORATION TRANSACTION DOCUMENTS"), were
terminated in their entirety, including all licenses, sublicenses, rights and
obligations thereunder (including any rights and obligations which according to
their terms or otherwise were intended to survive termination or expiration of
the relevant agreement). Without limitation of the foregoing, and for the
avoidance of doubt, (a) Amgen acknowledges and agrees, on behalf of itself and
its Affiliates that, effective as of the Termination Date, any and all rights of
Amgen with respect to the Collaboration Technology or Licensed Products reverted
to PRAECIS, and neither Amgen nor any of its Affiliates has or shall have any
rights or claims of any nature whatsoever (i) to, in, arising out of, or with
respect to, the Collaboration Technology or any Licensed Products, or the
development, commercialization, sale, use, assignment or transfer thereof or
(ii) under or arising out of the Collaboration Agreement or any other
Collaboration Transaction Documents, and (b) PRAECIS acknowledges and agrees, on
behalf of itself and its Affiliates that, effective as of the Termination Date,
any and all obligations of Amgen or any of its Affiliates with respect to (i)
the Collaboration

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Agreement and all other Collaboration Transaction Documents or (ii) the
Collaboration Technology or Licensed Products, terminated, and neither PRAECIS
nor any of its Affiliates has or shall have any rights or claims of any nature
whatsoever against Amgen or its Affiliates with respect to the Collaboration
Agreement, the other Collaboration Transaction Documents, the Collaboration
Technology or any Licensed Products, or the development, commercialization,
sale, use, assignment or transfer thereof. Without limiting the generality of
the foregoing, PRAECIS acknowledges and agrees that Amgen shall have no
obligation to extend to PRAECIS all or any part of the line of credit
contemplated by Section 9(e) of the Collaboration Agreement. Notwithstanding the
foregoing, nothing contained in this Section 2 shall terminate or alter or
impair in any manner the respective rights and obligations of PRAECIS and Amgen
under the Clinical Studies Letter Agreement, the Clinical Studies Assignment
Agreements, the Endo IND Transfer Letter or the UCB Assignment Agreement
(collectively, the "SURVIVING AGREEMENTS"), which shall continue in full force
and effect in accordance with their respective terms. For the avoidance of
doubt, the parties acknowledge that the term "SURVIVING AGREEMENTS" shall not
include any agreements or other documents which are the subject of or are
referred to in the Surviving Agreements (for example, the UCB Assignment
Agreement shall not include the UCB-Amgen Agreement).

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3.   INVENTORY.

     (a)  Promptly after the Signing Date, PRAECIS will make, and Amgen will
          cooperate with PRAECIS' reasonable requests in making, appropriate
          arrangements for the shipment from Amgen to PRAECIS at PRAECIS'
          principal place of business identified in the first paragraph hereof
          or such other location or locations as may be determined by PRAECIS,
          of all quantities of inventory of Licensed Products, in whatever form,
          listed on Exhibit C hereto (collectively, "AMGEN INVENTORY"), all of
          which quantities of inventory Amgen hereby represents and warrants to
          PRAECIS are (to the extent not previously delivered to PRAECIS as
          indicated on such Exhibit C) located at Amgen's premises in Thousand
          Oaks, California (the "AMGEN PREMISES"). Subject to PRAECIS making
          appropriate shipping arrangements as provided in the first sentence of
          this Section 3(a), Amgen will effect the delivery of Amgen Inventory
          (to the extent not previously delivered to PRAECIS as indicated on
          Exhibit C hereto) to PRAECIS' designated shipping company at the Amgen
          Premises (the "DELIVERY") within ten (10) business days after the
          Signing Date. Upon Delivery, all Amgen Inventory shall be free and
          clear of all liens, claims or encumbrances of any kind or nature
          arising from any action of Amgen. Risk of loss for all Amgen Inventory
          shall rest with Amgen until Delivery, whereupon it shall transfer to
          PRAECIS.

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          Amgen represents and warrants to PRAECIS that the Amgen Inventory has
          been, and until Delivery will be, maintained under cGMP conditions,
          which representation and warranty shall survive Delivery. PRAECIS
          shall be solely responsible for maintaining the Amgen Inventory in
          compliance with cGMP conditions after Delivery. The date on which
          Delivery is completed as contemplated by this Section 3(a) is referred
          to as the "DELIVERY DATE." The parties agree and acknowledge that the
          Amgen Inventory shall not include inventory of Licensed Products, in
          whatever form, in the possession or control of Salsbury Chemicals,
          Inc. as of the Signing Date (the "SALSBURY INVENTORY"), or any other
          inventory not specifically listed on Exhibit C hereto.

     (b)  Amgen hereby disclaims any right, title or interest in or to the
          Salsbury Inventory, and PRAECIS acknowledges that Salsbury Chemicals,
          Inc. shall be solely responsible for delivering the Salsbury Inventory
          in accordance with PRAECIS' instructions.

4.   DELIVERABLES. As promptly as practicable after the Signing Date, and in any
event not later than September 17, 2002, Amgen will deliver or cause to be
delivered to PRAECIS, at its principal place of business identified in the first
paragraph hereof or such other location or locations as may be designated by
PRAECIS to Amgen, all of the documents, clinical data, equipment and other
materials listed on Exhibit D hereto (collectively, "DELIVERABLES") to the
extent not

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previously delivered. Amgen agrees to execute any and all additional instruments
of assignment or other documentation, and take any other actions as reasonably
necessary to vest in PRAECIS valid title to all Deliverables, free and clear of
all liens, claims or encumbrances of any kind or nature arising from any action
of Amgen, at PRAECIS' sole cost and expense. Risk of loss for any Deliverable
shall rest with Amgen until it leaves the Amgen Premises, whereupon it shall
transfer to PRAECIS.

5.   REGULATORY, TRADEMARK AND PATENT ASSIGNMENTS. Amgen hereby assigns to
PRAECIS Amgen's entire right, title and interest in and to (i) all regulatory
filings, regulatory approvals, and other governmental authorizations, permits or
approvals, in each case to the extent relating to Licensed Products, including
without limitation, those listed on Exhibit E hereto, and (ii) (A) all
trademarks (including any registrations and applications for registration
thereof and all goodwill attaching thereto) relating to Licensed Products,
including without limitation the trademark Plenaxis(TM) and all registration
applications with respect thereto, all of which are listed on Exhibit F hereto,
and (B) the patent application(s) listed on Exhibit F hereto, including all
foreign counterparts thereto and continuations, continuations-in-part, and
divisionals thereof, and all patents issuing from any of the foregoing. Amgen
represents, warrants and covenants that the items, property and rights being
assigned pursuant to this Section 5 are free and clear of all liens, claims or
encumbrances of any kind or nature arising from any action of Amgen. Amgen
agrees to execute, and to file or record with or provide proper notice to, or
(if appropriate) enable PRAECIS to file or record

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with or provide proper notice to, the appropriate governmental offices, any and
all additional instruments of assignment or other documentation (including
without limitation separate instruments of trademark and patent assignment), as
may be reasonably requested by PRAECIS to assure PRAECIS of the benefit of the
assignments provided for in this Section 5, at PRAECIS' sole cost and expense.
The parties acknowledge and agree that, as contemplated by this Section 5, (i)
prior to the Signing Date, Amgen has executed and delivered to (A) the FDA a
letter, a copy of which is attached hereto as Exhibit G, transferring ownership
of the Abarelix U.S. Endometriosis IND (No. 56,259) to PRAECIS (the "ENDO IND
TRANSFER LETTER") and (B) PRAECIS trademark assignments for the applications for
trademark registration and the trademarks (including any registrations and all
goodwill attaching to the foregoing) listed on Exhibit F hereto (other than an
assignment of trademark application number 132426 listed under section 5 of part
A of Exhibit F hereto (the "Egypt Trademark Assignment")) in the form attached
hereto as Exhibit H, (ii) on or before September 17, 2002, Amgen will execute
and deliver to PRAECIS the Egypt Trademark Assignment in the appropriate form
prescribed by Egyptian trademark authorities, and (iii) Amgen has previously
executed and delivered to PRAECIS an assignment of the patent application listed
on Exhibit F in the form attached hereto as Exhibit I. PRAECIS shall have sole
responsibility with respect to, and bear all expenses arising after the
Termination Date in connection with, the prosecution, maintenance and defense of
such trademark applications and patent application(s).

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6.   CASH PAYMENT. On the Delivery Date, PRAECIS shall pay Amgen, by wire
transfer of funds to the account of Amgen designated on Exhibit J attached
hereto, the non-refundable sum of Thirteen Million Dollars ($13,000,000), which
shall constitute full and complete satisfaction of all amounts payable by
PRAECIS to Amgen under or in connection with the Collaboration Agreement or the
termination thereof and all amounts payable by PRAECIS to Amgen in consideration
of Amgen's delivery of Inventory pursuant to Section 3 hereof.

7.   ASSIGNMENT OF CERTAIN THIRD PARTY CONTRACTS.

     (a)  UCB-AMGEN AGREEMENT. In accordance with Section 9.3 of the UCB-Amgen
          Agreement, pursuant to the UCB Assignment Agreement, Amgen has
          assigned to PRAECIS and PRAECIS has accepted the UCB-Amgen Agreement
          in its entirety, and PRAECIS has assumed all of Amgen's liabilities
          and obligations thereunder effective as of the Termination Date
          (without limitation, however, of Amgen's obligations under Section
          12(a) hereof).

     (b)  OTHER CONTRACTS. Amgen hereby assigns to PRAECIS, effective as of the
          Termination Date, all of Amgen's rights and obligations under the
          agreements listed on Exhibit K hereto (the "OTHER CONTRACTS"),
          subject, in the case of each Other Contract, to any required consent
          to such assignment of such Other Contract. Amgen and PRAECIS shall
          cooperate in good faith to obtain any

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          necessary consent to such assignment (and upon any such necessary
          consent being obtained, such assignment shall be deemed to have been
          effected hereby), provided that neither PRAECIS nor Amgen shall be
          required to pay any consideration to obtain such consent. PRAECIS
          shall, and hereby does effective as of the Termination Date, assume
          Amgen's obligations under each Other Contract to the extent Amgen's
          rights under such Other Contract have been validly assigned to PRAECIS
          as contemplated by this Section 7(b) (without limitation, however, of
          Amgen's obligations under Section 12(a) hereof). Such Other Contracts
          which have been validly assigned to and assumed by PRAECIS in
          accordance with this Section 7(b) are referred to as the "ASSUMED
          OTHER CONTRACTS."

8.   ASSUMED CLINICAL STUDIES.

     (a)  ASSUMPTION BY PRAECIS OF CLINICAL STUDIES. Amgen and PRAECIS
          acknowledge and agree that, pursuant to the Clinical Studies Letter
          Agreement, effective as of, and from and after, September 20, 2001,
          PRAECIS has had and shall have all obligations, responsibility and
          control over regulatory and operational matters with respect to the
          clinical studies referred to below (the "ASSUMED CLINICAL STUDIES"),
          without limitation, however, of Amgen's obligations under Section
          12(a) hereof:

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          (i)    ENDOMETRIOSIS STUDY
                 A Multi-Center, Randomized, Controlled Clinical Trial Comparing
                 the Safety and Efficacy of Abarelix-Depot to Lupron Depot
                 3.75 mg in Women with Endometriosis-Associated Pain.

                 PRAECIS Protocol Number 149-99-02

                 No Amgen Protocol Number

          (ii)   ROLLOVER STUDY
                 A Rollover, Multicenter, Open-Label, Maintenance Study of
                 Patients with Prostate Cancer Who Were Previously Treated with
                 Abarelix-Depot 50mg or 100mg IM.

                 PRAECIS Protocol Number 149-99-04

                 Amgen Protocol Number 990789

          (iii)  3b STUDY
                 An Open-label comparison of Neoadjuvant Hormonal Therapy (NHT)
                 with Abarelix Depot 100 mg IM or Lupron Depot 7.5 mg IM in
                 Patients with Prostate Cancer Planned to Undergo Brachytherapy
                 or External-beam Radiation Therapy.

                 PRAECIS Protocol Number 149-00-01

                 Amgen Protocol Number 20000170

          (iv)   INVESTIGATOR IND CLINICAL STUDIES
                 Phase II study of abarelix-depot in androgen-independent
                 prostate cancer.

                 Amgen Protocol Number 20000775

                 Phase II trial of abarelix-depot in patients with
                 androgen-independent prostate cancer.

                 Amgen Protocol Number 20000726

          (v)    INVESTIGATOR IND PRECLINICAL STUDIES
                 The role of androgen surge in the response of prostate cancer
                 to androgen withdrawal.

                 (No protocol number available) Amgen Contract # 20008224

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                 Evaluation of abarelix on the prostate cancer in the TRAMP
                 model.

                 (No protocol number available) Amgen Contract # 20008261

     (b)  CLINICAL STUDIES CONTRACTS. The parties acknowledge that, pursuant to
          separate letter agreements (the "CLINICAL STUDIES ASSIGNMENT
          AGREEMENTS"), Amgen has assigned to PRAECIS all of Amgen's rights, and
          PRAECIS has assumed all of Amgen's obligations, under the agreements
          listed on Exhibit L hereto as of the dates set forth therein, all of
          which are agreements for clinical sites related to the Assumed
          Clinical Studies (the "CLINICAL STUDIES CONTRACTS"), without
          limitation, however, of Amgen's obligations under Section 12(a)
          hereof.

9.   NON-ASSERTION COVENANT. Amgen, on behalf of itself and its officers,
directors, employees, agents and Affiliates and each of their respective
successors and assigns, agrees not to bring, and not to permit any other party
acting on its behalf to bring, any suit, action or proceeding alleging that any
activity of PRAECIS or any Affiliate or any licensee or sublicensee thereof in
connection with the development or commercialization of any Licensed Products
(a) substantially as the Licensed Products exist on the Signing Date and (b)
substantially as such development or commercialization was contemplated by the
Collaboration Agreement prior to its termination, infringes any patent or other
intellectual property right owned or controlled by Amgen or any of its
Affiliates as of the Signing Date. Nothing contained in this Section 9 shall
prevent Amgen

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from defending the validity of any patent or other intellectual property right
in any action brought against Amgen.

10.  RELEASES; COVENANTS NOT TO SUE; NO ASSIGNMENT OF CLAIMS.

     (a)  Releases.

          (i)    RELEASE BY AMGEN. Amgen, on behalf of itself and its officers,
     directors, employees, agents and Affiliates and each of their respective
     successors and assigns, hereby irrevocably and unconditionally releases and
     forever discharges PRAECIS, and its officers, directors, employees, agents
     and Affiliates and each of their respective successors and assigns, from
     all claims, liabilities, obligations, causes of action and demands of any
     nature whatsoever, whether known or unknown, on account of or arising from
     the Collaboration Agreement or any other Collaboration Transaction
     Documents, or any breach of any of the foregoing, including any remedies
     which Amgen might otherwise now or hereafter have thereunder, both in
     equity and at law, but excluding all claims, liabilities, indemnifications,
     obligations, causes of action and demands under the Surviving Agreements,
     this Termination Agreement or any agreement or instrument entered into on
     or after the Signing Date between PRAECIS and Amgen (or by PRAECIS or Amgen
     for the benefit of the other) pursuant to or as contemplated by this
     Termination Agreement.

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          (ii)   RELEASE BY PRAECIS. PRAECIS, on behalf of itself and its
     officers, directors, employees, agents and Affiliates and each of their
     respective successors and assigns, hereby irrevocably and unconditionally
     releases and forever discharges Amgen, and its officers, directors,
     employees, agents and Affiliates and each of their respective successors
     and assigns, from all claims, liabilities, obligations, causes of action
     and demands of any nature whatsoever, whether known or unknown, on account
     of or arising from the Collaboration Agreement or any other Collaboration
     Transaction Documents, or any breach of any of the foregoing, including any
     remedies which PRAECIS might otherwise now or hereafter have thereunder,
     both in equity and at law, but excluding all claims, liabilities,
     indemnifications, obligations, causes of action and demands under the
     Surviving Agreements, this Termination Agreement or any agreement or
     instrument entered into on or after the Signing Date between PRAECIS and
     Amgen (or by PRAECIS or Amgen for the benefit of the other) pursuant to or
     as contemplated by this Termination Agreement.

          (iii)  GENERAL RELEASE OF UNKNOWN CLAIMS. In connection with the
     foregoing releases set forth in this Section 10(a), except as expressly set
     forth therein, each of PRAECIS and Amgen hereby waives the benefits of
     Section 1542 of the California Civil Code which provides:

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          "A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE CREDITOR DOES
          NOT KNOW OR SUSPECT TO EXIST IN HIS FAVOR AT THE TIME OF EXECUTING THE
          RELEASE WHICH, IF KNOWN BY HIM, MUST HAVE MATERIALLY AFFECTED HIS
          SETTLEMENT WITH THE DEBTOR."

     (b)  Notwithstanding the provisions of Section 1542, this Termination
          Agreement releases claims to the extent provided in Section 10(a)
          above, whether known or unknown, foreseen, unforeseen, patent or
          latent which each party has as of the date hereof against the other,
          and this release shall act as a release of future claims that may
          arise from acts arising prior to the date hereof, whether such claims
          are currently known, unknown, foreseen, unforeseen, patent or latent.
          Each of PRAECIS and Amgen understands and acknowledges the
          significance and consequence of such specific waiver of Section 1542
          and hereby assumes full responsibility for such waiver.

     (c)  COVENANT NOT TO SUE. The parties, on behalf of themselves and their
          respective officers, directors, employees, agents and Affiliates and
          each of their respective successors and assigns, hereby irrevocably
          and unconditionally waive and give up any right to, and covenant and
          agree not to and not to permit any other party acting on their behalf
          to, commence any action, or bring any

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          charge or complaint, against each other or any of the other Persons
          released under Section 10(a) above, with respect to the claims,
          liabilities, obligations, causes of action or demands so released
          under Section 10(a) above, or to seek or be entitled to any equitable
          or monetary relief in any action or in connection with any charge or
          complaint that may be commenced or brought on their behalf with
          respect thereto.

     (d)  NO ASSIGNMENT OF CLAIMS. Each party hereby represents and warrants to
          the other that neither it nor any of its Affiliates has assigned to
          any other Person any claims, causes of action or demands released
          pursuant to Section 10(a) above.

     (e)  NO ADMISSION. Each party acknowledges that this Termination Agreement
          effects the settlement of existing and potential claims, and nothing
          herein is intended to constitute or should be construed as an
          admission of liability to any party or to any Person.

11.  CONFIDENTIALITY.

     (a)  PRAECIS CONFIDENTIAL INFORMATION. Subject to the further provisions of
          this Section 11(a), Amgen will keep confidential and will not publish
          or otherwise disclose or use for any purpose any data, information or
          materials of PRAECIS or Amgen constituting or contained in any
          Deliverables, or constituting, contained in or

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          relating to any Collaboration Technology or any Licensed Product, or
          otherwise created or developed by or on behalf of PRAECIS or Amgen, or
          disclosed by PRAECIS to Amgen, pursuant to or in connection with the
          Collaboration Agreement (collectively, "PRAECIS CONFIDENTIAL
          INFORMATION"), except (i) as separately agreed to in writing by
          PRAECIS after the Signing Date; (ii) solely with respect to PRAECIS
          Confidential Information which is also Amgen Confidential Information
          and solely to the extent such PRAECIS Confidential Information (A) was
          created or developed without use of, and does not include, incorporate
          or utilize, any data, information, technology, inventions or
          intellectual property rights included in the Collaboration Technology,
          and (B) is not included or incorporated in, or utilized by PRAECIS or
          any licensee or sublicensee thereof in connection with the development
          or commercialization of, any Licensed Products substantially as
          Licensed Products exist on the Signing Date and substantially as such
          development or commercialization was contemplated by the Collaboration
          Agreement prior to its termination; (iii) to the extent that such
          PRAECIS Confidential Information (A) was generally available to the
          public or otherwise part of the public domain at the time of its
          disclosure to the Receiving Party, or (B) became generally available
          to the public or otherwise part of the public domain after its
          disclosure or development, as the case may be,

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          other than through any act or omission of Amgen in breach of this
          Section 11(a); or (iv) to the extent that (A) such PRAECIS
          Confidential Information is required to be disclosed in prosecuting or
          defending litigation (including any litigation relating to the
          enforcement of this Agreement) or complying with any court order or
          governmental regulation or (B) Amgen determines in good faith, after
          consultation with outside legal counsel, that such Praecis
          Confidential Information is otherwise required by law (including any
          rule, regulation, policy or practice of any regulatory agency or
          authority or any stock market or exchange on which any securities of
          Amgen are listed and traded) to be disclosed. Nothing contained in
          this Section 11(a) shall constitute any grant by PRAECIS of any
          license or other rights in or to any intellectual property of PRAECIS
          nor prevent PRAECIS from defending the validity of any patent or other
          intellectual property right in any action, proceeding or investigation
          against or involving PRAECIS.

     (b)  AMGEN CONFIDENTIAL INFORMATION. PRAECIS will keep confidential and
          will not publish or otherwise disclose or use for any purpose any
          data, information or materials of Amgen constituting or contained in
          any Deliverables, or constituting, contained in or relating to any
          Collaboration Technology or any Licensed Product, or otherwise created
          or developed by or on behalf of Amgen (other than by or on behalf of
          PRAECIS), or

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          disclosed by Amgen to PRAECIS, pursuant to or in connection with the
          Collaboration Agreement (collectively, "AMGEN CONFIDENTIAL
          INFORMATION"), except (i) as separately agreed to in writing by Amgen
          after the Signing Date; (ii) in connection with the development or
          commercialization of the Collaboration Technology or Licensed Products
          (for the avoidance of doubt, including in connection with the filing
          or prosecution of any patent applications); (iii) to the extent that
          such Amgen Confidential Information (A) was generally available to the
          public or otherwise part of the public domain at the time of its
          disclosure to PRAECIS, or (B) became generally available to the public
          or otherwise part of the public domain after its disclosure or
          development, as the case may be, other than through any act or
          omission of PRAECIS in breach of this Section 11(b); or (iv) to the
          extent that (A) such Amgen Confidential Information is required to be
          disclosed in prosecuting or defending litigation (including any
          litigation relating to the enforcement of this Agreement) or complying
          with any court order or governmental regulation or (B) PRAECIS
          determines in good faith, after consultation with outside legal
          counsel, that such Amgen Confidential Information is otherwise
          required by law (including any rule, regulation, policy or practice of
          any regulatory agency or authority or any stock market or

                                       22
<Page>

          exchange on which any securities of Praecis are listed and traded) to
          be disclosed.

12.  INDEMNIFICATION.

     (a)  INDEMNIFICATION BY AMGEN. Amgen shall indemnify PRAECIS against, and
          hold PRAECIS harmless from, any and all liabilities, losses, damages
          or costs and expenses (collectively, "LOSSES") arising out of (i) any
          third-party claims of any nature in connection with the research,
          development, manufacturing or marketing of Licensed Products, or
          actions or omissions relating thereto, in each case prior to the
          Signing Date, by, on behalf of, under authority of, or pursuant to
          contracts with, Amgen, any of its Affiliates or their respective
          licensees or sublicensees, including without limitation pursuant to
          the Collaboration Transaction Documents, but only if and to the extent
          such Losses are attributable to the gross negligence or willful
          misconduct of Amgen or its Affiliates or their respective licensees or
          sublicensees; (ii) any breach by Amgen of any covenant or agreement of
          Amgen contained in this Termination Agreement or in the Surviving
          Agreements; (iii) any representation or warranty of Amgen contained in
          this Termination Agreement being untrue in any material respect;
          and/or (iv) the matters described on Exhibit M attached hereto. For
          purposes hereof, any manufacturing or other activities or obligations

                                       23
<Page>

          performed or provided by PRAECIS shall not be considered to have been
          performed or provided on behalf of, or under authority of, Amgen, its
          Affiliates or sublicensees. For the avoidance of doubt, PRAECIS
          acknowledges and agrees that Amgen shall not be required to indemnify
          Praecis pursuant to clause (i) of this Section 12(a) to the extent
          that any Losses referred to in such clause (i) are attributable to
          Amgen's or its Affiliate's active or passive negligence, provided such
          negligence does not constitute gross negligence.

     (b)  INDEMNIFICATION BY PRAECIS. PRAECIS will indemnify Amgen against, and
          hold Amgen harmless from, all Losses arising out of (i) any third
          party claims of any nature in connection with the research,
          development, manufacturing, marketing or sale of Licensed Products
          (other than by, on behalf of or under authority of Amgen, its
          Affiliates, or sublicensees), or actions or omissions relating
          thereto, whether occurring prior to, on or after the Termination Date,
          including without limitation any such claims arising out of the
          Assumed Clinical Studies, the Clinical Studies Contracts, the Clinical
          Studies Assignment Agreements, the Clinical Studies Letter Agreement,
          the Assumed Other Contracts, any Collaboration Transaction Documents
          (including the UCB-Amgen Agreement), the IUF License Agreement or the
          Synthelabo Agreement, as any such agreements may be amended, modified
          or

                                       24
<Page>

          supplemented from time to time (including, in the case of this clause
          (i) any such third party claims for Losses consisting of contractual
          obligations of Amgen assumed by PRAECIS which were in effect as of the
          time such contractual obligations were assumed by PRAECIS), provided,
          however, that notwithstanding the foregoing or any other provision of
          this Termination Agreement or any Surviving Agreement, PRAECIS shall
          have no obligation or liability under this Section 12(b) or otherwise
          with respect to any Losses as to which Amgen is required to indemnify
          PRAECIS pursuant to clause (i) or (iv) of Section 12(a) hereof; (ii)
          any breach by PRAECIS of any covenant or agreement of PRAECIS
          contained in this Termination Agreement or in the Surviving
          Agreements; and/or (iii) any representation or warranty of PRAECIS in
          this Termination Agreement being untrue in any material respect.

     (c)  NOTICE OF INDEMNIFICATION CLAIM. Each party will notify the other
          party in writing within five (5) business days of becoming aware of a
          claim for which indemnification may be sought hereunder.

13.  ENTIRE AGREEMENT. This Termination Agreement (including the Exhibits
attached hereto which are incorporated by reference herein and the Surviving
Agreements) constitutes the entire agreement between the parties with respect to
the subject matter hereof (and thereof) and supersedes all previous agreements
or

                                       25
<Page>

understanding between the parties. This Termination Agreement shall bind and
inure to the benefit of, and be enforceable by, the parties and, with respect to
Sections 10 and 24, the other Persons referred to therein, and the respective
successors, assigns, heirs, executors and administrators of the parties and,
with respect to Sections 10 and 24, of such other Persons. This Termination
Agreement may only be changed or modified by written agreement of the parties.

14.  GOVERNING LAW AND JURISDICTION. This Termination Agreement will be governed
by and interpreted in accordance with the laws of the State of Delaware, without
reference to its conflicts of law principles. The parties hereby submit to the
exclusive jurisdiction of the Delaware courts, both state and federal, in all
matters concerning this Termination Agreement.

15.  COUNTERPARTS. This Termination Agreement may be executed in counterparts
(and by facsimile signatures), each of which shall be deemed an original but
which together shall constitute one and the same instrument.

16.  VALIDITY AND BINDING NATURE OF AGREEMENT. Each party hereby represents and
warrants to the other that this Termination Agreement has been duly authorized,
executed and delivered by, and is the valid and binding obligation of, such
party, enforceable against such party in accordance with its terms.

17.  NO OTHER REPRESENTATIONS. Each party acknowledges having read this
Termination Agreement and fully understands its provisions, and acknowledges

                                       26
<Page>

and agrees that no representation or promise not contained herein has been made
to induce such party to enter into this Termination Agreement.

18.  LEGAL ADVICE. Each party has had the opportunity to receive and has
received independent legal advice from attorneys of their choice with respect to
the advisability of making the settlement and release provided herein and of
executing this Termination Agreement.

19.  DISPUTES. Each party hereto agrees that in the event of any litigation
arising under this Termination Agreement, the prevailing party shall be entitled
to recover the reasonable fees and disbursements of counsel paid by such
prevailing party in connection with such litigation.

20.  PUBLIC ANNOUNCEMENTS. Neither party will make any public announcement
regarding this Termination Agreement without the prior approval of the other
party. In addition, in no event will either party use the name of the other
party in any press release or other public announcement without the prior
approval of the named party; provided, however, that no such approval of the
other party shall be necessary if the press release or other public announcement
is substantially similar to releases or announcements previously approved by
such party (provided, however, that the term "substantially similar" shall not
be deemed to permit additional information to be included in any such release or
announcement if such information has not been previously approved by the other
party). Each party agrees not to publicly disparage or defame, or make any
material misrepresentation regarding the other party or any officer, director or

                                       27
<Page>

employee of the other party; provided that this Section 20 shall not impair a
party's right to provide truthful testimony or other information, or to
otherwise make public statements or disclosures, to the extent a party, after
consultation with outside legal counsel, determines in good faith that it is or
may be required by law to do so.

21.  NOTICE. Any notice, demand or communication under this Termination
Agreement shall be in writing and served by personal delivery, registered or
certified mail, or by overnight delivery by a nationally-recognized overnight
delivery service, to the address of the party receiving notice as set forth in
the first paragraph of this Termination Agreement, or at any domestic address
that a party may provide to any other party in writing from time to time.

22.  SEVERABILITY. Whenever possible, each provision of this Termination
Agreement shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of this Termination Agreement shall become
prohibited or invalid under applicable law, such provision shall be ineffective
only to the extent of such prohibition or invalidity without invalidating the
remainder of such provision or the remaining provisions of this Termination
Agreement, which shall remain in full force and effect.

23.  WAIVER. No waiver of any provision of this Termination Agreement or of any
provision of any agreement or instrument entered into in accordance herewith or
as contemplated hereby shall be valid unless made in writing and executed by a
duly authorized officer of the waiving party. Failure of either party to insist
upon

                                       28
<Page>

strict observance of or compliance with any of the terms of this Termination
Agreement in one or more instances shall not be deemed to be a waiver of its
rights to insist upon such observance of or compliance with such terms or the
other terms hereof with respect to subsequent failures in the future.

24.  THIRD PARTY VENDORS AND CONSULTANTS. Amgen agrees that it will not, and
will cause its Affiliates not to, interfere with, obstruct or impede any third
party vendor, supplier or consultant with respect to, and for the benefit of the
PRAECIS Parties (as defined below) and each such third party vendor, supplier or
consultant, Amgen hereby consents to such third parties, (except to the extent
provided in Exhibit N with respect to two employees of one such third party
consultant) initiating, continuing or carrying out work for PRAECIS, its
Affiliates or their respective licensees or sublicensees (the "PRAECIS Parties")
in connection with the development or commercialization of Collaboration
Technology or Licensed Products, it being acknowledged and agreed, however, that
this Section 24 shall not diminish in any manner the obligations of the parties
under Section 11 of this Termination Agreement or Amgen's rights under any
agreement between Amgen and such third party vendor, supplier or consultant
(provided that in any event Amgen will permit any such third party to disclose
Amgen Confidential Information to the same extent that PRAECIS would be
permitted to disclose such information under Section 11(b) of this Termination
Agreement) nor impair in any manner Amgen's ability to enter into agreements not
inconsistent with this Section 24 with any such vendor, supplier or consultant.

                                       29
<Page>

     IN WITNESS WHEREOF, PRAECIS PHARMACEUTICALS INCORPORATED and Amgen Inc.
have caused this Termination Agreement to be duly executed by their authorized
representatives as of the date first written above.

PRAECIS PHARMACEUTICALS INCORPORATED

By:    /s/ Kevin F. McLaughlin
       ------------------------
Name:  Kevin F. McLaughlin
       ------------------------
Title: Senior Vice President
       and Chief Financial
       Officer
       ------------------------

AMGEN INC.

By:    /s/ Fabrizio Bonanni
       ------------------------
Name:  Fabrizio Bonanni
       ------------------------
Title: Senior Vice President of
       Quality and Compliance
       ------------------------

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EXHIBIT 10.1    
  

 
 

INTELLECTUAL PROPERTY SALE, AMENDMENT AND TERMINATION AGREEMENT    
  

        This INTELLECTUAL PROPERTY SALE, AMENDMENT AND TERMINATION AGREEMENT, dated as of October 2, 2002 (the
"Amendment") hereby amends the DISTRIBUTION, LICENSE AND SUPPLY AGREEMENT, dated as of December 7, 1999, and as amended from time to time
thereafter (the "Agreement"), by and between ANESTA CORP., a Delaware corporation ("Anesta") and ELAN PHARMA INTERNATIONAL
LIMITED, an Irish Company ("Elan"). Capitalized terms used herein but not defined shall have the meanings given to them in the Agreement. 

 
 

Recitals    
  

        WHEREAS, on December 7, 1999, Anesta and Elan entered into the Agreement, pursuant to which Anesta and Elan
agreed upon the terms under which Elan or its Subdistributors would distribute, market and sell OT-fentanyl in the Territory; 

        WHEREAS, Anesta and Elan entered into letter agreements on December 7, 1999, January 21, 2000 and January 31, 2001
that modified certain terms of the Agreement; and 

        WHEREAS, Anesta and Elan now desire Elan to sell to Anesta its rights in respect of the Anesta Patents and the Anesta Know-How
under the Agreement and to terminate or amend certain aspects of their relationship, and wish to do so by amending certain provisions of the Agreement. 

        NOW, THEREFORE, in consideration of the foregoing and the covenants and promises contained in the Agreement and in this Amendment, the
Parties agree as follows: 

        A.    The
Parties hereby agree (i) that Elan shall sell to Anesta and Anesta shall acquire Elan's rights in respect of the Anesta Patents and Anesta Know-How
under the Agreement, (ii) to end the appointment of Elan as the exclusive distributor of OT-fentanyl Products in the Territory, and (iii) in pursuance thereof to terminate
the exclusive license to market, import, use, sell, offer for sale, manufacture and distribute OT-fentanyl Products in the Territory that was granted by Anesta to Elan under the Agreement,
in each case with effect from the Repurchase Date and subject to the provisions of this Amendment. In furtherance of and in connection with the foregoing, the Parties hereby agree that the following
provisions of the Agreement are amended as follows: 

        1.    Section 1
of the Agreement is hereby amended by the insertion of the following Sections 1.1A and 1.27A: 

        "1.1A "Amendment" shall mean the intellectual property sale, amendment and termination agreement dated October 2, 2002. 

        "1.27A "Repurchase Date" shall mean October 2, 2002. 

        2.    Sections
2.1 and 2.3 of the Agreement are hereby deleted in their entirety, and are of no further force and effect as of the date hereof. 

        3.    Section 2.4
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "2.4 Distribution Period.    The Distribution Period shall commence upon the first date of sale of OT-fentanyl
Products in the Territory and shall expire on the Repurchase Date immediately after the coming into effect of the Amendment." 

        4.    Sections
2.5, 2.6, 2.7, 2.8, 2.9(a), 2.9(b) and 2.9(c) of the Agreement are hereby deleted in their entirety, and are of no further force and effect as of the date
hereof. 

        5.    Section 2.9(d)
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "(d) Anesta Ownership.    Elan hereby confirms, agrees to and recognizes Anesta's exclusive ownership of the Anesta Trademarks
and the renown of the Anesta Trademarks." 

 

        6.    Section 2.9(e)
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "(e) Goodwill.    The Parties agree that all use of the Anesta Trademarks by Elan has been for the sole and exclusive benefit of
Anesta and the goodwill and reputation accrued in connection with Elan's use of the Anesta Trademarks has accrued to Anesta. In the event Elan has acquired any right, title or interest in or to or
relating to the Anesta Trademarks for any reason, effective immediately Elan hereby assigns, at no cost, all such right, title and interest, together with any related goodwill or reputation, to
Anesta. Elan agrees to promptly execute all documents reasonably requested by Anesta in connection with such assignment." 

        7.    Sections
2.9(f), 2.9(g), 2.9(h), 3.1, 3.2, 3.3, 3.4, 3.5 3.7, 3.8, 4.1 (subject to Section 10.5 of the Agreement, as amended by this Amendment), 4.2, 4.3, 4.4 and
4.5 of the Agreement are hereby deleted in their entirety, and are of no further force and effect as of the date hereof. 

        8.    Section 4.7
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "4.7 Products Recall. 

        (a) Voluntary Recall.    If either Party desires to recall OT-fentanyl Products shipped prior to the Repurchase Date
for non-conformities with Specifications (other than such non-conformities that would require recall pursuant to the requirements of applicable laws or regulations), it shall
so notify the other Party. If the other Party does not agree that the relevant OT-fentanyl Products do not comply with Specifications, the dispute shall be settled as set forth in
Section 4.7(c). If the Parties agree as to such non-conformity or such non-conformity is determined pursuant to Section 4.7(c), then the Party desiring the recall
shall administer the recall in a commercially reasonable manner with the other Party's cooperation. If one Party's actions were the sole cause of the non-conformity with Specifications,
such Party shall bear all costs and expenses of the recall. 

        (b) Mandatory Recall.

        (i) In the event that the relevant regulatory authority requires or otherwise initiates a recall of the OT-fentanyl Products
shipped prior to the Repurchase Date for any reason whatsoever, Anesta will forthwith administer the recall. If the Parties are unable to agree as to whether or not the underlying reason for the
recall is a non-conformity of the OT-fentanyl Products with Specification, and/or whether or not Anesta or Elan is responsible for such non-conformity, the Parties
shall submit a sample of the recalled OT-fentanyl Products for analysis pursuant to Section 4.7(c). If a Party is notified by a regulatory authority that a recall is required, it
shall promptly give to the other Party written notice of the need to recall that quantity. 

        (ii) In the event that the principal reason for the recall under this Section 4.7(b) is Elan's negligence or willful misconduct,
its failure to handle or store OT-fentanyl Products in conformity with Specifications, or Elan's failure to comply with applicable laws or regulations, then Elan shall be liable for the
cost of the recall and any replacement quantities of OT-fentanyl Products and will reimburse Anesta for all its reasonable costs and expenses of such recall. In all other cases, Anesta
shall be solely responsible for all costs of the recall and any replacement quantities of OT-fentanyl Products and shall reimburse Elan for all its reasonable costs and expenses of
assisting in such recall. 

        (c) Testing. If there is a disagreement as referred to in the second sentence of Section 4.7(a) or the second sentence of
Paragraph 4.7(b)(i), the Parties shall submit samples of the OT-fentanyl Products in question and the samples of the corresponding batch retained by Anesta to a mutually acceptable
Third Party laboratory, which shall determine whether such OT-fentanyl Products meets the Specifications and/or, as applicable, whether or not Anesta or Elan is responsible for such
non-conformity. The Parties agree that the determination of the laboratory, after it has assessed the 

2

 

retention samples, shall be final and determinative. The Party against whom the Third Party tester rules shall bear the reasonable costs of the Third Party testing." 

        9.    Section 4.8(a)
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "(a) Both Parties warrant as of the Repurchase Date that they have complied with all applicable present and future orders, regulations,
requirements and laws of any and all federal, state, provincial and local authorities and agencies in the Territory relating to the promotion, marketing, sale and distribution of the
OT-fentanyl Products on a country by country basis in the Territory. Regarding the shipment of OT-fentanyl Products into and within the Territory, Elan hereby warrants as of
the Repurchase Date that it has complied with the requirements of Exhibit F (as amended from time to time by Anesta to be in accordance with changes in the applicable laws or regulations or
interpretations thereof)." 

        10.    Sections
5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 6.1, 6.2, 6.3, 6.4 and 6.5 of the Agreement are hereby deleted in their entirety, and are of no further force and effect
as of the date hereof. 

        11.    Sections
7.1, 7.2 and 7.3 are each hereby deleted in their entirety, and are of no further force and effect as of the date hereof. 

        12.    Other
than with respect to any OT-fentanyl Products inventory sold by Elan prior to the date hereof ("Prior Sales"), Sections 7.4, 7.5, 7.6, 7.7 and 7.8 are
hereby deleted in their entirety, and are of no further force and effect as of the date hereof. With respect to Prior Sales, Anesta shall be entitled to receive royalty payments from Elan as though
these sections remained in full force and effect. 

        13.    Section 8.1
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "8.1.    Ownership of Intellectual Property.    Anesta shall retain all of its right, title and interest in and to all
Anesta Technology, Anesta Trademarks, copyrights, and all other industrial and intellectual property embodied in or which covers the OT-fentanyl Products. Except as otherwise expressly
provided in this Amendment, Elan hereby confirms as of the Repurchase Date that it has no right, title or interest in any industrial or intellectual property relating to the OT-fentanyl
Products." 

        14.    Section 8.2
and 8.3(a) of the Agreement are hereby deleted in their entirety, and are of no further force and effect as of the date hereof. 

        15.    Section 8.3(b)
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "(b) Third Party Claims.    Anesta shall indemnify and hold harmless Elan, its Affiliates and their employees and agents against
all and any claims, suits or actions filed or threatened against Elan and/or any distributor of OT-fentanyl Products claiming that a patent or other intellectual property right owned by it
is infringed or misappropriated by the distribution, marketing or sale of any OT-fentanyl Products. Anesta may, but shall not be obligated to defend any such claims, suits or actions. Elan
will assist in the defense of any such claim, suit or action as reasonably requested by Anesta, at Anesta's expense. Anesta shall not settle any such claim, suit or action if such settlement contains
an admission of liability or would impose on Elan any obligation which cannot be performed solely by Anesta without the prior express written consent of Elan, which shall not be unreasonably withheld
or delayed." 

        16.    Section 8.3(c)
of the Agreement is hereby deleted in its entirety, and is of no further force and effect as of the date hereof. 

3

 

        17.    Section 8.4(a)
of the Agreement shall be deleted in its entirety with effect from the first anniversary of the date hereof, and shall be of no further force and
effect as of the first anniversary of the date hereof. 

        18.    Section 8.4(b)
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "(b) Prosecution by Anesta.    Anesta may, but shall not be obligated to commence, at its own expense, an infringement action
against any person or entity infringing, including infringement or misappropriating the Anesta Technology directly or contributorily. To the extent that such infringement is alleged to relate to the
period prior to the Repurchase Date, Elan shall cooperate with Anesta as reasonably requested, at Anesta's expense." 

        19.    Section 8.4(c)
and 9.3 of the Agreement are hereby deleted in their entirety, and are of no further force and effect as of the date hereof. 

        20.    Section 10.1
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "10.1.    Term.    Except as otherwise provided in Section 10.3 hereof, this Agreement shall expire upon the
expiration of the Distribution Period." 

        21.    Section 10.2
of the Agreement is hereby deleted in its entirety, and is of no further force and effect as of the date hereof. 

        22.    Section 10.3
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "10.3.    Accrued Rights, Surviving Obligations.    This Amendment or the termination or expiration of this Agreement
shall not affect any accrued rights of either Party. The terms of Sections 2.2, 2.4, 2.9(d), 2.9(e), 3.6, 4.6, 4.7, 4.8, 5.9, 7.5 (for royalty payments accruing during the Distribution Period), 7.6,
7.7, 7.8, 10.1, 10.3, 10.4, 10.5, 10.6, 10.7, 12.4 and 12.5 and Articles 1, 8, 9, 11 and 13, together with all exhibits to the Agreement, as such provisions have been amended by the Amendment, shall
survive the termination or expiration of this Agreement." 

        23.    Section 10.4
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "10.4. Existing OT-fentanyl Products Inventory.

        (a)    Sale of Existing Inventory. Upon the terms and subject to the conditions of the Amendment, Anesta hereby agrees to pay to
Elan on behalf of the Designated Purchasing Party within two days of the Repurchase Date a sum equal to US$600,000 (six hundred thousand dollars) (the "Existing Inventory Purchase Price"), by wire
transfer to a bank which Elan shall designate in writing to Anesta with at least three days advance written notice, in full payment for the sale, conveyance, assignment and delivery to the designated
Purchasing Party under clause 10.4(d) of any OT-fentanyl Products and placebos of the same (together "Relevant Products") in its inventory as of the Repurchase Date (the "Existing
Inventory"), subject to adjustment as set forth in Section 10.4(c) of this Agreement (as amended). For the avoidance of doubt, any sums payable under this clause 10.4(a) will be
exclusive of any VAT or other relevant taxes that may be payable. 

        (b)    Purchasing Party. Anesta will have the right to appoint any of its Affiliates as the entity that will purchase the
Existing Inventory located in the various territories. For the purpose of this Agreement, the Affiliate that is appointed to purchase the Existing Inventory will be known as the Designated Purchasing
Party. The Designated Purchasing Party will take full legal title to the goods that it acquires, and shall have the right to sell or otherwise dispose of these goods as legal owner. Elan agrees to
issue invoices for the Existing Inventory to the Designated Purchasing Party. 

4

   
        (c)    Calculation of Existing Inventory Value. Within fourteen (14) days after the Repurchase Date, Elan and Anesta (or
a designated representative of Anesta) shall jointly conduct a physical stock take of the Existing Inventory existing as of such date, and Elan shall issue, within 15 days after the Repurchase
Date, on the basis of such physical stock take and the amount of Existing Inventory shipped to customers at Anesta's written direction (copies of which shall be provided to Elan) between the
Repurchase Date and such physical stock take, in reasonable detail a report setting forth the result of such stock take and a calculation of the Existing Inventory Value (as defined below). Anesta (or
a designated representative of Anesta) shall have the right to review all work papers and procedures used to calculate the Existing Inventory Value. Unless, within 15 days after delivery of the
report setting forth Elan's calculation of the Existing Inventory Value, Anesta notifies Elan in writing that it objects to the calculation of Existing Inventory Value and specifies the basis for its
objection, the Existing Inventory Value as calculated by Elan shall be final and binding on the Parties for purposes of this Section 10.4(b). If Anesta objects and if Anesta and Elan are not
able to resolve Anesta's objections within 15 days after such notification is given, all remaining matters in dispute shall be resolved in accordance with Section 13.2 of the Agreement.
For purposes hereof, "Existing Inventory Value" shall mean the total value of the Existing Inventory existing as of the Repurchase Date calculated by: (i) multiplying (aa) the number of units
of Relevant Products in Elan's inventory which in the case of OT-fentanyl Products are in saleable condition and with a shelf life of not less than 9 (nine) months as of the Repurchase
Date (and products shipped at Anesta's written direction between the Repurchase Date and the date of the stock take shall be deemed to meet those criteria) and (bb) the sum of (x) the
VAT-exclusive amount originally invoiced per unit by Anesta to Elan (y) the VAT-exclusive amount paid by Elan in respect of transportation of such Relevant Products to
their place of storage and (z) the VAT-exclusive amount paid by Elan in respect of finished pack release testing; and (ii) adding VAT payable in respect of such units. 

        Supply
of each unit of OT-fentanyl Products in Elan's inventory shall be EXW (Incoterms 2000) its place of storage (or, at Anesta's option and subject to the consent of the
party storing it, by reappropriation within such place of storage). Accordingly the Parties acknowledge that each such supply is within the particular country of the place of storage. Anesta further
acknowledges and agrees that the OT-fentanyl Products in any particular location may be held by, and supplied to Anesta by one or more Affiliates of Elan, and that payment in respect of
the same may be due to such Affiliate(s), provided, however, that Anesta shall be entitled to pay to Elan all amounts due hereunder to any Affiliate of Elan, and such payment by Anesta to Elan shall
satisfy all of Anesta's payment obligations to such Affiliate under this Section 10.4. 

        (d)    Destroyed Product. It is hereby acknowledged that as from November 10, 2002, it will not be permissible to sell
certain OT-fentanyl Products ("Old Logo Products") in the United Kingdom under applicable law, due to such Old Logo Products bearing a name on their packaging which is not within the
requisite approvals, as amended. From the Repurchase Date until November 10, 2002, Anesta shall use all reasonable efforts to sell such Old Logo Products in the United Kingdom in preference to
other
OT-fentanyl Products (consistent with such products having an adequate shelf life). To the extent that, despite reasonable efforts, Anesta has not sold such Old Logo Products in the United
Kingdom by November 10, 2002, Elan shall pay to the Designated Purchasing Party in the United Kingdom the per unit cost of remaining Old Logo Products that were previously purchased by such
Designated Purchasing Party pursuant to this Section 10.4. Anesta shall inform Elan of, and shall provide a proper invoice in respect of, such amount, and Elan shall be entitled to inspect and
audit Anesta's records relating thereto. Such payment will be made within 15 days from November 10, 2002, by wire transfer to the bank designated by the Designated Purchasing Party.
Anesta shall at Elan's expense after November 10, 2002 promptly destroy any such remaining Old Logo Products. 

        (e)    Settlement. Within 15 days after the Existing Inventory Value has been finally determined in accordance with
Section 10.4(d), the difference, if any, between the Existing Inventory Purchase Price 

5

 

and the Existing Inventory Value shall be paid by Anesta to Elan (if the Existing Inventory Value exceeds the Existing Inventory Purchase Price) or by Elan to Anesta (if the Existing Inventory
Purchase Price exceeds the Existing Inventory Value). Such payment shall be by wire transfer to the bank designated by the payee. 

        (f)    Livery. As of the date six months following the Repurchase Date (or such earlier date as may be specified by governmental
or regulatory authority), Anesta shall not manufacture, package or release OT-fentanyl Products bearing Elan's name, logo and/or trademarks. Prior to such date, Anesta shall be permitted
to manufacture, package and release OT-fentanyl Products that bear Elan's name, logo and/or trademarks. Notwithstanding the foregoing, the parties hereby agree that after such date, the
Designated Purchasing Party may continue to sell any OT-fentanyl products from the Existing Inventory that bear Elan's name, logo and/or trademarks for as long as they are permitted to do
so under applicable law. Solely for the purposes for which Anesta is permitted to use Elan's name, logo and/or trademarks pursuant to this Section 10.4(f), Elan shall grant to Anesta a
non-exclusive, royalty free license in the United Kingdom, Ireland and Germany to such of Elan's trade marks as are used in the packaging of the OT-fentanyl Products as at the
Repurchase Date, from the Repurchase Date until exhaustion or disposal of the said permissibly manufactured, packaged and/or released OT-fentanyl Products, it being understood that Anesta
shall exhaust such stocks prior to selling OT-fentanyl Products without Elan's name, logo and trademarks. 

        Elan
shall retain all of its right, title and interest in and to its name, logo and/or trademarks. Subject to the foregoing paragraph, Anesta hereby confirms as of the Repurchase Date
that it has no right, title or interest in Elan's name, logo and/or trademarks.". 

        24.    Section 10.5
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "10.5. Transfer of Regulatory Approvals. Effective immediately as of the Repurchase Date, Elan shall to the extent permissible under
applicable law transfer or cause to be transferred to Anesta all Regulatory Approvals, or applications therefor, that are in the name of Elan at Anesta's cost. Elan
agrees to promptly execute all documents and take any other actions reasonably requested by Anesta in connection with such transfer, including the taking of any actions necessary (with Anesta's
cooperation and at Anesta's cost) to obtain publication of the marketing authorization therefor in the Gazetta Ufficiale in Italy. Anesta agrees to use
commercially reasonable efforts to assist in the transfer to Anesta of all such Regulatory Approvals or applications therefor as expeditiously as possible." 

        25.    Section 10.6
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "10.6. No Payment for Good Will. Where permitted by applicable law, Elan hereby expressly and irrevocably waives any of the following that
arises directly from the adoption of the Amendment or the termination of this Agreement: claims for compensation or damages based on lost profits, good will generated for the OT-fentanyl
Products or customers of the OT-fentanyl Products enlisted by Elan during the term of this Agreement, and any other claims or statutory rights." 

        26.    Section 10
of the Agreement is hereby amended by the insertion of the following Section 10.7: 

        10.7.    Returned Products. Elan shall be solely responsible for refunds due to customers in respect of returned
OT-fentanyl Products shipped to customers prior to the Repurchase Date. Anesta shall be solely responsible for refunds due to customers in respect of returned OT-fentanyl
Products shipped to customers on or after the Repurchase Date. The foregoing shall not affect (a) any right of Elan or Anesta under this Agreement, as the case may be, in respect of defects in
such OT-fentanyl Products, or (b) the calculation of Net Sales." 

6

 

        27.    Sections
12.1, 12.2 and 12.3 of the Agreement are hereby deleted in their entirety, and are of no further force and effect as of the date hereof (but for the avoidance
of doubt without prejudice to Article E of this Amendment). 

        28.    Section 12.4
of the Agreement is hereby amended with effect as of the date hereof by the deletion of the words "and further subject to the provisions of
Section 2.7". 

        29.    Section 13.4
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "13.4 Notices. Any notice required or permitted to be given under the Agreement or this Amendment shall be in writing, shall specifically
refer to the Agreement as amended by this Amendment and shall
be deemed to have been sufficiently given and received for all purposes if (i) eight (8) days after the notice was mailed by registered mail, postage prepaid and return receipt
requested, (ii) two (2) days after the notice was sent by internationally recognized express delivery service, (iii) one (1) day after the notice was sent by facsimile
transmission, with transmission confirmed, or (iv) immediately if the notice is personally delivered. Unless otherwise specified in writing, the mailing addresses of the Parties shall be as
described below. 

	For Anesta:	 	Anesta Corp.

4745 Wiley Post Way, Suite 650

Salt Lake City, Utah 84116

USA

Attention: President

Facsimile No.: 801.595.1406

Telephone and Confirmation No.: 801.595.1405
	

With a copy to:	
 	

Cephalon, Inc.

145 Brandywine Parkway

West Chester, Pennsylvania 19830

USA

Attention: General Counsel

Facsimile No.: 610.738.6590

Telephone and Confirmation No.: 610.344.0200
	

For Elan:	
 	

c/o Elan International Services Ltd.

102 St. James Court

Flatts,

Smiths FL04

Bermuda

Attention: Secretary

Facsimile No. +1 441 292 2224"

        30.    Exhibit E
of the Agreement is hereby deleted in its entirety, and is replaced as follows: 

        "Serious
Adverse Events, Non-Serious Adverse Events and Medical Information Queries. 

        A
Serious Adverse Event is defined as an occurrence that at any dose: 

	•
	Results
in death,

	•
	Is
life-threatening (note: "life-threatening" refers to an event in which the patient was at risk of death at the time of the event;
it does not refer to an event which hypothetically might have caused death if it were more severe),

	•
	Requires
inpatient hospitalization or prolongation of existing hospitalization, 

7

 

	•
	Results
in persistent or significant disability/incapacity,

	•
	Is
a congenital anomaly/birth defect, or

	•
	Is
an important medical event; i.e., based on scientific and medical judgment may jeopardize the patient or may require intervention to prevent one of the
other outcomes listed above 

        Elan
shall, on the Repurchase Date, forward copies of any and all details of Serious Adverse Events and Non-Serious Adverse Events reported to date to Elan in Germany,
Ireland and United Kingdom. Also, on the Repurchase Date Elan shall provide Anesta with details of all Medical Information queries received and responded to as of the Repurchase Date: such details
shall include (if provided), but not be restricted to correspondents, letters to correspondents, standard replies and bibliographies of references cited. Elan agrees to cooperate with Anesta and its
representatives to ensure that the hand-over of all such information is handled expeditiously and completely. 

        If,
after the Repurchase Date, Elan receives any written, telephone or other communications concerning Serious Adverse Events, Non-Serious Adverse Events or Medical
Information queries relating to Actiq, Elan shall notify Cephalon by e-mail within 24 hours. The information notified shall include, but shall not be restricted to: the person
reporting the information to Elan, the contact details for this person (to include at least: affiliation, address, telephone number, fax number and e-mail address), the nature of the
communication and the person at Elan who received the information. 

8

   
        Within ten (10) days after the Repurchase Date, Elan shall prepare and forward to Anesta for review written procedures (whether in the form of a Standard Operating Procedure (SOP)
or otherwise), detailing the procedures to be followed for contacting Anesta with such information as described herein. This SOP shall be approved by Anesta and enacted by Elan within 14 days
of Anesta's written approval. 

Elan
shall forward said information as follows: 

For
Germany: 

Alexandra
Martin (Cephalon GmbH) 

	Telephone:

Fax:

e-mail	 	+49 89 1709 4496

+49 89 1709 4495

amartin@cephalon.de
	

For Ireland and UK	
 	

 
	Balwant Heer (Cephalon UK Limited)
	Telephone:

Fax:

e-mail:	 	+44 1483 453360

+44 1483 457480

bheer@cephalon.com

        Notwithstanding
anything to the contrary in this Exhibit E, Elan shall not be obliged to provide information to the extent that the same may breach applicable data protection
legislation or other laws protecting privacy." 

        B.
In consideration of the sale by Elan to Anesta of Elan's rights under the Agreement in respect of the Anesta Patents and the Anesta Know-How and the covenants set forth in
Section C below, Anesta shall pay to Elan the non-refundable sum of US$50 million (fifty million dollars), in US$ and by wire transfer, within two days of the Repurchase Date
without any set-off, withholding or deduction whatsoever. The Parties hereby agree that any obligations of Elan owed to Anesta, or of Anesta owed to Elan, pursuant to or referred to in
Sections 7.1, 7.2 or 7.3 of the Agreement are hereby offset and deemed satisfied in connection with the payment by Anesta to Elan contemplated by this Section B. 

        C.
Within 7 (seven) days of the Repurchase Date, Elan shall provide to Anesta (i) copies of all promotional materials and sales aids used by Elan with respect to
OT-fentanyl Products (if available), and (ii) copies of any databases in Elan's possession containing the names of physicians who have prescribed OT-fentanyl Products.
Thereafter Elan and Anesta shall reasonably co-operate in good faith with a view to Elan making available to Anesta all non-confidential relevant material relating to the
marketing, sales and distribution of the OT-fentanyl Products in the Territory within Elan's possession, in order to effectuate the purposes of this Amendment. 

9

 

        D.
With effect from the date hereof, Anesta shall assume all rights and obligations of Elan and/or its Affiliates in respect of the following clinical trials (the "Clinical Trials"): 

	Elan Study Reference
	 	Country
	 	Title of Proposal
	 	Investigator Name

	001	 	Germany	 	Comparison of oral transmucosal fentanyl citrate ("OTFC") with oral immediate release morphine for initial dose titration of transdermal therapy with a fentanyl patch.	 	Dr L Radbruch
	

005	
 	

Italy	
 	

Prospective clinical trial on OTFC for the treatment of breakthrough cancer pain in patients already receiving opioid therapy.	
 	

Dr De Conno
	

014	
 	

UK	
 	

Phase I/II to investigate the use of OTFC in the management of acute mucosal pain for patients undergoing head and neck radiotherapy.	
 	

Dr AJ Sykes

        With
effect from the date hereof, Anesta shall also assume all rights and obligations of Elan and/or its Affiliates in respect of Elan's patient registry / patient survey (involving
approximately 30 physicians) in Germany. Notwithstanding the above, with respect to the Clinical Trials, Anesta shall be responsible for all costs and expenses relating to or arising from the Clinical
Trials up to the amount of US$5,000 (five thousand dollars), and Elan shall be responsible for all costs and expenses relating to or arising from the Clinical Trials in excess of such amount. Anesta
shall send an invoice to Elan requesting payment for any such costs or expenses pursuant to this Section D. 

        The
foregoing shall not constitute any assignment or attempted assignment which would be a breach by Elan of the contract with the counterparty thereto. Anesta shall perform Elan's
obligations thereunder and shall indemnify and hold harmless Elan against all claims, losses, expenses, damages, liabilities or proceedings made or brought by the counterparty alleging a breach of the
contract, to the extent that such breach is alleged to relate to an act or omission after the date hereof. 

        Elan
warrants as of the date hereof that, to the best of its knowledge, other than the Clinical Trials, no clinical trials are being conducted in the Territory with respect to the
OT-fentanyl Products, and Elan has had no discussions with any third party regarding any clinical trials that could without further action by Anesta reasonably result in a binding
agreement to conduct such clinical trials. 

        Anesta
shall not acquire any rights in respect of any other agreements entered into between Elan and any third party concerning the OT-fentanyl Products (the "Third Party
Contracts") and Elan shall remain solely responsible for the performance of Elan's obligations under the Third Party Contracts. Subject to Section 10.7 of the Agreement as amended, Anesta shall
be solely responsible for entering into its own arrangements with regard to the OT-fentanyl Products following the Repurchase Date. 

        E.
This Amendment is without prejudice to any accrued rights and obligations of the Parties prior to the date hereof, provided that the Parties agree that all unfulfilled orders for
OT-fentanyl products are hereby cancelled and are of no further effect. 

        F.
It is hereby acknowledged for the avoidance of doubt that the period of the covenant given in Section 3.6(a) of the Agreement shall expire one year after the Repurchase Date. 

        G.
Except as amended hereby by this Amendment, the Agreement shall remain unmodified and in full force and effect. 

        H.
This Amendment may be executed in any number of counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. 

        I.
Subject to Section J, no announcement or public statement concerning the existence, subject matter or any term of this Agreement, or its performance, shall be made by or on
behalf of any party 

10

 

without the prior written approval of the other, such approval not to be unreasonably withheld or delayed. 

        J.
A party (the "Disclosing Party") will be entitled to make an announcement or public statement or to disclose Confidential Information
that the Disclosing Party is required to make or disclose pursuant to a valid order of a court or Governmental Authority or any other requirement of law or any securities or stock exchange; provided
that if the Disclosing Party becomes legally required to make such announcement, public statement or disclosure hereunder, the Disclosing Party shall give the other party prompt notice of such fact to
enable that other party to seek a protective order or other appropriate remedy concerning any such announcement, public statement or disclosure, including confidential treatment and/or appropriate
redactions. The Disclosing Party shall fully co-operate with the other party in connection with that other party's efforts to obtain any such order or other remedy. If any such order or
other remedy does not fully preclude announcement, public statement or disclosure, the Disclosing Party shall make such announcement, public statement or disclosure only to the extent that the same is
legally required. 

        K.
The following provisions of the Agreement shall apply to this Amendment mutatis mutandis: Section 12.3(a) (Representation And Warranty As To Corporate Power);
Section 12.3(b) (Representation And Warranty As To Due Authorization And Enforceability); and Article 13 (Miscellaneous) as amended, other than Sections 13.12 (U.S. DEA Compliance) 

[signatures
begin on next page] 

11

        IN WITNESS WHEREOF, the Parties hereto have duly executed this Agreement as of the date first written above. 

	 	 	ANESTA CORP.
	

 	
 	
By:	

/s/  J. KEVIN BUCHI      
 Name: J. Kevin Buchi

Title: Vice President and Treasurer

Date: October 2, 2002
	

 	
 	
ELAN PHARMA INTERNATIONAL LIMITED
	

 	
 	
By:	

/s/  KEVIN INSLEY      
 Name: Kevin Insley

Title: Authorized Signatory

Date: October 2, 2002

QuickLinks

EXHIBIT 10.1

INTELLECTUAL PROPERTY SALE, AMENDMENT AND TERMINATION AGREEMENT

Recitals

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