Document:

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FINAL CONFORMED COPY WITH HANDWRITTEN INSERTS MARKED IN BOLD ITALIC

                 Confidential Treatment Requested As To Certain
                      Information Contained In This Exhibit

                COLLABORATIVE RESEARCH AND DEVELOPMENT AGREEMENT

This COLLABORATIVE RESEARCH AGREEMENT ("Agreement") is entered into as of
December 1, 2000 by and between PFIZER INC and its Affiliates ("Pfizer"), a
Delaware corporation, having an office at 235 East 42nd Street, New York, New
York 10017, and Megan Health, Inc. ("Megan"), a Delaware corporation, having an
office at 3655 Vista Ave., St;

WHEREAS, Megan has expertise in vaccine technology; and

WHEREAS, Pfizer has the capability to undertake research for the discovery and
evaluation of agents for treatment of disease and also the capability for
clinical analysis, manufacturing and marketing with respect to therapeutic and
vaccine agents; and

WHEREAS, Pfizer and Megan enter into this Agreement to discover and develop
animal vaccines and therapeutic agents; and

WHEREAS, Pfizer and Megan enter into a License and Royalty Agreement of equal
date with this Agreement with regard to certain patents and patent applications
owned by Megan,

NOW, THEREFORE, the parties agree as follows:

1.       DEFINITIONS. Whenever used in this Agreement, the terms defined in this
Section 1 shall have the meanings specified in this Section.

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         1.1   "AFFILIATE" means any corporation or other legal entity owning,
directly or indirectly, fifty percent (50%) or more of the voting capital shares
or similar voting securities of Pfizer or Megan; any corporation or other legal
entity fifty percent (50%) or more of the voting capital shares or similar
voting rights of which is owned, directly or indirectly, by Pfizer or Megan or
any corporation or other legal entity fifty percent (50%) or more of the voting
capital shares or similar voting rights of which is owned, directly or
indirectly, by a corporation or other legal entity which owns, directly or
indirectly, fifty percent (50%) or more of the voting capital shares or similar
voting securities of Pfizer or Megan. 1.2 "Commitment Year" means a twelve-month
period commencing on the Effective Date and each anniversary of the Effective
Date thereafter.

         1.3   "CONFIDENTIAL INFORMATION" means any and all information about
any element of a party's Technology or Program Technology which is disclosed by
such party ("Disclosing Party) to the other (Receiving Party) and either
designated "Confidential" in writing by the Disclosing Party at the time of
disclosure or, if orally or otherwise disclosed, confirmed within thirty (30)
days following disclosure. Confidential Information shall not include
information that, as of the date of such disclosure, is (i) known to the
Receiving Party other than through a prior confidential disclosure to the
Receiving Party by the Disclosing Party; or (ii) disclosed in published
literature, or otherwise generally known to the public through no fault or
omission of the receiving party; or (iii) obtained from a third party free from
any obligation of confidentiality to the disclosing party.

         1.4   "CONTRACT PERIOD" means the period beginning on the Effective
Date and ending on the date on which this Agreement terminates.

         1.5   "EFFECTIVE DATE" is DECEMBER 1, 2000.

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         1.6   "AREA" means research, development and commercialization with
respect to *** Confidential Treatment Requested as to this information *** as
further described in the Research Plan.

         1.7   "FTE" means full-time equivalent.

         1.8   "LICENSE AGREEMENT" shall mean the License and Royalty Agreement
between the parties of even date with this Agreement.

         1.9   "PATENT RIGHTS"

                    (a) the patents and patent applications listed in Exhibit A
of the License Agreement, and patents issuing on them, including any divisional,
continuation, continuation-in-part, renewal, extension, reexamination, reissue
or foreign counterpart of such patents and patent applications; and

                    (b) all patent rights in and to inventions *** Confidential
Treatment Requested as to this information *** including all the Valid Claims of
patent applications, whether domestic or foreign, claiming such patentable
inventions, including all continuations, continuations-in-part, divisions, and
renewals, all letters patent granted thereon, and all reissues, reexaminations
and extensions thereof.

         1.10   "PRODUCT" means any *** Confidential Treatment Requested as to
this information *** the manufacture, use, sale, offer for sale or import of
which would infringe any Valid Claim within Patent Rights in the absence of a
license.

         1.11   " RESEARCH PLAN" means the written plan describing the research
and development in the Area to be carried out by Pfizer and Megan pursuant to
this Agreement. Each annual Research Plan will be attached to and made a part of
this Agreement as Exhibit A.

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         1.12   "RESEARCH PROGRAM" means the collaborative research program in
the Area conducted by Pfizer and Megan pursuant to the Research Plan.

         1.13   "RESERVED RIGHTS" means any of the following: (a) the
exclusive rights granted by Megan to Boehringer Ingelheim, including the
right to grant sublicenses, to manufacture, use, sell, offer for sale and
import vaccines and therapeutics for horses (the "Equine License"); (b) rights
relating to Megan-Registered Trademark- Vac I, Megan-Registered Trademark- Egg
and Megan-Registered Trademark- Vac II, AntiPath, as they now exist and as set
forth in Exhibit B to the License Agreement; and (c) applicability of Program
Technology and Patent Rights to human vaccines and human therapeutic agents.

         1.14   "TECHNOLOGY" means and includes all materials, technology,
technical information, know-how, expertise and trade secrets in the Area .

                1.14.1  "MEGAN TECHNOLOGY" means Technology that is or was
developed by employees of or consultants to Megan alone or jointly with third
parties prior to the Effective Date, but, in the case of consultants or third
parties, only to the extent Megan has the right to grant rights to such
Technology.

                1.14.2   "PROGRAM TECHNOLOGY" means Technology that is or was
developed in the course of performing the Research Program by employees of or
consultants to Pfizer or Megan solely or jointly with each other.

                1.14.3   "PFIZER TECHNOLOGY" means Technology that is or was
developed by employees of or consultants to Pfizer alone or jointly with third
parties prior to the Effective Date, but, in the case of consultants or third
parties, only to the extent Pfizer has the right to grant rights to such
Technology.

         1.15   "VALID CLAIM" means a claim within Patent Rights so long as such
claim shall not have been disclaimed by Pfizer (in the case of Patent Rights
within the Pfizer Technology) or by Megan (in the case of Patent Rights within
the Megan Technology)

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or both (in the case of Patent Rights within the Program Technology) and shall
not have been held invalid in a final decision rendered by a tribunal of
competent jurisdiction from which no appeal has been or can be taken.

2.       COLLABORATIVE RESEARCH PROGRAM

         2.1    PURPOSE. Megan and Pfizer shall conduct the Research Program
throughout the Contract Period. All Technology in the Area developed in the
course of performing the Research Plan will become part of the Program
Technology. The objective of the Research Program is to discover and develop
Products.

         2.2    RESEARCH PLAN. The Research Plan shall be attached as Exhibit A
within sixty (60) days of the Effective Date. For each Commitment Year after the
first, the Annual Research Plan shall be prepared by the Research Committee for
submission to and approval by Pfizer and Megan no later than ninety (90) days
before the end of the prior Commitment Year. The parties expect that Megan's
primary responsibility will be the construction of live, genetically attenuated
recombinants to be used in SALMONELLA-vectored animal vaccines together with
limited immunogenicity testing and Pfizer's primary responsibility will be to
develop vaccines based on such constructs.

         2.3    EXCLUSIVITY. *** Confidential Treatment Requested as to this
information ***

         2.4    RESEARCH COMMITTEE.

                2.4.1  PURPOSE. Pfizer and Megan shall establish a Research
Committee (the "Research Committee"). The functions of the Research Committee
shall be:

                       (a) to prepare the Research Plan, and any amendments;

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                       (b) to review and evaluate progress under the Research
Plan;

                       (c) to coordinate and monitor publication of research
results obtained from the Research Program as specified in Section 4.2; and

                       (d) to coordinate and monitor the exchange of information
and materials that relate to the Research Program.

                The functions detailed in (c) and (d) shall survive termination
of this Agreement.

                2.4.2  MEMBERSHIP. Pfizer and Megan each shall appoint, in its
sole discretion, four members to the Research Committee. Substitutes may be
appointed at any time by written notice to the other party.

         The members initially shall be:

         Pfizer Appointees:           Everett Rosey (Chair)
                                      Tonia Agin
                                      Dennis Foss
                                      Robert Ankenbauer

         Megan Appointees:            Kevin Killeen
                                      Steve Tinge
                                      Donata Sizemore
                                      Ken Roland

                2.4.3  CHAIR. The Research Committee shall be chaired by ***
Confidential Treatment Requested as to this information ***

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                2.4.4  MEETINGS. The Research Committee shall meet at least
quarterly, at places selected by each party in turn and on dates mutually agreed
by the parties. The location of the first meeting of the Research Committee
shall be at Pfizer's election. Representatives of Pfizer or Megan or both, in
addition to members of the Research Committee, may attend such meetings at the
invitation of either party.

                2.4.5 Minutes. The Research Committee shall keep accurate
minutes of its deliberations which record all proposed decisions and all
actions recommended or taken. Drafts of the minutes shall be delivered to all
Research Committee members within five (5) business days after each meeting.
The party selecting the location for the meeting shall be responsible for the
preparation and circulation of the draft minutes.

                2.4.6 Decisions. All issues related to the Research Program
shall be discussed by the Research Committee members. *** Confidential
Treatment Requested as to this information ***

                2.4.7  EXPENSES. Pfizer and Megan shall each respectively bear
all expenses, including reasonable travel, related to the participation of their
designated members of the Research Committee.

         2.5   REPORTS AND MATERIALS.

                2.5.1  REPORTS. During the Contract Period, Pfizer and Megan
each shall furnish to the Research Committee:

                       (a) summary written reports within fifteen (15) days
after the end of each stage of the Research Plan, commencing on the Effective
Date, describing the progress under the Research Plan; and

                       (b) comprehensive written reports within thirty (30) days
after the end of each contract year, describing in detail the work accomplished
by it under the Research Plan during the year and discussing and evaluating the
results of such work.

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                2.5.2  MATERIALS. Megan and Pfizer shall, during the Contract
Period, as a matter of course as described in the Research Plan, or upon each
other's written or oral request, as the parties may reasonably agree, furnish to
each other samples of biochemical, biological or synthetic chemical materials
which are part of Pfizer Technology, Megan Technology or Program Technology and
which are necessary for each party to carry out its responsibilities under the
Research Plan; provided, however, that Megan shall, upon request, deliver to
Pfizer samples of any material made pursuant to the Research Plan. To the extent
that Pfizer requests and Megan provides quantities of materials in excess of the
quantities required to do pre-clinical proof of principle experiments, Pfizer
shall reimburse Megan for the reasonable costs of such materials.

         2.6   LABORATORY FACILITIES AND PERSONNEL. Megan and Pfizer shall
provide suitable laboratory facilities, equipment and personnel for the work to
be done by each party in carrying out the Research Program. *** Confidential
Treatment Requested as to this information ***

         2.7   DILIGENT EFFORTS. Pfizer and Megan each shall use ***
Confidential Treatment Requested as to this information *** efforts to achieve
the objectives of the Research Program. Megan and Pfizer will use reasonably
diligent efforts to achieve the objectives listed in the Research Plan, and
Pfizer will use reasonably diligent efforts to assist Megan in the Research
Plan.

3.       PAYMENTS.

         3.1  RESEARCH PROGRAM FUNDING. Pfizer will fund the research to be
performed by Megan, pursuant to this Agreement, according to the following
schedule:

*** Confidential Treatment Requested as to this information ***

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The funding payments are expected to support the work of *** Confidential
Treatment Requested as to this information ***

                3.1.1  All funding payments shall be made quarterly in advance
for work scheduled to be performed by Megan during any three (3) month period,
against Megan's invoice for such three (3) month period. At the end of each
three (3) month period, Megan shall make adjustments as necessary to reflect the
personnel actually assigned and the work actually performed by Megan and such
adjustments shall be reflected in Megan's invoice for the next three (3) month
period; provided, however, that in each Commitment Year Megan shall be assigned
sufficient work to be performed by *** Confidential Treatment Requested as to
this information ***. Both parties understand that all payments pursuant to this
Section are noncreditable and nonrefundable.

                3.1.2  The amount of the funding payment for each quarter shall
be based on the personnel assigned calculated on an FTE basis; provided,
however, that the aggregate amount of funding payments made in any Commitment
Year shall not exceed the Annual Commitment listed above for such Commitment
Year.

         3.3  US FUNDS. Each payment pursuant to this Agreement shall be paid by
Pfizer in U.S. currency by wire transfer in immediately available funds to an
account designated by Megan, or by other mutually acceptable means within thirty
(30) days after receipt by Pfizer of the invoice from Megan consistent with this
Section 3.

         3.4  RECORDS. Megan shall keep for three (3) years from the conclusion
of each year complete and accurate records of its expenditures of efforts from
payments received by it from Pfizer under Section 3.1. The records shall conform
to good accounting principles as applied to a similar company similarly
situated. Pfizer shall have the right at its own expense during the term of this
Agreement and during the subsequent three-year period to appoint an independent
certified public accountant

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reasonably acceptable to Megan to inspect said records to verify the accuracy of
such expenditures of efforts, pursuant to each Research Plan. Upon reasonable
notice by Pfizer, Megan shall make its records available for inspection by the
independent certified public accountant during regular business hours at the
place or places where such records are customarily kept, to verify the accuracy
of the expenditures of efforts. This right of inspection shall not be exercised
more than once in any calendar year and not more than once with respect to
records covering any specific period of time. All information concerning such
expenditures of efforts, and all information learned in the course of any audit
or inspection, shall be deemed to be Megan Confidential Information, except to
the extent that it is necessary for Pfizer to reveal the information in order to
enforce any rights it may have pursuant to this Agreement or if disclosure is
required by law. The failure of Pfizer to request verification of any
expenditures of efforts before or during the three-year period shall be
considered acceptance by Pfizer of the accuracy of such expenditures of efforts,
and Megan shall have no obligation to maintain any records pertaining to such
report or statement beyond such three-year period. The findings of such
inspection, if any, shall be binding on the parties.

4.       TREATMENT OF CONFIDENTIAL INFORMATION

         4.1    CONFIDENTIALITY

                4.1.1 Pfizer and Megan each recognize that the other's
Confidential Information constitutes highly valuable, confidential information.
Subject to the terms and conditions of the License Agreement, the obligations
set forth in Section 4.3 and the publication rights set forth in Section 4.2,
Pfizer and Megan each agree that during the term of this Agreement and for five
(5) years thereafter, it will keep confidential, and will cause its Affiliates
and sublicensees to keep confidential, all Megan Confidential Information or
Pfizer Confidential Information, as the case may be, that is disclosed to it, or
to any of its Affiliates or sublicensees pursuant to this Agreement. Neither
Pfizer nor Megan nor any of their respective Affiliates or sublicensees shall
use such

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Confidential Information of the other party except as expressly permitted in
this Agreement. For the purposes of this Section 4, it is understood that
Program Technology shall be deemed Confidential Information of both parties.

                4.1.2 Pfizer and Megan each agree that any disclosure of the
other's Confidential Information to any officer, employee or agent of the other
party or of any of its Affiliates shall be made only if and to the extent
necessary to carry out its responsibilities under this Agreement and shall be
limited to the maximum extent possible consistent with such responsibilities.
Pfizer and Megan each agree not to disclose the other's Confidential Information
to any third parties under any circumstance without written permission from the
other party. Each party shall take such action, and shall cause its Affiliates
and sublicensees to take such action, to preserve the confidentiality of each
other's Confidential Information as it would customarily take to preserve the
confidentiality of its own Confidential Information. Each party, upon the
other's request, will return all the Confidential Information disclosed to it by
the other party pursuant to this Agreement, including all copies and extracts of
documents, within sixty (60) days of the request upon the termination of this
Agreement except for one (1) copy which may be kept for the purpose of complying
with continuing obligations under this Agreement.

                4.1.3 Megan and Pfizer each represent that all of its employees,
and any consultants to such party, participating in the Research Program who
shall have access to Program Technology, the Technology of the other (Pfizer
Technology or Megan Technology, as the case may be) or Confidential Information
of the other (Pfizer Confidential Information or Megan Confidential Information,
as the case may be) are bound by agreement to maintain such information in
confidence.

         4.2    PUBLICATION. Notwithstanding any matter set forth with
particularity in this Agreement to the contrary, results obtained in the course
of the Research Program may be submitted for publication following scientific
review by the Research Committee and subsequent written approval by Megan's and
Pfizer's managements, which approval

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shall not be unreasonably withheld. After receipt of the proposed publication by
both Pfizer's and Megan's managements, such managements shall provide written
approval or disapproval (i) within thirty (30) days for a manuscript; (ii)
within fourteen (14) days for an abstract for presentation at, or inclusion in
the proceedings of, a scientific meeting; or (iii) within fourteen (14) days for
presentation materials to be used at a scientific meeting.

         4.3    PUBLICITY. Except as required by law, neither party may disclose
the terms of this Agreement nor the research described in it without the written
consent of the other party.

         4.4    PERMITTED DISCLOSURE.

                4.4.1 DISCLOSURE REQUIRED BY LAW. If either party is requested
to disclose the other party's Confidential Information in connection with a
legal or administrative proceeding or is otherwise required by law to disclose
the other party's Confidential Information, such party will give the other party
prompt notice of such request. The Disclosing Party may seek an appropriate
protective order or other remedy or waive compliance with the provisions of this
Agreement. If the Disclosing Party seeks a protective order or other remedy, the
Receiving Party will cooperate. If the Disclosing Party fails to obtain a
protective order or waive compliance with the relevant provisions of this
Agreement, the Receiving Party will disclose only that portion of Confidential
Information which its legal counsel determines it is required to disclose.

                4.4.2 DISCLOSURE OF INVENTIONS. Each party shall promptly inform
the other about all inventions in the Area within the Program Technology that
are made in the course of carrying out the Research Program by employees of, or
consultants to, either of them solely, or jointly with employees of, or
consultants to, the other.

         4.5    RESTRICTIONS ON TRANSFERRING MATERIALS. Megan and Pfizer
recognize that the biological, biochemical and chemical materials which are part
of Program

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Technology represent valuable commercial assets. Therefore, throughout the
Contract Period and for five (5) years thereafter, Megan agrees not to transfer
such materials to any third party for use in the Area, unless prior written
consent for any such transfer is obtained from Pfizer; and Pfizer agrees not to
transfer such materials to any third party for use outside the Area, unless
prior written consent for any such transfer is obtained from Megan.

5.       INTELLECTUAL PROPERTY RIGHTS. The following provisions relate to
intellectual property rights in the Program Technology.

         5.1    OWNERSHIP. *** Confidential Treatment Requested as to this
information ***

         5.2    The filing, prosecution and maintenance of Patent Rights is set
forth in the License Agreement.

         5.3    Pfizer and Megan each grant to the other an irrevocable,
royalty-free, non-exclusive, world-wide license to manufacture and use Patent
Rights and Program Technology for all research purposes.

6.       ACQUISITION OF RIGHTS FROM THIRD PARTIES.  During the Contract Period,
Megan and Pfizer shall each promptly notify each other of any appropriate
opportunities to acquire in any manner from third parties, technology, patents
or information which it proposes to use in the course of performing the Research
Program. Megan and Pfizer shall decide if such rights should be acquired in
connection with the Research Program and, if so, whether by Megan, Pfizer or
both, it being understood that nothing herein shall obligate either party to
obtain such rights or, if it does acquire such rights, to make such rights
available for use in the Research Program. If acquired, such rights shall become
part of the Confidential Information, Technology or Patent Rights, whichever is
appropriate, of the acquiring party or Program Technology, as the case may be.

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7.       OTHER AGREEMENTS. Concurrent with the execution of this Agreement,
Megan and Pfizer shall enter into the License Agreement and Stock Purchase
Agreement of even date. This Agreement, the Stock Purchase Agreement and the
License Agreement are the sole agreements with respect to the subject matter and
supersede all other prior or contemporaneous agreements and understandings,
written or oral, between the parties with respect to same.

8.       TERM, TERMINATION AND DISENGAGEMENT.

         8.1    TERM. Unless sooner terminated, as provided below, or extended,
by mutual agreement of the parties, this Agreement shall expire *** Confidential
Treatment Requested as to this information *** years from the Effective Date.

         8.2    EVENTS OF TERMINATION. The following events shall constitute
events of termination ("Events of Termination"):

                       (a) if any written representation or warranty made by
Megan or Pfizer, or any of its officers, under or in connection with this
Agreement shall prove to have been incorrect in any material respect when made;

                       (b) Megan or Pfizer shall fail in any material respect to
perform or observe any term, covenant or understanding contained in this
Agreement or in any of the other documents or instruments delivered pursuant to,
or concurrently with, this Agreement, and any such failure shall remain
unremedied for thirty (30) days after written notice to the failing party.

         8.3     TERMINATION.

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                8.3.1  UPON EVENT OF TERMINATION BY PFIZER OR MEGAN. Upon the
occurrence of any Event of Termination, the party not responsible may, by
written notice to the other party, terminate this Agreement.

                8.3.2  If either party terminates this Agreement pursuant to
Section 8.3.1, the License Agreement shall not terminate, but instead shall
terminate or expire in accordance with its terms.

         8.4    TERMINATION BY PFIZER. Within ninety (90) days preceding the end
of the first Commitment Year, Pfizer may terminate this Agreement, with or
without cause, by delivering written notice of termination to Megan. If Pfizer
terminates this Agreement pursuant to this Section, it will make all funding
payments which would have otherwise been due through the first Commitment Year.
Pfizer will retain all rights and obligations as set forth in the License
Agreement.

         8.5    Termination of this Agreement by either party, with or without
cause, will not terminate the licenses granted pursuant to Section 5.3.

         8.6    Termination of this Agreement for any reason shall be without
prejudice to:

                       (a) the rights and obligations of the parties provided in
Sections 4, 5, and 11 and any Sections which provide by its terms performance by
either party subsequent to termination;

                       (b) Megan's right to receive all payments accrued under
                           Section 3; or

                       (c) any other remedies which either party may otherwise
                           have.

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9.       REPRESENTATIONS AND WARRANTIES. Megan and Pfizer each represents and
warrants as follows:

         9.1 It is a corporation duly organized, validly existing and is in good
standing under the laws of the State of Delaware; is qualified to do business
and is in good standing as a foreign corporation in each jurisdiction in which
the conduct of its business or the ownership of its properties requires such
qualification; and it has all requisite power and authority, corporate or
otherwise, to conduct its business as now being conducted, to own, lease and
operate its properties and to execute, deliver and perform this Agreement.

         9.2 The execution, delivery and performance by it of this Agreement
have been duly authorized by all necessary corporate action and do not and will
not (a) require any consent or approval of its stockholders beyond the approvals
already obtained; (b) violate any provision of any law, rule, regulations,
order, writ, judgment, injunction, decree, determination or award presently in
effect having applicability to it or any provision of its certificate of
incorporation or by-laws; or (c) result in a breach of or constitute a default
under any material agreement, mortgage, lease, license, permit or other
instrument or obligation to which it is a party or by which it or its properties
may be bound or affected.

         9.3 This Agreement is a legal, valid and binding obligation of it
enforceable against it in accordance with its terms and conditions, except as
such enforceability may be limited by applicable bankruptcy, insolvency,
moratorium, reorganization or similar laws, from time to time in effect,
affecting creditor's rights generally.

         9.4 It is not under any obligation to any person, or entity,
contractual or otherwise, that is conflicting or inconsistent in any respect
with the terms of this Agreement or that would impede the diligent and complete
fulfillment of its obligations.

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         9.5 It has good and marketable title to or valid leases or licenses
for, all of its properties, rights and assets necessary for the fulfillment of
its responsibilities under the Research Program, subject to no claim of any
third party other than any relevant lessors or licensors.

10.      COVENANTS OF MEGAN AND PFIZER OTHER THAN REPORTING REQUIREMENTS.
Throughout the Contract Period, Megan and Pfizer each shall:

         10.1 maintain and preserve its corporate existence, rights, franchises
and privileges in the jurisdiction of its incorporation, and qualify and remain
qualified as a foreign corporation in good standing in each jurisdiction in
which such qualification is from time to time necessary or desirable in view of
their business and operations or the ownership of their properties.

         10.2 comply in all material respects with the requirements of all
applicable laws, rules, regulations and orders of any government authority to
the extent necessary to conduct the Research Program, except for those laws,
rules, regulations, and orders it may be contesting in good faith.

11.      INDEMNIFICATION. Pfizer and Megan will indemnify, defend and hold each
other harmless for any and all damages, settlements, costs, legal fees and other
expenses incurred in connection with a claim by a third party against either
party based on any action or omission of the indemnifying party's agents,
employees, or officers related to its obligations under this Agreement;
provided, however, that the foregoing shall not apply (i) if the claim is found
to be based upon the negligence, recklessness or willful misconduct of the party
seeking indemnification; or (ii) if such party fails to give the other party
prompt notice of any claim it receives and such failure materially prejudices
the other party with respect to any claim or action to which its obligation
pursuant to this Section applies. Notwithstanding the foregoing, Pfizer hereby
expressly agrees to

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indemnify, defend and hold harmless Megan (and all officers, directors, agents
and Affiliates of Megan) for any and all claims arising from clinical trials
pursued by Pfizer or its Affiliates and/or sublicensees, the use, manufacture,
sale or offer to sell of Products, and/or the exercise of rights granted to
Pfizer under Section 5.3 or the License Agreement (including without limitation
product liability claims). The indemnifying party, in its sole discretion, shall
choose legal counsel, shall control the defense of such claim or action and
shall have the right to settle same on such terms and conditions it deems
advisable.

12.     NOTICES. All notices shall be in writing mailed via certified mail,
return receipt requested, courier, or facsimile transmission addressed as
follow, or to such other address as may be designated from time to time:

        If to Pfizer:           To Pfizer at its address as set forth at the
                                beginning of this Agreement, Attention: Senior
                                Vice President, Pfizer Global Research and
                                Development.

        With copy to:           Assistant General Counsel, Pfizer Global
                                Research and Development

        If to Megan:            To Megan at its address as set forth at the
                                beginning of this Agreement, Attention:
                                President, Megan Health, Inc.

        With copy to:           Una Ryan, CEO
                                AVANT Immunotherapeutics, Inc.
                                119 Fourth Avenue
                                Needham, MA 02494

Notices shall be deemed given as of the date received at the above specified
address.

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13.      GOVERNING LAW. This Agreement shall be governed by and construed in
accordance with the laws of the State of New York, without regard to its
conflicts of law provisions.

14.      MISCELLANEOUS.

         14.1  BINDING EFFECT. This Agreement shall be binding upon and inure to
the benefit of the parties and their respective legal representatives,
successors and permitted assigns.

         14.2  HEADINGS. Paragraph headings are inserted for convenience of
reference only and do not form a part of this Agreement.

         14.3  COUNTERPARTS. This Agreement may be executed simultaneously in
two or more counterparts, each of which shall be deemed an original. Signatures
may be transmitted via facsimile, thereby constituting the valid signature and
delivery of this Agreement.

         14.4  AMENDMENT, WAIVER. This Agreement may be amended, modified,
superseded or canceled, and any of the terms may be waived, only by a written
instrument executed by each party or, in the case of waiver, by the party or
parties waiving compliance. The delay or failure of any party at any time or
times to require performance of any provisions shall in no manner affect the
rights at a later time to enforce the same. No waiver by any party of any
condition or of the breach of any term contained in this Agreement, whether by
conduct, or otherwise, in any one or more instances, shall be deemed to be, or
considered as, a further or continuing waiver of any such condition or of the
breach of such term or any other term of this Agreement.

         14.5  NO THIRD PARTY BENEFICIARIES. No third party including any
employee of any party to this Agreement, shall have or acquire any rights by
reason of this

<PAGE>

                                       20

Agreement. Nothing contained in this Agreement shall be deemed to constitute the
parties partners with each other or any third party.

         14.6  ASSIGNMENT AND SUCCESSORS. This Agreement may not be assigned by
either party , except that each party may assign this Agreement and the rights
and interests of such party, in whole or in part, to any of its Affiliates, any
purchaser of all or substantially all of its assets or to any successor
corporation resulting from any merger or consolidation of such party with or
into such corporations.

         14.7  FORCE MAJEURE. Neither Pfizer nor Megan shall be liable for
failure of or delay in performing obligations set forth in this Agreement, and
neither shall be deemed in breach of its obligations, if such failure or delay
is due to natural disasters or any causes reasonably beyond the control of
Pfizer or Megan.

         14.8  SEVERABILITY. If any provision of this Agreement is or becomes
invalid or is ruled invalid by any court of competent jurisdiction or is deemed
unenforceable, it is the intention of the parties that the remainder of the
Agreement shall not be affected so long as the essential benefits of this
Agreement remain enforceable and obtainable.

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by
their duly authorized representatives.

PFIZER INC                                    MEGAN HEALTH, INC.

By:   /S/ GEORGE M. MILNE, JR.                By:   UNA S. RYAN
   -------------------------------               -------------------------------

Name:  GEORGE M, MILNE, JR.                   Name:  UNA S. RYAN
     -----------------------------                 -----------------------------

Title:   SR. VICE PRESIDENT                   Title:  PRESIDENT
      ----------------------------                  ----------------------------

<PAGE>

                                       21

cc:    Pfizer Inc, Legal Division, Groton, CT 06340<PAGE>

                                                                   EXHIBIT 10.19

                     SECOND AMENDMENT TO SUBLEASE AGREEMENT

     Reference is made to that certain Sublease Agreement, dated as of March 31,
1998 (the "Sublease") by and between the Sublandlord and Subtenant (as such
parties are identified below) for premises at the property commonly known as 201
Spring Street, Lexington, Massachusetts. This Second Amendment to Sublease
Agreement (this "Second Amendment") is entered into as of June 27, 2000 between
Sublandlord and Subtenant. For valuable consideration, Sublandlord and Subtenant
agree that:

     1.   DEFINITIONS. In this Second Amendment the following terms have the
          meanings given to them.

          (a)  Sublandlord: MediaOne of Delaware, Inc., a Delaware corporation.

          (b)  Subtenant: Segue Software, Inc., a Delaware corporation.

          (c)  Sublease: Sublease Agreement, dated March 31, 1998, between
               Sublandlord and Subtenant; as amended by that First Amendment to
               Sublease, dated effective July 15, 1998.

          (d)  Original Premises: The Subleased Premises, as defined in the
               Sublease.

          (e)  Third Expansion Space: 5,800 rentable square feet located in the
               lower level or garden level of the Building, as shown on EXHIBIT
               A-1 to this Second Amendment.

          (f)  Building Address:      201 Spring Street
                                      Lexington, Massachusetts

          (g)  Effective Date: July 1, 2000

          (h)  Third Expansion Space Rent Commencement Date: October 1, 2000.

Any capitalized term used in this Second Amendment but not defined in this
Second Amendment has the meaning given for such term in the Lease.

     2. AMENDMENT TO SECTION 1. As of the Effective Date, the Third Expansion
Space shall become a part of the Subleased Premises. The aggregate rent payable
for the time period between the Effective Date and the Third Expansion Space
Rent Commencement Date (i.e. $33,350) shall be amortized based upon a per annum
interest rate of 10%, beginning on the Third Expansion Space Rent Commencement
Date and ending on the Expiration Date. The Monthly Rent set forth in subsection
(i) below includes such amortization. Therefore, as of the Effective Date, the
subsections of Section 1 set forth below are amended in their entirety to read
as follows:

          (d)  SUBLEASED PREMISES: The Initial Subleased Premises, First
               Expansion Space, the Second Expansion Space, and the Third
               Expansion Space, located on the first and second floors and the
               lower level (also known as garden level) of the Building, along
               with the appurtenant right to use common facilities as set forth
               in Section 2.2 of the Master Lease. The Initial Subleased
               Premises, the First Expansion Space, and the Second Expansion
               Space will be occupied by Subtenant in accordance with the
               Occupancy Schedule attached to this Sublease as EXHIBIT B, and
               the Third Expansion Space will be occupied by Subtenant July 1,
               2000.

          ****

          (l)  MONTHLY RENT: Payment of Rent shall begin as of the Commencement
               Date. The schedule below reflects the Monthly Rent payable
               (subject to waiver pursuant to Sections 3(e) and 3(l) of this
               Lease).

<PAGE>

               TIME PERIOD                         MONTHLY RENT

               8/1/98 - 12/31/98                     $104,625.00
               1/1/99 - 6/30/99                      $135,625.00
               7/1/99 - 9/30/00                      $174,375.00
               10/1/00 - 6/30/03                     $186,037.83
               7/1/03 - 6/30/05                      $191,667.83
               7/1/05 - 10/31/07                     $192,146.17

               ****

          (k)  RENTABLE AREA OF THE SUBLEASED PREMISES:

               8/1/98 - 12/31/98                   40,500 square feet
               1/1/99 - 6/30/99                    52,500 square feet
               7/1/99 - 6/30/00                    67,500 square feet
               7/1/00 - 10/31/07                   73,300 square feet

               ****

          (m)  OPERATING EXPENSES BASE:

               (1)  Original Premises, First Expansion Space and Second
                    Expansion Space: The actual Operating Expense for the 12
                    month period commencing on the Commencement Date, adjusted
                    pursuant to Section 5(c) below to reflect occupancy of 100%
                    of the Rentable Area of the Building.

               (2)  Third Expansion Space: The actual Operating Expenses for the
                    12 month period commencing on January 1, 2000, adjusted
                    pursuant to Section 5(c) below to reflect occupancy of 100%
                    of the Rentable Area of the Building.

          ****

          (n)  SUBTENANT'S SHARE:

               8/1/98 - 12/31/98                      39.512%
               1/1/99 - 6/30/99                       51.220%
               7/1/99 - 6/30/00                       65.853%
               7/1/00 - 10/31/07                      71.512%

               (determined by dividing the Rentable Area of the Subleased
               Premises by the Rentable Area of the Building and rounding to the
               nearest one thousandth of one percent)

          ****

          (o)  PARKING SPACES:

               8/1/98 - 12/31/98                       142
               1/1/99 - 6/30/99                        184
               7/1/99 - 6/30/00                        236
               7/1/00 - 10/31/07                       257

               All parking spaces are unassigned, non-reserved, and
               non-designated parking spaces in those surface parking lots made
               available to Sublandlord pursuant to the Master Lease.
               Subtenant's use of the Parking Spaces shall be in common with use
               by other tenants and Subtenants of the Building and

<PAGE>

               other buildings in the business park, and shall be subject to the
               parking rules and regulations referenced in Section 2.2.1 of the
               Master Lease.

     4. AMENDMENT TO EXHIBIT A. As of the Effective Date, EXHIBIT A-1 to this
Second Amendment shall be added to and become a part of EXHIBIT A to the
Sublease.

     5. TENANT FINISH ALLOWANCE FOR THIRD EXPANSION SPACE. As of the Effective
Date, Sublandlord shall provide Subtenant with an improvement allowance in an
amount equal to $25.00 per rentable square foot of the Third Expansion Space
($25 x 5,800 square feet = $145,000 total) (the "3E Allowance"). This amount
shall be paid by Sublandlord to Subtenant within 30 days after completion of the
improvements to the Third Expansion Space and Subtenant delivers to Sublandlord
invoices for design and construction work relating to the Third Expansion Space.
All improvements shall be constructed in accordance and consistent with the
requirements in the Master Lease for alterations and additions by the
Sublandlord (see Section 3.3 of the Master Lease). Subject to the approval of
the Master Landlord, it is anticipated that the tenant improvements to the Third
Expansion Space will be carried out by Subtenant's contractor. Any unused
portion of the 3E Allowance shall not be deemed a credit due Subtenant, or
otherwise applied to Rent under the Sublease.

     6. CONFIRMATION OF SUBLEASE. Sublandlord and Subtenant confirm and ratify
in all respects the terms and conditions of the Sublease, as amended by this
Second Amendment.

     7. BROKERS. With respect to this Second Amendment, Sublandlord's Broker is
Grubb & Ellis and Subtenant's Broker is McCall and Almy. Sublandlord and
Subtenant acknowledge that they have dealt with no other brokerage firms other
than those listed above. Sublandlord shall be responsible for paying all
brokerage commissions, pursuant to the terms of a separate agreement.

     Sublandlord and Subtenant have executed this Second Amendment on the date
first set forth above.

SUBLANDLORD:                                    SUBTENANT:

MEDIA ONE OF DELAWARE, INC.,                    SEGUE SOFTWARE, INC., a Delaware
a Delaware corporation                          corporation

By /s/ Thomas Wootten                           By  /s/ Gary Stickel
  ---------------------------------               ------------------------------
Name Thomas Wootten                             Name Gary Stickel
    -------------------------------                 ----------------------------
Title Director of Real Estate                   Title V.P. H.R. Admin.
     ------------------------------                  ---------------------------

Approved as to legal form by counsel to Sublandlord:
Fisher, Sweetbaum & Levin, P.C.

By /s/ Carlen T. Clark
  ---------------------
Date    6/30/00
    -------------------

STATE OF                    )
        --------------------
                            )ss.
COUNTY OF                   )
         -------------------

     The foregoing was acknowledged before me this________day of_______________,
200___, by
_________________________________as____________________________________________
______of_____________________.

WITNESS my hand and official seal.

                                                --------------------------------
                                                Notary Public

My commission expires
                     ---------------------------

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